| 摘要 |
PURPOSE:To prevent as much as possible occurrences of rust due to electrolytic corrosion in a conductive contact part, by installing a highly conductive sacrifice material to the conductive contact part of an Al alloy-made gun arm and a power supplying part of copper alloy, etc., so that the sacrifice material is fitted and removed freely. CONSTITUTION:For example, a spot gun arm 1 of a portable spot welding machine is provided with a pair of openable and closable arm components 2 and 3. Components 2 and 3 are made of an Al alloy and each base has a fitting part 6 formed flat by stepping both sides. The flat face of a copper alloy-made power supplying secondary cable terminal 7 is brought into contact with the fitting part 6 and fitted by screws. On the other hand, the front end face 10a and one side face 10b of the sacrifice material 10 are brought into contact with the rear end face 6a of the fitting part 6 and a part of the fitting face 7a of the termenal 7, respectively, and the sacrifice material 10 is fitted by a bolt 11 so that it is fitted and removed freely. An Al-5Zn-2Hg alloy, etc., which has a higher conductivity than the gun arm has and a smaller potential difference than the gun arm and terminal have, is used to make the sacrifice material 10. In this way, the electric current to components 2 and 3 flows preferentially and condensedly to the sacrifice material 10. |
