Study On Grinding And Polishing Process Of Commercial Pure Titanium Based On Fixed Abrasive

Commercial pure titanium has many advantages such as high specific strength,high corrosion resistance,and biocompatibility,etc.It is extensively adopted in medical equipment,aerospace equipment,chemical equipment,and marine equipment.For example,the shells of centrifuge commonly used in modern industry mostly made of commercial pure titanium to improve its corrosion resistance.For large centrifuge shells,which are susceptible to immersion and corrosion by inorganic acids due to their large surface area,nickel plating is required,and the uniformity and adhesion strength of the coating are limited by the processing quality of the shell surface.However,due to the low hardness,strong plasticity and low thermal conductivity of commercial pure titanium,the traditional grinding and polishing is prone to generate grinding heat and cause surface damage,the processing quality is difficult to guarantee,and the processing efficiency is not high.Based on this,this paper puts forward a new technology of grinding and polishing commercial pure titanium by fixed abrasive,and explores the material removal mechanism of fixed abrasive grinding,in order to obtain high quality processing surface efficiently,provide theoretical basis for the formulation of process parameters,and also provide new ideas for the application of fixed abrasive technology.The main work carried out in this paper includes:(1)Preparation of fixed abrasive padThrough single factor experiment,the effects of different abrasive shapes on the commercial pure titanium’s material removal rate and surface roughness were compared and analyzed.The results indicate that abrasive with irregular shape is prone to improve the processing efficiency.Therefore,so as to improve the grinding efficiency,abrasive particles with irregular shape should be used in the preparation of fixed pad.In order to guarantee the service effect of fixed abrasive pad,the influence of grinding time on commercial pure titanium grinding effect is analyzed by single factor experiment.The results indicate that when grinding time is 15 minutes,the fixed abrasive pad can process commercial pure titanium and obtain better grinding effect.(2)Process parameter analysis of fixed abrasive grinding commercial pure titaniumOrthogonal experiment was used to analyze the influence of different process parameters on surface roughness and material removal rate when grinding commercial pure titanium with fixed abrasive.The results show that grinding pressure and p H value have greater influence on surface roughness,while grinding pressure and grinding disc speed have greater influence on material removal rate.(3)Optimization of process parameters for fixed abrasive grinding of commercial pure titaniumIn order to overcome the limitation of orthogonal experiment in parameter selection quantity,BP neural network is used to train grinding experiment data,establish the mapping relationship between process parameters and surface roughness,and particle swarm optimization algorithm was used to seek for the optimum process parameters,and the reliability of process parameters was verified by experiments.The results show that the surface roughness mapped by the simulated process parameters is only about 2% different from that of the experiment,which indicates that BP neural network and particle swarm optimization can effectively optimize the process parameters of commercial pure titanium for fixed abrasive grinding.(4)Experimental study on commercial pure titanium polishingThe polishing experiment of commercial pure titanium was studied by response surface method,and the influence of process parameters on the processing effect of commercial pure titanium during polishing was analyzed.The results indicate that the process parameters which have the most significant effect on the surface quality of commercial pure titanium polishing are: speed > pressure > flow rate.The surface roughness Ra and material removal rates after polishing were 4.6nm and 13.85nm/min respectively.(5)Analysis of the removal mechanism of commercial pure titanium by fixed abrasive grindingThe contact model between the abrasive particles in the fixed abrasive pad and the workpiece was established,and the nanoindentation/scratch experiment was used to simulate the process of single diamond abrasive particles indenting commercial pure titanium,and the mechanical properties of the abrasive and polished parts under different loads were compared.The surface topography characteristics of the workpiece after scribing were analyzed.The results show that the elastic modulus and hardness of the workpiece after grinding with fixed abrasives are relatively high,and there may be work hardening on the surface.From scratch surface morphology,it can be seen that the material has obvious uplift accumulation phenomenon,indicating that the material removal is mainly ductile removal of plastic deformation.