Patent GB-315122-A (GB)
Title: Improvements in automatic weighing machines
IPC: G01G11/00
Filed: 1928-08-09
Abstract: 315,122. Richardson, H., and Murray, S. G. Aug. 9, 1928. Automatic - feed weighers. - An automatic weighing machine comprises a conveyer having means for operating it continuously, weighing means supporting a portion at least of the conveyer, and a travelling feed conveyer arranged to feed material to be weighed to the continuouslyoperating conveyer and having means for advancing it intermittently under the control of the weighing means whereby separate weighed charges of material are formed successively on the continuously-operating conveyer. The weighing conveyer 3, Fig. 1, and its electric driving motor 14 are mounted on a frame. 16 supported on a system of weighing levers 20 terminating in a weighbeam 29. Above the weighing conveyer is arranged a feed conveyer 2 mounted, together with its driving motor 6 upon a frame 8 pivoted on a pin 10. The feed conveyer receives material from a feed hopper 9 and drops it onto the righthand end of the weighing conveyer which then carries it in the opposite direction and discharges it. When a full charge has fallen upon the weighing conveyer, the weighbeam 29 descends to an horizontal position and a mercury switch. 34 opens the circuit of the motor 6 and stops the feeding conveyer. As the weighed charge is leaving the weighing conveyer the weighbeam rises and starts the feed conveyer to weigh out a further charge. In the event of a shortage of material in the hopper 9 the frame 8 tilts and a mercury switch 36 thereon stops both the motors 6 and 14. In a modified machine where the feed hopper is carried on the frame 8 and the two - conveyers move in the same direction, safety means are provided for stopping the machine, if the feed to the weighing conveyer is soreduced by clogging at the outlet of the feed hopper that the weighbeam fails to descend and stop the feed motor 6. These safety means comprise a pivoted shoe bearing upon the layer of material on the weighing conveyer and connected by a toggle linkage to an additional switch pivoted on the frame. In the normal action of the machine a pin on the weghbeam breaks the toggle each time the weighbeam descends and thereby allows the pivoted shoe to rise under the pressure of the next batch of oncoming material without displacing the additional switch. If, however, the flow of material is unduly reduced by choking of the feed outlet the weighbeam fails to descend and break the toggle linkage and in consequence the rise of the pivoted shoe rocks the switch and stops the motors and the machine. In the event of foreign matter jamming the weighing conveyer and causing undue strain on the driving means a driving-pin connecting a pair of coupling members is arranged to break Relative movement consequently takes place between the coupling members and allows a cam surface to rock the additional switch referred to above and thus stop the machine. If the material discharged from the weighing conveyer accumulates within the receiving hopper, thus mixing the successive weighed charges, the pressure of material pushes back a hinged plate at the side of the hopper, and the hinged plate acting through a switch, stops the machine. Instead of employing a weighbeam 29, the weighing levers 20 may be connected to a dial spindle turning against the resistance of balance weights suspended from a cam. An adjustable arm on the dial spindle carries a pivoted mercury switch which tilts suddenly under the impetus of a rolling hall and stops the driving motor of the feeding conveyer when a full charge has been delivered to the weighing conveyer. The return of the dial spindle during discharge from the weighing conveyer automatically starts another weighing operation. The weighing conveyer may be adjustable endwise beneath the feed conveyer to shorten the time of weighing when dealing with small charges. In a modified apparatus, Fig. 8, for weighing out charges containing two different materials in predetermined proportions, two feed hoppers 109, 109<a> are provided each with a feed conveyer 102, 102<a>mounted in the manner previously described. The feed conveyers discharge on to a common weighing conveyer 103 connected by weighing levers to a dial spindle 77 which carries as previously described a switch 82 for stopping the feed conveyer 102 when the requisite weight of material has been fed from this conveyer. At this moment, a second mercury switch carried by the dial spindle, starts the feed conveyer 102<a> and maintains the feed until the total charge is completed whereupon the feed conveyer 102<a> is arrested bv a further movement of the dial spindle and the weighing conveyer commences to discharge, a further weighing operation being automatically initiated by the subsequent rise of the weighing conveyer. The mercury switches may be adjusted to vary the proportions of the two materials.