JPH0841617A - Control of weight unit, metsuke in transverse direction of hot dip coated steel sheet - Google Patents

Abstract

PURPOSE:To make it possible to obtain a homogeneously plated steel by predicting a camber by using a specific relation and controlling the flatness of the steel sheet to high accuracy. CONSTITUTION:The steel sheet 15 is made to travel via a sink roll 5 and support rolls 6, 7 in a hot dip coating bath from hot bridle rolls 1 to 4 and the weight unit in the transverse direction of the plated steel sheet is controlled. Thereupon, theta is calculated between the respective rolls by using the relation. The wrapping angle THETAof the steel sheet 15 of the first roll is determined. The wrapping angle of the first roll and the C camber on the outlet side of the respective rolls are obtd. as functions by the equation using the sum of the moving amt. of the sink roll 5 and the moving amt. of the lower support roll 6 obtd. by the relation. Presetting is executed by a driving device 11 in accordance with the numerical value calculated in such a manner that the C camber of on the outlet side of the first roll attains 0, by which the flatness of the steel sheet 5 is controlled with the high accuracy and the variations in the METSUKE in the transverse direction of the steel sheet are minimized. As a result, the variations in the transverse direction of the steel sheet are made uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to hot-dip galvanizing, in which a steel plate or a steel plate coated with an underplating metal such as Ni runs through a hot-dip galvanizing bath of a corrosion-resistant metal such as zinc, lead-tin or aluminum. The present invention relates to a control method for making uniform the areal weight variation of a steel sheet.

[0002]

2. Description of the Related Art Hot-dip galvanized steel sheets are of many types such as zinc, tin, and aluminum, which have relatively low melting points. It is often used as a material for automobiles and home appliances. Such a hot-dip galvanized steel sheet is generally a hot-rolled or even cold-rolled steel sheet that passes through a pre-oxidation furnace, then a reduction annealing furnace, and then a cooling furnace, passes through a hot-dip galvanizing bath, and is in a molten state adhered to the surface. The plating metal is wiped with a gas wiping nozzle while being controlled to have a predetermined basis weight, and if necessary, it is further passed through an alloying heating furnace for production. However, there is a problem in that the weight per unit area of the plated metal of the manufactured hot-dip plated steel sheet varies greatly in the width direction, and the weldability or the close coatability is impaired. Such a problem depends on the distance between the steel plate and the gas wiping nozzle, and can be solved by always keeping the distance constant, but it has not been solved because the steel plate changes into various shapes and runs.

As a means for flattening the shape of a steel sheet, a method of judging the shape of the steel sheet by an operator's visual observation and moving a sink roll or a support roll in the plating bath or a touch roll above the gas wiping is disclosed in JP-A-3-17249. Japanese Patent Laid-Open No. 3-138344, a method of adjusting the amount of pushing of a support roll so that the amount of warp at the nozzle position becomes 0 according to the steel plate size and tension of the steel plate to be plated and the material, The position of the roll in the snout is adjusted so that the warp amount at the nozzle position becomes 0 according to the steel plate size, tension, and material of the steel plate to be plated, as in Kaihei 2-54746 and Japanese Patent Laid-Open No. 3-166354. Or installing shape detectors before and after the gas wiping nozzle position and adjusting the position of the roll in the snout so that the amount of warp at the nozzle position becomes zero. That way, JP-A-2-26
As in Japanese Patent No. 585, the thickness of the plating layer at the end and the center in the width direction of the steel plate is detected above the gas wiping nozzle, and the position of the sink roll is automatically controlled so that the difference between the detected values becomes the minimum value. However, there is a method of correcting the shape.

However, in the case where the position of the sink roll or the support roll is preset based on experience as described above, it is not possible to expect flatness of the steel plate shape with a large amount of hits and misses at all times. Regarding the method of adjusting the position of the support roll according to the steel plate to be plated, there are a huge number of combinations of steel plate size and material, and it is necessary to analyze a huge amount of data to enable presetting in any pattern. Is required.

Further, as for the method of adjusting the roll position in the snout according to the steel plate to be plated,
There are a huge number of combinations of steel plate size and material, and a huge amount of data must be analyzed to enable presetting in any pattern. Also, in automatic control using a shape detector, a shape detector with considerably high accuracy is required, but since unsolidified molten zinc adheres to the steel plate near the gas wiping nozzle, the contact type shape detector is used. Laser-type and electromagnetic-type non-contact type shape detectors are used because of the problem that the detector cannot be used.

The laser type shape detector includes a light cutting method of irradiating a laser beam and a method of projecting a reflected light of the irradiating laser light on a screen to process the screen. In the former method, since the steel plate near the gas wiping is in a mirror surface state, diffuse reflection hardly occurs, the sensitivity deteriorates, and measurement is impossible. In the latter method, since the steel plate is constantly vibrating, the reflected image is displaced, and there is a problem in measurement accuracy. or,
In order to detect the shape with high accuracy, it is necessary to set a large distance from the irradiation laser beam from the steel plate, but many devices are installed around the gas wiping device, making it physically impossible to install. is there. On the other hand, the electromagnetic shape detector has a method of detecting the shape by measuring the tension distribution of the steel sheet by applying an electromagnetic force from the outside of the steel sheet, as disclosed in Japanese Patent Publication No. 57-6054. Since even the flattened steel plate shape is detected, it is impossible to detect the steel plate shape at the gas wiping position, and at the present time, a highly accurate shape detector cannot be expected.

Further, the shape correction as described above is effective only in the case of a steel plate shape having a simple symmetrical warp.
The actual steel plate shape is not limited to a bilaterally symmetrical simple warp, but also a bilaterally asymmetrical steel plate shape. In the case of an asymmetrical steel plate shape, even if the position of the sink roll or the like is controlled by calculating the difference in the thickness of the plating layer between the end portion and the central portion in the width direction of the steel sheet,
The steel plate is not always flat. That is, in the asymmetrical steel plate shape, it is necessary to detect and control the continuous shape of the steel plate.

Further, in the single-operation arrangement of the support rolls in which only the lower support rolls are used for straightening the shape, in the case of straightening only by moving the sink roll to straighten the shape of the steel plate of thick material, the sink is used. Although the roll cannot be straightened unless it is moved considerably, there is a limit to the amount of movement of the sink roll due to the structure of the equipment, so the steel plate shape of thick material may not be straightened in some cases. Therefore, when the support roll is moved to perform shape correction, if the lower support roll is a single operation, moving the lower support roll changes the vertical pass line of the steel sheet, and therefore it is installed on the bath. Other equipment such as a wiping nozzle also has to be moved, which complicates the work. For this reason,
Although it is sufficient to perform two operations of upper and lower supports that can fix the shape of thick steel plate and the vertical pass line of steel plate,
Since the amount of movement of the sink roll that eliminates the warp is different between the case where the single operation of the support roll is performed and the case where the operation of the second support roll is performed, high precision cannot be expected by the control methods such as.

[0009]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art, and (1) according to the operation state such as one operation of the support roll and two operations, and the roll position,
From the relational expression between the wrap angle of the roll and the amount of C warp, the moving amount of the sink roll or the support roll that makes the steel plate shape flat is calculated, and based on this, presetting is performed using the drive device of the sink roll or the support roll, It is possible to control the flatness of the steel sheet with high accuracy.

Also, (2) one operation of the support roll, 2
It is possible to detect the continuous shape of the steel plate at the nozzle position according to the main operating state and roll position, and even in the case of asymmetrical steel plate shapes, the sink roll and support roll can be operated to determine the total absolute amount of warpage. It is possible to minimize the variation of the basis weight of the steel sheet in the width direction.

Further, (3) one operation of the support roll,
2 According to the operation state and roll position, the amount of warp of the steel plate at the nozzle position is predicted from the amount of steel plate warp detected in the snout, and the amount of movement of the sink roll or support roll that makes the predicted warp amount 0 By calculating and operating, it is possible to minimize the total absolute amount of warpage and control the variation in areal weight of the steel sheet in the width direction to the minimum. The purpose is to:

[0012]

A first aspect of the present invention is a galvanized steel sheet that travels from a hot bridle roll through a sink roll or a support roll in a hot dip plating bath. Is used to calculate θ between the rolls, the wrap angle Θ of the steel plate at the i-th roll is obtained from the equation (4), and the wrap angle at the i-th roll and the amount of C warp on the roll-out side are calculated. than the (5) showing a relationship, a sum of the amount of movement and the lower support roll of the sink roll as C warpage of relation (6) for each roll as P _Shift, the P _Shift Obtained as a function, ΔC
It is characterized in that the flatness of the steel sheet is controlled with high precision by using a shape control calculation device that calculates P _shift for = 0 and a drive device that moves the sink roll based on the calculated P _shift. Is a method for controlling the areal weight of the hot dip plated steel sheet. θ _i = cos ⁻¹ (A / B) …………………… (1) where A = H _i × [H _i ² + D _i ² − (d _i + d _{i + 1} ) (D _i + a) −a ² ] ^1/2 + (1/4) × (d _i + d _{i + 1} −2D _i ) × (d _i + d _{i + 1} +2 a) ... (2) B = H _i ² + (1/4) × (d _i + d _{i + 1} −2D _i ) ² (3) H _i : Center distance between i-th roll and i + 1-th roll D _i : i-th roll and i + 1-th roll Roll wrap amount d _i : Roll diameter of i-th roll d _{i + 1} : Roll diameter of i + 1-th roll a: Plate thickness Θ _i = θ _i-1 + θ _i …………………… (4) ΔC _i = (A ₁ Θ _i + A ₂ T / Y _P Θ _i + A ₃ a / Θ _i + A ₄ Y _P / a) + (A ₅ Y _P Θ _i + A ₆ a ² / Θ _i + A ₇ a / Θ _i + A ^{_{8 aY P + a 9 a 2}} + a 10) ΔC i-1 + a 11 ..................... (5) However, [Delta] C _i: i-th roll exit side Of C warpage _{(mm) ΔC i-1:} C warpage at (i-1) -th roll exit side (mm) theta _i: winding angle of the i-th roll (deg) T: tension (kg / mm ²⁾ Y _P : Yield stress (kg / m ² ) A ₁ to A ₁₁ : Constant ΔC = Q (P _shift ) …………………… (6)

A second aspect of the present invention detects the intensity of fluorescent X-rays received by irradiating γ-rays or X-rays in the width direction of the plated steel sheet traveling from the hot dip bath through the gas wiping zone, and detecting the intensity of the fluorescent X-rays in the width direction of the steel sheet. From the plate width direction scanning plating amount measuring device for measuring each plating amount on the front and back surfaces and each measured plating amount on the front and back surfaces in each width direction of the steel plate, the steel plate shape is obtained based on the equation (7). A shape calculation device and the steel plate shape obtained from this are approximated by a function of a quartic function, the extreme value of the quartic function is calculated, the form of the steel plate shape is recognized from the number of calculated extreme values, and the amount of warpage is calculated. And the wrap angle of the steel plate at the i-th roll by calculating the warp amount calculation device and the formulas (1) to (3) geometrically from the roll arrangement to calculate θ between the rolls. Θ is obtained from the equation (4) and the moving amount of the sink roll and the moving amount of the lower support roll are calculated. The sum of the amounts by using the C amount of warpage of the relational expression a (5) at each roll exit side as P _Shift, calculates the amount of warpage in support roll exit side as in equation (6), is estimated When the curved shape is asymmetrical to the left and right, a model formula that minimizes the absolute amount of the entire warp is obtained as in the formula (8), and a P _shift for calculating ΔC = 0 is calculated. A drive device that drives the sink roll so as to achieve the _specified P _shift , and the shape estimated from the adhered amount according to the operating state of the support roll and the roll arrangement is an asymmetrical steel plate shape such as S warp or W warp. In the above, the feature is that the movement amount of the sink roll that minimizes the overall warpage in the shape is calculated, and the sink roll is moved based on this amount to minimize the unit weight variation in the width direction of the steel sheet. Hot dip This is a method for controlling the basis weight of the steel sheet in the width direction. ΔD = (lnW ₁ −lnW ₂ ) / K …………………… (7) However, ΔD: Displacement amount (mm) when the center of the distance between the front and back gas wiping nozzles is 0 (mm) W ₁ : Front of steel plate Adhesion amount (g / m ² ) W ₂ : Adhesion amount on the back of the steel sheet (g / m ² ) K: Constant that varies depending on the type of steel sheet θ _i = cos ⁻¹ (A / B) ………………… (1) However, A = H _i × [H _i ² + D _i ² − (d _i + d _{i + 1} ) (D _i + a) −a ² ] ^1/2 + (1/4) × (d _i + d _{i +1} −2D _i ) × (d _i + d _{i + 1} +2 a) ... (2) B = H _i ² + (1/4) × (d _i + d _{i + 1} −2D _i ) ² …………… ( 3) H _i : distance between centers of i-th roll and i + 1-th roll D _i : roll wrap amount of i-th roll and i + 1-th roll d _i : roll diameter of i-th roll d _{i + 1} : i + 1 th roll roll diameter a: plate thickness _{Θ i = θ i-1 +} θ i ............... _{... (4) ΔC i = (} A 1 Θ i + A 2 T / Y P Θ i + A 3 a / Θ i + A 4 Y P / a) + A 5 Y P Θ i + A 6 a 2 / Θ i + A 7 a / θ _i + A ₈ aY _P + A ₉ a ² + A ₁₀ ) ΔC _i-1 + A ₁₁ (5) However, ΔC _i : C warp amount (mm) ΔC _i at the i-th roll exit side _-1 : i-C roll amount (mm) on the exit side of the 1st roll Θ _i : winding angle (deg) of the i-th roll T: tension (kg / mm ² ) Y _P : yield stress (kg / m) ² ) A ₁ to A ₁₁ : constant ΔC = Q (P _shift ) ……………… (6) ΔC = Q (P _shift ) + (ΔC _DS + ΔC _WS ) −ΔC _A ………… ( 8) _{However, ΔC = Q (P shift)} : sheet thickness, tension, P _Shift determined by warpage and winding angle at the yield stress and the rolls
Function of ΔC _DS : Warp amount on the left side with respect to the center of S warp (m
m) (In case of W warp, ΔC _C : Corresponds to center warp) ΔC _WS : In the case of S warp, the amount of warp on the right side with respect to the center (m
m) (ΔC _E in case of W warp: Corresponding to edge warp) ΔC _A : Q during P _shift when recognizing the shape and calculating the warp amount
(P _shift )

A third invention is a method for controlling the areal weight of a plated steel sheet which runs from a C warp detector for measuring the shape of a steel sheet in a snout and a hot bridle roll through a sink roll or a support roll in a hot dip plating bath, From the roll arrangement geometrically using the formula (1), θ between each roll
Is calculated, and the wrap angle Θ of the steel plate on the i-th roll is obtained from the formula (4), and the formula (5) indicating the relationship between the wrap angle on the i-th roll and the amount of C warpage on the roll-out side is expressed. Accordingly, the sum of the moving amount of the sink roll and the moving amount of the lower support roll is defined as P _shift , and the relational expression (6) of the C warp amount of each roll
Use the formula to determine the amount of warpage on the support roll outlet side (6)
Using the amount of warpage calculated by the formula and measured from the C warpage detector installed in the snout, the amount of warpage on the support roll outlet side is predicted from the formula (6), and this predicted amount of warpage Δ
A shape control calculation device that calculates P _shift such that C = 0 and a drive device that drives a sink roll and a support roll that are rolls in the bath to achieve the calculated P _shift. The amount of warp of the support roll on the output side is predicted from this, and the amount of movement of the sink roll or support roll that minimizes the amount of warp on the output side of the support roll is calculated according to the operating state of the support roll and the roll arrangement. A method for controlling the basis weight of a hot-dipped galvanized steel sheet is characterized by minimizing the variation in the basis weight of the steel sheet by moving a roll or a support roll. θ _i = cos ⁻¹ (A / B) …………………… (1) where A = H _i × [H _i ² + D _i ² − (d _i + d _{i + 1} ) (D _i + a) −a ² ] ^1/2 + (1/4) × (d _i + d _{i + 1} −2D _i ) × (d _i + d _{i + 1} +2 a) ... (2) B = H _i ² + (1/4) × (d _i + d _{i + 1} −2D _i ) ² (3) H _i : Center distance between i-th roll and i + 1-th roll D _i : i-th roll and i + 1-th roll Lapping amount d _i : Roll diameter of i-th roll d _{i + 1} : Roll diameter of i + 1-th roll a: Plate thickness Θ _i = θ _i-1 + θ _i …………………… (4) ΔC _i = (A ₁ Θ _i + A ₂ T / Y _P Θ _i + A ₃ a / Θ _i + A ₄ Y _P / a) + (A ₅ Y _P Θ _i + A ₆ a ² / Θ _i + A ₇ a / Θ _i + A _{8 ^{aY P + a 9 a 2 +}} a 10) ΔC i-1 + a 11 ........................ (5) However, [Delta] C _i: i-th roll exit side Of C warpage _{(mm) ΔC i-1:} C warpage at (i-1) -th roll exit side (mm) theta _i: winding angle of the i-th roll (deg) T: tension (kg / mm ²⁾ Y _P : Yield stress (kg / m ² ) A ₁ to A ₁₁ : Constant ΔC = Q (P _shift ) …………………… (6)

(Detailed Description of the Invention) In FIG. 1 and FIG.
An example of an apparatus for carrying out the width direction basis weight control method of the present invention will be shown. Reference numeral 15 is a steel plate which is plated with a corrosion-resistant metal such as zinc or lead-tin and runs. The steel plate 15 passes through the hot bridle rolls 1 to 4 and is circulated around the sink roll 5 in the hot dip bath to be plated, and the lower support roll 6,
The shape is corrected by the upper support roll 7 and then rises, and then the gas wiping nozzle 8 and an electromagnetic wiping nozzle, which is installed as necessary, controls the amount of coating to a predetermined amount, and then rises to reach the top roll 9.

The single operation of the support rolls means that the upper support rolls 7 are separated from the steel plate 1 so as not to come into contact with each other as shown in FIG. 2, and the rolls in contact with the steel plate 15 are called sink rolls 5 and lower support rolls 6. It is an operating form.
As shown in FIG.
The rolls that are in contact with the sink roll 5, the lower support roll 6, and the upper support roll 7 are in an operating mode. Reference numeral 10 is a shape control calculation device.

As shown in FIG. 3, i-th roll and i + 1
The wrapping angle generated between the two rolls of the th roll can be calculated geometrically as shown in equation (1). θ _i = cos ⁻¹ (A / B) …………………… (1) where A = H _i × [H _i ² + D _i ² − (d _i + d _{i + 1} ) (D _i + a) −a ² ] ^1/2 + (1/4) × (d _i + d _{i + 1} −2D _i ) × (d _i + d _{i + 1} +2 a) ... (2) B = H _i ² + (1/4) × (d _i + d _{i + 1} −2D _i ) ² (3) Here, H _i is the center distance between the i-th roll and the i + 1-th roll, and D _i is the i-th roll and the i + 1-th roll. The roll wrap amount of the roll, d _i is the roll diameter of the i-th roll, d _{i + 1} is the roll diameter of the i + 1-th roll, and a is the plate thickness.

When θ is calculated between the rolls, the overall wrap angle Θ of the steel sheet on the i-th roll is Θ _i = θ _i-1 + θ _i (4). However, the wrap angle of the first roll is Θ ₂ = θ
_2, in the case of one support roll operations, the sixth roll winding angle is theta ₆ = theta _6, when the two support rolls operations, 7 th roll winding angle is theta ₇ = theta _7.

Next, the wrap angle and C for the i-th roll
The following relational expression holds with the amount of warpage. ΔC _i = (A ₁ Θ _i + A ₂ T / Y _P Θ _i + A ₃ a / Θ _i + A ₄ Y _P / a) + (A ₅ Y _P Θ _i + A ₆ a ² / Θ _i + A ₇ a / Θ _i + A ₈ aY _P + A ₉ a ² + A ₁₀ ) ΔC _i-1 + A ₁₁ (5) where ΔC _i is the amount of C warpage on the i-th roll exit side, Δ
C _i-1 is the amount of C warpage on the exit side of the i-1 th roll, Θ _i is the overall wrap angle of the i th roll, T is the tension, Y _P is the yield stress, a is the plate thickness, and A ₁ to A ₁₁ is a constant.

In the case of one support roll operation, the wrap angles of the hot bridle roll 1 to the lower support roll 6 and the C warp amount on the roll-out side of each roll are calculated, and in the case of two operation rolls, the hot bridle roll 1 ~ The wrapping angle to the upper support roll 7 and the amount of C warpage on the roll exit side are calculated.

Now, _assuming that D ₅ = P _shift , in the case of the operation of one support roll, the amount of C warp on the rising side at the exit side of the lower support roll 6 is calculated by using the formulas (1) to (5). Calculating the wrap angle and the amount of C warpage from 1 to 6,
It has a relational expression like the expression (9). ΔC ₆ = Q ₁ (P _shift ) (9) This is the P _shift determined by the plate thickness, tension, yield stress, the amount of warpage in the first to sixth rolls, and the wrap angle. Represents a function. Further, P _shift can be represented by the sum of the movement amounts of the sink roll 5 and the lower support roll 6.

In the case of operating two support rolls, the amount of C-curvature at the rising of the upper support roll 7 is also ΔC ₇ = Q ₂ (P _shift ) ... (10) This is the plate thickness. , P, a function of P _shift determined by a tension, a yield stress, a warp amount in the first to seventh rolls, and a wrap angle. Therefore, the P _{shift at} which ΔC ₆ or ΔC ₇ becomes 0 is calculated using the equations (9) and (10).

Here, the moving amount of the sync roll 5 is (1
It can be calculated based on the equation (1). Moving amount of sink roll 5 = P _shift -Moving amount of lower support roll 6 (11)

Reference numeral 11 is a drive unit for the sink roll 5 and the lower support roll 6, and moves the sink roll 5 and the lower support roll 6 based on the moving amount of the sink roll 5 calculated by the shape control arithmetic unit 10.

As described above, the P _{shift at} which ΔC = 0 is calculated by the convergence calculation using the relational expression between the wrapping angle of the roll and the C warp amount according to the operating state of the support rolls and the roll arrangement. The flatness of the steel sheet can be controlled with high accuracy by moving the sink roll based on the P _shift and performing presetting.

When an error occurs in presetting, the warp amount is calculated from the shape of the steel plate, and feedback control of the moving amount of the sink roll 5 at which the warp amount becomes 0 is performed.
It is possible to control the flatness of the steel sheet with higher accuracy.

FIG. 4 and FIG. 5 show an embodiment of the width direction basis weight control method of the second invention. Reference numeral 15 is a steel plate which is plated with a corrosion-resistant metal such as zinc or lead-tin and runs. Steel plate 1
5 passes through hot bridle rolls 1 to 4, goes around the sink roll 5 in the hot dip plating bath, is plated, and is raised while the shape is corrected by the lower support roll 6 and the upper support roll 7, and the gas wiping nozzle 8 and further. An electromagnetic wiping nozzle, which is installed as necessary, controls the coating weight to a predetermined amount and then ascends to reach the top roll 9.

The single operation of the support roll is a state in which the upper support roll 7 is separated from the steel plate 15 so as not to come into contact therewith, and the rolls in contact with the steel plate 15 are the sink roll 5 and the lower support roll 6. It is in a state. The two-roll operation of the support rolls is an operation state in which the rolls in contact with the steel plate 15 are the sink roll 5, the lower support roll 6, and the upper support roll 7.

Reference numeral 12 is a device for measuring the coating amount of the plated steel plate 15 in the plate width direction, which is installed above the gas wiping nozzle 8. Plate width direction scanning plating amount measuring device 12
Detects the fluorescent X-ray intensity by irradiating the traveling plated steel plate 15 with γ-rays or X-rays in the plate width direction, and measures the amount of each plating adhesion on the front and back surfaces in the steel plate width direction.

Numeral 13 is a shape calculation device, which is based on the following equation based on the following equations based on the amount of plating on the front and back surfaces of the steel plate in each width direction transmitted from the device for measuring the amount of plating plating in the plate width direction 12 and the gas wiping. The distance of the nozzle 8 is calculated and the steel plate shape is obtained. The factors that determine the adhesion amount are the strip passing speed V (m / min), the steel plate 15 to the gas wiping nozzle 8
Distance D (mm), gas wiping pressure P (kg / c
m ² ), steel plate surface properties, steel medium components, plate temperature immediately before entering the plating bath, plating components, plating bath temperature, steel plate size, etc., but gas wiping pressure P (kg / cm ² ) and plate passing speed V
(M / min), for factors other than the distance D (mm) from the steel plate 15 to the gas wiping nozzle 8, it is possible depending on the steel type or the influence of the adhesion amount on the variation is small, so P,
The adhered amount can be calculated accurately with V and D, and the relation W = F (P, V, D) (12) holds. F is the shape of the gas wiping nozzle,
Since it is a function that depends on the plating composition and the composition of the steel sheet, it can be determined by limiting the same equipment and plating composition.

By hot dip galvanizing, the adhesion amount is 30 to 200 g
In the case of / m ² , an adhesion amount regression model formula such as Formula (13) can be obtained. W = exp (K ₀ + K ₁ P + K ₂ V + K ₃ D) (13) Here, K _{0 to} K ₃ represent constants, which vary depending on the type of the steel plate 15. Although the steel plate shape can be calculated from the output of the adhesion amount meter on one side according to the equation (13), it is considered that there are other factors influencing the variation in the adhesion amount in the plate width direction in addition to the steel plate shape. In order to take out, the anti-symmetry of the front and back sides of the adhesion amount with respect to the shape of the plate is utilized, and P and V can be calculated as in the equation (14) using the front and back adhesion amount meter as the same front and back sides. However, in P, the front and back are often the same, but if there is a pressure difference between the front and back, it is necessary to correct the pressure. ΔD = (D ₁ −D ₂ ) / 2 = (lnW ₁ −lnW ₂ ) / 2K ₃ (14) Here, ΔD is the displacement amount when the center of the distance between the front and back gas wiping nozzles 8 is 0. , D ₁ is the distance from the front steel plate 15 to the gas wiping nozzle 8 position, and D ₂ is the back steel plate 15
~ Distance to gas wiping nozzle 8 position, W ₁ represents the amount of adhesion on the front surface of the steel plate 15, and W ₂ represents the amount of adhesion on the back surface of the steel plate 15. From this, the steel plate shape is obtained by the shape calculation device 13 using the equation (14).

Reference numeral 14 is a warp amount calculation device. The steel plate shape obtained by the shape calculation device 13 can be approximated by a function of a quartic equation such as the equation (15). _{G (x) = C 0 +} C 1 x + C 2 x 2 + C 3 x 3 + C 4 x 4 ......... (15) where, C ₀ -C ₄ is a constant, x is representative of the position of the plate width direction of the steel sheet shape . By using ΔD calculated using the adhesion amount output by the adhesion amount detector and x at that time, C _{0 to} C ₄
By determining, the function approximation of the steel plate shape becomes possible. Next, an extreme value is calculated in order to recognize the shape of the steel plate shape that is approximated by a quartic function.

In equation (15), which is the derivative of the quartic function, x is calculated such that G '(x) = 0. G ′ (x) = C ₁ + 2C ₂ x + 3C ₃ x ² + 4C ₄ x ³ (16) If the number of the extreme values calculated here is one, a simple warp 2
If there are three pieces, it is recognized as S-warp, and if three pieces, it is recognized as W-warp. next,
The amount of warpage is calculated.

As for the S-warp, as shown in FIG. 6, a warp of ΔC _DS , which is the amount of warp on the left side with respect to the center, and ΔC _WS , which is the amount of warp on the right side, is calculated. The absolute value of each warp amount can be calculated by the following formula. ΔC _DS = | ΔD _DS −ΔD _DS (pole) ｜ ………… (17) ΔC _WS = | ΔD _WS −ΔD _WS (pole) ｜ ……………… (18) where ΔC _DS is The amount of warp on the left side of the center, ΔC _WS is the amount of warp on the right side of the center, ΔD _DS is the quadratic function value at the leftmost edge position in the width direction, and ΔD _WS is the rightmost edge position in the width direction. Quadratic function value at, ΔD _DS (pole)
Is the quadratic function value at the extreme position on the left side in the width direction, ΔD
_WS (pole) is the quartic function value at the extreme position on the right side in the width direction.

Regarding the direction of the warp, when the derivative of the quartic function value near the extreme position is observed, it has a downward convex direction (+ warp) when it changes from negative to positive, and changes from positive to negative. It is recognized as a shape with upward convexity (-warp) when it is raised. In the case of W warp, as shown in FIG. 7, a center warp ΔC _C and an edge warp ΔC _E are calculated. First, ΔC _C and ΔC _E are calculated based on the following equations. Note that the direction of the warp is determined in the same manner as in the case of S-warp in the vicinity of the extreme values of the left extreme value, the central extreme value, and the right extreme value in the plate width direction.

The directionality is negative to positive (+) at the extreme value on the left side.
Warp), and positive to negative (-warp) at the center extreme value,
And when the extreme value on the right side is from negative to positive (+ warp) ΔD _DS (pole)> ΔD _WS (pole), ΔC _C = ΔD _CC (pole) -ΔD _WS (pole) ……………… ( 19) If ΔD _DS (pole) ≤ ΔD _WS (pole), then ΔC _C = ΔD _CC (pole) -ΔD _DS (pole) (20) ΔC _E is the larger of ΔC _DS and ΔC _WS I will do it. Here, ΔD _CC (pole) is a quartic function value at the extreme position in the center, and ΔC _DS and ΔC _WS are ΔC _DS = ΔD _DS −ΔD _DS (pole) ……………… (21) ΔC _It can be calculated as _WS = ΔD _WS −ΔD _WS (pole) ……………… (22).

The directionality is positive to negative (-warp) at the left extreme value, negative to positive (+ warp) at the central extreme value, and positive to negative (-warp) at the right extreme value. Case ΔD _DS (pole)> ΔD _WS (pole) If ΔC _C = ΔD _DS (pole) -ΔD _CC (pole) ……………… (23) If ΔD _DS (pole) ≤ ΔD _WS (pole) ΔC _C = ΔD _WS (pole) −ΔD _CC (pole) (24) ΔC _E is the larger of ΔC _DS and ΔC _WS . Here, ΔC _DS and ΔC _WS can be calculated by the following equations, respectively. ΔC _DS = ΔD _DS (pole) −ΔD _DS ………… (25) ΔC _WS = ΔD _WS (pole) −ΔD _WS ………… (26) The amount of warpage of the device that performs the above arithmetic processing The arithmetic unit 14.

Reference numeral 10 is a shape control arithmetic unit. As shown in FIG. 3, the wrapping angle generated between the two rolls, i-th roll and i + 1-th roll, can be geometrically calculated as in the equation (1). θ _i = cos ⁻¹ (A / B) ……………… (1) where A = H _i × [H _i ² + D _i ² − (d _i + d _{i + 1} ) (D _i + a) + a ² ] ^1/2 + (1/4) × (d _i + d _{i + 1} −2D _i ) × (d _i + d _{i + 1} + 2a) (2) B = H _i ² + (1/4) × (d _i + d _{i + 1} -2D _i ) ² (3) Here, H _i is the center distance between the i-th roll and the i + 1-th roll, and D _i is the i-th roll and the i + 1-th roll. The roll wrap amount of the roll, d _i is the roll diameter of the i-th roll, d _{i + 1} is the roll diameter of the i + 1-th roll, and a is the plate thickness.

When θ is calculated between the rolls, the overall wrap angle Θ of the steel plate on the i-th roll is Θ _i = θ _i-1 + θ _i (4). However, the wrap angle of the first roll is Θ ₂ = θ
_2, in the case of one support roll operations, the sixth roll winding angle is theta ₆ = theta _6, when the two support rolls operations, 7 th roll winding angle is theta ₇ = theta _7.

Next, the wrap angle and C for the i-th roll
The following relational expression holds with the amount of warpage. ΔC _i = (A ₁ Θ _i + A ₂ T / Y _P Θ _i + A ₃ a / Θ _i + A ₄ Y _P / a) + A ₅ Y _P Θ _i + A ₆ a ² / Θ _i + A ₇ a / Θ _i + A ₈ aY _P + A ₉ a ² + A ₁₀ ) ΔC _i-1 + A ₁₁ (5) where ΔC _i is the amount of C warpage at the i-th roll exit side, ΔC _i
C _i-1 is the amount of C warpage on the exit side of the i-1 th roll, Θ _i is the overall wrap angle of the i th roll, T is the tension, Y _P is the yield stress, a is the plate thickness, and A ₁ to A ₁₁ is a constant.

In the case of one support roll operation, the wrapping angles from the hot bridle roll 1 to the lower support roll 6 and the C warp amount on each roll exit side are calculated. In the case of two support operations, the hot bridle roll 1 ~ The wrapping angle to the upper support roll 7 and the amount of C warpage on the roll exit side are calculated.

Now, assuming that D ₅ = P _shift , in the case of the single operation of the support rolls, the amount of C-curvature at the rising side on the exit side of the lower support roll 6 is calculated by using the formulas (4) to (5). Then, when the wrap angle and the C warp amount of the rolls 1 to 6 are calculated, there is a relational expression like the expression (9). ΔC ₆ = Q ₁ (P _shift ) (9) This is a function of P _shift determined by the plate thickness, tension, yield stress, the amount of warpage in the first to sixth rolls, and the wrap angle. Represents Further, P _shift can be represented by the sum of the movement amounts of the sink roll 5 and the lower support roll 6.

In the case of the operation with two support rolls, the amount of C warp at the rising of the upper support rolls 7 is also ΔC ₇ = Q ₂ (P _shift ) ............ (10) This is the plate thickness, It represents a function of P _shift determined by the tension, the yield stress, the amount of warp in the first to seventh rolls, and the wrap angle.

In the case of S warp, the warp amount on the left side with respect to the center is ΔC _DS and the warp amount on the right side is Δ with respect to the center at a certain shape recognition timing.
If P _shift when C _WS is P _A , then ΔC _DS
The following relational expression holds for the P _shift and the C warp amount that minimize both ΔC _WS and ΔC _WS . In the case of one support roll operation, ΔC = Q ₁ (P _shift ) + (ΔC _DS + ΔC _WS ) −ΔC _A (27) Here, ΔC _A = Q ₁ (P _A ). Further, in the case of operating two support rolls, ΔC = Q ₂ (P _shift ) + (ΔC _DS + ΔC _WS ) −ΔC _A (28) where ΔC _A = Q ₂ (P _A ). From this, ΔC
Calculating the P _{shift at} which = 0, this is ΔC _DS and C _WS
P _shift that minimizes both. Also in the case of W warp, similarly, P _shift that minimizes both the center warp ΔC _C and the edge warp ΔC _E may be calculated.

Therefore, the moving amount of the sync roll 5 can be calculated based on the following equation. Moving amount of sink roll 5 = P _shift -Moving amount of lower support roll 6 (11)

Reference numeral 11 is a drive device for the sink roll 5 and the lower support roll 6, and moves the sink roll 5 and the lower support roll 6 based on the moving amount of the sink roll 5 calculated by the shape control arithmetic unit 10.

According to the above method, even if the shape estimated from the adhered amount is asymmetrical steel plate shape such as S-warp or W-warp depending on the operation state of the support roll and the roll arrangement, the total warp amount in the shape is shown. By calculating the amount of movement of the sink roll 5 that minimizes and moving the sink roll based on this, it is possible to minimize the unit weight variation in the width direction of the steel sheet.

FIGS. 8 and 9 show an embodiment of the width direction basis weight control method of the third invention. Reference numeral 15 is a steel plate which is plated with a corrosion-resistant metal such as zinc or lead-tin and runs. Steel plate 1
5 passes through hot bridle rolls 1 to 4, goes around the sink roll 5 in the hot dip plating bath, is plated, and is raised while the shape is corrected by the lower support roll 6 and the upper support roll 7, and the gas wiping nozzle 8 and further. An electromagnetic wiping nozzle, which is installed as necessary, controls the coating weight to a predetermined amount and then ascends to reach the top roll 9.

The single operation of the support roll is a state in which the upper support roll 7 is separated from the steel plate 15 so as not to come into contact therewith, and the rolls in contact with the steel plate 15 are the sink roll 5 and the lower support roll 6. It is in a state. The two-roll operation of the support rolls is an operation state in which the rolls in contact with the steel plate 15 are the sink roll 5, the lower support roll 6, and the upper support roll 7.

Reference numeral 16 is a C warp detector for detecting the amount of steel plate shape warp in the snout (the amount of steel plate shape warp occurring between the hot bridle roll 4 and the sink roll 5).

Reference numeral 10 is a shape control arithmetic unit. As shown in FIG. 3, the wrapping angle generated between the two rolls, i-th roll and i + 1-th roll, can be geometrically calculated as in the equation (1). θ _i = cos ⁻¹ (A / B) ……………… (1) where A = H _i × [H _i ² + D _i ² − (d _i + d _{i + 1} ) (D _i + a) + a ² ] ^1/2 + (1/4) × (d _i + d _{i + 1} −2D _i ) × (d _i + d _{i + 1} + 2a) (2) B = H _i ² + (1/4) × (d _i + d _{i + 1} -2D _i ) ² (3) Here, H _i is the center distance between the i-th roll and the i + 1-th roll, and D _i is the i-th roll and the i + 1-th roll. The roll wrap amount of the roll, d _i is the roll diameter of the i-th roll, d _{i + 1} is the roll diameter of the i + 1-th roll, and a is the plate thickness.

When θ is calculated between the rolls, the total wrapping angle Θ of the steel sheet on the i-th roll is Θ _i = θ _i-1 + θ _i (4). However, the wrap angle of the first roll is Θ ₂ = θ
_2, in the case of one support roll operations, the sixth roll winding angle is theta ₆ = theta _6, when the two support rolls operations, 7 th roll winding angle is theta ₇ = theta _7.

Next, the wrap angle and C for the i-th roll
The following relational expression holds with the amount of warpage. ΔC _i = (A ₁ Θ _i + A ₂ T / Y _P Θ _i + A ₃ a / Θ _i + A ₄ Y _P / a) + A ₅ Y _P Θ _i + A ₆ a ² / Θ _i + A ₇ a / Θ _i + A ₈ aY _P + A ₉ a ² + A ₁₀ ) ΔC _i-1 + A ₁₁ (5) where ΔC _i is the amount of C warpage at the i-th roll exit side, ΔC _i
C _i-1 is the amount of C warpage on the exit side of the i-1 th roll, Θ _i is the overall wrap angle of the i th roll, T is the tension, Y _P is the yield stress, a is the plate thickness, and A ₁ to A ₁₁ is a constant.

In the case of one support roll operation, the wrap angles of the hot bridle roll 1 to the lower support roll 6 and the amount of C warp on the roll exit side are calculated. In the case of two operation rolls, the hot bridle roll 1 ~ The wrapping angle to the upper support roll 7 and the amount of C warpage on the roll exit side are calculated.

Now, the shape warp amount detected by the C warp detector 16 corresponds to the outgoing side warp amount of the hot bridle roll 4, and is equal to ΔC ₄ . Therefore, _assuming that D ₅ = P _shift , in the case of operating one support roll, the C warp amount on the exit side of the lower support roll 6 uses ΔC ₄ measured by the C warp detector 16 and the formula (5). Then, when the wrap angle and the amount of C warp of the rolls 5 to 6 are calculated, a relational expression such as the expression (9) is obtained. ΔC ₆ = Q ₁ (P _shift ) (9) This is a function of P _shift determined by the plate thickness, tension, yield stress, the amount of warp in the fifth to sixth rolls, and the wrap angle. Represents Further, P _shift can be represented by the sum of the movement amounts of the sink roll 5 and the lower support roll 6.

In the case of the operation of two support rolls, the amount of C warp at the rising of the upper support roll 7 is also ΔC ₇ = Q ₂ (P _shift ) ............ (10) This is the plate thickness, P determined by tension, yield stress, ΔC ₄ and the amount of warp and wrap angle of the 5th to 7th rolls
Represents the _shift function.

Therefore, from the above, the warp amount of the steel plate shape at the nozzle position is predicted, and the P _{shift at} which ΔC ₆ or ΔC ₇ becomes 0 is calculated using the equations (9) and (10). .

Here, the moving amount of the sync roll 5 is (1
It can be calculated based on the equation (1). Moving amount of sink roll 5 = P _shift -Moving amount of lower support roll 6 (11)

Reference numeral 11 is a drive device for the sink roll 5, which moves the sink roll 5 and the lower support roll 6 based on the amount of movement of the sink roll 5 and the lower support roll 6 calculated by the shape control arithmetic unit 10.

As described above, the amount of shape warp in the snout is detected by the C warp detector installed in the snout according to the roll operating condition of the support roll and the roll warp angle and the amount of C warp are detected. By using the relational expression to predict the warp amount at the nozzle position, calculate P _shift such that the predicted warp amount becomes 0, and move the sink roll and the support roll based on the calculated P _shift , It is possible to control the flatness of the steel sheet with high accuracy and minimize the unit weight variation in the width direction of the steel sheet.

[0061]

Embodiments FIGS. 10 to 13 show an embodiment of the first invention.
Shown in Plate thickness 0.8 in one support roll operation
mm, width 1800 mm, hot-dip galvanized steel sheet, the shape of the steel sheet by manual intervention of the sink roll by the operator is shown in Fig. 10.
FIG. 11 shows the result of presetting by calculating the P _{shift at} which ΔC = 0 using the control model formula, moving the sink roll by using the driving device so that the obtained P _shift is obtained.

In the operation of two support rolls, hot-dip galvanized steel sheet having a thickness of 0.8 mm and a width of 1800 mm,
Fig. 12 shows the steel plate shape by the manual intervention of the operator's sink roll. Using the control model formula, ΔC = 0 P
FIG. 13 shows the result of presetting performed by calculating _shift , moving the sink roll using the drive device so as to obtain the obtained P _{shif t} .

Thus, according to the operating state of the support rolls and the roll arrangement, the relation P between the winding angle of the roll and the amount of C warpage is used to calculate P _shift such that ΔC = 0, and the calculated P _shift is calculated. By moving the sink roll based on _shift and performing presetting, it becomes possible to control the flatness of the steel sheet with high accuracy.

Embodiments of the second invention are shown in FIGS.
7 shows. During operation of one support roll, a hot-dip galvanized steel plate having a plate thickness of 0.8 mm and a plate width of 1200 mm was used to measure the amount of adhesion on each of the front and back surfaces by a plate width direction scanning measuring device,
The shape before shape correction estimated using the shape calculation device is shown in Fig. 1.
There are four.

[0065] than this, using the warpage calculation unit calculates the [Delta] C _DS, [Delta] C _WS in S warp, [Delta] C _DS, P is calculated from the shape processing device the P _Shift to minimize both the [Delta] C _WS, the resulting the results of the so straightening moving sink roll by the sink roll driving device so as to _shift shown in FIG. 15.

When two support rolls are in operation,
A hot-dip galvanized steel plate having a plate thickness of 0.8 mm and a plate width of 1200 mm was measured by measuring the amount of adhesion on each of the front and back surfaces by a plate width direction scanning measuring device, and the shape before shape correction estimated by the shape calculation device is shown in FIG. On the street.

[0067] than this, using the warpage calculation unit calculates the [Delta] C _C, [Delta] C _E in W warp, [Delta] C _C, calculated from the shape processing device the P _Shift to minimize both the [Delta] C _E,
FIG. 17 shows the result of shape correction by moving the sink roll by the sink roll driving device so as to obtain the obtained P _shift .

As described above, the shape estimated from the adhered amount according to the roll arrangement in the operating state of the support roll is S
Even in a laterally asymmetrical steel plate shape such as a warp or a W warp, the amount of movement of the sink roll is calculated so as to minimize the total amount of warpage in the shape, and the sink roll is moved based on this to calculate the width of the steel sheet in the width direction. The unit weight variation can be minimized.

18 to 2 shows an embodiment of the third invention.
It is shown in FIG. The shape before hot feed galvanized steel sheet having a thickness of 0.8 mm and a width of 1200 mm before the feedforward control is performed when one support roll is in operation is as shown in FIG. The amount of warp at the position of the gas wiping nozzle is estimated based on the amount of warp, and P _shift for flattening the shape at the nozzle position is calculated by the shape control arithmetic unit. the results were the cause straightening moving sink roll by the sink roll driving device so that the P _{Shif t} shown in FIG. 19.

When two support rolls were operated, the hot-dip galvanized steel sheet having a plate thickness of 0.8 mm and a plate width of 1200 mm, before feed-forward control, had a shape of
As shown in FIG. 20, the amount of warp in the snout is grasped by the C warp detector, and based on this, the amount of shape warp at the gas wiping nozzle position is estimated to flatten the shape at the nozzle position. FIG. 21 shows the result of calculating a different P _shift from the shape control arithmetic unit and performing shape correction by moving the sink roll by the sink roll driving device so as to obtain the obtained P _shift .

As described above, the amount of shape warp in the snout is detected by the C warp detector installed in the snout according to the operation state of the support roll and the roll arrangement, and the wrap angle and the amount of C warp of the roll are detected. By using the relational expression to predict the warp amount at the nozzle position, calculate P _shift such that the predicted warp amount becomes 0, and move the sink roll and the support roll based on the calculated P _shift , It is possible to control the flatness of the steel sheet with high accuracy and minimize the unit weight variation in the width direction of the steel sheet.

[0072]

According to the above-mentioned method for controlling areal weight of the present invention,
Even in the case of a steel plate shape having a simple warp or a left-right asymmetrical steel plate shape, by simply operating the sink roll and the support roll, it is possible to control the unit weight variation in the steel plate width direction to the minimum and obtain a homogeneous plated steel plate. be able to.

[Brief description of drawings]

FIG. 1 shows a configuration of a width direction basis weight control method when operating a single support roll in the first invention.

FIG. 2 shows a configuration of a width direction basis weight control method when operating two support rolls in the first invention.

FIG. 3 shows a relationship of a wrapping angle between rolls in the first invention to the third invention.

FIG. 4 shows a configuration of a width direction basis weight control method at the time of operating a single support roll in the second invention.

FIG. 5 shows a configuration of a width direction basis weight control method when operating two support rolls according to a second aspect of the invention.

FIG. 6 shows the relationship between the definition of the amount of S-warp and the directionality of the warp in the second invention.

FIG. 7 shows the relationship between the definition of the warp amount of the W warp and the directionality of the warp in the second invention.

FIG. 8 shows a configuration of a width direction basis weight control method when operating a single support roll in a third aspect of the invention.

FIG. 9 shows a configuration of a width direction basis weight control method when operating two support rolls in the third invention.

FIG. 10 shows an example of a steel plate shape when a sink roll is manually preset with a hot-dip galvanized steel plate having a plate thickness of 0.8 mm and a plate width of 1800 mm in the single operation of the support roll in the first invention.

FIG. 11 is a P _shift at which ΔC = 0 in a control model formula for a hot-dip galvanized steel sheet having a sheet thickness of 0.8 mm and a sheet width of 1800 mm in a single operation of the support roll in the first invention.
_Is calculated, the sink roll is moved so as to obtain the obtained P _shift , and an example of the steel plate shape after presetting is shown.

FIG. 12 shows an example of a steel plate shape when a sink roll is manually preset with a hot-dip galvanized steel plate having a plate thickness of 0.8 mm and a plate width of 1800 mm in the operation of two support rolls in the first invention.

FIG. 13 is a P _shift at which ΔC = 0 when a control model formula is used for a hot-dip galvanized steel sheet having a sheet thickness of 0.8 mm and a sheet width of 1800 mm in the operation of two support rolls in the first invention.
_Is calculated, the sink roll is moved so as to obtain the obtained P _shift , and an example of the steel plate shape after presetting is shown.

FIG. 14 is a plate thickness 0.8 mm and a plate width 120 in the second invention.
An example of the shape of a 0 mm hot-dip galvanized steel sheet after control when one support roll is operated is shown.

FIG. 15 is a plate thickness 0.8 mm and a plate width 120 in the second invention.
An example of the shape of a 0 mm hot-dip galvanized steel sheet after control when one support roll is operated is shown.

FIG. 16 is a plate thickness 0.8 mm and a plate width 120 in the second invention.
An example of the shape of a 0 mm hot-dip galvanized steel sheet before control when two support rolls are operated is shown.

FIG. 17: Plate thickness 0.8 mm, plate width 120 in the second invention
An example of the shape of the 0 mm hot-dip galvanized steel sheet after control when two support rolls are operated is shown.

FIG. 18 is a plate thickness 0.8 mm and a plate width 120 in the third invention.
An example of the shape of a 0 mm hot-dip galvanized steel sheet after control when one support roll is operated is shown.

FIG. 19 shows a plate thickness 0.8 mm and a plate width 120 in the third invention.
An example of the shape of a 0 mm hot-dip galvanized steel sheet after control when one support roll is operated is shown.

FIG. 20 shows a plate thickness of 0.8 mm and a plate width of 120 in the third invention.
An example of the shape of a 0 mm hot-dip galvanized steel sheet before control when two support rolls are operated is shown.

FIG. 21 shows a plate thickness 0.8 mm and a plate width 120 in the third invention.
An example of the shape of the 0 mm hot-dip galvanized steel sheet after control when two support rolls are operated is shown.

[Explanation of symbols]

1-4 Hot bridle rolls 5 Sink rolls 6 Lower support rolls 7 Upper support rolls 8 Gas wiping nozzles 9 Top rolls 10 Shape control calculation device 11 Sync roll and support roll drive device 12 Plating amount measuring device 13 Shape calculation device 14 Warp Quantity calculation device 15 Steel plate 16 C Warp detector H _i Center distance between i-th roll and i + 1-th roll H _{i + 1} i + 1 roll-center distance between i + 2nd roll D _i i-th roll and i + 1 th roll lapping amount D i _{+ 1} i _{+ 1} th roll and i + 2 th roll lapping amount d i _i-th roll diameter d i _{+ 1} i _{+ 1} th roll diameter d i _{+ 2} i + 2 th roll roll roll roll Diameter of the rolls of the rolls θ _{i The} wrapping angle θ _{i + 1} generated by the i th roll and the i + 1 th roll The wrap angle generated by the i + 1st roll and the i + 2nd roll Θ _{i + 1} The overall wrap angle of the _{i + 1st} roll

Continuation of the front page (72) Inventor, Jitsuta Miyakoshi 1-1, Hibahata-cho, Tobata-ku, Kitakyushu, Fukuoka Prefecture New Nippon Steel Corporation Yawata Works

Claims (3)

[Claims] 1. A method for controlling a basis weight of a plated steel sheet traveling from a hot bridle roll through a sink roll or a support roll in a hot dip plating bath, the formula (1) is used geometrically from a roll arrangement, The θ between the rolls is calculated, the wrap angle Θ of the steel plate on the i-th roll is obtained from the equation (4), and the wrap angle on the i-th roll and the C-curvature amount on the roll-out side are shown. From the formula (5), the relational expression (6) of the amount of C warp in each roll is defined as P _shift , which is the sum of the movement amount of the sink roll and the movement amount of the lower support roll.
As shown in the formula, presetting is performed using a shape control arithmetic device that calculates P _shift that is obtained as a function of P _shift and ΔC = 0 and a drive device that moves the sink roll based on the calculated P _shift , A method for controlling a basis weight of a hot dip plated steel sheet, characterized in that the flatness of the steel sheet is controlled with high accuracy to minimize the variation in the basis weight of the steel sheet. θ _i = cos ⁻¹ (A / B) …………………… (1) where A = H _i × [H _i ² + D _i ² − (d _i + d _{i + 1} ) (D _i + a) −a ² ] ^1/2 + (1/4) × (d _i + d _{i + 1} −2D _i ) × (d _i + d _{i + 1} +2 a) ... (2) B = H _i ² + (1/4) × (d _i + d _{i + 1} −2D _i ) ² (3) H _i : Center distance between i-th roll and i + 1-th roll D _i : i-th roll and i + 1-th roll Roll wrap amount d _i : Roll diameter of i-th roll d _{i + 1} : Roll diameter of i + 1-th roll a: Plate thickness Θ _i = θ _i-1 + θ _i …………………… (4) ΔC _i = (A ₁ Θ _i + A ₂ T / Y _P Θ _i + A ₃ a / Θ _i + A ₄ Y _P / a) + (A ₅ Y _P Θ _i + A ₆ a ² / Θ _i + A ₇ a / Θ _i + A ^{_{8 aY P + a 9 a 2}} + a 10) ΔC i-1 + a 11 ........................ (5) However, [Delta] C _i: out i-th roll C warpage in _{(mm) ΔC i-1:} C warpage at (i-1) -th roll exit side (mm) theta _i: winding angle of the i-th roll (deg) T: tension (kg / mm ² ) Y _P : Yield stress (kg / m ² ) A ₁ to A ₁₁ : Constant ΔC = Q (P _shift ) …………………… (6) 2. The intensity of fluorescent X-rays received by irradiating γ-rays or X-rays in the width direction of the plated steel sheet traveling from the hot dip bath through the gas wiping area is detected, and each of the front and back surfaces in the steel sheet width direction is detected. A plate width direction scanning plating deposition amount measuring device for measuring the plating deposition amount, and a shape calculation device for obtaining a steel plate shape based on the equation (7) from each plating deposition amount on the front and back surfaces in each width direction of the steel plate. , The obtained steel plate shape is approximated by a function of a quartic equation, the extreme value of the quartic function is calculated, the shape of the steel plate shape is recognized from the number of calculated extreme values, and the warp amount is calculated. The quantity calculation device and the arrangement of the rolls are used to calculate θ between the rolls geometrically using the formulas (1) to (3), and the wrapping angle Θ of the steel plate on the i-th roll is calculated by 4) and calculate the sum of the moving amount of the sink roll and the moving amount of the lower support roll by P _{sh As the ift} , using the relational expression (5) of the C warp amount on each roll output side, the warp amount on the support roll output side is calculated as in the expression (6), and the estimated shape is left-right asymmetrical. If, then a model formula that minimizes the absolute amount of warpage is obtained as in formula (8),
It is composed of a shape control calculation device that calculates a P _{shift at} which ΔC = 0 and a drive device that drives a sink roll so that the calculated P _shift is obtained. The estimated shape is
Even in a laterally asymmetrical steel plate shape such as S-warp or W-warp, the amount of movement of the sink roll that minimizes the overall amount of warp in the shape is calculated, and the sink roll is moved based on this to calculate the width direction of the steel sheet. Of the unit weight of the hot-dip galvanized steel sheet in the width direction. ΔD = (lnW ₁ −lnW ₂ ) / K (7) where ΔD: Displacement amount (mm) when the center of the distance between the front and back gas wiping nozzles is 0 (mm) W ₁ : Steel sheet surface Adhesion amount (g / m ² ) W ₂ : Adhesion amount on the back of the steel sheet (g / m ² ) K: Constant that varies depending on the type of steel sheet θ _i = cos ⁻¹ (A / B) ………………… (1) However, A = H _i × [H _i ² + D _i ² − (d _i + d _{i + 1} ) (D _i + a) −a ² ] ^1/2 + (1/4) × (d _i + d _{i +1} −2D _i ) × (d _i + d _{i + 1} +2 a) ... (2) B = H _i ² + (1/4) × (d _i + d _{i + 1} −2D _i ) ² (3) H _i : Distance between centers of i-th roll and i + 1-th roll D _i : Roll wrap amount of i-th roll and i + 1-th roll d _i : Roll diameter of i-th roll d _{i + 1} : i + 1-th roll roll diameter a: plate thickness _{Θ i = θ i-1 +} θ i ..................... (4 _{ΔC i = (A 1 Θ i} + A 2 T / Y P Θ i + A 3 a / Θ i + A 4 Y P / a) + A 5 Y P Θ i + A 6 a 2 / Θ i + A 7 a / θ i + A 8 aY _P + A ₉ a ² + A ₁₀ ) ΔC _i-1 + A ₁₁ (5) However, ΔC _i : C warp amount (mm) ΔC _i-1 : i at the _i- th roll exit side -1 C roll amount on the delivery side of the roll (mm) Θ _i : Wrap angle of the i-th roll (deg) T: Tension (kg / mm ² ) Y _P : Yield stress (kg / m ² ) A ₁ To A ₁₁ : constant ΔC = Q (P _shift ) ……………… (6) ΔC = Q (P _shift ) + (ΔC _DS + ΔC _WS ) −ΔC _A ………… (8) However, ΔC = Q (P _shift): sheet thickness, tension, P _Shift determined by warpage and winding angle at the yield stress and the rolls
Function of ΔC _DS : Warp amount on the left side with respect to the center of S warp (m
m) (In case of W warp, ΔC _C : Corresponds to center warp) ΔC _WS : In the case of S warp, the amount of warp on the right side with respect to the center (m
m) (ΔC _E in case of W warp: Corresponding to edge warp) ΔC _A : Q during P _shift when recognizing the shape and calculating the warp amount
(P _shift ) 3. A method for controlling the areal weight of a plated steel sheet, which travels from a C warp detector for measuring the shape of a steel sheet in a snout and a hot bridle roll through a sink roll or a support roll in a hot dip bath, to determine the geometrical shape from the roll arrangement. Mathematically, using the formula (1), θ is calculated between each roll, and i
The wrapping angle Θ of the steel plate at the th roll is obtained from the formula (4), and from the formula (5) showing the relationship between the wrapping angle at the i-th roll and the amount of C warpage on the roll-out side, the sink roll Using the relational expression (6) of the C warp amount in each roll, where the sum of the moving amount and the moving amount of the lower support roll is P _shift ,
The amount of warp on the support roll outlet side is calculated as in equation (6), and the amount of warpage measured by the C warp detector installed in the snout is used to calculate the amount of warp on the support roll outlet side from equation (6). predicting the amount of warpage, the drive sink roll and support roll is the bath roll thus becomes P _Shift shape processing device and the calculated to calculate the P _Shift such that the predicted warp amount [Delta] C = 0 A drive device that drives the sink rolls and supports that predict the warp amount of the support roll from the steel plate shape inside the snout and minimize the warp amount of the support roll according to the operating condition of the support roll and the roll arrangement. Hot-dip galvanized steel characterized by minimizing the variation in the basis weight of the steel sheet by calculating the amount of roll movement and moving the sink roll or support roll based on this Width direction basis weight control methods. θ _i = cos ⁻¹ (A / B) …………………… (1) where A = H _i × [H _i ² + D _i ² − (d _i + d _{i + 1} ) (D _i + a) −a ² ] ^1/2 + (1/4) × (d _i + d _{i + 1} −2D _i ) × (d _i + d _{i + 1} +2 a) ... (2) B = H _i ² + (1/4) × (d _i + d _{i + 1} −2D _i ) ² (3) H _i : Center distance between i-th roll and i + 1-th roll D _i : i-th roll and i + 1-th roll Roll wrap amount d _i : Roll diameter of i-th roll d _{i + 1} : Roll diameter of i + 1-th roll a: Plate thickness Θ _i = θ _i-1 + θ _i …………………… (4) ΔC _i = (A ₁ Θ _i + A ₂ T / Y _P Θ _i + A ₃ a / Θ _i + A ₄ Y _P / a) + (A ₅ Y _P Θ _i + A ₆ a ² / Θ _i + A ₇ a / Θ _i + A ^{_{8 aY P + a 9 a 2}} + a 10) ΔC i-1 + a 11 ........................ (5) However, [Delta] C _i: out i-th roll C warpage in _{(mm) ΔC i-1:} C warpage at (i-1) -th roll exit side (mm) theta _i: winding angle of the i-th roll (deg) T: tension (kg / mm ² ) Y _P : Yield stress (kg / m ² ) A ₁ to A ₁₁ : Constant ΔC = Q (P _shift ) …………………… (6)