高速单点冷滚打成形过程材料变形行为及控形控性机制研究

Aiming at reality of increasing requirements of modern industry and high-tech mechanical and electrical products for precision and performance of some parts such as gear, spline etc., by combination of theoretical analysis, simulation and experimental study, based on the primarily explored forming mechanism and motion parameters controlling, this project will focus on metal deforming & 3D flowing behavior and part shape & performance evolution mechanism during the process of local dynamic loading and integral accumulative forming of the dieless and unconstraint free forming method. The study is to maximize the plastic deforming capacity of material in the forming method, to explore the inherent cause of part's shape difference in different zones and macro & micro defect mechanism, to reveal the transforming conditions and laws of material flowing behaviors of different forming stages and regions in the roll-beating process, to find the coupling relationship of process parameters such as blank shape, material characteristics, geometry shape and dimensions of the roll-beating tool, repeating roll-beating times, roll-beating speed and feeding ratio etc. and part's precision, forming quality, mechanical & physical performance, to obtain the material's uneven deforming features in different deforming regions and characteristic regions and parameter selecting & optimizing matching mechanisms of controlling the part's shape and performance precisely, which will provide theoretical and technological support for the industrial application, part precision & performance controlling and equipment development of the green advanced cold plastic forming technology.

结合现代工业及高端机电产品对齿轮、花键等制件在精度和性能方面的要求越来越高的实际，采用理论分析、模拟仿真和实验相结合的方法，在初步探明的高速单点冷滚打成形机理及运动参数控制的基础上，重点研究这种无模无约束自由成形方法在局部动态加载、整体累积成形过程中金属变形和三维流动行为及制件形态、性态演变机制；挖掘材料在这种成形方法中的塑性变形潜能；探索制件不同部位形状差异及宏微观缺陷产生机理；揭示滚打过程不同阶段不同区域材料流动行为的转化条件和规律；发现毛坯形状、材料特性、滚打工具几何形状与尺寸、重复滚打次数、滚打速度及进给速率等工艺参数与制件精度和成形质量、机械物理性能之间的耦合关系；获得不同冷滚打条件下，不同变形区域及特征区域材料不均匀变形特征；形成制件形态和性态精确控制的参数选择与优化匹配机制，为这项绿色先进冷塑性成形技术的工业应用、制件精度和性能控制以及装备开发提供理论及技术支持。

功能表面高速单点累积成形过程，是通过断续往复运动的成形工具对不断旋转的制件表面高速击打，迫使制件在连续运动中不断受到打击而产生塑性变形，其累积效应最终实现制件成形。项目采用计理论分析、计算机模拟和实验相结合的方法，进行高速单点冷滚打成形全过程建模与仿真、成形过程不均匀塑性变形行为、缺陷形成机理及制件精确控制方法和成形过程参数优化方法研究。通过系统研究，发现了这种无模无约束自由成形方法在局部动态加载、整体累积成形过程中金属变形和三维流动行为及制件形态、性态演变机制，获得了制件纵向弓形及横向隆起的宏观缺陷、成形表面出现起皱、鳞纹的细观缺陷，以及主应力不均匀分布引起的微裂纹等微观缺陷的形成机理，初步探明了滚打过程不同阶段不同区域材料流动行为转化条件和规律，得到了毛坯形状、材料特性、滚打工具几何形状与尺寸、重复滚打次数、滚打速度及进给速率等工艺参数与制件精度和成形质量、机械物理性能之间的耦合关系，获得不同冷滚打条件下，不同变形区域及特征区域材料不均匀变形特征，通过单目标、多目标综合优化，形成了成形过程表面形态和性态控制的参数选择原则与优化匹配机制。项目的研究为发展这种单点无模累积成形技术奠定了理论和应用基础，在设备小功率轻量化、过程高效率节能化、制品高质量精密化的塑性成形中有广阔的应用前景。