【作者】 邱昕洋；

【导师】 秦大同； 张光辉；

【作者基本信息】 重庆大学 ， 机械设计及理论， 2010， 博士

【摘要】 精密蜗轮副作为精密分度或精密运动机构,主要用于齿轮加工机床、具有精密分度功能的加工中心、精密转台及仪器仪表等场合。研究一种精密动力型蜗杆传动,使之能够满足更高的输入转速、更大的输出转矩、更小的齿侧间隙、更好的刚性及更长的精度寿命等要求,具有重要的现实意义。钢制变齿厚平面蜗轮包络环面蜗杆传动能够满足对“精度”和“动力”有双重要求的场合,如何合理地设计、制造并确保其摩擦学性能是能否成功实现该传动的关键。论文围绕钢制平面蜗轮传动的关键技术,系统地进行啮合原理推导、参数分析、齿面接触分析、精密加工、润滑分析、材料配伍试验及加工试制等方面的研究。应用微分几何及共轭曲面原理给出平面蜗轮传动啮合原理;考察母平面倾角、压力角、模数等参数对接触线分布、蜗杆根切及蜗轮齿厚的影响,为合理设计蜗轮副提供了参考。在啮合分析及加工、装配工艺过程分析基础上,建立包含误差的齿面模型及装配模型;利用齿面间隙法对平面蜗轮传动进行齿面接触分析;考察各个误差对传动副齿面接触状态的影响,根据影响程度的不同提出误差干预的一般建议,为误差控制及合理修缘、修形提供指导。在阐述平面包络环面蜗杆形成原理基础上,运用刚体平面运动知识论证虚拟回转中心原理;通过实例验证了该原理的可行性。应用虚拟回转中心原理加工环面蜗杆,能够实现用小中心距的机床加工大中心距环面蜗杆的目的;应用该原理设计的机床,通用性强,适合于各种蜗杆类零件的加工。探讨平面蜗轮的制齿方法:通过加工方法分析及工艺试验,对比研究用于平面蜗轮齿面加工的铣削、插削、飞削、滚削、磨削加工法。着重考察连续分度飞削加工法,运用活动标架建立飞削加工的数学模型;并进行误差分析、优化设计、模拟仿真及工艺试验等研究。给出各种加工方法的优缺点及适用场合。在弹性流体动压润滑理论和钢制平面蜗轮传动啮合特点研究基础上,提出该传动的弹性流体动压润滑模型。通过计算整个接触区内的最小弹流膜厚,揭示最小膜厚的分布规律;分析速度、载荷、母平面倾角、压力角及蜗杆分度圆直径对该传动润滑性能的影响。结果表明:蜗杆啮入端的润滑状况优于啮出端,蜗杆齿顶的润滑状况优于齿根;改善平面蜗轮传动润滑性能较为有效的方法是优化压力角和增大蜗杆分度圆直径。改善润滑性能的同时,要综合考虑上述变量对传动效率和摩擦磨损等的影响。在分析钢制平面蜗轮传动摩擦学系统特性基础上,建立钢-钢线接触滑动摩擦模型,通过试样试验模拟传动副上任意接触点处的摩擦学系统。考察诸多因素对摩擦系统性能的影响,结果表明:极压剂的含量高、活性强的车辆齿轮油最适合于钢-钢滑动摩擦副;滑动摩擦高副宜选用粘度较高的润滑油;稳定工况下,摩擦系数随诱导法曲率半径的增大而减小;摩擦系数随润滑角的增加而减小;膜厚较薄时,表面光洁度的影响尤其重要;氮化层能有效地避免过度磨损;推荐的材料处理工艺为氮化-氮化或氮化-渗碳淬火;氮化层较深为宜;两偶件的表面硬度高、硬度差较小时,耐磨性能较好。以前述研究内容为指导,设计变齿厚平面蜗轮副;采用两种材料组合分别制造两套蜗轮副,验证了前述研究的结果,为开发该传动奠定基础。本文研究得到了国家自然科学基金的资助(50075089).更多还原

【Abstract】 The precision worm gears, which is used as a precision indexing or a fine motion mechanism, mainly uses in gear cutting machine, accuracy machine tool with indexing function, precision rotary table or instruments, and so on. Researching on the precision-power worm drives which can satisfy the higher input speed, the greater output torque, the smaller teeth clearance, the better rigidity, the longer accuracy life, etc, has the vital practical significance. The steel variational-tooth-thickness planar wormgear enveloping hourglass worm drive can satisfy the dual requirements of“precision”and“power”. How to design, manufacture and guarantee its tribology performances are the key technologies to achieve this transmission successfully. This dissertation investigates the key technologies such as meshing theory, parametric analysis, tooth contact analysis, precision machining, elastohydrodynamic lubrication (EHD) analysis, material combinations test, trial manufacture, and so on.The mesh theory of the planar worm gears is presented based on the differential geometry and the conjugate curved-surface principle. Influences of main parameters such as slope angle of generitix, pressure angle, axial module, etc. on distribution of contact lines, undercut of worm, and tooth thickness of wormgear, are studied on considering the characteristics of the new transmission. On the basis of engagement analysis together with technology analysis of machining and assembling, tooth surfaces models and assembly model containning errors are established. The tooth contact analysis of the driven are carried on by using the teeth-surface-clearance method. Effects of errors on teeth contact state are studied. General suggestions are proposed to minimizing the disadvantage effects of errors, and modifying the profile of the worm.Based on explaining the generating theory of planar enveloping hourglass worm, the principle of dummy gyration center is demonstrated by the knowledge of plane kinematics of rigid body. Machining test is carried out and the feasibility of the new principle is identified further. The results show that the dummy gyration center can be used in machining the hourglass worm completely, and the numeric control machine tool with the function of the dummy gyration center has versatile characteristic to processing all kinds of worm components.Through the processing method analysis and processing test, the cutting methods of planar wormgear such as milling, slotting, fly-cutting, grinding, and hobbing are discussed. The fly cutting method is studied further and the mathematical model of fly cutting is established by the method of moving coordinate. Error analysis, optimization design, analog simulation and technique test are carried out. The suitable situation, merits and faults of the cutting methods are presented.Based on study of EHD and mesh theory of the steel planar worm gears, EHD model for the drive is proposed. Minimum film thickness on the whole contact area is calculated. The distributions of film thickness are analyzed. Influences of velocity, load, slope angle of generitix, pressure angle and reference diameter of worm on lubrication performance are investigated. The results show that, the EHD status during entry engagement is better than that during exit engagement, and EHD state of worm addendum area is better than that of dedendum area. Optimizing pressure angle and increasing worm reference diameter have effect on improving lubrication performance. The influences of the variable on the transmission efficiency, frictional wear should be considered too during improving lubricantion.Based on study of tribology performances of the drive, the steel-steel line-contact sliding-friction model is established to simulate the tribology system of arbitrary contact point. Influencing factors along with their effects are analyzed. The results show that, extreme pressure gear oil containing more additive is suitable for steel-steel sliding friction pair, lubrication oil with high viscosity is beneficial to sliding friction higher pair, the larger relative curvature radius of sliding pair leads to lower friction coefficient in smooth conditions, the larger lubrication angle has higher advantageous to minimizing friction factor, the roughness of surfaces is vital in thin oil film conditions, nitration case can avoid excessive wear effectively, the recommended techniques of heat treatment are nitrogen treatment vs nitrogen treatment and nitrogen treatment vs carbonization, the friction pair which have high surface hardness and low difference of hardness has excellent wear resisting property.Steel variational-tooth-thickness planar worm gears is designed on considering the mentioned above findings. Two pairs of worm gears are trial manufactured using two material combinations.The dissertation is supported by National Natural Science Foundation(50075089).更多还原