JPS6048271B2 - Arc welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an arc welding method in which welding is performed while feeding an energized wire into an arc.

[Background of the invention]

When welding while feeding a wire into the arc using a non-consumable electrode arc such as a TIG arc or plasma arc, the torch should be tilted slightly (approximately 5 to 20 degrees) in the welding direction to take advantage of the preheating effect. Therefore, there is a method of welding by feeding the wire from the front of the arc.

However, in this case, especially in the high-speed region,
Due to the tilt of the torch, shielding is insufficient and the welding heat is prone to defects such as proholes. In addition, the wire welding speed is low, and there is a limit to how high the speed can be increased. On the other hand, for welding that requires higher speed and higher welding, it is effective to use a method in which the wire fed into the workpiece is also energized.

In order to stabilize the arc generated by the wire and the droplet transfer, the power supply is generally maintained by passing current between the wire and a non-consumable electrode. (occurs significantly). Ding wire is
It is fed into the arc from the front in the direction of welding progress.

In this case, magnetic blowing of the arc occurs due to the interaction of the magnetic field generated by the wire energization, and the arc bends in a direction opposite to the welding direction, ie, backward. Furthermore, since the wire is fed from the front, the weld metal is swept backward, causing the molten pool to retreat. As a result, there is a shortage of molten metal at the tip of the molten pool, making welding unstable, gas entrainment, and welding defects such as undercuts. In addition, there were disadvantages such as the receding of the molten pool was not noticeable, the shielding was lowered, and proholes were more likely to occur due to the entrainment of the atmosphere. [Object of the Invention] In view of the above-mentioned problems, an object of the present invention is to provide an arc welding method that can perform good welding with a stable molten pool by utilizing the features of conventional arc welding using wire current without impairing it. With the goal.

[Summary of the invention]

The present invention involves passing an arc current through a non-consumable electrode as a negative electrode and a material to be welded as a positive electrode, and feeding a current-carrying wire into the arc generated between the negative non-consumable electrode and the positive material to be welded. In the arc welding method, a DC power source with the polarity matched so that the non-consumable electrode side is negative is connected between the wire and the non-consumable electrode, and the wire is fed into the arc from behind as welding progresses. When feeding, electricity is applied between the wire and the non-consumable electrode so that the wire becomes the positive electrode, and the mutual repulsion of the magnetic field due to this energization is used to deflect the arc in the welding direction, and this deflection is controlled by the wire current value, and welding is performed while preheating the material to be welded and advancing the molten pool.

[Embodiments of the invention]

Figure 1 shows that the wire is fed from the outside of the torch during arcing,
This shows the principle of magnetic blowing that occurs when the wire is also energized.

An arc current (plasma current) flows between the electrode of the plasma torch 1 and the workpiece 2 in the direction of the arrow.

On the other hand, a current (wire current) also flows in the wire 3 in the direction of the arrow. Magnetic lines of force are formed in the direction shown in the figure from the current circuit due to energization, and the interaction of this magnetic field causes a magnetic blow in the direction that repels the wire 3, and the arc 4 is bent as shown in the figure. The larger the current Iw flowing through the wire,
Conversely, the smaller the plasma current Ip is, the more strongly the plasma arc 4 is bent due to the repulsive action. Of course, if you change the power supply connection and make the wire current flow in the opposite direction,
Needless to say, the plasma arc bends in the direction of the wire due to the suction effect. 4. In this case, wire transfer is unstable and spatter is likely to occur, which is undesirable.

Figure 2 shows an example of applying this method to welding based on the knowledge of this phenomenon. In this example of welding a joint with a groove, the wire 3 is fed from behind the plasma arc 4 in the direction of welding progress, and the wire 3 is connected to the positive electrode between the wire 3 and the non-consumable electrode in the torch. Welding is performed while deflecting the plasma arc 4 in the welding progress direction by applying current so that the plasma arc 4 is deflected in the welding direction. Note that 5 and 6 are DC power supplies. The wire 3 moves in the same direction as the welding progress direction, the weld metal is swept forward, and the molten pool leads forward, and
In addition to the preheating effect of the workpiece 2 due to the deflection of the arc 4, the molten pool becomes extremely stable and good welding can be performed.

According to this experiment, the depth of a mild steel material with a plate thickness of 97-Wl is 4wL.
(7) When welding a U groove at a welding speed of 400 wm/Min, plasma gas (Ar) 1.51/Min) plasma arc current 200 A) wire current 150 A) wire feeding speed approximately 8 m/Min (1. 2φ), good results were obtained with no welding defects. At this time, it was observed that the plasma arc 4 was deflected by about 20 degrees in the direction of welding progress. The deflection of the plasma arc 4 is determined by the mutual relationship between the plasma arc 4 and the magnetic field when a current is passed through the material to be welded, but for simplicity, it is better to control the deflection mainly using the wire current value.

Needless to say, the wire 3 can be transferred in a plasma arc, and welding can be performed while the droplet is transferred and the wire is brought into contact with the molten pool.

[Effects of the Invention] As described above, according to the present invention, when the wire is fed into the arc from behind in the direction of welding progress, the wire becomes the positive electrode between the wire and the non-consumable electrode. Since the current is energized, the electromagnetic force of the arc and the fluidity of the molten metal can be actively utilized, allowing the deflection of the plasma arc to preheat the material to be welded and the movement of the wire to advance the molten pool. Therefore, a stable molten pool is formed and good welding results can be obtained.

Furthermore, by controlling this wire current, not only can the amount of deflection of the plasma arc be easily controlled without using an electromagnetic device, but also the wire can be melted smoothly without the occurrence of spatter. Further, according to the present invention, since the amount of wire welded is large, the groove portion of the welded material can be efficiently welded, and the welding time can be shortened.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention, and FIG. 2 is a diagram showing an embodiment of the present invention. 1... Plasma torch, 2... Material to be welded, 3... Wire, 5, 6... DC power supply.

Claims (1)

[Claims] 1 An arc in which an arc current is passed with the non-consumable electrode as the negative electrode and the material to be welded as the positive electrode, and a current-carrying wire is fed into the arc generated between the non-consumable electrode as the negative electrode and the material as the positive electrode for welding. In the welding method, a DC power source with the polarity matched so that the non-consumable electrode side is negative is connected between the wire and the non-consumable electrode, and the wire is fed into the arc from behind in the direction of welding progress. Sometimes, an electric current is applied between the wire and a non-consumable electrode so that the wire becomes the positive electrode, and the mutual repulsion of the magnetic field due to this electric current is used to deflect the arc in the direction of welding progress, and this deflection is reflected by the wire current. An arc welding method characterized by performing welding while preheating the material to be welded and advancing the molten pool by controlling the value.