【作者】 施浩；

【导师】 张轲； 胡永强；

【作者基本信息】 上海交通大学 ， 材料科学与工程（专业学位）， 2015， 硕士

【摘要】 传统上,窄间隙激光填丝焊主要以人工示教为主,人为因素对焊接质量影响较大,焊接效率低。针对以上问题提出厚板窄间隙多层多道自动化激光填丝焊接及焊缝跟踪。首先研究了厚板激光填丝焊的工艺参数。实验结果表明,影响填丝焊焊缝成型的主要因素有激光功率、送丝速度、焊接速度、离焦量以及保护气流量。随激光功率的增加,单道焊缝的填充量下降,熔宽增加;随着送丝速度增大,焊缝填充量与堆高均增大;焊接速度的增加导致焊缝填充量与堆高下降,熔宽因热输入减小而下降;离焦量对熔深的影响较大,随着离焦量增大,焊缝熔深下降;保护气体流量过大,会影响焊缝成型的质量。其次建立单道填丝焊的焊缝几何与焊接输入参数之间的关系。本文通过响应曲面法分别建立了焊缝填充横截面积、熔宽、堆高、熔宽与堆高的比值与激光功率、送丝速度以及焊接速度之间的数学关系。验证实验结果表明,所建立的模型均能准确的对焊缝的几何参数进行预测。继而建立了基于单道填充横截面积的多层多道焊缝轨迹规划方法,包括焊接道数、焊枪端点坐标的算法、填充顺序等,使得焊道规划更加准确。随后利用KUKA机器人编程实现多道焊焊接程序。最后结合焊缝跟踪传感器实现了多层多道焊缝跟踪。该激光扫描式传感器能够实时调整焊缝跟踪轨迹,避免焊接过程中因焊接变形或者工装移位导致焊枪端点偏离原焊接轨迹的问题。验证实验结果表明,采用上述方法,能够准确的对焊缝几何、焊接道数、焊枪端点坐标偏移量进行预测。对于多层多道焊接接头缺陷的分析表明,热输入P/Vw以及送丝速度与焊接速度的比值Vf/Vw是影响接头质量的主要因素。另外,单道焊缝熔宽Ww与被填充层宽度Wt的比值会影响多层-单道填充时缺陷的形成。更多还原

【Abstract】 Traditionally, welding path planning mainly depends on man’s experiences and teaching methods. Human factors are not only influencing the quality of the joint but also in low welding efficiency. The aim of this paper is that the automatic multi-pass laser welding and seam tracking process are developed.To be the first, the process parameters of laser welding with filler wire should be explored. Experiment results showed that laser power, welding speed, wire feed rate, defocusing distance and shielding gas flow have big influences on the quality of the joint. The filling volume of single pass welding will decrease and the bead width will increase with the adding of laser power. As the wire feed rate grows, the filling volume and bead height all raise. The welding speed has a negative effect on filling volume and bead height. Because the heat input will decrease. The defocusing distance mainly affects the penetration of the bead. The quality of the joint will become terrible because of excessive shielding gas flow.Besides, statistical methods were applied to study the interactions between welding parameters and the geometry of single bead. By this method, the models between bead geometry and input welding parameters have been established. The responses include the transversal area, bead width, bead height of the added metals and the ratio of bead width to height. Verification experiments indicate that all these models can forecast the responses within the factors domain. These results will provide supports for automatic multi-pass laser welding.Finally, YLS-10 Kw Nd:YAG fiber laser system、KUKA robot and seam tracking sensor were used to study the automatic multi-pass and multi-layer laser welding. The number of filling pass was planned according to the ratio of gap width to the bead width. Then the algorithms of path planning were achieved by the robot programming. The laser point and wire tip position can be set automatically only by inputting bead parameters, groove sizes and welding parameters after teaching the weld line of the first pass.Verification experiments indicate that this method is valuable in automatic multi-pass laser welding. The practical filling passes and build-up sequence are accurately accord with the predicted results. Welding robot reached the planned position at precise coordinates and then finished the welding process successfully. Experiments about voids show that the heat input and the ratio of wire feed rate to the welding speed are the main factors affecting the joint qualities. The ratio of bead width to the width of the root layer also influences the forming of defects.更多还原