The physical datum method that uses the laser beam as the physical datum is proposed.A high accuracy of the straight movement on the line above 0.01 μm/100 mm is achieved through applying the method of the closed lo...The physical datum method that uses the laser beam as the physical datum is proposed.A high accuracy of the straight movement on the line above 0.01 μm/100 mm is achieved through applying the method of the closed loop feedback control that uses the laser beam as the datum.The measuring accuracy above 0.05 μm is obtained by applying the self making electric eddy displacement sensor to detect the geometric accuracy of the optical flat.It proves that the laser beam datum method can achieve the high accurcy of the straight movement and has the huge advantage.展开更多
An account of numerical solutions to the isothermal and flooded elastohydrodynamic lubrication(EHL)of a logarithmic profile roller,which is rolling over a flat plane,is given The analysis takes account of sideways fl...An account of numerical solutions to the isothermal and flooded elastohydrodynamic lubrication(EHL)of a logarithmic profile roller,which is rolling over a flat plane,is given The analysis takes account of sideways flow of lubricant in the inlet region of the contact When the results are presented in suitable non dimensional groups,it is shown that more uniformly pressure and shape of the film distributing in axial direction is taken place under light loading As the increase of the load,the end closure is displayed and the oil pressure rises sharply at the ends The seal action formed by the end closure makes the film thickness a little And the minimum film thickness is transferred from the central to the ends and the value is reduced rapidly As the increase of the speed,the end closure becomes much serious The optimum crowning value obtained in EHL state is larger than the design value obtained in elastostatic contact state for the same working conditions In order to verify the correctness of theory,optical interferometry is applied to measure the oil film thickness between a logarithmic profiled roller and a glass plate under pure rolling conditions It is found the agreement between numerical solutions and experiments is very good.展开更多
Dry wear experiments provide an insight detail on how severely contacting surfaces change under unlubricated sliding condition. The theory of dry sliding wear is used for understanding mixed-lubrication regime in whic...Dry wear experiments provide an insight detail on how severely contacting surfaces change under unlubricated sliding condition. The theory of dry sliding wear is used for understanding mixed-lubrication regime in which asperity interactions play a significant role in controlling of the friction coefficient(f). The purpose of this work is to study the tribological behavior of AISI 304 steel in contact with AISI 52100 steel during wear. Both materials are used in rolling element bearings commanly. Experiments are carried out using a pin-on-disc tribometer under dry friction condition. The areal(three dimensional, 3D) topography parameters are measured using a 3D white light interferometer(WLI) with a 10× objective. After wear tests, wear mechanisms are analyzed utilizing scanning electron microscope(SEM). Factorial design with custom response surface design(C-RSD) is used to study the mutual effect of load and speed on response variables such as f and topography parameters. It is observed that the root mean square roughness(S_(q)) decreases with an increase in sliding time. Within the range of sliding time, S_(q) decreases with an increase in the normal load. Within the range of sliding speed and normal load, it is found that S_(q), mean summit curvature(S_(sc)), and root mean square slope(S_(dq)) are positively correlated with f. Whereas, negative correlation is found between f and correlation length(Sal), mean summit radius(R), and core roughness depth(S_(k)).展开更多
文摘The physical datum method that uses the laser beam as the physical datum is proposed.A high accuracy of the straight movement on the line above 0.01 μm/100 mm is achieved through applying the method of the closed loop feedback control that uses the laser beam as the datum.The measuring accuracy above 0.05 μm is obtained by applying the self making electric eddy displacement sensor to detect the geometric accuracy of the optical flat.It proves that the laser beam datum method can achieve the high accurcy of the straight movement and has the huge advantage.
基金This project is supported by National Natural Science Foundation of China (No.59475037).
文摘An account of numerical solutions to the isothermal and flooded elastohydrodynamic lubrication(EHL)of a logarithmic profile roller,which is rolling over a flat plane,is given The analysis takes account of sideways flow of lubricant in the inlet region of the contact When the results are presented in suitable non dimensional groups,it is shown that more uniformly pressure and shape of the film distributing in axial direction is taken place under light loading As the increase of the load,the end closure is displayed and the oil pressure rises sharply at the ends The seal action formed by the end closure makes the film thickness a little And the minimum film thickness is transferred from the central to the ends and the value is reduced rapidly As the increase of the speed,the end closure becomes much serious The optimum crowning value obtained in EHL state is larger than the design value obtained in elastostatic contact state for the same working conditions In order to verify the correctness of theory,optical interferometry is applied to measure the oil film thickness between a logarithmic profiled roller and a glass plate under pure rolling conditions It is found the agreement between numerical solutions and experiments is very good.
文摘Dry wear experiments provide an insight detail on how severely contacting surfaces change under unlubricated sliding condition. The theory of dry sliding wear is used for understanding mixed-lubrication regime in which asperity interactions play a significant role in controlling of the friction coefficient(f). The purpose of this work is to study the tribological behavior of AISI 304 steel in contact with AISI 52100 steel during wear. Both materials are used in rolling element bearings commanly. Experiments are carried out using a pin-on-disc tribometer under dry friction condition. The areal(three dimensional, 3D) topography parameters are measured using a 3D white light interferometer(WLI) with a 10× objective. After wear tests, wear mechanisms are analyzed utilizing scanning electron microscope(SEM). Factorial design with custom response surface design(C-RSD) is used to study the mutual effect of load and speed on response variables such as f and topography parameters. It is observed that the root mean square roughness(S_(q)) decreases with an increase in sliding time. Within the range of sliding time, S_(q) decreases with an increase in the normal load. Within the range of sliding speed and normal load, it is found that S_(q), mean summit curvature(S_(sc)), and root mean square slope(S_(dq)) are positively correlated with f. Whereas, negative correlation is found between f and correlation length(Sal), mean summit radius(R), and core roughness depth(S_(k)).
