Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C7/00—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts
  • B24C7/0007—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a liquid carrier
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C7/00—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts

Definitions

• This invention relates to cutting or abrading apparatus, and relates specifically to a jet cutting or abrading apparatus wherein a cutting fluid comprising a liquid carrier and abrasive is jetted in a fine stream to act as a cutting lance for cutting, for example, rigid sheet materials.
• a " particular application for the present invention comprises the cutting of linings of pipes (such as underground sewers) where such linings block connections between lateral connecting pipes and the main sewer.
• the invention may also be used for cutting obstructions in pipes.
• a method of high pressure jet cutting comprising feeding high pressure liquid carrier and an abrasive composition comprising abrasive particles in suspension to a mixing head, delivering the resulting mixture to a nozzle from which said issues as a high pressure cutting jet or jets.
• the carrier fluid preferably is water at a pressure in the order of up to 4,000 psi.
• the present invention provides for the delivery of abrasive particles to the mixing head, in a fluent medium of such as to form with the abrasive particles a suspension in which the abrasive particles are suspended in such a fashion that if there is failure in the supply pressure delivering the mixture to the nozzle head, the particles will not fall out of suspension.
• This arrangement also has the considerable advantage that the supply of the abrasive composition can be stopped and restarted without any deleterious effects.
• the abrasive material may be sand, and a suitable fluent material for suspending sand is water with a thickening thixotropic agent.
• the mixture may be drawn into the high pressure water at the mixing head by virtue of venturi action.
• the abrasive composition is delivered at a slower speed than the water to the mixing head, but at said mixing head the abrasive composition is acceletated up to the speed of the water so that there is effective mixing, for delivery to the nozzle.
• the ratio of the throat restrictor for the abrasive compositions to that for the water, at the mixing head as in the order of 3:20.
• the abrasive composition is preferably delivered to the mixing- head by a twin piston pump arrangement the pistons being connected in a back to back or push-pull configuration.
• the water may be delivered by means of a high pressure water pump.
• the instant invention is also concerned with the apparatus for providing the fluid cutting jet, and also in accordance with the present invention, a high- pressure fluid cutting jet apparatus comprised an outlet nozzle for the jet, means supplying a carrier liquid under pressure to the nozzle and means for supplying a fluent composition comprising or containing the abrasive particles in suspension to said jet so that the liquid and composition mix in a ' mixing head to form the final cutting jet, said means for supplying the fluent composition comprising a pump means driven by the pressure of the carrier liquid.
• the said pump means preferably comprises a pair of piston pumps arranged back to back so as to have a common piston rod, with appropriate valving providing that the pressurised carrier liquid is applied alternately to the crown side of the piston of each pump, whilst the fluent composition is pumped by the rod side of the respective piston pumps and alternately, thereby to provide augmentation of the pressure in the fluent composition.
• the fluent composition is preferably supplied to the mixing head through a passage which is a fraction of the area of the passage through which the carrier liquid is supplied in order that the carrier liquid can be applied in substantially greater volume to the jet than the fluent composition, but so that the composition and carrier liquid are supplied to the jet at substantially the same velocity in order to ensure homogenous mixing of carrier liquid and fluent composition.
• the apparatus may embody a control shuttle valve controlling the supply of the carrier liquid under pressure to the alternate piston pumps, so that as one pump is pressurised, the other is exhausted, the shuttle valve being switched by a means coupled to the said common piston rod, and the outlets from the crown sides of the piston pumps being provided with appropriate one ⁇ way valves to ensure that as fluent composition is being pumped from one of said rod sides to the nozzle, the other is drawing in a fresh supply of the fluent composition ready to be charged to the nozzle at the next stroke of that pump.
• Fig. 1 is a ciruit diagram of the hydraulic circuit of apparatus according to a first embodiment of the present invention
• Fig. 2 is a view of an apparatus according to a second embodiment of the invention.
• the hydraulic circuit of the apparatus comprises a water tank 10, water forming the pressurised liquid component of the system, a tank 12 for the composition of carrier matrix and abrasive, and a mixing head 14 to which a pressurised water line 16 and a pressurised fluent composition line 18 lead so that in the head 14, pressurised water and fluent material under pressure are mixed and together then pass along pipe 15 to an outlet nozzle 14A from which 14A and head 14 may be combined into a single unit to perform the cutting operation.
• the water travels in line 16 at greater speed than the composition in line 18 but in the head 14 are restrictors x and y for the composition flow and water flow in order to ensure that the composition and water meet at substantially the same velocity.
• the composition restrictor x may be 3/20ths of the cross- sectional area of the water restrictor y.
• the water is drawn from tank 10 by means of a pump 22 which may supply water at 21 litres per minute at a pressure in the order of 2,000 psi.
• the output line 24 from the pump 22 leads directly to the nozzle 14, but also has a branch line 26 containing a flow control valve 28 to divert say in the order of 3 litres per minute through a shuttle valve 30 depending upon its position as • will be explained hereinafter.
• the fluent composition is drawn from the tank 12 to either one of a pair of pumps 32, 34 which comprise piston and cylinder devices, and the pistons 36, 38 are arranged on a common piston rod 40 so that pumps 32 and 34 are arranged back to back.
• a centralising spring arrangement serves to bias the piston rod to the centralised position shown in Fig. 1.
• the composition is drawn from the tank 12 through a line 44 and either of two non-return valves 46, 48 in lines 50, 52 leading to the rod sides of pumps 32 and 34.
• Two outlet pipes from pumps 32 and 34 indicated by reference numerals 54 and 56 contain non-return valves 58 and 60 and lead to an outlet line 62 which in turn couples with the fluent composition outlet pipe 18.
• a continuous supply of the fluent composition and water through nozzle is therefore ensured, but the system can be stopped by stopping the pump 22.
• the amount of water which is used for displacing the pistons can be controlled by adjustment of the flow control valve 28..
• the apparatus comprises a nozzle head 10X containing a nozzle outlet 12X from which the high velocity jet of water issues, the water being supplied via a high pressure water hose 14 at a pressure in the order of 3,000 P.S.I, at 4 gallons per minute.
• the pipe 14X leads to a venturi chamber 16X which is traversed by a feed pipe 18X for the mixture of the abrasive composition.
• the composition is drawn in accordance with well-established venturi principles into the venturi chamber 16X in use through a small aperture 20X in the pipe 14X and facing the nozzle 12X.
• the abrasive composition is pumped by means of a motor 22X which drives a feed auger 24X, in a chamber 26X, to which the material is fed from a storage hopper 28X.
• the source of the material in hopper 28X and the source of high pressure water may be located remotely from the nozzle head 10X which typically will be loctated in the pipeline where cutting is to take place.
• a cross-connecting pipe 30X couples the feed pipe 18X for the composition and the water pipe 14X and contains a flushing valve 32X which is normally closed, but which can be opened when it is required to pump water through the pipe 18X in order to flush same of residual composition and/or abrasive.
• the composition is such that the carrier medium and the abrasive are of like density and/or specific gravity so that the abrasive particles will remain in suspension in the carrier even in the event of failure of the pump 22X.
• a ' s in the Fig. 1 embodiment there will be minimum or no settling out of the abrasive even when the system is not operational, distinguishing the method and apparatus from the known arrangements.
• a suitable compo'sition may comprise, by weight, the following:
• This composition may be mixed by weight with the water in the retes of 1 to 6 (one part composition to six parts water) .

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
• Processing Of Stones Or Stones Resemblance Materials (AREA)
• Crushing And Pulverization Processes (AREA)
• Confectionery (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26295712

Family Applications (1)

Country Status (7)

Cited By (1)

Families Citing this family (7)

Family Cites Families (12)

• 1990
  • 1990-08-06 EP EP90912675A patent/EP0485502A1/de not_active Withdrawn
  • 1990-08-06 CA CA002059661A patent/CA2059661A1/en not_active Abandoned
  • 1990-08-06 FI FI920423A patent/FI920423A0/fi not_active Application Discontinuation
  • 1990-08-06 WO PCT/GB1990/001222 patent/WO1991001852A1/en not_active Ceased
  • 1990-08-06 AU AU61791/90A patent/AU6179190A/en not_active Abandoned
  • 1990-08-06 KR KR1019920700210A patent/KR920703272A/ko not_active Withdrawn
  • 1990-08-06 JP JP2511796A patent/JPH04506938A/ja active Pending

Non-Patent Citations (1)

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