JPH03167401A - Method for measuring thickness of rolled strip plate - Google Patents

Abstract

PURPOSE:To enhance measuring accuracy by utilizing a plate-thickness converting expression based on mass-flow constant rule, using the measured values of the peripheral velocities of first and second rolls and preceding rates, and computing the plate thickness of the second roll. CONSTITUTION:Peripheral velocities VRA1 and VRA2 of an input-side roll 9A and a final-stage roll 9B are measured with pulse generators 7. Plate thicknesses H1 and Hout are measured with a gamma-ray thickness gage 5 and an X-ray thickness gage 6 which are attached in front of the roll 9A and at the rear of the roll 9B. Then, an output-side computed plate thickness value hout is obtained based on an actually measured value H1 in an output-end plate-thickness operator 21 by using the peripheral velocities VRA1 and VRA2 and preceding rates f1 and f2 of the rolls 9A and 9B and utilizing a converting expression based on a mass-flow constant rule. In a measured-plate-thickness-value evaluating device 22, the computed plate thickness value hout and an actually measured plate thickness value Hout are compared. When the difference is larger than a plate- thickness allowance error hout which is inputted from a setting device 1, an alarm signal is outputted to an upper process computer 23 as the abnormality of the apparatus.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for measuring the thickness of a rolled strip, and in particular, when measuring the thickness of a strip rolled in a continuous rolling mill while processing the strip, the present invention outputs thickness measurement data and measures the thickness of the strip. The thickness of the rolled strip is suitable for preventing the continued production of rolled strips with poor thickness by immediately detecting any abnormality in the equipment and outputting a measurement abnormality alarm signal. Concerning improvements in measurement methods.

[Conventional technology]

Conventionally, the thickness of a rolled strip is measured using an X-ray thickness meter or radiation thickness meter during processing in a continuous rolling mill. On the other hand, the following technology is disclosed in Japanese Patent Publication No. 49-46270. As shown in FIG. 5, the strip plate 18 is wound onto the take-up reel 10 via the deflector roll 31, and the deflector roll 31 and the take-up reel are moved by an amount proportional to the amount of advance of the strip plate 18. 10 is designed to rotate. The deflector roll 31 and the take-up reel 10 are provided with a measuring device for measuring the rotation angle. The rotation angles of the deflector roll when the strip plate 18 is fed by the lengths L1 and L2 starting from a certain point when the strip plate 18 is wound up to D2 on the take-up reel 10 are respectively expressed as θ1 and θ2. If the rotation angles of the winding and collecting sole are respectively ψ1 and ψ2, the following equation holds. L + = D 2 / 2・ψ++t/4π・ψ12
= D + / 2・θ1 ... (1) L
2 = D 2 / 2・ψ2+t/4π・ψ22=
D I /2・θ2 ... (2) This (1
), by eliminating D2 from equation (2), t={2πD+(
θ2ψ1−θ1ψ2)}/ψ1ψ2《ψ2−ψ1)
...(3), and the average thickness t of the strip can be found.
On the other hand, the following extraction technique is disclosed in Japanese Patent Publication No. 50-22415. As shown in FIG. 5, the strip 18 is wound onto the take-up reel 10 via the deflector roll 31, and the deflector roll 31 and the take-up are taken up by an amount proportional to the amount of advance of the strip 18. The reel 10 is set to rotate. A measuring device for measuring the rotation angle is attached to the deflector roll 31 and the take-up reel 10. When the advancing speed of the strip plate 18 is constant, the differential creta roll 31 rotates at a constant speed, but on the other hand, the take-up reel 1
0, as the strip plate 18 advances and the number of wraps to be wound increases, the radius increases by an amount equal to the thickness of the strip plate 18 per revolution, so the rotation speed becomes slower. So,
The thickness of the strip plate 18 is determined from the slope of the change in the rotational speed ratio of the deflector roll 31 and the take-up reel 10. On the other hand, Japanese Patent Laid-Open No. 54-58462 discloses the following technology. This is almost the same as the above-mentioned Japanese Patent Publication No. 50-22415, and when the above-mentioned Japanese Patent Publication No. 50-22415 calculates the plate thickness of the strip plate 18 from the gradient of the change in the rotational speed ratio of the deflector roll 31 and the take-up reel 10, Since the radius of the reel is used as the initial value, the measurement start point was limited to when winding was started on a new take-up reel, but in JP-A-54-58462, the radius of the take-up reel at the time of the start of measurement is used. This allows the measurement of plate thickness to be started at any time.

[Problems to be solved by the invention]

However, although measuring instruments such as X-ray thickness gauges and radiation thickness gauges can accurately measure minute deviations in plate thickness, they cannot directly measure the absolute amount of plate thickness. Also, the radiation of radiation sources!
There are problems such as long-term drift due to attenuation of the amount of l, making it difficult to obtain absolute reliability. Therefore, in order to improve reliability, these measuring instruments are generally backed up by other measuring methods. Also, Special Publication No. 49-46270, Special Publication No. 50-22415
, JP-A-54-58462 both measure the rotational speed of the backup roll or the final rolling roll to determine the rolling speed of the strip, but it is correct that the backup roll or the final rolling roll slips with respect to the strip. It is not possible to determine the rolling speed. In general, backup rolls have more slip than the final rolling roll. Furthermore, when measuring the rolling speed using the final rolling roll, if the rolling conditions such as tension change, the advance rate changes and the ratio between the rotational speed of the rolling roll and the rolling speed changes, causing variations in the measured values. ．．

Purpose of the Invention 1 The present invention has been made in view of the above-mentioned problems of the conventional art. In addition to correcting the measured value as appropriate to improve the accuracy of plate thickness measurement, in the unlikely event that an abnormality occurs in the speed measurement or plate thickness measuring device of this strip and the reliability of the plate thickness measurement decreases. The first object of this invention is to provide a method for measuring the thickness of a rolled strip that can improve the reliability of thickness measurement by detecting this abnormality and outputting an alarm signal. A second object of the present invention is to improve the accuracy of the advance rate used in sheet thickness calculation, thereby improving the accuracy of sheet thickness measurement. [Means for Solving the Problems] The present invention provides a method for measuring the thickness of a strip rolled in a continuous rolling mill, in which the first thickness is directly measured in the vicinity of the first rolling roll; A first rolling roll peripheral speed is measured with the first rolling roll, a second rolling roll peripheral speed is measured with a second rolling roll different from the first rolling roll, and the mass flow is determined according to the constant mass flow law. Using the plate thickness conversion formula based on
Based on the first plate thickness, the measurement value of the circumferential speed of the rolling roll, the advancement rate of the first rolling roll, the measurement value of the circumferential speed of the second rolling roll, and the advancement rate of the second rolling roll, the exit side of the second rolling roll is determined. The first objective was achieved by calculating the thickness of the plate. The present invention also provides a method for improving the precision of the advance rate in a method for measuring the thickness of a strip rolled in a continuous rolling mill, in which the forward tension of the strip is measured in front of the rolling roll, and the tension of the strip is measured in front of the rolling roll. Measure the rear tension of the strip at the rear of the rolling roll, and measure the inlet thickness of the strip at the front of the rolling roll, or use a preset thickness value to determine the inlet thickness, and then calculate the front tension. Calculate and learn using the rear tension and the entrance plate thickness,
A temporary advance rate is determined, and the determination of the temporary advance rate is performed on a plurality of rolls, a plurality of temporary advance rates are determined, the circumferential speed of each of the plurality of rolls is measured, and the circumferential speed of each of the plurality of rolls is determined. Calculate and learn from the provisional advancement rate, the inlet plate thickness, and the rolling roll circumferential speed to obtain an advancement rate correction value, calculate the advancement rate from the provisional advancement rate and the advancement rate correction value, and use the advancement rate. The second objective was achieved by calculating the plate thickness.

[Effect]

In the present invention, we focus on the fact that in continuous rolling mills, X-ray thickness gauges, radiation thickness gauges, etc. are usually installed at several locations on the F2 in the continuous rolling mill as means for measuring plate thickness for feedback of plate thickness control. At the same time, in order to cover the shortcomings of these X-ray thickness gauges and radiation thickness gauges in measuring the absolute amount of plate thickness, the values of the thickness gauges installed at multiple locations in the continuous rolling mill should be mutually checked. This method checks for abnormalities in these thickness gauges, etc., and determines the final thickness measurement of the rolled strip. Therefore, the reliability problem of X-ray thickness gauges and radiation thickness gauges, which has been a problem in the past, can be solved by mutually checking the measured values of two or more thickness gauges. Further, in the present invention, the rolling speed value of the rolled strip obtained from the rotational speed of the rolling roll is used to mutually check the measured values of two or more thickness gauges. Even if it becomes impossible to obtain the correct rolling speed value due to slippage between the rolling plate and the plate, this will not be a problem as the abnormality can be detected from the results of mutual checking of the measured values of the thickness gauge. Furthermore, the circumferential speed of the rolling roll and the advance rate of the rolling roll are used as substitutes for the rolling speed in numerical calculations for obtaining plate thickness measurements and checking for abnormalities between thickness gauges. By learning the rate and parameters for calculation based on the rolling tension, actual Mt plate thickness, and rolling roll circumferential speed, it is possible to improve the accuracy and reliability of plate thickness measurements. can. Learning of this advance rate is performed based on changes in the front tension and rear tension, which have a large effect on the advance rate among changes in rolling conditions. In general, it is experimentally known that when the front tension of a certain roll increases, the advance rate of that roll also increases, and when the rear tension increases, the advance rate of that roll decreases.

【Example】

Hereinafter, a first embodiment of the present invention will be explained in detail using FIG. In this first embodiment, a gamma ray thickness gauge 5 is provided in front of the final rolling roll 9B in the continuous rolling mill to measure the thickness of the strip at a point in the middle of processing, and to measure the rolling speed at the point in the middle of processing. In order to obtain an approximate value, a pulse generator 7 is provided on the rolling roll 9A immediately after the gamma-ray thickness gauge 5, and the circumferential speed of the rolling roll 9A is measured. In addition, an XIl thickness meter 6 is installed at the outlet of the continuous rolling mill to measure the thickness of the strip at the outlet of the continuous rolling mill, and to obtain an approximation of the rolling speed at the outlet of the continuous rolling mill. A pulse generator 7 is provided on the rolling roll 9B immediately before the thickness gauge 6 to measure the circumferential speed of the rolling roll 9B. The setting device l is a means for inputting parameters, etc. for plate thickness calculation using push buttons, a keyboard, etc. The outlet end plate thickness calculation unit 21 calculates a calculated plate thickness value in terms of exit @ from the gamma ray thickness gauge 5, the measured value of the pulse generator 7 at the 2fl position, and the advance rate set by the setting device 1. The plate thickness measurement value evaluator 22 calculates the plate thickness meter 3! in terms of the outlet end.
．． The value hout is compared with the measured value of the X-ray thickness gauge 6 at the outlet of the continuous rolling mill}{out, and evaluation is performed based on the plate thickness tolerance set value set by the setting device 1. The operation of the first embodiment of the present invention will be explained below using FIG. A pulse generator 7 for measuring the circumferential speed of each roll is attached to the inlet side rolling roll 9A and the final rolling roll 9B, and the circumferential speed of each rolling roll 9A, 9B is determined by the pulse generator 7. Measure l and vRA2. Next, the plate thicknesses H1 and }lout are measured using thickness gauges 5 and 6 installed in front of the inlet side rolling roll 9A and behind the final stage rolling roll 9B. In the outlet end plate thickness calculator 21, the vR^1,
vR^2, hAt and advance rates f1, f2 of the inlet side roll 9A and final stage roll 9B input from the setting device 1
From the measured value H1 of the plate thickness in front of the nine rolling rolls on the inlet side, the calculated value hout of the plate thickness on the outlet side is obtained. The calculation method is as follows. In a continuous rolling mill, the strip taken in from the machine entrance is completely discharged to the exit side after processing such as rolling, and the constant mass flow law is established, so the following equation is established. VRAI (1+ ft ) hout=Vp^t (
1,000ft+)Xlt+/VRA 2 (1,000ft)
...(5) As a result, the plate thickness meter X value ha on the outlet end side
Find ut. This first step to measure the thickness of the rolled strip
In the example, this calculated value hout is used as the final plate thickness measurement value. This plate thickness calculation value ho ut and the actual measurement value HOυt by the X-ray thickness meter 6 behind the final rolling roll 9B
should match. The plate thickness measurement value evaluator 22 compares the calculated plate thickness hout and the measured plate thickness} lout, and when the difference is greater than the plate thickness tolerance Δha ut, which is the set value input from the setting device l, An alarm signal is output to the upper process computer 23 as an abnormality in the equipment. This abnormality is caused by γ
Failure of line thickness gauge 5, X-ray thickness gauge 6, rolling roll 9A,
It is possible that the measurement value of the pulse generator 7 is abnormal due to a slip of the 9B. In this way, the reliability of the method for measuring the thickness of rolled strips can be increased by using the measured thickness of at. Further, a second embodiment will be explained below using FIG. 2. This second embodiment is based on the first embodiment, and the advance rate used in the plate thickness calculation to convert the value of the inlet gamma-ray thickness meter 5 of the first embodiment to the outlet end plate thickness is based on actual measurement data. The purpose is to have children learn by learning from each other. Therefore, the second embodiment will be explained with respect to this advanced rate learning method. In the advanced rate learning method of the second embodiment, a tension gauge 8 is placed before and after the roll roll 9A with an open entrance, a γ-ray thickness gauge 5 is placed in front of the roll roll 9A, and a pulse generator 7 is placed on the roll roll 9A itself. These measured values are taken into the temporary advance rate learning device 3 to determine the temporary advance rate of the inlet side rolling roll 9A. Similarly, tension gauges 8 are placed at the front and rear of the final roll 9B, and a pulse generator 7 is placed on the roll 9B itself, and together with these measured values, the front plate thickness of the final roll 9B is set in advance. The value is taken into the temporary advance rate learning device 3 and the temporary advance rate of the final rolling roll 9B is determined. Further, a pulse generator 7 disposed on the inlet side rolling roll 9A and the final stage rolling roll 9B.
and a gamma ray thickness meter 5 placed in front of the inlet side rolling roll 9A.
and Xa! placed behind the final rolling roll 9B! Thickness total 6
The respective measured values and the tentative advance rates of the inlet side roll 9A and the final stage roll 9B are taken into the advance rate correction value learning device 2, and the advance rate correction value is determined. The second aspect of the present invention will be described below.
Among the examples, the effect of advanced rate learning will be explained using FIG. Learning the advance rate utilizes the fact that the advance rate of a roll can be calculated as the number between the front tension and rear tension of that roll. Then, by comparing and correcting the advanced ratios of a plurality of rolling rolls calculated in this way, accuracy can be further improved. Here, the advanced rate before comparing and correcting multiple advanced rates is the provisional advanced rate. First, the inlet side rolling roll 9 of the provisional advance rate is
In order to obtain the tentative advance rate of A, tension gauges 8 are placed before and after the inlet roll 9A, and the measured values are calculated as t.
Let r 1, tbl. In addition, the measured value of the gamma ray thickness meter 5 placed in front of the nine rolling rolls on the entrance side is defined as H1. Further, the expected value fol of the advance rate of the inlet side rolling roll 9A is set in advance by the setting device 1. Here, the correction of the tentative advance rate by various actually measured values is as follows: tentative advance *<corrected value. ) can be expressed by the following formula. f
A tube = fl>1 + (at /a tr ) t ・A tr t+(a
f/afb) ・Δtl,t+ (2}f/miH
〉 1 ・ΔH1...《6〉Then, in the provisional advanced rate learning device 3, based on the calculation formula, the measurement value tf l,
Set tb1 and H1 (use iifo+ to determine the temporary advance rate f^1 of the inlet side roll roll 9A. Similarly, determine the temporary advance rate of the final stage roll 9B. First, set the tension before and after the final stage roll 9B, respectively. A total of 8 rolls are arranged, and the measured values are tr s and tbs, respectively.Furthermore, the expected value H5 of the plate thickness in front of this final stage rolling roll 9B and the expected value jos of the advance rate of this final stage rolling roll 9B are set respectively. It is set in advance in the machine 1.Here, the correction of the provisional advancement rate using various actually measured values is expressed by the following formula, similar to the inlet side rolling roll 9A, assuming that the provisional advancement rate (corrected) is f^5. It is possible to do this. Based on the calculation formula, the measurement value t
The provisional advance rate f^5 of the final stage rolling roll 9B is determined from rs, tbs, set value H5, and fOs. - Further, an X-ray thickness gauge 6 is placed behind the final rolling roll 9B, and the measured value is set as Hout. Let β be the smoothing exponent used in the learning device set in configurator 1. In addition, the rolling roll circumferential speed measured by the pulse generator 7 placed on the inlet open rolling roll 9A and the final stage rolling roll 9B is expressed as VRAI and VR^2.
Suppose that In the advanced rate correction value learning device 2, the measured value H+,
Hout, VR^1, vRA2 and the total Xfiaf^+
, f^2 and the set value β, the advanced rate correction value f3 is calculated using the following two equations. fa +=(10f^t)/(1+f^5)X(H*
/Hout) X (VRAI/VRA5) =<8) fcx1=f
at+β(fα+fa+)...<9) Here, fα゛1 is the advanced rate correction value of the previous process obtained by the process of this advanced rate correction value learning device 2 performed at regular intervals. As shown in equation (9), the deviation between the currently determined advanced rate correction value fα 1 and the previous advanced rate correction value fα'1 is determined by the weighting ratio of the smoothing index β.
It is accumulated to t. In general, it is experimentally known that the advance rate in a continuous rolling mill will be different depending on the product thickness and material of the strip being rolled, even under the same rolling conditions. Therefore, this advance rate correction value fll1 is stored in the material-by-material advance rate correction value table memory 20 as data of the advance rate correction value fα1 for each product of each material and plate thickness. When the material or thickness of the strip being rolled in a continuous rolling mill is changed, first, the advance rate correction value fα1 of the strip that has been processed up to that point is corrected for each material in order to update the data. Write data into the corresponding material and plate thickness portion of the value table memory 20, and then read data corresponding to the material and plate thickness of the strip to be processed next from the material-by-material advance rate correction value table memory 20. The operation of the advanced rate learning method in the second embodiment is as described above. hout=(1+f^t)/(1+f^s)x, obtained by calculation based on the following formula:
(V R AT / V R^5)X (H1/
(10) In the second example of measuring the thickness of this rolled strip, the calculated value ho of the strip thickness is
Let ut be the final plate thickness measurement. This equation (10) corresponds to the equation (5) in the first embodiment for calculating the plate thickness, but when compared with the equation (4) above, equation (10) has the value 1/fa1. A term for advanced rate correction value has been added. In the second embodiment, this advance rate correction value is calculated based on the advance rate of a plurality of rolling rolls, etc. for each product that differs depending on the material and plate thickness of the strip, and is used when calculating the plate thickness. By doing this, we aim to improve the accuracy and reliability of plate thickness measurements. Note that this first embodiment is a simplified version of the configuration of the second embodiment for explaining the content of claim 1;
The working example and this second example are originally the same. In addition, Fig. 3 shows a calculation table of the experimental data for the outlet end plate thickness [hout] calculated without correcting the advance rate using a learning device, and Fig. 4 shows the calculated value hout obtained in the experiment.
The actual measured value of the plate thickness of the corresponding part of u t and coil 33 is shown, but the difference between this calculated value and the actual measured value is within the product tolerance ±0
．． We were able to keep it sufficiently small compared to 6%.

【Effect of the invention】

As explained above, according to the present invention, by mutually checking the measured values of two or more thickness gauges such as X-ray thickness gauges and radiation thickness gauges that are not installed at the same position, the thickness of the rolled strip can be improved. We were able to improve the reliability of measurements. or,
When measuring plate thickness, measure the rolling speed by measuring the rotational speed of the rolling roll, which has less slip than the backup roll, and learn the advance rate of the rolling roll at any time even if rolling conditions such as tension change. As the rolling speed can now be measured more accurately, the accuracy of thickness measurements of rolled strips has been improved. In this way, the ability to improve the reliability and accuracy of product thickness measurements in the manufacture of strips has great industrial significance.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a plate thickness measuring method according to a first embodiment of the present invention, Fig. 2 is a block diagram of a plate thickness measuring method according to a second embodiment of the present invention, and Fig. 3 is a block diagram of a plate thickness measuring method according to a second embodiment of the present invention. Calculation table of experimental data of plate thickness measurement using the learning device according to the example; FIG. FIG. 5 is an explanatory diagram of the conventional technology. 1... Setting device, 2... Advanced rate correction value learning device, 3... Temporary advanced rate learning device, 5... γ-ray thickness meter, 6... X-ray thickness meter, 7... Pulse generator, 8... Tension meter, 9A... Inlet measurement rolling roll, 9B... Final stage rolling roll, 10... Winding reel, 11... Deflector roll, 12... Comparison calculation 13...Alarm generator, 14...Display device, 15...Indicator, 16...Plate thickness calculator, 17...Calculation timing setter, 18...Strip plate (covered plate) workpiece), 20... Material-by-material advanced rate correction value table memory, 21.
... Outlet end plate thickness calculator, 22... Plate thickness measurement value evaluator, 23... Process computer, 33... Coil. 2nd figure 33 3rd figure 4; JJ review 5th figure 31 Q1

Claims (2)

[Claims] (1) In the method for measuring the thickness of a strip being rolled in a continuous rolling mill, the first strip thickness is directly measured in the vicinity of the first rolling roll, and the first strip thickness is directly measured in the vicinity of the first rolling roll. measuring a circumferential speed of a rolling roll, a second rolling roll different from the first rolling roll;
The circumferential speed of the second rolling roll is measured, and using a plate thickness conversion formula based on the constant mass flow law, the first plate thickness and the measured value of the circumferential rolling roll speed, the advance rate of the first rolling roll, and the A method for measuring the thickness of a rolled strip, comprising calculating the thickness at the exit side of the second rolling roll based on the measured value of the circumferential speed of the second rolling roll and the advance rate of the second rolling roll. (2) In a method for improving the accuracy of the advance rate in the method of measuring the thickness of a strip rolled in a continuous rolling mill, the forward tension of the strip is measured in front of the rolling roll, and the tension of the strip is measured behind the rolling roll. Measure the rear tension of the plate and measure the inlet thickness of the strip in front of the rolling roll, or
Or, use a preset plate thickness value as the entrance plate thickness, calculate and learn using the front tension, the rear tension, and the entrance plate thickness to obtain a provisional advancement rate, and obtain the provisional advancement rate. is carried out on a plurality of rolling rolls, obtaining a plurality of provisional advancement rates, measuring the circumferential speed of each of the plurality of rolling rolls, and determining the provisional advancement rate, the inlet plate thickness, and the rolling roll of each of the plurality of rolling rolls. Rolling characterized by calculating and learning from the circumferential speed to obtain an advancement rate correction value, determining the advancement rate from the provisional advancement rate and the advancement rate correction value, and calculating the plate thickness using the advancement rate. How to measure the thickness of a strip.