RU2412915C2 - Method of producing shaped article, glass material and method of determining glass material and profile board shape - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to shaping process. Glass material is placed on the profile board so that, at least, three points on bottom surface of said material stay in contact with shaping surface while its central part is separated from shaping surface. For lens with gradual increase in focal power, three points on bottom surface represent two points on the side related to far focal power reference point and one point relates to near focal power reference point. For monofocal lens, the entire surface of glass material bottom surface should stay in contact with shaping surface. Glass material is heated to deformation temperature. Glass material represents glass with spherical bottom and top surfaces. Profile board represents an arbitrary shape profile board.

EFFECT: higher accuracy of shaping.

35 cl, 16 dwg

Description

Technical field

The present invention relates to a method for manufacturing a molded product by hot bending molding, to a glass material for use in a hot bending molding method, and to a method for determining a shape of its lower surface, and to a method for determining a shape of a forming surface of a template for use in a hot bending molding method.

State of the art

Methods for forming glass patterns for eyeglass lenses include applying mechanical grinding and polishing methods, mechanical grinding methods, and electrical processing methods, such as electric discharge treatment to produce a heat-resistant core template, bringing this core template into contact with a glass softened by heating to shape it the surface of the main template, the use of the grinding program for each surface shape that needs to be obtained, and movanie main mold having the appropriate surface shape.

In recent years, there has been an increased need for multifocal eyeglass lenses that are made thinner and lighter due to the introduction of an axially symmetric, aspherical lens design. A hot bend molding method has been proposed (see Japanese Unexamined Patent Publication (KOKAI) Heisei No. 6-130333 and 4-275930) as a method for forming patterns for manufacturing spectacle lenses having such complex shapes.

Description of the present invention

In the hot bend molding method, a glass material consisting of a thermoplastic material such as glass is placed on a template and softened by heating to a temperature above or equal to its softening point, causing it to come into close contact with the template. The shape of the template is thus transmitted to the upper surface of the glass material, to obtain a molded product with the desired surface shape. Thus, since the hot bend molding method is a molding method in which the upper surface of the glass material is formed indirectly without being brought into contact with the template, it is difficult to control the shape of the upper surface. In particular, a template having an aspherical surface shape is used to produce templates for multifocal eyeglass lenses. However, it is extremely difficult to convey such a complex shape with high accuracy of the upper surface of the glass material.

In addition, the shape of the optical surface of the spectacle lenses varies for different products, depending on the degree of curvature and the like. Thus, it is required to create a shape of the surface of the template for this product in order to obtain a template for lenses to form the desired optical surface. However, the shape of the glass material changes in a complex way when softened by heating. Thus, even when using a template having a forming surface that was designed to shape to the desired optical surface, it is difficult to mold the upper surface of the glass material with the desired shape. For this reason, in practice, when developing glass materials and templates, complex form corrections are performed, respectively, of glass materials and templates. In this way, the development of patterns and glass materials to obtain molded products of the desired shape is not an easy thing.

In such circumstances, it is an object of the present invention to provide a method for molding the upper surface of a glass material into a desired shape.

Another objective of the present invention is to provide a method for easily and easily determining the surface shape of a template and glass material for the production of molded products of the desired shape.

The authors of the present invention conducted extensive research to achieve the above goals, leading to the discovery that the above goals were achieved by thermal softening of the glass material, both the upper surface and the lower surface of which is spherical, on the forming surface with free-form surface forms other than spheres, with molding the upper surface of the glass material with an approximately offset surface relative to the forming surface of the template. The present invention has been developed on such a basis.

The present invention relates to:

a method for manufacturing a molded product, comprising molding the upper surface of the glass material that has been placed on the forming surface of the template to obtain a molded product by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into tight contact with the forming surface, in which

glass having upper and lower surfaces, which are spherical in shape, is used as glass material,

a template having a forming surface being a free-form surface other than a spherical surface is used as a template,

the upper surface of the glass material is molded with an approximately offset surface relative to the forming surface of the template.

In addition, the present invention relates to:

glass material for use in a molding method in which the upper surface of the glass material that has been placed on the forming surface of the template, the forming surface being a free-form surface other than a spherical surface, is formed with an approximately offset surface relative to the forming surface of the template to obtain a molded product by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into tight contact with the molds guide surface,

which has an upper and lower surface that are spherical in shape and also has substantially equal thickness in the normal direction.

In addition, the present invention relates to:

a method for determining the shape of the forming surface of the template for use in a molding method in which the upper surface of the glass material that has been placed on the forming surface of the template is molded into the desired shape to obtain a molded product by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into a dense contact with the forming surface in which

the forming surface is a free-form surface other than a spherical surface,

Assuming that the glass material has upper and lower surfaces that are spherical in shape and has substantially equal thickness in the normal direction, the shape of the forming surface is determined based on the desired shape of the upper surface and thickness in the normal direction of the glass material.

Moreover, the present invention relates to:

a method for manufacturing a molded product, comprising molding the upper surface of the glass material that has been placed on the forming surface of the template to obtain a molded product by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into tight contact with the forming surface, in which

glass material having upper and lower surfaces that are spherical in shape and also having substantially equal thickness in the normal direction is used as glass material,

a template having a forming surface, which is a free-form surface other than a spherical surface, and the forming surface of which was determined by the method for determining the shape of the forming surface of the present invention, is used as a template.

Further, the present invention relates to:

a method for determining the shape of the lower surface of the glass material for use in a molding method in which the upper surface of the glass material that has been placed on the forming surface of the template is molded into a desired shape to obtain a molded product by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into a dense contact with the forming surface in which

the forming surface is a free-form surface other than a spherical surface,

on the assumption that the glass material has upper and lower surfaces that are spherical in shape and has substantially equal thickness in the normal direction, the shape of the forming surface is determined based on the desired shape of the upper surface and the shape of the forming surface, which was determined based on the thickness of the glass material in the normal direction .

Moreover, the present invention relates to:

a method for determining the shape of the lower surface of the glass material for use in a molding method in which the upper surface of the glass material that has been placed on the forming surface of the template is molded into a desired shape to obtain a molded product by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into a dense contact with the forming surface in which

the molded product is a mold or part of a mold for a single-focal spectacle lens,

a spectacle lens is a lens with a gradual increase in optical power having one reference point for measuring far optical power and one reference point for measuring near optical power,

the forming surface is a free-form surface other than a spherical surface,

on the assumption that the glass material has upper and lower surfaces that are spherical in shape and has substantially equal thickness in the normal direction, the shape of the lower surface is defined as a surface having a spherical shape whose average curvature is approximately identical to the average curvature at the reference point for measurement far optical power of the lens with a gradual increase in optical power.

Moreover, the present invention relates to:

a method for manufacturing a molded product, comprising molding the upper surface of the glass material that has been placed on the forming surface of the template to obtain a molded product by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into tight contact with the forming surface, in which

a template having a forming surface that is a free-form surface other than a spherical surface is used as a template,

glass material having upper and lower surfaces that are spherical in shape and substantially equal in thickness in the normal direction, the shape of the lower surface of which was determined by the method for determining the lower surface of the present invention, is used as glass material.

The present invention allows the production of molded products of the desired shape with high accuracy by hot bending molding.

The present invention also allows an easy and simple determination of the surface shapes of patterns and glass materials used in the hot bend molding method.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described below in more detail.

A method of manufacturing a molded product of the present invention is a method of manufacturing a molded product, comprising molding the upper surface of the glass material, which was placed on the forming surface of the template to obtain a molded product by heating the glass material to a temperature that allows deformation to bring the lower surface of the glass material into tight contact with the forming surface in which glass having upper and lower surfaces that are spherical in shape is used in as glass material, a template having a forming surface that is a free-form surface other than a spherical surface is used as a template, and the upper surface of the glass material is formed with an approximately offset surface relative to the forming surface of the template.

In the method of manufacturing a molded product of the present invention, the upper surface of the glass material is formed with an approximately offset surface relative to the forming surface of the template. The term "offset surface relative to the forming surface of the template" means a surface for which the distance in the normal direction between this surface and the forming surface of the template is constant. Thus, ″ biased ″ clearly differs from the term ″ similar ″. The term “approximately offset surface” means that the main elements of a given surface shape of the template are offset, and cover surface shapes along with the correction and processing errors used to achieve other goals. That is, in the present invention, the upper surface of the glass material after molding and the forming surface of the template have an approximately biased ratio, whereby the space in the normal direction is approximately equal in all positions. The method of manufacturing molded products of the present invention allows the production of molded products of the desired shape with high accuracy using a template having a forming surface that is approximately offset from the desired shape of the upper surface of the glass material. In addition, by determining the surface shape (the shape of the upper surface of the glass material), which must be molded at the end, it is sufficient to construct a template with a forming surface that satisfies an approximately offset relation to this surface shape, providing a ready-made design of the forming surface. In addition, the advantage is that molded products with a complex surface shape, such as templates for multifocal eyeglass lenses, can be obtained from glass material having two spherical surfaces that are easy to process and design.

A glass material that has substantially equal thickness in the normal direction can be used in the present invention, thereby allowing the formation of an upper surface of the glass material with an approximately offset surface relative to the forming surface of the template. Here, the phrase ″ essentially equal thickness in the normal direction ″ means that at least in the geometric center of the glass material or in the optical center point containing the point for measuring far optical power, the degree of change in thickness measured in the normal direction is less than or equal to 1 , 0 percent, preferably less than or equal to 0.8 percent.

The shape of the glass material before being processed by thermal plasticization will be described below based on FIG. Figure 1 shows an example (sectional view) of glass that has substantially equal thickness in the normal direction.

In figure 1, the glass material 206 has a meniscus shape with concave and convex surfaces, the outer shape being round. The surface shapes of the concave surface 202 and the convex surface 201 of the glass material are both spherical.

The term ″ normal direction ″ of two surfaces of the glass material means a direction that is perpendicular to the surface of the glass material at any position on the surface of the glass material. Accordingly, the normal direction changes at each position on the surface. For example, the direction 204 in FIG. 1 means the normal direction at point 208 on the concave surface of the glass material. The intersection points of the normal direction 204 with the concave and convex surfaces are 208 and 209, respectively. Thus, the interval between 208 and 209 is the thickness in the normal direction. There are other positions on the concave surface of the glass, such as 210 and 212, the normal directions of which are 203 and 205, respectively. In the normal direction 203, the interval between 210 and 211, and in the normal direction 205, the interval between 212 and 213, is the thickness in the normal direction. In a glass material with equal thickness in the normal direction, this space between the upper and lower surfaces in the normal direction is a constant. That is, in glass materials with equal thickness in the normal direction, the upper and lower surfaces are parts of spherical surfaces having one center (207 in FIG. 1).

In this regard, figure 2 shows a schematic diagram of the state of contact between the glass material and the template before and after thermal plasticization. As shown in figure 2 (a), the authors of the present invention conducted an extensive study on the shape deformation caused by thermal plasticization of the glass material when placed on the template, so that at least part of the edge zone of the lower surface of the glass material was in close contact with the forming surface, and the central part of the lower surface of the glass material was separated from the template. As a result, the authors found that as soon as the glass material was placed, as shown in Fig. 2, thermal plasticization caused deformation, where the upper (concave) surface of the glass material was compressed in a direction parallel to the surface, and the lower (convex) surface expanded in a direction parallel to surface. The authors of the present invention further conducted a second study, which led to the discovery that when the deformation of the mold due to thermal plasticization of the glass material, the space in the normal direction between the concave and convex surfaces was kept almost constant with a fairly slight change before and after the deformation of the mold. Figure 2 shows an example in which the upper surface is concave and the lower surface is convex. Similarly, when the upper surface is convex and the lower surface is concave, the interval in the normal direction between the concave and convex surfaces was kept almost constant with a fairly small change before and after the deformation of the shape. Details have not yet been clearly defined; It is believed that this is due to the fact that glass deformation due to thermal plasticization may be identical or close to deformation in a viscoelastic material.

Brief information on viscoelastic materials will be given here. First, an elastic material is a material that expands in proportion to the magnitude of the applied force, returning to its original shape when the force is removed. A viscous material is a material that tends to gradually deform when a force is applied, but retain shape when the force is removed. A viscoelastic material is a material having the properties of both elastic and viscous materials; namely, it has the property of deformation like an elastic material when a force is applied, but retains its shape as soon as the force has been removed. For the sake of simplicity, an example of flat glass will be referenced below to further describe the deformation of the shape of a viscoelastic material.

Figure 3 is a drawing showing the deformation of a viscoelastic material in the form of sheet glass. When flat glass is deformed by thermal plasticization, it is believed that it is deformed into a circular arc shape, like an elastic material, with one surface expanding and the opposite surface contracting. When this happens, there is a plane between the two surfaces of the glass, where neither tension nor compression occurs. It is called a neutral surface. This cross section is called the neutral line. Assuming that this sheet glass almost corresponds to a viscoelastic material, and R denotes the bending radius of the neutral line AB in FIG. 3, the length of the curve CD, which is separated in the normal direction by δ (delta) R, can be approximately expressed as (R + δR) θ (theta).

In addition, the cross section of the viscoelastic material retains a flat surface that remains undistorted after deformation orthogonal to the neutral surface and two of these surfaces. Accordingly, the glass material subjected to thermal plasticization is deformed like an elastic material, and after deformation behaves like a viscous material, restoring its shape. The present inventors have found that the thickness of the glass material in the normal direction remains essentially unchanged, thus, and the space between the upper and lower surfaces of the glass material in the normal direction remains almost identical before and after deformation. That is, it is preferable that the glass material used in the present invention has a substantially equal thickness in the normal direction, and that the thickness in the normal direction does not substantially change before and after deformation. Here, ″ thickness in the normal direction does not substantially change before and after deformation ″ means that the percentage of change in thickness in the normal direction before and after deformation at the furthest measurement points provided by JIS was less than or equal to 1 percent.

The use of such glass material allows high accuracy of the formation of the upper surface of the glass material in such a way as to obtain an offset, or rough offset, relative to the forming surface of the template.

In order to approximately consider the glass material to be a viscoelastic material, it is desirable that the external diameter of the glass material be adequately larger relative to the thickness in the normal direction of the glass material, so that the external diameter of the glass material is adequately large relative to the thickness of the glass material in the normal direction and that the external diameter of the glass material is adequately large relative to the amount of bending direction perpendicular to the glass. Namely, for the glass material used in the present invention, which is considered as a viscoelastic material, it is desirable that the thickness in the normal direction is from 2 to 10 nm, preferably from 5 to 7 nm. In addition, the outer diameter of the glass material is preferably from 60 to 90 nm, preferably from 65 to 86 nm. The ″ outer diameter ″ of the glass material is the difference between a point on a portion of the edge zone of the lower surface of the glass material and an opposite point on the boundary of the edge zone.

The present invention also relates to a method for determining the shape of the forming surface of a template for use in a molding method in which the upper surface of the glass material that has been placed on the forming surface of the template is formed into a desired shape by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into a dense contact with the forming surface, in which the forming surface is a free-form surface other than a spherical surface, and p Assuming that the glass material has upper and lower surfaces that are spherical in shape and has substantially equal thickness in the normal direction, the shape of the forming surface is determined based on the desired shape of the upper surface and thickness in the normal direction of the glass material.

As described above, the thickness between the upper and lower surfaces of the glass material in the normal direction is almost preserved before and after deformation by thermal plasticization. Accordingly, the space in the normal direction between the upper surface of the glass material and the forming surface of the template after molding can be considered substantially identical to the thickness in the normal direction of the glass before molding. Thus, the shape of the forming surface of the template can be determined based on the desired shape of the upper surface of the glass material and the thickness of the glass material in the normal direction. That is, the surface shape of the forming surface of the template can be determined by determining the desired shape of the upper surface of the glass material, and then determining the surface, so that the distance in the normal direction from the surface of the mold that has been determined matches the thickness of the glass material in the normal direction.

The present invention also relates to a method for determining the shape of the lower surface of the glass material for use in a molding method, in which the upper surface of the glass material that has been placed on the forming surface of the template is formed into a desired shape by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into contact with the forming surface, in which the forming surface is a free-form surface other than a spherical surface and, and assuming that the glass material has upper and lower surfaces that are spherical in shape and has substantially equal thickness in the normal direction, the shape of the forming surface is determined based on the desired shape of the upper surface and the shape of the forming surface, which was determined based on thickness of glass material in the normal direction.

In the manufacture of a template for spectacle lenses with a gradual increase in optical power having one reference point for measuring far optical power and one reference point for measuring near optical power of the present invention, it is desirable to define the shape of the lower surface of the glass material as a surface having a spherical shape, the average curvature of which is approximately identical to the average curvature at the reference point for measuring far optical power. Thus, the lower surface of the glass material and the forming surface of the template can contact at least three points, as will be noted later, and the spherical glass material can be stably placed on the forming surface of the template, which is aspherical in shape. Spectacle lenses with a gradual increase in optical power and a reference point for measuring optical power will be described in detail below. Since glass material with equal thickness in the normal direction, and having spherical upper and lower surfaces, is used in the present invention, determining the shape of the lower surface of the glass material, as described above, allows you to determine the shape of the upper surface of the glass material based on the thickness in the normal direction.

Glass material with two spherical surfaces is used in the present invention. Thus, by determining the shape of the forming surface of the template, as indicated above, in the manufacture of the template for a single-focal spectacle lens, the shape of the lower surface of the glass material can be determined based on the shape of the forming surface of the template that has been determined. This method of determining the shape of the lower surface will be described below.

In the present invention, the lower surface of the glass material is spherical. Thus, the radius of curvature can be obtained and the shape of the bottom surface can then be determined by defining only three points consisting of the center of the spherical surface and any two opposite points located on the circle. For example, as shown in figure 2 (a), when the glass material is placed on the template so that at least part of the boundary of the edge of the lower surface is in close contact with the forming surface, and the central part of the lower surface of the glass material is separated from the forming surface, that the lower surface of the glass material is in contact with the forming surface at one point on the border of the edge of the lower surface of the glass material, and at the point opposite to this point (E and E 'in figure 2 (a)). Since the lower surface of the glass material is spherical, the above contact positions become points on the circumference of the circle at a fixed distance from the center on the forming surface of the template. The distance between these two points (E and E 'in figure 2 (a)), corresponds to the outer diameter of the glass material. Then set the point (point C in figure 2 (a)), removed from the Central position of the forming surface of the template at a distance T in the vertical direction. The distance T corresponds to the space between the lower surface of the glass material and the forming surface of the template before heating, and can be determined by considering the size of the glass material, its properties of thermal deformation, and the like. For example, it can be installed from 0.2 to 5 mm.

In this way, a spherical shape passing through E, E 'and C is determined, that is, the shape of the lower surface of the glass material.

A method for determining the shape of the lower surface of the glass material will be described in more detail.

In Fig. 2 (a), when the vertical distance between the line connecting E and E '(the dashed line in Fig. 2 (a)) and the center of the forming surface is denoted by dt (mm), the distance between E-E' is denoted as D (mm), and the average curvature of the forming surface is denoted as R, dt can be obtained from the following equation:

[Number 1]

Then, based on the calculated dt and the distance T (mm) between the center of the lower surface of the glass material and the center of the forming surface, we can obtain the radius of curvature r of the lower surface from the following equation:

[Number 2]

The shape of the lower surface of the glass material can be determined in this way.

In addition, by determining the shape of the lower surface of the glass material in the above manner using glass material having two spherical surfaces and equal thickness in the normal direction, the shape of the upper surface of the glass material can be determined from the shape of the lower surface that has been determined and the thickness of the glass material in the normal direction. That is, a surface for which space in the normal direction from a lower surface having a surface shape that has been determined to correspond to the thickness of the glass material in the normal direction can be defined as the upper surface of the glass material.

In the present invention, molded products can be manufactured using glass material and a template whose surface shape has been determined as set forth above. In order to carry out high-precision molding using glass material and a template whose surface shape has thus been determined, glass materials are preferably used that have the above-mentioned desired thickness in the normal direction and an outer diameter for a good approximation to the viscoelastic material. Thus, the shape of the upper surface of the glass material can be obtained as an approximately offset surface relative to the forming surface of the template.

A pattern that can be used in the present invention will be described below.

The template on which the glass material is placed is not specifically limited, except that it has a free-form forming surface that is not a spherical surface. Known patterns used in the hot bend molding method can be used.

The above free form means a surface shape that includes a surface in which the curvature in the position for long-distance measurement on the optical surface differs from the curvature in other positions. Examples are surface shapes including optical surfaces, such as axially symmetric aspherical lenses with a gradual increase in optical power, lenses with a gradual increase in optical power, and lenses with a gradual increase in optical power, both surfaces of which are aspherical.

Spherical shape means a shape in which the curvature is constant in the position for long-distance measurement and in other positions on the optical surface of the lens. The term axially symmetric aspherical means, for example, a shape in which the curvature in the position for distant measurement, located in the geometric center, differs from the curvature in other positions on the optical surface of the lens. As a rule, axially symmetric aspherical lenses have a shape in which the position for long-distance measurement is located in the geometric center, and the curvature increases or decreases continuously with the distance from the center of the lens along the main longitudinal direction from the center to the edge of the lens. For example, a centrally symmetric aspherical lens has a cross section shown in FIG. 11b. A lens with a gradual increase in optical power is a lens that is used as a lens with a gradual increase in optical power for presbyopia. When used in presbyopic glasses, lenses with a gradual increase in optical power give the advantage of not being identifiable as presbyopic glasses based on their appearance, and the advantage of providing continuously transparent, continuous vision from distant to near vision. Therefore, they are generally widely used. However, without introducing boundary lines into the area bounded by the lenses, multiple fields of vision are provided, including a field of vision for viewing far away, a field of vision for near vision and a field of vision for viewing intermediate distances. Examples of a lens with a gradual increase in optical power that can be manufactured according to the present invention include, firstly, a one-sided lens with a gradual increase in optical power, having a progressive surface both on the first dioptric surface, which is the front surface, and on the second dioptric surface , which is the surface of the eyeball, and secondly, a two-sided aspherical lens with a gradual increase in optical power with the effects of progressive optical power, definiteness between the first dioptric surface that is the front surface and the second dioptric surface that is the outer surface of the eyeball, wherein the first surface and the second surface collectively impart a far degree and introduction degrees based on the prescription. A lens with a gradual increase in optical power has, for example, a degree distribution such as that shown in FIGS. 7-10 or the cross section shown in FIGS. 11a and 11c.

In addition, a template having a forming surface of a given roughness is readily used in the present invention. The mold surface of the template commonly used in the hot bend molding method is a polished mirror. However, when the forming surface of the template coming into contact with the glass material is a smooth surface such as a polished surface, it often sinteres with glass, the surface of the template is scratched during the removal of the glass material or the like, compromising the service life. Sintering with glass material can be prevented by using a template having a forming surface of a given roughness. This item will be described based on FIG.

Figure 4 shows an enlarged diagram of the state of contact between the template and the glass material before and after thermal plasticization in a template having a forming surface of a given roughness. As shown in figure 4, even when the forming surface of a given roughness is fused with a part of the glass material to achieve softening, sintering of the entire forming surface does not occur, and it is limited only by protruding parts, and strong adhesion between the glass material and the forming surface of the template does not develop. Thus, it becomes easy to separate the glass material from the template, thereby avoiding damage to the template and glass material (molded product) after softening. However, when the forming surface is too rough, there is a risk of affecting the shape of the upper surface of the glass material, and the inability to obtain the desired surface shape. Considering the above, as an example, as a template, it is desirable to use a template having many irregularities with a maximum height Rmax within the range from 0.1 to 100 micrometers and an average distance S between local peaks within the range from 0 , 01 to 1.00 mm. The above Rmax refers to a value that is measured in accordance with the definition of surface roughness described in JIS BO601-1982. The average space S between local peaks is a value that is measured in accordance with the definition described in JIS K7125. The above maximum roughness with a height of Rmax is preferably from 1 to 10 micrometers, preferably from 3 to 9 micrometers. The above average distance between the local peaks S is preferably from 0.01 to 0.1 mm, preferably from 0.05 to 0.5 mm. The roughness of the forming surface is preferably from 0.01 to 10 micrometers, preferably from 0.1 to 1 micrometer, and more preferably from 0.3 to 0.9 micrometers, as the arithmetic average roughness Ra, measured in accordance with the definition of surface roughness, described in JIS BO601-1982. Within the above ranges, sintering can be prevented and precise molding can be achieved.

The above height and distance between bumps can be measured using, for example, Form Talysurf manufactured by Taylor Hobson Corp. In Form Talysurf, a ruby or diamond is placed on the tip of the probe; the tip of the probe is moved along the surface of the lens, and in contact with the lens; and the surface of the lens is scanned to measure the surface shape. The measured scan path is usually just linear. Measure part of the surface. The scanning direction during the measurement is perpendicular to irregularities on the forming surface of the template. After measuring the height of the bumps and the distance between them on the forming surface of the template is determined by analyzing the measured values of the height of the bumps and the distance between them.

The above pattern can be made of materials that are commonly used in known patterns used in the hot bend molding process. Since metals have poor resistance at 800 ° C, which is usually the maximum softening temperature, and have high coefficients of thermal expansion, this form is significantly deformed due to thermal expansion that occurs with temperature changes near 800 ° C. When the level of change is large, there is a risk that at least either the glass material or the template will not be able to withstand the difference in compression during cooling on the contact surface between the glass material and the template, and will collapse. Thus, the template used in the present invention is desirably made from a heat-resistant material having good resistance and an expansion coefficient that is close to the coefficient of expansion of the glass material. Examples of such heat-resistant materials are ceramics based on alumina (Al ₂ O ₃ ), based on AlTiC (Al ₂ O ₃ -TiC), based on zirconium oxide (ZrO ₂ ), based on silicon nitride (Si ₃ N ₄ ), on based on aluminum nitride (AlN) and based on silicon carbide (SiC), as well as other ceramics having the main components in the form of SiO ₂ , Al ₂ O ₃ or MgO. Here, the term ″ having the main components in the form ″ means that these components are considered equal to or greater than 50 weight percent of the structural components of this template.

Firstly, the template material is suitable, which has, for example, hardness (Vickers hardness) from 7 to 24 Hv, bending strength from 400 to 2000 MPa, Young's modulus from 180 to 410 GPa, thermal conductivity from 3.0 to 170 W / mK, the coefficient of linear expansion from 4.30 to 10.8 × 10 ^-6 , heat resistance from 750 to 850 ° C, and density from 3.10 to 10.70 g / cm ³ . Secondly, a material having a hardness (Vickers hardness) of 7 to 15 Hv, Young's modulus of 190 to 210 GPa, a linear expansion coefficient of 6.0 to 7.0 × 10 ^-6 and heat resistance of 775 to 825 ° C. Thirdly, a material having a hardness (Vickers hardness) of 9 to 15 Hv, a Young's modulus of 180 to 402 GPa, a linear expansion coefficient of 4.30 to 10.8 × 10 ^-6 and a heat resistance equal to or more than 800 ° C. The template material is also preferably hydrophobic.

A forming surface with the above surface roughness can usually be obtained only by grinding or cutting, without polishing. In the present invention, high-precision spherical glass materials having a spherical polished surface and patterns with a free shape other than a spherical surface can be combined to easily form free-form optical surfaces other than a spherical surface. When the forming surface has the above surface roughness, a mirror-shaped glass free-form optical surface can be obtained without the need for a step of polishing the forming surface to a mold having a free-form surface. This is very cost effective and productive.

In the present invention, the glass material is placed on the forming surface of the template before molding. The glass material can be placed on the template so that at least part of the boundary zone of the lower surface of the glass material is brought into contact with the forming surface, and the central part of the lower surface of the glass material is separated from the template. In the present invention, since the glass material, the lower surface of which is spherical in shape, is placed on a forming surface having a free shape that is not spherical, a stable arrangement of the glass material is preferably achieved by arranging the glass material so that at least three points on the lower surface of the edge part were in contact with the forming surface.

The method of manufacturing a molded product of the present invention can be applied to produce a mold for spectacle lenses using block polymerization, or to produce a portion of such a mold. Typically, spectacle lenses are classified as single-focal spectacle lenses, multifocal spectacle lenses, or spectacle lenses with a gradual increase in optical power. A brief description of spectacle lenses with a gradual increase in optical power is given in JIS T 7315 and JIS T 7330. Spectacle lenses with a gradual increase in optical power will be described below.

In spectacle lenses with a gradual increase in optical power, the areas of the far, intermediate and near field of vision are distributed based on the frequency of use. A far field that has a high frequency of use is often made wide, and is designed based on an emphasis on a long range or short range. Applications vary depending on differences in the width of the field of view related to the distance to the subject. Three main categories can be distinguished: universal spectacle lenses with a gradual increase in optical power, spectacle lenses with a gradual increase in optical power for intermediate near vision and spectacle lenses with a gradual increase in optical power for near near vision. There are also types with a focus on longer ranges and with a focus on the far-medium range. Universal eyeglass lenses with a gradual increase in optical power are designed for use both in the far and near ranges, and have functions that allow both far and near vision. However, they are limited in the breadth of the field of view that they give in the middle and near regions. Usually, the wider the field of view in the far and near ranges, the greater the tendency for distortion and deviation, especially to the progression, which must be obtained in the intermediate range. Spectacle lenses with a gradual increase in optical power for intermediate and near vision are endowed with a wide intermediate region and the near region, by limiting the far region. The far region occupies a higher position than the universal region and has a long progression band, so there is slight distortion and deviation, especially in the progression band . However, such lenses are not convenient for the long range of vision. Spectacle lenses with a gradual increase in optical power for near-near vision primarily have near ranges and do not have far ranges; they are, therefore, sometimes classified as single-focal lenses. All of the above categories of lenses with a gradual increase in optical power are suitable as target lenses produced using molds in the form of molded products made either by the production method of the present invention or using the template of the present invention described below.

Lenses with a gradual increase in optical power can be divided into three groups, based on the location of progressive elements on the concave and convex surfaces of the lens. The first group consists of lenses with a gradual increase in optical power with a convex (external) surface in which the progressive surface is located on the convex surface. The second group consists of lenses with a gradual increase in optical power with a concave (inner) surface, in which the progressive surface is located on the concave surface. And the third group consists of two-sided aspherical (also called two-sided combined) lenses with a gradual increase in optical power, in which progressive elements are divided between two surfaces.

A convex lens surface with a gradual increase in optical power has a progressive surface on a convex surface, wherein a progressive optical power is generated based on the shape of the optical surface of the convex surface. Concave lenses with a gradual increase in optical power are similar, with the exception of the difference between concavity and bulge.

Bilateral aspherical lenses with a gradual increase in optical power have the advantage of both ″ the outer surface of the lens with a gradual increase in optical power ″ and the ″ inner surface of the lens with a gradual increase in optical power ″. Thus, they are lenses with a gradual increase in optical power, having a design in which changes in optical power in the vertical direction related to the length of the progression band are distributed and arranged on the side of the convex surface, and changes in optical power in the horizontal direction related to distortion and deflection, distributed and located on the side of the concave surface. The surface of this “double-sided combined progression” consists of special aspherical surfaces that are not progressive surfaces on both surfaces, and are structurally different from traditional lenses with a gradual increase in optical power, called “double-sided lenses with a gradual increase in optical power”, in which the specified degree is added splits between both surfaces, which are progressive surfaces. Since both surfaces of the lens can be used synthetically, the distinct fields of vision can be expanded to the far, intermediate and near ranges. In particular, deflection and distortion along the perimeter of the lens are improved.

JIS T7315, JIS T7313 and JIS T7330 set reference points for measuring optical power as reference points for measuring the refractive index of spectacle lenses. The reference points for measuring optical power are parts that are surrounded by circles with a diameter of about 8.0 to 8.5 mm; for example, on the surface on the front side or on the side of the eyeball of a spectacle lens. In single-focal eyeglass lenses, the reference point for measuring optical power is in the center of the lens surface. In lenses with a gradual increase in optical power and multifocal eyeglass lenses, there are many reference points for measuring optical power. As will be described below, lenses with a gradual increase in optical power can be roughly divided into groups of universal lenses with a gradual increase in optical power, lenses with a gradual increase in optical power for vision at intermediate and close distances, and lenses with a gradual increase in optical power for vision at short range. There are two reference points for measuring optical power, called the reference point for measuring the far part and the reference point for measuring the near part, in universal lenses with a gradual increase in optical power and lenses with a gradual increase in optical power for viewing at intermediate and close distances. There are two reference points for measuring near parts in lenses with a gradual increase in optical power for near-field vision.

Progressive lenses are usually formed into an aspherical shape that is vertically and right-left asymmetric and includes shapes of greater complexity than spherical shapes. The intermediate region located between the reference point for measuring the far part and the reference point for measuring the near part in lenses with a gradual increase in optical power is called a progression band. Within this band, the optical power changes progressively. The reference point for measuring the proximal portion is in the position related to the convergence of the eyeballs in the position either to the right or left of the main meridian, and is determined to be located either to the right or left of the main meridian, based on the right and left separation of the eyeballs. Accordingly, in the case of a convex surface of the lens, the convex surface has an aspherical shape, which is vertically and right-left asymmetric. Since the upper surface of the mold for molding such a surface shape is also aspherical in shape, the shape of the mold surface of the template, which is approximately offset from the shape of the upper surface of the mold (the desired shape of the upper surface of the glass material), is also aspherical in shape and vertically and right-left asymmetric. However, the glass material is spherical in shape. When a spherical glass material is placed on a vertically and right-left asymmetric forming surface, there is a time when it cannot be kept in a stable state and becomes unstable. The same is true for double-sided aspherical lenses with a gradual increase in optical power. For stable placement of spherical glass material on a forming surface that is aspherical in shape, it is desirable that the glass material be placed on the template so that at least on the lower surface of the edge of the glass material are two points that are located on the side relative to the reference point for measuring the far optical power of the lens with a gradual increase in optical power, and one point, which is located on the side of the reference point for measuring the near optical power, was in contact with uyuschey surface. When the glass material is molded into a molded product (mold or part thereof), the surface that was the upper surface of the glass material (the surface opposite to the surface that is in close contact with the forming surface) is transferred to the eyeglass lens. ″ The position related to the reference point for measuring the optical power ″ of the lower surface of the glass material is part of the lower surface of the glass material, the opposite part of the upper surface of the glass material serving as the part that is transferred to the reference point for measuring the optical power of the spectacle lenses on the surface of the obtained mold. As stated above, the lower surface of the glass material is formed into a spherical shape having an average curvature that is approximately identical to the average curvature at the reference point for measuring the far optical power of the lens with a gradual increase in the optical power that must be obtained at the end, thereby making it possible to stabilize the glass material on the forming surface with the three above points of support.

12 (a) is a visual drawing of the contact between the lower surface of the molded material for the production of the mold of the lens with a gradual increase in optical power and the forming surface of the template. 12 (a), the support points A, B and C are the contact points of the lower surface of the glass material with the forming surface. 12 (a), the support points A and B, which lie above the line corresponding to the horizontal line of the lens (also referred to as the “horizontal comparison line ″ or ″ principal longitude ″) drawn through two aligned reference points, are two points located on the side corresponding to the reference points for measuring the far optical power, and the pivot point C, which is below the meridian, is a point located on the side corresponding to the reference points for measuring the near optical power. As shown in FIG. 12 (a), two points located on the side correspond to the reference points for measuring the far optical power, preferably located symmetrically near the line corresponding to the main meridian, which passes through the reference point for measuring the far optical power of the lens with gradual increase optical power on the underside of the glass material. Furthermore, when the lens to be obtained at the end has a surface shape with only one progressive surface, the pivot point on the side corresponding to the reference point for measuring the near optical power is preferably located on the side opposite from the reference point for measuring the near optical power with respect to line corresponding to the main meridian, as shown in Fig.12 (a). Furthermore, as shown in FIG. 12 (b), when the lens to be obtained at the end is aspherical with progressive elements (such as the convex surface of HOYALUX iD manufactured by HOYA (Co., Ltd.)), the contact point, located on the side corresponding to the reference point for measuring the near optical power, it is desirable to be located on the line corresponding to the main meridian (pivot point F in Fig. 12 (b)).

″ The line related to the main meridian passing through the reference point for measuring far optical power ″ on the lower surface of the glass material refers to the part on the lower surface of the glass material, the opposite part on the upper surface of the glass material, becoming the part that is transferred to the part in which the main meridian is spectacled the lens is located on the surface of the mold.

In the embodiments described below, at least three of the above points are contact points (supports); however, there may be four or more contact points.

In a single-focal eyeglass lens, it is desirable that the glass material be positioned so that the entire circumference of the edge portion of the lower surface is in contact with the forming surface.

Glass material is not specifically limited. Glasses such as crown-based, flint-based, barium-based, phosphate-based, fluorine-containing and fluorophosphate-based glasses are suitable. In the first example, a suitable glass is glass comprising SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ as structural components and having a glass material composition, given in molar percent, from 45 to 85 percent SiO ₂ , from 4 to 32 percent Al ₂ O ₃ , from 8 to 30 percent Na ₂ O + Li ₂ O (with a Li ₂ O content of less than or equal to 70 percent of Na ₂ O + Li ₂ O), the total amount of ZnO and / or F ₂ from 2 to 13 percent (where F ₂ <8 percent), Li ₂ O + Na ₂ O / Al ₂ O ₃ from 2/3 to 4/1, and SiO ₂ + Al ₂ O ₃ + Na ₂ O + Li ₂ O + ZnO + F ₂ > 90 percent.

In the second example, a suitable glass is glass having a glass material composition, given in molar percent, from 50 to 76 percent SiO ₂ , from 4.8 to 14.9 percent Al ₂ O ₃ , from 13.8 to 27.3 percent Na ₂ O + Li ₂ O (with a Li ₂ O content of less than or equal to 70 percent of Na ₂ O + Li ₂ O), the total amount of ZnO and / or F _{2 is} from 3 to 11 percent (where F ₂ <8 percent), Li ₂ O + Na ₂ O / Al ₂ O ₃ from 2/3 to 4/1, and SiO ₂ + Al ₂ O ₃ + Na ₂ O + Li ₂ O + ZnO + F ₂ > 90 percent.

In the third example, the glass composition is: SiO ₂ (47.8 percent), Al ₂ O ₃ (14.0 percent), Na ₂ O (12.1 percent), B ₂ O ₃ (percent), ZnO (6, 0 percent), F ₂ (2 percent), MgO (2 percent), Li ₂ O (16.1 percent), As ₂ O ₃ (0.3 percent).

In a fourth example, a further suitable glass composition is: SiO ₂ (63.6 percent), Al ₂ O ₃ (12.8 percent), Na ₂ O (10.5 percent), B ₂ O ₃ (1.5 percent) ZnO (6.3 percent), Li ₂ O (4.8 percent), As ₂ O ₃ (0.3 percent), Sb ₂ O ₃ (0.2 percent). Other metal oxides such as MgO, PbO, CdO, B ₂ O ₃ , TiO ₂ and ZrO ₂ ; painted metal oxides; and similar can be added to stabilize the glass, facilitate melting and colorization, provided that they do not exceed 10 percent.

As further characteristic properties of the glass material, for example, suitable thermal properties are: a deformation temperature of 460 to 483 ° C, an upper annealing limit of 490 to 621 ° C, a softening point of 610 to 770 ° C, a glass transition temperature (T _g ) of 510 to 665 ° C, yield point (T _s ) from 535 to 575 ° C, specific gravity from 2.47 to 3.65 (g / cm ³ ), refractive index, N _d from 1.52300 to 1.8061, thermal diffusion rate from 0.3 to 0.4 cm ² · min, Poisson's ratio from 0.17 to 0.26, photoelasticity constant 2.82 × 10 ^-12 , Young's modulus from 6.420 to 9,000 kg s / mm ² and linear coefficient R extensions from 8 to 10 × 10 ^-6 / ° C. The deformation temperature is 460 ° C, the upper limit of annealing is 490 ° C, the softening point is 650 ° C, the glass transition temperature (T _g ) 485 ° C, the yield strength (T _s ) 535 ° C, the specific gravity is 2.47 (g / cm ³ ) , refractive index, N _d 1.52300, thermal diffusion rate 0.3576 cm ² · min, Poisson's ratio 0.214, photoelasticity constant 2.82 × 10 ^-12 , Young's modulus from 8.340 kg s / mm ² and linear expansion coefficient from 8, 5 to 10 × 10 ⁻⁶ / ° C. are particularly preferred. The shapes of the upper surface and lower surface of the above glass materials are constructed in the manner described above. By processing glass into a specific surface shape, glass material for molding can be obtained. Glass material can be processed by known methods. The shape of the glass material is not specifically limited, provided that the upper and lower surfaces are spherical; it can be spherical, elliptical, have an axisymmetric shape (toroidal lenses, aspherical axisymmetric lenses with a gradual increase in optical power), have the shape of a free surface (lenses with a gradual increase in optical power, aspherical double-sided lenses with a gradual increase in optical power) or similar. A meniscus shape having two polished spherical surfaces is preferred. The surfaces of the glass material are preferably mirrored surfaces. The surface roughness is preferably a roughness with a maximum height Rmax of less than or equal to 0.04 micrometers, and an arithmetic average roughness Ra of less than or equal to 0.005 micrometers. The lower limit of the roughness of the glass material is, for example, the maximum roughness Rmax of 0.01 micrometers and the arithmetic average roughness Ra of 0.01 micrometers.

After placing the glass material on the forming surface of the template, the glass material is heated to a temperature that allows deformation on the template. ″ The temperature allowing deformation ″ is desirably a temperature that is higher than or equal to the glass transition temperature (T _g ). Heating can be carried out by a known method, such as placing a template in an electric furnace. By controlling the temperature of the atmosphere in the electric furnace to a predetermined temperature for the glass material, the glass material can be heated to the desired temperature. Details of temperature control will be described later below.

As shown in FIG. 2 (a), before heating, there is a partial gap between the lower surface of the glass material and the forming surface; there is no full, close contact. When heating the glass material in this state, the fluidity of the glass material increases as it softens. As shown in FIG. 2 (b), the lower surface of the glass material is in close contact with the forming surface. The term "tightly contacted" in the present description does not mean a state in which the glass material penetrates into irregularities on the forming surface.

In the present invention, as shown in FIG. 2, it is preferable that the covering element is located on top of the template on which the glass material was placed, and the open part on the side of the forming surface of the template on which the glass material was placed, is preferably coated. In the present invention, the term “coated” means the separation of the internal space from the external to the extent that a foreign substance, such as dust and waste, does not enter; air passage is permissible.

The surface of the glass material, which is subjected to thermal plasticization, is very reactionary. Since the molding step is usually quite long, any foreign substance, such as dust in the air and waste in the electric furnace, which adheres to the upper surface of the glass material during this period, adheres very strongly, compromising the accuracy of the molding. Thus, there is a risk of the inability to form an optical surface. In contrast, when the glass material is subjected to thermal plasticization with the exposed part on the side of the forming surface of the glass material coated with the coating element, the inclusion of the above foreign substance is prevented. In addition, the use of a covering element, as described above, provides an additional advantage in that it does not require the installation of a large-scale device for cleaning the room where the electric furnace is installed.

The covering element may be of any shape that will cover the exposed part on the side of the forming surface of the template on which the glass material was placed. An example of such a covering element will be described based on FIG. However, the present invention is not limited to the embodiment shown in FIG. 2. The cover member is described below in the form of a cap. However, the cover member of the present invention is not limited to the cover member.

In the embodiment shown in FIG. 2, an annular support member is positioned between the cover member and the template, and the edge surface of the stepped portion of the circumference of the support member is mounted in the edge surface of the cover opening. When such a supporting element is not used, it is sufficient to provide a stepped element to support the covering element on the circumference of the template and matching the edge surface of the stepped element to the opening of the covering element.

The lid member shown in FIG. 2 forms part of a cylindrical shape. Only the bottom surface of the cylindrical shape is open, there is space inside. The dimensions of the coating element are not specifically limited, but from the point of view of impact resistance and heat transfer efficiency, a thickness of about 1 to 5 mm, an internal height of 5 to 100 mm, preferably 30 to 60 mm are desirable.

A stepped mounting portion is formed inside the lid member shown in FIG. 2. The thickness of the side surface from the stepped installation part to the hole is thinner than the thickness of the side surface from the upper surface to the stepped installation part. By making the edge surface of the hole of the coating element thin, the contact surface between the cover element and the support element is reduced in this way (the template when the support element is not used) and the pressure per unit area that is exerted on the edge surface of the hole by the mass of the cover element itself increases the air tightness inside the cover item. When a support member is used, as shown in FIG. 2, and the area of the edge surface of the opening of the cover portion is made small, it becomes possible to reduce the contact area between the support member and the covering member, thereby reducing the entire size of the support member. Reducing the size of the support element reduces the thermal expansion of the support element, thereby enhancing the airtightness of the covering element.

The edge surface of the opening of the covering element, which is installed in the template or support element, is desirably a smooth surface in order to increase the density. In addition, in order to achieve an even distribution of heat throughout the glass material, it is desirable to adjust the inner upper surface facing the opening of the coating element in shape to the upper surface of the glass material, and preferably approximately similar in shape to the shape of the upper surface of the glass material. The inner upper surface of the lid member, facing the hole, is desirably an approximately flat surface. When the shape of the inner upper surface of the coating element matches the shape of the upper surface of the glass material, it becomes possible to uniformly irradiate the glass material placed on the forming surface with the heat of radiation from the coating element, increasing the uniformity of heat distribution in the glass material. However, the shape of the upper surface of the glass material varies from product to product. Accordingly, in order to guarantee a uniform heat distribution in the glass material even when forming a plurality of glass materials with different shapes of the upper surface, it is desirable that the inner upper surface of the coating element is approximately flat. In addition, as shown in FIG. 1, it is desirable that the edge portion of the inner upper surface of the cover element is formed in a rounded shape. When angles are present, the distribution of heat tends to become partially inhomogeneous. By providing a rounded shape, as shown in FIG. 1, the heat distribution within the coating element can be made uniform. For example, the use of a rounded shape, such as the one set above, effectively enhances the service life when the covering element is made of ceramic, since the ceramic tends to crack when corners are present.

The cover element is included in the template or support element located on the template, thereby separating the inside of the cover element from the external atmosphere. The separation of the inner part of the coating element from the external atmosphere in this way prevents the dispersion and contamination of a foreign substance, such as dust and waste, and also creates a buffering effect that weakens the uneven temperature distribution and unforeseen changes in temperature in the atmosphere to which the glass material is exposed. In the traditional hot bend molding method, glass material is placed on a template and introduced into the furnace along with the template. However, since the heat distribution inside the furnace is uneven, it is difficult to uniformly heat the complex glass materials inside the furnace. In addition, since changes in temperature in the furnace directly affect the glass material, there is a risk of deformation and the like due to unforeseen changes in temperature.

In contrast, the coating element temporarily retains external heat, and the coating element itself achieves a uniform temperature distribution. The accumulated heat is then radiated to the inside from the covering element. As was established above, the shape of the inner upper surface of the coating element can be adjusted for effective control, so that the heat that is radiated from different parts of the coating element as a heat source is radiated uniformly on the glass material, allowing uniform heating of the glass material. In addition, sudden changes in temperature inside the furnace are weakened by the coating element, preventing deformation and the like caused by such sudden changes in temperature. In order to conduct thermal plasticization of the glass material well, the thermal conductivity of the coating element should preferably be from 3 to 170 W / mK, preferably from 90 to 120 W / mK.

The coating element preferably consists of a ceramic material with good heat resistance. Examples of such ceramic materials are ceramics based on alumina (Al ₂ O ₃ ), based on AlTiC (Al ₂ O ₃ -TiC), based on zirconium oxide (ZrO ₂ ), based on silicon nitride (Si ₃ N ₄ ), on based on aluminum nitride (AlN) and based on silicon carbide (SiC), as well as other ceramics having the main components in the form of SiO ₂ , Al ₂ O ₃ or MgO. Here, the term "having the main components in the form" means that these components are considered equal to or greater than 50 weight percent of the structural components of the coating element.

Ceramics comprising SiO ₂ , Al ₂ O ₃ and / or MgO in an amount greater than or equal to 99 percent, the remainder being K ₂ O or the like, is a suitable heat-resistant material for use in the coating element.

Firstly, a material having a hardness (Vickers hardness) of 7 to 24 Hv, bending strength of 400 to 2000 MPa, Young's modulus of 180 to 410 GPa, linear expansion coefficient of 4.30 to 10.8 × 10 ^{- 6} , heat resistance from 750 to 850 ° C, and density from 3.10 to 10.70 g / cm ³ , is an example of a suitable material for a coating element. Secondly, a material having a hardness (Vickers hardness) of 7 to 15 Hv, Young's modulus of 190 to 210 GPa, linear expansion coefficient of 6.0 to 7.0 × 10 ^-6 and heat resistance of 775 to 825 ° C is particularly suitable. Thirdly, a material having a hardness (Vickers hardness) of 9 to 15 Hv, a Young's modulus of 180 to 402 GPa, a linear expansion coefficient of 4.30 to 10.8 × 10 ^-6 and a heat resistance equal to or greater than 800 ° C is particularly suitable. The material of the coating element is also preferably hydrophobic.

The method of manufacturing the coating element is not specifically limited. For example, when the coating element is made of ceramic, it can be obtained by powder metallurgy. Namely, the ceramic powder is laid in a metal template serving as a mold for the coating element, and molding is performed by compression. Then, the molded ceramic is heated for a predetermined period (for example, about 10 hours) to an elevated temperature greater than or equal to 1000 ° C (for example, from 1550 to 1750 ° C) to obtain a coating element in the form of a sintered ceramic element. Then, the edge surface of the opening of the coating element is desirably processed for smoothness. This treatment is not specifically limited for smoothness, and can be carried out by conventional rounding methods. For example, a plate-shaped diamond with a flat surface can be mounted on the lower shaft of the processing device and rotate at a speed of about 200 to 300 revolutions per minute in order to grind the side surface of the region of the open part of the coating element and obtain a smooth surface. When processing for smoothness, it is desirable to supply water (from about 1 to 2 l / min, for example) to the surface to be treated for cooling.

In the case of a ceramic coating element, it is desirable to treat the upper inner surface of the coating element to prevent dispersion of particles. This is necessary to prevent the dropping of microparticles of ceramics during molding and contamination of the upper surface of the glass material. The method of applying glaze and its sintering can be applied as a treatment to prevent dispersion of particles. In the above steps of manufacturing the coating element, the glaze can be applied to the upper inner surface of the coating element after compression molding, but before sintering so that the sintering firmly adheres the glaze to the upper inner surface of the coating element. It is sufficient to carry out the treatment to prevent the dispersion of particles, at least on the upper inner surface of the coating element, located face to the upper surface of the glass material. When molding by sucking air through the holes formed in the template, as will be described later, it is desirable to treat the upper inner surface of the coating element to prevent dispersion of particles, while at the same time leaving the side surfaces untreated to allow the passage of air.

Glaze is a viscous substance containing glass particles, which is usually used to brighten the surface of ceramic products. Typically, the glazes consist of SiO ₂ , Al ₂ O ₃ , CaO, MgO, K ₂ O, Na ₂ O, Fe ₂ O ₃ , Li ₂ O and the like. After applying the glaze to the upper inner surface of the coating element, it is sintered at a temperature above its melting point to obtain a coating layer on the inner surface of the coating element by melting glass particles. This coating layer can prevent the dispersion of ceramic particles on the upper surface of the glass material. Glaze having a melting point higher than the temperature of thermal plasticization of the glass material, such as glaze having a melting point of 1150 to 1300 ° C., can be used. A coating layer formed by a glaze having a melting point higher than the temperature of thermal plasticization of the glass material is desirable since it will remain unmelted during molding, preventing the dispersion of particles.

As shown in figure 2, the support element can be placed on the edge of the template. The support element effectively positions the glass material. The support provided by the support member will be described below.

When the glass material is supported by the support element, it is desirable to arrange the glass material so that at least part of the lower surface of the edge part of the glass material is in close contact with the forming surface, the center of the lower surface of the glass material is separated from the forming surface, and support is provided for the supporting element, the lower part being provided the side surface of the glass material was separated from the support element, and at least a portion of the upper edge portion of the side surface of the glass material was held by the supporting element. By arranging the glass material and providing support with the support member in this manner, support can be provided without fusing together the glass material and the support member, the glass material being located and supported on the template by the support member. This will be described below based on FIGS. 1 and 13. However, the present invention is not limited to the following embodiment.

In the form shown in FIG. 2, a meniscus-shaped glass material with a convex lower surface and a concave upper surface is arranged on the forming surface of the convex template. Fig is an enlarged diagram of the state of contact between the support element and the side surface of the glass material before and after softening.

First, at the beginning of molding, the glass material is placed on the forming surface of the template in a state supported by the supporting element. As shown in FIG. 13 (a), it is desirable to provide support provided by the support member, wherein the lower portion of the side surface of the glass material is separated from the support member, and at least a portion of the upper edge portion of the side surface of the glass material is supported by the support member. In this case, for example, the upper edge part of the side surface of the glass material refers to a part above 4/5, preferably above 1/2, the side surface of the glass material, and the lower part of the side surface of the glass material refers to a part lower than the part that is supported by the supporting member by the method described above.

In addition, at the beginning of molding, as shown in Fig. 2 (a), the glass material is placed on the forming surface of the template so that the edge of the lower surface of the glass material is in close contact with the forming surface, and the central part of the lower surface of the glass material is separated from the forming surface. Here, the central part of the lower surface of the glass material refers to a position from the center of the forming surface to about 1/2 of the radius, preferably to a position from the center of the forming surface to a radius of 50 mm. The edge part of the lower surface of the glass material, which is in close contact with the forming surface, is a part that is located away from the central part of the lower surface of the glass material. At the start of molding, only the edge portion of the lower surface of the glass material is in contact with the forming surface of the template. The lower surface of the located glass material and the forming surface are separated over the entire area inside the edge part moving towards the geometric center of the glass material.

When the glass material is subjected to thermal plasticization only with the edge part of the lower surface in direct contact with the forming surface of the template in this way, the central part of the softened glass material is deformed vertically under its own weight, as it is heated. As shown in FIG. 2 (b), the central portion of the lower surface comes into contact with the forming surface. This change in the shape of the lower surface is the reason that the upper surface of the glass material undergoes slight compression and changes shape. In the present invention, since the glass material is supported by the support member only in the upper edge portion of the side surface, this compression of the upper surface of the glass material eliminates contact between the glass material and the support member. As shown in FIG. 13 (b), the support member is then separated from the glass material. In addition, since the edge of the glass material has been in a state of contact with the forming surface since the beginning of molding, preventing expansion due to thermal expansion, a state of no contact can be maintained between the lower part of the side surface of the glass material and the supporting member. In this way, at least when the entire lower surface of the glass material is in close contact with the forming surface of the template, the glass material can be separated from the support element. Thus, high-precision molding becomes possible by arranging the glass material on the template without fusing the glass material with a support member to prevent shear during thermal plasticization. In addition, since the lower part of the side surface of the glass material does not come into contact with the support member during molding, deformation and the like caused by pressure due to differences in thermal expansion can be prevented.

By providing support in the aforementioned manner, since contact between the glass material and the support member is eliminated as the glass material changes shape (the displacement of the central portion of the lower surface of the glass material in the direction of contact with the forming surface, and the accompanying compression of the upper surface of the glass material) due to thermal plasticization, there is no need to remove the support member to prevent fusion. Thus, molding can be carried out without removing the support element from the template, and without causing fusion of the glass material and the support element. In the above embodiment, it is desirable to maintain the support element in a safe state on the template, at least until the upper edge part of the side surface of the glass material is separated from the support element, and, further, until the formation of the upper surface of the glass material is completed. This enables precise positioning and improves molding accuracy.

The support member and the support provided by the support member will be described in detail below.

As indicated above, the support member used in the present invention is desirably shaped to support at least a portion of the upper edge portion of the side surface of the glass material, while maintaining a state of non-contact with the bottom portion of the side surface of the glass material. An example of such a support element is an annular element that is circular in shape along the edge surface of the circumference of the glass material, with a space in the part on top of which the glass material is located, as shown in sectional view, shown in Fig. 14. A top view of the annular element shown in FIG. 1 is shown in FIG. 14 (a), and a cross section along the section line I-I in FIG. 14 (a) is shown in FIG. 14 (b).

The above support element is sufficient to support at least part of the upper edge part of the side surface of the glass material. However, in order to stably support the glass material, it is desirable that the glass material is supported by contact with at least three points on the upper edge of the side surface of the glass material, and it is preferable that the glass material is supported by contact with the entire circumference of the upper edge part of the side surface of the glass material. For example, the annular element shown in FIG. 2, as shown in FIG. 13, has a protruding portion 1101 and an edge surface 1102 on the inner circumference. The protruding portion 1101 may be in contact with the upper edge portion of the side surface of the glass material to support the glass material. The edge surface 1102 faces the side surface of the glass element, but does not come in contact with it. The protruding part is not necessary to arrange around the entire inner circumference of the support element, it can be partially provided. For example, three or more protruding parts can be placed on the inner circumference of the support element, preferably at equal angles. However, it is desirable that the protruding part be in the form of a ring located completely around the inner circumference of the support element in order to provide a reliable location and support.

The shape of the protruding portion 1101 can be determined by considering the shape and dimensions of the disposable and supported glass material. For example, when the protruding part 1101 is made completely surrounding the inner circumference of the support element, and glass material with an external diameter of 60 to 90 mm is used, the inner diameter of the protruding part 1101 can be set within the tolerance range from -0 to +0.05 mm of the external shape of the glass material based on the outer diameter of the glass material. The width (d in FIG. 13) of the contact portion of the protruding portion 1101 with the upper edge portion of the side surface of the glass material is desirably sufficient to support the glass material and to separate after softening. For example, when the width (D in FIG. 13) of the side surface of the glass material is from 3 to 20 mm, this is preferably from about 10 to 20 percent of D. It is desirable to position the upper edge portion of the protruding portion 1101 so as to contact the upper edge of the edge portion glass material.

As shown in FIGS. 2 and 13, the support member can be mounted and fitted to the upper part of the edge of the template. The shape of the edge surface 1105 installed in the template is set so that it matches the shape of the template. For example, when using glass material with the above external diameter, a tolerance of +0.1 to 0.2 mm can be specified based on the external diameter of the template. In addition, a stepped support portion can be provided on the side surface of the template and fitted to the lower surface of the circumference of the support member for more stable support of the support member.

When using a covering element, such as described above, as shown in FIG. 13, for example, the edge surface 1103 in the stepped portion of the circumference of the glass material and the opening of the dust cover are jointly adapted to the location of the dust cover. The width of the edge surface 1103 may have a sufficient area relative to the opening of the dust cover; for example, about 6 to 8 mm can be used. The surface of the edge surface 1103 may be mirrored to improve the tightness of the fit in the dust cover.

The aforementioned support element supports at least the upper edge part of the side surface of the glass material located on the protruding element 1101 provided on the part of the inner circumference, preferably supports the entire circumference of the upper edge part of the side surface of the glass material, and arranges the glass material in a desired position on the forming surface of the template. For example, such a desired position may be a position in which the geometric center of the forming surface of the template corresponds to the optical center or geometric center of the glass material.

The above support element is preferably made of heat-resistant material. Heat-resistant stainless steel is desirable as a heat-resistant material; suitable, for example, is an austenite-based material. Austenite-based stainless steel materials have compositions containing C, Si, Mn, P, S, Ni, Cr, and Mo. The proportion (mass percent) of the components contained, for example, is less than or equal to 0.08 percent C, less than or equal to 1.50 percent Si, less than or equal to 2.00 percent Mn, less than or equal to 0.045 percent P, less than or equal to 0.030 percent S , from 19.00 to 22.00 percent Ni, from 24.00 to 26.00 percent Cr. Specifically, SUS310S with a high chromium content based on a high nickel content can be used.

The processing of the shape of the support element can be carried out by a multi-purpose machine or a CNC milling machine. It is desirable to form an oxide film on the surface of the support member to increase the service life. The surface treatment used to form the film may be electropolishing, electrostatic coating, or the like.

In the present invention, it is desirable to use a template having through holes extending from the forming surface to the opposite surface from the forming surface, and suction through the through holes during molding is preferably used. By providing through holes in the forming surface, and applying suction in this manner, the time required to deform the glass material can be reduced, and productivity can be improved. As shown in the enlarged schematic drawings of FIG. 4, when using a template having irregularities, there remains a space between the forming surface and the glass material, as shown in FIG. 4 (b), even after thermal plasticization to bring the forming surface into tight contact with the lower surface of the glass material . The formation of this space has the effect of preventing fusion, as noted above. On the other hand, air remains in this space and air pockets form. When these air pockets remain between the forming surface and the glass material, the air is sometimes trapped without exhausting. However, these air pockets create a space between the forming surface and the glass material, creating the risk of making it difficult to control the shape of the glass material with the forming surface when the glass material comes into contact with the forming surface. Accordingly, when using a template having a forming surface with a predetermined roughness, as described above, it is desirable that through holes in the forming surface are provided and suction is performed to remove air pockets.

When performing suction using a coating element, as described above, the pulse of the suction pump sometimes becomes uneven when the seal created by the coating element is excessively dense. In addition, when the suction is carried out to the limit of the suction force of the suction pump, the suction through the through holes sometimes stops. Thus, when providing through holes in the forming surface, and performing suction, it is desirable to use a cover element with a given degree of breathability to control the flow rate during the suction process, and even outside the pulse of the suction pump. When a coating element having a predetermined degree of breathability is used, the formation of a certain degree of negative pressure inside the coating element causes air to flow from outside, making it possible to prevent suction stop due to an extremely negative pressure inside the coating element. The air that flows into the inside of the coating element from the outside is filtered by the coating element, preventing contamination by a foreign substance such as dust and waste, and preventing a problem of cleanliness.

In order to guarantee the prescribed breathability, it is therefore desirable that the covering element consist of a porous material. The porosity is desirably, for example, from 5 to 80 percent, preferably from 30 to 40 percent. When carrying out processing to prevent dispersion of particles, as described above, only the upper surface on the inside of the coating element can be treated in order to maintain the breathability of the side surface.

In the manufacture of the mold or part of the mold for eyeglass lenses of the present invention, and the use of a template having through holes, it is desirable to arrange the holes of the through holes on the side of the forming surface so as not to overlap the positions relating to the measurement parts of the refractive index in the eyeglass lenses on the bottom the surface of the glass material when the forming surface of the template and the lower surface of the glass material are in close contact.

Namely, the above mold can be used in the manufacture of spectacle lenses by installing two molds on an annular gasket and pouring a solution of the lens starting material into the cavity formed by the molds and gasket for polymerization. The template used in this method is usually constructed in accordance with procedures including determining the shape of the surface of the eyeglass lens (determining the design parameter), then converting the design parameters of the eyeglass lens into the shape of the surface of the mold (determining the design parameters of the mold), and then converting the design parameters mold in the form of a surface pattern. Each of these transformations can be carried out by a known method, and preferably carried out by the method of determining the surface shape of the present invention described above. The shape of the surface located in the cavity of the mold, which is made using a template having a surface shape defined in this way, is transferred to the eyeglass lens, allowing to obtain optically functional surfaces. However, when there is an unintended deformation in the mold, obtained due to suction through the through holes, an optically functional surface is formed at the end with a shape different from the shape of the design parameters. The position in the eyeglass lens that has the greatest effect on optical performance is the reference point for measuring optical power. When there is a significant shift in the surface shape of a given part from the design parameters, it becomes difficult to obtain a spectacle lens with a given refractive index. Thus, in order to prevent the aforementioned deformation in places of the surface of the mold, which are transferred to the positions in the eyeglass lens at which the reference points for measuring the optical power are formed, it is desirable to arrange the holes of the through holes on the forming surface of the template so that they do not overlap the positions related to reference points for measuring the optical power on a spectacle lens on the lower surface of the glass material when the forming surface and the lower surface of the glass material are in a raft th contact. Thus, it is possible to obtain a mold (or part of it) for spectacle lenses that is free from deformation caused by absorption at positions corresponding to the reference points for measuring optical power, and this mold can be used to produce high-quality spectacle lenses with specified optical characteristics.

The location of the above through holes will be described below.

The number of through holes may be equal to one, but it is desirable to provide multiple through holes. The number of through holes formed on the template is not particularly limited, and can be appropriately determined. When the forming surface has a diameter of from about 80 to 100 mm, for example, from about 6 to 60 through holes can be located on the forming surface. As shown in FIG. 5 (a), a plurality of through holes can be spaced evenly at equal intervals over the entire forming surface. However, it is desirable to arrange these through holes so that the positions corresponding to the reference points for measuring the optical power of the spectacle lens on the lower surface of the glass material do not overlap the holes on the side of the forming surface when the forming surface and the lower surface of the glass material are brought into tight contact, as described above.

It is desirable to arrange the through holes in the template at least in the edge part of the forming surface, for a plurality of through holes it is preferable to be located within a range smaller than the outer diameter of the glass material on at least two concentric circles.

In the present description, the term "edge part of the forming surface" means the part surrounding the Central part of the forming surface. The term "central part of the forming surface" means, for example, a position from the center of the forming surface to about 1/2 of the radius.

5 (b) and (c) are examples of through holes that were located at the edge of the forming surface, but not close to the geometric center of the forming surface of the template. In these cases, it is also desirable to arrange through holes so that the positions corresponding to the reference points for measuring the optical power of the spectacle lens on the lower surface of the glass material do not overlap the holes on the side of the forming surface when the forming surface and the lower surface of the glass material are in tight contact. In addition, in FIG. 5 (b), the through holes in the edge portion are spaced at equal intervals on a plurality of concentric circles. The number of through holes located per unit area in positions near the center is small, and the number of through holes per unit area increases with distance from the center. That is, the through holes are located with increasing from the Central part towards the edge part (with several through holes near the center and many through holes in the edge part). As a result of the study conducted by the authors of the present invention, the location of the through holes in this way, especially when using glass material as a glass material, can guarantee reliable moving properties. In addition, the authors of the present invention have found that deformation by thermal plasticization can be carried out uniformly over the entire surface, and distortion inside the glass material can be suppressed. The reasons for this are not yet fully known, but it is assumed that they are as follows.

There are properties whereby the rate of deformation of glass materials and the tendency that such deformation occurs is greatest at the center, while the rate of deformation is relatively low and the deformation tends not to occur in the perimeter portion. As shown in FIG. 3, when the lower surface of the glass material is convex and the forming surface of the template is concave, the supporting part of the glass material is the edge portion of the circumference of the glass material. In this case, the edge part along the perimeter of the glass material, which is supported by the forming surface, tends not to move even during the process of thermal plasticization, acting as a suppressing factor on the deformation caused by softening along the perimeter of the edge part. It is believed that the peripheral portion undergoes a low deformation rate and tends not to undergo shape deformation. However, there is no supporting part in the center, therefore, there is no factor to suppress deformation caused by softening. The authors of the present invention found that the real deformation of the glass material begins in the Central part, propagating sequentially to part of the perimeter.

However, the difference between the strain rate in the edge part and the central part of the glass material sometimes becomes a factor creating distortion inside the glass material. This is because when the central part of the glass material is deformed by thermal plasticization of the first, and the deformation does not occur in the edge part, distortion develops between the central part and the edge part of the glass material. The fact that the strain rate in the part along the perimeter is low, and that deformation does not occur, also become factors that reduce the accuracy of the transfer. Thus, numerous through holes are located in the edge part of the forming surface of the template, the distribution of the suction force is increased in the edge part where deformation does not occur, and several through holes are located in the central part that undergoes deformation in order to stably distribute the suction force per unit area. It is believed that this guarantees reliable transfer properties, allows the deformation of thermal plasticization to occur evenly over the entire surface, and prevents distortion inside the glass material. In this way, by arranging the through holes, it is possible to control the difference in the strain rates and the tendency to deform due to the position in the glass material, enhancing the reproducibility of the transfer of the glass shape. Suction through the through holes, as stated above, provides the advantages of reducing the time of deformation of the glass material and increasing productivity.

The location of the through holes can be selected respectively for each molded material. For example, FIG. 5 (b) is suitable in the case of a relatively large bend, for example, when the mold to be machined is an arc with an average curvature equal to or greater than 8, and FIG. 5 (c) is suitable in the case of a relatively small bend, such as an arc with an average curvature equal to or less than 5. In addition, as shown in FIG. 5 (a), the location of the through holes uniformly over the entire surface is suitable for molds with free-form surfaces, such as lenses with a gradual increase in optical power.

In order to conduct high-precision molding during suction through the through holes, it is desirable that the diameter of the through holes, the viscosity of the glass material during the suction process, the thickness of the glass material and the suction pressure satisfy equation 1 below. In particular, as indicated above, when using a template with a very rough forming surface and conducting an excessive level of suction through the through holes, there is a risk that the surface roughness of the forming surface and the shape of the through holes will affect the shape of the upper surface of the glass material. Thus, it is desirable to satisfy equation 1 during suction. It is also desirable to carry out suction under conditions satisfying Equation 1 in order to equalize the pulse of the suction pump, and to use a coating element having a suitable degree of breathability, as described above.

[Number 3]

Equation 1

More precisely, equation 1 can be expressed as equation 1-1 below.

Equation 1-1

In the above equations, H denotes the diameter (mm) of the through holes, V denotes the viscosity (poise) of the glass material during the suction process, T denotes the thickness (mm) of the glass material and P denotes the suction pressure (mm Hg / cm ² ), where 1 poise = 0, 1 Pa · s K denotes a coefficient; 1.8 to 3.0 × 10 ^-9 is suitable.

More precisely, the diameter of the through holes can be from 0.3 to 0.5 mm, the viscosity of the glass material during the suction process can be from 6.81 × 10 ⁺⁷ to 1.26 × 10 ⁺⁸ poise, the thickness of the glass material can be from 4 to 7 mm and the suction pressure can be from 80 to 120 mm Hg / cm ² (= from 1.0 × 10 ⁴ to 1.6 × 10 ⁴ Pa / cm ² ).

You can take the thickness of the glass material identical in the molding process. In the above equation 1, the thickness of the glass material is the thickness at the beginning of molding. In the present invention, based on the above equation 1, the temperature of the glass material in the process of thermal plasticization can be controlled by a thermocouple or the like, the viscosity of the glass material can be calculated and the suction pressure can be set. The suction pressure can also be set based on the relationship between temperature and viscosity, the latter being calculated from the viscosity properties of the glass material used.

The suction method will be described below based on FIG. 6 is a drawing of an example of a suction method. However, the present invention is not limited to the embodiment shown in FIG. 6.

As shown in FIG. 6, the template 402 on which the glass material was placed is placed on the suction base 403. The suction is carried out using the suction base 403 and a portion of the suction pump 404. The suction base 403 is a hollow plate base where the templates are located , curved in a concave shape. It is made of material such as heat-resistant stainless steel (SUS310S). Air inlets 407 are located at locations where patterns are located on the upper surface of the suction base. Outlets for supplying suction air to the suction pump are located on the lower surface of the suction base and are connected to the suction terminal 405, which is connected to the suction pump. It is desirable to set the suction pressure in order to satisfy the above equation 1; for example, it can be set from 80 to 120 mm Hg (= from 1.0 × 10 ⁴ to 1.6 × 10 ⁴ Pa).

A specific embodiment of a method for manufacturing a molded article of the present invention will be described below. However, the present invention is not limited to the embodiment described below.

First, preferably in a clean room, the template is placed with the forming surface on top. When using the support element in the manner described above, the support element is placed in the edge part of the forming surface and the stepped support element of the side surface. The glass material is then placed at a predetermined position on the forming surface along the support member. The edge surface of the side of the glass material is reliably supported horizontally by the support element. The edge surface of the edge of the lower surface of the glass material is in contact with the forming surface of the template in the vertical direction, and is reliably supported. The central part on the side of the contact surface of the glass material with the template is separated from the forming surface of the template. The separation distance varies depending on the shape of the forming surface of the template and the lower surface of the forming surface of the material, but usually ranges from 0.1 to 2.0 mm.

Then, the lid member is preferably placed in the support member and installed. After covering the open part on top of the template on which the glass material was located with an element that is a cover, they are sent from a clean room to the electric furnace. The assembly of the template, the support element, the glass material and the lid element is placed on the suction base of an electric furnace, heat treated in an electric furnace, and a suction treatment is carried out using a suction device. To reliably prevent contamination with a foreign substance, the location of the glass material on the template and the like is preferably carried out in a clean room in this way.

In an electric furnace, it is possible to carry out the processing by thermal plasticization with effective temperature control based on a given temperature program. As an electric furnace, a batch electric furnace or a continuous electric furnace can be used. A description of the batch electric furnace will be given first.

A batch electric furnace is a device in which the workpiece is placed in a relatively small, enclosed space, and the temperature inside the furnace is changed in accordance with a predetermined temperature program. It is equipped with many sensors. Temperature is measured by a variety of sensors, and each heater can be controlled to control the temperature. In a batch electric furnace for thermal plasticization, there is a supporting part holding the workpiece. Moreover, the support part can be moved inside the furnace. Imbalances in the temperature distribution due to the location inside the furnace can be balanced by the control of the support element.

A continuous electric furnace will be described later.

A continuous feed electric furnace is an apparatus having an input and an output in which the workpieces are treated by heating by passing through the interior of the electric furnace with a predetermined temperature distribution for a certain period using a conveying device such as a conveyor. A plurality of heaters are designed in the continuous feed electric furnace to create and discharge heat, and the air circulation control device can maintain uniform heat distribution within the furnace.

PID controllers can be used in temperature control with each sensor and heater in an electric furnace. PID controllers are a control method for detecting deviations between the temperature set by the program and the actual temperature, and returning (feedback) deviations from the set temperature to 0. PID controllers are a method for obtaining the output in the “Proportional”, “Integral”, “Differential” way when calculating the deviation. The basic equation for PID controllers is given below.

[Number 4]

The basic equation for PID controllers is:

P term:

I term:

D term:

insofar as

In this way:

In the above equations, e stands for deviation, K stands for growth (growth with the subscript P stands for proportional growth, growth with the subscript I stands for integral growth, and growth with the subscript D stands for differential growth), Δ (DELTA) t stands for sample time (time sampling, reference frequency) and the subscript n denotes the real time.

Using PID controllers can increase the accuracy with which the temperature inside the furnace is controlled to change the distribution of the amount of heat based on the shape and number of loaded workpieces. A static system (e.g., a balancer) can be adopted for movement inside an electric furnace.

In a particular embodiment, an electric furnace with a continuous loading, which can be used in the present invention, the system of movement is the static system, the temperature controls are PID temperature controls, the temperature measurement device is "K thermocouple 30 point made Platina", a maximum temperature employed is 800 ° C, the commonly used temperature range is from 590 to 650 ° C, the internal atmosphere is dry air (free from oil and dust), The atmospheric calibration is in the form of an inlet air curtain, an internal purge of the furnace, and an outlet air curtain, the temperature control accuracy is ± 3 ° C, the cooling system is air-cooled, and the suction points are located in 3 positions inside the furnace.

The temperature inside the electric furnace can be raised from room temperature to a temperature above the glass transition temperature, but lower than the softening temperature of the glass, by heating and raising the temperature. The temperature is desirably kept lower than the softening temperature of the glass for a certain period, and then gradually reduced to room temperature.

The temperature is controlled inside the furnace in a cycle with a given duration.

An example of temperature control in which an individual cycle lasts 17 hours and a glass substance is used as a glass material will be described below. However, the present invention is not limited to the embodiment described below.

Temperature control of the furnace can be carried out in seven stages. The first step (A) is a preheating step. The second stage (B) is the stage of rapid heating and temperature rise. The third stage (C) is the stage of slow heating and raising the temperature. The fourth stage (D) is the stage in which a constant temperature is maintained. The fifth step (E) is a slow cooling step. The sixth stage (F) is a rapid cooling step. And the seventh stage (G) is the natural cooling stage.

In the preheating step (A), which is the first step, a constant temperature close to room temperature is maintained for 90 minutes. This is done in order to establish a uniform temperature distribution throughout the glass material and to facilitate the reproducibility of the temperature distribution of the glass material by temperature control during the processing of thermal plasticization. The temperature that is maintained can be any temperature around room temperature (from about 20 to 30 ° C).

In the rapid heating step (B), which is the second step, the heating is carried out for about 90 minutes by raising the temperature from room temperature (e.g. 25 ° C) to a temperature 50 ° C below (also subsequently referred to as “T1") glass transition temperature ( also subsequently referred to as ″ T _g ″) at a rate of about 4 ° C./min, for example. Then, in the slow heating step (C), which is the third stage, the heating is carried out for 120 minutes by raising the temperature from temperature T1 to a temperature of about 50 ° C below the softening temperature of the glass (also subsequently called "T2") at a speed of 2 ° C / min, for example. In the step of maintaining a constant temperature (D), which is the fourth step, the temperature T2 is maintained for about 60 minutes.

Glass material that has been heated to a temperature of T2 is heated for about 30 minutes in the step of maintaining a constant temperature. Then carry out heating for another 30 minutes at a temperature of T2. When using a template having through holes as described above, suction processing through the through holes of the template can be carried out over the past 30 minutes. The suction treatment can be carried out by the operation of a suction pump located outside the electric furnace. As shown in FIG. 6, the suction pump 404 is connected to the suction terminal 405, the suction base 403, and through holes in the template, respectively. During suction by the suction pump, negative pressure is created. Negative pressure passes through the through holes in the template, applying suction to the glass material located on the template. The creation of suction from 80 to 150 mm Hg (= from 1.0 × 10 ⁴ to 1.6 × 10 ⁴ Pa) through the suction inlet of the installed heat-resistant base of the template begins 30 minutes after the start of heating at temperature T2 in an electric furnace. First, a suction pump 404 is turned on outside the furnace, and negative pressure is created through the suction terminal 405 in the interior of the suction base, which has a hollow structure. The suction base, in which negative pressure was created, communicates with through holes on the bottom surface of the template. Through holes on the lower surface of the template penetrate to the forming surface at the top of the template and carry out suction by applying a negative suction pressure to the glass material located on the template. As indicated above, the use of an element representing a cover with a given breathability is desirable when conducting suction through the through holes.

Once suction is complete, the glass material is deformed by plasticization on the template. Once the deformation by plasticization is completed, cooling is carried out. In the slow cooling step (E), fifth stage, cooling is carried out, for example, for 300 minutes at a speed of 1 ° C / min to a temperature 100 ° C below T _g (also subsequently referred to as “T3") to fix the shape change caused by deformation. The slow cooling step also includes annealing elements to remove glass distortion.

Then, in the rapid cooling step (F) of the sixth step, cooling is carried out to about 200 ° C at a speed of about 1.5 ° C / min. There is a risk that the glass that was softened and the template will be damaged due to intrinsic thermal contraction and the difference between each other in the coefficients of thermal expansion when the temperature changes. Accordingly, the rate of change of temperature is preferably small to the extent that damage does not occur.

In addition, when the temperature drops to a temperature equal to or more than 200 ° C., a quick cooling step (G), a seventh step, is carried out. In the rapid cooling step (G), natural cooling is carried out from 200 ° C. to room temperature.

Once the softening treatment is completed, the lower surface of the glass material and the forming surface of the template exactly match each other. The upper surface of the glass material is deformed due to deformation of the shape of the lower surface of the glass material, forming the desired optical surface. Once the glass optical surface has formed in the above steps, the glass material is removed from the template to form a molded article. The thus obtained molded product can be used as a mold for eyeglass lenses (preferably multifocal eyeglass lenses). Alternatively, a part, such as an edge part, can be removed, and then the molded product can be used as a mold for eyeglass lenses.

Brief Description of the Drawings

Figure 1 shows an example (sectional view) of glass of substantially equal thickness in the normal direction.

Figure 2 shows a schematic drawing of the state of contact between the template and the glass material before and after softening.

Figure 3 is a drawing showing the deformation of a viscoelastic material in the form of sheet glass.

Figure 4 shows an enlarged schematic drawing of the state of contact between the template and the glass material before and after thermal plasticization in a template having a forming surface of a given roughness.

Figure 5 shows a specific example of the location of the through holes on the forming surface of the template.

6 is a drawing showing an example of a suction method.

7 is a distribution diagram of S degree (medium degrees) in a progressive multifocal lens.

Fig. 8 is a distribution diagram of C degree (cylindrical degrees) in a progressive multifocal lens.

Fig.9 is a top view corresponding to the distribution of S degrees in Fig.7.

FIG. 10 is a plan view corresponding to the degree distribution C in FIG.

11a is a drawing showing a cross section of a plastic lens with a gradual increase in optical power.

11b is a drawing showing a cross section of a centrally symmetric aspherical plastic lens with a gradual increase in optical power.

11c is a drawing showing a cross section of a glass lens with a gradual increase in optical power.

12 is a visual depiction of the contact between the lower surface of the molded material and the forming surface of the template.

Fig is an enlarged schematic drawing of the state of contact between the support element and the side surface of the glass material before and after softening.

Fig.14 is a top view of the annular element shown in Fig.2, shown in Fig.14 (a), and a section along the section line I-I in Fig.14 (a) is shown in Fig.14 (b).

Claims (35)

1. A method of manufacturing a molded product, comprising molding the upper surface of the glass material, which was placed on the forming surface of the template so that at least three points on the lower surface of the edge of the glass material were in contact with the forming surface, and the Central part of the lower surface of the glass material was separated from the forming surface, and for a lens with a gradual increase in optical power, three points on the edge of the lower surface of the glass material consist of two points on the edge of the lower surface of the glass material, which are located on the side relative to the reference point for measuring the far optical power of the lens with a gradual increase in optical power, and one point, which is located on the side of the reference point for measuring the near optical power, and for a single-focal lens the inner circumference of the edge of the lower surface of the glass material was in contact with the forming surface; the glass material is heated to a temperature that allows deformation to bring the lower surface of the glass material into tight contact with the forming surface and to obtain a molded product, moreover, glass having a upper and lower surface that is spherical in shape is used as glass material, and a template with a forming surface, which is a free-form surface other than a spherical surface, the upper surface of the glass material after molding and forming the surface of the template has an approximately offset relationship, whereby the space in the normal direction is approximately equal in all positions. 2. The production method according to claim 1, in which the glass material has a substantially equal thickness in the normal direction. 3. The production method according to claim 1, in which the upper and lower surfaces of the glass material are parts of spherical surfaces having a common center. 4. The production method according to claim 2, in which the thickness of the glass material in the normal direction is essentially unchanged before and after molding. 5. The production method according to claim 4, in which the glass material has a thickness in the range from 2 to 10 mm in the normal direction. 6. The production method according to claim 5, in which the glass material has an outer diameter in the range from 60 to 90 mm. 7. The production method according to any one of claims 1 to 6, in which the glass material is placed so that at least three points on the lower surface of the edge part of the glass material are in contact with the forming surface, and the central part of the lower surface of the glass material is separated from the forming surface. 8. The production method according to claim 7, in which
a molded product is a mold or part of a mold for a spectacle lens,
a spectacle lens is a lens with a gradual increase in optical power, having one reference point for measuring far optical power and one reference point for measuring near optical power,
three points on the edge of the lower surface of the glass material, consist of two points on the edge of the lower surface of the glass material, which are located on the side relative to the reference point for measuring the far optical power of the lens with a gradual increase in optical power, and one point that is located on the side of the point reference for measuring near optical power. 9. The production method of claim 8, in which two points that are located on the side relative to the reference point for measuring far optical power are located symmetrically relative to the line on the lower surface of the glass material related to the main meridian that passes through the reference point for measuring far optical power of the lens with a gradual increase in optical power. 10. The production method according to claim 8 or 9, in which the lower surface of the glass material has a spherical shape, the average curvature of which is approximately identical to the average curvature at the reference point for measuring the far optical power of the lens with a gradual increase in optical power. 11. The production method according to claim 7, in which
the molded product is a mold or part of a mold for a single-focal spectacle lens,
the glass material is placed so that the entire inner circumference of the edge portion of the lower surface of the glass material is in contact with the forming surface, and the central part of the lower surface of the glass material is separated from the forming surface. 12. Glass material for use in a molding method in which the upper surface of the glass material that has been placed on the forming surface of the template, the forming surface being a free-form surface other than a spherical surface, is molded into an approximately offset surface relative to the forming surface of the template, that is, geometrically the center of the glass material or at the optical center point containing a point for measuring far optical power, the degree of change in thickness, measured normal direction is less than or equal to 1.0%, to obtain a molded product by heating the glass material to a temperature permitting deformation to bring a lower surface of the glass material into tight contact with the forming surface,
which has upper and lower surfaces that are spherical in shape and also has substantially equal thickness in the normal direction. 13. Glass material according to item 12, in which the thickness of the glass material in the normal direction is essentially unchanged before and after molding. 14. The glass material according to item 13, in which the glass material has a thickness in the range from 2 to 10 mm in the normal direction. 15. The glass material according to 14, in which the glass material has an outer diameter in the range from 60 to 90 mm 16. Glass material according to any one of paragraphs.12-15, in which the glass material is placed so that at least three points on the edge of the lower surface of the glass material are in contact with the forming surface, and the central part of the lower surface of the glass material is separated from the forming surface . 17. Glass material according to clause 16, in which
a molded product is a mold or part of a mold for a spectacle lens,
a spectacle lens is a lens with a gradual increase in optical power, having one reference point for measuring far optical power and one reference point for measuring near optical power,
three points on the edge of the lower surface of the glass material consist of two points on the edge of the lower surface of the glass material, which are located on the side relative to the reference point for measuring the far optical power of the lens with a gradual increase in optical power, and one point that is located on the side of the reference point for measuring near optical power. 18. Glass material according to 17, in which two points that are located on the side relative to the reference point for measuring the far optical power are located symmetrically relative to the line on the bottom surface of the glass material related to the main meridian that passes through the reference point for measuring the far the optical power of the lens with a gradual increase in optical power. 19. The glass material according to claim 18, wherein the lower surface of the glass material has a spherical shape, the average curvature of which is approximately identical to the average curvature at the reference point for measuring the far optical power of the lens with a gradual increase in optical power. 20. The glass material according to clause 16, in which
the molded product is a mold or part of a mold for a single-focal spectacle lens,
the glass material is placed so that the entire inner circle on the edge of the lower surface of the glass material is in contact with the forming surface, and the central part of the lower surface of the glass material is separated from the forming surface. 21. A method for determining the shape of the lower surface of the glass material for use in a molding method in which the upper surface of the glass material that is placed on the forming surface of the template is molded into a desired shape having an average curvature that is approximately identical to the average curvature at the reference point for measuring the far optical power of the lens with a gradual increase in optical power, as well as by determining three points consisting of the center of a spherical surface and any two opposite points located a circle for single-vision lenses, to obtain the molded article by heating the glass material to a temperature permitting deformation to bring a lower surface of the glass material into tight contact with the forming surface, wherein
the forming surface is a free-form surface other than a spherical surface,
Assuming that the glass material has upper and lower surfaces that are spherical in shape and has substantially equal thickness in the normal direction, the shape of the forming surface is determined based on the desired shape of the upper surface and the shape of the forming surface, which was determined based on the thickness of the glass material in the normal direction. 22. The method according to item 21, in which the thickness of the glass material in the normal direction is essentially unchanged before and after molding. 23. The method according to item 22, in which the glass material has a thickness in the range from 2 to 10 mm in the normal direction. 24. The method according to item 23, in which the glass material has an external diameter in the range from 60 to 90 mm 25. The method according to item 21, in which the glass material is placed so that at least three points on the edge of the lower surface of the glass material are in contact with the forming surface, and the Central part of the lower surface of the glass material is separated from the forming surface. 26. The method according A.25, in which
the molded product is a mold or part of a mold for a single-focal spectacle lens,
the glass material is placed so that the entire inner circle on the edge of the lower surface of the glass material is in contact with the forming surface, and the central part of the lower surface of the glass material is separated from the forming surface. 27. A method for determining the shape of the lower surface of the glass material for use in a molding method in which the upper surface of the glass material that is placed on the forming surface of the template is molded into the desired shape to obtain a molded product by heating the glass material to a temperature allowing deformation to bring the lower surface of the glass material into tight contact with the forming surface, in which
the molded product is a mold or part of a mold for a single-focal spectacle lens,
a spectacle lens is a lens with a gradual increase in optical power, having one reference point for measuring far optical power and one reference point for measuring near optical power,
the forming surface is a free-form surface other than a spherical surface,
on the assumption that the glass material has upper and lower surfaces that are spherical in shape and has substantially equal thickness in the normal direction, the shape of the lower surface is defined as a surface having a spherical shape, the average curvature of which is approximately identical to the average curvature at the reference point for measuring the far optical power of the lens with a gradual increase in optical power. 28. The method according to item 27, in which the thickness of the glass material in the normal direction is essentially unchanged before and after molding. 29. The method according to p, in which the glass material has a thickness in the range from 2 to 10 mm in the normal direction. 30. The method according to clause 29, in which the glass material has an outer diameter in the range from 60 to 90 mm 31. The method according to clause 30, in which
the glass material is placed so that at least three points on the edge of the lower surface of the glass material are in contact with the forming surface, and the central part of the lower surface of the glass material is separated from the forming surface. 32. The method according to p, in which three points on the edge of the lower surface of the glass material consist of two points on the edge of the lower surface of the glass material, which are located on the side relative to the reference point for measuring the far optical power of the lens with a gradual increase in optical power, and one point that is located on the side of the reference point for measuring the near optical power. 33. The method according to p, in which two points that are located on the side relative to the reference point for measuring the far optical power are located symmetrically relative to the line on the lower surface of the glass material related to the main meridian that passes through the reference point for measuring the far the optical power of the lens with a gradual increase in optical power. 34. A method of manufacturing a molded product, comprising molding the upper surface of the glass material, which was placed on the forming surface of the template, to obtain the molded product by heating the glass material to a temperature that allows deformation, to bring the lower surface of the glass material into tight contact with the forming surface, in which
a template having a forming surface being a free-form surface other than a spherical surface is used as a template,
glass material, which has upper and lower surfaces that are spherical in shape, has substantially equal thickness in the normal direction, and the shape of the lower surface of which has been determined by the method according to any one of claims 21-33, is used as glass material. 35. The production method according to clause 34, in which the upper surface of the glass material is molded into an approximately offset surface relative to the forming surface of the template.

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