Based on the basic theory of mechanics,kinematic and dynamic analysis for a slider-crank mechanism with a balance mechanism is performed.The theoretical formula of the load spectrum for the interaction between the cra...Based on the basic theory of mechanics,kinematic and dynamic analysis for a slider-crank mechanism with a balance mechanism is performed.The theoretical formula of the load spectrum for the interaction between the crank shaft and the bearing seat of the upper beam is achieved by approximately simplifying the mechanical model of the crank shaft.The simulation for the load spectrum data of combined frame under the operating conditions of blanking or piling is performed using Matlab and the law of the load spectrum curves under these two conditions is analyzed.The simulation results show that under a no-load condition,the load spectrum curves of the interaction between the crank shaft and the bearing seat of the upper beam present a form of periodic sine wave and under the piling condition,the load spectrum curves of the interaction between the crank shaft and the bearing seat of the upper beam present a form of periodic pulse wave.The simulation results can provide a theoretical foundation for the load determination during the process of analyzing the dynamic characteristics on the combined frame of a closed high-speed press through the finite element method.展开更多
A new method combining the slider-crank mechanism dynamic(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effects of CB dimensions and engine speed on the lubrication efficiency and friction ...A new method combining the slider-crank mechanism dynamic(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effects of CB dimensions and engine speed on the lubrication efficiency and friction power loss(LE-FPL)of an engine.The dynamic and lubrication equations are then solved on the basis of the combined model via an algorithm developed in MATLAB.To enhance the reliability of the research results,the experimental data of combustion gas pressure is applied for simulation.The load bearing capacity(or oil film pressure),friction force,friction coefficient,and eccentricity ratio of the CB are selected as objective functions to evaluate the LE-FPL.The effects of engine speed,bearing width,and bearing radius on the LE-FPL are then evaluated.Results show that reductions in engine speed,bearing width,or bearing radius can decrease the FPL but reduce the LE of the engine and vice versa.In particular,the LE-FPL can effectively be improved by slightly reducing the bearing width and bearing radius or maintaining engine speed at 2000 r/min.展开更多
The total load on a crank bearing was calculated by performing a load analysis of the crank connecting rod mechanism. The Reynolds equation for hydrodynamic lubrication of the crank bearing was established at the Reyn...The total load on a crank bearing was calculated by performing a load analysis of the crank connecting rod mechanism. The Reynolds equation for hydrodynamic lubrication of the crank bearing was established at the Reynolds boundary condition and was then solved using the Holland method. From this the regular track of the beating axis was obtained. As the crank beating gradually wears the eccentricity ratio corresponding to the minimum oil film thickness increases gradually. The oil-bound film eventually breaks down, which allows friction and collision between the metal surfaces of the crank pin and the bearing. The rigid impact leads to excitation of high frequency vibrations at the natural frequencies of the connecting rod. The experiments show that the wear condition of the crank beating can be identified correctly through the vibration signature at the natural frequencies of the connecting rod. The degree of wear can be predicted accurately through the energy content of the high frequency bands.展开更多
A new hybrid numerical method that couples the dynamic slider-crank mechanism(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effect of micro asperity contact on the tribological properties o...A new hybrid numerical method that couples the dynamic slider-crank mechanism(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effect of micro asperity contact on the tribological properties of a CB.In the hybrid model,the dynamic equations of the SCM are established based on the Newton method,while the lubrication equations of the CB are established on the basis of the Reynolds equation.Experimental data of the engine are also used in simulation analyses to enhance the reliability of the results.The load-bearing capacity(LBC)and friction force of the CB are selected as objective functions.Results show that the LBC has a negligible effect on the tribological properties of the CB,but the friction force greatly affects the resistance of the bearing under different radial clearances and surface roughness values.In particular,the maximum friction force in the asperity contact region accounts for 40.5%of the maximum total friction force at a radial clearance of 5μm and 77.7%of the maximum total friction of the CB with a surface roughness of 10μm.展开更多
A design of different microtextures on the surface of the crankpin bearing(CB)is proposed to ameliorate the lubrication and friction performance(LFP)of engines.On the basis of the CB s hydrodynamic lubrication model,t...A design of different microtextures on the surface of the crankpin bearing(CB)is proposed to ameliorate the lubrication and friction performance(LFP)of engines.On the basis of the CB s hydrodynamic lubrication model,the bearing surface of CB using different microtextures,such as wedge-shaped textures(WSTs),square textures(STs),circular textures(CTs),and combined square-circular textures(CSCTs),is simulated and assessed under various external loads of the CB at an engine speed of 2000 r/min.The pressure of the oil film,the frictional force,the force of the solid asperity contact,and the friction coefficient of the CB are used as objective functions.Results indicate that the bearing surface designed by the STs remarkably improves the CB s LFP in comparison with other structures of WSTs,CTs,and CSCTs.Particularly,the average values of the frictional force,solid asperity contact,and friction coefficient of the CB using the STs are greatly reduced by 28.5%,14.5%,and 33.2%and by 34.4%,26.3%,and 43.6%in comparison with the optimized CB dimensions and CTs,respectively.Therefore,the application of the STs on the CB surfaces can enhance the LFP of engines.展开更多
基金The Key Technologies R& D Program of Jiangsu Province(No. BE2006036)Transformation Program of Science and Technology Achievements of Jiangsu Province (No. BA2008030)
文摘Based on the basic theory of mechanics,kinematic and dynamic analysis for a slider-crank mechanism with a balance mechanism is performed.The theoretical formula of the load spectrum for the interaction between the crank shaft and the bearing seat of the upper beam is achieved by approximately simplifying the mechanical model of the crank shaft.The simulation for the load spectrum data of combined frame under the operating conditions of blanking or piling is performed using Matlab and the law of the load spectrum curves under these two conditions is analyzed.The simulation results show that under a no-load condition,the load spectrum curves of the interaction between the crank shaft and the bearing seat of the upper beam present a form of periodic sine wave and under the piling condition,the load spectrum curves of the interaction between the crank shaft and the bearing seat of the upper beam present a form of periodic pulse wave.The simulation results can provide a theoretical foundation for the load determination during the process of analyzing the dynamic characteristics on the combined frame of a closed high-speed press through the finite element method.
基金The National Key Research and Development Plan(No.2019YFB2006402)the Key Project of Scientific Research Plan of Hubei Polytechnic University(No.21xjz02A)the Open Fund Project of Hubei Key Laboratory of Intelligent Transportation Technology and Device,Hubei Polytechnic University(No.2020XY105,2020XZ107).
文摘A new method combining the slider-crank mechanism dynamic(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effects of CB dimensions and engine speed on the lubrication efficiency and friction power loss(LE-FPL)of an engine.The dynamic and lubrication equations are then solved on the basis of the combined model via an algorithm developed in MATLAB.To enhance the reliability of the research results,the experimental data of combustion gas pressure is applied for simulation.The load bearing capacity(or oil film pressure),friction force,friction coefficient,and eccentricity ratio of the CB are selected as objective functions to evaluate the LE-FPL.The effects of engine speed,bearing width,and bearing radius on the LE-FPL are then evaluated.Results show that reductions in engine speed,bearing width,or bearing radius can decrease the FPL but reduce the LE of the engine and vice versa.In particular,the LE-FPL can effectively be improved by slightly reducing the bearing width and bearing radius or maintaining engine speed at 2000 r/min.
文摘The total load on a crank bearing was calculated by performing a load analysis of the crank connecting rod mechanism. The Reynolds equation for hydrodynamic lubrication of the crank bearing was established at the Reynolds boundary condition and was then solved using the Holland method. From this the regular track of the beating axis was obtained. As the crank beating gradually wears the eccentricity ratio corresponding to the minimum oil film thickness increases gradually. The oil-bound film eventually breaks down, which allows friction and collision between the metal surfaces of the crank pin and the bearing. The rigid impact leads to excitation of high frequency vibrations at the natural frequencies of the connecting rod. The experiments show that the wear condition of the crank beating can be identified correctly through the vibration signature at the natural frequencies of the connecting rod. The degree of wear can be predicted accurately through the energy content of the high frequency bands.
基金The National Key Research and Development Project(No.2019YFB2006402)the Open Fund Project of Key Laboratory of Intelligent Conveying Technology and Device,Hubei Polytechnic University.
文摘A new hybrid numerical method that couples the dynamic slider-crank mechanism(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effect of micro asperity contact on the tribological properties of a CB.In the hybrid model,the dynamic equations of the SCM are established based on the Newton method,while the lubrication equations of the CB are established on the basis of the Reynolds equation.Experimental data of the engine are also used in simulation analyses to enhance the reliability of the results.The load-bearing capacity(LBC)and friction force of the CB are selected as objective functions.Results show that the LBC has a negligible effect on the tribological properties of the CB,but the friction force greatly affects the resistance of the bearing under different radial clearances and surface roughness values.In particular,the maximum friction force in the asperity contact region accounts for 40.5%of the maximum total friction force at a radial clearance of 5μm and 77.7%of the maximum total friction of the CB with a surface roughness of 10μm.
基金The National Key Research and Development Program of China(No.2019YFB2006402)the Open Fund Project of Hubei Key Laboratory of Intelligent Transportation Technology and Device,Hubei Polytechnic University(No.2021XZ107)the Key Scientific Research Project of Hubei Polytechnic University(No.21xjz02A).
文摘A design of different microtextures on the surface of the crankpin bearing(CB)is proposed to ameliorate the lubrication and friction performance(LFP)of engines.On the basis of the CB s hydrodynamic lubrication model,the bearing surface of CB using different microtextures,such as wedge-shaped textures(WSTs),square textures(STs),circular textures(CTs),and combined square-circular textures(CSCTs),is simulated and assessed under various external loads of the CB at an engine speed of 2000 r/min.The pressure of the oil film,the frictional force,the force of the solid asperity contact,and the friction coefficient of the CB are used as objective functions.Results indicate that the bearing surface designed by the STs remarkably improves the CB s LFP in comparison with other structures of WSTs,CTs,and CSCTs.Particularly,the average values of the frictional force,solid asperity contact,and friction coefficient of the CB using the STs are greatly reduced by 28.5%,14.5%,and 33.2%and by 34.4%,26.3%,and 43.6%in comparison with the optimized CB dimensions and CTs,respectively.Therefore,the application of the STs on the CB surfaces can enhance the LFP of engines.
