Overall overload protector for a press - has individual protectors for each tool stage and each driving point

摘要

The overall overload protector responds to an overload value which is smaller than the total of the overloads on individual overload protectors within the press system, and provides an opportunity for elimination of overload at a driving point within the system by simple means. The press system is multi-stage, and in the case of overload of the first stage the oil pressure increases between the piston and the cylinder so that oil is ejected through the safety valve into the oil tank. The piston actuates the limit switch for stopping. The piston which responds to overall overload is loaded on one side pneumatically and on the other side by plunger pistons. This equilibrium position ensures that no additional stages are stopped when one stage is affected. Plunger pistons push the overall overload piston upwards if excessive overload is present until the outlet is opened and oil is ejected into the tank and the limit switch is actuated for stopping the entire machine.