GB876754A - Volumetrically-operating measuring out and dispensing machine having means for maintaining the weight of discharge constant - Google Patents

Abstract

876,754. Electric control systems. HESSER, MASCHINENFABRIK-A.G., FR. Jan. 11, 1960 [Jan.12, 1959 ; Jan. 22, 1959], No. 936/60. Class 40 (1). [Also in Group XL (b)] In order to dispense loose material in batches of equal weight the density of the material is directly or indirectly determined in the dispensing machine and the density determination used to adjust the capacity of the measuring out members to maintain the weight in each batch constant. In one embodiment the loose material is fed down a hopper 1 to a dispensing machine generally indicated at 2. A source 4, of beta or gamma radiation, is arranged on one side of the hopper and the amount of radiation received by the Geiger tube or ionization chamber detector 5 is dependent on the density of the material. The detector output is applied to a comparison device 6 and any out of balance signal used to operate a double clutch 12 in the appropriate direction to cause the machine drive to drive wheel 15 through worm 14 to a position where the input from potentiometer 21 to comparison device again balances the detector output. The clutch is then released. Wheel 15, besides operating potentiometer 21, also moves linkage 14 to control the volume of the measuring chambers 1 in such a way as to maintain the weight dispensed constant. A delay relay may be incorporated in the correction, circuit to ensure that correction is effected only when the material of changed density is actually being dispensed. Normally, however, the low rate of correction due to the worm drive is sufficient to prevent errors. Where the machine incorporates a device 27 to check the height of the contents of the filled packages so as to effect rejection of improperly filled ones adjustment may be extended to this device. As shown, the device is one in which light from a source 28 reflected from the top of the material in the package is directed to photo-cell 29 if the material level is at the correct height. Variation in volume to maintain constant weight will affect the height of material in the packages and, to ensure that packages are only rejected when filled with an incorrect weight, a vertically movable slider 31 carrying the light and cell units is adjusted by crank 37 coupled by lineage 36 to wheel 15. This compensates for density variations. Instead of moving the cell and light vertically as a unit, adjustment of their angular setting may be effected if preferred.