JP3417255B2 - Preformed body to be blow molded into a container and compression molding apparatus for compression molding the same - Google Patents

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 a container for beverages and the like, a synthetic resin container made of an appropriate synthetic resin such as polyethylene terephthalate is widely put into practical use. Such a synthetic resin container is generally 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 the blow-molded portion of the pre-molded body. Manufactured by blow molding. The mouth-neck portion of the preformed body defines the mouth-neck portion 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 filling the container with contents, the container is held by supporting the lower surface of the support ring.

[0003]

Therefore, the conventional manufacturing method of the synthetic resin container has a limit 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 you cannot do it. In order to mold the pre-molded article with high molding efficiency, it is intended to adopt compression molding instead of injection molding. However, in the case where the pre-molded body is a compression-molded body, there are the following problems to be solved. That is, in the case of compression molding, it is possible to supply the synthetic resin material to the female mold means or the male mold means before closing the male mold means and the female mold means to define the mold space therebetween. is necessary. The supply of the synthetic resin material is performed, for example, by extruding the softened and molten synthetic resin material from the extruder and separating the synthetic resin material from the 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 normally, there is 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 synthetic resin material causes the male mold means and the female mold means to move toward each other to be in a closed state, and when the synthetic resin material is compression-molded between them, Varying the mutual spacing with the female means. Therefore, in general, a slight variation is generated in the dimensions such as the thickness and the outer diameter of the entire compression molded preform. A slight change in the dimensions of the blow-molded part of the pre-molded product does not cause any particular problem, but if a slight change occurs in the main dimensions such as the height of the mouth and neck, the inner and outer diameters, (a) When the lid is attached to the mouth / neck portion, the required sealing characteristics cannot be achieved due to the dimensional variation of the portion where the sealing means disposed on the lid is brought into close contact. (B) From the lower surface of the support ring to the mouth / neck It is not uncommon for unacceptable problems such as various obstacles to occur in the automatic lid mounting operation for mounting the lid on the mouth and neck due to variations in the height to the tip of the part. Conventionally, it is considerably difficult, if not impossible, to use a molding means which is considerably complicated, if not impossible, to compression-mold a pre-molded body without causing errors in the main dimensions such as the height of the mouth and neck and the inner and outer diameters. It is considered necessary, and as far as the present inventors know, compression molding of a pre-molded product has not been realized yet.

The present invention has been made in view of the above facts, and its main technical problem is to increase the height of the mouth and neck, the inner and outer diameters, etc. without requiring complicated and expensive mold means. The object is to enable compression molding of the pre-molded article with high molding efficiency without causing an error in the main dimension.

[0005]

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

[0006] That is, according to one aspect of the present invention, the compression is performed without requiring complicated and expensive mold means and without causing an error in the main dimensions such as the height of the mouth and neck and the inner and outer diameters. As a pre-molded body whose shape is improved to enable molding, it is composed of an annular mouth-neck portion and a bottomed cylindrical blow-molded portion hanging down from the mouth-neck portion. A support ring that projects outward in the radial direction is arranged on the outer peripheral surface of the, and in a synthetic resin pre-molded product that is blow molded into the container, the inner peripheral edge of the lower surface of the support ring An annular groove is formed in the portion, and the dimension of the annular groove and the dimension of the blow-molded portion are varied by the variation of the amount of synthetic resin material, but the mouth and neck portion is dimensioned except for the annular groove. As much as possible so that Is molded by compressing the synthetic resin material, it is provided preform, characterized in that.

According to another aspect of the present invention, the preforming is performed without requiring complicated and expensive mold means and without causing an error in major dimensions such as the height of the mouth and neck and the inner and outer contours. As a compression molding device that enables compression molding of a body, it is composed of an annular mouth-neck portion and a bottomed cylindrical blow-molded portion that hangs down from the mouth-neck portion. A support ring that projects outward is disposed, and a compression molding device for compression molding a pre-molded article in which an annular groove is formed on the inner peripheral edge of the lower surface of the support ring approaches each other. A male means and a female means that are moved in a direction to be set to a closed state that cooperatively defines a mold space, and are moved in a direction away from each other to be in an open state, The male mold means, together with the inner surface of the blow molding part, All the surfaces of the neck except the annular groove are defined, and the female mold means defines the outer surface of the blow-molded portion and the annular groove of the mouth-neck, which is caused by fluctuations in the amount of synthetic resin material. However, due to the fluctuation of the mutual distance between the male mold means and the female mold means in the closed state, the size of the annular groove and the height of the blow molding part in the compression-molded pre-molded body are varied. A compression molding apparatus is provided in which the mouth and neck portion does not change in size except for the annular groove.

The male mold means defines a core member that defines at least the inner surface of the blow-molded portion and the inner peripheral surface of the mouth-neck portion.
It is preferable that the split mold member includes at least a split mold member that defines a lower surface of the support ring, and the split mold member is composed of a plurality of split mold pieces that are separated from each other by being moved radially outward. is there.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will now be described in more detail with reference to the accompanying drawings.

FIG. 1 shows a preferred embodiment of the preform of the present invention. It is compression molded from an appropriate synthetic resin such as polyethylene terephthalate.
The pre-molded body indicated by is composed of an annular mouth-neck portion 4 and a bottomed cylindrical blow-molded portion 6 that hangs from the mouth-neck portion 4.
The mouth / neck portion 4 has a substantially cylindrical shape as a whole, and the inner peripheral surface thereof extends vertically in practice except for the upper end portion. On the upper part of the outer peripheral surface of the mouth / neck portion 4, an annular projecting jaw portion 8 projecting outward in the radial direction is formed. The upper end portion and the upper end surface of the inner peripheral surface of the mouth / neck portion 4 are defined by curves that smoothly follow the jaw portion 8. An annular support ring 10 is formed at the lower portion of the mouth / neck portion 4 so as to project radially outward. 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 portion of the lower surface of the support ring 10 in the mouth / neck portion 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 / neck portion 4 has an annular groove 1 due to a change in the amount of synthetic resin material.
The dimension of 2 and the dimension of the blow-molded portion 6 are varied, but the neck 4 is made by compressing a synthetic resin material so that the dimension does not vary except for the annular groove 12. Is important.

FIG. 2 shows a male mold means 14 and a female mold means 16 in a compression molding apparatus for compression molding the preform 2.
And are illustrated. The male-type means 14 and the female-type means 16 are relatively moved in a direction toward and away from each other to be 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 chain double-dashed line, and the male means 14 and the female means 16 are closed. In this closed state, the male mold means 14 and the female mold means 16 define a mold space for compression-molding the front mold between them. The male means 14 and the female means 16 are returned to the open state by raising the male means 14 to the raised position shown by the solid line.

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

The female mold means 16 has a generally cylindrical shape as a whole, and a relatively large recess 34 is formed in the center thereof. The female die 16 is formed with an annular ridge 36 protruding upward from the outer peripheral edge of the recess 34. The outer shape of the upper end portion of the annular protrusion 36 corresponds to the inner diameter of the lower end portion of the split mold member 20 of the male mold means 14, and the male mold means 14 and the female mold means 1
When 6 is closed, the upper end of the annular ridge 36 is divided into two parts.
0 to the lower end to define the annular groove 12 of the preform 2. The inner peripheral surface of the annular protrusion 36 defines the outer surface of the blow molding part 6 together with the inner surface of the recess 34.

The compression molding process of the preform 2 using the male mold means 14 and the female mold means 16 is as follows.
As shown in FIG. 3-A, male means 14 and female means 16
When the and are in the open state, the female means 1 is formed in an appropriate manner.
A synthetic resin material 36 in a softened and melted state is supplied into the concave portion 34 of 6. Next, as shown in FIGS. 3-B and 3-C, the male mold means 14 is gradually lowered, and in response to this, the synthetic resin material 3 existing in the concave portion 34 of the female mold means 16 is moved.
The male mold means 14 acts on 6 to compress and flow the synthetic resin material 36. When the male mold means 14 is lowered to the position shown in FIG. 3-C, the mold space defined between the male mold means 14 and the female mold 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 preform 2 having the shape of the mold space defined between the female mold means 16 and the female mold means 16 is compression molded.

As described above, it is practically impossible to precisely control the amount of the synthetic resin material 36 supplied to the concave portion 34 of the female mold means 16, and the amount of the synthetic resin material 36 supplied is very small. It varies by a minute. Synthetic resin material 3 supplied
A variation in the amount of 6 causes the volume of the mold space to vary, and thus the final descent 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 changed. Thus, in the compression molding of the pre-molded body 2 using the male mold means 14 and the female mold means 16 having the above-mentioned forms, as clearly understood by referring to FIG. 3-C) changes, the dimensions of the blow molding section 6, more specifically, the height h and the thickness t of the blow molding section 6 vary. Furthermore, the mouth and neck 4
The size 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 an appropriate lid (not shown)
The portion of the mouth and neck 2, excluding the annular groove 12, which is important for the sealing of the, the operation of mounting the lid on 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 of the portion of the mouth / neck portion 2 excluding the annular groove 12 (inner diameter x, height y, jaw portion 8)
The outer diameter z, etc.) of (1) can be set to a predetermined value without changing.

After the synthetic resin material 36 is compressed as described above and the preform 2 is formed, as shown in FIG.
As shown in FIG. 3, the male means 14 is lifted to separate the male means 14 from the female means 16. Since the molded pre-molded body 2 defines the lower surface of the support ring 10 formed on the mouth-neck portion 4 of the molded pre-molded body 2 in which the split mold member 20 of the male mold means 14 is molded, It is raised in association with the mold means 14 and is separated from the female mold means 16. Next, as shown in FIG. 4-B, only the core member 18 in the male mold means 14 is further raised, whereby the core member 18 is separated from the pre-molded body 2. Thereafter, as shown in FIG. 4-D, the two split mold pieces 32 constituting the split mold member 20 are moved outward in the radial direction, and the split mold member 20 is also separated from the pre-molded body 2. The pre-molded body 2 thus molded is taken out.

The pre-molded body 2 compression-molded as described above is further subjected to blow molding, which is known per se, so that the blow-molded portion 6 of the pre-molded body 2 has two points in FIG. As partially shown by a chain line, blow molding is performed to mold the main part of the container (the body and the bottom part following the mouth / neck part 4).

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the present invention. It does not require many words that it can be modified. For example, in the illustrated embodiment, the synthetic resin material is supplied to the female mold means in a state in which the male mold means is completely separated from the female mold means, but if desired, the male mold means and the female mold means may be supplied. So that they are partially closed, the synthetic resin material is injected into the space between them, and then the female mold means and the male mold means are completely closed, and the injected synthetic resin material is compression molded. It is also possible to carry out a unique compression molding called compression molding to mold the pre-molded body.

[0022]

According to the present invention, a preformed body can be formed without requiring 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 drawings]

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

2 is a cross-sectional view showing male and female mold means used for compression molding the preform of FIG.

FIG. 3 is a cross-sectional view showing a step of molding the preform 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-molded article molded by using the male mold means and the female mold means shown in FIG.

[Explanation of symbols]

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

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 49/02 B29B 11/12

Claims (3)

(57) [Claims] 1. A support ring which is composed of an annular mouth-neck portion and a bottomed cylindrical blow-molded portion that hangs down from the mouth-neck portion, and a support ring protruding outward in the radial direction is arranged on the outer peripheral surface of the mouth-neck portion. In the synthetic resin pre-molded body that is blow molded into the container by the blow molding, an annular groove is formed on the inner peripheral edge of the lower surface of the support ring, and the amount of the synthetic resin material varies. The dimension of the annular groove and the dimension of the blow-molded portion are varied by the compression of the synthetic resin material by preventing the dimension of the mouth / neck portion from varying except for the annular groove. A pre-molded article characterized by being molded by. 2. A support ring which is composed of an annular mouth-neck portion and a bottomed cylindrical blow-molded portion that hangs down from the mouth-neck portion, and a support ring protruding outward in the radial direction is arranged on the outer peripheral surface of the mouth-neck portion. In the compression molding device for compression molding the preformed body in which the annular groove is formed on the inner peripheral edge of the lower surface of the support ring, the preformed bodies are moved in the directions toward each other and cooperate with each other. A male mold means and a female mold means that are set to a closed state that defines a mold space and that are moved in directions away from each other to be opened. Together with the inner surface, it defines all the surfaces of the mouth and neck except 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. Mutual movement of the male and female means in the closed state due to fluctuations in volume. The size of the annular groove and the size of the blow-molded portion in the compression-molded preform are varied by the variation of the distance, but the size of the mouth / neck is varied except for the annular groove. A compression molding device characterized by the absence of the above. 3. The male mold means includes at least a core member defining an inner surface of the blow-molded portion and an inner peripheral surface of the mouth / 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 composed of a plurality of split mold pieces that are separated from each other by moving the split mold members radially outward.