Cylinder packs a punch for energy savings

Cylinder packs a punch for energy savings

It sounds like a machine gun going off. That's because hydraulic cylinders in a new punching axis can cycle up to 4,000 times per minute. The new, ready-to-install punching cylinder axis promises maximum performance while lowering energy consumption. When pursuing development work targeted on high-efficiency punching cylinder axes, Bosch Rexroth specialists first analyzed the energy demand patterns in punching and nibbling machines under real-world conditions. The findings: The application calls for peak energy during just 10% to 20% of the total cycle time. Only the punch movement itself demands full energy output while secondary periods — tool changing, loading or removing workpieces, etc. – require little hydraulic power.

Because they incorporate demanddriven energy generation, Bosch Rexroth modules offer potential energy savings of 80% to 90% of total operating time without restricting productivity. Above all, boosting efficiency lowers the total costs of ownership and reduces CO2 emissions.

Standardized punching cylinder axes are especially well suited to applications associated with nibbling, punching, engraving, soft punching, and deep drawing. Three versions are available — standard, advanced, and high-performance — to deliver 200 kN and 300 kN of rated force. They typically achieve rates of 600 to 1500 cycles/min at a stroke of 4 mm (and up to 4000 cycles/min in an engraving mode). Two pressure ranges and an accumulator charging circuit cut required power consumption up to 50%.

Energy boosted as needed

In its fastest version, the punching cylinder axis from Bosch Rexroth can achieve up to 4000 strokes/min.

Even in an optimized high- and lowpressure system, a constant-speed pump generates full flow all the time. However, the Type ER adjustable pump with electrohydraulic pressure regulation will reduce energy consumption during idling periods. Those periods can account for 80% to 90% of total cycle time. To execute the punch movements themselves, the adjustable pump works in concert with the electrohydraulic controls to charge accumulators in the highand low-pressure system.

The A10VSO axial-piston pump used in this configuration covers an extremely broad performance spectrum, with rated pressure to 315 bar and displacement from 18 to 140 cm3. Hysteresis in all the models is less than 3 bar. The residual pressure function, designed for safety, protects the machine in case of a power failure and extends service life.

The software for the integrated pressure modulation solution is stored in a Bosch Rexroth HNC100-3x motion controller. It matches pump output to the process and provides stepless response to momentary changes in demand. The HNC100-X supports Profibus DP, Sercos III, CANopen, and Profinet RT and also incorporates an Ethernet service interface.

Reducing complexity

Bosch Rexroth augments the punching cylinder axes with shock-tested servo motors and an open CNC control concept. In accordance with IEC 61131- 3, lead time is reduced by a common engineering environment for project work, commissioning, and diagnosis for all the PLC-based electrical and hydraulic drives. Only four hydraulic hoses need be installed. Furthermore, a preassembled cable harness prevents wiring errors.

This summary was provided by Rolf Heidenfelder, Bosch Rexroth AG, Germany. For more information, contact him at [email protected] or visit