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Dry! CNC vertical lathe tool wear and breakage detection methods

by:SNK     2020-08-22
Dry! CNC vertical lathe tool wear and breakage detection way release time: 2018 - 06 - 04 clicks: 3020 nc vertical lathe tool wear and breakage of the nc vertical lathe test is suitable for machining medium and small dish, cover parts high strength cast iron base, column, has the good stability and seismic behavior of the vertical structure, the convenient clamping workpiece, cover an area of an area small, adopts oil-water separation structure, make the water clean environmental protection lasting separate cooling water tank, easy to clean. A large formal vertical lathe accuracy of CNC vertical lathe, function; Stepless speed regulation, the main motor frequency conversion transfer speed; Increase the power universal milling head. Cartridge precision high stiffness spindle structure, easy to repair the spindle sleeve symmetry; Suspension design, better to eliminate the influence of thermal deformation of machining accuracy high power ac spindle motor, to enhance the stability of the machine tool spindle adopts imported advanced grease lubrication, fully enclosed, saddle without maintenance. Column guide overweight load is linear rolling guide, good dynamic response performance, high accuracy stable with high quality vertical electric tool post for 6 station, high rigidity and reliable tool change quickly, the centralized machine operation panel, make the operation more convenient; Quick X/Z axis adopts the high precision ball screw and screw bearing, good accuracy stable protection, this product is fully closed environment clean. Single CNC vertical lathe processing, monitoring of tool wear and breakage, with the experience of workers, is still able to normal production, and for FMS, CIMS, no one chemical plant, must solve the online real-time monitoring and control of the tool wear and breakage problem. Because in a timely manner to determine the extent of the cutting tool wear and breakage and on-line real-time control, is to improve the production process automation and guarantee the product quality, avoid damage to one of the key elements of the machine tool, cutting tool, workpiece. Principle of selection of parameters, monitoring tool wear and breakage of measurement method are many, can be divided into two types: direct measurement and indirect measurement method. Direct measurement method includes: optical method, contact resistance, radioactive, etc. Indirect measurement method includes: cutting force or power measurement method, the cutting tool and workpiece measurement, temperature measuring method, vibration analysis, the method of AE, motor current or power measurement method, etc. Comparison of the existing tool wear and breakage monitoring methods, each have advantages and disadvantages, the selection of acoustic emission ( AE) And motor current signal as the monitoring parameter. This is because the AE signal can avoid machining worst affected by the noise in the low frequency area, affected by the vibration and acoustic noise is small, high signal noise ratio (SNR) in the areas of interest, and easy to deal with the signal. Fast response, high sensitivity; But when heavy loading, are susceptible to interference. And motor current signal is easy to extract, can adapt to all of the machining process, and has no effect on normal machining, but are susceptible to interference, slow reaction time and light load, low sensitivity. So, made AE and motor current monitoring signals at the same time, you can use these two monitoring the amount of their respective strengths, complementary, broadening the scope of monitoring, improve the monitoring accuracy and judging the success rate. Cutting process, when the nc vertical lathe tool wear and breakage occurs, corresponding change of cutting force, cutting force changes of motor output torque change, which cause a corresponding change of the motor current, the current method is by monitoring the change of the motor current, indirect online real-time judge the tool wear and breakage. AE is a material or structure from external or internal force deformation or fracture, release the strain energy in the form of elastic wave phenomenon. It has low amplitude, wide frequency range of characteristics. Test and spectrum analysis found that: the normal cutting of the AE signal is mainly plastic deformation of the workpiece material, its power spectrum distribution, below 100 KHZ value is large, more than 100 KHZ is smaller. When the tool wear and breakage, above 100 KHZ frequency components of AE signals are much larger than normal cutting, especially 100 - 300 KHZ frequency components between the larger. Therefore, we should through band-pass filter, monitor - 100 300 KHZ frequency components of AE signal changes, for monitoring tool wear and breakage. Use AE, motor current signal synthesis on tool wear and breakage of the discriminant principle is: light load area, depending on the AE signal envelope, with the threshold method to distinguish; In the load zone when the motor current and AE signal, carried on with the method of the combination of these two discriminant, improve the success rate of the discriminant specific method is: if the AE signal more than AE threshold, the delay time constant for the ds ( D value depends on the system) , if in the ds time, current signal is more than the threshold current signal and tool wear or breakage limit. If in the ds time, current signal does not exceed current signal threshold, do not call the police, by continuing delay constant monitoring. The AE as the guide, AE signal and motor current signal & other And throughout the &; Discriminant model, using the AE signal has the characteristics of real-time, sensitive, and the motor current signal has the nature of the lag, has strong anti-interference ability, improve the success rate of discriminant. In the heavy load, the motor current signal is given priority to, the AE signal is complementary to discrimination. Among all the way to the grid voltage monitoring circuit, through the fluctuation of power monitoring, eliminate because of the influence of the power grid voltage fluctuation on monitoring, improve the anti-interference ability of the system. Automatic minus the first cutting, automatic minus the first cutting line purpose is current with changes in the current measured by determining the amount, improve the sensitivity of current signal monitoring.
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