JP2015174351A - molding die for optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding die for an optical element that can eliminate a temperature difference between cavities caused by the temperature of a temperature control pipe in the molding die, and can form an optical element having high accuracy.SOLUTION: A molding die for an optical element comprises a first mold 41 and a second mold 42. At least one of the first and second molds 41, 42 include: a plurality of optical transfer surfaces 61e, 71e, forming a plurality of optical elements, on a surface facing the first mold 41 or the second mold 42; and temperature control pipes 66a, 76a, allowing passing of a heat medium, in the inside of the first and second molds 41, 42. In the temperature control pipes 66a, 76a, a cross sectional area of a first pipe part P1 corresponding to a part in the plurality of optical transfer surfaces 61e, 71e, where temperature tends to be relatively low at the time of molding is smaller than that of a second pipe part P2 corresponding to a part where temperature tends to be relatively high.

Description

  The present invention relates to a molding die for an optical element for injection molding an optical element or the like.

  2. Description of the Related Art Manufacturing of molded articles such as optical elements is performed using an injection molding apparatus. In general, in an injection molding apparatus, molten resin is injected into a cavity constituted by a fixed mold and a movable mold, and is cooled and solidified in the mold to mold an optical element. Here, if there is a temperature distribution in the mold, the optical performance of the molded product may vary.

  As a molding apparatus for adjusting the temperature in a mold, there is an apparatus having an electrothermal conversion element in a mold portion that forms a cavity as a mold space (see Patent Document 1).

  As another molding device for adjusting the temperature in the mold, the inner diameter of the temperature control pipe arranged around the sprue, runner, gate, and cavity (cooling part) formed in the mold is changed to the sprue, runner. There are devices that differ depending on the cross-sectional areas of the gate and the cavity (see Patent Document 2).

  In addition, although it is a technology to form a cup body from a metal plate, cooling water adjustment is performed in a method for controlling the temperature of a mold (die, punch presser and punch) of a seamless can manufacturing apparatus by circulating cold water or hot water. There is a method of detecting the temperature of the cooling water in the conduit before returning to the tank and adjusting the amount of cold water or hot water supplied based on the detected value (see Patent Document 3).

  However, in the apparatus of Patent Document 1, since it is necessary to provide an electrothermal conversion element for each cavity, the cost increases. Moreover, in the apparatus of patent document 2, the internal diameter of temperature control piping is changed corresponding to the cross-sectional area of a cooling site | part, and it does not mention temperature adjustment between the cavities which have the same cross-sectional area. Therefore, when a temperature difference occurs between cavities, it is difficult to eliminate the temperature difference. In the method of Patent Document 3, it is difficult to eliminate the temperature difference between the cavities only by adjusting the amount of cold water or hot water to be circulated and changing the temperature of the heat medium.

International Publication No. 08/26456 Japanese Patent Laid-Open No. 11-104765 JP 2009-61677 A

  The present invention provides a molding die for an optical element that can eliminate a temperature difference between cavities caused by a temperature distribution of a temperature adjusting pipe in the molding die and can mold a highly accurate optical element. The purpose is to provide.

  In order to solve the above problems, a molding die for optical elements according to the present invention includes a first die and a second die, and at least one of the first and second die is a first die. A plurality of optical transfer surfaces for molding a plurality of optical elements on a surface facing the second mold, and a temperature adjustment pipe through which the heat medium passes through the first and second molds. The piping corresponds to a portion where the cross-sectional area of the first piping portion corresponding to the portion where the temperature tends to be relatively low during molding among the plurality of optical transfer surfaces, the temperature tends to be relatively high. It is smaller than the cross-sectional area of the second piping portion.

  In the molding die for optical elements, the temperature distribution is compensated according to the temperature distribution of each optical transfer surface at the time of molding when the sectional area of the temperature adjusting pipe is substantially constant. By being different, the temperature difference between the optical transfer surfaces can be reduced. For example, when the cross-sectional area of the temperature adjustment pipe is substantially constant, a portion of the plurality of optical transfer surfaces whose temperature tends to be relatively low during molding occurs. By setting the portion where the temperature tends to be relatively low as the first piping portion and reducing the cross-sectional area of the first piping portion, the temperature of the first piping portion becomes higher than the case where it is not reduced. . Thereby, the temperature difference between the cavities formed between the optical transfer surfaces of the first and second molds can be eliminated. Therefore, a highly accurate optical element can be molded even in the production of a multi-piece optical element. Moreover, since the temperature of the molding die can be adjusted by adjusting the cross-sectional area of the temperature adjusting pipe, it is not necessary to provide a separate heater or additional pipe.

  In another aspect of the present invention, the first piping portion has a blocking member that restricts the flow of the heat medium. In this case, the cross-sectional area of the first piping portion can be adjusted to a desired area according to the size of the blocking member, and the temperature of the molding die can be easily adjusted.

  In still another aspect of the present invention, the blocking member protrudes in a dam shape or an annular shape in the cross section of the first piping portion.

  In still another aspect of the present invention, the blocking member is detachable.

  In still another aspect of the present invention, the flow of the heat medium in the second pipe part is a laminar flow, and the flow of the heat medium in the first pipe part is a turbulent flow. When the turbulent flow is generated in the first pipe portion, the temperature difference from the laminar flow having a relatively high temperature is eliminated.

  In still another aspect of the present invention, the temperature adjusting pipe is a split type flow path that connects adjacent pipes via a connection port. In this case, the temperature adjusting piping can be made simple.

  In still another aspect of the present invention, the number of heat medium inlets provided in the temperature adjusting pipe is smaller than the number of optical transfer surfaces. Thus, the temperature difference between the cavities can be eliminated even when the number of inlets is reduced in order to simplify the structure of the temperature adjusting pipe.

  In yet another aspect of the present invention, the temperature adjustment pipe is disposed along the periphery of a line connecting a plurality of optical transfer surfaces. In this case, the optical transfer surface can be efficiently and uniformly heated.

  In still another aspect of the present invention, the temperature adjustment pipe has an annular shape when viewed from a surface where the first mold and the second mold face each other.

It is a conceptual diagram explaining the shaping | molding apparatus incorporating the shaping die for optical elements which concerns on 1st Embodiment. (A) And (B) is side sectional drawing explaining a shaping die. (A) is a figure explaining the piping for temperature control and its periphery seen from the end surface of a receiving plate among 1st metal mold | dies, (B) is seen from the end surface of a receiving plate among 2nd metal mold | dies. It is a figure explaining the piping for temperature adjustment and its periphery, (C) and (D) is a figure explaining the cross-sectional structure of the piping for temperature adjustment, (E) and (F) are piping for temperature adjustment. It is a figure explaining the flow of the inside heat medium. (A) is a conceptual diagram explaining the temperature adjustment pipe viewed from an oblique direction, (B) is a partially enlarged perspective sectional view in a direction perpendicular to the flow of the heat medium of the temperature adjustment pipe, C) is a partially enlarged cross-sectional view in a direction parallel to the flow of the heat medium in the temperature adjusting pipe. (A)-(F) is a figure explaining the shaping die of a 3rd embodiment, and (A) shows piping for temperature regulation and its circumference seen from the end face of a receiving plate among the 1st metallic molds. It is a figure explaining, (B) is a figure explaining the piping for temperature adjustment seen from the end surface of a receiving plate among the 2nd metal molds, and its circumference, (C) and (D) are for temperature adjustment It is a figure explaining the cross-sectional structure of piping, (E) And (F) is a figure explaining the flow of the heat medium in piping for temperature control. (A) And (B) is a figure explaining the temperature measurement position in an Example and a comparative example. (A) And (B) is a figure explaining the relationship between the temperature measurement position and temperature difference in an Example and a comparative example. (A) And (B) is a figure explaining the relationship between the temperature measurement position and temperature difference in another comparative example.

[First Embodiment]
Hereinafter, a molding die for an optical element according to a first embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a molding apparatus 100 includes an injection molding machine 10 that is a main body part that performs injection molding to produce a molded product MP, and a take-out device 20 that is an accessory part that takes out the molded product MP from the injection molding machine 10. And a control device 30 that comprehensively controls the operation of each part constituting the molding apparatus 100.

  The injection molding machine 10 is mainly a horizontal molding machine, and includes a molding die 40, a stationary platen 11, a movable platen 12, a mold clamping plate 13, an opening / closing drive device 15, and an injection device 16. The injection molding machine 10 is also provided with a mold temperature controller 47, a pressure reducing device (not shown) and the like. The injection molding machine 10 clamps both molds 41 and 42 by sandwiching a first mold 41 and a second mold 42 constituting the molding mold 40 between the fixed platen 11 and the movable platen 12. This enables molding.

  The fixed platen 11 is fixed to the approximate center of the support frame 14 so as to face the movable platen 12, and supports the take-out device 20 on the upper part thereof. The inner side 11a of the fixed platen 11 faces the inner side 12a of the movable platen 12, and supports the first mold 41 in a detachable manner. The fixed platen 11 is formed with an opening 11b through which a later-described nozzle 16d is passed. Note that the fixed platen 11 is fixed to the mold clamping plate 13 via a tie bar so that it can withstand the pressure of mold clamping during molding.

  The movable platen 12 is supported by the linear guide 15a so as to be movable back and forth with respect to the fixed platen 11. The inner side 12a of the movable platen 12 faces the inner side 11a of the fixed platen 11, and supports the second mold 42 in a detachable manner. Note that an ejector driving unit 45 is incorporated in the movable platen 12. The ejector driving unit 45 is for extruding the molded product MP in the second mold 42 toward the first mold 41 in order to release the molded product MP.

  The mold clamping machine 13 is fixed to the end of the support frame 14. The mold clamping machine 13 supports the movable board 12 from the back via the power transmission part 15d of the opening / closing drive device 15 at the time of mold clamping.

  The opening / closing drive device 15 includes a linear guide 15a, a power transmission unit 15d, and an actuator 15e. The linear guide 15 a supports the movable platen 12 and enables the movable platen 12 to smoothly reciprocate with respect to the advancing and retreating direction with respect to the fixed platen 11. The power transmission unit 15 d expands and contracts by receiving a driving force from an actuator 15 e that operates under the control of the control device 30. As a result, the movable platen 12 moves forward and backward freely with respect to the mold clamping plate 13, close to or away from the mold clamping plate 13. As a result, the fixed platen 11 and the movable platen 12 can be brought close to or separated from each other, and the first mold 41 and the second mold 42 can be clamped or opened.

  The injection device 16 includes a cylinder 16a, a raw material storage unit 16b, a screw drive unit 16c, and the like. The injection device 16 operates at an appropriate timing under the control of the control device 30, and can inject a molten resin (injected melt) in a state of temperature control from the resin injection nozzle 16d. In the state where the first mold 41 and the second mold 42 are clamped, the injection device 16 has a nozzle 16d in a sprue port portion 65 (see FIG. 2B), which will be described later, through the opening 11b of the stationary platen 11. , The molten resin in the cylinder 16a can be injected and supplied at a desired timing and pressure with respect to a flow path space FC (see FIG. 2B) described later.

  A mold temperature controller 47 provided in association with the injection molding machine 10 circulates a temperature-controlled heat medium in a flow path provided in both molds 41 and 42. Thereby, the temperature of both metal mold | dies 41 and 42 can be kept at an appropriate temperature at the time of shaping | molding.

  The take-out device 20 includes a hand 21 that can hold the molded product MP and a three-dimensional drive device 22 that moves the hand 21 three-dimensionally. The take-out device 20 operates at an appropriate timing under the control of the control device 30, and remains in the second die 42 after the first die 41 and the second die 42 are separated and opened. It has the role of gripping the molded product MP and carrying it out.

  The control device 30 includes an opening / closing control unit 31, an injection device control unit 32, an ejector control unit 33, and a take-out device control unit 34. The opening / closing control unit 31 enables the molds 41 and 42 to be closed, clamped, opened, and the like by operating the actuator 15e. The injection device control unit 32 causes the molten resin to be injected at a desired pressure into the cavity CV formed between the molds 41 and 42 by operating the screw driving unit 16c and the like. The ejector control unit 33 operates the ejector driving unit 45 to push out the molded product MP remaining in the second mold 42 when the mold is opened from the second mold 42 to release the mold. The take-out device control unit 34 operates the take-out device 20 to grip the molded product MP remaining in the second mold 42 after mold opening and mold release and carry it out of the injection molding machine 10.

  Hereinafter, the molding die 40 will be described in detail. As shown in FIG. 2A and the like, the second mold 42 on the movable side of the molding die 40 can reciprocate in the AB direction. The second mold 42 is moved toward the first mold 41 on the fixed side, and both molds 41 and 42 are mold-matched with mold-matching surfaces, ie, parting surfaces PS1 and PS2, and clamped. As shown in FIG. 2 (B), a cavity CV for molding the optical element and a channel space FC which is a channel for supplying molten resin to the cavity CV are formed.

  The first mold 41 is a fixed mold, and includes a mold part 60 disposed on the inner side, that is, the parting surface PS1 side, and a mounting plate 64 disposed on the outer side, that is, the fixed platen 11 side in FIG. Among these, the mold part 60 has a divided structure divided into a plurality of parts. The mold part 60 includes a template 60a and a receiving plate 60b. In the mold part 60, the template 60a and the receiving plate 60b are fixed to each other with bolts or the like.

  The mold plate 60a of the mold part 60 includes a core part 62 as a mold body and a peripheral part 63 surrounding the mold body as divided parts. The peripheral portion 63 of the template 60a is a metal plate-like member, and a plurality of core holding ports 61a into which the plurality of core portions 62 are inserted, and a sprue connection for supplying molten resin from the outside to the inside. And a mouth 61b. A core portion 62 is inserted into each core holding port 61a, and the tip surface of the core portion 62 serves as an optical transfer surface 61e for forming an optical function portion of the optical element.

  The receiving plate 60b is a metal plate-like member, is disposed between the template 60a and the mounting plate 64, and supports the template 60a from behind. Similar to the template 60a, the receiving plate 60b includes a sprue connection port 61c for supplying molten resin from the outside to the inside.

  In order to keep the temperature of the molding die 40 at an appropriate temperature during molding, a temperature adjusting pipe 66a for circulating a heat medium, a temperature monitoring thermometer (not shown), and the like are formed inside the mold portion 60. ing. The temperature adjustment pipe 66 a and the like are connected to the mold temperature controller 47. For example, oil or water is used as the heat medium.

  The temperature adjusting pipe 66a is formed by a combination of a pair of grooves provided so as to face each other between the template 60a and the receiving plate 60b. As shown in FIG. 3A, the temperature adjustment pipe 66a is disposed so as to surround the optical transfer surface 61e along the periphery of the closed line ST connecting the plurality of optical transfer surfaces 61e. Therefore, the temperature adjustment pipe 66a heats the optical transfer surface 61e efficiently and uniformly. The temperature adjusting pipe 66a has an annular shape when viewed from the surface (parting surface PS1 shown in FIG. 2A) where the first mold 41 and the second mold 42 face each other. The temperature adjusting pipe 66a of the present embodiment is a split double type flow path. Specifically, as shown in FIGS. 4 (A) to 4 (C), it extends between the mold plate 60a and the receiving plate 60b and extends over the temperature adjusting pipe 66a and the periphery thereof, for temperature adjustment. A partition BK that divides the pipe 66a into two along the flow path is provided. The temperature adjusting pipe 66a has a double structure in which the adjacent front side pipe HP1 and back side pipe HP2 are connected via connection ports 66e and 66g (see FIG. 3A, etc.). That is, the temperature adjusting pipe 66a is configured by the front side pipe HP1 corresponding to the first flow path FP1 on the template 60a side and the back side pipe HP2 corresponding to the second flow path FP2 on the receiving plate 60b side. . As shown in FIGS. 3 (A) and 4 (A), the temperature adjustment pipe 66a is above and below the mold 60a side of the first mold 41 and adjacent to the connection ports 66e and 66g. It has inlets 66c and 66d through which the heat medium flows into the flow path. Further, the temperature adjusting pipe 66a has outlets 66f and 66h for allowing the heat medium to flow out of the flow path above and below the receiving plate 60b side of the first mold 41 and adjacent to the connection ports 66e and 66g. Each has. A partition wall WA is provided between the inlets 66c and 66d and the outlets 66f and 66h and the connection ports 66e and 66g adjacent to the inlets 66c and 66d and the second flow paths FP1 and FP2. Thus, by dividing the first and second flow paths FP1 and FP2 into two by the partition wall WA, two circulation paths are formed in the temperature adjustment pipe 66a. Since the adjacent front side pipe HP1 and back side pipe HP2 are simply connected by the connection ports 66e and 66g and partitioned by the partition wall WA, the temperature adjustment pipe 66a has a simple structure. The number of inlets 66c and 66d is smaller than the number of optical transfer surfaces 61e. In other words, the heat medium inlets 66c and 66d may not be provided for each optical transfer surface 61e. Thus, the temperature difference between the cavities CV can be eliminated even when the number of the inlets 66c and 66d is reduced in order to simplify the structure of the temperature adjusting pipe 66a.

  The temperature adjustment pipe 66a has a uniform flow path cross section as a whole, but the first corresponding to a portion of the plurality of optical transfer surfaces 61e that tends to have a relatively low temperature during molding. The cross-sectional area of the pipe part P1 is locally smaller than the cross-sectional area of the second pipe part P2 corresponding to the part where the temperature tends to be relatively high. That is, in the temperature adjustment pipe 66a arranged along the plurality of optical transfer surfaces 61e, the cross-sectional area is uniform in the second pipe portion P2, but for example, the first pipe located near the optical transfer surface 61e. In the pipe portion P1, the size of the cross-sectional area is not constant or the same. Specifically, as shown in FIGS. 4B and 4C, the first piping portion P1 has a blocking member 67 that restricts the flow of the heat medium, and the second piping portion. The inner diameter is narrower than P2. The blocking member 67 is detachable, and the cross-sectional area of the first piping portion P1 can be adjusted to a desired area according to the size of the blocking member 67. Thereby, the temperature of the molding die 40 can be easily adjusted. Here, FIG. 4B is a partially enlarged perspective sectional view of the area AR shown in FIG. As shown in FIG. 4B, the blocking member 67 protrudes in a dam shape in the cross section of the first piping portion P1. The blocking member 67 has a quadrangular shape in a cross section in a direction perpendicular to the flow path of the first piping portion P1 (direction perpendicular to the flow of the heat medium). In the present embodiment, the blocking member 67 is fixed so as to be embedded at two opposing positions in the first flow path FP1 arranged in an annular shape. The blocking member 67 has a size that blocks about 25% of the cross-sectional area of the first flow path FP1. A groove (not shown) in which the blocking member 67 is fitted is formed in the template 60a. The blocking member 67 is press-fitted into the groove and attached to the template 60a. The grooves can be formed at appropriate positions along the temperature adjusting pipe 66a of the template 60a, and the position and number of the blocking members 67 can be changed as appropriate. As shown in FIG. 3A and the like, in this embodiment, the blocking member 67 is an intermediate portion between the top side above the first mold 41 (C direction) and the ground side below (D direction). And it is arrange | positioned at the 1st piping part P1. The position of the blocking member 67 is determined by the temperature difference of the optical transfer surface 61e. Before attaching the blocking member 67, the cross-sectional area of the temperature adjusting pipe 66a is substantially constant. When the first mold 41 is heated in a state where the cross-sectional area is substantially constant, a temperature difference tends to occur between the optical transfer surfaces 61e. The position of the first piping portion P1 is a portion where the temperature of each optical transfer surface 61e before the blocking member 67 is attached becomes relatively low. In the temperature adjusting pipe 66a having an annular structure as in the present embodiment, the temperature is relatively low in the intermediate part (direction perpendicular to the CD direction) of the two inlets 66c and 66d. Therefore, the blocking member 67 is disposed with the intermediate portion between the inlets 66c and 66d as the first piping portion P1. The flow of the heat medium in the first pipe portion P1 having a relatively small inner diameter is a turbulent flow, and the flow of the heat medium in the second pipe portion P2 is a laminar flow. Occurrence of turbulent flow in the first piping portion P1 can efficiently increase the temperature of the first piping portion P1, and the temperature difference from the second piping portion P2 having a relatively high temperature is eliminated. To do.

  Hereinafter, the flow of the heat medium in the temperature adjusting pipe 66a will be described. In FIG. 3 (E), the second flow path FP2 is schematically shown outside the first flow path FP1, but is actually opposed. As shown in FIGS. 3 (C) to 3 (E), the heat medium is in the upper side (vertically upward) inlet 66c above the first mold 41 (C direction) and below (D direction). It flows in from a certain ground side (vertically downward) inlet 66d. The heat medium flowing in from the top-side injection port 66c of the first mold 41 flows clockwise in the first flow path FP1, passes through the ground-side connection port 66e of the first mold 41, and passes through the second mold FP1. It flows into the flow path FP2 (solid line). Thereafter, the heat medium flows clockwise in the second flow path FP2 and flows out from the top-side outlet 66f of the first mold 41 (broken line). On the other hand, the heat medium flowing in from the ground side inlet 66d of the first mold 41 flows clockwise in the first flow path FP1, passes through the top side connection port 66g of the first mold 41, It flows into the second flow path FP2 (dashed line). Thereafter, the heat medium flows clockwise in the second flow path FP2 and flows out from the ground side outlet 66h of the first mold 41 (two-dot chain line).

  Returning to FIG. 2A, the mounting plate 64 is a metal plate-like member, and supports the mold part 60 from behind. The mounting plate 64 has sprue connection ports 64b connected so as to extend the sprue connection ports 61b and 61c provided in the peripheral portion 63 of the mold part 60 and the receiving plate 60b. A sprue port portion 65 is formed on the base side of the sprue connection port 64b to contact the tip of the nozzle 16d of the injection device 16.

  The second mold 42 is a movable mold, and includes a mold part 70 disposed on the inner side, that is, the parting surface PS2, a mounting plate 74 disposed on the outer side, that is, the movable platen 12 side in FIG. And an ejector member 75 formed so as to be embedded in 74. Among these, the mold part 70 has a divided structure divided into a plurality of parts. The mold part 70 has a template 70a and a receiving plate 70b. In the mold part 70, the template 70a and the receiving plate 70b are fixed to each other with bolts or the like.

  Of the mold part 70, the mold plate 70a includes a core part 72 as a mold body and a peripheral part 73 surrounding the mold body as divided parts. The peripheral portion 73 of the template 70a is a metal plate-like member, and includes a plurality of core holding ports 71a into which the plurality of core portions 72 are inserted, and a cold slug 71b facing the sprue connection port 61b. A core portion 72 is inserted into each core holding port 71a, and a tip surface of the core portion 72 is an optical transfer surface 71e for forming an optical function portion of the optical element. The peripheral portion 73 is also formed with a pin insertion port 71g through which an ejector pin 75a constituting the ejector member 75 is passed.

  The receiving plate 70b is a metal plate-like member, is disposed between the template plate 70a and the mounting plate 74, and supports the template plate 70a from behind. The receiving plate 70b includes pin insertion openings 71h and 71i through which the ejector pins 75a constituting the ejector member 75 are passed.

  Inside the mold part 70, as with the first mold 41, in order to keep the temperature of the molding die 40 at an appropriate temperature during molding, a temperature adjusting pipe 76 a for circulating a heat medium, a temperature monitoring temperature A meter (not shown) is formed. The temperature adjustment pipe 76 a and the like are connected to the mold temperature controller 47. Hereinafter, since the mold part 70 has the same configuration as the mold part 60 of the first mold 41, the description thereof will be omitted as appropriate.

  The temperature adjusting pipe 76a is formed by a combination of a pair of grooves provided so as to face each other between the template 70a and the receiving plate 70b. As shown in FIG. 3B, the temperature adjustment pipe 76a is disposed so as to surround the optical transfer surface 71e along the periphery of the closed line ST connecting the plurality of optical transfer surfaces 71e. The temperature adjustment pipe 76a has an annular shape when viewed from the surface (parting surface PS2 shown in FIG. 2A) where the first mold 41 and the second mold 42 face each other. Similar to the temperature adjustment pipe 66a of the first mold 41, the temperature adjustment pipe 76a of the present embodiment is a split double type flow path. Specifically, the temperature adjustment pipe 76a has a double structure in which the adjacent front-side pipe HP1 and back-side pipe HP2 are connected via connection ports 76e and 76g (see FIG. 3F, etc.). . That is, the temperature adjustment pipe 76a is configured by a front side pipe HP1 corresponding to the first flow path FP1 on the template 70a side and a back side pipe HP2 corresponding to the second flow path FP2 on the receiving plate 70b side. . As shown in FIG. 3 (B), the temperature adjusting pipe 76a is located above and below the mold plate 70a side of the second mold 42 and adjacent to the connection ports 76e and 76g. The inlets 76c and 76d are respectively introduced into the inlet. The temperature adjusting pipe 76a has outlets 76f and 76h for allowing the heat medium to flow out of the flow path above and below the receiving plate 70b side of the second mold 42 and adjacent to the connection ports 76e and 76g. Each has. A partition wall WA is provided between the inlets 76c and 76d and the outlets 76f and 76h and the connection ports 76e and 76g adjacent to the inlets 76c and 76d and the outlets 76f and 76h, respectively, separating the first and second flow paths FP1 and FP2. As described above, by dividing the first and second flow paths FP1 and FP2 into two by the partition wall WA, as in the case of the first mold 41 or the mold portion 60, the temperature adjustment pipe 76a has two circulation paths. Is formed.

  The temperature adjustment pipe 76a has a uniform flow path cross section as a whole, but the first corresponding to the portion of the plurality of optical transfer surfaces 71e whose temperature tends to be relatively low during molding. The cross-sectional area of the pipe part P1 is locally smaller than the cross-sectional area of the second pipe part P2 corresponding to the part where the temperature tends to be relatively high. Specifically, the first piping portion P1 has a blocking member 77 that restricts the flow of the heat medium, and has an inner diameter smaller than that of the second piping portion P2. In the present embodiment, the blocking member 77 is fixed so as to be embedded at two opposing positions in the first flow path FP1 arranged in an annular shape. A groove (not shown) into which the blocking member 77 is fitted is formed in the template 70a. The blocking member 77 is press-fitted into the groove and attached to the template 70a. As shown in FIG. 3B and the like, in the present embodiment, the blocking member 77 is an intermediate portion between the top side above the second mold 42 (C direction) and the ground side below (D direction). It arrange | positions to the 1st piping part P1. Occurrence of turbulent flow in the first piping portion P1 can efficiently increase the temperature of the first piping portion P1, and the temperature difference from the second piping portion P2 having a relatively high temperature is eliminated. To do.

  Hereinafter, the flow of the heat medium in the temperature adjusting pipe 76a will be described. As shown in FIG. 3 (F), the heat medium is divided into a top side (vertically upward) inlet 76c above the second mold 42 (C direction) and a ground side (vertical) below (D direction). It flows in from the lower (inlet) 76d. The heat medium flowing in from the top inlet 76c of the second mold 42 flows counterclockwise in the first flow path FP1, passes through the ground side connection port 76e of the second mold 42, It flows into the two flow paths FP2 (solid line). Thereafter, the heat medium flows counterclockwise in the second flow path FP2 and flows out from the top side outlet 76f of the second mold 42 (broken line). On the other hand, the heat medium flowing in from the ground side inlet 76d of the second mold 42 flows counterclockwise in the first flow path FP1, and passes through the top side connection port 76g of the second mold 42. , Flows into the second flow path FP2 (dashed line). Thereafter, the heat medium flows counterclockwise in the second flow path FP2 and flows out from the ground side outlet 76h of the second mold 42 (two-dot chain line).

  Returning to FIG. 2A, the mounting plate 74 is a metal plate-like member, and supports the mold part 70 from behind. The mounting plate 74 includes pin insertion openings 74g and 74h through which the ejector pins 75a and 75b constituting the ejector member 75 are passed.

  The ejector member 75 is a mechanical mechanism having ejector pins 75a and 75b and an ejector plate 75d, and operates by being driven by the ejector driving unit 45 of FIG. The ejector pins 75a and 75b are connected to the ejector plate 75d, and can be moved forward and backward collectively within the pin insertion ports 71g, 71h and 71i of the mold portion 70 and the pin insertion ports 74g and 74h of the mounting plate 74. it can. When the ejector member 75 is set in the advanced state, the ejector pins 75a and 75b move forward, and the central ejector pin 75a protrudes from the bottom of the cold slug 71b provided in the peripheral portion 73 of the mold portion 70, and other ejectors. The pin 75b pushes the core part 72 and protrudes from the parting surface PS2. On the contrary, when the ejector member 75 is in the retracted state, the ejector pins 75a and 75b are retracted, and the central ejector pin 75a is retracted into the bottom of the cold slug 71b provided in the peripheral portion 73 of the mold portion 70, The pin 75b is retracted to allow the core portion 72 to retract. The core portion 72 has a structure with an unillustrated spring or the like attached. When the core portion 72 is not subjected to the urging force that moves forward from the ejector pin 75a, the core portion 72 moves backward and is stored behind the core holding port 71a. .

  In addition, when the 1st metal mold | die 41 and the 2nd metal mold | die 42 are clamped, the optical transfer surface 61e of the core part 62 incorporated in the 1st metal mold | die 41, and the core part 72 incorporated in the 2nd metal mold | die 42 are shown. A cavity CV for forming an optical element is formed between the optical transfer surface 71e and the optical transfer surface 71e. A runner space RU is formed between a mold surface part 61r provided on the mold surface of the mold part 60 of the first mold 41 and a mold surface part 71r provided on the mold surface of the mold part 70 of the second mold 42. It is formed. The runner space RU is a part of the flow path space FC shown in FIG. 2B, and communicates with the sprue connection port 61b (see FIG. 2A).

  Hereinafter, a method for manufacturing a molded product MP, that is, an optical element, using the molding apparatus 100 shown in FIG. 1 will be described. First, the temperature distribution of the molding die 40 is measured in the initial state in the previous stage of the molding cycle. In the previous stage of the molding cycle, the cross-sectional areas of the temperature adjusting pipes 66a and 76a in the mold parts 60 and 70 are not adjusted and are substantially constant. In this state, the temperature of the heated molding die 40 is measured, and the temperature difference between the optical transfer surfaces 61e and 71e is measured. A temperature difference between the optical transfer surfaces 61e and 71e is calculated from the obtained temperature, and a piping portion corresponding to a portion where the temperature tends to be relatively low is defined as a first piping portion P1. The blocking members 67 and 77 are attached to the first piping portion P1, and the cross-sectional area of the first piping portion P1 is made smaller than the initial state (temperature adjustment step). In the present embodiment, the cross-sectional area in the lateral direction (specifically, the middle portion between the top side and the ground side) where the temperature is relatively low is reduced. Thereafter, in this stage of the molding cycle, the mold temperature controller 47 heats both molds 41 and 42 to a temperature suitable for molding. When the molds 41 and 42 are heated by narrowing the cross-sectional area of the first piping part P1, heat resistance and pressure (turbulent flow) are generated in the temperature adjusting pipes 66a and 76a, and the first piping part P1 and the surrounding temperature rise. As a result, the temperature distribution of the temperature adjusting pipes 66a and 76a in the mold parts 60 and 70 becomes uniform.

  After the temperature of the molding die 40 is uniform and stable, the opening / closing drive device 15 is operated to advance the movable platen 12 to start mold closing (mold closing process). By continuing the closing operation of the opening / closing drive device 15, as shown in FIG. 2 (B), mold clamping is performed to clamp the first mold 41 and the second mold 42 with a necessary pressure. In this state, in the injection molding machine 10, the injection device 16 is operated to inject molten resin into the cavity CV between the clamped first mold 41 and the second mold 42 at a necessary pressure. To perform injection (injection process). The injection molding machine 10 maintains the resin pressure in the cavity CV. Note that after the molten resin is introduced into the cavity CV, the molten resin in the cavity CV is gradually cooled by heat dissipation, so that the molten resin is solidified with the cooling and waits for completion of molding. Next, in the injection molding machine 10, the opening / closing drive device 15 is operated to perform mold opening for retracting the movable platen 12 (mold opening process). Along with this, the second mold 42 moves backward, and the first mold 41 and the second mold 42 are separated. Next, in the injection molding machine 10, the ejector driving unit 45 is operated, and the molded product MP including the optical element is ejected by the advancement of the ejector pins 75a and 75b. As a result, the optical element of the molded product MP is pushed out to the first mold 41 side and released from the second mold 42 (release process). Finally, the take-out device 20 is operated so that the proper position of the extruded molded product MP is gripped by the hand 21 and taken out to the outside (take-out process).

  In the optical element molding die described above, the cross-sectional areas of the temperature adjusting pipes 66a and 76a are in accordance with the temperature distribution of the optical transfer surfaces 61e and 71e during molding when the cross-sectional area is substantially constant. By being different so as to compensate for this temperature distribution, the temperature difference between the optical transfer surfaces 61e and 71e can be reduced. For example, by reducing the cross-sectional area of the first piping portion P1 corresponding to the portion of the plurality of optical transfer surfaces 61e and 71e whose temperature tends to be relatively low at the time of molding, the first is smaller than the case where it is not reduced. The temperature of the piping part P1 becomes higher. Thereby, the temperature difference between the cavities CV formed between the optical transfer surfaces 61e and 71e of the first and second molds 41 and 42 can be eliminated. Therefore, a highly accurate optical element can be molded even in the production of a multi-piece optical element. Further, since the temperature of the molding die can be adjusted relatively easily by adjusting the cross-sectional areas of the temperature adjusting pipes 66a and 76a, it is not necessary to provide a separate heater or additional pipe.

  When there is a temperature difference between the cavities CV, a difference in optical performance (for example, 1 ° C.≈Newton ring (interference fringe)) occurs, and it becomes difficult to obtain a large number of high-precision optical elements.

[Second Embodiment]
Hereinafter, the molding die for optical elements according to the second embodiment will be described. The molding die for the optical element according to the second embodiment is a modification of the molding die for the optical element according to the first embodiment, and the matters not specifically described are the molding die for the optical element according to the first embodiment. Similar to mold.

  As shown in FIG. 5 (A), in the present embodiment, the temperature adjustment pipe 66a includes first and second intermediate portions between the top side above the first mold 41 and the ground side below. A partition wall WA that separates the two flow paths FP1 and FP2 is provided. Further, connecting ports 66e and 66g for connecting the first flow path FP1 and the second flow path FP2 are provided above and below the partition wall WA. As a result, the heat medium flows through the half of the temperature adjustment pipe 66a between the top side and the ground side, that is, vertically up and down. In the temperature adjusting pipe 66a having the branch structure as in the present embodiment, the periphery of the injection port 66c that is an intermediate portion between the two connection ports 66e and the periphery of the injection port 66d that is an intermediate portion between the two connection ports 66g. However, the temperature tends to be relatively low. Therefore, the blocking member 67 is disposed in the first piping portion P1 corresponding to the heat medium inlets 66c and 66d, and the cross-sectional area of the piping portion at the top and bottom (CD direction) is reduced to reduce the first portion. Increase the temperature of the piping part P1.

  Hereinafter, the flow of the heat medium in the temperature adjusting pipe 66a will be described. As shown in FIGS. 5 (C) to 5 (E), the heat medium flowing in from the top-side inlet 66c flows in two directions in the first flow path FP1, and flows from the connection port 66e to the second flow path. It flows into FP2 (solid line). Thereafter, the heat medium that has flowed into the second flow path FP2 flows back to the top side, and flows out from an outlet 66f provided on the opposite side of the injection port 66c (broken line). On the other hand, the heat medium flowing in from the ground-side inlet 66d also flows in two directions in the first flow path FP1, and flows into the second flow path FP2 from the connection port 66g (dashed line). Thereafter, the heat medium flowing into the second flow path FP2 flows back to the ground side, and flows out from the outlet 66h provided on the opposite side of the injection port 66d (two-dot chain line).

  The temperature adjustment pipe 76a in the second mold 42 also has the same structure and heat as the temperature adjustment pipe 66a in the first mold 41 as shown in FIGS. 5 (B) and 5 (F). This is a medium flow, and the description is omitted.

(Example)
Specific examples will be described below.
As an example, temperature adjusting pipes 66a and 76a (annular structure) shown in FIG. In the present embodiment, rectangular blocking members 67 and 77 as shown in FIG. 4B and the like are provided in the first pipe portion P1 where the temperature of the temperature adjusting pipes 66a and 76a is relatively low. . The blocking members 67 and 77 were arranged at two locations in the middle portion between the injection ports 66c and 66d. The blocking members 67 and 77 are large enough to block about 25% of the cross-sectional area of the first flow path FP1. The temperature was measured using a crystal temperature sensor with high resolution. A temperature difference between the optical transfer surfaces 61e and 71e was calculated from the obtained temperature. In the first mold 41, as shown in FIG. 6 (A), the temperature measurement position is the measurement position (7) on the celestial side indicated by a bold line among the measurement positions (1) to (8) arranged clockwise. ), The measurement position (4) on the ground side, and the measurement positions (2) and (5) in the lateral direction. Moreover, in the 2nd metal mold | die 42, as shown in FIG.6 (B), as shown in FIG.6 (B), among the measurement positions of (1)-(8) arrange | positioned counterclockwise, the measurement of the celestial side shown with a thick line The position (7), the ground side measurement position (4), and the lateral measurement positions (2) and (5). The temperature difference in the figure was calculated based on the measurement position (7) on the top side.

  As a comparative example, the temperature adjustment pipe (annular structure) shown in FIG. 3 (A) and the like without the blocking members 67 and 77 and the temperature adjustment pipe (branch structure) shown in FIG. 5 (A) and the like. Using. The measurement method and measurement position in the comparative example are the same as in the example.

  FIG. 7A and FIG. 8A are diagrams for explaining the relationship between the temperature measurement position and the temperature difference in the example and the comparative example in the first mold 41. In FIG. 7A, a solid line L1 indicates a temperature adjustment pipe 66a (annular structure) having the blocking member 67 of the embodiment, and a broken line L2 indicates a temperature adjustment pipe (circle) having no blocking member of the comparative example. Ring structure). In FIG. 8A, an alternate long and short dash line L3 indicates a temperature adjustment pipe (branch structure) that does not have the blocking member of the comparative example. As shown in FIG. 7A, the temperature difference between the optical transfer surfaces 61e of the example is 0.3 ° C. or less (range surrounded by a dotted line) at any measurement position, and the temperature difference is extremely high. small. On the other hand, the temperature difference of the comparative example was 1.22 ° C. at maximum, especially in the temperature adjustment pipe (annular structure) that does not have the blocking member, and the temperature difference became large. When the temperature difference is 1.22 ° C., the optical performance of the optical element obtained by simultaneous molding of a large number varies, but the temperature of the temperature adjustment pipe 66a is low, and the optical transfer surface 61e (in this embodiment, the measurement position) By providing the blocking member 67 on the piping portion in the vicinity of the optical transfer surface (2) and (5), the temperature difference is reduced to 0.3 ° C. or less, and the optical performance of the optical element can be made uniform. Recognize.

  FIGS. 7B and 8B are diagrams for explaining the relationship between the temperature measurement position and the temperature difference in the second mold 42 according to the example and the comparative example. In the second mold 42 as well, as in the first mold 41, the temperature difference of the comparative example, in particular, the temperature adjusting pipe (annular structure) having no blocking member was 0.79 ° C. at maximum. By providing the member 77, the temperature difference of the example was reduced to 0.3 ° C. or less.

  As shown in FIG. 8 (B), the temperature adjustment pipe having the branch structure shown in FIG. 5 (A) also has a portion where the temperature difference is a maximum of 0.64 ° C., but in this case, the temperature is low. If a blocking member is provided near the optical transfer surface 71e (in the case of this comparative example, the optical transfer surface at the measurement positions (4) and (7)), the temperature difference can be eliminated.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications are possible. For example, in the above embodiment, the shape of the cavity CV provided in the molding die constituted by the first die 41 and the second die 42 can be various shapes. That is, the shape of the cavity CV formed by the optical transfer surfaces 61e, 71e, etc. is merely an example, and can be appropriately changed according to the use of various optical elements.

  In the above embodiment, the position, number, area, thickness, and the like of the blocking members 67 and 77 provided in the temperature adjusting pipes 66a and 76a can be appropriately changed.

  In the above embodiment, the blocking members 67 and 77 project in a dam shape in the cross section of the first piping part P1, but may project in an annular shape.

  In the above-described embodiment, the blocking members 67 and 77 provided in the temperature adjusting pipes 66a and 76a may be any members that disturb the flow of the heat medium. Further, the surface of the blocking member may be processed rough.

  In the above embodiment, the number of the heat medium inlets 66c and 66d can be changed as appropriate.

  In the above embodiment, the partition walls WA are provided in the temperature adjustment pipes 66a and 76a. However, the pipes WA may be used instead of the partition walls WA by not forming the pipe grooves in the mold plates 60a and 70a and the receiving plates 60b and 70b.

  In the above embodiment, if the temperature adjustment pipes 66a and 76a are arranged at positions close to the cavity CV along the periphery of the line ST, the first mold 41 and the second mold 42 face each other. The ring shape does not have to be viewed from (parting surfaces PS1, PS2).

  In the above-described embodiment, the temperature adjustment pipes 66a and 76a are provided in the first and second molds 41 and 42, respectively, but are provided only in one of the first and second molds 41 and 42. Also good.

  In the above embodiment, the resin filled in the cavity CV is not limited to the thermoplastic resin, but may be a thermosetting resin or other various materials.

  In the above embodiment, the injection molding machine 10 is not limited to the horizontal type, but can be a vertical type molding machine in which the first mold 41 and the second mold 42 are arranged vertically.

  DESCRIPTION OF SYMBOLS 10 ... Injection molding machine, 11 ... Fixed board, 12 ... Movable board, 40 ... Molding die, 41 ... 1st metal mold, 42 ... 2nd metal mold, 60, 70 ... Mold part, 60a, 70a ... Template 60b, 70b ... receiving plate, 61e, 71e ... optical transfer surface, 66a, 76a ... temperature adjustment piping, 66c, 66d, 76c, 76d ... injection port, 66e, 66g, 76e, 76g ... connection port, 66f, 66h , 76f, 76h ... outlet, 67, 77 ... blocking member, 100 ... molding device, CV ... cavity, FP1 ... first flow path, FP2 ... second flow path, MP ... molded product, P1 ... first piping part, P2 ... second piping part, PS1, PS2 ... parting surface, WA ... partition wall

Claims (9)

A first mold and a second mold;
At least one of the first and second molds includes a plurality of optical transfer surfaces for molding a plurality of optical elements on a surface where the first mold and the second mold face each other, and the first and second molds. And a temperature adjusting pipe through which the heat medium passes inside the mold,
In the temperature adjustment pipe, the cross-sectional area of the first pipe portion corresponding to the portion of the plurality of optical transfer surfaces that tends to have a relatively low temperature during molding tends to have a relatively high temperature. A molding die for an optical element, which is smaller than a cross-sectional area of a second pipe portion corresponding to a certain portion.   2. The molding die for an optical element according to claim 1, wherein the first pipe portion has a blocking member that restricts the flow of the heat medium.   3. The molding die for an optical element according to claim 2, wherein the blocking member protrudes in a dam shape or an annular shape in a cross section of the first pipe portion.   The molding die for an optical element according to any one of claims 2 and 3, wherein the blocking member is detachable.   The flow of the heat medium in the second pipe portion is a laminar flow, and the flow of the heat medium in the first pipe portion is a turbulent flow. A molding die for an optical element described in the item.   6. The molding die for an optical element according to claim 1, wherein the temperature adjustment pipe is a split-type flow path that connects adjacent pipes via a connection port. Type.   The number of injection holes for the heat medium provided in the temperature adjusting pipe is smaller than the number of the optical transfer surfaces, for an optical element according to any one of claims 1 to 6. Molding mold.   The metal mold for an optical element according to any one of claims 1 to 7, wherein the temperature adjusting pipe is disposed along a periphery of a line connecting the plurality of optical transfer surfaces. Type.   The said temperature adjustment piping has an annular shape seeing from the surface where the said 1st metal mold | die and a said 2nd metal mold | die oppose, The Claim 1 characterized by the above-mentioned. Mold for optical elements.

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