厚钢板激光焊接装置的研究

Research On the Set of Laser Welding for Thick armor plate

为满足激光厚板焊接对激光光束质量的要求,研制了多折非虚共焦非稳腔横流CO_2激光器以及厚钢板激光焊接装置。采用了外光桥、内光腔形式一级振荡,两级放大的非稳腔的光腔结构。多折非稳激光谐振腔结构可充分利用辉光放电区及其下游介质增益,获得足够大的高质量的激光功率输出。用有限元法,对该类型的激光谱振腔的特性进行了理论分析。分析结果表明,该多折非稳腔输出激光远场能量分布与多模激光能量分布相似,但非稳腔输出激光远场相位分布不存在180°跳变,因而能够将光束聚焦到厚板深透焊所需功率密度。焊接4mm的钢板,焊速超过了3.2m/min,深宽比大于2:1,焊接6mm钢板,焊速达2.1M/min以上,深宽比大于3:1,并可焊接8mm厚的钢板,通过试轧到0.3mm厚不断带,拉伸试验表明焊缝强度大于母材,说明焊缝具有良好的延展性和机械强度。

We develop the multi - fold unstable resonator for the 10kW transverse flow multimode laser to meet the need of high beam quality in welding thick steel plate, In which two stages of amplifying and one stage of oscillation are applied. The multi - fold resonator covers the discharge region and downstream active medium effectively, which is beneficial to high power output. Finite- element method is adopted in the theoretical analysis of the characteristics of the resonator. It shows that the multi - fold unstable resonator have a far - field intensity distribution similar to the multimode laser without singularity of 180°phase shift, so the beam can be focused to reach the enough power density for deep- penetration welding. The processing speed exceeds 3. 2M/min, 2.1M/min with the depth- to - width ratio more than 2:1 and 3:1 when welding the steel sheet of thickness of 4mm and 6mm, respectively. The welding thickness of the sheet can reach up to 8mm. The sheet can be rolled to become 0.3mm thick without crack in the welding joint, and its tensile test shows the strength and the ductibility of the welding joint is higher than the base material in the all cases mentioned.