Electric heating – Metal heating – By arc
Patent
1988-08-09
1989-08-15
Shaw, Clifford C.
Electric heating
Metal heating
By arc
21912422, 21912512, B23K 912
Patent
active
048577006
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a control apparatus for an automatic arc welding machine, more particularly, to a control apparatus for an automatic arc welding machine for automatically performing arc welding by weaving a welding torch along a weld line, using an arc sensor to detect an arc current caused by the weaving, and compensating movement of the welding torch.
BACKGROUND ART
In automatic arc welding a welding torch is made to weave along the weld line of base metals to be welded, and simultaneously, an arc current caused by the weaving is detected by an arc sensor to compensate movement of the welding torch, and thereby the weld line of the base metals is automatically arc welded. More specifically, when the actual weld line of the base metals to be welded deviates from an instructed weld line, the arc current is detected by the arc sensor and processed and thereby the movement of the welding torch is compensated to correctly move the welding torch along the actual weld line.
In the processing of an arc current of a conventional control apparatus for an automatic arc welding machine, for example, the position, amplitude, and the like of an arc current detected by the arc sensor are monitored, and welding torch is moved for a predetermined distance in accordance with the peak value of the monitored position, amplitude, and the like, and as a result, the welding torch is moved along the actual weld line of the base metals.
An arc current detected by an arc sensor has an unstable waveform because of disturbances occurring during arc welding and the like. In particular, although the peak value of the ac current is processed by smoothing the current waveform thereof through a filter or the like, a change in the arc current caused by a deviation of the welding torch from the weld line of the base metals cannot be easily discriminated from a change in the arc current caused by a disturbance or the like. Furthermore, a peak can occur in an arc current due to factors other than a deviation of the welding torch from the weld line, and as a result, an overcompensation of the movement of the welding torch occurs.
DISCLOSURE OF THE INVENTION
The object of the present invention is to correctly move the welding torch along the weld line of the base metals, and to perform arc welding even when an actual weld line of base metals to be welded deviates from an instructed weld line.
According to the present invention, there is provided a control apparatus for an automatic arc welding machine for automatically performing arc welding by weaving a welding torch along a weld line, using an arc sensor to detect an arc current caused by the weaving, and compensating movement of the welding torch, characterized in that the control apparatus comprises: an area calculating device for detecting the arc current at every half period of the welding, and integrating the arc current on a time basis to calculate two areas each corresponding to a 1/4 period, a first area comparing discriminating device for comparing the two areas and discriminating between a first large area and a second small area, a second area comparing discriminating device for calculating a first correction area by subtracting a predetermined area from the first area, the predetermined area corresponding to a predetermined time period at an end portion of the first area, and comparing the first correction area with the second area, and a movement compensating device for correcting a reference value by using a correction function to compensate movement of the welding torch when the first correction area is larger than the second area.
With the control apparatus for the automatic arc welding machine according to the present invention having the arrangement described above, the welding torch is caused to weave along the weld line to perform an automatic arc welding, an arc current caused by the weaving is detected by an arc sensor, and movement of the welding torch is compensated. The arc current detected at every half period of the weaving
REFERENCES:
patent: 4587398 (1986-05-01), Sarugaku et al.
patent: 4658112 (1987-04-01), Thompson
patent: 4704513 (1987-11-01), Sugitani et al.
Kanda Yuichi
Mizuno Tohru
Morikawa Shigehiro
Torii Nobutoshi
Toyoda Kenichi
Fanuc Ltd.
Shaw Clifford C.
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