JPH0584208B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a blow molding method for synthetic resin molded products, and more specifically, to obtain a synthetic resin blow molded product with higher transparency. This is the purpose.

[Conventional technology]

A cylindrical parison extruded from an extrusion molding machine is held between two split molds, and blow air, which is pressurized air, is injected into the parison held between the two split molds to form the parison into a bottle. BACKGROUND ART A molding method of blow molding a molded article such as a body is known as a blow molding method.

Conventionally, this type of blow molding method involves blow molding the parison into a molded product and then cooling both molds to cool and harden the molded product, or cooling both molds in advance and then cooling and hardening the molded product. Cooling and hardening of the molded product was achieved by contacting the blow-molded molded product with the mold.

As described above, in the conventional blow molding operation method, cooling and hardening of the blow molded molded product was achieved only by the two molds, and therefore the molded product was not necessarily cooled sufficiently.

[Problem that the invention seeks to solve]

As described above, in the conventional blow molding method, since the molded product was not sufficiently cooled, it was not possible to obtain a sufficiently transparent molded product, and only a slightly cloudy product could be molded.

In addition, since it takes time for the molded product to harden due to cooling, a relatively long cooling time is required to remove the molded product from both molds after the blow molding operation is completed, which results in the completion of molding of one blow molded product. It took a long time to complete the process, which was a major obstacle to improving productivity.

[Means and actions for solving problems]

The present invention was devised to solve the problems and dissatisfied points in the conventional examples described above, and is designed to directly cool a blow-molded product with cooling water, thereby achieving rapid cooling of the blow-molded product. be.

Hereinafter, the blow molding method according to the present invention will be explained with reference to the drawings showing one embodiment of the method according to the present invention.

The blow molding method according to the present invention is a method for blow molding a blow molded product S made of a crystalline synthetic resin material, and immediately after the completion of the blow molding operation by press-fitting blow air AB, blow air BA and air are added into the molded product S. The molded product S is rapidly cooled by injecting cooling water W at approximately the same pressure.

That is, a cylindrical parison P extruded from a die head 1 of an extruder is held between the molds 2 and 2, and then a blow nozzle 3 is inserted into the parison P held between both molds 2. insert,
Blow air BA is press-fitted into the parison P through the inserted blow nozzle 3, and the parison P is blow-molded into a formed article S.

When the blow molding operation from the parison P to the molded product S is completed, cooling water W for cooling is immediately injected and filled into the molded product S at a pressure almost equal to that of the blow air BA, and this molding is completed. Product S is rapidly cooled.

The reason why the cooling water W is filled into the molded product S at a pressure substantially equal to that of the blow air BA is to prevent the molded product S from shrinking and deforming due to rapid cooling by the cooling water W.

Once the molded product S has been rapidly cooled by the cooling water W, the cooling water W is drained from the molded product S, the molded product S is released from both molds 2, and the molded product S is blown. Molding is completed.

〔Example〕

In the illustrated embodiment, the blow nozzle 3 has a double pipe structure, and the blow air BA for blow molding the parison P into the molded article S is press-fitted into the parison P from the central passage of the blow nozzle 3.

Cooling water W is injected into the molded product S immediately after blow molding is completed using this blow air BA.
is injected into the molded product S from the center passage of the blow nozzle 3 in the same way as the blow air BA described above, but the blow air BA in the molded product S is injected into the upper end of the blow nozzle 3 in the molded product The air is discharged from an open air outlet 4 through an outer passage of the blow nozzle 3.

When the cooling water W is injected into the molded product S, the cooling water W is filled into the molded product S at a pressure substantially equal to that of the blow air BA.

Once the molded product S has been rapidly cooled by injecting and filling the cooling water W', the discharge air HA is press-fitted into the molded product S through the outer passage of the blow nozzle 3, and the molded product of the discharge air HA is By press-fitting into the molded product S, the cooling water W is drained out of the molded product S through the central passage of the blow nozzle 3.

Once the cooling water W has been drained from the molded product S, both molds 2 are opened and the molded product S is released.
The molding operation of the molded product S is completed.

〔Effect of the invention〕

In this way, the blow molding method according to the present invention
Cooling water W is injected and filled into the molded product S that has just completed the blow molding operation using the blow air BA to rapidly cool the molded product S, so the transparency (microcrystalline) of the crystalline synthetic resin material that is the molding material is improved. This results in a significant increase in the molded product S with high transparency.

Further, since the molded product S is forcibly rapidly cooled by the cooling water W, the cooling rate of the molded product S is extremely fast, and therefore the molded product S can be cooled and hardened within a short time.

As is clear from the above explanation, the blow molding method according to the present invention can obtain a blow molded product with extremely high transparency, and can significantly shorten the time required to mold one blow molded product. Therefore, it exhibits many excellent effects such as being able to increase the productivity of blow molded products.

[Brief explanation of the drawing]

The drawings show an example of the operating sequence of the method of the present invention, in which Fig. 1 shows the extrusion molding state of the parison, Fig. 2 shows the clamping state of both molds, and Fig. 3 shows the blow molding operation state. FIG. 4 shows the state of rapid cooling operation by injecting and filling the cooling water, FIG. 5 shows the state of discharging the cooling water, and FIG. 6 shows the state of completion of draining the cooling water from the molded product. Explanation of symbols: 1; Die head; 2; Mold; 3;
Blow nozzle, 4; air outlet, P; parison,
S: Molded product, W: Cooling water, BA: Blow air,
HA; Exhaust air.

Claims (1)

[Claims] 1 A method for blow molding a blow molded product made of a crystalline synthetic resin material, in which immediately after the blow molding operation is completed by press-fitting blow air into the molded product,
A blow molding method for a synthetic resin molded product, in which the molded product is rapidly cooled by injecting and filling cooling water at approximately the same pressure as the blow air.