飞秒激光加工液体火箭发动机喷注部件无锥度微孔试验研究

Experimental Study on Femtosecond Laser Processing Non-taper Micro-holes in Injection Components of Liquid Rocket Engines

为了提高液体火箭发动机喷注部件微孔加工质量,完全消除孔壁锥度,提出了倾斜工件改变激光与孔壁入射角的旋转钻孔方法,设计搭建了工件空间调控的装置平台,研究了激光倾斜角度和激光入射方位对微孔尺寸与结构形貌的影响,探究了倾斜加工直孔孔型的演变过程,并针对离心式喷嘴切向孔开发出一套完整的定孔径、定锥度倾斜工件旋转钻孔的工艺。结果表明,进行激光倾斜加工时需要保证激光光轴和工件旋转轴共面,否则会产生孔形曲线误差;通过调整工件倾斜角度可控制钻孔锥度,调整激光焦点相对工件表面旋转中心的距离可控制钻孔半径。该方法实现了孔深4.5 mm,深径比10∶1的大深径比无锥度微孔加工,加工质量较好,孔口和孔壁无明显热影响区和重铸层,可满足液体火箭发动机离心式喷嘴切向孔的可控高质量加工要求。

In order to improve the micro-hole processing quality of liquid rocket engine injection components and completely eliminate the taper of hole wall,a rotary drilling method for inclined workpiece with changing the incident angle of laser and hole wall is proposed.The device platform for workpiece space regulation is designed and built.The influence of inclination angle and laser incidence orientation on the size and structure morphology of micro-holes is studied,and the evolution of inclined processing micro-holes is explored.A complete set of rotary drlling technology for inclined workpiece with fixed hole diameter and fixed taper is developed for centrifugal nozzle tangential holes.The results show that it is necessary to ensure that the laser optical axis and the workpiece rotation axis are coplanar during inclined processing,otherwise the hole curve error will be generated;the drilling taper can be controlled by adjusting the inclination angle of the workpiece,and the drilling radius can be controlled by adjusting the distance between the laser focus and the rotation center of the workpiece surface.The method realizes the non-taper deep holes processing with the depth of 4.5 mm and aspect ratios of 10:1.The micro-holes have good quality and no heat affected zone or recast layer on the surfaces and wall.The requirements of controllable high-quality processing of the tangential hole of the centrifugal nozzle of the liquid rocket engine may be satisfied.