Anyone gaining only a superfluous familiarity with fluid technology can easily underestimate the performance and intelligence of modern hydraulics. Who would think that this technology is highly precise, energy efficient, and ready today for Industry 4.0 applications? Here are six capabilities of a strong drive technology:
Electro-hydraulic axis controllers close the control loop decentrally, similar to electrical servo drives, and harmonize the target/actual position in real time within milliseconds. The precision of the movement solely depends on the respective utilized measuring system. In tool and plastic machines, hydraulic drives reliably position axes to a precision of a few micrometers.
It is often difficult to place electro-mechanical 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.
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.
Ready-to-install servo-hydraulic axes have an integrated fluid loop and are driven by the same servo drives as the electro-mechanical versions. Since axes are encapsulated systems, engineers must only connect power and communication cables for assembly and start-up, and then start-up can begin. Everything else (for example, the parameterization values determined from simulations) is already stored in the drive software and supports the plug and run philosophy.
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 retrofitted without major efforts to significantly reduce the energy consumption in production.
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. This makes them an ideal match for the increasingly integrated and technology-overlapping infrastructure of modern production environments – all the way up to Industry 4.0.
About the author: Dr. Steffen Haack is a member of the Executive Board for Bosch Rexroth AG and is responsible for the industrial applications and sales division. For more information, visit www.boschrexroth-us.com.