Three-dimensional Detection System For Buried Morphology Of High-frequency Resistance Welding With Structured Optical Scanning

The high-frequency electric resistance welding(HF-ERW)welded pipe has the characteristics of low cost and stable application performance,and has been applied in many important industrial fields.Due to the extensive application of straight seam high frequency resistance welded pipe and its rapid development,its quality problem has been paid more and more attention both at home and abroad.Because the quality of the weld is related to the surface burrs after welding,in this paper,the weld burrs of the straight seam high frequency resistance welding pipe are detected in order to obtain the effective parameters of the welding quality inspection.In this paper,the shape of high-frequency resistance welding seam is taken as the object of detection,the key technologies of line structure light vision sensor,sensor parameter calibration,structural light high precision light bar center extraction,system principle prototype construction,host computer software design and other key technologies are studied,and the structural light visual inspection system which can realize the three-dimensional inspection of the geometrical features of the weld shape is designed,which has great theoretical and practical value for the quality control and detection of high-frequency resistance pipe welding.In the process of studying the three-dimensional topography of glitches in the scanning of the wire structure,firstly,the simplified scanning model of the detection system is given,and the mathematical measurement mod-el of the detection system is established by the perspective projection principle,which makes the relationship between the pixel coordinate points and the coordinates of the world coordinates be established.And further the mathematical model of the three-dimensional structure of the structured light scanning is composed of the simplified scanning model and the mathematical measurement model of the detection system.Secondly,the geometric model of the optical sensor is used to realize the calibration of the structural light vision sensor.The geometric parameters of the camera imaging are obtained by the internal parameter calibration of the structural light vision sensor,which can describe the relationship between the three-dimensional coordinates of the camera from the three-dimensional coordinates of the camera to the two-dimensional coordinates of the image.The relationship between the camera coordinate system and the world coordinate system is obtained by the external standard calibration of the structural light vision sensor,and the relationship between the two-dimensional image coordinates and the world coordinate system is established.Practice has proved that the accuracy of this method can be up to 0.03 mm.In addition,a method of extracting the center of the structure is proposed by using the directional block,which can obtain the sub-pixel center of the structural light stripe accurately and quickly,and improve the measurement accuracy of the system.Finally,the standard mass experiment is carried out in combination with the mathematical model of the system and the precise extraction method of the structural light stripe center.The experimental results verify the real-time effectiveness of the structured light scanning 3D detection system.Simultaneously,the dynamic scale detection of the burr surface of the weld surface is carried out,and the 3D point cloud image of the weld surface is drawn.The experiment has achieved good results.