GB666306A - Automatic weighing machine and feed control means therefor - Google Patents

Abstract

666,306. Automatic feed weighers. WRIGHT MACHINERY CO. Aug. 23, 1949, No. 21844/49. Class 143 [Also in Group XXX] An automatic feed weigher has separate vibrating main and dribble feed troughs arranged so that the latter is directly above the former. Material is fed to the automatic feed weigher described in Specification 638,665 by means of a conveyer 15, Figs. 1, 4 and a pair of vibrating troughs 90, 93, the conveyer being driven by a motor 25 under the control of a normally closed microswitch 66, which is opened by movement of a shoot 44 when it contains sufficient material to pivot downwardly against the action of an adjustable spring (not shown), so that a regular flow of material is fed to a vibrating hopper 63. This hopper feeds the bulk feed trough 93, through adjustable doors 99, and has a tapering arcuate section extension 90 secured thereto which constitutes the dribble feed trough, this trough being so shaped that an even, fine flow of material will be discharged from its end and that all surplus material will be discharged therefrom into the bulk feed trough 93. In operation initial movement of the preloaded weighing apparatus 115 opens a normally closed micro-switch 118 in circuit with the bulk feed vibrator 96 which is thereby stopped so that the final weight is made up from the continuously vibrating dribble feed trough 90. Cut-off is effected by automatically pivoting a pair of doors 157, 157a on shafts 159, 161 which doors then form a temporary hopper in which the material collects ready for dumping into the weigh pan when they are re-opened at the commencement of the next weighing cycle. The mechanism for operating said doors comprises an electromagnet 147 which when energized, by closing of contacts 144, 145, on further downward movement of the weigher 115 releases a single revolution clutch 151 to effect raising traversing and emptying of one weigh pan and replacement thereof by the other as described in Specification 638,665, and simultaneously a cam 196, Fig. 7, is rotated to raise a yoke 188 against the action of a spring 199 so that racks 190 rotate pinions 192 operatively secured to the shafts 159, 161 causing the doors to effect first cut off and then, after the empty pan is in position, dumping of the material accummulated thereon. In a modification, Figs. 13, 14, one weigh pan 102a only is used and cut-off is effected by stopping the vibrator 78 operating the dribble feed. In operation initial downward movement of the weigher 108 opens micro-switch 118 so discontinuing vibration of the bulk feed trough 93, but on further downward movement of the weigher closing contacts 144, 145, a relay 303 is operated to disconnect the dribble vibrator78 so effecting cut-off and, furthermore to energize an electromagnet 147a which releases a single revolution clutch 151 to effect discharge of the pan, a cam 316 rotatable with the discharge operating shaft 152a opens a normally closed microswitch 301 which ensures that the feed will not restart on de-energization of relay 303, consequent upon rising movement of the weigher after the pan has been removed, until after the dumping is complete. The trunnions on the pan are each T-shaped so that the limb 105a of each can be engaged between a member 327 pivoted to an arm 328 at 329 and a block 333 secured to said arm 328, movement to the right of arm 324 consequent upon rotation of shaft 152a serving first to lock the trunnions between members 327 and blocks 333 then to lift the trunnions off the weigher, and finally to pivot the arms 328 about pivots 331 to effect dumping. In both embodiments the vibrators are fed with D.C. from rectifiers 125, 133, 125a 133a and control of the speed of vibration is effected by means of rheostats 128, 136, 128a, 136a. Specification 633,075 also is referred to.