| 摘要 |
A guide tube for guiding a wire (23) of filler metal in an arc welding machine and for applying arc current thereto comprises a metal body (80) having a longitudinal bore (82) through which the wire passes. Near the front end of the tube there are two transverse passages (95) housing respective ball (96) which are urged to project into the bore by respective spiral compression springs (97). These serve to keep the wire pressed against the opposite side of the bore to maintain good electrical contact. The springs are held in by a sheath (100) fitted over the end of the tube. The sheath also serves to keep an end piece (50) in place. Both the sheath and the end piece are made of refractory material which is electrically insulating and which is non-adhesive to spattering metal from the weld melt. This helps to prevent the front of the tube getting clogged up in operation.
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