JPH09328323A - Optical element, forming of optical element and apparatus for forming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical element without causing a flash or chipping of a formed product in a parting line even when forming a lens having a large wall thickness, e.g. a concave lens and without being restricted by a takeout method by using a specific mold. SOLUTION: This optical element is obtained by using a mold in which a boundary part of a forming surface with a mold member 16 in a ring member 2 is brought into linear contact with the mold member 16 and fixed in a state thereof brought into pressure contact in the direction of close adhesion to the ring member 16 in the optical element prepared by pressing a material heated in a deformable state, cooling the pressed material in a cavity formed by providing a releasing part with the ring member 2 forming the outer periphery of at least one of a pair of mold parts and then taking out the formed product from the mold to thereby afford a surface corresponding to the forming surface of the mold. Furthermore, the mold is preferably fitted even in a plane parallel to the optical axis of the forming surface of the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element obtained by press-molding a heated material, a molding die apparatus therefor, and a molding method.

[0002]

2. Description of the Related Art In recent years, an aspheric lens has been used in an optical system such as a camera or a video camera, which contributes to downsizing of the optical system and cost reduction. As a method for efficiently manufacturing the aspherical lens, a method is known in which a material is sandwiched between molding dies having a predetermined surface accuracy and press molding is performed. However, since the lenses used in the optical system are relatively strict in accuracy and appearance, as a lens shape that can be molded by such a method, production has been performed mainly on convex lenses. However, there are also demands for concave lenses whose surface transfer is difficult and lenses whose thickness varies greatly, and various molding methods have been improved.

As one of them, in a concave lens having a large peripheral wall thickness with respect to the center, it is necessary to devise the peripheral shape of the mold so that the peripheral glass does not escape during molding.

For example, Japanese Patent Application Laid-Open No. 7-17730 describes the contents of "mold for molding a ball-deficient meniscus lens", in which the molding surface is located at the outer periphery of the ball-cut portion protruding in the center. By forming the shape of the molded part into a concave surface, the volume of the peripheral part of the molded product is reduced and the amount of heat shrinkage of the glass is suppressed,
It achieves good surface transferability without sink marks on the outer peripheral portion.

In Japanese Utility Model Laid-Open No. 4-118428, although not a concave lens shape, a molding die for irregularly shaped elements in which the wall thickness once increases from the center to the outer circumference and then decreases toward the outer circumference to form a knurled surface is described. Has been done. In this case, two mold members are used in the central part and the outer peripheral part of the molding surface, and the parting line near the molding surface is inclined or perpendicular to the center axis of the mold. When the glass material is pressed, the two mold members come into close contact with each other, and it is possible to prevent the occurrence of burrs on the parting line.

In addition to the concave lens shape, the lens face may be formed at the same time as molding, and this face may be used for positioning in a later assembling process, but forms the outer periphery of the mold. When forming this lobed surface with a ring member or a barrel mold, positioning with the mold is not performed directly on the molding surface of the mold, but a new positioning portion is formed on the outer periphery of the molding surface. For example, the fitting is performed by a cylindrical portion that is a surface parallel to the optical axis. Alternatively, in some cases, the outer periphery of the molded product has been centered in a post process.

[0007]

However, first of all, regarding a concave lens whose surface is difficult to transfer and a lens whose thickness varies greatly, it is not always possible to deal with various shapes required in the above-mentioned conventional example. There wasn't.

That is, according to Japanese Patent Laid-Open No. 7-17730, as seen in the drawings, the central portion and the outer peripheral portion of the molding surface of the mold are integrally formed, and the boundary portion between the central portion and the outer peripheral portion has a large edge or a large curvature (R Is small), and in such a shape, the grinding tool cannot enter the recess when the die is processed, and it is very difficult to process because it is a manual operation, which is not realistic.

Further, even if they are not integrated, there is no disclosure about a device for making them into two bodies. In other words, a parting line is always created when the split type is used, but regarding the treatment of burrs caused by glass entering there,
Not listed.

In that respect, in the actual Kaihei 4-118428, the center part and the outer peripheral part of the mold are composed of separate members, and the parting line has been devised so that a mold structure is formed to prevent the occurrence of burrs. There is.

However, since there are restrictions on the method of treating the parting line, the shape of the mold is naturally restricted.

That is, in this case, since the molds of the two members are brought into close contact with each other by the pressing force of the glass material, the shape of the parting line is 0 degree or more with respect to the plane perpendicular to the central axis of the mold. It is formed with an angle of 45 degrees or less. Therefore, if the parting line exceeds 45 degrees, the force of pushing the parting line is stronger than the force of adhering the parting line, and there is a possibility that the occurrence of burrs cannot be easily prevented.

In addition to such shape restrictions, at least one of the members near the parting line has a shape having an edge of 45 degrees or less, so that the workability and strength of the member are improved. However, there was a drawback that it caused restrictions.

Next, referring to the case where the boss surface of the lens formed by the ring is used for positioning, in the above-mentioned conventional example, the positioning of the ring with respect to the mold is not directly performed on the molding surface, Since it is made with a reference surface made secondarily, it is inevitable to include some errors during processing,
A lens having a severe optical axis accuracy has a drawback that it causes a poor accuracy.

An object of the first, fourth, and seventh inventions according to the present application is that the boundary portion of the ring member on the molding surface with respect to the molding member is in line contact with the molding member in a ring shape, and the molding member does not contact the molding member. By fixing in a state of being pressed in the direction of closely contacting with each other, when molding a lens having a large peripheral wall thickness such as a concave lens, even when using such a two-body mold, This enables a practical mold structure without causing burrs or chips in the molded product on the parting line, and without restrictions on how the parting line is taken.

Further, with the same configuration, the optical element, the mold structure, which makes the positional relationship between the molding surface of the lens and the lens core portion used for positioning in the subsequent process more precise,
And a molding method.

The objects of the second, fifth and eighth inventions of the present application are, in addition to the ring member and the mold member making line contact in a ring shape, a surface parallel to the optical axis of the molding surface of the mold member. However, due to the fitting, even when using a mold having a shape in which the centering effect of the ring member and the mold member is small by merely making line contact in a ring shape, such as a mold having an aspherical surface or a gentle curvature, The present invention enables close contact with a ring member and highly accurate positioning, and achieves an optical element, a mold structure, and a molding method similar to those of the first invention.

Further, an object of the invention according to the present application is that by pressing the upper and lower molds and the ring member so that the clearance between the release portions provided on the outer peripheral portion of the cavity is 0.8 mm or more. The pressure of the material at the time of molding is released to the release part so that an excessively high pressure is not applied to the parting line.

[0019]

In order to achieve the above object, the invention according to the present application provides a cavity formed by providing a releasing portion from a pair of molds and a ring member forming the outer circumference of at least one of the molds. In the optical element, in which the material heated to a deformable state is pressed, the molded product is taken out of the mold after cooling, and a surface corresponding to the molding surface of the mold is obtained, and the mold and the molding method, the ring is used. The boundary portion of the member on the molding surface with the mold member is fixed in a state of being in line contact with the mold member in a ring shape and being pressed against the mold member in a direction of being in close contact with the mold member. . According to this, it is possible to assemble the ring member and the die member at the boundary portion without a gap, and it is possible to assemble the ring member with respect to the molding surface of the die member with high accuracy. Further, even if a slight molding pressure is applied, the molding can be performed without forming a gap at the boundary.

In order to achieve the above object, in the invention according to the present application, the ring member and the mold member are fitted not only in the ring-shaped line contact but also in a surface parallel to the optical axis of the molding surface of the mold. It is characterized by

According to this, even when a die having a shape in which the ring member and the die member have a small centering effect only by making line contact in a ring shape, such as an aspherical surface or a die having a gentle curvature, The same effect as can be obtained.

In order to achieve the above object, the invention according to the present application is configured such that the clearance between the release parts provided on the outer periphery of the cavity formed by the upper and lower molds and the ring member is 0.8 mm or more. Is characterized by.

According to this, even in the case of a mold configuration in which a molding pressure is easily applied to the boundary between the ring member and the mold member,
The molding pressure applied to the boundary can be reduced.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

Description of Embodiments FIGS. 1 to 4 show a mold for an optical element according to an embodiment of the present invention, showing a configuration for molding a concave lens, in which a pressing operation by upper and lower mold members is completed, It shows a state where the molding of the glass lens is almost completed. See also FIG.
[Fig. 2] is a detailed view of the vicinity of a molded product, and Fig. 2 is a view showing the configuration of the entire molding die. Further, FIG. 3 and FIG. 4 are detailed views of the vicinity of a molded product showing another embodiment, respectively.

(First Embodiment) In FIGS. 1 and 2, a barrel mold 14 constituting an outer shell of a molding die 12 is placed on a main body 10 of a molding apparatus for an optical element via a support substrate 20. Has been done. The body mold 14 is formed in a substantially square prism shape in a top view, and through holes 14a and 14b are formed on the center axis of the body mold 14 so as to penetrate the body mold 14 up and down. Among these through holes, the upper through hole 14a has
An upper mold member 16 formed in a cylindrical shape is slidably inserted along the up-down direction in a fitted state. Upper mold member 1
A disc-shaped flange portion 16a is formed at the upper end portion of 6, and the lower surface of the flange portion 16a abuts on the upper surface 14c of the body die 14 from above, whereby the upper die member 16 is formed.
Is prevented from moving further downward, thereby defining a downward press stroke of the upper die member 16. Further, on the lower surface of the upper mold member 16, a molding surface 16b for pressing the glass material 40 and transferring a desired shape to the surface to form an optical function surface is formed.

Further, a cylindrical surface 16c parallel to the optical axis of the molding surface 16b is formed on the outer periphery of the lower portion of the upper mold member 16, and a screw having the optical axis of the molding surface 16b as an axis is formed above the cylindrical surface 16c. The portion 16d is formed. On the other hand, the ring member 2 is formed on the outer circumference of the molding surface 16b of the upper mold member 16, and the upper mold member 1 is formed on the inner circumference of the ring member 2.
Cylindrical surface 16c of No. 6 and cylindrical surface 2c corresponding to the threaded portion 16d
The threaded portion 2d is formed, and the cylindrical surface is fitted and positioned with respect to the surface direction of the molding surface 16b perpendicular to the optical axis, and is fixed by the threaded portion. In addition, a mating surface 2a with the molding surface 16b of the upper mold member 16 is formed on the inner periphery of the lower portion of the ring member 2, and an edge portion 2b which is in line contact with the molding surface 16b is formed on the innermost peripheral side thereof. Has been done. At this time, the edge portion 2
In order for b to contact the molding surface 16b, the inclination of the mating surface 2a must be equal to or less than the inclination angle of the tangent line R of the molding surface 16b at the position corresponding to the edge 2b. . As a result, the molding surface 16b of the upper mold member 16 and the edge portion 2b of the ring member 2 come into line contact with each other in a ring shape without a gap, and are fixed to each other by the respective screw portions 16d and 2d. Is positioned in a state of being pressed against the optical axis direction of. FIG. 3 is a view for explaining a method of determining the angles α, β formed by the ring member 2, the upper mold member 16 and the outer periphery of the molded part. Let R be a line connecting the center of curvature o of the molding surface of the upper die member 16 and the edge portion 2b of the ring member 2, and β be the angle formed by this straight line R and the mating surface 2a of the ring member 2, and also be the straight line R The angle formed by the molding surface 2e of the ring member 2 is α.
Here, since the pressure applied to the ring member at the time of pressing acts on the edge portion 2b, it is necessary to secure the strength of this portion. Therefore, the angle obtained by subtracting β from the angle α may be set to a large value. First, considering the angle β, the smaller the angle, the more advantageous in terms of strength.
If it becomes smaller than the degree, the molding surface 16b and the mating surface 2a come into contact with each other at a portion other than the edge portion 2b.
A gap is created between 6b and the mating surface 2a, and glass enters during molding, causing burrs and cracks. Therefore, the angle β is preferably set to 90 degrees, but may be set to be larger than 90 degrees in consideration of the processing tolerance and the case where the molding surface 16b is an aspherical surface. Next, considering the angle α, the edge portion 2b receives a pressure in a linear direction from the molding surface 16b, and considering the strength of the edge portion, the angle α
Is preferably 180 degrees or more, but may be 180 degrees or less depending on the shape of the molded product if there is a margin in strength. Further, in FIG. 3, the molding surface 2e has a linear shape. It may be changed to correspond to the shape of the molded product.

A piston rod 22 of an upper air cylinder for generating a press pressure applied to the glass material 40 is arranged above the upper mold member 16 in a state of being supported by a supporting member (not shown). There is. The lower end of the piston rod 22 is connected to the upper end surface of the upper mold member 16. Therefore, the upper air cylinder is operated and the piston rod 22 is extruded downward, whereby the press pressure P1 is applied to the glass material 40.

Further, the upper die member 16 is provided with a sensor 27 for measuring the temperature in the vicinity of the molding surface 16b, and the upper die member 16 is supplied from an N ₂ gas supply source (not shown) through an N ₂ jet pipe 34. A cooling pipe 30 for cooling 16 is installed.

On the other hand, in the through hole 14b on the lower side of the body mold 14, a lower mold member 18, which is formed in a cylindrical shape like the upper mold member 16, is slidable in the vertical direction in a fitted state. Has been inserted into. A disc-shaped flange portion 18a is formed in the lower portion of the lower mold member 18, and the flange portion 18a is formed.
The lower surface 18c of the support substrate 2 on which the body mold 14 is placed
0 is in contact with the upper surface. The support substrate 20 is configured to receive the downward pressing pressure P1 applied to the lower mold member 18 from the upper mold member 16 via the glass material 40. On the upper end surface of the lower mold member 18, a molding surface 18b for transferring a desired shape to the lower surface of the glass material 40 to form an optical function surface is formed.

Therefore, the glass material 40 is provided with an optical function surface 40a on the upper surface of which the surface shape of the molding surface 16b of the upper mold member 16 is transferred, and on the lower surface thereof, the molding surface 18b of the lower mold member 18. The optical function surface 40b having the transferred surface shape is formed.

As described above, the thickness of the formed molded product is defined by the lower surface of the flange of the upper mold member 16 contacting the upper surface of the body mold 14, and the thickness of the molded product is changed every time it is processed. It is designed not to change.

A cavity is formed by the upper mold member 16, the ring member 2 and the lower mold member 18, but an opening is provided on the outer periphery of the cavity so that the cavity does not become a closed space at the end of pressing. There is. That is, FIG.
In this case, a gap A is formed between the ring member 2 and the lower mold member 18.

Further, a piston rod 24 of a lower air cylinder is installed on the lower surface of the molding apparatus main body 10, and the piston rod 24 is attached to the through hole 10a formed in the molding apparatus main body 10 and the support substrate 20. It is connected to the lower surface 18c of the lower mold member 18 through the through holes 20a thus formed. In order to prevent the concave lens (40) from losing its shape in the cooling process after the molding operation of the concave lens (glass material 40) is completed, the piston rod 24 of the lower air cylinder is configured to move the lower mold member 18 upward. It is for pushing up and applying pressure P2 to the concave lens (40).

Further, the lower mold member 18 is provided with a sensor 28 for measuring the temperature in the vicinity of the molding surface 18b, and a lower mold member 18 is passed from an N ₂ gas supply source (not shown) through an N ₂ jet pipe 36. A cooling pipe 32 for cooling 18 is installed.

On the other hand, on the side surface of the body mold 14, an opening hole 14d is formed.
The glass material 40 is supplied to the inside of the molding die 12 through the opening hole 14d, and the concave lens (40) that has been molded is taken out from the inside of the molding die 12.

Inside the barrel mold 14, the barrel mold 14, the upper mold member 16 and the lower mold member 18 are heated, and at the same time, the glass is passed through the barrel mold 14, the upper mold member 16 and the lower mold member 18. A heater 26 for heating the material 40 is arranged.

The heater 26 has an upper mold part and a lower mold part connected to independent temperature controllers (not shown).
The temperature is detected and controlled by 7, 28.

Next, the molding die 1 constructed as described above.
The procedure for molding the concave lens by 2 will be described.

First, the piston rod 22 of the upper air cylinder is pulled in, the upper die member 16 is slid upward with respect to the body die 14, and is released from the lower die member 18. In this state, the glass material 40 heated to a predetermined high temperature is supplied onto the molding surface 18b of the lower mold member 18 by an automatic hand or the like through the opening hole 14d of the body mold 14. Further, the body mold 14, the upper mold member 16 and the lower mold member 18 are heated to a temperature corresponding to predetermined molding conditions.

After the glass material 40 is supplied onto the molding surface 18b of the lower mold member 18, the piston rod 22 of the upper air cylinder is pushed out to make the molding surface 16b of the upper mold member 16 on the upper surface of the glass material 40. And press pressure P1 is applied to the glass material 40. This press pressure P1
When the upper mold member 16 is gradually moved downward by being applied, the glass material 40 is gradually crushed in the horizontal direction, and finally the state shown in FIGS. 1 and 2 is obtained. In this state, on the upper and lower sides of the glass material 40, the optical function surfaces 40a and 40b to which the shapes of the molding surface 16b of the upper mold member 16 and the molding surface 18b of the lower mold member 18 are transferred are formed.
And the glass material 40 is molded to a desired thickness.

Thereafter, the molded concave lens (glass material 40) is cooled. At this time, the upper mold member 16 and the lower mold member 18 are supplied to the cooling pipes 30 and 32 through the N2 jet pipes 34 and 36, respectively. Cooling is accelerated by the N ₂ gas. Further, in this cooling process, the piston rod 24 of the lower air cylinder is operated so that the surface shape of the molded concave lens (40) does not collapse, and the lower mold member 1 is operated.
8 is pushed up and pressure P2 is applied to the concave lens (40). Then, when the temperature drops to a predetermined temperature, the piston rod 24 of the lower air cylinder is pulled in and the pressure P2 is released. After that, the piston rod 22 of the upper air cylinder is again retracted, the upper mold member 16 moves upward, and the concave lens is taken out to the outside through the opening hole 14d of the barrel mold 14 by an auto hand or the like.

The concave lens (40) is molded by the series of operations described above.

Here, a more detailed example will be described. Lanthanum-based glass (refractive index 1.7
3, Abbe's number 49.4, transition point 571 ° C), and a concave aspherical surface on the upper surface side (approx. R12mm) with an effective diameter of φ17mm,
A concave meniscus lens having a convexity of R 170 mm on the lower surface side, an effective diameter of 22 mm, a center thickness of 1.6 mm, and an outer peripheral thickness of 5.6 mm is molded. Further, the mold at this time has a structure as shown in FIG. 1, the diameter of the edge portion 2b of the ring member 2 is φ18 mm, the cylindrical portion 2c of the ring member 2 and the cylindrical portion 2 of the upper mold member 16 are
c is fitted within a length of 10 mm with a gap of 5 μm or less, and a cemented carbide die having a gap A dimension of 1.3 mm between the ring member 2 and the lower die member 18 is used as follows. Molded. The angles β and α of the ring member 2 are 1 respectively.
It was set to 00 and 185 degrees.

1 and 2, first, the upper mold member 1
6 and the lower mold member 18 are at a temperature of 550 ° C., the glass material 40 is charged, and in this state, the temperature of the upper mold member 16 and the lower mold member 18 becomes 640 ° C., and a heating source (not shown) is used. After waiting until the material 40 reaches a predetermined temperature, it is press-molded with a press pressure of 4200N and further cooled while finally applying a force of 4200N until the temperature of the point transfer is reached. I took it out. As a result of molding in this way, although the molded product (40) is filled with glass up to the vicinity of the edge portion 2b of the ring member 2,
No burr was generated. At this time, the optical function surface 40a on the upper surface side of the molded product (40) is the molding surface 16b of the upper mold member 16.
Up to φ17.8 mm in diameter, and the optical function surface 4 on the lower surface side
0b is the diameter of the molding surface 18b of the lower mold member 18 of 23.9.
Since the transfer was performed up to mm, the upper and lower surfaces secured the effective diameter of the lens or more, and a good molded product was obtained.

Further, when the portion of the molded product (40) in contact with the ring member 2 is positioned, the optical eccentricity is set to 60.
It was possible to set it within the second, and a good molded product was obtained.

By the way, in the above-mentioned molding, when the dimension A between the ring member 2 and the lower mold member 18 is set to 0.6 mm, the edge portion 2b of the ring 2 is filled with pissiri and glass,
Although burr does not occur, the glass becomes the edge,
A slight chipping occurred partially. In this case, although it can be used as a product, since glass fragments remain in the molding die, cleaning is required, which hinders continuous molding.

In this embodiment, screws are used as a method for fixing the ring member 2 and the upper mold member 16 as shown in FIG. 1. However, as shown in FIG. Alternatively, the upper mold member 50 and the upper mold member 50 may be fixed to each other. In this case, although a space in the radial direction is required rather than using a screw, the length of the cylindrical portion 4d of the ring member 4 is easily increased, which is suitable for cases where the eccentricity of the lens is severe. In any case, the designer can arbitrarily devise the attachment of the ring member and the mold member.

Further, the boundary of the ring member 2 is in contact with the molding surface 16b of the mold member 16 in an edge shape, but other shapes may be in line contact with each other. The boundary portion of 2 may have an R (curved surface) shape, or the ring member 2 may be a flat portion to be brought into contact with the molding surface 16b of the mold member 16.

(Second Embodiment) FIG. 5 is a detailed view of the vicinity of the molded product showing the second embodiment, except that a ring member is also provided on the outer periphery of the lower mold to make it into two bodies. Is the same as that of the first embodiment, and therefore the overlapping portions will be omitted.

Here again, a detailed example will be given to explain that the material 40 is made of heavy crown glass (refractive index 1.5.
8, Abbe number 59.4, transition point 550 ° C.), concave R30 mm on both sides, effective diameter φ14 mm, center thickness 1.
A concave lens having a thickness of 3 mm and a peripheral thickness of 3.2 mm is molded. The mold at this time has a structure as shown in FIG.
And the diameters of the edge portions 6b and 8b of both are φ1.
4.8 mm, the cylindrical portion 6c of the ring member 6, the cylindrical portion 52c of the upper mold member 52, and the cylindrical portion 8c of the ring member 8
And the cylindrical portion 54c of the lower mold member 54 each have a length of 7 mm.
In the range of 6 μm or less, fitting was performed, and molding was performed as follows using a cemented carbide mold in which the clearance C dimension between the ring member 6 and the ring member 8 was 0.8 mm. The angles β and α were set to 91 and 170 degrees, respectively.

In FIG. 4, first, when the temperature of the upper mold member 52 and the lower mold member 54 is 500 ° C., the glass material 44 is
And in this state, the upper mold member 52 and the lower mold member 5
After the temperature of No. 4 has reached 620 ° C. and the material 44 has reached a predetermined temperature with a heating source (not shown),
Press molding was performed with a pressing pressure of 3100N, and further, cooling was performed by finally applying a force of 2200N until the temperature of point transfer was reached, and then the molded product was taken out. As a result of molding in this way, although the molded product (44) was filled with glass to the vicinity of the edge portions 6b and 8b of the ring members 6 and 8, burrs did not occur. At this time, the molded product (4
4) The optical function surface 44a on the upper surface side is the molding surface 52b of the upper mold member 52 up to φ14.5 mm in diameter, and the optical function surface 44b on the lower surface side is the molding surface 54b of the lower mold member 54 in diameter. Similarly, the transfer was performed up to φ14.5 mm, and in this case as well, the effective diameter of the lens or more was secured on both the upper and lower surfaces, and a good molded product was obtained.

Further, even when the respective parts of the molded product (44) which come into contact with the ring members 6 and 8 are positioned, the optical eccentricity can be set within 50 seconds, and a good molded product is obtained.

By the way, in the above molding, when the clearance C between the ring member 6 and the ring member 8 is set to 0.5 mm, the edge portions 6b and 8b of the ring members 6 and 8 are filled with pissiri and glass, and burr is formed. Although it did not occur, the glass became the edge, so a slight chipping occurred, which also hindered continuous molding.

In this embodiment, the shape of the concave lens is described, but the shape is not particularly limited. For example, even in the case of a convex lens, the positioning portion which requires relatively high precision is formed by a mold ring. If the mold is composed of a plurality of members using a ring and the shape of the glass is required near the mating part, it is not necessary to produce burr. Applicable.

[0055]

As described above, according to the invention of the present application, the boundary portion of the ring member on the molding surface with the mold member is in line contact with the mold member in a ring shape, and the mold member is still in contact. Since it is fixed in a state in which it is pressed in the direction in which it comes into close contact with, it can be assembled without creating a gap at the boundary between the ring member and the mold member, and even if some molding pressure is applied. Also, since there is no gap at the boundary portion, it is possible to obtain a molded product without burrs or chips during molding. Therefore, considering the strength of the material without worrying about the occurrence of burrs and chips, even if it is advantageous to make the mold from multiple members, such as when molding a lens with a large peripheral thickness such as a concave lens, it is important to consider the strength of the material. You can freely select the parting line. This allows
It is now possible to design a mold that is composed of multiple members and that corresponds to lenses of various shapes.The lens molded by that mold requires a minimum amount of material, and also causes sink marks in the peripheral area. The effect is great, such as a high-precision lens that does not exist.

Further, according to this mold structure, the position of the ring member with respect to the molding surface of the mold member can be determined and assembled with high accuracy, so that the lens molded by this mold is formed by the ring member. Even if a part is used as a positioning part in the post process, it has sufficient accuracy, and even if the part is used as a positioning part in the post process, it has enough accuracy to ensure higher accuracy. The process can be shortened even for lenses that require positioning.

According to the invention of the present application, the ring member and the mold member can be fitted not only in line contact in a ring shape but also in a plane parallel to the optical axis of the molding surface of the mold member. , Even when using a die having a small centering effect between the ring member and the die member, such as an aspherical surface or a die having a gentle curvature, by simply making line contact in a ring shape, the adhesion with the ring member is increased, It is possible to position with high accuracy. As a result, regardless of the shape of the molding surface, a highly reliable positioning of the ring member and the mold member is achieved without generating a gap such as a burr.

Further, according to the invention of the present application, the gap is formed between the upper and lower molds and the release portion provided on the outer peripheral portion of the cavity formed by the ring member so as to be 0.8 mm or more, whereby the pressure molding is performed. Since the pressure of the material at that time is released to the release part so that an unnecessarily high pressure is not applied to the boundary part between the ring member and the mold member, the mold structure is shaped so that the molding pressure is easily applied to the boundary part. Even in the case of, it is possible to obtain a molded product in which burrs and chips do not occur. Therefore, also in this case, it becomes possible to design a mold composed of a plurality of members without being influenced by the shape.
The scope of application of the inventions 4 and 7 is broadened.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a mold for an optical element according to a first embodiment of the present invention, which is a detailed view around a molded product after completion of a pressing operation.

FIG. 2 is a cross-sectional view showing the configuration of a molding die for an optical element according to the first embodiment of the present invention, and is a diagram showing the overall construction of the molding die after the pressing operation is completed.

FIG. 3 is an explanatory diagram for setting each angle of the ring member 2.

FIG. 4 relates to a first embodiment (another embodiment) of the present invention,
FIG. 6 is a cross-sectional view showing a configuration of a molding die of an optical element, which is a detailed view of the vicinity of a molded product after completion of a pressing operation.

FIG. 5 is a cross-sectional view showing a configuration of a mold for an optical element according to a second embodiment of the present invention, which is a detailed view of the vicinity of a molded product after completion of a pressing operation.

[Explanation of symbols]

2, 4, 6, 8 Ring members 2a, 4a, 6a, 8a Mating surfaces 2b, 4b, 6b, 8b Edge portions 2c, 4c, 6c, 8c Cylindrical surfaces 2d, 4d, 6d, 8d Screw portion 10 Molding apparatus main body 12 Molding mold 14 Body 14d Opening hole 16,50,52 Upper mold member 16b, 18b, 50b, 52b, 54b Molding surface 16c, 50c, 52c, 54c Cylindrical surface 16d, 52d, 54d Screw part 18, 54 Lower mold member 22, 24 Piston rod 26 Heater 27, 28 Sensor 30, 32, 62, 64 Cooling pipe 34, 36 N ₂ jet pipe

Claims (6)

[Claims] 1. A material heated in a deformable state is pressed and cooled in a cavity formed by a pair of molds and a ring member forming the outer periphery of at least one of the molds, the cavity being provided with a release portion. Then, in the optical element in which a surface corresponding to the molding surface of the mold is obtained by removing from the mold, the boundary portion of the ring member on the molding surface with the mold member makes a line contact with the mold member in a ring shape. An optical element obtained by using a mold that is fixed while being pressed against the mold member in a direction in which the mold member is in close contact with the mold member. 2. A ring member and a mold member can be obtained by using a mold which is fitted in a plane parallel to the optical axis of the molding surface of the mold member, in addition to the ring-shaped line contact. The optical element according to item 1, which is characterized. 3. An optical element molding member having a fitting portion that fits in the axial direction of a mold member that forms an aspherical surface of an optical element and a contact portion that contacts the aspherical surface and seals the optical element material. An optical element molding device characterized by the above. 4. A material heated in a deformable state is pressed and cooled in a cavity formed by a pair of molds and a ring member forming the outer periphery of at least one of the molds, the cavity being formed by providing a release portion. After that, the molded product is taken out of the mold, and in the molding die of the optical element having a surface corresponding to the molding surface of the mold, the boundary portion between the molding surface of the ring member and the molding member is ring-shaped with respect to the molding member. Line contact with
In addition, the apparatus for molding an optical element is characterized in that it is fixed in a state of being pressed against the mold member in a direction in which it closely contacts. 5. The angle formed by a straight line connecting the center of curvature of the molding surface of the die member and the edge portion of the ring member and the mating surface of the ring member is at least 90 degrees or more. Item 3. An optical element molding apparatus according to any one of items 3 to 4. 6. A material heated in a deformable state is pressed and cooled in a cavity formed by a pair of molds and a ring member forming the outer periphery of at least one of the molds, the cavity being formed by providing a release portion. In the method for molding an optical element having a surface corresponding to the molding surface of the mold after taking out the molded product from the mold, the boundary portion of the ring member with the molding surface has a ring shape with respect to the molding member. A method of molding an optical element, which comprises molding with a mold fixed in a state of being in line contact with the mold and being pressed against the mold member in a direction in which the mold member is in close contact with the mold member.