JPH06190882A - Manufacture of inner box of heat insulating box - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing an inner box of heat insulating box capable of manufacturing the inner box with high precision at low cost and in a short time. CONSTITUTION:A melted resin 8 to be injected from an injector 10 is injected by pressing pressure of a press section 7 into a recess 6 formed at one side of a fixed mold 5 arranged apart from the injector 10. While the resin 8 is being injected, the press section 7 is made to proceed into the recess 6 so as to form a predetermined clearance sealed in between the press section 7 and the fixed mold 5. The resin 8 is made to penetrate the clearance so as to form an inner box.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an inner box of a heat insulating box such as a freezer and a refrigerator.

[0002]

2. Description of the Related Art Conventional heat insulation boxes such as freezer and refrigerator are
A heat insulating material is interposed between the outer case and the inner case made of resin. As a method for manufacturing the inner box of this heat-insulating box, for example, as shown in FIG. 5, a resin such as polystyrene is extruded by a sheet extruder 1 and then passed through a plurality of rollers 2 to have a predetermined width, length and The sheet 3 is formed so as to have a thickness, and the sheet 3 is set in a mold, and then the sheet 3 is heated and the inside of the mold is evacuated to bring the sheet 3 into close contact with the mold. A vacuum forming method for forming the box 4 (hereinafter referred to as a VF method) is generally used. And as such a VF method, Japanese Patent Publication No. 3-4
Some are disclosed in Japanese Patent No. 6377.

As another manufacturing method, a molten resin is injected into a gap formed between molds by an injection molding machine, and the resin is forcibly filled in the gap to manufacture an inner box. There is an injection molding method. As such an injection molding method, there is one as disclosed in Japanese Patent Publication No. 4-17779.

On the other hand, in the case of BS antennas, high-performance belts, etc., which require precise flatness, an injection press method in which a molten resin is injected into a mold and then press pressure is applied to the resin to form a product by compression. (Hereinafter referred to as “impress method”).

[0005]

However, in the VF method, which is one of the conventional methods for manufacturing an inner box of such a heat-insulating box, the above-mentioned sheet extrusion and vacuum forming are used for forming the inner box. In addition to the above process, a trimming press process for removing an extra portion such as a flange for chucking from the molded inner box is required, which causes a problem that the time required for molding becomes long.

Polystyrene or the like is used so that the resin used as the material will not melt down from the mold even if it is heated in the vacuum forming process. However, this resin such as polystyrene is expensive. Further, in each of the sheet extrusion step, the vacuum forming step, and the trimming press step, there is a problem in that a material loss occurs such as an extra portion being removed, which results in a high material cost and a high manufacturing cost.

Further, in the VF method, since the mold used is formed by laminating aluminum castings, there is variation in accuracy of the mold itself, and the degree of vacuum and vacuum during vacuum forming. There is a problem that the accuracy of the inner box varies because the degree of adhesion of the resin to the mold is slightly different depending on the molding time and the like.

On the other hand, in the injection molding method which is another manufacturing method, the resin injection pressure of the injection molding machine is high because the gap between the molds is forcibly filled with the resin. Must also have the strength to withstand this high injection pressure, and as a result, the mold itself will become larger and the manufacturing cost will increase, and the initial cost will also increase. It was unsuitable.

Further, in the impress method, the resin is warped, sink marks, and flow marks are generated at the time of molding, so that the application example is limited to the manufacturing of a shallow and small product such as a BS antenna or a high-performance belt. However, there is a problem that it cannot be used for manufacturing a large-sized resin product having a deep bottom such as an inner box of a heat insulating box.

It is an object of the present invention to provide a method for manufacturing an inner box of a heat insulating box which can manufacture an inner box with high accuracy in a short time and at low cost.

[0011]

SUMMARY OF THE INVENTION According to the present invention, in a heat insulating box body formed by interposing a heat insulating material between an outer box and an inner box made of resin, a fixing member having a recess formed on one side thereof is used. The mold includes a die, a press part that enters a recess of the fixed die to form a predetermined gap between the die and the fixed die, and an injector that pours a molten resin into the recess, and is sealed from the injector. While the molten resin is being poured into the recess which is not formed, the press portion is allowed to enter the recess to form a predetermined sealed gap between the press portion and the fixed mold, and the molten resin is poured into the recess. The formed resin is permeated into the gap to form the inner box.

[0012]

With this structure, the molten resin injected from the injector can be poured into the concave portion formed on one side of the fixed mold located at a position farther than the injector by the pressing pressure of the pressing portion. Furthermore, by injecting the resin into the recess while pouring the resin,
A predetermined gap that is hermetically sealed is formed between the press section and the fixed mold, and the resin is permeated into this gap to form the inner box. Therefore, the injection pressure can be reduced and the mold can be downsized.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an inner box molding apparatus for molding an inner box by a method for manufacturing an inner box of a heat insulating box according to an embodiment of the present invention.

In the figure, 5 is a fixed mold having a recess 6 formed on one side thereof, and 7 is a press unit driven by a drive unit (not shown) to move the fixed mold 5 into and out of the recess 6. It is a hydraulic press.

Here, the hydraulic press 7 enters into the concave portion 6 while pressing the resin 8 poured into the concave portion 6 of the fixed mold 5 by the injector 10 described later against the back wall of the concave portion 6, and the inside of the concave portion 6 is pushed. This is for forming a sealed gap having a predetermined width (hereinafter referred to as a molding gap) between the fixed mold 5 and the hydraulic press 7 which corresponds to the shape of the inner box to be molded.

A guide groove 9a is formed in each of the upper and lower edges of the recess 6 of the fixed mold 5, and a stopper 9 is held in the guide groove 9a so as to be slidable in the lateral direction. Here, in this stopper 9, the hydraulic press 7 is recessed 6
When it comes into contact with the hydraulic press 7, it slides inwardly of the guide groove 9a while contacting the hydraulic press 7 and eventually contacts the inner wall of the guide groove 9a to stop the hydraulic press 7 at the position where the forming gap is formed, and the gap is formed. It is for hermetically sealing. Also,
The stopper 9 also serves as a sealing member that prevents the resin 8 from leaking out from the molding gap.

On the other hand, 10 is an injector attached to the fixed mold 5. The injector 10 injects the molten resin 8 so that the resin 8 faces the recess 6 at a position distant from the injector 10. It is for gradually pouring from the formed resin injection port 5a into the recess 6.

The amount of the resin 8 injected by the injector 10 at one time is the amount necessary to form one inner box, and as a result, an excessive amount of the resin 8 is formed in the molding gap. Is not filled, and no internal stress is generated in the molded inner box.

Here, the injection of the resin 8 from the injector 10 is carried out in accordance with a molding command from a control device (not shown). In response to this molding command, the hydraulic press 7 also enters the fixed mold 5. The resin 8 gradually poured from the resin injection port 5a into the recess 6 by the hydraulic press 7 is pressed against the back wall of the recess 6.

At this time, since the resin 8 is poured into the recess 6 from the resin injection port 5a when the recess 6 is not in a sealed state, the tightening pressure applied to the hydraulic press 7 and the fixed mold 5 is poured in the sealed state. It is not so large compared to the case where
The size is about 1/4.

Therefore, the strength of the hydraulic press 7 and the fixed mold 5 is not so large, and the material is made of a material such as aluminum which is relatively soft and easy to process, and can be formed in a small size. Has become.

When the hydraulic press 7 further enters the recess 6, the resin 8 is pressed by the pressing pressure of the hydraulic press 7.
Is sandwiched between the hydraulic press 7 and the back wall of the concave portion 6 and gradually spreads in the vertical direction, and eventually the hydraulic press 7 reaches the forming gap forming position to form a closed forming gap, and FIG. As shown in, the resin 8 penetrates into the molding gap,
Thereby, the inner box having a desired shape is formed.

After forming the inner box in this way, the hydraulic press 7 is withdrawn from the recess 6, and then the inner box stuck to the hydraulic press 7 is removed.

Next, the manufacturing of the inner box by the inner box forming apparatus thus constructed will be described. First, when a molding command is issued from the control device, the resin 8 melted by the injector 10 is gradually poured into the recess 6 from the resin injection port 5a as shown by arrow A in FIG.
As shown in (3), the resin 8 starts to enter the recess 6 and starts to press the resin 8 against the back wall of the recess 6.

In this state, since the concave portion 6 is not hermetically sealed, the hydraulic press 7 and the fixed mold 5 do not have to receive much filling pressure of the resin 8 injected from the injector 10.

The hydraulic press 7 has a stopper 9
While further sliding inward of the guide groove 9a, the resin 8 further enters the concave portion 6, and accordingly, the resin 8 is sandwiched between the hydraulic press 7 and the back wall of the concave portion 6 and gradually spreads in the vertical direction.

Eventually, as shown in FIG. 3, the stopper 9 comes into contact with the inner wall of the guide groove 9a, the hydraulic press 7 reaches the forming gap forming position and stops, and the inside of the recess 6 is sealed by the stopper 9. The amount of resin required to mold one inner box that has been sealed and injected from the injector 10 penetrates into the molding gap, and the inner box is molded.

By the way, after the inner box is formed in this manner, the hydraulic press 7 is withdrawn from the recess 6 as shown by the arrow in FIG. 4, and then the inner box 4 is removed from the hydraulic press 7.
Be prepared for the next molding command. The protrusion 4a extending rearward from the rear wall of the inner box 4 is removed after the inner box 4 is removed.

As described above, the resin 8 is filled in the hermetically sealed recess 6 by allowing the hydraulic press 7 to enter the recess 6 while pouring a fixed amount of the resin 8 into the recess 6 of the fixed mold 5. It is possible to mold the inner box without applying so much pressure to the fixed mold 5 and the hydraulic press 7 as compared with the above-mentioned one.

As a result, the fixed die 5 and the hydraulic press 7 are
Can be made of aluminum and can be miniaturized so that the initial cost can be reduced.

In addition, by injecting the hydraulic press 7 while pouring the resin 8 in this way to form the inner box,
The inner box 4 can be molded without causing warpage, deformation, flow marks, or the like.

Furthermore, the resin used may be inexpensive such as polyethylene, and the manufacturing cost of the inner box itself can be reduced.

[0034]

As described above, according to the present invention, a large amount of resin is poured into the fixed mold while the press portion is allowed to enter the fixed mold, so that a large pressure is applied as compared with the injection molding method. It is possible to form a deep-bottom inner box without applying it to the press section, and it is possible to manufacture a highly accurate inner box in a short time.

Further, the fixed die and the press portion can be made of aluminum or the like and can be miniaturized, and the initial cost can be reduced. Further, since the inner box can be formed of an inexpensive material, it is possible to manufacture the low cost inner box.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an inner box molding device for molding an inner box by a method for manufacturing an inner box of a heat insulating box according to an embodiment of the present invention.

FIG. 2 is a view showing a state where a hydraulic press of the inner box molding apparatus enters into a fixed mold.

FIG. 3 is a diagram showing a state where the hydraulic press has reached a forming gap forming position.

FIG. 4 is a view showing a state in which the hydraulic press is retracted from the fixed mold.

FIG. 5 is a diagram showing a process of forming an inner box by a conventional vacuum forming method.

[Explanation of symbols]

 5 Fixed mold 6 Recessed portion 7 Hydraulic press 8 Resin 10 Injector

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Claims (1)

[Claims] 1. A heat insulation box body formed by interposing a heat insulating material between an outer box and an inner box made of resin, and a fixed mold having a recess on one side thereof, and this fixed mold. A press part that enters into the concave part of the mold to form a predetermined gap between the fixed mold and an injector for injecting the melted resin into the concave part, and melts from the injector into the unsealed concave part. While the resin is being poured, the press section is allowed to enter the concave section to form a predetermined sealed gap between the press section and the fixed mold, and the resin poured into the concave section is permeated into the gap. A method of manufacturing an inner box of a heat-insulating box body, characterized by forming the inner box.