Over the past few decades, the technical development of hydraulic plastics processing machines and machine tools has been driven basically by increases in efficiency (accuracy, cycle time, etc.). Here, the use of proportional and high-response valves as well as an improvement of the energy balance through the use of variable displacement pumps with electro hydraulic control have been in the foreground. In recent years, requirements with regards to energy saving and noise reduction have become increasingly stricter. Rexroth responds to these changing market requirements with the use of variable-speed pump drives (DvP).

With variable-speed pump drives, Rexroth opens up new possibilities of cutting life-cycle costs while complying with user specifications. While conventional variable displacement pumps with asynchronous motor control the displacement and pressure via internal control mechanisms, on the variable-speed pump drive, Rexroth relocates the closed-loop control into the converter. Outside the machining time when no hydraulic flow is required and during partial load operation the frequency converter reduces the speed of the electric drive and the fixed displacement motor. This reduces energy consumption, hydraulic power losses, which are introduced into the oil, and noise emissions. As soon as the hydraulic system requires more power, the converter adjusts the speed accordingly with the demands.

www.boschrexroth.ca

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