枪械固定式刚性抛壳机构动作故障机理

聚焦枪械固定式刚性抛壳机构动作故障机制及其数学建模，利用失效模式和影响分析方法分析机构故障模式和影响因素，得到两大主控因素为抛壳速度和抛壳挺抛壳窗相对位置。构建了固定式刚性抛壳机构的数学模型，获得固定式刚性抛壳机构性能参数，并结合故障模式给出故障判据。以某小口径自动步枪的结构参数为例，针对主控因素进行故障边界分析，并进行试验验证。理论计算和试验结果表明：抛壳可靠性随着抛壳速度的增大而提高；抛壳窗位置变化存在显著的双向边界效应，主要表现为抛壳窗对于弹壳的“欠（过）约束”效应和弹壳与抛壳窗撞击点位置变化；弹壳向内回弹和弹壳二次撞击是造成卡壳故障发生的直接原因。

Failure Mechanism of the Fixed Rigid Ejection Mechanism in Firearms

Thisstudy employs the failure mode and effect analysis (FMEA) method to study the failure mechanism and mathematical modelling of fixed rigid ejection mechanism, and to obtain failure modes and influencing factors. The two main controlling factors are the ejecting speed and the relative position of the ejector and ejection opening. Adynamics model is developed and the performance parameters are obtained. The failure criteria are acquired based on failure modes. The failure boundary analysis and experimental verification of the main factors are carried out using the structural parameters of a small-caliber automatic rifle as an example. Both theoretical calculations and experimental results indicate that higher ejecting speed leads to higher reliability. Besides, a significant bidirectional boundary effect is found in ejection opening displacement,demonstrated as the under-constrained(over-constrained) effect of the ejection opening on the cartridge case and changing position of the impact point. The direct causes of case jamming failure are the inward rebound of the cartridge case and secondary impacts.