JP2669488B2 - Injection mold and molded body using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die capable of efficiently cooling a boss portion or the like forming a thick portion of a molded article, and a molding using a core material molded from this die. Regarding the body

[0002]

2. Description of the Related Art An injection molding die having a cooling means such as a boss is disclosed in, for example, Japanese Utility Model Laid-Open No. 61-12714. This technique is, as shown in FIG.
01 is provided with a boss hole forming cast pin 103 made of a material having high heat conductivity on the side facing the cavity 102 (the boss hole forming cast pin 103 is fixed by caulking the pipe 104). The purpose is to prevent the occurrence of shrinkage (dent) near the bottom surface 105a of the boss portion 105 due to poor cooling of the molded body.

[0003]

The technique of the above publication is effective when the boss portion is relatively short, but it also requires a long cooling time in the case of a molded product having a long boss portion. If the mold is opened with insufficient pressure, the thick part of the boss part is cut off from the molded product, resulting in a defect.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide an injection molding die capable of efficiently cooling a thick boss portion. The present invention also provides a molded body using a core material molded from this mold.

[0005]

In order to solve the above-mentioned problems, the injection mold of the present invention has a boss hole formed in one of a pair of molds, such as a combination of a movable mold and a fixed mold, which constitutes a cavity. For this purpose, an injection molding die having a plurality of boss hole forming casting pins is usually provided, and a cooling casting pin for cooling the boss portion is provided on the other die. The boss hole forming casting pin and the cooling casting pin are made of a material having high thermal conductivity.

Further, the molded product of the present invention is obtained by sticking a skin layer onto a core material molded by using the above-mentioned injection molding die, and the hole formed by the cooling casting pin has a hole. A vent is provided to connect the hole and the outside. Here, the skin layer includes not only a solid skin but also a layer in which a foam layer is laminated on a solid.

Further, another molded body of the present invention has a structure in which a foam layer and a skin layer are laminated on the core material, and the boss hole is formed with the tip of the cooling casting pin having a gap. By facing the tip of the casting pin, the hole formed by the cooling casting pin communicates only with the foam layer.

[0008]

Since the injection mold of the present invention is provided with the boss hole forming casting pin and the cooling casting pin having good thermal conductivity, the boss portion can be cooled from both sides. In the molded article of the present invention, a skin layer is adhered to a core material provided with a ventilation hole connecting the hole formed by the cooling cast pin and the outside. Therefore, air is not trapped in the holes, so that the skin layer is not lifted or dented due to changes in temperature.

Also, the skin and the molded body are set in a mold,
In the case where the foaming agent is injected and integrated during this time, the tip of the cooling cast pin is adjusted so as to oppose the tip of the boss hole forming cast pin with a gap, and formed by the cooling cast pin. It is possible to prevent the foaming agent from leaking by allowing the formed hole to communicate only with the foam layer.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Here, FIG. 1 is a partial sectional view showing an example of the injection mold of the present invention.

In the figure, a boss hole forming cast pin 3 made of a material having high heat conductivity is provided on the side of the movable die 1 facing the cavity 2 and fixed by caulking with a pipe 4. Since the injection mold itself is provided with cooling means (not shown), it is usually unnecessary to newly provide a cooling means for the boss hole forming cast pin 3, but in some cases, the boss hole forming cast pin is not provided. Direct cooling means may be provided on the bottom 3a.
Further, on the side of the fixed mold 6, a cooling casting pin 7 which is also made of a material having high thermal conductivity is provided. In order to provide the cooling cast pin 7, a hole corresponding to the diameter of the pin is drilled in the fixed die 6 and the pin is driven in and fixed, or a hole larger than the boss hole forming cast pin 3 is used. Make a hole, insert a pin, and caulk with a pipe to fix. Since the cooling means is also provided in the injection molding die itself at the bottom portion 7a of the cooling casting pin 7 as described above, it is not necessary to provide new cooling means, but in some cases, a direct cooling means may be provided. It may be provided.

In order to produce a molded body using the injection mold according to the present invention, a plasticized raw material (for example, polypropylene) heated and melted in a cylinder (not shown) is injected into the cavity 2 with a plunger, and the injection is performed for a predetermined time. After cooling and curing, the product is released. The boss 5 is a boss hole forming cast pin 3
Also, since the cooling casting pin 7 efficiently cools from both sides, tearing due to insufficient cooling does not occur at the time of mold release.

Next, an example of the molded article according to the present invention will be described. FIG. 2 is a partial cross-sectional view (a) showing an example of the molded body of the present invention and a partial perspective view (b) of the boss portion 5 provided on the core material 9.
It is. In FIG. 1A, a molded body 8 is formed by adhering a skin 10 made of vinyl chloride on a core material 9 made of, for example, polypropylene produced by the injection mold. Such a molded body 8 is suitable for use as, for example, an instrument panel of an automobile. As shown in FIGS. 2A and 2B, the core material 9 is provided with a hole portion 11 formed by the cooling die pin 7 and a ventilation hole 12 connecting the outside. The ventilation hole 12 can be provided by, for example, attaching a blade having a width equal to the thickness of the cavity 2 to the cooling cast pin 7 and simultaneously molding the core material 9. If the vent hole 12 is provided in the core material 9, air is not trapped in the hole 11 when the skin 10 is attached, so that the skin 10 can be prevented from swelling.

FIG. 3 is a partial sectional view showing another example of the molded article according to the present invention. This molded body 13 is formed on the core material 9 made of polypropylene, for example, by the injection molding die,
It has a structure in which a foam layer 14 such as urethane foam is formed, and a vinyl chloride skin 10 is further laminated thereon. Like the above-mentioned molded body 8, this molded body 13 is also suitable for use in, for example, an instrument panel of an automobile.

An example of forming the molded body 13 will be described. First, the core material 9 is formed by the injection molding die, and the core material 9 is left on the movable die 1 as shown in FIG. The fixed mold 15 on which the epidermis 10 is set is put together. Then, the urethane foaming liquid is injected into the space formed between the core material 9 and the skin 10 (including the hole portion 11 formed by the cooling die pin 7) to form the foaming layer 14.

[0016]

As described above, according to the injection molding die of the present invention, the thick boss portion is efficiently cooled from both sides by the boss hole forming casting pin and the cooling casting pin having good thermal conductivity. Therefore, tearing does not occur due to insufficient cooling during mold release. Further, in the molded body, using a core material provided with a vent hole that connects the hole formed by the cooling casting pin and the outside, a skin layer is adhered to the core material to form a molded body. No air is trapped in the part. Therefore, the skin layer does not rise or dent due to a change in temperature.

Further, the skin and the molded body are set in a mold,
When a foaming agent is injected and integrated during this period, the tip of the cooling die pin is adjusted so as to oppose the tip of the boss hole forming die pin with a gap, and is formed by the cooling die pin. It is possible to prevent the foaming agent from leaking by allowing the formed hole to communicate only with the foam layer.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an example of an injection mold of the present invention.

FIG. 2 is a partial cross-sectional view (a) showing an example of the molded body and a partial perspective view (b) of a boss portion provided on the core material.

FIG. 3 is a partial cross-sectional view showing another example of the molded body.

FIG. 4 is a partial sectional view showing an example of a conventional injection mold.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Movable type, 2 ... Cavity, 3 ... Boss hole formation casting pin, 5 ... Boss part, 6, 15 ... Fixed type, 7 ... Cooling casting pin, 8, 13 ... Molded body, 9 ... Core material, 10 ... skin, 11 ...
Holes, 12: vents, 14: foam layer.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29K 105: 24 B29L 9:00 (56) References JP-A-55-53542 (JP, A) Opened 2-207958 (JP, A) Opened 1986-12714 (JP, U) Opened 62-185010 (JP, U) Opened 1986-12715 (JP, U) Opened actual 56-69421 (JP, U) JP, U) Actually open 61-164711 (JP, U) Actually open 58-123033 (JP, U)

Claims (3)

(57) [Claims] 1. An injection molding die in which one of a pair of dies for forming a cavity is provided with a boss hole forming casting pin, and the other of the pair of dies is provided with a cooling casting pin for cooling a boss portion, The boss hole forming casting pin and the cooling casting pin are made of a material having high thermal conductivity, which is an injection molding die. 2. A molded body obtained by adhering a skin layer on one surface of a core material molded by using the injection molding die according to claim 1, in a hole formed by the cooling die pin. Is a molded body characterized by having a vent hole connecting the hole and the outside. 3. In a molded body in which a foam layer and a skin layer are laminated on one surface of a core material molded by using the injection molding die according to claim 1, the tip of the cooling die pin has a gap. A molded product, characterized in that the hole portion formed by the cooling casting pin communicates only with the foam layer by facing the tip of the boss hole forming casting pin.