Process Analysis And Machining Accuracy Research In Inner Round Grinding Of Zirconia Ceramic Bearing Rings

Ceramic bearings have excellent properties such as wear resistance,corrosion resistance,high and low temperature resistance,long service life,non-conducting,and non-magnetic conductivity and other traditional metal bearings do not have,and have a wide range of application prospects in the aerospace,defense and military industry,energy chemical industry,equipment manufacturing and other fields.However,properties of ceramic materials themselves lead to problems such as substandard surface quality and poor roundness during processing of ceramic bearing rings,which brings great challenges to precision processing and wide application of ceramic bearings.Therefore,it is urgent to explore a suitable manufacturing process for ceramic bearing rings.In this paper,we took 7009 C zirconia bearing outer ring as the research object.Based on the analysis of the grinding removal mechanism of zirconia material,the surface roughness and roundness variation law of zirconia rings under different processing conditions were studied through experiments to provide theoretical basis for the processing and manufacturing of ceramic bearing rings.The research contents are as follows:(1)Ceramic material removal processes(including slip rubbing,plowing and chip formation)and removal methods(including plastic removal,brittle removal,powdered removal)were summarized.Based on the surface breakage damage model,the law that the surface breakage rate was mainly determined by the grinding wheel characteristics,ceramic material properties and grinding parameters was explained.The calculation formula of the maximum undeformed chip thickness was derived,and the relationship between the maximum undeformed chip thickness and the grinding grain diameter,workpiece speed,grinding wheel speed,grinding depth,and grinding wheel equivalent diameter was obtained.The effect of grinding modes on grinding force,grinding temperature,and grinding surface integrity was investigated,which was an important guideline for engineering ceramic grinding processing.(2)Grinding experiments on zirconia ceramic workpieces were carried out,and it was found that the surface quality of grinding zirconia workpieces for down grinding was better than that for up grinding under the same grinding parameters.The grinding parameters had different degrees of influence on the surface roughness of zirconia ceramic workpiece,and the grinding depth had the greatest influence on the surface roughness,followed by the grinding wheel speed,and the workpiece feed rate had no significant influence on the roughness.At the same time,a predictor model for surface roughness was established and the correctness of the model was verified,which provided a theoretical basis for grinding process of ceramic rings.(3)Grinding experiments of zirconia ceramic ring were performed,and it was found that the surface roughness of ceramic ring decreased with decreasing grinding wheel grain size,decreased with increasing grinding wheel speed and workpiece speed,and increased with increasing grinding wheel feed rate and axial oscillation rate.It was revealed that the influence of every process parameter on surface roughness of ceramic ring was in the following order:grinding wheel grain size,grinding wheel speed,axial oscillation rate,grinding wheel feed rate,workpiece speed.And the optimal combination was recommended for inner round grinding of zirconia ceramic rings.(4)The main factors that affect the roundness of ceramic rings were revealed to be the clamping method of bearing ring and the size of clamping force,and four methods of evaluating roundness error were introduced.In addition,the minimum clamping force of bearing ring was calculated,and the formula of radial deformation of bearing ring was derived.Finally,it was revealed that the deformation of ring decreased with the increase of the number of contact points and increased with the increase of the clamping force.(5)Grinding experiments of zirconia ceramic ring were designed,and it was found that the smallest roundness error of ring was machined by the pneumatic clamping method.During the increase of clamping force from 0.10 MPa to 0.25 MPa,the roundness error of ceramic rings processed by three different clamping methods increased continuously.However,roundness error of the rings machined by the pneumatic clamping method had the least variation.It was analyzed that pneumatic fixture clamping method was more advantageous than conventional three-jaw chuck clamping method for machining high precision ceramic bearing rings.This paper provides an effective method for precision machining of ceramic bearing rings,and the research results are an important guide for improving the surface quality and roundness of ceramic bearing rings,as well as providing a technical basis for the precision machining and popularization of key components of ceramic bearings.