The PLC controlled system which is used to control step-motor and electricwelding machine is introduced in this paper, and automatic control of T-type channel Joints is realized.
利用可编程序控制器（PLC）控制步进电机和电焊机，实现T型管道接头焊接的自动化控制。
2
Automatic control has been used in the ignition of electric arc, welding wire-feed, movement of arc along welding direction, receiving arc of welding, etc.
埋弧自动焊时，引燃电弧、焊接送丝、电弧沿焊接方向移动及焊接收尾等过程均可实现自动化控制。
3
The elements and the whole sets of construction design of the automatic steel-pipe electricwelding machine were introduced. The composition of hardware and software of the systems were also designed.