JPH02147169A - Plasma mig welding method - Google Patents

Abstract

PURPOSE:To change an arc intensity distribution by changing one at least of a position and an angle of a MIG are in a plasma arc. CONSTITUTION:At the time of starting an arc, a pilot arc is generated between a plasma electrode 10 and a plasma chip 11 and the plasma arc 18 is generated between base metals 17 with this as assistant. A MIG welding wire 16 is fed from a MIG electrode 15 to generate the MIG arc 19. While the MIG electrode 15 moving and changing an angle in an insulating cylinder 14 of the inside of the plasma electrode 10, welding is performed. The MIG arc 19 is moved to the outside of the plasma arc 18 and arc intensity of an end is increased. Since the torch height is not changed even in a narrow gap by changing an intensity distribution of the arc, the same effect as in the case of weaving being carried out is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a plasma MIG welding method that utilizes a combined arc of plasma and MIG.

(Prior Art) Plasma arc welding and MIG welding are known as conventional welding methods. In plasma arc welding, high-density heat is generated by an arc having a mechanically and electrically focused plasma column, and welding is performed using this heat. Furthermore, MIG welding is a type of inert gas arc welding, and is welding using a welding wire as an electrode. This MIG welding
The welding wire itself becomes a consumable electrode and welds, and since it is carried out in an inert gas, it is possible to weld dithane and zirconium, which cannot be welded in the atmosphere.

In recent years, plasma MIG welding, which is a combination of plasma arc welding and MIG welding, has been proposed. The plasma MIG welding method involves starting from the center of a hollow plasma electrode.
A method is known in which a consumable MIG welding wire is fed in the axial direction to generate a MIG arc in the center of the plasma arc (see Japanese Patent Publication No. 59-5067).

(Problem to be Solved by the Invention) The spread of the MIG arc generated in a plasma arc is restricted, and even if the arc length is extended, the arc does not spread significantly like the MIG arc of a living body. A conventional plasma MIG arc has a MIGff on the central axis of the plasma electrode.
Due to the structure in which the f-pole is provided, looking at the arc intensity distribution, the central part is stronger due to the MIG arc, and the surrounding area is covered by the plasma arc. Further, the molten metal from the MIG welding wire A7 passes through the MIG arc and transfers into droplets to the base metal side. That is, the droplet transfers from the center of the plasma arc.

When welding materials with poor thermal conductivity using plasma MIG welding, almost the entire surface of the area hit by the plasma arc tends to become molten or wet, and even if droplets migrate from the center of the plasma arc, the plasma arc Molten metal that has migrated widely to the surface it hits tends to spread. Also,
Even if the surface of the base metal is not necessarily molten or wetted by the plasma arc, if the high-temperature molten metal transferred as droplets overlaps, the heat of this molten metal can melt the lapped surface with the base metal. .

However, in the case of materials with good thermal conductivity such as aluminum and copper, as shown in FIG. The molten pool separates from the part near the torch and near the bottom of the MIG arc 3. For this reason, the transferred droplets from MIG welding white T74 do not weld to the molten part 5 of the groove wall, and the transferred weld metal 6 becomes a convex bead, which causes a welding defect when the welding of the next bus is repeated. There is a risk that it will happen.

In order to prevent this, conventional methods have been used such as increasing the groove angle to avoid a large separation of the molten pool, or shifting the torch position so that the MIG arc 3 hits the recessed portion 2a. The former method has the disadvantage that the groove becomes large and the amount of welding increases.

In addition, the latter method requires a higher torch height. That is, the arc length becomes longer than necessary, resulting in disadvantages such as poor shielding.

The present invention was developed in consideration of the above circumstances, and is a plasma MIG welding method that allows high-quality welding even on materials with good thermal conductivity without enlarging the groove or making the arc length longer than necessary. The purpose is to provide

[Structure of the invention]

(Means for Solving the Problems) A plasma MIG welding method according to the present invention is a plasma MIG welding method in which welding is performed by generating a MIG arc in a plasma arc, in which at least one of the position and angle of the MIG arc is changed in the plasma arc. This changes the intensity distribution of the arc.

(Function) By shifting the position and angle of the MIG arc in the plasma arc, the intensity distribution of the arc can be changed.
Even in a narrow groove, the same effect as weaving can be obtained without changing the torch height.

(Example) An embodiment of the present invention will be described with reference to FIG.

In FIG. 1, the plasma MIG welding torch has a plasma electrode 10 and a plasma chip 11 held through an insulating tube 12, and an outer tube 13 provided outside the plasma depth 11. The inside of the plasma electrode 10 is electrically insulated by an insulating tube 14, and inside this insulating tube 14 is a MIG electrode 15 which can move forward and backward and left and right in FIG. 1 and can freely change its angle.
is provided. A MIG welding wire 1716 is provided within the MIG electrode 15 and fed through the interior thereof.

In the plasma MIG welding torch configured as described above, when the arc star 1 is applied, a pilot arc is generated between the plasma electrode 10 and the plasma tip 11, and a plasma arc 18 is generated between the plasma core pole 10 and the base metal 17, which are located at a good distance.
To assist in generation. When a plasma arc 18 is generated between the plasma electrode 10 and the base material 17, the invasive pilot arc may or may not be cut electrically. In this case, the plasma electrode 10 and the plasma chip 11 are electrically insulated by the insulating cylinder 12.

When the plasma arc 18 is generated, the MIG welding wire 16 is fed from the MIG electrode 15, and a voltage is applied between the MIG electrode 15 and the base metal 17.
MiG Arc 19 is generated inside. These arcs18.
A shielding gas 20 is supplied from between the outer fli 13 and the plasma chip 11 to prevent oxidation of the base material 17 heated and melted by the plasma chip 19 . The MIG electrode 15 is moved in the space inside the insulating tube 14 provided inside the plasma electrode 10 by a moving device (not shown) back and forth or left and right as shown in FIG. 1, or while changing the angle. Perform welding.

In this way, the plasma electrode 10 with a space formed inside
The MIG electrode 15 may move back and forth, left or right, or the MIG electrode 1
Since welding can be performed while changing the angle by 50 degrees, it is possible to bring the A MIG arc 19 closer to the outside of the plasma arc 18 and increase the arc strength at the end of the plasma arc 18, thus widening the range of influence of the MIG arc 19. By changing the intensity distribution of the arc, the same effect as weaving can be obtained without changing the torch height even in a narrow groove.

〔Effect of the invention〕

The plasma MIG welding method according to the present invention changes the intensity distribution of the arc by avoiding changes in at least one of the position d and angle of the MIG arc in the plasma arc, so the torch height can be changed even in a narrow groove. The same effect as weaving can be obtained without the need for weaving.

[Brief explanation of the drawing]

FIG. 1 shows a plasma MIG welding torch used in an embodiment of the plasma MIG welding method according to the present invention;
FIG. 2 is a sectional view showing a welded state when materials with good thermal conductivity are welded by the conventional plasma MIG welding method. 10... Plasma electrode, 11... Plasma chip,
15... MIG electrode, 16... MIG welding wire, 17
... Base material, 18... Plasma arc, 19... MIG arc, 20... Shielding gas. , 庬 2 Figure 1

Claims (1)

[Claims] A plasma MIG welding method in which welding is performed by generating a MIG arc in a plasma arc, characterized in that the intensity distribution of the arc is changed by changing at least one of the position and angle of the MIG arc in the plasma arc. Method.