SU1421505A1 - Apparatus for monitoring position of grinding wheel of machine tool - Google Patents

Abstract

The invention relates to the automation of production processes and is intended for the automatic control of grinding machines. The purpose of the invention is to increase the machining accuracy by taking into account the control error caused by a decrease in the diameter of the grinding wheel as it is worn. The device is equipped with a serially connected programming device and adder. The adder is connected between the output of the converter and the first input of the threshold device, and the input of the programming device is connected to the output of the threshold device directly or through the machine control circuit. 3 il. S

Description

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The invention relates to the automation of production processes and can be used in automatic control systems on grinding machines.

The purpose of the invention is to increase the machining accuracy by taking into account the control error caused by a decrease in the grinding wheel diameter as it is worn.

FIG. 1 shows a control error generation scheme; in fig. 2 is a block diagram of the device; in fig. 3 is a diagram of the position of the grinding wheel at the moment of issuing a command for sub-adjustment and. after its implementation at the beginning of processing and after the n number of sub-adjustments.

FIG. 1 shows a diagram of the image. function of the number of sub-adjustments.

the inaccuracy of monitoring the position of the grinding wheel by a known device for the general case where the point a of contact

 sensor element of the measuring device is shifted relative to the point b of the contact of the grinding 20

the circle with the workpiece at a distance //, and the measurement line does not coincide with the normal passing through point a.

The index A indicates the cutting position, the grinding wheel surface prior to the beginning of processing, the index b - its position at the moment when the control device issues the first command for subsetting, indexes C and D - its position at the time of issuing the 5th command for subsetting and after its implementation.

The error in the D position of the grinding wheel, due to a decrease in its diameter, after η number of sub-adjustments is determined as follows:

(ti +) S, where S is the value of the sub-adjustment impulse;

R (t and Rn are the radius of the grinding wheel, respectively, during adjustment and after n the number of sub-adjustments.

R ,, (l + SnY + (h-S) (l + Sn) (n-S) cosY.

With intensive wear of the grinding wheel, for example, operating in self-sharpening mode, the magnitude of the error D, 1 during the time between adjustments of the measuring transducer can significantly exceed the processing tolerance, which leads to marriage.

The device contains a measuring transducer 1 connected in series, the sensitive element of which is in contact with the cutting surface of the grinding wheel 2, the adder 3 and the threshold device 4 connected via the second input to the setting device 5, and the programming device 6. The programming device 6 is connected to the second input of the adder 3 and at the input - with the output of the threshold device 4 or directly (in Fig. 2, this connection is shown by the dotted

25

40

50

This function, for example, for the last measurement line parallel to the tipping circle passing through a point with machining (Fig. 3), has the form

-H

6 v c - // 2-vn "where /. (N-t-l) S.

The formula is obtained when d.

To simplify the scheme of the past device, the function can be modulated as piecewise linear in this case. Programming can be performed in the form of a sequential counter of the number of subadapting transducer and the mas amplifier. Commands on the measurement come from the travel triggering at a given grinding wheel head, j. The grinding wheel can be used according to the selected linear function.

The device works shortly.

At the initial moment, the output signal of programming 6 has a zero value and the new device 4 with a sum signal corresponding to the input signal 1.

When the grinding wheel S is worn, the signal arriving at the body 1 becomes equal to the one that is set from the setting device 5. Portion 4 is triggered and the machine receives a signal

The signal from the threshold device or through the circuit also enters the input of the prog device 6 and the output signal in accordance with the rear. This signal in the adder 55 from the signal of measuring p 1 and the threshold device 4 do not need to be repaired when the grinding wheel is

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1421505

line), or through the machine control circuit 7.

To eliminate the machining error associated with an increase in the curvature of the tested surface of the grinding wheel as it wears out, the retrain command must be made each time with the wear wheel of the grinding wheel along the measurement line (Fig. 3), corresponding to a reduction in its radius by the amount of the adjustment pulse .

In order to fulfill this requirement, the magnitude of the signal at the output of the programming device 6 at a constant value of the sub-adjustment pulse must be

function of the number of sub-adjustments.

This function, for example, in the case where the measurement line is parallel to the normal passing through the point of contact of the grinding wheel with the workpiece (Fig. 3), has the form

0

five

0

0

(

6 v c - // 2-vn "where /. (N-t-l) S.

The formula is derived under the assumption that.

To simplify the programming circuitry, the function can be approximated by a piecewise linear function. In this case, the programming device can be executed, for example, in the form of a series-connected counter of the number of subadjustments, a digital-to-analogue converter, and a scaling amplifier. Commands to change the scale come from limit switches that operate at given positions of the grinding wheel head. Defined by j. The grinding wheel heads are installed according to the chosen piecewise linear function.

The device works as follows.

At the initial moment of processing, the signal at the output of the programming device 6 has a zero value and the signal corresponding to the signal of the converter 1 is input to the input of the threshold device 4 from the adder 3.

When the grinding wheel is worn by S, the signal coming from converter 1 becomes equal to the signal coming from setpoint 5. Threshold device 4 is triggered and a signal for subsetting is received in machine control circuit 7.

The signal from the threshold device 4, either directly or through the control circuit 7, is also fed to the input of the programming device 6, and at its output a signal is generated in accordance with a predetermined algorithm. This signal in the adder 3 is subtracted 5 from the signal of the measuring transducer 1 and the threshold device 4 issues a command for sub-adjustment at the wear value of the grinding wheel along the line of the measured dimension.

five

associated with the first input with a converter, and output with a machine control circuit, and a setting device connected to the second input of the threshold device, characterized in that, in order to improve accuracy, it is equipped with a programming device connected with its input to the output of the threshold device and consisting of a series-connected counter of the number of sub-adjustments of the grinding wheel,

of the machine’s foveal circle, which contains a digital-to-analogue converter and a mass-measuring converter, a sensitivity-stacking amplifier, the output of which

The main element of which is intended to be connected to the input of an adder injected into the device with the cutting surface, connected between the grinding wheel, the threshold device, the distributor and the threshold device.

corresponding to the reduction of the radius of the grinding wheel on the value of S.

Thus, the device allows to increase the processing accuracy due to the automatic correction of the signal of the measuring transducer 1 according to a given program.

Claims (1)

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