Electric heating – Metal heating – By arc
Patent
1987-11-20
1989-09-26
Shaw, Clifford C.
Electric heating
Metal heating
By arc
21912512, B23K 912
Patent
active
048702471
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of and an apparatus for controlling a welding robot, and more particularly, it relates to a method of and an apparatus for controlling a welding robot for performing weaving between two members that are being welded in accordance with previously stored data relating to an interspace therebetween.
BACKGROUND OF THE PRIOR ART
One of important functions of a welding robot is weaving a weld between members being welded thereby. As is well known in the art, such weaving is a welding method of oscillating a welding torch substantially perpendicularly to a weld line to move the same along the weld line. In a conventional control method for making the welding robot perform such weaving, generally the oscillation width in the perpendicular direction, i.e., the weaving width amplitude is previously set in a computer as a constant value, to oscillate the forward end of the torch of the welding robot in the constant weaving amplitude and thereby to perform welding.
However, in the workpiece to be welded (hereinafter referred to as "welded member", and when two members are to be welded to each other, as "first" and "second" welded members respectively), the butting space and bevel width between the first and second welded members (generically referred to as an "interspace" between the welded members) are frequently not uniform in the weld line direction. This is due to variations and integrated errors in cutting accuracy, bending accuracy and assembling accuracy caused by bending and distortion of materials. When such welded members are joined by a weld woven by a welding robot through application of the conventional control method, the welding is performed in the constant weaving amplitude regardless of the nonuniformity of the interspace therebetween, whereby under-and-overwelding is caused depending on positions, to very seriously lower the weld quality.
Therefore, manual welding has been generally required to weave welded members having a ununiform interspace between them.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve the aforementioned problem of the prior art and provide a method of controlling a welding robot which can perform exact qualities of weaving even if the interspace between welded members is ununiform along the weld line direction, thereby to secure welding accuracy of high quality.
The present invention is directed to a method of and an apparatus for controlling a welding robot for weaving first and second welded members by a welding robot having a welding torch and arms movably supporting the welding torch while oscilating and moving the welding torch along the weld line of the welded members.
According to the present invention, data on change in the interspace between the first and second welded members along the weld line direction are previously stored in advance of the welding, in order to attain the aforementioned object. On the basis of the stored data, arithmetic is so performed as to form the weld while varying the weaving amplitude with the aforementioned change in the interspace to obtain command values, which command values are outputted to control the motion of the welding robot.
Therefore, even if the interspace between the welded members is nonuniform, such nonuniformity is heated as a change in the interspace along the weld line direction so that the weaving amplitude is varied with the nonuniformity, whereby the weaving is neither too much nor too little, to secure welding accuracy of high quality.
The aforementioned and other objects and effects of the present invention will become more apparent from the following description when taken with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a general view of a welding robot according to the preferred embodiments of the present invention.
FIG. 2 is a view showing the manner of setting teaching points and the locus of a welding torch in a first embodiment of the present invention.
REFERENCES:
patent: 4163886 (1979-08-01), Omae et al.
Fukuoka Hisahiro
Kamiyama Yoichi
Takano Yutaka
Hitachi Construction Machinery Co. Ltd.
Shaw Clifford C.
Shin Meiwa Industry Co., Ltd.
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