Electromagnetic Sensor For Slab Identification By Detecting Gaps Between Consecutive Moving Slabs On Roll Table

Thus according to the basic aspect of the present invention there is provided anelectromagnetic sensor for on-line slab tracking / identification by detecting gapsbetween contiguously moving slabs on a roll table/conveyor comprising:An electromagnet means operatively connected to a power source for generatingmagnetic Iines of force between the free ends of the electromagnet means;A search coil selectively disposed above said roll table/conveyor carrying moving slabssuch that any change in the flux pattern and strength of the field of saidelectromagnetic lines of force in its vicinity due to said moving slabs with intermittentgaps there between induces a pulse of voltage into the search coil; andA signal-processing unit operatively connected to process said induced voltage signaland identify slab gap(s) encountered. Importantly, the above sensor of the invention comprises slab Identification logicinvolving counting two successive slab gaps between contiguously moving slabs overroll table and generating a slab count.The signal processing unit comprise means for filtering induced voltage signal forunwanted noise signals, amplifier means for identifying a single square wave pulsewhenever a single slab gap is encountered. Preferably, the said signal processingmeans further comprises means for counting and establishing the slab identity. Forthe purpose the signal-processing unit comprises of electronic circuitry adapted tofunction for raw signal filtering, amplification, comparison, logic checking, leveltransfer and slab counting.Moreover, the sensor means comprising the electromagnetic sensor comprises of asingle unit including the core of the electromagnet, main coil of the electromagnet,search coil to trap the said slab gap signal when a slab gap moves under it assembledas a single sensor unit, non magnetic mounting brackets and hook means forselectively mounting said sensor unit such as to dispose said search coil selectivelyabove said roller/conveyor carrying the slabs.In accordance with a preferred aspect the electromagnetic sensor comprisesdifferential length pole blocks adapted to be selectively attached in varying lengthspreferably 20, 30 and 40mm lengths to get differential pole lengths.The DC power supply source required by the electromagnetic sensor comprisesstandard regulated variable dc power supply unit with provision of variable powersupply from 0-30 Vdc with 3 Amp capacity with preferable rated capacity of thesensor being 0.8 Amp at 24Vdc. The output signal of the sensor comprise standard+12V dc and relay adapted for general purpose applications.In accordance with another aspect of the present invention the electromagneticsensor comprises:comparator means respectively for forward and reverse gap detection andinterlocking means for blocking wrong detections in either direction; counter means comprising up counter adapted to count gaps in forward direction anddown counter adapted for counting gaps in the reverse direction, said countersoperatively connected to LED based display unit for displaying absolute number ofslab counts at any point of time.

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