KR100299445B1 - Apparatus and method for measuring transformation amount of high temperature hot-rolled steel plate - Google Patents

Abstract

PURPOSE: An apparatus and method is provided to achieve improved accuracy of measurement by preventing errors caused due to the change of lift-off. CONSTITUTION: An apparatus comprises a flux measuring unit(30) including a flux generator(31) installed underneath a high temperature hot-rolled steel plate(11), and which generates magnetic flux by a static current, an alternating exciter(32) for supplying static current to the flux generator, and a voltage measuring device(33) for measuring, in a voltage value, the flux applied from the flux generator; a unit time input unit(40) for obtaining unit time by using the movement speed of the hot-rolled steel plate and the transformation amount of the distance between stands of a roller; a maximum voltage measuring unit(50) for measuring maximum voltage for voltages measured by the voltage measuring device, during the unit time obtained by the unit time input unit; and an arithmetic operation unit(60) for calculating transformation amount by using the maximum voltage measured by the maximum voltage measuring unit.

Description

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

1 is a block diagram of a conventional device for measuring the amount of transformation and flatness of steel.

2 is a block diagram of a conventional on-line measuring device for the amount of transformation and flatness of other steel materials.

3: A graph showing the voltage change according to the lift-off change for each measurement frequency.

4 is a block diagram of a device for measuring the amount of transformation of a 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 transformation amount measurement of the present invention.

<Description of the symbols for the main parts of the drawings>

11: hot rolled steel sheet 31: magnetic flux generating device

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 for producing high strength steel in the steelmaking process, a technique for strengthening the transformation structure by controlled cooling at the end of the hot rolling process is used. In this metamorphic reinforcement technology, a device for measuring the real-time metamorphic behavior of steel is essential. In this regard, the invention regarding the measurement of the transformation amount using the physical phenomenon that changes from the γ phase (ferromagnetic: magnetic permeability, μ = 1) of the steel to the α phase (ferromagnetic: magnetic permeability, μ >> 1) Nos. 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?-? Transformation of the steel material 11 occurs or the distance L between the steel material 11 and the coil (hereinafter referred to as "lift-off distance") changes, the magnetic field strength of the steel material 11 changes. This happens and the intensity of the magnetic flux 19 passing through each of the detection coils 13 and 14 is out of the initial state and 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 above-mentioned 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 the notification 30070, as shown in FIG. 2, the transformation amount and flatness of the steel material 11 using the same two AC excitation devices 21 and 22 with the same high frequency and low frequency AC power supply. In this system, two systems with different frequencies are used, but the induced voltage signal due to the change of lift-off due to the vibration of the hot-rolled steel sheet and the induced voltage signal due to the transformation rate of the hot-rolled steel sheet Since it is measured at the same time as the detection coil, the calculation of the transformation amount based on the complex mathematical model has a limitation in measurement time delay and accuracy. In FIG. 2, reference numerals 23 and 24 denote excitation coils, 25 detection coils, 26 and 27 band pass filters, 28 arithmetic units, and 29 magnetic fluxes.

FIG. 3 shows the variation of the induced voltage signal according to the lift-off change when the 100% transformation test piece is measured by the method shown in FIGS. 1 and 2. When the lift-off (distance between the hot rolled sheet and the measuring sensor) changes from 0 mm to 50 mm, the measured signal of the 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. When shaking during the cooling process of the hot-rolled steel sheet in the hot-rolling process, a change in the lift-off occurs and a change in the organic voltage signal as shown in FIG. 3 occurs. When the amount of deformation of the lift-off and hot-rolled steel sheet is changed at the same time, there is a problem in that measurement time delay and accuracy are inferior because it has to be solved based on a complicated mathematical model.

Accordingly, the present inventors conducted research and experiments to solve the problems of the conventional method, and proposed the present invention based on the results. The present invention obtains only the maximum value of the measured voltage signal during the unit time, and the transformation rate. In order 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 this.

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 an alternating current excitation device for supplying a constant current to the magnetic flux generating device, and an organic voltage meter 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 the transformation amount measurement from the distance between the moving speed of the hot rolled steel sheet and the stand of the 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 voltage value and the transformation amount for 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, and obtaining an organic voltage change with time; Obtaining a minimum unit time T of metamorphic measurement as shown in Equation (1) below;

Where L _S is the distance between the finishing mill stands and V is the moving speed of the hot rolled steel sheet.

Obtaining the maximum voltage value within the minimum unit time T or the time range obtained above from the induced voltage change over time obtained above; 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 installed on the lower portion of the hot rolled steel sheet 11 passing through the cooling facility at a predetermined distance (L: lift-off distance) to generate magnetic flux by a constant current, 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 induced magnetic flux as a voltage value, and is electrically connected to the maximum voltage measuring device 50.

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 of the hot rolled steel sheet to be measured should be obtained, 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, and the change of the induced voltage with time is obtained.

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

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

Where L _S is the distance between the finishing mill stands and V is the moving speed of the 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 over time obtained above, and then, 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 vibration time of the high temperature hot rolled steel sheet passing through the cooling facility as a unit time. The vibration of the high temperature hot rolled steel sheet passing through the cooling facility is that the standing wave formed between each stand of the finishing mill changes to vibration in the cooling section. Therefore, the wavelength of the standing wave formed between each stand of filamentous rolling becomes twice the distance between stands.

λ = 2L _S ....... (1a)

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

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 unit time is longer than T, the hot rolled steel sheet will be lowered more than once to the minimum position. Therefore, the accurate measurement result will be obtained. However, if the unit time is shorter than T, the hot rolled steel sheet will be moved to the minimum position of the hot rolled steel sheet. It may not come down, resulting in incorrect measurement results. When the unit time is set to T in FIG. 4, the action of the apparatus has the form of signal processing as 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 L _S between the finishing mill stands. As in Equation (1), this distance, 2L _S , 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. The signal measured by the induced voltage measuring device 33 is changed as shown in FIG. 3 due to the change of the lift-off due to vibration even when the transformation rate of the hot rolled steel sheet is the same. That is, as shown in FIG. 3, when the lift-off is large, a small induced voltage value is shown, and when the lift-off 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 of processing a signal 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 instrument 50 becomes a signal when the lift-off of the hot rolled steel sheet is the smallest, and this maximum voltage is sent to the computing device 60 and the value of the transformation rate 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 apparatus of FIG. 4 and the lift-off compensation method of FIG. 5 are used, respectively. Experimental results of FIG. 3 show that the accuracy of the transformation rate measurement of 11% to 8% can be obtained 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 complicated mathematical model for the effect (change-off change) of vibration during transfer of hot-rolled steel sheet. Although the accuracy is limited due to the compensation at, the present invention calculates the transformation rate by calculating only the maximum value of the measurement 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 generating device installed at a lower portion of the hot-rolled steel sheet at a predetermined distance from the high-temperature hot rolled steel sheet 11 passing through the cooling equipment to generate magnetic flux by constant current. (31), an alternating current excitation device (32) for supplying a constant current to the magnetic flux generating device (31), and an organic voltage measuring device (33) for measuring a magnetic flux induced from the magnetic flux generating device (31) as a voltage value. 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 a hot-rolled steel sheet to continuously measure the induced voltage (V) induced by the magnetic flux when the hot-rolled steel sheet is moved to obtain a change in the induced voltage over time; Obtaining a minimum unit time T of metamorphic measurement as shown in Equation (1) below; Where L _S is the distance between the finishing mill stands and V is the moving speed of the hot rolled steel sheet. Obtaining the maximum voltage value within the minimum unit time T or the time range obtained above from the induced voltage change over time obtained above; And calculating a transformation amount by a correlation between the maximum voltage value and the transformation amount using the maximum voltage value obtained above.