JP4695404B2 - Mold assembly apparatus and optical element manufacturing method - Google Patents

Description

  The present invention presses an optical element such as a lens without applying post-processing such as grinding or polishing to a molding surface by applying a pressing load to a mold that contains and assembles a molding material such as glass. The present invention relates to an assembling apparatus for assembling a mold while supplying a molding material, and a method of manufacturing an optical element using the molding die assembled by the assembling apparatus, and in particular, molding an optical element such as a biconcave lens. The present invention relates to a molding die assembling apparatus and an optical element manufacturing method capable of satisfactorily supplying a molding material onto a lower molding surface having a convex surface.

  There is known a method of manufacturing an optical element such as a lens by press-molding a molding material such as glass by heating with a pair of upper and lower molding dies softened by heating and precisely processed into a predetermined shape (for example, Patent Document 1). 2).

  Patent Document 1 describes a molding method for positioning an optical material with respect to a molding die by moving a pair of positioning members in the molding die and bringing them into contact with each other with the optical material (molding material) interposed therebetween. ing. In this method, the optical element is prevented from being displaced by holding the optical element while being positioned with respect to the molding surface at the time of pressurization or immediately before pressurization.

  In Patent Document 2, the glass preform (molding material) is held at a position away from the mold by the holding means for holding the end surface of the glass preform (molding material), and then the glass preform is heated. A method of releasing the holding by the holding means and pressurizing the glass preform is described. Thus, a chemical reaction between the glass preform and the mold can be avoided during heating, and molding can be performed without impeding the radial flow of the glass preform during pressurization.

Japanese Patent No. 3501580 JP-A-9-286622

  When molding a molding material (such as a glass material) with a precision mold press and molding an optical element such as a lens, it is common to press and mold the molding material between a pair of upper and lower molds having opposing molding surfaces. Is. At this time, it is necessary to supply and arrange the molding material on the lower mold molding surface in advance, but depending on the shape of the optical element to be obtained, it is not always possible to arrange the molding material at the center position of the lower mold molding surface. Not easy.

  For example, in the case of molding a biconcave lens, when the molding material has to be supplied and arranged on the lower mold molding surface having a convex surface, for example, as shown in FIG. 14, it is arranged on the lower mold molding surface. The molding material tends to slide down prior to press molding, and it is difficult to place the molding material on the lower mold surface. If the molding material slides down or is displaced, the optical element to be molded becomes uneven in thickness and not only in a defective shape, but also due to uneven load application due to the uneven thickness, Surface accuracy will deteriorate.

  According to the description of Patent Document 1, an optical material positioning member is arranged in a mold, and this is moved in opposite directions around a reference position by driving means such as a rack and a pinion, and the optical material is sandwiched between them. By abutting and stopping, the optical material is positioned with respect to the mold, and the positioning member is retracted by the driving means immediately before the molding surface abuts on the material during pressing.

  However, according to this method, since the positioning member is disposed inside the mold, the mold has an extremely complicated structure. For this reason, the heat capacity of the mold becomes large, and it is difficult to efficiently perform temperature control for temperature increase and decrease. Furthermore, if structures such as racks and pinions are placed in the vicinity of the mold, not only will the equipment increase in size, but it will also be necessary to consider the effects of thermal deformation of these structures, making the equipment design significantly more complex To do.

  Furthermore, when a mold consisting of upper and lower molds is fixed to the press device, and the temperature rise, press, and cooling are performed at the same position, the molding material should be positioned by a movable member that complicates the device as described above. Although it is possible to some extent, a molding method in which a molding material is housed in a molding die separated from a press apparatus, and each of the processing chambers in the apparatus is transferred to sequentially perform appropriate processing (details will be described later). However, it is extremely inefficient and practically impossible to provide such a large movable member as described above in each mold.

  Further, Patent Document 2 discloses a drawing in which a flat plate-shaped preform is pressure-formed by an upper and lower mold having convex surfaces. And in patent document 2, it heats in the state which mounted the preform on the upper end of a holding ring, and then lowers a holding ring with a drive means, The preform held inside a shaping | molding die is immediately before pressurization. Then, the preform is released from the holding ring, the preform is placed on the lower mold, and then the preform is pressurized by the upper and lower molds.

  However, even in such a method, supply of the molding material to the molding die, pressurization, molding, and the like, sequentially performing appropriate processing while transferring the molding die containing the molding material to each processing chamber In the molding method in which the body is not taken out at the same position, there is an inconvenience that the driving means of the holding means (the push rod shown in FIG. 2 of Patent Document 2 or the gas supply means shown in FIG. 3) cannot be installed. .

  Furthermore, in the apparatus disclosed in Patent Document 2, since there is no means for regulating the mutual position of the upper and lower molds in the horizontal direction, the upper and lower molds cannot be coaxial. For this reason, eccentricity (mutual horizontal shift and mutual tilt) occurs between the first surface and the second surface of the optical element to be molded, and sufficient optical performance cannot be obtained.

  The present invention is considered in view of the above circumstances, and even when the lower mold molding surface has a convex surface, the molding material is accommodated in a state of being arranged at an appropriate position on the lower mold molding surface. The purpose of the present invention is to provide a mold press mold assembling apparatus and an optical element manufacturing method capable of assembling the mold, and the mold having the upper and lower molds is transferred to the apparatus without being fixed to the press apparatus. However, it is applicable to a molding method in which appropriate processes are sequentially performed, and an object is to provide an assembly apparatus for a mold press mold and an optical element manufacturing method capable of efficiently mass-producing high-precision optical elements.

In order to achieve the above object, an apparatus for assembling a molding die according to the present invention includes a lower die having a convex molding surface, an upper die having a molding surface formed on a surface facing the lower molding surface, An assembly apparatus for assembling a molding die provided with a lower die and a barrel die capable of inserting the upper die from both end sides in a state where a molding material is accommodated, wherein the barrel die and the lower die A first driving means for relatively moving them closer to and away from each other, a supply means for supplying a molding material onto the lower mold molding surface, and the molding material supplied by the supply means to the lower mold molding surface. The holding means that holds the molding material, the second drive means for holding the molding material by the holding means, and the retracting the holding means, and the molding by the relative proximity of the body mold and the lower mold At least the largest outer diameter part of the material is inserted into the barrel mold and the front When the molding material by the lower molding surface the inner peripheral surface of the barrel die is held, and a control means for actuating the second driving means so as to retract said retaining means from the said lower mold molding surface It is a configuration with.

  With such a configuration, it is possible to prevent the molding material supplied on the lower mold surface from slipping or being displaced without providing an additional member for holding and supporting the molding material inside the molding die. In addition, it is possible to assemble the mold by accommodating the molding material in a state of being arranged at an appropriate position on the lower mold molding surface.

The method for producing an optical element of the present invention includes a lower mold on which a molding surface having a convex surface is formed, an upper mold on which a molding surface is formed on a surface facing the lower mold molding surface, the lower mold, and the A method of manufacturing an optical element by press-molding a molding material using a molding die having an upper die and a barrel die that can be inserted from both ends, and is supplied onto the lower die molding surface. While holding the molding material by the holding means disposed on the lower mold molding surface, the body mold and the lower mold are relatively brought close together so that at least the maximum outer diameter portion of the molding material is After the molding material is inserted into the barrel mold and the molding material is held by the lower mold molding surface and the inner peripheral surface of the barrel mold, the holding means is retracted from the lower mold molding surface, and then the lower mold and The molding material is press-molded between the upper molds.

  This method prevents slipping or misalignment of the molding material supplied on the lower mold surface without providing additional members to hold and support the molding material inside the mold. It is possible to assemble the mold by accommodating the molding material in an appropriate position on the lower mold molding surface, and the optical element to be molded is eccentric without causing uneven thickness or shape defect. The optical element can be manufactured by controlling the accuracy precisely and easily.

In addition , after at least the maximum outer diameter portion of the molding material is inserted into the barrel mold and the molding material is held by the lower mold molding surface and the inner peripheral surface of the barrel mold , from above the lower mold molding surface by so as to retract said retaining means, so that the retention means does not interfere with the assembly of the mold, even retracts the holding means from the lower mold molding surface on the inner circumference of the lower mold molding surface and the body type The surface can hold the molding material more stably.

  In the method for producing an optical element of the present invention, the molding material can be formed into a cylindrical shape or a biconvex curved shape. When the molding material has a biconvex curved shape, the holding means holds the lower side from the maximum outer diameter portion of the molding material and secures an open space around the maximum outer diameter portion. be able to.

  According to such a method, the holding means does not contact the maximum outer diameter portion of the molding material, and an open space can be secured around the maximum outer diameter portion, so that the maximum outer diameter portion of the molding material can be reliably secured to the body. Can be inserted into the mold.

  Further, in the method for manufacturing an optical element of the present invention, the molding die assembled in a state where the molding material is accommodated is transferred to a plurality of processing chambers including a heating chamber, a press chamber, and a cooling chamber. By performing a process including heating, pressing, and cooling in the chamber, the molding material can be press-molded.

  According to such a method, it is possible to efficiently raise and lower the temperature of the molding die while simultaneously using a large number of molding dies, and shorten the actual time (molding cycle time) required for individual molding. And when assembling the mold in the method of the present invention, it is possible to prevent the molding material supplied on the lower mold molding surface from slipping and misalignment without providing a large movable member in the mold. A manufacturing method can be used suitably.

As described above, according to the present invention, without providing an additional member for holding and supporting the molding material inside the molding die, the sliding of the molding material supplied on the lower molding surface and the position The mold can be assembled by accommodating the molding material in a state of being prevented from being displaced and arranged at an appropriate position on the lower mold molding surface.
For this reason, an optical element can be manufactured by accurately and easily controlling the eccentricity accuracy without causing a thickness deviation or shape defect in the molded optical element.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a mold assembly apparatus and an optical element manufacturing method according to the present invention will be described below with reference to the drawings.

[Mold press mold]
First, an example of a mold press mold (hereinafter simply referred to as a mold) that is preferably used in the present invention will be described. Here, FIG. 1 is a schematic cross-sectional view of the mold, showing a state when a press load is applied (see FIG. 10 (11)). 8-12 is explanatory drawing which shows each process in embodiment of the manufacturing method of the optical element which concerns on this invention mentioned later.

The molding die shown in FIG. 1 includes an upper die 10, a lower die 20, and a body die 30, and press-molds a molding material 50 between the upper die 10 and the lower die 20.
In the example shown in the figure, the body mold 30 is configured so that the upper and lower molds 10 and 20 are slidably guided when assembling the molding mold or press molding, thereby restricting the horizontal relative positions thereof. The coaxiality of 10, 20 is ensured.
For this reason, the sliding clearance between the body mold 30 and the upper and lower molds 10 and 20 is preferably 10 μm or less, particularly 5 μm or less in consideration of the required eccentric accuracy of the optical element. If the sliding clearance is controlled, the eccentricity between the molding surfaces 11 and 21 of the upper and lower molds 10 and 20 (shift: horizontal displacement of the molding surfaces 11 and 21 of the upper and lower molds 10 and 20, tilt: upper and lower molds 10 and 20. Can be suppressed with high accuracy.

  In the illustrated mold, during press molding, the upper mold 10 is slidably guided in the cylinder mold 30 with respect to the lower mold 20 fitted in the cylinder mold 30, and the upper and lower molds 10, 20 are relative to each other. Although it is comprised so that it may approach and space apart, it can also be comprised contrary to this. That is, the lower mold 20 may be slidably guided in the first trunk mold 30 with respect to the upper mold 10 fitted in the trunk mold 30, and the upper and lower molds 10 and 20 are coaxial. The specific configuration is not limited as long as it is relatively close to and away from each other while ensuring the above.

  In such a body mold 30, when the upper and lower molds 10, 20 approach and separate from each other, vent holes 33, 33 are provided so that the movement of the upper and lower molds 10, 20 is not hindered by a pressure difference between the inside and outside of the mold. Is preferably provided. In particular, as shown in the drawing, when the inner diameter of the body mold 30 is changed to be a stepped part, or when the upper end surface of the body mold 30 and the upper end surface of the upper mold 10 are substantially on the same plane. A vent hole 33 is provided at a position that is approximately the same height as the outer edge of the molding surface 11 of the upper mold 10, and the volume in the gap between the stepped part and the gap between the molding material 50 and the upper and lower molds 10, 20 is increased or decreased. Thus, it is preferable that the atmospheric gas is conducted through the vent hole 33 so that the inside of the mold is always equal to the external pressure. This makes it possible to smoothly perform press molding and assembly / disassembly of the mold.

  The upper mold 10 has a molding surface 11 formed on the lower surface facing the lower mold 20. In the example shown in FIG. 1, the molding surface 11 is a convex surface, but may be a concave surface or a flat surface. Further, a flange portion 12 having a diameter larger than that of the molding surface 11 is formed at the upper portion of the upper mold 10, and this flange portion 12 is accommodated in a large-diameter inner peripheral portion 31 formed at the upper portion of the body mold 30. The

  At this time, when the upper surface of the upper mold 10 and the upper surface of the trunk mold 30 are flush with each other, the lower surface of the flange portion 12 formed on the upper mold 10 and the small-diameter inner peripheral section formed on the trunk mold 30 It is preferable that a gap G having a predetermined dimension or more is secured between the upper end of 32. By securing such a gap G, the upper die 10 is pushed in until the upper surface of the upper die 10 coincides with the upper surface of the barrel die 30 during press molding, and the thickness of the molded body 15 is once determined. However, it is possible to continue to apply the necessary load (only the weight of the upper mold 10 may be applied) to the molded body 51 and to allow the upper mold 10 to descend following the thermal contraction of the molded body 51 (FIG. 10 (11), (12)).

  A molding surface 21 having a convex surface is formed on the upper surface of the lower mold 20 facing the upper mold 10. Further, a flange portion 22 having a diameter larger than that of the molding surface 21 is formed at the lower portion of the lower mold 20. At the time of press molding, the lower surface of the barrel die 30 is brought into contact with the upper surface of the flange portion 22 and is brought into close contact with each other by the press pressure, whereby the mutual position of the lower die 20 and the barrel die 30 is defined with high accuracy. This also suppresses the tilt.

In such a mold, there are no particular restrictions on the materials of the upper mold 10, the lower mold 20, and the body mold 30. List cermets of silicon carbide, silicon, silicon nitride, tungsten carbide, aluminum oxide or titanium carbide, or those coated with diamond, refractory metal, noble metal alloy, carbide, nitride, boride, oxide, etc. Can do.
Further, the molding surfaces 11 and 21 of the upper and lower molds 10 and 20 are composed of a single component layer or a mixed layer of amorphous and / or crystalline graphite and / or diamond in order to prevent glass fusion. It is preferable to use a carbon film or a release film made of a noble metal alloy.

[Molding die assembly equipment]
Next, an embodiment of a mold assembly apparatus (hereinafter simply referred to as an assembly apparatus) according to the present invention will be described with reference to an example of assembling the mold shown in FIG. Here, FIG. 2 shows one process of an example of assembling the mold shown in FIG. 1 by the assembling apparatus according to the present embodiment. Each of FIGS. 2 (a) and 2 (b) is shown in FIG. ), (6).

  The assembling apparatus in the present embodiment is for assembling a molding die while supplying the molding material 50 onto the molding surface 21 of the lower die 20, and the body die 30 and the lower die 20 are relatively moved when the molding die is assembled. The lower mold 20 can be incorporated into the body mold 30 by bringing them close to each other. When the molded body 51 is taken out by disassembling the mold after press molding, the body mold 30 and the lower mold 20 The lower mold 20 can be extracted from the body mold 30 by relatively separating them.

In the example shown in the figure, the upper die 10 is incorporated in the body die 30 in advance when assembling the forming die. Then, in a state where the upper mold 10 is inserted, the position of the body mold 30 is fixed by the holding means 80, and the lower mold 20 mounted on the mounting table 70 configured to be movable up and down (FIG. 2 ( a)), the mounting table 70 is moved up and down, so that the mounting table 70 approaches and moves away from the body mold 30 (see FIG. 2B).
At this time, the mounting table 70 is provided with an opening 71 on the surface on which the lower mold 20 is mounted, and the lower mold 20 is brought into close contact with the mounting table 70 by sucking atmospheric gas from the opening 71. It is preferable to configure so that the lower mold 20 is not displaced on the mounting table 70.

In the present embodiment, as the driving means for raising and lowering the mounting table 70, that is, as the driving means (first driving means) for moving the body mold 30 and the lower mold 20 relatively close to each other, the body mold 30 is used. There is no particular limitation as long as the mounting table 70 can be moved up and down along the vertical direction while maintaining the horizontal positional relationship between the lower mold 20 and the lower mold 20.
For example, a lifting mechanism that lifts and lowers the mounting table 70 using a hydraulic cylinder, an air cylinder, or the like, or a lifting mechanism that lifts and lowers the mounting table 70 by converting the rotational motion into a linear motion by rotating a screw shaft, etc. Can do.

In the present embodiment, the position of the body mold 30 is fixed and the lower mold 20 is configured to approach and separate from the body mold 30, but conversely, The body mold 30 can be configured to approach and separate from the lower mold 20 by fixing the position and moving the holding means 80 up and down.
Thus, the specific configuration of the first drive means in the present invention is not limited to the above example as long as the body mold 30 and the lower mold 20 can be relatively close to each other and separated from each other.

Further, the assembling apparatus according to the present embodiment includes supply means for supplying the molding material 50 onto the molding surface 21 of the lower mold 20 when assembling the molding die.
The supply means can be, for example, a transfer arm 60 provided with a suction pad 61 at the tip (see FIGS. 8 (3) and (4)), but molding the lower mold 20 with a positional accuracy within a predetermined range. The specific configuration is not particularly limited as long as the molding material 50 can be supplied onto the surface 21.

Furthermore, the assembling apparatus in the present embodiment includes a holding member 40 as a holding unit that holds the supplied molding material 50 on the molding surface 21 of the lower mold 20.
The holding member 40 stably holds the molding material 50 supplied on the molding surface 21 of the lower mold 20 (see FIG. 2A), and prevents the molding material 50 from slipping or shifting. is there. Then, when assembling the mold, the lower mold 20 is molded while maintaining the relative positional relationship with the lower mold 20 until the body mold 30 and the lower mold 20 come close to each other and the two are in a predetermined positional relationship. It has a function of continuing to hold the molding material 50 on the surface 21 (see FIG. 2B). In the example shown in FIG. 2, the trunk mold 30 and the lower mold 20 are close to each other, and a part of the molding material 50 is inserted into the trunk mold 30, and the molding surface 21 of the lower mold 20 and the inner peripheral surface of the trunk mold 30. Thus, the molding material 50 is held by the holding member 40 until the molding material 50 is held.

For example, as shown in FIG. 3, the holding member 40 can be composed of a pair of arms 45 and 45 each having a holding portion 41 at the distal end portion. The specific configuration of 40 is not particularly limited.
In the illustrated example, the holding member 40 is configured to be able to open and close the holding portion 41 by moving the arms 45 and 45 close to and away from each other on a horizontal plane substantially equal to the molding surface 21 of the lower mold 20. And the holding member 40 comes to be able to hold | maintain the shaping | molding raw material 50 on the shaping | molding surface 21 of the lower mold | type 20 by closing the holding | maintenance part 41 by making the arms 45 and 45 adjoin each other. Yes. Further, the holding member 40 releases the holding of the molding material 50 by separating the arms 45, 45 and opening the holding portion 41, and can be retracted from between the body mold 30 and the lower mold 20. Yes.
The holding member 40 can be maintained in a relative positional relationship with the lower mold 20 by being attached to the mounting table 70. Moreover, in FIG. 3, the holding | maintenance part 41 of the closed state is shown with the broken line.

  When holding the molding material 50 on the holding member 40, the holding member 40 is put on standby on the molding surface 21 of the lower mold 20 with the holding unit 41 closed, and the molding material 50 is held on the holding unit 41 by the transfer arm 60. By mounting, the molding material 50 can be held by the holding member 40. Further, the holding portion 41 is held so as to sandwich the molding material 50 from the opposite direction while maintaining the state held by the conveyance arm 60 with respect to the molding material 50 supplied onto the molding surface 21 of the lower mold 20 by the conveyance arm 60. The holding by the transfer arm 60 may be released after closing and holding the molding material 50 by the holding member 40 or simultaneously with holding the molding material 50 by the holding member 40.

  In the present embodiment, the driving means for opening and closing the holding portion 41, that is, the driving means (second driving means) for holding the molding material 50 by the holding member 40 and for retracting the holding member 40 are, for example, A linear motor, a stepping motor, or the like can be used, but in synchronization with the first driving means for moving the body mold 30 and the lower mold 20 relatively close to each other, the body mold 30 and the lower mold 20 are Is not particularly limited as long as the holding member 40 can be controlled by an arbitrary control means so that the holding member 40 is retracted from between the body mold 30 and the lower mold 20.

  Here, an example in which the first driving means and the second driving means are controlled in synchronization will be described. FIG. 13 is a block diagram illustrating an example of the control unit. The control unit 100 includes a control unit 101 that controls driving of the first drive unit 110 and the second drive unit 120, and a detection unit 102.

  In the illustrated control means, when the molding material 50 is held by the holding member 40 (see FIG. 9 (5)), a start signal for starting assembly of the molding die is input to the control unit 101. When the start signal is input, the control unit 101 drives the first driving unit 110, so that the mounting table 70 starts to rise. The position of the mounting table 70 is detected by the detection unit 102, and the mounting table 70 is raised until the body mold 30 and the lower mold 20 have a preset positional relationship. Then, when the mounting table 70 is raised until the body mold 30 and the lower mold 20 are in a predetermined positional relationship, the detection unit 102 outputs a detection signal to the control unit 101. The control unit 101 to which the detection signal is input stops driving the first drive unit 110 and interrupts the ascent of the mounting table 70 (see FIG. 9 (6)). On the other hand, the control unit 101 drives the second driving unit 120 to release the holding of the molding material 50 by the holding member 40 and retract the holding member 40 (see FIG. 9 (7)).

When the detection unit 102 detects that the retraction of the holding member 40 is completed, a detection signal is output to the control unit 101, and the control unit 101 to which the detection signal is input stops driving the second drive unit 120. To do. On the other hand, the control unit 101 drives the first driving unit 110 again to further raise the mounting table 70. When the lower mold 20 is incorporated into the body mold 30, the detection unit 102 outputs a detection signal to the control unit 101, and the control unit 101 to which the detection signal is input stops driving the first drive unit 110. Then, the rising of the mounting table 70 is stopped (see FIG. 9 (8)).
Thereby, the assembly of the mold is completed.

  There is no restriction | limiting in particular in the material of the shaping | molding raw material 50 used for this invention, For example, it can be set as glass raw materials, such as a glass preform. The shape of the molding material 50 is, for example, a block-shaped optical glass cut and polished and processed into a cylindrical shape, a spherical shape, etc. (cold processing), or dropped from a molten state onto a receiving mold. Alternatively, it can be preliminarily molded (hot molded) into a spherical shape, a biconvex curved surface shape, or the like by flowing down. In the present invention, a cold-worked columnar glass material, a hot-formed biconvex curved glass material, or a pre-molding such as processing a flat or concave surface further hot after hot forming. Preferred glass material.

Further, the diameter of the molding material 50 needs to be smaller than the diameter of the molded body 51 to be obtained (the inner diameter of the body mold 30), and is preferably slightly smaller. If it does in this way, since the molding material 50 accommodated in the shaping | molding die will not be unevenly distributed on the lower mold | type 20, it will become difficult to produce uneven thickness at the time of press molding. Specifically, for example, 90 to 99% of the diameter of the molded body 51 to be obtained is preferable.
The molded body 51 taken out from the mold can be centered (the outer periphery of the molded body is cut off and the center of the outer diameter coincides with the optical center). It is preferable that the shape of the final optical element is made as it is without performing the machining.

  The holding member 40 is designed in consideration of the shape and size of the molding material 50. For example, as shown in FIG. 2, when the molding material 50 is cylindrical, the holding member 40 is held. In accordance with the vertical cross-sectional shape of the portion to be formed, the holding portion 41 is provided with a step portion 42, and the step portion 42 supports the bottom surface and the side surface along the outer peripheral edge portion on the lower surface side of the molding material 50. The material 50 is preferably held by the holding member 40. As shown in FIG. 4, when the molding material 50 has a biconvex curved shape, a taper 43 having a shape following the surface on which the molding material 50 is held is provided at the tip of the holding portion 41. Can be easily held horizontally.

  As described above, the holding portion 41 is formed in a shape that can easily hold the molding material 50 by providing the stepped portion 42, the taper 43, and the like according to the shape of the portion where the molding material 50 is held. It is preferable to hold the molding material 50 more stably. However, the stepped portion 42 and the taper 43 are not provided, and the shape is such that the molding material 50 is held substantially by line contact with the corner portion. May be. Further, in the illustrated example, the molding material 50 is held over the entire circumference. However, as long as the molding material 50 can be stably held, the shape of the holding portion 41 is, for example, a part that contacts the molding material 50. However, it may be provided at regular intervals along the circumferential direction.

Further, the thickness of the holding member 40 may be sufficient to hold and support the supplied molding material 50 in consideration of the strength and rigidity of the holding member 40, but the thickness of the holding member 40 is not limited. If it is too large, the following problems may occur.
For example, when the molding material 50 has a cylindrical shape, the area of the portion that supports the side surface of the molding material 50 becomes larger, depending on the shape of the step provided in the holding portion 41, whereas the side surface of the molding material 50 is increased. If the area of the portion that can come into contact with the inner peripheral surface of the body mold 30 is relatively small, the holding of the molding material 50 by the molding surface 21 of the lower mold 20 and the inner peripheral surface of the body mold 30 tends to become unstable. There is a possibility that a defect or a problem that the holding member 40 interferes with the molding surface 21 of the lower mold 20 may occur.
For this reason, it is preferable that the maximum thickness of the holding member 40 is not more than half the thickness of the molding material 50.

Further, when the molding material 50 has a biconvex curved shape, it is preferably held by the holding portion 41 at a position closer to the lower mold 20 than the maximum outer diameter portion of the molding material 50 (see FIG. 4). By setting the position for holding the molding material 50 in this way, the holding portion 41 does not contact the maximum outer diameter portion of the molding material 50, and an open space can be secured around the maximum outer diameter portion.
Thereby, when the molding material 50 is inserted into the trunk mold 30 due to the proximity of the trunk mold 30 and the lower mold 20, the maximum outer diameter portion of the molding material 50 is reliably inserted into the trunk mold 30. Even if the holding of the molding material 50 by the holding unit 40 is released, the molding material 50 can be stably held by the molding surface 21 of the lower mold 20 and the inner peripheral surface of the barrel mold 30.

  In the present embodiment, the timing for retracting the holding member 40 from between the body mold 30 and the lower mold 20 is a part of the molding material 50 (molding material as shown in FIG. 2B and FIG. 4B). When the shape of 50 is a biconvex curved surface shape, the maximum outer diameter portion of the molding material 50) is inserted into the body mold 30, and the molding material 50 is formed by the molding surface 21 of the lower mold 20 and the inner peripheral surface of the cylinder mold 30. When the state is held, the arms 45 and 45 are driven in a direction away from each other to release the holding of the molding material 50 and at the same time, the retraction of the holding member 40 may be started. However, the holding member 40 can be retracted at the following timing.

  That is, for example, as shown in FIG. 5, while maintaining the relative positional relationship between the lower mold 20 and the protection member 40 from the state shown in FIG. By holding them close, the holding member 40 that is in contact with the lower surface of the body portion 30 is pushed down relative to the lower mold 20, and thus the holding of the molding material 50 by the holding member 40 is released and then held. The member 40 may be retracted.

  If the timing at which the holding member 40 is retracted in this way, the holding of the molding material 50 by the holding member 40 is released in a state where a larger portion of the molding material 50 is inserted into the body mold 30. The holding of the molding material 50 by the molding surface 21 of the lower mold 20 and the inner peripheral surface of the body mold 30 can be made more stable.

  For example, when the molding material 50 has a biconvex curved shape, the maximum outer diameter portion of the molding material 50 can be more reliably inserted into the body die 30 when the holding member 40 is retracted. In the example shown in FIG. 5, the molding material 50 has a biconvex curved shape, but such a mode is also effective when the molding material 50 has a cylindrical shape. In this case, although not particularly illustrated, when the holding member 40 is retracted, the entire molding material 50 can be inserted into the body mold 30.

Here , FIG. 6 is a reference diagram showing an example in which the molding material 50 is held by being held between the lower mold 20 and the upper mold 10 .

  For the material of the holding member 40 as described above, for example, a resin or a metal such as SUS or aluminum can be used. In addition, the molding material 50 can be preheated and then supplied to the molding die. At this time, in the case where a resin is used for the holding member 40, in consideration of the preheating temperature of the molding material 50, the molding material 50 is about 200 ° C. It is preferable to select a heat-resistant one. In addition, the holding member 40 may be appropriately coated on the contact portion with the molding material 50 (for example, the holding portion 41) to prevent fusion.

[Mold press molding equipment]
Next, a mold press molding apparatus (hereinafter simply referred to as a molding apparatus) suitable for carrying out the optical element manufacturing method according to the present invention will be described. Here, FIG. 7 is a schematic plan view of a rotary transfer molding apparatus shown as an example of such a molding apparatus.

The molding apparatus shown in FIG. 7 includes an extraction / insertion chamber P1 and a large number of processing chambers P2 to P8 arranged side by side in the circumferential direction.
In the take-out / insertion chamber P1, an operation of taking out the molding die that has been molded and an operation of inserting a molding die that contains a molding material to be newly used for molding are performed. The molding die inserted from the take-out / insertion chamber P1 is always held in a state in which a molding material (or molded body) is accommodated, for example, by being held on a holding table attached to a rotary table that rotates in the direction of the arrow in the figure. It sequentially passes through the processing chambers P2 to P8 under a non-oxidizing gas atmosphere (inert gas atmosphere). The rotary table rotates intermittently at regular intervals, and the mold moves between adjacent processing chambers by this intermittent rotation. And this fixed time becomes a molding cycle time.

  Here, P2 is a first heating chamber, P3 is a second heating chamber, and P4 is a third heating chamber (or soaking chamber), which are also collectively referred to as a heating unit. P5 is a press chamber, and a press load is applied to a mold set at a temperature suitable for press molding in the heating section. P6 is a first slow cooling chamber, P7 is a second slow cooling chamber, and P8 is a rapid cooling chamber. These are also collectively referred to as a cooling section, and the mold is cooled after a press load is applied. These processing chambers P2 to P8 are arranged at substantially equal intervals, and are controlled to a temperature suitable for each processing, and in order to keep the temperature in each processing chamber at a predetermined temperature, shutters S1 to S6 are used. It is partitioned.

If a molding apparatus as shown in FIG. 7 is used, a desired optical element can be efficiently obtained by subjecting a molding die containing a molding material (or molded body) to appropriate processing while sequentially transporting each processing chamber. Can be manufactured.
That is, since the temperature of the mold is increased to a temperature suitable for press molding, press load is applied, and the subsequent cooling process is performed by the mold passing through each processing chamber arranged two-dimensionally. These molding dies can be used at the same time, and the actual time (molding cycle time) required for each molding is shortened.
As described above, the time required for the rotary table to rotate intermittently and the mold to move between adjacent processing chambers is the molding cycle time.

  In the method of manufacturing an optical element according to the present invention, a molding die containing a molding material (or molded body) is transferred to each processing chamber such as a heating chamber, a press chamber, and a cooling chamber, and heating, pressing, and cooling are performed. Although it implements suitably in the shaping | molding apparatus which performs the suitable process including sequentially, the specific structure of such a shaping | molding apparatus is not restrict | limited to the above-mentioned example. For example, in the above-described example, the mold is transferred by the rotary table, but it is configured so that it can pass through each processing chamber arranged two-dimensionally (in some cases three-dimensionally) at a predetermined time interval. If it is what is carried out, the means in particular to transfer a shaping | molding die will not be restrict | limited.

  Moreover, the arrangement configuration of each processing chamber can be appropriately changed in order to optimize the heating process and the cooling process in accordance with the composition of the molding material and the shape of the molded body to be obtained. For example, changes such as four heating chambers or three annealing chambers can be performed. In order to further improve production efficiency, the same number of heating chambers, press chambers, and cooling chambers are provided in series, and multiple types of press molding that require different temperature conditions and different pressurization conditions are performed simultaneously. May be.

  Further, in order to improve production efficiency, for example, a plurality of molds are provided in each processing chamber by, for example, allowing a plurality of holders used in the same process to pass through each processing chamber at the same time. They can be processed simultaneously. Specifically, when processing such as heating, application of a press load, and cooling processing is performed in each processing chamber, two or more molds are arranged in the traveling direction, and the same processing is simultaneously performed on them. Can do. In this case, the press chamber is preferably provided with two or more pressing means arranged in the traveling direction.

[Method for Manufacturing Optical Element]
Next, an embodiment in which the molding die shown in FIG. 1 is applied to the molding apparatus shown in FIG. 7 will be described as an embodiment of the optical element manufacturing method according to the invention. Here, FIG. 8 is explanatory drawing which shows process (1)-(4) in the manufacturing method of the optical element which concerns on this embodiment, FIG. 9 is explanatory drawing which shows the said process (5)-(8), figure. 10 is an explanatory view showing the steps (9) to (12), FIG. 11 is an explanatory view showing the steps (13) to (16), and FIG. 12 is an explanatory view showing the steps (17). .

Process (1)-(5): Molding material supply process In this embodiment, in the state which the upper mold | type 10 incorporated in the trunk | drum 30 and the lower mold | type 20 spaced apart (refer FIG. 8 (1)), a molding material 50 is supplied onto the molding surface 21 of the lower mold 20. At this time, the holding member 40 waits with the holding portion 41 closed on the molding surface 21 of the lower mold 20 (see FIG. 8B). On the other hand, the forming material (for example, glass preform) 50 is sucked and held by the transport arm 60 with the suction pad 61 and transported above the molding surface 21 (see FIG. 8 (3)).
Then, after the suction pad 61 reaches the molding surface 21 of the lower mold 20 with accuracy within a predetermined range, and the molding material 50 is placed on the holding member 40 (holding portion 41) (see FIG. 8 (4)). By releasing the adsorption, the molding material 50 is held by the holding member 40 (see FIG. 9 (5)).

At this time, in the illustrated example, the holding portion 41 is provided with a stepped portion 42, and the stepped portion 42 supports the bottom surface and the side surface along the outer peripheral edge on the lower surface side of the cylindrical shaped material 50, thereby forming the forming material. 50 is held by the holding member 40. Thereby, the molding material 50 is stably held on the molding surface 21 of the lower mold 20 without sliding down or causing a positional shift.
In the illustrated example, the molding material 50 has a cylindrical shape, but may have a convex curved surface such as a biconvex curved surface shape. When the molding material 50 has a biconvex curved shape, it is preferably held by the holding member 40 at a position closer to the lower mold 20 than the maximum outer diameter portion of the molding material 50 (see FIG. 4).

  When the molding material 50 is supplied, the center of the suction pad 61 and the center of the molding material 50 are aligned in advance, and the center of the suction pad 61 and the center of the molding surface 21 of the lower mold 20 are provided. It is preferable to control the operation of the transfer arm 60 so that the molding material 50 is placed on the holding member 40 in a state in which they substantially match, and the transfer arm 60 is retracted immediately after the molding material 50 is supplied. To do. Further, the position of the body mold 30 in which the upper mold 10 is incorporated is fixed by the holding means 80.

Steps (6) to (8): Mold Assembling Step When the molding material 50 is held by the holding member 40, the mounting table 70 is raised while the position of the body die 30 is fixed by the holding means 80, and the holding member While maintaining the relative positional relationship between the lower mold 20 and the lower mold 20, the lower mold 20 approaches the trunk mold 30.

  When the mounting table 70 is raised by a predetermined amount, a part of the molding material 50 is inserted into the trunk mold 30, and the molding material 50 is also held by the molding surface 21 of the lower mold 20 and the inner peripheral surface of the trunk mold 30. (See FIG. 9 (6)). Next, the holding member 40 releases the holding of the molding material 50 and retracts from the molding surface 21, but the molding material 50 is held by the molding surface 21 of the lower mold 20 and the inner peripheral surface of the trunk mold 30. Therefore, it does not slide off from the molding surface 21 or is not displaced (see FIG. 9 (7)).

  At this time, when the molding material 50 has a cylindrical shape, the thickness of the molding material 50 is set to h in order to stabilize the holding by the molding surface 21 of the lower mold 20 and the inner peripheral surface of the body mold 30. The length of the portion inserted into the body mold 30 is preferably 0.2 h or more.

After the holding member 40 is retracted from the molding surface 21 of the lower mold 20, the mounting table 70 is further raised to incorporate the lower mold 20 into the body mold 30 (see FIG. 9 (8)). At this time, the clearance between the body mold 30 and the lower mold 20 is preferably 5 μm or less. Further, it is preferable that the upper mold 10 and the trunk mold 30 assembled in advance have the same clearance. Thereby, the eccentricity between the molding surfaces 11 and 21 of the upper and lower molds 10 and 20 can be suppressed with high accuracy.
When the lower mold 20 is assembled in the body mold 30 and the upper surface of the flange portion 22 of the lower mold 20 abuts on the lower surface of the body mold 30, as shown in FIG. The upper surface of the mold 10 is pushed up to a position higher than the upper surface of the body mold 30.

  In assembling the mold, the first driving means for bringing the body mold 30 and the lower mold 20 close to each other, the holding of the molding material 50 by the holding member 40, and the molding surface 21 of the lower mold 20 of the holding member 40 from above. The second drive means for performing retraction can be controlled in synchronization with the control means as described above. Further, when assembling the molding die, the upper die 10 and the barrel die 30 may be lowered by the holding means 80 instead of raising the mounting table 70.

In the above steps (1) to (8), the mounting table is obtained by sucking the atmospheric gas from the opening 71 provided in the mounting table 70 so that the lower mold 20 does not shift on the mounting table 70. The lower mold 20 can be adhered and fixed on the 70. Further, as will be described later, when the mold is disassembled, the lower mold 20 is brought into close contact with the mounting table 70 by suction of the atmospheric gas, and the position when the lower mold 20 is extracted from the body mold 30 is maintained. Thus, it is possible to avoid the horizontal relative position of the lower mold 20 and the trunk mold 30 from shifting.
In addition, according to said process (1)-(8), the shaping | molding die accommodated and assembled with the shaping | molding raw material 50 is inserted in a shaping | molding apparatus from the taking-out / insertion chamber P1 in the shaping | molding apparatus shown in FIG. However, the above steps (1) to (8) may be performed in the take-out / insertion chamber P1.

Step (9): Heating step The molding material 50 is accommodated and the molding die inserted into the molding apparatus is sequentially transferred to the heating chambers P2 to P4 by holding it on a holding stand 75 attached to a rotary table. While heating (see FIG. 10 (9)). Thus, the temperature of the molding material 50 together with the molding die is raised to a temperature suitable for press molding.
At this time, for example, the first heating chamber P <b> 2 maintains a high temperature equal to or higher than the pressing temperature of the molding material 50 and rapidly heats the molding die and the molding material 50. And the shaping | molding die in which the shaping | molding raw material 50 was accommodated is stopped for a predetermined time in the 1st heating chamber P2, and is transferred to the 2nd heating chamber P3 according to rotation of a turntable. Due to the heating in the second heating chamber P3, the mold and the molding material 50 are further heated and soaked to approach the press temperature. Next, the molding die and the molding material 50 are soaked in the third heating chamber P4 so that the viscosity of the molding material 50 is 10 ⁶ to 10 ⁹ poises suitable for press molding. Preferably, the temperature of the molding material 50 is The temperature is set to a viscosity of 10 ⁶ to 10 ⁸ poise.
In addition, there is no restriction | limiting in particular in the heating means with which the heating chambers P2-P4 are equipped. For example, a heater by resistance heating, a high frequency induction coil, or the like can be used.

Steps (10) to (11): Pressing Step The mold that has reached an appropriate temperature is transferred to the press chamber P5 (see FIG. 10 (10)). In the press chamber P5, a press load is applied to the mold by a press head 90 from above the mold at a predetermined pressure (for example, 30 to 200 Kg / cm ² ) and for a predetermined time (for example, several tens of seconds) (see FIG. 10 (11)).
When the lower surface of the press head 90 comes into contact with the upper surface of the body mold 30, the thickness of the molded body 51 is defined, and then the press head 90 is lifted to cancel the application of the press load, thereby completing the pressing process. To do.

Step (12): Cooling Step After completion of the pressing step, the molding die is sequentially transferred to the slow cooling chambers P6 and P7 and the quenching chamber P8 and subjected to a cooling process (see FIG. 10 (12)).
In the quenching chamber P8, quenching with a cooling gas can be performed, and the molded body 51 is cooled until the temperature becomes a glass transition point or lower. At this time, in the molding die, the gap G as described above is secured with a predetermined dimension between the lower surface of the flange portion 12 of the upper die 10 and the upper end of the small-diameter inner peripheral portion 32 of the body die 30. Thus, it becomes possible for the upper mold 10 to follow the shrinkage of the glass by its own weight, and good shape accuracy can be obtained.
In addition, when the upper mold | type 10 descend | falls following the shrinkage | contraction of glass, the space | interval of the clearance gap G between the flange part 12 of the upper mold | type 10 and the upper end surface of the small diameter inner peripheral part 32 of the trunk | drum 30 will become narrow.

Steps (13) to (14): Disassembling step of the forming die When the forming die returns to the take-out / insertion chamber P1, the forming die is taken out of the forming apparatus, disassembled the forming die, and taken out of the formed body 51. Further, a new molding material 50 is supplied.
In the step of disassembling the mold, the mold containing the molded body 51 is transferred to the mounting table 70 by the robot (see FIG. 11 (13)) and positioned by chucking the periphery. Then, atmospheric gas is sucked from the opening 71 of the mounting table 70, the lower mold 20 is integrally held on the mounting table 70, the mounting table 70 is lowered vertically, and the lower mold 20 is moved from the trunk mold 30. And the upper mold 10 and the lower mold 20 are separated (see FIG. 11 (14)). When the lower mold 20 is extracted from the body mold 30, the lower mold 20 is integrally held on the mounting table 70, and the position when the lower mold 20 is extracted from the body mold 30 is maintained. It is possible to avoid the horizontal relative position of the trunk mold 30 from shifting.
At this time, the position of the barrel die 30 in which the upper die 10 is incorporated is fixed by the holding means 80, as in the molding material supply step and the molding die assembly step described above.
In the take-out / insertion chamber P1 that is not in an inert gas atmosphere, it is preferable to control the temperature of the mold so that the temperature of the mold becomes 250 ° C. or less in consideration of prevention of oxidation of the mold.

Steps (15) to (17): Optical Element Removal Step After the lower die 20 is extracted from the body die 30, the transfer arm 60 is inserted between the upper and lower dies 10 and 20 (see FIG. 11 (15)). Then, the molded body 51 is sucked and sucked by the suction pad 61 at the tip (see FIG. 11 (16)), and the molded body 51 is taken out from the molding surface 21 of the lower mold 20 (see FIG. 12 (17)).

  After these steps (1) to (17) are completed, the process can be continuously performed by returning to step (1) and repeating the above cycle.

  In the optical element manufacturing method according to the present embodiment as described above, the molding material 50 supplied onto the molding surface 21 of the lower mold 20 is held by the holding member 40 disposed on the molding surface 21 of the lower mold 20. However, by bringing the body mold 30 and the lower mold 20 close to each other, the holding member 40 is inserted between the body mold 30 and the lower mold 20 after at least a part of the molding material 50 is inserted into the body mold 30. Since the molding material 50 is press-molded between the lower mold 20 and the upper mold 10 and then, an additional member for holding and supporting the molding material 50 is not provided inside the molding die. The molding material 50 supplied on the molding surface 21 of the lower mold 20 is prevented from slipping and being displaced, and the molding material 50 is accommodated in a state of being arranged at an appropriate position on the molding surface 21 of the lower mold 20. The mold can be assembled.

  And since it is not necessary to provide an additional member in the inside of a shaping | molding die, the shaping | molding die assembled in this embodiment can be made into the structure where the upper-and-lower molds 10 and 20 and the trunk | drum 30 contact directly. For this reason, the horizontal shift (shift) and tilting (tilt) between the upper and lower molds 10.20 can be limited by the clearance of the portion where the upper and lower molds 10, 20 and the body mold 30 are in contact with each other, and the manufactured optical element It is possible to precisely and easily control the eccentricity accuracy.

  In addition, the mold is transferred to a plurality of processing chambers including a heating chamber, a press chamber, and a cooling chamber, and the processing including heating, pressing, and cooling is performed in each processing chamber, so that the mold is accommodated inside the molding die. Since the molded material 50 is press-molded, it is possible to efficiently raise and lower the temperature of the mold while simultaneously using a large number of molds, and shorten the actual time (cycle time) required for individual molding. it can. And when assembling the molding die in this embodiment, it is possible to prevent the molding material supplied on the lower molding surface from slipping or misalignment without providing a large movable member in the molding die. A manufacturing method can be used suitably.

  While the present invention has been described with reference to the preferred embodiment, it is needless to say that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. .

  The present invention presses an optical element such as a lens without applying post-processing such as grinding or polishing to a molding surface by applying a pressing load to a mold that contains and assembles a molding material such as glass. In molding, the present invention can be applied to an assembling apparatus for assembling a mold while supplying a molding material, and a method for manufacturing an optical element using a molding die assembled by the assembling apparatus.

It is a schematic sectional drawing which shows an example of the mold press shaping | molding die suitably used for this invention. It is explanatory drawing which shows 1 process in the example which assembles the shaping | molding die shown in FIG. 1 with one Embodiment of the assembly apparatus of the shaping | molding die concerning this invention. It is a schematic plan view of a holding means (holding member). It is explanatory drawing which shows 1 process in the example which assembles the shaping | molding die shown in FIG. 1 by other embodiment of the assembly apparatus of the shaping | molding die which concerns on this invention. It is explanatory drawing which shows 1 process in the other example which assembles the shaping | molding die shown in FIG. 1 by other embodiment of the assembly apparatus of the shaping | molding die which concerns on this invention. It is a reference figure which shows the example which clamps a shaping | molding raw material with an upper-lower mold. It is a schematic plan view which shows an example of the mold press molding apparatus suitable for enforcing the manufacturing method of the optical element which concerns on this invention. It is explanatory drawing which shows process (1)-(4) in one Embodiment of the manufacturing method of the optical element which concerns on this invention. It is explanatory drawing which shows process (5)-(8) in one Embodiment of the manufacturing method of the optical element which concerns on this invention. It is explanatory drawing which shows process (9)-(12) in one Embodiment of the manufacturing method of the optical element which concerns on this invention. It is explanatory drawing which shows process (13)-(16) in one Embodiment of the manufacturing method of the optical element which concerns on this invention. It is explanatory drawing which shows the process (17) in one Embodiment of the manufacturing method of the optical element which concerns on this invention. It is a block diagram which shows an example of the control means which controls a 1st drive means and a 2nd drive means. It is explanatory drawing which shows the state which has arrange | positioned the shaping | molding raw material on the lower mold | type molding surface which has a convex surface.

Explanation of symbols

10 Upper mold 11 Molding surface 20 Lower mold 21 Molding surface 30 Body mold 40 Holding member (holding means)
50 Molding material 51 Molded body 60 Transfer arm 70 Mounting table 100 Control unit 101 Control unit 102 Detection unit 110 First drive unit 120 Second drive unit P2 First heating chamber P3 Second heating chamber P4 Third heating chamber P5 Press chamber P6 1st annealing chamber P7 2nd annealing chamber P8 Quenching chamber

Claims (8)

The lower mold in which the molding surface having the convex surface is formed, the upper mold in which the molding surface is formed on the surface facing the lower mold molding surface, and the lower mold and the upper mold can be inserted from both ends. An assembly apparatus for assembling a mold having a body mold in a state in which a molding material is accommodated,
First driving means for relatively approaching and separating the body mold and the lower mold;
Supply means for supplying a molding material onto the lower mold molding surface;
Holding means for holding the molding material supplied by the supply means on the lower mold forming surface;
A second driving means for holding the molding material by the holding means and retracting the holding means;
Due to the relative proximity of the barrel mold and the lower mold , at least the largest outer diameter portion of the molding material is inserted into the barrel mold, and the molding material is formed by the lower mold molding surface and the inner peripheral surface of the barrel mold. An apparatus for assembling a mold press mold, comprising: a control unit that operates the second drive unit to retract the holding unit from the lower mold forming surface when held. The apparatus for assembling a mold press mold according to claim 1, wherein a maximum thickness of the holding means is half or less of a thickness of the molding material. The lower mold in which the molding surface having the convex surface is formed, the upper mold in which the molding surface is formed on the surface facing the lower mold molding surface, and the lower mold and the upper mold can be inserted from both ends. A method of manufacturing an optical element by press molding a molding material using a molding die provided with a body mold,
While holding the molding material supplied on the lower mold molding surface by holding means arranged on the lower mold molding surface,
By bringing the body mold and the lower mold relatively close to each other, at least the maximum outer diameter portion of the molding material is inserted into the body mold, and the lower mold forming surface and the inner peripheral surface of the body mold After the molding material is held, the holding means is retracted from the lower mold forming surface,
Next, the method of manufacturing an optical element, wherein the molding material is press-molded between the lower mold and the upper mold. The method of manufacturing an optical element according to claim 3 , wherein the molding material has a cylindrical shape. The method of manufacturing an optical element according to claim 3 , wherein the molding material has a biconvex curved shape. 6. The method of manufacturing an optical element according to claim 5 , wherein the holding unit holds a lower side of the maximum outer diameter portion of the molding material and secures an open space around the maximum outer diameter portion. The method for manufacturing an optical element according to claim 3, wherein a maximum thickness of the holding unit is not more than half of a thickness of the molding material. The molding die assembled in a state in which the molding material is accommodated is transferred to a plurality of processing chambers including a heating chamber, a press chamber, and a cooling chamber, and processing including heating, pressing, and cooling is performed in each processing chamber. The method of manufacturing an optical element according to claim 3 , wherein the molding material is press-molded.

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