JPH0847707A - Method for measuring thickness in hot rolling mill - Google Patents

Abstract

PURPOSE:To measure the thickness of a rolled stock with high accuracy without providing a thickness gage in a position adjacent to a rolling mill by providing sheet speedometers respectively in the vicinity of the thickness gage and on the inlet and outlet sides in the vicinity of a rolling roll. CONSTITUTION:A 1st and 2nd sheet speedometers 11, 12 are provided in the positions adjacent to the rolling mill 1 and on the inlet and outlet sides of the rolling mill 1 and the thickness gage 13 is provided in the position beyond 3m from the inlet side of the rolling mill. Further, a 3rd sheet speedometer 14 is provided in the same position with this thickness gage 13 or in the position at some distance from the rolling mill l to that position. The thickness of the rolled stock P on the inlet side is measured with the thickness gage 13, the moving speed of the rolled stock is measured with the 3rd sheet speedometer 14 and the time when the part for measuring thickness of the rolled stock P reaches the rolling mill 1 is determined. From this thickness of the rolled stock P every moment on the inlet side, the speed Vi on the inlet side and speed Vo on the outlet side of the rolled stock P which is passed through the rolling mill that are measured with the 1st and 2nd sheet speedometers 11, 12, the thickness of the rolled stock P on the outlet side is estimated based on the principle of conservation of mass flow in the rolling mill 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip thickness measuring method in a hot rolling mill.

[0002]

2. Description of the Related Art In a hot rolling process of a metal sheet, in order to ensure the sheet thickness accuracy of the rolled sheet after rolling, it is necessary to measure the sheet thickness of the rolled sheet during rolling to obtain a target sheet thickness. Plate thickness control is performed to adjust the rolling amount of the rolling roll and the tension on the rolled material.

Conventionally, the most commonly used strip thickness measuring method is to install a strip thickness gauge on the exit side of a hot rolling mill and compare the strip thickness measured by this strip thickness gauge with the target strip thickness. A monitor AGC (Automatic Gauge Control) that feeds back the deviation as a control amount and increases or decreases the reduction amount and the tension to control the plate thickness to a target value.

This method has an advantage that the control accuracy is high because the thickness of the rolled material is actually measured. And, because the delay of measurement due to the time of transfer of the rolled material from the rolling mill exit to the sheet thickness measurement position adversely affects the control accuracy, the sheet thickness gauge is positioned as close as possible to the rolling roll of the rolling mill,
For example, it needs to be provided within 2 m.

Further, as another plate thickness measuring method, there is a gauge meter AGC which estimates the plate thickness of a rolled material from the information of the rolling load and the rolling position by utilizing the elasticity of the rolling mill. h0 = (P / K) + S0 + GMC, where h0: plate thickness on delivery side, S0: rolling position, P: rolling load, K: rolling mill spring, GMC: gauge meter correction term.

In the gauge meter AGC as well, it is necessary to provide a plate thickness gauge in order to guarantee the absolute value of the plate thickness, and the gauge plate thickness measurement point is measured by the plate thickness gauge. The accuracy of the gauge meter correction term is maintained by a learning method, but this learning method cannot cope with the momentary change of each pass of the gauge meter correction term and it is difficult to obtain sufficient plate thickness accuracy. Yes, the plate thickness accuracy is insufficient as compared with the gauge meter method.

From these facts, the gauge meter A is generally used.
GC is rarely used alone, Monitor A
It is required to measure the thickness of rolled material by using GC together.

[0008]

Among the hot rolling of metal sheets, rolling machines such as a hot rough rolling machine and a plate rolling machine, which have an area for rolling a particularly thick rolled material, that is, steel. Alternatively, in a reversible hot rolling mill of non-ferrous metal, which has the ability to pass a rolled material having a plate thickness of 50 mm or more, when rolling a rolled material having a plate thickness of more than 50 mm, Warpage may occur near the exit side.
Then, when the rolled material is warped, there is a possibility that the rolled material collides with a device provided near the rolling roll on the delivery side of the rolling device and damages the device. Particularly in a reversible hot rolling mill, since the traveling direction of the rolled material is reversed for each pass, both the front and rear surfaces of the mill are on the exit side, and both may collide.

On the other hand, X-ray plate thickness gauges and γ-ray plate thickness gauges are generally known as plate thickness gauges capable of accurately measuring the plate thickness of a rolled material by hot rolling of this thick plate. This thickness gauge has a launching part and a receiving part above and below the passage of the rolled material,
The thickness of the rolled material is measured by receiving the radiation emitted from the launching portion through the rolled material at the receiving portion. However, since this gamma-ray plate thickness meter contains a radioactive substance, if the emitting part and the receiving part are damaged, radiation leakage may occur and the handling thereof may be dangerous. Further, the X-ray plate thickness meter is also an expensive device, and it is not easy to repair it when it is broken.

When these plate thickness gauges are provided near the rolling rolls for performing monitor AGC, the plate thickness 50
When rolling a rolled material having a thickness of more than mm, there is a risk that the rolled material may warp near the rolling roll and the rolled material may collide with the thickness gauge provided near the rolling roll to damage the thickness gauge.
In this case, there is a possibility that radiation leakage will occur from the γ-ray plate thickness gauge as described above, and its handling will be dangerous.
There is a possibility that the broken X-ray plate thickness gauge cannot be measured.

Therefore, when rolling a rolled material of a thick plate, it is difficult to provide a plate gauge at a position within 2 m from the rolling roll, and generally at a position 10 m or more away from the rolling roll. It is provided. For this reason, when measuring the plate thickness, the problem of increasing the delay time of the control of the tip portion and the feedback control occurs, and the accuracy of the monitor AGC rather decreases, so the gauge meter AGC is unavoidably used.

Further, in recent years, in a steel plate rolling mill or the like, a plate thickness gauge has been provided at a position of 2 m to 3 m which is close to a rolling roll. In this case, protection from the warp of the rolled material is performed. In order to do so, the plate thickness gauge is installed inside a sturdy structure, and as a result, there is a drawback that the burden is large in terms of space constraints and costs.

Further, in the hot rough rolling machine for aluminum, the rolled material is particularly thick and the thickness is 400 mm to 600 mm.
Since the stroke of the guard on the inlet side and the outlet side of the rolling mill becomes long because it reaches a value of mm, it is still more difficult including the restriction on the installation of the protective structure.

Therefore, a monitor AG using a plate thickness gauge
C has been adopted only for cold-rolling and hot-rolling thin plate rolling. That is, conventionally, it is difficult to install a strip thickness gauge near the rolling mill, so that the strip thickness gauge is installed far from the rolling mill, and this strip thickness gauge is adjusted by the gauge meter strip thickness.
It was used in combination with GC.

The present invention has been made based on the above circumstances, and relates to a hot rolling mill capable of highly accurately measuring the thickness of a rolled material without installing a thickness gauge at a position close to the rolling mill. An object is to provide a plate thickness measuring method.

[0016]

[Means for Solving the Problems] In order to achieve the above-mentioned object, a method for measuring a plate thickness in a hot rolling mill of the present invention is a reversible hot rolling mill for steel or non-ferrous metal, and a plate thickness of 50 mm or more. In the rolling mill having the ability to pass the rolled material, the first and second plate speed gauges are provided at positions close to the rolling mill on the inlet side and the outlet side of the rolling mill in the pass for controlling the plate thickness, and A strip thickness gauge is provided at a position 3 m or more from the entrance side of the rolling mill, and a third strip speed meter is provided at the same position as this strip thickness gauge or at a position apart from the rolling mill with respect to this position. While measuring the entrance side plate thickness of the rolled material that is moved toward the rolling mill by the thickness gauge, the third plate speed meter measures the moving speed of the rolled material, the plate thickness measurement portion of the rolled material The time when it reaches the rolling mill, and From the inlet side plate thickness of the rolled material and the inlet side speed and the outlet side speed of the rolled material passing through the rolling mill measured by the first and second plate speed gauges, the inlet side and the outlet side of the rolling mill The outgoing side plate thickness of the rolled material is estimated based on the principle of constant mass flow on the side.

[0017]

[Function] The principle of constant mass flow is also called the principle of constant volume velocity. The volume (product of plate thickness and speed) of the rolled material entering the rolling roll from the entrance side of the rolling roll and the rolling roll from the rolling roll at the same time. The principle is that the volume (product of plate thickness and velocity) in the rolled material that emerges is equal, and this is due to the incompressibility of the metallic material.

The plate speed meter is an optical one, and is provided with a light emitting portion on either the upper side or the lower side of the passage of the rolled material to measure the speed, so that it is affected by the warp of the rolled material. It can be installed at a position close to the rolling roll without needing a strong protection facility.

Since the plate thickness gauge is provided at a position apart from the rolling roll, it is not affected by the plate warp of the rolled material. Measuring the plate thickness on the entry side with a plate thickness gauge provided at a location distant from the rolling roll is not used because the calculation of the transfer delay of the plate thickness becomes enormous and there is a problem in measurement accuracy. However, coupled with the recent improvement in the accuracy of the plate speed meter, this problem is solved by providing plate speed meters near the plate thickness gauge and at the inlet and outlet sides near the rolling rolls.

For these reasons, the conventional monitor AGC, which cannot be used in the hot rolling, cannot be adopted because a plate thickness gauge cannot be provided at a position close to a rolling roll when rolling a thick rolled material. Can be used to measure the plate thickness of the rolled material, and can be measured by a monitor AGC.

That is, according to the present invention, since the AGC using the mass flow plate thickness is applied to the rolling mill in the situation where the plate thickness gauge cannot be installed close to the rolling mill, a great effect can be obtained. Conventionally, the measurement of mass flow plate thickness itself is not applied to rolling mills under such conditions because unmeasureable parts occur at the front and back of the rolled material because the thickness gauge cannot be installed close to the rolling mill. However, according to the present invention, it is possible to perform measurement with a precision that is practical by properly selecting and arranging the sensors.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. This embodiment is intended for plate thickness control of rolled material in a hot reversible plate rolling mill. Plate thickness of rolled material is 10
The target is mm or more.

The hot reversible plate rolling mill will be described. In the figure, 1 is a pair of rolling rolls for rolling a metal sheet which is a rolled material P, 2 is a motor for rotating the rolling roll 1, 3 is a frequency generator for measuring the rotation speed of the rolling roll 1, and 4 is the rolling roll 1. A rolling down device for rolling down the rolling roll 1 driven by the rolling down device 4, a rolling down amount detecting device for measuring the rolling down amount of the rolling roll 1, and a rolling down device 6 for measuring a load applied to the rolling roll 1 by the rolling material P during rolling. A load detection device, 7 is a table roller that conveys the rolled material P located on the left side of the rolling roll 1 in the drawing, and 8 is a table roller that conveys the rolled material P that is positioned on the right side of the rolling roll 1 in the drawing.

In this rolling mill, on the one hand, the rolled material P is placed on the table roller 7 from the right side to the left side with respect to the rolling roll 1 and conveyed, passed through the rolling roll 1 and rolled, and then the table roller 8 is further rolled. On the other hand, the rolled material P is placed on the table roller 8 from the left side to the right side with respect to the rolling roll 1 and conveyed, and passes through the rolling roll 1 to be rolled. Further, it is placed on the table roller 7 and conveyed (rightward path). Then, this round trip is repeated several times. The plate thickness of the rolled material P during rolling is adjusted by adjusting the amount of reduction of the rolling roll 1 by the reduction device 4.

In carrying out the method of the present invention, the right side and the left side of the pair of rolling rolls 1, that is, when the rolled material P is moved from the right side to the left side to perform rolling, the inlet side and the outlet side, and the rolled material P. When moving from the left side to the right side for rolling, the first and second plate speed gauges 11 and 1 are provided on the exit side and the entrance side at positions within 2 m from the rolling mill, respectively.
2 is provided. The positions of these plate speed gauges 11 and 12 are symmetrical with respect to the rolling roll 1. Also, each plate speed meter 1
Reference numerals 1 and 12 are provided at the table rollers 7 and 8 below the conveyance path of the rolled material P.

The plate speedometers 11 and 12 are of a laser Doppler system for irradiating the rolled material P with a laser beam and measuring the moving speed of the rolled material P in the reflected state.
According to the current speedometer technology, it is possible to obtain a wide measurement range that is resistant to environmental disturbances.

On the right side of the pair of rolling rolls 1, that is, when the rolled material P is moved from the right side to the left side for rolling, on the entry side, the plate speed meter 11 is farther than the pair of rolling rolls 1. A plate thickness gauge 13 is provided at the position. The plate thickness gauge 13 is of a radiation type. A third plate speed meter 14 is provided at a position distant from the pair of rolling rolls 1 with respect to the plate thickness meter 13. A laser Doppler system is used as the plate speed meter 14. Alternatively, the plate speed meter 14 is provided at the same position as the plate thickness meter 13.

Further, on the left side of the pair of rolling rolls 1, that is, when the rolled material P is moved from the left side to the right side for rolling, the pair of rolling rolls 1 with respect to the plate speed gauge 12 is provided on the inlet side.
A plate thickness gauge 15 is provided at a farther position. The plate thickness gauge 15 is of a radiation type. A plate speed gauge 16 is provided at a position distant from the pair of rolling rolls 1 with respect to the plate thickness meter 15. A laser Doppler system is used as the plate speed meter 16. Alternatively, the plate speed meter 16 is provided at the same position as the plate thickness meter 15.

Reference numeral 21 is an arithmetic circuit for each plate speed meter 11.
Information from 12, 14, 16 and thickness gauges 13, 15
The plate thickness of the rolled material P is calculated by receiving the information from Reference numeral 22 denotes a control circuit, which receives information from the arithmetic circuit 21 and compares it with a preset reference plate thickness value set in advance to instruct the reduction device 4 about the drive amount so as to correct the deviation.
The reduction device 4 is driven by a predetermined amount based on this instruction. Information on the reduction amount detection device 5 and the load detection device 6 is sent to the control circuit 22.

Next, a method for controlling the plate thickness of the rolled material in this rolling mill will be described. As an example, the case of a leftward path will be described. Rolling roll 1 for leftward pass
On the other hand, the right side is the entrance side and the left side is the exit side. The rolled material P is placed on the table roller 7 and conveyed from the right side to the left side of the rolling roll 1, passes through the rolling roll 1 and is rolled, and then is further placed on the table roller 8 and conveyed.

First, the plate thickness of the rolled material P passing through the plate thickness gauge 13 is measured. Further, the plate speed meter 14 measures the speed of the rolled material P, and the arithmetic circuit 21 uses the measured value to calculate the movement amount of the plate thickness measuring portion of the rolled material P whose plate thickness is measured. . As a result, the arithmetic circuit 21 changes the rolling roll 1 from moment to moment.
The plate thickness hi at the entrance side of each part of the rolled material P which has reached is calculated.

At the same time, the traveling speeds Vi and V0 of the rolled material P on the inlet side and the outlet side are measured by the plate speed gauges 11 and 12 provided on the inlet side and the outlet side of the rolling roll 1. At this time, according to the principle of constant mass flow on the inlet side and the outlet side of the rolling roll 1, the outlet plate thickness h0 is h0 × W0 × V, where the plate widths of the rolled material P on the inlet side and the outlet side are Wi and W0.
0 = hi × Wi × Vi holds.

That is, h0 = (Wi / W0) × (Vi
The output side plate thickness h0 can be estimated as / V0) × hi. The arithmetic circuit 21 calculates the outgoing plate thickness h0 based on this equation.

Here, the strip widths Wi and W0 of the rolled material P on the inlet side and the outlet side of the rolling roll 1 may be actually measured, but sufficient accuracy ( It is possible to obtain ± 0.2%) and considering the difficulty of measurement at a position close to the rolling roll 1, Wi / W0 = f (Wi, h
It is advantageous to give i, h0, R, μ, Km) as a coefficient for each pass.

Further, the speed V0 of the rolled material P on the delivery side may be approximated by using the peripheral speed of the roll × (1 + advance rate) and replaced with actual measurement, but the prediction accuracy of the advance rate is ± 0. It is not sufficient at about 6%, and at present, it is limited to use as an excessive estimation for only the tip portion until the delivery side plate speed calculation position is reached.

Then, based on this measurement result, the rolled material P
Plate thickness control. That is, the arithmetic circuit 21 sends the output side plate thickness information to the control circuit 22, and the control circuit 22 calculates the control amount based on this and instructs the reduction device 4.

As described above, instead of measuring the plate thickness of the rolled material P with the plate thickness gauge provided in the position close to the rolling rolls, the output side plate thickness h0 estimated by the above method is used to perform the feedback plate thickness. By performing the control, the plate thickness can be measured with the same accuracy as when the plate thickness gauge is provided at a position close to the rolling roll.

Also, when the rolled material P is rolled in the rightward pass, the same effect can be obtained by the same action. In this case, the plate thickness obtained by the principle of constant mass flow at the time of the previous leftward pass and the data of the position of the plate thickness measurement portion obtained by the plate speedometer 12 on the output side are used to make the right side pass plate thickness gauge. It is also possible to replace with the concrete data of 15 and the plate speed meter 16.

In the method of the present embodiment, the plate speed meter is an optical one, and the speed is measured by providing the light emitting portion on either the upper side or the lower side of the passage of the rolled material P. It can be provided at a position close to the rolling roll without being affected by the warp of the rolled material, and does not require a strong protection facility.

Since the plate thickness gauge is provided at a position apart from the rolling roll, it is not affected by the plate warp of the rolled material. Measuring the plate thickness on the entry side with a plate thickness gauge provided at a location distant from the rolling roll is not adopted because the calculation of the delay in transferring the plate thickness becomes enormous and there is a problem in measurement accuracy. However, coupled with the fact that the accuracy of the plate speed gauge has improved in recent years, this problem was solved by providing plate speed meters near the plate thickness gauge and at the inlet and outlet sides near the rolling rolls, respectively. There is.

For these reasons, it is impossible to employ a conventional reversible hot rolling mill because it is impossible to provide a plate thickness gauge at a position close to a rolling roll when rolling a thick strip. The thickness of rolled material can be measured by using the monitor AGC
It can be measured by GC.

That is, according to the present invention, since the AGC using the mass flow plate thickness is applied to the rolling mill in the situation where the plate thickness gauge cannot be installed close to the rolling mill, a great effect can be obtained. Conventionally, the measurement of mass flow plate thickness itself is not applied to rolling mills under such conditions because unmeasureable parts occur at the front and back of the rolled material because the thickness gauge cannot be installed close to the rolling mill. However, according to the present invention, it is possible to perform measurement with a precision that is practical by properly selecting and arranging the sensors.

[0043]

As described above, according to the sheet thickness measuring method of the hot rolling mill of the present invention, it is a reversible hot rolling mill of ferrous steel or non-ferrous metal, and a rolled material having a sheet thickness of 50 mm or more is used. In a rolling mill having the ability to pass, it is possible to install a plate speed gauge near the rolling mill, and it is possible to measure the same speed as the rolling mill entrance side and rolling mill side due to the continuity of the rolled material. It is possible to measure the strip thickness of the rolled material with high accuracy by the monitor AGC without installing the strip thickness gauge near the rolling mill. High accuracy, reduction of delay time and reduction of uncontrolled tip of rolled material are possible without installation.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a strip thickness measuring method in a hot rolling mill.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rolling roll, 11 ... Plate speed meter, 12 ... Plate speed meter, 13 ... Plate thickness meter, 14 ... Plate speed meter,
15 ... Plate thickness gauge, 16 ... Plate speed gauge.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G01B 11/06 Z G01P 3/36 E

Claims (1)

[Claims] 1. A reversible hot rolling mill for ferrous or non-ferrous metals, which is capable of passing a rolled material having a plate thickness of 50 mm or more, wherein the rolling mill is installed at the pass for controlling the plate thickness. Side and exit sides are provided with first and second plate speed gauges at positions close to the rolling mill, a plate thickness gauge is provided at a position 3 m or more from the entrance side of the rolling mill, and the same position as this plate thickness gauge is provided. Or a third plate speed meter is provided at a position distant from the rolling mill with respect to this position, and the entrance side plate thickness of the rolled material that is moved toward the rolling mill is measured by the plate thickness gauge, and Three plate speedometers measure the moving speed of the rolled material, determine the time when the plate thickness measurement portion of the rolled material reaches the rolling mill, and the incoming plate thickness of the rolled material at each moment, Before passing through the rolling mill measured by the first and second plate speedometers From the incoming speed and the outgoing speed of the rolled material, in the hot rolling machine characterized by estimating the outgoing plate thickness of the rolled material based on the principle of constant mass flow on the incoming and outgoing sides of the rolling mill Plate thickness measurement method.