THE dynamic, self-learning blanking function of SICK’s C4000 Palletiser safety light curtain offers safety, availability, supplementary functions and installation and operating cost benefits of up to 40% compared to conventional muting solutions.
The device detects persons entering the hazardous areas of machines but permits the transport of material in and out of such areas. Pattern detection, for example, of pallet feet or goods on pallets, obviates the need for supplementary sensors and guarding measures.
The C4000 Palletiser’s electro-sensitive protective equipment corresponds to Type 4 according to IEC 61496 and SIL 3 in compliance with IEC 61508.
The safety light curtain is designed for access protection during automated material transport, requiring no additional sensors, swing doors or indicator lamps. The drop in frequency of device faults (corresponding to the reduction in the number of components) results in a significant increase in plant availability.
The C4000 Palletiser has a self-learning, dynamic blanking function for pattern detection that reliably differentiates between transported materials and persons during transport into the protected area.
Pattern detection can take place in one of two ways depending on the system version - Standard or Advanced:
1) via the size and closed shape of an object, for example, the goods on a pallet.
2) via the size and number of several objects, for example, the feet of a grid box or pallet, or the number of individual goods transported at fixed distances to one another.
In the first scenario, the blocking of individual light beams and a minimum size are monitored and evaluated. The automatic detection of unitised goods, requiring no complex programming, offers maximum operating flexibility. The difficult adjustment of muting sensors for differing batches, which would normally be required, is completely unnecessary.
In the second situation, self-learning detection of object patterns, for example, differing pallets, takes place during simultaneous distance monitoring. In addition, the system also carries out a quality inspection during the access process, during which defective pallet or grid box feet (which could impair automated handling) are detected.
Both versions of the C4000 Palletiser are delivered with pattern detection of goods and Europallets already activated. The teaching-in of a new pattern takes place automatically during mixed operation.
The systems can process transport direction signals. This permits both the detection of the transport direction of goods or pallets and the switching of the light curtain from pattern detection to protective mode in the case of a belt standstill.
Both functions contribute towards minimising the necessary safety distances - important wherever mounting space is limited.
The C4000 Palletiser can also be used in Ex-zones 2 or 22 with the optional ATEX Kit.
The C4000 Palletiser’s safety light curtain monitors hazardous areas on automatically operated machines, such as robots, turntables, palletisers, insertion equipment or strapping machines. These are often integrated into automated material flow concepts, for example, objects such as loaded pallets, workpieces, containers or car shells on skids are automatically transported into the working area of the machinery and out again.
The permanently active safety light curtain uses the data from the self-learning distance monitoring to reliably differentiate between persons and material.
Information on the maximum permissible size of an object, entry into and departure from the protective field, self-learnt object distances within the protective field and their changes, among other data, are used for detection and for differentiating between persons and a transport vehicle. Just one of these switching criteria is sufficient to bring the hazardous machine movement to a stop.
Up to now the usual method for safeguarding entrance and exit locks has been safety light curtains with their connected muting sensors, muting lamps and sometimes also swing doors. Time-related and logical conditions are checked using muting sensors, on the basis of which system can distinguish between persons and material. This solution has proven itself in industry but involves greater material and installation costs. Thus both pattern detection and muting have their advantages, based on the particular operating conditions present.
There remains, however, the question of which technique is to be used when. The advantages of pattern detection include, above all, minimising installation costs and the number of components, providing maximum availability. Only the actual safety sensor is required.
However, an unambiguous detectability of the pattern of goods or transport aids is essential. Therefore muting is the right solution when pattern detection is inappropriate, but objects still need to be detected by muting sensors and the switching frequency, which can be evaluated in terms of both time and logic. In practice, both alternatives are often found side by side.