An Experimental Study on Electrochemical Mechanical Finishing of Bearing Raceway Surfaces
|Course||Mechanical Design and Theory|
|Keywords||Bearing raceway Eletrochemical mechanical finishing Sufacemorphology Surface roughness|
Rolling bearings are widely used in industry,agriculture,transportation,national defence,aerospace, household appliances,office machinery and high technology.They are of importance to the people’s livelihood. There are about80%of the bearings in the world used in industrial and agricultural machinery,and transportation equipment like cars,trains,aircraft.Now the bearing raceway superfinishing always make the quality of processing surface deteriorate caused by unstable machining process in which the grinding wheel and oilstone are easy to block.The high relative speed of grinding tool and workpiece exacerbates the problem.The blocking of abrasive tools is more serious caused by large processing area, high original surface roughness and large machining allowance in finishing process of medium and large rolling bearings. Even the superfinishing process with advanced oilstone also has defects caused by mechanical cutting.Electrochemical mechanical machining realizes a high speed and quality of surface processing by the method Combining electrolyte removal and mechnical finishing.As a typical composite technology of traditional finishing and non-traditional finishing machining,it can make the most of advantages of the two methods and make up their shortages.And It Is a very promising processing technology and the application of it has important implications for Improving the level of bearing manufacture of China. Therefore,to solve problems of electrochemical mechanical finishing of bearing raceway, this thesis does the following:The principle of anodic dissolution in electrochemical machining is studied and the finishing mechanism and processing characteristics are analyzed according to the chemical thermodynamics and chemical kinetics of electrode process.According to the characteristics of the bearing raceway,the electrochemical mechanical finishing test bed of inner ring raceway is established.The problems,like cathode design, electrolyte flow and filter workpiece fixture design and pressure control mode of abrasive tools,are discussed.Several flow fields were simulated and analyzed by Fluent.Taking the inner rings of a kind of domestic manufacturing cylindrical roller bearing as workpieces, The orthogonal experiments and single factor experiments are used to analysis the influence of machining parameters to surface roughness and the optimal combination of process parameters and surfaces of Ra0.04μm are obtained.Surfaces of different machining methods are observed through SEM and characteristics of microtopography are analyzed contrastivcly. Surfaces of electrochemical machining are analyzed through chemical energy spectrum and the theory of phaseformed passive film is proved. The mechanism of electrochemical mechanical finishing machining is verified by analyzing the Surface which have incomplete passive film.The research results show that it is feasible of machining bearing raceway by electrochemical mechanical finishing.It can solve problems which conventional mechanical superfinishing has and the surface of electrochemical mechanical finishing has a microtopography which has good friction and wear performance.