KR19980049292A - Deformation measuring device of high temperature hot rolled steel sheet and its method - Google Patents

Abstract

The present invention relates to an on-line measuring device and method for the transformation of high temperature steel, and by measuring only the maximum value of the measured voltage signal such as unit time, the transformation rate can be measured more easily, as well as lift It is an object of the present invention to provide an apparatus and method for more accurately measuring the amount of transformation of a hot rolled steel sheet by removing an error caused by a change in the off.

The present invention is a device for measuring the amount of transformation of the hot rolled steel sheet, in the cooling facility of the hot rolled steel sheet is installed at a lower portion with a constant distance from the hot hot rolled steel sheet 11 passing through the cooling facility to generate a magnetic flux by a constant current The magnetic flux generator 31, the AC excitation device 32 for supplying a constant current to the magnetic flux generator 31, and the organic voltage measuring device 33 for measuring the magnetic flux induced from the magnetic flux generator 32 as a voltage value. Magnetic flux measuring device 30 consisting of; A unit time input unit 40 for obtaining a unit time for measuring the amount of transformation from the distance between the moving speed of the hot rolled sheet and the stand of the finishing mill; A maximum voltage measuring device (50) for obtaining a maximum voltage value measured by the organic voltage measuring device (33) during a unit time obtained from a unit time input device (40); And a calculation device 60 for calculating a transformation amount based on the maximum voltage measured by the maximum voltage measuring device 50, and a measuring method of the transformation amount of the hot rolled steel sheet.

Description

Deformation measuring device of high temperature hot rolled steel sheet and its method

Fig. 1: Configuration diagram of conventional on-line measuring device for transformation amount and flatness of steel

2 is a schematic diagram of a conventional on-line measuring device for the amount of transformation and flatness of other steels

Fig. 3: Graph showing voltage change according to liftoff change by measurement frequency

4 is a configuration diagram of the apparatus for measuring the amount of transformation of the hot rolled steel sheet according to the present invention

5 is a schematic diagram for explaining the principle of the real-time lift-off compensation in the measurement of the transformation amount of the present invention

* Description of the symbols for the main parts of the drawings *

11: hot rolled steel sheet 31: flux generator

32: AC excitation device 33: organic voltage meter

40: unit time input unit 50: maximum voltage meter

60: computing device

The present invention relates to an on-line measuring apparatus and method for transforming high-temperature steel, and more particularly, to transformation of hot-rolled steel sheet by using a maximum value of a predetermined unit time in an organic voltage signal measured by a magnetic flux measuring apparatus of a hot-rolled steel sheet. An apparatus for measuring a quantity and a method thereof.

As a means of manufacturing high-strength steel in the steelmaking process, the transformation of transformation structure due to controlled cooling is used at the end of the hot rolling process. In the case of the metamorphosis protection technology, a device for measuring the real-time transformation behavior of steel is essential. In this regard, the invention relating to the measurement of the amount of transformation using a physical phenomenon that changes from the γ phase (ferromagnetic: magnetic transmittance, μ = 1) of the steel to the α phase (ferromagnetic: magnetic transmittance, μ1) is disclosed in Korean Patent Publication No. 90- 5481 and 30070.

In Publication No. 90-5481, as shown in FIG. 1, the magnetic flux 19 is generated by using the AC excitation device 17 and the first excitation coil 12 in the steel 11 to be measured, By using the first detection coil 13 and the second detection coil 14, the magnetic flux to be bridged is detected as a change in the induced voltage, respectively. When the γ-α transformation of the steel material 11 occurs, or when the distance L (hereinafter, referred to as a lift-off distance) between the steel material 11 and the coil changes, the magnetic field strength of the steel material 11 changes. The intensity of the magnetic flux 19 passing through each of the detection coils 13 and 14 deviates from the initial state and is measured by the induced voltage of the detection signals 15 and 16. The first and second induced voltage signals measured by the first and second detection coils 13 and 14 are processed by the calculating device 18 to calculate the amount of transformation and the flatness.

However, the method disclosed in the publication No. 90-5481 has a problem that it is difficult to accurately detect the amount of transformation because it does not consider the change of the impedance according to the change of the lift off distance of the steel.

On the other hand, in Publication No. 30070, as shown in FIG. 2, the transformation amount and flatness of the steel material 11 using two alternating current excitation devices 21 and 22 that are the same as the high frequency and low frequency AC power supplies. At the same time, these devices use two systems with different frequencies but detect the induced voltage due to the change of lift-off resulting from the vibration of the hot rolled steel sheet and the induced voltage signal due to the change of the transformation rate of the hot rolled steel sheet. Due to the simultaneous measurement at the coil, the calculation of the amount of transformation dependent on a complex mathematical model has limitations in measurement time delay and accuracy. In FIG. 2, the twenty-five symbols 23 and 24 denote excitation coils, 25 detection coils, 26 and 27 band pass filters, 28 arithmetic units, and 20 magnetic fluxes. FIG. 3 shows the variation of the induced voltage signal according to the lift-off when the 100% transformation test specimen was measured by the method shown in FIG. 1 and FIG. When the lift-off (distance between the hot rolled sheet and the measuring sensor) changes from 0 mm to 50 mm, the signal of the induced induced voltage shows a decreasing change. Especially when the lift-off is smaller than 15 mm, it decreases to a large value. The magnitude of the signal also varies depending on the frequency of the constant current of the AC excitation device that supplies the constant current. In the hot rolling process, the hot rolled steel sheet is shaken during the cooling process to cause a change in the lift-off, resulting in a change in the organic voltage signal as shown in FIG. 3. When the amount of deformation of the lift-off and hot-rolled steel sheet changes at the same time, there is a problem in that the measurement time delay and accuracy are inferior because the solution must be solved based on a complicated mathematical model.

Accordingly, the present inventors have conducted research and experiments to solve the problems of the conventional method described above, and have proposed the present invention based on the results, and the present invention obtains only the maximum value of the measured voltage signal during the unit time and transforms it. By measuring the rate, it is possible to provide a device and a method for measuring the amount of transformation of the hot-rolled steel sheet more accurately by removing the error caused by the change of the lift-off as well as measuring the amount of transformation more simply. There is a purpose.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is a method for measuring the amount of transformation of the hot rolled steel sheet, in the cooling equipment of the hot-rolled steel sheet is installed at a lower distance from the hot-rolled steel sheet passing a cooling facility at a certain distance to generate a magnetic flux by a constant current A magnetic flux measuring device comprising a stimulating excitation device for supplying a constant current to the magnetic flux generating device, and an organic voltage measuring device for measuring a magnetic flux induced from the magnetic flux generating device with a voltage value; A unit time input unit for obtaining a unit time of transformation amount measurement from a distance between a moving speed of a hot rolled sheet and a stand of a finishing mill; A maximum voltage measuring device for obtaining a maximum voltage value measured by the organic voltage measuring device during a unit time obtained from a unit time input device; And it relates to a transformation amount measuring device of the hot rolled steel sheet comprising a calculation device for calculating the transformation amount by the maximum voltage measured by the maximum voltage measuring device.

In addition, the present invention provides a method for measuring the transformation amount of hot rolled steel sheet, the method comprising: obtaining a correlation between the maximum low pressure value and the transformation amount of the hot rolled steel sheet; Obtaining a correlation between the maximum voltage value and the transformation amount of the hot rolled steel sheet; Generating a constant magnetic flux to be interfered by the hot-rolled steel sheet to continuously measure the induced voltage (V) induced by the magnetic flux when the hot-rolled steel sheet moves; Obtaining a minimum unit time T of metamorphic measurement as shown in Equation 1 below;

(Ls: distance between the rolling mill stand, V: moving speed of hot rolled steel sheet)

Obtaining a maximum voltage value within the minimum unit time T or the time range obtained above from the induced voltage change according to the measured time; And calculating a transformation amount by a correlation between the maximum voltage value and the transformation amount using the maximum voltage value obtained above.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

As shown in FIG. 4, the apparatus for measuring the amount of transformation of the hot rolled steel sheet according to the present invention includes a magnetic flux measuring device 30, a unit time input device 40, a maximum voltage measuring device 50, and a calculation device 60. do.

The magnetic flux measuring device 30 is a magnetic flux generating device 31 for generating a magnetic flux by a constant current installed below the hot rolled steel sheet 11 passing a cooling facility at a predetermined distance (L: lift-off distance), magnetic flux AC excitation device 32 for supplying a constant current to the generator 31, and an organic voltage measuring device 33 for measuring the magnetic flux induced from the magnetic flux generator 31 by a voltage value.

The magnetic flux generating device 31 is electrically connected to the AC excitation device 32 to receive a constant current from the AC excitation device 32 to generate a magnetic flux 19 of the excitation coil 311 and the hot rolled steel sheet 11. It consists of a detection coil 312 for detecting a change in magnetic flux varying by the amount of transformation and the lift-off (L).

The frequency of the constant current supplied from the AC excitation device 32 is preferably about 10 Hz to 10 kHz.

The organic voltage measuring device 33 is electrically connected to the detection coil 312 to measure the magnetic flux induced by a voltage value, and is electrically connected to the maximum voltage measuring device 41.

The unit time input unit 40 is configured to measure the amount of transformation from the distance between the moving speed of the hot rolled steel sheet and the stand of the finishing mill, and the maximum voltage measuring unit 50 measures the unit time during the unit time obtained from the unit time input unit 40. The maximum voltage value measured by the induced voltage measuring device 33 is configured, and is configured to send the calculated maximum voltage value electrically connected to the calculating device 60 to the calculating device 60.

The calculating device 60 is configured to obtain the amount of transformation using the maximum voltage value measured from the maximum voltage measuring device 50.

Hereinafter, the method of measuring the transformation amount of a hot rolled steel plate using the transformation amount measuring apparatus of this invention is demonstrated.

In order to measure the transformation amount of the hot-rolled steel sheet according to the present invention, a correlation between the maximum voltage value and the transformation amount should be obtained for various hot-rolled steel sheets to be measured, and this correlation can be obtained using existing data.

Next, a constant magnetic flux is generated to be interfered by the hot rolled steel sheet, and the induced voltage induced by the magnetic flux during the movement of the hot rolled steel sheet is continuously measured.

The induced voltage is measured using the magnetic flux measuring device 30 shown in FIG.

Next, the unit time input unit 40 calculates the minimum unit time T of the transformation amount measurement as shown in the following equation (1), and then

(Ls: distance between the rolling mill stand, V: moving speed of hot rolled steel sheet)

In the maximum voltage measuring device 50, the maximum voltage value within the minimum unit time T or the time range obtained above is obtained from the induced voltage change according to the time measured above, and then the arithmetic unit 60 By using the maximum voltage value obtained above, the transformation amount is calculated by the correlation between the maximum voltage value and the transformation amount, which will be described in detail below.

The unit time sent from the unit time input unit 40 to the maximum voltage measuring unit 50 is a period of vibration of the high temperature hot rolled steel sheet passing through the cooling facility as a unit time. Vibration of the hot rolled steel sheet passing through the cooling facility is a standing wave formed between each stand of the finishing mill is a vibration in the cooling section. Therefore, the wavelength of the standing wave formed between each stand of the filament rolling is twice the distance between the stands.

λ = 2Ls... … … … … (1a)

Is the wavelength of the standing wave formed between each stand, and Ls is the distance between the finishing mill stands. High-temperature hot-rolled steel sheet passing through the cooling facility proceeds with the same wavelength as the standing wave formed between each stand proceeds. Therefore, the oscillation period of the hot rolled steel sheet is obtained by dividing the moving speed (V) of the hot rolled sheet by the wavelength of the standing wave. If the oscillation period is the minimum unit time (T) for measuring the transformation, it is expressed as Equation (1) below. Can be.

This unit time is the time that the hot rolled steel sheet can be lowered to the minimum position once during the transfer of the hot rolled steel sheet. If the trial time longer than T is the unit time, the hot rolled steel sheet will be lowered more than once to the minimum position, resulting in accurate measurement. It can come down, resulting in incorrect measurement results. When the unit time is set to T in FIG. 4, the action of the device has a form of signal processing as shown in FIG. In FIG. 5, A indicates that the hot rolled steel sheet is divided by the width in the longitudinal direction by a distance that is twice the distance Ls between the finishing mill stands. As in Equation (1), this distance, 2Ls, is the distance corresponding to the time T. In FIG. 5, B is a signal detected by the organic voltage measuring device 33 of FIG. 4 installed under the hot rolled steel sheet of the hot rolling process water cooling section. Even if the signal measured by the induced voltage measuring device 33 has the same transformation rate, the measured signal is changed as shown in FIG. That is, as shown in FIG. 3, when the liftoff is large, a small induced voltage value is shown, and when the liftoff is small, a large induced voltage value is represented. In FIG. 5, C shows the signal of the unit time input when T is the unit time. In FIG. 5, D shows a process in which the signal is processed in the maximum voltage meter 50. The maximum voltage meter 50 is deactivated while the signal of the unit time input device (C in FIG. 5) is at 1 (ON). The maximum value of the signal of the voltage measuring device (B of FIG. 5) is obtained, and when the signal of the unit time input device (C of FIG. 5) becomes 0 (OFF), the maximum value of the measuring signal is sent to the computing device. Therefore, the signal measured by the maximum voltage measuring device 50 is a signal when the lift-off of the hot rolled steel sheet is the smallest, and this maximum voltage is sent to the calculating device 60 to change the value of the transformation amount as shown in E of FIG. The maximum voltage is used to calculate. E of FIG. 5 shows that the maximum amount of induced voltage, h, is measured in the third region shown in A of FIG. When measured by this series of processes, the transformation rate measuring device shown in FIG. 4 is installed at a constant distance from the hot rolled steel sheet under the cooling section of the hot rolled steel sheet, and the transformation rate can be measured by removing the influence of the vibration of the hot rolled steel sheet. Can be.

Although it depends on the measurement frequency, when the transformation rate is measured by the transformation rate measuring device installed at about 600 Hz and the lift-off 10 mm to 15 mm, the first and second liftoff compensation methods of FIG. It can be seen from the results of the experiment of FIG. 3 that the accuracy of the transformation rate measurement of about 11% to 8% can be achieved compared to the conventional transformation rate measuring apparatus and method of FIG. 2.

As described above, the present invention has a simple measuring device and method compared to the conventional device and method, and even in the signal processing method, the conventional measuring device has a complex mathematical model for the effect of the vibration during transfer of the hot-rolled steel sheet. Although the accuracy is limited by compensating at, the present invention calculates the transformation rate by calculating only the maximum value of the measured signal during the unit time, thereby eliminating the error caused by the change of the lift-off, thereby obtaining a more accurate transformation amount. have.

Claims (2)

In the apparatus for measuring the amount of transformation of the hot rolled steel sheet, in the cooling equipment of the hot-rolled steel sheet, a magnetic flux generation that is installed at a lower distance from the high-temperature hot-rolled steel sheet 11 passing through the cooling equipment to generate magnetic flux by constant current. The device 31, the AC excitation device 32 for supplying a constant current to the magnetic flux generator 31, and the organic voltage measuring device 33 for measuring the magnetic flux induced from the magnetic flux generator 31 as a voltage value A magnetic flux measuring device 30; A unit time input unit 40 for obtaining a unit time of transformation amount measurement from the distance between the moving speed of the hot rolled steel sheet and the distance between the stand of the finishing mill; A maximum voltage measuring device (50) for obtaining a maximum voltage value measured by the organic voltage measuring device (33) during a unit time obtained from a unit time input device (40); And a calculation unit (60) for calculating a transformation amount by the maximum voltage measured by the maximum voltage measuring device (50). A method of measuring a transformation amount of a hot rolled steel sheet, the method comprising: obtaining a correlation between a maximum voltage value and a transformation amount of a hot rolled steel sheet; Generating a constant magnetic flux to be interfered by the hot-rolled steel sheet to continuously measure the organic low pressure (V) induced by the magnetic flux when the hot-rolled steel sheet moves; Obtaining a minimum unit time T of metamorphic measurement as shown in Equation 1 below; (Ls: distance between the rolling mill stand, V: moving speed of hot rolled steel sheet) Obtaining a maximum voltage value within the minimum unit time T or the time range obtained above from the induced voltage change according to the measured time; And And calculating a transformation amount by a correlation between the maximum voltage value and the transformation amount by using the obtained maximum voltage value.