Automatic argon arc (plasma)straight seam welding machine is mainly used for the automatic butt welding of cylinders and aligned plates made with stainless ateel,iron,aluminum and brass,etc,Because automatic movement machanism is used,The welding joints are good in shape and beatiful. The pneumatic clamping device is equipped with special copper pressing feet,ensuring safety and the accuracy of the clamping device: The back lining can be adjusted and selected in accordance with the thickness of the material to be welded:The back lining can ensure to provide stable protective gas to ensure double side forming in single side welding. The movement during longitudinal welding is driven by the direct current speed measuring motor,and the movement is stable: The welding gun can be automatically positioned with pneumatic,and can also be manually adjusted with the cross slide plate.