热-力在多筋薄壁镁合金型材温热张力绕弯中的协调作用机制

Magnesium alloy bent profiles with multi-rib and thin-walled used in the aerospace, automotive and other fields can lose weight, reduce fuel consumption and pollution emissions. However, these profiles that manufactured by traditional bending process are prone to producing springback, wrinkling and distortion. The warm tension-rotation bending process is presented. The profiles are heated and applied tension, post-stretching and lateral pressure to improve the bendability and forming accuracy by heat-force condition. Coordination mechanisms of heat-force condition on magnesium alloy profile in warm tension-rotation bending are investigated by using theoretical analysis, numerical simulation and experimental methods. The mechanical state and stress-strain of magnesium alloy profiles in bending process by heat-force condition are researched. The mechanism of the heat-force condition on reducing springback, eliminating wrinkling and distortion is clarified. The mechanism of the heat-force condition on improving the bendability and forming accuracy is determined. The mathematical relationships between process parameters and geometric dimensions and springback are established. The effect of the heat-force condition on microstructure and texture is investigated. The plastic deformation mechanism of the bending of magnesium alloy bent profile is revealed. This project aims to reveal the coordination mechanism of heat-force condition on magnesium alloy profile in warm tension-rotation bending, which provides the theoretical basis for the effective control of the quality and accuracy of magnesium alloy parts in bending process and feasible technologies for manufacturing of magnesium alloy profiles.

多筋薄壁镁合金弯曲型材应用于航空航天、汽车等领域可以减重、降低油耗和污染排放量，传统弯曲方法成形该结构件易产生回弹量大、起皱、扭曲等缺陷。本项目采用温热张力绕弯成形工艺，拟通过加热型材、施加张力、补拉力和侧压力使型材在热力作用下提高其弯曲性能和成形精度，采用理论分析、数值模拟和实验方法研究热力在镁合金型材温热张力绕弯中的协调作用机制，分析弯曲成形中热力作用时镁合金型材力学状态、应力应变演变等力学问题，阐明热力作用对减小型材回弹、消除起皱和扭曲的作用机制，明确热力作用对提高型材弯曲性能和成形精度的作用机制，建立热力工艺参数与型材几何尺寸以及回弹量的数学关系，阐明热力作用对型材微观组织和织构的影响规律，揭示镁合金型材弯曲成形的塑性变形机理。本项目旨在揭示热力在镁合金型材温热张力绕弯中的协调作用机制，为有效控制镁合金弯曲成形的质量和精度提供理论基础，并为镁合金型材的成形制造提供可行的技术方法。

多筋薄壁镁合金弯曲型材应用于航空航天、汽车等领域可以减重、降低油耗和污染排放量，传统弯曲方法成形该结构件易产生回弹量大、起皱、扭曲等缺陷。本项目主要以AZ31镁合金型材为研究对象，利用温热张力绕弯工艺成形镁合金型材，采用理论分析、数值模拟和实验方法研究镁合金型材温热张力绕弯成形行为，重点研究分析了AZ31镁合金型材组织及性能、模拟分析了AZ31镁合金型材温热张力绕弯成形、设计了张力绕弯成形试验机并开展了弯曲试验。研究结果表明热力作用提高型材弯曲成形质量并显著降低型材回弹，获得了工艺参数对型材回弹和几何尺寸的影响规律，明确了影响型材回弹和几何尺寸变化程度因素依次为预拉量（张力）、弯曲角、弯曲速度和温度。在现有模拟和实验研究条件下，认为温度170-220℃、预拉量3-6%是较优的弯曲工艺参数。本项目研究结果有望为有效控制镁合金弯曲成形的质量和精度提供理论基础，并为镁合金型材的成形制造提供可行的技术方法。