Abstract: A coaxial nozzle of a laser beam machine has an inner nozzle in which a laser beam and an inner gas are passing through an inner side, an outer nozzle provided at an outer side of the inner nozzle, and a cooling circuit for cooling the inner nozzle.

Abstract: A coaxial nozzle of a laser beam machine has an inner nozzle in which a laser beam and an inner gas are passing through an inner side, an outer nozzle provided at an outer side of the inner nozzle, and a cooling circuit for cooling the inner nozzle.

Abstract: Oxygen and nitrogen contained in air is separated by an air separator. The separated nitrogen gas is supplied to an optical path cover of a laser beam machine as a protective gas for bend mirrors. Further, the separated nitrogen gas or oxygen gas can be selectively supplied to a laser beam head as an assist gas. The purity of the separated nitrogen gas can be kept within a predetermined range (94 to 99.5%) on the basis of a difference in pressure between a first conduit for supplying nitrogen gas and a second conduit for supplying oxygen gas. It is preferable to provide a filter for removing dust from air supplied to the air separator and a second filter for removing oil mist from the separated nitrogen supplied to the optical path cover.