GALLED JOINTS MADE WITH ELECTRIC HEATING

摘要

The invention, the subject of our International Application PCT/GB 91/00950 provides a method of securing against lateral motion two bodies held in face-to-face asperity contact, thereby to make a join between the two bodies, in which method there is inserted into the interface between the two bodies a material that on minimal initial lateral relative motion of the two surfaces promotes rapid but controllable 'galling' between the two surfaces, this galling binding the surfaces against further such motion. The present invention relates to improvements in galled joints generally, as well as more specifically both to an improvement of our earlier Application's method to facilitate its use over a wider range of interfacial conditions, and also to an addition of that method to permit in some favourably configured joints the converting of the galled contacts therewithin into actual inter-metallic diffusion bonds across the interlocked (joined) faces to form continuous welds. The invention proposes that, while and/or after a galled joint is formed, an electric current be passed across the joint. If the current is provided during joint formation then the supplied external mechanical energy is supplemented by the electric current energy so as selectively to heat and soften the touching asperities, enabling them to deform and flatten more rapidly to bring other smaller asperities nearby into contact and thus increase the number of gall sites. If the current is provided after joint formation, then it is believed that it results in the stimulation and/or acceleration of the formation of diffusion bonds across the opposed faces of the joint.