硬质合金刀具的动态可靠性及失效率研究

分析了硬质合金刀具在断续切削加工时的主要失效形式,考虑了冲击载荷作用次数对刀具可靠性的影响,运用应力-强度干涉模型及随机过程理论,建立了硬质合金刀具的动态可靠性数学模型,给出了刀具在断续切削加工时的可靠度的变化规律.同时建立了以载荷冲击次数及加工时间为度量指标的刀具失效率计算模型.研究表明,随着载荷冲击次数和加工时间的增加,刀具的可靠度曲线出现逐渐降低的变化过程.刀具失效率具有"浴盆"曲线的特征,且与实验结果相吻合.通过该曲线可以准确地划分刀具的早期失效期、偶然失效期和耗损失效期,为刀具选取试验和修复时间以及可靠寿命等指标提供了理论依据.

Research on Dynamic Reliability and Failure Rate of Cemented Carbide Cutting Tool

Based on the main failure mode of cemented carbide cutting tool and the influence of impact loading times on cutting tool reliability， a mathematical model on dynamic reliability of cemented carbide cutting tool was built by using the theory of stress-strength interference model and stochastic process， and the change rule of reliability was also obtained. On this basis， with impact loading times and machining time as the metrics respectively， the failure rate models were established. The results show that cutting tool reliability decreases gradually with the increase of impact loading times and machining time， and cutting tool failure rate characteristics of “bathtub” curve. According to this curve， the earlier， random and wear-out failure period of cutting tool can be divided accurately， that provides a theoretical basis for tool selection test， repair time and reliability life.