19孔发射药挤出过程的数值模拟与模具优化

高黏度药料挤出成型19孔发射药过程会出现模针断裂和无法成型的现象。本研究采用有限元方法,模拟了药料的流动情况。分析了模具压缩比、成型段长度和针架结构对流道内压力场、速度场的影响,获得合理的模具结构。优化后模具压缩比为4.25,成型段长度为26.0mm,并优化针架结构,增加轴向流动的药料。结果显示,优化后流道内最大压力减小40.45%,模针所受最大径向合力减小37.45%,流道内最大径向分速度减小66.98%。优化后模具挤出的19孔发射药组成均匀,表面光滑,内孔分布良好。定容燃烧结果表明,该19孔发射药燃烧稳定,并具有优良的渐增性。

Numerical Simulation of Extrusion Process and Die Optimization for 19-Hole Propellant

Pin broken appears in process of extrusion of 19-hole propellant and products are hard to be shaped when the viscosity of flow is high. This study simulated the forming process of propellant by the finite element method to solve this problem. On the basis of simulation results, effects of the compression ratio, the length of forming section and structure of pin holder on the distribution of stress and velocity of propellant flow were analyzed. The compression ratio of the optimized die is 4.25, the forming length is 26.0 mm, and the pin holder is optimized to increase the axial flow propellant. The results show that, after optimization, the maximum pressure in the flow channel reduces by 40.45%, the radial force on the outermost die pins reduces by 37.45%, the maximum radial velocity of the fluid in compression section decreases by 66.98%. The components distribute evenly, the propellant surfaces are smooth and the holes are in good distribution in propellants which are extruded by the new die. The constant volume combustion experiment confirms that the 19-hole propellants burn stability and the progressive combustion is excellent.