JP2003065490A - Method of manufacturing heat insulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a vacuum heat insulator capable of discharging the air in low vacuum, and remarkably reducing a manufacturing time. SOLUTION: In this method of manufacturing the vacuum heat insulator by mounting a spacer 4 in an internal space 3 formed between metallic plate members 2 opposite to each other, by sealing the internal space 3 after discharging the air, and by deforming the same into the desired shape, a getter 5 is mounted in the internal space 3, the air is discharged from the internal space 3 in low vacuum from 1 Pa (0.75×10<-2> Torr) to 1×10<2> Pa (about 0.75 Torr), then the internal space is sealed, and the getter 5 is after-heated and activated to apply high vacuum.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a vacuum heat insulator.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a vacuum heat insulator, for example, in Japanese Patent Publication No. 2-55153, a structure is placed in a vacuum heating furnace and heating temperatures are 580 to 600 ° C. and 10 ^−2.
To 10 ⁻³ Pa (10 ⁻⁴ to 10 ⁻⁵ Torr) for about 1 hour, and then, three exhaust holes having a diameter of 0.5 mm are sealed with an electron beam welding machine. . Further, in Japanese Patent Application Laid-Open No. 7-298991, a structure is placed in a vacuum heating furnace and a heating temperature of 450 ° C. and 1 Pa.
After vacuum heating and exhausting at a vacuum degree of (10 ⁻² Torr) or less, a method of melting the brazing material arranged in the vicinity of the exhaust hole with laser light and closing the exhaust hole (area 0.7 to 7.0 mm ² ) is used. It is disclosed.

[0003]

However, in the conventional method for manufacturing a vacuum heat insulator, 1 Pa (10 ^-2 Torr) is used.
r) A high-vacuum diffusion pump is required because the vacuum is evacuated to a high vacuum of r) or less. For this reason, the equipment becomes bulky, and piping equipment for cooling the pump with water is also required. In addition, it takes several tens of minutes to heat the oil in the diffusion pump to enable it to operate, and the heating or exhaust process is started after the furnace or the internal space of the structure reaches a high vacuum level. It takes tens of minutes. Further, it takes about 1 hour to maintain a high degree of vacuum even in the heating and exhausting process. As a result, it took about 2 hours from the installation of the structure to the removal.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a method for manufacturing a vacuum heat insulator which can be evacuated at a low vacuum and which can significantly reduce the manufacturing time. .

[0005]

In order to solve the above-mentioned problems, according to the present invention, a spacer is arranged in an internal space formed between opposed metal plate-like bodies to exhaust the internal space. In the method of manufacturing a vacuum heat insulator, which is deformed into a desired shape after being sealed with a getter, a getter is provided in the internal space, and the internal space is changed from 1 Pa (0.75 × 10 ⁻² Torr) to 1 × 10 ^2. After evacuating and sealing at a low vacuum degree of Pa (about 0.75 Torr), the getter is post-heated and activated to obtain a high vacuum degree.

According to the present invention, since the gas is exhausted at a low vacuum,
Since the exhaust speed of gas molecules is high and the temperature rise speed of the structure is also high, as a result of degassing from the constituent members and exhaust of the closed internal space, the exhaust time is shortened.

For exhausting the internal space, not a high vacuum pump such as a diffusion pump but a vacuum roughing pump conventionally used as an auxiliary pump, specifically, only a rotary pump is used, or a rotary pump is used. It is preferable to use both the mechanical booster pump and the mechanical booster pump because the exhaust can be instantly started.

The exhaust part for exhausting the internal space is
By cutting off after sealing, it does not interfere with the subsequent molding process.

It is preferable to perform a leak test of the internal space before sealing the internal space, and perform sealing when it is confirmed that there is no leak in the internal space. In this way, the process is simplified by performing the leak test and the sealing in a series of processes.

If the internal space is sealed by seam-welding the opposing metal plate-like members, the sealing work becomes very simple.

For exhausting and sealing the internal space, the opposing metal plate-shaped bodies may be installed in a vacuum furnace and seam welding of the peripheral edge portion may be performed.

The internal space is sealed from room temperature to about 250 ° C.
The post-heating of the getter is from 250 ° C to 600 ° C.
It is preferable to carry out.

As the getter, it is preferable to use a titanium foil or a zirconium foil.

When the getter is brought into contact with the inner surfaces of the facing metallic plate-like members, the heat of the metallic plate state, which is heated by post-heating, can be transmitted to the getter, and the getter is sufficiently activated. be able to.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a method for manufacturing a vacuum heat insulator according to the present invention. Reference numeral 1 denotes a structure before it becomes a vacuum heat insulating body, and the structure 1 is, as shown in FIG.
A spacer 4 having substantially the same shape as that of the internal space 3 is provided in the internal space 3 having a substantially flat plate shape, and a getter 5 is provided in the internal space 3.

The metal thin plate 2 of the structure 1 is formed by stacking two rectangular plates 2a and 2b as shown in FIG.
It is formed by folding one rectangular plate 2c into two as shown in FIG. The metal thin plate 2 has a thickness of 0.05 m
It is possible to use stainless steel, iron, titanium or the like having a thickness of m to 0.5 mm. After the spacer 4 and the getter 5 are arranged on the outer edge of the metal thin plate 2, pressure bonding such as seam welding or TIG is performed.
It is joined by butt welding such as welding or MIG brazing. As shown in FIG. 4, one rectangular plate 2c
The one that is folded in two requires a small joining area. On one side of the thin metal plate 2, an exhaust portion 6 formed of a rectangular protruding piece is formed, and an exhaust port 7 is formed in the exhaust portion 6. The exhaust port 7 may be formed only by forming an opening in the thin metal plate 2, or may be joined with a tip tube.

As the spacer 4, woven or non-woven fabric such as glass fiber, ceramic fiber, carbon fiber, or mica can be used. Those having a thickness of 0.1 to 15 mm in the uncompressed state are preferred. However, in order to increase the degree of vacuum in the internal space 3, it is preferable to use a nonwoven fabric. Further, for example, a ceramic material that is not damaged by the heating temperature during post-heating (for example, 450 ° C.) may be used. The spacer 4 may be formed by stacking a plurality of thin ones.

The titanium foil as the getter 5 is used to absorb gas or the like generated in the internal space 3 and maintain a desired degree of vacuum after the structure 1 is exhausted and sealed. The titanium foil preferably has a thickness of 0.01 to 0.03 mm. Thickness of 0.02 to 0.03m instead of titanium foil
m zirconium foil may also be used.

Next, a method of manufacturing a vacuum heat insulating body from the structure 1 will be described.

First, as shown in FIG. 2, the exhaust pipe 11 is pressed against the exhaust port 7 of the structure 1 through the seal member 12,
A rotary pump 9 is connected to the exhaust pipe 11 via a pipe 8 as shown in FIG. 1, and a leak test device 10 is connected to the pipe 8. If the rotary pump 9 and a mechanical booster pump (not shown) are used together instead of using the rotary pump 9 alone, the exhaust can be instantly started.

Then, the rotary pump 9 is driven to move the internal space 3 of the structure 1 to 1 Pa (0.75 × 1).
0 ⁻² Torr to 1 × 10 ² Pa (about 0.75 To
Evacuate at a low vacuum degree of rr). At this time, the presence of the spacer 4 reliably prevents the contact between the facing surfaces of the metal thin plate 2. This exhaust step can be performed at room temperature,
If necessary, the heating may be performed at a temperature of about 250 ° C. or lower.

When it is confirmed by the leak test device 10 that there is no leak in the internal space 3 of the structure 1 while maintaining the low degree of vacuum, the root of the exhaust portion 6 of the metal thin plate 2 is removed. 2 in FIG. 2 by seam welding the S portion in FIG.
Joined as shown by the dotted chain line, this joined portion is S- in FIG.
Cut at the position indicated by the S line.

Subsequently, a large number of the structures 1 are manufactured, and the structures 1 are collectively housed in a heating furnace (not shown), and the structures 1 are heated from 250 ° C. to 600 ° C. As a result, the getter 5 inside the structure 1 is activated, and the occluded gas on the metal surface of the structure 1 is sufficiently released. As a result, the occlusion gas released in the internal space 3 of the structure 1 is absorbed by the getter 5 together with the residual air. As a result, the internal space 3 of the structure 1 is 3 × 10 ⁻³ Pa (about 2.25 Pa).
3 × 10 ⁻⁴ Pa (about 2.2) from × 10 ⁻⁵ Torr).
A high vacuum degree of 5 × 10 ⁻⁶ Torr) is reached and a vacuum heat insulator is obtained.

FIG. 5 shows changes in pressure and temperature in the internal space in the above-described method for manufacturing a vacuum heat insulator. As the internal space 3 of the structure 1 is exhausted, the pressure in the internal space 3 drops from 1 atm to 1 Pa (0.75 × 10 ⁻³ Torr), and after performing a leak test at the point T,
At the point S, the exhaust part 6 is sealed and cut by seam welding.
At this time, even after the internal space 3 of the structure 1 is sealed, the stored gas continues to be released from the surface of the metal thin plate 2, so that the pressure in the internal space 3 increases. Next, when the structure 1 is heated to 450 ° C. in the heating furnace, the stored gas is sufficiently released and released from the surface of the metal thin plate 2, so that the pressure in the internal space 3 further increases. At the same time, the getter 5 is activated, so that the liberated occlusion gas is removed along with the residual air.
Is absorbed by. As a result, the pressure in the internal space 3 of the structure 1 gradually decreases, and becomes 3 × 10 ⁻³ Pa (about 2.25 × 1).
0 ^-5 Torr) reaches a desired high vacuum degree.

The vacuum heat insulator thus obtained can be formed into a desired shape. For example, the body and lid of electric pots, rice cookers, lunch jars, the back of the hood of vehicles, the inside of vending machines, the inside of safes, the wall of houses, the body of electric water heaters, etc. Can be processed into a desired shape according to various places that require. As shown in FIG. 6, a cylinder (a), a square tube (b), or a box shape (f) is formed by bending or the like, or a hemispherical shape (e), a cylinder shape (c), or a square ( It may be a bottomed cylinder such as d).

The inventors conducted a heat insulation performance test on the vacuum heat insulator obtained as described above. In this heat insulation performance test, in an atmosphere of 20 ° C., the temperature at the center of the upper surface of the vacuum heat insulator was measured while steam at 100 ° C. was applied to the center of the lower surface. As a result, as shown in FIG. 7, it was found that the vacuum heat insulator manufactured according to the present invention exhibited remarkably excellent heat retention property as compared with the vacuum heat insulator which was not evacuated, and was sufficiently practical. . It was also found that when the thickness is 3.1 mm, the heat insulating performance is not so different from that having a thickness of more than 3.1 mm. Further, if the thickness is 2 mm or less, for example 0.8 mm, the heat insulation performance is slightly inferior to that of 3.1 mm, but it is easy to process and should be arranged with a margin even in a narrow area. Was possible. Furthermore, when a so-called aging test was conducted in which the sample was left to stand in an atmosphere of 95 ° C. for 6 days, heat insulation performance was maintained, and there was no problem even when used in a high temperature environment such as an electric pot. I found out.

In the above embodiment, the structure 1 was formed in advance and the rotary pump 9 evacuated and sealed, but the internal space is evacuated and sealed by the opposing metal thin plate 2. The spacer 4 and the getter 5 are installed in the vacuum furnace and the space between them is set to 1 Pa (0.75 × 10
^-2 Torr to 1 × 10 ² Pa (about 0.75 Torr)
After evacuation to the low vacuum degree of r), the peripheral edge of the structure 1 may be sealed by seam welding.

[0029]

As is apparent from the above description, the present invention
According to, 1 Pa (0.75 × 10 ^-2From Torr)
1 x 10^TwoExhausted at a low vacuum of Pa (about 0.75 Torr)
The high vacuum port such as a diffusion pump.
There is no need to use a pump, which greatly simplifies the equipment.
It Also, use a vacuum vacuum pump to heat at low vacuum.
Since it can be exhausted, the exhaust can be started up instantly and
The molecular exhaust speed is fast, and the temperature rise speed of the structure is also fast.
Therefore, degassing from the components and
As a result of the promotion of exhaust, the exhaust time is significantly shortened.

[Brief description of drawings]

FIG. 1 is a schematic view showing a method for manufacturing a vacuum heat insulator according to the present invention.

FIG. 2 is a cross-sectional view of the structure of FIG. 1 taken along the line II.

FIG. 3 is an exploded perspective view of a structure of an example in which rectangular plates are stacked and assembled.

FIG. 4 is an exploded perspective view of a structure of another example in which a rectangular plate is folded in two and assembled.

FIG. 5 is a diagram showing changes in pressure and temperature in the internal space of the structure during manufacturing of the vacuum heat insulator according to the present invention.

FIG. 6 is a perspective view showing a processing example of a vacuum heat insulator.

FIG. 7 is a graph showing the results of a heat insulating performance test of the vacuum heat insulator manufactured according to the present invention.

[Explanation of symbols]

1 structure 2 Metal thin plate 3 internal space 4 spacers 5 getters 6 exhaust 7 exhaust port 8 piping 9 Rotary pump 10 Leak test equipment

Claims (9)

[Claims] 1. Manufacturing of a vacuum heat insulator in which a spacer is disposed in an internal space formed between opposed metal plate-like bodies, the internal space is evacuated and sealed, and then deformed into a desired shape. In the method, a getter is disposed in the internal space, and the internal space is evacuated and sealed at a low vacuum degree of 1 Pa (0.75 × 10 ⁻² Torr) to 1 × 10 ² Pa (about 0.75 Torr). After stopping, a high degree of vacuum is obtained by post-heating and activating the getter to obtain a high degree of vacuum insulation. 2. The method according to claim 1, wherein the exhaust of the internal space is performed by using only a rotary pump or by using a rotary pump and a mechanical booster pump together. 3. The method according to claim 1, wherein the exhaust part for exhausting the internal space is cut off after sealing. 4. The leak test of the internal space is performed before the internal space is sealed, and the sealing is performed when it is confirmed that there is no leak in the internal space. The method according to any one of 1 to 3. 5. The method according to claim 1, wherein the sealing of the internal space is performed by seam welding the facing metal plate-like bodies. 6. The exhaust and sealing of the internal space is performed by installing the facing metal plate-like bodies in a vacuum furnace and seam welding the peripheral edge portion. Method. 7. The internal space is sealed from room temperature to about 250.
The getter is post-heated from 250 ° C to 600 ° C.
The method according to any one of claims 1 to 6, wherein the method is performed at a temperature of ° C. 8. The method according to claim 1, wherein a titanium foil or a zirconium foil is used as the getter. 9. The method according to claim 1, wherein the getters are brought into contact with the inner surfaces of the facing metallic plate-shaped bodies.