JP2011136882A - Molding device for optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding device for an optical element, the device effectively suppressing heat distribution of the molding device and producing an optical element of high accuracy with high production yield by suppressing the heat distribution. <P>SOLUTION: The molding device 1 molds an optical element by sequentially conveying a molding mold 50 having a raw material for molding an optical element between an upper die and a lower die, to the respective stages 3, 4, 5 of heating, press-forming and cooling provided in a chamber 2. The molding device includes: a plurality of pairs of plates 3b, 4b, 5b, each including upper and lower plates for mounting the molding die 50 in the respective stages of heating, press-forming and cooling, and subjecting the mounted molding mold 50 to the processes of heating, press-forming and cooling; a control means for controlling the processes of heating, press-forming and cooling; and heat shielding plates 4e, 5e disposed between one stage and the adjoining stage. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a molding apparatus capable of continuously manufacturing optical elements, and more particularly, to an optical element molding apparatus capable of stably holding the plate temperature of each processing stage in the apparatus at a predetermined temperature.

  In recent years, a method for accommodating an optical element molding material in a mold, heat-softening and press-molding, and molding an optical element with high accuracy has become common. An optical element manufacturing apparatus that continuously molds a plurality of optical elements while being conveyed is proposed (for example, see Patent Documents 1 to 3).

  In these optical element manufacturing apparatuses, at the time of heat softening of the optical element molding material, press molding, the mold is set to a predetermined temperature, and the heating state is maintained at a high temperature condition sufficient to process the optical element molding material. After the molding, the molding material is cooled and solidified, and at this cooling, the temperature is set to 200 ° C. or lower so that the molding die is not oxidized. Therefore, in each processing stage in the molding apparatus, each stage is maintained at a different predetermined temperature so that the predetermined processing can be stably performed.

JP-A-8-259240 JP 2008-69019 A JP 2009-96676 A

  In this way, in the molding apparatus that sequentially performs processing while moving the molding die, the optical element molding material and the heating stage that gradually raises the temperature of the molding die are arranged on the inlet side of the molding die, The final stage of the heating stage reaches the maximum temperature, press molding is performed while maintaining this temperature, the optical element shape is given to the optical element molding material, and then the cooling stage is gradually lowered in temperature. It is common.

  When performing such processing, the temperature gradient of the entire apparatus gradually increases from the mold inlet side, and the press stage for the press molding process is set at the apex to the mold outlet side. It is getting lower gradually.

  Therefore, each stage is adjacent to the adjacent stage, in particular, the stage whose temperature is higher than that stage is affected by the temperature of the adjacent stage and becomes higher than a predetermined temperature. There will be a difference.

  If a temperature difference is generated in the same plate as described above, a temperature distribution is also generated in the mold on the plate. For example, in the cooling stage, if the adjacent stage is a press processing stage, the temperature on the press processing stage side of the cooling stage is high and the temperature on the opposite side is low, so the mold on the cooling plate It is said that the optical element that is cooled due to the temperature distribution inside cannot be uniformly cooled, and the cooling rate varies depending on the location, so that it becomes impossible to obtain a desired shape, thereby reducing the yield. There was a problem. Such a problem becomes particularly apparent when the diameter of an optical element to be manufactured is increased and the distance between adjacent plates is reduced.

  The present invention has been made paying attention to such problems, and in manufacturing an optical element, the plate temperature of each stage is not affected by the plate temperature of an adjacent stage, and the plate temperature is made uniform. An object of the present invention is to provide an optical element manufacturing apparatus that manufactures optical elements with high yield.

  As a result of intensive studies, the present inventors have found that the above-described problems can be solved by the optical element molding apparatus of the present invention that achieves uniform temperature in the plate, and have completed the present invention. .

  That is, the optical element molding apparatus of the present invention sequentially conveys a molding die in which an optical element molding material is placed between an upper die and a lower die to the heating, press molding, and cooling stages provided in the chamber. A molding apparatus for molding an optical element, wherein the molding apparatus is equipped with a molding die at each stage of heating, press molding and cooling, and heating, press molding and cooling are performed respectively on the mounted molding die. A plurality of pairs of upper and lower plates for performing each process, a driving means for performing heating, press molding and cooling processes by moving the pair of plates in each group closer to or away from each other, and controlling the conveyance of each process and mold And a heat shield that prevents thermal interference between the plates without interfering with conveyance of the mold between at least one of the adjacent plates The is characterized in that provided.

  According to the optical element molding apparatus of the present invention, in the production of the optical element, the temperature is uniformed so as not to cause a large temperature difference in the plate at each processing stage. The temperature distribution in the mold is uniform, and the optical element can be manufactured stably and with high yield.

It is a schematic block diagram of the shaping | molding apparatus of the optical element which is one Embodiment of this invention. It is a front view of the heat shielding board used for the shaping | molding apparatus of FIG. It is the figure which showed the other structural example which provided the heat shielding board in the plate. It is the figure which showed the example at the time of providing a heat shielding board in all the side surfaces of a plate. It is a schematic block diagram of the shaping | molding apparatus of the optical element which is other embodiment of this invention.

  Hereinafter, the present invention will be described in detail. FIG. 1 is a schematic configuration diagram of an optical element molding apparatus according to an embodiment of the present invention (only a chamber 2 is shown in cross section).

  The optical element molding apparatus 1 of the present invention heats a chamber 2 serving as a molding chamber for molding an optical element, and an optical element molding material provided inside the chamber 2 to form an optical element. A heating stage 3 that softens the material; a press molding stage 4 that press-molds the heat-softened optical element molding material; and a cooling stage 5 that cools the optical element molding material provided with the optical element shape by press molding. Is.

  Here, the chamber 2, which is a molding chamber, provides a place for performing a molding operation of the optical element therein. The chamber 2 is provided with an inlet for taking in the optical element molding die 50 and an outlet for taking out the molding die 50 after the molding of the optical element is finished. An intake shutter 6 and an extraction shutter 7 are provided. By opening and closing these shutters as necessary, the mold 50 can be taken in and out of the chamber 2 and the atmosphere in the chamber 2 is maintained. In addition, the mold inlets 8 and 9 are provided at the inlet and the outlet, respectively, on which the molding die 50 can be placed outside the chamber 2.

  Inside the chamber 2, a heating stage 3, a press molding stage 4 and a cooling stage 5 for molding an optical element are provided, and molding operations are performed by these stages. Actually, the molding die 50 containing the optical element molding material is taken into the chamber 2 from the intake port, moved in order while performing the predetermined processing in each of the above stages, and molded when the predetermined processing is completed. The mold 50 is taken out from the chamber 2 through the take-out port.

  Inside the chamber 2, the molding die 50 softens the optical element molding material and facilitates deformation, and is heated to a high temperature, so that the atmosphere in the chamber is nitrogen or the like so that the molding die 50 is not oxidized. An inert gas atmosphere can be obtained. This inert gas atmosphere can be achieved by replacing the internal atmosphere with the chamber 2 as a closed structure. However, as a semi-closed structure, an inert gas is always supplied into the chamber 2 and a positive pressure is generated in the chamber. However, an inert gas atmosphere may be maintained by preventing external air from flowing in. The intake shutter 6 and the extraction shutter 7 described above are effective for making the inside of the chamber 2 a semi-sealed state with a simple configuration. The chamber 2 and the shutters 6 and 7 are preferably formed of a material such as stainless steel or alloy steel and are a material from which gases and impurities do not precipitate at high temperatures.

  Next, each stage that performs the molding operation of the present invention will be described. The mold 50 used for describing each stage is generally a set of molds composed of an upper mold that forms the upper optical functional surface of the optical element and a lower mold that forms the lower optical functional surface. It is a type | mold and has a trunk | drum type | mold which aligns an upper type | mold and a lower type | mold further. The body mold is a hollow cylindrical inner cylinder that regulates the optical axis of the upper mold and the lower mold on the same axis during pressing, and a hollow cylindrical shape that is provided on the outer periphery of the inner cylinder and regulates the distance between the upper mold and the lower mold It is preferable that the outer shell of the present invention is constituted.

  The mold 50 is made of a material such as cemented carbide or ceramics, and the upper mold and the lower mold each have a molding surface for transferring the surface shape of the optical element to be molded. The shape of the optical element formed may be a mold that molds any lens shape of biconvex, biconcave, plano-convex, plano-concave, convex meniscus, or concave meniscus. In the case of using an outer shell, a material having durability at high temperatures, corrosion resistance, and high mechanical strength is preferable, and a material having a high thermal expansion coefficient is preferable, specifically, stainless steel such as SUS. It is preferable to do.

  The heating stage 3 of the present invention softens the optical element molding material accommodated in the molding die 50, and is composed of a pair of upper and lower heating plates 3b in which a heater 3a is embedded. The heating plate 3b can heat the upper die and the lower die by bringing the pair of upper and lower heating plates 3b into contact with the upper die and the lower die of the molding die, and further the optical housed in the molding die. The element molding material can also be heated.

  More specifically, in the heating stage 3, the lower heating plate 3b is fixed to the bottom plate of the chamber 2, and the upper heating plate 3b can move up and down. The upper heating plate 3b is connected to a shaft 3d via a heat insulating plate 3c so that the heat of the heating plate 3b itself is not transmitted as it is. The shaft 3d can move the heating plate 3b up and down by a cylinder (not shown). Thus, by making the heating plate 3b movable up and down, it is possible to control the contact / non-contact of the upper heating plate 3b with the upper die of the molding die 50, and at the desired timing, The optical element molding material can be heated.

  Further, the lower heating plate 3b is fixed to the bottom plate via the heat insulating plate 3c on the plate side so that the heat is not transmitted as it is when the lower heating plate 3b is fixed to the chamber 2.

  The press molding stage 4 of the present invention reduces the distance between the upper mold and the lower mold of the mold 50 by narrowing the distance between the upper and lower press plates 4b, and the optical element molding material accommodated in the mold 50 is obtained. The optical element is molded by pressing and deforming in the softened state, and applying the optical forming surface shapes of the upper mold and the lower mold to the optical element molding material, and the heater 4a is embedded in the upper and lower sides. It consists of a pair of press plates 4b. The press using the press plate 4b is performed while maintaining the heating temperature in the previous stage.

  More specifically, in the press molding stage 4, the lower press plate 4b is fixed to the bottom plate of the chamber 2, and the upper press plate 4b can move up and down. The upper press plate 4b is connected to a shaft 4d through a heat insulating plate 4c so that the heat of the press plate 4b itself is not transmitted as it is. The shaft 4d can move the press plate 4b up and down by a cylinder (not shown). Thus, by allowing the press plate 4b to move up and down, the upper press plate 4b can be lowered and press molding using the molding die 50 placed on the lower press plate 4b can be performed. At this time, press molding can be performed at a predetermined pressure, and the optical element shape can be imparted to the optical element molding material with high accuracy.

  In addition, the lower press plate 4b has a heat insulating plate 4c and a press plate 4b laminated and fixed in this order on the bottom plate of the chamber 2, similarly to the heating plate 3b. It is configured not to transfer heat to the chamber 2. Further, a heat shielding plate 4e is provided between the press plate 4b and the adjacent heating plate 3b to shield the mutual heat from being directly transferred. The heat shielding plate 4e is attached to the heat insulating plate 4c.

  The cooling stage 5 of the present invention cools and solidifies the optical element molding material to which the optical element shape is imparted by cooling the molding die 50, and a pair of upper and lower coolings in which the heater 5a is embedded. It consists of a plate 5b. The cooling plate 5b can cool the upper die and the lower die by bringing the pair of upper and lower cooling plates 5b into contact with the upper die and the lower die of the molding die, and further the optical housed in the molding die. The element molding material can also be cooled.

  More specifically, in this cooling stage 5, the lower cooling plate 5b is fixed to the bottom plate of the chamber 2, and the upper cooling plate 5b can move up and down. The upper cooling plate 5b is connected to a shaft 5d through a heat insulating plate 5c so that the heat of the cooling plate 5b itself is not transmitted as it is. The shaft 5d can move the cooling plate 5b up and down by a cylinder (not shown). In this way, by allowing the cooling plate 5b to move up and down, it is possible to control contact / non-contact of the upper cooling plate 5b with the upper mold of the mold 50, and at a desired timing, The optical element molding material can be cooled.

  Similarly to the heating plate 3b, the lower cooling plate 5b has a heat insulating plate 5c and a cooling plate 5b stacked and fixed in this order on the bottom plate of the chamber 2, and the lower cooling plate 5b It is configured not to transfer heat to the chamber 2. Further, a heat shielding plate 5e is provided between the cooling plate 5b and the adjacent press plate 4b so as to shield the mutual heat from being directly transmitted. The heat shielding plate 5e is attached to the heat insulating plate 5c.

  It should be noted that the solidification of the optical element molding material here may be cooled below the glass transition point of the material, more preferably below the strain point, and when sufficiently cooled, the optical element shape of the optical element molding material becomes stable. , Deformation is suppressed. Cooling here means lowering to a temperature at which the optical element molding material is solidified so that the optical element shape can be stably applied, and the temperature is only about 50 to 150 ° C. lower than the press plate. Since the temperature is still high, the heater 5a is embedded in the cooling plate 5b.

  Further, the heating plate 3b, press plate 4b and cooling plate 5b on the upper side of each stage are fixed to the shaft through the heat insulating plate as described above, and this shaft is connected to the cylinder. The cylinder is not limited as long as each plate can be moved up and down. For example, a cylinder such as an electric servo cylinder, a hydraulic cylinder, and an electric hydraulic cylinder can be used.

  The heating plate 3b, the press plate 4b, and the cooling plate 5b described above have contact surfaces with the molding die parallel to the horizontal surface. In particular, the press plate 4b has contact surfaces with the molding die of the press plate 4b. Is tilted, the center axes of the upper mold and the lower mold of the mold 50 do not coincide with each other, and the optical element manufactured at this time may have a defective product because the optical axes thereof do not coincide with each other. Therefore, the management of the parallelism and flatness of the plates in each stage is strictly performed.

  In each of these stages, the plate is the one in which a cartridge heater is inserted and fixed inside a material such as stainless steel, cemented carbide, alloy steel, etc., and the temperature of the plate is raised by heating the cartridge heater to obtain a desired value. The temperature can be maintained.

  Moreover, the heat insulating plates 3c, 4c, 5c of each stage may be a known heat insulating plate such as ceramics, stainless steel, die steel, high-speed steel, etc., which has high hardness and is difficult to be deformed by pressure during press molding. It is preferable that the ceramic is less likely to cause the occurrence of the problem. In the case of using a metal material such as stainless steel, die steel, and high-speed steel, it is preferable to coat the surface with an anti-oxidation film, and specifically, a coating treatment of CrN, TiN, TiAlN, or the like.

  Furthermore, the heat shielding plates 4e and 5e may be any one that does not affect the adjacent plate by heat transfer due to the heating of the plate in each stage. Specifically, the heat from the adjacent plate is not affected. Any material can be used as long as it can suppress heat transfer that indirectly transfers heat through the surrounding gas. Generally, since the space between the plates of each stage is not unnecessarily wide, a plate-like body having a thickness of about 0.5 to 2 mm may be disposed between the plates. In FIG. 1, the heat shielding plate 4 e between the heating plate and the press plate is fixed to the heat insulating plate 4 c, but it may be fixed to the heat insulating plate 3 c or the chamber 2. Moreover, although the heat shielding plate 5e between the press plate and the cooling plate is fixed to the heat insulating plate 5c, it may be fixed to the heat insulating plate 4c or the chamber 2 as well.

  At this time, since the heat shielding plates 4e and 5e are provided to prevent thermal interference between the plates as described above, the heat shielding plates 4e and 5e are provided between the adjacent plates. It is required to provide

  Since the upper heating plate 3a, press plate 4a, and cooling plate 5a are moved up and down by the driving means, when providing a heat shielding plate, for example, to move up and down integrally with these plates, for example, It is preferable to fix to the heat insulating plates 3c, 4c, 5c shown in FIG.

  At this time, it is preferable to use materials such as stainless steel and ceramics as the heat shielding plate. In order to exhibit the heat shielding effect more effectively, a ceramic plate having a low thermal conductivity is preferable, and when the heat shielding effect is partially performed or the heat shielding plate is processed after being installed. Although the shielding effect is slightly inferior, a metal plate that is easy to process is preferable.

  FIG. 2 (a) shows the heat shield plate 4e as viewed from the inlet side. The temperature of these plates is also higher at the center than at both ends when viewed from the inlet side. Since the heat shield plate having the shape of FIG. 2 (a) is not sufficiently uniform in the plate temperature, for example, both ends are cut away so that the central portion can be heat shielded. The heat shield plate having the shape as shown in 2 (b) is preferably configured to equalize the plate temperature. In this case, when there is a large temperature difference in one plate, processing is performed so that the high temperature portion is shielded and the low temperature portion is not shielded so as to equalize the plate temperature.

  FIG. 1 shows an example in which the heat shielding plates 3e, 4e, and 5e are provided on one side of the plate. FIGS. 3 and 4 illustrate the press plate 4b as an example and the heat shielding plate as a plate. The other structural example in the case of providing was shown. FIG. 3A shows a heat shielding effect that is provided on both side surfaces of the plate. FIG. 3 (b) shows a heat shielding plate provided on the upper plate that moves up and down so that it can be shielded to the periphery of the mold when it is lowered, and further has a heat shielding effect. It is an enhanced one.

  Further, as shown in FIG. 4, a heat shield plate extending to the periphery of the mold as shown in FIG. 3B is provided not only on both sides of the plate but on all sides of the plate so as to surround the four sides of the mold. In this case, the heat shielding effect is further enhanced, which is particularly preferable. FIG. 4 shows a front view (FIG. 4 (a)), a bottom view (FIG. 4 (b)), and a left side view (FIG. 4 (c)) when the heat shielding plate is provided on all side surfaces of the plate. It is shown and partially shown as a perspective view.

  Further, when the heat shield plate is extended to the periphery of the mold as shown in FIGS. 3B and 4, the extended heat shield plate comes into contact with the lower plate or the heat shield plate to perform press molding operation. In order not to hinder the above, an extended portion extending downward from the lower surface of the upper plate (the surface for pressing the mold) must be provided so as to be shorter than the height of the mold.

  The heating stage 3, the press molding stage 4, and the cooling stage 5 described above form a place (stage) where predetermined processing is performed, so that processing by each stage can be performed sequentially and smoothly. The mold 50 is controlled by a control unit that moves the mold 50 so as to be mounted on each stage at a predetermined timing by a conveying unit (not shown).

  More specifically, the processing by the heating plate 3b, the press plate 4b, and the cooling plate 5b is to perform a predetermined processing while the molding die 50 is sequentially transported and moved onto each plate in the above order. As the stage 50 is moved to the next stage, the stage that has been processed is vacant, and further, a molding die 50 containing another optical element molding material is transported there to continuously mold a plurality of optical elements. The operation can be performed.

  The transport means for performing this process is not shown in the figure, but, for example, by a robot arm or the like, from the mold placing table 8 to the heating plate 3b, from the heating plate 3b to the press plate 4b, and from the press plate 4b to the cooling plate. 5b can be moved from the cooling plate 5b to the mold mounting table 9.

  The control means also controls the temperature of the pair of upper and lower plates in each stage of the mold movement, heating, press molding, and cooling, the timing of the vertical movement, etc., and a series of molding operations smoothly, It is controlled so that it can be performed continuously. At this time, the opening and closing of the taking-in shutter and the taking-out shutter are also controlled. Further, it is preferable to control the supply amount and timing of nitrogen so that the atmosphere in the chamber 2 is filled with an inert gas.

  In other words, the optical element molding apparatus 1 is an optical element molding apparatus that carries out a predetermined process while raising and lowering the temperature at one or more positions, by conveying a molding die.

  Next, an optical element molding method using the optical element molding apparatus 1 will be described.

  First, the molding die 50 is placed on the molding die mounting table 8 on the inlet side, and the optical element molding material is accommodated in the molding die 50. The intake shutter 6 is opened to open the intake port, and the mold 50 is conveyed onto the heating plate 3b by the conveying means. When conveyed, the lower mold of the mold 50 is heated to the same temperature as the heating plate 3b because it contacts the lower heating plate 3b. At the same time, the upper die is brought into contact with the upper heating plate 3b from above and heated similarly.

  When the upper mold and the lower mold are heated in this manner, the optical element molding material accommodated therein is also heated, and the optical element molding material is easily deformed when heated above the yield point. Generally, the heating temperature is set to a temperature between the yield point (At) and the softening point because the lens surface becomes clouded when the temperature is raised to the softening point. At this time, the rate of temperature rise is preferably about 0.5 to 2.5 ° C./sec.

  The mold 50 and the optical element molding material sufficiently heated by the heating stage 3 in this way are conveyed and placed on the lower press plate 4b by the conveying means.

  The press plate 4b is also heated to the same temperature as the heating plate 3b, so that the optical element molding material is maintained in a softened state. Further, the upper press plate 4b is lowered to reduce the distance between the press plates 4b, thereby reducing the distance between the upper die and the lower die, and applying pressure to the optical element molding material accommodated in the molding die 50. It can be transformed over time.

  In this pressing step, as described above, the optical element molding material is press-molded by applying pressure from above and below the molding die 50, whereby the optical forming surfaces of the upper mold and the lower mold are transferred to the optical element molding material. The optical element shape is given.

In the press in this pressing step, the heating temperature is about the same as the temperature heated in the preceding heating stage, and the pressure during pressing is 2.5 to 37.5 N / mm ² per unit area of the lens molded body. Preferably, for example, 10 to 20 / mm ² is particularly preferable.

  And by performing such a press process, the shaping | molding die 50 by which the press cut was completed is conveyed from the press plate 4b to the cooling plate 5b by a conveyance means. This transport means is the same as the transport means described above.

  Next, the mold 50 is cooled by the cooling plate 5b. This is similar to the above heating step. The lower mold is the lower cooling plate 5b, and the upper mold is the upper cooling plate 5b lowered and brought into contact. Cool by. Thereby, the optical element molding material is cooled and solidified. This cooling is preferably performed to a temperature below the glass transition point (Tg) of the optical element molding material, and more preferably to a temperature below the strain point of the optical element molding material. At this time, the temperature lowering rate is preferably 0.1 to 2.5 ° C./sec, and more preferably 0.5 to 1.0 ° C./sec.

  The heating step and the cooling step described above are preferably performed so as to change the temperature stepwise, and the heating step is performed step by step by providing one or more heating stages. The temperature is raised so as to reach the molding temperature in the heating stage immediately before the press molding stage. Also, in the cooling process, by providing one or more cooling stages, the temperature of the optical element molding material is lowered stepwise so as to reach a temperature of 200 ° C. or lower. Thus, by performing heating and cooling step by step, the rapid temperature change of the optical element molding material is suppressed, and the characteristics of the optical element such as distortion and surface cracking are deteriorated. There can be no.

  FIG. 5 shows an example of an optical element molding apparatus using a plurality of heating stages and cooling stages in order to carry out such a heating process and a cooling process. The optical element molding apparatus 11 shown in FIG. 5 includes a chamber 12, a first heating stage 13, a second heating stage 14, a third heating stage 15, a press molding stage 16, a first cooling stage 17, The apparatus has a second cooling stage 18 and a third cooling stage 19, and in the chamber 12, as with the optical element molding apparatus 1, an inlet for the molding die 50 and an inlet that can be opened and closed. The shutter 20, the take-out port and the take-out shutter 21 that can be opened and closed, and the mold mounting tables 22 and 23 are provided outside the take-in port and the take-out port.

  This optical element molding apparatus 11 is provided with three heating stages and three cooling stages to perform heating and cooling step by step, and each plate has a heat shielding plate on its adjacent plate side. The configuration is the same as that of the optical element molding apparatus 1 of FIG. The heat shielding plates 13e, 14e, 15e, 16e, 17e, 18e, and 19e are arranged between adjacent plates in each of the heating stage, press molding stage, and cooling stage so as to suppress heat conduction between the plates. Is provided.

  In the first heating stage 13, the optical element molding material is preheated to a temperature lower than the glass transition point and lower by about 200 to 400 ° C., and in the second heating stage 14, the temperature is close to the glass transition point. In the 3rd heating stage 15, it heats to the temperature of a yield point + 10-30 degreeC. Further, in the press molding stage 16, a molding operation is performed using a molding die while maintaining the molding temperature, and an optical element shape is imparted. In the first cooling stage 17, the glass material is cooled to about the glass transition point + 20 ° C. The cooling stage 18 is further cooled to below the strain point, and the third cooling stage 19 is cooled to a temperature of 200 ° C. or less at which the mold is not oxidized.

  Here, in the third cooling stage, the plate to be used is a water cooling plate provided with piping so that the cooling water circulates instead of the heater in the other stage so that the cooling can be efficiently performed. It has become.

  In this optical element molding apparatus 11, the influence between adjacent plates is large because the cooling stage for cooling the optical element is affected by the fact that the temperature of the adjacent plate is high, and cooling of a part of the optical element is sufficiently performed. It's time you can't. If such cooling becomes non-uniform, distortion occurs in the optical element due to the difference in cooling rate, or the mold release cannot be performed well, which adversely affects the characteristics of the optical element obtained as it is. Is. In particular, since the influence between the press plate 16b and the first cooling plate 17b is large, it is preferable to provide a heat shielding plate at least between the press plate 16b and the first cooling plate 17b. Furthermore, it is preferable to provide a heat shielding plate so as not to be affected by the adjacent cooling stages between the subsequent cooling stages.

  In addition, between the heating stages and between the heating stage and the press molding stage, the effect of causing problems is smaller than that of the cooling stage, but the heat shield plate is similarly used so that the predetermined processing can be performed at a uniform temperature. It is preferable to provide it. FIG. 5 shows an example in which a heat shielding plate is provided between all the plates.

  The optical element obtained by cooling is then subjected to post-processing such as cutting the excess part into an optical element shape or applying an annealing process to remove distortion or the like in order to obtain an optical element shape. To be the final product.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(Example 1)
The optical element was molded as follows using the optical element molding apparatus 11 of FIG.
The optical element molding apparatus 11 used here is a heat insulating plate using, as a heating plate, a press plate, and a cooling plate, a tungsten carbide 100 × 74 × 18 mm rectangular parallelepiped plate having four 750 W cartridge heaters inside. As an example, a laminate of a 100 × 74 × 9 mm plate made of SUS304 and a 100 × 74 × 9 mm plate made of zirconia was used. The gap between each plate is arranged to be 6 mm, and the lower end of a 144 × 52 × 2 mm plate made of SUS304 is bent at 90 ° C. as a heat shielding plate between the plates, It was used by being fixed to a heat insulating plate laminated with the plate.

  The cylinder that moves the upper plate up and down uses an air cylinder, and a shaft having a shaft diameter of 40 mm is connected and fixed to the upper plate. The chamber was a 440 × 592 × 240 mm box made of SS400, and the lower plate of this chamber was 440 × 592 × 20 mm.

  The mold 50 is composed of an upper mold, a lower mold, and a trunk mold having an inner cylinder and an outer cylinder. The upper mold, the lower mold, and the inner cylinder are made of cemented carbide made of tungsten carbide, and the outer cylinder is made of SUS. By press molding, a biconvex molded product having a diameter of 40 mm, a center thickness of 7.5 mm, a peripheral thickness of 3 mm, and an aspherical recent curvature radius of 100 mm and 85 mm, respectively, is obtained. An optical element with a diameter of 35 mm was obtained by centering.

  A biconvex spherical surface having a diameter of 36 mm, a center thickness of 8.83 mm, a peripheral thickness of 4.3 mm, and a radius of curvature of 90 mm and 60 mm, respectively, formed on the molding surface 12a of the lower mold 12 of the mold by grinding and polishing made of borosilicate glass. A lens optical element molding material was placed. This optical element molding material has a strain point of 495 ° C., a glass transition point (Tg) of 532 ° C., and a yield point (At) of 573 ° C.

  The mold 50 containing the optical element molding material is conveyed and placed on the first heating plate 13b by the conveying means, and at the same time, the upper first heating plate 13b is lowered and brought into contact with the upper mold. The optical element molding material is heated for 300 seconds, and then is transported and placed on the second heating plate 14b, and at the same time, the upper second heating plate 14b is lowered and brought into contact with the upper mold. The element molding material is heated for 300 seconds, and further conveyed and placed on the third heating plate, and at the same time, the upper third heating plate 15b is lowered and brought into contact with the upper mold to form the molding die 50 and the optical element molding. The material was heated for 300 seconds to make the optical element molding material softened. The first heating plate 13b was set to 280 ° C., the second heating plate 14b was set to 500 ° C., and the third heating plate 15b was set to 600 ° C.

Next, the mold 50 was transported and placed on the press plate 16b, and the upper press plate 16b was lowered. The press pressure during the molding was 5 N / mm ² and the press time was 250 seconds. At this time, the temperature of the press plate 16b was 600 ° C.

  After pressing, the mold is conveyed and placed on the first cooling plate 17b, and at the same time, the upper cooling plate 17b is lowered to contact the upper mold and cooled for 300 seconds, and then the mold is moved to the second cooling plate. When the upper second cooling plate 18b is lowered and brought into contact with the upper mold, cooled for 300 seconds, and further, the forming mold is conveyed and placed on the third cooling plate 19b. At the same time, the upper third cooling plate 19b was lowered to contact the upper mold and cooled for 300 seconds. At this time, the first cooling plate 17b was set to 550 ° C., the second cooling plate 18b was set to 450 ° C., and the third cooling plate 19b was set to 20 ° C. (cooling water temperature).

  The optical element molding material was cooled to room temperature, and when it was sufficiently cooled, it was removed from the mold and an optical element was obtained.

  In the optical element molding apparatus of the present invention, when the temperature distribution of the cooling plate 17b was measured and no heat shielding plate was installed between the plates, the temperature difference between the press plate 16b side and the second cooling plate 18b side was 10. Occurs about ℃. When a heat shielding plate was installed between the plates, the temperature difference could be reduced to about 2 ° C. Furthermore, when the temperature distribution of the metal mold | die arrange | positioned on the cooling plate 17b was measured, the temperature distribution of the plate showed the same tendency.

When the lens was actually molded with or without the heat shielding plate, when the heat shielding plate was not installed, shape defects such as stigma occurred, and it was difficult to stably obtain good products.
When a heat shielding plate was installed, shape defects such as stigma were suppressed, and molding with high quality and high yield was possible.

  As described above, the optical element molding apparatus of the present invention can suppress the plate temperature distribution in the production of the optical element, and can further suppress the mold temperature distribution. As a result, it was found that the shape of the optical element can be stabilized and the yield can be improved.

  The optical element molding apparatus of the present invention can be used for continuously producing optical elements by press molding while sequentially moving the mold.

DESCRIPTION OF SYMBOLS 1 ... Optical element shaping | molding apparatus, 2 ... Chamber, 3 ... Heating stage, 4 ... Press molding stage, 5 ... Cooling stage, 6 ... Intake shutter, 7 ... Extraction shutter, 8, 9 ... Mold mounting base, 50 ... Molding Mold, 3a, 4a, 5a ... heater, 3b ... heating plate, 4b ... press plate, 5b ... cooling plate, 3c, 4c, 5c ... heat insulation plate, 3d, 4d, 5d ... shaft, 4e, 5e ... heat shielding plate

Claims (7)

An optical element molding apparatus for molding an optical element by sequentially transporting a molding mold in which an optical element molding material is placed between an upper mold and a lower mold to heating, press molding, and cooling stages provided in a chamber. There,
The molding apparatus includes a plurality of pairs of upper and lower pairs that mount the molding die at the heating, press molding, and cooling stages, and perform heating, press molding, and cooling processes on the mounted molding die, respectively. Drive means for causing the heating, press molding, and cooling processes to be performed by approaching or separating the pair of plates in each set, and control means for controlling conveyance of each process and the mold. As well as
An apparatus for molding an optical element, characterized in that a heat shielding plate is provided between at least one of adjacent plates to prevent thermal interference between the plates without interfering with conveyance of the mold.   The optical element molding apparatus according to claim 1, wherein the heat shielding plate is provided between a press molding stage and a cooling stage.   The heating stage and / or the cooling stage is configured to perform heating and / or cooling stepwise in a plurality of stages, and the heat shielding plate is provided between these stages. The apparatus for molding an optical element according to claim 1 or 2.   4. The optical element molding apparatus according to claim 1, wherein the heat shielding plate is provided on at least one side of plates adjacent to each other.   5. The apparatus for molding an optical element according to claim 4, wherein the heat shielding plate is provided at the same height as a plate to which the heat shielding plate is fixed.   6. The heat shielding plate is processed so as to shield a high temperature portion of the plate and not to shield a low temperature portion so that the temperature of the plate is uniform. The molding apparatus for an optical element according to any one of the above.   The optical element molding apparatus according to claim 1, wherein the heat shielding plate is made of metal or ceramics.

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