弧齿锥齿轮热滚轧成形的金属流线构型及抗疲劳失效机理

Spiral bevel gears are widely used in equipment such as helicopters, automobiles and engineering machinery as the main driving parts, whose fatigue failures would seriously affect the reliability for the whole. The available tooth cutting manufacturing methods for spiral bevel gears have the following problems, low utilization of materials, high energy consumption, and early fatigue failures due to the abscission of metal fiber streamline. For the middle and small module spiral bevel gears made by low carbon alloy steel, this project applies the hot rolling near forming, instead of the cutting forming, to explore a new method for spiral bevel gears fatigue resistance manufacturing. The model of compulsive meshing between the tool gear and the tooth blank being rolled is to be setup, the characteristics for plastic flow of metal materials during the hot rolling forming process is to be studied, and the modes of actions from the mechanical behaviors between the die and contacting surface of gear blank to the qualities of the gears being formed, as well as the influencing rules of forming processing parameters upon the metal streamline configurations with multi-field coupling factors are to be explored. The angle between the direction of the unit max tensile stress of the easily-failed gear teeth and the direction of metal fiber streamline is to be calculated, the inhibiting effects of the inherent qualities on the tooth original fatigue crack initiation and development during the hot rolling forming process are to be investigated, and the mechanisms of fatigue resistance failures for the hot rolling forming process are to be clearly analyzed. The gear fatigue life research experiment of hot rolling near forming is to be conducted to investigate the effects of the fatigue strength improvement by rolling forming. This project will provide theoretical basis for the industrial applications of rolling net/near forming and lightweight design of spiral bevel gears, and its application prospects are explicit.

弧齿锥齿轮广泛应用于直升飞机、汽车、工程机械等装备作为主传动部件，疲劳失效严重影响整机的可靠性。弧齿锥齿轮现有的切齿制造方法材料利用率低、能耗大，金属的纤维流线被切断易产生早期疲劳失效。本项目以低碳合金钢制成的中小模数弧齿锥齿轮为对象，采用热滚轧成形替代切削成形，探索一种弧齿锥齿轮抗疲劳制造的新方法。对工具齿轮与被轧齿坯强制啮合进行建模，研究金属材料在热滚轧成形过程中的塑性流动特性，探索模具与齿坯接触力学行为对轮齿成形质量的作用机制和多场耦合因素下成形工艺参数对金属流线构型的影响规律。计算轮齿易失效单元最大拉应力的方向与金属纤维流线方向的夹角，探究热滚轧成形的内在质量对轮齿原始疲劳裂纹萌生、扩展的抑制作用，明晰热滚轧成形的抗疲劳失效机理。开展热滚轧成形齿轮疲劳寿命试验研究，探究滚轧成形提高疲劳强度的效果。本项目将对弧齿锥齿轮热滚轧成形工业应用和轻量化设计提供基础理论，应用前景明显。

弧齿锥齿轮现有的切齿制造方法材料利用率低、能耗大、金属的纤维流线被切断易产生早期疲劳失效，本项目采用热滚轧近净成形代替热前切削加工，并对其抗疲劳机理进行了研究。建立了热滚轧数值模型，制定了滚轧成形技术方案，构建了弧齿锥齿轮热滚轧成形的动态边界条件，分析了滚轧温度、摩擦系数、模具转速与进给速度对金属流动的作用规律，形成了最佳工艺组合的技术方案。.构建了模具轮与被轧轮坯之间的啮合力学模型，分析了小轮齿数对滚轧力的作用关系，探索了不同进给深度对应的应力-应变场分布特征，基于节点追踪技术分析了轮齿各点的变化规律，构建了齿面及齿顶法向力与摩擦力的耦合关系，明晰了齿面摩擦力对成形缺陷的作用机制。.搭建了弧齿锥齿轮滚轧试验台并完成了滚轧试验验证，分析了热滚轧成形后轮齿的内部组织形态与金属流线的三维形貌特征，完成了传统切削加工和热滚轧成形齿轮的疲劳寿命对比试验，并对材料利用率及加工效率进行了跟踪计算。结果表明，滚轧成形的弧齿锥齿轮疲劳寿命提高了48.65%，材料利用率提高了15.74%，制齿效率提高了50%，为弧齿锥齿轮的轻量化设计提供了新的技术支撑。