JPS603980A - Method and device for oscillating arc in gas shielded metal arc welding - Google Patents

Abstract

PURPOSE:To oscillate a welding arc by a simple method in the stage of gas shielded metal arc welding by ejecting alternately a shielding gas and a control gas having a different potential inclination from the right and left with respect to the advancing direction of a welding torch. CONSTITUTION:A voltage is impressed between a welding wire 1 attached to a welding torch 1 and materials 21 to be welded to generate an arc 20 and to melt the wire 1, thereby welding the groove of the materials 21. A shielding gas 23 such as Ar is ejected from the gas nozzle 2 on the outside of the torch 1 to shield the weld zone against air. Gaseous CO2 24 are ejected alternately from the left and right side as a control gas in the stage of such welding. Since the gaseous CO2 has the ionization potential higher than the ionization potential of the gaseous Ar, the arc 22 is swung alternately to the right and left side walls 21a, 21b of the groove toward the direction where the potential inclination is low and therefore the groove is welded with weaving without oscillation of the torch 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for oscillating an arc in gas-shielded metal arc welding.

An arc is generated between the welding wire and the base metal, and this arc is used as a heat source to melt the welding wire and base metal, and a shielding gas such as argon or carbon dioxide is flowed around the arc to isolate the welding area from the surrounding air. In gas-shielded metal arc welding, the arc is generally oscillated in order to sufficiently penetrate the welded area and prevent welding defects from occurring.

Conventionally, this arc oscillation method involves riving the torch by mechanical means, and adding a mechanism to the welding wire supply device to forcibly apply bending prestrain to the welding wire. A device whose tip is extended while swinging is known. However, all of these methods have the disadvantage that the mechanism is complicated and the device becomes large.

The present invention was developed in view of the above points, and aims to provide a method and device for oscillating an arc simply and economically without requiring a complicated mechanism.
The unique feature of this method is to oscillate the arc by alternately ejecting a shielding gas and a control gas with different potential gradients from the left and right sides of the welding torch in the direction of travel. The welding torch body is made with flow channels so that the gas can be communicated near the contact tip of the welding torch to both left and right sides in the direction of travel of the welding torch, making it compact and compact.

Ah,. 1 The present invention will be explained below with reference to FIGS. 1 to 3. FIG. 1 is a diagram for explaining the present invention in detail. In normal gas-shielded metal arc welding, the voltage applied by the welding power source is connected to the welding wire 20 through the contact tip provided at the tip of the welding torch 1. The voltage is applied between the objects 21 to be welded, and an arc 22 is generated between the tip of the welding wire 20 and the object 21 to be welded. A welding torch 1 is placed around the arc 22.
It is covered with a shielding gas 23 such as argon ejected from a gas nozzle 2 provided near the gas nozzle 2 to block air.

When the center of the welding wire 20 is located at the center of the groove of the workpiece 21, the arc 22 has a symmetrical shape with the welding wire 20 at the center, as shown in FIG. 1(a). Ru. Now, in this state (the shielding gas 23 is argon gas), carbon dioxide gas is used as the control gas 24 in Fig. 1 (b).
) as shown by the dotted line, it is ejected from the left side when viewed from the direction of movement of the welding torch 1. As a result, the arc 22 is swung against the groove right side wall 21b of the workpiece 21 to be welded. This is because carbon dioxide gas is attracted by the high-speed plasma airflow of the arc column and forms a layer of carbon dioxide gas between the left side wall 21a of the groove and the arc column, and carbon dioxide gas has a higher ionization voltage than argon gas, so welding Compared to the potential gradient between the tip of the wire 20 and the right side wall 21b of the groove, the tip of the welding wire 20 and the left side wall 21a of the groove
This is because the potential gradient becomes high, and the arc 22 is generated so as to be swung toward the right side wall 21b of the groove where the potential gradient is low.

In the same way, control gas 24 (carbon dioxide gas) is melted and applied to torch 1.
If the arc 22 is ejected from the right side as viewed from the direction of movement, the arc 22 is generated in a state in which it is swung toward the left side wall 21a of the groove, as shown in FIG. 1(C), contrary to the above case. By repeating this operation alternately, that is, by ejecting the control gas 24 alternately from the left and right sides of the welding torch 1 for a certain period of time,
The arc 22 is oscillated left and right about the center of the groove. According to the experiment, the amount of control gas is st7 for shield gas (argon gas) 30t/min.
It was found that oscillation was sufficient within about a minute.

Further, it is also possible to use carbon dioxide gas as the shield gas and argon gas as the control gas, contrary to the above description. In this case, the arc 22 is shown in Figure 1 @(C
) and vice versa (III, that is, the control gas is swung toward the side from which it was ejected.The shield gas is generally argon, carbon dioxide, helium, or a mixture of these gases, but if the control gas is The present invention can be carried out without any particular limitation by selecting those having different slopes.

Next, an apparatus for carrying out the method of the present invention will be explained with reference to FIGS. 2 and 3. FIG. 2 is a sectional front view of the welding torch 1, and FIG. 3 is a sectional view taken along the line I in FIG.

A wire supply body 4 is fixed to the upper center of the main body of the welding torch 1 with screws 4b. This wire supply body 4 is provided with a power supply terminal 5 connected to a welding power source and a shielding gas supply port 6, and a pipe 4c is inserted into the center of the wire supply port 43. , Oya'y
The welding torch 1 has a cylindrical upper part with a tapered part in the center, and a plate-shaped lower part to enable narrow gap welding. (see Figure 3).

In the center of the welding torch 1, holes 1c and 1d are bored, which communicate with a shielding gas flow path 6a formed inside the wire supply body 4 and through which the shielding gas is ejected.

A control gas supply lower 8 is provided at the top of the welding torch 1 to eject control gas from left and right in the direction of movement of the welding torch 1 (indicated by arrows). 1, flow paths 7a and 8a for control gas are formed.

A hole 1a communicating with the pipe 4c of the wire supply body 4 is vertically formed in the center of the welding torch 1, and a contact tip 3 is screwed into the lower end. The tap 1b to which the contact tip 3 is attached has flow paths 7b and 8b communicating with the control gas flow paths 7a and 8a, and as shown in FIG. They are formed to eject from each direction (with respect to the direction).

In addition, a cooling water supply port 9 and a cooling water discharge port 10 are provided in the upper part of the welding torch 1 in order to cool the torch.
5E is formed. The welding torch 1 has an insulating bushing 11
A cylindrical gas nozzle 2a is screwed onto the outer periphery of the insulating bushing 11. Further, a gas nozzle 2 that fits the gas nozzle 2a is attached with a tightening ring 12, so that the gas nozzle 2 can be moved up and down depending on the shape of the welded part and fixed at an appropriate position.

Next, a case in which welding is performed using the apparatus configured as described above will be explained.

The welding wire is fed into the welding wire supply port 4a from a wire reel (not shown) via a supply device, and is fed out through the hole 3b of the contact tip 3. Then, shear arc occurs when power is applied.

In this case, cooling water flows in from the cooling water supply port 9, circulates within the welding torch 1, and flows out from the cooling water outlet 10 to cool the welding torch 1.

On the other hand, shielding gas such as argon is supplied to shielding gas supply port 6.
The gas is introduced from the gas nozzle 2a and the welding torch 10 through the flow path 6a and the hole 10.degree. 1d and is ejected downward between the gas nozzle 2a and the welding torch 10. Further, a control gas such as carbon dioxide gas having a potential gradient different from that of the shielding gas is alternately fed from the control gas supply lower 8 by a solenoid valve or the like at regular intervals.

Control gas flows through channels 7a and 7bt or channels 8a and 8b ib.
, are ejected alternately from the left and right sides of the contact tip 3 (indicated by arrows in FIG. 3). Therefore, by simply moving the welding torch 1 linearly along the welding line, the arc is oscillated as explained above.

As explained above, according to the present invention, there is no need to provide a complicated mechanism for swinging the welding torch in the width direction of the groove or for creating a bend in the welding wire, as in the past, in a simple and reliable manner. The arc can be oscillated. In addition, since the control gas is ejected through a flow path drilled in the welding torch body which is constantly cooled, the influence of welding spatter and temperature is reduced, making it compact and extremely durable.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the principle of the method of the present invention.
) is a state diagram of normal gas-shielded metal arc welding, and (C) in FIG. 1 is a state diagram when the arc is oscillated by applying a control gas. 2 and 3 show an embodiment of the apparatus used in the method of the present invention, with FIG. 2 being a sectional front view and FIG. 3 being a sectional view taken along the line 1--I in FIG. ■ is a welding torch, 1a is a hole, 1b is a tap, 1c, 1d
is a hole, 2 and 2a are gas nozzles, 3 is a contact tip,
3b is a hole, 4 is a wire supply body, 4a is a welding wire supply port, 4b is a screw, 4C is a pipe, 5 is a power supply terminal, 6
is a shield gas supply port, 6a is a flow path, 7 is a control gas supply port, 7a and 7b are flow paths, 8 is a control gas supply port, Ba, B
b is a flow path, 9 is a cooling water supply port, 9a is a flow path, 10 is a cooling water outlet, 11 is an insulating bushing, 12 is a tightening ring, 2
0 is a welding wire, 21 is a workpiece to be welded, 21a is a left side wall of the groove, 21b is a right side wall of the groove, 22 is an arc, 23 is a shielding gas, and 24 is a control gas. Patent applicant: Nippon Sharyo Manufacturing Co., Ltd. Figure 1 (0)

Claims (1)

[Claims] 1. Generating an arc between the welding wire and the workpiece,
In gas-shielded metal arc welding, which is performed by ejecting a shielding gas such as argon or carbon dioxide around the welding part, in addition to the above-mentioned shielding gas, a control gas having a different potential gradient from the shielding gas is added to the left side in the direction of travel of the welding torch. A method for oscillating an arc in gas-shielded metal arc welding, characterized in that the arc is oscillated in the width direction of a groove of a workpiece by ejecting alternately from the right side near the arc. 2. In a welding device for gas-shielded metal arc welding, which is performed while jetting shielding gas around the welding part of the groove of the workpiece, in addition to the above-mentioned shielding gas, a control gas having a potential gradient different from that of the shielding gas is used to control the progress of the welding torch. In order to oscillate the arc in the width direction of the groove by ejecting it alternately from the left and right sides of the welding torch toward the vicinity of the arc, we have control that communicates with the left and right sides of the welding torch, respectively, near the contact tip at the tip of the welding torch. An arc oscillation device for gas-shielded metal arc welding, characterized in that a gas flow path is provided in a welding torch body.