JPH0686090B2 - Method and apparatus for molding synthetic resin bottle with pressure absorbing panel - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a bottle molding method and apparatus that absorbs a pressure inside a bottle by a deformation of a panel when the pressure inside the bottle changes.

[Conventional technology]

Conventionally, a synthetic resin bottle is used when the liquid filled in the bottle is cooled at a high temperature and the inside of the bottle is decompressed, or when the carbonated drink in the bottle is vaporized and the inside of the bottle becomes high in pressure. Is designed to absorb the above-mentioned pressure by deforming the bottle body, and an example thereof is Japanese Utility Model Laid-Open No. 57-180608.

In this publication, as shown in FIG. 5, a bottle body 20 is formed by a raised portion 21 and a pressure absorbing panel portion 22, and when the inside of the bottle is depressurized, the pressure absorbing panel portion 22 is deformed inward. It is something that is done.

[Problems to be solved by the invention]

In the bottle as shown in FIG. 5, the raised portion 21 of the bottle body 20 and the pressure absorbing panel portion 22 are formed to have substantially the same thickness.
Since the raised portion 21 is a raised portion that prevents the bottle body portion 20 from being deformed into a dogleg shape, the thickness of the raised portion 21 cannot be made very thin. Then, the pressure absorbing panel portion 22 does not become too thin, and only the pressure absorbing panel portion 22 does not easily deform.

The present invention has been made in view of the above matters, and a method and a device for forming only a deformed portion of a bottle thinly so that only a necessary portion is easily deformed in accordance with a change in pressure inside the bottle. To do this is a technical issue.

[Means for solving problems]

The first invention is a method for molding a synthetic resin bottle provided with a pressure absorbing panel, which comprises an inner surface 4 of a columnar portion 3 and a nesting member 6.
The preform is set in the blow molding die 1 whose inner surface 7 and the inner surface 7 are located on substantially the same circumference, and compressed air is blown into the preform to expand the preform. The outer surface of the preform is attached to the inner surface 7 of the insert 6, and then the insert 6 is advanced into the blow molding die 1 to attach the raised portion 21 and the pressure absorbing panel portion 22 to the bottle body 20. To form.

The second invention is a molding apparatus for a synthetic resin bottle provided with a pressure absorption panel, and in a blow molding die 1 having a cavity 2 formed therein, the bottle body 20 of the bottle to be molded contacts. The part is composed of the inner surface 4 of the columnar part 3 and the inner surface 7 of the insert 6, and the insert 6 is provided so as to be able to advance and retreat in the radial direction of the cavity 2 of the blow molding die 1.

[Action]

According to the present invention, when the preform is set in the blow molding die 1 and compressed air is blown into the preform, the preform expands and the outer surface sticks to the inner surface 7 of the insert 6, and the preform has unevenness. There is almost no, and the thickness is formed into a cylindrical shape having a substantially uniform thickness. Next, when the insert 6 is advanced into the blow molding die 1, the pressure absorbing panel portion 22 of the bottle body 20 is recessed inward as shown in FIG. When recessed inward, the corner portion 23 of the bottle body portion 20 at the corner portion 9 of the nest 6 is circumferentially (third)
And the corner portion 23 is thinly formed.

[Examples] A molding apparatus and a molding method used in the present invention will be described below with reference to the examples shown in FIGS. 1 to 4.

In this molding apparatus, in a blow molding die 1 having a hollow portion 2 formed therein, a portion of a bottle to be molded which is in contact with a bottle body portion 20 is composed of an inner surface 4 of a columnar portion 3 and an inner surface 7 of a nest 6. I am configuring. Each end of the nest 6 is formed into an inclined surface 8 and the corner portion 9 is formed into a wide angle. Also,
The insert 6 is provided in the radial direction of the cavity 2 of the blow molding die 1 so as to be able to move forward and backward by using a hydraulic piston.

Then, in this molding method, first, polyethylene terephthalate is injection molded to form a preform,
The formed preform is set in a blow molding die 1 at a molding temperature, and compressed air is blown into the preform to expand the preform, so that the outer surface of the preform and the inner surface 4 of the columnar portion 3 and It is made to stick to the inner surface 7 of the insert 6, and then the insert 6 is advanced into the blow molding die 1 while maintaining the pressure of the compressed air at the same level as in the expansion stage to form a substantially cylindrical bottle barrel. It was possible to obtain a bottle in which a raised portion (21) for retaining the shape of the entire bottle body (20) and a thin corner portion (23) that easily bends due to a change in internal pressure of the bottle were formed in the portion (20).

〔The invention's effect〕

According to the present invention, when a bottle is molded from a preform, it is formed by once forming it into a large-diameter tubular shape, then advancing the nest 6, and recessing the pressure absorbing panel portion 22 inward. The pressure absorbing panel portion 22 is formed so that 23 is stretched in the circumferential direction, and as a result, the bottle body portion 20 in which the corner portion 23 of the pressure absorbing panel portion 22 is thin is formed, and the pressure inside the bottle is reduced. It was possible to mold a bottle in which the pressure absorbing panel portion 22 was easily deformed in accordance with the change of.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part of an embodiment of a molding apparatus of the present invention, FIG. 2 is a half-cut sectional view thereof, FIG. 3 is a view for explaining a molding method, and FIG. 4 is a molded bottle. FIG. 5 is a cross-sectional view of a bottle molded by a conventional example. 1 ... Blow molding die, 2 ... Cavity part, 3 ... Column part, 4 ... Inner surface, 6 ... Nesting, 7 ... Inner surface, 20 ... Bottle body part, 21 ... Raised part, 22 …… Pressure absorption panel section.

Claims (2)

[Claims] 1. An inner surface 4 of a columnar portion 3 and an inner surface 7 of a nest 6.
And, the preform is set in the blow molding die 1 positioned on substantially the same circumference, and compressed air is blown into the preform to expand the preform,
The outer surface of the preform is adhered to the inner surface 7 of the insert 6, and then the insert 6 is advanced into the blow molding die 1 so that the bottle body 20 has a raised portion 21 and a pressure absorbing panel portion 22. Of forming a synthetic resin bottle equipped with a pressure absorbing panel for forming a container. 2. In a blow molding die 1 having a cavity 2 formed therein, a portion of a bottle to be molded which is in contact with a bottle body 20 is constituted by an inner surface 4 of a columnar portion 3 and an inner surface 7 of a nest 6. Then, the nest 6 is a synthetic resin bottle molding apparatus provided with a pressure absorbing panel provided so as to be able to advance and retreat in the radial direction of the cavity 2 of the blow molding die 1.