Research On Assembly Quality Inspection System Of Piston Ring Based On Machine Vision

As the core component inside the engine,if the piston ring is improperly assembled,it will directly affect the tightness between the piston and the cylinder,causing a series of problems such as the reduction of the engine compression ratio,difficulty in starting and insufficient power.With the continuous development of my country’s manufacturing industry,for the assembly method of piston rings,a mainstream semi-automatic assembly method,supplemented by manual participation and mainly by assembly machines,has been formed.Although this assembly method can well realize a variety of piston rings,but due to the accumulated errors,faults and manual operation errors of the machine itself,the piston rings are misassembled and missing,so that the assembly quality of the piston rings cannot be guaranteed.However,due to its own limitations,it is difficult to ensure the efficiency and accuracy of the inspection by using the traditional manual visual inspection method for quality inspection in the assembly process.Therefore,in view of the above-mentioned semiautomatic assembly methods that are prone to wrong assembly and missing assembly,this paper adopts the method of visual inspection,combined with related technologies such as error prevention,automatic control and digital image processing,to carry out a real-time analysis of piston ring assembly quality.The research on the online inspection system,through the analysis and processing of the piston ring surface and piston side images collected during the assembly process,completes the real-time feedback of the unqualified situation of the piston ring assembly,improves the qualified rate of the assembled finished product,and is very important for the realization of the high quality of the piston ring,highefficiency assembly is of great significance.This paper is mainly aimed at a mainstream semi-automatic assembly machine for piston ring assembly on the market.It is developed with a modular idea to complete the online detection of the wrong and missing installation of the two gas rings in the assembly process,and make the detection The system can be retrofitted directly to semi-automatic assembly machines.The specific research work of this paper is as follows:(1)The research on machine vision technology and piston ring assembly technology has been carried out,and the overall solution of the system has been determined according to the actual production cycle of the assembly machine and the overall requirements of the inspection system;(2)According to the structure of the piston ring and the piston and their surface optical properties,a combined lighting scheme of the ring light source above the assembly station and the side strip light source is proposed.Accurate acquisition of images of piston ring assembly quality inspection content;(3)The detection requirements of the system and the characteristics of each detection content in the image are analyzed.According to different detection content,the image is filtered,binarized,image morphology,feature extraction,template matching and other processing,and the piston ring assembly is realized.Error-proof and leak-proof detection function in the process;(4)The man-machine interface of the inspection system is written in the Qt Creator development environment,and the software framework of the system is built in combination with the Open CV visual development library and the SQLite3 lightweight database.According to the specifications and parameters of different types of piston rings and pistons to be inspected,the corresponding The testing program realizes the on-line testing of the assembly quality of the multi-variety piston rings;and the validity and testing accuracy of the testing system are verified by experiments.