Method and apparatus for seam welding metal tubing

Claim 1

IN A WELDING MILL OF THE TYPE ADAPTED TO FORM METAL TUBING BY WELDING THE CONVERGING EDGES OF AN ADVANCING SKELP, COMPRISING A HIGH FREQUENCY MEANS FOR RAISING THE TEMPERATURE OF SAID EDGES TO THE PRESSURE WELDING TEMPERATURE OF SAID SKELP, PRESSURE ROLLS FOR FORCING THE HEATED EDGES TOGETHER TO FORM A WELDED SEAM HAVING EXCESSIVE METAL PROTRUDING OUTWARDLY FROM SAID SEAM, AND A SCARFING TOOL FOR CUTTING THE EXCESSIVE METAL FROM SAID SEAM, THE IMPROVEMENT COMPRISING: AN INDUCTION AND CONDUCTION ANNEALING DEVICE LOCATED ON THE OPPOSITE SIDE OF SAID SCARFING TOOL FROM SAID HIGH FREQUENCY MEANS AND SPACED FROM SAID HIGH FREQUENCY MEANS A SUFFICIENT DISTANCE TO ALLOW SAID SEAM TO COOL AT LEAST TO APPROXIMATELY THE CRITICAL TEMPERATURE OF THE METAL OF SAID TUBING, SAID ANNEALING DEVICE INCLUDING A FIRST CONTACT RIDING ON SAID TUBING ADJACENT SAID SCARFED SEAM AT A FIRST LOCATION, A SECOND CONTACT RIDING ON SAID TUBING ADJACENT SAID SCARFED SEAM AT A LOCATION SPACED FROM SAID FIRST LOCATION, CONDUCTORS FOR CONNECTING SAID CONTACTS ACROSS A SOURCE OF HIGH FREQUENCY ALTERNATING CURRENT, AND AT LEAST ONE OF SAID CONDUCTORS EXTENDING IN CLOSE SPACED RELATIONSHIP WITH SAID SEAM AND BETWEEN SAID CONTACTS AND SAID SCARFING TOOL BEING LOCATED CLOSELY ADJACENT TO SAID HIGH FREQUENCY MEANS.