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A waterjet assembly for an entrainment waterjet cutting head device comprises a passaged component adapted to be connected to a source of pressurised water and a waterjet nozzle for converting water pressure energy to kinetic energy to form a high velocity waterjet. The waterjet nozzle comprises sup

A waterjet assembly for an entrainment waterjet cutting head device comprises a passaged component adapted to be connected to a source of pressurised water and a waterjet nozzle for converting water pressure energy to kinetic energy to form a high velocity waterjet. The waterjet nozzle comprises superhard material and has a contracting bore. The passaged component and the waterjet nozzle are arranged such that pressurised water from the source flows through the passaged component to and through the contracting bore in the waterjet nozzle to generate the high speed waterjet. In use of the waterjet assembly, the outlet face of the passaged component is sealingly forced against the upstream face of the waterjet nozzle.

대표청구항 ▼

1. A waterjet assembly for an entrainment waterjet cutting head device, said waterjet assembly comprising: a passaged component having an elongate passage bore extending through the passaged component and adapted to be connected to a source of pressurised water, a direction of flow of said pressuris

1. A waterjet assembly for an entrainment waterjet cutting head device, said waterjet assembly comprising: a passaged component having an elongate passage bore extending through the passaged component and adapted to be connected to a source of pressurised water, a direction of flow of said pressurised water through the assembly defining an upstream direction and a downstream direction, anda waterjet nozzle for converting water pressure energy to kinetic energy to form a high velocity waterjet, said waterjet nozzle being of superhard material and comprising a nozzle bore converging from a wider upstream end to a narrower downstream end, whereinthe passaged component and the waterjet nozzle being arranged such that pressurised water from the source of pressurized water flows through the passaged component to and through nozzle bore in the waterjet nozzle to generate said high velocity waterjet, and whereinin use of the waterjet assembly, a downstream face of the passaged component is forced against an upstream face of the waterjet nozzle to form a seal. 2. The waterjet assembly of claim 1, wherein the waterjet nozzle is a structural element adapted to carry a sealing force from the passaged component. 3. The waterjet assembly of claim 1, wherein the passage bore of the passaged component and the nozzle bore of the waterjet nozzle have substantially the same diameter at a point where said passage bore and said nozzle bores meet. 4. The waterjet assembly of claim 1, wherein the downstream face of the passaged component and the upstream face of the waterjet nozzle each comprise essentially optically flat surfaces. 5. The waterjet assembly of claim 1, wherein the passaged component is made of metal and the upstream face of the waterjet nozzle has a surface which is sintered, etched, grown, deposited or machined so that said surface has superhard crystals or elements protruding from it such that when the downstream face of the passaged component is forced against the upstream face of the waterjet nozzle, said superhard crystals or elements cause plastic flow of metal on the downstream face of the passaged component contacting the upstream face of the waterjet nozzle to fill voids in the upstream surface of the waterjet nozzle thereby forming the seal. 6. The waterjet assembly of claims 1, wherein the passaged component is made of metal and comprises a seat of superhard material at its downstream end, such that said seat is interposed between the passaged component and the waterjet nozzle, wherein the upstream face of the seat has a surface which is sintered, etched, grown, deposited or machined so that said surface has superhard crystals or elements protruding from it that, when the downstream face of the passaged component is forced against the upstream face of the seat, cause plastic flow of metal on the downstream end face of the passaged component to fill voids in the upstream surface of the seat thereby forming the seal. 7. The waterjet assembly of claim 6, wherein the seat comprises a layer of polycrystalline diamond sintered, grown, bonded or deposited on a substrate of sintered tungsten carbide and wherein a downstream face of said layer of polycrystalline diamond is essentially optically flat. 8. The waterjet assembly of claim 1, wherein the superhard material of the waterjet nozzle is selected from diamond and diamond supported on a substrate and a downstream exit end of the nozzle bore extends through said diamond. 9. An entrainment waterjet cutting head device comprising a waterjet assembly comprising:a passaged component having an elongate passage bore extending through the passaged component and adapted to be connected to a source of pressurised water, a direction of flow of said pressurised water through the assembly defining an upstream direction and a downstream direction, anda waterjet nozzle for converting water pressure energy to kinetic energy to form a high velocity waterjet, said waterjet nozzle being of superhard material and comprising a nozzle bore converging from a wider upstream end to a narrower downstream end, whereinthe passaged component and the waterjet nozzle are arranged such that pressurised water from the source of pressurized water flows through the passaged component to and through said nozzle bore in the waterjet nozzle to generate said high velocity waterjet, and whereinin use of the waterjet assembly, a downstream face of the passaged component is forced against an upstream face of the waterjet nozzle to form a seal;a chamber traversed in use by said high velocity waterjet,an abrasive inlet for in flow of abrasive particles suspended in a carrier fluid, aid abrasive inlet leading to said chamber,an outlet tube extending downstream from the chamber, coaxially with the passage bore and the nozzle bore, such that the high velocity waterjet entrains the abrasive particles and the carrier fluid from the abrasive inlet and passes into the outlet tube, whereby momentum transferred from said high velocity waterjet to the abrasive particles within the outlet tube and an abrasive machining jet is emitted from the cutting head device, anda cutting head body. 10. The entrainment waterjet cutting head device of claim 9, further comprising a detachable housing adapted to hold the waterjet nozzle and the outlet tube, such that when the detachable housing is mounted to the cutting head body the passaged component is urged against the waterjet nozzle and to produce part or all of said sealing force. 11. The entrainment waterjet cutting head device of claim 10, wherein an external diameter of the waterjet nozzle is larger than an external diameter of the outlet tube, and wherein the detachable housing comprises first and second coaxial passageways having diameters to receive the waterjet nozzle and the outlet tube respectively, said coaxial passageways being adapted such that a portion of the downstream face of the waterjet nozzle is directly supported by the detachable housing and the sealing force is transmitted through the waterjet nozzle to the detachable housing. 12. The entrainment waterjet cutting head device of claim 10, wherein said chamber is formed in the outlet tube and the waterjet nozzle and the outlet tube each have the same outer diameters and fit within a common passageway through the detachable housing so that said sealing force is transmitted from the waterjet nozzle to the outlet tube and from the outlet tube to the detachable housing. 13. The entrainment waterjet cutting head device of claim 10, wherein the chamber is formed within the outlet tube, and wherein the outlet tube comprises a further passageway upstream of the chamber within which further passageway the waterjet nozzle is located such that said sealing force is transmitted from the waterjet nozzle to the outlet tube and through the outlet tube to the detachable housing. 14. The entrainment waterjet cutting head device of claim 9, so adapted such that said pressurised water acts on an upstream end of the passaged component to force the downstream face of the passaged component into sealing contact with the upstream face of the waterjet nozzle. 15. The entrainment waterjet cutting head device of claim 109, wherein the passaged component comprises a seat of superhard material, and the waterjet nozzle and the seat are located within a common passageway in the detachable housing. 16. A waterjet assembly for an entrainment waterjet cutting head device, said waterjet assembly comprising: a passaged component having an elongate passage bore extending through said passaged component, and being connectable to a source of pressurised water such that a direction of flow of said pressurised water through the waterjet assembly defines an upstream direction and a downstream direction;a waterjet nozzle to form a high velocity waterjet, said waterjet nozzle comprising a superhard material and having a nozzle bore extending through it that converges from a wider upstream end to a narrower downstream end;the passage bore of the passaged component and the nozzle bore of the waterjet nozzle being coaxially aligned to permit said pressurised water to flow to the nozzle bore and be emitted from the narrower downstream end of the nozzle bore as said high velocity waterjet; anda downstream face of the passaged component being forced in use against an upstream face of the waterjet nozzle to form a seal. 17. The waterjet assembly of claim 1, wherein the passaged component comprises metal and has a seat of superhard material mounted to its downstream end by a technique selected from brazing and welding, said seat comprising a substrate of sintered tungsten carbide having a layer of polycrystalline diamond applied to its downstream face, said layer of polycrystalline diamond being essentially optically flat, so as to form a seal against an essentially optically flat upstream face of the waterjet nozzle. 18. The entrainment waterjet cutting head device of claim 9, wherein the passaged component of the waterjet assembly comprises a portion of the cutting head body.