Patent ID: 8342912

Claim:
An abrasive water jet processing machine for jetting a fluid where an abrasive is mixed from a nozzle and performing a cutting, the machine comprising: a fluid supply device configured to supply the fluid to the nozzle; an abrasive supply device configured to supply the abrasive to the nozzle and to mix the abrasive in the fluid; and an injection pressure controller configured to control injection pressure for jetting the fluid, the abrasive supply device comprising: a reservoir hopper essentially consisting of a pressure vessel for reserving the abrasive; an abrasive supply tube configured to communicate the reservoir hopper with the nozzle; and an air purge device configured to supply compressed air to the abrasive supply tube and the reservoir hopper, to use an air flow rate increased by loading flow pressure on the abrasive passing through the abrasive supply tube by means of the compressed air, and to feed by the flow pressure the abrasive to the nozzle, the injection pressure controller performing a two-stage control of controlling the injection pressure in a piercing, wherein the piercing occurs prior to the cutting and is performed at a lower pressure than the injection pressure for cutting, the air purge device comprising a flow pressure controller configured to control the flow pressure of the compressed air passing through the abrasive supply tube in a state of the injection pressure being controlled to be low by the injection pressure controller, wherein the flow pressure controller controls the flow pressure in the piercing to be higher than the flow pressure in the cutting.