Automatic Longitudinal Seam Welding Machine for Flat Metal Sheet   1. Welding Requirements:  To finish the flat metal sheet butt joint welding automatically. To guarantee the uniform surface forming and good appearance, the depth of fusion and width of fusing reach the welding requirement. It is easy to clamp and load. Adopts butt welding process, it requires one side welding both sides formation.  2. Equipment Composition The machine is made up of gantry type working table, welding torch longitudinal moving mechanism, pneumatic clamping bar mechanism, loading and unloading table, fixture, conductivity mechanism, welding torch lifting, clamping and adjusting mechanism, electrical control system, welding power source and pneumatic system.  1) Welding torch clamping&adjustment&lifting mechanism:  The welding torch is driven by air cylinder to move up and down to switch between preparation and welding station. It adopts push-wire feeding mode to ensure the wire feeding stability.  The torch can move up and down, left and right and angle fine adjustment. The welding torch forward and backward distance can be set according to the length of workpiece.  2) Pneumatic clamping bar mechanism Pneumatic clamping bar mechanism is driven by air cylinder to press the workpiece evenly. The clamping bar head is made of copper plate. It will lift after finishing welding process, then unload workpiece.  3)Gantry type working table The working table consists of fixed station, water cooling copper back clamping bar, up and down pneumatic positioning mechanism. The fixed station adopts welded bed. Base is welded by square tubes and steel plates.  The upper face machined and mounted with copper back clamping bar, which has a water cooling system to ensure the temperature of back clamping bar is not to high to affect the welding result. To realize the effect of one side welding and both sides formation.  Three pneumatic positioning air cylinders drive the positioning plate up and down to control the seam position. When the workpiece is positioned the length on the working table, the clamping bar presses the workpiece tightly, positioning air cylinders falls down and starts to weld.  3. Electrical system:  1. ) It is controlled by imported PLC, with good stability, simple structure and easy maintenance.  2) Using Taiwan original touch screen as input and output interface, welding length, arcing igniting and arc ending time, welding current, welding voltage and welding speed can be all input through the interface.  3) Integrated control panel box. Control buttons, touch screen, welding specification are concentrated on one panel, it is easy to use and operate.  4 ) Welding power source: It is chosen by customer.