Abstract: An electromagnetic power drive for a friction welding machine, comprising a magnetic core installed immovably, which carries a power coil connected to a voltage regulator made as a switch and at least one pickup coil connected to an integrator producing voltage proportional to the actual value of the magnetic flux during friction welding, which is connected to a comparison means comprising two comparators, a driving input of one of said comparators receives voltage proportional to the assigned value of the magnetic flux during friction welding, the driving input of the other comparator receives voltage proportional to the other assigned value of the magnetic flux, and a control signal generator having a hysteresis-loop output characteristic, which is connected to the comparators, the output of said generator being the output of the comparison means electrically coupled with the voltage regulator.

Abstract: A method of friction welding wherein the parts to be welded, of materials with inherent Young's moduli, are jigged coaxially, set to rotate with respect to each other under an axial pressure recurrently varying with a frequency which is in inverse proportion to the lower value of the Young's moduli and to the diameter--or to the smaller diameter--of the parts while these are being heated up for welding, whereby, the value of the frequency varies over a range between + and -15% and the parts are then upset-forged together.

Abstract: In accordance with the disclosure, the workpieces being welded are brought together by rectilinearly oscillating at least one of them along the line of bringing them together with the amplitude in the movement of the workpiece towards the other workpiece greater than that in the movement of the same workpiece in the direction opposite to the direction towards the other workpiece, voltage is applied to said workpieces for flashing and heating them in the course of bringing them together, and then an upset force is applied to the workpieces. The hydraulic drive adapted to generate the oscillatory rectilinear motion in a continuous flash butt-welding machine includes a hydraulic cylinder with two chambers which provides for moving one of the workpieces being welded with respect to the other and comprises apparatus for feeding hydraulic fluid alternately into either of the chambers of the hydraulic cylinder of the machine, the apparatus being connected with the cylinder through two hydraulic lines.