Optimization Of Magnetorheological Fluid And Processing Parameters

Magnetorheological Finishing(MRF) can achieve ultra-smooth surface. MRF belongs todeterministic processing and can polish complex surfaces. Workpiece processed by MRF has asmaller sub-surface damage layer. Based on MRF,the dissertation focuses on optimizing of polishingprocess. The main work and results are as follows:1. To improve the sedimentation stability of MR FluidDeposition of the iron particles had been analyzed. Reunion of iron particles is considered to bethe main reason for the settlement. Reducing reunion of iron particles is an an effective way toimprove the anti-settling property of MR Fluid.Under the single-point anti-settlement model. Byexperiments,it was found that sodium acetate can inhibit the reunion of iron particles. Settlement ratiois0.27after placing6hours. Iron surface modification, using hyperdispersants instead ofconventional surfactant, silane coupling agent can increase the adsorption force of the anchor group.Settlement ratio between0.15to0.2after placing6hours. Based on single-point anti-settlementmodel, it was established multi-point anti-settlement model, which including line anti-settlementmodel, surface anti-settlement model and sphere anti-settlement model. Advantages of multi-pointanti-settlement model are that adsorption force anchor group increased. Experiments show thathexametaphosphate,belonging surface anti-settlement model, can effectively suppress deposition ofMR Fluid. Its settlement ratio is0.08after placing6hours. Chain anti-settlement model was proposed.But its settlement ratio is a little lager than multi-point anti-settlement model.2.To improve the antioxidant stability of MR fluidDissertation study of the relationship between PH value and antioxidant stability of MR fluid.Experiments show that higher PH value is more conducive to slow rust of MR Fluid. Several types ofrust agent had been selected to conduct rust experiments. The results prove that triethanolamine canobviously inhibit the reaction of iron and oxygen. Simultaneously, zero-field viscosity and magneticshear yield stress of MRF has not been affected. It can be concluded that antioxidant stability of MRfluid which added with triethanolamine can be improved.3.To search relationship between processing parameters and shape of removal functionIt was proposed to calculated diameter, depth, volume of spot with MATLAB program. Themethod is simple, fast and high-precision. Experiments were established to explore the relationshipbetween shape of spot and processing parameters which including processing depth, discharge of MRfluid, iron granularity, concentration of cerium oxide and cerium oxide granularity.It provides a database for MRF. Appropriate processing parameters should be selected according to the actualprocessing requirements. Some occasions which need mass material removal(such as roughprocessing), large processing depth, processing depth, iron granularity and concentration of ceriumoxide should be a priority. Same time small cerium oxide granularity should be also first choice.Experiments prove that discharge of MR fluid varies from40to50ml/min, iron granularity variesfrom2.5to4μm, cerium oxide granularity varies from1.2to1.8μm have little impact on the shape ofspot. Such process parameters are suitable for surface modification or other deterministic processing.4.To optimize polishing process parameters based on orthogonal experimentMaterial removal rate and surface roughness are selected as the target processes. Main factorsincluding processing depth, discharge of MR fluid, concentration of cerium oxide and cerium oxidegranularity had been considered. Orthogonal experiment with four factors and three levels had beenconducted in order to search the law between main factors, removal rate,and surface roughness. Graycorrelation analysis had been adopted to optimize the two target processes.