| 摘要 |
PROBLEM TO BE SOLVED: To restrain a thermal lens effect by providing the first nozzle forming a shield gas current and the secondary nozzle forming a clean air current on the surface of a transmitting flat lens. SOLUTION: The first nozzle 4 and the secondary lens 7 are used in order to restrain the thermal lens effect in a laser welding device. The secondary nozzle 7 is arranged so that a hole 2a is worked at the symmetrical position with respect to the first nozzle 4 on the basis of the transmitting flat lens 1 and an ejecting port 7a is faced to the transmitting flat lens 1. By this method, at the time of blowing, the shield gas 6 and the clean air 9 are simultaneously made to flow on both surfaces from the upper side to the lower side without any waste and both surfaces are cooled. Both surfaces of the transmitting flat lens 1 are wholly cooled by blowing the clean air 9 in addition to cooling with the shield gas 6. More effectiveness is obtained by not only using the clean air 9 to rise the inner pressure in the beam transmission line but also optimally regulating the flow rate with a valve 25. |
