Induction heating and pressure welding of two weldable surfaces

The induction welding unit (20) has a heavy frame (22), at least one laminated or non-laminated induction coil (40,42), a hydraulic cylinder (30) to move at least one of the parts (M1,M2) being welded and an adjustable clamping mechanism (24). The weldable surfaces (S1,S2) are separated from each other. Heating and upset is carried out under a hood (44) and an inert gas flows over the welded surfaces to prevent oxidation. The cylinder and piston rod provide a relative movement between the parts and the induction coil(s), so that the coils are in close proximity between the surfaces and are then withdrawn.A transformer (46) transmits HF voltage through the coil when it is in position between the weldable surfaces, in order to heat the surfaces to an upsetting temp. The surfaces are then pressed together with sufficient force to upset for the purpose of welding together, with the coil(s) arranged at a distance from the surfaces