JPS62152718A - Method of molding synthetic resin bottle equipped with pressure absorbing panels and device thereof - Google Patents

Abstract

PURPOSE:To mold a bottle easily deformable in response to the change in inner pressure by a structure wherein liners are provided so as to be able to advance and retreat radially to the mold cavity part in a blow mold. CONSTITUTION:First, a preform of polyethylene terephthalate made by injection molding is set in a blow mold 1 at molding temperature so as to be expanded by the compressed air blown in it in order to spread the outer surface of the preform on the inner surfaces 7 of liners 6 and on the inner faces 4 of columnar parts 3. Secondly, under the state that the pressure of the compressed air is held at the same as that in the expansion stage, the liners 6 are advanced inwards in the blow mold 1 so as to realize a bottle, at a nearly cylindrical bottle shell part 20 of which rising parts 21 to retain the whole shape of the bottle shell part 20 and thin corner parts 23 which easily bend in response to the change in inner pressure of the bottle are made. As a result, the bottle shell part 20, in which each corner part 23 of each pressure absorbing panel part 22 is thin-walled, is formed and consequently a bottle the pressure absorbing panel part 22 of which easily deforms in response to the change in pressure in side the bottle can be molded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for forming a bottle, in which when the pressure inside the bottle changes, the pressure is absorbed by deformation of the panel.

[Conventional technology]

Conventionally, synthetic resin bottles were used when the liquid filled in the bottle at high temperature cooled and the pressure inside the bottle was reduced, or when carbonated drinks etc. in the bottle evaporated and the pressure inside the bottle became high. The above-mentioned pressure is absorbed by deforming the bottle body, and an example thereof is disclosed in Japanese Utility Model Application No. 57-180608.

As shown in FIG. 5 of this publication, the bottle body 20 is
It is formed of a raised part 21 and a pressure absorbing panel part 22, and the pressure absorbing panel part 22 deforms inward when the pressure inside the bottle is reduced.

[Problem that the invention seeks to solve]

The bottle as shown in FIG.
The pressure absorbing panel portion 22 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 20 from deforming into a dogleg shape or the like, the thickness of the raised portion 21 cannot be made very thin. In this case, the pressure-absorbing panel portion 22 will not become too thin, and only the pressure-absorbing panel portion 22 will be less likely to deform.

The present invention has been made in view of the above-mentioned problems, and provides a method and apparatus for forming only the portion of the bottle to be deformed thinly so that only the necessary portion is easily deformed in response to changes in the pressure inside the bottle. The technical challenge is to do so.

[Means for solving problems]

The first invention is a method for molding a synthetic resin bottle equipped with a pressure absorbing panel, in which the inner surface 4 of the columnar part 3 and the nest 6
The preform is set in the blow molding mold 1 in which the inner surface 7 of the The outer surface of the preform is stuck to the inner surface 7 of the insert 6, and then the insert 6 is advanced into the blow molding mold l, and the raised portion 21 and the pressure absorbing panel portion 22 are attached to the bottle body 20. I tried to form it.

The second invention is a synthetic resin bottle molding device equipped with a pressure absorption panel, in which a blow molding mold l having a cavity 2 formed therein is in contact with a bottle body 20 of a bottle to be molded. The inner surface 4 of the columnar part 3 and the inner surface 7 of the nest 6 are arranged in the mold 1 for blow molding.
It was provided so that it could move forward and backward in the radial direction of the cavity 2.

[Effect]

In the present invention, when a preform is set in a blow molding mold l and compressed air is blown into the preform, the preform expands and its outer surface sticks to the inner surface 7 of the nest 6, causing the preform to become uneven. It is formed into a cylindrical shape with almost no thickness and approximately uniform thickness.

Next, when the nest 6 is advanced into the blow molding mold l,
As shown in FIG. 3, the pressure absorbing panel portion 22 of the bottle body 20 is recessed inward. When recessed inward, the corner portion 23 of the bottle body 20 at the corner 9 of the nest 6 is stretched in the circumferential direction (arrow in FIG. 3), and the corner portion 23 is formed thin.

〔Example〕

Hereinafter, the molding apparatus and molding method used in the present invention will be explained according to the examples shown in FIGS. 1 to 4.

In this molding device, in a blow molding mold l having a cavity 2 formed inside, a portion in contact with a bottle body 20 of a bottle to be molded is formed by an inner surface 4 of a columnar portion 3 and an inner surface 7 of a nest 6. It consists of Each of the nests 6 has both ends formed into an inclined surface 8 and a corner portion 9 formed into a wide angle. Also,
This nest 6 is provided so as to be movable forward and backward in the radial direction of the cavity 2 of the blow molding die 1 using a hydraulic piston.

In this molding method, first, a preform is formed by injection molding polyethylene terephthalate,
The formed preform is set in a blow molding mold l at a molding temperature, and compressed air is blown into the preform to expand the preform, so that the outer surface of the preform is aligned with the inner surface 4 of the columnar part 3 and The insert 6 is stuck to the inner surface 7 of the insert 6, and then the insert 6 is advanced into the blow molding mold l with the compressed air pressure maintained at the same level as in the expansion stage to form a substantially cylindrical bottle body. It was possible to obtain a bottle in which a raised part 21 for retaining the shape of the entire bottle body 20 and a thin corner part 23 that is easily bent due to changes in the internal pressure of the bottle were formed in the part 20.

〔Effect of the invention〕

In the present invention, when a bottle is molded from a preform, the preform is first formed into a large-diameter cylindrical shape, and then the nest 6 is advanced and the pressure-absorbing panel portion 22 is recessed inward. The pressure absorption panel section 22 is formed such that the section 23 is pulled in the circumferential direction, and as a result, the bottle body section 20 is formed in which the corner part 23 of the pressure absorption panel section 22 is thinned, and the pressure inside the bottle is reduced. Pressure absorption panel part 2
2 was able to mold a bottle that was easily deformed.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a main part of an embodiment of the molding apparatus of the present invention, Fig. 2 is a half-cut cross-sectional view thereof, Fig. 3 is a diagram explaining the forming method, and Fig. 4 is a view of a molded bottle. Transverse cross-sectional view, FIG. 5 (This is a cross-sectional view of a bottle molded according to a conventional example. 1. Blow molding mold, 2. Cavity portion, 3. Columnar portion, 4. Inner surface,
6. Nesting, 7. Inner surface, 20
...Bottle body, 21.. Raised section, 22.. Pressure absorption panel section. Figure 1 and Figure 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) The inner surface 4 of the columnar part 3 and the inner surface 7 of the nest 6,
A preform is set in a blow molding mold 1 positioned on approximately the same circumference, and compressed air is blown into the preform to expand the preform, and the outer surface of the preform is aligned with the nest 6. stick it to the inner surface 7 of
Next, the nest 6 is advanced into the blow molding mold 1, and the bottle body 20 is provided with a pressure absorption panel forming a raised part 21 and a pressure absorption panel part 22. (2) In a blow molding mold 1 having a cavity 2 formed therein, the portion in contact with the bottle body 20 of the bottle to be molded is constituted by the inner surface 4 of the columnar portion 3 and the inner surface 7 of the nest 6; and,
This nest 6 is a synthetic resin bottle molding device equipped with a pressure absorbing panel that is movable in the radial direction of the cavity 2 of the blow molding die 1.