Systems for abrasive jet piercing and associated methods

1. A method for using a jet to cut a workpiece, the method comprising:

providing pressurized liquid to a cutting head of an abrasive jet system;

passing the liquid through an orifice within the cutting head to form a jet having a density;

flowing abrasive to the cutting head;

incorporating the abrasive into the jet downstream from the orifice, wherein the jet accelerates the incorporated abrasive towards an outlet of the cutting head;

flowing pressurized gas to the cutting head;

incorporating the gas into the jet downstream from the orifice, wherein the jet accelerates the incorporated gas towards the outlet, and wherein incorporating the gas reduces the density of the jet;

impacting the jet against a workpiece to pierce the workpiece at a starting point for an intended cut in the workpiece, wherein impacting the jet against the workpiece includes impacting the jet against the workpiece while the jet includes the abrasive and while the density of the jet is reduced;

stopping or otherwise reducing the flow of the pressurized gas to the cutting head after piercing through the workpiece or after piercing the workpiece to a desired piercing depth less than a full thickness of the workpiece, and while continuing to pass the liquid through the orifice to maintain the jet, wherein the stopping or otherwise reducing the flow of the pressurized gas increases the density of the jet; and

cutting the workpiece along the intended cut after stopping or otherwise reducing the flow of the pressurized gas to the cutting head and while continuing to pass the liquid through the orifice to maintain the jet.

2. The method of claim 1 wherein flowing the pressurized gas to the cutting head includes flowing the pressurized gas to the cutting head while the pressurized gas carries the abrasive to the cutting head.

3. The method of claim 2 wherein flowing the pressurized gas to the cutting head includes flowing the pressurized gas from a pressurized gas source to the cutting head via a conduit operably positioned between the pressurized gas source and the cutting head.

4. The method of claim 3 wherein:

the orifice is a first orifice; and

the method further comprises—

passing the abrasive from an abrasive container into the conduit via a second orifice operably positioned between the abrasive container and the conduit, and

combining the abrasive with the pressurized gas within the conduit while the pressurized gas flows through the conduit toward the cutting head.

5. The method of claim 4 wherein:

flowing the pressurized gas to the cutting head includes opening a valve operably positioned between the pressurized gas source and the conduit; and

stopping or otherwise reducing the flow of the pressurized gas includes closing the valve.

6. The method of claim 5 , further comprising pressurizing the abrasive container.

7. The method of claim 6 wherein pressurizing the abrasive container includes pressurizing the abrasive container to cause a pressure upstream of the second orifice to be at least generally equal to a pressure downstream of the second orifice.

8. The method of claim 1 wherein flowing the abrasive to the cutting head includes flowing the abrasive to the cutting head downstream from the orifice while separately flowing the pressurized gas to the cutting head.

9. The method of claim 1 wherein:

impacting the jet against a workpiece includes impacting the jet against a workpiece at a fluid pressure of greater than 1000 PSI and less than 10,000 PSI; and

cutting the workpiece along the intended cut includes cutting the workpiece at a fluid pressure greater than 10,000 PSI.

10. The method of claim 1 wherein flowing pressurized gas to the cutting head includes operating a valve to flow the pressurized gas into an abrasive container.

11. The method of claim 1 wherein flowing pressurized gas to the cutting head includes operating a valve to a) flow a first portion of the pressurized gas into an abrasive container, and b) flow a second portion of the pressurized gas to the cutting head, wherein the second portion of the pressurized gas does not pass through the abrasive container.

12. The method of claim 11 wherein the valve is a first valve, and wherein flowing pressurized gas to the cutting head includes operating the first valve to maintain a generally equivalent pressure across a second valve positioned at an outlet of the abrasive container.

13. The method of claim 1 wherein flowing the pressurized gas to the cutting head includes flowing the pressurized gas through an abrasive supply conduit, and wherein the method further comprises operating a valve to flow the abrasive into a flow of the pressurized gas.

14. The method of claim 13 wherein operating a valve to flow the abrasive into a flow of the pressurized gas includes operating the valve to flow the abrasive into a collector portion adjacent an abrasive container.

15. The method of claim 14 wherein stopping or otherwise reducing the flow of the pressurized gas to the cutting head does not reduce a rate of a flow of the abrasive.

16. The method of claim 1 wherein flowing pressurized gas to the cutting head includes operating a valve via a controller to equalize a pressure across an abrasive container.

17. The method of claim 1 wherein flowing pressurized gas to the cutting head includes flowing the pressurized gas through an abrasive container.

18. The method of claim 1 wherein flowing pressurized gas to the cutting head includes flowing the pressurized gas through a collector portion of an abrasive supply conduit, and wherein flowing abrasive to the cutting head includes flowing abrasive from an abrasive container into the collector portion.

19. The method of claim 1 wherein stopping or otherwise reducing the flow of the pressurized gas to the cutting head does not reduce a rate of a flow of the abrasive.