JPH08332570A - Tig welding method - Google Patents

Abstract

PURPOSE: To provide TIG welding method capable of controlling a current, position, etc., of welding torch, with a digital computer and obtaining highly convergent arc. CONSTITUTION: In TIG welding method, in which by butting metals 3, 4 to be welded each other, connecting a power source between the metals 3, 4 and a welding torch 1 for generating arc and supplying inert gas, the metals 3, 4 each other are welded, an intermediate frequency pulse power source 25 having reduced generation of electromagnetic waves to power source is used as well as helium is used for inert gas.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a TIG welding method.

[0002]

2. Description of the Related Art TIG (Tungste) is one of the arc welding methods.
n Inert Gas) There is a welding method.

FIG. 6 is a conceptual diagram of a conventional TIG welding method.

In the figure, 1 is a welding torch 1 and 2
Is a high frequency power supply for generating an arc between the metal 3 and 4 butted to each other and the welding torch 1. Reference numeral 5 is an argon gas cylinder for supplying an argon gas for preventing the oxidation of the welded portion. Reference numeral 6 is an analog control circuit for controlling the arc current, voltage or position of the welding torch 1.

[0005] Such a welding torch 1 is brought close to the joint portion of the metals 3 and 4 butted against each other, and an argon gas is supplied. At the same time, a high-frequency power source 2 is used to increase the high-frequency power between the welding torch 1 and the metals 3 and 4. Apply voltage. This creates an arc 7 between the welding torch 1 and the metal 3, 4. The heat generated by the arc 7 melts the joints of the metals 3 and 4 to weld the metals together.

FIG. 7 is a conceptual diagram of another conventional example of the TIG welding method.

In the figure, a welding torch 1, a pulseless power supply (DC high voltage power supply) 8 for generating an arc between the metal 3 and 4 to be welded and the welding torch 1, an argon gas cylinder 5, and welding A digital computer 9 for controlling the current, voltage, position, etc. of the torch 1 is shown.

[0008] Such a welding torch 1 is brought close to the joint portion of the metals 3 and 4 butted against each other, and argon gas is supplied, and at the same time, a direct current is supplied from the pulseless power source 8 between the welding torch 1 and the metals 3 and 4. Apply high voltage. This creates an arc 10 between the welding torch 1 and the metal 3,4. The heat generated by the arc 10 melts the joints of the metals 3 and 4 and welds the metals 3 and 4.

[0009]

By the way, in the conventional example shown in FIG. 6, since the high frequency power source 2 is used as the power source, the focusing property of the arc 7 is high. However, since the analog control circuit 6 is used to control the current, position, etc. of the welding torch 1, welding cannot be performed accurately.

On the other hand, in the conventional example shown in FIG. 7, since the digital computer 9 is used, the welding torch 1
It is possible to accurately control the current, position, etc. However, since the pulseless power source 8 is used as the power source, the energy of the arc 10 is small and the focusing property of the arc 10 is low. For this reason, for example, when welding a horizontal pipe from the inside, the welded portion at the upper end may melt and drop, making it impossible to perform welding. Further, it is impossible to weld a base material having a thickness of 4 mm or more.

Therefore, a high frequency power source is used as the power source,
It is possible to control the position and current of the welding torch with a digital computer.

However, the frequency of the high-frequency power source is usually 1 KHz, and self-noise (electromagnetic waves) is generated, and this self-noise may enter the digital computer due to electromagnetic induction and cause a malfunction. Further, since the arc current is as large as several tens of amperes, even if the digital computer and the welding torch are separated from each other, a large current may flow through the digital computer due to electromagnetic induction, causing a failure.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a TIG welding method capable of controlling the current and position of the welding torch with a digital computer and obtaining a highly focused arc.

[0014]

In order to achieve the above-mentioned object, the present invention aims to butt together metals to be welded and connect a power source between the metal and the welding torch to generate an arc and supply an inert gas. Then, in the TIG welding method for welding metals together, a medium-frequency pulse power source that generates a small amount of electromagnetic waves is used as a power source, and helium gas is used as an inert gas.

In addition to the above construction, the present invention is one in which the current and voltage of the arc and the position of the welding torch are controlled by a digital computer.

In addition to the above configuration, the present invention is one in which the frequency of the medium frequency pulse power supply is set to about 100 Hz.

[0017]

According to the above construction, when the arc is generated by the pulse from the medium frequency pulse power source, the arc having a high focusing property is generated. Electromagnetic waves are hardly generated from the medium-frequency pulse power source, and therefore, even if a digital computer is used for controlling the arc current and arc voltage and the position control of the welding torch, there is no influence of the medium-frequency pulse. Further, since the helium gas which is hard to be ionized is used as the inert gas, the generation of the arc plasma is promoted and the energy is not dispersed, so that the arc having a higher focusing property can be obtained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the TIG welding method of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram of the TIG welding method of the present invention. The same reference numerals are used for the same members as those in the conventional example described above.

In the figure, reference numeral 20 denotes a rod-shaped tungsten electrode, the tip (lower end in the figure) of which is formed into a conical shape. This tungsten electrode 20 has a cylindrical collet 21.
It is held inside and is provided coaxially within the substantially cylindrical gas nozzle 22. The tungsten electrode 20, the collet 21, and the gas nozzle 22 constitute the welding torch 1.

An intermediate frequency pulse power supply 25, in which an intermediate frequency pulse generator 23 and a DC high voltage power supply 24 are connected in series, is connected to the collet 21 and the metals 3 and 4 that are butted against each other. The medium frequency pulse generator 23 has a frequency of 1
Although a high voltage pulse of 00 Hz is generated, the present invention is not limited to this, and may be any frequency (several hundreds of Hz) at which electromagnetic noise is not generated.

Reference numeral 26 is a cylinder for containing a helium gas as an inert gas. Tungsten electrode 20
A pipe 27 is provided between the welding torch 1 and the cylinder 26 so as to supply helium gas between the gas nozzle 22 and the gas nozzle 22.

FIG. 2 is a conceptual diagram of an embodiment of a TIG welding machine to which the TIG welding method of the present invention is applied, and FIG.
FIG. In addition, the case where a pipe and a tubular joint are used as the metal to be welded will be described.

In the figure, 28 is an arm of a robot 29 for rotating or moving the welding torch 1. A medium frequency pulse power supply 25 is connected between the welding torch 1 and the pipe 30 (or the joint 31). A cylinder 26 for ejecting argon gas to the joint 32 is connected to the welding torch 1 via a pipe 27. A digital computer 33 is connected to the robot 29 and the medium frequency pulse power supply 25.

Next, the operation of the embodiment will be described.

The robot 29 is operated in accordance with an instruction from the digital computer 33 to bring the welding torch 1 closer to the joint 32 between the metal pipe 30 and the joint 31 that are butted against each other. When argon gas is supplied to the welding torch 1 from the cylinder 26, the argon gas is supplied from the welding torch 1 to the joint 32.
Is jetted toward. When the medium frequency pulse power supply 25 is activated, an arc 34 is generated between the welding torch 1 and the joint 32. Since the arc 34 is generated by the high voltage pulse from the medium frequency pulse power supply 25, not only the focusing property is high, but also the electromagnetic noise is less generated and the digital computer 33 is not affected. Therefore, a proper arc current and voltage are used for the welding torch 1, the metal tube 30, and the joint 3.
The welding speed and welding position of the welding torch 1 are accurately controlled. Moreover, since argon gas, which is hard to be ionized, is used as the inert gas, the generation of arc plasma is promoted and the energy is not dispersed, so that the arc 34 having a higher focusing property can be obtained. By such arc 34 having a high focusing property, the joint portion 32 is thin and deeply melted, and even if a metal having a thickness of 4 mm is welded, the joint portion 32 does not melt and drop.

FIG. 4 is a diagram showing an arc by the conventional TIG welding method. FIG. 5 is a diagram showing an arc by the TIG welding method shown in FIG.

It can be seen from FIGS. 4 and 5 that the arcs 35 generated by the conventional TIG welding method are dispersed and the arcs 34 generated by the TIG welding method of this embodiment are concentrated. Therefore, according to the TIG welding method of the present embodiment, it can be applied to the first layer backside welding and the groove welding of the small diameter pipe.

[0029]

In summary, according to the present invention, the following excellent effects are exhibited.

Since the medium frequency pulse power source is used as the power source and the argon gas is used as the inert gas, the position and current of the welding torch can be controlled by the digital computer and a highly focused arc can be obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a TIG welding method of the present invention.

FIG. 2 is a conceptual diagram of an embodiment of a TIG welding machine to which the TIG welding method of the present invention is applied.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a diagram showing an arc according to a conventional TIG welding method.

5 is a diagram showing an arc by the TIG welding method shown in FIG.

FIG. 6 is a conceptual diagram of a conventional TIG welding method.

FIG. 7 is a conceptual diagram of another conventional example of the TIG welding method.

[Explanation of symbols]

 1 Welding torch 3, 4 Metal 25 Medium frequency pulse power supply 26 Cylinder

Claims (3)

[Claims] 1. A TIG welding method for welding metal members to be welded together, connecting a power source between the metal and a welding torch to generate an arc, and supplying an inert gas to weld the metal members together. A TIG characterized in that a helium gas is used as the inert gas and a medium-frequency pulsed power supply with a small generation of electromagnetic waves is used for
Welding method. 2. The TIG welding method according to claim 1, wherein the current and voltage of the arc and the position of the welding torch are controlled by a digital computer. 3. The frequency of the medium-frequency pulse power supply is approximately 10
The TIG welding method according to claim 2, wherein the frequency is 0 Hz.