Double-stroke lifting mechanism for fixed welding machine

The double-stroke lifting mechanism for the fixed welding machine comprises an air cylinder and a connecting pipe, the upper end of the connecting pipe is connected to a cylinder rod of the air cylinder, the axis of the cylinder rod is consistent with that of the connecting pipe, a connecting plate is arranged at the lower end of the connecting pipe, and the air cylinder is installed on a machine body through an installation plate. A fixing plate parallel to the connecting pipe is arranged at the lower end of the mounting plate, a guide groove is formed in the fixing plate, the guide groove penetrates through the fixing plate, and a limiting pin is arranged in the guide groove. The welding head has the advantages that after the limiting pin is inserted into the limiting groove, the connecting pipe can only ascend till the lower groove wall of the limiting groove is attached to the limiting pin, and then the connecting pipe cannot ascend, so that in general, the limiting pin is inserted into the limiting groov