JPS583791A - Welding method of copper or copper alloy - Google Patents

Abstract

PURPOSE:To obstruct generation of a welding defect, and to form a satisfactory bead, by setting a non-consumable electrode and a consumable electrode as a preceding electrode and a succeeding electrode, respectively, and combining them at a suitable distance. CONSTITUTION:A currents supplied from a welding electric power supply 7 to non-consumable electrodes 2, 2' being preceding electrodes of a welding torch, and a suceeding consumable electrode 4, arcs are generated between them and a material to be welded 1, and welding is executed. To the electrode 4, a wire 5 is fed by a device 13. When a distance between the electrodes 2, 2' and 4 is large, a local heating effect of the preceding electrode is decreased and an incompletely fused overlap bead is generated, therefore, a distance between the electrodes is set to <= about 7mm. at a point where the center line of each electrode contacts with a base metal 1. In this regard, a welding current is supplied to each electrode alternately by switching elements 8, 8' and 9, 9' in order to prevent interference of an arc, and these elements are controlled by a device 12. Also, in order to stabilize an arc of the non-consumable electrode, a high frequency superposing device 11 and arc stabilizing resistances 10, 10' of the consumable electrode are connected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a welding method for copper or copper alloys, and in particular to a method for welding copper or copper alloys, which can obtain a good welded joint without causing welding defects such as poor fusion or overlap beads. Concerning a method of welding alloys.

Traditionally, copper or copper alloys have a thermal conductivity of 5 compared to mild steel etc.
~8 times or more, the heat dissipates quickly, making it difficult for the material to be welded to melt.Also, the solidification rate of the molten metal is also fast, resulting in extremely poor wetting of the molten metal, resulting in blowholes, overlaps, etc. This causes welding defects such as poor fusion. Therefore, welding is performed by preheating the welded part to 500 to 800C using a burner or the like.

In this way, welding while preheating at a high level requires a great deal of labor, and the working environment is also poor, which hinders the automation of welding.

An object of the present invention is to provide a method for welding copper and copper alloys, which allows good welding results to be obtained without preheating the copper or copper alloys, and which enables automatic welding.

The present invention has confirmed through experiments that by combining a non-consumable electrode and a consumable electrode, it is possible to freely control the welding input while keeping the amount of welding constant. By performing welding while maintaining the spacing between the non-consumable electrode and the consumable electrode at a distance that does not cause Doparap unfused beads, welding defects can be prevented and beads can be formed well.

FIG. 1 shows the relationship between welding input and wire feed speed in the present invention method combining a non-consumable electrode and a consumable electrode and the conventional MIG welding method. The welding current of the consumable electrode is 200A. The wire is MG990 (1.6φ). In the MIG method, the wire feeding speed increases as the welding input increases. Therefore, the welding input is used to melt the wire, and it is not possible to provide enough energy to melt the material to be welded.In contrast, in the method of the present invention, the welding current of the consumable electrode is kept constant;
Since the welding current of the non-consumable electrode can be varied, as shown in the figure, the welding input can be changed significantly with the wire feeding speed, ie, the amount of welding fixed, being constant. This shows that non-consumable electrodes can be used to locally heat and suppress heat dissipation. Therefore, as shown in Fig. 2, local heating may be performed using the non-consumable electrode 2 as the leading electrode, and the following consumable electrode 4 may be used to generate an arc 6 between the wire 5 and the workpiece 1 for welding. I understand that. However, the distance t1 between the non-consumable electrode 2 and the consumable electrode 4, that is, the distance f11 between the point where the extension of the center line of both electrodes touches the workpiece 1
If is large, the leading local heating effect on the trailing electrode will be reduced, resulting in an overlap fusion failure peak.
The distance between the electrodes varies depending on the current value, but is preferably 7 or less. FIG. 3(a) shows the relationship between the interelectrode distance and the penetration cross-sectional area. The consumable electrode welding current is 350A.

FIG. 3(b) is a diagram showing the cross-sectional area of penetration. As the distance between the electrodes increases, the cross-sectional area of penetration decreases, and when the distance is 7 mm or more, an overlapping bead that is not penetrated into the base metal will occur.Therefore, it is necessary to further consider the welding conditions. It is preferable that the distance be 7 degrees or less.

FIG. 4 shows a configuration diagram of an apparatus according to an embodiment of the present invention.

The welding torch is composed of a leading non-consumable electrode 2.2' and a trailing consumable electrode 4, each of which is supplied with current from a welding power source 7, creating an arc 3.6 between it and the workpiece 1. generated and welded. The consumable electrode 4 has a wire feeding device 1
3 feeds the wire 5.

The welding current is passed through the switching element 8 to prevent arc interference. E,' and 9.9' are configured to alternately supply each electrode. Further, these elements are controlled by a control device 12. Furthermore, in order to stabilize the arc of the non-consumable electrode, a high frequency superimposing device 11 and an arc stabilizing resistor 10° 10' of the consumable electrode are connected. When welded a copper plate with a thickness of 10+a+ using this device, a very good weld was obtained without any welding defects such as blowholes or overlaps, even without preheating. The welding conditions were: non-consumable electrode: 350A, consumable electrode: 20OA.

Interelectrode distance: 1.5cm, welding speed: 200cm/min
.

Switching frequency: 200Hz, shielding gas is Ar.

MG990 (1.6φ) for steel welding was used as the wire. FIG. 5 shows microscopic photographs of the cross sections of peas obtained by the conventional MIG method (a) and the method of the present invention (b). In the method of the present invention, the bead shape is smooth and sufficient penetration is obtained. As described above, if the method of the present invention is used, there is no need for preheating using a burner or the like, so the efficiency of overlapped welding is improved. Also, it can be easily automated. In the conventional method using the same welding current, poor penetration occurred as shown in the figure.

As described above, according to the method of the present invention, an excellent 7'C weld with a smooth bead surface and sufficient penetration was obtained. Welding efficiency was also significantly improved.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between welding input and wire feeding speed, Figure 2 is a diagram showing the arrangement of each electrode in the method of the present invention, and Figure 3 is a diagram showing the relationship between the distance between electrodes and the cross-sectional area of penetration. 4 is a block diagram of an example of an apparatus for carrying out the method of the present invention, and FIG. 5 is a microscopic photograph of a cross section of a weld bead welded by the conventional MIG method and the method of the present invention. 1... Material to be welded, 2.2'... Non-consumable electrode, 3...
- Non-consumable electrode arc, 4... Consumable electrode, 5... Wire, 6... Consumable electrode arc, 7... Welding power source, 8.
8', 9°9'... switching element, 10...
Arc stabilizing resistance, 11... High frequency superimposition device, 12...
- Control device, 13... wire feeding device.

Claims (1)

[Claims] 1. A method of performing arc welding by alternately supplying a welding current to a non-consumable electrode and a consumable electrode, wherein the leading electrode is a non-consumable electrode, the trailing electrode is a consumable electrode, and the non-consumable electrode A method for welding copper or copper alloys, characterized in that welding is performed while maintaining a distance between a consumable electrode and a consumable electrode at a distance that does not cause overlapping and poorly fused beads. 2. A copper wire according to claim 1, characterized in that the distance between the non-consumable electrode and the consumable electrode is 7 or less at the point where the center line of each electrode touches the material to be welded. How to weld copper alloys. 3. A method for welding copper or copper alloy according to claim 1 or 2, in which the material to be welded is melted by a leading electrode.