JP2009262418A - Mold device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold device capable of being inexpensively manufactured, and having excellent durability and molding an undercut part without inhibiting design flexibility of a molded product. <P>SOLUTION: A core insert member 17 which is elastically deformable to a second mold 14 side is projectingly provided in a molding space 15 by utilizing a clearance between the molds 13, 14 formed in a first mold 13 having an ejector pin 16 of the first mold 13 and the second mold 14 to be mounted when both the molds 13, 14 are opened. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mold apparatus suitable for molding a molded article having an undercut portion.

  As a molding method of a molded product having an undercut portion, a method of molding the undercut portion using a special undercut processing structure of an inclined core, a slide core, a collapsible core, and a placing core that can be projected and retracted in a molding space (for example, Patent Document 1) and a method of forcibly removing the undercut portion using elastic deformation of the molded product (for example, see Patent Document 2) are widely adopted.

  In the former method, the mold structure becomes complicated and the manufacturing cost of the mold apparatus increases, and malfunctions may occur due to wear of the sliding part in the undercut processing structure or galling on the mold. It was. In addition, when the entire peripheral groove is formed on the inner peripheral surface or outer peripheral surface of the cylinder, the slide core or the like becomes a split mold, so that a step or a convex portion is formed on the molded product at the mating part of the mold. There was a problem in function. On the other hand, in the latter method, there is no problem of steps or protrusions, but because the undercut part is forcibly removed while deforming, the molded product may be deformed or damaged, and the material of the molded product or There is a problem that the degree of freedom of design with respect to thickness and the like is greatly restricted.

  Therefore, as a molding method other than the above for a molded product having an undercut portion, a method of molding the undercut portion using a tube that can expand and contract in the molding space by taking in and out of air (for example, see Patent Document 3). In addition, a method of forming an undercut portion using a rubber-like elastic body that is elastically deformed into a forming space when the die is closed (see, for example, Patent Document 4) has been proposed.

JP 2007-144755 A JP 2003-39508 A JP 2006-240191 A JP-A-2-258218

  In the methods described in Patent Documents 3 and 4, since there is no need to use a split mold, steps and protrusions are not formed on the molded product, but there are the following problems.

  That is, in the method described in Patent Document 3, a mechanism for taking air in and out of the tube is necessary, the tube is deformed by the resin pressure in the molding space, and the molding accuracy of the molded product is reduced. There's a problem.

  Further, in the method described in Patent Document 4, since the undercut portion is formed by projecting and deforming the rubber-like elastic body into the molding space using the mold closing operation, a mechanism for taking in and out air can be omitted. However, similarly to the method described in Patent Document 3, there is a problem that the rubber-like elastic body is deformed by the resin pressure in the molding space and the molding accuracy of the molded product is lowered.

  An object of the present invention is to provide a mold apparatus that can be manufactured at low cost, has excellent durability, and can mold an undercut portion without impairing the design freedom of a molded product.

  The mold apparatus according to the present invention has a gap between the molds formed when the molds are opened on the first mold to which the ejector pins of the first mold and the second mold are attached. Utilizing this, a nesting member that can be elastically deformed toward the second mold side is provided so as to protrude into the molding space.

  In this mold apparatus, a molded product is molded in the molding space in a state where the tip of the insert member protrudes into the molding space formed by the first mold and the second mold. By arranging the child member in the middle part of the molded product, the undercut part can be formed on the inner surface side or outer surface side of the middle part of the molded product by the nested member. For example, when forming a cylindrical molded product, a groove-shaped undercut portion is formed on the outer peripheral surface of the middle portion in the center line direction of the molded product by the insert member, or in the middle direction of the molded product in the center line direction. A groove-like undercut portion can be formed on the inner peripheral surface of the portion. On the other hand, when releasing the molded product, the molded product is pushed out to the second mold side by the ejector pin in a state where the mold is opened. At this time, the nesting member is moved to the second mold side. Since it slips out from the undercut portion of the molded product while elastically deforming, the molded product can be released without applying an excessive force to the undercut portion. In this way, the structure of the mold apparatus becomes complicated by the simple structure in which the first mold is provided with the nesting member made of an elastic body that can be elastically deformed toward the second mold side, or the mold apparatus is manufactured. A mold apparatus capable of forming an undercut portion while preventing an increase in cost can be realized. In addition, when the molded product is released, the insert member is elastically deformed so that the molded product can be released and no excessive force acts on the undercut portion of the molded product. The degree of freedom in design with respect to shape and thickness can be greatly expanded.

  Here, the mold is a mold for molding a cylindrical or columnar molded product, and is formed on at least one of the inner peripheral surface and the outer peripheral surface of the middle part in the center line direction of the molded product by the insert member. Forming the groove is a preferred embodiment. In the mold apparatus according to the present invention, molded products having various shapes having an undercut portion can be formed. Cylindrical and columnar molded products having grooves on the inner and outer peripheral surfaces are widely used as sleeves and bushes. The mold apparatus according to the present invention can be used to efficiently and accurately mold these molded products. In particular, the mold apparatus according to the present invention can be suitably used as a mold apparatus for forming a molded product having an annular groove extending in the circumferential direction on the inner peripheral surface or outer peripheral surface of the molded product.

  It is also preferable to provide a fixing member for fixing the nesting member to the first mold, and to form a chamfered surface made of an arc surface or an inclined surface at the tip edge of the fixing surface on the nesting member side of the fixing member. It is. That is, when the nesting member is elastically deformed, the nesting member is press-contacted to the edge edge of the fixing surface of the fixing member on the nesting member side, and stress concentration occurs in the nesting member at the press-contacting point. In the present invention, by forming a chamfered surface on the fixing member, stress concentration at the contact point can be reduced and damage to the nested member can be prevented.

  It is also a preferred embodiment to form a molding portion that protrudes into the molding space of the telescopic member into a semicircular cross section. In other words, the angle formed by the nesting member with respect to the molded product changes with the elastic deformation of the nesting member toward the second mold side. However, as in the present invention, the molding space of the nesting member is changed. If the molded part protruding inward is formed in a semicircular cross section, the angle of the nested member with respect to the molded product can change smoothly around the center of this semicircle, so the tip of the nested member is undercut of the molded product It is possible to smoothly remove the molded product from the part, and the releasability of the molded product can be further improved.

  The nesting member has a higher elastic limit compared to a metal material such as a leaf spring, and has a low elastic modulus. It is preferably composed of a synthetic resin material or a rubber material, and a synthetic resin material or a rubber material such as a fluororesin, a polyacetal resin, a polyamide resin, a polyether ether ketone resin, a nitrile rubber, a chloroprene rubber, or a fluororubber can be suitably used. .

  In a preferred embodiment, the mold is a mold for plastic injection molding. However, the present invention can be similarly applied to powder molds and cast molds in addition to injection molds.

  According to the mold apparatus according to the present invention, the structure of the mold apparatus becomes complicated with a simple structure in which the first mold is provided with an insert member made of an elastic body that can be elastically deformed toward the second mold side. In addition, it is possible to realize a mold apparatus capable of forming an undercut portion while preventing an increase in the manufacturing cost of the mold apparatus. In addition, when the molded product is released, the insert member is elastically deformed so that the molded product can be released and no excessive force acts on the undercut portion of the molded product. The degree of freedom in design with respect to shape and thickness can be greatly expanded.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a molded product that can be molded by the mold apparatus according to the present invention will be described.
In the mold apparatus according to the present invention, it is possible to form molded products having various shapes in which grooves and recesses are formed as undercut portions on the inner surface side and the outer surface side in the middle of the mold opening and closing direction. For example, FIG. Like a molded product 1A shown in FIG. 1B, a cylindrical molded product having a through hole 3A in which an annular groove 2A is formed on the inner peripheral surface as an undercut portion, or a molded product 1B shown in FIG. A cylindrical molded product having a through-hole 3B in which an annular groove 2B is formed on the outer peripheral surface, a molded product in which an annular groove is formed on the inner peripheral surface and the outer peripheral surface, although not shown, and FIG. As in the molded product 1C shown in c), a cylindrical molded product having a through-hole 3C in which an arc-shaped groove 2C is formed in the inner circumferential surface with a circumferential interval, as shown in FIG. Like the molded product 1D, it has a through hole 3D in which an annular groove 2D is formed on the outer peripheral surface. And shaped piece, as moldings 1E shown in FIG. 1 (e), and the like rectangular molded article having a through hole 3E on the inner peripheral surface to form a groove 2E annular suitably shaped.

  Next, the configuration of an example of the mold apparatus according to the present invention will be described with reference to a mold apparatus for forming the molded product 1A shown in FIG.

  As shown in FIGS. 2 and 3, the mold apparatus 10 is an injection mold apparatus, and includes a first mold 13 having a mold plate 11 and a core 12 fixed thereto, and a first mold. 13 and a plurality of ejector pins 16 provided in the first mold 13 so as to be able to move in and out in a molding space 15 formed by combining the two molds 13 and 14, and the tip part is molded. A nesting member 17 fixed on the first mold 13 so as to protrude into the space 15, and a gap between the molds 13, 14 formed when both the molds 13, 14 are opened. Utilizing this, as shown in FIG. 5, a nesting member 17 made of an elastic body that can be elastically deformed toward the second mold 14 is provided.

  The nesting member 17 is formed of a ring-shaped plate member having a constant width, and a molding part 17 a having a semicircular cross section that protrudes into the molding space 15 is formed on the outer periphery of the nesting member 17. A mounting portion 17b to the first mold 13 is formed on the inner peripheral portion of the first mold 13. The nesting member 17 is fixed to the first mold 13 at the mounting portion 17b, and is arranged substantially horizontally as shown by a solid line in FIGS. 2 and 4 except when the molded product 1A is released. The molding portion 17a is held in a molding posture protruding into the molding space 15. However, when the molded product 1A is released, as shown by a solid line in FIG. So that the portion other than the mounting portion 17b is elastically deformed in a curved shape toward the second mold 14 and is elastically deformed into a releasing posture in which the molded portion 17a is detached from the groove portion 2A of the molded product 1A. It is configured.

  The fixing structure of the nesting member 17 with respect to the first mold 13 will be described. A small-diameter portion 12a to which the nesting member 17 can be fitted is formed at the upper end portion of the core 12, and an annular shape is formed in the vicinity of the upper end of the core 12. A receiving surface 12b is formed. A substantially disk-shaped fixing member 18 is detachably fixed to the upper end portion of the core 12 via a screw member 19, and a fixing surface 18 a for fixing and holding the telescopic member 17 is provided on the outer peripheral portion of the fixing member 18. A ring-shaped fixing portion 18b at the lower end is formed so as to protrude downward. When the telescopic member 17 is fixed to the first mold 13, the fixing member 18 is fixed to the core 12 in a state where the telescopic member 17 is externally fitted to the small diameter portion 12 a, and The mounting portion 17b of the telescopic member 17 is sandwiched and fixed between the fixing surface 18a and the receiving surface 12b of the core 12.

  The receiving surface 12b is disposed at a position corresponding to the lower end of the groove 2A in the molded product 1A, and the second mold 14 is an annular molded portion for molding the inner peripheral surface above the groove 2A of the molded product 1A. 14a is formed so as to protrude downward, and as shown in FIG. 4, with the molds 13 and 14 closed, the middle portion of the insert member 17 is between the receiving surface 12b and the lower end surface of the annular molded portion 14a. The telescopic member 17 is configured to be fixedly held between the molds 13 and 14.

  A chamfered surface 18c made of an arcuate surface or an inclined surface is formed on the outer peripheral edge of the fixed surface 18a of the fixed member 18, and when the nested member 17 is elastically deformed in a releasing posture, the nested member 17 is formed by the chamfered surface 18c. By receiving the stress, the stress concentration of the nesting member 17 at the contact portion with the fixing member 18 is alleviated.

  In the present embodiment, the nesting member 17 is sandwiched between the fixing member 18 and the core 12 of the first mold 13, but instead of the fixing member 18, a fixing portion is used as in the fixing structure shown in FIG. 6. A fixing member 18A in which the vertical length of 18b is set to be short is provided, and the fixing member 18A is fixed to the core 12, and the nest is inserted between the fixing surface 18a of the fixing member 18A and the receiving surface 12b of the first mold 13. A gap wider than the thickness of the member 17 is formed, and a gap is formed between the fixing surface 18a of the fixing member 18A and the receiving surface 12b of the first mold 13 to hold the nesting member 17 and release. It is also possible to configure so that the nesting member 17 is elastically deformed as shown by a virtual line at the time of molding. In addition, as a structure for fixing the nesting member 17 to the first mold 13, any structure other than those shown in FIGS. 2 and 6 can be used as long as the nesting member 17 can be held so as not to fall off from the first mold 13. It is also possible to adopt a fixed structure.

  The nesting member 17 can be formed of an elastic body made of any material as long as it is a synthetic resin material or a rubber material having a higher elastic limit and a lower elastic modulus than a metal material. Since the insert member 17 is in direct contact with the high-temperature molten resin injected into 15, it is made of a synthetic resin material having heat resistance. Specifically, it is preferably composed of a heat-resistant synthetic resin material such as a fluororesin, a polyacetal resin, a polyamide resin, or a polyetheretherketone resin, or a rubber material such as nitrile rubber, chloroprene rubber, or fluororubber. Moreover, since the molding part 17a of the insert member 17 slides on the inner surface of the molded product 1A, it is preferable to adjust the hardness so that the inner surface of the molded product 1A is not damaged.

  The thickness T of the nesting member 17 and the distance L from the mounting portion 17b to the molding space 15 can be arbitrarily set. However, as the thickness T increases, the nesting member 17 becomes difficult to elastically deform, and the distance L Since the telescoping member 17 is less likely to be elastically deformed as the length becomes shorter, the wall thickness T and the distance L are appropriately set in consideration of the releasability of the molded product 1A.

  The molded portion 17a of the telescopic member 17 protruding into the molding space 15 is difficult to separate from the molded product 1A when the molded product 1A is released. It is preferable to form a cross-sectional shape having a shorter partial arc shape. Further, when the molded product 1A is released, the molded portion 17a of the nesting member 17 slides on the inner peripheral surface of the molded product 1A, so that no scratches or the like are formed on the molded product 1A during sliding. The outer surface of the molded part 17a is preferably formed in a circular arc shape with a smooth surface.

  In the mold apparatus 10, as shown in FIG. 4, a molten synthetic resin material is injected into the molding space 15 in a state where the molding portion 17 a of the nesting member 17 protrudes into the molding space 15. 1A will be molded. When the molded product 1A is released, as shown in FIG. 5, the molded product 1A is ejected by ejector pins 16 to release the molded product 1A. At this time, the molded portion 17a of the nesting member 17 is released. Moves to the second mold 14 side together with the molded product 1A, the nesting member 17 is elastically deformed to the mold release posture, and the molded portion 17a of the nesting member 17 is detached from the groove 2A of the molded product 1A. Then, while the molded portion 17a of the nesting member 17 is pressed against the inner peripheral surface of the molded product 1A in this released state, the molded product 1A moves to the second mold 14 side, and the molded product 1A enters. The molded product 1A is released from the child member 17, and the nested member 17 returns to the molding posture shown in FIG.

  According to this mold apparatus 10, the structure of the mold apparatus 10 is complicated with a simple configuration in which the first mold 13 is provided with the nesting member 17 made of an elastic body that can be elastically deformed toward the second mold 14. Thus, it is possible to realize a mold apparatus capable of forming the groove 2A as the undercut part while preventing the manufacturing cost of the mold apparatus 10 from being increased. Moreover, when the molded product 1A is released, the insert member 17 is elastically deformed so that the molded product 1A can be released, and no excessive force acts on the groove 2A as the undercut portion of the molded product 1A. The degree of freedom in designing the material of the product 1A, the shape of the groove 2A, the plate thickness, etc. can be greatly expanded.

  Instead of the nesting member 17, as shown in FIG. 7, it is possible to use a nesting member 17 </ b> A that is divided into a molding portion 20 and a support member 21 that elastically supports the molding portion 20.

  Moreover, when shape | molding molded products 1B-1E as shown in FIG.1 (b)-FIG.1 (e), it is in the shape of molded products 1B-1E with the 1st metal mold | die 13 and the 2nd metal mold | die 14. FIG. In addition to forming a corresponding molding space, a mold apparatus in which a nested member for molding the grooves 2B to 2E is fixed to the first mold 13 is used.

  Furthermore, in the present embodiment, the case where the present invention is applied to a mold apparatus for injection molding has been described, but the present invention is similarly applied to a mold apparatus for powder molding or cast molding. be able to.

(A)-(e) is explanatory drawing of the molded product which can be shape | molded with the metal mold | die apparatus of this invention. The longitudinal section in the mold opening state of the metallic mold device of the present invention Plan view of the first mold of the mold apparatus Longitudinal sectional view of the mold device with the mold closed Explanatory drawing of operation at the time of mold release of mold product FIG. 2 equivalent view of a mold apparatus of another configuration Longitudinal sectional view of the vicinity of the nesting member of the mold apparatus of other configuration

Explanation of symbols

1A to 1E Molded products 2A to 2E Groove parts 3A, 3B, 3C, 3E Through hole 10 Mold device 11 Mold plate 12 Core 12a Small diameter part 12b Receiving surface 13 First mold 14 Second mold 14a Annular molding part 15 Molding space 16 Ejector pin 17 Nesting member 17a Molding portion 17b Mounting portion 18 Fixing member 18a Fixing surface 18b Fixing portion 18c Chamfering surface 19 Screw member 18A Fixing member 17A Nesting member 20 Molding portion 21 Support member

Claims (7)

  Of the first mold and the second mold, the first mold to which the ejector pin is attached is connected to the second mold side by utilizing the gap between the molds formed when both molds are opened. A mold apparatus characterized in that a telescopically deformable telescopic member is provided so as to protrude into the molding space.   The mold is a mold for forming a cylindrical or columnar molded product, and a groove is formed on at least one of an inner peripheral surface and an outer peripheral surface in the middle of the molded product by the insert member. The mold apparatus according to claim 1.   The fixing member which fixes the said insert member to a 1st metal mold | die is provided, The chamfering surface which consists of a circular arc surface or an inclined surface was formed in the front-end edge of the fixed surface by the side of the insert member in this fixing member. Mold equipment.   The mold apparatus of any one of Claims 1-3 which formed the shaping | molding part which protrudes in the shaping | molding space among the said nesting members in semicircle shape in cross section.   The mold apparatus according to any one of claims 1 to 4, wherein the nesting member is made of a heat-resistant synthetic resin material or rubber material.   The mold apparatus according to any one of claims 1 to 5, wherein the nesting member is made of a fluororesin, a polyacetal resin, a polyamide resin, a polyetheretherketone resin, a nitrile rubber, a chloroprene rubber, or a fluororubber. The mold apparatus according to claim 1, wherein the mold is a mold for plastic injection molding.

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