Study On Abrasive Water Jet Dressing Technology Of Fixed Abrasive Lapping Pad

Fixed abrasive machining technology is widely used in the field of ultra-precision machining,due to its high machining efficiency,less damage to the subsurface of the workpiece,high abrasive utilization,and environmental protection.However,the fixed abrasive lapping pad as the core technology will produce the phenomenon of “glazing” in the later stage of processing,which will reduce the processing efficiency and processing quality of the workpiece material.Therefore,it is necessary to properly dress dull the fixed abrasive lapping pad.The dressing method and dressing quality have a certain influence on the processing performance of the fixed abrasive lapping pad.Aiming at the problems of poor dressing effect and a high degree of damage in the existing fixed abrasive dressing technology,this paper proposes a new technology for dressing the fixed abrasive lapping pad using an abrasive water jet.To improve its dressing efficiency and dressing quality.The main research contents are as follows:（1）Construction of Abrasive Water Jet Dressing SystemSelf-designed and built a set of abrasive water jet dressing system.The system is mainly composed of a power system,abrasive supply system,nozzle system,motion control system,etc.It can ensure the stable and continuous dressing of the fixed abrasive lapping pad and ensure that the dressing trajectory is controllable.（2）Optimization of Abrasive Water Jet Dressing Process Parameters for Fixed Abrasive Lapping PadThe influence of jet pressure,nozzle target distance,abrasive concentration and spray angle on the dressing effect of W7 diamond fixed abrasive lapping pad was investigated by the single factor test method.The results show that the dressing effect first increases and then decreases with the increase of jet pressure,nozzle target distance and spray angle,and increases with the increase of abrasive concentration.The influence of jet pressure,nozzle target distance,abrasive concentration and injection angle on the machining performance of the W7 diamond bonded abrasive lapping pad was investigated by orthogonal experiment,and its dressing process parameters were optimized.The results show that the significant factors affecting the processing performance of the jet system after dressing the fixed abrasive lapping pad are C（abrasive concentration）> D（spray angle）>A（jet pressure）>B（nozzle target distance）.The optimal process parameter combination is jet pressure 4MPa,nozzle target distance of 15 mm,abrasive concentration of 7%,and spray angle of70°.The interaction among jet pressure,abrasive concentration and spray angle was investigated by response surface methodology,and a regression prediction model for the machining performance of fixed abrasive lapping pads was established.The results show that the interaction between various factors will affect the processing performance of the fixed abrasive lapping pad to varying degrees.The regression prediction model obtained by the experiment is used to optimize the process parameters of the jet system,and a set of optimal solutions within the range of process parameters are obtained: the jet pressure is 3.8MPa,the abrasive concentration is 3%,and the spray angle is 73°.Comparing the material removal rate of quartz glass predicted by the regression model with the actual test results,it is found that the difference between the two is only4.562nm/min.It shows that the established regression prediction model has high accuracy.（3）Study on the Mechanism of Dressing Fixed Abrasive Lapping Pad with Abrasive Water JetThe discrete element simulation method analyzes the microscopic phenomenon of the influence of different jet pressure,nozzle target distance,abrasive concentration and spray angle on the abrasive water jet dressing the fixed abrasive lapping pad.The dressing mechanism of abrasive water jet dressing of the fixed abrasive lapping pad was explored.The simulation results show that the influence mechanism of each parameter is closely related to the surface residual height of the fixed abrasion lapping pad.The higher the surface residual height is,the rougher the surface of the fixed abrasive lapping pad is,the better the dressing effect is.The influence trend of different process parameters on the removal rate of workpiece material is basically consistent with that of residual height of the lapping pad obtained by simulation.