JP2012210810A - Injection molding die, resin molded product, and method for producing resin molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding die having a size appropriate for a molded product and a simple structure, and whereby even if the molded product has an undercut portion, a number of molded products can be obtained, and to provide a resin molded product, produced by using the die, and a method for producing a resin molded product using the die.SOLUTION: An injection molding die 1 comprises a stationary die, a movable die 3, and a slide core 4, and is the die used for obtaining a number of resin molded products having hollow portions. There is one parting line between the stationary die and the movable die 3, and a molding cavity of the injection molding die is divided in series in the movable direction of the movable die by the slide core 4 to form a plurality of cavities. The injection molding die has a core pin 5 for forming the hollow portion of the molded product, and a submarine gate 6 for filling each molding cavity with the resin is formed on the core pin 5.

Description

  The present invention relates to a synthetic resin product injection mold, a resin molded product, and a method for producing a resin molded product that can be obtained in large numbers.

  As a means for producing a product made of a synthetic resin, a production method by injection molding is generally performed. Injection molding can be easily mass-produced by an injection mold even when a product having a complicated shape is manufactured. Generally, an injection mold is composed of a fixed mold (a fixed mold) and a movable mold (movable mold) that can be clamped and opened with respect to the fixed mold. A molded product corresponding to the shape of the molding cavity is molded by injecting and filling molten resin into a molding cavity formed by the fixed mold and the movable mold that are clamped and solidified.

  In an injection mold, by providing a plurality of molding cavities in one injection mold, it is possible to simultaneously manufacture a plurality of molded products in a single molding process. In such a multi-cavity injection mold, molding cavities are usually arranged in parallel on a mating surface (parting line (hereinafter referred to as PL)) of a fixed mold and a movable mold.

  Further, as an injection mold for simultaneously producing more molded products, a stack mold mold is known in which a plurality of movable molds are stacked and a molding cavity is formed in each movable mold (see Patent Document 1). .

  In addition, as a multi-piece injection mold when the molded product has an undercut part (a shape part that cannot be removed by simply opening the mold), the slide cores are arranged in a row of molding cavities so that the slide cores do not interfere with each other. An injection mold that is arranged at an angle with respect to the direction is known (see Patent Document 2).

  In addition, a plurality of annular movable molds arranged in series in the axial direction of the core rod-shaped fixed mold are provided so that the movable mold can be detachably connected to the fixed mold in the radial direction. An injection mold having a plurality of slide cores and runner slide cores disposed on the outer peripheral side of the fixed mold is known (see Patent Document 3).

JP 2001-129640 A JP 2002-234059 A Japanese Patent Laying-Open No. 2005-225032

  However, although the injection mold disclosed in Patent Document 1 can take a large number of molded products, the molten resin flow rate (sprue, runner) becomes long, so the cooling rate of the molten resin increases. . Therefore, it is limited to the application in a thin molded product in which defects such as sink marks are unlikely to occur, and it is difficult to apply to a molded product having a complicated shape.

  The injection mold disclosed in Patent Document 2 can take a large number of molded products, but requires a plurality of sets of slide cores, which complicates the mold structure as a whole. For this reason, the manufacturing cost of a metal mold | die is large. In addition, since the mold cavities have a parallel structure and the slide core structure is also complicated, the mold itself is larger than a single-piece injection mold.

  In addition, since the injection mold disclosed in Patent Document 3 has a gate formed on the slide core, the molten resin flow path has a complicated structure, and the mold itself becomes large.

  The present invention has been made to cope with such problems, and even when the molded product has an undercut portion, a large number of molded products can be obtained, and the size is suitable for the molded product. It is an object of the present invention to provide an injection mold having a simple structure, a resin molded product manufactured using the mold, and a method for manufacturing a resin molded product using the mold.

  An injection mold of the present invention is an injection mold for taking a large number of resin molded products having a movable part, a fixed mold, and a slide core, and having a hollow portion, the fixed mold and the movable mold. A core pin that has a single PL and a plurality of molding cavities in the injection mold divided by the slide core in series in the movable direction of the movable mold to form a hollow portion of the molded product And a submarine gate for filling each molding cavity with resin is formed on the core pin.

  A plurality of the molding cavities are formed in series in the movable direction of the movable mold by convex portions provided in the movable direction of the slide core and in contact with the core pin.

  The slide core is configured to move radially about the molding cavity when the PL of the fixed mold and the movable mold is viewed from the front of the cavity. Further, the slide core is one set.

  A convex part and / or a concave part are provided on the inner side in the movable direction of the slide core.

  The resin molded product of the present invention is manufactured using the injection mold of the present invention. Moreover, the surface of the said molded article has a hole, a hollow, or a processus | protrusion, It is characterized by the above-mentioned.

  The method for producing a resin molded product of the present invention is a method of simultaneously producing a plurality of resin molded products having hollow portions using the injection mold of the present invention, wherein the fixed mold and the movable mold are collided with each other. A step of injecting and filling resin through the submarine gate into the plurality of molding cavities divided by the slide core in a combined state, and after the resin is solidified, the movable mold is opened and the slide core is movable And a step of taking out a plurality of resin molded products in the shape of a molding cavity in which the core pin portion is a hollow portion.

  The step of taking out is characterized in that it is a step of taking out all of the plurality of resin molded products by protruding the end face of one resin molded product with a protruding pin. Further, the resin molded product after taking out is not post-processed.

  The injection mold of the present invention has a movable mold, a fixed mold, and a slide core, and the fixed mold and the movable mold have a single PL, and the molding cavity in the injection mold is a movable movable mold. Since a plurality of core pins are formed by being divided by a slide core in series in the direction, forming a hollow part of a molded product, and a submarine gate for filling a resin into each molding cavity is formed on the core pin, Although it is a multi-cavity mold, the size of the injection mold (vertical and horizontal dimensions) can be made the same as that of a single-cavity injection mold without forming molding cavities in parallel. It can be sized appropriately. Moreover, since there is only one PL, the mold opening structure of the mold can be simplified. Furthermore, since the gate is a submarine gate formed on the core pin that forms the hollow part, the flow path of the molten resin can be made simple, and compared with the case where the gate is formed on the slide core, injection molding It is possible to simplify the mold and avoid an increase in the size of the mold.

  A plurality of the molding cavities are formed in series in the movable direction of the movable mold by convex portions provided in the movable direction inner side of the slide core and in contact with the core pin. A plurality of molded products can be formed with a simple structure to be used.

  Since the molding cavity is formed in a plurality in series in the movable direction of the movable mold, the slide core is centered on the molding cavity when the PL of the fixed mold and the movable mold is viewed from the front of the cavity. Even in the case of a radially movable structure, the mold structure does not become complicated.

  Since only one set of the slide core is used, the mold structure is not complicated and a plurality of molded products can be manufactured. Moreover, the enlargement of a metal mold | die can be avoided.

  Since the convex portion and / or the concave portion are provided on the inner side in the movable direction of the slide core, it is possible to manufacture a resin molded product having a hole, a depression, or a projection serving as an undercut portion by the convex portion or concave portion. Become

  The method for producing a resin molded product of the present invention is a method for simultaneously producing a plurality of resin molded products having hollow portions using the above injection mold, and slides in a state where the fixed die and the movable die are brought into contact with each other. A step of injecting and filling a resin through a submarine gate into a plurality of molding cavities divided by the core, and after the resin is solidified, the movable mold is opened and the slide core is moved so that the core pin portion is a hollow portion. And a step of taking out a plurality of resin molded products in the shape of a molding cavity, so that a plurality of molded products can be obtained simultaneously by one set of slide cores, without using a complicated structure injection mold, and It can be manufactured with a small injection mold, and the manufacturing cost can be kept low.

  In addition, the step of taking out is a step of taking out all of the plurality of resin molded products by projecting the end face of one resin molded product with a projecting pin, so that the molded product can be easily taken out and the projecting structure can be simplified. .

  Moreover, since the gate cut and the division of the molded product are performed by injection molding, post-processing of the molded resin molded product can be made unnecessary.

  Since the resin molded product of the present invention is manufactured using the injection mold described above, a plurality of the resin molded products can be obtained simultaneously, and the manufacturing cost can be kept low. Moreover, a hole, a hollow, or a protrusion can be easily formed on the surface of the resin molded product.

It is a figure which shows an example of the injection mold of this invention, and is an axial direction side view which shows the state which the slide core opened radially after shaping | molding and the molded article (bearing cage) appeared. It is a figure which shows an example of the injection mold of this invention, and is a perspective view which shows the state which protruded the molded article with the protrusion pin. FIG. 3 is a single perspective view of the slide core in FIGS. 1 and 2. It is an expansion perspective view of the core pin periphery in FIG. It is sectional drawing which shows each process in the manufacturing method of the resin molded product of this invention.

  An embodiment of an injection mold according to the present invention will be described with reference to FIGS. FIG. 1 is an axial side view showing a state in which a slide core is opened radially after molding and a molded product appears, and FIG. 2 is a perspective view showing a state in which the molded product is protruded by a protruding pin. As shown in FIGS. 1 and 2, the injection mold 1 of the present invention has a fixed mold 2, a movable mold 3, and a plurality of slide cores 4. A core pin 5 is provided on the movable mold 3 side, and a submarine gate 6 for filling a molding cavity with resin is provided inside the core pin 5. The core pin 5 forms a hollow part of the molded product. The core pin 5 has a cylindrical shape whose axial direction is the movable direction of the movable mold 3 (arrow in FIG. 1), and is formed at the center of the molding cavity in the axial direction. There is one PL8 which is an abutting surface between the movable mold 3 and the fixed mold 2. Since there is only one PL, the mold opening structure of the mold can be simplified. A plurality of protruding pins 7 are provided around the core pin 5 on the movable mold 3 side. In addition, the resin molded product 9 in FIG. 1 is a cage for a needle bearing which is a radial bearing.

  In the injection mold 1, a plurality (two) of molding cavities are formed in series in the movable direction of the movable mold 3. The plurality of molding cavities are formed by being divided in series in the movable direction of the movable mold 3 by the slide core 4 in a state where the fixed mold 2 and the movable mold 3 are abutted. The plurality of molding cavities are all formed on the movable mold 3 side. With the plurality of molding cavities, a plurality of resin molded products can be molded simultaneously, and a large number of molded products can be obtained. By forming the molding cavities in series in the movable direction of the movable mold 3, the size of the injection mold (vertical and horizontal dimensions as viewed from the front of the cavity) can be made the same as that of the single injection mold.

  The slide core 4 moves radially around the molding cavity when the PL 8 of the fixed mold 2 and the movable mold 3 is viewed from the front of the cavity (in the core pin axis direction). Here, when the slide core 4 is radially movable, when the PL 8 of the fixed mold 2 and the movable mold 3 is viewed from the front of the cavity, each of the plurality of slide cores 4 is centered on the molding cavity. It is movable in an arbitrary circumferential angle direction and is movable so as to spread radially (concentrically) in the entire circumference (360 °) as the entire slide core 4. In FIGS. 1 and 2, only two slide cores 4 are shown for simplicity, but in an actual aspect, the slide cores 4 are arranged in all the concave portions 3 a of the movable mold 3. At the time of mold clamping, the core pin 5 is abutted to cover the entire circumference without any gaps. In addition, the joint of the adjacent slide core 4 becomes a slide core parting line (SPL).

  FIG. 3 shows a single perspective view of the slide core 4. The slide core 4 has a convex portion 4a provided on the inner end surface in the movable direction and in contact with the core pin. Here, the inside in the movable direction refers to the opposite side of the circumferential angle direction in which each slide core 4 is movable. The convex portion 4a is formed over the entire width W in the circumferential direction of the slide core on the end surface 4b on the inner side in the movable direction of each slide core 4. In addition, the axial direction length L of the convex part 4a is set to arbitrary lengths, and this length L becomes the distance between molding cavities. Since the slide core 4 is formed in a plurality (one set) so as to cover the circumferential direction without a gap, the projecting portion 4a is formed on the end surface on the inner side in the movable direction of each slide core 4 with the full width W in the circumferential direction of the slide core 4. By being formed over, when the mold is clamped, the projecting portions 4a of the slide core 4 are connected in the circumferential direction so that the entire circumference of a part of the core pin 5 in the axial direction is in contact with and covered. By the convex portions 4a connected in the circumferential direction, the molding cavity is formed in two in series in the movable direction of the movable die 3 (core pin axial direction).

  The shape and number of other parts of the slide core 4 can be arbitrarily selected as long as the slide core 4 is shaped so as to abut against the core pin at the time of clamping and cover the entire circumference without gaps. The slide core 4 is composed of one set composed of a plurality of movable cores that can be moved simultaneously or interlocked. As shown in this embodiment, in the slide core 4, all the slide cores 4 may have the same shape, and the slide cores may have different shapes. The injection molding die 1 of the present invention can form a plurality of resin molded products simultaneously with one set of slide cores 4 while providing a plurality of molding cavities by providing convex portions 4a, etc. Is no longer necessary. By making the slide core 4 into one set, the mold structure is not complicated.

  The slide core 4 can be provided with a convex portion and / or a concave portion for forming a hole, a depression, or a protrusion on the surface of the molded product in addition to the convex portion 4a on the end surface on the inner side in the movable direction. As shown in FIG. 3, in this embodiment, in order to form a plurality of elongated holes on the surface of the molded product, a convex portion 4 c is formed on the end surface 4 b on the inner side in the movable direction of each slide core 4. Since one convex hole is formed on the surface of the molded product by one convex portion 4c, a long hole corresponding to the number of slide cores 4 is formed in one molded product. In a resin molded product, holes, dents, and protrusions on the surface of the molded product that are formed in a direction perpendicular to the protruding direction, etc., become undercut portions. In the injection mold of the present invention, this portion is the above-mentioned slide. The core 4 can be easily formed. For this reason, the injection mold of this invention can be utilized suitably also for manufacture of the resin molded product which has a hole, a hollow, or a processus | protrusion on the surface.

  FIG. 4 shows an enlarged perspective view around the core pin. In FIG. 4, a part of the slide core is omitted. As shown in FIG. 4, the core pin 5 has a submarine gate 6 for filling a molding cavity with resin therein. The submarine gates 6 are formed at least as many as the number of molding cavities. In this embodiment, since there are two molding cavities, two submarine gates 6 are formed on the core pin 5. If necessary, a plurality of gates may be provided for one molding cavity. In the injection mold according to the present invention, since the molding cavities are formed in series in the axial direction along the core pin 5, the submarine gate 6 can be formed inside the core pin 5. By forming the submarine gate 6 inside the core pin 5 forming the hollow part of the resin molded product, the flow path of the molten resin can be made simple, and compared with the case where the gate is formed on the slide core, injection The molding die can be simplified and the enlargement of the die can be avoided.

  The shape of each submarine gate 6 is not particularly limited, but it is preferable that each molding cavity connected to the gate has a shape with an excellent filling balance so that the resin is simultaneously filled in each molding cavity. For example, in order to minimize the difference in flow path length of molten resin (difference in gate length), the gate provided in the molding cavity far from PL is formed at a position close to PL of the molding cavity. The gate provided in the molding cavity close to the eye can be formed at a position far from the PL of the molding cavity. If the gate length is different, the filling balance can be improved by adjusting the cross-sectional area. By making the submarine gate into a shape with an excellent resin filling balance between the molding cavities, it is possible to eliminate quality variations among resin molded products molded simultaneously in the molding cavities.

  Using the injection mold of the present invention, a resin molded product can be molded using the resin composition as a material. The kind of the resin composition used as the material can be arbitrarily determined according to the required characteristics of the resin molded product. Examples of the synthetic resin used as the base resin of the resin composition include polyamide 6 (PA6) resin, polyamide 6-6 (PA66) resin, polyamide 6-10 (PA610) resin, polyamide 6-12 (PA612) resin, Polyamide (PA) resin such as polyamide 4-6 (PA46) resin, polyamide 9-T (PA9T) resin, polyamide 6-T (PA6T) resin, polymetaxylene adipamide (polyamide MXD-6) resin, polytetra Fluoropolymers that can be injection molded such as fluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) resin, tetrafluoroethylene / hexafluoropropylene copolymer (FEP) resin, ethylene-tetrafluoroethylene copolymer (ETFE) resin , Polycarbonate (PC) resin, polyace (POM) resin, wholly aromatic polyester resin, polyphenylene sulfide (PPS) resin, polyether ether ketone (PEEK) resin, polyamideimide (PAI) resin, polyetherimide (PEI) resin, injection moldable polyimide ( PI) resin. In each polyamide resin, a number represents the number of carbon atoms between amide bonds, and T represents a terephthalic acid residue. Each of these synthetic resins may be used alone or may be a polymer alloy in which two or more kinds are mixed.

  Among these synthetic resins, it is preferable to use a polyamide (PA) resin because it is excellent in injection moldability and can be easily molded even with the above-described submarine gate. In addition, in order to improve the mechanical strength of resin molded products, glass fibers, aramid fibers, carbon fibers, various mineral fibers (whiskers), etc. are blended with these resin compositions as long as they do not impair injection moldability. May be. Furthermore, in order to improve the slidability of the resin molded product, a solid lubricant such as polytetrafluoroethylene resin powder, graphite, or molybdenum disulfide may be blended. In addition, you may mix | blend another well-known additive as needed.

  Although the case where the number of molding cavities is two has been described based on each drawing, it can be divided into a larger number depending on the shape of the resin molded product, the type of resin, and the like. In the case of dividing into a larger number, it is possible to increase the number of convex portions 4a provided on the end face on the inner side in the movable direction in the slide core 4 and provide the submarine gate 6 in each molding cavity.

  The manufacturing method of the resin molded product of this invention is demonstrated based on FIG. FIG. 5 is a cross-sectional view showing the steps in the production method of the present invention. In addition, the resin molded product 9 in FIG. 5 is a cage for a needle bearing which is a radial bearing. The production method of the present invention is a production method for simultaneously producing a plurality of resin molded products having hollow portions using the above injection mold.

  First, there is a step of injecting and filling resin through a submarine gate 6 into a plurality of molding cavities divided by the slide core 4 in a state where the fixed mold 2 and the movable mold 3 are abutted (FIGS. 5A and 5B). )). Note that a passage of molten resin material (not shown) is formed in the fixed mold 2 up to the submarine gate 6.

  Next, after the resin in the molding cavity is solidified through the pressure holding process and the cooling process, the movable mold 3 is moved from the abutting state with the fixed mold 2 to the opposite side to the fixed mold 2 and opened, and the slide core 4 is moved, and a plurality of resin molded products 9 molded in the molding cavity are taken out (FIGS. 5C and 5D). In this process, the slide core 4 is movably opened so as to spread radially as a whole of the slide core 4 when the PL of the fixed mold 2 and the movable mold 3 is viewed from the front of the cavity (FIGS. 1, 2 and the like). reference). The mold, slide core, and ejector pin are moved by driving means such as a hydraulic cylinder (not shown).

  The resin molded product 9 is taken out by protruding from the molding cavity with the protruding pin 7 provided around the core pin 5 on the movable mold 3 side (FIG. 5D). By projecting the end face of one resin molded product with the projecting pin 7, this resin molded product can extrude another resin molded product, and all of the plurality of resin molded products 9 can be taken out. For this reason, except for the resin molded product that comes into contact with the protruding pin 7, no protruding pin marks remain on the molded product. Although not shown, the resin in the submarine gate 6 is taken out by a protruding pin provided inside the core pin 5 that operates in conjunction with the protruding pin 7.

  Since the plurality of resin molded products 9 are independently molded in the molding cavity divided by the slide core 4, if the slide core 4 is moved and the mold is opened, it is obtained in a mutually divided state (FIG. 5 ( c)). Further, when the resin molded product 9 is protruded, the resin molded product 9 and the submarine gate 6 are cut at the connecting surface (surface position of the core pin 5). As described above, in the manufacturing method using the injection mold of the present invention, the gate cut and the resin molded product are divided by the injection molding, so that the post-processing of the resin molded product such as the division of the molded product and the gate treatment is performed. It can be made unnecessary.

  The resin molded product of the present invention is manufactured using the above injection mold, and is a molded product having a hollow portion. Since the resin molded product is manufactured using the injection mold, a plurality of the resin molded products can be obtained simultaneously, and the manufacturing cost can be kept low. In addition, a resin molded product having a complicated structure having holes, depressions, or protrusions on the surface is also a suitable target molded product of the present invention. Examples of the resin molded product of the present invention include a cage for a radial bearing (roller bearing or ball bearing), a radial bearing body (sliding bearing), a seal ring, and the like. Among these, a cage for a radial bearing (roller bearing or ball bearing) having a hole serving as an undercut portion on the surface is a preferable molded product in the present invention.

  The injection mold according to the present invention can take a large number of molded products even when the molded product has an undercut portion, and has a simple structure with a size suitable for the molded product. It can utilize suitably for manufacture of the resin molded product which has a part. In particular, it can be suitably used for the production of a resin molded product having a complicated structure, which has been difficult to obtain in the past and has irregularities such as holes, dents, or protrusions on the surface.

DESCRIPTION OF SYMBOLS 1 Injection mold 2 Fixed type 3 Movable type 3a Concave part 4 Slide core 4a Convex part 4b End surface 4c Convex part 5 Core pin 6 Submarine gate 7 Extrusion pin 8 Parting line (PL)
9 Plastic molded products

Claims (10)

An injection mold for taking a large number of resin molded products having a movable mold, a fixed mold and a slide core, and having a hollow part,
There is one parting line between the fixed mold and the movable mold, and a plurality of molding cavities in the injection mold are formed by being divided by the slide core in series in the movable direction of the movable mold,
An injection mold having a core pin that forms a hollow part of the molded product, and a submarine gate for filling the molding cavity with a resin is formed on the core pin.   2. The plurality of molding cavities are formed in series in the movable direction of the movable mold by a convex portion that is provided inside the movable direction of the slide core and contacts the core pin. The injection mold described.   3. The slide core according to claim 1, wherein the slide core moves radially around the molding cavity when a parting line between the fixed mold and the movable mold is viewed from the front of the cavity. Injection mold.   The injection mold according to claim 1, 2 or 3, wherein the slide core is one set.   The injection mold according to any one of claims 1 to 4, wherein a convex portion and / or a concave portion are provided on an inner side in the movable direction of the slide core.   A resin molded product having a hollow part, which is manufactured using the injection mold according to any one of claims 1 to 5.   The resin molded product according to claim 6, wherein a surface of the molded product has a hole, a depression, or a protrusion. A manufacturing method for simultaneously manufacturing a plurality of resin molded products having hollow portions using the injection mold according to any one of claims 1 to 5,
A step of injecting and filling resin through the submarine gate into the plurality of molding cavities divided by the slide core in a state where the fixed mold and the movable mold are abutted;
A step of opening the movable mold after the resin is solidified, moving the slide core, and taking out a plurality of resin molded products in the shape of the molding cavity in which the core pin portion is a hollow portion. A method for producing a resin molded product characterized by the above.   The method of manufacturing a resin molded product according to claim 8, wherein the step of taking out is a step of taking out all of the plurality of resin molded products by projecting an end face of one resin molded product with a projecting pin.   The method for producing a resin molded product according to claim 8 or 9, wherein the resin molded product after removal is not post-processed.

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