By using the central UE 70 safety controller, the decentralized UE 21 I/O extensions as well as tactile and electro-sensitive protective equipment, the Austrian Mischek Systembau GmbH, a manufacturer of precast concrete elements, saw the realization of a complete solution that has improved not only safety but also the processes of the plant.

The entire project of modernizing the concrete component production in terms of safety technology was carried out by Unitechnik Cieplik & Poppek AG. For over 15 years, the company, specializing in automated logistics systems, has been cooperating with partners in mechanical engineering to automate the production
of precast concrete parts. The production of a precast concrete
component requires about a dozen process steps. Considering that a shuttering pallet measuring 3.5 x 13.5 m² and filled with concrete can weigh up to 22 tons, one realizes the importance of making the individual work place safe.

Safety and improvement of processes: the dual objective at Mischek

Every year, Mischek’s prefabricated parts plant in Gerasdorf near Vienna produces about 75,000 tons of concrete elements that are as high as a room and are used primarily in Viennese housing construction (large panel construction). Cleaning/oiling, automatic shuttering, shuttering supplementation, reinforcement/builtin components, packing, hardening, lifting – the transport between the different work stations occurs automatically, while many process steps are carried out by employees. In the course of a conversion of the facility to current automation systems, the safety technology at the ten circulation points and at additional processing or handling stations is scheduled to undergo modernization and restructuring in such a way that it contributes to an improvement of processes related to production logistics.

Suitable safety portfolio

At Mischek, ten dualbeam M4000 multiple light beam safety devices are used to guard the circulation stations as well as the vibrating station from entry. Another M4000 – in conjunction with a deflecting mirror column – provides doublesided monitoring of the tilting table for pallets. Well over a dozen i110 safety position switches with roller levers are deployed for checking the lattice gates between the transfer table and the different circulation stations. Safety switches of the i17 series with a separate actuator take care of monitoring the access doors.

Central: the UE 70 safety controller offers monitoring logic adapted to processes

The core of the system solution is the UE4470 safety controller, by way of which the main stopping circuits are operating. Via certified functional blocks, it allows interlinking multiple light beam safety devices, emergency stop switches and enable switches as well as doorand gaterelated safety requests in a logical way. During ongoing operations, the status, diagnostic, and error reports can be recorded and processed on site or via a network. For this purpose, the UE4470 is integrated into the communications structures of the entire facility by means of a PROFIBUS gateway. This means universal schemes toward machine safety can be implemented that also have a positive influence on the processes related to automation technology, e.g. on the performance and availability of the transfer tables. With a view to the complex tasks at Mischek, the UE4470 safety system was extended with the aid of decentralized UE4421 I/O units. With these IP 20 fieldbus nodes and their safe inputs/outputs, onsite integration of the safety devices was possible without any problems. One UE4421 each takes on the monitoring of signals from two adjacent processing stations; at the vibrating point and the tilting table, one UE4421 each is used. This approach meant saving substantial costs for cabling and installation.

Positive: the experiences with start-up

The people at Unitechnik arrive at a positive assessment regarding the use of the safety package that was coprojected and delivered by SICK and has been in operation at Mischek since January 2007. Programming proved to be very userfriendly. The possibility of testing the safety logic at the company location without hardware prevents unnecessary stress and loss of time on the construction site. At the same time, the solution with the UE4470 is so flexible that any additional monitoring functions possibly recognized on site can be supplemented logically and by sensors. For Unitechnik’s client Mischek, the comprehensive cooperation in terms of safety technology with SICK as a system supplier for sensor and control engineering has resulted in a customized and design-to-cost “safety solution” that now bears the CE label.