JPH0214149B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of welding using a combination of TIG arc and MIG arc. The present inventor considered the efficiency of Teig arc welding and its application to surface overlay welding, and in research to explore the possibility of composite arc welding that combines Teig arc welding with pure argon MIG arc welding, we conducted research on pure argon MIG arc welding under short-circuit transition conditions. When the Teig arc was brought close to the arc, the droplets migrated into globules, and we confirmed that a MIG arc with no spatter was obtained.We also observed the arc phenomenon when a magnetic field was applied while keeping the distance between the electrodes appropriate. As a result of studying the effects on bead formation, we were able to obtain excellent beads with a stable arc under the required conditions. The present invention is based on this knowledge, and includes:
The electrodes of the leading MIG-arc welding torch and the Teigu-arc welding torch that follows it are directed to approximately the same part on the base metal, and a magnetic field is applied to the welded area by both torches. This method is characterized by suppressing arc repulsion, etc., and performing welding while correcting the MIG arc in the wire feeding direction. The present invention will be explained in more detail below with reference to the drawings. In the composite welding method of the present invention, as shown in FIG. 1, when performing welding along a required weld line on the base material 1, the MIG arc welding torch 2 is placed in advance, and the Teigue arc welding torch 3 is placed in front of it. Follow and move. The above MIG arc welding torch 2 is
The welding wire 4 is used as an electrode, and while a shielding gas such as argon is flowing from the flow path 5 around the welding wire 4, the power source 6 is turned on.
Arc welding is performed using a welding current from In addition, the Teigue arc welding torch 3 is
Arc welding is performed using a tungsten electrode 7 and a welding current from a power source 9 while flowing a shielding gas such as argon from a flow path 8 around the electrode. The electrodes of these torches 2 and 3 are directed to substantially the same part on the base material 1, and the distance between the electrodes is maintained appropriately as described later.
As shown in the figure, a magnetic field by permanent magnets 11, 12, etc. is applied to the generated composite arc 10, and the MIG arc and Teig arc repulsion are mainly corrected by the magnetic field in the wire feeding direction. In addition, in the figure, 13 indicates a weld bead. According to such composite welding, excellent bead welding can be performed using a stable arc that does not generate any spatter, unlike pure argon MIG arc welding, where the cathode spot on the base metal side moves and there are many spatters under unstable conditions. In particular, the welding current for Teig arc welding is 200A, and the welding current for Migu arc welding is 200A.
When the current is 100 A, an excellent bead can be obtained when the distance between the electrodes is approximately 10 mm and the magnetic flux density is approximately 15 to 20 Gauss. Next, an experimental example regarding composite welding of the present invention will be explained. In this experiment, as shown in FIG. 1, bead placement welding was performed by placing a MIG arc welding torch 2 in advance and forming a bead with a Teigue arc welding torch 3. As the MIG arc welding power source 6, a thyristor type constant voltage characteristic power source was used, and as the Teigue arc welding power source 9, a silicon rectification type droop characteristic power source was used.
Table 1 shows the basic welding conditions.

【table】

[Table] In pure argon arc welding using only the MIG arc welding torch 2 at an average current of 100 A and an arc voltage of 20 V, the number of short circuits was 10 to 15 per second, the arc was unstable, and spatter occurred. Furthermore, when both Teig arc welding and MiG arc welding torches 2 and 3 were used and the distance between the electrodes was 10 mm, the droplet transfer was 1.5 times per second, leaving a slight short circuit. However, when a magnetic field of 20 Gauss was applied to it, there was no short circuit and no spatter occurred. According to these experiments, when the Teig arc is brought close to the Mig arc, the Mig arc crawls up, and the repulsion on the Mig arc side is large even in the absence of a magnetic field. This arc interference is caused by the large welding current ratio (TEIG welding current/MIG welding current).
This is thought to be due to the actual arc length becoming longer due to the MIG arc creeping up. On the other hand,
By applying a magnetic field with a magnetic flux density of 20 Gauss, the MIG arc was corrected in the wire feeding direction, and a suitable composite arc could be obtained. We also investigated the relationship between the bead shape and conditions such as the distance between the electrodes and the applied magnetic flux density, and found that as the distance between the electrodes increased, the bead width decreased. This is due to the cooling effect of the MIG weld metal.
In addition, when a magnetic field is applied, the Teig arc and Mig arc become a suitable composite arc, which prevents the bead from cooling, and the distance between the electrodes is 10 mm, 18~20 Gauss
I was able to obtain excellent beads. As shown in FIG. 3, the bead width reaches its maximum at 15 to 20 Gauss, and when it exceeds 20 Gauss, the bead width rapidly decreases and the excess buildup increases, making it difficult to form a normal bead. This is because the heat of the MIG arc is not effectively applied to the base metal because the MIG arc is attracted to the Teig arc side. The penetration showed a flat shape or a slightly deep peripheral penetration shape on both sides. This penetration shape is effective when applied to overlay welding. In addition, as shown in Figure 4, the amount of wear of the tungsten electrode is 0.5 to 0.5 at a magnetic flux density of 15 to 20 Gauss.
The consumption rate is 1.0 mg/min, which is comparable to the consumption amount in the conventional cold wire method. As a result of welding by changing the welding current and arc voltage of MIG arc welding with the Teig arc welding current of 300A, the MIG arc welding current was 100A.
At MIG current of 140A and 120A, an excellent bead with a wide bead width and low excess thickness was obtained.
When the welding speed exceeded 30 g/min, irregularities on the bead surface and uneven toes occurred. However, it was possible to obtain a welding speed approximately twice that of the conventional cold wire method.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus for performing composite welding according to the present invention, FIG. 2 is a plan view of the main parts thereof, and FIGS. 3 and 4 are graphs showing experimental results. 1... Base material, 2... MIG arc welding torch,
3... Teigu arc welding torch, 10... Composite arc.

Claims (1)

[Claims] 1 The electrodes of the leading MIG arc welding torch and the Teigue arc welding torch that follows,
The MIG arc is corrected in the wire feeding direction by applying a magnetic field to the welded part by both torches by directing them to approximately the same part on the base material, and suppressing the repulsion of the arc by both torches due to the magnitude of the magnetic flux density. This is a Teig-Arc/Mig-Arc combined welding method that is characterized by welding while welding.