Research On 3D Shape Measurement Of Parts For Metal Additive Manufacturing Process

Through the development in recent years,metal additive manufacturing technology has gradually become an important manufacturing method,whose applications are also increasing.However,due to the material characteristics of the manufacturing process and the particularity of the manufacturing method,some defects or deformations will occur in the manufacturing process parts,so that the manufacturing precision of the manufacturing workpieces still falls short of the traditional manufacturing method.In order to measure the three-dimensional topography of parts during the printing process,based on the principle of non-contact optical three-dimensional measurement technology,this paper proposes a three-dimensional topography measurement technology based on binocular structure light.This method improves the speed of the traditional structured light measurement,structured light encoding and decoding.In addition,this paper includes the optical properties of the metal surface measurement of the important technologies such as research,design and development of the binocular color structured light system model,and set up the software and hardware platform where additive manufacturing process can be used in the three-dimensional parts topography.The research contents of this paper include the following points:(1)To study the mathematical model of binocular stereo vision and its basic principle,analyze the characteristics of binocular stereo vision measurement method,and establish a systematic model suitable for the measurement of three-dimensional topography of parts in metal additive manufacturing.Studying the technology of color structured light coding.A decoding technology based on composite grating is proposed to realize the phase resolution through the single-color optical coding.(2)The traditional phase unwrapping technique is analyzed.Based on this,a phase unwrapping method based on pseudo-random sequence is proposed to realize the absolute phase without reference point.Analyzing the surface optical properties of metal additive manufacturing parts,analyzing the influence of the surface optical properties on the 3D reconstruction from the reflective model and CCD camera model,and putting forward a technique to eliminate the influence of the reflection on the reconstruction process.(3)To analyz the causes of color distortion in the process of color image acquisition,and propose a color correction method to correct the color distortion in the collected images by combining the surface optical properties of metal additive parts.(4)Combined with the measurement system model proposed in this paper,the software and hardware experiment platform is set up,and the typical parts are selected for measurement and analysis.