JPS6284873A - Arc welding method - Google Patents

Abstract

PURPOSE:To cope with complicated welding position and joint shape by making an arc generating point not coaxial with the torch center, by performing an oscillation with repeated rotation of the torch or electrode and by changing the rotary angle and rotary center as well. CONSTITUTION:An arc generating spot is formed at the eccentric position to the torch center by making the tip of an electrode 8 eccentric in non-consumable electrode method and by making the wire 11 projecting from the wire guide groove 10 of a contact tip 9 eccentric in consumable electrode method. In case of performing the welding, the arc oscillation is performed by repeatedly turning the electrode 8 or tip 9 for the torch center and the control of the rotary center position to the weld line L and rotary angle theta of the repeated turn is performed as well. The optimum oscillating state coped with the complicated change in the welding position and joint shape can thus be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an arc welding method that realizes an optimal oscillation state depending on complicated welding postures and joint shapes.

[Prior art] The shapes of electrodes in conventional arc welding methods are as shown in Figures 10 (A) and (B) for non-consumable electrodes, and as shown in Figures 11 (A) and (B) for consumable electrodes. In both cases, the electrode tip is aligned with the center of the torch. Also, in both cases, the torch is non-rotating. Therefore, the point of generation of the arc coincides with the center of the torch, and the center of the amplitude of the oscillation coincides with the center of the groove. In Fig. 10, 1 is a non-consumable electrode, and 11 is a non-consumable electrode.
In the figure, 2 indicates a consumable electrode (filler wire).

[Problem to be Solved by the Invention 1] However, when welding the branch pipe 4 to the main pipe 3 at right angles as shown in FIG. Therefore, if oscillation is performed symmetrically with respect to the weld line, the molten metal 1 will sag depending on the welding location as shown in FIG. 13, and welding defects such as poor fusion due to undercuts 5 and overlaps 6 will occur.

In view of the above-mentioned circumstances, the present invention attempts to always maintain the best welding condition even when the welding position changes and the joint shape is complex.

[Means for solving the problem] The present invention makes the arc generation point eccentric with respect to the center of the torch,
This method is characterized in that oscillation is performed by repeatedly rotating the torch or electrode, and the repeated rotation angle and center of rotation are changed depending on the welding situation.

[Operation] Since the arc generation point is eccentric to the center of the torch, when the torch or electrode is rotated, the arc moves and oscillation becomes possible. Also, by changing the repetitive rotation angle and its center, the amplitude of the oscillation and the center of the oscillation change.

[Example] The present invention will be described in detail below with reference to the drawings.

In the present invention, in the non-consumable electrode method, the tip of the electrode 8 is eccentrically formed as shown in FIGS. The filler wire 11 protruding from the contact tip 9 by being inclined at a portion thereof is eccentric from the center of the torch, so that the point of generation of the arc is shifted from the center of the torch. Since the point of generation of the arc is shifted from the center of the torch, the arc moves as the torch rotates.

Therefore, oscillation is possible by repeatedly rotating the torch.

In oscillation using this method, various oscillation modes can be selected by appropriately selecting the rotation angle of the repetitive rotation and selecting the center of the repetitive rotation.

Figure 3 shows the mode of oscillation, and Figure (A) shows the center of repeated rotation θ and the welding line aligned;
i) (ii) 0iD (to) and b in which the rotation angle is increased sequentially, rfI diagram < 1111) (/ is the one in which the center θ of repeated rotation and the welding ML are shifted.

Also, Figure 4 is a diagrammatic representation of the trajectory of the oscillation.
B) and Q\) in the same figure correspond to Q\) in Figure 3, respectively.

By appropriately selecting the center θ of the repetitive rotation of the torch and the angle of the repetitive rotation described above, various oscillation modes can be selected even if the torch movement in the welding line direction (travel running on the trolley) is continuous at a constant speed. As shown in FIG. 5, it is also possible to change it to intermittent running ((a) in the same figure), change in running speed ((b) in the same figure), and forward/backward movement ((a) in the same figure). By appropriately combining and synchronously controlling the torch rotation mode and the trolley running mode, it becomes possible to select an extremely wide variety of oscillation modes.

In addition, the oscillation mode can be easily changed by simply changing the rotational state of the torch or by simply controlling the running speed of the trolley, and can also be easily changed in response to changes in welding posture and joint shape during welding. It can be followed sufficiently.

For example, when welding the branch pipe 4 of the main pipe 3 shown in Fig. 6 at the A-A arrow section, consider the drooping of the molten metal and make sure that more heat is input to the upper part of the joint. If you select the oscillation mode 1 to mode, for example, the torch rotation mode shown in Fig. 3 (B) and the trolley running mode shown in Fig. 5 (A), and perform the oscillation as shown in Fig. 7, the smooth bead as shown in Fig. 8 can be made by 1q. can be done.

Next, one of the control devices for controlling the above oscillation rate.
An example will be explained with reference to FIG.

A pulse generator 20 is connected to a motor 19 for rotating the torch 31, an angle detector 22 is attached to the torch 31 to detect the rotation angle of the torch, and the detection signal of the pulse generator 20 is compared via a motor feedback circuit 21. The signal from the angle detector 22 is input to the comparator 15 via the calculator 23 and the repetition command circuit 24.

Further, a signal from the angle setting device 12 for setting the rotation angle of the torch 31 and a signal from the center setting device 13 for setting the center of repetitive rotation are input to the comparator 15. manipulates the signals from the angle setter 12, center position setter 13, and repeat command circuit 24, and inputs the results to the position and speed servo circuit 16. A speed setting signal is inputted to the servo circuit 16 from the rotational speed setting device 14 .

The output from the 1/1 output circuit 16 is input to the comparator 17 and the forward/reverse command circuit 25, and the signal from the forward/reverse command circuit 25 is input to the speed setting signal from the bogie speed setter 28 and the bogie running motor 27. It is input to the bogie drive circuit 26 together with the output from the connected pulse generator 29. The truck driving circuit 26 causes the truck to travel in a required manner based on these three signals.

1--When the rotation angle of the torch 31 and the center of repetitive rotation are selected by the angle setting device 12 and the center setting device 13, and the actual rotational position of the torch 31 is input from the repetition command circuit 24 to the comparator 15, Comparator 15 sends a signal for position control to servo circuit 1
Enter into 6. The servo circuit 16 controls the torch rotation motor 1 based on this position control signal and rotation speed setting signal.
Outputs a control signal for driving 9. This signal is compared with the actual motor rotation speed from the motor feedback circuit 21 in the comparator 11, and a correction control signal that achieves the set speed is input to the motor drive circuit 18, and the motor drive circuit 18 performs the correction control signal. Torch rotation motor 1 based on the signal
Drive 9.

The actual position of the torch 31 in the rotational direction is determined by the angle detector 22 and the calculator 23 as described above.
The reversal signal when the signal reaches the reversal position is input from the repetition command circuit 24 to the comparator 15, and based on this signal, the servo circuit 16
issues a control signal for inversion.

The forward/reverse command circuit 25 is set and inputted in advance to the manner in which the bogie travels, and a control signal corresponding to the manner is outputted to the bogie drive circuit 26. Further, the running speed of the bogie is set from the bogie speed setting device 28, and the actual running speed of the bogie is inputted from the pulse generator 29.

When a synchronizing signal is inputted from the servo circuit 16 to the forward/reverse command circuit 25, the bogie drive circuit 26 synchronizes with the repetitive rotation of the torch 31 and causes the bogie to travel in a desired manner.

[Effects of the Invention] As described above, according to the present invention, the best welding performance and high quality welding can always be obtained even when the welding posture changes and the joint shape is complex.

[Brief explanation of drawings]

Figures 1 (a) and 1 (b) show the shape of a non-consumable electrode for carrying out the present invention, in which (a) is a front view, (b) is a side view, and
Figures (A) and (B) show the shape of the same consumable electrode, (A) is a side view, (B) is a bottom view, and Figure 3 (A), (B), and Q\) are electrode rotations for oscillation. Fig. 4 ←) (0) (/\) is a pictorial diagram showing the locus corresponding to the above oscillation, and Fig. 5 (a) (b) QO is a diagram showing the traveling mode of the welding cart. , FIG. 6 is an explanatory diagram of a welded joint in which a branch pipe is welded to a main pipe, FIG. 7 is a diagram showing the locus of oscillation in the joint, and FIG. 8 is a view taken along arrow A-A in FIG. 6. Fig. 9 is a block diagram showing an example of a control device for carrying out the present invention, Fig. 10 (a) shows the shape of a conventional non-consumable electrode, and (b) is a front view. is a side view, Figure 11 (a) (
B) shows the shape of the same consumable electrode, (A) is a front view, and (
B) is a bottom view, FIG. 12 is an explanatory view showing a state in which a branch pipe is welded to the main pipe, and FIG. 13 is a view taken along the line B-B in FIG. 12. 8 is an electrode, 11 is a filler wire, 12 is an angle setting device,
13 is a center setter, and 31 is a torch. Patent application Hitoshi Kawajima Harima Heavy Industries Co., Ltd. Figure 5 (A) (B) (C) Figure 6 Figure 8 Figure 7

Claims (1)

[Claims] 1) Oscillate by repeatedly or continuously rotating the torch or electrode that deflects (directs) the arc in a predetermined direction by eccentrically centering the arc generation point with respect to the center of the torch, and adjusting the repetitive rotation angle and angle depending on the welding situation. An arc welding method characterized by repeatedly changing the center of rotation.