Safety is top of the curriculum at the University of Wels
Productivity and safety used to be seen as two contradictory goals, but this ceased to be the case some time ago. This is because intelligent safety controls help to avoid downtime and can allow maintenance work to be undertaken in hazardous areas – under strict supervision – without stopping the whole plant.
With safety having such central importance, it makes sense to start including it in the engineering degree curriculum – and this is something the University of Wels in Austria has done. In its Computer Integrated Manufacturing (CIM) laboratory, Rockwell Automation’s light curtains, safety mats and emergency stop switches help make sure that students and visitors are safeguarded from the installed robots. This is particularly important considering that, with one exception, none of the robots moving around the area is enclosed in any physical guarding. A compact Allen-Bradley SmartGuard 600 safety controller intelligently controls the various components
Until recently, safety was not a main focus in the university’s CIM laboratory. “We did have a list of do's and don’ts for the students – a sort of code of conduct in the lab,” admits Professor Reinhardt Busch, Wels University’s Production Engineering Department Head, “but we didn’t have any safety technology as such.”
“We wanted a flexible solution that allowed us to switch between several different modes of operation,” explains Hans-Jürgen Becherstorfer, Chief CIM Engineer. “It was important to not only secure the whole plant, but also to exclude certain machines for practice purposes.”
The system is made up of several practice stations including robots and image recognition, a control and visual display system, central and remote Programmable Logic Controllers (PLCs), a safety PLC, an offline robot programming module, and a station for programming the Profibus-based RFID system. Every automation and mechatronics student at Wels University must master each of these stations in the course of a semester.
Under the guidance of the Chief CIM Engineer and a tutor, the students also have to achieve specific goals at each stage. From October 2009, an additional task will be added: “Integrate laser scanners, light curtains, safety mats and emergency stop devices with the safety PLC and create a functioning safety application.”
Programming the Rockwell Automation safety solution is facilitated by the predefined modules and is more a case of setting parameters than actual coding. Describing the programming principle, Martin Berger, commercial engineer motion & safety at Rockwell Automation says: “The user simply selects the desired inputs and predefined function blocks from the library, then connects them to the output by simple drag and drop. SmartGuard 600 makes it simpler and quicker to program even complex and sophisticated safety applications. If there are not enough on-board IOs for large applications, users can just increase the number of inputs and outputs using decentralised IOs on DeviceNet.”
In the CIM lab, two SmartGuard 600 safety controllers are at the heart of the recently-installed safety solution. Nine decentralised IO stations have been integrated via DeviceNet, providing a total of 192 inputs and outputs for this application. Extensions can be added whenever required. SmartGuard 600 can also communicate with an overarching machine control system via DeviceNet. It mainly shares status and diagnostic data so that the standard PLC can supply information about the point at which the safety circuit was interrupted.
Different ways to provide safety
Until recently, Wels University had chosen a simple method to prevent unauthorised entry to the CIM lab’s robot and production machine area during its open day. “We just blocked off the area with an array of tables, plant stands and potted shrubs,” admits Prof. Busch with a smile. Things have come a long way since then. With one exception, the robots moving around the area are not enclosed in any physical guarding, so safeguarding is now provided by safety light curtains, laser scanners, safety mats and safety interlock switches. “Rockwell Automation offers a broad range of safety products, making it easier to find the right solution for any application,” comments Martin Berger from Rockwell Automation.
Rockwell Automation has installed several different safety solutions in the CIM laboratory. There is an Allen-Bradley Guardmaster SafeZone safety laser scanner beside the SCARA station that is used for configuring and programming the warning and alarm fields according to the safety levels required. The pendulum arm robot has a MatGuard system at its feet. “The advantage of the safety mats is that they last for a very long time and can withstand harsh conditions,” says Berger. “They can handle three tonnes with no problem.”
In an emergency, safety can be provided rapidly by a rope (cable-operated) pull switch, similar to a skydiver’s ripcord. Berger describes it: “Our Lifeline rope-operated interlock system is ideal for conveyor belt applications. It helps safeguard a worker in the event of the worker being caught up in something on the conveyor and be dragged along it or pulled onto the belt.” The students working in Wels University’s CIM lab are protected from the dangers of the conveyor belt with a pull switch on one side and a safety light curtain on the other.
“We provided the university’s CIM lab with various safety components and the corresponding engineering services,” notes Ludwig Haslauer, Sales Director of Rockwell Automation in Austria. “Our goal was to give the students an introduction to the wide range of safety systems and applications available. Once they start work, they’ll hopefully think about implementing safety measures right from the outset!”
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