JP5307976B2 - Injection mold - Google Patents

Description

  The present invention relates to, for example, an injection mold for forming a molded product with a hook such as a test tube or a writing instrument.

  An injection mold for molding a cylindrical molded product such as a test tube or a writing instrument is provided with a plurality of cavities in one molding mold, and the molten resin injected from a resin injection port is distributed by a hot runner. It is configured to lead to the cavity.

  This injection mold is configured so that a plurality of molded products can be simultaneously molded by one injection molding, basically, one resin injection port in the sprue portion provided in the center portion, A branch gate that branches into a plurality of branches is provided. On the other hand, the mold body is provided with a plurality of cavities, and a hot runner having an edge gate communicating with the cavities is provided. Then, the resin pressure from the resin passage of the hot runner is uniformly distributed to the edge gate that opens to the cavity forming cavity portion of the cavity via the branch gate (see, for example, Patent Document 1).

In addition, as an injection mold, it has a barrel molding cavity and a flange molding cavity at the opening end of the barrel molding cavity, a cavity for molding a molded product with a flange, and molding a hip from a hot runner There is known an injection mold of a molded product provided with an edge gate leading to a side portion of a cavity portion (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 2005-41020 Japanese Patent No. 3396880

However, the injection mold of Patent Document 1 has a problem that a gate mark remains in the body portion of the molded product because the edge gate is opened in the body portion forming cavity portion of the cavity. In addition, since the injection gate of Patent Document 2 has an edge gate opened to the cavity forming cavity portion of the cavity, the gate mark does not remain in the body portion of the molded product, thus eliminating the problem of Patent Document 1. it can.
However, when the resin filled in the flange molding cavity is cooled, a contraction is formed between the opening hole of the edge gate, and the molten resin flows out of the edge gate into this gap, so that the molded product can be removed. There is a problem that the resin residue is generated in the part and the quality of the molded product is deteriorated.
The present invention has been made paying attention to the above circumstances, and the purpose thereof is to leave a gate mark on the flange of the molded product even if an edge gate communicating with the cavity for molding the flange of the cavity is provided. An object of the present invention is to provide an injection mold that can improve the quality of a molded product.

In order to achieve the above object, the present invention provides a fixed mold, a movable mold that can be brought into and out of contact with a fixed mold, a fixed mold, and a movable mold. A body molding cavity part provided between the cavity part, a cavity having a flange part molding cavity part at the opening end of the body part molding cavity part, and molding a flanged molded product, and a resin provided in the fixed mold A hot runner having a resin passage communicating with the inlet, an edge gate provided in the hot runner for filling the cavity with the molten resin, and a molten resin provided in the edge gate and supplied from the hot runner to the cavity And an undercut is formed in the die-cutting direction of the flanged molded product at the periphery of the flange molding cavity from the split surface. An inclined surface composed of an inclined surface is provided, the opening hole is provided opposite to the inclined surface, and the flange of the molded product is reduced in diameter by the inclined surface when the molded product is punched. An injection mold characterized in that the resin is cut by rubbing.

  According to a second aspect of the present invention, the opening hole of the edge gate according to the first aspect is opposed to a middle portion of the inclined surface of the inclined surface forming the undercut, and the flange portion of the flanged molded product is removed when the flanged molded product is die-cut. The resin is cut by rubbing the opening hole.

  According to a third aspect of the present invention, the cavity according to the first aspect includes a plurality of cavities, the hot runner has an edge gate communicating with the branch gate, and the molten resin guided through the hot runner is provided with the plurality of cavities. It is characterized by distributing to.

  According to this invention, the inclined surface that forms the undercut in the die-cutting direction of the molded product with the flange is provided on the outer peripheral portion of the flange molding cavity portion, and the opening hole of the edge gate is provided opposite to the inclined surface. Thus, when the molded product with a flange is punched, the resin is cut by rubbing the opening hole with the flange of the molded product with the flange. Therefore, no gate marks remain on the flange portion of the molded product with a hook, and the quality of the molded product can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a vertical side view of an injection mold, FIG. 2 is an enlarged vertical side view of an X portion of FIG. 1, and FIG. 3 is a perspective view of a molded product with a flange. The injection mold 11 is a mold for molding a flanged molded product A such as a test tube or a writing instrument. As shown in FIG. 1, one injection mold 11 has a plurality of flanged molded products. A molding part 12 capable of molding A at the same time is provided.

  The injection mold 11 will be described. The injection mold 11 includes a fixed mold 13 and a movable mold 14 and is divided by a dividing surface 15. The fixed mold 13 is provided with a hot runner 16 communicating with a resin injection port (not shown), and the molten resin injected from the resin injection port is branched and guided to a plurality of molding parts 12.

  A resin passage 17 is provided in the axial center portion of the hot runner 16, and a heater 18 is wound around the outer periphery of the resin passage 17. An edge gate 19 is provided at the lower end of the hot runner 16, that is, at the downstream side of the resin passage 17. The edge gate 19 is made of, for example, a heat conductive alloy such as Be-Cu, and has a cylindrical portion 19b having a resin passage 19a communicating with the resin passage 17, and a widening portion 19c having a widening end provided integrally with the cylindrical portion 19b. have. The widened portion 19c is provided with a plurality of branch gates 20a and 20b corresponding to the number of the molded portions 12, which are bifurcated left and right in the present embodiment. On the downstream side of these branch gates 20a and 20b, opening holes 21a and 21b that are opened on the left and right side surfaces of the edge gate 19 are provided. A resin heat insulating layer 19 c is provided around the edge gate 19.

  The cylindrical portion 19b of the edge gate 19 thus configured is inserted into a mounting hole 22 drilled along the axis at the lower end portion of the hot runner 16, and the upper end surface of the cylindrical portion 19b is the bottom surface 22a of the mounting hole 22. Abut. A mounting hole 23 is formed in the lower end portion on the axis of the edge gate 19, and a receiving piece 24 made of a material having heat resistance such as ceramic and having a small thermal expansion coefficient is fixed to the mounting hole 23. ing. The receiving piece 24 is in contact with a gate pad 25 provided on the movable mold 14. And even if the resin pressure is applied to the edge gate 19, the edge gate 19 is prevented from lowering in the drawing.

  Next, the molding part 12 will be described. The cavity 26 for molding the flanged molded product A is composed of a trunk part molding cavity part 27 and a collar part molding cavity part 28. The body molding cavity 27 and the collar molding cavity 28 are a cavity outer cylinder 29 provided in the fixed mold 13 and a cavity provided in the movable mold 14 and inserted into the cavity outer cylinder 29. It is comprised by the clearance gap between the inner cylinder parts 30. FIG.

Further, as shown in FIG. 2, an inclined surface 28 b that forms an undercut 28 a in the die-cutting direction of the flanged molded product A is formed on the outer peripheral portion of the flange molding cavity portion 28. The opening hole 21a (21b) of the edge gate 19 is opposed to the inclined middle part of the inclined surface 28b, and the molten resin injected from the opening hole 21a (21b) of the edge gate 19 extends from the inclined surface 28b to the flange part. The molding cavity portion 28 is filled.
Furthermore, a pipe 32 is concentrically provided in the axial direction in the inner cavity 30a of the inner cylinder portion 30 with a gap 31 on the outer peripheral surface. The inside of the pipe 32 is provided with a cooling water forward path 33, and the gap portion 31 is provided with a cooling water backward path 34 that communicates with the cooling water forward path 33 at the tip of the pipe 32. The cooling water forward path 33 communicates with a discharge side of a cooling water supply source (not shown), and the cooling water return path 34 constitutes a cooling water circulation path communicating with a suction side of the cooling water supply source. And the molten resin with which the cavity 26 was filled is cooled uniformly from the inside.

  A spiral cooling water channel (not shown) is provided over the entire length of the outer peripheral portion of the cavity outer cylinder portion 29 to uniformly cool the molten resin filled in the cavity 26 from the outside.

  Further, a hemispherical portion 35 is provided at the distal end portion of the body portion forming cavity portion 27. A block 36 that is fixed to the fixed mold 13 is provided on the distal end side of the body portion forming cavity portion 27. The block 36 is provided with a recessed portion 37 that forms a hemispherical portion 35.

  Next, the operation of the injection mold configured as described above will be described.

  When molten resin is injected from a resin injection port (not shown) into the injection mold 11 from the injection molding machine, the molten resin is guided to the resin passage 17 of the hot runner 16. The molten resin in the resin passage 17 is led from the hot runner 16 to the branch gates 20a and 20b through the resin passage 19a of the edge gate 19, and the resin heat insulating layer 19b provided around the edge gate 19 and the opening holes 21a, The cavity 26 is filled through 21b. That is, when the molten resin is filled into the cavity 26 from the branch gates 20a and 20b through the opening holes 21a and 21b, a part of the semi-molten resin in the resin heat insulating layer 19c is combined with the injected molten resin. The cavity 26 is filled with the molten resin, and the molten resin is filled in the order of the collar part molding cavity part 28 to the body part molding cavity part 27 and the hemispherical part 35.

  At this time, the edge gate 19 is pressed downward by the pressure of the molten resin, but the receiving piece 24 fixed to the edge gate 19 is in contact with the receiving base 25 provided in the movable mold 14. 19 can be prevented from falling.

  Further, since the cooling water passage is provided so as to surround the outside of the cavity 26, the molten resin filled in the cavity 26 is uniformly cooled from the outside. Inside the cavity 26, a cooling water circulation path is formed in which the cooling water flowing from the cooling water supply source flows through the cooling water forward path 33, is folded at the tip of the pipe 32, and flows to the cooling water return path 34. The molten resin filled in the inside is uniformly cooled also from the inside.

  Therefore, the resin in the cavity 26 is cooled and solidified in a short time. After the resin is cooled and solidified, when the movable mold 14 is retracted with respect to the fixed mold 13, the fixed mold 13 and the movable mold 14 are divided by the dividing surface 15, and the hooked molding following the shape of the cavity 26 is formed. Product A is obtained.

At this time, since the undercut 28a is formed in the die-cutting direction of the flanged molded product A on the outer peripheral portion of the flanged molding cavity portion 28, the flange of the flanged molded product A forcibly passes through a narrow passage during die cutting. Then, the opening holes 21a and 21b are rubbed with the ridges of the flanged molded product A to cut the resin. Therefore, as shown in FIG. 3, the gate mark does not remain in the ridge portion of the molded product A with a flange, and the quality of the molded product can be improved.
The undercut 28a formed on the outer peripheral portion of the flange molding cavity portion 28 is contracted when the molten resin filled in the flange molding cavity portion 28 is cooled, and the flange portion is reduced in diameter. Need to design. That is, even if the diameter of the flange portion of the flanged molded product A is reduced, the flange portion of the flanged molded product A needs to be able to cut the resin by rubbing the opening holes 21a and 21b during die cutting.
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal side view of an injection mold showing a first embodiment of the present invention. The vertical side view which expanded the X section of FIG. 1 which showed the same embodiment. The perspective view of the molded product with a hook which shows the same embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Injection mold, 13 ... Fixed mold, 14 ... Movable mold, 15 ... Dividing surface, 16 ... Hot runner, 17 ... Resin passage, 19 ... Edge gate, 21a, 21b ... Opening hole, 26 ... Cavity, 27 ... trunk molding cavity, 28 ... buttocks molding cavity, 28a ... undercut, 28b ... inclined surface

Claims (3)

A fixed mold,
A movable mold that can be brought into and out of contact with the fixed mold,
A body molding cavity provided between the fixed mold and the movable mold, and a cavity having a flange molding cavity at the opening end of the body molding cavity, and molding a molded product with a flange,
A hot runner having a resin passage communicating with a resin inlet provided in the fixed mold;
An edge gate provided in the hot runner to fill the cavity with molten resin;
An opening hole provided in the edge gate for supplying molten resin supplied from the hot runner to the cavity;
Have
An inclined surface comprising an inclined surface in the same direction that forms an undercut in the die-cutting direction of the flanged molded product starts at the peripheral surface of the flange molding cavity from the dividing surface. The opening hole is provided so as to face the surface, and when the molded product is punched, the flange portion of the molded product is reduced in diameter by the inclined surface, and the opening hole is rubbed and the resin is cut. Injection mold characterized by.   2. The resin is cut by rubbing the opening hole at a flange portion of the flanged molded product when die-cutting the flanged molded product, facing a midway portion of the inclined surface. The injection mold described in 1.   The cavity includes a plurality of cavities, the hot runner has an edge gate communicating with a branch gate, and the molten resin guided through the hot runner is distributed to the plurality of cavities. Item 2. An injection mold according to Item 1.

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