The surface morphology and roughness of a workpiece are crucial parameters in grinding processes.Accurate prediction of these parameters is essential for maintaining the workpiece’s surface integrity.However,the rand...The surface morphology and roughness of a workpiece are crucial parameters in grinding processes.Accurate prediction of these parameters is essential for maintaining the workpiece’s surface integrity.However,the randomness of abrasive grain shapes and workpiece surface formation behaviors poses significant challenges,and accuracy in current physical mechanism-based predictive models is needed.To address this problem,by using the random plane method and accounting for the random morphology and distribution of abrasive grains,this paper proposes a novel method to model CBN grinding wheels and predict workpiece surface roughness.First,a kinematic model of a single abrasive grain is developed to accurately capture the three-dimensional morphology of the grinding wheel.Next,by formulating an elastic deformation and formation model of the workpiece surface based on Hertz theory,the variation in grinding arc length at different grinding depths is revealed.Subsequently,a predictive model for the surface morphology of the workpiece ground by a single abrasive grain is devised.This model integrates the normal distribution model of abrasive grain size and the spatial distribution model of abrasive grain positions,to elucidate how the circumferential and axial distribution of abrasive grains influences workpiece surface formation.Lastly,by integrating the dynamic effective abrasive grain model,a predictive model for the surface morphology and roughness of the grinding wheel is established.To examine the impact of changing the grit size of the grinding wheel and grinding depth on workpiece surface roughness,and to validate the accuracy of the model,experiments are conducted.Results indicate that the predicted three-dimensional morphology of the grinding wheel and workpiece surfaces closely matches the actual grinding wheel and ground workpiece surfaces,with surface roughness prediction deviations as small as 2.3%.展开更多
The existing leakage models,which include smooth plane leakage model,rough and waveform surface leakage model,and tapered-face leakage model,can not be applied to describing the active state of contacting mechanical s...The existing leakage models,which include smooth plane leakage model,rough and waveform surface leakage model,and tapered-face leakage model,can not be applied to describing the active state of contacting mechanical seal.In these models,only prime microscopic surface topography and constant leakage rate are taken into consideration.Based on fractal geometry theory,a leakage model was established with consideration of the change of microscopic surface topography and time-correlation of leakage rate.The relationship between leakage rate,the change of microscopic surface topography of seal surface and leaking channel under operation conditions was described quantitatively by fractal parameter with unattached dimension.There existed an optimum fractal parameter during the mechanical seal running,which corresponded to the lowest leakage rate.The research results helped to ascertain the roughness and waviness of seal surface,and to select machining methods of sealing members.According to the leakage model presented in this paper,the leakage rate of contacting mechanical seal can be forecasted,which may be used as reference in the maintenance and operation of mechanical seals.展开更多
基金Supported by Special Fund of Taishan Scholars Project(Grant No.tsqn202211179)National Natural Science Foundation of China(Grant No.52105457)+2 种基金Shandong Provincial Young Talent of Lifting Engineering for Science and Technology(Grant No.SDAST2021qt12)National Natural Science Foundation of China(Grant No.52375447)China Postdoctoral Science Foundation Funded Project(Grant No.2023M732826).
文摘The surface morphology and roughness of a workpiece are crucial parameters in grinding processes.Accurate prediction of these parameters is essential for maintaining the workpiece’s surface integrity.However,the randomness of abrasive grain shapes and workpiece surface formation behaviors poses significant challenges,and accuracy in current physical mechanism-based predictive models is needed.To address this problem,by using the random plane method and accounting for the random morphology and distribution of abrasive grains,this paper proposes a novel method to model CBN grinding wheels and predict workpiece surface roughness.First,a kinematic model of a single abrasive grain is developed to accurately capture the three-dimensional morphology of the grinding wheel.Next,by formulating an elastic deformation and formation model of the workpiece surface based on Hertz theory,the variation in grinding arc length at different grinding depths is revealed.Subsequently,a predictive model for the surface morphology of the workpiece ground by a single abrasive grain is devised.This model integrates the normal distribution model of abrasive grain size and the spatial distribution model of abrasive grain positions,to elucidate how the circumferential and axial distribution of abrasive grains influences workpiece surface formation.Lastly,by integrating the dynamic effective abrasive grain model,a predictive model for the surface morphology and roughness of the grinding wheel is established.To examine the impact of changing the grit size of the grinding wheel and grinding depth on workpiece surface roughness,and to validate the accuracy of the model,experiments are conducted.Results indicate that the predicted three-dimensional morphology of the grinding wheel and workpiece surfaces closely matches the actual grinding wheel and ground workpiece surfaces,with surface roughness prediction deviations as small as 2.3%.
文摘The existing leakage models,which include smooth plane leakage model,rough and waveform surface leakage model,and tapered-face leakage model,can not be applied to describing the active state of contacting mechanical seal.In these models,only prime microscopic surface topography and constant leakage rate are taken into consideration.Based on fractal geometry theory,a leakage model was established with consideration of the change of microscopic surface topography and time-correlation of leakage rate.The relationship between leakage rate,the change of microscopic surface topography of seal surface and leaking channel under operation conditions was described quantitatively by fractal parameter with unattached dimension.There existed an optimum fractal parameter during the mechanical seal running,which corresponded to the lowest leakage rate.The research results helped to ascertain the roughness and waviness of seal surface,and to select machining methods of sealing members.According to the leakage model presented in this paper,the leakage rate of contacting mechanical seal can be forecasted,which may be used as reference in the maintenance and operation of mechanical seals.
