Patent ID: 7381923
Filing Date: 2008-06-03
Classification: B23K

Abstract:
1. In a combination of a contact tip and a consumable electrode for electric arc welding in which the contact tip has a body defining a bore having a length between an inlet end and an outlet end for the consumable electrode to pass through the bore, wherein the improvements comprise: the bore, in succession in a direction from the inlet end to the outlet end, having a first longitudinal section, a second longitudinal section and a third longitudinal section; the bore having a smaller diameter in the second longitudinal section than in the first longitudinal section to define at adjacent ends of the first and second longitudinal sections a circumferential step facing towards the inlet end; differences in diameters of the first and second longitudinal sections of the bore and hence the size of the step such that the consumable electrode is able to pass through each of the first and second longitudinal sections with a respective clearance each enabling electrical contact between the consumable electrode and the body, and such that the consumable electrode is able to bed into the body at the step thereby to establish in the second longitudinal section a primary contact region of the bore at which electric current from a welding power supply is transferred to the consumable electrode from the body; and the bore in the third longitudinal section having an increased diameter, relative to the diameters in the first and second longitudinal sections, for precluding between the body and the consumable electrode secondary contact in the third longitudinal section effective to substantially short circuit primary electrical contact in the primary contact region.