JPS61293673A - Magnetic stirring welding method - Google Patents

Abstract

PURPOSE:To avoid the changeover of the normal and reverse rotation in a magnetic stirring on the gap of a welding material and to obtain a good penetration bead by chnchronizing the oscillating of a welding torch or welding material and the direction of the magnetic field. CONSTITUTION:The welding torch performs a welding with moving in the regular order of A O B O A by an oscillating device. On the other hand an oscillating position detector 8 detects the moving position of the welding torch 1 and transmits it to an alternating current generater 7. And in case of the welding torch 1 being under moving on A B the exciting power source 16 in normal direction is outputted and the molten metal is rotated in the arrow mark continuous line direction inside a molten pool 13. In case of B A similarly the molten metal inside the molten metal 13 is rotated in the arrow mark dot line direction and the burn through of the welding metal is eliminated without suspending the rotation of the molten metal while the welding torch 1 is moving on the gap G of the center O of the welding groove.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improvement in a magnetic stirring welding method, and particularly to a magnetic stirring welding method that can easily obtain a good uranami bead.

(Prior Art) Conventionally, single-sided welding is often used in joint welding of steel plates, steel pipes, etc., but it is necessary to obtain a good under-wave bead in the first layer welding. Therefore, efforts are being made to improve welding methods, create welding grooves, and manage welding conditions. However, in any of the above welding methods, the range of appropriate welding conditions for obtaining a good Uranami bead is narrow, and the current situation is that a stable and good Uranami bead cannot be obtained.

An example of joint welding of steel plates by a conventional method is shown in FIGS. 5, 6, 7, and 8.

FIG. 5 shows a conventional TrG welding method. In the figure, 1 is TI
G welding torch, 2 indicates a material to be welded, and 3 indicates a tungsten electrode. This T-G welding method is a method in which the groove portion of the welded material 2 is t-S melted by arc heat generated between the tungsten electrode 3 and the welded material 2 to obtain an underwave bead. However, although such a TIG welding method can obtain a good Uranami bead, it has the following drawbacks.

(1) Welding groove processing costs are high. (Processing accuracy is required.) (2) It is necessary that the grooves are in close contact.

Figure 6 shows the commonly used oscillating T welding method, where 1 is the T welding torch, 2 is the material to be welded, 3 is the tungsten electrode, 4 is the filler rod, and the arrow 5 is the TIG welding method. The left and right oscillation directions of the welding torch 1 are shown. In this oscillating T-type G welding method, molten metal is produced while feeding a filler rod 4 into an arc generated between a tungsten electrode 3 and a workpiece 2, and the welding torch 1 is moved from side to side periodically. This is a method of welding while oscillating, but it has the following drawbacks.

(1) Allowable groove width is narrow.

(2) Since the range of appropriate welding conditions is narrow, it is difficult to obtain a stable Uranami bead.

Note that (&) and (b) in FIG. 7 show an example of a typical groove shape of the oscillated T-type G welding method.

FIG. 8 shows an example of the magnetic stirring TIG welding method. In the figure,
6 is a magnetic field generating coil, 7 is an alternating current generating power supply that supplies the coil, 1 is a TIG welding torch, 3 is a tungsten electrode, 4 is a filler rod, 2 is a workpiece to be welded, 5 is the left and right side of a TIG welding torch Indicates the oscillation direction.

This magnetically stirred GIW welding method is a method of obtaining molten metal while feeding a filler rod 4 into an arc generated between a tungsten electrode 3 and a workpiece 2 to be welded. Then, when an alternating current is passed through the magnetic field generating coil 6 provided in the TIG welding torch 1,
An alternating magnetic field is generated and the molten metal is stirred by the force generated by the alternating magnetic field and the arc current.

Therefore, the welding progresses from the surface under stirring.

Note that the welding torch 1 advances the welding while moving straight or oscillating from side to side to obtain an underwave bead.

According to this welding method, the drawbacks of the welding method shown in FIGS.
(2) The disadvantages of Uranami beads, such as occasional drop-off and irregular bead surface appearance and dents, have not been resolved yet.

Furthermore, FIGS. 9 and 10 show principle diagrams of welding conditions by the conventional magnetic stirring TIG welding method.

In FIG. 9(a), a welding current 12 flowing from the tungsten electrode 3 into the molten pool 13 flows radially within the molten pool 15 and the welded material 2. In FIG. To this, T-worker G welding torch 1
When a magnetic field 11 perpendicular to the workpiece 2 is applied by the magnetic field generating coil 6 installed at the tip of the welding current 12 and the magnetic field 1
1, as shown in FIG. 9-(b), a Lorentz force 14 is generated and the molten pool 13 begins to rotate in one direction. By making the magnetic field 11 a low-frequency alternating magnetic field, a reversal force can be periodically applied to the molten pool 13. Therefore, the molten metal in the molten pool 15 periodically
While being stirred in the opposite direction, it solidifies regularly as welding progresses. In addition, in FIG. 9, 7 indicates an alternating current generator, and 4 indicates a filler rod.

FIG. 10 shows a partially enlarged view of the vicinity of the molten pool 13 in FIG. 9. The molten pool 16 is almost horizontal, and inside the molten pool 15,
Lorentz force 14 acts to stir in the forward and reverse directions. Note that 10 indicates a weld bead. Therefore, due to the action of the magnetic field, horizontal rotational force is generated in the molten metal in the molten pool 13, which acts as a horizontal component force, reduces the gravity in the vertical direction, and also reduces the arc force acting in the vertical direction. This prevents the product from falling or dripping.

However, the fact that the molten metal is stirred in the forward and reverse directions by low frequency means that the molten metal is temporarily stopped during the forward and reverse directions. This stop should occur twice in one cycle. That is, it shows that there are two times in one cycle of magnetic stirring when the magnetic stirring effect disappears. Even if the welding torch 1 is oscillated, if the magnetic stirring effect disappears on the groove gear G, molten metal will fall.

(Problems to be Solved by the Invention) In joint welding of steel plates, steel pipes, etc., especially joint welding of steel pipes, the quality of the single-sided welding uranami bead is an important point that affects the life of the product. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the drawbacks of the conventional welding method described above, to obtain good front and back peeds, to eliminate the magnetic stirring effect and to prevent molten metal from falling. The present invention aims to provide a magnetic stirring welding method with a wide allowable groove width and a wide range of appropriate welding conditions. The present invention relates to a magnetic stir welding method characterized in that the direction of the magnetic field is synchronized with the oscillation of a welding torch or a workpiece.

That is, in the conventional method of obtaining a uranami bead using the magnetic stirring welding method, the oscillation period of the welding torch and the magnetic stirring were unrelated, but in the present invention, (1) the oscillation period of the welding torch and the magnetic stirring period are and (2) the oscillation direction and position of the welding torch and the stirring direction (rotation direction) of the molten metal by magnetic stirring.
This method is characterized by a magnetic stirring welding method that maintains a constant constant.

The welding method of the present invention having such features is effective for all products manufactured by welding, particularly for first-layer Uranami welding and all-position welding.

The present invention will be explained below based on the drawings.

FIG. 1 shows a configuration diagram 2 of a magnetic stirring TIG welding apparatus according to the present invention. In Fig. 1, 6 is a magnetic field generating coil, 7 is an alternating current generating 'tIL source, 1 is a T/G welding torch, 5 is a tungsten electrode, 4 is a filler rod, 2 is a material to be welded, and 8 is an oscillator. A position detector 5 indicates the left and right oscillation directions of the welding torch.

The T-welding torch 1 is equipped with a magnetic field generating coil 6, and an alternating current generating power source 7 is connected to the magnetic field generating coil 6, and an alternating current is supplied to the alternating current generating coil 6. A welding device 9 is connected to the TIG welding torch 1, to which welding current, shielding gas, etc. are supplied, and at the same time, it is also equipped with an oscillation mechanism.

Furthermore, an oscillating position detector 8 is attached to the upper part of the T-worker G welding torch 1, and is connected to an alternating current generating power source 7, and the output current of the alternating current generator 7 is determined by the welding position signal from the oscillating position detector 8. is supplied to the magnetic field generating coil B while controlling the The magnetic field generated by the magnetic field generating coil 6 is supplied to the welding part to magnetically stir the molten metal.

Furthermore, the filler rod 4 connects the tungsten electrode 3 and the material to be welded 2.
It is fed at an appropriate speed to the welding part in the arc that occurs during this time.

In the present invention, as shown in FIG.
The position of the welding torch 1 and the direction of oscillation are detected by the oscillation position detector 8, and the alternating current is synchronized with the position of the welding torch 1, as shown in FIG. The direction of rotation is always kept at a constant position.

FIG. 2(a) shows a partially enlarged view of the vicinity of the molten pool 13 according to the present invention, and FIGS. 2(1)-(e) show the welding torch 1.
A schematic diagram of an oscillation trajectory 5 is shown. In FIG. 2, 2 is the material to be welded, 10 is the weld bead, 13 is the molten pool, 5 is the oscillation locus of the welding torch 1, 0 is the welding groove and the center line of the welding torch 1, and A.

B indicates the left and right oscillation range of the welding torch 1.

Further, an arrow 15 in the molten pool 13 indicates the direction of rotation of the molten metal by magnetic stirring, and 16 indicates an excitation current waveform.

The welding torch 1 during welding is controlled by the oscillation device from A→
Perform welding while moving regularly from 0 → B → 0 → A. On the other hand, the oscillating position detector 8 detects the moving position of the welding torch 1 and transmits, for example, the position A and the position B to the alternating current generator 7. When the welding torch 1 is moving to A - + H, the alternating current generator 7 outputs the excitation power in the positive direction as shown in 16, for example, and the molten metal flows in the molten pool 13 in the direction of the solid arrow. Rotate. Similarly, B4
In case A, if the molten metal in the molten metal 13 rotates in the direction of the dotted arrow, the rotation of the molten metal will stop (reverse) while the welding torch 1 is moving on the gear G with the welding groove center 0. Never.

In other words, switching between forward and reverse rotation of the magnetic stirring of the molten metal should be carried out regularly at the upper left and right sides of the welded material 2 where the plate thickness is high, avoiding the top of the gear G of the welded material 2. There will be no burn-through. Also, Figure 2 (2-2 in al.
If the plate thickness is different as in
(Fig. 2(d)), excitation current 16-2 (Fig. 2(e)
)) Heat input control can be performed as shown in ()).

(Effect of the invention) According to the present invention, even in joints with the same plate thickness and different plate thickness, (1
) The allowable groove width is wider, and (2) the range of appropriate welding conditions is wider! (3) A regular and beautiful bead appearance can be obtained for both the uranami bead and the front bead, and (4) in the case of joint welding of steel pipes, it is possible to use a welding position between 9 o'clock and 3 o'clock. In other words, the allowable range of welding postures becomes wider.

Examples are shown below.

EXAMPLE Obtaining a Uranami weld bead In the conventional welding method shown in FIG. 5, the allowable range of the root gap G is 0 to [L5M1
In the welding method shown in the figure, 2±αsM.

In the welding method shown in FIG. 8, the allowable range for the root gap G is 1 to 4 mm, and in the conventional method, the allowable range for the root gap G is narrow, making it difficult to obtain continuous, beautiful, and stable welding and welding.

On the other hand, according to the synchronous magnetic stirring oscillator G welding method of the present invention, the root gap G is 1 mm to 5 mm.
It is possible to obtain a continuous and stable Uranami bead over a wide range, and at the same time, it is possible to obtain a bead with a uniform wetting on the left and right sides of the bead and a good angle.

FIG. 3 shows the number of oscillations and the range of magnetic field strength for obtaining a good Uranami bead. As shown in Figure 3, when the magnetic field strength is 100 Gauss or more, the welding torch oscillates 30 times.
It can be seen that the range of times/min to 40v min is good.

According to the method of the present invention, the oscillation rate of the welding torch and the period of magnetic stirring of the weld metal can be synchronized to provide stable back-up even in uranami welding using MAG welding, MIG welding, and plasma welding equipped with magnetic field generating coils. The action and effect for obtaining a wave bead are the same, and although the welding condition range is slightly different from that of the above-mentioned synchronous magnetic stirring T welding method, a good back wave bead can be obtained.

Up to now, we have explained the case of oscillating the welding torch, but instead of oscillating the welding torch,
The effect is the same even if the material to be welded is oscillated.

As a result of welding carbon steel in a uranami bath according to the present invention, a good uranami bead was obtained. Table 1 shows an example of welding conditions for each welding method.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the magnetic stirring T welding device adopted in the method of the present invention, Fig. 2 is a diagram for explaining the principle of the method of the present invention, and Fig. 2 (+L) is a diagram of the present invention. 2(b) to 2(e) are schematic diagrams showing the relationship between the oscillation trajectory of the welding torch of the present invention and the output of the excitation power source, and FIG. 3 is a partial enlarged view of the vicinity of the molten pool according to the present invention. Chart showing the number of oscillations and magnetic field strength range obtained by Uranami beads,
4(a) to 4(C) are diagrams showing the groove shapes adopted in the embodiments of the present invention, and FIGS. 5, 6, and 8 are diagrams showing the conventional normal TUG welding method, its modification method, and magnetic stirring TIG
A diagram for explaining the welding method, FIG. 7 is a diagram for explaining the groove shape when implementing the welding method of FIG. 6, FIG.
FIG. 10 is a diagram for explaining the principle of the conventional magnetic stirring TIG welding method. Sub-agent 1) Meikoku agent Ryo Hagiwara - Sub-agent Atsuo Anzai Figure 3 Magnetic field strength (glass) Figure 4 (a) (b) (C) 1Gl- Figure 9 (ρ Figure 10

Claims (1)

[Claims] A magnetic stir welding method in which welding is performed by applying a magnetic field coaxially with the welding arc, which is characterized by synchronizing the direction of the magnetic field with the oscillation rate of the welding torch or the welded material.