| 摘要 |
PROBLEM TO BE SOLVED: To obtain a wide and uniform weld bead, in an irradiation torch equipped with a first and a second convex lens, by forming a plane positioned vertically to the incident angle of a parallel beam in the center of the convex side of the second convex lens. SOLUTION: A laser beam B projected from an optical fiber cable 2, after turning to a parallel beam B2 at a first convex lens 3, passes through the spherical face of a second convex lens 4 and becomes a convergent beam B3 . The parallel beam B2 passing through the cut part in the center of the second convex lens 4 passes as it is through the second convex lens 4, reaching an irradiation position situated at a distance Y from the second convex lens 4. Consequently, a resultant beam (B2 +B3 ) is formed by the parallel beam B2 in which beam strength is consistent from the center to the peripheral part and by the convergent beam B3 in which beam strength is higher in the peripheral part than in the center, with the distribution of the beam strength slightly higher in the surrounding part, dispersing in the radial direction and appearing nearly trapezoidal. Therefore, the weld bead is wide and shallow penetration. |
