JPH05220777A - Method for molding synthetic resin material - Google Patents

Abstract

PURPOSE:To enhance the strength of a molded product and to select flexibility or the touch by forming a gas channel to the interior of the resin within a mold by hollow injection molding and discharging the gas to inject a filling material in a part of the gas channel or the whole thereof before demolding. CONSTITUTION:A thermoplastic resin P is injected in a mold 3 from the injection nozzle of an injection machine 2 and gas G is injected in the resin P through the injection nozzle. After cooling, the injection machine 2 is allowed to recede to discharge the gas G. Next, a filling material M is injected in a gas channel T from an injector 4. A filling material M composed of a thermoplastic resin may be injected using the injection machine 2 without using the separate injector 4. When the gas G is introduced into the thermoplastic resin within the gas channel T under pressure, a resin layer can be laminated to the inside of the molded resin P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a synthetic resin material. More specifically, it relates to improvement of a so-called hollow injection molding method for a synthetic resin material, which is a combination of injection molding and pressurization with gas.

[0002]

2. Description of the Related Art Conventionally, as a method of molding a synthetic resin material,
For example, the one shown in FIG. 7 is known.

In this conventional method for molding a synthetic resin material, an injection machine 2 in which a gas unit 1 for supplying a gas (nitrogen gas) G under pressure is connected to an injection nozzle for injecting a thermoplastic synthetic resin material P is used. The mold 3 as shown in FIG. 7 (A).
After injecting the thermoplastic synthetic resin material P from the injection nozzle of the injection machine 2, the gas is injected into the synthetic resin material P from the gas unit 1 through the injection nozzle of the injection machine 2 as shown in FIG. G is press-fitted, and the synthetic resin material P is cooled while maintaining the pressurized state of the gas G. Then, as shown in FIG. 7C, the injection machine 2 is retracted from the mold 3 and the synthetic resin material P is removed. The gas G is discharged, the mold 3 is released as shown in FIG. 7 (D), and the molded product P'is taken out. A hollow gas channel T is formed inside the molded product P ′ molded in this way.

This conventional method for molding a synthetic resin material is called a so-called hollow injection molding method. The synthetic resin material P injected into the mold 3 is pressed from the inside by a pressure of gas G to form the molding surface of the mold 3. Since the pressure is applied to the molded product, there is an advantage that a molded product P ′ having good transferability can be obtained. In terms of practical use, it is used for preventing sink marks in a thick wall portion in an uneven thickness structure having a thin wall portion and a thick wall portion, and for providing a reinforcing rib structure with a gas channel T.

In such a conventional method for molding a synthetic resin material, since the gas channel T is formed inside the molded product P ', the weight balance of the molded product P'is better than that when the gas channel T is not formed. Although the design becomes troublesome, and if the molded product P ′ is provided in a vibrating portion, there is a problem that vibration resonates with the gas channel T, but the molded product taken out of the mold 3 and taken out. There is a problem in that it is difficult to perform a machining work for P'to solve such a problem. Further, as a result of the formation of the gas channel T, the strength of the product is affected, but in order to maintain the strength, the selection range of the synthetic resin material is narrowed, and there is a restriction that flexibility and tactile feel cannot be freely selected.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems and the like, and it is an object of the present invention to provide a method for molding a synthetic resin material capable of correcting a gas channel during molding. It is an issue. Another object of the present invention is to provide a molding method in which the flexibility and tactile feel of a product can be freely selected while maintaining the strength freely.

[0007]

In order to solve the above problems, the method for molding a synthetic resin material according to the present invention employs the following means.

That is, according to the first aspect of the invention, the gas is press-fitted into the thermoplastic synthetic resin material injected into the mold, and the synthetic resin material is cooled while maintaining the pressurized state of the gas. After cooling, the synthetic resin material is cooled. In the method of molding a synthetic resin material in which a gas channel is formed inside the molded product by discharging the gas inside the material and then releasing the mold to take out the molded product, It is characterized in that the filler is injected into a part or the whole of the inside of the gas channel before the mold release.

According to a second aspect of the present invention, in the method for molding a synthetic resin material according to the first aspect, the gas is pressed into the inside of the filler made of the thermoplastic synthetic resin material injected into the gas channel, and Cool the filler while maintaining the pressure,
The method is characterized in that the step of discharging the gas inside the filler after cooling and then releasing the mold to take out the molded product is performed at least once.

[0011]

According to the above-mentioned means, according to the first aspect, the filler is injected into a part or the whole of the inside of the gas channel, so that the correction processing for eliminating the gas channel or changing the structure of the gas channel is performed. It is possible to perform the correction processing of the gas channel without causing expansion deformation of the molded product by injecting the filler before the mold is released after the gas is discharged. The problem of providing a molding method of a synthetic resin material capable of correcting and processing a gas channel is solved. Further, since the filler is present, the strength can be easily maintained, and therefore, the selection range of the synthetic resin material on the surface side can be remarkably widened.

According to the second aspect of the present invention, in the operation of the first aspect, the correction process of the gas channel is the same as the conventional process of injecting and pressurizing the synthetic resin material.

[0013]

EXAMPLES Examples of the method for molding a synthetic resin material according to the present invention will be described below with reference to FIGS.

FIG. 1 shows a first embodiment of a method for molding a synthetic resin material according to the present invention.

In this embodiment, after discharging the gas G as shown in FIG. 1 (A) (corresponding to FIG. 7 (C) of the above-mentioned conventional example), as shown in FIG. Injects the filler M into the gas channel T by a separate injector 4.

This filling material M is injected by an injection machine 4 such as an injection machine.
It may be a thermoplastic synthetic resin that is injected and injected, or may be formed of a material different from the synthetic resin material in the form of granules, pellets, powder, or the like. Also, this filler M
The injection amount of the gas into the gas channel T may be the entire gas channel T as shown in the figure, or may be a part thereof. If the filler M is granular or the like, as shown in FIG.
If the filler M is injected simultaneously with the discharge of the gas G as shown in (A) and the reduced pressure inside the gas channel T is used, the filler M can be easily injected.

When the filling material M is filled in the gas channel T as described above, the gas channel T disappears (all is injected) or the structure of the gas channel T is changed (partial injection). Even if the gas channel T is filled with the filling material M, the synthetic resin material P (molded product P (molded product P) is injected because the thermoplastic synthetic resin material P injected into the molding die 3 is still surrounded by the molding die 3. ') Does not expand and deform.

After the injection of the filler M, the filler is cooled if necessary, and then the mold 3 is released as shown in FIG. 1 (C) to take out the molded product P '. ..

FIG. 2 shows a third embodiment of the method for molding a synthetic resin material according to the present invention.

In this embodiment, the injector 4 of the first embodiment described above is abolished, and the filler M made of a thermoplastic synthetic resin material is used by using the injector 2 as shown in FIG. 2 (B). The gas is injected into the gas channel T.

According to such an embodiment, since the injector 4 is not particularly required, there is an advantage that the device structure is simplified. It should be noted that such use of the injection machine 2 can be handled by a simple modification of the injection nozzle of the existing injection machine 2.

FIG. 3 shows a third embodiment of the method for molding a synthetic resin material according to the present invention.

In this embodiment, after the filling material M of the second embodiment is injected into the gas channel T, as shown in FIG.
As shown in FIG. 5, a gas is press-fitted into the filler M, and the same steps as the steps of the conventional molding method described above are repeated.

According to such an embodiment, a layer of the filler M can be laminated inside the thermoplastic synthetic resin material P. It should be noted that the layers of the filler M laminated by repeating the same steps as the steps of the conventional molding method described above are proportional.

FIG. 4 shows a fourth embodiment of the method for molding a synthetic resin material according to the present invention.

In this embodiment, the aforementioned injector 4 is used, and the gas unit 1 is connected to the mold 3 without being connected to the injection nozzle of the injector 2.

According to such an embodiment, there is an advantage that the injection amount of the gas G can be easily adjusted without being restricted by the injector 2. Two

In the molded product P'molded by the above-described embodiment, the gas channel T is corrected and the weight balance design of the molded product P'is complicated compared to the case where the gas channel T is not formed. Further, if the molded product P ′ is provided at the vibrating portion, problems such as vibration resonating with the gas channel T can be solved, and qualitative improvement can be obtained.

For example, in a molded product P'made of a resin tank of a radiator as shown in FIG. 5, a filler M made of a material having good heat insulation and hardness is provided in all of the gas channels T formed in the ribs on the periphery. By injecting, it is possible to prevent the ribs from being damaged due to caulking to the seat plate and to prevent deformation due to heating of the cooling water, and to protect the surroundings from the heated cooling water. Further, in a molded product P'comprising an automobile door handle as shown in FIG. 6, the thermoplastic synthetic resin material P on the outside is made of a flexible material, and the filler M laminated on the inside is made of a hard thermoplastic material. By making the color different from that of the resin material P, the grip feeling is improved, and the color appearance is also improved.

As described above, in the method for molding a synthetic resin material according to the present invention, the filler is injected into a part or all of the inside of the gas channel so that the gas channel disappears or the structure of the gas channel is improved. It is possible to perform correction processing such as changing, and by injecting the filling material before releasing the mold after discharging gas, correction processing of the gas channel can be performed without causing expansion deformation of the molded product. As a result, the gas channel can be corrected during the molding, and the gas channel can be continuously corrected in the conventional hollow injection molding process, so that the molding cost can be reduced.

Further, the molded product molded by this method has the effects that the strength can be easily improved and the flexibility and tactile feel of the product can be freely selected.

[Brief description of drawings]

FIG. 1 shows a first embodiment of a method for molding a synthetic resin material according to the present invention, and the order of steps is shown in (A) to (C).

FIG. 2 shows a second embodiment of the method for molding a synthetic resin material according to the present invention, and the order of steps is shown in (A) to (C).

FIG. 3 shows a third embodiment of the method for molding a synthetic resin material according to the present invention, and the order of steps is shown in (A) to (C).

FIG. 4 shows a first embodiment of the method for molding a synthetic resin material according to the present invention, showing one characteristic step.

FIG. 5 is a cross-sectional view showing the structure of a molded product molded by carrying out the present invention.

FIG. 6 is a cross-sectional view showing another example of FIG.

FIG. 7 shows a conventional example, and the order of steps is shown in (A) to (D).

[Explanation of symbols]

 1 Gas Unit 2 Injection Machine 3 Mold 4 Injection Machine G Gas M Filler P Thermoplastic Synthetic Resin Material P'Molded Product

Claims (2)

[Claims] 1. A gas is injected into a thermoplastic synthetic resin material injected into a mold, the synthetic resin material is cooled while maintaining the pressurized state of the gas, and the gas inside the synthetic resin material is cooled. By releasing the mold and taking out the molded product,
In a method of molding a synthetic resin material for forming a gas channel inside a molded product, a synthetic resin characterized by injecting a filler into a part or all of the inside of the gas channel before releasing from the mold after discharging gas. Forming method of material. 2. The method for molding a synthetic resin material according to claim 1, wherein the gas is pressed into the inside of the filler made of the thermoplastic synthetic resin material injected into the gas channel to maintain the pressurized state of the gas. Then, the step of cooling the filling material, discharging the gas inside the filling material after cooling, and releasing the mold to take out the molded product is carried out at least once.