This example shows an actuator that is intended to drive a machine tool working unit performing a sequence of three technological operations: coarse drilling, fine drilling, and reaming. The actuator speed is controlled by one of three pressure-compensated flow control valves metering out return flow from the cylinder. The selection of an appropriate flow control is performed by directional valves that are activated by a control unit.
ELM_F and ELM_R are the signals that activate forward and return motions, respectively, by shifting the main directional valve. ELM_1 activates normally- closed valve DV_1. When opened, valve DV_1 bypasses all flow controls and sets the fast traverse speed. ELM_2 controls valve DV_2. When deenergized, this valve directs return flow through Flow Control 1, which is set to reaming speed. ELM_3 directs flow either through Flow Control 2 (fine drilling) or Flow Control 3 (coarse drilling).
The technological load is simulated as a position-dependent force by using a table lookup block.
Flow control valves are arranged as a subsystem comprised of a fixed orifice and a pressure compensator. The electromagnets are also arranged as a subsystem built of a single-acting actuator and a converter.