Ready-to-install servo-hydraulic axes have an integrated fluid loop and are driven by the same servodrives as the electromechanical versions.
Last month, I wrote about a visit to Morrell Group in Auburn Hills, Mich., as it hosted Bosch Rexroth’s “Smart Factory” tour. I am sure there are many naysayers out there that believe that hydraulics can’t be smart or that it cannot offer the many options that are available with electronic components. But those naysayers would be wrong.
While at the press tour, we saw new technologies and applications where hydraulic valves, variable speed pump drives and other components are working in systems to increase system efficiency, decrease energy and noise and provide diagnostics to plant personnel.
Following up on these thoughts is Dr. Steffen Haack, a member of the Executive Board of Bosch Rexroth AG, responsible for Industrial Applications and Sales Division. Haack was at the event with us that afternoon, but here he shares where and when he thinks modern hydraulics is highly precise, energy-efficient and ready for Industry 4.0 applications.
Micrometer precision: Electrohydraulic axis controllers close the control loop decentrally, similar to electrical servodrives, and harmonize the target/actual position in real time within milliseconds. This precision depends on what measurement system is used; for example, in tool and plastic machines, hydraulic drives reliably and precisely position axes to a few micrometers.
Compact: It is often difficult to place electromechanical drives with sufficient performance in tight construction spaces. Unlike hydraulic drives they also add significant heat. Since power generation is decentralized in the power unit and since it is connected to the actuator via lines or pipes, OEMs can generate high forces even on minimal construction space. The relatively low level of heat created in the work area dissipates optimally through the hydraulic fluid.
Need-based energy efficiency: Software combines the best from electrical and hydraulic systems. The decentralized intelligence in the electronic control device adjusts the rotational speed of the pump drive on demand as the consumer requires power, or it lowers it to zero. In comparison to common constant drives, this reduces the energy consumption of hydraulic power units by up to 80% By the way: even older facilities and machines can be retrofit without major efforts to significantly reduce the energy consumption in production.
Rexroth’s Sytronix variable-speed pump drive is the prime example of this, as it can reduce energy use by as much as 80% but also dramatically reduce noise as well.
Balanced drive physics: Fluid technology is not always inherently linear. Drive software for hydraulic actuators takes these particularities into consideration and harmonizes them automatically. Pre-programmed, typical hydraulic functions, e.g. synchronization or position-dependent braking, merely require the optimization of parameters within the scope of start-up. They are based on a transparent software structure and function equally on all hardware platforms.
Open and outgoing: With increasing frequency, real time Ethernet protocols in modern machines integrate all actuators and peripherals into each other. Modern motion controls for hydraulic drives support all common protocols, e.g. Sercos, EtherCAT, Ethernet IP, PROFINET RT, Powerlink and Varan. Their software is also based on open standards, e.g. IEC 61131-3 and PLCopen. With this it is an ideal match for the increasingly integrated and technology-overlapping infrastructure of modern production environments – all the way up to Industry 4.0.
Rexroth’s IAC- proportional valve offers a multi-Ethernet interface while providing all the necessary position, force and pressure control.
The company’s IAC-R proportional control valves are yet another example of this, as they offer a multi-Ethernet interface while providing all the necessary position, force and pressure control. These valves have their own control electronics on-board, but also the control electronics for the motion axis itself. So the axis encoder (positon control) and / or pressure transducers (pressure, force, or p/Q control) plug directly into the valve housing itself, driving all of that control to the device level.
Rexroth calls this design an absolute “game-changer” for multi-axis machines. They reduce costs and space when it comes to panel space and field wiring as it eliminates the need to use separate axis controllers on each axis for a machine having 10 to 14 (or more) independent hydraulic axes of control.
Simply exchangeable: Ready-to-install servohydraulic axes have an integrated fluid loop and are driven by the same servodrives as the electromechanical versions. Since axes are encapsulated systems, engineers must only connect power and communication cables for assembly and start-up, and start-up can begin. Everything else, for example the parameterization values determined from simulations, are already stored in the drive software and support the plug-and-run philosophy.
What is interesting about these points is that they should be ones anyone involved with fluid power technology should know. As Haack points out, precision and power density are two of the most important reasons why modern hydraulics is ready for Industry 4.0. There is no match for hydraulics’ power density; it is the reason it is used so often in tight spaces and on small machinery. So it’s now our turn to promote these ideas, as we work to educate more engineers about the benefits of fluid power technology in the smart factory.
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