JPH0621915U - Injection mold - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] The present invention aims to provide an injection molding die for injection-molding an injection-molded product partially having a through hole without causing burrs in the through hole. It is what [Structure] The injection-molding die of the present invention is provided with a pin or a convex body corresponding to a through-hole shape in a part of the die,
In an injection molding die for forming a through hole in a part of a molded product, an elastic body such as rubber or plastic is arranged at a position where the pin or the convex body contacts when the die is closed. It is characterized by that.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an injection molding die, and more particularly to an injection molding die for producing an injection molding product having a through hole in a part of the molding product.

[0002]

[Prior art]

 It is known that a molded product made of a thermoplastic resin material or a thermosetting resin material as a raw material has a through hole in a part thereof, and these are manufactured by the following method. In this one method, through-holes are not formed in the die molding stage, burrs that occur at the seams of the half-die halves are removed as necessary, and then manual processing or punching equipment is used in the subsequent process. It is a method of punching a through hole at a predetermined place.

In addition, as shown in FIG. 5, in another method, a pin or a convex body 13 corresponding to the shape of a through hole is provided on one fixed die 11, and a mold is closed on the other movable die 12. In this case, a hole 14 corresponding to the pin or the convex body 13 is provided, and the clearance 15 between the pin or the convex body 13 and the hole 14 is set to about 1 to 50 μm, and the resin material 16 is injected there. However, in this case, burrs are hardly generated in the through-hole portion of the molded product.

[0004]

[Problems to be solved by the device]

 However, in these known methods, the first method requires the separation and removal of burrs, which complicates the process and is disadvantageous in that in many cases burrs cannot be removed cleanly. In this case, the mold must be processed extremely accurately, which increases the cost, and in reality, processing variations are unavoidable, and the pin or convex shape is easily broken, and the pin or convex shape and the hole There is a drawback in that the material easily wraps around in the gaps and it is difficult to prevent the formation of burrs.

[0005]

Means for Solving the Problems The present invention relates to an injection molding die that solves the above disadvantages and drawbacks. A part of the die is a pin or a convex body corresponding to a through-hole shape. In an injection-molding die for forming a through hole in a part of a molded product, an elastic body such as rubber or plastic is attached to the portion where the pin or the convex body contacts when the die is closed. It is characterized by being arranged.

That is, the present inventor has variously studied to develop an injection molding die in which a molded product having a through hole in a part thereof by injection molding of a resin material does not generate burrs in the through portion. As a result, in a known injection-molding die in which a pin or a convex body corresponding to the shape of a through hole is provided in a part of the die, a portion that comes into contact with the pin or the convex body when the die is closed. It was found that burrs do not occur when an elastic body made of rubber, plastic, etc. is placed in the interior, and the present invention was completed by conducting research on the type, shape, hardness, etc. of this elastic body. This will be described in more detail below.

[0007]

[Action]

 The present invention relates to an injection molding die for molding a molded product having a through hole in a part thereof, in which a pin or a convex body corresponding to the through hole shape is provided in a part of the die. In a known injection-molding die as described above, an elastic body such as rubber or plastic is arranged at a portion where the pin or the convex-shaped body contacts when the die is closed. However, according to this, since the occurrence of burrs at the through hole portion is eliminated, there is an advantage that an injection molded product having a through hole in a part thereof can be easily and efficiently produced.

The present invention relates to an injection molding die for obtaining a molded product having a through hole in a part thereof by injection molding a resin material. The resin material to be injection-molded in the injection-molding die of the present invention includes thermosetting materials such as natural rubber, silicone rubber, SBR, IR, chloroprene, fluororubber, EPDM, IIR, NBR, acrylic rubber and urethane rubber. Examples thereof include resin materials and thermoplastic resin materials such as nylon, polyethylene, polypropylene, ABS, and polycarbonate.

Injection molding using such a resin material is performed by using an injection molding machine having an injection mechanism such as a plunger type, a screw-in line type, a pre-plunger type, and a mold clamping mechanism such as a toggle type or a direct pressure type. However, in order to form a through hole of any shape such as a circle, an ellipse, a triangle, a square, etc. in a part of the molded product, either one of the fixed mold and the movable mold can be used. In addition, a pin or a convex body corresponding to the shape of the through hole is provided.

The injection molding die of the present invention is a known injection molding die provided with a pin or a convex shape body corresponding to the shape of the through hole. It is said that an elastic body made of rubber or plastic is placed at the portion in contact with the convex body, and this elastic body is made of natural rubber, silicone rubber, SBR, IR, chloroprene, EPDM, IIR, It may be molded from NBR, fluororubber, or the like, rubber such as urethane resin or Teflon resin, or plastic (including thermoplastic elastomer).

The injection molding by the injection molding die of the present invention is performed by the method shown in FIGS. 1 (a) and 2 (a) are vertical sectional views showing an injection molding method using the injection molding die of the present invention, and FIGS. 1 (b) and 2 (b) are convex. This is a partially enlarged view of the vicinity of the shaped body, and this injection molding is performed with the fixed mold 1 and the movable mold 2 of the injection molding mold as shown in FIGS. 1 (a) and 2 (a). The resin material is densely ejected into the cavity, and the molded product 3 is molded therein. Since the molded product 3 needs to have a through hole, the fixed mold 1 has A pin or convex body 4 corresponding to the shape of the through hole is provided. The length of this pin or convex body is the same as the length of the through hole of the molded product in Fig. 1, and the longer one is longer. It is shown in FIG.

In the injection molding die of the present invention, the elastic body 5 made of rubber or plastic is arranged at the portion where the pin or the convex body 4 comes into contact when the die is closed. However, FIG. 1B and FIG. 2B are enlarged views showing the arrangement of the pin or the convex body 4 and the elastic body 5.

Therefore, according to this, when the resin material is ejected into the cavity portion of the closed mold, the molded article 3 is molded in the cavity and the resin material is in the vicinity of the pin or the convex body. When the mold is opened, a through hole is formed here, but since the pin or the convex shape body 4 exists here, the resin material cannot enter the area and burrs do not occur. Further, since the elastic body 5 is arranged above the pin or the convex shape body 4, there is an advantage that the pin or the convex shape is not damaged even when the mold is closed.

If there is a risk that the elastic body 5 will fall out of the mold before or during the injection process, the hole into which the elastic body 5 is inserted is undercut as shown in FIG. Alternatively, it may be applied or an adhesive may be applied thereto as shown in FIG. 4, and the adhesive layer 6 may be adhered to the mold.

If the hardness of the elastic body 5 is too low, burrs will gradually occur during repeated injection molding, and if the hardness is too high, the pin or the convex body will be damaged. Since it is possible that the rubber hardness is equivalent to 60 to 80 degrees, it is preferable that this material has heat resistance above the molding temperature, although it depends on the target molded product. The surface roughness should also be as low as possible.

[0016]

【Example】

 Next, examples of the present invention will be given. Example 1 A cylindrical pin for forming a through hole is provided in a fixed mold, a hole is provided in a position of a movable mold that opposes the pin, and a pin is brought into contact with the mold when the mold is closed. Corn rubber KE-1915A / B [trade name, manufactured by Shin-Etsu Chemical Co., Ltd.] was packed and heated to 150 ° C. to cure it to obtain an elastic body.

Then, 100 shot injection molding of silicone rubber KE-1915A / B (previously described) into this mold was performed using an injection molding machine LS-28A [trade name of Nisshin Plastic Co., Ltd.]. It was confirmed that this molded product did not have any burrs formed in its through holes and that the mold was not damaged.

Example 2 A square columnar pin for forming a through hole is provided in a fixed die, and a hole is provided at a position of a movable die corresponding to this pin, and the pin comes into contact with the die when the die is closed. Fluorine rubber Viton [trade name manufactured by DuPont, USA] was packed up to the position where it was heated and heated to 170 ° C to cure it into an elastic body.

Next, silicone rubber containing KE-951 [trade name of Shin-Etsu Chemical Co., Ltd.] and 100 parts by weight of a curing agent and C-8 [trade name of the same company] with 2 parts by weight of silicone rubber. When 100 shot injection molding was performed using the compound as a molding material using an injection molding machine, LS-28A (described above), no burr was formed in the through hole of this molding and there was no damage to the mold. It was confirmed.

Example 3 A columnar pin for forming a through hole is provided in a fixed die, and a hole is provided in a position of a movable die corresponding to this pin so that when the die is closed, the pin is The fluororubber Viton (described above) was packed up to the point of contact, heated to 170 ° C, and cured to form an elastic body.

Next, a 100-shot injection molding was performed on this mold by using ABS resin / AX-IP187 [trade name of Asahi Kasei Co., Ltd.] as a molding material using an injection molding machine LS-28A (described above). It was confirmed that this molded product did not have any burrs formed in its through holes and that the mold was not damaged.

[0022]

[Effect of device]

 The present invention relates to an injection molding die, which has a through hole formed in a part of a molded article in which a pin or a convex body corresponding to the shape of the through hole is provided in a part of the die as described above. An injection-molding die for molding, characterized in that an elastic body such as rubber or plastic is arranged at a position where it contacts the pin or the convex body when the die is closed. However, according to this, it is possible to prevent the occurrence of burrs in the through-holes of the molded product, so that it is possible to easily and efficiently manufacture the molded product having the desired through-hole. Given.

[Brief description of drawings]

1A is a vertical sectional view of an injection molding method using an injection molding die of the present invention, and FIG. 1B is a partially enlarged view thereof.

2A is a vertical sectional view of an injection molding method using another injection molding die of the present invention, and FIG. 2B is a partially enlarged view thereof.

FIG. 3 is a partially enlarged view of an injection-molding die of the present invention using an undercut elastic body. .

FIG. 4 is a partially enlarged view of an injection molding die of the present invention in which an elastic body is bonded by an adhesive layer.

FIG. 5 is a vertical sectional view of an injection molding method using a conventionally known injection molding die.

[Explanation of symbols]

1, 11 ... Fixed type, 2, 12 ... Movable type 3, 13 ... Molded body, 4, 14 ... Pin or convex shaped body, 5
… Elastic body, 6… Adhesive layer, 15… Clearance.

Claims (1)

[Scope of utility model registration request] 1. An injection molding die for forming a through hole in a part of a molded product, wherein a pin or a convex shape corresponding to the shape of the through hole is provided in a part of the die, and the mold is closed. An injection-molding die, characterized in that an elastic body such as rubber or plastic is arranged at a portion where the pin or the convex-shaped body comes into contact with each other.