JPS6142806Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a primary molded product for forming wide-mouth bottles made of synthetic resin such as polyethylene terephthalate resin that is biaxially stretched and blow-molded. The purpose is to uniformly stretch and mold the film.

When attempting to biaxially stretch blow mold a wide mouth bottle using a synthetic resin material, there is not much difference between the diameter of the mouth and the diameter of the body, which will take the final shape without undergoing stretch molding, so the body will need sufficient stretching. It was supposed to be molded into its final shape without receiving it.

Therefore, conventional wide-mouth bottles made of synthetic resin that are biaxially stretch blow-molded are molded without sufficiently stretching the body, which results in a large wall thickness and the chemical resistance of the resin material. The problem was that it wasn't sexual enough.

The present invention was devised in order to eliminate the drawbacks of the conventional examples described above, and the body part of the primary molded product is molded into a substantially hemispherical shell shape, and the part to be assembled into the biaxial stretch blow molding mold is The thickness of the neck portion located between the mouth edge portion and the body portion is formed to be thin so that the stretching force acting on the primary molded product acts in a concentrated manner.

An embodiment of the present invention will be described below with reference to the drawings.

The primary molded product 1 according to the present invention is formed by, for example, injection molding, and has a neck portion 4 having a thin short cylindrical shape at the upper end of a body portion 2 having an approximately hemispherical shell shape.
It has a structure somewhat resembling a deep-dish shape, in which a thick mouth rim 3 that bulges outward is connected to the upper end of the neck 4.

The body 2 has a substantially hemispherical shell shape as described above, but it is more advantageous to have a shape similar to an inverted conical cylinder with a spherical arc shape at the lower end as in the illustrated embodiment.

This means that the average diameter of the body 2 is the size of the bottle 1'
This is because it is possible to make the diameter as small as possible than the diameter of the body of the body, and by doing so, it is possible to obtain more elongation in the radial direction.

The mouth rim 3 that forms the mouth of the primary molded product 1 becomes the part that will form the mouth of the bottle 1', but this mouth rim 3 is placed in a biaxial stretch blow molding mold. Since it is an assembly part of the primary molded product 1, it is not stretch-molded at all.

Therefore, sufficient wall thickness is provided so that it can exhibit sufficient mechanical strength without being subjected to stretch forming.

Since this mouth rim 3 is also the part where the cap for keeping the bottle body 1' sealed is assembled, the wall thickness should be adjusted so that the cap can be assembled smoothly. It is designed so that it bulges outward by the length of the opening to form a locking strip around the outer periphery of the opening of the bottle body 1.

The stretching force applied to the primary molded product 1 concentrates on the neck 4 provided between the mouth edge 3 and the body 2, and the neck 4 is stretched earlier than the body 2. It is formed into a short, thin cylindrical shape.

The present invention has the above-mentioned configuration, and the primary molded product 1 according to the present invention is put into a bottle body 1'.
Biaxial stretch blow molding is carried out by exactly the same operation as conventional biaxial stretch blow molding.

That is, the primary molded product 1 is heated uniformly to a temperature that produces a stretching effect, is assembled into a biaxial stretch blow molding mold at the mouth edge 3, and is stretch-molded in the axial direction by advancing the stretch pin. Next, pressurized fluid is injected into the primary molded product 1 and stretched in the radial direction to form a bottle 1' by biaxial stretch blow molding.

In this way, the biaxial stretch blow molding operation of the primary molded product 1 into the bottle 1' may be completely the same as the normal biaxial stretch blow molding operation.

By the way, during this biaxial stretch blow molding, the primary molded product 1 undergoes a specific stretching deformation according to its structure.

That is, when the body 2 and the neck 4 begin to be stretched in the axial direction due to the action of the stretching pins, the stretching force is applied to the thin neck. 4, and the neck portion 4 is stretched by a predetermined amount before the body portion 2 is stretched.

When the amount of stretching of the neck portion 4 reaches a predetermined amount, the body portion 2 is then stretched in earnest, and when this stretching in the axial direction is completed, the taper angle is relatively large as shown by the dashed line in the figure. It has a large inverted conical shape.

Following this axial stretch forming, a pressurized fluid (generally air) is injected into the primary molded product 1 to stretch it in the radial direction. As is clear from the shape of the primary molded product 1 that has been stretch-molded in the axial direction indicated by the chain line, the stretch-molding is completed in the order from the part near the mouth of the bottle 1' to the bottom.

Therefore, the last part to be stretched in the radial direction is the part that forms the body of the bottle 1'.

As is well known, in biaxial stretch blow molding of bottles, the neck 4, which is the part that is close to the part to be assembled into the blow mold, and the lower end of the body 2, where the tip of the stretching pin comes into contact, are areas that are difficult to stretch. However, in the case of the present invention, as is clear from the above-mentioned stretch-forming operation, the stretching force concentrates and acts on the neck portion 4 during stretch-forming in the axial direction, so that the neck portion 4 is sufficiently stretch-formed. In addition, the lower end of the body 2 is the part that is stretched and deformed to the end, and is also the part that has the smallest diameter compared to the diameter of the bottle 1' to be molded. This results in a large amount of stretching deformation.

In this way, the fact that the neck 4 and the lower end of the body 2 are sufficiently stretched and molded means that the entire bottle 1' except for the mouth is sufficiently stretched. As a result, a thin bottle 1' can be formed.

Further, the stretching in the axial direction of the integral body of the body part 2 and the neck part 4 is carried out in the stretch-forming order in which the body part 2 is stretched after the stretching of the neck part 4 is completed, as described above. When the part 2 is stretched, the part near the neck part 4, which has already been stretched by a predetermined amount and is no longer deformed by stretching, will be stretched more.On the other hand, when stretched in the radial direction, Since the lower end of the section 2 will undergo greater stretching, the entire body section 2 will be stretched almost uniformly when the stretch forming is completed, resulting in a uniform wall thickness. A bottle 1' can be obtained.

As is clear from the above explanation, 1 according to the present invention
The next molded product can be formed into a wide-mouth bottle by sufficiently stretching the parts other than the mouth, and since the parts of the bottle other than the mouth are stretched almost uniformly, it is thin and almost uniform. It has many excellent functions and effects, such as being able to obtain a wide-mouthed bottle with a thick wall, and since the conventional molding operation can be used as is, new molding operation techniques and equipment are not required. .

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing the structure of an embodiment of the present invention, and also shows a bottle to be molded. Explanation of symbols, 1...Primary molded product, 2...Body part,
3...rim, 4...neck, 1'...bottle body.

Claims (1)

[Scope of utility model registration request] This is a primary molded product for forming wide-mouthed synthetic resin bottles that is biaxially stretch blow molded. A primary molded product for forming a wide-mouth bottle, which is provided with a mouth rim 3 that bulges outward and becomes thicker.