刀具磨损过程的质量控制图

Study on Quality Control Chart of Tool Wear Process

刀具磨损是机械加工过程中普遍存在的一种自然现象,机械加工过程中影响加工精度的某些系统性因素随着时间而变化,而且随着系统性因素影响程度的加剧,导致随机性因素也具有了时变性质,即加工过程的方差是随刀具磨损时间的加长而增大的。文章利用递增型异方差的Glejser检验方法,拟作符合刀具磨损规律的加工过程残差模型,计算出刀具磨损过程的控制限,提出了符合刀具磨损特点的加工过程控制图,并运用一个具体案例,说明如何构造文中提出的控制图,结果表明该图可正确地判断刀具在加工过程是否处于受控状态。

Tool wear is a natural phenomenon in the machining processes. Some systemic factors influencing machining precision vary over time. Furthermore, such factors seriously influence the random factors and also cause these random factors vary over time. That is, the variance of machining process increases with the tool wear time lengthening. In this paper, the model of the residuals of the machining process is fitted using Glejser test method which can test the increasing heteroskedasticity of the process. On this basis, the control limits of tool wear process are calculated, then, the control chart of machining process is developed. An example is exerted to show how to construct the control chart developed in this paper. The results show that this chart can correcdy judge whether the tool in machining process is in control.