JPH0345698B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a heat insulating door applied to refrigerators and the like.

[Technical Background of the Invention] Conventionally, a heat insulating door for a refrigerator or the like has a structure in which a urethane resin is foamed and filled as a heat insulating material into an outer shell consisting of an outer panel and an inner panel.

[Problems with the Background Art] However, in such a conventional configuration, carbon dioxide gas with high thermal conductivity is trapped in the bubbles of the urethane resin when the urethane resin is foamed and filled.
The insulation performance could not be said to be sufficient. In addition, because the outer panel, inner panel, and foamed urethane resin are required to construct the heat-insulating door, not only does the number of parts increase, but the number of manufacturing and assembly steps for each of these components also increases, which increases costs accordingly. There was a problem.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to improve the heat insulation performance, and to form an outer shell without using an outer panel or an inner panel. It is an object of the present invention to provide a method of manufacturing a heat insulating door that can reduce the number of parts and the associated manufacturing and assembly man-hours, thereby reducing costs.

[Summary of the Invention] In order to achieve the above object, the present invention provides a mold having a cavity having a shape corresponding to the external shape of an insulated door, and contains a powder material that melts when heated to a predetermined temperature or higher in the mold. Alternatively, after carrying out the step of storing the filler made of granules and the step of evacuating the inside of the mold, the contact surface of the filler with the mold is heated and melted, and the melted portion is cooled. When solidified, the surface forms an outer shell to maintain the internal vacuum state.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In Fig. 1, reference numeral 1 denotes a heat insulating door for a refrigerator, for example, and this has protrusions 2, 2 for forming a door pocket, which are oriented vertically and spaced apart from each other at a predetermined distance on both the left and right sides of the back surface. Sashes 3, 3 as door components are provided at both left and right end portions, and a filling material 5, which will be described later, is housed in the outer shell 4 of the sashes 3, 3. Further, the heat insulating door 1 is configured such that the inside of the outer shell 4 is maintained in a vacuum state through the steps described below, thereby exhibiting a sufficient heat insulating effect.

The heat insulating door 1 is manufactured through the steps shown in FIG. 2, and the manufacturing method will be described below.

That is, in the material filling step shown in FIG. 2a, the material melts into the lower mold 6 having a cavity shape corresponding to the shape of the heat insulating door 1 when heated to a predetermined temperature or higher, and when cooled thereafter. A resin powder A made of, for example, a thermoplastic resin, which is a powder or granular material that solidifies, and sashes 3, 3, which are door parts, are stored. Incidentally, in this step, if a slight vibration is applied to the lower die 6, the resin powder A can be housed more densely. In the pressurizing and evacuation process (see FIG. 2b) that follows the material filling process, an upper mold 9 consisting of a fixed upper mold 7 and a movable upper mold 8 is placed on the lower part of the lower mold 6, and the lower mold The sashes 3, 3 in the mold 6 are fixed by a fixed upper mold 7, the resin powder A in the lower mold 6 is pressed and solidified by the movable upper mold 8, and the air in the cavity is removed by a plurality of molds provided in the lower mold 6. Small ventilation hole 6a
(Only two are shown in the figure)
This will evacuate the inside of the cavity. In this case, the efficiency of evacuation can be increased by evacuating the entire space in which the lower mold 6 and the upper mold 9 are housed. Further, 6b in FIG. 2B is a filter provided in the small hole 6a of the lower mold 6.

After this, a heating step and a second
The cooling steps shown in Figure d are performed sequentially. In the above heating step, the lower mold 6 and the upper mold 9 are heated to melt the surface of the resin powder A inside (the contact surface with the lower mold 6 and the upper mold 9), and in the subsequent cooling step, the lower mold is heated. The mold 6 and the upper mold 9 are cooled to solidify the surface of the resin powder A. As a result of these steps, the outer shell 4 is formed by the surface of the resin powder A, that is, the part that is once melted and then solidified, and the unmelted part of the resin powder A is formed as the filler 5. This is how the heat insulating door 1 is formed. In addition, in the heating step, pressure may be continuously applied to the resin powder A inside by the movable upper die 8. After the above cooling step is completed, the mold opening step shown in FIG. 2e is carried out to take out the heat insulating door 1. After this, the outer shell 4 etc. are painted if necessary.

According to this embodiment having such a configuration, the following effects can be obtained. That is, the outer shell 4 of the heat insulating door 1 is formed by melting and solidifying the surface of the resin powder A, which is filled between the lower mold 6 and the upper mold 9 and pressed into a predetermined shape. Since it is not necessary to use an outer plate and a molded inner plate, the number of parts can be reduced, and the number of manufacturing and assembly steps can be reduced. Furthermore, since a vacuum heat insulating layer is formed inside the outer shell 4, the heat insulating performance is improved compared to the conventional foam filling with urethane resin. Furthermore, since the sash 3 is embedded during molding of the heat insulating door 1, the heat insulating door 1 can be obtained as a structural body, and the number of assembly steps can be reduced. still,
In the above embodiment, the heat insulating property is further improved by depositing a metal such as aluminum on the surface of the outer shell 4 as necessary, or by coating the surface of the deposited film with another material. Also good. In addition, the sash 3 is embedded in the heat insulating door 1, but other parts such as the handle fixture, pocket fixture, handle, and door front plate have a higher softening point than the resin powder A and can withstand heat. It may also be embedded.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings; for example, the powder or granular material constituting the filler is not limited to thermoplastic resin, but may include hollow bodies of glass, Other materials such as powder or ceramics may be used, and various modifications may be made without departing from the spirit of the invention.

[Effects of the Invention] As is clear from the above description, the present invention is applicable to the production of an insulating door that improves heat insulation performance by forming a vacuum heat insulating layer inside the outer shell, by using an outer panel and an inner panel. It is possible to form the outer shell portion without any problems, thereby reducing the number of parts and the associated manufacturing and assembly man-hours, thereby achieving an excellent effect of reducing costs.

[Brief explanation of drawings]

Figures 1 and 2 show one embodiment of the present invention. Figure 1 is a perspective view showing a partially cutaway heat-insulating door, and Figure 2 is a cross-sectional view showing the manufacturing process of the heat-insulating door. be. In the drawing, 1 is the insulation door, 4 is the outer shell, 5 is the filling,
6 indicates a lower mold, and 9 indicates an upper mold.

Claims (1)

[Claims] 1. A step of providing a mold having a cavity having a shape corresponding to the external shape of the heat insulating door, and storing a filling made of powder or granules that melts when heated to a predetermined temperature or higher in the mold; a step of evacuating the inside of the mold; and a step of heating and melting the contact surface of the filling with the mold and cooling and solidifying the melted portion to form an outer shell portion on the contact surface. A method of manufacturing an insulated door.