JPH113727A - Sealing device for sodium-sulfur battery in reduced pressure and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To welding seal without passing through shielding gas by moving an assembled vessel and lid, containing an active materail such as sodium sulfur into a vacuum vessel, and substituting an inert gas, argon gas, for the inside of the vacuum vessel to a predetermined reduced pressure after evacuating the vacuum vessel and the vessel in order to welding seal the same at a predetermined reduced pressure. SOLUTION: A vessel 1, formed by inserting assembling a vessel and a lid, is moved into a vacuum vessel 4, the inside of the vacuum vessel 4 is evacuated to 1.3×1<1> Pa or higher. Thereafter, in a state in which a vacuum valve 20 is closed and sealed, an argon gas valve 22 is opened so as to substitute to a predetermined reduced pressure. After the substitution, the argon valve 22 is closed, an arc is generated from an electrode 3 without shielding the gas flow, the vessel 1 is rotated at a proper rotational speed so as to welding seal the whose periphery of a vessel 1 jointing portion. Thereby, reliable welding seal can be attained at low cost, without incurring high cost, or requiring high degree vacuum device and welding machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for sealing the inside of a container to a vacuum, and particularly when an active material such as sodium or sulfur is sealed in the container, the device reacts with oxygen in the air to temporarily seal the inside of the container. The present invention relates to an inexpensive tungsten electrode argon gas welding and sealing apparatus suitable for evacuating, substituting a predetermined degree of vacuum with an inert gas, and sealing under reduced pressure without variation.

[0002]

2. Description of the Related Art A conventional sealing method and apparatus are disclosed in
As described in No. 35125, the container 12 for sealing shown in FIG. 6 is assembled to some extent in advance, welded, the container having the small holes 14 for deaeration for sealing is put in a vacuum container, and the container is evacuated to a predetermined pressure. The pressure is used to perform fusing and sealing with a beam for an extremely short time in a degree of vacuum required for a heat source or various gas atmospheres.

[0003]

According to the above prior art, it is necessary to pre-process the pores for degassing in the sealing container, and to perform the arc-sealing of the pores for degassing with an arc in various gas atmospheres. No consideration has been given to the arc generation method. A) Instability of arc generation and reduction in reliability due to formation of an oxide film during arc welding. B) High processing cost due to the need for degassing pores in the container. C ) There was a problem that a man-hour for welding parts having pores for degassing to the container in advance was necessary.

That is, in the known example of FIG. 5, a lid 13 having pores 14 for deaeration is welded to a container 12 in advance, then moved into a vacuum container, evacuated, and then suitable for an arc or plasma beam or electron beam source. The heat source 7 is activated in an atmosphere, that is, a high vacuum or an appropriate gas atmosphere, and the deaeration pores 14 are welded and sealed.

However, in this method: a) When an arc is generated only in an arbitrary gas atmosphere, the arc is not stable, the arc is intermittent, or the arc concentration is poor, the reliability of the welded portion is poor, and oxygen in the air remains. There was a possibility that an oxide film was formed on the welded portion and a melting defect was generated.

B) The lid 13 having the pores 14 for deaeration is welded in advance, moved into a vacuum vessel, and the pores 14 for the deaeration are welded in a vacuum or various gas atmospheres. Two welding steps are required and the cost is high.
In addition, the processing cost of the lid 13 is high because the pores 14 for deaeration are processed.

C) The heat source 7 is an arc electrode such as a tungsten torch or a plasma beam source or an electron beam source, and the arc electrode such as a tungsten torch cannot obtain stable arc generation due to the electrode material and the shape of the electrode tip.

There was a fear that

[0009]

The stabilization of arc generation is as follows.
The initial vacuum degree of the vacuum vessel is set to 1.3 × 10 ¹ Pa or more, and 99.99% of argon gas is replaced and sealed at a predetermined pressure, so that an oxide film is not formed at the time of welding by tungsten electrode argon gas welding. A stable arc can be continuously obtained, and the material of the electrode is a lanthanum-containing electrode whose electron emissivity is larger than that of thorium and yttrium-containing tungsten electrodes. By forming the arc, continuous stability of the arc is achieved, and furthermore, the distance between the electrode and the welded portion is selected in the range of 0.5 mm to 3.0 mm to achieve the stabilization of the arc generation.

[0010] In order to make the entire circumference of the cylindrical metal container continuous by stabilizing the arc generation, cooling water is flowed at a flow rate of 1 liter / min to the electrode torch portion and the receiving portion of the cylindrical metal container. Prevents overheating of the cylinder and welds the fitting of the cylindrical metal container and the lid continuously over the entire circumference. By eliminating the need for a two-step process of welding and sealing, and eliminating the need for processing the pores for degassing, the processing cost of parts can be reduced.

The opening / closing door of the vacuum container can select and use a highly reliable and reliable sealing mechanism according to the required degree of vacuum. Therefore, each time the container to be sealed is exchanged, the ultimate vacuum degree in the container and the container after vacuum sealing are changed. The degree of internal vacuum does not vary. Since the container and the lid are inserted and assembled and the lid is provided with a gas vent, the degree of vacuum according to the degree of vacuum of the vacuum container is obtained by the insertion assembly gap and the gas vent groove, so assembly can be easily performed outside the vacuum container .

The ultimate degree of vacuum of this vacuum container is 1.3 × 10 ¹
By setting the pressure to Pa or more, it is possible to prevent an oxide film from being formed at the time of welding due to oxygen remaining in air in an atmosphere in which the inside of the vacuum vessel is replaced with argon gas at a predetermined pressure, thereby obtaining an atmosphere suitable for tungsten electrode argon gas welding. The tungsten electrode uses a lanthanum-containing electrode as a material to ensure arc generation, and the tip angle is set at an acute angle of 10 to ensure that the arc is generated from the electrode tip and that the arc length is long and the arc is suitable for welding. Select within the range of degrees to 30 degrees. If the tip angle is less than 30 degrees, the arc is generated not from the arc generation distribution from the electrode tip but from the entire electrode, so that it has poor stability and is not suitable for a welding arc.

If the distance between the electrode and the weld is smaller than 0.5 mm, there is a high possibility that the molten metal in contact with the weld will come into contact with the electrode and the arc will be interrupted. When the welding current is increased because the metal of the part does not melt, a phenomenon occurs in which the electrode melts and the electrode is not suitable for continuous welding, so the distance between the electrode and the welded part is 0.5 mm to 3.0 mm.
And continuous welding was made possible. When continuous welding is performed, the temperature of the electrode, the electrode torch and the weld is overheated, the welding conditions are changed, the reliability is poor, and the ceramic holder of the electrode torch may be damaged. Flow at a flow rate to prevent overheating. The cooling water is in a desirable state if the temperature is controlled in a thermostat. The interior of the vacuum vessel is repeatedly evacuated, sealed, replaced with argon gas, welded, replaced with atmospheric pressure, and removed and replaced with a welded product every time welding is performed, so there is no change in welding selection conditions due to the effect of welding fume generated during welding. Since the effect of heat generation is less than 3 minutes in a vacuum vessel capacity of 100 liters and the temperature rise of the atmosphere is also about 1 ° C, the change in pressure rise in the cylindrical metal vessel is highly reliable within a range that can be controlled. Made it possible.

[0014]

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

A container 1 to be vacuum-sealed and a lid 2 having a maximum insertion gap of 0.2 mm are previously inserted and assembled into a vacuum container 4.
From the airtight door 18 into the vacuum vessel 4.
Thereafter, the rotation drive unit 21 and the receiving unit 23 are set so that the gap between the tungsten electrode 3 and the container 1 at the welding portion is set to 0.5 mm to 3.0 mm. The vacuum pump 17 evacuates the vacuum vessel 4 to 1.3 × 10 ¹
The vacuum system valve 20 is closed, and argon gas, which is an inert gas, is supplied to the argon gas system valve 22.
Is opened to replace the inside of the vacuum container 4 to a predetermined reduced pressure value of 4 × 10 ³ Pa or more, and the rotation drive unit 21 is closed. In order to measure this pressure, a capacitance manometer (GM-1) is used for measuring the initial vacuum degree to the vacuum degree after replacing the argon gas.
The measurement is managed using a vacuum gauge 6 (manufactured by ULVAC of type 000).

As a result, the inside of the vessel 1 has the same pressure as that of the vacuum vessel 4, and when an arc is generated from the tungsten electrode 3 and the welded portion starts to melt, the rotary drive section 21 is rotated by the motor 15 so that the welded portion of the vessel 1 is welded. The entire circumference is welded and sealed.

As for the ultimate vacuum before replacing the gas to a predetermined pressure with argon gas, the higher the degree of vacuum, the smaller the amount of oxygen remaining in the air and the less the formation of an oxide film generated during welding. However, as shown in FIG. 1.3 for gas welding
If it is × 10 ¹ Pa or more, stable and stable arc generation is obtained, and the oxide film of the welded portion does not affect the melting reliability.

Further, the higher the ultimate vacuum degree, the higher the reliability of welding, but the time required for vacuum evacuation is required. Therefore, in this embodiment, 1.3.times.10.sup. ^The equipment cost is suppressed to ¹ Pa or more.

FIG. 2 shows an assembled state of the container 1 and the lid 2.
The lid 2 is made of SUS by plastic working, and the gas vent groove 2a is simultaneously processed by plastic working in the assembly fitting portion, so that the cost of parts production is reduced, and the gas vent groove 2a reduces the inert gas to a predetermined reduced pressure value. The replacement time is minimized to ensure the reliability of the sealing pressure value in the container 1.

The tungsten electrode 3 is selected within a range of 2.8 mm to 4.5 mm in diameter in consideration of arc generation even in a reduced pressure atmosphere. In this embodiment, a diameter of 3.2 mm is used,
The electrode 3 is formed in a pencil shape and the tip angle is selected within a range of 10 to 30 degrees, and the material is tungsten or lanthanum (La).
(Electrode holding ratio of 1.7% to 2.2%) is used to achieve stabilization and continuity of the arc. Welding machine 19
Is a Hitachi inverter TIG welding machine DT-NP-300
A was used.

As for the electrode materials, four types of commercially available products were evaluated for arc generation, and the results are shown in Table 1.

[0022]

[Table 1]

Under the conditions of an electrode diameter of 3.2 mm, a tip angle of 15 degrees, an atmospheric pressure of 4 × 10 ³ Pa, a distance between the electrode and a welding portion of 1.0 mm, and a welding current of 50 A to 180 A, the thorium-containing tungsten electrode has a current set value. Irrespective of this, arc discharge occurs from the whole electrode and is not suitable for welding. Also, with the yttrium-containing tungsten electrode, when the welding current was 90 A or less, an arc discharge from the entire electrode could generate an arc continuously concentrated from the electrode tip at a current value exceeding 90 A. With the lanthanum-containing tungsten electrode, continuous concentrated arc generation from the electrode tip could be obtained at all current set values. The diameter of the electrode is limited in commercially available products, so that it is partially manufactured by polishing and evaluated with an electrode diameter of 1.0 mm to 10.0 mm. The results are shown in FIG. When the electrode diameter is smaller than 2.8 mm, arcing and continuous generation are good, but the electrode is blown before the entire circumference welding is completed. This is presumably because the arc is less likely to concentrate and spread under reduced pressure, so that the length of the glowing portion of the tungsten electrode increases, leading to fusing. The electrode diameter is 4.5mm
If the current exceeds the value, it is necessary to increase the current value because the continuity of arc generation is insufficient and the metal does not melt.
Since a current value of 0 A or more is required, thermal effects occur on portions other than the welded portion, which results in breakage of the device and excessive melting, which is not suitable for continuous welding.

In order to carry out the continuous welding sealing of the container 1, a cooling water from the cooling water intake 10 is provided to the lid 2 in the rotary drive unit 21 to constantly cool the cooling water by providing a flow path to the lid 2. Cooling water is taken out from a cooling water outlet 9. The electrode 3 uses a commercially available water-cooled torch, is inserted through a cooling water inlet 7 and is taken out through a cooling water outlet 8 to prevent overheating.

[0025]

According to the present invention, the entire container having an assembly gap is put in a dedicated vacuum container, evacuated, and sealed, and replaced with argon gas to a predetermined pressure. Since the arc is generated from the electrode and the entire circumference of the cylindrical metal container is welded and sealed, the same reliable welding and sealing can be performed every time without requiring a dedicated hole for sealing and degassing. In addition, by supplying cooling water to the welding and electrode torch portion, there is an effect that the selected welding conditions due to overheating and fluctuations in pressure in the welding vessel are suppressed and continuous welding sealing can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention.

FIG. 2 is an assembly diagram of an electrode shape, a container and a lid in the embodiment.

FIG. 3 is a diagram showing a relationship between a tungsten electrode diameter and arc generation.

FIG. 4 is a diagram showing the weldability depending on the initial vacuum degree before argon gas replacement.

FIG. 5 is a sectional view of a conventional example.

FIG. 6 is a sectional view of a conventional container.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Lid, 3 ... Tungsten electrode, 4 ... Vacuum container, 5 ... Argon gas supply pipe, 6 ... Vacuum gauge, 7, 10 ...
Cooling water inlet, 8, 9 ... Cooling water outlet, 11, 1
2, 13 ... O-ring, 14 ... Welder power cord, 15 ...
Rotary drive motor, 16: vacuum exhaust line, 17: vacuum pump, 18: vacuum container door, 19: welding machine, 20: vacuum valve, 21: rotary drive unit, 22: argon gas valve, 23: receiving unit, 24 ... Active material such as sodium or sulfur.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yukihiro Umezu 3-1-1, Sachimachi, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. Hitachi Plant

Claims (8)

[Claims] 1. An apparatus for sealing an active material such as sodium or sulfur in a cylindrical metal container, wherein the inside of the vacuum container is 1.3 ×.
It has a means for making a vacuum of 10 ¹ Pa or more and a means for controlling the pressure to a constant value of 4.0 × 10 ³ Pa or less by purging with an argon gas. A pressure reducing sealing device for a sodium-sulfur battery, wherein the entire circumference is sealed with a tungsten electrode argon gas welding device. 2. The tungsten electrode according to claim 1,
Holds 1.7% to 2.2% of lanthanum oxide, electrode diameter is 2.8mm to 4.5mm, electrode tip shape is tip angle 1
A reduced pressure sealing device for a sodium-sulfur battery, wherein the device is set to 0 to 30 degrees and the gap between the electrode and the cylindrical metal container is welded to 0.5 to 3.0 mm. 3. The sodium welding method according to claim 1, wherein the electrode chuck portion and the cylindrical metal container chuck portion are continuously welded by having an overheating prevention mechanism for flowing cooling water having a flow rate of 1 liter / minute or more. Vacuum sealing device for sulfur batteries. 4. The rotation control mechanism for a cylindrical metal container according to claim 1, wherein the entire circumference of the cylindrical metal container is welded at a rotation speed of 0.5 to 5 rpm using a motor installed outside the vacuum container as a rotation source. Pressure reducing sealing device for a sodium-sulfur battery. 5. The welding power source for a cylindrical metal container according to claim 1, wherein the welding power source is a direct current welding power source installed outside the vacuum container and has a current value of 5 mm.
A reduced pressure sealing device for a sodium-sulfur battery, wherein the entire circumference of a cylindrical metal container is welded at 0A to 180A. 6. A sodium-sulphur automatic welding system in which a rotation control mechanism for a cylindrical metal container and a welding power source are placed outside the vacuum container, and electrode position control, gas pressure control, gas flow control, and cooling water flow control are performed automatically. Battery vacuum sealing device. 7. A method for sealing an active material such as sodium or sulfur in a cylindrical metal container, wherein a portion to be sealed after the active material is charged into the cylindrical metal container is formed by fitting a lid to the cylindrical metal container and welding. In the fitting portion of the cylindrical metal container and the lid, a gap necessary for evacuating gas other than solid matter in the cylindrical metal container is provided, and the cylinder is inserted into the vacuum container and evacuated. After vacuuming the inside of the metal container, argon gas is introduced while maintaining the vacuum container at a negative pressure, the inside of the cylindrical metal container is set to a negative pressure argon gas atmosphere, and the inside and outside of the cylindrical metal container is controlled to a constant negative pressure. And welding by a welding method in which a cylindrical metal container is rotated and sealed by tungsten electrode argon gas welding. 8. The method according to claim 1, wherein the active material is sealed in the cylindrical metal container. The cylindrical metal has a gas vent groove of a slit groove in a direction substantially perpendicular to a welding line at a fitting portion between the metal and the lid. 8. The sodium according to claim 7, wherein the cylindrical metal container is evacuated in a short time while the metal container is covered, and the slit groove is melted and sealed at the same time by full circumference welding. -A method of sealing the sulfur battery under reduced pressure.