Patent GB-931001-A (GB)
Title: Improvements in and relating to continuous weigh feeders
Inventor: ATKINS JOHN HARRY CLAPHAM
IPC: G01G11/00
Filed: 1959-11-30
Abstract: 931,001. Weighing-apparatus. BAKER PERKINS HOLDINGS Ltd. Nov. 25, 1960 [Nov. 30, 1959], No. 40602/59. Class 143. [Also in Group XXX] A continuous weigh feeder, operable in conjunction with a controlled-discharge hopper and presettable weighing mechanism which governs the discharge rate of the hopper, includes a section whereat the flexible conveyer belt is supported from underneath by a weighing platform arranged cantilever-wise from a pivot such that the free, swinging end is immediately or closely adjacent to the delivery of the hopper and its pivotal axis is remote therefrom. The conveyer belt 3 is driven in the direction 16 whereby its lower run is in tension due to the drive. The upper run is supported by fixed backing plates 10, 11 and, in the gap between the backing plates, passes over the weighing platform 4. The platform 4 is arranged as a cantilever fulcrumed on a shaft 12, its free end 13 being near the outlet from the hopper 2, which is controlled by gate mechanism 6. To avoid drag, an auxiliary belt 17 has its upper run between the backing plate 10 and the under surface of the upper run of the belt 3 and assists the drive of the belt 3 so as to give a pushing action to the material-carrying portion 9 of the belt. The tracking of the belt 3 is adjustable due to the construction of the end roller 8, Fig. 4, the ends of which are tapered at 21 and which is arranged so that its axis may be swung about a pivot 20 and locked in position. The weighing mechanism, Figs. 5 and 6, comprises, firstly, a dummy cantilever arm 25, fulcrumed on the end of the shaft 12 whereby it initiates the movement of the table 4 and, secondly, a steelyard fulcrumed at 46, its short arm 27 being connected to the end of the arm 25 through a yoke 26 and its long arm 32 carrying, at its end, a masking plate 36 which can move across the face of a photoelectric cell 35. The weight is preset by a movable and/or variable main weight 29 and a rider weight 30. The rider weight 30 is arranged to be moved along the long arm 32 by the action of a lead screw 43, attached to or comprising the steelyard arm 32, which is rotatable from a knob 47, outside the weighing machine, through gearing 44, 45. The rider weight 30, Fig. 7, is a short metal tube 48 of a diameter such that its centre of gravity is below the axis of the lead screw 43 and with an annular rib 49 which engages the thread of the lead screw. There may be a similar rib at the other end of the tube. The weighing mechanism and the end bearing of the shaft 12 are enclosed in duct-proof housings 38, 37 and the shaft passes through dust-proof glands 41, 42. The photo-electric cell responds to the variation in intensity of light, from a lamp 33, caused by the movement of the masking plate 36, and causes a signal to be sent to one of two electromagnetic clutches. A cam-shaft is rotated in one direction or the other, according to which clutch is energized, resulting in a gate 51 being raised or lowered till its lower edge coincides with the upper or lower edge of a slot 52 in another gate 50, both gates covering the outlet from the hopper 2. If the desired weight of material is not then achieved, the cams on the shaft rotate other cams, through a lost-motion device, whereby the gate 50 is moved in the same direction as the gate 51, thus increasing the rate of feed correction. On reaching a point where the weight is slightly exceeded, one clutch is disengaged and the other engaged, with the result that the gate 51 moves in the opposite direction while the gate 50 stays still, the desired output being achieved by final operation of the gate 51 only. Specification 931,002 is referred to.