Programmed welding machine with weld head speed override

Claim 1

In a welding machine for joining a plurality of pairs of metal pieces along substantially identical weld grooves disposed between said pieces: (a) a frame, (b) a plurality of carriages, each being mounted to said frame for movement relative to a respective first axis, (c) a rotator suspended beneath each said carriage and with said rotator being rotatable about a C axis disposed generally perpendicularly to said pieces, (d) a weld head suspended beneath each said carriage for forming a weld in one of said grooves, (e) a sensor suspended beneath each said carriage for following the contour of the respective groove in advance of the respective weld head, (f) each said weld head and sensor being rotatable with a respective rotator with respect to a said C axis, (g) first and second motive means: (1) to selectively drive each said carriage along its respective first axis, and (2) to rotate each said rotator about its respective C axis, (h) each said first and second motive means being actuatable in response to a programmable input control unit to cause each said sensor and weld head to traverse a programmed path at a given speed, and with said path generally corresponding to that of the respective groove, (i) program override means connected to each said rotator and responsive to a deviation in the respective groove perpendicular to the respective programmed path and sensed by the respective sensor to cause said rotator and its weld head to move from the programmed path to a corrected path which is in correspondence with the actual path formed by the respective groove, (j) and second override means connected to the program override means of each said rotator for selectively changing the speed of movement of the respective weld head in a direction parallel to the respective groove.