矩形波导管冷拉拔表面微观形貌模拟及粗糙度预测数学模型

To meet the requirement of super-smooth inner surface of the aluminum rectangular tube in the cold drawing process, the research is carried out for exploring the significant factors and the mechanism in influencing the final product's surface roughness. The surface roughness is measured from Al6061-T4 material for five strain histories and the effect of microstructure and mechanical property on the surface roughness is found out. The FEM model for the tube drawing process is established, including the surface micro-topography evolution. Based on the crystal plastic theory, the relationship of surface roughness, variables in the drawing process, material mechanical property and the microstructure is presented. In this FEM model, the lubrication layer is also discreted. The contact mechanism in the deformation zone and the frictional factor distribution is studied. The mathematical model is proposed to describe the evolution of the surface roughness in wave-guide tube cold drawing process using the Mathematical regression method. The practical drawing experiments are also conducted to verify and correct the proposed mathematical model. This model comprises the computational system including the material characterization, microstructure, process variables, die variables and lubrication effect, which will be crucial for the surface roughness prediction in the cold drawing process.

针对铝合金矩形波导管冷拉拔成形需获得超光滑的内表面这一要求，探求塑性成形过程中影响工件表面粗糙度的诸因素及其作用机制。以波导管所采用的Al6061-T4材料为对象，用实验方法分析其在五种不同的应变路径下，多晶体材料的微观结构和机械性能对表面粗糙度变化的影响。建立冷拉拔波导管包含表面微观形貌演化的FEM模型，采用晶体塑性理论求解，从而获得波导管表面粗糙度、拉拔成形参数、管材机械性能和微观结构之间的相互关系。在包含表面微观形貌演化的FEM模型中，将工具和工件之间的润滑层做离散化处理，研究塑性变形区工具与工件间的接触机理和摩擦因子场分布。采用数学回归的方法建立波导管冷拉拔工艺过程中表面粗糙度演化数学模型。对应进行拉拔实验，以验证和修正该表面粗糙度数学模型。该数学模型所搭建的是包含材料属性、微观组织结构、工艺设计、模具设计和润滑状况在内的计算分析体系，将实现冷拉拔塑性变形过程中表面粗糙度的可靠预测

针对铝合金矩形波导管冷拉拔成形需获得超光滑的内表面这一要求，探求了塑性成形过程中影响工件表面粗糙度的诸因素及其作用机制。首先，从宏观上分析了多道次拉拔变形中材料的流动规律，实现了波导管的形状精度和尺寸精度控制。在此基础上，建立了宏-细观耦合的多道次拉拔有限元分析模型，得到了成品管的内表面粗糙度的演变规律。对应进行了拉拔实验，验证了宏-细观耦合模型的有效性。建立了包含表面微观形貌的多晶体有限元分析模型，计算了单向拉伸过程中的表面粗糙度、拉伸变形量以及材料微观结构参数之间的相互关系，获得了单向拉伸过程中表面粗糙度演化数学模型。

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