| 摘要 |
A spigot 22 and socket 20 eg. of plastics material are welded together by inducing a current in an induction member embedded in the weld region. The temperature of the induction member rises until it reaches its Curie temperature, at this point the temperature ceases to rise. The induction member may be a copper wire coated with iron/nickel composite to several skin depths and may be embedded in one or both of the spigot 22 and socket 20 or in a separate collar interposed between the two. A welding appliance 30 for inducing current in the induction member may be in the form of a clamp for simultaneously inducing current and clamping the socket 20 onto the spigot 22. A method of forming a socket 20 involves extruding a pipe with a region of increased thickness, fitting a collar including an induction member to a former, then warming and plastically expanding the region of increased thickness onto the former and collar. The spigot may be ceramic or metal, in which case adhesion is by a keying action of the collar material between ribs on the outer surface of the spigot. |
