To provide a water-jet device capable of solving a problem that a conventional device to drill and cut often generates frame itself and generates sparks in a process of work, that cutting drilling performance tends to be short though there is no risk to be a flashing source or an ignition source on a water drinking water-jet and that sparks are occasionally generated on an abrasive water-jet.

It is possible to drill and cut an object 10 while avoiding a danger of ignition and combustion even in gas having the danger of ignition and combustion by providing a means to supply incombustible gas 1, water 2 and an abrasive material 13, a nozzle 6 to jet water and the abrasive material arranged with its jetting port directed toward a surface 10 of the object, a space filled with the water arranged by making contact with a part 10 of the surface of the object with which a material jetted from a jetting port of this nozzle 6, the abrasive material, the material constituting the object or some of them and the incombustible gas 1 and a conduit 11 to supply the incombustible gas 1 to this space.

COPYRIGHT: (C)2008,JPO&INPIT