JPH10337769A - Premolding to be molded into container by blow molding and compression molding machine for molding it by compression molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mold a premolding to be molded into a container by compression molding without generating an error in a pericipal size such as height and inner and outer diameters of a neck. SOLUTION: An annular groove 12 is disposed on an inner peripheral edge of a support ring 10 formed at a neck 4 of a premolding 2. And, a size of the groove 12 of the neck 4 is changed together with a size of a blow molding unit 6 by changing synthetic resin material amount. The neck 4 is not changed in size except the groove 12, and the premolding 2 is compression molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin preform which is blow-molded into a container and a compression molding apparatus for compression-molding the preform.

[0002]

2. Description of the Related Art As containers for beverages and the like, containers made of a synthetic resin made of an appropriate synthetic resin such as polyethylene terephthalate are widely and practically used. In general, such a synthetic resin container is formed by injection-molding a pre-molded body composed of an annular mouth-neck portion and a bottomed cylindrical blow-molded portion hanging down from the mouth-neck portion, and then blow molding the pre-molded body. Manufactured by blow molding. The mouth and neck of the preform defines the mouth and neck of the container, and a support ring is formed on the outer peripheral surface thereof. When the lid is attached to the mouth and neck to seal the container after the contents are filled in the container, the container is held by supporting the lower surface of the support ring.

[0003]

However, the conventional manufacturing method of the synthetic resin container has a limitation in the molding efficiency in the injection molding of the pre-molded article, and the pre-molded article is molded with high molding efficiency. There is a problem that can not be. In order to mold the pre-molded body with high molding efficiency, it is intended to adopt compression molding instead of injection molding. However, in the case where the pre-molded article is formed by compression molding, there are the following problems to be solved. That is, in the case of compression molding, the synthetic resin material can be supplied to the female means or the male means before the male means and the female means are closed and a molding space is defined therebetween. is necessary. The supply of the synthetic resin material is performed, for example, by extruding a softened and molten synthetic resin material from an extruder and cutting off the synthetic resin material from an extrusion port of the extruder. Due to this, it is extremely difficult to control the supply amount of the synthetic resin material with sufficient precision, and there is usually an error of about 0.5 to 1.0% in the supply amount of the synthetic resin material. Such an error in the amount of the synthetic resin material is caused by moving the male means and the female means in a direction in which they approach each other to close them, and when the synthetic resin material is compression-molded between the two means, Varying the spacing between the female means. Therefore, usually, a slight variation is generated in the dimensions such as the thickness and the outer diameter of the whole preformed body that has been compression molded. Slight variations in dimensions in the blow-molded part of the pre-molded body do not cause any particular problem. However, when slight variations are generated in the main dimensions such as the height of the mouth and neck, and the inner and outer diameters, (a) When the lid is attached to the mouth and neck, due to the dimensional fluctuation of the part where the sealing means arranged on the lid is brought into close contact, the required sealing characteristics are not achieved. Due to variations in the height to the tip of the part, there are many risks that unacceptable problems occur, such as various obstacles occurring in the lid automatic mounting operation of mounting the lid on the mouth and neck. Conventionally, it is difficult, if not impossible, to use a rather complicated and expensive mold means to compression-mold a preform without causing errors in main dimensions such as the height of the mouth and neck, inner and outer diameters, and the like. It is considered necessary to perform the compression molding of the preformed body to the present inventors' knowledge.

[0004] The present invention has been made in view of the above-mentioned facts, and its main technical problem is that the height and inner and outer diameters of the mouth and neck, such as the height and inner and outer diameters, are not required without complicated and expensive mold means. An object of the present invention is to enable compression molding of a preform with high molding efficiency without causing errors in main dimensions.

[0005]

Means for Solving the Problems As a result of earnest research, the present inventors have changed the form of the preformed body itself to a form in which an annular groove is formed on the inner peripheral edge of the lower surface of the support ring.
It has been found that the above technical problem can be achieved.

That is, according to one aspect of the present invention, compression is performed without causing errors in main dimensions such as the height and inner and outer diameters of the mouth and neck, without requiring complicated and expensive mold means. In order to enable molding, as a pre-formed body having an improved form, the pre-formed body includes an annular mouth-neck portion and a bottomed cylindrical blow-molded portion hanging from the mouth-neck portion. A support ring projecting outward in the radial direction is provided on an outer peripheral surface of the synthetic resin preformed body which is formed by blow molding the blow molded portion to be made into a container. An annular groove is formed in the portion, and the size of the annular groove and the size of the blow molded portion fluctuate due to a change in the amount of synthetic resin material. At least not to fluctuate, Is molded by compressing the synthetic resin material, it is provided preform, characterized in that.

[0007] According to another aspect of the present invention, the preforming is performed without causing any errors in the main dimensions such as the height of the mouth and neck and the inner and outer shapes without requiring complicated and expensive mold means. As a compression molding device that enables compression molding of a body, the compression molding device includes an annular mouth-neck portion and a bottomed cylindrical blow-molded portion that hangs down from the mouth-neck portion. A compression molding apparatus for compression molding a preform having an annular groove formed in an inner peripheral edge of a lower surface of the support ring is provided with a support ring extending outward. A male means and a female means, which are moved in the directions and are set in a closed state which cooperate to define a mold space, are moved in a direction away from each other and are brought into an open state, The male means together with the inner surface of the blow molding section The face of the neck is defined except for the annular groove, and the female mold means defines the outer surface of the blow-molded portion and the annular groove of the mouth and neck, which is caused by a change in the amount of synthetic resin material. The size of the annular groove and the height of the blow-molded portion in the compression-molded pre-molded body vary due to the variation in the mutual distance between the male mold means and the female mold means in the closed state. The compression molding apparatus is characterized in that the mouth and neck are not varied in size except for the annular groove.

[0008] The male mold means includes at least an inner surface of the blow molded portion and a core member defining an inner peripheral surface of the mouth and neck portion;
Preferably, a split member defining at least the lower surface of the support ring, the split member being composed of a plurality of split pieces separated from each other by being moved radially outward. is there.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings.

FIG. 1 shows a preferred embodiment of the preformed body of the present invention. Compression molded from an appropriate synthetic resin such as polyethylene terephthalate,
The preformed body indicated by is formed of an annular mouth-neck portion 4 and a bottomed cylindrical blow-molded portion 6 hanging from the mouth-neck portion 4.
The mouth and neck 4 has a substantially cylindrical shape as a whole, and its inner peripheral surface extends vertically in practice except for the upper end. An annular projecting jaw 8 projecting outward in the radial direction is formed at the upper part of the outer peripheral surface of the mouth and neck 4. The upper end surface and the upper end surface of the inner peripheral surface of the mouth and neck 4 are defined by a curve that smoothly follows the jaw 8. An annular support ring 10 that protrudes radially outward is formed at a lower portion of the mouth and neck 4. The outer peripheral surface of the support ring 10 extends substantially vertically. The lower surface of the support ring 10 extends substantially horizontally.

It is important that an annular groove 12 is formed in the inner peripheral edge of the lower surface of the support ring 10 in the mouth and neck 4. The cross-sectional shape of the annular groove 12 in the illustrated embodiment is substantially rectangular.

The blow molding part 6 following the mouth-neck part 4 includes an inverted truncated cone-shaped body part 7 and a hemispherical bottom part 9.

The preformed body 2 having the annular groove 12 formed in the mouth and neck 4 is provided with the annular groove 1 due to a change in the amount of the synthetic resin material.
2 and the size of the blow molding portion 6 are varied, but the mouth and neck portion 4 is formed by compressing the synthetic resin material so that the size is not varied except for the annular groove 12. It is important that

FIG. 2 shows a male mold means 14 and a female mold means 16 in a compression molding apparatus for compression-molding the preformed body 2.
Are illustrated. The male means 14 and the female means 16 are relatively moved in a direction approaching and separating from each other and are opened and closed. In the illustrated embodiment, the male means 14 is lowered from the raised position shown by the solid line to the lowered position shown by the two-dot chain line, and the male means 14 and the female means 16 are closed. In such a closed state, the male mold means 14 and the female mold means 16 define a molding space between them for compression molding the pre-mold. By raising the male means 14 to the raised position shown by the solid line, the male means 14 and the female means 16 are returned to the open state.

Continuing with FIG. 2, the male means 14 in the illustrated embodiment comprises a core member 18 and a split member 20. The core member 18 includes a relatively large-diameter cylindrical portion 22, a relatively small-diameter cylindrical portion 24 located below the cylindrical portion 22, an inverted truncated conical portion 26 extending downward from the cylindrical portion 24, and It has a hemispherical portion 28 located at the lower end. As can be understood by referring to FIG. 1 in conjunction with FIG. 2, the surfaces of the cylindrical shape 24, the inverted truncated conical shape portion 26 and the hemispherical shape portion 28 correspond to the inner peripheral surface of the mouth and neck portion 4 and the inner surface of the blow molded portion 6. Is specified. An annular concave portion 30 is formed on the lower surface of the cylindrical portion 22, and the inner surface of the annular concave portion 30 is formed on the outer peripheral surface of the mouth-neck portion 4 together with the upper end surface of the mouth-neck portion 4. Is specified. The split mold member 20 is composed of two split pieces 32. Each of the two split mold pieces 32 is semi-annular and cooperates to form an annular shape when positioned in the closed position shown by the solid line. The split mold piece 32 has an inner surface that defines the lower surface of the support ring 10 in the mouth and neck 4 excluding the inner peripheral edge where the annular groove 12 exists, together with the outer surface of the mouth and neck 4 other than the outer surface of the jaw 8. Having. The two split pieces 32 constituting the split member 20 can be moved outward in the radial direction and separated from each other, as shown by the two-dot chain line in FIG.

The female means 16 has a substantially cylindrical shape as a whole, and has a relatively large concave portion 34 formed at the center thereof. An annular ridge 36 projecting upward from the outer peripheral edge of the concave portion 34 is formed in the female mold means 16. The outer shape of the upper end of the annular ridge 36 corresponds to the inner diameter of the lower end of the split member 20 of the male means 14, and the male means 14 and the female means 1
6 is closed, the upper end of the annular ridge 36 is
0 to define the annular groove 12 of the preform 2. The inner peripheral surface of the annular ridge 36 defines the outer surface of the blow molded portion 6 together with the inner surface of the concave portion 34.

The compression molding step of the pre-molded body 2 using the male mold means 14 and the female mold means 16 is as follows.
As shown in FIG. 3A, the male means 14 and the female means 16
Is in the open state, the female means 1 in an appropriate manner.
The synthetic resin material 36 in a softened and molten state is supplied into the recessed portion 6 of FIG. Next, as shown in FIGS. 3B and 3C, the male means 14 is gradually lowered, and accordingly, the synthetic resin material 3 existing in the concave portion 34 of the female means 16 is moved.
The male means 14 acts on 6, and the synthetic resin material 36 is compressed and made to flow. When the male means 14 is lowered to the position shown in FIG. 3C, the molding space defined between the male means 14 and the female means 16 is completely filled with the synthetic resin material 36, Therefore, the male means 14 is prevented from descending further. Thus, the male means 14
The pre-molded body 2 having the shape of the mold space defined between the mold member 16 and the female mold means 16 is compression-molded.

As described above, it is practically impossible to control the amount of the synthetic resin material 36 supplied to the concave portion 34 of the female mold means 16 with extremely high precision. Minutes or fluctuates. Synthetic resin material 3 supplied
Variations in the quantity of 6 cause the volume of the mold space to fluctuate, and thus the final lowered position of the male means 14, ie, the distance d between the male means 14 and the female means 16 in the closed state.
(FIG. 3-C) is varied. Thus, in the compression molding of the pre-molded body 2 using the male mold means 14 and the female mold means 16 of the above-described embodiment, as clearly understood by referring to FIG. If FIG. 3-C) changes, the dimensions of the blow-molded part 6, more specifically, the height h and the thickness t of the blow-formed part 6 change. In addition, the mouth and neck 4
Of the annular groove 12 formed in the support ring 10, and more specifically, the depth e of the annular groove 12 varies. However, the mouth and neck 4 with a suitable lid (not shown)
The portion of the mouth and neck 2 other than the annular groove 12 which is important for the seal of the mouth, the operation of attaching the lid to the mouth and neck 4, etc. is defined by the male means 14 itself, and is therefore supplied. Even if the amount of the synthetic resin material 36 varies, the dimensions (inner diameter x, height y, jaw 8
Is set to a predetermined value without fluctuating.

After the preform 2 is formed by compressing the synthetic resin material 36 as described above, FIG.
The male means 14 is raised to separate the male means 14 from the female means 16, as shown in FIG. The molded preform 2 defines the lower surface of the support ring 10 formed on the mouth and neck 4 of the molded preform 2 in which the split mold member 20 of the male mold means 14 is formed. It is raised together with the mold means 14 and is separated from the female mold means 16. Next, as shown in FIG. 4B, only the core member 18 in the male mold means 14 is further raised, whereby the core member 18 is separated from the preform 2. Thereafter, as shown in FIG. 4D, the two split pieces 32 constituting the split member 20 are moved outward in the radial direction, and the split member 20 is also separated from the preformed body 2. The preformed body 2 thus formed is taken out.

The pre-molded body 2 compression-molded as described above is further subjected to blow molding known per se, whereby the blow-molded portion 6 of the pre-molded body 2 has two points as shown in FIG. As shown partially in dashed lines, the main part of the container (the body and the bottom following the mouth and neck 4) is formed by blow molding.

As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings. However, the present invention is not limited to such embodiments, and various modifications are possible without departing from the scope of the present invention. It is not necessary to say that the correction is possible. For example, in the illustrated embodiment, the synthetic resin material is supplied to the female means in a state where the male means is completely separated from the female means, but if desired, the male means and the female means are supplied. So that the synthetic resin material is injected into the space between them, and then the female and male means are completely closed, so-called injection molding of the injected synthetic resin material. The preform can be formed by performing a unique compression molding called compression molding.

[0022]

According to the present invention, the preformed body can be formed without requiring any complicated and expensive mold means and without causing errors in the main dimensions such as the height of the mouth and neck and the inner and outer diameters. Compression molding can be performed with high molding efficiency.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a preferred embodiment of a pre-molded article compression-molded according to the present invention.

FIG. 2 is a sectional view showing a male means and a female means used for compression-molding the preformed body of FIG. 1;

FIG. 3 is a cross-sectional view showing a step of forming the pre-formed body shown in FIG. 1 using the male mold means and the female mold means shown in FIG.

FIG. 4 is a cross-sectional view showing a step of taking out a pre-formed body formed using the male mold means and the female mold means shown in FIG.

[Explanation of symbols]

 2: Pre-molded body 4: Mouth and neck part 6: Blow molded part 8: Jaw part of mouth and neck part 10: Support ring of mouth and neck part 12: Annular groove of support ring 14: Male means 16: Female means 18: Core member of male means 20: Split member of male means 32: Split piece of split member

Claims (3)

[Claims] 1. An annular mouth-neck portion and a bottomed cylindrical blow-molded portion hanging from the mouth-neck portion, and a support ring projecting outward in the radial direction is disposed on an outer peripheral surface of the mouth-neck portion. In the synthetic resin preform that can be blow-molded into a container by blow molding, an annular groove is formed on the inner peripheral edge of the lower surface of the support ring, and the amount of synthetic resin material varies. As a result, the size of the annular groove and the size of the blow-molded portion are changed, but the mouth and neck portion are not changed except for the annular groove, and the synthetic resin material is compressed. A pre-molded article characterized by being molded as follows. 2. An annular mouth-and-neck portion and a bottomed cylindrical blow-molded portion hanging from the mouth-and-neck portion, and a support ring projecting outward in the radial direction is disposed on an outer peripheral surface of the mouth-and-neck portion. In a compression molding apparatus for compressing and molding a preform having an annular groove formed on an inner peripheral edge of a lower surface of the support ring, the support ring is moved in a direction approaching each other and cooperates. A male mold means and a female mold means which are set in a closed state to define a molding die space and are moved in a direction apart from each other to be brought into an open state, wherein the male mold means is provided in the blow molding section. Along with the inner surface, all surfaces except the annular groove of the mouth and neck are defined, and the female mold means defines the outer surface of the blow molded portion and the annular groove of the mouth and neck, and is made of a synthetic resin material. Interaction between the male means and the female means in the closed state due to the variation of the amount Due to the change of the gap, the size of the annular groove and the size of the blow molded portion in the compression-molded pre-formed body are changed, but the size of the mouth and neck is changed except for the annular groove. There is no compression molding apparatus. 3. The male mold means includes a core member defining at least an inner surface of the blow molded portion and an inner peripheral surface of the mouth and neck portion, and a split mold member defining at least a lower surface of the support ring. 3. The compression molding apparatus according to claim 2, wherein the split mold member is constituted by a plurality of split pieces separated from each other by moving outward in the radial direction.