JPS591211A - Molding method of synthetic resin bottle like vessel - Google Patents

Abstract

PURPOSE:To obtain a vessel with a uniform thickness by a method wherein a heated synthetic resin sheet is stretched on the upper part of a mold, this sheet is pushed up by compressed air at the circumferential part of the opening of the upper end of the mold, the before-mentioned sheet is pushed by a plug into the mold and then compressed air is blown in from the plug side. CONSTITUTION:A heated synthetic resin sheet A is stretched on the upper part of a mold 1, said sheet A is pushed up by compressed air from compressed air holes 1a at the circumferential part of the opening of the upper end of the mold 1, pushed by a plug 4 into the mold 1 and then compressed air is blown from the compressed air holes 4a on the plug 4 side to attach the before-mentioned sheet A closely to the inside of the mold 1. In this method, a synthetic resin vessel B with a large and uniform thickness can be blow-molded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding a synthetic resin bottle-shaped container, and more particularly to a method for forming a bottle-shaped container from a thermoplastic synthetic resin sheet to have uniform wall thickness at each part.

Using a mold, a heated thermoplastic synthetic resin sheet (hereinafter simply referred to as a sheet) is fixed on the top surface of the mold, the sheet is pushed into the mold from above using a plug, and compressed air is blown from the plug side to push the sheet into the inner surface of the mold. A method is known in which the material is molded in close contact with the material and then cooled.

This method is relatively common, but especially for bottle-shaped containers with a small mouth and a large bottom, only the small portion pushed down through the opening of the sheet mold is used. As a result of being subjected to molding of an enlarged body, even if a plug is used, only a thin molded product can be obtained, and the molded product tends to become thinner toward the bottom.

The present inventor has completed the present invention as a result of intensive research into a method for improving such conventional drawbacks and obtaining a molded article as thick as possible and having a uniform thickness from a single sheet.

That is, the gist of the present invention is to provide a method for forming a bottle-shaped container by stretching a heated synthetic resin sheet above a mold, pushing it into the mold with a plug, and then blowing compressed air from the plug side. Between the upper ends of the resin sheet mold
The means for pushing the sheet upward using a synthetic resin bottle-shaped container characterized by pushing the sheet into the mold with a plug while pushing up the peripheral part of one part using compressed air is not particularly limited, but for example, the means for pushing the sheet upward between the top surface of the mold and For sealing and fixing the sheet by sandwiching it, four parts are formed on the bottom surface of the seal plate in the area corresponding to the area around the mold opening, and using this seal plate, the sheet is sealed at the top of the mold, The periphery of the sheet can be easily pushed up by blowing compressed air upward into the circular portion of the seal plate from below the sheet. Examples of the synthetic resin sheet used include sheets made of commonly used 1a resins such as vinyl chloride resin, polyethylene, polypropylene, polystyrene, and polycarbonate, and either a single sheet or a laminate thereof can be used.

An example of the embodiment will be specifically described below with reference to the drawings.

The drawings are schematic diagrams showing an example of the implementation of the present invention, in which Fig. 1 is a sectional view showing the state before the plug is lowered, Fig. 2 is a sectional view while the plug is being lowered, and Fig. 3 is a sectional view when it is molded. be. First, as shown in FIG. 1, a heated sheet (A) is placed on the upper surface of a mold 1 (a two-piece mold), and the sheet is pressed and fixed onto the upper surface of the mold by a sealing plate 2 from above. This sealing plate 2 has a plug 4 which can be freely lowered through an opening provided at a position corresponding to the opening of the mold 1, and four parts are formed on the lower surface around this opening, and a plug 4 is formed around the recessed part. is provided with a gasket 3 for pressing the sheet. Then, the sheet A is pushed into the mold 1 by the plug 4. At the same time, compressed air is blown into the upper surface of the mold 1 from the compressed air hole 1a, and the area around the upper end of the mold of the sheet A is moved upward, that is, into the space formed by the recess of the seal plate! I'll push it inside. On the other hand, as shown in Figure 2, the plug 4
are successively lowered into the mold 1. As a result, the peripheral part of the sheet A is pushed up and smoothly extends into the mold 1 as the plug 4 descends without coming into close contact with the upper end surface of the mold 1, and the sheet around the upper opening of the mold becomes thin. Stretched. The plug 4 descends to the lowest part in the mold, and the plug 4 and seal plate 2 are stopped by the plug stopper 4'.
When the gap is sealed, compressed air is then discharged from the pressurized air hole 4a of the plug 4 as shown in FIG. . lb is a vacuum hole through which vacuum suction is simultaneously performed during the cooking process. Note that at this time, the compressed air 1a is closed.

Although not shown, the mold is provided with a jacket for cooling water, air, etc. to improve the cooling effect. After cooling, the molded body is taken out using a mold and punched into a predetermined shape around the mouth of the main body, and the required finishing is performed as usual.

In the above embodiment, the shape and size of the four parts of the seal plate 2 are arbitrarily determined depending on the material of the seal and the shape of the molded body, but the sheet is blown into the air hole 1a to prevent the sheet from adhering to the inner surface of the seal plate. It is important to push it up, and the inner surface may be treated with adhering pressure such as Teflon processing or uneven formation.

According to the present invention, the peripheral portion of the sheet, which was conventionally pinched between the upper end surfaces of the mold and not stretched and was not used for main body molding, is stretched extremely thin and is smoothly introduced into the mold as the plug descends. Since it is used for main body molding, the material can be used effectively and a molded product with a thick and uniform wall thickness can be obtained.

According to experiments, a molded body having the same wall thickness as obtained using a sheet of 1 sm thickness using the conventional method was found to have a thickness of 0.8 sm according to the present invention.
It can be obtained by a sheet with a thickness of mm.

As described above, the present invention provides a method for molding a bottle-shaped article having a relatively small opening with respect to a main body from a sheet.
It is extremely beneficial and its effects are remarkable.

[Brief explanation of drawings]

The drawings are schematic diagrams showing an example of the implementation of the present invention, in which Fig. 1 is a sectional view showing the state before the plug is lowered, Fig. 2 is a sectional view while the plug is being lowered, and Fig. 3 is a sectional view when it is molded. be. l... Molding mold, 1a... Pressurized air hole, 2 river seal plate!・
...Space part, 3...Putskin, 4...' Plug, 4
a... Pressure hole Figure 1 Figure 2

Claims (1)

[Claims] A method of forming a bottle-shaped container by stretching a heated synthetic resin sheet above a mold, pushing it into the mold with a plug, and then blowing compressed air from the plug side to bring the sheet into close contact with the mold, A method for molding a synthetic resin bottle-shaped container, which comprises pushing the synthetic resin sheet into the mold with a plug while pushing the peripheral portion of the upper end opening of the synthetic resin sheet upward with compressed air.