JPH06294494A - Structure for vacuum insulating wall - Google Patents

Abstract

PURPOSE:To provide the structure of a vacuum insulating wall capable of quickly discharging the internal gas regardless of the heat insulating wall having a complex shape and capable of shortening the evacuation processing time without deforming the heat insulating wall. CONSTITUTION:A mat 2 made of inorganic fibers compressed and hardened by an organic binder is sealed in a heat insulating wall 1A, the organic binder is heated and converted into cracked gas, the interior of the vacuum insulating wall 1A is evacuated, a recessed groove 2A is provided on the surface of the mat 2 made of inorganic fibers, and hollow inorganic fine grains 5 are filled in the recessed groove 2A. The recessed groove 2 filled with the hollow inorganic fine grains 5 serves as an air passage to accelerate the evacuation processing, and the hollow inorganic fine grains 5 prevent the surface of the heat insulating wall 1A from being recessed and deformed by the atmospheric pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum heat insulating wall structure.

[0002]

2. Description of the Related Art Conventionally, as a structure of a heat insulating wall for high-order heat insulation such as a baking furnace for heat treatment, the heat insulating wall composed of inner and outer walls is used as a hermetically sealed space, and an inorganic fiber mat is housed therein and then vacuum exhausted to hermetically seal it. A heat insulating wall is known (for example, Japanese Utility Model Laid-Open No. 62-54396). This kind of heat insulating wall can obtain a high-order heat insulating effect by the synergistic effect of the inside vacuum atmosphere and the heat insulating effect of the densely packed inorganic foamed powder. For example, a wall body having a thickness of about 4 to 5 cm. It is said that it is possible to insulate between room temperature and the temperature difference of 300-400 ℃.

By the way, in the above-mentioned heat insulator, when the mat is sealed in the heat insulating space and the heat insulating wall is evacuated, the heat insulating wall is caused by the unevenness of the filling degree of the fiber mat or the compressive deformability of the fiber mat, which causes the pressure difference between the inside and outside. Then, there is a problem that it may be depressed and deformed. In view of such a problem, an organic binder is contained as an inorganic fiber mat sealed in the heat insulation space, and compressed to a density that can withstand atmospheric pressure against vacuum, so that the heat insulation wall has a thickness almost equal to that of the heat insulation space. The heat-insulating mat that has been compressed and hardened is inserted into the heat-insulating space, and then the heat-insulating wall is gasified by heating in the presence of air to the decomposition temperature of the organic binder, and this gas is sucked and discharged. After that, a method of evacuating the heat insulating space was proposed (for example, Japanese Patent Application No. 3-104735).

[0004]

The above-mentioned method has almost solved the problems such as the concave deformation due to the vacuuming of the heat insulating wall, but when the inside of the heat insulating wall is evacuated, the gasified organic binder is completely removed. There was a problem that it took time to suck. That is,
Removal of gasified organic binder and increase in gas flow resistance during vacuum evacuation make it necessary to strengthen suction time and suction pressure for complete suction, and there is a problem that suction vacuum processing cannot be performed in a short time. . In view of such problems,
Although it has been proposed to form a groove for air circulation in the heat insulating mat (for example, JP-A-3-81695), there is a drawback that the surface of the heat insulating wall along the groove is dented and deformed due to atmospheric pressure. there were.

[0005]

In view of the above problems, the present invention can quickly discharge the gasified organic binder inside even if the heat insulating wall has a complicated shape, and the heat insulating wall is not deformed. The purpose of the structure is to obtain a structure of a vacuum heat insulating wall that can shorten the vacuuming time.

[0006]

That is, the method of vacuumizing a vacuum heat insulating wall according to the present invention encloses a mat made of inorganic fibers obtained by compression curing with an organic binder inside the heat insulating wall,
In the vacuum heat insulating wall formed by heating to decompose and gasify the organic binder and to evacuate the inside of the heat insulating wall, concave grooves are provided on the mat surface made of the inorganic fibers, and hollow inorganic fine particles are filled in the concave grooves. It is characterized by being done.

[0007]

In the present invention, since the concave surface is provided on the surface of the inorganic fiber mat enclosed in the heat insulating wall, it serves as a passage for exhaust gas when evacuating and exhausts when evacuating the heat insulating wall. The gas is smoothly discharged without increasing the flow resistance of the gas and an efficient vacuum is achieved.

Further, since the inorganic fine particles filled in the concave groove have almost no elasticity and do not break at a pressure of about atmospheric pressure, concave deformation due to atmospheric pressure is prevented. Furthermore, even if the inorganic particles are densely packed, there are voids between them and the hollow part of the particles also serves as a passageway for the air, so there is no hindrance to the flow of exhaust air in the groove, and heating at around 400 ° C does not cause any problems. There is no effect. Therefore, heating and exhausting can be achieved smoothly.

[0009]

Embodiments of the present invention will be described below. 1 is a sectional view of an essential part of an embodiment of the present invention, FIG. 2 is a plan view of a heat insulating mat 2, FIGS. 3 and 4 are sectional views showing an inserted state of the heat insulating mat 2, and FIG. 5 is a manufacturing apparatus of the embodiment. FIG.

A heat-insulating container 1 having a width of 1000 mm, a depth of 600 mm, a height of 1700 mm, and a heat-insulating layer thickness of W40 mm is molded, and then the fiber diameter is 5 μm.
Spraying spraying 10 parts by weight of phenolic resin (Braiofen manufactured by Dainippon Ink and Chemicals, Inc.) to 100 parts by weight of glass fiber mat on the thick and thin mats made of rock wool of ~ 8 μm without pressure. And impregnate it with a press machine while heating it at a pressure of ² kg / cm ² to pressurize it to form a groove 2A having a width of 1 cm and a depth of 5 mm as shown in FIG. Thickness 37
A ~ 39 mm compression mat 2 was molded.

Next, a maximum grain size of 1.5 mm is formed in the groove 2A,
Hollow inorganic fine particles 5 having an average particle diameter of 1 mm (Marukoshi Kogyo Co., Ltd .: trade name "Ceramic Cocoon") are filled and the mat is inserted into the heat insulating wall 1A as shown in FIG. 3 or FIG. The opening of the heat insulating wall 1A was closed.

As shown in FIG. 5, the heat insulating container 1 is placed in a heating furnace 3 and the valve 4 is connected to an opening provided in a heat insulating wall 1A to heat the heat insulating container to 300 ° C. and an air suction pump ( Suction was performed by (not shown) and suction was performed. When the time required for the gas of the organic binder inside to reach a sufficiently low concentration range was counted, it was found to be about 35 minutes.

As a comparative example, a heating and vacuuming operation was carried out for the case of using a fiber mat having no groove and the case of using a fiber mat having grooves 2A but having no hollow inorganic fine particles filled therein. When the gas suction time until the same level of gas concentration was measured, the former averaged 1.5
In the latter case, the outer wall of the heat-insulating container has already begun to deform along the groove during vacuum evacuation and the groove is almost completely filled.
It took a minute. Further, the deformation of the heat-insulated container subjected to the vacuum treatment was observed. In the comparative example in which the hollow inorganic fine particles were not filled inside although there was the concave groove 2A, the concave deformation along the concave groove occurred. In the example, no such indentation deformation was observed.

[0014]

As explained above, according to the method of the present invention, since the discharge of the gasified organic binder inside is promoted by the concave groove, the gas suction efficiency is improved, and the gas suction treatment is performed as compared with the conventional method. The time can be remarkably shortened and the production efficiency of the vacuum insulated container can be improved. In addition, sufficient strength can be maintained without denting deformation of the outer wall of the heat insulating container along the groove.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of the present invention.

FIG. 2 is a plan view of a heat insulating mat 2.

FIG. 3 is a cross-sectional view showing an inserted state of a heat insulating mat 2.

FIG. 4 is a cross-sectional view showing an inserted state of the heat insulating mat 2.

FIG. 5 is a cross-sectional view of the manufacturing apparatus according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulation container 1A ... Insulation wall 2 ... Insulation mat compressed and hardened by an organic binder 2A ... Recessed groove 3 ... Heating furnace 4 ... Valve 5 ... Hollow inorganic fine particles

Claims (1)

[Claims] 1. A vacuum heat insulating wall obtained by enclosing a mat made of inorganic fibers formed by compression and hardening with an organic binder inside the heat insulating wall, heating and decomposing and gasifying the organic binder, and vacuumizing the inside of the heat insulating wall. 2. The structure of the vacuum heat insulating wall according to, wherein a concave groove is provided on the surface of the mat made of the inorganic fiber, and hollow inorganic fine particles are filled in the concave groove.