JP2006248869A - Mold press-forming apparatus, its press head, and method for production of optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold press-forming apparatus in which a press means for applying load to a press-forming die is improved and press forming can be performed without deteriorating eccentricity precision, and also to provide a press head therefor and a method for production of an optical device. <P>SOLUTION: When pressing by a press-forming die 1, a barrel mold 4 is press-contacted with a receiving face 23 of a flange 22 of a lower die 2 by a first press head 11 to mutually position the barrel mold 4 and the lower die 2. While holding such a state, a forming material W is press-formed by adding load to an upper die 3. Thus, when press-forming the material W, the barrel mold 4 and the lower die 2 are fixed without tilting, and the first press head 11 related to the above press contact is also fixed. Thereby, the upper die 3 is pressed without tilting by a guided second press head 12, and the relative tilt of the upper and lower dies can surely be prevented from occurring, thus enabling the production of an optical device having high shape accuracy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an optical element, in which an optical element is manufactured without grinding / polishing a surface to be molded by press-molding a molding material such as glass with a precision-molded press mold, and therefore The present invention relates to a mold press forming apparatus to be used. More specifically, the present invention relates to a pressing unit (press head) for pressing a press mold in a mold press molding apparatus, and an improvement of a press mold pressed by the pressing unit.

  A method of manufacturing an optical element such as a high-precision aspheric lens by press molding is known. According to such a method, the complicated aspherical polishing step which has been conventionally performed can be omitted, so that it is possible to manufacture a large number of optical elements having the same shape at low cost.

  In recent years, along with the demand for high-pixel imaging optical systems and high NA pickup lenses, the coaxiality of the first and second surfaces required for optical elements has become increasingly severe. Therefore, in order to suppress the mutual tilt (tilt) of the upper and lower mold axes in the mold and to suppress the horizontal axis shift (shift) of the upper and lower molds, it is only necessary to improve the structure of the mold. There is a limit, and the pressing method and pressing means of the mold are improved. In addition, an optical element having a high degree of molding difficulty, such as a concave meniscus lens or a biconcave lens, obtains good surface accuracy by a multi-stage press in which the load application is changed over time.

  For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 11-035333), a glass material to be molded that has been softened by heating is initially pressed with a molding die to transfer the shape of the molding surface of the molding die at the start of initial pressing or at the initial stage. Cooling the mold and molded glass during the pressurization, and applying a pressure (secondary pressurization) weaker than the initial pressure to the molded glass during this cooling, the molded glass is below the glass transition point. A manufacturing method and a manufacturing apparatus for a glass molded body in which a molded glass is taken out from a molding die after that is shown. Thereby, it is supposed that a glass optical element with high surface accuracy and center thickness accuracy can be molded.

  Further, in Patent Document 2 (Japanese Patent Publication No. 5-31504), a mold composed of upper and lower molds and a barrel mold in which glass to be molded is arranged is sequentially transferred through a plurality of press chambers. By pressing the upper mold until the pressure stroke is limited to the body mold (sleeve), the center thickness of the glass to be molded is substantially determined, and by pressing only the upper mold with the pressure rod in the second press chamber, A manufacturing method and a manufacturing apparatus for obtaining a glass molded body with high shape accuracy by preventing the occurrence of sink marks after pressurization are shown.

  On the other hand, Patent Document 3 (Japanese Patent Publication No. 4-42338) discloses a method for preventing eccentricity by providing pressing protrusions on the pressing surface of the upper die so that the axes of the upper die and the lower die are aligned. Yes.

Further, in Patent Document 4 (Japanese Patent Publication No. 2-28460), the upper mold is pressed from above through a push plate, and the push plate is brought into contact with the upper surface of the guide mold during pressurization. A method for suppressing the tilt (tilt) and the misalignment (decenter) of the shaft is disclosed.
Japanese Patent Laid-Open No. 11-035333 Japanese Patent Publication No. 5-31504 Japanese Examined Patent Publication No. 4-42338 Japanese Patent Publication No. 2-28460

  According to Patent Document 1, it is said that a glass material can be formed into a final product shape by initial pressing, and the surface accuracy can be maintained and improved by secondary pressing. However, after forming the glass material by bringing the upper and lower molds close to each other at the initial pressurization, when the upper mold is pressed by the secondary pressurization, the body mold that guides the upper and lower molds is horizontal within the range of the horizontal clearance. Free in direction. For this reason, there is a drawback that the coaxiality of the upper and lower molds is impaired and it is difficult to ensure the eccentric accuracy of the molded product.

  Further, according to Patent Document 2, since the body mold is pressed against the lower mold while pressing the upper mold with the primary pressurization, the coaxiality of the upper and lower molds is secured at the stage of the primary pressurization. However, since only the upper mold is pressed at the stage of secondary pressurization, the barrel mold becomes free, and there is a possibility that the eccentricity accuracy may deteriorate.

  Furthermore, since the method described in Patent Document 3 is a method for preventing the occurrence of eccentricity due to the load applied by the pressing means, the pressing means does not increase the eccentricity accuracy. Therefore, with the method disclosed herein, it is difficult to manufacture an aspherical (both aspherical) optical element with high accuracy.

  On the other hand, in Patent Document 4, the eccentric accuracy is obtained by the contact of the push plate. However, once the pressing plate comes into contact, no load is applied even if the pressing plate is pressed thereafter. Therefore, it cannot be used as a technique for improving the eccentricity accuracy when the pressing is performed in a plurality of stages.

  In view of these points, an object of the present invention is to improve a pressing unit that applies a load to a press mold, and to perform press molding without deteriorating the eccentric accuracy, and the press The present invention proposes a method for manufacturing a head and an optical element.

  In order to solve the above-described problems, a mold press molding apparatus of the present invention includes a first mold having a molding surface, a second mold having a molding surface disposed opposite to the first mold, and the first mold. A cylindrical mold for coaxially inserting the first and second molds and the molding surfaces of the first and second molds are moved in a relatively close direction so that they are arranged between the molding surfaces. Pressing means for press-molding the formed molding material, and the pressing means is guided by the pressure contact means for positioning the body mold by pressing the body mold against a positioning reference surface, and the pressure contact means. However, load applying means for pressing the first mold is provided. Relative movement means that the first mold may move toward the second mold or the second mold may move toward the first mold.

  Preferably, the reference surface is formed on the second mold, and in this case, the body mold is brought into pressure contact with the reference surface by the pressure-contacting means, so that the body mold and the second mold are mutually connected. Positioning is performed.

  In the mold press molding apparatus of the present invention, at the time of press molding, at least the body mold is positioned with respect to the reference surface by the press contact means, and a molding material is applied by applying a load to the first mold by the load application means while maintaining this state. Is pressing. Therefore, since the body mold is positioned and fixed when the molding material is pressed, there is no problem that the body mold is inclined with respect to the upper and lower molds. Therefore, it is possible to prevent deterioration of the eccentric accuracy of the molded product.

  Here, the press contact means may be a cylindrical first press head, and the load applying means may be a second press head inserted and fitted inside the first press head. In this case, it can be configured to include a biasing means that biases the first press head in the pressing operation direction of the second press head in accordance with the pressing operation of the second press head. As the urging means, an elastic member such as a coil spring disposed between the first and second press heads can be used.

  Further, the first press head includes a pressing surface capable of contacting an axial end surface of the body mold on the side where the first mold is inserted, and the second press is provided on the pressing surface. It is possible to adopt a configuration in which a hole allowing the axial movement of the head is opened.

  Further, the second press head includes a pressing surface substantially parallel to the pressing surface of the first press head, and a large-diameter portion capable of sliding contact with the inner peripheral surface of the first press head. It is desirable that the pressing surface of the second press head and the outer peripheral surface of the large-diameter portion are formed so as to be orthogonal to each other.

  In this case, the axial length of the large-diameter portion of the second press head is set to the large length of the second press head so that the second press head is accurately guided by the first press head without tilting. It is desirable to make it longer than the axial length from the diameter part to the pressing surface.

  Next, the second mold is generally provided with a large-diameter flange formed at an axial end, and the reference plane perpendicular to the pressing operation direction of the pressing means can be formed on the flange. . In this case, when the barrel mold is pressed by the first press head and brought into close contact with the reference surface, the upright direction of the barrel mold and the pressing operation direction of the pressing means may be matched.

  On the other hand, the present invention press-molds a molding material in a molding die having first and second dies having opposing molding surfaces and a barrel die into which the first and second dies are coaxially fitted. In order to accomplish this, a press head of a mold press molding apparatus that presses the mold, the pressure contact means for positioning the body mold by pressing the body mold against a reference surface for positioning, and the pressure contact means And a load applying means for pressing the first mold while being guided.

  Here, the press contact means performs the mutual positioning of the body mold and the second mold by pressing the body mold against the reference surface formed on the second mold. It is characterized by.

  Further, the pressure contact means has a cylindrical first press head, the load application means has a second press head fitted inside the first press head, and the second press head. In accordance with the pressing operation, the first press head is provided with an urging means for urging the first press head in the pressing operation direction of the second press head. As the urging means, an elastic member such as a coil spring disposed between the first and second press heads can be used.

  Further, the first press head includes a pressing surface capable of contacting an axial end surface of the body mold on the side where the first mold is inserted, and the pressing surface includes the second press head. It is characterized in that a hole allowing an axial movement of the head is opened.

  Furthermore, the second press head includes a pressing surface that is substantially parallel to the pressing surface of the first press head, and a large-diameter portion that can slide in contact with the inner peripheral surface of the first press head. In addition, the pressing surface of the second press head and the outer peripheral surface of the large diameter portion are formed so as to be orthogonal to each other. In this case, the axial length of the large diameter portion of the second press head is preferably longer than the axial length from the large diameter portion to the pressing surface in the second press head.

  On the other hand, the present invention is a method for manufacturing an optical element, wherein when press-molding a heat-softened molding material using the mold press molding apparatus having the above-described configuration, the press contact means is used to position the barrel mold. A pressure contact step of pressing the barrel mold against the reference surface; and a load applying step of applying a load to the first mold by the load applying means in a state of pressing the barrel mold.

  Here, when the mold press molding apparatus includes the urging means, when applying a load by the second press head in the load applying step, the urging force of the urging means It is desirable to increase the pressing force of the first press head against the body mold.

  Next, the optical element manufacturing method of the present invention includes a first mold having a molding surface, a second mold having a molding surface disposed opposite to the first mold, and the first and second molds. In a mold having a body mold for coaxially inserting the mold, a supplying step of supplying a molding material between the molding surfaces, and heating the molding material so as to be in a state suitable for press molding. A heating process for softening and in this state, a pressing process for pressing the molding die to press-mold the molding material until the molding material reaches a predetermined thickness in a predetermined temperature range. A first pressing step for pressing, and a second pressing step for pressing the molding material further at a temperature lower than that of the first pressing step by pressing means including a first press head and a second press head. The pressing process A press-contacting process for positioning the first press head, the body mold and the second mold relative to each other by pressing the body mold against at least a part of the second mold by the first press head; and And a load applying step of applying a load to the first die using the second press head guided by the first press head while maintaining the positioning state.

  Here, in the load application step, it is desirable to increase the pressing force of the first press head to the body mold as the second press head moves.

  According to the present invention, at the time of pressing the molding material, first, the body mold is positioned and fixed, or the cylinder mold and the second mold are fixed in a mutually positioned state, and the first mold is maintained while maintaining this state. The molding material is press-molded by applying a load. Therefore, since the body mold is fixed without tilting when the molding material is press-molded, it is possible to suppress the occurrence of relative tilting between the first and second molds, and to manufacture an optical element having high shape accuracy. be able to.

  In particular, when press-molding a molding material by applying a load to the first mold while pressing the barrel mold against the second mold and fixing their relative positions, these pressure-contact surfaces are formed with high precision. In addition, if the orthogonality between the pressure contact surface of the body mold and the inner peripheral surface of the body mold on which the upper mold is guided is accurately formed, the upper mold can be pressed without tilting. Can be increased.

  Further, in the optical element manufacturing method of the present invention, the pressing process is performed in two stages including the first and second pressing processes. In the second pressing process, the body mold is first pressed against the second mold by the pressing process. These positions are defined, and this state is maintained, and the molding material is pressed by applying a load to the first die in the load application step. Therefore, it is possible to manufacture an optical element having a high molding difficulty, such as a concave meniscus lens or a biconcave lens, with high shape accuracy.

  Embodiments of the present invention will be described below with reference to the drawings.

(Mold press molding equipment)
FIG. 1 is a schematic plan view showing the whole of a rotary transfer type mold press molding apparatus to which the present invention is applied, FIG. 2 is a schematic sectional view showing a press mold to be transferred, and FIG. 3 is a press chamber. FIG.

  The mold press molding apparatus P according to the present embodiment performs a suitable molding by transferring a press mold containing a molding material (glass preform or the like) sequentially through each processing chamber ( Glass optical elements and the like).

  As shown in FIG. 1, the mold press molding apparatus P includes a take-out / insertion chamber P1 and a large number of processing chambers P2, P3, P4, P5, P6, P7, and P8 arranged side by side in the circumferential direction. Through these processing chambers in an inert gas atmosphere, a press mold containing a molding material is placed on a rotary table so as to pass sequentially.

  The processing chambers P2 and P3 are first and second heating chambers, the processing chamber P4 is a soaking chamber, the processing chamber P5 is a press chamber, and the processing chambers P6 and P7 are first and second annealing chambers. The processing chamber P8 is a rapid cooling chamber. The press chamber P5 of this example includes a first press chamber P5 (1) and a second press chamber P5 (2). These processing chambers P2 to P8 are arranged at substantially equal intervals, and the temperature is controlled to a temperature suitable for each processing. Therefore, these processing chambers P2 to P8 are partitioned by shutters S1, S2, S3, S4, S5, S6, and S7.

  The first heating chamber P2, the second heating chamber P3, the soaking chamber P4, the first annealing chamber P6, the second annealing chamber P7, and the quenching chamber P8 are a press mold containing a molding material, and a molding material. Or it is for adjusting the temperature of the press mold which accommodated the obtained molded object.

  The rotary table rotates intermittently at fixed time intervals, and a molding die supplied with a molding material in the insertion / insertion chamber P1 passes through the processing chambers P1 to P8, and then enters the extraction / insertion chamber P1. It is taken out as a mold containing the molded body at the take-out part. The intermittent rotation period at this time is the molding cycle time. By using such a transfer type (not limited to a rotary type, including a linear movement type) mold press molding apparatus P, various processes necessary for press molding can be performed simultaneously in parallel. This is advantageous for shortening the real time (cycle time) required for molding.

  The present invention is suitably used in a mold press molding apparatus and method as in this example in which a press mold is transferred to each processing chamber and appropriate processes including heating, pressing, and cooling are sequentially performed. However, the present invention is not limited to this. Needless to say.

(Press mold)
As shown in FIG. 2, the press mold 1 of this example includes a lower mold 2 (second mold) having a molding surface 2a, and an upper mold 3 having a molding surface 3a disposed opposite to the molding surface 2a. (First mold) and a barrel mold 4 into which the lower mold 2 and the upper mold 3 are coaxially fitted. The body mold 4 has a cylindrical shape, and the hollow portion has a middle portion in the vertical direction as a small-diameter portion 41, and an upper large-diameter portion 42 having a larger diameter above and below the small-diameter portion 41. And the lower large diameter part 43 is formed.

  The lower mold 2 includes a cylindrical lower mold body 21 and a large-diameter circular flange 22 that is coaxially formed integrally with the lower end thereof, and a molding surface 2 a is formed on the upper end surface of the lower mold body 21. Has been. The lower mold body 21 has an outer diameter dimension that can be fitted into the lower large-diameter portion 43 of the trunk mold 4, and the annular lower end surface 44 of the trunk mold 4 is pressed against the flange 22. An annular receiving surface 23 (reference surface) having a size is formed.

  The upper mold 3 includes a cylindrical upper mold body 31 and a large-diameter circular flange 32 that is coaxially formed integrally with the upper end, and a molding surface 3 a is formed on the lower end surface of the upper mold body 31. Has been. The upper die body 31 is sized to fit into the small diameter portion 41 of the body die 4, and the flange 32 is sized to fit into the upper large diameter portion 42. The thickness of the flange 32 is thinner than the depth of the upper large diameter portion 42.

  Here, the radial clearance between the trunk mold 4 and the lower mold 2 is 5 μm or less, and the radial clearance between the upper mold 3 and the trunk mold 4 is the same. When the lower end surface 44 of the body mold 4 contacts the receiving surface 23 of the lower mold flange 22, the circular upper end surface 33 of the upper mold 3 is positioned higher than the annular upper end surface 45 of the body mold 4 due to the thickness of the glass material W. Is set to move to. Further, the body mold 4 is formed so that the orthogonality between the lower end surface 44 and the upper end surface 45 of the body mold 4 and the inner peripheral surface of the hollow portion of the body mold 4 is highly accurate.

(Press room)
Next, as shown in FIG. 3, the press chamber P <b> 5 of the mold press molding apparatus P includes a heating unit 52 installed in a casing 51, a reflector 53 that reflects heat from the heating unit 52, and a tip mold. A rotary table 55 as a transfer means for transferring the support base 54 that supports the press mold 1 on the mounting surface 54a, a support bar 56 for supporting the rotary table 55 from the lower side during the press operation, and a predetermined pressure on the press mold 1. A pressure rod 57 that applies a load, a drive motor 58 that controls the vertical movement of the pressure rod 57, and a press head 10 that is provided at the tip of the pressure rod 57 and serves as a pressing means for pressing the press mold 1. It has. FIG. 3 is a schematic configuration diagram showing a cross-sectional configuration of the press chamber P5 (2).

  Here, a press head 10A shown in FIG. 4 to be described later is attached as the press head 10 to the first press chamber P5 (1). In the second press chamber P5 (2), a press head 10B shown in FIGS. The configuration other than the press head is basically the same.

(Press head)
FIG. 4 is an explanatory view showing the pressing operation in the first press chamber P5 (1). As can be seen from this figure, in the first press chamber P <b> 5 (1), the press head 10 </ b> A as the press head 10 is connected to the tip of the pressure rod 57. The press head 10 </ b> A is a disk-shaped member having a flat circular pressing surface 61 that is orthogonal to the direction (the pressing operation direction) of the axis 57 a of the pressing rod 57 that is the pressing direction.

  FIG. 5 is a schematic cross-sectional view showing a press head installed in the second press chamber P5 (2), and FIG. 6 is an explanatory diagram showing a press operation in the second press chamber P5 (2). The configuration of the second press head 10B disposed in the second press chamber P5 (2) will be described with reference to these drawings.

  The press head 10 </ b> B is a first press head 11 that presses the body mold 4 toward the lower mold 2 and press-contacts the first press head 11, and is inserted into the first press head 11 in a coaxial state and presses only the upper mold 3. 2 Press head 12 and a coil spring 13 which is a biasing means for biasing the first press head 11 in the same direction as the pressing operation direction of the second press head 12 in accordance with the pressing operation of the second press head 12. I have.

The first press head 11 is made of a material having high heat resistance (for example, Si ₃ N ₄ or other ceramics) and has a substantially cylindrical shape. In this example, the pressing operation direction of the press head 10B is the vertical direction shown in the drawing (the axial direction 57a of the pressing rod 57), and the pressing surface 11a at the lower end of the first press head 11 is in relation to the operating direction 57a. It is formed on orthogonal surfaces.

  A through hole 11b that allows the second press head 12 to move up and down is provided at the center of the pressing surface 11a. The inner diameter of the through hole 11b is larger than the diameter of the tip 12b of the second press head 12, and smaller than the diameter of the flange 32 of the upper die 3. In addition, since the pressing surface 11a of the first press head 11 is an annular end surface larger than the outer diameter of the body mold 4, the pressing surface 11a presses the upper mold 3 and the body mold 4 in the process of the press operation described later. be able to.

  On the inner peripheral surface of the hollow portion of the first press head 11, in order from the lower side, an upward annular first step surface 11c, an upward annular second step surface 11d, and an upward annular third step surface 11e. Is formed.

  Like the 1st press head 11, the 2nd press head 12 consists of a material with high heat resistance, and is inserted in the hollow part of the 1st press head 11 in the coaxial state, The end surface on the free end side, ie, a lower end surface Is a circular pressing surface 12c sized to push only the upper mold 3, and the other end is connected to a pressing rod 57. As a connecting structure, the pressure rod 57 and the second press head 12 shown in the figure are integrated, or both are connected by a screwing member or a fastening member, or are connected via a joint such as a universal joint. Various connection structures can be selected.

  A large-diameter portion 12 a having a diameter larger than that of both end sides is formed in the intermediate portion of the second press head 12. And after inserting the large diameter part 12a of the 2nd press head 12 into the back | inner side (to the downward direction) rather than the 3rd step surface 11e of the 1st press head 11, it is in the opening part of the upper end side of the 1st press head 11. By fixing the retaining ring 11f, the second press head 12 is integrated so as not to be detached from the first press head 11.

A coil spring 13 is inserted into a small diameter portion 12b on the tip side (lower side) of the large diameter portion 12a of the second press head 12 so as to surround the small diameter portion 12b. The coil spring 13 is mounted between the first step surface 11 c of the first press head 11 and the lower step surface 12 d of the large diameter portion 12 a of the second press head 12. The coil spring 13 is made of a heat-resistant spring material (ZrO ₂ ceramics, austenitic stainless steel, Inconel alloy, Si ₃ N ₄ ceramics, etc.), and is set to have a predetermined spring constant (for example, about 3 kgf / mm). Yes.

  The first press head 11 as a whole is urged downward by a coil spring 13 with respect to the second press head 12, and the lower surface of the retaining ring 11 f is a large-diameter portion 12 a of the second press head 12. Is held in contact with the upper end surface 12e. In this state, the pressing surface 11 a of the first press head 11 protrudes slightly below the pressing surface 12 c of the second press head 12. For example, it protrudes about 2 mm.

  Further, when the first press head 11 and the second press head 12 are relatively moved in the axial direction, the second step surface 11d (position restricting portion) of the first press head 11 and the large diameter portion 12a of the second press head 12 are used. When the lower step surface is in contact with each other, the relative movement between the two is regulated. That is, the maximum movement amount of both is S in the figure. As described above, the second step surface 11d functioning as the position restricting portion prevents the coil spring 13 from being excessively compressed and broken due to the second press head 12 being undesirably lowered. However, in a normal pressing process, the lower step surface of the large-diameter portion 12a of the second press head 12 does not contact the second step surface 11d for position regulation, and the pressing surface of the second press head 12 is Control is performed so that the lowering of the second press head 12 stops when it protrudes about 5 to 20 μm from the pressing surface 11 a of the first press head 11.

  In a preferred embodiment, the clearance of the sliding portion between the large diameter portion 12a of the second press head 12 and the inner peripheral surface of the hollow portion of the first press head 11 is 5 to 15 μm. Moreover, it is preferable to suppress the fall of the 2nd press head 12 in the said clearance by making these sliding lengths as long as possible.

  For example, as shown in FIG. 7, the axial length (L1) of the large diameter portion 12a of the second press head 12 is relatively long, for example, the axial length of the small diameter portion 12b below the large diameter portion 12a. By forming so as to be longer than (L2), the upper die 2 can be pressed more straightly by the second press head 12. Of course, it is useful to maintain the verticality of the sliding portion of the large diameter portion 12a of the second press head 12 and the pressing surface 12c with high accuracy.

(Optical element manufacturing process by mold press molding equipment)
Next, an embodiment of a process of molding an optical element using the mold press molding apparatus P having the above configuration will be described.

1) Glass material supply step A molding material W, for example, a glass material, which is preformed into a shape having a convex curved surface (both convex curved surfaces in this example) is prepared, and the glass material W is transported by a transport arm with a suction pad. In a state where the upper and lower molds 2 and 3 are separated from each other, the glass material W is released by releasing the suction at a position with a positional accuracy within a predetermined range with respect to the molding surface 2a of the lower mold 2 placed on the support base 56. It is distributed to the lower mold forming surface 2a. The transfer arm is withdrawn immediately. In the mold press molding apparatus P, this process is performed in the take-out / insertion chamber P1 or a disassembly / assembly unit (not shown) installed outside the outer circumference of FIG.

2) Assembling process of press mold The support base 56 is raised, and the lower mold 2 is assembled into the body mold 4. The radial clearance between the trunk mold 4 and the lower mold 2 is 5 μm or less, and the upper mold 3 and the trunk mold 4 have the same clearance. When the lower end surface 44 of the body mold 4 contacts the receiving surface 23 of the lower mold flange 22, the upper end surface 33 of the upper mold moves to a position higher than the upper end surface 45 of the body mold due to the thickness of the glass material W (FIG. 4A). reference). This process can also be performed in the take-out / insertion chamber P1 or the disassembly / assembly section.

3) Heating Step The glass mold W and the press molding are heated while the press mold 1 containing the glass material W is sequentially transferred to the first heating chamber P2, the second heating chamber P3 and the soaking chamber P4. The mold 1 is brought to a temperature suitable for press molding.

For example, the first heating chamber P2 is kept at a high temperature equal to or higher than the press temperature of the glass material W, and rapidly heats the press mold 1 and the glass material W. After the press mold 1 and the glass material W are stationary for a predetermined time in the first heating chamber P2, the rotary table 21 rotates and reaches the second heating chamber P3. Due to the heating in the second heating chamber P3, the press mold 1 and the glass material W are further heated or soaked and approach the press temperature. Next, the press mold 1 and the glass material W are soaked in the soaking chamber P4 so that the glass viscosity is equivalent to a viscosity of 10 ⁶ to 10 ⁹ poise suitable for press molding, and transferred to the press chamber P5. Preferably, the glass material has a temperature at which a viscosity of 10 ⁶ to 10 ⁸ poise is obtained. The heating means is not particularly limited, such as a heater by resistance heating or a high frequency induction coil.

4) Pressing process As described above, the press chamber P5 is composed of the first press chamber P5 (1) and the second press chamber P5 (2), both of which are partitioned by the shutter S4, and each chamber has a pressing means. And each room temperature can be individually controlled.

The press mold 1 containing a glass material heated to a temperature corresponding to a glass viscosity of 10 ⁶ to 10 ⁹ poise in the heating process is sent to the first press chamber P5 (1) in FIG. ), The upper die 3 slightly protrudes from the upper end surface 45 of the trunk die 4. In the first press chamber P5 (1), the upper die 3 is pressed using a press head 10A having a tip pressing surface larger in diameter than the body die 4 (load is 30 to 200 kg / cm ² ), for example. As shown in FIG. 4B, the upper end surface of the body mold 4 and the upper end surface of the upper mold 3 are positioned on the same plane. At this time, the glass material W is deformed as the upper mold 3 is lowered, but the pressure is maintained for a predetermined time (for example, several tens of seconds) while a load is applied in the state of FIG. By pressing in the first press chamber P5 (1), the glass material W can be formed so that the thickness of the glass material W is within a predetermined range with respect to the thickness of the press product to be obtained.

Next, the press mold 1 is transferred to the second press chamber P5 (2) and is molded using another press head 10B as shown in FIG. The second press chamber P5 (2) has a temperature lower than that of the first press chamber P5 (1) (for example, a temperature at which the viscosity of the glass material in the mold becomes a temperature corresponding to 10 ⁹ to 10 ¹³ poise). Is controlled.

  FIG. 6A shows a state immediately before pressing the press mold 1 with the press head 10B. The press head 10B is connected to the lower end of the pressure rod (drive shaft) 57 located above, and the press head 10B continues to descend as the pressure rod 57 descends. As shown in FIG. 6 (B). The pressing surface 11 a of the first press head 11 contacts the upper end surface 45 of the body mold 4. At this time, the first press head 11 is substantially restricted from being further lowered by the body die 4. Note that the pressing surface 11 a of the first press head 11 can also contact the upper end surface 33 of the upper mold 3.

  As the pressure rod 57 continues to descend, as shown in FIG. 6C, only the second press head 12 descends and presses the upper die 3 while the first press head 11 is stopped. At this time, since the coil spring 13 is gradually compressed as the second press head 12 is lowered (pressing operation), the first press head 11 that is in contact with the upper end surface 45 of the body die 4 without load is removed. The body mold 4 is pressed by the spring force, and the pressing force increases according to the amount of lowering of the second press head 12.

  In this embodiment, the pressing surface 12c of the second press head 12 is set to be positioned 2 mm above the pressing surface 11a of the first press head 11, so that the pressing surface 12c of the second press head 12 is the upper die 3. The coil spring 13 is compressed by 2 mm at the point of contact with the coil. If the spring constant is 3 kgf / mm, when the coil spring is compressed by 2 mm, the first press head 11 presses the body mold 4 with 6 kgf.

  In the lower die 2, a receiving surface 23 orthogonal to the pressing operation direction of the press head 10 </ b> B is formed on the flange 22, and when the barrel die 4 is pressed by the first press head 11, the lower end surface 44 of the barrel die 4 is the lower die. 2 is closely attached to the receiving surface 23. At this time, the upper die 3 is pressed without tilting by forming the orthogonality of the lower end surface 44 and the upper end surface 45 of the body mold 4 and the inner peripheral surface of the body mold 4 with high accuracy. Therefore, the occurrence of tilt of the molded product Wa can be prevented in advance.

The lowering of the second press head 12 is controlled to stop when the pressing surface protrudes about 5 to 20 μm from the pressing surface 11 a of the first press head 11. In the second press chamber P5 (2), the glass material W is cooled to a temperature corresponding to a state where the viscosity exceeds 10 ¹³ poise while maintaining the state of FIG. 6C for a predetermined time (for example, several tens of seconds). . When the press mold 1 and the molded product Wa are cooled to a predetermined temperature or lower, the press head 10B is raised to release the pressing force to the press mold 1.

5) Cooling step After the pressing step, the press mold 1 is sequentially transferred to the first slow cooling chamber P6 and the second slow cooling chamber P7, and the molded body Wa has a temperature sufficiently lower than the transition temperature Tg (for example, And Tg−50 ° C.). At this time, since the upper mold 3 follows the shrinkage of the glass by its own weight, the contact of the molding surface is maintained and good shape accuracy is obtained. Thereafter, the press mold 1 is transferred to the quenching section P8 and quenched with a cooling gas.

6) Mold Disassembly Step The press mold 1 returns to the take-out / insertion chamber P1 and is transported from here to the disassembly / assembly section, where the press mold 1 is disassembled, the molded product Wa is taken out, and a new glass material W is supplied. Done. That is, the press mold 1 containing the molded body Wa is placed on a disassembly / assembly table (not shown) by a robot and positioned by gripping the periphery. The disassembly / assembly table is lowered vertically, and the upper and lower molds 2 and 3 are separated. In the present embodiment, the processing chambers P2 to P7 are in an inert gas atmosphere, and the take-out / insertion chamber P1 is opened to the atmosphere during take-out / insertion. The release to the atmosphere is preferably performed at 250 ° C. or lower.

7) Step of taking out the molded body The transfer arm is inserted between the upper and lower molds, and the molded body Wa is sucked and taken out by the suction pad at the tip. Thereafter, the above steps are repeated.

(Effect of this embodiment)
As described above, according to the mold press molding apparatus P according to the present embodiment, when the upper die 3 is pressed by the second press head 10B, the first press head 11 causes the barrel die 4 to move to the lower die 2. It presses against the receiving surface 23 so as to stand upright. Therefore, the relative inclination between the body mold 4 and the lower mold 2 is surely suppressed by ensuring the parallelism of the upper and lower end faces 44 and 45 of the body mold 4 and the receiving surface 23 of the lower mold flange in advance. it can.

  The pressing surface 12 c of the second press head 12 is formed substantially parallel to the pressing surface 11 a of the first press head 11, and the pressing surface 12 c of the second press head 12 is the large diameter of the second press head 12. It is comprised so as to be orthogonal to the outer peripheral surface of the part 12a. Accordingly, as the second press head 12 is lowered, the first press head 11 can press the barrel die 4 straight (in parallel with the lowering direction of the second press head 12), and the second press head 12 Can press the upper die 2 straight.

  Therefore, since the relative inclination between the trunk mold 4 and the upper mold 2 can be suppressed, tilt generated between the upper and lower surfaces of the molded product (optical lens) can be reliably suppressed.

  In other words, in the present embodiment, the glass material W that has been softened is pressed to a predetermined thickness with a high degree of eccentricity in the first pressing step. Furthermore, this is cooled to a predetermined temperature range, and an appropriate load is applied to the shape of the surface of the glass material W that is affected by the heat shrinkage caused by the cooling, thereby correcting the surface accuracy. This temperature range is in the range of Tg to Ts, and the thickness change amount due to pressing is 5 to 20 μm.

  In the second pressing step, first, the press contact step is performed, the lower die 2 and the barrel die 4 are pressed to fix their relative positions, and the first press head 11 that presses the barrel die 4 is also the result. The position is fixed. Therefore, the position of the second press head 12 guided by the first press head 11 is also indirectly defined. Thereby, the coincidence of the axes of the upper and lower molding surfaces is obtained.

  Therefore, this embodiment can be applied not only to the formation of a biconvex lens and a convex meniscus lens, but also to the formation of a concave meniscus lens and a biconcave lens. Can do.

(Other embodiments)
The above-mentioned mold press forming apparatus P is an apparatus for sequentially transferring the press mold 1 to each processing chamber by rotational transfer. The press head according to the present invention transfers a linear transfer type press apparatus or a mold. It is applicable also to the single press apparatus which press-forms in one process chamber without doing.

  In addition, the arrangement structure of each processing chamber of the above-described mold press molding apparatus can be changed as appropriate in order to make the necessary heating process and cooling process in accordance with the composition of the molding material and the shape of the molded body.

  For example, in the above-described embodiment, two press chambers are provided and pressed using different press heads. However, the press chamber is set as one chamber and only the press head of the present invention is used to press the mold. Can also be done. In this case, it is desirable to appropriately control the temperature in the press chamber. Further, it is possible to change the number of heating units to four or the number of cooling chambers to three.

  Furthermore, in order to further increase the production efficiency of the above process, the same number of heating chambers, press chambers, and cooling chambers may be provided in series, and multiple types of molding that require different temperature conditions and different pressurization conditions may be performed simultaneously. .

  Furthermore, when processing such as heating, pressurization, and cooling is performed in each processing chamber, it is possible to arrange two or more molds and perform the same processing on them simultaneously. In this case, the press chamber is preferably provided with two or more pressing means corresponding to the number of molds.

  The present invention can also be applied to the case where the press mold 1A having the configuration shown in FIG. 8 is used. The basic structure of the press mold 1A shown in this figure is the same as that of the press mold 1 described above, and includes a lower mold 2A, an upper mold 3A, and a body mold 4A. A different point is that the lower mold flange 22 is fitted into the body mold 4 </ b> A, and the body mold lower end surface 44 is directly placed on the mounting surface 56 a of the support base 56.

  In this case, the reference surface for fixing the body mold 4A in the positioning state at the time of pressing is the mounting surface 56a. At the time of pressing, the body die 4A is pressed by the first press head 11 of the press head 10B, and the lower end surface 44 thereof is brought into pressure contact with the placement surface 56a. Therefore, if the perpendicularity between the lower end surface 44 of the body mold 4A and the inner peripheral surface of the hollow portion is precisely defined, the inclination of the body mold 4A can be prevented, and the molding material W can be pressed in that state.

It is a schematic plane block diagram which shows embodiment of the mold press molding apparatus to which this invention is applied. It is a schematic sectional drawing which shows the press mold used for the mold press molding apparatus of FIG. It is a schematic block diagram which shows the cross-sectional structure of the press chamber of FIG. It is explanatory drawing which shows the structure and operation | movement of the 1st press chamber of FIG. It is explanatory drawing which shows the press head of the 2nd press chamber of FIG. It is explanatory drawing which shows the operation | movement in the 2nd press chamber of FIG. It is explanatory drawing which shows the modification of the press head of FIG. It is explanatory drawing which shows another example of a press molding die.

Explanation of symbols

P mold press molding apparatus, P1 to P8 processing chamber, S1 to S67 shutter, P5 (1) first press chamber, P5 (2) second press chamber, 1 press mold, 2 lower mold, 21 lower mold body, 22 Flange, 23 Receiving surface (reference surface), 3 Upper die, 31 Upper die body, 32 Flange, 33 Upper end surface, 4 Drum type, 41 Small diameter portion, 42 Upper large diameter portion, 43 Lower large diameter portion, 44 Lower end surface 45 Upper end surface, 10 press head, 10B press head, 11 first press head, 11a pressing surface, 12 second press head, 12a large diameter portion, 12b small diameter portion, 12c pressing surface, 13 coil spring, W molding material, Wa press product

Claims (16)

A first mold having a molding surface;
A second mold having a molding surface disposed opposite to the first mold;
A barrel mold that coaxially inserts these first and second molds;
A pressing means for press-molding a molding material disposed between the molding surfaces by relatively moving the molding surfaces of the first and second molds in a direction close to each other;
The pressing means is
Pressure contact means for positioning the body mold by bringing the body mold into pressure contact with a positioning reference surface;
A mold press molding apparatus, comprising: a load application unit that presses the first mold while being guided by the press contact unit. In claim 1,
The reference surface is formed on the second mold;
A mold press molding apparatus characterized in that the body mold and the second mold are positioned relative to each other when the body mold is brought into pressure contact with the reference surface by the pressure contacting means. In claim 2,
The pressure contact means has a cylindrical first press head,
The load application means has a second press head inserted inside the first press head,
The pressing means further includes biasing means for biasing the first press head in the pressing operation direction of the second press head in accordance with the pressing operation of the second press head. Mold press molding equipment. In claim 3,
The first press head includes a pressing surface capable of coming into contact with an axial end surface of the body mold on the side where the first mold is inserted,
A mold press molding apparatus according to claim 1, wherein a hole allowing axial movement of the second press head is formed in the pressing surface. In any one of claims 2 to 4,
The second press head includes a pressing surface substantially parallel to the pressing surface of the first press head, and a large-diameter portion capable of sliding contact with the inner peripheral surface of the first press head,
A mold press molding apparatus, wherein the pressing surface of the second press head and the outer peripheral surface of the large-diameter portion are formed to be orthogonal to each other. In claim 5,
The mold press molding apparatus, wherein an axial length of the large diameter portion of the second press head is longer than an axial length from the large diameter portion to the pressing surface of the second press head. In any one of claims 2 to 6,
The second mold includes a large-diameter flange formed at an axial end,
The flange is formed with the reference surface perpendicular to the pressing operation direction of the pressing means,
A mold press characterized in that an upright direction of the barrel mold and a pressing operation direction of the pressing means coincide with each other when the barrel mold is pressed by the pressure contact means and brought into close contact with the reference surface. Molding equipment. In order to press-mold a molding material in a molding die having first and second dies having opposing molding surfaces and a barrel die into which the first and second dies are coaxially inserted, the molding is performed. A press head of a mold press molding apparatus for pressing a mold,
Pressure contact means for positioning the body mold by bringing the body mold into pressure contact with a positioning reference surface;
A press head for a mold press forming apparatus, comprising: a load applying unit that presses the first mold while being guided by the press contact unit. In claim 8,
The pressure contact means has a cylindrical first press head,
The load application means has a second press head inserted inside the first press head,
The apparatus further comprises an urging means for urging the first press head in the pressing operation direction of the second press head in accordance with the pressing operation of the second press head. Press head. In claim 8 or 9,
The first press head includes a pressing surface capable of coming into contact with an axial end surface of the body mold on the side where the first mold is inserted,
A press head for a mold press molding apparatus, wherein a hole allowing axial movement of the second press head is opened in the pressing surface. In any one of claims 8 to 10,
The second press head includes a pressing surface substantially parallel to the pressing surface of the first press head, and a large-diameter portion capable of sliding contact with the inner peripheral surface of the first press head,
A press head for a mold press forming apparatus, wherein the pressing surface of the second press head and the outer peripheral surface of the large diameter portion are formed to be orthogonal to each other. In claim 11,
A press for a mold press forming apparatus, wherein an axial length of the large-diameter portion of the second press head is longer than an axial length from the large-diameter portion to the pressing surface in the second press head. head. An optical element manufacturing method for obtaining an optical element by press-molding a heat-softened molding material using the mold press molding apparatus according to any one of claims 1 to 7,
In order to position the body mold, a pressure welding process in which the body mold is pressed against the reference surface by the pressure welding means;
A load applying step of applying a load to the first mold by the load applying means in a state in which the body mold is in pressure contact. An optical element manufacturing method for obtaining an optical element by press-molding a heat-softened molding material using the mold press molding apparatus according to any one of claims 3 to 7,
A load applying step of applying a load to the first mold by the load applying means in a state in which the body mold is pressed against the reference surface by the pressing means;
In the load application step, when a load is applied by the second press head, the pressing force of the first press head to the body mold is increased by the biasing force of the biasing means. Method. A first mold having a molding surface, a second mold having a molding surface opposed to the first mold, and a body mold for coaxially inserting the first and second molds are provided. A supply step of supplying a molding material between the molding surfaces in the molding die;
A heating step of heating and softening the molding material so as to be in a state suitable for press molding;
In this state, including a pressing step of pressing the molding die and press-molding the molding material,
The pressing step includes a first pressing step that pressurizes the molding material to a predetermined thickness in a predetermined temperature range, and a pressing means that includes a first press head and a second press head. A second pressing step of further pressurizing the molding material at a low temperature,
In the second pressing step, the first press head is brought into pressure contact with at least a part of the second mold, whereby the first press head, the cylinder mold, and the second mold are mutually connected. A pressing process for positioning, and a load applying process for applying a load to the first die using the second press head guided by the first press head while maintaining these positioning states. A method for manufacturing an optical element. In claim 15,
In the load applying step, the pressing force of the first press head to the body mold is increased with the movement of the second press head.

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