准双曲面齿轮小轮热滚轧成形机理及轮齿近净成形控制策略

The fatigue resistance of hypoid pinions made by face milling or face hobbing is weak, and mismatch with hypoid gears made by precision forging processing characterized by gear teeth are near net shaped, so the combination of hypoid pinions and gears made by the method mentioned above, affects the improvement of overall mechanical preformance. Aiming at the issue, this research focuses on hypoid pinions used in automobile drive axle, and the technical solution of near net shaped hypoid pinions by hot roll forming technology is proposed. Based on the theories of gear meshing and upper bound analysis, the rolling motion model and forming force calculating model of hot roll forming were established. By the theory of elastic-plastic and thermal-mechanical coupled FEM, the inner stress-strain and temperature field distribution of the blank during the process of hot roll forming were analyzed, and the metal flowing law was forecasted, and the factor resources responsible for the shaped teeth defects were predicted, and the influence rules of processing parameters on forming quality of the shaped teeth were found. By combining robust design method with objective function optimization design method, the best combination of processing parameters was confirmed. Through the studies on the elastic deflection of tool gear, elastic recovery and thermal expansion deflection of gear blank, the tool gear tooth modification strategy was proposed. By virtue of numerical simulation and experiments, the control of near net shaped tooth quality is managed effectively. For the hot roll forming of hypoid pinion, this research can provide technical support and theoretical basis.

针对传统铣齿加工准双曲面齿轮小轮抗疲劳强度低，无法与采用精密锻造近净成形技术加工的大轮相匹配，从而影响齿轮副整体机械性能提高的问题，本项目以汽车驱动桥准双曲面齿轮小轮为研究对象，提出采用热滚轧技术近净成形小轮的方案。基于齿轮啮合理论和上限法理论，建立小轮热滚轧成形的运动模型和成形力计算模型；借助热力耦合弹塑性有限元理论和数值模拟，分析热滚轧过程中轮坯内部应力应变及温度场分布，探明金属材料的流动规律，预测轮齿缺陷产生的因素来源，寻求工艺参数对轮齿成形质量的影响规律；结合稳健性设计方法和目标函数值拟合算法，确定最佳的工艺参数组合；通过对热滚轧过程中工具齿轮的弹性变形、齿坯卸载后的弹性回复以及齿坯热胀冷缩变形的研究，建立工具齿轮齿面修正的补偿策略；借助数值模拟和试验相结合的手段，实现对轮齿近净成形质量的有效控制。项目研究成果为准双曲面齿轮小轮热滚轧近净成形制造提供理论依据和技术支撑。

通过对准双曲面齿轮啮合理论、热滚轧成形机理以及轮齿近净成形精度控制策略的深入研究，探索出了一条准双曲面齿轮塑性成形加工的新途径，为准双曲面齿轮小轮绿色制造的实现提供了技术支撑。基于齿面接触分析（TCA）技术和齿轮共轭啮合理论，获得了准双曲面齿轮小轮的理论齿面方程，结合齿面旋转投影原理，对工作齿面进行5x9网格划分，构建了滚轧工具轮的三维模型。通过对准双曲面齿轮副的虚拟啮合实现了接触区的动态仿真，结果验证了构建齿轮副三维模型理论的有效性。基于小轮滚轧成形的数学模型，在工具轮与工件轮坯的两种联动模式下，深入研究了滚轧成形的工艺参数对轮齿成形的影响规律，分析了各种成形缺陷的特征规律，结果显示：工具轮转速选择范围为50-70r/min，工具轮的进给速度控制范围为0.6-0.8mm/r，滚轧温度的范围为950-1000℃。基于有限元正反向模拟理论，着重研究了工具轮齿面在滚轧力作用下产生的弹性变形规律、轮坯卸载后的弹性回复规律以及冷却收缩变形规律，通过预控变形逆向调整策略对工具轮进行了齿面误差修正，结果显示：修正后的工具轮轮齿凹面螺旋角减小，凸面螺旋角增大，两齿面的压力角减小。基于最优的试验方案在自制的滚轧试验台上进行试验，结果验证了准双曲面齿轮小轮滚轧成形技术方案和仿真结果的有效性，为新方法的工业应用提供理论依据。