| 摘要 |
PCT No. PCT/US90/00021 Sec. 371 Date Jan. 4, 1990 Sec. 102(e) Date Jan. 4, 1990 PCT Filed Jan. 4, 1990.An automatic welder is used in an internal welder unit which travels along the interior of a pipeline and provides the interior weld passes at the junction of abutting pipe joints. The internal welder unit has an electronic control system which includes a plurality of microprocessor control units, each of which performs specific functional operations for the internal welder unit. The microprocessor control units are interconnected by a serial communication link which permits the transmission of commands and data between all of the microprocessor control units. The control system includes a back end control unit positioned in the internal welder unit, a front end control unit with a panel in the weld unit, a reach rod control unit at the end of a reach rod and a power supply control unit adjacent the arc power supply. The control system directs the operation of orbiting internal welders to have a zero or slow travel speed at a start point to ensure a high reliablity of arc initiation. After the arc is started, the travel speed of the internal welders is accelerated to a high speed rate for the majority of the weld pass. At the end of the weld pass, the welders travel rate and wire feed rate are suddenly reduced to zero for the weld termination. The control system can extend to include one or more external welders, as well as external monitoring and control devices, all of which communicate through the serial communication link.
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