For the design of gears manufactured with wire electrical discharge machining （WEDM） technology, determination of the primary gear parameters is discussed considering the characteristics of the machining method. Som...For the design of gears manufactured with wire electrical discharge machining （WEDM） technology, determination of the primary gear parameters is discussed considering the characteristics of the machining method. Some constraint conditions on gear parameters are abnegated, which makes micro gear design more flexible. Based on gear mesh theory, the algorithm of generating gear tooth profiles is studied, which includes involute and non-involute curve segments. The phenomena of tooth profile interferences during gear mesh are analyzed, and a gear mesh simulation algorithm is designed. Based on ACIS, the WEDM oriented software for the design and mesh simulation of micro gears is developed, by which the modeling, mesh simulation and interference check can be implemented. An experiment is carried out to design and manufacture a pair of micro involute gears, and the proposed method is proved feasible.展开更多
Cycloid speed reducers are widely used in many industrial areas due to the advantages of compact size, high reduction ratio and high stiffness. However, currently, there are not many analytical models for the mesh sti...Cycloid speed reducers are widely used in many industrial areas due to the advantages of compact size, high reduction ratio and high stiffness. However, currently, there are not many analytical models for the mesh stiffness calculation, which is a crucial parameter for the high-fidelity gear dynamic model. This is partially due to the difficulty of backlash determination and the complexity of multi-tooth contact deformation during the meshing process. In this paper, a new method to calculate the mesh stiffness is proposed including the effects of tooth profile modification and eccentricity error. The time-varying mesh parameters and load distribution of cycloid-pin gear pair are determined based on the unloaded tooth contact analysis （TCA） and the nonlinear Hertzian contact theory, allowing accurate calculations of the contact stiffness of single tooth pair and the torsional stiffness of multi-tooth pairs. A detailed parametric study is presented to demonstrate the influences of tooth profile modification, applied torque and eccentricity error on the torsional mesh stiffness, loaded transmission error, Hertzian contact stiffness and load sharing factor. This model can be applied to further study the lost motion and dynamic characteristics of cycloid speed reducer and assist the optimization of its precision, vibration and noise levels.展开更多
The counter-meshing gears （CMG） discriminator is a mechanically coded lock, which is used to prevent the occurrence of High Consequence Events. This paper advanced a new kind of self-assembly metal CMG discriminator...The counter-meshing gears （CMG） discriminator is a mechanically coded lock, which is used to prevent the occurrence of High Consequence Events. This paper advanced a new kind of self-assembly metal CMG discriminator based on multi-exposure LiGA like process and sacrificial layer process. The new CMG discriminator has the following characters except low cost： 1） it has only discrimination teeth sections; 2） the thickness of each gear layer exceeds one hundred micrometers; 3） it is axially driven by a separate dectronic magnetic micromotor directly; 4） its CMG is made of metal and is batch fabricated in the assembled state; 5） it is prevented from rotating in the opposite direction by pawl/ratchet wheel mechanism; 6） it has simpler structure. This device has better strength and reliability in abnormal environment compared to the existing surface micro machining （SMM） discriminator.展开更多
A mathematical model has been developed using the space engagement theory and the differential geometry for the line contact of noninvolute beveloid gears with intersecting axes with their tooth profile equations and ...A mathematical model has been developed using the space engagement theory and the differential geometry for the line contact of noninvolute beveloid gears with intersecting axes with their tooth profile equations and engagement equations established for the first time and their meshing theory analysed. It can be seen from the fact that the tooth profile equation finally derived is no longer a standard involute helicoid and standard involute beveloid gears with intersecting axes have no way to satisfy the line contact requirement. However, the noninvdute beveloid gears derived in this paper satisfy the line contact requirement very well. All these work will inevitably facilitate further investigations into gear tooth generation, stiffness, backlash and efficiency of transmission.展开更多
A nonlinear model of anti-backlash gear with time-varying friction and mesh stiffness was proposed for the further study on dynamic characteristics of anti-backlash gear. In order to improve the model precision, appli...A nonlinear model of anti-backlash gear with time-varying friction and mesh stiffness was proposed for the further study on dynamic characteristics of anti-backlash gear. In order to improve the model precision, applied force analysis was completed in detail, and single or double tooth meshing states of two gear pairs at any timing were determined according to the meshing characteristic of anti-backlash gear. The influences of friction and variations of damping ratio on dynamic transmission error were analyzed finally by numerical calculation and the results show that anti-backlash gear can increase the composite mesh stiffness comparing with the mesh stiffness of the normal gear pair. At the pitch points where the frictions change their signs, additional impulsive effects are observed. The width of impulsive in the same value of center frequency is wider than that without friction, and the amplitude is lower. When gear pairs mesh in and out, damping can reduce the vibration and impact.展开更多
A multi-try counter-meshing gears (CMG) discrimination device based on micro electromechani-cal system (MEMS) technology was designed for some specified information fields. The discrimination device consists of two gr...A multi-try counter-meshing gears (CMG) discrimination device based on micro electromechani-cal system (MEMS) technology was designed for some specified information fields. The discrimination device consists of two groups of metal CMG, two pawl/ratchet mechanisms, two driving micromotors and two re-setting micromotors, which make the CMG withdraw by raising the pawls. The energy-coupling element is a photoelectric sensor with a circular plate which is notched. Micromotor is fabricated using the ultraviolet LiGA (UV-LiGA) fabrication process and precision mechanical engineering. The discrimination device has the function which can automatically reset, with the correct resetting code, it can be tried another times.展开更多
基金The Teaching and Research Award Program for Out-standing Young Teachers in Higher Education Institutions of MOE,P.R.China.
文摘For the design of gears manufactured with wire electrical discharge machining （WEDM） technology, determination of the primary gear parameters is discussed considering the characteristics of the machining method. Some constraint conditions on gear parameters are abnegated, which makes micro gear design more flexible. Based on gear mesh theory, the algorithm of generating gear tooth profiles is studied, which includes involute and non-involute curve segments. The phenomena of tooth profile interferences during gear mesh are analyzed, and a gear mesh simulation algorithm is designed. Based on ACIS, the WEDM oriented software for the design and mesh simulation of micro gears is developed, by which the modeling, mesh simulation and interference check can be implemented. An experiment is carried out to design and manufacture a pair of micro involute gears, and the proposed method is proved feasible.
基金Project(51575062)supported by the National Natural Science Foundation of ChinaProject(51605049)supported by the National Natural Science Foundation for Young Scholar of ChinaProject(BA2015177)supported by the Science and Technology Achievements Transformation Program of Jiangsu Province of China
文摘Cycloid speed reducers are widely used in many industrial areas due to the advantages of compact size, high reduction ratio and high stiffness. However, currently, there are not many analytical models for the mesh stiffness calculation, which is a crucial parameter for the high-fidelity gear dynamic model. This is partially due to the difficulty of backlash determination and the complexity of multi-tooth contact deformation during the meshing process. In this paper, a new method to calculate the mesh stiffness is proposed including the effects of tooth profile modification and eccentricity error. The time-varying mesh parameters and load distribution of cycloid-pin gear pair are determined based on the unloaded tooth contact analysis （TCA） and the nonlinear Hertzian contact theory, allowing accurate calculations of the contact stiffness of single tooth pair and the torsional stiffness of multi-tooth pairs. A detailed parametric study is presented to demonstrate the influences of tooth profile modification, applied torque and eccentricity error on the torsional mesh stiffness, loaded transmission error, Hertzian contact stiffness and load sharing factor. This model can be applied to further study the lost motion and dynamic characteristics of cycloid speed reducer and assist the optimization of its precision, vibration and noise levels.
文摘The counter-meshing gears （CMG） discriminator is a mechanically coded lock, which is used to prevent the occurrence of High Consequence Events. This paper advanced a new kind of self-assembly metal CMG discriminator based on multi-exposure LiGA like process and sacrificial layer process. The new CMG discriminator has the following characters except low cost： 1） it has only discrimination teeth sections; 2） the thickness of each gear layer exceeds one hundred micrometers; 3） it is axially driven by a separate dectronic magnetic micromotor directly; 4） its CMG is made of metal and is batch fabricated in the assembled state; 5） it is prevented from rotating in the opposite direction by pawl/ratchet wheel mechanism; 6） it has simpler structure. This device has better strength and reliability in abnormal environment compared to the existing surface micro machining （SMM） discriminator.
文摘A mathematical model has been developed using the space engagement theory and the differential geometry for the line contact of noninvolute beveloid gears with intersecting axes with their tooth profile equations and engagement equations established for the first time and their meshing theory analysed. It can be seen from the fact that the tooth profile equation finally derived is no longer a standard involute helicoid and standard involute beveloid gears with intersecting axes have no way to satisfy the line contact requirement. However, the noninvdute beveloid gears derived in this paper satisfy the line contact requirement very well. All these work will inevitably facilitate further investigations into gear tooth generation, stiffness, backlash and efficiency of transmission.
基金Project(51175505)supported by the National Natural Science Foundation of China
文摘A nonlinear model of anti-backlash gear with time-varying friction and mesh stiffness was proposed for the further study on dynamic characteristics of anti-backlash gear. In order to improve the model precision, applied force analysis was completed in detail, and single or double tooth meshing states of two gear pairs at any timing were determined according to the meshing characteristic of anti-backlash gear. The influences of friction and variations of damping ratio on dynamic transmission error were analyzed finally by numerical calculation and the results show that anti-backlash gear can increase the composite mesh stiffness comparing with the mesh stiffness of the normal gear pair. At the pitch points where the frictions change their signs, additional impulsive effects are observed. The width of impulsive in the same value of center frequency is wider than that without friction, and the amplitude is lower. When gear pairs mesh in and out, damping can reduce the vibration and impact.
基金the National High Technology Re-search and Development Program (863) of China(No. 2003AA404210, 2005AA404250, 2003AA404210,2006AA01Z443)
文摘A multi-try counter-meshing gears (CMG) discrimination device based on micro electromechani-cal system (MEMS) technology was designed for some specified information fields. The discrimination device consists of two groups of metal CMG, two pawl/ratchet mechanisms, two driving micromotors and two re-setting micromotors, which make the CMG withdraw by raising the pawls. The energy-coupling element is a photoelectric sensor with a circular plate which is notched. Micromotor is fabricated using the ultraviolet LiGA (UV-LiGA) fabrication process and precision mechanical engineering. The discrimination device has the function which can automatically reset, with the correct resetting code, it can be tried another times.
