SU1281377A1 - Monitoring arrangement for n/c machine tool - Google Patents

Abstract

The invention provides protection of the metal-cutting equipment and the workpiece against accidental consequences when cutting the cutting tool into the part or elements of the AIDS system during accelerated movements. The device contains a vibration transducer connected in series, a bandpass amplifier, a detector, a low-pass filter, a comparator, a three-input element I, a preliminary band force 1; a spruce, connected between the vibration transducer and a bandpass amplifier, three measurement channels, each of which contains a series-connected Hbie pulse displacement sensor, pulse shaper, adjustable one-shot, NOT element, two-input element And, the second input of which is connected to the output of adjustable The rator, the outputs of the elements AND channels are connected via a three-input element OR to the input of a three-input element AND, the third input of which is connected to the output of the CNC system, the input of which is connected to the output of the three-input element I. Obtaining information about the cutting process is carried out on the basis of joint consideration vibroacoustic emission signal and speed of movement of the cutting tool. 1 il. (L N9 00 Mrfl with Nj

Description

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The invention relates to mechanical engineering, in particular to metal cutting on CNC machines, and can be used to protect metal cutting equipment and workpieces from accidental consequences when inserting a cutting tool into a part or elements of the AIDS system in accelerated movements.

The aim of the invention is to expand the functionality by protecting the device from accidental cutting of the cutting tool into the part or elements of AIDS with speeds exceeding the working

The drawing shows a block diagram of the device.

The device consists of an acoustic signal generation channel that contains a vibration transducer 1 connected in series, a pre-bandpass amplifier 2, a band-pass amplifier 3, a detector 4, a low-pass filter 5, a comparator 6, and three identical measurement channels to determine if the permissible speed of the working movement is exceeded along the coordinates X, Y, Z. Each of the indicated channels contains a series-connected pulse displacement sensor 7, a pulse shaper 8, an adjustable one-shot 9, a second one vibrator 10, the NAND gate 11, two-input AND gate 12, a second input coupled to an output of an adjustable monostable multivibrator 9, wherein the output of the AND gate 12 is the output channel prevsheni determining the speed limit of the working movement.

The device also contains three-input logic elements OR I3 and And 14. At the same time, the inputs of the element OR 13 are connected to the outputs of the channels for determining the limiting speed of working displacements, and the output is connected to the first input of the element 14, the second input of which is connected to the output of the channel for generating an acoustic signal i.e. with the output of the comparator 6, and the third input is connected to the rotation sensor of the spindle (not shown) of the NC system 15. The output of the element 14 is connected to the schemes for stopping the feeding and rotation of the spindle (not shown) of the NC system 15

The device works as follows.

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At the moment of cutting the cutting tool into the part, intense vibro-acoustic radiation (vibro-acoustic emission) occurs in the cutting zone.

The VAZ signal is sensed by a transducer installed in the immediate vicinity of the cutting zone, for example, on a support, amplified by a pre-band amplifier 2 located in the immediate vicinity of the transducer 1, to reduce noise in the connecting wires. The signal is then amplified and filtered by the band-pass amplifier 3, detected by the detector 4 and fed to a low-pass filter 5. The time constant of the filter 5 is selected because of the separation of the useful signal about the cutting tool cutting into the part from pulsed electromagnetic and acoustic interference. The signal then goes to comparator 6, the threshold of which is selected in such a way that it triggers when a cutting process occurs. I

Determining the speed limit

the displacement along the coordinates, the limit values permissible for feed rates, based on the processing condition, is carried out using three identical measurement channels. Rabot1T they as follows. The pulses from the displacement sensors 7, by coordinates, the frequency of which is proportional to the speed of movement, are fed through the pulse shaper 8 to the adjustable one-shot 9. The single-shot 9 operates in restart mode, i.e. starts a new cycle of reference time, if during the time of the output pulse, a new trigger signal arrives at the input. The duration of a pulse generated by a single vibrator on the leading edge of the trigger pulse from the driver 5Q 8 can be adjusted and set equal to the period of the pulses from sensor 7, at the maximum working feed. Then, the pulses, whose frequency is determined by the frequency of the pulse from sensor 7, and the duration, by the single vibrator 9, are fed to the input of the single vibrator 10. The single vibrator 10, as well as the single vibrator 9, is triggered by a change in its input sig0

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from the low level to the high one, but unlike the first one-vibrator, the duration of the pulse generated by it is constant and equal to the period of the pulses from sensor 7 at the lowest possible feed rate. Next, the signal is inverted by the element HE 11 and fed to the element AND 12, to the second input of which a signal is output from the one-shot 9.

Consider the operation of this part of the scheme for three cases: a) there is no movement along the coordinate; b) the tool moves at the feed rate; c) the tool moves at a speed higher than the work feed.

In the first case, the pulses at the output of the sensor 7 are missing, therefore, the one-shot 9 and 10 are not triggered, and the output of the element 12 has a logical zero.

In the second case, the pulses from the sensor 7 movements, the passage through the shaper of 8 pulses, periodically start one-shot 9, which, in turn, starts the one-shot 10. Moreover, since the duration of the pulses generated by the one-shot 10 exceeds the follow-up period of the input pulses, having spread over the first input pulse, the one-shot 10 is in this state as long as the input pulses arrive. At its output there is a logical unit that does not transmit pulses from the output of the one-vibrator 9 to the input of the element AND 12. Thus, at the output of the channel (output of the element AND) there is a logical zero. I

In the third case, the period of input

the pulses will be less than the duration of the pulses generated by the single vibrator 9; therefore, skipping over the first input pulse, it constantly maintains the level of the logical unit at its output (fed by the input pulses). The single-vibrator 10, having transferred the signal at the output of the one-vibrator 9 along the leading edge, after a time equal to the duration of the impulse formed by it, passes into the state, the logical zero at the output. After the element 11 is inverted, this signal enters the input of the element 12 as a logical unit. The presence of two logical units at the inputs of the element And 12 leads to the appearance of the unit and its output.

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Thus, only in the case of a caliper moving at a speed v, which prefixes the maximum permissible operating speed of movement, the output of the corresponding channel is set to the level of the logical unit, which through the OR 13 element enters the first input of the three-input element 14.

Ø The signal at the inputs of the element I I4 carries the following information: the signal at the first input is about the movement of the support along one of the coordinates with a speed exceeding the maximum. . valid

 5 dp working feed; the signal at the second input indicates the presence of a cutting process; the signal at the third input signals the rotation of the spindle. The third signal is introduced to prevent false positives of the device when fixing the part, when mechanical shocks Mof yT are perceived as the beginning of the cutting process.

The presence of all three signals at the inputs of element And 14 indicates the occurrence of the cutting process during accelerated movement of the caliper, which indicates an accidental incision and causes the command to be issued with

30 output element And 14 in the CNC system

15 to immediately stop the feed and g rotation of the spindle.

Claims (1)

Invention Formula A control device for a CNC machine, containing a series-connected vibration transducer, a bandpass amplifier, a detector, a low-pass filter and a comparator, a CNC system with a spindle rotation sensor and spindle feed and rotation stop circuits, impulse displacement sensors of the actuator via controlled axes, characterized by the fact that, in order to extend the functionality by protecting the machine from accidental cutting of the tool, a three-inlet element AND, an OR element, whose output It is connected to the first input of the three-input element I, the second input of which is connected to the comparator, the third input to the rotation sensor of the spindle, and the output to the schemes for stopping the feed and rotation of the spindle, connected to the movement sensor connected to each device 35 40 512813776 pulse generator, controlled by one-, adjustable-stroke one-shot, novibrator, second one-shot, and the outputs of all two-input elements are NOT element, two-input element are And, And are connected to the element inputs — the second input is connected to the output OR,