Centering method for stepped shaft and hole assembling process

Abstract

The invention provides a centering method for a stepped shaft and hole assembly process, and the method comprises the steps: photographing an image of a hole part through a calibrated camera, and obtaining the centering deviation of the hole part through an image recognition and ellipse fitting method; adjusting the position of the to-be-assembled hole part by utilizing the centering deviation until the axis of a through hole in the hole part coincides with the axis of the camera, and fixing the hole part and the position of the camera at the moment; shooting an image of each end surface in the assembling process of the stepped shaft through the calibrated camera; obtaining coordinates of a stepped shaft small-diameter end face fitting circle center and a stepped shaft medium-diameter endface fitting circle center by using an image recognition and ellipse fitting method; connecting the two circle centers, calculating the midpoint coordinate of the connecting line, and comparing the midpoint coordinate with the axis coordinate of the hole part to adjust the pose of the stepped shaft to be assembled, so as to realize the centering monitoring of the stepped shaft and the hole. Real-time monitoring and feedback of the centering condition of the stepped shaft and the hole are achieved based on machine vision.

Description

technical field [0001] The invention belongs to the technical field of intelligent assembly, and in particular relates to a centering method for the assembly process of a stepped shaft and a hole. Background technique [0002] The main function of the stepped shaft is to use the shoulders with different radial dimensions to limit the movement of the parts on the shaft to position and install the parts. It is characterized by high manufacturing precision and small fit clearance. In the manufacturing fields of aviation, aerospace, automobiles and ships, the assembly of stepped shaft and hole parts is very common. With the continuous improvement of assembly requirements, the assembly accuracy of the stepped shaft and the hole has been paid more attention. Under the initial conditions, the hole and the stepped shaft are separated, and the centering deviation will inevitably occur during the centering process. Excessive deviation may cause bumps between the end faces of the st...

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Problems solved by technology

[0004] After preliminary research and literature search, the current domestic research status on the shaft hole docking problem is as follows: Guangzhou Zhongchuan Wenchong Dock Co., Ltd. proposed a shaft and shaft hole alignment detection method and alignment detection device, the application publication number is CN109668530A, This method uses laser projection for axis fitting, but it is not applied in the assembly process; Zhangjiagang Chang'an University School of Automotive Engineering Han Yi's team proposed an automatic centering system for shaft hole assembly based on image processing, and the application publication number is CN 106204610A , this method does not consider the unique characteristics of the stepped shaft, and it only elaborates on the conventional shaft-hole fit, which has certain limitations; Cheng Yunyong's team from Northwestern Polytechnical University proposed an assembly alignment method based on machine vision monitoring, and the application publication number is CN 107617876A , using the stepped axis target to determine the assembly pose, this method uses circle fitting in the algorithm without considering the fitting error caused by the initial pose during the assembly process

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