高强镀锌钢激光填粉焊接的粉末输送研究.pdf

学兔ww.xet
第50卷第4期
机械工程学报
1.50No.4
2014年2月
JOURNAL OF MECHANICAL ENGINEERING
Feb
2014
DOI:10.3901/JMIE.2014.04.060
高强镀辥钢溦光填粉焊接的粉末输送研究
张屹徐磊刘西霞李庆福
(湖南大学汽车车身先进设计制造国家重点实验室长沙410082)
摘要:激光塡粉焊接是一种高柔性化焊接加工技术,能有效降低激光焊接裝配精度。使用自行开发的侧向送粉装置,基于粉
末分布密度与图像灰度的相关性,测量分析粉束截面的粉末分布密度和粉末输送的有效性,并开展高强镀锌钢光纤激光填粉
焊接的焊接工艺性及接头性能的研究。结果表明,粉末落点是决定粉末利用率的关键因素。以45°侧向送粉时,有效输送率
最高的粉末落点为-1.75mm。粉末落点过于靠近或远离激光束时均不利于金属粉末有效熔入熔池。粉末落点为-4mm时,粉
末利用率最高。焊缝中心铜的质量分数随着送粉速度的降低而线性减小。填充粉末能明显提高焊缝表面质量,细化热影响区
晶粒,提高焊缝组织性能,同时提高了激光焊接间隙裕度,降低工件对激光焊接装配精度的要求。
关键词:激光焊接;粉末输送;添加粉末;装配精度
中图分类号:TG456
Study on Powder Delivery in Laser Welding of High Strength Galvanized
Steel with Powder Filing
ZHANG Yi XU Lei LIU Xixia LI Qingfu
(State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,
Hunan University, Changsha 410082
Abstract: Laser welding with powder filling is a highly flexible welding technology due to its effective reduction of the assembly
accuracy of workpiece. Based on the correlation between the density of powder distribution and the image gray, the distribution
density on the cross section of the powder beam is measured, and the effectiveness of the powder delivery with a self-developed
lateral device for powder feeding is analyzed. Furthermore, the welding technological properties and the joint performance in fiber
laser welding of high strength galvanized steel with powder filling are studied. The results show that: The powder position is the key
factor of the rate of the power utilization. When filling powder laterally in angle of 45, the most effective delivery rate can be
obtained with the powder position of-1. 75 mm. The power would to be fed into the welding pool ineffectively when powder position
is too close to or far away from the laser beam. The highest rate of the powder utilization can be realized with the powder position of
-4 mm The copper content on the weld center section decreases linearly with the reduction of the powder feeding speed. Powder
filling can significantly improve the performance of the weld surface and refine the grains in the heat-affected zone, as well as the
improvement of the weld properties. Laser welding with powder injection is able to improve the weld surface quality, create finer
microstructure in the heat affected zone, improve the strength of the weld, as well as increase the gap tolerance and reduce the
assemble accuracy of the workpiece
Key words: laser welding; powder delivery; powder filling; assembly accuracy
则是其车身连接的主要方式。随着激光技术的高速
0前言
发展和车身轻量化的不断发展,激光焊接由于焊接
速度快、热影响区小、加工柔性好和易于自动化等
镀锌钢由于其良好的抗腐蚀性在汽车制造领优点2到,被越来越多地应用于汽车制造。同时,激
域得到了广泛应用叫,而传统的电阻点焊和氮弧焊光对接焊接替代传统的搭接焊将有效地减轻车身重
量,提高白车身的强度和刚度+?。然而,激光对接
国家自然科学基金(51175162)和湖南省自然科学基金重点(12J2032)资
助项目。20130329收到初稿,20130826收到修改稿
焊接要求工件的装配精度高',通常小于板厚的