复杂外形航空发动机TC4钛合金宽弦空心风扇叶片弯扭成形

Twist-bend forming of aeroengine titanium TC4 wide-chord hollow fan blade with complex geometries

弯扭成形是钛合金空心风扇叶片制造中一种有效的辅助成形手段,赋予空心叶片毛坯理想的过渡形状,改善工艺性。针对应用于大涵道比涡扇发动机的TC4钛合金宽弦空心风扇叶片的工艺试验件,研究适用于复杂外形叶片的单轴扭转与双轴扭转两种弯扭方法,提出了夹头运动参数的设计方法,分析了机构的运动规律以及成形原理。基于有限元模拟,研究了扭转方式以及弯扭路径等关键工艺参数对于制件外形、变形区分布、扭转力矩以及表面缺陷的影响,并进行了弯扭实验。结果表明,采用单轴扭转方式,弯扭温度为750℃,叶尖夹头扭角为20.4°,扭转速度为0.68(°)/min,能够将平板毛坯成形出合理的过渡形状。弯扭后面板上出现了失稳凹陷,与有限元结果一致。

Twist-bend forming is considered as an effective auxiliary forming means for titanium wide-chord hollow fan blades. It is used to form the hollow blank to the preferred in-process shape, which improves the manufacturability. For the process test sample of certain type of TO4 titanium wide-chord hollow fan blades used in high bypass ratio turbofan engines, a single-axis and a double-axis twist-bend forming approaches are proposed. The design method for the motion parameters is developed based on the analysis of forming principle and clamps movement rules. Numerical method is used to investigate the effects of different twist-bend manners and load paths on the result, such as obtained geometries, deformation distribution, required torque and skin deflections. The forming experiment is conducted. The results show that the single-axis manner can obtain satisfactory result using the following process parameters： 750℃ for forming temperature, 20.4° for twist angle of top clamp and 0.68 （°）/min for twisting velocity. Grooves do appear on the blade skin as the FE analysis predicts.