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INDUSTRIAL SAFETY SENSING applications in robotic welding
Industrial safety is probably at the top of most system integrators’ check lists. This is due in part to the legal penalties imposed on those breaching regulations but also in the fact that modern engineers are more highly educated in safety principles than in any previous generation. Panasonic explains further
T
here are many dangers or hazards within the manufacturing
environment and a great deal of text and instructions are aimed at both intrinsic safety systems to cover generic areas and dedicated systems to cover very specialised areas. One area that certainly causes a good deal of interest is that of safety systems and industrial robotic systems in the automotive manufacturing environment. However, worldwide there are only a
limited numbers of vendors who supply both industrial safety sensors and industrial robotic systems. Panasonic is one such company that supplies products on a global level to companies involved in all levels of automotive manufacturing. Its range of safety light guards and sensing products are used at many levels in conjunction with their robotic welding systems. Engineering processes requiring
industrial welding robots are common place within the automotive industry since they offer high process speeds, quality and repeatability to the manufacturing process. However, a problem associated with the process is that of extraneous light caused by sparking and arcing in a welding environment. Although not immediately obvious, safety light guards can be falsely triggered by such light sources and so those offering immunity to these effects are indispensable when used in such an environment. The Panasonic SF4B series of safety light guard offers immunity from false triggering and so allows optimal performance for protecting personnel in the working vicinity of welding robots.
APPLICATIONS A typical application would see a safety light guard used in the protection of a welding cell where a safety system is configured to use safety door switches, safety light guards and safety laser scanners. The SF4B series safety light guard system fulfils all the standards required
8 APRIL 2014 | AUTOMATION
from the Machinery Directive (2006/42/EC) achieving a performance level of PLe and a safety integrity level of SIL3. Of course the global nature of
automotive manufacture means that production facilities are located all over the world making it necessary that all sites and products meet industrial safety requirements on an international basis.
ELCA For those unfamiliar with the principals involved in safety light curtain sensors a brief overview may prove useful. A safety light guard works like multiple thru-beam light arrays with many emitters and receivers located in a robust housing for use in tough, harsh environments. Within a robotic weld shop environment there are many examples of extraneous light and it
Right and below: an area that certainly causes a good deal of interest within the manufacturing environment is that of safety systems and industrial robotic systems in the automotive manufacturing environment
narrow light spectrum, there are instances where extraneous light can cause a false alarm leading to a safety shutdown of a machine even though no safety relevant event has occurred. The ELCA function implemented into the
design of the SF4B series safety light guard is designed to prevent such a loss and is realised by synchronising the emitter and receiver of the device with each other. Every emitter/transmitter pair is processed serially and if any extraneous light falls on the receiving element then the safety light guard does not trigger and alarm immediately, but performs a second scan. Only if the same condition is detected during the second scan does the sensor switch to an alarm mode, placing the robot controller into a shutdown condition. The safety light curtain will only output an alarm condition when two occurrences of the same event are detected. If there is a danger of welding spatter or beads contaminating the sensing surface of an SF4B Light Guard, an accessory in the form of a replaceable anti-spatter front protection cover can be fitted to the transmitter and receiver of each device.
is well understood that a traditional light guard can interpret these conditions as an unsafe condition leading to a machine shutdown. Panasonic and one of the largest automobile manufacturers have worked closely together to develop a product that combats this situation referred to as the ELCA function, (Extraneous Light Check and Avoid). This function not only eliminates mutual interference from other SF4B Light Guards, but also from the other sources of extraneous light that can bring a machine to a stop. Although the receiving element in a Safety Light Guard works in a very
SUMMARY The safety light guard is one of a range of safety products offered from Panasonics portfolio. Apart from the SF4B series with its metal enclosure, the product range also includes the SF2C/SF4C series housed in a polycarbonate enclosure and currently one of the smallest light guard products available on the market. In the workplace, safety means going
home at the end of the day as fit and healthy as you were when you arrived at the beginning of your day. Panasonics’ safety light guards certainly help achieve this aim.
Panasonic
www.panasonic-electric-works.co.uk T: 01908 231 555
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