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为了准确地模拟出激光深熔焊接中小孔的动态变化过程,根据小孔内激光能量的传输过程和吸收机制,采用光线追踪法来描述小孔对激光能量的多重反射吸收作用,建立了基于光线追踪的热源模型,分析了工艺因素对30Cr Mn Si A钢激光深熔焊接过程中瞬态小孔的深度振荡和熔池流动行为的影响。结果表明,激光焊接过程中熔池的小孔深度呈周期性变化并伴有高频振荡特征,而小孔的振荡是焊接不稳定性和缺陷形成的重要原因。而随着激光功率的增大,小孔深度增大,小孔深度达到相对稳定状态的时间缩短。小孔深度达到相对稳定状态时,小孔振荡的幅度随激光功率的增加而增大。在对不同工艺条件下熔池的温度场、流场和小孔的动态演化过程对比的基础上,进一步探索了焊缝气孔的形成机理,并提出了减少焊缝气孔和增强小孔稳定性的新思路。
In order to accurately simulate the dynamic process of small holes in deep penetration laser welding, ray tracing method is used to describe the multi-reflection absorption of small holes on laser energy according to the transmission process and absorption mechanism of laser energy in the small holes. Ray tracing heat source model was used to analyze the influence of technological factors on the deep oscillation and the flow behavior of transient small holes during the laser deep penetration welding of 30Cr Mn Si A steel. The results show that the depth of the puddle in the laser welding process changes periodically with the characteristics of high frequency oscillation. The oscillation of the pinhole is an important reason for the welding instability and defect formation. With the increase of the laser power, the depth of the hole increases, and the time for the hole depth to reach a relatively stable state is shortened. When the depth of the hole reaches a relatively stable state, the amplitude of the hole oscillation increases with the increase of the laser power. Based on the comparison of the dynamic evolution of the molten pool temperature field, flow field and pore under different process conditions, the formation mechanism of the weld pores was further explored and the ways to reduce the porosity of the weld seam and enhance the stability of the pores New ideas.