Laser welding device

1. A laser welding device comprising:

a chamber that has a low-pressure internal space in which a workpiece is disposed;

a laser beam irradiation unit that irradiates the workpiece with a laser beam to weld the workpiece;

a laser transmission window through which the laser beam from the laser beam irradiation unit is transmitted; and

a gas injection nozzle that is disposed on a workpiece side from the laser transmission window,

wherein the gas injection nozzle includes an optical path hole through which the laser beam passes and an injector that injects an inert gas for shielding metal vapor, which is ejected from the workpiece to the laser transmission window side when the workpiece is welded by the laser beam, into the optical path hole toward an irradiation direction side and an optical axis side of the laser beam, and

wherein the injector is provided in a circumferential shape along an inner peripheral surface of the optical path hole.

2. The laser welding device according to claim 1 ,

wherein the injector is configured to inject the inert gas in a direction inclined at a predetermined angle with respect to an optical axis of the laser beam toward the irradiation direction side and the optical axis side of the laser beam.

3. The laser welding device according to claim 2 ,

wherein the injector is formed in a circumferential slit shape.

4. The laser welding device according to claim 3 ,

wherein the injector having a slit shape is inclined at substantially the same angle as the predetermined angle as a whole.

5. The laser welding device according to claim 3 , further comprising:

an inert gas supplier for introducing the inert gas to the gas injection nozzle,

wherein the gas injection nozzle further includes a buffer space which is provided in a circumferential shape on an outside of the injector and through which the inert gas introduced from the inert gas supplier flows.

6. The laser welding device according to claim 5 ,

wherein a plurality of the inert gas suppliers are disposed on an outer peripheral portion of the gas injection nozzle at substantially equal angular intervals.

7. The laser welding device according to claim 1 ,

wherein the optical path hole has a constant cross-sectional shape that is orthogonal to the irradiation direction along the irradiation direction, as a whole.

8. The laser welding device according to claim 1 ,

wherein a cross-sectional shape of the optical path hole orthogonal to the irradiation direction has a circular shape equal to or larger than a spot diameter of the laser beam at a disposition position of the gas injection nozzle and smaller than a diameter of the laser transmission window.

9. The laser welding device according to claim 1 , further comprising:

a tubular portion through which the laser beam that has been transmitted through the laser transmission window passes and which communicates with the chamber,

wherein the laser transmission window and the gas injection nozzle are disposed in the tubular portion.

10. The laser welding device according to claim 9 ,

wherein the tubular portion has a first tubular portion in which the laser transmission window is disposed and a second tubular portion which has a space through which the laser beam passes and is adjacent to the irradiation direction side of the first tubular portion,

a length of the second tubular portion in the irradiation direction is longer than a length of the first tubular portion in the irradiation direction, and

the gas injection nozzle is disposed on the chamber side of the first tubular portion from the laser transmission window.

11. The laser welding device according to claim 10 , further comprising:

a pump which exhausts air in the chamber to form a low pressure in the internal space of the chamber,

wherein the chamber includes an exhaust port connected to the pump, and

a distance from the gas injection nozzle to the exhaust port is longer than a distance from the gas injection nozzle to the laser transmission window.

12. A laser welding device comprising:

a chamber that has a low-pressure internal space in which a workpiece is disposed;

a laser beam irradiation unit that irradiates the workpiece with a laser beam to weld the workpiece;

a laser transmission window through which the laser beam from the laser beam irradiation unit is transmitted;

a gas injection nozzle that is disposed on a workpiece side from the laser transmission window; and

an inert gas supplier for introducing an inert gas to the gas injection nozzle,

wherein the gas injection nozzle includes an optical path hole through which the laser beam passes and an injector that injects the inert gas for shielding metal vapor, which is ejected from the workpiece to the laser transmission window side when the workpiece is welded by the laser beam, into the optical path hole toward an irradiation direction side and an optical axis side of the laser beam, and

wherein the gas injection nozzle further includes a buffer space which is provided in a circumferential shape on an outside of the injector and through which the inert gas introduced from the inert gas supplier flows.