JPS58221105A - Method for measuring thickness of steel plate - Google Patents

Abstract

PURPOSE:To obtain the exact thickness of a steel plate and to improve the prediction of the position where the thickness changes and the responsiveness of the timing for changing the correction rate thereof by correcting the deviation between the theoretical characteristic curve of the dosage of transmitted radiation for the thickness of the steel plate and the actually measured characteristic curve. CONSTITUTION:The thickness in the end part of a thick-rolled steel plate 9 introduced into a rolling mill 1 is predicted with a calculator 19 for predicting thickness of a gage meter type or a setting part 20 for rolling schedule in a computer 13, by which the thickness and the correction rate of the thickness are determined. The thickness is determined from the dosage of transmitted radiation measured with a radiation thickness gage 10 and is compared with the predicted thickness. If the difference is larger than the value in a permissible range, the thickness is substituted in the characteristic curve and a fresh correction rate for the thickness is determined. If the thickness is not determined in the stage of predicating the thickness, the exact thickness obtd. by using a prescribed theoretical equation is outputted to a control part for rolling. On the other hand, if the value compared with the predicted thickness is within the value in a permissible range, the measured thickness is outputted as an exact thickness to the control part for rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for measuring the thickness of a steel plate using radiation during rolling, by comparing a theoretical characteristic curve of the transmitted radiation dose with respect to the thickness of the steel plate and an actually measured characteristic curve. This is related to a method for measuring the thickness of a steel plate by correcting this deviation to obtain an accurate plate thickness.In the rolling process, the thickness of the steel plate is successively measured during rolling. Feedback to the rolling control mechanism is important for accuracy control, and the following theoretical formula i is used as a means of measuring plate thickness.
The radiation transmission amount method according to the method according to 1) is widely used.

11゜T:□・ln-・・・・・・・・・tt1μmρ
However, as shown in Figure 1, there is a discrepancy between the theoretical characteristics and the actually measured characteristics of the relationship between the plate thickness and the amount of transmitted radiation.
When calculating the plate thickness by substituting ff1iiizxt-s into the theoretical formula ill, the value becomes tn, and there will be an error of α between it and the actual plate thickness tX. Therefore, in actual operation, It is necessary to appropriately correct this amount of deviation, which varies depending on the thickness of the 1U11 steel plate.
An error in the plate thickness prediction to determine the above correction amount, or an unforeseen situation where the plate thickness cannot be predicted, will cause a major problem in terms of plate thickness measurement accuracy. In order to improve rolling accuracy, the sound emission may be changed.) When measuring plate thickness, there are major difficulties in predicting the point of change in plate thickness and determining the timing of changing the plate thickness correction amount. there were. This was the conventional situation.

In view of the above-mentioned drawbacks, the present invention has completely improved and eliminated them, and the deviation between the theoretical characteristic curve of the transmitted radiation dose with respect to the thickness of the steel plate and the actually measured characteristic curve (corrected plate thickness) has been solved in advance. The plate thickness correction amount t1 is determined by the predicted plate thickness obtained by the rolling schedule or gauge meter method or the theoretically measured plate thickness. It is an object of the present invention to provide a method for measuring the thickness of a copper plate.

The method of the present invention will be explained below based on the embodiments shown in the drawings.

FIG. 2 is a system diagram showing the entire apparatus to which the method of the present invention is applied. In the same figure, 1 is a rolling mill.

2.2 is an upper and lower work roll, 3, 3Vi is an upper and lower backup roll, 4 is a hydraulic cylinder, 5 is a magnescale for oil column cover loading provided in the hydraulic cylinder 4, 6 is a load cell for detecting the rolling load Pi, 7 is a reduction screw,
Reference numeral 8 denotes a position detector for detecting the entire position of the lowering screw 7.

A rolling material (steel plate) 9 is caught between the work rolls 2 and 2 of the rolling mill 1 from the left side of the figure, is rolled, and exits to the right side. A radiation source 11 serving as a radiation thickness gauge 10 and a transmitted radiation dose detector 12 arranged therebetween are placed directly in front of the work rolls 2.2 and 7j, with a steel plate 9 interposed therebetween.

13 is a calculator that controls the rolling mill 1 and the radiation thickness gauge 10i. The calculator 13 includes a plate thickness correction amount calculator 14 that determines a correction amount ΔTt for the plate thickness determined by the gauge meter method, rolling schedule, or measured plate thickness;
An accurate plate is obtained by adding the correction IAT obtained by the plate thickness correction amount calculator 14 to the initial plate thickness Tar tJIl obtained by the plate thickness measurement calculator 15 by detecting the transmitted radiation electrician Tt. It has 16 board thickness calculators for calculating thickness.

When predicting plate thickness using the gauge meter method, when predicting plate thickness using the device 19, first, the signal @a from the position detector 8 that detects the position of the reduction screw 7 and the oil column telegraph 8b of the Magnescale 5 are used. From this, the set opening degree S between the work rolls 2.2 is determined by the roll setting laparotomy calculator 17. seek. Then, the load signal P of the load cell 6 and the mill tonality calculator 1
The mill stiffness is determined from the mill constant M given by 8, and from the input ei and the signal, the predicted plate thickness ty is calculated.

ty=40i ・・・・・・・・・・・・(2) Seek a meeting. Further, when predicting the plate thickness based on the rolling schedule, it is sufficient to take out tj set in advance in the rolling schedule setting section 20.

Furthermore, when determining the plate thickness using the transmitted radiation iIT, it can be determined by substituting it into the above-mentioned ITkifJ equation (1).

Next, referring mainly to the flowchart shown in FIG. 3, a specific method for measuring plate thickness according to the present invention will be explained.

As far as possible, for the tip end src of the thick rolled steel plate 9, the predicted plate thickness ty or 1jtj is pre-assigned using the gauge meter type plate thickness prediction calculator 19 or the rolling schedule V setting unit 20, and these plate thicknesses ty or tj are calculated. If it is possible to determine the plate thickness correction amount ΔTO for these plate thicknesses, the plate thickness correction amount ΔTO is determined. This is because, as shown in No. 11N, the value of the transmitted radiation for the plate thickness 1 is different between the theoretical value and the measured value, so the plate thickness error α (required plate thickness correction)' for this difference is shown in It may be determined in advance as shown, and then obtained from this table or by calculation. Then, the plate thickness T is determined by substituting it into the transmission radiation thickness measurement formula f1) measured by the radiation thickness meter lO. Next, this plate thickness Ttilifl is compared with the predicted plate thickness ty or Fitj, and if the difference is greater than the value d indicating the tF valley range, it is determined that the plate thickness prediction is incorrect, and the plate thickness T A new plate thickness correction -AT1 is determined by substituting into the characteristic diagram shown in FIG. 4 or by ii calculation. Therefore, in the case where the predicted plate thickness tj or tj cannot be obtained due to a failure of the load cell 6 at the step of plate thickness prediction described in III, the steel plate 9 is at the measurement position f11 of the radiation thickness gauge 10.
Substitute the transmitted radiation at amount IT't into the equation (1) to find the plate thickness T, and determine the plate thickness correction amount -T from this plate thickness T in the same manner as described in 110. In this case, there is a one-step delay in meaningful thickness measurements at the center compared to when the thickness can be predicted more or less accurately. The thus obtained 7jT+ΔT, ij is output to the rolling control section as an accurate sheet thickness. On the other hand, the child side plate thickness ty or t
If the comparison value between j and T is equal to or smaller than d, which indicates the allowable range, it means that the plate thickness predetermined value 6i1J is correct, and the measurement plate p#T0ATo is sent to the rolling control unit as the accurate plate thickness. Output.

By the way, when the plate thickness measurement of the steel plate 9 is carried out continuously, the plate thickness 'I' [sequentially determined by the (1+ formula) is calculated from the transmitted radiation electrician T during the continuous measurement, and the plate thickness 1 and the child side plate are If the difference between the thickness ty or if tj or T is larger than the value 8 indicating the allowable range, the plate thickness correction amount ΔT8 of yrfc is determined from the plate thickness in the above-mentioned manner, and is calculated as d+ΔT.

is output to the rolling control section. If the above difference is equal to or smaller than θ, the plate thickness T' and the plate thickness correction cover ΔTo or ATl for the predicted plate thickness tj or TJ or T
f plus plate thickness, i.e. (TI+ΔT, or AT,
) is accurate and is output to the rolling control section. If the measurement is still continuing, the process returns to the block of the flowchart for determining the plate thickness T' by the transmitting radiation electrician T that is currently being continued, and the above measurement operation is repeated to block light. however,
From the second time onwards, the plate thickness correction amount is determined by comparing the plate thickness according to the previous theoretical formula and the measured plate thickness obtained from the transmitted radiation dose measurement T. If the process is not in 0 continuation [1jEND]. The above is the method for measuring the plate thickness in one bus, and if a plurality of round trip buses are to be carried out, the above operation may be repeated.

As explained above, in the present invention, since there is a discrepancy between the theoretical characteristic curve of the transmitted radiation dose with respect to the thickness of the steel plate and the characteristic curve measured from the sky, correction is made by calculating the relationship between the above two characteristic curves by the difference i. Since we determined the exact plate thickness, the obtained plate thickness is very accurate, and automatic plate thickness control (
Accuracy control 1 is excellent, such as Go). Furthermore, even if the plate thickness changes midway through, the prediction of the position of plate thickness change and the timing of changing the correction amount are automatically determined, resulting in excellent responsiveness.

[Brief explanation of the drawing]

Figure 1 is a drawing showing the relationship between plate thickness and transmitted radiation dose, Figure 2
Fig. 3 is a system diagram showing the entire apparatus to which the method of the present invention is applied, Fig. 3 is a flowchart of the apparatus shown in Fig. 2, and Fig. 4 is a drawing showing the relationship between the plate thickness correction amount and the predicted or 111 constant plate thickness. It is. 9... Steel plate 10... Radiation thickness needle special liver applicant
Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney Toshihiko Uchida Figure 1 JP-A-58-221105 (4) Procedural Amendment (Voluntary) August 6, 1980 1, 11 (Designation D Special IT F) 7- 10512
No. 7, No. 2, Title of the invention Steel plate thickness measurement method 3, Relationship to the amended case Address of patent applicant 5-15 Kitahama, Higashi-ku, Osaka Name
(211) Sumitomo Metal Industries, Ltd. Representative Director Nori Kumagai 4, Agent 5, Need for amendment Voluntary amendment 6, Subject of amendment [Details of the invention] Column 7, Contents of amendment (l) Amend and correct the "Detailed Description of the Invention" column. 8. No list of attached documents 21 2 6

Claims (1)

[Claims] l. When measuring the plate thickness using radiation during rolling of a steel plate, the theoretical characteristic curve for the same radiation dose can be determined from the theoretical characteristic curve of the amount of transmitted radiation against the thickness of the steel plate and the actually measured characteristic curve. The relationship between the plate thickness on the curve and the plate thickness on the upper characteristic curve is determined, and the plate thickness is calculated using a theoretical formula based on the actual amount of transmitted radiation, and the predicted plate thickness obtained using the rolling schedule or gauge meter method, etc.
The predicted plate thickness or the plate thickness obtained by the theoretical formula is used as the theoretical plate thickness, and this is applied to the plate thickness according to both of the above characteristic curves, and the obtained t value is added as the thickness correction amount to determine the accurate plate thickness of the steel plate. A method for measuring the thickness of a steel plate.