JP3166440B2 - Hollow injection molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow injection molding method in which a gas is introduced into a resin material in a cavity during injection molding of a resin molded product, thereby forming a hollow portion in a part of the resin molded product. It relates to a molding device.

[0002]

2. Description of the Related Art A hollow injection molding apparatus of this type has a structure shown in FIG. The hollow injection molding apparatus shown in FIG. 2 is for molding the bumper fascia 1 of the automobile bumper shown in FIGS. 3 and 4, and is formed by a core block (movable mold) 2 and a cavity block (fixed mold) 3. The cavity 4 to be filled is filled with the resin material through a gate (not shown), and a predetermined timing, for example, immediately after the injection of the resin material is completed. An inert gas typified by nitrogen gas is introduced into the above resin material.

The inert gas introduced into the cavity 4 is a part of the part to be formed into the molded article 1, which has a small flow resistance, that is, the center of the thick part 7, which is relatively delayed in cooling and solidification. The gas spreads through the portion, and the gas applies internal pressure to the resin material to assist the flow of the resin material and at the same time prevent the occurrence of molding defects such as sink marks. Is left as a hollow portion 8 as it is, so that it functions as a reinforcing rib.

On the other hand, the gas nozzle 5 is heated and maintained at a predetermined temperature by a heater 9 and is driven forward and backward by an actuator such as an air cylinder (not shown) as shown in FIG. In the illustrated mold open state, the gas nozzle 5 is separated from the gas inlet 6.

That is, by pressing the gas nozzle 5 against the gas inlet 6 only in the mold clamping state shown in FIG. 1B, the resin material entering the gas inlet 6 is softened and melted by the heat of the gas nozzle 5. When the gas is introduced, the gas is smoothly introduced from the gas nozzle 5 to the center of the thick portion 7, while the gas nozzle 5 is retracted from the gas injection port 6 in the mold open state shown in FIG. This prevents the mold temperature from rising over a wide range of the core block 2 around the gas inlet 6 (similar structures are disclosed in JP-A-4-78511 and JP-A-5-78511). -31746).

[0006]

However, the conventional structure as described above requires not only an actuator for driving the gas nozzle 5 to move forward and backward, but also a gas inlet 6 for starting the supply of gas to the gas nozzle 5. Therefore, an interlock mechanism for detecting whether or not the gas nozzle 5 is properly pressed is required, which complicates the mold structure.

In addition, since the gas nozzle 5 is embedded in the core block 2, there is a problem that workability at the time of maintenance and inspection of the gas nozzle 5 itself is poor.

The present invention has been made in view of the above problems, and has simplified the structure by eliminating actuators and the like, which were conventionally required, and also improved the workability during maintenance and inspection. An object of the present invention is to provide a structure of a hollow injection molding device.

[0009]

According to the present invention, a cavity of an injection molding die is filled with a resin material, and a gas is introduced into the resin material in the cavity from a gas nozzle facing the cavity to form a molded product. In a hollow injection molding apparatus in which a hollow portion is formed in a portion, one of a core block and a cavity block forming the injection molding die is subjected to a mold clamping and mold opening operation in accordance with a mold closing operation. The gas nozzle that moves in the mold clamping and mold opening directions is elastically supported, and when the mold clamping is completed, the gas injection port of the gas nozzle positioned between the core block and the cavity block faces the cavity. It is characterized by.

[0010]

According to this structure, the gas nozzle has a substantially floating structure. During the mold opening operation, the gas nozzle is separated from the core block or the cavity block provided with the gas nozzle so as to float from the mating surface, while the mold is opened. At the time of tightening, the gas nozzle is positioned between the mold mating surfaces of the core block and the cavity block, so that gas can be introduced into the resin material in the cavity.

[0011]

FIG. 1 is a view showing an embodiment of the present invention, in which parts common to those of the conventional structure shown in FIG.

As shown in FIG. 1, of the core block 2 and the cavity block 3 forming an injection mold, a gas nozzle 10 is provided on the mold mating surface 3a on the cavity block 3 side.
Is arranged. More specifically, a nozzle receiving recess 11 large enough to receive the gas nozzle 10 is formed on the mold mating surface 3 a of the cavity block 3 so as to be continuous with the cavity 4. The gas nozzle 10 is clamped through the coil spring 13 and the coil spring 13 so as to be movable forward and backward in the mold opening direction.

In the state before the mold clamping, FIG.
As shown in FIG. 5, the gas nozzle 10 floats and protrudes from the nozzle receiving recess 11 toward the core block 2 by the force of the coil spring 13 while the mold block shown in FIG. The gas nozzle 10 sandwiched between the mold mating surfaces 2a, 3a is correctly positioned in the nozzle receiving recess 11, and the gas nozzle 10
The gas injection port 10a at the tip of is formed so as to face a portion of the cavity 4 corresponding to the thick portion 7 of the molded article 1.

Further, the gas nozzle 10 is provided with a heater 9 as in the prior art, and the gas nozzle 10 is turned on only when the gas nozzle 10 is floating from the nozzle receiving recess 11 as shown in FIG. The gas supply hose 14, which is heated by the heater 9 and connected to the gas nozzle 10, is received by the groove 15 on the cavity block side during mold clamping.

The gas nozzle 10 may be provided on the core block 2 side instead of the cavity block 3 side.

In the hollow injection molding apparatus configured as described above, when the state shifts from the state shown in FIG. 1A to the mold clamping operation, the mold mating surface 2a of the core block 2 comes into contact with the gas nozzle 10 on the way. Then, the gas nozzle 10 is gradually pushed into the nozzle receiving recess 11. And core block 2
When the mold and the cavity block 3 are completely clamped, the gas nozzle 10 is correctly positioned and positioned in the nozzle receiving recess 11, and in this state, the gas inlet 10a of the gas nozzle 10 faces the cavity 4 for the first time.

Thereafter, a resin material is injected and filled into the cavity 4 in the same manner as in the prior art.
Gas is introduced into the resin material inside. As a result, a hollow portion 8 is formed in a portion of the molded article 1 which is to become the thick portion 7 by introducing gas.

When the mold is opened to take out the molded product 1 after a predetermined time in the mold clamping state, the gas nozzle 10 gradually comes out of the nozzle receiving recess 11 by the force of the coil spring 13 and finally (FIG. It returns to the state of A).

[0019]

As described above, according to the present invention, the mold clamping,
The floating structure in which the elastically supported gas nozzle moves forward and backward in response to the mold opening operation eliminates the need for actuators and interlock mechanisms that were previously required for driving the gas nozzle forward and backward, thus reducing the mold structure. Can be simplified.

Further, in the mold open state, the gas nozzle floats up from the mold mating surface of the core block or the cavity block and is exposed to the outside, so that maintenance and inspection work of the gas nozzle can be performed very easily. Thus, there is an effect that the troublesome hole processing for inserting and arranging the gas nozzle is not required.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of the present invention, wherein (A) is a cross-sectional view of a main part before mold clamping, and (B) is a cross-sectional view of a main part after mold clamping.

FIG. 2 is a view showing an example of a conventional hollow injection molding apparatus;
(A) is a sectional view of a main part before mold clamping, and (B) is a sectional view of a principal part after mold clamping.

FIG. 3 is a perspective view of a bumper fascia which is a molded product.

FIG. 4 is a sectional view taken along the line aa of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Resin molded article (bumper fascia) 2 ... Core block 3 ... Cavity block 2a, 3a ... Matching surface 4 ... Cavity 7 ... Thick part 8 ... Hollow part 10 ... Gas nozzle 10a ... Gas inlet 11 ... Nozzle receiving concave part 12 ... Support rod 13 ... Coil spring

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (1)

(57) [Claims] A cavity is formed in a part of a molded product by filling a resin material into a cavity of an injection mold and introducing a gas into the resin material in the cavity from a gas nozzle facing the cavity. According to the hollow injection molding apparatus described above, one of the core block and the cavity block forming the injection molding die is provided with a mold clamping and mold opening direction in accordance with a mold clamping and mold opening operation. A hollow injection molding apparatus, wherein a moving gas nozzle is elastically supported and a gas injection port of the gas nozzle positioned and sandwiched between the core block and the cavity block faces the cavity when mold clamping is completed. .