基于微型双螺杆的各向异性装药技术原理和关键工艺参数

Principles and key process parameters of anisotropic propellant loading based on micro⁃twin⁃screw systems

各向异性装药是固体火箭发动机能量精细化管理和性能跨越式提升的重要途径。利用增材制造“离散-堆积”的工艺优势,确立了基于微型D6 mm双螺杆的“在线计量-原位混合-连续挤出-增材制造”各向异性复合推进剂增材制造系统原理。在挤出成型过程中,将复合推进剂的材料要素准确映射到药柱的几何空间,为各向异性装药提供一种新的思路。面向挤出成型增材制造工艺需求,室温快速固化双组分聚脲被用于复合推进剂黏合剂,实现了外径120 mm、内径57 mm、高240 mm代料药柱的增材制造成型,固体质量含量72%。进一步定义和实验确立了D6 mm双螺杆系统的关键工艺参数——计量精度、混合均匀度(CV)和组分切换时间(t_(s))。结果表明:粉体、黏合剂的计量体积分别为0.036、0.610 cm^(3)/转,并与螺杆的转速呈良好的线性关系;“粉体-树脂”混合物取样体积为1.0 ml时,变异系数CV值为1.1%,t_(s)低至8 s。

Anisotropic propellant loading of solid rocket motors is an important direction for realizing refined energy manage⁃ment and performance breakthrough.Taking“discrete⁃stacking”advantages,additive manufacturing(AM)system of“online mete⁃ring⁃in⁃situ mixing⁃continuous extrusion⁃additive manufacturing”using D6 mm micro⁃twin⁃screw,were established for anisotropic propellant loading.In the extrusion AM process,accurately mapping the propellant materials information to the grain geometric space,provides a new approach for anisotropic loading.Rapid curing two⁃component polyurea were employed as binder to satisfy the rheological requirement of extrusion AM.Substitute grain with an outer diameter of 120 mm,an inner diameter of 57 mm and a height of 240 mm was prepared,with a solid mass content of 72%.Definitions and experimental methods for critical technical parameters of the AM prototype were investigated,including metering accuracy,mixing uniformity(coefficient of variation,CV),and component switching time(t_(s)).The result_(s)show that the metering volume of the AM prototype is linearly related to the screw rotating speed,ex⁃trusion volumes per revolution for powder and binder are 0.036 cm3 and 0.610 cm^(3),respectively.CV=1.1%t_(s)is as low as 8 s,when sampling volume“powder⁃resin”mixture is 1.0 ml.