JPS59107772A - Method for preventing magnetic blow of welding arc - Google Patents

Abstract

PURPOSE:To prevent the magnetic blow of an arc and the generation of weld defects by detecting the generation of the magnetism by the arc during welding with a magnetic detector disposed in the groove part at the end faces of materials to be arc welded, operating an electromagnet and negating the magnetism. CONSTITUTION:A welding wire 2 is inserted into the groove 1' formed by objects 1a, 1b to be welded, and an arc 3 is generated from the tip of the wire 2. When welding progresses in an arrow direction, a magnetic line of force 3' is generated in an arrow direction of a solid line near the end A of the objects 1a, 1b and the arc 3 at the tip of the wire 2. The line 3' is detected with a magnetic detector 4 and is enlarged with an amplifier 6. The polarity of the signal thereof is discriminated by a polarity discriminator 7. The output signal enlarged by an output amplifier 8 is supplied to an electromagnet 5 which is so operated as to negate the line 3' in the groove at the plate end A.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing magnetic blowing of plate edges in arc welding, and is particularly concerned with the method of preventing magnetic blowing of plate edges in arc welding.
Effective for arc welding.

Conventionally, narrow gap MAG arc welding is performed as shown in Figure 1.
The welding wire 2 is inserted into the groove 1'' in which the objects to be welded 1allb are arranged in one shape, power is supplied to the welding wire 2 and the objects to be welded 1a+1b' from a welding power source (not shown), and shielding gas is supplied from a gas nozzle (not shown). was supplied to generate arc 3 and perform welding.

In welding using this method, as the welding progresses and approaches the edge of the plate, magnetic blowing of the arc occurs, making the welding unstable and potentially causing welding defects.

That is, to explain this with reference to FIG. 2, which is a partially cut-out version of FIG.
Assuming that a welding arc 3 is generated within the groove 1, which is made up of grooves 1 and 1b, and welding progresses from the A end to the B end of the workpiece la, 1b, when the welding wire 2 approaches the B end, the arc 3 is deflected in the direction of the arrow.

As shown in FIG. 2, a welding current 1 flows from the welding wire 2 through an arc 3 to the objects to be welded 1a, lb.
The flow shall be as follows. In this case, clockwise lines of magnetic force are generated concentrically around the welding wire 2 due to the "right-handed" law. However, as shown in Fig. 3, when welding surrounded by a groove in the steel material, especially near the plate edge, when approaching the B edge, the magnetic field lines 3' generated by the welding wire 2 are dense on the B edge side, and are dense on the A edge side. It becomes sparse on the side and occurs in the direction of the arrow attached to the magnetic field lines 3''.

In the case of such a magnetic field line arrangement, near the arc 3, magnetic field lines are generated that go from the side tip surface of the workpiece 1b to the groove surface on the 1a side, and the arc 3 moves in the direction shown by arrow P in Fig. 2. deflected to This phenomenon occurred regardless of the direction of the current flowing through the welding wire 2 and whether it was direct current or alternating current.The closer the welding wire was to the edge of the workpiece, the stronger the arc acted on it, making welding unstable and causing welding defects. .

The present invention proposes a method for preventing magnetic blowing at the edge of a plate that can solve this problem, and also involves arranging a magnetic detector and an electromagnet at the bevel on the end face of a plate to be arc welded, thereby preventing the generation of magnetism by the arc during welding. The present invention provides a method for preventing welding arc magnetic blowing, which is characterized in that the magnetism is detected by the detector and the electromagnet is operated to cancel the magnetism.

In the method of the present invention, current is passed through the electromagnet so as to cancel out the lines of magnetic force detected at the edge of the plate, and the magnetic force acting on the arc is reduced to zero, thereby preventing magnetic blowing at the edge of the plate and obtaining a sound weld. I can do it.

An embodiment of the method of the present invention will be described in detail below with reference to FIGS. 4 and 5.

1allb is a workpiece to be welded, and a welding wire 2 is inserted into a groove 1' formed by the workpieces 1a and 1b. 3 is a welding arc generated from the tip of the welding wire 2 within the groove, and 4 is a groove 1' at the plate end of the workpiece 1a+1b.
A magnetic detector inserted into the workpiece 1allbO
A magnetism canceling electromagnet is placed at the end of the plate together with the magnetic detector 4; 6 is an amplifier for magnifying the signal detected by the magnetic detector 4; and 7 is a polarity discriminator 8 for the detected signal that operates the electromagnet 5. This is an output amplifier.

When welding progresses in the direction shown by the arrow in FIG. 4, as described above, near the A end of the workpiece 1allb and the arc 3 at the tip of the welding wire 2 shown in FIG. 5, lines of magnetic force flow in the direction of the solid arrow. It has occurred. These lines of magnetic force are detected by magnetic detector 4.
The polarity of the signal is discriminated by a polarity discriminator 7, and then the output signal magnified by an output amplifier 8 is supplied to the electromagnet 5, and the output signal of the workpieces 1a, lb is It operates to cancel the lines of magnetic force within the groove of the plate end A.

As described above, in the method of this invention, a detector detects the magnetic lines of force generated by the current flowing through the welding wire itself, and the current is passed in the opposite direction to the electromagnet placed at the edge of the plate, thereby constantly reducing the magnetic force generated at the edge of the plate to zero. This has the effect of preventing magnetic blowing of the arc and preventing welding defects from occurring.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a conventional narrow gap welding situation, FIG. 2 is a side view of the same as above, FIG. FIG. 5 is a perspective view showing an embodiment when applied to narrow gap welding, and FIG. 5 is a schematic diagram of the same device. Iallb: object to be welded, 1°: groove, 3: arc. 3°: magnetic field lines, 4: magnetic detector, 5: electromagnet.

Claims (1)

[Claims] A magnetic detector and an electromagnet are arranged at the end face groove of the plate material to be arc welded, the detector detects magnetism generated by the arc during welding, and the electromagnet is operated to cancel the magnetism. Welding arc magnetic blow prevention method.