Intelligent Self-sufficient Systems for Powerful Drive Tasks

Maritime Activity Reports, Inc.

May 22, 2017

Stand-alone self-contained electro-hydraulic servo axis (SHA): Functionalities identical to that of electromechanical variants. (Image: Bosch Rexroth)

Stand-alone self-contained electro-hydraulic servo axis (SHA): Functionalities identical to that of electromechanical variants. (Image: Bosch Rexroth)

 Standalone self-contained electro-hydraulic servo axis (SHA) from Bosch Rexroth

New from Bosch Rexroth are standalone axes with identical servo-drives for actuators with mechanical or hydraulic force transmission, offering new degrees of freedom for machine manufacturers in finding drive solutions that suit specific application requirements. The versions with hydraulic transmission are provided with their own, decentralized fluid circuit. The installation, commissioning and connection to controls and Industry 4.0 environments via a Multi-Ethernet interface or ProfiBus are identical on both variants.
The standalone self-contained electro-hydraulic servo axis largely consists of electrical and hydraulic series components. They pair all the functions known from servo-drives with the physical advantages of fluid power technology such as high power density and robustness. The standardized subassemblies, that is, hydraulic cylinder, control block and motor/pump group, form the basis for these linear axes of modular design. They are fitted with their own, closed fluid circuit and do without a central hydraulic power unit. The leak-free fluid circuit requires only a very small amount of hydraulic fluid. Bosch Rexroth delivers the axes completely preassembled, filled with hydraulic fluid and commissioned. The system is virtually maintenance-free and the fluid medium service life corresponds to that of the axis.
Identical commissioning
Each stand-alone axis includes Rexroth IndraDrive servo drives, with a power spectrum of up to 630kW. Thanks to their decentralized intelligence and standardized software, the type of force transmission is irrelevant for the higher-level control. Also when it comes to commissioning, there is no difference. A power connection and a communication connection to the higher-level control are sufficient. In addition, IndraDrive controllers with their Multi-Ethernet interface support all common Ethernet protocols like Sercos, ProfiNet, EtherNet/IP, EtherCAT, Powerlink or ProfiBus.
Intelligent, reliable and energy-efficient
The software of the IndraDrive servo-drives assumes the control of the linear unit. The SHA library contained in the software automatically takes account of all specialties of fluid power technology. This allows the user to easily parameterize even complex travel profiles, for example for forming and joining technology, injection molding machines and other applications that involve large forces. Apart from the standard function “Safe Torque Off”, IndraDrive drives offer further certified safety functions. With the help of “Safety on Board”, which is integrated in the drive, machine manufacturers can reach safety levels up to SIL 3 according to IEC 61508, which corresponds to PLe according to IEC 13849.
Bosch Rexroth’s standalone self-contained electro-hydraulic servo axes are characterized by their high energy efficiency. If temporarily no movement is required, the servo-drive lowers the motor speed for the pump in-line with the demand in partial-load operation or switches to stand-by mode. Power branching in multi-axis operation is accomplished purely electrically. The controllers recover braking energy and can make it available to other consumers via an intermediate circuit. In addition, it is possible to store the recovered energy or feed it back to the mains.
Simulation for dimensioning in line with application requirements
For the rating of the SHA in line with application requirements, Rexroth developed a simulation program on the basis of experience in modeling of hydraulic systems gained over decades. This software tool shortens the time to market and offers machine manufacturers higher safety in the engineering phase.
Thanks to the modular design of the SHA with standardized subassemblies, the machine manufacturer can easily adapt the axis exactly to his application. SHA from Rexroth covers the power range from 100 kN to 2.500 kN in pulling and pushing direction. The maximum stroke of the axes, which feature protection class IP 65, is 1,800 mm. With an integrated, magnetostrictive absolute encoder, the accuracy is 1 μm.
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