Patent GB-962175-A (GB)
Title: Apparatus for stacking and weighing sliced food products
IPC: B26D7/30
Filed: 1962-03-06
Abstract: 962,175. Separating or sorting by weighing. UNEXCELLED CHEMICAL CORPORATION. March 6, 1962 [March 6, 1961],No. 8631/62. Heading G1W. [Also in Divisions A4, B8 and G3] An apparatus for use with a food slicing machine comprises a stacker for receiving and stacking delivered slices, a counter for counting the number of slices received, a stacker moving mechanism controlled by the counter to move the stacker on receipt of a predetermined number of slices to a new position for both stack delivery and receipt of further slices, a conveyer to receive the delivered stack, a weighing machine responsive to stack weight, and a path selecting mechanism controlled by the weighing mechanism to select the path taken by a stack according to whether it is underweight or not underweight. GENERAL. Food such as meat roll is fed forward on the slicing machine 31 (Fig. 1) by a hydraulically operated feeder 35 to a rotary spiral shaped blade 36 and thence to a stacker 100 (Fig. 7) which is arranged to receive and stack a number of slices on one of four surfaces and then rotates through 90 degrees to deposit the stack on an endless conveyer 104 fixed to a weigh scale 108 (Fig. 5) the number of slices being related to the time interval in which the stacker 100 is stationary as determined electronically by a circuit (Fig. 17). The load on the scale determines the degree of coupling between the windings of a differential transformer 472, the transformer core being movable and fixed to the scale mechanism. An oscillatory signal is fed to the transformer primary and the secondary output, being related to the load, is used to operate relays (see circuit Fig. 18) such that if the load is underweight a reject conveyer 110, to which it is passed, is lowered and the load from thence is passed to an underweight conveyer 118. If correct or overweight the conveyer 110 is not lowered and the load passes on to a conveyer 112. FOOD FEED. The food feeder 35 is moved forward or backward by hydraulic mechanism including a cylinder 46 (Fig. 2 not shown) and piston 47, the speed of movement of which is adjusted by varying the orifice in a valve 64 by means of solenoids 418, 438 (Fig. 18) and (Figs. 14 to 16 not shown). Feed movement can be started or stopped by means of solenoids 504, 506 on a control valve 54. A switch 524 (Fig. 1) on the slicer operated by the feeder gives indication when the food is in position to be cut. The thickness of slice is proportional to the feed rate. WEIGHING AND WEIGHT CORRECTION. (Figs. 5, 18) The weighing mechanism comprises the scale conveyer 104 which is supported by a tube 170 on a scale 108. Cantilevered flexible plates 462, 464 carry a weight head 466 connected to tube 170 also the damper 468 and the core 470 of a differential transformer 472. The transformer windings 474 are fixed to the frame of the scale. Movement of the core varies the coupling between primary 474a and secondary 474b. Primary 474a is fed from an oscillator amplifier unit 742. The resultant output from the secondary 474b is in the form of two anti-phase signals which are respectively applied to two identical amplifiers 744, 744<1>. Amplified signals are applied through capacitors 810, 810<1> to identical voltage detector circuits 820, 820<1> comprising thyratrons 818, 818<1>. A second signal is applied to the detector circuits, to the screen grids of the thyratrons from the oscillator amplifier 742. If the load on the scale is of correct weight the signal applied to its control grid is such that thyratron 818 will fire. If overweight the signals applied to the control grids of 818 and 818<1> is sufficient to cause both thyratrons to fire. If underweight neither will fire. When power is applied through lines 700, 702 a relay 706 is energized, and if relay 610 (Fig. 17) is unenergized and contacts 610a, 610c are as shown, the contacts 706a,706b,706e,706d thus will open preventing, energization of relays 704, 708. At a predetermined time after delivery on the scale conveyer of a load the relay 610 is energized and its contacts 610a, 610b, 610c change over and relay 706 is de-energized. The scale is then brought into play and a potential is applied to thyratron 818 through relay 704. If a stack is underweight 818 doesn't fire, contacts 704a, 704b will remain closed and 704b, 704c will open, solenoid 418 will be energized and act to turn shaft 402 (Figs. 14 to 16 not shown) thus increasing the valve 64 orifice, to increase the rate of food feed and thickness of slice delivered; also the reject solenoid 360 would be energized (see reject conveyer). If the stack is overweight relays 704, 708 are both energized and hence also the solenoid 438 which acts to decrease the valve 64 orifice and thickness of slice. If the stack is of correct weight the relay 704 is energized but 708 is not, so that neither of solenoids 418, 438 are energized. For operation of conveyers see Division B8. SLICE COUNTING (Fig. 17). A switch 656 operated by the slicing blade is open when the blade is cutting and the potential applied to the screen grid of tetrode 608 keeps it cut off. When a full slice is cut the switch closes and a voltage pulse is applied to the screen grid of 608 and if a capacitor 644 has discharged sufficiently through an adjustable grid bias resistor 642 the tetrode 608 fires and the relays 510, 542 are energized. Adjustment of the bias resistor 642 adjusts the time interval before the tetrode 608 fires and thus determines the number of slices cut before the turret is moved a step to discharge the slices and the cutting of the next stack of slices is commenced. Specifications 853,760, 945,260, U.S.A. Specifications 2,812,792 and 2,903,032 are referred to.