SU1640545A1 - Adaptive radiation measurer for plate thickness and deviations from the average thickness - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the thickness of metal sheets during their hot rolling. The purpose of the invention is to increase accuracy and speed. This is achieved by choosing the optimal measurement cycle duration using a loop consisting of a reversible counter 20, a first counter 4, a second key 12, a third key 14, delay lines 18 and 19, and the first control unit 8. The use of delay lines increases the resistance of the circuit to the instability of the input signal. After a controlled rental comes out

Description

The invention relates to a measurement technique, is intended to measure thickness using wave radiation or fluxes of elementary particles and can be used to measure the thickness of metal, for example steel sheets, during their hot rolling on rolling mills, as well as to detect deviations of the measured thickness from the average value.

The purpose of the invention is to improve the accuracy at a limited counter size, optimizing the speed and self-tuning of the thickness gauge.

Fig. 1 shows a block electrical measurement circuit: Fig. 2 is a graph of the frequency of the signal at the detector output versus the thickness of the monitored metal and its linear approximation; on fig.Z - fragment of the timing diagram of the adaptation contour.

The adaptive radiation gauge of thickness and deviations from the average value contains an ionizing radiation source 1, detection unit 2, first key 3, first 4 and second 5 pulse counters, pulse generator 6, first RAM block 7, first control block 8, first block 9 indications, the first divider 10, a sheet presence indicator 11, a second key 12 with an inverse output, an inverter 13, a third 14. a fourth 15, a fifth 16 and a sixth 17 keys, a first 18 and a second 19 delay lines, a reversible counter 20, a microprocessor controller 21 second block 22, the second divider 23, the second control unit 24, the third counter 25, the second RAM block 26 and the reference absorbers block 27, the input of which is connected to the control output of the microprocessor controller 21, the output of the detection unit 2 through the third input of the first key 3 are connected with the counting input of the first counter 4 and the first input of the fifth key 16, the output of the first counter 4 is connected to the information input of the first RAM block 7 and the input of the second key 12. the inverse output of which is connected to the first inputs of the first 3 and t The second key 14 and the input of the inverter 13, the output of the inverter 13 is connected to the first input of the fourth key 15, the output of the third key 14 is connected to the clock input of the first delay line 18 and the reset input of the second delay line 19, and the output of the fourth key 15 to the clock input of the second line 19 and the reset input of the first delay line 18, the output of which is connected to the first counting input of the reversible counter 20, the output of the second delay line 19 connected to the second counting input of the reversing counter 20, the outputs of the first 7 and second 26 RAM blocks Connected respectively with the first and second inputs of the microprocessor controller

21, the third input of which is connected to the output of the reversible counter 20 and the information input of the second counter 5, the fourth input with the information output of the second counter 5, the fifth input - with the output of the metal presence indicator 11, the second input of the first control unit 8 and the second inputs of the fifth 16 and sixth 17 keys, the first and second information outputs of the microprocessor controller 21 are connected

respectively, with the first 9 and second 22 display units, the output of the pulse generator 6 is connected to the counting input of the second counter 5, the second output of which is connected to the second input of the first key 3

and the first input of the first control unit 8, the first output of the last one is connected to the zeroing input of the first counter, and the second output - with the second inputs of the third 14 and fourth 15 keys, the first input of the sixth key 17 and the write control input of the first memory unit 7, outputs n In addition, 16 and sixth 17 keys are connected to the counting inputs of the first 10 and second 23, respectively, divisors, the output

The first divider 10 is connected to the counting input of the third counter 25, and the output of the second divider 23 is connected to the input of the second control unit 24, the first output of which is connected to the zero inputs of the first 10, second 23 dividers and the third counter 25, and the second output to the write control input the second memory block 26, the information input of which is connected to the output of the third counter 25.

The meter works as follows.

During no rolling 28, a signal with a maximum frequency (Imax, which depends on the total thickness of parasitic absorbers between the ionizing radiation source 1 and the detection unit 2) is generated at the output of the detection unit 2. This frequency can also vary gradually over time. reasons, for example, when changing the parameters of the detecting unit 2, when accumulated in the control zone of the scale, separated from rolled products, etc. The signal from the detecting unit 2 is fed to the counters via the third input of the first key 3 the input of the first counter 4 in the presence of the second input of the first key 3 logical signal that permits the measurement cycle, the time of which is determined by the code of the binary number M set at the information input of the second counter 5 by a reversing counter 20. At the output of the second counter 5 a high-level logic signal is generated ( Fig. 36), the duration of which is determined by the expression

Tm at

(one)

where T is the duration of the thickness measurement cycle, s;

At is the oscillation period of the generator signal of 6 pulses, s.

The operation of the adaptation circuit, which includes the first key 3, the first counter 4, the second key 12 with the inverted output, the inverter 13, the third 14 and the fourth 15 keys, the first 18 and the second 19 delay lines, the reversing counter 20, the second counter 5, the generator 6 pulses and the first control unit 8, is reduced to ensure such a measurement cycle duration T, during which the counting input of the first counter 4 will receive a well-defined number of pulses N with a following frequency equal to Somax Outcome from the given N, which, in turn identifies with the required metrological accuracy of the thickness gauge, and use the expression f

N 2K- 1.

(2)

it is possible to determine a sufficient bit length in binary code of the first counter 4

(N-1),

(3)

where K is the number of binary bits of the first counter 4.

At the initial moment of time (at the moment of activation), a sufficiently small value M is entered into the reversible counter 20, at which the first counter 4 during the measurement cycle T does not have time to dial the maximum number N. As a result, logical 1 is stored at the inverse output of the second key 12 (FIG. The left part), by which the third key 14 permits the passage of the first delay line 18 and the reset input of the second delay line 19 to the clock input at the end of each measurement cycle at the second output of the first control unit 8 (Fig. 3 ) Multiplicity delays the first delay line 18 significantly exceeds the multiplicity of second delay line 19 and in practice conditions selected from

, Zmax

 Zg

VMHH Cumin

(four)

where Us is the delay ratio of the second delay line 18, rounded to the nearest whole number; Zmax is the maximum possible length of controlled roll, m;

VMHH minimum speed possible

movement of controlled roll, m / s;

Cmin is the minimum possible measurement cycle time, derived from the maximum possible frequency and size of the first counter with

This condition does not allow the measurement cycle duration to be varied during the control of the strip thickness. Through the LIB pulses, the first delay line forms a short pulse (fig3) at its output and returns to the initial state. This impulse causes the number M to be increased by one (in FIG. 3, the number M increases with

12 to 13), which, in turn, causes an increase in the measurement cycle time by At. The described process of increasing the measurement cycle time will continue for as long as the number of pulses

The detection unit 2, which passed through the first key 3 (Fig. 3D), during the measurement cycle time will not exceed N. In this case, the second key 12, having established that the first counter 4 is full, exposes in its

inverse output logic O (fig.Ze), which closes the first key 3, thereby prohibiting further operation of the first counter 4 (fig.Zd, right part). Besides. logical o closes the third key 14

and, transformed by an inverter 13 into a logical G (FIG. ZH), permits the passage of pulses from the second output of the first control unit 8 (FIG. D) to the clock input of the second delay line 19 and the input

resetting the first delay line 18 through the fourth key 15 (FIG. 3K). The delay ratio of the second delay line 19 is practically selected within 4–16 units. This line is intended to protect the adaptation circuit from accidental interference associated with possible electromagnetic high-frequency pickups on the line. transmissions from the detecting unit 2 to the first key 3, the randomness of the process of dividing the radioactive element of the ionizing radiation source, and the like. After 4–16 times confirming that the first counter 4 overflows, the second delay line 19 forms a short pulse (not shown) reducing the number M by one. If this condition in the process of dialing the specified number of the second delay line 19 is not fulfilled, then the third key 14 generates a pulse which nulls the contents of this delay line and triggers the first delay line 18. Thus, both the first 18 and second 19 delay lines make the adaptation circuit resistant to possible instability of the input signal.

At the end of each measurement cycle, the first control unit 8 and the second output generates a short pulse (Fig. 3b), recording information accumulated in the first counter 4, into the first operating memory unit 7, and a short pulse at the first output at the moment the new cycle starts. measurement (FIG. 3), which zeroed the first counter 4, preparing it for a new measurement.

A scheme for extracting the average frequency of the useful signal, including the fifth 16 and sixth 17 keys, the first 10 and second 23 dividers, the second control unit 24, the third counter 25 and the second main memory unit 26, work as follows. When a metal enters the control zone, the sheet presence indicator forms at its output a signal that opens the fifth 16 and sixth 17 keys. As a result, the third counter 25 begins to integrate the pulses generated at the output of the first divider 10 and obtained as a result of dividing the frequency of the useful signal transmitted from the output of the detection unit 2 through the first 3 and fifth fifth keys.

The second divider 23 calculates using the pulses generated at the second output of the first control unit 8 and passing through the sixth key 17, the number of complete measurement cycles.

The conversion factor for the first 10 and second 23 divisors is the same and equals a certain number I, which is chosen

starting from the required length of the section of the sheet being checked, on which it is necessary to average the thickness of the rolled products. Upon the expiration of the I measurement cycles, the second divider 23 generates a pulse, under the action of which the second control unit 24 produces a short pulse at the second output, causing the second RAM unit 26 to receive the information accumulated by the third

the counter 25 for the I cycles, and then at the first output — a short pulse, nulling the first 10, second 23 dividers and the third counter 25, returning the allocation circuit of the average value of the useful signal frequency to the initial state. The number loaded into the second block of RAM 26 from the third counter 25 is determined by the expression

Per

 J

(n, / l)

(five)

or

Per 1/1 2)

P |

i 1

(6)

where psr is the number loaded into the second memory unit and equal to the average value of the normalized frequency n for the first measurement cycles;

I - the conversion factor of the first 10 and second 23 dividers;

j is the number of the current measurement cycle;

l; - the normalized frequency of the useful signal at the i-th measurement cycle, i.e. the number of pulses calculated by the first counter 4 and memorized by the first RAM block 7 during the measurement cycle time T, which is set optimally.

The actual value of rii depends on the thickness of the controlled roll,

water normalized frequency values of n, in

The absolute value of the thickness of the monitored roll is carried out by the microprocessor controller 21, using for this purpose any known algorithm, for example, a piecewise linear approximation of a nonlinear characteristic (FIG. 2), which, in turn, can be obtained during active testing and self-testing, which As follows, after the controlled steel leaves the control zone, the microprocessor controller 21 will issue a command to the block 27 of the reference absorbers to enter the control zone via the control output. light of the

or another metal plate of a given thickness. Thus, in the pauses between the control of the metal, the thickness gauge conducts an automatic self-calibration.

The information entered into the microprocessor controller 21 from the output of the first RAM block 7 is converted into a numerical code corresponding to the measured thickness value, displayed in a form convenient for the operator on the first display unit 9, and the deviation of this thickness from the average value received from the second block 26 of the RAM and converted in a similar manner, on the second display unit 22.

Under real conditions when measuring the thickness of rolled 28, for example steel sheet, during sheet rolling on the rolling mill, the sheet may leave the measurement zone at any time, even at the very beginning of the measurement cycle. For the last measurement of this sheet, it is not known what time from measurement cycle, it is present in the control zone, and the number worn by the first counter 4 does not carry information about the measured thickness of the object 28, i.e. The last measurement has a large error. When an object leaves the control zone, the sheet presence indicator 11 generates a corresponding signal, under the action of which the first control unit 8 at its second output generates a short pulse, similar to that generated at the end of the measurement cycle (Fig. 3b). This impulse organizes the input into the first block 7 of RAM by the information accumulated by the first counter 4. Simultaneously, the microprocessor controller 21 is loaded with the number M and the current state of the second counter 5. The input is made at the third and fourth inputs of the microprocessor controller 21, respectively. These two numbers determine the additional error of the thickness gauge on the last measurement cycle, which is approximately calculated by the formula

M

(7)

or

M

5доп - Оосн / р

(eight)

where (Zopop is the additional error of the thickness gauge arising due to the shortening of the measurement cycle time, mm;

5n - main error of thickness gauge, mm;

e is the current state of the second counter 5, if the latter is operating in the summing mode of the generator 6 pulses from zero to M;

F is the current state of the second counter in the event that the latter is operating in the mode of subtracting the pulses of the generator 6 from M to zero.

The basic absolute error of the thickness gauge in the first approximation is determined by the formula

OoCri -

D P ODIX

S7jj

N

(9)

where Ah is the specified increment of the thickness of the sheet 28 in the control zone, mm;

Dso - change in the frequency of the last signal corresponding to a given increment on the most gentle part of the characteristic (FIG. 2, the right part), 1 / s. The result of the calculation obtained from expression (8) is also displayed on display blocks 9 and 22, which makes it possible to judge the error of the thickness gauge with full and especially with reduced last measurement cycles

Claims (1)

Invention Formula An adaptive radiation thickness and deviation from the average value, containing a source of ionizing radiation, a detection unit, the first key, the first and second pulse counters, a pulse generator, the first RAM, the first control unit, the first display unit, the first divider and the sheet presence indicator, which is different in that, in order to increase accuracy and speed, it is equipped with a second key with an inverse output, an inverter, the third, fourth, fifth and sixth keys, the first and second delay lines, a reversible counter, a microprocessor controller, a second display unit, a second divider, a second control unit, a third counter, a second main memory unit and a block of reference absorbers whose input is connected with microprocessor controller control output, the output of the detection unit through the third input of the first key is connected to the counting input of the first counter and the first input of the fifth key, the output of the first counter is connected to the information input of the first RAM block and the second key input, the inverse output of which is connected to the first inputs of the first and third keys and the inverter input, the inverter output is connected to the first input of the fourth key, the third key output is connected to the clock input of the first delay line and the reset input of the second delay line key - with the clock input of the second delay line and the reset input of the first delay line, the output of which is connected to the first counting input of the reversible counter, the output of the second delay line connected to the second counting input of the reverse with the outputs of the first and second operational units are connected respectively to the first and second inputs of the microprocessor controller, the third input of which is connected to the output of the reversible counter and the information input of the second counter, the fourth input - to the information output of the second counter, the fifth input - with the output of the indicator of the presence of metal, the second input of the control unit and the second inputs of the fifth and sixth keys, the first and second the information outputs of the microcontroller spring controller are connected respectively to the first and second indication blocks, the output of the pulse generator is connected to the counting input of the second counter, the second output of which is connected to the second input of the first key and the first input of the first control unit, the first output of the last one, and the second output — with the second inputs of the third and fourth keys, the first input of the sixth key, and the recording control input of the first RAM block, the fifth and sixth outputs The keys are connected to the counting inputs of the first and second dividers, respectively, the output of the first divider is connected to the counting input of the third counter, and the output of the second divider is connected to the input of the second control unit, the first output of which is connected to the zeroing inputs of the first, second dividers and the third counter, and the second output - with the recording control input of the second memory unit, the information input of which is connected to the output of the third counter. nm U 1D 1ШШЛЛЖШЛШШЛШШ ЕЦ g 1 1 f s): i. 1 - / x fj I s t (Mr MI Pw.J