JPH0736724Y2 - Opening of plastic tubular articles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a structure of an opening of a plastic tubular article, and particularly to the inner circumference or the outer circumference of the opening.
The present invention relates to an improvement in a tubular article formed by intermittently forming undercuts such as ribs or grooves.

An example of such a tubular article is the body of a mahbo bottle. Generally, the exterior body of a bubble bottle is formed by attaching a shoulder body to the upper part of a cylindrical body, and a vacuum double bottle is housed in the package body to form a bubble bottle.
In order to attach the shoulder body to the body, a female screw is usually engraved on the end of the body, and a male screw is engraved on the shoulder body.

However, if a female screw is engraved on the inner circumference of the end of the body,
Since the thread portion of the female screw becomes thick, a sink mark appeared on the outer surface along the thread and was extremely unsightly. Further, the opening of the body is narrowed by the height of the thread of the female screw, the diameter of the vacuum double bottle accommodated inside is restricted, and the capacity of the bubble bottle is reduced.

In view of such circumstances, the body and the female screw are formed as separate bodies to prevent the appearance of sink marks on the outer surface of the body, and the diameter of the vacuum double bottle accommodated inside is made to be somewhat large, so that the internal capacity is It is expected to increase.

FIG. 3 shows such a bottle. Reference numeral 1 denotes an exterior body, which is composed of a tubular body 2 and a shoulder body 3 coupled to an upper opening of the body 2, and a vacuum double bottle 4 is housed in the exterior body 1. The upper end of the vacuum double bottle 4 is pressed against the lower side of the opening in the center of the shoulder body 3 via a packing 5, and the bottom portion is tightened by a tightening body 6 screwed to the bottom of the body 2.

A handle 7 is fixedly attached to the back of the body 2, and a spout 8 is formed at the front of the shoulder 3 to form the shoulder 3
The central opening is closed with a stopper 9.

The body 2 is a plastic injection molded product, and a plurality of ribs 10 are intermittently provided on the inner circumference of the upper end portion thereof. The thickness of the rib 10 is sufficiently smaller than the thickness of the outer wall of the body 2 and is such that sink marks do not occur during molding. Reference numeral 11 denotes an internal thread ring 11 having an internal thread 12 engraved on the inner periphery thereof. The internal thread ring 11 is fitted to the inner periphery of the body 2 below the rib 10, and the internal thread 12 of the internal thread ring 11 is fitted to the shoulder body 3.
A male screw 13 engraved on the outer periphery of the is screwed to connect the shoulder body 3 to the body 2.

2. Description of the Related Art As described above, the body 2 of the bubble bottle has ribs 10 intermittently formed on the inner surface of the upper opening.
It does not matter if the rib 10 is formed all around the opening of the body 2, but since this rib 10 becomes an undercut during injection molding, if this rib 10 is formed all around, it will be removed from the mold. Has to make the structure of the mold at the time of molding extremely complicated. When the rib 10 is formed intermittently, only the mold of the rib 10 can be slid inward, and the mold of the part without the rib 10 can be removed from the molded product without moving. Therefore, the structure of the mold can be relatively simple.

However, if the rib 10 is formed intermittently as described above, both the inner and outer surfaces of the body 2 are smooth over the entire length in the portion where the rib 10 is absent. Therefore, when the molded product is cooled in the mold when the body 2 is molded, shrinkage occurs, and in the portion without the rib 10, the edge of the opening is recessed as shown by the chain line in FIG. Of. In the portion where the rib 10 is present, the rib 10 is engaged with the mold and thus cannot be contracted, so that the length of the molded product does not change during molding, but the rib 10 is not provided. Since no such engagement occurs in the part, it is not possible to prevent contraction.

Therefore, a slight difference occurs in the length of the body 2 between the portion with the ribs 10 and the portion without the ribs 10, and the upper edge of the body 2 undulates. Therefore, when the shoulder body 3 is joined to the body 2, a gap is created between the body 2 and the shoulder body 3 in the portion where the rib 10 is not present, which makes the appearance very unsightly.

The present invention has been made in view of the above circumstances, and there is no local difference in contraction at the time of formation, a sink mark 14 is prevented from being generated at the edge of the opening, and the periphery is flush with the same plane. It is an object of the present invention to provide a structure of an opening of a tubular article which can be

Means for Solving the Problems Thus, the present invention relates to a plastic cylindrical article having an undercut intermittently formed in the circumferential direction of the opening, and covering approximately the entire width between the undercuts in the opening. Thus, an auxiliary undercut capable of being forcedly removed from the mold is formed.

Hereinafter, the case where the present invention is applied to the body 2 of the foam bottle will be described. FIG. 1 shows a main part of the body 2, in which ribs 10 serving as undercuts are intermittently formed in the circumferential direction along the inner circumference of the upper opening.

In the present invention, an auxiliary rib 15 as an auxiliary undercut is formed on the inner surface of the rib 10 over the extension of the rib 10 over the front width of the portion between the ribs 10. There is. As shown in FIG. 2, the auxiliary rib 15 has a gentle slope formed on the upper and lower sides thereof, and is firmly locked to the mold as an undercut while the mold is closed during molding. However, when the mold is opened and the molded product is removed, the molded product can be forcibly removed by elastically deforming the molded product.

Thus, when molding the body 2, the plastic material is injected into a closed mold and cooled to mold, but the lower part of the molded product is such that the bottom of the body 2 is a mold. The ribs 10 and the auxiliary ribs 15 are formed so as to be almost continuous over the entire inner surface of the molded product in the upper part, and the ribs 10 and the auxiliary ribs 15 are formed. Since it is locked to the mold, the molded product is locked to the mold at both upper and lower ends, and cannot shrink in the length direction even when cooled.
Therefore, there is no difference in the length of the body 2 locally,
The upper edge of the body 2 is molded exactly in the same plane.

The part between the rib 10 and the auxiliary rib 15 and the opening edge of the molded product may shrink, but the distance is small and the amount of shrinkage is small, and it is almost uniform over the entire circumference. The contraction does not cause local shrinkage 14 or damage to the plane of the opening edge due to the contraction.

Also, when releasing the molded product from the mold, first remove the molded product and the inner mold from the outer mold, then slide the mold of the part of the inner mold where the rib 10 is formed inward, and then When the molded product is pulled out from the remaining inner mold portion, the molded product elastically deforms, so that the inner mold can be released over the auxiliary ribs 15.

Effect of the Invention According to the present invention, since the difference in shrinkage does not locally occur in the molded product, the openings of the molded product can be molded in the same plane with high accuracy. Therefore, when it is applied to the body 2, no gap is formed at the joint between the body 2 and the shoulder 3, which is extremely preferable in appearance.

Further, in the present invention, since the auxiliary rib 15 can be forcibly removed from the mold, it is not necessary to make a complicated movement of the mold when the molded product is removed from the mold, and the metal having a simple structure can be used. It can be molded in a mold.

Embodiment In the above description, the present invention is applied to the exterior body 1 of a foam bottle.
Although the case where it is applied to the body 2 in the above is described, it is needless to say that the present invention can be applied to a tubular article used for other purposes and has the same operational effect.

Further, in the above description, the rib 10 is provided so as to project from the inner surface of the opening of the tubular article, but even if the groove is not a rib, it is an undercut at the time of molding. , Can be applied in exactly the same way. The same applies when these undercuts are formed on the outer surface of the tubular article. Furthermore, the auxiliary rib 15 may be an undercut that allows forcible removal, may be a groove, or may be formed on the outer surface of the tubular article.

Further, the undercut originally possessed by the molded product and the auxiliary undercut formed by the present invention do not need to be formed on the same surface of the tubular article, for example, the undercut is formed on the outer surface of the tubular article. In some cases, it is also possible to form an auxiliary undercut on its inner surface and vice versa.

[Brief description of drawings]

FIG. 1 shows an example of a tubular article to which the present invention is applied.
FIG. 2 is a perspective view of the main part of the body of the mahobin, and FIG.
It is an expanded sectional view of the II-II part in FIG. FIG. 3 is a central longitudinal sectional view of a foam bottle using a body to which the present invention is applied. FIG. 4 is a perspective view of a main part of a conventional body of the foam bottle. 2 …… Cylindrical article (body) 10 …… Undercut (rib) 15 …… Auxiliary undercut (auxiliary rib)

Claims (1)

[Scope of utility model registration request] 1. A plastic cylindrical article (2) having undercuts (10) intermittently formed in the circumferential direction of an opening, wherein a space between the undercuts (10, 10) in the opening is approximately the same. An opening for a plastic tubular article, characterized by forming an auxiliary undercut (15) that can be forcefully removed from the mold over the entire width.