Aiming at determining the thermal contact resistance of ball screws,a new analytical method combining the minimum excess principle with the MB fractal theory is proposed to estimate thermal contact resistance of ball ...Aiming at determining the thermal contact resistance of ball screws,a new analytical method combining the minimum excess principle with the MB fractal theory is proposed to estimate thermal contact resistance of ball screws considering microscopic fractal characteristics of contact surfaces.The minimum excess principle is employed for normal stress analysis.Moreover,the MB fractal theory is adopted for thermal contact resistance.The effectiveness of the proposed method is validated by self-designed experiment.The comparison between theoretical and experimental results demonstrates that thermal contact resistance of ball screws can be obtained by the proposed method.On this basis,effects of fractal parameters on thermal contact resistance of ball screws are discussed.Moreover,effects of the axial load on thermal contact resistance of ball screws are also analyzed.The conclusion can be drawn that the thermal contact resistance decreases along with the fractal dimension D increase and it increases along with the scale parameter G increase,and thermal contact resistance of ball screws is retained almost constant along with axial load increase before the preload of the right nut turns into zero in value.The application of the proposed method is also conducted and validated by the temperature measurement on a self-designed test bed.展开更多
The sliding-rolling mixed motion behavior degrades the ball screw’s precision at different levels.Based on the sliding-rolling mixed motion between ball and screw/nut raceway,the ball screw’s precision loss consider...The sliding-rolling mixed motion behavior degrades the ball screw’s precision at different levels.Based on the sliding-rolling mixed motion between ball and screw/nut raceway,the ball screw’s precision loss considering different given axial loading and rotational speed working conditions was investigated.Since creep and lubrication relate to sliding and rolling motion wear,the creep and lubrication characteristics are analyzed under different working conditions.Besides,the precision loss was calculated considering the sole influence of sliding behavior between ball and screw and compared with the results from other current models.Finally,research on precision loss owing to the sliding-rolling mixed motion behavior was realized under given working conditions,and suitable wear tests were carried out.The analytical results of precision loss are in good agreement with the experimental test conclusions,which is conducive to better predicting the law of precision loss in stable wear period.展开更多
The design of servo controllers for flexible ball screw drives with matched and mismatched disturbances and uncertainties is focused to improve the tracking performance and bandwidth of ball screw drives.A two degrees...The design of servo controllers for flexible ball screw drives with matched and mismatched disturbances and uncertainties is focused to improve the tracking performance and bandwidth of ball screw drives.A two degrees of freedom mass model is established based on the axial vibration characteristics of the transport ball screw,and the controller of an adaptive integral sliding mode is proposed combining the optimal design of state feedback gain matrix K to restrain the vibration and the matched disturbances and uncertainties.Then for the counteraction of the mismatched disturbances and uncertainties,a nonlinear disturbance observer is also developed.The trajectory tracking performance experiments and bandwidth analysis were conducted on experimental setup with the proposed control method.It is proved that the adaptive integral sliding mode controller has a high tracking performance and bandwidth especially for the axial vibration characteristics model of ball screw drives.And the ball screw tracking accuracy also has a considerable improvement with the application of the proposed nonlinear disturbance observer.展开更多
In order to achieve automatic adjustment of the double-nut ball screw preload, a magnetostrictive ball screw preload system is proposed. A new cylindrical giant magnetostrictive actuator （CGMA）, which is the core co...In order to achieve automatic adjustment of the double-nut ball screw preload, a magnetostrictive ball screw preload system is proposed. A new cylindrical giant magnetostrictive actuator （CGMA）, which is the core component of the preload system, is developed using giant magnetostrictive material （GMM） with a hole. The pretightening force of the CGMA is determined by testing. And the magnetic circuit analysis method is introduced to calculate magnetic field intensity of the actuator with a ball screw shaft. To suppress the thermal effects on the magnetostrictive outputs, an oil cooling method which can directly cool the heat source is adopted. A CGMA test platform is established and the static and dynamic output characteristics are respectively studied. The experimental results indicate that the CGMA has good linearity and no double-frequency effect under the bias magnetic field and the output accuracy of the CGMA is significantly improved with cooling measures. Although the output decreased with screw shaft through the actuator, the performance of CGMA meets the design requirements for ball screw preload with output displacement more than 26 μm and force up to 6200 N. The development of a CGMA will provide a new approach for automatic adjustment of double-nut ball screw preload.展开更多
In order to achieve large tolerance capture and high stiffness connection for space payload operations,a Chinese large-scale space end-effector (EER) was developed.Three flexible steel cables were adopted to capture t...In order to achieve large tolerance capture and high stiffness connection for space payload operations,a Chinese large-scale space end-effector (EER) was developed.Three flexible steel cables were adopted to capture the payload with large capture allowance.Ball screw transmission mechanism and plane shape-constraint four bar linkage mechanism were utilized to connect the payload with high stiffness.The experiments show that capture tolerances in X,Y,Z,Pitch,Yaw,Roll directions are 100 mm,100 mm,120 mm,10.5°,10.5°,12°,respectively.The maximum connection stiffness is 4 800 N·m.The end-effector could meet the requirements for space large tolerance capture and high stiffness connection in the future.展开更多
基金Projects(51875008,51505012,51575014)supported by the National Natural Science Foundation of ChinaProject supported by the China Scholarship Council
文摘Aiming at determining the thermal contact resistance of ball screws,a new analytical method combining the minimum excess principle with the MB fractal theory is proposed to estimate thermal contact resistance of ball screws considering microscopic fractal characteristics of contact surfaces.The minimum excess principle is employed for normal stress analysis.Moreover,the MB fractal theory is adopted for thermal contact resistance.The effectiveness of the proposed method is validated by self-designed experiment.The comparison between theoretical and experimental results demonstrates that thermal contact resistance of ball screws can be obtained by the proposed method.On this basis,effects of fractal parameters on thermal contact resistance of ball screws are discussed.Moreover,effects of the axial load on thermal contact resistance of ball screws are also analyzed.The conclusion can be drawn that the thermal contact resistance decreases along with the fractal dimension D increase and it increases along with the scale parameter G increase,and thermal contact resistance of ball screws is retained almost constant along with axial load increase before the preload of the right nut turns into zero in value.The application of the proposed method is also conducted and validated by the temperature measurement on a self-designed test bed.
基金Project(51975012)supported by the National Natural Science Foundation of ChinaProject(Z1511000003150138)supported by the Beijing Nova Program,China+1 种基金Project(Z191100001119010)supported by the Shanghai Sailing Program,ChinaProject(2018ZX04033001-003)supported by the National Science and Technology Major Project,China。
文摘The sliding-rolling mixed motion behavior degrades the ball screw’s precision at different levels.Based on the sliding-rolling mixed motion between ball and screw/nut raceway,the ball screw’s precision loss considering different given axial loading and rotational speed working conditions was investigated.Since creep and lubrication relate to sliding and rolling motion wear,the creep and lubrication characteristics are analyzed under different working conditions.Besides,the precision loss was calculated considering the sole influence of sliding behavior between ball and screw and compared with the results from other current models.Finally,research on precision loss owing to the sliding-rolling mixed motion behavior was realized under given working conditions,and suitable wear tests were carried out.The analytical results of precision loss are in good agreement with the experimental test conclusions,which is conducive to better predicting the law of precision loss in stable wear period.
基金Project(2013ZX04008011)supported by the National Science and Technology Major Projects of ChinaProject(51675100)supported by the National Natural Science Foundation of China
文摘The design of servo controllers for flexible ball screw drives with matched and mismatched disturbances and uncertainties is focused to improve the tracking performance and bandwidth of ball screw drives.A two degrees of freedom mass model is established based on the axial vibration characteristics of the transport ball screw,and the controller of an adaptive integral sliding mode is proposed combining the optimal design of state feedback gain matrix K to restrain the vibration and the matched disturbances and uncertainties.Then for the counteraction of the mismatched disturbances and uncertainties,a nonlinear disturbance observer is also developed.The trajectory tracking performance experiments and bandwidth analysis were conducted on experimental setup with the proposed control method.It is proved that the adaptive integral sliding mode controller has a high tracking performance and bandwidth especially for the axial vibration characteristics model of ball screw drives.And the ball screw tracking accuracy also has a considerable improvement with the application of the proposed nonlinear disturbance observer.
基金Project(51475267) supported by the National Natural Science Foundation of China
文摘In order to achieve automatic adjustment of the double-nut ball screw preload, a magnetostrictive ball screw preload system is proposed. A new cylindrical giant magnetostrictive actuator （CGMA）, which is the core component of the preload system, is developed using giant magnetostrictive material （GMM） with a hole. The pretightening force of the CGMA is determined by testing. And the magnetic circuit analysis method is introduced to calculate magnetic field intensity of the actuator with a ball screw shaft. To suppress the thermal effects on the magnetostrictive outputs, an oil cooling method which can directly cool the heat source is adopted. A CGMA test platform is established and the static and dynamic output characteristics are respectively studied. The experimental results indicate that the CGMA has good linearity and no double-frequency effect under the bias magnetic field and the output accuracy of the CGMA is significantly improved with cooling measures. Although the output decreased with screw shaft through the actuator, the performance of CGMA meets the design requirements for ball screw preload with output displacement more than 26 μm and force up to 6200 N. The development of a CGMA will provide a new approach for automatic adjustment of double-nut ball screw preload.
基金Project(2006AA04Z228) supported by the National High Technology Research and Development Program of China
文摘In order to achieve large tolerance capture and high stiffness connection for space payload operations,a Chinese large-scale space end-effector (EER) was developed.Three flexible steel cables were adopted to capture the payload with large capture allowance.Ball screw transmission mechanism and plane shape-constraint four bar linkage mechanism were utilized to connect the payload with high stiffness.The experiments show that capture tolerances in X,Y,Z,Pitch,Yaw,Roll directions are 100 mm,100 mm,120 mm,10.5°,10.5°,12°,respectively.The maximum connection stiffness is 4 800 N·m.The end-effector could meet the requirements for space large tolerance capture and high stiffness connection in the future.
