| 摘要 |
PURPOSE:To increase the effective absorption rate of a laser beam and to perform stably and efficiently welding by shielding the upper and lower parts at a butt weld point by semispherical cavities and focusing the reflected and radiated energy from the weld point by multiple reflection to the weld point. CONSTITUTION:The upper and lower parts of the butt part 2 of thin steel sheets 1, 1 are shielded by semispherical cavities 4, 4'. A laser beam 3 is irradiated through a laser beam introducing hole 5 onto the weld point 2. The spot diameter of the beam 3 on the weld surface in the part where said beam is projected is made larger than the permissible accuracy for butting. An optical system is so set that the focal position of the beam 3 comes to the turning point of the upper cavity 4 as far as possible. When the beam 3 is irradiated in such a state, the effective absorption rate on the point 2 is increased by the multiple reflection effect of the cavities 4, 4'. The energy of the beam passing through the butt spacing is also reflected by the cavity 4' and further the energy radiated from the molten part is utilized by the multiple reflection. |
