JPS6228406Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a preformed product which is an intermediate product of a stretched hollow container whose body has an elliptical cross section.

Conventionally, stretched hollow containers made of thermoplastic synthetic resin such as polyethylene terephthalate have been made by injection molding or the like to form a preformed product with one end closed, and after heating the preformed product to a temperature at which it can be stretched, it is placed in a molding die. It is molded by stretch blow molding.

Therefore, a hollow container 1 whose body has an elliptical cross section
0 from a cylindrical material which is a preformed product, as shown in Fig. 1, the side walls a, a' in the major axis direction have a larger molding expansion ratio than the side walls b, b' in the minor axis direction, and are stretched. Since the ratio is large, it is impossible to avoid the drawback that the side wall in the long axis direction becomes thin. In order to eliminate this drawback, recently the side walls of the cylindrical material 16 have been made thick so that the side walls a and a', which face each other in the cross-sectional shape of the body, are made thicker, as shown in FIG. First, a preformed product 11 with thin side walls b and b′ facing each other in the direction of
Stretch blow molding is performed to form an elliptical hollow container in which the thicker parts a and a' are in the major axis direction and the thinner parts b and b' are in the minor axis direction in the cross section of the body. The major axis direction of
By setting a′, it became possible to obtain a hollow container with approximately uniform wall thickness.

By the way, for convenience in handling, the preformed product 11 has a body cross-sectional shape with the outer side of the preformed product 11 being circular as shown in FIG. Therefore, it is not easy to confirm the direction of the thick parts a, a' or the direction of the thin parts b, b'. Therefore, although the opposing side walls a and a' are made thick, it is difficult to align these portions with the long axis direction of the product, resulting in a disadvantage that many defective products occur.

The present invention has such drawbacks as described below.

The preformed product 11 according to the present invention is calculated so that the cross-sectional shape of the body of the product as a stretch-blow-molded hollow container is an ellipse and the thickness is uniform. It is formed as a preform 11 for drawing of a cylindrical body 16 as shown in FIG. As shown, a protrusion 17 is formed above the neck ring 12, for example, at one or both of the positions in the a and a' directions of the thick wall part, thereby forming the preform thick wall part a,
Use it as a confirmation mark for a′.

Note that the protruding body 17 is provided in the immediate vicinity of the neck ring 12, and is located above the neck ring 12.
In this case, a short and small protrusion 17 as a position confirmation mark is formed in the vicinity of the neck ring 12, which is a part that does not interfere with the formation of a threaded part and other shaping of the predetermined opening shape of the product container 11.

When performing secondary molding using such a preformed product, if the preformed product is inserted into the mold for molding the product using the protruding body 17 provided immediately above the neck ring 12 as a confirmation mark, the protruding body So that the 17th position corresponds to the long diameter part of the product molding die,
The preform can be easily positioned in the circumferential direction, and the product can be molded at an expansion ratio that corresponds to the thickness of each part of the body wall of the preform, and the cross-sectional shape of the body of the hollow part of the product can be adjusted. Even if it is oval in shape,
This allows the entire circumference of the trunk wall to be approximately uniform in thickness.

In summary, the present invention provides a preformed product for a stretched hollow container having an elliptical cross-section of the body. Thick wall part a,
a' and thin-walled parts b and b' facing each other in the direction perpendicular to this are formed into a cylindrical body, and at the upper part 15 of the neck ring 12, a short part is placed on the outer periphery of the preform 11 at a position immediately above the neck ring 12. This is a preformed product for forming an elliptical stretched hollow container characterized by a structure in which a protruding body 17 and the like are provided.

As described above, since the outer shape of the body cross section of the preform 11 is circular and the inner shape is oval, the preform can be manufactured easily and inexpensively by using an elliptical core. can be molded,
Furthermore, since the wall thickness of the preform is varied, it is possible to obtain a wall thickness distribution that corresponds to the stretching rate of the elliptical stretched hollow container.

Furthermore, a protrusion 1 serving as a confirmation marker is placed near the neck ring 12 that grips the preform 11.
7, when gripping the preform 11 to insert it into the mold, the direction of the preform 11 is kept constant, so even if the outer circumference of the preform 11 is circular, the mold The preform 11 can be easily inserted into the mold by correctly corresponding to the long diameter position of the neck ring 12, and the position confirmation mark is placed immediately above the neck ring 12, not at the lower part 14 of the neck ring 12, which is stretched by blow molding or the like. Therefore, when molding the container 10 as a product from the preform 11, the protrusion 17 does not pose a problem.

Therefore, it is a preformed product that is easy to manufacture, and can be easily and reliably molded into an elliptical stretched hollow container having a body wall with a substantially uniform wall thickness.
Moreover, it is a preformed article for an elliptical stretched hollow container, which has the advantage of being less likely to produce defective products with uneven wall thickness.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the body of a conventional elliptical stretched hollow container, Fig. 2 is a cross-sectional view of the body of a conventional preform, and Fig. 3 is a side view of essential parts of the preform according to the present invention. Figure 4 is a top view. 10=elliptical stretched hollow container, 11=preform, 12=neck ring, 14=neck ring lower part, 15=neck ring upper part, 16=cylindrical body, 1
7 = protruding body.

Claims (1)

[Scope of utility model registration request] A preformed product for a stretched hollow container having an elliptical cross-section of the body, the outer shape of the cross-section of the body is circular, the inner shape of the cross-section of the body is oval, and the wall thickness is set to a desired value,
A cylindrical body is formed by forming opposing thick-walled parts a, a' and thin-walled parts b, b' facing each other in a direction perpendicular to these, and a short and small protrusion is formed on the outer periphery of the preform immediately above the neck ring. A preformed product for forming an oval stretched hollow container characterized by a structure with a body.