JP4114748B2 - Injection molding product manufacturing equipment - Google Patents

Description

  The present invention relates to an apparatus for manufacturing an injection-molded product having an end portion having a negative corner portion shape so that a parting line does not appear.

  An automobile resin bumper having negative corners at both ends is manufactured by injection molding. As shown in FIG. 3 (A), a conventional general injection molding apparatus includes a fixed lower mold 1, an upper mold 2 that moves up and down relative to the lower mold 1, and a lower mold 1 that is mounted on a slide base 4 by a cylinder 5. A trapezoidal convex portion 60 having inclined surfaces on two front and rear surfaces on the surface facing the upper mold 2 of the demolding core 3. The upper die 2 is provided with a trapezoidal concave portion 90 having the same shape as the convex die 60, and the front end portion of the demolding core 3 is brought into contact N with the lower die 1 before the upper die 2 is raised, As shown in FIG. 3 (B), the upper die 2 is lowered, the concave portion 90 is fitted to the convex portion 60, the demolding core 3 is positioned and fixed, and the die is brought into contact with the die clamping force 0. A cavity C1 for molding an injection molded product is formed by the mold 1 and at the same time the negative corner portion is molded by the upper mold 2, the lower mold 1 and the demolding core 3. Then, as shown in FIG. 3C, a clamping force is applied to the lower die 1 and the upper die 2, and as shown in FIG. 3D, the cavities C1 and C2 are applied to the cavities C1 and C2. An injection molded product W is molded by injecting resin.

In the conventional injection mold described above, the mold release core 3 is in a parallel H1 posture with respect to the upper mold 2 at the time of contact with the mold with a clamping force of 0 in FIG. When the clamping force of the lower mold 1 and the upper mold 2 is applied, the mold releasing core 3 does not maintain the parallel H1 as shown in FIG. As a result, a step is generated in the cavity C2 for forming the negative angle portion, and when the resin is injected and injected into the cavities C1 and C2, the upper die 2 is pressed and moved by the resin pressure. As a result, the parting line PL is generated in the negative angle portion S of the injection molded product W as shown in FIGS. 4 and 5 due to the step. There is a problem that it takes a lot of time for countermeasures against this defect and also requires maintenance.
Japanese Patent Application Laid-Open No. 2003-205536 provides a technique for preventing the parting line PL from appearing on a part that becomes a design surface of an injection-molded product having a part that becomes an undercut part. Expensive equipment costs are required.
Japanese Utility Model Publication No. 2003-205536

  An object of the present invention is to provide an apparatus for manufacturing an injection molded product in which a parting line does not appear in an injection molded product having a negative corner at the end while maintaining the structure of a conventional injection mold. It is to be.

The present invention for achieving the above object is an apparatus for producing an injection-molded article having a negative angle portion at an end as defined in claim 1, comprising a fixed lower mold and the lower mold An upper mold that moves up and down with respect to the lower mold , and a demolding core that is attached to the lower mold via a urethane rubber plate or an elastic member of a rubber plate so that it can float and slide in a horizontal direction by a cylinder. When the upper mold is lowered, the concave part provided in the upper mold is brought into contact with the convex part provided in the demolding core, and the demolding core is positioned and fixed. In the injection mold in which the cavity for forming the negative angle portion is formed by the upper mold, the lower mold, and the demolding core at the same time, the convex portion provided on the demolding core is formed of the demolding core. Forward and backward A vertical surface on the front side and an inclined surface on the rear side in the advancing and retreating direction of the demolding core, and the concave portion provided in the upper mold is formed between the vertical surface contacting the vertical surface of the convex portion and the convex portion. An inclined surface that abuts the inclined surface is formed, and before clamping the upper die in the raised position, a clearance is set between the vertical surface of the convex portion and the vertical surface of the concave portion, and the upper die is lowered. After clamping, the vertical surface of the convex part is brought into contact with the vertical surface of the concave part by the inclined surfaces of the convex part and the concave part so that a clearance is set between the lower mold and the front end face of the mold release core. The core is positioned and fixed at a regular position .

According to the present invention, since the demolding core is free in its advancing and retreating direction, the demolding core is positioned and fixed at a normal position after the upper mold is lowered, and an elastic member such as a urethane rubber plate is used. Therefore, the upper mold and the lower mold can absorb the bending of the demolding core when the clamping force is applied by the elastic member, thereby creating a step that creates a parting line in the cavity for molding the negative corner. Even if the upper mold is pressed and moved by the resin pressure injected and injected into the cavity, the mold removal core is free in the advancing and retreating direction, ensuring that the mold removal core follows the movement of the upper mold and has no step. This makes it possible to produce injection molded products with good appearance quality without any parting line, and simply add a simple structure while maintaining the structure of the conventional injection mold. Hakare is cost reduction of mold equipment costs, it is possible significantly reduce the mold maintenance man-hours, maintenance during production also minimized the management man-hours can be greatly reduced. In addition, the number of live man-hours is greatly reduced, and the entire live life period can be shortened.

  The best mode for carrying out the present invention will be described below with reference to the drawings. The structure of the device of the present invention will be described with reference to FIG. Reference numeral 1 denotes a fixed lower mold, and reference numeral 2 denotes an upper mold that moves up and down relative to the lower mold 1. A demolding core 3 is attached to the lower mold 1 so as to be slidable in a horizontal direction on a slide base 4 by a cylinder 5. A convex portion 6 is provided on a surface of the demolding core 3 facing the upper die 2, and a concave portion 9 corresponding to the convex portion 6 is provided on the upper die 2. FIG. 1 shows a state before mold clamping in which the upper mold 2 is located at the upper position as shown in FIG. Such a configuration is the same as that of a conventional general injection molding apparatus described in the background art.

In the above configuration, an elastic member 12 such as a urethane rubber plate is interposed on the lower surface of the slide base 4, and the demolding core 3 is attached to the lower mold 1 so that it can float (only about 0.2mm), and after clamping The bending of the demolding core 3 is absorbed by the elastic member 12. The elastic member 12 is not limited to a urethane rubber plate, but may be a normal rubber plate.

In the present invention, the convex portion 6 provided on the mold release core 3 forms a vertical surface 7 on the front side in the advance / retreat direction of the mold release core 3 and an inclined surface 8 on the rear side in the advance / retreat direction of the mold release core 3. The concave portion 9 provided in the upper mold 2 is formed with a vertical surface 10 that contacts the vertical surface 7 of the convex portion 6 and an inclined surface 11 that contacts the inclined surface 8 of the convex portion 6. A gap a is set between the vertical surface 7 of the convex part 6 and the vertical surface 10 of the concave part 9 before the mold clamping when the upper mold 2 is in the raised position. The vertical surface 7 of the convex portion 6 is brought into contact with the vertical surface 10 of the concave portion 9 by the inclined surfaces 8 and 11 of the concave portion 9 and the concave portion 9, and a clearance Fr1 is formed between the lower die 1 and the front end surface of the demolding core 3. The cylinder 5 is set to the clearance Fr2 so that the demolding core 3 is properly positioned based on its forward / backward direction in a free state. It is obtained so as to fix.

  The molding process by the injection molding apparatus of the present invention will be described with reference to FIG. FIG. 2A shows the first step in the state shown in FIG. 1A. The mold release core 3 is positioned at the forward end by the cylinder 5 before the mold clamping in which the upper mold 2 is in the raised position, and the projection 6 The clearance a is set between the vertical surface 7 and the vertical surface 10 of the recess 9.

  FIG. 2B is a second step shown in FIG. In this second step, the upper mold 2 is lowered and the demolding core 3 comes into contact with the mold 6 with the protrusion 6 and the recess 9 in the free state in the advancing and retracting direction, and the mold is clamped with a mold clamping force of zero. At this time, the demolding core 3 is moved forward by the inclined surfaces 8 and 11 of the convex portion 6 and the concave portion 9, the vertical surface 7 of the convex portion 6 is brought into contact with the vertical surface 10 of the concave portion 9, and the clearance a is set to zero. The core 3 is positioned and fixed at a regular position, and the upper die 2 and the lower die 1 form a cavity C1 for molding an injection molded product. At the same time, the upper die 2, the lower die 1 and the demolding core 3 form a negative corner portion. A cavity C2 is formed for molding.

  FIG. 2C shows the third step. This third step is a step of applying a clamping force to the lower mold 1 and the upper mold 2. At this time, the mold release core 3 bends due to the addition of the clamping force, but this is absorbed by the elastic member 12, and the mold release core 3 is held in a state parallel to the upper mold 2 to form the negative corner portion. Therefore, the mold is clamped without generating a step in the cavity C2.

  FIG. 2D shows the fourth step. In the fourth step, the resin is injected and injected into the cavity C1 for molding the injection molded product and the cavity C2 for molding the negative corner portion in a state where the mold is clamped by applying the clamping force in the third step. This is a step of forming a molded product. In the fourth step, the elastic member 12 absorbs the bending of the mold release core 3 in the third process, and the mold release core 3 maintains a state parallel to the upper mold 2 and the cavity C2 for molding the negative corner portion. Therefore, the parting line PL does not appear at the negative angle portion as in the prior art.

  In the fourth step, the upper mold 2 is pressed and moved by the resin pressure injected and injected over the cavity C1 and the cavity C2, but the clearance Fr2 is set in the cylinder 5 portion of the mold release core 3 so that the core removal 3 moves forward and backward. Since the moving force of the upper die 2 acts on the vertical surface 7 of the convex portion 6 from the vertical surface 10 of the concave portion 9, the demolding core 3 follows the movement of the upper die 2, and the negative angle The cavity C2 for forming the portion maintains a state without a step, and the parting line PL is not generated at the negative angle portion.

  As described above, the present invention adds a simple structure to an injection mold that is generally used in the past, thereby reducing the generation of a step where the parting line PL is generated in the cavity C2 for forming the negative angle portion. It is possible to manufacture injection molded products with good appearance quality, eliminating the need for a lot of time for countermeasures against defects caused by the parting line PL, eliminating the need for maintenance, and reducing the cost of mold equipment. Has advantages.

Sectional view of the device of the present invention Sectional drawing which shows the process by this invention apparatus Sectional drawing which shows the processing process in the manufacturing apparatus of a conventional general injection molded product Perspective view of an injection-molded product with a parting line when processed with a conventional device E-line cross section of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower mold | type 2 Upper mold | type 3 Demolding core 4 Slide base 5 Cylinder 6 Convex part 7 Vertical surface 8 Inclined surface 9 Recessed part 10 Vertical surface 11 Inclined surface 12 Elastic member a Clearance C1 Cavity C2 Cavity PL Parting line Fr1 Clearance Fr2 Skimmer

Claims (1)

An apparatus for manufacturing an injection-molded product having a negative angle portion at an end, a fixed lower mold, an upper mold that moves up and down relative to the lower mold, and a urethane rubber plate or a rubber plate on the lower mold The demolding core is mounted so as to be able to float through an elastic member and to be slidable in a horizontal direction by a cylinder. A recess provided in the upper mold is provided in the demolding core by lowering the upper mold. The mold is aligned with the convex portion and the mold release core is positioned and fixed to form a cavity for molding an injection molded product with the upper mold and the lower mold, and at the same time, the negative angle section is formed by the upper mold, the lower mold and the mold release core. in the injection mold to form a cavity for molding the convex portion provided on said demolding core and a vertical surface on the front side in the moving direction of demoulding the core, inclined rear in the moving direction of demolding the core The concave portion provided in the upper mold is formed with a vertical surface that contacts the vertical surface of the convex portion and an inclined surface that contacts the inclined surface of the convex portion. Before clamping the mold, a clearance is set between the vertical surface of the convex portion and the vertical surface of the concave portion, and after clamping the upper mold is lowered, the vertical surface of the convex portion is formed by the inclined surfaces of the convex portion and the concave portion. Injection molding , characterized in that the mold release core is positioned and fixed at a normal position so that a gap is set between the lower mold and the front end face of the mold release core by aligning with the vertical surface of the recess Product manufacturing equipment.

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