JP2008162213A - Injection molding mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously mold resin molded products having undercut portions inside of the products. <P>SOLUTION: A pair of slide cores 6 is arranged in movable-side mold plates 4 so as to slide on a movable-side receiving plate 5 and cavity blocks 7 are connected to the cores. In a pair of facing inner slide cores 11, supporting portions 11a are incorporated in a fixed-side mold plate 2 movably in a mold opening and closing direction and in a vertical direction, tips face a cavity 8 having bosses 11b fitting into undercut portions 9a of the molded product 9 formed inside the molded product 9. A center core 12 having a tapering portion is secured to the fixed-side receiving plate 3 and the tip enters the inside of an inner slide core 11 so as to be sandwiched. Pushing pins 13 arranged in the cavity blocks 7 are biased by coil springs 14 and push and press the inner slide core 11 in a closing direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an injection mold, and more particularly, to an inner structure of an injection mold for molding a molded product having an undercut portion inside.

  In recent years, plastic products have been frequently used in various industrial products for the purpose of improving material characteristics, facilitating parts production, facilitating assembly, reducing weight, and reducing costs, and are mass-produced using injection molding machines. Some of such plastic molded products have an undercut portion on the inside, such as a bottle cap or an automobile console box. When molding such a molded article, an injection mold having an inner slide core is used (for example, see Patent Document 1).

  An example of an injection mold for molding such a plastic molded product will be described with reference to the drawings. FIG. 4 is a sectional view showing the main part of a conventional injection mold. As shown in FIG. 4, the injection mold 51 is composed of a fixed mold and a movable mold, and is fixed above the parting line PL1, which is a split surface between the fixed mold and the movable mold. A fixed-side template 2 and a fixed-side receiving plate 3 are laminated on the mold. The fixed-side template 2 incorporates a fixed-side cavity block 21 that forms the cavity 8 together with the movable-side cavity block 57, a fixed-side cavity spacer A22, and a fixed-side cavity spacer B23. A dividing surface between the fixed side mold plate 2 and the fixed side receiving plate 3 is a parting line PL2.

  In the main part of the movable mold below the parting line PL1, a cavity 8 on the inside and a movable cabinet block 57 on the outside are incorporated in the movable receiving plate cavity spacer 5 to form a movable mold 4 section. is doing. A molded product 9 molded in the cavity 8 has an elongated cylindrical shape with one side sealed and a groove on the inner wall.

  The pair of opposed inner slide cores 11 are incorporated so that the support portion 11a is sandwiched between the fixed side cavity block 21 and the fixed side cavity spacer B23 and is slidable in the fixed side cavity spacer A22 in a direction perpendicular to the mold opening / closing direction. The coil springs 15 are biased toward each other. Further, the driving range of the inner slide core 11 is restricted by a bolt 16 fixed to the support portion 11a. The front end of the inner slide core 11 faces the cavity 8, and has a protrusion 11 b that fits into an undercut portion 9 a formed inside the molded product 9.

  A central core 12 having a tapered distal end is fixed to the stationary side receiving plate 3, and the distal end of the central core 12 narrows into the inner slide core 11 and is integrated with the distal end of the inner slide core 11. And has a cylindrical shape. Other details of the configuration are not related to the present invention, and the description thereof will be omitted.

  Next, the molding operation of this injection mold will be described. First, when the molten resin is injected into the cavity 8 and the resin is cooled and cured while maintaining the pressure for a certain time, the mold is opened as shown in FIGS. FIG. 5 is a cross-sectional view of the main part of the injection mold 51 showing the part on the fixed side receiving plate 3 away from the fixed side mold plate 2 in the parting line PL2. FIG. 6 is a cross-sectional view of an essential part of the injection mold 51 showing that the movable mold moves and the parting line PL1 starts to be opened in order to take out the molded product 9.

As shown in FIG. 5, when the fixed side receiving plate 3 is separated from the fixed side mold plate 2, the central core 12 is pulled out from the inner slide core 11, and the support portion 11 a moves in a direction in which the inner slide core 11 is closed. At this time, since the sliding force in the support portion 11 a does not reach the tip of the inner slide core 11, the protrusion 11 b of the inner slide core 11 is not released from the undercut portion 9 a while being in close contact with the molded product 9. In this state, as shown in FIG. 6, the molded product 9 is pulled out from the cavity 8 by the inner slide core 11 as the parting line PL <b> 1 opens and the movable mold moves.
JP 2001-162627 A (FIGS. 1 to 6)

  However, as described above, in the conventional injection mold 51, the sliding force in the support portion 11a does not reach the tip of the inner slide core 11, so that an underline is shown in FIG. There was a problem that the molded product 9 having the cut portion 9a could not be released and was left behind in the fixed mold, making it impossible to perform continuous molding.

  The present invention has been made to solve such conventional problems, and an object thereof is to provide an injection mold that enables continuous molding of a resin molded product having an undercut portion on the inside. It is.

  Means of the present invention for solving the above problems is an injection mold for molding a resin molded product having an undercut portion inside by a cavity formed of a fixed side mold and a movable side mold. A pair of inner slide cores having protrusions that fit into the undercut portions of the product are urged in the closing direction and are supported by the fixed side mold plate so as to be movable in the direction perpendicular to the mold opening and closing direction and face the cavity. In the injection mold configured to open the inner slide core by inserting the central core fixed to the fixed side receiving plate, the pair of slide cores are urged in the protruding direction by a coil spring. A cabinet block storing a push pin is provided, and the push pin presses the inner slide core from the outside.

  The push pin is retracted from the molded product together with the cabinet block when the slide core is opened.

  As described above, according to the present invention, there is provided an injection mold for molding a resin molded product having an undercut portion on the inside by a cavity formed of a fixed side mold and a movable side mold. A pair of inner slide cores having protrusions that fit into the undercut portions of the inner surface are urged in a closing direction and are supported by a fixed-side mold plate so as to be movable in a direction perpendicular to the mold opening / closing direction and face the cavity. In the injection mold configured to open the inner slide core by inserting the central core fixed to the fixed side receiving plate, the push urged in the protruding direction by the coil spring on the pair of slide cores Since the cabinet block containing the pins is arranged so that the push pin presses the inner slide core from the outside, the continuous shot of the resin molded product having the undercut portion on the inside is provided. Molding becomes possible, it came to the cost of the hand-numbered shortening, such as significant a molded article can be achieved.

  Further, since the push pin is retracted from the molded product together with the cabinet block when the slide core is opened, the push pin is retracted from the molded product and the molded product can be taken out.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of an injection mold according to an embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional views of a main part for explaining the operation of the injection mold.

  First, referring to FIG. 1, the configuration of an injection mold that is an embodiment of the present invention will be described. In FIG. 1, the same components and components as those of a conventional injection mold 51 in the injection mold 1 are denoted by the same names and reference numerals, and the description thereof is omitted. In the movable side template 4, a pair of cabinet blocks 7 are arranged on a pair of slide cores 6 that slide on the movable side receiving plate 5. The cavity 8 is formed by the fixed side mold plate 2, the cavity block 7 and the movable side receiving plate 5.

  A pair of opening / closing pins 10 for operating the slide core 6 are fixed to the fixed side receiving plate 3. The push pin 13 is disposed in the cavity block 7 and has a tip abutting against the inner slide core 11 to press the inner slide core 11 in a closing direction. A coil spring 14 is inserted into the rear portion of the push pin 13 and biases the push pin 13 in a direction in which the push pin 13 protrudes into the cavity 8.

  Next, the molding operation by the injection mold will be described with reference to FIGS. After the fixed side mold and the movable side mold are closed, molten resin is injected into the cavity 8 and the pressure is maintained for a certain time, and then the resin is cooled and cured to mold the molded product 9. Next, as shown in FIG. 2, the parting line PL <b> 2 is opened so that the fixed side receiving plate 3 is separated from the fixed side mold plate 2. When the central core 12 is pulled out from the inner slide core 11, the support portion 11a of the inner slide core 11 moves in the arrow direction, and at the same time, the push pin 13 biased by the coil spring 14 pushes the inner slide core 11 in the arrow direction. Therefore, the inner slide core 11 is released from the molded product 9 as indicated by an ellipse with a two-dot chain line.

  Subsequently, as shown in FIG. 3, when the movable mold moves and the parting line PL <b> 1 opens, the inner slide core 11 is pulled out from the cavity 8. As the movable mold is moved, the slide core 6 is opened by the action of the opening / closing pin 10, so that the push pin 13 is retracted from the molded article 9 and the molded article 9 is left in the cavity 8 of the movable mold. When the molded product 9 is taken out, the mold is closed in the reverse order to that when the molded product 9 is opened, and is prepared for the next molding.

  Next, the effect of the injection mold which is an embodiment of the present invention will be described. Since the push pin 13 is disposed on the slide core 6 and the push pin 13 presses the inner slide core 11 in the direction of closing the outer slide core 11 from the outside by the coil spring 14, the inner slide core 11 is formed when the parting line PL2 is opened. The product 9 can be released from the mold. Thereby, since the molded product 9 remains in the movable mold, continuous injection molding of a resin molded product having an undercut portion is possible.

  The injection mold of the present invention can be widely applied to injection molding of a molded product having an undercut portion.

It is principal part sectional drawing of the injection mold which is embodiment of this invention. It is principal part sectional drawing explaining the operation | movement of the injection mold which is embodiment of this invention. It is principal part sectional drawing explaining the operation | movement of the injection mold which is embodiment of this invention. It is principal part sectional drawing of the conventional injection molding die. It is principal part sectional drawing explaining operation | movement of the injection mold of FIG. It is principal part sectional drawing explaining operation | movement of the injection mold of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection mold 6 Slide core 7 Cavity block 8 Cavity 9 Molded product 9a Undercut part 11 Inner slide core 11b Protrusion part 12 Central core 13 Push pin 14 Coil spring

Claims (2)

  An injection mold for molding a resin molded product having an undercut portion inside by a cavity composed of a fixed side mold and a movable side die, and having a protrusion that fits into the undercut portion of the molded product A pair of inner slide cores are urged in a closing direction and are supported by a fixed-side mold plate so as to be movable in a direction perpendicular to the mold opening / closing direction, facing the cavity, and a central core fixed to the fixed-side receiving plate is In the injection mold configured to open the inner slide core by sandwiching, a mold block containing a push pin biased in a protruding direction by a coil spring on a pair of slide cores, An injection mold, wherein a push pin presses the inner slide core from the outside.   2. The injection mold according to claim 1, wherein the push pin retracts from the molded product together with the cabinet block when the slide core is opened.

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