Material Removal Mechanism Of Lapping TC4 Titanium Alloy By Fixed Abrasive

The quality of aero-engine blade directly determines the performance of the engine,such as work efficiency and service life.In order to meet the requirements of the blade,the blade material is usually high strength,high heat and corrosion resistance and high thermal fatigue resistance,such as titanium alloy or superalloy.The fixed abrasive lapping has the advantages of high processing efficiency and good controllability of the process.It has been widely applied to the precision and ultra-precision processing of brittle materials,plastic metals,etc.In this paper,the method for lapping titanium alloy using fixed abrasive spherical head is proposed.Based on the theoretical analysis and experimental,the influence of process parameters on the lapping results was explored,and the material removal mechanism during fixed abrasive lapping was studied.The main research work and results are as follows:(1)The material removal model and the contact model during fixed abrasive spherical head lapping was established.The effects of different process parameters on lapping contact behavior and material removal rate were analyzed by mathematical modeling.The effects of spherical head radiu,lapping pressure and lapping angle on the stress and strain of various components of the lapping system were studied by finite element simulation.(2)The fixed abrasive spherical head was designed and made,and the single point lapping experiment was carried out using planar TC4 titanium alloy as the research object.The material removal rate and the surface roughness were used as indicators to optimize the types,particle diameters of the abrasives and lapping parameters.It was found that the lapping result of 20-30?m silicon carbide is better.The optimal parameters are spindle speed 2000 rpm,lapping angle 30° and lapping time 10 second,which material removal rate is 0.37 mg/s,surface roughness is 700 nm.Under this condition,the material removal rate is high and the roughness requirement of the workpiece is satisfied.(3)Process parameters of plane lapping were optimized.The effects of lapping distance,spherical head movement speed,feed depth and spindle speed on material removal rate,surface roughness and flatness of the workpiece were studied.The optimal lapping parameters are lapping distance 2 mm,spherical head movement speed 600 mm/min,feed depth 0.15 mm,and spindle speed 2000 rpm,which material removal rate is 0.67 mg/s,surface roughness is 149 nm,and value of flatness is 4.05 um.At this time,the material removal rate is the high,and the surface roughness and the flatness of the workpiece are good.(4)The path of plane lapping was optimized.Repeated lapping experiments were carried out.It was found that the surface of workpiece is regularly undulating after lapping.The lapping path was optimized based on the above results.When the lapping path is optimal,the material removal rate is 1.19 mg/s,surface roughness is 201 nm,and value of flatness is 3.86 ?m.At this time,the material removal rate is high,and the workpiece flatness is better.