Method and device for automatic control of resistance-butt welding

Claim 1

A METHOD OF AUTOMATIC CONTROL OF A STRAIGHT FLASHWELDING PROCESS WHEREIN THE WELDING CYCLE CONSISTS F THE FOLLOWING CONSECUTIVE STAGES: (A) PREPARATORY STAGE, DURING WHICH THE WORKPIECES TO BE WELDED ARE MOVED TOGETHER AT A COMPARATIVELY LOW CONSTANT SPEED WHILE APPLYING AN ALTERNATING VOLTAGE OF A MAGNITUDE SUFFICIENT TO BEGIN FLASHING OF THE COLD ENDS OF THE WORKPIECES TO BE WELDED AND SMOOTH OUT THE IRREGULARITIES THEREON, THE END OF THE PREPARATORY STAGE BEING DETERMINED WHEN A PREDETERMINED PRESET INTEGRAL VALUE OF THE WELDING CURRENT HAS FLOWED THROUGH THE WORKPIECES; (B) FIRST STAGE, WHOSE DURATION COMMENCES FROM THE BEGINNING OF THE FLASHING OVER THE ENTIRE END SECTION AREA OF THE WORKPIECES BEING WELDED, AND WHEREIN THE SAME VOLTAGE AND ADVANCING SPEED ARE MAINTAINED, AS DURING THE PREVIOUS PRELIMINARY STAGE, FOR A SUFFICIENT TIME, DEPENDING ON THE DIMENSIONS AND CONFIGURATION OF THE WORKPIECES BEING WELDED, TO INSURE UNIFORM HEATING OF THE ENTIRE SURFACE BEING FLASHED; (C) SECOND STAGE, WHEREIN THE ADVANCING SPEED IS KEPT AT THE PREVIOUS LEVEL, WHILE THE VOLTAGE IS REDUCED BY A VALUE ADEQUATE FOR MAINTAINING THE INTERVIEW OF THE WELDING CURRENT NOT LESS THAN THAT DURING THE SAID FIRST STAGE, AND FOR CONTINUING STABLE FLASHING OF THE WORKPIECES; (D) THIRD STAGE, WHEREIN TO INCREASE THE INTENSITY OF FLASHING OF THE WORKPIECE THE ADVANCING SPEED IS INCREASED AND SIMULTANEOUSLY THE VOLTAGE IS RAISED TO A LEVEL CLOSE TO THE VALUE OF THE VOLTAGE DURING THE SAID PREPARATORY AND FIRST STAGES; (E) FOUTH STAGE, WHEREIN UPSETTING IS PERFORMED WITH A PRESET UPSET TRAVEL AND UPSET CURRENT TIME.

Claim 2

A METHOD OF AUTOMATIC CONTROL OF A STRAIGHT FLASHWELDING PROCESS WHEREIN THE WELDING CYCLE CONSISTS F THE FOLLOWING CONSECUTIVE STAGES: (A) PREPARATORY STAGE, DURING WHICH THE WORKPIECES TO BE WELDED ARE MOVED TOGETHER AT A COMPARATIVELY LOW CONSTANT SPEED WHILE APPLYING AN ALTERNATING VOLTAGE OF A MAGNITUDE SUFFICIENT TO BEGIN FLASHING OF THE COLD ENDS OF THE WORKPIECES TO BE WELDED AND SMOOTH OUT THE IRREGULARITIES THEREON, THE END OF THE PREPARATORY STAGE BEING DETERMINED WHEN A PREDETERMINED PRESET INTEGRAL VALUE OF THE WELDING CURRENT HAS FLOWED THROUGH THE WORKPIECES; (B) FIRST STAGE, WHOSE DURATION COMMENCES FROM THE BEGINNING OF THE FLASHING OVER THE ENTIRE END SECTION AREA OF THE WORKPIECES BEING WELDED, AND WHEREIN THE SAME VOLTAGE AND ADVANCING SPEED ARE MAINTAINED, AS DURING THE PREVIOUS PRELIMINARY STAGE, FOR A SUFFICIENT TIME, DEPENDING ON THE DIMENSIONS AND CONFIGURATION OF THE WORKPIECES BEING WELDED, TO INSURE UNIFORM HEATING OF THE ENTIRE SURFACE BEING FLASHED; (C) SECOND STAGE, WHEREIN THE ADVANCING SPEED IS KEPT AT THE PREVIOUS LEVEL, WHILE THE VOLTAGE IS REDUCED BY A VALUE ADEQUATE FOR MAINTAINING THE INTERVIEW OF THE WELDING CURRENT NOT LESS THAN THAT DURING THE SAID FIRST STAGE, AND FOR CONTINUING STABLE FLASHING OF THE WORKPIECES; (D) THIRD STAGE, WHEREIN TO INCREASE THE INTENSITY OF FLASHING OF THE WORKPIECE THE ADVANCING SPEED IS INCREASED AND SIMULTANEOUSLY THE VOLTAGE IS RAISED TO A LEVEL CLOSE TO THE VALUE OF THE VOLTAGE DURING THE SAID PREPARATORY AND FIRST STAGES; (E) FOUTH STAGE, WHEREIN UPSETTING IS PERFORMED WITH A PRESET UPSET TRAVEL AND UPSET CURRENT TIME.