091-10 Lohr, 2010-10-26

Greater Energy Efficiency for Press Brakes

Variable-speed pump drive

Variable-speed pump drives for forming machine tools save energy, reduce average noise emissions, and improve process quality and precision movement.

Variable-speed pump drives from Rexroth also integrate into existing concepts

Rexroth realizes energy savings of up to 50 percent as compared to fixed systems with its variable-speed pump drives for press brakes and other forming machine tools. Active regulation improves process quality and precision movement while maintaining proven safety concepts. And average noise emissions are reduced such that secondary noise reduction measures typically required do not need to be fitted.

Rexroth's BlueHydraulics technology combines hydraulic pumps optimized for variable-speed operation with a controlled electric drive. A frequency converter with standard motor or servo drive is used, depending on dynamic requirements, to convert the command values specified by the machine control to as-required speeds. This, in turn, influences control of the synchronized cylinders used for the press brake.

In partial-load operation (e.g. downward travel without a bending load and loading times), the pump drive reduces operating speeds to save considerable amounts of energy. Real-world results prove that savings of up to 50 percent are possible, with a commensurate reduction in climate-damaging CO2 emissions. Active regulation also reduces the heat absorbed by the hydraulic fluid so that the cooling system can be downgraded considerably or even omitted altogether. Average noise emissions are also reduced by up to 10 dB(A) due to the temporary drop in speed. This almost always makes it possible to minimize secondary insulation measures.

The highly precise active regulation system achieves better synchronization as compared to the conventional valve-based setup used in press brakes. It also improves the positioning accuracy for the required end position via accompanying pressure monitoring – an important prerequisite for realizing exact bending angles on the workpiece. Speed control simplifies the hydraulic circuit while maintaining all proven safety functions of the hydraulic control. This enables the energy-saving, variable-speed pump drives to be integrated into existing machine concepts as well. Press manufacturers can combine the energy-efficient active regulation system with the proven, standardized safety concepts of their standard machines without additional outlay required.

The variable-speed drives are commissioned like other electromechanical drives from Rexroth. All hydraulic particularities have already been factored into the software. Machine manufacturers can retain the familiar user interface of their controller, since the variable-speed pump drives automatically adjust to the command values assigned to them. The drives also provide a great deal of information for optimizing processes by enabling transparent access to data. As a result, only machine-specific parameters need to be configured. Finally, the drives enhance condition-monitoring options for targeted maintenance.

Rexroth uses a comprehensive, systematic approach in developing such solutions. With 4EE (Rexroth for Energy Efficiency), the drive and control specialist has identified four key levers for higher energy efficiency that apply to all drive and control technologies: products and systems optimized for low energy consumption, recovery and storage of excess energy, energy supplied on demand, and systematic analysis with optimum planning, simulation, and consulting.

Bosch Rexroth AG is one of the leading drive and control technology specialists worldwide. Under the brand name of Rexroth the company supplies more than 500,000 customers with tailored solutions for driving, controlling and moving. Bosch Rexroth is a partner for industrial applications and factory automation, mobile applications and using renewable energies. As The Drive & Control Company, Bosch Rexroth develops, produces and sells components and systems in more than 80 countries. In 2009, the company of the Bosch Group with its 34.200 employees generated sales amounting to about EUR 4,1 bn.

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Susanne Herzlieb
Maria-Theresien-Straße 23
97816 Lohr am Main
Phone: +49 9352 18-1573