中文摘要：

将影响机加工艺可靠性的主要因素刀具的失效率作为研究对象,将刀具的切削参数作为随机变量,以最大似然估计为基础,结合可靠性分析方法,建立机加工艺系统的动态可靠性数学模型,推导各工序刀具的失效率计算公式。在此基础上,以刀具失效率为判据,建立了如何确定被更换刀具的工序及换刀时间的方法。研究结果表明,当整体工艺流程系统可靠度低于某一阈值时,即可确定更换刀具的时间,再应用刀具失效率模型,就能够迅速找出失效率最大的工序所使用的刀具,并及时更换,从而确保刀具在失效之前满足工艺可靠性要求,最大限度地利用刀具,减少换刀次数,降低成本,从而保障整体工艺系统的高可靠性。

英文摘要：

The failure rate of cutting tools is taken as the research object,which has an effect on the reliability of whole machining process. A mathematical model for the dynamic reliability of machining process is established based on the reliability analysis method and the maximum likelihood estimation,in which the cutting parameters are determined as random variables,and the failure rate formula of each tool is also derived. On this basis,a simple method is presented for determining the tool replacing time and the corresponding job according to their respective failure rate. The research results show that,when the reliability of whole machining process system is below a certain threshold value,the proposed model can be used to define which and when cutting tool must be replaced in time in the certain working procedure,of which the failure rate is the biggest. This allows us to make the most of each tool and reduce the number of tool replacing so as to decrease the cost. Meanwhile,a simple algorithm is proposed to keep high process reliability by ensuring that tools are replaced before their failures.