JP4780982B2 - Mold press molding apparatus and optical element manufacturing method - Google Patents

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 ensured at the stage of the primary pressurization. However, since only the upper die is pressed at the stage of secondary pressurization, the barrel die 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.

An object of the present invention, in view of the above problems, in addition to improvements to the pressing means for applying a load to press mold, and you press molding equipment capable of performing press-molding without deteriorating eccentric accuracy It is to propose a method for manufacturing 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 has a cylindrical first press head, and the second surface on which a receiving surface orthogonal to the pressing operation direction of the pressing means is formed. A press contact means for positioning the body mold by press-contacting the body mold to a flange of the mold; and a second press head inserted inside the first press head, and being guided by the pressure contact means a load applying means for pressing said first mold, before And a biasing means disposed between the first press head and the second press head. The second press head has one end connected to a pressure rod and a free end side end face of the first press head. While pressing only the mold, the first press head moves in the pressing operation direction by the urging means with the pressing operation of the second press head without being connected to the pressing rod, The body mold is pressed by a pressing surface .

In the present invention, relative movement means that the first mold may move toward the second mold, or the second mold may move toward the first mold.

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 receiving surface orthogonal to the pressing operation direction at the time of press molding by the press contact means, and the load application means keeps this state while maintaining this state. A molding material is pressed by applying a load to the mold 1. 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.

Further, the mold press molding apparatus of the present invention includes a 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. In addition, as the urging means, an elastic member such as a coil spring disposed between the first and second press heads can be used. If it does in this way, the pressing force to the drum mold by the 1st press head can be raised by the energizing force of the energizing means.

In particular, in the configuration of the present invention in which a molding material is press-molded by applying a load to the first die in a state in which the body die is pressed against the second die and the relative positions thereof are fixed, these pressure-contact surfaces are provided. If the orthogonality between the pressure contact surface of the body mold and the inner peripheral surface of the body mold on which the first mold is guided is formed with high precision, the first mold can be pressed without inclination. Therefore, the eccentric accuracy of the molded product can be increased.

In the present invention, 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 second pressing head is formed so that the pressing surface of the second press head and the outer peripheral surface of the large-diameter portion are 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 lower step surface of the diameter portion to the pressing surface.

Then, when the front Symbol barrel die are in close contact with the receiving surface of said pressed second type by the first press head, an upright direction of the barrel die and the pressing operation direction of the pressing means coincides Just do it.

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 receiving surface of the second mold, 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. It is a feature.

Here, when a load is applied by the second press head before Symbol load application step, by the biasing force of the biasing means, it is possible to increase the pressing force to the barrel die of the first press head desirable.

  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 first mold is guided can be formed with high accuracy, the first mold can be pressed without inclination. It is possible to increase the eccentricity accuracy.

  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, Si3N4 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 the length (L2), the upper die 3 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 106 to 109 poise suitable for press molding, and transferred to the press chamber P5. Preferably, the glass material has a temperature at which a viscosity of 106 to 108 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.

A press mold 1 containing a glass material heated to a temperature corresponding to a glass viscosity of 106 to 109 poise in the heating process is shown in FIG. 4 (A) in a state where it is fed into the first press chamber P5 (1). As shown, the upper mold 3 slightly protrudes from the upper end surface 45 of the trunk mold 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) is controlled to a temperature lower than that of the first press chamber P5 (1) (for example, the temperature at which the viscosity of the glass material in the mold reaches a temperature corresponding to 109 to 1013 poise). Has been.

  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 1013 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 3 straight.

Therefore, since the relative inclination between the trunk mold 4 and the upper mold 3 can be suppressed, the 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 is sufficiently softened is pressed to a predetermined thickness with high eccentricity accuracy 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-described mold press molding apparatus P is an apparatus that sequentially transfers 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.

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 .

Claims (6)

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
The cylinder mold is positioned by press-contacting the cylinder mold to a flange of the second mold having a cylindrical first press head and having a receiving surface orthogonal to the pressing operation direction of the pressing means. Pressure welding means;
A second press head inserted inside the first press head, a load applying means for pressing the first mold while being guided by the press contact means ;
Urging means disposed between the first press head and the second press head,
The second press head has one end connected to a pressure bar, and the end surface on the free end presses only the first mold,
The first press head is not connected to the pressure bar and moves in the pressing operation direction by the urging means in accordance with the pressing operation of the second press head, and the cylinder surface is moved by the pressing surface. press-molding apparatus characterized by pressing. In claim 1,
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 2,
The mold is characterized in that an axial length of the large diameter portion of the second press head is longer than an axial length from a lower step surface of the large diameter portion to the pressing surface in the second press head. Press molding equipment. In any one of claims 1 to 3 ,
When the body mold is pressed by the pressure contact means and comes into close contact with the receiving surface of the second mold, the upright direction of the body mold coincides with the pressing operation direction of the pressing means. A mold press molding apparatus characterized by the above. 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 4 ,
In order to position the body mold, a pressure-contacting process in which the body mold is pressed against the receiving surface of the second mold by the pressure-contacting 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. In claim 5,
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.

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