The Hole Position Correction And High Precision Repeated Positioning Technology Of Automatic Drilling And Riveting Machine

In the drilling task of the outer skin of the launch box,the accuracy of hole-making position directly affects the assembly quality of the product.Due to the influence of manufacturing error and system calibration error,there is a deviation between the theoretical hole position and the actual hole position,which needs to be corrected online.In addition,the drilling and riveting of the outer skin of the launch box are two separate processes and need to be re clamped during product assembly,which will cause a new problem to the repeated positioning for the riveting process.In order to solve the above problems,this paper focuses on the hole position correction and repeated positioning methods of the automatic drilling and riveting machine tools.The main research contents are as follows:(1)The positioning error chain of drilling and riveting in automatic riveting system was analyzed,the main positioning error sources were determined,and the hole position correction and secondary positioning method based on the datum hole was put forward in combination with the hole position distribution characteristics on the product,and the correction and positioning accuracy were verified by simulation.(2)A method of detecting and locating the datum hole by vision system was proposed.The imaging characteristics of the circular hole in the camera were simulated by using the pinhole imaging model.The relationship between the camera object distance and the ellipse long axis of the circular hole image was established,and the correctness of the model was verified by experiments.(3)The algorithm of extracting and fitting the circular holes in the image was studied.The method of extracting the boundary of the circular hole based on OTSU and an ellipse fitting method based on the idea of RANSAC were proposed,which can effectively solve the separation problem of the inner wall of the hole and the front wall plate.Through comparative test and analysis,the fitting algorithm in this paper can effectively improve the ellipse fitting accuracy.(4)Through the simulation of the actual processing flow,the verification scheme of drilling and riveting processing was established.The positioning accuracy of visual inspection,the position correction accuracy of the hole and the repeated positioning accuracy of assembly hole position were verified.The results show that the corrected hole position error and repeated positioning error were within ±0.05 mm,which met the high-precision positioning requirements of the assembly hole of the launch box.