| 摘要 |
A steel nut body has its wrench flats covered by a sheet stainless steel sheath that extends over one of the nut ends to form a cap. The surfaces of the wrench flats are formed with ridges that bear against the inner surfaces of the sheath. The sheath is welded to the nut to resist forces exerted during torquing by bringing a pair of electrodes into pressured contact with the sheath on opposed sides of the nut to produce pressure concentrations at the ridges. An extremely short, high current electrical pulse is then passed between the electrodes. The heating produced by the current at the interface between the sheath and the nut body decreases the electrical resistance of this path resulting in primary current flow path between the two interfaces, through the nut body, to produce resistance welds at the inner faces without substantially modifying the metallurgy of the sheath.
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