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美国商业部国家标准局最近研制成功了一种价廉的监视装置。它能用来有效地探测异常钻削,并能预报在自动加工过程中小钻头可能发生的故障。该装置用一价格低廉的小型微处理机来分析从过载传感器送来的信号(过载传感器靠磁力吸附在工件表面上)。当钻头进入工件、钻入孔和退出工件时,监视装置将来自传感器的正常幅值记录下来,同时监测超过正常幅值400%的峰值信号。发现峰值信号后,监视装置继续探测此峰值信号在一定的时间周期内是否会以钻头转速为周期连续出现四次,若连续出现四次,监视装置就向机床控制系统发出信号,中断钻削过程。由于该装置要求在一定的时间间隔内过载信号峰值必须出现四次再进行故障预报,这样就减少了因对工件的随机冲击而发出“假信号”的次数。
The National Bureau of Commerce of the United States Department of Commerce recently developed a cheap surveillance device. It can be used to effectively detect anomalous drilling and to predict possible failures of small bits during automatic machining. The device uses a small, inexpensive microprocessor to analyze the signals sent from the overload sensor, which is magnetically attracted to the workpiece surface. As the drill bit enters the workpiece, drills in the hole and exits the workpiece, the monitoring device records the normal amplitude from the sensor while monitoring for peak signals that exceed 400% of the normal amplitude. After the peak signal is found, the monitoring device continues to detect whether the peak signal appears four times in succession within a certain period of time at the bit rotation speed. If four consecutive times occur, the monitoring device sends a signal to the machine control system to interrupt the drilling process . Since the device requires that the overload signal peaks occur four times in a certain time interval and then the fault is predicted, the number of “false signals” issued due to the random impact on the workpiece is reduced.