SU1201114A1 - Grinding machine control system - Google Patents

Abstract

A GRINDING MACHINE CONTROL SYSTEM containing a measuring head i connected to an electronic amplifier, the output of which is connected to the first integrator, an adder, and connected in series to a differentiating cell, a reference element and an executive element of the machine, characterized in that, for the purpose of accuracy, it equipped with a subtracting device, the first input of which is connected to the first integrator, two amplitude detectors, the inputs of which are connected to the subtractive device, and the outputs to the adder, the second int The controller, whose input is connected with the output of the adder, and the outputs with the second input of the subtractor i device and with the differentiating cell, and the speed controller for the SL SL allowance, the input of which is connected to the output of the electronic amplifier, and the output with the second input of the comparison element,

Description

The invention relates to a machine tool industry and can be used to control the feed during mortise grinding.

The aim of the invention is to improve the accuracy by controlling the feed during the entire processing cycle and suppressing the high-frequency and low-frequency components of the measurement information signal.

FIG. 1 is a block diagram of a grinding machine control system; Fig. 2 is a plot of the measurement information signal during the removal of the allowance at the input of the first integrator; in fig. 3 is the same at the output of the second integrator; in fig. 4 is a graph of the variation of the cross feed rate of the machine as a function of the removed allowance X

The grinding machine control system contains an inductive measuring head 1, which controls the size of the part 2. The measuring head 1 is connected in series with the electronic amplifier 3, the output of which is connected to the inputs of the first integrator 4 and the setpoint controller 5 for removing the allowance. The output of the first integrator 4 is connected to one of the inputs of the subtracting device 6. The output of the subtractive device 6 is connected to the inputs of amplitude detectors 7 and 8, the outputs of which are connected to the inputs of the adder 9 The output of the adder 9 is connected to the input of the second integrator 10. The output of the second integrator 10 is connected to the input the differentiation of the cell 11 and the second input of the reading device 6; The output of the differentiating cell 11 is connected to one input of the comparison element 1 2, the other: the input of which is connected to the speed reference 5. Output of the comparison element 12 is connected to the actuating element 13 of the machine 14.

The system works as follows.

When machining part 2 on a grinding machine 14, the allowance X controlled by the measuring head 1 by the diameter of the part changes from a certain value Dp. to zero (curve 15 in FIG. 2).

The measurement information signal (Fig. 2) is a constant component, on which interference signals of different physical nature are superimposed and characterized by their frequency, duration and amplitude. FIG. 2 (curve 15)

shows the component, the characteristic shape of the part. Signals that carry information about the roughness and other defects of the surface of the part are superimposed on this component.

In addition, very often single impulse noise is also present (Fig. 2, the segment ix t arising from the ingress of grains of abrasive material under the measuring

probe gauge. The measuring information signal X, removed by measuring head 1, passes through an electronic amplifier 3, which performs amplification, signal conversion

and linearization of the transform characteristic. From the output of the electronic amplifier 3, the measurement information signal X is fed to the integrator 4. The task of the integrator 4 is to suppress impulse noise having a random distribution pattern. The time constant of the integrator is taken from the condition

,,

where the duration of the interference signal (on the order of 10-15 ms. In this case, the absolute error at the output of integrator 4 is determined by

from the expression

H-vc

 U C about

where Y ,, is the rate of change of the signal at the integrator output; UMCIKC maximum value

the signal at the input of the integrator is 5tor (10 V);

5 - the steepness of the measuring information signal (8 mV / μm). Then ujj 1.25 microns. 50 Thus, an interference signal with a duration of 10-15 ms of any amplitude is limited to 1-1.5 µm. The signal, free from amplitude noise, arrives at one 55 of the inputs of the read device 6, to another input which receives a signal from the output of the second integrate 10. Signal from the output of the integrator

10 is a constant component (curve 16 in FIG. 3) of the measurement information signal and is free from interference. As a result of the subtraction in the subtractor 6 at the output thereof. There is variable ca. interference signal, mainly due to the deviation of the part shape, roughness. The interference signal arrives at the inputs of the amplitude detectors 7 and 8, which rectify the interference of the positive and negative polarities, respectively. From the outputs of the amplitude detectors 7 and 8, the rectified interference signal of the positive and negative polarities is passed to the adder 9, where the value of the average component of the interference signal is determined by algebraic summation. From the output of the adder 9, the average component of the interference arrives at the second integrator 10. The task of the integrator 10 is to extract a constant component of the signal that is free from interference. The voltage at the output of the integrator 10 varies at the same speed as the input, but does not contain an interference signal.

Denote:

max is the maximum value at the input of the subtractor 6;

R / min is the minimum value of the signal at the input of the subtractor 6; constant

the input signal of the subtractive device 6; x - rate of change of signal

measuring information; x is the delay of the signal passing through the integrato 10.

Then the voltages at the output of the amplitude detectors 7 and 8 are respectively

.Kc-Dcp + Vxi (1) U, D «HH-D ,. (2)

Voltage tij. at the top of the adder 9 equals

Uj., - e "v ,.

This voltage is fed to the input of the second integrator 10. The speed

changes in this signal at the output of integrator 10 can be determined from the expression /

 -2,6V,

(3)

dt

where T is the integrator time constant 10.

On the other hand, the voltage on the output of the integrator 10 is:

fJu (4)

Or, substitute (4) in (3) and count. (TVx const, we get

15

(five)

Comparing (3) and (5), we see that the 20 rates of change of the signal at the input and output of the integrator GO are the same. From the output of the integrator 10, the signal enters the differentiating cell 11, where after differentiation, 25 determines the rate of change

signal X:, SX

 I T

- “V, (npH06)

The signal V | f is fed to one input 30 of the comparison element 12, the other input of which receives the signal Vg from the output of the speed limiter 5. The speed limiter 5 on the basis of the information about the monitored size X at its input generates an algorithm for controlling the speed Vg allowances in function X (curve 17 of Fig. 4). The specified algorithm is described by the expression

V3 - V "- con5i for X" ajc xrX |,

VM-V.

(6)

UK-X)

where X is the maximum value

removable allowance; Hz is the value of the removed allowance at which the change in the feed rate of the grinding wheel occurs.

Comparison element 12 patterns mismatch 18

55 AV "Vg-V. (7)

After amplification, the error signal DU is supplied to the actuating element 13, which controls the cross feed rate of the machine 1A. In section X, the transverse feed rate, given by the algorithm (6), is maximal (V). The actual feed rate V (Fig. A, curve 19), which is output, the differentiation of cell 11, also has a maximum value and fluctuates around a given value of V / y,. Upon reaching the value of 146 Hu; the cross feed rate is linearly reduced to the value of V V, then the grinding wheel is retracted. Thus, the execution of the algorithm (6) requires knowledge of the real speed of removal of the allowance x during the whole part processing cycle. In turn, this allows organizing the filing fee also during the whole processing cycle.

J6

Scp

Claims (1)

GRINDING MACHINE CONTROL SYSTEM, comprising a measuring head, connected to an electronic amplifier, the output of which is connected to the first integrator, an adder, and series-differentiating cell, a comparison element and an actuating element of the machine, characterized in that, in order to increase accuracy, it is equipped a subtractor, the first input of which is connected to the first integrator, two amplitude detectors, the inputs of which are connected to the subtractor, and the outputs to the adder, the second integrator Whose input is connected to the output of the adder and the outputs - to the second input of the subtractor and differentiating © cell, and the stock removal rate setting device having an input coupled with the output of the electronic amplifier, and the output - to the second input of the comparison element. SU „„ 1201114 ΐ