JPS63130205A - Method for controlling thickness of tapered metal plate - Google Patents

Abstract

PURPOSE:To permit plate thickness control with decreased thickness errors by determining an actual taper quantity from the detected thickness and moving distance of a rolled stock, calculating the control taper quantity from the deviation from a reference value and adjusting a roll gap. CONSTITUTION:A pulse generator 3 emits the rotation signal of a work roll 1 and a counter 41 detects the rotating speed from the signals thereof and calculates the moving distance of a steel product 2 from the rotating speed and roll diameter. On the other hand, a thickness detector 5 detects the transmitted radiation dose changing according to the thickness and outputs the same to a thickness measuring part 43 of a thickness controller 4 which calculates the actually measured thickness value in accordance with the detected value. An average taper quantity computing part 44 calculates the average value of the tapered quantity from the moving distance and the thicknesses at a prescribed number of thickness detection points and outputs the same to a deviation computing part 45 which calculates the deviation of the average value and the reference taper quantity to output the same to a target thickness change computing part 46 which calculates a change quantity of the thickness and outputs the same to a gap control part 6. The control part controls a hydraulic screw down device 7 to adjust the roll gap.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the longitudinal thickness of a tapered metal plate manufactured by hot rolling a metal material.

[Prior Art] In ships, tanks, etc., the pressure applied to the steel plates that form them is small at the top and increases toward the bottom. Therefore, depending on the pressure applied, the upper part has a thin steel plate,
A thick steel plate was used for the lower part, and the upper and lower steel plates were welded together.

In recent years, in order to reduce such welding processes, 1
The method of using so-called tapered steel plates, in which the thicknesses of the steel plates differ in the longitudinal direction, is increasing.

In hot rolling, the roll opening is generally set in consideration of the plastic properties such as deformation resistance of the material to be rolled, the mill rigidity coefficient, etc. before rolling starts, but if rolling is continued with this set opening, This causes variations in the thickness of the rolled material on the exit side. That is,
The deformation resistance of each part varies according to the temperature difference between the parts of the heated rolled material, and this difference in deformation resistance affects the plastic properties, causing inappropriate roll openings and variations in plate thickness. A gauge meter method is used as a method for controlling such variations in plate thickness.

The gauge meter method is a control method commonly used in automatic plate thickness control devices (AGC) installed in rolling mills, and measures differences in deformation resistance of rolled materials as changes in rolling load caused by these differences. However, it is based on the principle that if the value calculated from this measured value and the mill rigidity is regarded as the amount of change in plate thickness and the roll opening degree is adjusted, the outlet side plate thickness can be kept constant. In other words, the plate thickness after rolling is determined by the roll opening during rolling, and the roll opening during rolling is determined by the roll opening during no load and the change in deformation resistance of the rolled material. The amount of deformation of the rolling mill is determined in proportion to the rolling load. Expressing this in the formula, h=so +P/M ・=+11 H: Output plate thickness So: Roll opening at no load P: Rolling load M: Mill rigidity coefficient, and by modifying the formula (1), Δh= ΔS+ΔP/M (1-1) Δh; Amount of plate thickness handled ΔS: Amount of change in roll opening ΔP: Amount of change in rolling load. Therefore, when rolling to a constant thickness, (1-1)
Adjust the roll opening to make Δh in the equation zero.

In addition, in the case of rolling a tapered metal plate, this plate thickness change amount Δh
is regarded as the taper amount, and the roll opening degree is adjusted so that Δh matches the desired taper amount.

As a method for rolling a tapered metal plate as described above, a feedforward method is also used.

The φ feedforward method predicts the rolling load before rolling based on the target taper amount and the predicted temperature of the material to be rolled, calculates and sets the rolling position of the predicted rolling load from the roll rotation speed, etc. Taper rolling is performed using the predicted rolling load at the rolling position.

[Problem that the invention seeks to solve]

However, the mill stiffness coefficient M used in equations (1) and (1-1) above is expressed as a relationship between rolling load and roll opening, but this is nonlinear and not in a -order numerical manner. In the rolling of a tapered metal plate, in which the roll opening degree changes over a wider range than in general rolling, only low accuracy can be expected in plate thickness control based on the gauge meter method.

In addition, the material to be rolled on the entrance side of the rolling mill suffers from deformation resistance, etc. due to temperature differences in each part of the material to be rolled due to changes in plate thickness, material quality, and differences in arrival time from the heating furnace to the rolling mill. Plastic properties are affected.

This instability of the plastic properties acts as a disturbance in the AGC control system, reducing the accuracy of plate thickness control.

Furthermore, since the tapered metal plate has a different cumulative reduction rate in the rolling direction, the temperature of the rolled material inevitably changes in the rolling direction, resulting in different deformation resistance.

Therefore, this difference in deformation resistance reduces the accuracy of plate thickness control in the AGC system.

On the other hand, the feedforward method controls the plate thickness based on the rolling position and rolling load set before rolling, so even though the set calculation formula is accurate, for example, if the starting point of control shifts, etc. Once rolling has started, there is no means to make corrections until the end of rolling, so the deviation is directly reflected in the error in plate thickness.

The present invention has been made to solve these problems, and an object of the present invention is to provide a highly accurate method for controlling the thickness of a tapered metal plate with less thickness error.

[Means for solving problems]

The present invention provides a length measuring device for detecting the moving distance of the material to be rolled, and also provides a plate thickness detector on the exit side of the rolling machine, and measures the plate thickness detected by the plate thickness detector and the plate thickness detected by the length measuring device. The actual taper amount is calculated from the detected moving distance of the rolled material, the deviation between the actual taper amount and a preset reference value is calculated, the control taper amount is calculated based on the deviation, and the control taper amount is The feature is that the roll opening degree is adjusted based on this.

[Function] In the method of the present invention, while the length measuring device detects the moving distance of the material to be rolled, when the tip of the material to be rolled reaches the thickness detector, the thickness detector detects the thickness of the material to be rolled. start, calculate the actual taper amount from these plate thicknesses and travel distance, calculate the deviation between this actual taper amount and a preset reference value, calculate the control taper amount based on this deviation, and calculate the control taper amount. Adjust the roll opening based on.

C Embodiment] Hereinafter, the present invention will be described in detail based on drawings showing embodiments thereof.

FIG. 1 is a block diagram showing the configuration of a rolling mill according to the present invention. In the figure, reference numeral 1 denotes a work roll, and upper and lower work rolls 1.1 roll a steel material 2. The work roll 1 is provided with a pulse generator 3 interlocked with the work roll 1. When rolling is started, the pulse generator 3 sends a signal according to the rotation of the work roll 1, and this signal is sent to the counter 41 of the plate thickness control device 4. Output to. counter 4
1 detects the rotation speed of the work roll 1 from this signal, and calculates the moving distance of the steel material 2 from this rotation speed and the roll diameter. On the other hand, a plate thickness detector 5 using X-rays, γ-rays, etc. is provided near the exit side of the work roll 1, and when the tip of the steel material 2 reaches the plate thickness detector 5, the plate thickness detector 5 detects the plate thickness. The amount of transmitted radiation that changes depending on the amount of radiation is detected, and this detected value is output to the plate thickness measuring section 43 of the plate thickness control device 4. The plate thickness measurement unit 43 calculates the actual measurement value of the plate thickness based on this detected value, and the plate thickness is detected at regular intervals in the same manner. After the plate thickness is detected, after a predetermined period of time has elapsed, plate thickness control based on the moving distance and the plate thickness actual measurement value is started, and the plate thickness control is performed at the same cycle.

The average taper amount calculation unit 44 calculates the average value of the taper amount from the moving distance and the plate thickness at a predetermined number of plate thickness detection points, and outputs it to the deviation calculation unit 45 . The deviation calculation section 45 calculates the deviation between this average value and a preset reference value of the taper amount and outputs it to the target plate thickness change amount calculation section 46, and the target thickness change amount calculation section 46 calculates the deviation Calculate the plate thickness change based on
This calculated value is output to the roll opening degree control device 6.

The roll opening degree control device 6 is composed of an AGC that controls the roll opening degree using a gauge meter method, and calculates the taper amount in the next control from the target plate thickness change amount, and further determines the rolling position according to this taper amount. is calculated, and the hydraulic pressure lowering device 7 consisting of a hydraulic valve, a hydraulic cylinder, etc. is made to adjust the roll opening degree.

Note that until the steel material 2 reaches the plate thickness detector 5 and the actual measurement of the plate thickness starts, the roll opening degree control device 6 operates as described in (1) above.
The roll opening degree is adjusted based on the plate thickness change amount calculated by the conventional gauge meter method using the formula and the formula (1-1).

The method for controlling the plate thickness l of the present invention will be explained below, focusing on the operation of the plate thickness control device 4 in the tapered steel plate rolling apparatus configured as described above, using symbolic expressions and a flowchart of the control procedure shown in FIG.

Note that the subscript i indicates the order of plate thickness detection and control.

Furthermore, until the steel material 2 reaches the plate thickness detector 5 and the plate thickness is detected, a gauge meter method similar to the conventional method is used.

That is, the pressure gauge detected by the load cell 8 provided near the work roll 1 is output to the rolling load measuring device 9,
While calculating the rolling load P, the rolling position, that is, the roll opening degree S, is detected from the rolling position detector 10 provided in the hydraulic rolling device 7. When these rolling load P and roll opening degree S values are output to the roll opening degree control device 6, the roll opening degree control device 6 calculates these changes ΔP and ΔS,
From these values and the mill stiffness coefficient M, the plate thickness change amount Δh is calculated as in the above equation (1-1). Furthermore, this calculated value Δ
h and the target plate thickness change amount set in advance according to the rolling schedule, and in order to make this deviation zero, P
I control is performed to calculate the rolling down position, and the hydraulic rolling down device 7 adjusts the roll opening degree based on this calculated value.

Further, when the work roll 1.1 starts rolling the steel material 2, the pulse generator 3 transmits a signal in synchronization with the pulses generated as the work roll 1 rotates, and the counter 41 that receives this signal The moving distance La of the steel material 2 is calculated from the rotation speed and roll diameter of the work roll 1 calculated from this number of signals (bl.
When reaching the plate thickness, a change in the amount of transmitted radiation such as X-rays and γ-rays is detected according to the plate thickness (C), and this detected value is the plate thickness α1 constant part 4
3 and the plate thickness ha is calculated (d). Similarly, each time a plate thickness detection point is reached, the plate thickness hal + h
a2, ha3... are calculated.

Next, the average taper amount measuring section 44 at the control point l,
Calculate the average taper amount Δhta: from the plate thickness at a predetermined number of plate thickness detection points and the moving distance of the steel material 2.e), and use this average taper amount Δhtal as the actual value of the taper amount at the control point i. The average taper amount measurement unit 44 similarly calculates a moving average value of the taper amount from the plate thickness at a predetermined number of plate thickness detection points for each control point.

On the other hand, the target taper amount calculation unit 42 stores the planned thickness change Δh aim of the steel material 2 and the planned rolling distance La1n from the tip of the steel material 2 to the point at which the planned thickness change is achieved, based on the rolling schedule. It is set before the start of rolling (f),
From these values, the reference taper amount Δh taia+ is calculated as follows (fgl.

aim The deviation calculation unit 45 also calculates the reference target taper amount Δh ta
The deviation Δhte between im and the average taper amount ΔhtaH is calculated as in the following formula (hl.

Δhtel=Δhtaim, (Δhta1 +Δh
tel-I
Target taper amount Δb in 1ν control this time based on H-+
The deviation Δhte+ of the control point is corrected on the premise that aaiml has been corrected as described later and rolling has been performed according to this correction value.

In this case, if the gain is less than 1.0, the correction will be slow and the control will be insufficient, and if it exceeds 2.0, the correction will be rapid and the control will become unstable, so set the gain to between 1.0 and 2.0. do. Note that at the first control point (i = 1), since the deviation detection of the previous control point is not performed, the deviation Δht
It is not possible to modify e1. Therefore, as shown in the formula below, Δhte1=Δh time−Δhta1 ++・(
3-1).

Next, the target plate thickness change amount calculation unit 46 first calculates the next control point (
Target taper amount Δh taim up to i+1): + 1
Calculate as below.

Δhtaiml+1=Δhtaim: +Δhte;
X G − (41 Furthermore, this target taper amount・Δh
timeBB + standard taper amount Δh caim Target plate thickness change amount Δh caim at the next control point (i+1) from the moving distance of the steel material 2 to be rolled based on taim and these values
++ Calculate 1 (jl.

Δhcaim l+ 1−ΔhtimeXLa +Δ
htaim1+I Xj! cp...(5) La: Distance traveled by the steel material lcp: Control pitch Here, the scale factor of the roll opening degree control device 6 (AGC control system) is O≦KA≦1.0 (take direct and KA
When is smaller than 1.0, A
It is necessary to take into account the decrease due to the GC scale factor KA and the change in the thickness of the inlet side, and Δhc1++ is obtained by correcting Δhcaim+++.

Δhc1H−Δhcaim++t×f(KA+Q
+M, 8H+)...(6) f (K8, Q, M, ΔH1) Correction of the decrease by the two-scale factor KA and the change in the entrance plate thickness Q: Plasticity coefficient M: Mill stiffness coefficient □ Number ΔH1 : Entrance side plate thickness change KA Niscale factor Therefore, this plate thickness control value Δhc1++ is calculated by plate thickness correction calculation section 4.
After being corrected in step 7, it is outputted to the roll opening degree control device 6 as the target plate thickness instruction value of 8GC.

After the start of plate thickness control by actual plate thickness measurement, PI control is performed on the control value Δhct++ instead of the plate thickness change amount Δh calculated from the detection values of the rolling load and roll opening in AGC, and the hydraulic pressure is adjusted according to the control result. The rolling down device 7 determines the rolling position and the roll opening degree is adjusted (g)).

〔effect〕

In the method of the present invention, by controlling the plate thickness based on the actual plate thickness value, the plate thickness is lower than the plate thickness control based on the plate thickness assumed value calculated based on the unstable factors such as the mill stiffness coefficient and the plasticity coefficient. This has the excellent effect of enabling highly accurate plate thickness control with few errors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a rolling mill according to the present invention;
FIG. 2 is a flowchart showing the control procedure. 1... Work roll 2... Steel material 3... Pulse generator 4... Plate thickness control section 5... Plate thickness detector 6... Roll opening degree control device 7... Hydraulic lowering device 8 ...Load cell 9...Rolling load measuring device 10.
...Down position detector 41...Counter 42...
Target taper amount calculation section 43... Plate thickness measurement section 44...
・Average taper degree measurement section 45...Deviation calculation section 46.
...Target plate thickness change calculation unit 47...Plate thickness correction calculation unit Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono $2 Figure

Claims (1)

[Claims] 1. A length measuring device is provided to detect the moving distance of the material to be rolled, and a plate thickness detector is provided on the exit side of the rolling machine, and the plate thickness detected by the plate thickness detector and the plate thickness detected by the length measuring device are provided. The actual taper amount is calculated from the moving distance of the rolled material, the deviation between the actual taper amount and a preset reference value is calculated, the control taper amount is calculated based on the deviation, and the roll is adjusted based on the control taper amount. A method for controlling the thickness of a tapered metal plate, characterized by adjusting the opening degree.