Patent GB-1309424-A (GB)
Title: Method of and apparatus for measuring and dispensing predetermined  amounts of powdered material
IPC: G01F11/24
Filed: 1970-03-11
Abstract: 1309424 Compressing powders PERRY INDUSTRIES Inc 11 March 1970 11575/70 Heading B5A [Also in Division B8] Apparatus for dispensing slugs formed by compressing measured quantities of powdered material, comprises a measuring chamber having an open end, a piston including a piston head disposed within the chamber and pervious to gas but impervious to the powdered material, vacuum means to subject the chamber to a negative pressure through the head during charging of the chamber with a predetermined quantity of material, means to effect relative movement between the chamber and the piston to eject the material from the chamber, and means for compacting the material before or after charging of the chamber to provide a slug within the chamber. As illustrated in Figs. 1 and 2, the apparatus comprises a hopper 35, and a metering wheel 33 comprising a plurality of radially disposed chambers 34 each having disposed therein a respective piston 42 biased by a spring (not shown) to engage a stationary cam 45. Bores 50 in the wheel are each associated with a respective chamber. A hub member 57 on which the wheel is mounted includes an arcuate groove 54 connected to a vacuum pump (not shown), and a bore 57 connected to a pressure gas source. When a chamber communicates with the hopper, the associated bore 50 communicates with the groove 54 such that a negative pressure is induced in the chamber to draw in a charge of material from the hopper. During passage of the chamber from the hopper to a discharge position, the chamber outer end will be closed by an anvil 56 and at this time the piston will be moved radially outwardly by the cam 45 to compress the material charge against the anvil. Before the chamber reaches the discharge position communication between the groove 54 and bore 50 will be broken, and at the discharge position the piston will be moved outwardly of the chamber whilst the bore 50 will communicate with the pressure gas source. The charge will then be deposited in a container. The containers may be moved in synchronism with the wheel to effect discharge from each chamber into a respective container. The anvil may be replaced by an endless belt (60) (Fig. 6, not shown). Where the powdered material is an explosive powder the anvil or endless belt is preferably formed of a resilient material, e.g. rubber or neoprene. The apparatus of Fig. 8 comprises a cylinder 71, and a piston 72 having a porous head 73 and a rod 73A. The cylinder is connected to a source of negative pressure 77 or a source of pressurized gas 78 in dependence on the position of valve member 83. In use the piston is moved relative to the cylinder 71 to define a measuring chamber 82, and the cylinder is introduced into a vessel 84 containing powder. Connection of the cylinder to the negative pressure source causes a charge of powder to flow into the chamber 82. The end of the cylinder is doctored, e.g. by passing over the edge of the vessel 84 and is then applied against a surface (85) (Fig. 10, not shown), e.g. of conductive rubber so that movement of the piston towards the surface will compact the powder charge. Subsequently the cylinder is positioned over a container, the piston is moved to a protracted position and pressurized gas is supplied via valve 81 to the cylinder 71 so as to remove the powder charge from the piston head. The apparatus of Figs. 14 and 19 comprises piston and cylinder units 91 mounted on a frame 93 which is supported on horizontally disposed slidable bars 97, each unit being associated with a respective powder container 130. The frame includes cross-bars 94, 95 vertically movable on posts 96. Coil springs (119) (Fig. 24, not shown) maintain the crossbars in an adjustable spaced relationship. The lower cross-bar 95 carries the cylinders or barrels 114 while the pistons (i.e. porous heads 117 and hollow rods 116) are carried by the upper crossbar 94. In operation, as a plurality of capsules 140 fed from a capsule supply are moved from position I.P. to the illustrated position by the pusher 146, the frame 93 is moved to position the units over the powder containers 130 at position F.P. The cross-bars are moved downwardly so that each barrel 114 extends through an aperture 135 in a flexible diaphragm 133 covering a powder container, and negative pressure is induced in the measuring chambers 121. The cross-bars are then moved upwardly and the frame is moved to the right (Fig. 14) over a doctor blade 136 to a position C.P. at which the cross-bars are moved downwardly together until the barrels engage a compacting surface 137. Continued downward movement of the cross-bar 94 will cause the piston heads to compress the powder charges against the surface. The units are again raised, moved to the discharging station E.P. and lowered until the barrels contact the capsules 140. Continued downward movement of the cross-bar 94 causes the piston heads to discharge the powder charges into the capsules. At this time a pulse of pressurized gas is directed to the units to assist in separating the powder charges from their piston heads. The units then return to the illustrated full line position, the loaded capsules are moved to the position I.P. and further capsules are supplied to displace the loaded capsules. Fig. 31 illustrates an apparatus in which compaction of the material is effected by a blade 204 prior to the measuring chamber 209 being charged. Compaction may alternatively be effected by vibrating the bowl 200.