kubler articles

Good Bye Unbalance: Slip rings convince with safe industrial Ethernet communication

Kubler 11/1/2015

Good Bye UnbalanceData rates in the high gigabit range are on the agenda of modern machines. In order to keep pace with this trend, Kubler relies on Industrial Ethernet in its new slip rings. Read how significant performance improvements can be achieved this way.

Rotary tables, balancing machines, measuring and testing equipment, but also any kind of automation facilities and industrial robots are typical applications for slip rings. They are used wherever motion sequences are universal and are repeated millions of times with highest accuracy. In such environments, the rotary transmission systems play a decisive role for the transmission of very high data rates.

In cases where the rotary motions take place only in a restricted angular range, it might be possible to arrange the transmission between components with flexible cables. But in continuous rotary movements, the slip ring is the unrivalled component to achieve the transmission path.

Keep pace on the way to 4.0

Gripping and motion components used in industrial plants must today be able to transmit real-time data. This is one of the most important requirements in automation technology in order to keep pace on the way to Industry 4.0. "Kubler slip rings are setting here an important milestone with the new SR120 Ethernet Contact: A modular 3-chamber system with a shield concept ensures safe transmission of load current, signals, air, hydraulics and now also Ethernet data" reports Gunter Kahrs, Product Manager for Transmission Technology at Fritz Kubler.

The new slip rings transmit all data protocols based on the Fast Ethernet standard, that is to say e.g. Profinet, Ethernet/IP and many others. Besides Ethernet signals, they are also able to transmit the signals of further field bus systems. The SR120 Ethernet Contact slip ring offers its users up to 20 channels that can be freely combined for transmitting loads, signals and Ethernet data. The channels for the required electrical power are approved for max. 400 V AC with a current up to 20 A. The signal channels transmit up to 48 V/ 8 A.

The media lead-throughs for air or hydraulics can operate both according to the one-way and to the twoways principle. "The contact, based on copper-to-bronze for load transmission and on silver-to-noble metal for signal transmission, ensures clear and reliable communication between the static and the rotary section. With a service life exceeding 500 million revolutions, this slip ring meets all main requirements of the market, mainly oriented on robustness" according to Gunter Kahrs.

Shielding ensures reliable interference immunity 
The SR120 slip ring has a modular structure with a three-chamber system. All chambers are both separated physically from each other and shielded internally. Size, shape and shielding form a constructive unit that ensures high availability of all media, of the data as well as of the intermediate circuit voltage, which all pass through the slip ring.

The data frame of the Industrial Ethernet communication is not affected by electromagnetic interferences. Experience has shown that the search for the cause of EMC problems can lead to long standstill periods, as they are very difficult to detect for the machine user. The SR120 help avoiding this failure cause.

Use on a balancing machine

In a balancing machine, a highly intelligent measuring and control device monitors both the quality and the accuracy required for shaft compensation and balancing. High measuring accuracy and high-resolution imaging methods determine the data that will be used directly to implement the changes in mass distribution required for balancing. All of the data can be retrieved permanently in real time: from statistical calibration, polar optimization and - in case of unsymmetrical shafts - differential angle measurement.

Existing ambient interferences are detected. Every small adaptation is recorded during machine operation, such as pneumatic or electrical changes or the pressure that might appear during the process. The recording of all these parameters allows realizing repeat orders with minimum changeover times.

If unbalance occurs, the Override function sets the rotary speed to a non-critical range according to the occurring vibrations, and then regulates it back to the nominal speed. In this machine environment, networking via Industrial Ethernet brings in a first phase a significant efficiency and accuracy increase. In the long term, the user also benefits from time savings thanks to shorter set-up times and less maintenance work.

Tailored solutions

Machine modularization is today an imperative for efficiency and costs saving and requires a decentralized structure for automation solutions. Gunter Kahrs explains "For these reasons, the SR120 slip ring is a tailor-made solution for all industrial areas where the requirements for high data rates and fast availability are increasingly gaining importance."

These robust slip rings transmit many bus standards such as Profibus, ASI-Bus, DeviceNet, Ethernet/IP, protected against failures and without loss. Besides a wide variety of installation possibilities, a matched program of media options for air, load, signals and hydraulics is completing this series to make it a universally usable system.