JP4724920B2 - Compression molding device for preformed body for blow molding container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is composed of an annular mouth-neck portion and a bottomed cylindrical blow-molded portion depending from the neck-and-neck portion, and compression-molds a synthetic resin preform that is blow-molded into a container. that on the equipment.
[0002]
[Prior art]
As containers for beverages and the like, synthetic resin containers made of an appropriate synthetic resin such as polyethylene terephthalate are widely used in practice. Such a synthetic resin container is generally formed by injection-molding a preformed body comprising an annular mouth-neck portion and a bottomed cylindrical blow-molded portion depending from the neck-and-neck portion, and then the blow-molded portion of the preformed body. Is produced by blow molding or stretch blow molding. The mouth-and-neck portion of the preformed body defines the mouth-and-neck portion of the container, and a support ring is usually formed on the outer peripheral surface thereof. When the container is sealed by attaching a lid to the mouth and neck after filling the contents in the container, the container is held by supporting the lower surface of the support ring.
[0003]
Thus, the conventional manufacturing mode of the synthetic resin container has a problem that the molding efficiency in the injection molding of the preform is limited, and the preform cannot be molded with high molding efficiency. In order to mold the preform with high molding efficiency, it is intended to adopt compression molding instead of injection molding. However, when the pre-molded body is compression molded, there are problems to be solved as follows. That is, in the case of compression molding, it is necessary to fill the mold with a synthetic resin material before closing the mold and defining the mold cavity. The filling of the synthetic resin material is performed by, for example, extruding a softened or molten synthetic resin material from an extruder and separating the synthetic resin material from the extrusion port of the extruder. Due to this, it is extremely difficult to control the filling amount of the synthetic resin material with sufficient precision, and there is usually an error of about 0.5 to 1.0% in the filling amount of the synthetic resin material. Such an error in the amount of the synthetic resin material is caused by moving the first mold means and the second mold means constituting the mold in a direction close to each other so that they are closed, and the synthetic resin material is synthesized between the two. The mutual distance between the first mold means and the second mold means when the resin material is compression molded is varied. Therefore, usually, a slight variation is generated in the dimensions such as the thickness and the outer diameter of the entire pre-formed body that has been compression-molded. Slight fluctuations in the dimensions of the blow molded part of the pre-molded body do not cause any particular problem, but if slight fluctuations are generated in the main dimensions such as the height of the mouth and neck, the inner and outer diameters, When the lid is attached to the mouth and neck, due to the dimensional variation of the part where the sealing means disposed on the lid is brought into close contact, the required sealing characteristics cannot be achieved. (B) From the lower surface of the support ring to the mouth and neck There are many possibilities that unacceptable problems such as various obstacles occur in the automatic lid mounting operation for mounting the lid on the mouth and neck due to the fluctuation of the height to the tip of the section.
[0004]
In Japanese Patent Laid-Open No. 10-337769, an annular groove is formed on the inner peripheral edge of the lower surface of the support ring in order to solve the problems as described above when compression molding the preform. In this way, the depth of the annular groove can be changed along with the thickness of the blow-molded part according to the fluctuation of the filling amount of the synthetic resin material, thereby changing the filling amount of the synthetic resin material. First, a compression molding mode is disclosed in which the shape and dimensions of the mouth and neck are made constant.
[0005]
[Problems to be solved by the invention]
However, the compression molding mode as described above disclosed in JP-A-10-337769 is still not fully satisfactory and has the following problems. That is, since an annular groove is formed in the support ring, particularly when the depth of the annular groove is relatively deep, the strength of the support ring or the vicinity thereof is excessively low, and when the preform is stretched prior to blow molding or When the blow molded part of the preform is blown, the preform may be deformed or damaged.
[0006]
The present invention has been made in view of the above-mentioned facts, and the main technical problem thereof is that the low-strength portion is not locally generated in the pre-molded body, regardless of the variation in the filling amount of the synthetic resin material. by providing the overall height of the can allowed to constant, new and improved equipment for compression molding preform of the preform with allowed to the shape and dimensions of the neck of the preform constant is there.
[0010]
[Means for Solving the Problems]
According to the present invention, as a compression molding apparatus that achieves the main technical problem, the compression molding apparatus includes an annular mouth-neck portion and a bottomed cylindrical blow-molded portion depending from the neck-and-neck portion, and the blow-molded portion is blow-molded. In a compression molding device for a preform for a blow molded container to be a container,
A first mold means for defining at least a portion other than the lower part of the outer peripheral surface of the mouth neck together with the upper end surface of the mouth neck; and a second mold means for defining the outer surface of the blow molded part A third mold means that is movably inserted into the central through opening formed in the first mold means and defines at least the inner surface of the blow-molded portion,
The second mold means is filled with a soft or molten synthetic resin material, and then the first mold means, the second mold means, and the third mold means cooperate with each other. Is closed in a state defining the temporary mold cavity, and then the relationship between the first mold means and the second mold means is maintained without being changed . Means is moved relative to the first mold means and the second mold means to reduce the thickness of the portion defining the blow mold in the temporary mold cavity; Is provided.
[0011]
In a preferred embodiment, the third mold means defines a lower portion of the inner peripheral surface of the mouth and neck portion together with the inner surface of the blow molded portion, and the first mold means includes the mouth and neck portion. A first mold member that defines at least a portion other than the lower portion of the outer peripheral surface of the first portion, and a second portion that defines a portion other than the lower portion of the inner peripheral surface of the mouth and neck portion together with the upper end surface of the mouth and neck portion. And a mold member. In another preferred embodiment, the third mold means defines the entire inner peripheral surface of the mouth neck together with the inner surface of the blow molded part, and the first mold means comprises the mouth A first mold member that defines at least a portion of the outer peripheral surface of the neck portion other than the lower portion; and a second mold member that defines the upper end surface of the mouth neck portion.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of a compression formed KatachiSo location constructed according to the present invention will be described in detail with reference to the accompanying drawings.
[0013]
1 shows a typical example of the preform to be molded with a preferred embodiment of a compression formed KatachiSo location of the present invention is illustrated. A pre-molded body generally indicated by numeral 2 and compression-molded from an appropriate synthetic resin such as polyethylene terephthalate is composed of an annular mouth-neck portion 4 and a bottomed cylindrical blow-molded portion 6 depending from the mouth-neck portion 4. It is configured. The mouth-and-neck part 4 has a substantially cylindrical shape as a whole, and a male thread 8 is formed at the upper part of the outer peripheral surface. An annular support ring 12 is formed at the lower part of the mouth-and-neck portion 4 so as to protrude outward in the radial direction. The blow molding part 6 following the mouth / neck part 4 includes a substantially cylindrical body part 14 and a hemispherical bottom part 16 extending downward. In preform 2 in the illustrated embodiment, the region ranging from the inner peripheral surface lower part of the neck 4 to the inner peripheral surface upper portion of the blow molding unit 6, frustoconical inner diameter downward is reduced slightly Part 17 exists. As shown by a two-dot chain line in FIG. 1, blow molding is applied to the blow molding portion 6 or blow molding is applied after stretch molding is performed, and thus a container having a required shape is formed.
[0014]
FIG. 2 illustrates a compression molding apparatus for compression molding the preform 2. The illustrated compression molding apparatus includes a first mold means 18, a second mold means 20, and a third mold means 22. The first mold means 18 and the third mold means 22 are mounted on a movable substrate 24 that can be moved up and down. On the other hand, the second mold means 20 is mounted on a stationary substrate (not shown). If desired, instead of or in addition to mounting the first mold means 18 and the third mold means 22 on the movable substrate 24, the second mold means 20 is mounted on the movable substrate, The second mold means 20 can be moved up and down relatively with respect to the first mold means 18 and the third mold means 22.
[0015]
First molding die means 18 in the illustrated embodiment includes a first mold member 26 and a second mold member 28. The second mold member 28 is suspended from the movable substrate 24 via a plurality of suspension rods 29 arranged at intervals in the circumferential direction, and is moved up and down in accordance with the movement of the movable substrate 24. . The first mold member 26 is combined with the lower end portion of the second mold member 28. The first mold member 26 is composed of two arc-shaped portions 26a and 26b extending over an angle of 180 degrees, and is provided with a moving means (not shown) for moving in the circumferential direction. Has been. Therefore, the first mold member 26 is moved up and down in accordance with the up and down movement of the movable substrate 24 and is moved in the circumferential direction separately from the up and down movement. The first mold member 26 is a portion of the outer periphery of the mouth-and-neck portion 4 in the preform 2 other than the lower part, more specifically, the lower peripheral edge of the support ring 12 on the outer-periphery of the mouth-and-neck portion 4. An inner peripheral surface 30 that defines a portion above the lower surface of the inner peripheral surface. The second mold member 28 has a thin cylindrical protrusion 32 protruding downward, and the outer peripheral surface 34 of the protrusion 32 defines the upper part of the inner peripheral surface of the mouth neck 4 in the preform 2. Further, the downwardly facing annular shoulder surface 36 located at the base end of the protruding portion 32 in the second mold member 28 defines the upper end surface of the mouth and neck portion 4 in the preformed body 2.
[0016]
The second mold means 20 has a columnar shape as a whole, and a thin cylindrical protruding portion 38 protruding upward is formed at the center of the upper surface. A blind hole 40 extending downward is formed inside the protrusion 38. The upper surface 42 of the protrusion 38 defines the inner peripheral edge of the lower surface of the support ring 12 formed on the outer peripheral surface of the mouth-and-neck portion 4 in the preform 2. The inner surface 44 of the blind hole 40 is, together with the lower part of the inner peripheral surface of the mouth-and-neck part 4 in the pre-formed body 2 (more specifically, the part below the lower surface of the support ring 12 formed on the outer peripheral surface). 6 outer surface is defined.
[0017]
The second mold member 28 of the first mold means 18 is formed with a central through opening 46 extending through the central portion thereof, and the third mold means 22 moves to the central through opening 46. It is comprised from the elongate column-shaped member inserted freely. A shoulder surface 48 facing upward is formed in the middle portion of the outer peripheral surface of the third mold means 22, and the outer peripheral surface 50 of the portion above the shoulder surface 48 has a cylindrical shape extending substantially vertically. The outer diameter of the outer peripheral surface 50 is made to correspond to the inner diameter of the central through opening 46. The outer peripheral surface 52 of the portion below the shoulder surface 48 has a cylindrical part extending substantially vertically, followed by a truncated cone part with an inner diameter slightly decreasing downward, and subsequently followed by a substantially vertical part. The lower end portion has a hemispherical shape. The outer peripheral surface below the shoulder surface 48 in the third mold means 22 defines the inner surface of the blow-molded portion 6 together with the lower portion of the inner peripheral surface of the mouth-and-neck portion 4 in the front molded body 2. Elevating / lowering means 54 (only a part of which is shown) is attached to the upper end of the third mold means 22 for moving the third mold means 22 up and down with respect to the movable substrate 24. The elevating / lowering means 54 can be formed from an appropriate means such as a hydraulic or pneumatic cylinder mechanism. With respect to the first mold means 18, the third mold means 22 has a shoulder surface 48 on the lower end surface of the protruding portion 32 formed on the second mold member 28 of the first mold means 18. It is moved up and down relatively from the ascending position (position shown in FIG. 1) where it abuts.
[0018]
The compression molding method of the preform 2 by the compression molding apparatus as described above will be described as follows. When starting the compression molding, as shown in FIG. 2, the movable substrate 24 is moved to the raised position, and the first mold means 18 and the third mold means 22 are the second mold. It is spaced upwardly from the means 20. Then, the soft resin or molten synthetic resin material 56 is filled into the blind hole 40 of the second mold means 20. The synthetic resin material 56 such as polyethylene terephthalate can be conveniently filled by extruding from an extrusion port of an extruder (not shown) and separating from the extrusion port. As is well known to those skilled in the art, it is extremely difficult if not impossible to control the filling amount of the synthetic resin material 56 with sufficient precision, and usually an error of about 0.5 to 1.0% occurs. . In a preferred embodiment of the compression molding method according to the present invention, when the movable substrate 24 is lowered and the first mold means 18 is lowered to the lowest position relative to the second mold means 20 (third in the mold section 22 the state shown in the first tentative molding cavity that is defined in the allowed are) lowered with the first mold unit 18 has been brought located at the uppermost position with respect to the mold means 18 (i.e. 3 A synthetic resin material 56 having a volume V2 slightly larger than the volume V1 of the provisional molding cavity) is filled.
[0019]
Next, the movable substrate 24 is lowered, and the first mold means 18 and the third mold means 22 are lowered with respect to the second mold means 20 (in this case, the third mold means 22). Is first positioned at the uppermost position with respect to the mold means 18), and the synthetic resin material 56 is gradually compressed. Thus, as described above, the volume V2 of the filled synthetic resin material 56 is defined by provisional molding that is defined when the mold means 18 is first lowered to the lowest position relative to the second mold means 20. The first mold means 18 and the third mold means 22 are shown in FIG. 3 in the initial stage of compression molding even if the volume V1 of the cavity is larger and therefore the movable substrate 24 is lowered at the required pressure. The first mold means 18 and the third mold means 22 cannot be lowered to the position, and are positioned slightly above the position shown in FIG. When the filled synthetic resin material 56 is cooled and gradually contracted over time, the first mold means 18 and the third mold means 22 are gradually lowered accordingly. When the volume of the synthetic resin material 56 is reduced to the volume V1 of the temporary molding cavity, the first mold means 18 and the third mold means 22 are lowered to the positions shown in FIG. A cavity is defined.
[0020]
Even after that, the synthetic resin material 56 continues to be cooled and its volume is gradually reduced. In the compression molding method and apparatus constructed according to the present invention, after the provisional molding cavity is defined as described above, the third mold means 22 is at a predetermined pressure in response to the shrinkage of the synthetic resin material 56. Can be lowered. As can be understood by comparing FIGS. 3 and 4, the third mold means 22 gradually descends from the state shown in FIG. 3 where the provisional cavity is defined toward the state shown in FIG. When squeezed, the shape and size of the portion defining the mouth and neck portion 4 of the preform 2 in the temporary molding cavity are not substantially changed, but the thickness of the portion defining the blow molded portion 6, particularly blow molding. The part defining the lower end of the part 6 is gradually reduced. Thus, until the synthetic resin material 56 is sufficiently cooled, the third mold means 22 is gradually lowered to reach the state shown in FIG. 4, and the preform 2 is molded. When the third mold means 22 is lowered with respect to the first mold means 18, the second mold in the first mold means 18 is understood by comparing and referring to FIGS. The lower end surface of the protrusion 32 formed on the member 28 and the shoulder 48 of the third mold means 22 are separated from each other, and a slight gap 58 is generated between them. However, when the third mold means 22 is lowered, the synthetic resin material 56 is cooled to a considerably low temperature, particularly in the portion that defines the mouth-and-neck portion 4 of the preform 2. According to such experience, the synthetic resin material 56 does not flow into the gap 58 (even if the synthetic resin material 56 slightly flows into the gap 58, the gap is formed in the mouth neck 4 of the preform 2. Therefore, the sealing performance of the mouth / neck portion 4 is not adversely affected).
[0021]
The following facts should be noted in compression molding as described above. That is, even if there is a slight variation in the volume of the filled synthetic resin material 56, the state illustrated in FIG. 3 is always established, and the variation in the filling amount of the synthetic resin material 56 is from the state illustrated in FIG. The third mold means 22 is compensated for by the variation of the descending amount. Therefore, the variation in the filling amount of the synthetic resin material 56 is compensated for by changing the thickness of the blow molded portion 6 without substantially changing the shape and size of the mouth-and-neck portion 4 of the preform 2.
[0022]
After the synthetic resin material 56 compression-molded to the required shape is sufficiently cooled, the movable substrate 24 is raised and the pre-molded body 2 molded from the second mold means 20 is released. Next, the third mold means 22 is raised with respect to the first mold means 18, and the two portions 26a and 26b constituting the first mold member 26 in the first mold means 18 are moved. The preformed body 2 can be removed from the first mold means 18 and the third mold means 22 by moving outward in the radial direction, and the compacted preform 2 can be taken out.
[0023]
5 to 7 show a modification of the compression molding method and apparatus. In the modification shown in FIGS. 5 to 7, the second mold member 128 in the first mold means 118 does not have a thin cylindrical protrusion (see the protrusion 32 in FIG. 2). Therefore, the second mold member 128 of the first mold means 118 defines only the upper end surface of the mouth-and-neck portion 4 in the preform 2 and does not define the inner peripheral surface of the mouth-and-neck portion 4. In the modification shown in FIGS. 5 to 7, the third mold means 122 has a shoulder surface (see the shoulder surface 48 in FIG. 2) on the outer peripheral surface of the third mold means 122. The upper half of the outer peripheral surface has a cylindrical shape that extends substantially vertically, and the third mold means 122 includes the entire inner peripheral surface of the mouth-and-neck portion 4 and the entire inner surface of the blow-molded portion 6 in the preform 2. It prescribes. 5 to FIG. 7, the third mold means 122 is lowered with respect to the first mold means 118 from the state shown in FIG. However, no gap (see gap 58 in FIG. 4) is created inside the mold cavity. On the other hand, in the modification shown in FIGS. 5 to 7, the mouth-and-neck portion 4 of the pre-molded body 2 is shaped as required, but when the synthetic resin material 156 is still not sufficiently cooled, The third mold means 122 is moved not only between the lower part of the inner peripheral surface of the neck 4 but also the upper part of the inner peripheral surface which is relatively important for the sealing performance of the mouth and neck part 4. In addition, slips are generated that are desirable to avoid. Except for the above-described points of the compression molding apparatus shown in FIGS. 5 to 7 and the compression molding method using the same, the compression molding apparatus shown in FIGS. 2 to 4 and the compression molding method using the same are substantially the same. .
[0024]
【The invention's effect】
According to the compression forming KatachiSo location of the present invention, locally without allowed to accompany the problems such as allowed to produce a portion of the low strength preform, despite variations in the filling amount of the synthetic resin material, preform It is possible to make the shape and size of the neck and neck of the body constant and to make the total height of the preformed body constant .
[Brief description of the drawings]
FIG. 1 is a half cross-sectional view illustrating a typical example of a preform to be molded in a preferred embodiment of a compression formed KatachiSo location of the present invention.
FIG. 2 is a sectional view showing a preferred embodiment of the compression molding apparatus of the present invention in an initial state of a compression molding process.
3 is a cross-sectional view showing the compression molding apparatus shown in FIG. 2 in an intermediate state of a compression molding process.
4 is a sectional view showing the compression molding apparatus shown in FIG. 2 in a final state of a compression molding process.
FIG. 5 is a cross-sectional view showing a modification of the compression molding apparatus of the present invention in an initial state of a compression molding process.
6 is a cross-sectional view showing the compression molding apparatus shown in FIG. 5 in an intermediate state in a compression molding process.
7 is a sectional view showing the compression molding apparatus shown in FIG. 5 in the final state of the compression molding process.
[Explanation of symbols]
2: Pre-molded body 4: Mouth neck portion 6 of preformed body 6: Blow-molded section 18 of preformed body 18: First mold means 20: Second mold means 22: Third mold means 56: Synthesis Resin material 118: First mold means 120: Second mold means 122: Third mold means 156: Synthetic resin material

Claims (3)

It is composed of an annular mouth-neck part and a bottomed cylindrical blow-molded part that hangs down from the mouth-neck part.
A first mold means for defining at least a portion other than the lower part of the outer peripheral surface of the mouth neck together with the upper end surface of the mouth neck; and a second mold means for defining the outer surface of the blow molded part A third mold means that is movably inserted into the central through opening formed in the first mold means and defines at least the inner surface of the blow-molded portion,
The second mold means is filled with a soft or molten synthetic resin material, and then the first mold means, the second mold means, and the third mold means cooperate with each other. Is closed in a state defining the temporary mold cavity, and then the relationship between the first mold means and the second mold means is maintained without being changed . Means is moved relative to the first mold means and the second mold means to reduce the thickness of the portion defining the blow mold in the temporary mold cavity; A device characterized by. The third mold means defines the lower part of the inner peripheral surface of the mouth and neck part together with the inner surface of the blow molded part, and the first mold means includes at least the outer peripheral surface of the mouth and neck part. A first mold member that defines a part other than the lower part; and a second mold member that defines a part other than the lower part of the inner peripheral surface of the mouth and neck part together with the upper end surface of the mouth and neck part. The apparatus of claim 1 . The third mold means defines the entire inner peripheral surface of the mouth / neck portion together with the inner surface of the blow-molded portion, and the first mold means includes at least the outer peripheral surface of the mouth / neck portion. having a first mold member defining a portion other than the bottom, and a second mold member defining the upper end surface of the mouth neck apparatus according to claim 1.

Images