Interference signals such as vibration and noise transmitted from the main shaft are mainly transmitted through the sensor housing. The special adaptive filter used in this system can filter various interference signals from the housing and retain the transmission from the fluid medium. The resulting tool broke the AE signal. The adaptively filtered signal enters the high-pass filter (cutoff frequency 100 kHz), and the high-pass filtered AE signal has a certain attenuation. After being amplified again, it enters the detector, and the detected AE signal enters the comparator for waveform discrimination. First, the amplitude of the envelope of the AE signal is compared. When it reaches the preset amplitude threshold, the comparator 1 triggers the flipping, starts to output the signal, and then enters the pulse width comparison, that is, the signal enters the integrator to start integration, and the integral The device works according to the following calculations: Where Uo(t) is the output of the integrator; K is the constant determined by the circuit parameters; Ui(t) is the input of the integrator, ie the output of comparator 1; Uo(0) is the output of the integrator at the beginning of the integration time , adjusted by circuit parameter to 0. 2, the structure of the tool damage monitoring system The structure of the monitor is shown in Figure 4. It consists of a sensing cavity and an electronic circuit cavity. The sensing chamber receives signals from the sensing elements. The electronic circuit cavity includes a power module, a pre-processing module, a post-processing module, and a control module. In addition to the above-mentioned acoustic emission monitoring process, they can also give the machine control signal to stop the machine after the alarm. At the same time, the user is prompted by the sound and light alarm, and the relay alarm output interface is given for the user to select. The sensing cavity, the electronic circuit cavity and the circuit boards in the electronic circuit cavity are all modularized, and the plug-in connection is adopted between them to facilitate maintenance and replacement. Due to the industrial electromagnetic noise, the monitor's working environment is relatively harsh, and the monitor is designed to resist interference. At the same time, according to the electromagnetic compatibility design principle, a grounding and housing shielding structure is adopted. Electromagnetic and power interference experiments, such as the start and stop of electric drills and machine tools, proved that a series of measures were effective. Figure 4 Schematic diagram of the monitor structure 3 experiment The drill bit damage test was carried out on the CA6140 common lathe. The cooling lubricant system on the machine was directly used. The monitor was connected in series to the root of the cooling lubricant flexible pipe. The cooling lubricant was 20# oil. High-speed steel twist drills with different diameters (0.5 to 2.1 mm) and different cutting parameters (cutting speed: 400~1400r/min, feed: 0. 028~0.036mm/r) drilling 45# Steel and hard aluminum were tested 56 times with a success rate of 98%. The high-speed steel twist drill bit damage test was carried out on the RE3020 machining center. The working material was 45# steel, and the cooling lubricating fluid was 20# engine oil. The experimental results are shown in the table below. During the experiment, the artificial sensing of the sensor housing and the machining center spindle, as well as the machining center start-stop, shifting, etc. did not cause false alarms, which proved that the instrument has strong anti-interference ability. Previous page Disk Magnet,Msg Manufacturer China,Rare Earth Magnet Fenghua Jade Motor Co., Ltd. , http://www.motor-magnet.com
The flip signal of comparator 1 accumulates for a certain time. When the output of the integrator is higher than the preset pulse width threshold, comparator 2 triggers the flip (when the integrator output is below the pulse width threshold, it is considered to be the impact interference). The alarm circuit is triggered by the output signal of the comparator 2, and the machine stop signal is given. Such a monitoring and processing method is completely realized by a hardware circuit in real time, and is a good practical method for monitoring tool breakage. 
Tool diameter / mm Experimental data Spindle speed /
(r . mim -1 ) Feed rate/
(mm . min -1 ) Number of experiments Number of successes 0.5 2000 40 15 15 0.8 2000 40 20 20 1.0 2000 40 10 10 1.5 1000 40 5 5 2.0 600 40 2 2
This intelligent monitor is mainly used for online real-time automatic monitoring of tool breakage, and can also be applied to other metal and non-metal dynamic crack monitoring.