SU1679271A1 - Device for assessing wear of cutting tool - Google Patents

Abstract

The invention relates to metal cutting and can be used to automatically control and correct dimensional wear of cutting tools on CNC machine tools. The purpose of the invention is to improve the accuracy by automatically changing the trigger levels of the threshold elements signaling tool wear. The device contains an accelerometer, an amplifier, high and low frequency filters, two detectors and two threshold elements. With increasing tool wear, the acoustic signal from the accelerometer increases and one of the threshold elements triggers, indicating wear. Then, using a signal from the CNC unit, the threshold is increased and, by the value of this signal, the CNC corrects the position of the tool. With further wear and re-triggering of the threshold elements, the procedure for increasing the threshold and correcting the position is repeated until the critical dimensional wear of the tool is reached. 1 il. cl

Description

The invention relates to the processing of metals by cutting and can be used to automatically control and correct the dimensional wear of the cutting tool on CNC machine tools,

The purpose of the invention is to improve accuracy.

The drawing shows a block diagram of a device for estimating wear of a cutting tool on CNC machines.

The device contains a series-connected accelerometer 1 and amplifier 2, a low-pass filter 3 and a high-pass filter 4, the inputs of which are connected to the output of amplifier 2, the first and second detectors 5, 6, whose inputs are connected respectively to the outputs of the low filter 3 and filter 4

high frequencies, the first and second aoric elements 7, 8, the inputs of which are connected respectively to the outputs of the first and second detectors 5, 6, the first and second digital-to-analog converters (D / A) 9, 10, the output of which is connected respectively to the control inputs of the first and the second DAC, and the analog inputs are designed to input reference signals, the element OR 11, whose inputs are connected to the outputs of the first and second threshold elements 7, 8, the counter 12, the output of which is connected to the digital inputs of the DAC 7, 8, block 13 I / O, intended for interaction with the CNC machine, the digital output of which is connected to the input of the counter 12, the element And 14, the first input and output of which is connected to the block 13 I / o, and VTO

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the swarm input is with the output of the element OR 11. The input-output unit 13 interacts with the computing unit 15 of the CNC of the machine, which is connected to the feed drive control unit 16 and further with the coordinate feed drive block 17,

The device works as follows.

The computational unit 15 of the CNC, with a command to carry out a wear assessment in the control program, using the supply drive control unit 16 and the coordinate feed unit 17, sets the specified modes for controlling dimensional wear, i.e. works the feed in the direction opposite to the work feed and moves the cutter away from the cutting surface by an amount necessary to ensure a reliable absence of contact between the workpiece surface and the back surface of the tool. Then block 15 through block 13 I / o sets the level of logic 1 at the first output of the logic element 14 and reads the signal from its output.

The mechanical vibrations of the instrumental assembly from the accelerometer 1 are converted into an electrical signal which is amplified by amplifier 2 and fed to a low pass filter 3 and a high pass filter 4. The first threshold device 7 compares the signal B0. coming from the output 1 of the detector 5 with the threshold value A0. In the second threshold device 8, the signal W, coming from the output of the second detector 6, is compared with the threshold value AL. When a signal appears at the output of at least one of the threshold devices at the output of the logical element OR 11 and therefore at the second input and output of the logical element 14 is set to a logical level of 1, which indicates that a certain value has been reached by wear.

This signal passes through the I / O unit 13 and is fed to the computing unit 15 of the CNC device. This indicates that the wear of the tool has reached a certain value and correction of the position of the tool nose is necessary. The amount of correction is determined as follows. The computing unit 15 of the CNC through the block 13 I / o sends to the counter 12 pulse. The value of the counter code increases, consequently increases and

the value of the threshold values of A0 and AI. If the triggering of the threshold devices occurs in this case, then the next build-up takes place.

counter 12. The increment of the counter is performed until the triggering of the threshold devices ceases. Then, the computing unit 15 of the CNC device with the help of the drive control unit 16

feeds and block 17 of the drives of coordinate feeds, the tool tip is corrected by one or another value depending on the number of pulses transmitted to the counter 12. Through

for some time, the next cycle of monitoring tool wear. The procedure described is repeated. Correction of the tool tip position will occur until the dimensional wear reaches a critical value, after which a tool change is performed.

The accuracy of the estimate is determined by the size of the counter 12.

Claims (1)

Invention Formula A device for estimating the wear of a cutting tool on CNC machines, containing a series-connected accelerometer and amplifier, a low and filter high-pass filter, whose inputs are connected to the amplifier output, the first and second detectors, whose inputs are connected respectively to the low-filter outputs and a high-pass filter, the first and second threshold elements, the inputs of which are connected respectively to the outputs of the first and second detectors, the element And the I / O unit, designed to interact q machine CNC, the input and output of which are connected to the first input and output of the element And, characterized in that, in order to increase accuracy, it is equipped with an OR element, whose inputs are connected to the outputs of the first and second threshold elements, and the output is connected to the second input of the AND element, the first and second digital-analogue converters, and outputs which are connected respectively with the control inputs of the first and second threshold elements, and the analog inputs for inputting reference signals, and a counter, the input of which is connected to the I / O unit, and the output - with digital inputs of digital-to-analog converters.