Welding control systems

An automatic arc welding system comprising, in combination:

• a. a track positionable adjacent to a weld path on a member to be welded;
• b. a carriage coupled to said track;
• c. a carriage motor on the carriage for moving it along the track at a given speed so that the carriage follows along the path;
• d. a welding torch coupled to said carriage;
• e. a torch motor on the carriage which when energized causes excursion movement of the torch in a direction perpendicular to the direction of motion of the carriage;
• f. amplitude control signal generating means for said torch motor to provide a desired amplitude of excursion of said torch;
• g. excursion time control signal generating means for said torch motor to provide a desired excursion time for the torch to travel between the limits of the desired amplitude;
• h. left and right dwell time control signal generating means for said torch for individually providing desired left and right dwell times of the torch at the left and right limits of the torch excursion on the left and right sides of the weld path respectively, whereby the selected amplitude, excursion time, and left and right dwell times may be automatically controlled;
• i. welding current servo means for supplying welding current to said torch;
• j. welding current control means connected to and controlling said welding current servo means to provide current to the torch, said welding current control means including means for providing low frequency current pulses alternating between adjustable high and low current levels, the frequency and duty cycle of the high current level being independently adjustable, said means comprising in combination a high level current source;
• a low level current source;
• a switch logic means connecting said high level current source and low level current source to said welding current servo so that when said switch logic means is switched back and forth the high level current source and low level current source are alternately applied to the welding current servo;
• means for generating a series of pulses at a frequency proportional to the carriage speed in inches per second divided by a given number of pulses per inch as set into said system;
• first and second counters connected to receive said pulses at their inputs;
• and a flip-flop circuit having set and reset terminals connected respectively to the outputs of said first and second counters, said first counter automatically resetting itself and providing an output pulse to said flip-flop when a given number of pulses have been counted, and said second counter providing an output after a given count is achieved less than said first mentioned count to reset said flip-flop, said duty cycle being set into said second counter, said flip-flop connecting to said switch logic means to alternately pass said high level current source and low level current source in accord with the selected counts for said first and second counters;
• and,
• k. means automatically responsive to the torch position connected to said means for generating welding current so that the high level current occurs during the left and right dwell times and the low level current occurs during the excursion times of said torch.