JP2016129971A - Injection molding mold, optic element production method and optic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate a relative position and relative movement of a movable mold and a fixed mold, in mold opening operation and in mold release operation, and prevent damage of an optic element which is a molded product.SOLUTION: A cavity for molding a molded product of an optic element (17) is defined by a movable mirror face piece 6 and a movable holding piece 7 of a movable mold, and a fixed mirror face piece 1 and a fixed holding piece 2 of a fixed mold. The movable mold comprises an ejector pin 9 as an extrusion member for releasing the molded optic element (17). The fixed mold comprises a sprue 13 for injecting molten resin, which is linearly disposed along a mold opening direction of the movable mold. As a fitting structure for limiting the relative movement of the movable mold and the fixed mold, in the mold opening direction, a straight pin 5 is disposed on the fixed holding piece 2, and a ball retainer 11 is disposed on the movable holding piece 7. The fitting structures can fit each other by irregular structures so as to protrude and retreat each other, and maintain a fitting state until the optic element is released from the movable mold.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an injection mold for molding an optical element using a movable mold and a fixed mold, a method for manufacturing an optical element for injection molding an optical element using the injection mold, and the injection mold. The present invention relates to an optical element that is injection-molded using the above.

  Resin optical elements using various plastic materials, such as lenses, are widely used in eyeglasses and various industrial products. An injection mold used for injection molding of various resin optical elements by an injection molding apparatus includes a fixed mold and a movable mold. A cavity for molding the optical element is defined by the mold surfaces of the fixed mold and the movable mold. The fixed mold is fixedly attached to the injection molding apparatus, and the movable mold is supported on a guide member such as a guide rail, and fixed according to the progress of the injection molding process such as mold closing and mold opening. It is moved relative to the mold. In many cases, a portion called a movable mold piece of a fixed mold of an injection mold is configured to be detachable from an injection molding apparatus. An injection path called a sprue communicating with the cavity is formed on the fixed mold side, and molten resin is injected into the cavity from the injection molding apparatus via the sprue.

  In injection molding of an optical element, a fixed mold is composed of, for example, a fixed mirror piece that transfers a lens surface and a fixed holding piece that holds the fixed mirror piece. On the other hand, for convenience in the process, the molded product (in this case, the optical element) is often first opened while being supported on the movable mold side, and then released from the movable mold. In this case, the movable mold includes, for example, a movable mirror piece for transferring the lens surface, a movable holding piece for holding the lens surface, an ejector pin for pushing the molded product (optical element) from the movable mold, a center pin, and the like. . Further, the center pin portion of the movable mold may be provided with a portion called a sprue lock or the like that is coupled to a portion of the molded product corresponding to the above-described sprue of the movable die via a hook-shaped engagement portion. . For this reason, the center pin of the movable mold is sometimes called a sprue lock pin. The sprue lock is used, for example, for releasing from a fixed mold while a molded product is supported by a movable mold.

  The cavity (air gap) defined by the mold closing of the fixed mold and the movable mold is divided into parts such as a cavity (in the narrow sense) that molds the main part of the sprue, runner, gate, and optical element. . Molten resin is inject | poured with respect to each of these site | parts in said order. In addition, each site | part of said (broad sense) cavity may be used as it is as a name of each site | part of the molded product after shaping | molding.

  Due to the property that the fixed mold sprue is a molten resin injection path, after casting, the sprue portion of the molded product has the greatest depth in the fixed mold. For this reason, in general, the sprue portion of the fixed mold is formed linearly (in parallel) so as to coincide with the mold opening direction in order to easily release the corresponding portion of the molded product from the fixed mold, and the molded product. It is configured as a flow path with a tapered cross section so that the diameter on the side of the taper increases.

  After casting the molten resin, the mold is kept in a closed state, for example, maintained at a temperature lower than the glass transition point of the resin and higher than the atmosphere, and the resin in the mold is cooled and solidified. For this reason, a flow path for circulating a cooling medium may be disposed inside the fixed mold or the movable mold. After cooling and solidification, the movable mold is moved to open the mold, and the molded product is first peeled off (released) from the fixed mold.

  Subsequently, during this mold opening or after mold opening, the molded product is extruded from the movable mold with, for example, a movable mirror piece on the movable mold side, an ejector pin arranged on the runner, and a center pin (a sprue lock pin). Mold release) and take out from the injection molding apparatus. An injection molding apparatus may be provided with a take-out unit for taking out and collecting a released molded product.

  The configuration of an apparatus for injection-molding an optical element with the structure and operation as described above is known, and is described, for example, in Patent Document 1 below.

JP 2010-012693 A

  In the conventional injection molding apparatus described in Patent Document 1, the movable mold and the fixed mold are coupled to the injection molding apparatus on the lower side thereof and are movablely supported or fixedly supported. In many cases, the positioning means is not provided on the upper side in consideration of the convenience. Therefore, when the mold opening operation is started and the clamping force is released, the mold is deformed or displaced by its own weight deformation due to the mold mass, the temperature rise of the mold, or the nozzle touch force of the molding machine. There is a case to do. In particular, there is a degree of freedom of movement on the upper side of the mold having no positioning means of the injection molding apparatus, and the movable mold and the fixed mold move not only in a predetermined mold opening direction but also in a direction crossing the mold opening direction. Or tilt.

  For example, in the mold opening process, particularly in releasing from the fixed mold, an operation of pulling out a sprue portion of the molded product from the fixed mold through a center pin coupled by a sprue lock is performed. Also, in the mold opening process, for example, in the middle of mold opening, before all the sprue parts of the molded product are pulled out from the fixed mold, an operation of pushing out the molded product from the movable mold with the center pin may be performed. is there. In any case, the above operation is performed in a state in which all the sprue parts of the molded product are not pulled out of the fixed mold, and at that time, the deformation and displacement of the movable mold and the fixed mold occur. The sprue of the molded product may come into contact with the fixed mold. At this time, for example, the stress applied to the sprue portion of the molded product may cause the lens portion of the molded product to be deformed or the lens portion of the molded product to be scratched.

  In addition, during the mold opening operation, the lens surface of the molded product peeled off from the fixed mold is rapidly cooled by the atmosphere between the time when the molded product is peeled from the fixed mold and the molded product is taken out from the movable mold. The lens surface to which the movable mold is transferred is cooled by the mold. As a result, a temperature distribution is generated between the lens surfaces of the molded product, and the lens of the molded product may be warped to deteriorate the shape accuracy.

  In view of the above, an object of the present invention is to provide a movable mold and a fixed mold at the time of mold opening operation or mold release when an optical element is injection molded using an injection mold comprising a movable mold and a fixed mold. In other words, it is possible to prevent the damage of the optical element that is a molded product.

  In order to solve the above-described problems, in the present invention, a cavity for molding an optical element is formed between an extrusion member, a first mold including a holding member for holding the extrusion member, and the extrusion member. In the injection mold including the second mold to be formed, the holding member and the second mold are fitted to each other by a concavo-convex structure so as to be protruded and retractable, and the holding member and the second mold A fitting structure that restricts relative movement to a direction orthogonal to the mold opening direction is provided, and the fitting structure maintains a fitting state with each other at the timing of releasing the optical element from the second mold. It is characterized by being comprised.

  According to the above configuration, by providing a fitting structure between the movable mold and the fixed mold of the injection mold, the relative position or relative movement between the movable mold and the fixed mold during mold opening operation or mold release. Is excellently controlled, and damage to the optical element that is a molded product can be prevented.

It is sectional drawing of the injection mold concerning the 1st Example of this invention. It is a flowchart which manufactures an optical element in the 1st Example of this invention. It is detail drawing of the mold release process concerning the 1st Example of this invention. It is sectional drawing of the injection mold concerning this invention. It is sectional drawing of the injection mold concerning this invention. It is sectional drawing of the injection mold concerning a prior art.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to embodiments shown in the accompanying drawings. The following embodiment is merely an example, and for example, a detailed configuration can be appropriately changed by those skilled in the art without departing from the gist of the present invention. Moreover, the numerical value taken up by this embodiment is a reference numerical value, Comprising: This invention is not limited.

  FIG. 1 shows an example of the configuration of an injection mold that employs the present invention. In this embodiment, the injection mold for injection molding the optical element includes a fixed mold A and a movable mold B, and these fixed mold A and movable mold B are mounted on an injection molding apparatus.

  FIG. 1 (or FIGS. 3 (a) to 3 (e), FIG. 4 and FIG. 5 described later) shows that the fixed mold A and the movable mold B of this embodiment are mounted on an injection molding apparatus, and the mold is opened / closed and released. The state when operated is shown as a cross-sectional structure. The fixed mold A and the movable mold B of the present embodiment are used by being mounted on an injection molding apparatus in order to injection mold an optical element (for example, a lens). The injection molding apparatus to which the fixed mold A and the movable mold B of the present embodiment are attached is, of course, an optical element manufacturing apparatus for manufacturing an optical element as a molded product if the molded product is an optical element (for example, a lens). Will be configured. FIG. 1 shows a fixed mold A and a movable mold B in a state where the mold is closed by an injection molding apparatus (the whole is not shown). The fixed mold A and the movable mold B are composed of the following members.

  In FIG. 1, the fixed mold A includes a fixed mirror piece 1 having a transfer surface for forming a lens surface of a molded product, and a fixed holding piece 2 that holds the fixed mirror piece 1. Further, the fixed mold A includes a fixed die set 3 that holds the fixed holding piece 2 and a sprue bush 4 for injecting resin from a nozzle of an injection molding apparatus. At the time of resin injection, a nozzle (not shown) of an injection molding device comes into contact with the concave portion at the right end of the sprue bush 4 and the resin is injected.

  Inside the sprue bush 4, a sprue 13 having a diameter that increases in the resin injection direction is defined. The sprue 13 is a resin injection path, and is arranged linearly along the mold opening direction of the movable mold B described later.

  The fixed holding piece 2 of the fixed mold A of the present embodiment is provided with one or more straight pins 5 having a cylindrical cross section. In FIG. 1, the cross section of two straight pins 5 is shown. The method of providing the straight pin 5 on the fixed holding piece 2 is arbitrary, and the straight pin 5 is integrally formed with the fixed holding piece 2 by cutting or the like, or is screwed to the fixed holding piece 2 by a screwing structure not shown. It is attached by wearing. The straight pin 5 constitutes a fitting structure together with a ball retainer 11 (rolling bearing) provided as a movable support mechanism on the movable mold B side described later.

  The movable mold B includes a movable mirror piece 6 having a transfer surface for forming a lens surface of a molded product, and a movable holding piece 7 that holds the movable mirror piece 6 and forms a flange around the lens. Further, the movable mold B includes a movable die set 8 that holds the movable holding piece 7, an ejector pin 9, and a center pin 10. The entire movable mold B composed of the above-mentioned parts is movably supported by a mold moving device of an injection molding device (not shown). In the present specification, the movable mirror piece 6 may be referred to as an extruding member, and the movable holding piece 7 may be referred to as a holding member. Moreover, although the example which has the movable mirror surface piece 6, the movable holding piece 7, the movable die set 8, the ejector pin 9, and the center pin 10 is shown in a movable metal mold | die, you may have these in a fixed metal mold | die. Moreover, you may have these in both a movable metal mold | die and a fixed metal mold | die. In the present specification, of the movable mold and the fixed mold, a mold having a mirror piece, a holding piece, a die set, an ejector pin, and a center pin is referred to as a first mold, and the other is referred to as a second mold. May be referred to as a metal mold. In this case, the second mold may also have a mirror piece, a holding piece, a die set, an ejector pin, and a center pin.

  The respective parts of the movable mirror piece 6, the ejector pin 9, and the center pin 10 are slidably supported (moved and retracted) in through holes provided at predetermined positions of the movable holding piece 7 and the movable die set 8. The protruding amounts of the movable mirror piece 6, the ejector pin 9, and the center pin 10 are configured to be independently operated by an ejector mechanism (not shown) of the injection molding apparatus. The sliding direction of the movable mirror piece 6, the ejector pin 9, and the center pin 10 is usually configured to match (in parallel) with the mold opening / closing of the injection molding apparatus.

  The movable holding piece 7 corresponds to each of the straight pins 5 on the fixed holding piece 2 side when the fixed mold A and the movable mold B are mounted on the injection molding apparatus so as to form a predetermined mold closed state. A ball retainer 11 that fits with each straight pin 5 is provided at a position. This ball retainer 11 constitutes a movable support mechanism for moving and supporting the straight pin 5.

  Needless to say, the above-described predetermined mold closed state means that, for example, the movable mirror piece 6 of the movable mold B and the fixed mirror piece 1 of the fixed mold A define a cavity (gap) corresponding to the desired lens shape. The fixed mold A and the movable mold B are closed. As is well known, the ball retainer 11 has a structure in which a plurality of freely rotatable balls are arranged on the inner peripheral surface, and supports the straight pin 5 by the point contact of each ball.

  The ball retainer 11 is attached to the movable holding piece 7 in a mounting hole that has been previously drilled in the movable holding piece 7 by a method such as press fitting (insertion), and thereby integrated with the movable holding piece 7.

  As described above, the straight pin 5 and the ball retainer 11 provided in the fixed mold and the movable mold are fitted into each other so as to be able to protrude and retract by the concavo-convex structure, and the relative movement between the movable mold B and the fixed mold A is opened. The fitting structure which restrict | limits to a direction is comprised. Of the concavo-convex structure, it is arbitrary whether a concave or convex structure is disposed with respect to the movable mold B and the fixed mold A. For example, the straight pin 5 and the ball retainer 11 are disposed in the movable mold. B and the fixed mold A may be the reverse of the above. The straight pin 5 and the ball retainer 11 are respectively arranged at positions that do not hinder mold release and removal of a molded optical element (lens) described later. Details of the details including the dimensions of the straight pin 5 and the ball retainer 11 will be described later in detail.

  In this embodiment, the above-described fitting structure (straight pin 5 and ball retainer 11) is fitted to each other until the mold is released from the movable mirror piece 6 by at least the ejector pin 9 and the center pin 10 after the mold opening is started. Configured to maintain state.

  Further, in this embodiment, the movable mirror piece 6 of the movable mold B is also precisely movable in the surface normal direction of the lens center between the movable mirror piece 6 and the movable holding piece 7 as a movable support mechanism. A ball retainer 12 (rolling bearing) is installed so that it can be moved to the right. The ball retainer 12 constitutes a movable support mechanism that movably supports the movable mirror surface piece 6.

  The injection molding device is provided with a temperature management unit (not shown: sometimes called a mold temperature control device). For the temperature management of the mold, for example, a configuration in which a flow path (not shown) through which a fluid flows is arranged inside the above-described fixed mold A and movable mold B is used. In that case, for example, the fluid maintained at a constant temperature supplied from the injection molding apparatus side to the flow path flows through the flow path in the injection mold, so that the fixed mold A and the movable mold B are kept at a constant temperature. Kept.

  FIG. 2 shows the flow of an injection molding process using the injection mold of this embodiment in the form of a flowchart. The injection molding process in FIG. 2 proceeds in sequence under the initiative of a control system (not shown) of the injection molding apparatus.

  In FIG. 2, in the mold closing process (step S <b> 11), the movable mold B is moved by the mold moving device of the injection molding apparatus, and the straight pin 5 of the fixed mold A and the ball retainer 11 of the movable mold B are moved. The mold is closed and clamped while fitting. At this time, a plurality of balls of the ball retainer 11 roll while being elastically deformed by the straight pin 5 and the movable holding piece 7 of the fixed mold A, so that the fixed mold A and the movable mold B move while positioning each other. At the stage where the mold closing (clamping) process is completed, the movable mirror piece 6 of the movable mold B and the fixed mirror piece 1 of the fixed mold A define a cavity (gap) corresponding to the desired lens shape. It becomes a state.

  In the resin injection step (step S12), a nozzle (not shown) of the injection molding apparatus is brought into contact with the opening of the sprue bush 4 and molten resin is injected from the sprue bush 4. The molten resin is sequentially injected into each part of the cavity defined by the mold closing. Each part of this cavity (or equivalent to each part of the molded product) is a portion corresponding to the sprue 13, the sprue lock 14, the runner 15, the gate 16, and the molded product main body (17: this portion for the molded product after molding). Lens (17).

  Subsequently, in the cooling step (step S13), after resin injection, pressurization and injection of the above-mentioned cavity in the cavity between the fixed mold A and the movable mold B in which the injected resin is kept below the glass transition temperature of the resin. It cools in each part and solidifies.

  In the mold opening and releasing step (step S14), the entire movable mold B is moved in the mold opening direction (left side in FIG. 1) by the mold moving device of the injection molding apparatus. At the same time, the molded product is pushed out by the movable mirror surface piece 6, the ejector pin 9 arranged at the site of the runner 15, and the center pin 10 arranged at the site of the sprue lock 14. Details of the process including the mold opening and release timing will be described later in detail with reference to FIG.

  In the take-out process (step S15), a part of the molded product is gripped and moved outside the mold by a take-out device (not shown) of the injection molding device.

  Here, FIG. 3 is used to show details of the lens opening and releasing steps of the lens according to the present invention.

  FIG. 3A shows an injection mold after completion of the mold closing process, resin injection process, and cooling process.

  After the cooling process is completed, as shown in FIG. 3B, the movable mold B is moved by the mold moving device of the injection molding apparatus until the fixed mold A and the movable mold B reach the distance Lb, and molding is performed. The product is peeled from the fixed mold A.

  The distance Lb is set smaller than the protruding amount L of the straight pin 5 of the fixed mold A from the parting line surface of the injection mold. In addition, the straight pins 5 on the fixed mold A side and the balls (spheres) constituting the plurality of bearing portions of the ball retainer 11 on the movable mold B side are elastically deformed by mutual contact, and the fixed mold A and the movable mold Molds B are positioned relative to each other.

  The positional relationship between the fixed mold A and the movable mold B shown in FIG. 3B is established, and after the molded product is peeled from the fixed mold A, the molded product is released from the movable mold B. For example, by using an ejector device (not shown) of an injection molding device, the movable mirror surface piece 6, the ejector pin 9 disposed on the runner 15, and the push-out member of the center pin 10 disposed on the sprue lock 14 are used as the movable mold B The movement starts in the closing direction (right side in the figure). At this time, the movement of the pushing member by the ejector device may be set to an arbitrary moving speed as long as the molded product is not damaged or deformed.

  Subsequently, the movable holding piece 7 is moved by the ejector device while the movable mold B is moved by the mold moving device of the injection molding device until the fixed mold A and the movable die B in FIG. And extrude to the position where the molded product peels. Thereafter, the movement of the movable mirror piece 6 by the ejector device is stopped. In addition, said distance Lc is smaller than the protrusion amount L of the straight pin 5 of the fixed mold A from the injection mold parting line surface similarly to FIG.3 (b).

  Next, the movable mold B is moved by the mold moving device of the injection molding apparatus until the fixed mold A and the movable mold B in FIG. The molded product is extruded by the center pin 10. Thereafter, the ejector device of the injection molding device is stopped. As the ejector pin 9 and the center pin 10 move, the sprue 13 and the runner 15 of the molded product move, so that the entire molded product is peeled off from the movable mirror piece 6 and the release of the molded product is completed. In addition, said distance Ld is smaller than the protrusion amount L of the straight pin 5 of the fixed mold A from the injection mold parting line surface similarly to FIG.3 (b).

  Thereafter, as shown in FIG. 3E, the movable mold B is sufficiently moved by the mold moving device of the injection molding apparatus, and the fixed mold A and the movable mold B are separated by using the take-out device of the injection molding machine. The molded product is taken out from the mold. At this stage, the portion of the lens (17) of the molded product is continuous with the gate 16, but thereafter, the gate 16 to the runner 15 to the sprue 13 at the boundary portion between the lens (17) and the gate 16 by an appropriate method. Separate the site. As a result, only the optical element, that is, the portion of the lens (17) is obtained as a final molded product.

  According to the injection mold of the present embodiment, the fixed mold A and the movable mold B, in particular, the fixed holding piece 2 and the movable holding piece 7 which are the main parts thereof, include, for example, a ball retainer 11 and a straight pin 5. A fitting structure is provided. For this reason, the relative movement of the fixed mold A and the movable mold B can be restricted in the mold opening direction even during the opening and closing of the mold, especially during the mold opening.

  According to the present embodiment, even immediately after the mold opening is started, even if the molded product including the lens (17) is peeled off from the fixed mold A and the movable mold B, the temperature distribution between the lens surfaces. Can reduce the amount of warping of the molded product and achieve high shape accuracy.

  Further, according to the present embodiment, even after the clamping force between the fixed mold A and the movable mold B is released, the straight pin 5 of the fixed mold A and the ball retainer 11 of the movable mold B are removed. Thus, the relative movement of the fixed mold A and the movable mold B can be restricted in the mold opening direction. In particular, the movement restriction is performed with high precision by the elastic deformation force of a plurality of balls of the ball retainer 11. Accordingly, it is possible to prevent the stationary mold A and the movable mold B from moving or tilting in a direction orthogonal to the mold opening operation direction.

  Accordingly, the relative positional relationship between the fixed mold A and the movable mold B is lost as in the conventional case, and for example, when the molded product is pushed out with the center pin 10 disposed at the sprue lock 14, the molded product sprue. There is no problem that the part (13) touches the fixed mold A. For this reason, for example, the molded product is deformed by the stress when the sprue (13) portion of the molded product touches the fixed mold A, or the portion of the lens (17) of the particularly important molded product is damaged. Can avoid problems.

  In particular, in this embodiment, the straight pin 5 and the movable mirror piece 6 of the fixed mold A are positioned so as to be able to move in and out (sliding) via the ball retainer 11 and the ball retainer 12, respectively, and the movement directions of the two match. . That is, by using a bearing structure such as the ball retainers 11 and 12, it is possible to precisely position the straight pins 5 and the movable mirror piece 6 of the fixed mold A or restrict the moving direction. Therefore, when the mold is opened as described above, or when the molded product is extruded, the molded product is deformed by the stress when the fixed mold A is touched without contacting the sprue 13 of the molded product and the fixed mold A after peeling. Or a problem such as damaging the part of the lens (17) of the molded product can be avoided.

  In order to prevent the movable mold B and the fixed mold A from moving in the direction orthogonal to the mold opening operation direction in the mold opening process, it is necessary to keep a large holding force of the balls of the ball retainer 11. . For this reason, for example, it is conceivable to select a component such that the ball retainer 12 has a larger ball diameter than the ball retainer 11.

  In the above description, different reference numerals are used for the distance Lb, the distance Lc, and the distance Ld, and it is implicitly shown that these distances are different (may be different). That is, in the above, it is considered to perform control such that the ejecting member is moved by the ejector device of the injection molding apparatus while the movable mold B is opened by operating the mold moving device of the injection molding apparatus.

  However, the mold can be controlled in different manners depending on the distance Lb, the distance Lc, and the distance Ld. For example, even when the pushing member is operated by the ejector device of the injection molding device in a state where the distance Lb and the distance Lc are the same and the mold moving device of the injection molding device is stopped, the same effect as described above can be obtained. Needless to say. Similarly, the same effect can be obtained by making the distance Lc and the distance Ld the same, or making the distance Lb, the distance Lc and the distance Ld the same.

  3C, the ejector device of the molding machine is stopped, the movement of the movable mirror piece 6, the ejector pin 9, and the center pin 10 is completed, and the movable mold B is sufficiently opened. Thereafter, the movable mirror piece 6 and the part of the molded lens (17) may be peeled off. Thereby, immediately after the mold opening is started, the molded product can be peeled off from the fixed mold A and the movable holding piece 7, and the flange portion of the lens 17 is rapidly cooled in addition to the fixed lens surface, thereby reducing the warpage amount of the molded product. be able to.

(Variations, etc.)
In the above, the fitting structure by the straight pin 5 of the fixed mold A and the ball retainer 11 of the movable mold B is provided, and the relative movement between the movable mold B and the fixed mold A is (particularly) the direction orthogonal to the mold opening direction. The configuration to restrict is shown. However, the fitting structure that restricts the relative movement of the movable mold B and the fixed mold A by fitting with each other by the concavo-convex structure as described above is limited to the structure shown in FIGS. is not.

  For example, a similar fitting structure for restricting the relative movement of the movable mold B and the fixed mold A can be configured by the straight pin 5 and the cylindrical hole 18 as shown in FIG. 4 (or FIG. 5 described later). In the following description, the same or corresponding members as those described above are denoted by the same reference numerals, and the detailed description thereof will be omitted below.

  The fitting structure of FIG. 4 is configured using a straight pin 5 having a cylindrical cross section as a convex portion and a cylindrical hole 18 as a concave portion. The straight pin 5 in FIG. 4 is integrated with the fixed holding piece 2 in the same manner as described above. The cylindrical hole 18 is directly drilled in the movable holding piece 7 so that the straight pin 5 can be slidably supported (in / out) with a desired dimensional accuracy, for example. Alternatively, the cylindrical hole 18 can also be configured by a method of press-fitting (inserting) a bearing member such as a metal bush instead of the above-described ball retainer 11.

  Even in the structure as shown in FIG. 4, as in the structure using the ball retainer 11 described above, the movable mold B and the fixed mold A move in a direction perpendicular to the intended mold opening direction during the mold opening operation. Can be prevented, and the same effect as described above can be obtained.

  Moreover, the same fitting structure which controls the relative movement of the movable mold B and the fixed mold A is not limited to the structure shown in FIG. 4 (FIG. 5), and for example, various uneven structures can be used. For example, the concavo-convex structure used in the fitting structure may be partially tapered, and may be configured by a combination of a straight pin and a taper hole, a taper pin and a straight hole, or a combination of a taper pin and a taper hole.

  The same fitting structure that restricts the relative movement of the movable mold B and the fixed mold A can provide a certain effect if it is a pair, but the movable mold B and the fixed mold A are different from each other. Needless to say, a larger number of positions can be expected to have a larger effect. When a plurality of fitting structures are provided in the movable mold B and the fixed mold A, for example, self-weight deformation due to the mold mass, temperature rise deformation of the mold, and nozzle deformation due to the nozzle touch force of the molding machine are prevented. It is advisable to select a plurality of arrangement positions so as to be able to do so.

  Moreover, the arrangement positions and the number of the extrusion members arranged on the movable mold B side are not limited to those shown in FIGS. 1 to 4 and can be arbitrarily changed by those skilled in the art. FIG. 5 shows a configuration using a fitting structure with straight pins 5 and cylindrical holes 18 similar to FIG. 4, and a plurality of ejector pins 19 as extrusion members for extruding a molded product (particularly, the portion of the lens (17)). The arrangement is shown. In addition, you may implement the structure which arrange | positions the several ejector pin 19 like FIG. 5 in combination with the fitting structure using the ball retainer demonstrated in FIGS. 1-3 (a)-(e). .

  The configuration in which a plurality of ejector pins 19 are arranged as shown in FIG. 5 can be suitably implemented when the diameter of the flange (flange) around the portion corresponding to the lens (17) of the molded product is large. Further, when a plurality of ejector pins 19 are arranged, the number thereof is arbitrary.

  By operating a plurality of ejector pins 19 as shown in FIG. 5 with an ejector device (not shown) of an injection molding device, the flange (flange) around the portion corresponding to the lens (17) of the molded product is extruded. The lens 17 and the movable mold B can be peeled and released.

  In the configuration of FIG. 5, the diameter of the base (the left portion in the drawing) of the movable mirror piece 6 is configured to be larger than that shown in FIGS. 1 to 4. The plurality of ejector pins 19 are arranged so as to penetrate through the movable die set 8 and the movable mirror piece 6 that is precisely supported by the ball retainer 12. Therefore, the push-out direction of each ejector pin 19 can be precisely regulated, for example, to coincide with the moving direction of the movable mold B via the ball retainer 12 and the movable mirror piece 6. That is, the push-out direction of each ejector pin 19 can be precisely regulated to an intended release direction, and deformation or damage when releasing the lens 17 from the movable mold B can be prevented.

(Specific examples of injection molding)
Here, an example of injection molding of the optical element (resin lens) using the injection mold shown in the above-described embodiment will be specifically shown. In the following, the material of the molded product, dimensions, numerical values related to the movement control of the mold, etc. will be exemplified, but the numerical values shown below are only reference numerical values, and it goes without saying that the present invention is not limited to these numerical values. Absent.

  The molded product molded by the injection mold shown in the above embodiment is a convex lens having a lens diameter of 11 mm, for example. Moreover, COP (cycloolefin polymer) etc. are used for resin of a molding material, for example. Examples of such COP resin for injection molding include products such as ZEONEX (registered trademark). In the case of this type of COP resin for injection molding, the mold temperature managed by the temperature management unit of the injection molding apparatus is set to about 120 ° C., which is lower than the glass transition temperature of the resin.

  When a lens is molded using the movable mold B and the fixed mold A as shown in FIGS. 1 to 5, the mold clamping force applied by the mold moving device of the injection molding apparatus is, for example, about 300 kN.

  Further, for example, in the structure in which the straight pins 5 and the ball retainer 11 are used in the fitting structure between the molds as shown in FIGS. 1 to 3A to 3E, the movable mold B and the fixed mold A are relatively arranged. The ball diameter and deformation amount of the ball retainer 11 are determined according to the position regulation accuracy. For example, in the mold for molding the lens (17) having the above-mentioned diameter, the dimensions of the above-described parts are set so that the 4 mm diameter ball of the ball retainer 11 is elastically deformed by about 10 micrometers by the straight pin 5 and the movable holding piece 7. Establish a relationship. Similarly, the dimensional relationship of the above-mentioned parts is determined so that a ball of 12 mm in diameter of the ball retainer 12 by the movable mirror piece 6 and the movable holding piece 7 is elastically deformed by about 6 micrometers.

  In the resin injection process (step S12 in FIG. 2), for example, the COP resin to be injected by an injection molding apparatus is heated to 270 ° C. to be in a molten state, and is injected through the opening of the sprue bush 4.

  In the cooling step (step S13 in FIG. 2), for example, the resin is cooled in a mold position shown in FIG. 3A while maintaining a mold clamping state in which the pressure on the resin is about 100 MPa by an injection molding apparatus.

  In the mold opening and releasing process, when the movable mold B is moved by the injection molding device at a speed of about 1 mm / s until the distance Lb reaches the position of 1 mm (FIG. 3B), the ejector member pushes the extrusion member. Starts moving at 1 mm / s. At this time, the pushing member to be moved by the ejector device is the movable mirror piece 6, the ejector pin 9, and the center pin 10, which are naturally moved at the same speed.

  Next, when the mold opening distance Lc moves to 2 mm (FIG. 3C), the movement of the movable mirror piece 6 of the pushing member by the ejector device is stopped. On the other hand, the ejector pin 9 and the center pin 10 of the extruded member continue to move at 1 mm / s.

  Further, when the mold opening distance Ld has moved to 5 mm (FIG. 3D), the movement of the ejecting members (ejector pins 9 and center pin 10) by the ejector device is stopped. Then, the movable mold B was moved as it was until the mold opening distance reached 200 mm (FIG. 3E). In this state, a take-out device (not shown) of the injection molding apparatus is entered into the mold, and for example, the part of the sprue 13 is gripped and the molded product is carried out of the mold.

  Note that the specific example described in this section is merely an example of mold control, and as mentioned earlier, depending on the distance Lb, the distance Lc, and the distance Ld, etc. Needless to say, the mold can be opened.

(Comparative example)
Here, in order to show the effect in the above-mentioned embodiment, the mold opening of the conventional structure which does not have a fitting structure between the movable mold B and the fixed mold A is shown in FIGS. Show the state. The mold structure shown in FIGS. 6A to 6C corresponds to a structure obtained by removing the fitting structure (the straight pin 5 and the ball retainer 11) from the structures shown in FIGS. 1 to 3A to 3E. 6 (a) to 6 (c), the same or corresponding members as in FIGS. 1 to 3 (a) to 3 (e) are denoted by the same reference numerals, and detailed description thereof will be omitted below. To do.

  The state of FIG. 6A corresponds to, for example, the mold closed (clamped) state of FIG. 3A described above. The optical elements (resin lenses) to be molded in FIGS. 6A to 6C are the same as described above, and the state after performing the mold closing process, the injection process, and the cooling process as in Example 1 is as shown in FIG. a).

  Next, in the mold opening and mold release process, when the movable mold B is moved to the positional relationship of FIG. 6B where the distance Lb is 1 mm / s and the distance Lb is 1 mm, the ejector device of the injection molding apparatus The extruded member starts moving at 1 mm / s. At this time, the pushing member to be moved by the ejector device is the movable mirror piece 6, the ejector pin 9, and the center pin 10, which are naturally moved at the same speed.

  At this time, in the structure shown in FIGS. 6A to 6C, there is no positioning member for correcting the position and inclination of the fitting member, that is, the fixed holding piece and the movable holding piece. The relative position (or aspect of relative movement) of the mold B may change. For example, the fixed mold A and the movable mold B are moved to M1 and M2 (FIG. 6 (b) to ( c)) may move in the respective directions. Thus, if the intended relative position (or aspect of relative movement) of the fixed mold A and the movable mold B changes, the sprue 13 of the molded product may come into contact with the fixed mold A.

  Thereafter, the movement of the movable mold B is continued, and the ejector pin 9 and the center pin 10 among the extruded members are continuously moved at 1 mm / s. And it moves to FIG.6 (c) which becomes the position where distance Lc is 2 mm. At this time, if the intended relative position (or the mode of relative movement) of the fixed mold A and the movable mold B is changed, the molded product comes into contact with the fixed mold A at the site of the sprue 13 or contacts. Will continue to do. The direction of the stress applied to the molded product by this contact is naturally not coincident with the mold opening direction or the mold releasing direction that coincides with the mold opening direction. For example, this stress causes the lens (17) of the molded product and the movable mirror piece 6 to move. The lens surface may peel off. Thereby, there is a high possibility that the part of the lens (17), which is an important part of the molded product, is deformed or damaged.

  As described above, in the mold opening in the conventional structure that does not have a fitting structure between the movable mold B and the fixed mold A, the relative displacement (relative movement) between the fixed mold A and the movable mold B is unexpected. An error may occur. Then, for example, the fixed mold A and a portion of the molded product, for example, the sprue 13 are in contact with each other, and the molded product is released in an unexpected direction due to the stress. There is a possibility that the part 17) may be deformed or damaged.

  On the other hand, for example, in the injection mold shown in the embodiment of FIGS. 1 to 5, a fitting structure is provided between the movable mold B and the fixed mold A as described above. For this reason, during mold opening operation or mold release, the relative position or relative movement between the movable mold B and the fixed mold A is surely restricted, and the optical element that is the molded product can be prevented from being damaged. is there.

  DESCRIPTION OF SYMBOLS 1 ... Fixed mirror surface piece, 2 ... Fixed holding piece, 5 ... Straight pin, 6 ... Movable mirror surface piece, 7 ... Movable holding piece, 9 ... Ejector pin, 10 ... Center pin, 11, 12 ... Ball retainer.

Claims (11)

Injection mold including a first mold including an extruding member, a holding member for holding the extruding member, and a second mold defining a cavity for molding an optical element between the extruding member In the mold,
A fitting that restricts relative movement of the holding member and the second mold in a direction perpendicular to the mold opening direction by fitting the holding member and the second mold so as to be able to protrude and retract from each other by an uneven structure. Each structure is provided,
2. The injection mold according to claim 1, wherein the fitting structure is configured to maintain a fitting state with each other at a timing when the optical element is released from the second mold.   2. The injection mold according to claim 1, wherein the fitting structure is configured to maintain a fitting state with each other at a timing at which the optical element is released from the pushing member.   The injection mold according to claim 1 or 2, wherein a plurality of the fitting structures are provided at different positions of the holding member and the second mold.   The extrusion member is a mirror piece having a transfer surface for forming the optical element, and the holding member is a holding piece for holding the mirror piece. The injection mold according to item.   5. The injection mold according to claim 1, wherein the first mold is a movable mold, and the second mold is a fixed mold. 6.   5. The injection mold according to claim 1, wherein the first mold is a fixed mold, and the second mold is a movable mold. 6.   The injection mold according to any one of claims 1 to 6, wherein the fitting structure is configured by a rolling bearing and a straight pin that fits freely into and out of the rolling bearing.   The injection mold according to any one of claims 1 to 7, wherein the movable support mechanism for moving and supporting the push-out member includes a rolling bearing.   An optical element manufacturing apparatus, wherein an optical element is injection molded using the injection mold according to any one of claims 1 to 8.   An optical element manufacturing method, wherein an optical element is injection molded using the injection mold according to claim 1.   An optical element that is injection-molded by using the injection mold according to claim 1.

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