基于逆向挤出的七孔发射药口模设计  

Die Design of Seven-perforated Gun Propellant Based on Inverse Extrusion

作　　者：刘欢欢 张江波 侯龙 麻明阳 马中亮 LIU Huan-huan;ZHANG Jiang-bo;HOU Long;MA Ming-yang;MA Zhong-liang(School of Environment and Safety Engineering,North University of China,Taiyuan 030051,China)

机构地区：[1]中北大学环境与安全工程学院,山西太原030051

出　　处：《火炸药学报》2023年第12期1107-1116,共10页Chinese Journal of Explosives & Propellants

摘　　要：为了探究七孔发射药挤出后偏孔的原因和寻求一种改善发射药的挤出偏孔的解决思路,通过模拟研究发射药挤出时在模具内的流动性掌握偏孔规律使其朝着理想的方向偏孔;根据几何模型建立发射药的内流道模型,以Bird-carreau law模型进行模拟分析,通过正向挤出模拟对挤出形状和尺寸进行了数值预测;然后对挤出过程进行逆向数值模拟设计了口模形状,重点分析了挤出过程的流场分布与压力分布,用设计后的口模模拟正向挤出,从理论上验证了逆向设计口模的可行性。结果表明,相较于压力和剪切速率,流速分布不均是导致发射药挤出偏孔的关键因素之一;发射药在模具挤出时,根据模具入口处截面的速度分布可以看到药料入口处的流速分布是不同的,靠近壁面处流速低,模针与模针之间流速高,最大流速约为最小流速的1.5倍;离开模具后大部分区域流速变小,其中流速快的部分因为流速降低导致面积增加,流速慢的区域因为流速增大导致面积减小,速度的重新分配引起自由表面的挤出变形;逆向挤出模拟可以对发射药的挤出偏孔提供补偿作用,并对逆向设计的口模形状进行了挤出验证,其挤出物的孔形与之前相比更为规整。因此通过逆向挤出设计口模形状有望提高发射药挤出的良品率。In order to explore the causes of perforation deviation after the extrusion of seven-perforated gun propellant,and seek a solution to improve the perforation deviation problem,the control method of perforation deviation towards the ideal direction was studied based on the fluidity of the propellant in the mold during extrusion.The internal flow channel model was established on the basis of the geometric model of propellant grain,and the Bird-carreau law model was used for simulation analysis,including the numerical prediction of the shape and size of the extruded grains.Then,the extrusion process was inversely simulated,the shape of die was designed,and the flow field distribution and pressure distribution of the extrusion process were analyzed.The designed die was used to simulate the extrusion,and the feasibility of inverse design of die was verified theoretically.The results show that the uneven flow velocity,not the pressure or shear rate,is one of the key factors associated with the perforation deviation phenomenon.According to the velocity distribution of the cross-section at the inlet of the mold during the extrusion process,it can be seen that the inlet flow velocity distribution is different.It reveals that the flow velocity near the wall is low,while the flow velocity between the needles is about 1.5 times higher.After leaving the die,the flow velocity in most areas decreases.The sectional area of the fast flow region increases due to the decrease of the flow velocity,on the contrary,the area of the slow flow region decreases due to the increase of the flow velocity.The results reveal the redistribution of the velocity causes the deformation of the free surface of extruded propellant.The inverse extrusion simulation can compensate for the perforation deviation in the propellant.The extrusion verification test of the inverse design of the die shape is carried out,and the perforation shape of the extrudate is more regular than before.Therefore,it is expected that the yield of propellant can be improved by

关 键 词：流体力学 POLYFLOW 流变模型 逆向挤出 七孔发射药 口模设计 

分 类 号：TJ55[兵器科学与技术—军事化学与烟火技术] TQ562[化学工程—炸药化工]