Based on the mathematical model of a novel cosine gear drive, a few characteristics, such as the contact ratio, the sliding coefficient, and the contact and bending stresses, of this drive are analyzed. A comparison s...Based on the mathematical model of a novel cosine gear drive, a few characteristics, such as the contact ratio, the sliding coefficient, and the contact and bending stresses, of this drive are analyzed. A comparison study of these characteristics with the involute gear drive is also carried out. The influences of design parameters including the number of teeth and the pressure angle on the contact and bending stresses are studied. The following conclusions are achieved： the contact ratio of the cosine gear drive is about 1.2 to 1.3, which is reduced by about 20% in comparison with that of the involute gear drive. The sliding coefficient of the cosine gear drive is smaller than that of the involute gear drive. The contact and bending stresses of the cosine gear drive are lower than those of the involute gear drive. The contact and bending stresses decrease with the growth of the number of teeth and the pressure angle.展开更多
线接触副在工程中广泛存在,且大多工作在弹性流体动压润滑状态下。为研究微凹坑对线接触摩擦副摩擦学性能的影响及表面三维表征参数与摩擦学特性之间的联系,采用激光微造型技术通过控制微凹坑面积占有率、凹坑深度、间距等参数加工制造...线接触副在工程中广泛存在,且大多工作在弹性流体动压润滑状态下。为研究微凹坑对线接触摩擦副摩擦学性能的影响及表面三维表征参数与摩擦学特性之间的联系,采用激光微造型技术通过控制微凹坑面积占有率、凹坑深度、间距等参数加工制造4个表面粗糙度相同,且表面微凹坑面积占有率分别为7%、14%、21%、28%的圆柱形试件;然后使用Talysurf CCI Lite非接触式三维光学轮廓仪对试样进行三维表面测量,且采用ISO25178定义的参数对三维表面形貌进行表征;并在电气化改造后的JPM-1型双盘摩擦磨损试验机上,针对不同滑滚比、不同载荷、不同转速等工况,完成一系列线接触弹流摩擦试验。结果表明,表面形貌的微观结构特性对线接触摩擦副的摩擦特性具有明显的影响,并给出表面体积参数以及特征参数与摩擦的关系;同时,在不同的工况条件及不同的滑滚比下表面结构特性对摩擦的影响效果也不同。展开更多
Silicon carbide(SiC) can be tribo-chemically smoothened during a self-mated sliding procedure in the aqueous environment. As well reported in the point-contact tests, this smoothening process works well due to the abu...Silicon carbide(SiC) can be tribo-chemically smoothened during a self-mated sliding procedure in the aqueous environment. As well reported in the point-contact tests, this smoothening process works well due to the abundant water as oxidant. After this smoothening process, the tribo-surface is well polished, a closely mated tribo-gap naturally forms, and an ultra-low friction state is built. However, water in the tribo-gap could be insufficient in industrial applications, e.g., the seal gap in mechanical seals. In this study, the tribo-chemical smoothening behavior in such environment was researched. A surface-contact reciprocating test was used to simulate the aqueous environment where water was insufficient. After tests, compared to the published results from the point-contact tests, the same ultra-low friction state was achieved. A part of the tribo-surface was tribo-chemically smoothened. The obtained smoothened surface microstructure was consistent with the published information. Meanwhile, severe abrasive wear occurred. A porous oxygen-rich layer was found existing beneath the abrasion-induced grooves, in which numerous smashed wear debris adhered on the worn surfaces. We concluded that the shortage of water initiated the severe abrasion, meanwhile the generated wear debris aggravated the wear condition. This understanding is instructive for developing new methods to avoid the severe abrasion in the same water insufficient environment.展开更多
基金National Natural Science Foundation of China(No.50575071)Natural Science Foundation of Hunan Province,China(No.06JJl0008)+1 种基金S&T Programs of Hunan Province,China(No.2007FJ4047)Program for New Century Excellent Talents in University,China.
文摘Based on the mathematical model of a novel cosine gear drive, a few characteristics, such as the contact ratio, the sliding coefficient, and the contact and bending stresses, of this drive are analyzed. A comparison study of these characteristics with the involute gear drive is also carried out. The influences of design parameters including the number of teeth and the pressure angle on the contact and bending stresses are studied. The following conclusions are achieved： the contact ratio of the cosine gear drive is about 1.2 to 1.3, which is reduced by about 20% in comparison with that of the involute gear drive. The sliding coefficient of the cosine gear drive is smaller than that of the involute gear drive. The contact and bending stresses of the cosine gear drive are lower than those of the involute gear drive. The contact and bending stresses decrease with the growth of the number of teeth and the pressure angle.
文摘线接触副在工程中广泛存在,且大多工作在弹性流体动压润滑状态下。为研究微凹坑对线接触摩擦副摩擦学性能的影响及表面三维表征参数与摩擦学特性之间的联系,采用激光微造型技术通过控制微凹坑面积占有率、凹坑深度、间距等参数加工制造4个表面粗糙度相同,且表面微凹坑面积占有率分别为7%、14%、21%、28%的圆柱形试件;然后使用Talysurf CCI Lite非接触式三维光学轮廓仪对试样进行三维表面测量,且采用ISO25178定义的参数对三维表面形貌进行表征;并在电气化改造后的JPM-1型双盘摩擦磨损试验机上,针对不同滑滚比、不同载荷、不同转速等工况,完成一系列线接触弹流摩擦试验。结果表明,表面形貌的微观结构特性对线接触摩擦副的摩擦特性具有明显的影响,并给出表面体积参数以及特征参数与摩擦的关系;同时,在不同的工况条件及不同的滑滚比下表面结构特性对摩擦的影响效果也不同。
文摘Silicon carbide(SiC) can be tribo-chemically smoothened during a self-mated sliding procedure in the aqueous environment. As well reported in the point-contact tests, this smoothening process works well due to the abundant water as oxidant. After this smoothening process, the tribo-surface is well polished, a closely mated tribo-gap naturally forms, and an ultra-low friction state is built. However, water in the tribo-gap could be insufficient in industrial applications, e.g., the seal gap in mechanical seals. In this study, the tribo-chemical smoothening behavior in such environment was researched. A surface-contact reciprocating test was used to simulate the aqueous environment where water was insufficient. After tests, compared to the published results from the point-contact tests, the same ultra-low friction state was achieved. A part of the tribo-surface was tribo-chemically smoothened. The obtained smoothened surface microstructure was consistent with the published information. Meanwhile, severe abrasive wear occurred. A porous oxygen-rich layer was found existing beneath the abrasion-induced grooves, in which numerous smashed wear debris adhered on the worn surfaces. We concluded that the shortage of water initiated the severe abrasion, meanwhile the generated wear debris aggravated the wear condition. This understanding is instructive for developing new methods to avoid the severe abrasion in the same water insufficient environment.
