增材制造工件上表面形变在线测量方法

Online measurement method for surface deformation of additive manufacturing workpiece

建立了以激光位移传感器为测量核心的增材制造在线测量系统,并对增材制造工件进行了在线三维形状测量。首先采用计算点云中两临近点斜率的方法计算工件边缘并测量工件长度;然后对工件点云及数模点云进行粗配准及精配准,并提出了基于z向坐标约束及曲率约束的点云临近点迭代精配准方法;最后将配准后的工件点云与数模点云进行对比,计算工件加工余量不足区域的坐标及范围。实验表明测量系统不确定度小于0.1 mm,长度误差率小于0.1%,测得样件表面4个区域存在加工余量不足风险,实现了增材制造过程中针对工件上表面形变量的三维在线测量。

An additive manufacturing online measurement system with laser displacement sensor as the measurement core was established,and online three-dimensional shape measurement was carried out on additive manufacturing workpieces.Firstly,the method of calculating the slope of two adjacent points in the point cloud is used to calculate the edge of the workpiece and measure the length of the workpiece.Then,the workpiece point cloud and digital analog point cloud are coarsely registered and fine-registered,and an iterative fine-registration method for point cloud proximity points based on z-direction coordinate constraint and curvature constraint is proposed.Finally,the registered workpiece point cloud is compared with the digital analog point cloud,and the coordinates and range of the workpiece machining allowance area are calculated.The experiment results show that the uncertainty of the measurement system is less than 0.1 mm,and the rate of deviation with length is lower than 0.1%,and there is a risk of insufficient processing allowance in the four areas of the measured surface of the sample,which realizes the three-dimensional online measurement of the deformation variable of the upper surface of the workpiece in the process of additive manufacturing.