Goodbye control cabinet!

Cabinet-free drive technology enhances productivity throughout the entire value stream. Bosch Rexroth outlines five requirements of the future.

Quickly convert machines for new products, subsequently expand production lines, reduce installation area – these and additional customer requests inspired Bosch Rexroth to develop cabinet-free drive technology. The current IndraDrive Mi generation also reflects the future requirements of mechanical engineers and end users.

Intelligent servo drives are indispensable for modern machines. The advantages are clear: at the touch of a button, they apply format conversions or changes in the movement profile and, in so doing, shorten changeover times. The other side of the coin: larger and larger control cabinets increasingly occupy “unproductive” space. At the same time, in almost all industries there has been a loud call for modular drive concepts that help shorten product life cycles and flexibly adapt existing production lines to new tasks.

Five requirements of the future

For Bosch Rexroth engineers, this resulted in the following five key requirements for developing cabinet- free drive technology. They oriented themselves to these requirements on the path to the current IndraDrive Mi generation. The first requirement revealed itself with a glance to the conventional drive technology: here, the motor and control device are separate from one another, a power cable and an encoder cable run from each motor to the control cabinet. Rule of logic: less cable, less control cabinet.

1.Less space, more flexibility

The advantages of the servo technology can also be enjoyed with an up to 90 percent reduction in cabling requirements. To this end, the decentralised drives of the IndraDrive Mi are entirely connected through a common hybrid cable for communication and erformance. Up to 30 servo drives can be combined with a cable harness up to 200 meters long to make one drive assemblage. The first drive is connected directly to the power supply and control unit through the hybrid cable. Mechanical engineers can also connect sensors, I/ Os, and fieldbus components directly to the decentralised drives without laying an additional fieldbus cable in the machine.

The mains connection and power supply components up to this point located in the control cabinet can now also be installed in the machine – performed in IP65. The mains module, including the filter, throttle, and contactor, is connected directly to the network. A regenerative supply module is responsible for supply and control electronics and integrates brake resistors and transistors alongside control electronics. In this way, the end user can completely forego the control cabinet and gain precious space on the surface.

2. Modularity in Electronics

The second requirement of cabinet- free drive technology follows the trend of modularisation. As the mechanical engineer can pre-install the drive modules and get them operating at his own plant, stations created subsequently to this can be incorporated quickly into existing production lines. Only the power supply and connection with the higher-level control unit need to be established on-site with the end customer. Moreover, if the drives are already parameterised, the quicker start-up also reduces the machine downtime resulting from modification.

To enable further integration of the modules into the end user’s automation landscape at no additional cost, Bosch Rexroth provided its solution with a Multi- Ethernet interface that supports all common Ethernet protocols, Sercos, PROFINET, EtherNet/IP, EtherCAT, and POWERLINK among them. This means fewer variations and less warehousing for maintenance.

3. Standard-compliant safety

Of course, conventional approaches cannot detract from machine safety

but ideally should increase availability. In the end, the machinery directive with Bosch Rexroth decentralized drive concepts easily translates into a basis for modularization. In addition to certified safety functions within IndraDrive Mi, the hybrid cable ensures transfer of all safety signals without additional wiring, thereby also eliminating an additional source of error.

What is particularly interesting is the easy adaptation of safety zones with several drives in one drive train. For Safe Torque Off, the first drive of a safety zone is wired in such a way that it processes the safety signals. To add additional drives to a safety zone, all that needs to be done there is to use a safety plug, which is extremely easy to do at start-up and transparent during operations. Several safety zones are possible within one drive train. This solution shortens the time required for restart after a manual adjustment and thus increases the machine’s availability.

4. Efficient use of energy

It is often right at the top of specifications: energy efficiency. Beyond its contribution to climate protection, it exerts a significant influence on life cycle costs. To this effect, cabinet-free drives can score with an energetic coupling for the system. As an energy exchange is possible between the drives using the hybrid cable, the brake energy of a stalling drive can be available to an accelerating drive, for example, and surplus energy can be fed back into the network. Power consumption can be cut in half as a result. On top of this, the power dissipation in the control cabinet drops as does the energy demand for cooling the control cabinet.

5. Ready for integration

The last and increasingly important requirement lies in the ability to network with company IT in terms of Industry 4.0. The decentralised drives already fulfill a major prerequisite for this as they operate independently according to higher-level instructions.

The Multi-Ethernet interface ensures the communication ability needed for horizontal and vertical networking. Beyond this, Rexroth is the first drive and control manufacturer to bridge drive technology and IT – in addition to the options for SPS-based automation in accordance with IEC 61131-3 and PLCopen as well as OPC UA technology.

For on-demand access to all drive parameters by way of high-level language-based applications, Bosch Rexroth has incorporated Open Core Interface technology from the higher-level Open Core Engineering solutions portfolio directly at the drive level. With the help of Open Core Interface for Drives, end users can for example read out and analyse energy consumption using common spreadsheet programs via macros. To simplify drive start-up, parameterisation, and diagnosis, self-programmed commercial smartphone and tablet apps using Open Core Engineering have found their way into day-to-day mechanical engineering.

Cabinet-free means future-proof

With its cabinet-free drive technology, Bosch Rexroth meets the essential requirements for the future with regard to spatial requirements and modularisation, safety and energy efficiency as well as vertical and horizontal networking. What appears especially promising is the integrated intelligence and interface technology suitable for implementing Industry 4.0 applications which are now at the top of the agenda for mechanical engineers and end users alike.


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