Research On Abrasive Group Force Transfer Law And Material Removal Characteristics Of Pneumatic Grinding Wheel

Nowadays,many high-tech products require more and more precision for large-surface modeling,and the demand for such complex curved parts is increasing,resulting in a single use of traditional flexible tools with free abrasives.It is difficult to meet the efficiency requirements of actual processing applications.There is an urgent need to improve the processing quality of workpiece surfaces while improving the processing efficiency of complex curved parts.Aiming at the problem of precision machining of complex curved surface of soft-solidified abrasive grain pressure wheel,an analytical model of the soft-solidified abrasive group dilatancy effect is proposed.Taking the microscopic angle of view as the entry point,the influence of the microscopic dilatancy effect of the soft-solidified abrasive grain group of the pneumatic grinding wheel on the material removal characteristics of the workpiece was studied.It was verified by corresponding simulation,force test and processing test.The main contents are as follows:(1)Based on the microscopic analysis method,the mathematical model of the damping coefficient of the porosity and bonded abrasive system was established based on the microscopic dilatancy reduction structure analysis of the abrasive grain group.The dilatant constitutive equation of soft-solidified abrasive grain group is established by means of mean square gradient method.The dilatancy effect of abrasive particles in flexible support environment and the dilatancy effect of abrasive grain group in different damping coefficient binders are analyzed.The influence of the change of the void ratio on the contact surface solves the difficulty of the mechanical analysis of the particle group in the non-fixed state of the complex surface processing.(2)Through PFC3D simulation,the different degrees of dilatancy and shearing of the abrasive grains in different damping coefficient binders were analyzed,and the internal porosity ratio was changed differently.The force sensor's force measuring device is used to verify the influence of the dilatancy effect on the contact force.The contact stress can be changed by the adjustment of the damping coefficient.The dynamics of the soft-solidified abrasive group under the dilatancy state are revealed by simulation and experimental analysis.(3)Based on the viscoelastic constitutive model of the soft-solidified abrasive grain group,a mathematical model of the damping coefficient of the porosity and bonded abrasive system is established.According to the micro-shutter expansion and shearing principle of the abrasive grain group,and the relationship between the pore ratio of the abrasive wheel and the average stress,the stress equation of the abrasive grain bonding layer and the action contact surface of the pneumatic grinding wheel is obtained.Combined with the Hertzian contact theory,the coefficients of the Preston equation are modified to correct the stress equation of the abrasive micro-shear expansion effect of the elastic abrasive grain bonding layer under flexible support conditions.A theoretical model for the material removal of the workpiece material was established for the polishing experiment of the soft-solidified abrasive grain grinding wheel.(4)Through the material removal test,the binder and abrasive grain size with different damping coefficients all affect the material removal factor.By adjusting the damping coefficient and particle size between the abrasive grains,the microscopic force chain distribution law can be changed to achieve processing.Improved surface quality and material removal and reduced scratch damage during processing.The material removal model of the grinding wheel during the actual polishing process was fitted to verify the feasibility of applying the equation to the quantitative analysis of material removal of soft-solidified pneumatic grinding wheel.According to the law of dilatancy effect,the binder damping coefficient can be increased to increase the amount of surface mold material removal.In the same processing time,the damping coefficient is increased by about 5.0×10~5,the material removal amount is increased by nearly 31.91%,and the surface mold roughness is improved.Nearly 32.34%,the scratch damage of the workpiece is significantly reduced.The research results of this paper lay a theoretical foundation for the high-precision and high-efficiency machining of complex curved workpieces,and also provide operational guidance for the processing of complex curved workpieces.