RESISTANCE TYPE FLASH BUTT WELDER

RESISTANCE TYPE FLASH BUTT WELDER A welder, comprising a self-contained pumping accumulator plant associated hydraulically with a hydraulic ram of a moving clamp transfer gear adapted for gripping pipes being welded, a device for decreasing the pressure in said hydraulic ram and in a pilot valve during flashing and for increasing said pressure during upsetting, a low-pressure high-capacity pump with a filter, a relief valve, a nonreturn valve and an unloading slide valve, two high-pressure lowcapacity pumps and a device for cutting in and out said pumps and the unloading slide valve. The pumping accumulator plant and the high-pressure pumps communicate with a main oil plant and a hydraulic control of said slide valves of the clamp hydraulic drives is connected to the pumping accumulator plant. The pilot valve is controlled by a welding process program control actuator. The machine is adapted for welding pipes of large diameters (exceeding 1000 mm), the overall dimensions and weight of the welder being comparatively small. During flashing that is done at a low pressure the tracing of resistance welding is effected, with the upsetting operation being carried out at a high pressure developed in a hydraulic feed circuit.