基于数字图像相关的切削加工剪切区应变率监测调控研究

Monitoring and Control of Strain Rate of Primary Shear Zone in Cutting Process Based on Digital Image Correlation

切削加工是航空制造领域主要加工方式之一,切削过程应变与应变率对切屑生成和加工表面质量有较大的影响,监测和调控切削过程应变与应变率是研究切削机理和实现加工过程控制的直接方法之一。本文开发了一套切削过程剪切区应变率监测调控软硬件系统,搭建了正交切削原位成像平台,获取切削过程剪切区显微照片,编写了多线程加速的全局数字图像相关算法,实现对正交切削过程的同步图像分析和剪切区应变率计算;建立了一套由计算机控制数控车床主轴的调速系统,根据测量应变率与目标应变率的大小关系实时调节主轴倍率。开展了两组正交切削试验,试验结果表明,所搭建的试验系统可以实现对剪切区的应变率监测与调控,调控后剪切区应变率与目标值偏差小于10%,与理论预测值相比误差小于23%。

Metal Cutting is one of the main processing methods in the field of aviation manufacturing, and strain and strain rate have a great impact on the chip formation and surface quality. The monitor and control of the strain and strain rate can contribute to the study of the cutting mechanism and conditioning of the machining process. In this paper, we developed an experimental setup for monitoring and controlling of strain rate in the primary shear zone. An in-situ imaging platform of orthogonal cutting is built, which can acquire the images of shear zone in the orthogonal cutting process.A global DIC algorithm accelerated by multithreading is developed to improve the efficiency of image analysis. The image analysis and strain rate calculation can be conducted as well by the DIC software. An online adjustment of spindle controlled by computer is established, which can adjust the spindle magnification in real time according to the relationship between the measured strain rate and the target strain rate. Two experiments for the control of the strain rate in the primary shear zone during orthogonal cutting are carried out. The experimental results show that this system can monitor and control the strain rate in the shear zone with an error less than 10% compared with target value, and less than 23% compared with theoretical predicted value.