GB1511484A - Method and apparatus for grading bodies and/or particles for size - Google Patents

Abstract

1511484 Counting particles in different size ranges REXNORD Inc 24 July 1975 [2 Aug 1974 2 July 1975] 34150/74 and 27826/75 Heading G1A [Also in Division G4] Stones X to be graded fall between an infrared source 11 and detectors 13, 14, 15 each comprising an array of elements such as photo-transistors, the number of detectors obscured simultaneously with the lowermost detector determining the size range of the stone. The photo-transistor may be placed at the ends of fibre-optic light guides the other ends of which receive the radiations. When any one photo-transistor is obscured the other transistors in the row and column containing the obscured transistor are electronically "obscured", the number of obscured columns then determining horizontal dimensions of the stone. A logic circuit 20 delivers pulses to counters 21 to 23 depending on the size of stone and to counter 24 for every stone counted. The arithmetic scaling unit may reset the counters whenever a hundred stones in all have been counted so that the percentage of each size is displayed by electronic number units 29 to 31. A further set of outputs from circuit 20 are taken to a circuit, Fig. 4 (not shown) for displaying cumulative totals for each size of stone the total number of stones to be examined being pre-selectable by a divisor selector (32) in the range 10<SP>3</SP> to 10<SP>6</SP>. Each detector may comprise a single row of elements, Fig. 6 (not shown). The apparatus may be positioned at the end of a conveyer belt and be used to automatically control crushing machinery to maintain the size and count of stones approximately constant. A single read-out console, Fig. 5 (not shown) may be switched between two or more sensing heads to monitor two or more crushers, or a single head may be mounted on a traverse between crushers.