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Automation Technologies 3/2015

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Automation Technologies 3/2015

Safety at all costs

Safety at all costs About Company name: Euchner GmbH + Co. KG Headquarters: Leinfelden, Germany Employees: 600 worldwide Products: safety switches with and without guard locking, safety relays, small safe control systems, enabeling switches, hand-held pendant stations, electronic key system When building a new entry buffer for a tandem line last year, Salzgitter Flachstahl GmbH had to secure a total of 39 hazardous and critical control areas. Euchner’s transponder coded safety switches CET with guard locking was used at more than 50 access points. he expansion of the tandem line by a continuous T entry buffer – ESTA, was one of the most important investment projects of Salzgitter Flachstahl GmbH last year. With more than 4,700 employees, 4.5 million metric tons of crude steel and the sales volume of € 2.8 billion in the year 2012, Salzgitter Flachstahl GmbH is the largest steel subsidiary in the Salzgitter Group. In an integrated smelter, the company produces hot wide strip, band steel, cold-rolled strip and surface-coated products measuring from 0.4 mm to 25 mm in thickness and up to 2,000 mm in width. The product portfolio includes drawing steels, deep-drawing steels, special deep-drawing steels, mild steels and fine-grain steels, as well as high-strength and superhigh strength steels. The most important clients for Salzgitter Flachstahl GmbH are the Automobile manufacturers and their suppliers, tube and pipe manufacturers, cold-rolling plants and the domestic-appliance industry. In the newly expanded tandem line, in order to maintain the continuous supply of steel strips to the rolling operation, the coils are welded together in a complex process. Along with other advantages, the technology serves to reduce off-gage length and most importantly increase the plant’s overall efficiency. Movable safety guard required During the ongoing operation the tandem line must not be entered. To ensure safety at all costs, the need for a safety guard arises. At Salzgitter Flachstahl, after a careful analysis of hazardous areas and critical entry points, the ESTA sub-project director Torsten Fingas reports that “We identified a total of 39 hazard areas in the vicinity of the new entry buffer.” To equip the plant for maintenance purposes the fence around it is provided with more than 50 access points comprising swing doors and sliding doors. These are the access points, which, require reliable safety switches capable of withstanding the harsh conditions of the steel making industry. The decision AUTOMATION TECHNOLOGIES 3/2015

COMPONENTS AND SOFTWARE to use the CET3-AP from Euchner was easy. For more than 60 years, the family-run business based in Leinfelden- Echterdingen has stood for practical, simple and customer- oriented automation solutions. As early as in the mid-80s, Euchner laid the foundations for the safety switches and systems based on a unique combination of electromechanics and transponder coding that now belong to the product range. The transponder-coded safety switch with guard locking and safe guard lock monitoring in use at Salzgitter Flachstahl forms a self-contained safety solution. Versatile in use The CET is used in securing safety doors of machines and installations for the protection of persons and processes. Thanks to the guard locking function with guard lock monitoring, the CET is also ideal in case of overtravelling machine movements. It is a very robust metal housing allows the CET to be used in the harshest environmental conditions. It achieves a locking force of 6,500 N in the locked state, which is particularly advantageous for large and heavy doors. In the version with double insertion slide, the CET is perfect for use with swing doors and rotary tables. Functionality The CET is mounted on the fixed part of the safety guard, and the actuator with its spring-loaded plunger and transponder on the moving part. When the safety guard is closed, the plunger of the actuator is guided into a recess via the insertion slide of the CET. The recess also contains the read head. It detects the safety door in closed position and in locked position. The internal evaluation electronics releases the safety circuit when the safety door is locked. A start button and a feedback loop can be optionally integrated. The Euchner safety switch also offers a versions with mechanical release, lock out release, wire front release and escape release. These features enable the personnel accidently locked in the operations area to open the locked safety guard from the inside in case of an emergency. The CET safety switch can be installed in any position. But Euchner recommends the installation position with head downwards as it achieves safety category 4 in this position and safety category 3 with the head in upward position. The safety category 4 and a performance level PL e according to EN ISO 13849-1 means the Euchner CET gives a 2 semiconductor output with internal monitoring, pulse switching and short circuit proof output. “This means that no other safety measures are needed on the door,” explains Bernhard Scholz, sales engineer at Euchner. Emphasizing on the excellent customer support provided by Euchner, Torsten Fingas concludes that “The device offers convincing technology and an attractive price- to-performance ratio. The safety system has been operating flawlessly since the new entry buffer was put into operation on the tandem line. We wouldn’t hesitate to install the CET again.” With all the safety features that Euchner’s safety switch offer, one can say Euchner is definitely more than safety. 02 The CET safety switch provides protection according to PLe 01 The plant is accessed through one of the more than 50 doors


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