JPH08300393A - Injection-molded product - Google Patents

Abstract

PURPOSE: To provide an injection-molded product having a lower hole or hollow part for insertion capable of certainly fixing a part without generating a crack or the like. CONSTITUTION: In an injection-molded product 10 provided with an insertion lower hole for permitting the insertion of a metal part under pressure, a gas venting hole 12 is provided to the bottom part of the insertion lower hole 11 and facing 11a is provided to the top part thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection-molded article provided with an insert pilot hole for press-fitting a metal part or the like.

[0002]

2. Description of the Related Art Gas injection molding, which has become more popular than before,
This is a molding method of forming a hollow portion in a molded product by injecting a pressurized gas into a molten resin injected into a cavity of a mold from a tip of a gas nozzle provided in communication with the cavity. Regarding the molding method for forming the hollow portion, for example, as described in Japanese Patent Publication No. 3-47171, the weight of the molded product is reduced and the surface is modified. There is provided an injection molding method and apparatus in which a gas passage communicating with the cavity is provided in the gate portion or the mold, and the molten resin in the cavity is filled with the gas passage through the gas passage to form the hollow portion. Are known.

On the other hand, in an injection-molded article provided with an insert pilot hole for press-fitting a metal part or the like in a later step, the pilot hole is conventionally formed to be smaller than the part to be press-fitted, A method has been adopted in which parts are pressed into and fixed to the prepared hole by pressing a part using a press-fitting machine using air pressure or hydraulic pressure.

[0004]

However, when the component is press-fitted into the prepared hole provided in the injection-molded product as described above, the injection-molded product is performed at room temperature, so that the side surface of the component causes the prepared hole to be prepared. The side wall of is strongly pressed. As a result, there is a problem in that the side wall of the prepared hole is cracked by the action of stress, and the fixing force of the component is reduced, so that the inserted component is easily rotated or easily removed.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to solve these problems and prevent cracks and the like from occurring, so that parts can be reliably manufactured. (EN) An injection-molded product having a prepared pilot hole for insert or an injection-molded product having a hollow portion.

[0006]

The injection-molded article of the present invention according to claim 1 is an injection-molded article provided with an insert pilot hole for press-fitting a metal part or the like. It is characterized in that a gas vent hole is provided at the bottom and a counterbore is provided at the top.

Further, in the injection-molded article of the present invention as set forth in claim 2, the gas vent hole provided at the bottom of the prepared hole for insert of the injection-molded article as set forth in claim 1 forms a hollow portion. It is characterized by being used as a gas injection port for pressurized gas.

[0008]

In the injection-molded product of the present invention as defined in claim 1, since the gas vent hole is provided at the bottom of the pilot hole for insert, the air in the pilot hole is sealed when the metal part or the like is press-fitted. It is not compressed and is discharged from the gas vent hole, so that the metal parts and the like can be press-fitted easily and smoothly.

Further, when a metal part or the like is press-fitted, an unreasonable force does not act on the side wall of the prepared hole, and the prepared hole is securely fixed without being cracked. Furthermore, since the counterbore is provided at the top, molten resin at the time of press-fitting is prevented from accumulating in the counterbore and rising on the upper surface of the prepared hole, and a good insert molded product is obtained.

In the injection-molded article of the present invention as defined in claim 2, the gas vent hole provided at the bottom of the pilot hole for insert is a gas injection port for pressurized gas for forming a hollow portion of the injection-molded article. Therefore, processing such as cutting of the resin adhered to the injection port is unnecessary, and the cost of the injection molded product can be reduced. Further, it is not necessary to separately provide a gas injection port for pressurized gas, the structure of the mold is simplified, and the manufacturing cost can be reduced.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part showing an example of the injection-molded article of the present invention according to claim 1. In FIG. 1, 11 is
It is a pilot hole provided in the molded product body 10. The pilot hole 11
Is a cylindrical body that is provided so as to protrude from the molded product body 10 and has an inner diameter of circular cross section.

A metal cylindrical insert part 1 or 2 as shown in FIG. 2 is press-fitted into the prepared hole 11. Further, a gas vent hole 12 is provided on the molded product body 10 side, which is the bottom of the prepared hole 11.

Therefore, when the insert part 1 or 2 is press-fitted into the pilot hole 11, the air in the pilot hole 11 is discharged from the gas vent hole 12 without being compressed in a sealed state. The component 1 or 2 can be easily press-fitted.

A counterbore 11a is provided on the top of the prepared hole 11 to form a pool of molten resin on the side wall of the prepared hole 11 when the heated insert part 1 or 2 is press-fitted. Therefore, it is possible to obtain an insert-molded product having a good appearance without the molten resin rising above the prepared hole 11.

Further, when the insert component 1 or 2 is press-fitted, there is an effect of preventing the tip periphery of the prepared hole 11 from being damaged by the tip of the insert component 1 or 2 due to a slight positional deviation or the like. .

The relationship between the inner diameter of the prepared hole and the outer shape of the insert part when press-fitting the insert part is a very important factor, and when the insert part is heated and press-fitted, the insert part abuts. It becomes a particularly important factor in melting the side wall of the prepared hole and bringing it into close contact with the insert part.

Therefore, as shown in FIGS. 1 and 2, the inner diameter A of the prepared hole 11, the inner diameter B and depth F of the expanded diameter portion 11a, the depth E of the prepared hole 11, and the knurled surface on the surface. 1a, 2
The relationship between the outer diameter C of the insert parts 1 and 2 having a and the fitting depth D is A = C-0.3 mm to C-0.2 mm B = C + 1 mm E = D + 0.5 mm or more F = 0.5 + 0. It is preferable to set it to 5 mm to 0.5 mm.

FIG. 3 is a sectional view of a main part showing another example of the injection-molded article of the present invention according to claim 1. In FIG.
Reference numeral 21 is a prepared hole provided in the molded product main body 20. The prepared hole 21 projects from the molded product main body 10 and has a bottom portion 21a.
Is provided and is a cylindrical body having an inner diameter of circular cross section.

Similar to the embodiment shown in FIG. 1, a metal cylindrical insert member 1 or 2 as shown in FIG. 2 is press-fitted into the prepared hole 21.

A gas vent hole 22 is provided at the bottom of the pilot hole 21. Therefore, when the insert component 1 or 2 is press-fitted into the pilot hole 21, the air in the pilot hole 21 is discharged from the gas vent hole 22 without being compressed in a sealed state. Alternatively, the press-fitting of 2 can be easily performed.

A counterbore 21a is provided at the tip of the prepared hole 21 and serves as a pool of molten resin on the side wall of the prepared hole 21 when the heated insert part 1 or 2 is press-fitted. Therefore, it is possible to obtain an insert-molded article having a good appearance without the molten resin rising above the prepared hole 21.

When the insert part 1 or 2 is press-fitted, care should be taken to prevent the tip periphery of the prepared hole 11 from being damaged by the end part of the insert part 1 or 2 due to a slight positional deviation or the like. Has been done.

Also in this embodiment, the insert parts 1,
Alternatively, it is preferable that the press-fitting of 2 and the dimensional relationship of the prepared hole 21 are the same as those in the above-described embodiment.

FIG. 4 is a sectional view of a main part showing an example of the injection-molded article of the present invention according to claim 2. In FIG. 4, 3
Reference numeral 1 denotes a pilot hole provided in the molded product body 30, and this pilot hole 31 is provided so as to project from the molded product body 30, and is a tubular body having an inner diameter with a circular cross section. Similar to the above-described embodiment, a metal cylindrical insert part 1 or 2 as shown in FIG. 2 is press-fitted into the prepared hole 31.

A gas inlet 32 for injecting a pressurized gas is provided at the bottom of the prepared hole 31, and a gas nozzle (not shown) provided on the prepared hole 31 side from the gas inlet 32 at the time of molding. Pressurized gas is injected into the molten resin in the cavity for molding the molded article body 30 from the tip of the hollow part 3
0a is formed.

A counterbore 31a is provided at the tip of the prepared hole 31 and serves as a pool of molten resin on the side wall of the prepared hole 31 when the heated insert part 1 or 2 is press-fitted.

When the insert part 1 or 2 is press-fitted, care should be taken to prevent the tip periphery of the pilot hole 31 from being damaged by the end part of the insert part 1 or 2 due to a slight positional deviation or the like. Has been done.

Therefore, as described above, the gas vent hole provided at the bottom of the pilot hole 31 for insert has the gas injection port 32 of the pressurized gas for forming the hollow portion of the injection molded product.
Therefore, it is not necessary to separately provide a gas injection port for pressurized gas, and the structure of the mold can be simplified.

[0029]

In the injection-molded product of the present invention as set forth in claim 1, since the gas vent hole is provided at the bottom of the pilot hole for insert, the air in the pilot hole is hermetically sealed when a metal part or the like is press-fitted. Without being compressed, the gas is discharged from the gas vent hole, and the metal parts or the like can be easily press-fitted smoothly.

Further, when a metal part or the like is press-fitted, an unreasonable force does not act on the side wall of the prepared hole, and the prepared hole is securely fixed without cracking. Furthermore, since the counterbore is provided at the top, molten resin at the time of press-fitting is prevented from accumulating in the counterbore and rising on the upper surface of the prepared hole, and a good insert molded product is obtained.

In the injection-molded article of the present invention as defined in claim 2, the gas vent hole provided at the bottom of the pilot hole for insert has a gas injection port for pressurized gas for forming a hollow portion of the injection-molded article. Therefore, processing such as cutting of the resin adhered to the injection port is unnecessary, and the cost of the injection molded product can be reduced. Further, it is not necessary to separately provide a gas injection port for pressurized gas, the structure of the mold is simplified, and the manufacturing cost can be reduced. Therefore, it is suitable as an injection-molded product provided with a pilot hole for insert.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part showing an example of an injection-molded article according to the present invention as set forth in claim 1.

FIG. 2 is a side view of an insert component that is fitted into the injection-molded product of FIG.

FIG. 3 is a sectional view of an essential part showing another example of the injection-molded article of the present invention according to claim 1.

FIG. 4 is a sectional view of an essential part showing an example of the injection-molded article of the present invention according to claim 2.

[Explanation of symbols]

 1, 2 Insert parts 1a, 2a Knurled surface 10, 20, 30 Molded product body 11, 21, 31 Prepared hole 11a, 21b Counterbore 12,22 Gas vent hole 21a Bottom part 30a Hollow part 32 Gas inlet A, B Inner diameter C Outer diameter D Fitting depth E, F Depth

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location // B29C 65/64 B29C 65/64 B29K 105: 22

Claims (2)

[Claims] 1. An injection-molded article having an insert pilot hole for press-fitting a metal part or the like, wherein a gas vent hole is provided at the bottom of the insert pilot hole and a counterbore is provided at the top. A characteristic injection molded product. 2. The injection-molded article according to claim 1, wherein a gas vent hole provided at the bottom of the pilot hole for insert serves as a gas inlet for pressurized gas for forming a hollow portion. .