钛合金板材振动辅助成形机理及关键技术研究

According to the forming accuracy and usability requirement of titanium alloy sheet metal in the development of aviation, aiming at the problems such as limited formability at room temperature and large residual stress in the forming process of titanium alloy sheet metal, based on material vibration effect, this project conducts research on vibration assisted forming process of titanium alloy sheet metal. In order to attain the purpose of improving the forming accuracy and usability of titanium alloy sheet metal, vibration effect is utilized to improve its plastic deformation ability and to release the residual stress. Theoretical analysis and numerical simulation as well as experiment are adopted to ascertain the influence rules of vibration effect on the mechanical properties of titanium alloy sheet metal and the elimination of residual stress, by which appropriate vibration frequency, vibration amplitude and vibration time at every deformation stage are obtained. On that basis, studies on formability in a series of processes such as vibration assisted bending, vibration assisted bulging and vibration assisted drawing are carried out. The deformation rules of titanium alloy sheet metal under vibration effect, as well as its limit deformation are obtained. Vibration assisted forming mechanism are revealed, and both technological process and quality control specification about the vibration assisted forming and elimination of residual stress of titanium alloy sheet metal are built.

本项目根据航空制造业发展对钛合金板材零件成形准确度及使用性能的要求，针对钛合金板材室温变形能力差、残余应力大等问题，基于材料振动效应，进行钛合金板材振动辅助成形工艺研究。成形过程中利用材料振动效应提高钛合金板材塑性变形能力，同时消除由于钛合金板材变形而产生残余应力，达到提高钛合金板材零件制造准确度和使用性能的目的。研究过程采用理论分析、数值模拟和实验相结合方法，确定振动效应对钛合金板材力学性能和残余应力消除的影响规律，得到钛合金板材塑性变形及残余应力消除过程所需振动频率、振动幅度和作用时间；在此基础上，进行钛合金板材振动辅助弯曲、胀形、拉深等工艺的成形性能研究，得到振动效应与钛合金板材耦合变形规律和成形极限，揭示钛合金板材振动辅助成形机理，建立复杂形状钛合金板材振动辅助成形、残余应力消除为一体的工艺流动和质量控制规范。

本项目针对钛合金塑性变形能力差，成形零件残余应力大而导致回弹量较大、形状稳定性差等问题，进行了钛合金板材振动辅助成形的研究。根据振动辅助成形原理，结合不同的成形工艺，设计出了振动辅助成形装置通过理论分析、实验和有限元结果的分析，得到了振动工艺材料参数对材料性能、成形工艺以及残余应力和回弹的影响规律；同时从振动效应对提高钛合金板材塑性变形能力、减小残余应力与回弹、减小成形过程中的界面摩擦系数以及提高成形工艺性能等方面进行了点阐述，得到了振动辅助成形机理及关键技术参数。研究结果表明，钛合金板材成形过程施加振动后，一方面可以减小了摩擦对板材成形性能的影响，另一方面可以提高了钛合金自身的塑形变形能力，同时成形过程中的应力叠加效应，从而使钛合金板材成形过程成形性能得到了提高，同时由于残余应力的降低也使其形状稳定性得到了改善，因此成形过程需要综合考虑振动效应对成形过程中的摩擦、材料性能及残余应力的影响，以获取最佳成形工艺参数。