涂层刀具高速铣削淬硬钢的声发射信号特征

AE Signal Characteristics of High-speed Milling Hardened Steels with Coated Tools

通过测量不同涂层铣刀高速铣削不同硬度淬硬钢材料时的声发射信号和切屑形态,得到了电压时间声发射信号以及声发射信号RMS值与切削工艺参数之间的关系。研究结果表明:声发射信号与淬硬钢材料硬度、刀具涂层类型及工艺参数有关;声发射信号可用来评价淬硬钢材料硬度的变化,随着淬硬钢材料硬度的增大,采集的声发射信号电压值呈逐渐增大的趋势;TiAlN涂层产生的锯齿形切屑的剪切带长度最小,切屑易于折断,从而导致其产生过程中的声发射RMS值偏小;随着切削速度和每齿进给量的增大,TiSiN、TiAlN、AlCrN和CrSiN四种涂层铣刀的声发射信号均快速增大,而随着轴向和径向铣削深度的增大,4种涂层铣刀的声发射信号变化不明显;在同一种切削参数条件下,可根据淬硬钢切屑变形特征的变化来间接评价刀具涂层的切削性能;声发射信号波形图的峰值大小可较好地反映锯齿形切屑的生成状态,进而可用来监控淬硬钢加工过程切削稳定性。

By measuring the AE signals and chip morphologies of different coated tool high-speed milling hardened steels with different hardness values, the voltage-time AE signals and the relationships between RMS values of AE signals and cutting parameters were obtained. The research results show that the AE signals are related to the hardness of the hardened steels, the tool coating types and the cutting parameter values. The AE signals may be used to evaluate the hardness changes of hardened steels, with the increasing of the hardness of hardened steels, the voltage values of AE signals increase gradually. The shear band lengths of sawtooth chips produced by the TiAlN coating are the shortest, the chips are easy to break so that the RMS values of AE are small during the cutting processes. With the increasing of cutting speeds and feed rates, the AE signals of TiSiN, TiAlN, AlCrN and CrSiN coated tools increase rapidly. However, as the axial and radial cutting depths increase, the AE signals of four coated tools do not change significantly. Under the same cutting parameter conditions, the cutting performances of the coated tools may be evaluated indirectly based on the chip deformation characteristic changes of the hardened steels. According to the peak values of AE signal oscillogram, the generating states of sawtooth chips may be well reflected, and then may be used to monitor the cutting stability of hardened steels during the working processes.