GB980083A - Material breaking cartridge for blasting and the like - Google Patents

Abstract

980,083. Fluid-pressure blasting devices. OLIN MATHIESON CHEMICAL CORPORATION. Sept. 25, 1961 [Oct. 11, 1960], No. 34334/61. Heading F3A. A compressed-gas blasting cartridge is adapted to discharge seqentially through exhaust ports situated at intervals along the length of the cartridge. In one embodiment, ports 94, 95 are normally closed by sleeve valves 92, 93 respectively, the valves being held in position by slidable metallic sealing rings 100, 107 and springs 105, 115. Smaller ports 120 at the forward end are closed by a piston 118 which is forced to the left by a spring 119 and closes a central orifice 116 by means of a ball valve 117. In operation, compressed gas is introduced to chamber 7 and from there the gas passes via central orifice 96 to chamber 8 and via central orifice 97 to control chamber 114. While charging, the pressures in chambers 7, 8 and 114 are substantially equal. The sealing rings 100, 107, which have modified knife edges 102, 108, form metal-to-metal seals with valves 92, 93 and have larger effective left-hand crosssectional areas so that they are urged to the right when compressed gas enters the cartridge. At a predetermined pressure ball valve 117 is unseated, the consequent gas pressure on piston 118 forcing it to the right against spring 119 to open ports 120 and rapidly reduce pressure in chamber 114. Valve 93 is now forced to the right by the pressure differential of chambers 114 and 8 and this differential is suddenly augmented when the metal-to-metal seal between ring 107 and valve 93 is broken, this occurring when shoulder 111 meets abutment 110. With the opening of ports 95 chamber 8 is effectively exhausted and the now present pressure differential of chambers 8, 7 causes similar exhaustion of the latter through ports 94. A further embodiment (Fig. 6, not shown), features three sets of ports, that nearest the work face allowing discharge first and that intermediate the other two last. A still further embodiment (Fig. 7, not shown), features two valves connected by a rod with exhaustion through those ports nearest the work-face occurring first when the feed line is vented to the atmosphere.