Authors:
Guojian Xu
Akihiko Tsuboi
Takemitsu Ogawa
Takeshi Ikeda
Laser X CO., Ltd., 7 Korukada Shinmayashi-cho Chiryu-shi Aichi 472-0017, Japan

Muneharu Kutsuna
Graduate School of Engineering, Nagoya University, 1 Furo-cho Chikusa-ku, Nagoya 464-8603, Japan

A ring beam optics was developed for a circular seam welding of the automotive parts using a 2 kW fiber laser. The characteristics of the ring beam optics were investigated by a Primes Beam Monitor. As a result, with increase of focal length of collimating lens, the outer diameter of the ring beam was hardly changed, however the inner diameter of the ring beam decreased. Therefore, the width of the ring beam was increased in the experiment. A distance (L₁₂) between first axi-cone lens and second axi-cone lens increases, the outer diameter and inner diameter of the ring beam increases simultaneously. And the width of the ring beam was almost fixed. Moreover, it was confirmed that the intensity distribution of the ring beam becomes uniform by adjusting the coaxial performance of collimating lens, first axi-cone lens, and second axi-cone lens. After the ring beam optics connects to the fiber laser facility, a transparent thermoplastic resin and opaque thermoplastic resin with a circular seam was welded by a Through Transmission Laser Welding (TTLW). The thermoplastic resins with a circular seam were firmly welded in a super-short time.