Pulse welding apparatus

A welding apparatus having a pulse current waveform control circuit for producing and outputting a group of pulse currents comprised of one or more pulse currents, said circuit comprising:

• an arc length detector for detecting an arc length at each moment based on an arc current detected value and outputting an arc length signal;
• a separation detector for detecting separation of a molten droplet on the basis of said arc length signal and outputting a separation detection signal;
• a target arc length setting device for setting a target arc length varying at each moment;
• a comparator for comparing at each moment said arc length signal and said target arc length;
• a pulse group current generator for setting a reference pulse current waveform;
• a current waveform period setting device for setting a pulse current group output period of the group of pulse currents in accordance with a wire-supplying speed;
• a current waveform duration setting device which is set for each pulse group period for outputting an ON signal to one or more analog switches;
• a flip flop which is set by said separation detection signal for outputting an ON signal to said one or more analog switches;
• a base current outputting device for outputting a base current;
• an adder for superimposing said base current on the group of pulse currents;
• a comparator for comparing the signal output from said adder with the arc current detected value so as to control an invertor drive circuit;
• and
• a charge amount setting device for setting the amount of charge of said group of pulse currents.

A pulse welding apparatus having a wire electrode with a tip, comprising:

• a pulse current waveform control circuit for outputting a group of pulse currents including a plurality of pulse currents having one of (i) more than one pulse width, (ii) more than one pulse peak value and (iii) more than one pulse interval, a smoothed current waveform of the group of pulse currents becoming a maximum peak value during a pulse group duration at a predetermined time after a beginning of outputting the group of pulse currents, said group of pulse currents being periodically repeated to form a train of said group of pulse currents;
• a timing unit for setting, based on welding conditions, the predetermined time occurring at any time after the beginning of outputting the group of pulse currents during the pulse group duration;
• a smooth current waveform generator for generating a signal representing the smoothed current waveform of the group of pulse currents, wherein said pulse current waveform control circuit generates said plurality of pulse currents based on said signal;
• and
• a pulse arc current waveform generator for generating a pulse arc current waveform by superimposing a continuous base current onto the train of said pulse group currents, wherein one of the pulse interval, pulse width, and pulse period of said group of pulse currents is varied in synchronism with the separation of a molten droplet on the tip of the wire electrode.

A pulse welding apparatus having a wire electrode with a tip, comprising:

• a pulse current waveform control circuit for outputting a group of pulse currents including a plurality of pulse currents having one of (i) more than one pulse width, (ii) more than one pulse peak value and (iii) more than one pulse interval, a smoothed current waveform of the group of pulse currents becoming a maximum peak value during a pulse group duration at a predetermined time after a beginning of outputting the group of pulse currents, said group of pulse currents being periodically repeated to form a train of said group of pulse currents;
• a timing unit for setting, based on welding conditions, the predetermined time occurring at any time after the beginning of outputting the group of pulse currents during the pulse group duration;
• a smooth current waveform generator for generating a signal representing the smoothed current waveform of the group of pulse currents, wherein said pulse current waveform control circuit generates said plurality of pulse currents based on said signal;
• and
• a pulse arc current waveform generator for generating a pulse arc current waveform by superimposing a continuous base current onto the train of said pulse group currents, wherein one of the pulse interval, pulse width, and pulse period of said group of pulse currents is changed a predetermined time after beginning of outputting said group of pulse currents.