RU2024006C1 - Method of wear inspection of cutting tool - Google Patents

Abstract

FIELD: instrumentation engineering. SUBSTANCE: cutting zone is probed with acoustic signals. Their frequency is set within 10⁶-10⁷ Hz. Amplitudes of these signals under working and decreased feed of tool are measured and wear of tool is estimated by relation of these amplitudes. EFFECT: increased authenticity of wear inspection of tool. 2 dwg

Description

 The invention relates to the processing of metals by cutting and can be used to determine tool wear on the rear surface during cutting.

 A known method for determining the wear resistance of a cutting tool when machining a workpiece on a machine [1], which consists in the fact that for the reference tool, a correlation between the wear period and the increment of the acoustic emission signal obtained at idle and during cutting is determined.

 The tool under study is cut, the increment of the acoustic emission signal is similarly determined, and the wear resistance value of the tool under study is determined from the obtained correlation dependence.

 However, this method has the following disadvantages. The measurement of the amplitude of the acoustic emission signal is carried out at a changing temperature, which during the measurement process does not provide optimality, since the measurement is carried out under simultaneously changing and interacting technological modes (speed, feed, cutting depth).

 The closest technical solution, selected as a prototype, is the method implemented in the device for monitoring the state of the cutting tool [2], which consists in the fact that during machining as a result of the interaction of the part and the tool creates an acoustic emission signal, which is measured. At the same time, the coolant consumption is determined. The amplitude of the acoustic signal is estimated, the signal is remembered and taken as exemplary. In the process, the current signal is compared with the exemplary one. Based on the results, an assessment is made of the degree of wear of the tool and, based on the evaluation, a signal is allocated to the CNC system of the machine to change, if necessary, the parameters of the machining process.

The disadvantage of this method is the low reliability of the control, since the signals are uninformative and highly susceptible to interference, in particular, the sound frequency range (16-2-10 ⁴ ) Hz is recorded by a microphone.

The purpose of the invention is to increase the reliability of control of wear of the cutting tool. This is achieved by probing the cutting zone with signals with a frequency of (10 ⁶ -10 ⁷ ) Hz, when the tool feeds by changing the cutting speed, the temperature in the cutting zone is kept almost constant, the tool feed is periodically reduced to a fixed one, while the amplitude of the indicated signals is also measured and the ratio of the amplitudes of these signals at working and reduced tool feeds determines its wear.

 In FIG. 1 shows a diagram of a device for a specific implementation of this method; in FIG. 2 - dependence of the average value of the chamfer of wear on the rear surface of the tool on the ratio of the amplitudes of the reflected signals at reduced and working feeds.

 The proposed method is implemented as follows.

 A device for implementing this method comprises an instrument assembly 1 with a piezoelectric transducer mounted in a cutting tool, an ultrasonic meter 2, a control computer 3, an actuator 4 of the main drive, an actuator 5 of the feed drive, a temperature sensor 6, a workpiece 7 and a cartridge 8.

In the process of cutting with a piezoelectric transducer 1, the cutting zone is probed with an acoustic signal with a frequency of (10 ⁶ -10 ⁷ ) Hz and the amplitude of the reflected signal A _{r is} recorded with an ultrasonic meter, the converted signal from which is fed to the control computer 3.

 During the machining process, the cutting speeds through the actuator 4 are changed so that the temperature in the cutting zone, measured by the sensor 6, is kept constant. In this case, the signal from the sensor 6 is also transmitted to the control computer 3, where it is continuously compared and converted into a speed control signal.

At a certain point in time, the actuator 5 produces a short-term reduction in the feed of the cutter, at which sounding and registration of the amplitude of the reflected signal A _{y are} also performed.

The ratio A _y / A _r using a computer is compared with a similar value in the correlation dependence obtained by processing the reference pair of part-tool.

The magnitude of the ratio A _y / A _p is judged on the value of the chamfer wear.

The proposed method is based on the fact that the processes of removal of allowance, chip formation and the machined surface, as well as the formation of wear surfaces are accompanied by the emission of acoustic emission pulses in the frequency range 10 ³ -10 ⁹ Hz, and the pulses due to wear and destruction of the cutting tool are most clearly manifested in frequency range 10 ⁶ -10 ⁷ Hz.

PRI me R. Spend the batch of 100 pcs. workpieces made of steel 45 material with a T15K6 carbide cutter. The cutting speed is varied within 100-150 m / min, so that at the contact surface temperature was ^about 450-500 C and maintained constant. In the process of cutting, the cutting zone was probed with the acoustic signal of the TsTS-19 piezoelectric transducer with a resonant frequency of 2.5 MHz and the amplitudes of the reflected signals A _{r were} recorded. The temperature measurement data was converted into a speed control signal using a 16K20T1 CNC machine, a microcircuit of Electronics NTs-31.

Periodically, on each blank, a short-term decrease in supply was made, at which sounding and recording of the amplitudes of the reflected signals A _y , which were received by the computer and were compared with the correlation dependence A _y / A _p = f (h ₃ ) of the standard, were also carried out. The scattering field of values of h ₃ depending on A _y / A _{p is} limited by curves 1 and 3, and the average values of wear during processing of a batch of parts are shown by curve 2. The maximum dispersion of wear h ₃ according to the criterion of the ratio of amplitudes A _y / A _{p of} acoustic emission indicated in the field of cutting modes, amounted to 40-50%. Using as the criterion of wear h _{3 the} ratio of the values of electrical resistivity R _y / R _p when processing under the same conditions gives a dispersion of 3-4 times more.

Claims (1)

METHOD FOR WEARING THE CUTTING TOOL WEAR, which consists in receiving acoustic signals from the cutting zone, evaluating their amplitudes and using them determine the degree of tool wear, characterized in that, in order to increase the reliability of control, the cutting zone is probed with signals with a frequency of 10 ⁶ - 10 ⁷ Hz, when the tool feeds by changing the cutting speed, the temperature in the cutting zone is kept almost constant, the tool feed is periodically reduced to a fixed value, while the amplitude of the nnyh signals and relative amplitudes of these signals at the working and feed rate reduction tool determine its wear.

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