摘要
目的 针对选区激光熔化成形薄壁件过程中存在的变形较大、精度低等问题,通过获得最优工艺参数区间来减小薄壁件的变形。方法 利用有限元软件分析薄壁件成形过程中温度场和应力场的演化规律;建立形变量预测模型并进行试验验证,研究工艺参数对薄壁件尺寸偏差的影响,得到激光功率、扫描速度与形变量之间的关系,实现对形变量的预测和控制。结果 随着扫描层数的增加,熔池的最高温度和热影响区也随之增大,等温线越密集,温度梯度越大,最终趋于稳定;薄壁件成形过程中,出现两侧壁边缘向内倾斜、上侧边缘出现内凹的现象,薄壁件的最大应力随层数的增加而减小,最大热应力主要分布在薄壁件底层的两端;形变量随激光功率的增大而增大,随扫描速度的增大而减小,薄壁件的形变量最小约为0.02 mm;试验验证所建立的数学模型误差在10%左右,误差较小,可以对形变量进行良好的预测和控制。结论 激光功率100~200 W、扫描速度800~1 000 mm/s为最优参数区间;降低能量密度可以有效降低薄壁件形变量,提高其精度。
The work aims to reduce the deformation of thin-walled parts by obtaining the optimal process parameter range,so as to solve the problems of large deformation and low precision in the process of selective laser melting forming. The evolution law of temperature field and stress field during the forming process of thin-walled parts was analyzed by finite element software. The shape variable prediction model was established and verified by experiments. Then, the effect of process parameters on the size deviation of thin-walled parts was studied and the relationship between laser power, scanning speed and shape variable was obtained to realize the prediction and control of shape variable. With the increase of the number of scanning layers,the maximum temperature and heat affected zone of the molten pool also increased. The denser the isotherms were, the greater the temperature gradient was, which finally tended to be stable. During the forming process of thin-walled parts, the edges of both sides of the wall inclined inward, and the upper edge was concave. The maximum stress of thin-walled parts decreased with the increase of the number of layers, and the maximum thermal stress was mainly distributed at both ends of the bottom layer of thin-walled parts. The shape variable increased with the increase of laser power and decreased with the increase of scanning speed. The minimum shape variable of thin-walled parts was about 0.02 mm. The experiments verified that the error of the established mathematical model was minor, about 10%, which could predict and control the shape variables well. The optimal parameter range covers the laser power of 100-200 W and the scanning speed of 800-1 000 mm/s. Reducing the energy density can effectively reduce the shape variable of thin-walled parts and improve the precision.
作者
许明三
江尧峰
姚耀伍
陈相档
曾寿金
叶建华
XU Ming-san;JIANG Yao-feng;YAO Yao-wu;CHEN Xiang-dang;ZENG Shou-jin;YE Jian-hua(Fujian Key Laboratory of Intelligent Machining Technology and Equipment,Fujian University of Technology,Fuzhou 350118,China;School of Mechanical and Automotive Engineering,Fujian University of Technology,Fuzhou 350118,China)
出处
《精密成形工程》
北大核心
2023年第2期86-94,共9页
Journal of Netshape Forming Engineering
基金
国家自然科学基金(51575110)
福建省自然科学基金(2020J01827)。
关键词
选区激光熔化
仿真分析
薄壁件
形变
数学模型
selective laser melting
simulation analysis
thin-walled parts
shape variable
mathematical model
