JP2002248650A - Method and apparatus for manufacturing blow molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blow molded article manufacturing apparatus capable of more enhancing productivity. SOLUTION: The blow molded article manufacturing apparatus is constituted so that the blow molded article is divided into two parts, that is, upper and lower divided bodies and the respective upper and lower divided bodies are molded to be joined to manufacture the blow molded article and equipped with an upper mold 1 which has first cavities 12a and 12b for molding the upper divided body, first projected parts 13a and 13b for molding the inner peripheral surface of the lower divided body and first recessed parts 14a and 14b for housing second projected parts 22a and 22b for molding the upper divided body on the same circumference of a circle, a lower mold 2 which has second cavities 23a and 23b for molding the lower divided body, second projected parts 22a and 22b for molding the inner peripheral surface of the upper divided body and second recessed parts 24a and 24b for housing the first projected parts 13a and 13b for molding the lower divided body on the same circumference of a circle and a drive part 6 for relatively rotating the upper and lower molds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a hollow molded article by injection molding.

[0002]

2. Description of the Related Art Conventionally, a hollow molded product manufactured by injection molding of a resin is disclosed in Japanese Patent Publication No. 2-38377,
As described in JP-A-1-193815, JP-A-6-297501, JP-A-8-34031, etc., the main configuration is as follows.

[0003] In a single mold, one or a plurality of two-piece hollow bodies are formed, and the divided surfaces of the divided bodies are butted by moving a template, and molten resin is applied to the butted surfaces. It is welded by injection to form one hollow body.

[0004] For example, in Japanese Patent Publication No. 2-38377,
The forming mold is composed of a fixed mold plate having a single sprue, a slide mold plate forming an upper split body, and a movable mold plate forming a lower split body. The mold plate is slid along the fixed mold plate, the upper and lower divided bodies are butted on the divided surface, and resin is injected into a gap between the divided surfaces and welded. In this case, the welding sprue is configured to communicate with the fixed sprue.

[0005]

However, in these prior arts, it is necessary to slide the mold plate along the fixed mold plate, which complicates the mold structure.
It is difficult to deal with many pieces, it is difficult to adapt hot runners,
There were problems such as difficulty in shortening the cycle, and it was difficult to improve productivity.

Accordingly, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method and an apparatus for manufacturing a hollow molded article capable of further improving productivity.

[0007]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, a method for manufacturing a hollow molded product according to the present invention is characterized in that the hollow molded product is divided into two parts, an upper divided body and a lower divided body. A method of manufacturing the hollow molded article by joining the lower split body and the upper mold for molding the upper split body and a lower mold for molding the lower split body, A molding step of simultaneously molding the upper divided body and the lower divided body at different angular positions in the abutting surfaces of the upper mold and the lower mold, and after molding the upper divided body and the lower divided body, A mold opening step of opening the mold and the lower mold, and positioning the upper mold and the lower mold relatively to rotate so that the position of the formed upper divided body matches the position of the lower divided body. A step of butting the upper mold and the lower mold again. Cured by supplying molten resin to the abutted portion of the lower split body and the upper split body, it is characterized by comprising a bonding step of bonding the on split body and the lower split body.

Further, in the method for manufacturing a hollow molded product according to the present invention, in the joining step, a molten resin is injected into a butt portion between the upper divided body and the lower divided body to be cured.

In the method for manufacturing a hollow molded product according to the present invention, the resin is a thermoplastic resin.

In the method of manufacturing a hollow molded product according to the present invention, the upper mold is formed such that a cavity for molding the upper split body and the upper mold and the lower mold are relatively rotated and abutted. In this case, in order to form the inner peripheral surface of the upper split body, the lower die has a recess on which the projecting portion enters, on the same circumference.

In the method of manufacturing a hollow molded product according to the present invention, the lower mold is formed such that a cavity for molding the lower split body and the upper mold and the lower mold are relatively rotated and abutted. In this case, a protrusion formed on the upper die and a recess into which the protrusion enters to form an inner peripheral surface of the lower split body are formed on the same circumference.

Further, the apparatus for manufacturing a hollow molded article according to the present invention divides the hollow molded article into two parts, an upper divided body and a lower divided body. An apparatus for manufacturing the hollow molded article by joining a divided body, wherein a first part for molding the upper divided body is provided.
Cavity, a first protruding portion for molding the inner peripheral surface of the lower divided body, and a second projection for molding the upper divided body.
An upper die having a first concave portion for accommodating the projection of the same, a second cavity for molding the lower split body, and an inner peripheral surface of the upper split body. A second protrusion for forming the lower split body, and a first protrusion for forming the lower divided body.
Characterized by comprising a lower mold having a second concave portion for accommodating the protrusion of the lower mold on the same circumference, and rotating means for relatively rotating the upper mold and the lower mold. .

In the apparatus for manufacturing a hollow molded product according to the present invention, the first cavity, the first protrusion, and the first recess of the upper die are arranged at equal angular intervals on the same circumference. It is characterized by being.

In the apparatus for manufacturing a hollow molded product according to the present invention, the second cavity, the second protrusion, and the second recess of the lower die are arranged at equal angular intervals on the same circumference. It is characterized by being.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing one embodiment of a mold for molding a hollow molded article of the present invention, FIG. 2 is a view showing a cavity arrangement of a fixed side mold plate viewed from a parting line of the mold,
FIG. 3 is a view showing the cavity arrangement of the movable mold plate viewed from the parting line of the mold. FIG. 5 is a diagram showing an upper split body and a lower split body which constitute a hollow molded product.

In FIG. 1, the mold for the hollow molded product includes a fixed mold plate 1, a movable mold plate 2, a hot runner manifold 3, hot runner chips 41, 42, 43,
A movable-side rotation guide 5 and a rotation actuator 6 are provided. The number of molds to be taken is two.
The fixed side template 1 has two upper divided bodies 111 (see FIG. 5).
12a and 12b for molding the outer peripheral surface of
And protrusions 13a and 13b for forming the inner peripheral surfaces of the two lower divided bodies 112 (see FIG. 5), and protrusions 22a and 22b for forming the inner peripheral surfaces of the upper divided bodies described later. Concave portions 14a and 14b for escape are provided. The movable mold plate 2 has cavities 23a and 23b for forming the outer peripheral surfaces of the two lower divided bodies, and projecting portions 22a and 22b for forming the inner peripheral surfaces of the two upper divided bodies. When,
Projection 13 for forming the inner peripheral surface of the above-mentioned lower divided body
a, 13b are provided with recesses 24a, 24b.

The hot runner chips 41a and 41b are
The hot runner chips 42a and 42b communicate with the fixed cavities 12a and 12b, respectively, and the hot runner chips 42a and 42b communicate with the movable cavities 23a and 23b, respectively, and each function as a gate of the upper and lower divided bodies. The hot runner chips 43a and 43b have a function as a gate of the molten thermoplastic resin, and the gates are provided in the cavities 12a and 12b.

The hot runner system of this embodiment employs a valve gate. The opening and closing operation of the valve controls the timing of resin injection into the upper and lower divided bodies and resin injection into the welded portion.

Regarding the cavity arrangement, the fixed side is 12
a, 12b, 13a, 13b, 14a, and 14b are disposed at equal intervals of 60 ° on a concentric circle with respect to the center of the template, and the movable side corresponds to the fixed side.
b, 23a, 23b, 24a and 24b are arranged at the same radius as the fixed side and at equal intervals of 60 ° on a concentric circle with respect to the center of the template.

Next, the procedure for manufacturing a hollow molded product manufactured using a mold having such a structure will be described.

First, the above-mentioned mold is mounted on an injection molding machine and the mold is clamped. At this time, the hollow body is 2 in this example.
The upper divided body is formed by the set of 12a and 22a and the set of 12b and 22b, and the lower divided body is formed by the set of 13a and 23a and the set of 13b and 23b. I have. The first step is these 4
This is a step of simultaneously molding the divided bodies.

That is, the heated and melted thermoplastic resin injected from the injection nozzle of the injection molding machine passes through the hot runner manifold 3 from the sprue and passes through the hot chip 41.
a, 41b, 42a, 42b, the cavity 12a and the protruding portion 22a, and the cavity 12b and the protruding portion 22 respectively.
b, cavity 23a and protrusion 13a, cavity 23
b and the space formed by the protrusion 13b, and the upper divided bodies 111a and 111b and the lower divided bodies 112a and 112b
Is molded. At this time, the hot tip 43a of the welded portion,
The valve 43b is closed to prevent the resin from flowing into the welding portion and the resin from flowing back from the shape portion.

Next, the mold is opened. At this time, the upper divided body remains in the cavities 12a and 12b of the fixed mold plate 1, and the lower divided body remains in the cavities 23a and 23b of the movable mold plate 2. After the mold is opened, the motor 6 is driven to rotate the movable mold plate 2 through the gears 32 and 34 by 60 ° about the center of the mold. In order to improve the positioning accuracy of the rotation, the stationary mold plate 1 and the movable mold plate 2 are provided with a positioning pin and a positioning bush, respectively, which are not shown. And the positions of the fixed side and the movable side can be determined more accurately. This rotation is guided by a bearing 5 which is a rotation guide.

After the rotation, when the mold is closed, the movable-side projections 22a and 22b for forming the inner peripheral surface of the upper divided body and the fixed-side projections 13a and 13 for forming the inner peripheral surface of the lower divided body are formed.
Since b protrudes from the parting line, 60 °
After the rotation, the recesses 14a, 14b,
14b, 42a and 42b.

As a third step, the upper divided bodies 111a, 111b and the lower divided bodies 112a, 112b, whose molds are tightened and whose divided surfaces abut each other, are opened through the hot chips 43a, 43b by opening the valve of the hot runner. The divided surfaces are welded by the injected molten resin. At this time, the valves of the hot chips 41a, 41b, 42a, 42b are closed to prevent the resin from flowing into the shape portion. After welding, the mold is opened, the molded product is removed, and the movable mold plate 2 rotates back to the initial position.

As shown in FIG. 5, the molded article of this embodiment has a length of 30 mm × width 40 mm × height 40 m.
m, vertical 40mm x horizontal 50mm, thickness 2
It is a hollow product having a flange of mm. The material is A
BS resin. A dividing surface is set at the center of the flange portion, and the upper part is defined as an upper divided body 111 and the lower part is defined as a lower divided body 112.

Since the present embodiment is an example of taking two pieces, the cavities, the protruding portions, and the concave portions are arranged at an angle of 60 ° with respect to the center of the template, however, the present invention is not limited thereto. The arrangement is not limited. For example, if three pieces are taken, a 40 ° array of nine equal parts is naturally obtained. Of course, it is also possible to arrange in two rows.

As described above, according to the above embodiment, a hollow body made of a thermoplastic resin can be manufactured with high productivity. In this embodiment, the cycle time can be reduced by 15% and the material weight can be reduced by 55%.
Naturally, full automation is also possible.

[0030]

As described above, according to the present invention,
A hollow molded article can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold according to an embodiment of the present invention.

FIG. 2 is a diagram showing a layout on a parting surface of a fixed mold;

FIG. 3 is a diagram showing a layout on a parting surface of a movable mold;

FIG. 4 is a sectional view of a mold before and after rotation of a template.

FIG. 5 is a diagram showing a shape of a molded product and a shape of a divided body.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fixed-side template 2 movable-side template 3 hot runner manifold 41, 42, 43 hot tip 5 movable-side rotation guide 6 rotation actuator 12a, 12b cavity 13a, 13b protrusion 14a, 14b recess 22a, 22b protrusion 23a, 23b Cavities 24a, 24b Depressions 111 Upper split body 112 Lower split body

Claims (8)

[Claims] 1. The hollow molded article is divided by dividing a hollow molded article into two parts, an upper divided body and a lower divided body, forming each divided body, and joining the upper divided body and the lower divided body. A method of manufacturing, wherein an upper mold for molding the upper divided body and a lower mold for molding the lower divided body are abutted with each other, and different angular positions in a mating surface of the upper mold and the lower mold. A molding step of simultaneously molding the upper divided body and the lower divided body, and a mold opening step of opening the upper mold and the lower mold after molding the upper divided body and the lower divided body, A positioning step of relatively rotating the upper mold and the lower mold to match the position of the molded upper divided body with the position of the lower divided body; and butting the upper mold and the lower mold again A butting step, at a butting portion of the upper split body and the lower split body Cured by supplying melt resin, hollow molded article manufacturing method, characterized by comprising a bonding step of bonding the on split body and the lower split body. 2. The method according to claim 1, wherein, in the joining step, a molten resin is injected into a butt portion between the upper divided body and the lower divided body to be cured. 3. The method according to claim 1, wherein the resin is a thermoplastic resin. 4. The inner peripheral surface of the upper split body when the upper mold and the lower mold are rotated relative to each other and the cavity for molding the upper split body is abutted. The method for manufacturing a hollow molded product according to claim 1, further comprising, on the same circumference, a concave portion into which the projecting portion formed on the lower mold enters for molding the hollow mold. 5. The inner surface of the lower mold when the cavity for molding the lower mold and the upper mold and the lower mold relatively rotate and abut against each other. The method for manufacturing a hollow molded product according to claim 1, wherein a protrusion formed on the upper mold has a concave portion into which the protrusion enters to form the same on the same circumference. 6. The hollow molded article is divided by dividing the hollow molded article into two parts, an upper divided body and a lower divided body, forming the respective divided bodies, and joining the upper divided body and the lower divided body. A first cavity for molding the upper divided body, a first protrusion for molding an inner peripheral surface of the lower divided body,
An upper mold having, on the same circumference, a first recess for accommodating a second protrusion for molding the upper split, a second cavity for molding the lower split, A second protrusion for molding an inner peripheral surface of the upper split body;
A lower mold having a second concave portion for accommodating the first protrusion for molding the lower split body on the same circumference; and for relatively rotating the upper mold and the lower mold. An apparatus for producing a hollow molded article, comprising: a rotating means. 7. The method according to claim 6, wherein the first cavity, the first protrusion, and the first recess of the upper die are arranged at equal angular intervals on the same circumference. An apparatus for manufacturing the hollow molded article according to the above. 8. The method according to claim 6, wherein the second cavity, the second projecting portion, and the second concave portion of the lower die are arranged at equal angular intervals on the same circumference. An apparatus for manufacturing the hollow molded article according to the above.