JP2020082706A - Method for producing extrusion blow container - Google Patents

Abstract

To provide a method for producing an extrusion blow container by forming a step part on an inner peripheral surface of a mouth part while preventing chips from entering into the extrusion blow container as well as the mouth part from reducing dimensional accuracy.SOLUTION: A method for producing an extrusion blow container 1, comprises: a parison forming step; a mold clamping step; a mouth part forming step; and a blowing step, in which on an outer peripheral surface of a plug 22, a first molded step part 23 having a first molded surface 23a facing downward and continuously extending over the entire circumference is formed, and during the mouth part forming step, the first molded step part is pressed against an inner peripheral surface of a parison W to form a step part 15 having a surface facing upward on an inner peripheral surface of a mouth part 11 of the extrusion blow container 1.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing an extrusion blow container.

For example, as disclosed in Patent Document 1 below, a container is known in which a step portion having a surface (hereinafter referred to as a step surface) facing upward is formed on the inner peripheral surface of the mouth portion. In this container, for example, it becomes possible to fill the content liquid with the tip opening edge of the filling nozzle abutting against the step surface, or when the content liquid is refilled into another container, It is possible to prevent the inner peripheral surface from sticking to the entire area by surface tension and staying in the mouth.
It is conceivable to form this container by extrusion blow molding.

In extrusion blow molding, first, a parison formed by extrusion molding and extending in the vertical direction is radially sandwiched by a pair of molding dies, and the lower end opening of the parison is closed with the upper end opening of the parison open, and then the parison. Insert the plug from the top opening into it and fit it, sandwich the parison with the outer peripheral surface of the plug and the inner surface of the cavity, mold the mouth of the extrusion blow container, and then from the supply hole formed in the plug. Pressurized air is supplied to stretch the part of the parison located below the molded mouth and press it against the inner surface of the cavity to mold the shoulder, body, and bottom of the extrusion blow container.
Conventionally, when forming the above-mentioned step portion, the inner peripheral surface of the mouth portion of the extrusion blow container is cut.

JP, 2002-347731, A

However, in the conventional method for manufacturing an extrusion blow container, since the step is formed by cutting the inner peripheral surface of the mouth, there is a risk that chips may enter the extrusion blow container, and There is a problem that the mouth portion is easily deformed by frictional heat generated during processing, rotational torque, etc., and it is difficult to form the mouth portion accurately. The latter problem may become apparent when a step is formed at a deep position in the mouth.

The present invention has been made in consideration of such circumstances, and prevents the chips from entering the extrusion blow container and the dimensional accuracy of the mouth from being reduced, while the inner peripheral surface of the mouth is prevented. It is an object of the present invention to provide a method for manufacturing an extrusion blow container capable of forming a step.

In order to solve the above problems and to achieve such an object, the method for producing an extrusion blow container of the present invention is a parison forming step of forming a parison extending in the vertical direction by extrusion molding, and a pair of molding dies. A mold clamping step of sandwiching the parison in the radial direction, closing the lower end opening of the parison with the upper end opening of the parison open, and positioning the parison in the cavity between the pair of molding dies, A plug is inserted into the parison from its upper end opening and fitted, the parison is sandwiched between the outer peripheral surface of the plug and the inner surface of the cavity, and a mouth portion forming step of forming the mouth portion of the extrusion blow container, Pressurized air is supplied from the supply hole formed in the plug, the part of the parison located below the formed mouth part is stretched, and pressed against the inner surface of the cavity to form the shoulder part of the extrusion blow container. A method for manufacturing an extrusion blow container, which comprises a first step, a step of molding a body, and a bottom, and a first molding surface facing downward and continuously extending over the entire circumference on the outer peripheral surface of the plug. 1 molding step portion is formed, and at the time of the mouth portion molding step, the first molding step portion is pressed against the inner peripheral surface of the parison so that the inner peripheral surface of the mouth portion has a surface facing upward. Mold the part.

According to this invention, the first molding step portion of the plug is pressed against the inner peripheral surface of the parison during the mouth portion forming step so that the inner peripheral surface of the mouth portion of the extrusion blow container has a surface facing upward. Since the part is molded, it is possible to form a step without generating chips and frictional heat, and chips may enter the extrusion blow container or the dimensional accuracy of the mouth part may deteriorate. It is possible to form a step on the inner peripheral surface of the mouth while preventing the above.
As mentioned above, since the step is not formed by cutting, it is possible to prevent loads such as frictional heat and rotational torque from being applied to the mouth, and even if the mouth is at a deep position near the shoulder. Even when the step portion is formed in, the mouth portion can be formed with high accuracy.
If the step portion is formed at a deep position of the mouth portion, the content liquid can stick to the inner peripheral surface of the mouth portion due to surface tension when refilling into another container, and the vertical length of the inner peripheral surface of the mouth portion is increased. It becomes shorter and the amount of the content liquid remaining in the mouth can be suppressed more reliably.

Here, on the outer peripheral surface of the plug, there is formed a second molding step portion that is located above the first molding step portion, faces downward, and has a second molding surface that extends continuously over the entire circumference. On the inner surface of the, gradually, as it goes upward, an inclined surface extending toward the outer side in the radial direction is formed, and during the mouth portion forming step, the second forming step portion is pressed against the inner peripheral surface of the parison, While molding the upper end opening edge of the mouth portion, the outer peripheral edge of the second molding surface is brought into contact with or close to the inclined surface, and a portion of the parison located above the formed mouth portion is formed. To remove.

In this case, during the mouth forming step, the second forming step is pressed against the inner peripheral surface of the parison to form the upper opening edge of the mouth of the extrusion blow container, and the inner surface of the cavity is inclined to the first inner surface. (2) The outer peripheral edge of the molding surface is brought into contact with or in close proximity to the parison, and a portion of the parison located above the molded mouth is cut off.
That is, at the time of forming the mouth portion, the upper opening edge of the mouth portion of the extrusion blow container and the step portion are formed, and at the same time, the part of the parison located above the formed mouth portion is cut off. The blow container can be efficiently formed.

ADVANTAGE OF THE INVENTION According to this invention, a step part can be formed in the inner peripheral surface of a mouth part, preventing that a chip|tip enters into an extrusion blow container and a dimensional accuracy of a mouth part falls.

It is a semi-longitudinal sectional view showing the important section of the extrusion blow container shown as one embodiment concerning the present invention. It is explanatory drawing explaining the manufacturing method of the extrusion blow container shown as one Embodiment which concerns on this invention. It is a semi-longitudinal sectional view showing the important section of the extrusion blow container shown as a modification concerning the present invention.

Hereinafter, a method for manufacturing an extrusion blow container according to an embodiment of the present invention will be described with reference to the drawings.
First, the extrusion blow container 1 will be described.
As shown in FIG. 1, the extrusion blow container 1 of the present embodiment includes a mouth portion 11, a shoulder portion 12, a body portion 13, and a bottom portion, which are arranged along a common axis O from the upper side to the lower side. It is constructed by connecting in sequence. The mouth portion 11, the shoulder portion 12, the body portion 13, and the bottom portion are arranged coaxially with the common axis O. Hereinafter, the direction along the common axis O is referred to as the up-down direction, the direction intersecting with the common axis O when viewed from the up-down direction is referred to as the radial direction, and the direction around the common axis O is referred to as the circumferential direction.

The extrusion blow container 1 is integrally formed of a synthetic resin material. Examples of synthetic resin materials include polypropylene, polyethylene, and polyethylene terephthalate. The extrusion blow container 1 is not limited to being formed of one kind of synthetic resin material, but may be formed by laminating different kinds of synthetic resin materials.
In the latter case, the layers laminated to each other may or may not be peelable. A configuration in which different kinds of synthetic resin materials are laminated can be formed more easily by extrusion blow molding than by injection molding and stretch blow molding using a preform.

For example, the extrusion blow container 1 may be formed by laminating two kinds of synthetic resin materials, that is, a main resin and a barrier resin.
In this case, examples of the main resin include polypropylene and the like. The barrier resin is a synthetic resin having a barrier property that restricts, for example, gas (oxygen, carbon dioxide, etc.), moisture such as humidity, light such as ultraviolet rays, and odorous components such as scents from passing through the main resin. It is a resin material and is appropriately selected according to the object to be barrier.
For example, a nylon resin, an ethylene vinyl alcohol copolymer resin, or the like is used to exhibit a gas barrier property, and a cyclic polyolefin resin or the like is used to exhibit a water barrier property.

A male screw portion 11 a is formed on the outer peripheral surface of the mouth portion 11. The upper opening edge 11b of the mouth portion 11 is a flat surface extending in a direction orthogonal to the common axis O in a vertical cross-sectional view taken along the up-down direction. The outer peripheral edge of the upper end opening edge 11b of the mouth portion 11 is a cutting trace 11c that is sharpened radially outward with respect to the outer peripheral surface of the mouth portion 11.

The upper end portion of the inner peripheral surface of the mouth portion 11 gradually extends outward in the radial direction as it goes upward. The upper portion of the inner peripheral surface of the mouth portion 11 is located radially outward of the lower portion of the inner peripheral surface of the mouth portion 11. The male screw portion 11a is integrally formed on the upper and lower portions of the outer peripheral surface of the mouth portion 11. A step portion 15 having a surface facing upward is formed on the inner peripheral surface of the mouth portion 11. The step portion 15 is located at a connecting portion between the upper portion and the lower portion on the inner peripheral surface of the mouth portion 11.

The angle of inclination of the upward facing surface of the step portion 15 with respect to the vertical direction is about 90°. As a result, for example, it becomes possible to fill the content liquid in a state where the tip opening edge of the filling nozzle is abutted against the upward facing surface of the stepped portion 15, or when the content liquid is refilled into another container. However, it is possible to reliably prevent the inner peripheral surface of the mouth portion 11 from being stuck to the inner peripheral surface of the mouth portion 11 due to surface tension and staying in the mouth portion 11.

The inclination angles of the upper part and the lower part on the inner peripheral surface of the mouth part 11 with respect to the horizontal direction orthogonal to the vertical direction are 85.0° or more and 89.9° or less, preferably 89.0° or more and 89.5° or less. Is becoming
On the inner peripheral surface of the mouth portion 11, a connecting portion between the lower portion and the step portion 15 is formed into a curved surface projecting radially inward. The radius of curvature of this connecting portion in the vertical cross-sectional view along the vertical direction is 0.05 mm or more.
On the inner peripheral surface of the mouth portion 11, a connecting portion between the upper portion and the step portion 15 is formed in a curved surface shape that is recessed radially outward. The radius of curvature of this connecting portion in the vertical cross-sectional view along the vertical direction is 0.05 mm or more.

Next, a method for manufacturing the extrusion blow container 1 configured as described above will be described.

First, the parison W is formed by extrusion molding (parison forming step). At this time, the parison W is extruded downward from the die head and extends vertically.
Next, the parison W extruded from the die head is radially sandwiched by the pair of molding dies 21, and the lower end opening of the parison W is closed while the upper end opening of the parison W is opened, and the parison W It is positioned in the cavity 21a between the molding dies 21 (mold clamping step).

Next, as shown in FIG. 2, the plug 22 is fitted into the parison W from the upper end opening thereof, and the upper part of the parison W is sandwiched between the outer peripheral surface of the plug 22 and the inner surface of the cavity 21a. The mouth 11 of the extrusion blow container 1 is molded (mouth molding step).
Here, on the outer peripheral surface of the plug 22, a first molding step portion 23 having a first molding surface 23a facing downward and continuously extending over the entire circumference is formed.
During the mouth portion forming step, the first forming step portion 23 is pressed against the inner peripheral surface of the upper part of the parison W to form the step portion 15 on the inner peripheral surface of the mouth portion 11.

Here, on the outer peripheral surface of the plug 22, there is formed a second molding step portion 24 that is located above the first molding step portion 23, faces downward, and has a second molding surface 24a that extends continuously over the entire circumference. ing. On the inner surface of the cavity 21a, an inclined surface 21b is formed which gradually extends outward in the radial direction as it goes upward. The inclined surface 21b is located at the upper end of the inner surface of the cavity 21a.

During the mouth forming step, the second forming step portion 24 is pressed against the inner peripheral surface of the upper part of the parison W to form the upper end opening edge 11b of the mouth portion 11, and the inclined surface 21b is provided with the second forming surface 24a. The outer peripheral edge is brought into contact with or brought close to the parison W, and the part of the parison W located above the formed opening 11 is cut off. At this time, the outer peripheral edge of the second molding surface 24a is in contact with or close to the lower end of the inclined surface 21b of the inner surface of the cavity 21a. Further, a cut mark 11c is formed on the upper edge 11b of the mouth 11.

Next, pressurized air is supplied from the supply hole 22a formed in the plug 22, and the part of the parison W located below the formed opening 11 is stretched and pressed against the inner surface of the cavity 21a (blow). Process). As a result, the shoulder portion 12, the body portion 13, and the bottom portion are molded to form the extrusion blow container 1.

As described above, according to the method for manufacturing the extrusion blow container according to the present embodiment, the first molding step portion 23 of the plug 22 is pressed against the inner peripheral surface of the parison W during the mouth molding step to perform extrusion blow molding. Since the step portion 15 having the surface facing upward is formed on the inner peripheral surface of the mouth portion 11 of the container 1, it becomes possible to form the step portion 15 without generating chips and frictional heat, and extruding. The step portion 15 can be formed on the inner peripheral surface of the mouth portion 11 while preventing chips from entering the blow container 1 and reducing the dimensional accuracy of the mouth portion 11.

As described above, since the step portion 15 is not formed by cutting, it is possible to prevent a load such as frictional heat and a rotational torque from being applied to the mouth portion 11. For example, as shown in FIG. Moreover, even when the step portion 15 is formed at a deep position of the mouth portion 11 near the shoulder portion 12, the mouth portion 11 can be formed with high accuracy.
When the step portion 15 is formed at a deep position of the mouth portion 11, the content liquid can stick to the inner peripheral surface of the mouth portion 11 due to surface tension when refilling into another container. Is shortened, and the amount of the content liquid remaining in the mouth portion 11 can be suppressed more reliably.

In the present embodiment, at the time of forming the mouth portion, the second forming step portion 24 is pressed against the inner peripheral surface of the parison W to form the upper end opening edge 11b of the mouth portion 11 of the extrusion blow container 1 and the cavity 21a. The outer peripheral edge of the second molding surface 24a is brought into contact with or close to the inclined surface 21b of the inner surface of the parison W, and the part of the parison W located above the molded mouth portion 11 is cut off.
That is, at the same time as molding the upper end opening edge 11b of the mouth portion 11 of the extrusion blow container 1 and the step portion 15 in the mouth portion forming step, the portion of the parison W located above the formed mouth portion 11 is formed. Since it is cut off, the extrusion blow container 1 can be efficiently formed.

The present invention is not limited to the above-described embodiments, but can be modified as appropriate without departing from the spirit of the invention.

For example, in the above-described embodiment, the portion of the parison W located above the formed mouth portion 11 is cut out during the mouth portion forming step, but the second forming surface 24a is pressed against the upper opening edge of the parison W. The upper edge 11b of the mouth 11 may be molded.

Besides, it is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the spirit of the present invention, and the above-described modified examples may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 extrusion blow container 11 mouth part 11b upper end opening edge 15 step part 21 molding die 21a cavity 21b inclined surface 22 plug 22a supply hole 23 first molding step part 23a first molding surface 24 second molding step part 24a second molding surface W parison

Claims (2)

A parison forming step of forming a parison extending in the vertical direction by extrusion molding;
The parison is radially sandwiched by a pair of molding dies, the lower end opening of the parison is closed while the upper end opening of the parison is opened, and the parison is positioned in the cavity between the pair of molding dies. Mold clamping process,
A plug is inserted from the upper end opening into the parison and fitted, the parison is sandwiched by the outer peripheral surface of the plug and the inner surface of the cavity, and a mouth portion forming step of forming the mouth portion of the extrusion blow container,
Pressurized air is supplied from the supply hole formed in the plug, the part of the parison located below the formed mouth part is stretched, and pressed against the inner surface of the cavity to push the shoulder of the extrusion blow container. A method for manufacturing an extrusion blow container having a blow step of molding a bottom portion, a body portion, and a bottom portion,
On the outer peripheral surface of the plug, a first molding step portion having a first molding surface facing downward and continuously extending over the entire circumference is formed,
An extrusion blow container in which, during the mouth portion forming step, the first forming step portion is pressed against the inner peripheral surface of the parison to form a step portion having an upward facing surface on the inner peripheral surface of the mouth portion. Manufacturing method. On the outer peripheral surface of the plug, there is formed a second molding step portion that is located above the first molding step portion, faces downward, and has a second molding surface that continuously extends over the entire circumference,
An inclined surface is formed on the inner surface of the cavity, which gradually extends toward the outer side in the radial direction as it goes upward.
At the time of forming the mouth portion, the second forming step portion is pressed against the inner peripheral surface of the parison to form the upper end opening edge of the mouth portion, and the inclined surface is formed outside the second forming surface. The method for producing an extrusion blow container according to claim 1, wherein the peripheral edge is brought into contact with or brought close to, and a portion of the parison located above the formed mouth portion is cut off.

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