行星滚柱丝杠的径向锻造与三辊滚轧复合塑性变形行为的研究

Comparing with the ball screw (BS), static and dynamic load increases more than three times, and service life extends more than ten times, and rotational speed increases two times for the planetary roller screw (PRS). Thus, PRS is suitably used in the working conditions of high-speed, heavy-load and long-life in the forging and stamping equipments. At the present, the production of PRS is dominated by metal-cutting process, and this process is characterized by long processing time, large material loss, and poor fatigue resistance. Thus, a novel radial-forging and rolling compound forming process of planetary roller screw is proposed in this project. The mechanical models of compound forming process of radial forging and three-die rolling will be established, and initial effected laws of main processing parameters on force parameters and deformed area in the compound forming process will be obtained by analytic analysis. A multiscale FE model is developed for radial-forging and rolling compound forming process, and numerical simulations will be carried out. The metal deformation behavior, microstructure evolution and its acting mechanism in multi-motion coordinating coupled multi-pass loading bulk forming process of screw will be studied. The influence laws of material parameters, geometric parameters and processing parameters on the multi-pass local loading process with multi-field coupling multi-parameter will be revealed. According to the results of the analytic and numerical analyses, the experimental equipment of radial-forging and rolling compound forming process will be developed, and then the relevant experiments are carried out. The optimization and control method of high-efficiency plastic forming with less-load for large-diameter heavy planetary roller screw is developed.

行星滚柱丝杠比传统的滚珠丝杠承载力大三倍以上、寿命延长十倍以上、工作转速高两倍，因此特别适用于塑性加工设备中的高速、重载、高寿命场合。现有的行星滚珠丝杠切削加工方式生产效率低、材料利用率低、抗疲劳性能差，为此本项目提出了径向锻造与三辊滚轧复合塑性变形新工艺方法。建立径向锻造与滚轧复合塑性成形工艺过程中的力学模型，解析分析初步获得复合成形过程的主要工艺参数及其对力能参数和变形区范围的影响规律；开展径向锻造与三辊滚轧复合塑性成形过程中多尺度建模并进行计算机仿真，研究多种运动协调的局部加载行星滚柱丝杠体积成形材料变形流变行为、组织形态演化及其作用机制；揭示多场多参数耦合下多道次局部加载材料参数、几何参数、工艺参数等对行星滚柱丝杠塑性变形行为的影响规律；依据理论分析与数值模拟结果，研制径向锻造与滚轧复合的试验装置并开展相应的试验研究工作，发展大直径重载行星滚柱丝杠高效省力塑性成形过程优化控制方法。

行星滚柱丝杠(PRS)是一种新型的适用于高速、重载、高精度场合的滚动功能部件，但其大直径丝杠以切削加工为主，效率低、浪费材料，对初始材料性能要求高、加工难度大。采用锻轧复合温冷成形可有效改进材料初始组织、提高零件机械性能性能、减少成形周期。本项目对丝杠、蜗杆等典型大直径、大齿高螺纹类零件径向锻造、滚轧及其复合的温冷成形工艺进行了系统研究，主要研究内容和重要结果如下：确定常用材料温成形温度区间和温、冷成形材料参数，基于试验和有限元相结合的方法建立了冷滚轧成形过程中硬度应变关联模型；基于等温、非等温圆环压缩试验评估确定了温径向锻成形过程摩擦条件，发展了反映轴类零件冷滚轧润滑特点和螺纹滚轧中连续接触变形运动特征的增量圆环压缩试验和单齿滚轧试验评估确定了冷滚轧过程摩擦条件；基于温冷复合成形模拟试验，研究了温冷复合成形下的温成形温度、温冷成形压缩量分配等下微观组织特征，以及冷成形下零件表面纹理和组织形态；建立径向锻造锤头和工件之间运动同几何参数之间的关系，以避免径向锻造过程折叠、减少径向锻后齿形偏差为目标，优化设计了径向锻造模具结构，建立了加热-径向锻造-冷却-滚轧全过程热力耦合有限元模型，应力、应变、温度等场变量数据全过程无缝衔接；研究了行星滚柱丝杠温成形区间内径向锻造过程热力行为，通过合理的模具设计和工艺过程控制，可以径向锻造成形出具有良好齿型的丝杠等零件；系统研究了螺纹类零件主动旋转轴向进给滚轧变形特征，设计制造滚轧模具，开展了直径80mm丝杠铝合金坯料试轧和中碳钢材料滚轧，获得良好齿型的滚轧零件；深入研究了锻轧复合温冷成形工艺变形特征，径向锻造形齿形良好，无乱齿折叠缺陷，正反往复滚轧对螺纹牙型有一定的校正和精整作用。研究结果为大直径重载丝杠等螺纹类零件的塑性成形制造奠定了良好的理论基础，提供了技术原型。