Device for the purpose of monitoring and controlling the movement of hydraulically driven plunger, in particular in injection molding machines

摘要

In a casting machine using an injection ram, the ram movements are measured accurately and reliably in spite of adverse ambient conditions by a special sensing arrangement located inside the hydraulic drive cylinder which drives the ram. A sonic energy pulse is generated in a waveguide near the hydraulic piston. This pulse propagates along the waveguide to a transducer at the cylinder wall. The time required for this pulse propagation corresponds to the position of the piston and hence of the injection ram.