干切削过程刀具磨损、破损监测与分析

Monitoring and Analysis of the Tool Wear and Break in Dry Machining Process

干切削也叫绿色切削,在加工过程中不加切削液,这样使得刀具的磨损、崩刃等危险性显著增加,为了对其进行监测和分析,建立了一套基于虚拟仪器的信号采集系统,采集铝合金干铣削过程中的温度、声发射和振动信号。对温度信号进行小波变换后,发现刀具磨损后,温度显著增高;对磨损刀具和新刀具干切过程采集的声发射和振动信号进行小波变换+希尔伯特变换后,发现求出的包络谱发生明显变化,新刀具的包络谱比较集中,而磨损刀具的包络谱不仅振幅增大而且比较分散;当刀齿折断时,对采集的温度、振动和声发射信号进行提升小波变换后,发现这3种信号都有一个最大值,这就是折断点,而且在最大值之前都经过了一个明显的突然增大的过程,增加到最大值之后,又急剧减小到零。

Dry machining is also called green machining, with no coolant used, but it will lead to the danger of wear and break of tools. In order to monitor and analyse the dry machining process, the signals in the process of high speed dry milling of aluminum alloy is gathered by a signal gathering system based on Labview environment. The temperature signal is processed by the wavelet transform and the results show that the temperature obviously increases after the wearing of the machining tool. The Acoustic Emission（AE） and vibration signals in the process of dry milling by using a wear tool and a new tool is processed by wavelet transform and Hilbert transform. It shows an obvious change, the envelope spectral（result of Hilbert transform） of using the new tool is relatively centralized, and the envelope spectral of using the wear tool is relatively dispersive and its amplitude is also increasing. When the tool is broken, the obtained signal of temperature, AE and vibration are processed by lifting wavelet transform, and it is found that all these three signals have a highest value, this point can be regarded as the breaking point. Before the vertex, they aU have an obvious process of increasing which lasts less than 0.025 s; after the vertex, all three signals decrease rapidly to zero.