AN ELECTROMAGNETIC SENSOR FOR SLAB IDENTIFICATION BY DETECTING THE GAPS BETWEEN CONTIGUOUSLY MOVING SLABS ON A ROLL TABLE/CONVEYOR

摘要

Thus according to the basic aspect of the present invention there is provided an electromagnetic sensor for on-line slab tracking / identification by detecting gaps between contiguously moving slabs on a roll table/conveyor comprising: An electromagnet means operatively connected to a power source for generating magnetic Iines of force between the free ends of the electromagnet means; A search coil selectively disposed above said roll table/conveyor carrying moving slabs such that any change in the flux pattern and strength of the field of said electromagnetic lines of force in its vicinity due to said moving slabs with intermittent gaps there between induces a pulse of voltage into the search coil; and A signal-processing unit operatively connected to process said induced voltage signal and identify slab gap(s) encountered. Importantly, the above sensor of the invention comprises slab Identification logic involving counting two successive slab gaps between contiguously moving slabs over roll table and generating a slab count. The signal processing unit comprise means for filtering induced voltage signal for unwanted noise signals, amplifier means for identifying a single square wave pulse whenever a single slab gap is encountered. Preferably, the said signal processing means further comprises means for counting and establishing the slab identity. For the purpose the signal-processing unit comprises of electronic circuitry adapted to function for raw signal filtering, amplification, comparison, logic checking, level transfer and slab counting. Moreover, the sensor means comprising the electromagnetic sensor comprises of a single 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 assembled as a single sensor unit, non magnetic mounting brackets and hook means for selectively mounting said sensor unit such as to dispose said search coil selectively above said roller/conveyor carrying the slabs. In accordance with a preferred aspect the electromagnetic sensor comprises differential length pole blocks adapted to be selectively attached in varying lengths preferably 20, 30 and 40mm lengths to get differential pole lengths. The DC power supply source required by the electromagnetic sensor comprises standard regulated variable dc power supply unit with provision of variable power supply from 0-30 Vdc with 3 Amp capacity with preferable rated capacity of the sensor 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 electromagnetic sensor comprises: comparator means respectively for forward and reverse gap detection and interlocking means for blocking wrong detections in either direction; counter means comprising up counter adapted to count gaps in forward direction and down counter adapted for counting gaps in the reverse direction, said counters operatively connected to LED based display unit for displaying absolute number of slab counts at any point of time.