| 摘要 |
During spot welding with long welding jaws 14 of inner support walls for fire protection doors 3 of parallelepiped shell structure, the problem of coating of the welding jaws 14 occurs. During each welding pass, a coating layer is produced at the places of a welding jaw where spot welding occurs, which means that after a certain number of welding passes the coatings become so sizeable that the welding jaw 14 is unusable. The purpose of the invention is to increase the lifetime of a welding jaw 14. This is done in that the door 3 and the welding jaw 14 are made to be moveable in relation to each other so that the layer coating is spread along a larger portion of a welding jaw 14. <IMAGE> |
