JPH06335956A - Molding of hollow object - Google Patents

Abstract

PURPOSE:To simply mold a hollow object using at least two sheets. CONSTITUTION:At least two sheets 10,11 are inserted in an opened mold and the peripheral edges of the respective sheets 10,11 are fused by claming the mold to obtain a flat hollow object 23 and air is injected into this flat hollow object 23 to mold a hollow object. By this method, the hollow object is simply obtained without using a parison.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a hollow body, and more particularly to a novel improvement for easily obtaining a hollow body by using at least two sheets.

[0002]

2. Description of the Related Art A blow molding method, which is a hollow molding method using a parison, is generally adopted as a conventional method for molding a hollow body of this type, which is disclosed in, for example, JP-A-62-99115. It is disclosed in the official gazette.

[0003]

Since the conventional method for molding a hollow body is configured as described above, the following problems exist. That is, since a cylindrical parison must be formed using an extruder and a crosshead, the device configuration becomes complicated and it is difficult to obtain an inexpensive device. Also, the diameter of the parison must be changed depending on the size of the hollow body, and in order to obtain a large hollow body, a large diameter crosshead must be prepared. It was difficult to mold.

The present invention has been made to solve the above problems, and in particular, provides a method for molding a hollow body by using at least two sheets to easily obtain the hollow body. With the goal.

[0005]

According to the method for molding a hollow body of the present invention, at least two sheets are inserted into an opened mold, and the mold is closed to weld the peripheral edges of the respective sheets. Is a flat hollow body, and air is injected into the flat hollow body to form a hollow body.

More specifically, it is a method of cutting the peripheral edge of the sheet by the first and second protrusions formed on the mold when the mold is closed.

More specifically, it is a method of evacuating the flat hollow body in the mold.

[0008]

In the method for molding a hollow body according to the present invention, at least two extruded sheets or heating sheets obtained by heating pre-extruded sheets are inserted into the opened mold, and the mold is closed. The flat hollow body is obtained by welding and becoming one. Thereafter, by inserting an air nozzle into the flat hollow body in the mold and injecting air, each sheet of the flat hollow body bulges along the inner surface of the mold, and a hollow hollow body is formed. Further, at the time of the above-mentioned molding, by vacuuming one of the sheets by a vacuum means (for example, a vacuum chamber) in the mold, the outer surface thereof can have a surface finish state equivalent to that of injection molding.

[0009]

The preferred embodiments of the method for molding a hollow body according to the present invention will be described in detail below with reference to the drawings. 1 to 4 are for showing a method for molding a hollow body according to the present invention. FIG. 1 is a block diagram showing mold opening, FIG. 2 is a block diagram showing mold closing, and FIG. 3 is a structure showing molding. 4 and 5 are configuration diagrams showing another embodiment of FIG.

A reference numeral 1 in FIG. 1 is a mold composed of a first mold part 2 and a second mold part 3 which are provided so as to be openable and closable. The protrusion 2a and the second protrusion 3a are formed.

First and second steps 2b and 3b are formed on each of the projections 2a and 3a. The first projection 2a is engaged with the second step 3b and the second projection 3a is The protrusions 2a and 3a are configured to engage with the first step portion 2b and have a cutting function by sliding on each other when the mold is closed. The height of the second protrusion 3a is set to be slightly higher than the height of the first protrusion 2a.

Next, a method of molding the hollow body having the above-mentioned structure will be described. First, as shown in FIG. 1, at least a pair of sheets 1 composed of an extruded sheet extruded from an extruder or a heating sheet obtained by heating an ordinary sheet 1
0 and 11 are inserted between the mold parts 2 and 3 which are opened. next,
As shown in FIG. 2, when the mold is closed in the state of FIG. 1, the edges 10a and 11a of the sheets 10 and 11 are cut by the engagement of the protrusions 2a and 3a, and at the same time as the second protrusion 3a. Due to the contact of the first step portion 2b, the peripheral edge 1 of each sheet 10, 11 is
The welded portions 20 are formed by welding 0a and 11a.

In the state of FIG. 2 described above, the cavity 1 of the mold 1
A flat hollow body 2 consisting of a pair of sheets 10 and 11 in A
3 is formed. In the state of FIG. 2, when a thin pipe-shaped air nozzle 21 is driven into the welded portion 20 and air 22 is injected through the air nozzle 21, the flat hollow body 2
3 swells as shown in FIG. 3, and the respective sheets 10 and 11 are molded along the inner surface of the cavity 1A of the mold 1 to form the hollow body 2
3A is molded.

As another embodiment, in the case where a vacuum chamber 25 (vacuum source is omitted), which is a vacuum means, is provided in the first mold part 2 constituting the mold 1, one sheet 10 is The inner surface of the cavity 1A is evacuated, and the outer surface of the sheet 10 is strongly attracted to the inner surface of the cavity 1A. Even if the inner pressure of the vacuum is several kg / cm ² , this outer surface is finished in the same smooth state as the injection molding. Although the pair of sheets 10 and 11 are used in the above-described embodiment, the number of sheets is not limited to one and may be one or more.

[0015]

Since the method for molding a hollow body according to the present invention is constructed as described above, the following effects can be obtained. That is, the hollow body can be easily obtained only by injecting air using at least a pair of sheets. Further, by vacuuming the sheet, the outer surface of the sheet is strongly attracted to the inner surface of the cavity, and the outer surface of the sheet can have a beautiful appearance as in injection molding.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing mold opening in a method for molding a hollow body according to the present invention.

FIG. 2 is a configuration diagram showing the mold closing of FIG.

FIG. 3 is a configuration diagram showing a hollow molding state.

FIG. 4 is a configuration diagram showing another embodiment of FIG.

[Explanation of symbols]

 1 type 2a 1st protrusion 3a 2nd protrusion 10,11 Sheets 10a, 11a Peripheral edge 22 Air 23 Flat hollow body 23A Hollow body

Claims (3)

[Claims] 1. A peripheral edge of each sheet (10, 11) by inserting at least two sheets (10, 11) into the opened mold (1) and closing the mold (1). 10a, 11a) is welded to form a flat hollow body (23), and air (22) is placed in the flat hollow body (23).
A method for molding a hollow body, comprising injecting and molding into a hollow body (23A). 2. A peripheral edge (10a, 11a) of each sheet (10, 11)
The first and second protrusions formed on the mold (1) when the mold is closed.
The method for molding a hollow body according to claim 1, wherein the method is performed by cutting with (2a, 3a). 3. The method for molding a hollow body according to claim 1, wherein the flat hollow body (23) is evacuated in the mold (1).