Electric resistance welding apparatus

摘要

The apparatus has a cylinder whose piston, which can be acted on by pressure on both sides, has a passage for the working medium, which simultaneously acts as a coolant, to cool the welding electrode. The cooling channel through which a flow can pass for cooling can be shut off by spring-loaded non-return valves which are hydraulically, automatically blocking in the working direction and in the opposite direction, for the application of force to the piston rod. The valves can also have a common spring, to save constructional volume. In the retracted end position of the piston, in which a cooling circuit is in operation, the non-return valve which hydraulically, automatically blocks oppositely to the working direction is rendered inoperative by a stop. This valve arrangement makes high piston powers possible on the one hand, but on the other hand maintains the cooling circuit at low delivery pressures.