JP2001150144A - Plasma welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of a tungsten electrode rod. SOLUTION: The plasma welding equipment is characterized in that an oxygen absorbent is provided at a pilot gas flow passage between a space 14 around an electrode of a plasma torch 10 and a pilot gas supplying source 29. The oxygen absorbent is provided at the flow passage which originates at a power source device 20 and leads to the plasma torch 10. Further, an inlet side valve device 24 for opening and closing a flow passage between a vessel 22 containing the oxygen absorbent and a gas supply passage for the vessel, and an outlet side valve device 25 for opening and closing a flow passage between the vessel and the torch are provided. A bypass valve device 26 is connected in parallel with the series connection of three elements composed of the inlet side valve device 24, the vessel 22, and the outlet side valve device 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma welding apparatus, and more particularly to a gas system for supplying a pilot gas from a pilot gas supply source to a space around an electrode of a plasma torch.

[0002]

2. Description of the Related Art Plasma welding machines are widely used in automatic welding machines in automobiles, home appliances, general industrial equipment, pipe-forming industries and the like. The demands of the automatic welding machine from users include (1) stable quality for a long time, and (2) long life of consumables.

On the other hand, in the plasma welding torch, the tungsten electrode becomes hot due to the elapse of the arc generation time, the evaporated tungsten scatters and adheres to the welding tip, the nozzle hole diameter becomes narrow, and the welding voltage becomes high. And a series arc is easily generated, and the welding arc is disturbed, which causes welding defects. Therefore, an increase in welding voltage and the occurrence of a series arc are guidelines for maintenance of the welding torch.

[0004] On the other hand, as the prior art, Patent No. 2
No. 685952 "Plasma Torch Cleaning Method"
There is. This is because when the nozzle hole diameter is reduced due to foreign matter adhering to the welding tip, when welding work is completed, the tungsten electrode is kept energized and the pilot gas flow rate temporarily supplied to the nozzle is increased, and It is a method of blowing off.

[0005]

However, this method has problems that a large amount of gas is used and that the method cannot be performed during a long continuous welding operation. Also, depending on the purity of the gas used, the interval of the maintenance time may be extremely short. As a countermeasure, a gas of high purity (99.999%) may be used, but it has a disadvantage that it is very expensive and costly. An object of the present invention is to reduce the consumption of a tungsten electrode rod.

[0006]

One of the causes of the consumption of the tungsten electrode rod is the amount of oxygen mixed in the pilot gas (Ar). The purity of the commonly used welding argon gas is
99.99% is common. However, oxygen is a problem among the impurities contained in the third place. Therefore, by removing this trace amount of oxygen to obtain a high-purity gas, the life of the tungsten electrode rod is extended.

(1) A plasma welding apparatus according to the present invention for realizing this is provided with a space (1) around an electrode of a plasma torch (10).
An oxygen absorbent (22) is provided in the pilot gas flow path between (4) and the pilot gas supply source (29).

For easy understanding, the symbols of the corresponding elements or corresponding parts in the embodiments shown in the drawings and described later are added in parentheses for reference. The same applies to the following.

According to this, the pilot gas supply source (29)
From the gas to the space (14) around the electrodes of the plasma torch (10), trace oxygen in the pilot gas
It is removed in 2), the consumption of the electrode (11) of the plasma torch (10) is reduced, and the service life of the tip (12) is prolonged. In addition, it was found that the fluctuation of the arc voltage was reduced.
It is presumed that the reduction in the consumption of the electrode (11) leads to a reduction in the amount of tungsten vaporized and scattered on the tip (12), which greatly contributes to the suppression of an increase in arc voltage.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (2) Pilot gas supply source (29)
In the plasma welding apparatus for supplying a pilot gas to the plasma torch (10) through a gas flow path in a power supply box (20) storing a welding power source, the plasma torch (10) exits the power supply box (20). Characterized in that an oxygen absorbent (22) is provided in the flow path leading to.

A power torch (20) contains a plasma torch (1).
There is a gas flow regulator (34) for adjusting the flow rate (liter / min) of the pilot gas supplied to the (0), and a valve device (33) for supplying / stopping the gas. When air enters from the seam or seam, or the seam with the gas pipe or hose, or the air that has accumulated during non-use is not sufficiently released, a small amount of air may flow out to the torch for a relatively long time during use of the torch. Conceivable. If an oxygen absorbent is provided between the pilot gas supply source (29) and the power supply box (20), it is not possible to prevent the oxygen of such leaked or retained air from flowing to the torch (10). However, by arranging the oxygen absorbent (22) in the flow path from the power supply box (20) to the plasma torch (10), such oxygen can be effectively removed, and the electrode (11) and the chip (12) It is expected that the service life can be extended more effectively.

(3) Container containing the oxygen absorbent (22)
And an inlet valve device (24) for opening and closing a gas supply passage to the container, and an outlet for opening and closing a passage between the container (22) and the plasma torch (10). And a valve device (25).

When the plasma welding device is not used, the inlet valve device (24) and the outlet valve device (25) are turned off (cut off the flow passage) so that the power supply box (20) can be used while not in use. ) Side to the oxygen absorber (22) and the torch (10)
The flow of air from the side to the oxygen absorbent (22) is blocked, and wasteful oxygen absorption of the oxygen absorbent is suppressed, so that the service life of the oxygen absorbent can be extended.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0015]

FIG. 1 shows an outline of the appearance of an embodiment of the present invention. In FIG. 1, a gas supply system is shown, and illustration of a power supply system is omitted. FIG. 2 shows a gas system inside an outer box or casing of the power supply device 20.

Referring to FIGS. 1 and 2, the pilot gas of the gas cylinder 29 is supplied with a gas hose 35 and a power supply 2.
0, a gas receiving base 28 attached to the outer case, a gas flow regulator 34, an electromagnetic on-off valve 33 for checking a welding power source gas,
Via a gas supply base 27 attached to the outer case of the power supply device 20, an inlet-side electromagnetic on-off valve 24, a deoxidizing cylinder 22 containing an oxygen absorbent, and an outlet-side electromagnetic on-off valve 25 on the mounting plate 21. Is supplied to the inner space 14 of the tip 12 of the plasma torch 10 and exits from the nozzle at the tip of the tip 12. Inlet-side solenoid on-off valve 24, deoxidizing cylinder 22, and outlet-side solenoid on-off valve 25
The on-off solenoid on-off valve 26 is connected in parallel with the series connection so that a gas flow path that bypasses the
Is connected. All the solenoid on-off valves 24 to 26 and 33 are normally closed valves, open (distributed) when the electric coil is energized, and closed (disconnected) while the electric coil is not energized. .

When the pilot gas is supplied to the plasma torch 10, the electromagnetic on / off valve 33 in the outer case of the power supply device 20 is first energized to open (distribute) the electromagnetic on / off valve 33. Energize valve 26 to open it. Solenoid on-off valve 2 for bypass on mounting plate 21
6 is open, the gas in the pilot gas supply system is supplied to the inlet-side solenoid on-off valve 24, the deoxidizing cylinder 22, and the outlet-side electromagnetic on-off valve 25.
If the air stays in the gas path from the base 28 to the base 27 while the welding apparatus is stopped, it does not enter the deoxidizing cylinder 22. At the timing when the stagnant gas flows out and the pilot gas of the gas cylinder 29 flows constantly to the plasma torch 10,
By opening the electromagnetic on-off valves 24 and 25 and closing 26, the supply setting of the deoxidized pilot gas to the plasma torch 10 is completed. When the supply of the pilot gas is stopped, all of the solenoid valves 24 to 26 on the mounting plate 21 are closed (cut off), and the solenoid on-off valve 33 of the power supply device 20 is closed.
Is also closed (cut off).

In the space 15 between the tip 12 of the plasma torch 10 and the shield nozzle 13, the shielding gas of the gas cylinder 32 is filled with a gas receiving base 31, an electromagnetic on-off valve 37, and a gas supply base mounted on the outer case of the power supply 20. 30. The supply / stop of the shielding gas is performed by an electromagnetic on-off valve 37. Next, an experimental example using the above-described welding apparatus will be described.

Welding conditions: Tungsten electrode 11: containing 2% thorium, φ1.6 m
m Pilot gas: 99.99% purity (Ar + 7% H2) Cooling water temperature: 25 ° C. Torch height: 3.5 mm Nozzle diameter: φ1.6 mm Pilot gas flow rate: 0.3 liter / min Shield gas flow rate: 7 Liter / min Welding current: 80A.

Deoxidizing cylinder 22: The deoxidizing cylinder 22 is a deoxidizing column which is a high-purity gas purifier and has a capacity to adsorb 200 cc of oxygen. This corresponds to the ability to process 1 ppm of oxygen for 200 cubic meters. Under the welding conditions in which the oxygen content in the pilot gas flow path is 10 ppm and the pilot gas flow rate is 0.5 liter / min, if the operating time per day is 8 hours, it can be used for about 80 days.

Operation: The manual valve of the gas cylinder 29 is opened, and the solenoid valves 33 and 26 are energized to open them, the pilot gas flows through the plasma torch 10, the manual valve of the gas cylinder 32 is opened, and the solenoid valve 372 is opened. It is opened by energization, and a shielding gas is flowed into the plasma torch 10. Plasma torch 10 from pilot gas cylinder 29
After the cleaning (removal of air) is completed, the solenoid valves 24 and 25 are energized and opened, and the solenoid valve 26 is deenergized and closed. After that, the pilot arc is ignited, and the welding arc is turned ON / OFF to perform welding work.

When a deoxidizing cylinder 22 is not used as a comparative example
(Electromagnetic on / off valve 26 flow, electromagnetic on / off valves 24, 25 shut off), as a first embodiment, mounting plate 21 is fitted with base 28 and gas cylinder 2
9, that is, when the deoxidizing cylinder 22 (mounting plate 21) is inserted between the power supply device 20 and the gas cylinder 29, and as a second embodiment, the mounting plate 21 is The electromagnetic switching valve 26 is shut off by being inserted between the device 20 and the plasma torch 10, and the electromagnetic switching valves 24 and 25
In the case where the deoxidizing cylinder 22 is inserted between the power supply device 20 and the plasma torch 10 as a flow, the electrode mass of the tungsten electrode 11 is measured in three cases, and the tip surfaces of the tungsten electrode 11 and the insert tip 12 are measured. Photo shoot.

In each of the three cases, the arc voltage was measured at 10 minute intervals, the mass of the tungsten electrode 11 was measured, and the tungsten electrode 11 and the insert tip 1 were measured.
Photograph 2 was taken after a one hour continuous arc. Table 1 below
2 shows the results of mass measurement of the tungsten electrode 11, and Table 2 shows the results.
Table 4 shows changes in the arc voltage. Table 5 shows the average of three measured values of the arc voltage.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

[Table 5]

FIG. 3 shows a photographed image of the tungsten electrode 11 and the insert tip 12, and FIG. 4 shows changes in the arc voltage shown in Table 5.

Referring to Table 1, in comparison with the comparative example in which the deoxidizing cylinder 22 was not used, Examples 1 and 2 in which trace oxygen was removed by the oxygen absorbent of the deoxidizing cylinder 22 were clearly depleted of the tungsten electrode. The amount is small. This is a result of the fact that the oxygen contained in the pilot gas was removed, the amount of tungsten oxidized was reduced, and the amount of tungsten scattered was reduced. In addition, from the results of all of the first to third times, it is found that the use of the oxygen absorbent results in more stable arc discharge.

In the first embodiment in which the oxygen absorbent is set at the inlet of the power supply device 20, the same result as in the second embodiment in which the oxygen absorbent is set at the outlet may be obtained. The loss mass of the electrodes is clearly lower. This seems to be due to the fact that when set at the entrance, some air will inevitably enter through the seams of the screws.

Reference is made to Tables 2 to 5 and FIG.
In the second measurement in Table 2 (Comparative Example), a series arc occurred after about 40 minutes, and the measurement was stopped and then again performed, so that an accurate value could not be measured. The average of the change in voltage was extracted and shown in Table 5 and FIG. Referring to these figures, it is understood that the voltage increase is the fastest in the comparative example, and the stable state is continued for a long time by using the oxygen adsorbent in Examples 1 and 2 next.
This is because when the arc is discharged from the acute angle portion of the tip of the tungsten electrode, the tip becomes red-hot, oxygen contained in the pilot gas reacts, becomes tungsten oxide, lowers the melting point, and evaporates and scatters. As shown in FIG. 5B, the evaporative splatters adhere to the tip hole of the insert tip 12 and the hole diameter is reduced, and as a result, the electric resistance in the arc passage is increased and the arc voltage is changed. Because. For this reason, the durability of the tungsten electrode is better when the increase rate of the arc voltage is lower, and the life is longer. In the comparative example, it takes about 30 minutes to change by 2V, whereas the working examples 1 and 2 have about 50 minutes, which is about 1.7 times the life. However, it is difficult at present to completely eliminate the loss of the tungsten electrode. However, the effect can be further improved by attaching an oxygen adsorbent near or in the torch 10.

Referring to FIG. In the comparative example, the tungsten electrode rod was severely lost in all of the first to third times, and the tip was melted down. Along with that, a lot of deposits that have melted out from the tungsten electrode rod have arrived. In Example 1, the value was good at the second time, and the surface when the tungsten rod was shaved remains, indicating that it was not so melted. Nothing else looks so bad. In Example 2, the surface of the tungsten electrode rod after shaving remains, indicating that the tungsten electrode rod is not so melted and is in a good state. The insert tip does not seem to be very different from Example 1 and there is no noticeable difference in the photograph.

In an actual welding operation, maintenance of the torch is required about every two hours under normal use conditions such as the comparative example. However, as in the second embodiment, the outlet of the power supply device 20 and the plasma torch 10 are connected to each other. When the deoxidizing cylinder 22 is inserted between
It can be used for about 6 hours.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of a main part of an embodiment of the present invention.

FIG. 2 is a block diagram showing a pilot gas flow path in an outer case of the power supply device 20 shown in FIG.

FIG. 3 is a photograph showing the appearance of a tungsten electrode rod and an insert tip of the plasma torch 10 shown in FIG. 1 after an experimental use.

FIG. 4 is a graph showing a change in arc voltage during experimental use of the plasma torch 10 shown in FIG.

FIG. 5A is an enlarged vertical sectional view of the insert tip 12 before using the plasma torch 10 shown in FIG. 1,
(B) is an enlarged longitudinal sectional view after use.

[Explanation of symbols]

10: Plasma torch 11: Tungsten electrode 12: Insert tip 13: Shield nozzle 14: Space around electrode 15: Inner space of shield nozzle 16, 17: Gas hose 20: Power supply device 21: Mounting plate 22: Deoxidizing cylinder 24-26 , 33, 37: solenoid on-off valve 27, 28, 30, 31: base 29, 32: gas cylinder 34: gas flow regulator 35, 36: gas hose

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E001 LD03 LH08 LH09 LH11 ME11 NA08 4E082 AA09 EA01 EA12 EB11 ED03 EF21

Claims (3)

[Claims] 1. A plasma welding apparatus wherein an oxygen absorbent is provided in a pilot gas flow path between a space around an electrode of a plasma torch and a pilot gas supply source. 2. A plasma welding apparatus for supplying a pilot gas to a plasma torch from a pilot gas supply source through a gas flow path in a power supply box storing a welding power supply, wherein a flow from the power supply box to the plasma torch is provided. A plasma welding apparatus, wherein an oxygen absorbent is disposed on a road. 3. An inlet valve device for opening and closing a container containing the oxygen absorbent and a gas supply flow path to the container.
The plasma welding apparatus according to claim 1 or 2, further comprising an outlet valve device for opening and closing a flow path between the container and the plasma torch.