JPH0671662B2 - Torch angle control method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a torch angle control method for high speed arc fillet welding performed along a bending welding line.

[Conventional technology]

Conventionally, in the case of automatically performing fillet welding of a T joint, a corner joint, etc., for example, the welding electrode is made to follow the groove route by following the groove profile by an arc sensor.

[Problems to be solved by the invention]

Conventionally, for example, in a welded joint in which the welding line 3 of the lower plate 1 and the standing plate 2 is bent to the left as shown in FIG. 11, while moving the welding torch 4 in the direction of arrow 5 along the welding line 3. In the case of automatic welding, the welding torch 4 is perpendicular to the welding line 3 before the welding torch 4 passes through the bending point 6.
After the welding torch 4 passes the bending point 6, the welding torch 4 makes a receding angle θ with respect to the welding line 3. When the torch angle of the welding torch 4 changes due to the bending of the welding line 3 in this way, the bead shape becomes discontinuous and the penetration depth changes, resulting in poor welding even when performing groove profiling. There was a point.

The present invention has been made to solve such a problem, and an object thereof is to propose a torch angle control method capable of automatically correcting a torch angle with respect to a bending welding line. Is.

[Means for solving problems]

The torch angle control method according to the present invention, in fillet welding performed along a welding line that bends while rotating the arc at high speed, (a) detects an arc voltage waveform or a welding current waveform of the rotating arc, ) The arc voltage waveform or the welding current waveform is ± 2.5 around the front point Cf of the welding advancing direction and the rear point Cr of the welding advancing direction.
Angle ± φo within a range of ± 90 ° from (°) to (c) the area Scf of the arc voltage waveform or welding current waveform made at the constant angle ± φo on the front point Cf side and the rear point Cr side. Calculate the area Scr of the arc voltage waveform or welding current waveform made at the angles ± φo, and (d) calculate the area difference Scf-Scr and detect the amount by which this area difference changes from the predetermined reference value. (E) The torch angle is changed according to the changing amount.

[Action]

In the present invention, when the torch angle with respect to the welding line fluctuates, the voltage waveform or welding current waveform of the rotating arc fluctuates, so fluctuations in the arc voltage waveform or welding current waveform during welding are detected and based on this fluctuation. Correct the torch angle when the welding line is bent.

〔Example〕

FIG. 1 is an explanatory view of fillet welding according to an embodiment of the present invention. In the drawing, 1 is a lower plate, 2 is a standing plate standing on the lower plate 1, 3 is a welding line, 4 is a welding torch. Is.

The welding torch 4 is rotated in the direction of arrow 7 by a rotation motor (not shown) at a rotation speed adapted to the welding current and welding speed,
By rotating the wire 8 passing through the eccentric hole of the current-carrying tip at the tip of the welding torch 4, the arc 9 is rotated at high speed and welding is performed along the welding line 3. In FIG. 1, the welding progress direction is perpendicular to the paper surface and extends from the back surface to the front surface, la is the arc length, le is the wire protrusion length, and Ex is
Is the distance between the welding torch 4 and the base metal.

FIG. 2 is an explanatory view of the welding torch 4 shown in FIG. 1 as seen from the direction of the rotation axis 10 and Cf, Cr, R, L in the drawing are the positions of the wire 8 when the welding torch 4 is rotating. Indicates, Cf
Is the position of the wire 8 in front of the welding advancing direction 5, R is the position of the wire 8 on the right side of 90 degrees toward the welding advancing direction 5, L is the position of the wire 8 on the left side of 90 degrees, and Cr is behind the welding advancing direction. The positions of the wires 8 are shown respectively. Further, φ represents a rotation angle of the wire 8 with respect to the welding proceeding direction 5.

As shown in Figs. 1 and 2, when the welding torch 4 is rotated under a constant wire feeding speed, the distance Ex between the welding torch 4 and the base metal differs depending on the position of the wire 6 during rotation, and the arc length. la changes. When the arc length la changes, the load characteristics change and the welding current I and the arc voltage E change. The change in the welding current I or the arc voltage E due to the change in the arc length la changes linearly with the change in the distance Ex unless the change in the distance Ex is large. As shown in FIG. 1, when the welding torch 4 rotates during fillet welding, the distance Ex changes with the sine wave as the reference shape according to the position of the wire 8, so that the welding current I and the arc voltage E are also at the position of the wire 8. Corresponding to the sine wave as a reference form changes. Note that this relationship holds true not only for consumable electrodes but also for non-consumable electrodes.

3 (a) and 3 (b) are arc voltage E and welding which change corresponding to the position of the rotating wire 8 or arc when the welding torch is perpendicular to the welding line 3 as shown in FIG. The waveform of the current I is shown. In FIG. 3, (a) is the waveform of the arc voltage E, (b) is the waveform of the welding current I,
Each waveform has a vertically inverted shape. The waveform of the welding current I can be obtained only by the welding power source having the constant voltage characteristic, and the waveform of the arc voltage E can be obtained by the welding power source having either the constant voltage characteristic or the constant current characteristic.

As shown in FIG. 4, when the welding torch 4 is perpendicular to the welding line 3, the waveform centering on the front position Cf and the rear position Cr of the wire 8 with respect to the welding proceeding direction 5 is as shown in FIG.
As shown in (b), the waveforms have substantially the same shape.

However, as shown in FIG. 5, when the welding torch 4 is tilted backward with respect to the welding advancing direction 5 and the advancing angle θ is taken, the arc la at the front position Cf of the wire 8 becomes longer than the arc length la at the rear position Cr. As shown in FIG. 6, the arc voltage waveform has a voltage level at the front position Cf higher than that at the rear position Cr. On the contrary, as shown in FIG. 7, when the welding torch 4 tilts forward with respect to the welding advancing direction 5 and takes a receding angle θ, the arc length la at the front position Cf becomes shorter than the arc length la at the rear position Cr, and the arc voltage As for the waveform, the voltage level at the front position Cf is lower than the voltage level at the rear position Cr as shown in FIG.

Therefore, by detecting the change in the arc voltage waveform, the change in the torch angle after the welding torch 4 has passed the bending point 6 in the welded joint in which the welding line 3 is bent to the left as shown in FIG. And its change amount can be detected and corrected. That is, the arc voltage waveform is set to Cf point and Cr
A certain angle φ to the left and right with respect to the welding direction centered on the point
Waveform area Scf, Scr created by dividing by o
Then, the torch angle can be corrected by the difference between the area Scf and the area Scr.

Here, the constant angle φo is set to 2.5 degrees to 90 degrees. Angle φo
Is set to 2.5 degrees or more because if the angle φo is less than 2.5 degrees, it is easily affected by noise on the waveform.

A block diagram of the control circuit shown in FIG. 10 in the case of automatically welding the above-mentioned torch angle control method by the welding torch 4 having the welded joint 3 in which the welding line 3 is bent as shown in FIG. 9 placed on the carriage 11. It will be explained based on. In FIG. 9, 12 is an electric motor for rotating the welding torch 4 in the direction of arrow 13.

First, the voltage detector 40 detects the arc voltage E, and the switch 41 divides the detected voltage E into the front point Cf side and the rear point Cr side in the welding direction. The timing of division of the arc voltage E by the switch 41 is controlled by a command signal from the switching logic circuit 42. The switching logic circuit 42 sets the rotation angle of the wire 8 detected by the rotation position detector 43 and the output φo of the φo setter 44, which sets a predetermined angle φo in the range of 2.5 degrees to 90 degrees, for example, 45 degrees. A comparison calculation is performed, and a waveform in a section in which the rotation angle of the wire 8 is ± φo centering on the forward point Cf in the welding advancing direction is output from the f side of the switch 41. Wire 6
The waveform of the section in which the rotation angle is ± φo around the rear point Cr in the welding traveling direction is output from the r side of the switch 41. The waveform output from the f side of the switch 41 is integrated by the integrator 45,
The waveform output from the r side of 41 is integrated by the integrator 46.
The n setter 53 is set with the number of times n of these integration processes, and the two integrators 45 and 46 are connected to the switching logic circuit 42.
Waveform integration is performed for n times of arc rotations output via, and the outputs Scf and Scr are stored in a memory respectively.
Output to 47, 48. Memories 47, 48 are integrators 45, 46 every n times
The signals Scf and Scr output from the differential amplifier 49 are repeatedly stored and retained. The differential amplifier 49 obtains this signal difference Scf-Scr and outputs it to the differential amplifier 50 at the next stage. In the differential amplifier 50, the above difference signal Scf-Scr
Difference ΔS = (Scf-Scr) -So from the reference value So when the proper torch angle is preset in the reference voltage setting device 51.
Is output to the torch rotating means 52. The reference value So is zero when the welding torch 4 is perpendicular to the welding line 3.

The torch rotating means 52 judges whether the signal ΔS is positive or negative, and the welding torch 4 is rotated by rotating the electric motor 12 shown in FIG. 9 according to the positive and negative signals and the value of the signal ΔS. Adjust the angle to the proper torch angle.

In the above embodiment, the torch angle is controlled by detecting the arc voltage waveform. However, even if the welding current waveform shown in FIG. 3 (b) is detected, the torch angle is controlled similarly to the above embodiment. can do.

〔The invention's effect〕

As described above, the present invention corrects the torch angle when the welding line is bent based on the fluctuation of the voltage waveform or the welding current waveform of the rotating arc, so that the bead shape at the bending point of the welding line is corrected. Discontinuity can be prevented. Further, even if the welding line is bent, it is possible to always weld at an appropriate torch angle, so that a certain penetration depth can be secured, and good beads can be formed over the entire length of the welding line.

[Brief description of drawings]

FIG. 1 is a side view of a welded portion of an embodiment of the present invention, FIG. 2 is an explanatory view showing the wire position of the above embodiment, FIG. 3 (a) is an arc voltage waveform diagram, and FIG. 3 (b) is Welding current waveform diagram, FIGS. 4, 5 and 7 are explanatory diagrams of welding torch position with respect to welding line, FIGS. 6 and 8 are arc voltage waveform diagram, 9
FIG. 10 is an explanatory view of an embodiment of the present invention, FIG. 10 is a block diagram of the control circuit of the above embodiment, and FIG. 11 is an explanatory view showing a conventional method. 1 ... Lower plate, 2 ... Standing plate, 3 ... Welding line, 4 ... Welding torch, 8 ... Wire.

Claims (2)

[Claims] 1. In fillet welding performed along a welding line that bends while rotating the arc at a high speed, (a) the arc voltage waveform or the welding current waveform of the rotating arc is detected, and (b) the arc voltage waveform. Alternatively, the welding current waveform is ± 2.5 around the front point Cf of the welding direction and the rear point Cr of the welding direction.
Angle ± φo within a range of ± 90 ° from (°) to (c) the area Scf of the arc voltage waveform or welding current waveform made at the constant angle ± φo on the front point Cf side and the rear point Cr side. Calculate the area Scr of the arc voltage waveform or welding current waveform made at the angles ± φo, and (d) calculate the area difference Scf-Scr and detect the amount by which this area difference changes from the predetermined reference value. (E) A torch angle control method characterized in that the torch angle is changed according to the changing amount. 2. The area difference Se of the arc voltage waveform or the welding current waveform when the predetermined reference value is the proper torch angle.
The torch angle control method according to claim 1, which is f-Scr.