Abstract: The machine incorporates two clamping means, a static one fitted to a bedframe and a movable one mounted on rods which are attached to upsetting hydraulic cylinders with their ends with provision for reciprocating back and forth. Each clamping means consists of a base and a holding-down plate which is hinged to the base and displaced by a hydraulic cylinder a body of which is hinged to the base and a piston rod of which is hinged to the holding-down plate interacting with a holding down roller in clamping workpieces. The machine is provided with a fastener in the form of an inverted L-shaped lever, a means of adjusting the alignment of the workpieces for welding, and a means of setting a gap between the workpieces, made as a plunger and an adjustable stop installed coaxially.