JPH08260122A - Method for controlling coating weight of hot-dipped steel sheet - Google Patents

Abstract

(57) [Summary] [Purpose] The amount of adhesion in the width direction of the steel sheet can be adjusted by operating the front and back gas wiping nozzles individually on the front and back sides in the variation in the amount of adhesion in the width direction when the front and back sides of the steel sheet are twisted. To make it uniform. [Structure] A plating operation amount measuring device for operating the width direction for measuring the adhesion amount of the steel plate in the width direction, and a gap calculating device for calculating the distance between the steel plate and the gas wiping nozzle from the adhesion amount value measured by the operation. It is composed of a twist amount calculation device that determines the left and right operation amount of the gas wiping nozzle and a left and right individual advancing and retracting drive device that moves the gas wiping nozzle by approximating the calculated value with a linear function, and determines the adhesion amount in the width direction of the steel plate. Control evenly.

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 the control of the amount of adhesion in order to even out the variation in the areal weight of the steel sheet in the width direction.

[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. Among them, galvanized steel sheets or their alloyed galvanized steel sheets have excellent corrosion resistance and weldability. It is often used as a material for automobiles and home appliances. Such hot-dip galvanized steel sheet is generally a hot-rolled or cold-rolled steel sheet that passes through a preliminary oxidation furnace, a reduction annealing furnace, and then a cooling furnace, passes through a hot-dip galvanizing bath, and is in a molten state on the surface. The metal is wiped with a gas wiping nozzle while being controlled to a predetermined adhesion amount, and if necessary, further passed through an alloying heating furnace to manufacture.

However, the amount of plated metal deposited on the manufactured hot dip plated steel sheet has a large variation in the width direction, and there is a problem that the weldability or the close coatability is impaired. Such a problem can be solved by depending on the distance between the steel plate and the gas wiping nozzle and 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 plate, as in JP-A-3-17249 and JP-A-3-138344, a sink roll and a support roll are provided depending on the plate thickness and plate width of the steel plate to be plated. There has been proposed a method of correcting the shape at the gas wiping nozzle position by adjusting the amount of pushing in to an appropriate value.

However, in such a method, the shape in which the steel sheet is in a twisted state with respect to the gas wiping nozzle cannot be corrected, so that the distance between the steel sheet and the gas wiping nozzle is not constant in the width direction, and the adhesion in the width direction is caused. Unable to eliminate the quantity variation.

Further, as in Japanese Patent Laid-Open No. 6-166696, the shape at the gas wiping nozzle position is estimated from the difference in the adhesion amount values in the front and back width directions, and the front and back gas wiping nozzles are set so as to be parallel to the shape. With respect to the driving method, when the variation in the adhesion amount in the width direction occurs without depending on the shape, the method of driving the front and back gas-wai pink sozzles in parallel to the estimated shape may be inappropriate.

[0007]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art. Even when the variation in the amount of adhesion in the width direction is in a twisted state, the amount of adhesion in the width direction is twisted. , The front and back sides of the gas wiping nozzle are individually operated to uniformly control the adhesion amount in the width direction of the front and back sides.

[0008]

As a first aspect of the present invention, as a first aspect of the present invention, a steel sheet is passed through a hot dip plating bath to wipe a molten plating metal adhering to the surface thereof with a gas wiping nose while controlling a predetermined basis weight. In the hot metal plating method of
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 the amount of coating adhesion at each position on the front and back surfaces in the steel sheet width direction is detected. The width-direction scanning plating deposition amount measuring device and the gas wiping nozzle are configured to be able to be driven individually on the front and back sides, while the operation amount on the front and back sides of the gas wiping nozzle is set appropriately according to the deposition amount on the front and back sides in the width direction. Is a method for uniformly controlling the amount of adhesion in the width direction on each of the front and back sides by adjusting the value to a desired value.
In a hot-dip galvanizing method for a steel sheet, which passes through a hot-dip galvanizing bath and wipes the hot-dip galvanized metal adhering to the surface with a gas wiping nozzle, a predetermined wiping amount is controlled. Width-direction scanning plating adhesion amount that detects the fluorescent X-ray intensity received by irradiating γ-rays or X-rays in the width direction of the plated steel plate running through and measuring the plating adhesion amount at each position on the front and back surfaces of the steel plate width direction Based on the following formula (2) from the measurement device and the measured plating adhesion amount at each position of the steel plate according to the following formula (2), the distance from the tip of each gas wiping nozzle to the steel plate is calculated in the width direction and the gap calculation device. Using the value of the distance from the gas wiping nozzle tip to the steel plate at each position, a linear function approximation is performed to calculate the width-direction adhesion amount twist for each of the front and back sides,
Based on the twist amount calculation device that determines the left and right operation amount of the gas wiping nozzle using this value, and the left and right operation amount obtained from this, it consists of a left and right individual advancing and retracting drive device for moving each of the front and back gas wiping nozzles. This is a method of making the amount of adhesion on each of the front and back sides of the steel sheet in the width direction uniform.

D = [lnW- (K ₀ + K ₁ × P + K ₂ × V)] / K ₃ (2) However, D: Distance from the front and back of each gas wiping nozzle tip to the steel plate (mm) W: Coating amount on each surface (g / m ² ) P: Gas wiping nozzle pressure on each surface (Kg /
cm ² ) V: Plate passing speed (m / min) K _{0 to} K ₃ : Constants that differ depending on the steel plate material

[0010]

FIG. 1 shows an example of the widthwise adhesion amount control device of the present invention.

In the figure, reference numeral 1 is a steel plate which is plated with a corrosion-resistant metal such as zinc or lead-tin and runs.

The steel plate 1 is a sink roll 2 in a hot dip bath.
And is raised while the shape is corrected by the lower support row 3 and the upper support roll 4, and is controlled to a predetermined amount by the gas wiping nozzle 5 and an electromagnetic wiping nozzle that is installed as necessary.

Reference numeral 6 is a device for measuring the coating amount of the plated steel plate 1 in the plate width direction, which is installed above the gas wiping nozzle 5.

The plate width direction scanning plating amount measuring device 6 is
The fluorescent X-ray intensity is detected by irradiating the traveling plated steel plate 1 with γ-rays or X-rays in the plate width direction, and the amount of each plated coating on the front and back surfaces in the steel plate width direction is measured.

According to the first aspect of the present invention, the operation amount of each of the front and back sides of the gas wiping nozzle 5 is adjusted according to each plating deposition amount on the front and back sides in the steel sheet width direction measured by the plate width direction scanning plating deposition amount measuring device 6. Is a method of uniformly controlling the amount of adhesion on each of the front and back sides by adjusting to an appropriate value.

An embodiment of the widthwise adhesion amount control device in the second aspect of the present invention is the control device described above with the following devices added. That is, reference numeral 7 denotes a gap calculation device, which is based on the following formula based on the following equations based on the plating adhesion amount on the front and back surfaces of each steel plate in the width direction transmitted from the plate width direction scanning plating adhesion amount measuring device 6: To calculate the distance.

Factors that determine the adhered amount are the sheet passing speed V (m / min), the distance D (mm) from the steel plate 1 to the Geis wiping nozzle 5, and the gas wiping pressure P (Kg / cm).
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 ), plate passing speed V (m / Min), and for factors other than the distance D (mm) from the steel plate 1 to the gas wiping nozzle 5, because of the type of steel, or the influence of the adhered amount on variations is small,
The adhesion amount can be calculated accurately with P, V and D, and the relation W = F (P, V, D) (3) 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. For example, hot-dip galvanized coating amount 30-200g
In the case of / m ² , an adhesion amount regression model formula such as formula (4) can be obtained.

W = exp (K ₀ + K ₁ × P + K ₂ × V + K ₃ × D) (4) Here, K _{0 to} K ₃ represent constants, which vary depending on the type of the steel sheet 1.

The amount of adhesion on each of the front and back sides of the steel plate 1 was measured using a plate width direction scanning plating adhesion amount measuring device 6, and the adhesion in which the front and back of the steel plate 1 were twisted from the detected width direction. In order to determine the amount variation and to calculate the left / right operation amount for increasing / decreasing the distance between the gas wiping nozzle 5 and the steel plate 1 front / back surface of the gas wiping nozzle 5 so as to reduce the variation in the adhesion amount between the front and back sides, the twists of the front and back sides are calculated. The variation in the adhered amount in the state is converted back into the distance from the tip of the gas wiping nozzle 5 to the steel plate 1 by using the equation (5) derived by transforming the equation (4).

D = [lnW- (K ₀ + Kl × P + K ₂ × V)] / K ₃ ··· (5) However, D: Distance from the tip of each gas wiping nozzle to the steel plate (mm) W: Both front and back Plating adhesion amount (g / m ² ) P: Gas wiping nozzle pressure for each front and back (Kg /
cm ² ) V: Plate passing speed (m / min) K _{0 to} K ₃ : Constants that differ depending on the material of the steel plate Therefore, from the gap computing device 7 using the formula (5), the steel plate 1 from the tip of each gas wiping nozzle 5 The distance can be calculated.

Using the distance G (x) from the tip of the gas wiping nozzle 5 to the steel sheet 1 calculated in the width direction of each of the front and back sides calculated by the gap calculation device 7 and the traverse position x corresponding thereto, a linear function approximation is performed. It can be expressed in a form like the formula (6). Note that equation (6)
C ₁ in each represents the amount of twist in the width direction adhesion amount.

G (x) = C ₀ + C ₁ x (6) However, x: traverse position C ₀ , C ₁ : constant Therefore, it is equal to the width direction adhesion amount twist amount. The left and right operation amounts of the front and back gas wiping nozzles 5 are determined so that That is, the left / right operation amount of the front / back gas wiping nozzle 5 can be determined based on the equations (7) to (10).

ΔS _omote (left) = C _{1 omote} × d / 2 (7) ΔS _omote (right) = − C _{1 omote} × d / 2 (8) ΔS _ura (Left) = C _{1 ura} × d / 2 ··· (9) ΔS _ura (Right) = −C _{1 ura} × d / 2 _··· (10) However, ΔS _omote (Left) : _{Increase /} decrease in the operation amount on the left side of the front gas wiping nozzle ΔS _omote (right): _{Increase /} decrease in the operation amount on the right side of the front gas wiping nozzle ΔS _ura (left): _{Increase /} decrease in the operation amount on the left side of the back gas wiping nozzle Δ S _ura (right): _{Increase /} decrease in the amount of operation on the right side of the back gas wiping nozzle C _{1 omote} : A linear function using the distance from the tip of the gas wiping nozzle calculated from the amount of surface adhesion to the steel plate and the traverse position corresponding to it the inclination of when approximated (table width direction adhesion amount twist min) C _{1 ura:} calculated from the back coating weight gas Tilt when linear function is approximated using the distance from the tip of the ipping nozzle to the steel plate and the traverse position corresponding to it (the amount of twist in the back width direction) d: Gas wiping nozzle length ± direction: + is gas The direction in which the wiping nozzle is widened is the direction in which the gas wiping nozzle is contracted.
_omote (left), ΔS _omote (right), ΔS _ura (left), Δ
S _ura (right) is calculated, and the increase / decrease in the operation amount of each of the left and right gas wiping nozzles 5 is calculated. Reference numeral 9 denotes a laterally advancing / retreating drive control device for the front and back gas wiping nozzles 5, which is ΔS calculated by the twist amount computing device 8.
_omote (left), ΔS _omote (right), ΔS _ura (left), Δ
5 front and back gas wiping nozzles to become S _ura (right)
The gas wiping nozzle advance / retreat drive device 10 such as a hydraulic cylinder or a screw screw is operated on each of the left and right sides of the.

As described above, the front and back gas wiping nozzles 5 are individually operated on the left and right sides to produce the steel plate 1.
Even in the variation in the adhesion amount in the width direction in each of the front and back sides, the adhesion amount can be uniformly controlled in the width direction of the steel sheet.

[0025]

【Example】

[Example 1] In a hot-dip galvanized steel sheet having a plate thickness of 2.0 mm and a plate width of 1377 mm, the adhesion amount regression model formula, that is, the formula (3) coefficient takes the following values.

K ₀ = 3.02, K ₁ = -0.8, K ₂ =
0.01, K ₃ = 0.06 Using the scanning width deposition amount measuring device 6 in the plate width direction, variations in the deposition amount on the front and back sides are shown in FIG.
Further, the distance from the tip of each gas wiping nozzle 5 to the steel plate 1 on each of the front and back sides is calculated from the adhesion amount value detected by the plate width direction scanning plating adhesion amount measuring device 6 using the gap calculating device 7, and the twist amount calculating device 8 When a linear function approximation is performed using, a straight line as shown in FIG. 3 is obtained.

The twist amount calculation device 8 is used to calculate the increase / decrease in the operation amount of each of the left and right gas wiping nozzles 5 on the front and back sides, and the front and back gas wiping nozzle left and right drive devices 10 are used to individually control the front and back sides. FIG. 4 shows the results of carrying out the control of the adhered amount by carrying out the operation.

In this case, ΔS _omote (left) = 2.98 m
m, ΔS _omote = −2.98 mm, ΔS _ura (left) = −
3.84 mm, ΔS _ura (right) = − 3.84 mm.

As a result, the adhered amount becomes as shown in FIGS. 2 to 4, and even when the adhered amount varies in the width direction when the front and back of the steel plate 1 are twisted, the adhered amount in the width direction of the steel plate 1 is highly accurate. Can be controlled.

When the conventional technique is used, the difference between the maximum value and the minimum value of the adhesion amount in the width direction of the steel sheet is 20 g / m ² , whereas when the present invention method is used, The difference between the maximum value and the minimum value can be controlled within 5 g / m ² .

[Example 2] Plate thickness: 1.5 mm, plate width: 160
In a 0 mm hot-dip galvanized steel sheet, the adhesion amount regression model equation, that is, the coefficient of equation (3), takes the following values.

K ₀ = 2.85, K ₁ = -0.95, K ₂
= 0.015, using K ₃ = 0.07 sheet width direction scanning coating weight measuring device 6 is as shown in FIG. 5 when indicating each deposition amount variation sides. Further, the distance from the tip of each gas wiping nozzle 5 to the steel plate 1 on each of the front and back sides is calculated from the adhesion amount value detected by the plate width direction scanning plating adhesion amount measuring device 6 using the gap calculating device 7, and the twist amount calculating device 8 When a linear function approximation is performed using, a straight line as shown in FIG. 6 is obtained.

The twist amount calculation device 8 is used to calculate the increase / decrease of the operation amount of each of the left and right gas wiping nozzles 5 of the front and back, and the front and back gas wiping nozzles are driven to move forward and backward individually for the front and back respectively. FIG. 7 shows the result of performing the operation to control the adhesion amount.

In this case, ΔS _omote (left) = − 3.40
mm, ΔS _omote (right) = 3.40 mm, ΔS
_ura (left) = 3.94 mm, ΔS _ura (right) = − 3.9
It is 4 mm.

As a result, the amount of adhesion becomes as shown in FIGS. 5 to 7, and even if the amount of adhesion varies in the width direction when the front and back sides of the steel plate 1 are in a twisted state, the adhesion is high in the width direction of the steel plate 1. You can control the quantity.

When the conventional technique is used, the difference between the maximum value and the minimum value of the adhesion amount in the width direction of the steel sheet is 50 g / m ² , whereas when the present invention method is used, the maximum adhesion amount is reduced. The difference between the value and the minimum value can be controlled within 15 g / m ² .

[0037]

According to the present invention, the gas wiping nozzles are individually operated on the right and left sides of the front and back sides even when the variation in the coating amount in the width direction is in a twisted state, based on the coating amount values in the width direction on the front and back sides of the steel sheet. As a result, it is possible to uniformly control the coating amount of each of the front and back sides of the steel sheet in the width direction, and it is possible to process the hot-dip galvanized steel sheet without variations in the width direction.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an adhesion amount control device according to the present invention.

FIG. 2 is a diagram showing a variation state of the adhesion amounts on the front and back sides before control, which is measured using a plate width direction scanning plating adhesion amount measuring device in [Example 1].

FIG. 3 is a diagram showing a state in which a linear function approximation is performed from the adhesion amount value of FIG. 2 using a gap amount calculation device.

FIG. 4 In [Example 1], a twist amount calculator is used to calculate an increase / decrease in the amount of movement of each of the right and left gas wiping nozzles, and the front / back gas wiping nozzle left / right drive device is used to calculate the front / back. It is a figure which shows the state of the variation of the adhesion amount as a result of performing the adhesion amount control by operating each left and right individually.

FIG. 5 is a diagram showing a variation state of the respective adhered amounts on the front and back sides before control, which is measured by using a plate width direction scanning plating adhered amount measuring device in [Example 2].

6 is a diagram showing a state in which a linear function approximation is performed from the adhesion amount value of FIG. 5 using a gap amount calculation device.

[Example 2] In [Example 2], a twist amount calculation device is used to calculate an increase / decrease in the amount of movement of each of the front and back gas wiping nozzles, and the front and back gas wiping nozzles are used to move forward and backward. It is a figure which shows the state of the variation of the adhesion amount as a result of performing the adhesion amount control by operating each left and right individually.

[Explanation of symbols]

 1 steel plate 2 sink roll 3 lower support roll 4 upper support roll 5 gas wiping nozzle 6 plate width direction scanning plating amount measuring device 7 gap calculator 8 twist amount calculator 9 gas wiping nozzle advancing / retreating drive controller 10 gas wiping nozzle advancing / retreating drive apparatus

Claims (2)

[Claims] 1. A hot-dip galvanizing method for a steel sheet, wherein a hot-dip galvanizing bath is passed through a hot-dip galvanizing bath to wipe a hot-dip galvanizing metal on a surface with a gas wiping nozzle to control a predetermined basis weight. Width to measure the amount of plating adhered at each position on the front and back sides of the steel sheet width direction by detecting the intensity of fluorescent X-rays that are received by irradiating γ-rays or X-rays in the width direction of the plated steel sheet traveling through the gas wiping area from Directional scanning plating deposition amount measuring device and gas wiping nozzle can be driven individually on the front and back sides, while the operation amount on the front and back sides of the gas wiping nozzle is set to an appropriate value according to the deposition amount in the width direction on each side. A method for controlling the adhesion amount of a hot dip plated steel sheet, wherein the adhesion amount in the width direction of each of the front and back is uniformly controlled by adjusting. 2. A hot-dip galvanizing method for a steel sheet, wherein the hot-dip galvanized metal that has passed through the hot-dip galvanized bath is wiped off by a gas wiping nozzle to control a predetermined basis weight. Width to measure the amount of plating adhered at each position on the front and back sides of the steel sheet width direction by detecting the intensity of fluorescent X-rays that are received by irradiating γ-rays or X-rays in the width direction of the plated steel sheet traveling through the gas wiping area from Directional scanning plating adhesion amount measuring device and gap calculating device for calculating the distance from the tip of each gas wiping nozzle to the steel plate based on the following formula (1) from the measurement plating adhesion amount at each position in the width direction of the steel plate And the value of the distance from the tip of the gas wiping nozzle to the steel plate at each position in the width direction,
Based on a linear function approximation, calculate the width direction adhesion amount twist amount on each of the front and back sides, and use this value to determine the left and right operation amount of the gas wiping nozzle based on the twist amount calculation device and the left and right operation amount obtained from it. A method for controlling the adhesion amount of a hot dip plated steel sheet, comprising a left and right individual advancing / retreating drive device for moving the gas wiping nozzles on the front and back sides, and averaging the adhesion amounts on the front and back sides of the steel sheet in the width direction. Equation (1): D = [lnW- (K 0 + K 1 × P + K 2 × V)] / K 3 where, D: distance sides from each of the gas wiping nozzle tip to the steel sheet (mm) W: front and back respectively of the plating Adhesion amount (g / m ² ) P: Gas wiping nozzle pressure (Kg /
cm ² ) V: Plate passing speed (m / min) K _{0 to} K ₃ : Constants that differ depending on the steel plate material