Study Of Magnetic Memory Nondestructive Testing On Stress Concentrated In Cold Rolling Bearing Rings

Bearing rings,which have been widely used in automobiles,ships,aircraft,industrial equipment and other machinery and equipment manufacturing and industrial fields,are the main components of bearings.Cold rolling is an important means of bearing ring production.In the process of cold rolling production,the original defects such as holes and inclusions in the bearing ring are continuously expanded and aggregated,resulting in a variety of microscopic crack defects and stress concentration.At present,the non-destructive testing of surface defects of bearing rings is in the initial stage.Therefore,it is of great significance to accurately predict and judge the high-risk areas such as micro-crack defects and stress concentration of rolling bearing rings,and realize the rapid detection of dangerous parts.The main purpose of this paper is to detect the stress concentration and other high-risk areas of cold rolling bearing rings by using metal magnetic memory method.This study provides a theoretical basis and technical method for the quality inspection of cold-rolled bearing rings.Based on the study of the stress and strain distribution in the defect areas during the cold rolling process,the variation law of the magnetic memory signal at the defect of the cold rolling bearing rings was studied,and verified by cold rolling test and metal magnetic memory test.The main research contents are as follows:(1)Based on the theory of ring rolling,the finite element model of bearing ring rolling with defects is established,which obtained the stress and strain distribution near the defect in the process of ring rolling.The influence of rolling deformation and defect parameters on stress and strain field is analyzed.The results show that there is a slight difference between the stress state in the vicinity of the defect and the base region during the cold rolling process.With the increase of rolling deformation,the stress level near the defect increases gradually.The smaller the initial size of the hole,the more easily the defect area is surrounded by high stress zones during the cold rolling process.The location,form and depth of the defect will affect the stress distribution in the hole region.(2)Based on the principle of metal magnetic memory detection,the finite element simulation model of magnetic memory test of cold rolling bearing rings is established.The simulation results reveal the change mechanism of magnetic memory signal during the detection process.The variation of the magnetic memory signal at the defect is analyzed,and the influence of the measurement path,the height of the extraction and defect burial depth is studied.The simulation results provide a theoretical basis for the realization of magnetic memory nondestructive testing on the stress concentration of cold rolling bearing rings.(3)The cold rolling test and the metal magnetic memory test were carried out.The characteristics and changing regularity of magnetic memory signals of bearing rings are preliminarily explored.The results show that the metal magnetic memory detection method can effectively detect the damage of the cold rolling bearing rings with stress concentration,and the normal magnetic field intensity gradient as the characteristic parameter can effectively characterize the high risk area of the component.