On-line Measurement Of Flatness And Profile Of SLM Forming Process Based On Surface Structure Light Three-dimensional Measurement Technique

Selective Laser Melting(Selective Laser Melting,SLM)is an advanced metal rapid prototyping process that is widely used in defense,energy,aerospace,medical and commercial applications.However,there are many influencing factors in the forming process and the forming process is complicated.So the forming process needs to be monitored to study the forming mechanism.Moreover because the forming parts are often difficult to measure complex shapes,visual on-line measurement can be used as an effective means to monitor the forming process and to measure the forming parts.In order to realize the detection of parts edge contour and three-dimensional topography and the monitoring of part forming,the three-dimensional measurement technology,image edge extraction technology and binocular stereo vision measurement technology are studied in this paper.According to the structure and measurement requirements of selective laser melting forming equipment,a hardware module of online visual measurement system is designed and manufactured.Finally,the parts are formed and measured on the SLM forming equipment.Here are the main work this paper include:(1)The three-dimensional measurement principle of vision is studied,such as the imaging model of camera,the three-dimensional measuring principle of surface structure light.According to the actual use environment of the measuring system,the self-calibration technology of the opposite structure is studied and researched,and the design experiment verifies the accuracy of the self-calibration technology.(2)The three-dimensional measurement of edge contours is studied,such as edge feature extraction in image,fitting of ellipse and straight edge,and the stereo matching technology of left and right camera in binocular stereoscopic vision and 3D reconstruction technology are studied.Dimensional reconstruction of simple edge is realized,and the accuracy of 3D reconstruction is verified.(3)According to the structure and demand of SLM forming equipment,the hardware selection and structure design of the on-line measurement system are completed,and the rationality of the structure is verified by the finite element method.(4)According to the measurement requirements of the forming equipment,the registration method of the coordinate system of the on-line measurement system is studied and the registration precision is verified.The measurement timing of the measurement system in the forming process is designed,and the measurement of the forming part is completed in the actual forming process.