圆柱齿轮高效精密轴向滚轧成形原理与关键技术研究

Compared to gear cutting processes, such as hobbing, shaping, etc., for large quantity batch production of spur and helical gears, the gear rolling process has many positive aspects in high productivity, saving material, high fatigue properties. Currently, the radial-feeding gear rolling process is difficult to keep the stability and precision the generating motion because feeding movement is coupled with generating motion between workpiece and the tools. Also, the material is trend to flow in the axil direction that will make some defects on the gear teeth. To solve the bottleneck problems, we propose a new gear rolling process by axil feeding with forced synchronization of workpiece. However, the material deformation is complex in the axial-pushed gear rolling process and the forming mechanism has not been revealed. The precision of the gear rolling process is still unsatisfied the requirement of the industry. This research proposal is based on the previous research, and continues to study on the forming mechanism, process, tool design, precision control, etc. The material flow, pressure distributions on the teeth of forming tools and its evolution are revealed based on the concept of slice-method. Then, the rolling force / torque calculation model can be derived by integration along axil direction, the boundary of forming process are clarified. To explore the effects of material flow and stress distribution on the teeth, a beveloid gear with chamfers is proposed as the rolling tools as well as design method. The gear deviations are mapped to multi-level factors to study the root causes. The impacted factors are systematically studied and error compensations methods are proposed. The theoretical models are optimized by conducting gear roll forming experiments to achieve the goal of precision control. Two software packages are developed for process and tool design, respectively. Finally, the proposed gear rolling process can successfully form the spur and helical gears with module of 2.5mm and precision of IT 7-8, and capable to replace the cutting methods. This research will lay a solid foundation for the industrialization of the precision roll forming process.

滚轧成形相对于滚（插）齿等圆柱齿轮批量生产工艺具有高效、节约材料、抗疲劳等优点，目前采用的径向滚轧成形轧轮与工件之间展成运动保持困难，材料宽展引起工件两端齿形不饱满。为此，申请者提出圆柱齿轮轴向滚轧新技术，由于材料流动剧烈且规律复杂，成形机理尚未清楚，加工精度未达到工业应用要求。项目在前期研究基础上，开展成形机理、工艺模型、轧轮设计、精度控制与实验研究，掌握成形基本原理，探明滚轧过程材料流动规律与轧轮载荷分布，建立基于轴向积分原理滚轧力能参数模型，探明工艺限制条件；揭示轧轮形状对材料流动性的影响规律，提出变齿厚轧轮设计理论与方法；揭示成形齿轮偏差的多层次影响关系，提出机床误差控制要求，建立轧轮轮齿修形方法；通过大量实验修正上述理论研究，掌握齿轮轴向滚轧成形基础理论与精度控制关键技术；加工齿轮模数2.5mm，综合精度IT7-8级，实现以轧代滚（插），为该技术工业应用奠定坚实的理论基础。

滚轧成形是利用轧轮与工件作展成运动，逐渐迫使工件部分材料流动产生轮齿，具有加工效率高、材料耗费少、表面质量和使用性能好等优点的一种先进制造技术。本项目提出直齿圆柱齿轮轴向冷轧成形的新工艺，并对该工艺的成形机理、机床研制、轧轮设计方法、成形缺陷与精度进行了研究，为直齿圆柱齿轮高效成形提供理论依据与方法支撑。具体研究内容如下：.1. 本研究基于自由分度式滚轧法的工件初始直径、轧轮齿初始相位以及重合度变化规律，建立了被轧工件成形节距误差的预测模型；以节距误差为评价指标，从理论角度分别探讨了它们对轧件分齿精度的影响；最后，利用有限元分析和实验验证前述理论分析。.2. 分析齿轮强制分度过程中关键部位材料流速、轨迹。通过切片法进行了金属流动的实验验证，毛坯被切成薄片，并将网格图案丝网印刷于毛坯上以用于跟踪材料流动的轨迹。.3. 在考虑工件轧后有效齿顶圆达到标准尺寸的基础上，构建强制分齿式滚轧工件轮齿长高系数模型，该模型将齿顶缺陷以及端面凸起对轮齿长高的影响考虑进来。利用有限元软件分析相关参数对工件齿顶圆的影响，并利用滚轧实验对所建立模型的有效性进行验证，实现了齿顶缺陷的有效控制。.4. 根据齿轮轴向滚轧成形特征，将轧轮结构分为切入段、精整段和退出段三部分；从轧轮齿的受力、齿根应力、滑移率及齿面划痕等角度，建立了轧轮切入段锥角、精整段齿全高、精整段以及退出段修正系数求解模型；设计制造多套轧轮，进行滚轧实验验证。.5. 本研究对第一代滚轧机床进行数控化改造，并授权杭州新剑机器人股份有限公司，研发制造了第二代全数控滚轧机床，可用轴向/径向滚轧，最大滚轧力为60吨。机床具备零件轴主动分度和轴向主动进给，实时监测出输出滚轧力/力矩/位置等。同时在传动链精度上有了较大的提升，机床精度大大提升，并进行了批量化生产。该技术同时应用于汽车水平座椅调节器的精密丝杆、RV滚柱丝杠等产品的批量化生产，取得了显著的经济效益。.综上，本研究已完成直齿圆柱齿轮冷轧成形工艺机理研究，并进入滚轧批量生产阶段。