Apparatus and method of phase control for resistance welding and other resistive-inductive loads
US4493040A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 1, 1982 |
| Grant date | Jan 8, 1985 |
| Priority date | — |
| Expiry date | Jun 1, 2002 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB23K11/252
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A computer-controlled welding apparatus includes a phase-controlled resistance welding circuit (A) for selectively conducting pulses of a welding current to a workpiece (B) and a control circuit (C) for controlling the conduction of the welding current. The control circuit includes a line clock generator (30) for determining the beginning of each voltage half line cycle and a conduction sensor (34) for determining whether or not a contactor (14) is conducting current to the workpiece. A microcomputer (40) is preprogrammed with a plurality of power factor correction curves, each of which represents weld current vs. firing angle for a fixed hangover angle. The computer is programmed to select one of the power factor correction curves. If the preceding half line cycle was conductive, the program selects the curve which corresponds to the hangover angle of the preceding half line cycle. If the present half cycle is the first conductive half cycle in a weld, the program selects the curve corresponding to a hangover angle of about 87.degree.. During pulsation welding, the curve is selected based upon the hangover angle of the most recent conductive half cycle and the number of nonconduct…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.