Patent ID: 6629632
Filing Date: 2003-10-07
Classification: B21C,B21D,B23K

Abstract:
A method for welding a tapered shaft having an open seam defined between opposed longitudinal edges, said method comprising;moving a tapered shaft along its longitudinal axis relative to a plurality of rollers arranged substantially symmetrically around a common fixed axis and each inclined at an acute angle relative to its next adjacent neighbors on each side, each of said plurality of rollers being movable by hydraulic pressure radially of the fixed axis for applying inwardly directed radial forces to the shaft at a plurality of discrete points spaced circumferentially around the shaft surface; controlling the movement of said rollers radially of the fixed axis to account for the taper and progressively close the seam as it passes said rollers; and progressively welding the seam after it is closed by said rollers; wherein the step of controlling the movement of the rollers includes using a control computer to vary the hydraulic pressure applied to the rollers by open loop control according to a predetermined voltage ramp.