JPH06192806A - Method for controlling shape of hot-dip plated steel sheet - Google Patents

Abstract

PURPOSE:To control the flattening degree of a hot-dip plated steel sheet with high accuracy by finding the moving amt. of a sink roll so as to form the shape of the steel sheet into a flat one by using the relational formulae of the camber of the steel sheet. CONSTITUTION:In a running plated steel sheet, from the relational formulae in which the camber DELTAC of the steel sheet is expressed by the relationship of the primary formulae of the moving amt. of the sink roll such as the formulae I and II, the size of the steel sheet and intermeshes IM between the upper and lower support rolls are substituted to decide the coefficients of each term in the primary formulae. The formula I is the case in which the sheet thickness (mm) (a) satisfies a <=1.6, and the formula II is the case in which 1.6<=a<=3.2 is satisfied. In the formulae I and II, alpha1 to alpha8 and beta1 to beta7 denote constants different in accordance with the material of the steel sheet. Moreover, the moving amt. of the sink roll so as to flatten the shape of the steel sheet is calculated in accordance with the formula III. Thus, the sink roll is driven, and presetting is executed. In such a manner, the flattening degree of the steel sheet passing through a hot dip plating tank can be controlled with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape of a hot-dip steel sheet in which a steel sheet and a steel sheet coated with a plating metal such as Ni run through a hot-dip bath of a corrosion-resistant metal such as zinc, lead-tin, or aluminum. It relates to a control method.

[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 galvannealed steel sheets are excellent in 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 even cold-rolled steel sheet that passes through a preliminary oxidation furnace, then a reduction annealing furnace, and then a cooling furnace, and then turns around a sink roll in the hot dip bath to pass through a support roll. While being run while being supported by the, the plating metal in a molten state adhering to the surface is wiped with a gas wiping nozzle to control a predetermined basis weight, and if necessary, further produced through an alloying heating furnace. However, the coating weight of the manufactured hot dip plated steel sheet has a large variation due to the change in the shape in the sheet width direction, and there is a problem that the weldability or the close coatability is impaired. The problem of variation due to such a simple shape 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 corrected to the steel plate that changes into various shapes and runs. .

As a means for flattening the shape of the steel plate, a method of judging the steel plate shape by the operator's eyes and moving a sink roll, a support roll or a touch roll above the gas wiping in the plating bath, and before and after the position of the gas wiping nozzle By installing the shape detector, determine the steel plate shape near the gas wiping nozzle, control the gas wiping pressure and the operating end of the nozzle position, the method of correcting the shape in the steel plate width direction using electromagnetic force, There are a method of presetting the position of the sink roll or the support roll based on the actual data already operated, a method of introducing a process computer, and a method of presetting the position of the sink roll or the support roll according to the steel plate size, the material, and the like.

However, in such a steel plate width shape correcting method, a highly accurate shape detector is required, but since the molten metal is attached to the steel plate in the vicinity of the gas wiping nozzle, the contact type Due to the problem that the shape detector cannot be used, a laser or electromagnetic non-contact type shape detector is used. The laser type shape detector includes a light cutting method of irradiating laser light and a method of projecting reflected light of the irradiating laser light on a screen to perform image processing. In the former method, since the steel plate near the gas wiping is in a mirror surface state, diffuse reflection hardly occurs and the sensitivity deteriorates,
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. Also, in order to detect the shape with high accuracy, it is necessary to increase the distance from the steel plate to the irradiation laser beam, but there are many devices around the gas wiping device,
It cannot be physically installed.

On the other hand, Japanese Patent Publication No.
As disclosed in Japanese Patent Laid-Open No. 60554, there is a method of measuring the tension distribution of a steel sheet by applying an electromagnetic force from the outside of the steel sheet to detect the shape of the steel sheet. It is impossible to detect the shape of the steel sheet at the position, and at this point in time, a highly accurate shape detector cannot be expected. Furthermore, in the control method of correcting the shape while judging the shape of the steel sheet, it takes a considerable time to finally flatten the steel sheet, which is a serious problem in terms of product quality. Further, the method of presetting the position of the sink roll or the support roll based on the experience of the operator causes a large hit and miss, and it is not always possible to expect highly accurate flattening of the steel plate shape. Further, in presetting the position of the sink roll or the support roll by the process computer, 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 all patterns.

In order to correct the shape, there is a method of moving the sink roll or the support roll in the plating bath. However, in the arrangement of the single support roll using only the lower support roll, the thick steel plate When straightening the shape by simply moving the sink roll, it cannot be straightened unless the sink roll is moved considerably.
Since the moving amount of the sink roll is limited due to the equipment structure,
Occasionally, the shape of a thick steel plate cannot be corrected. For this reason, if the support roll is also 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, so that it is installed on the bath. Other equipment such as the existing wiping nozzle must be moved, which complicates the work. Furthermore, if an asymmetrical shape occurs in the steel plate,
In the operation of one lower support roll, it is difficult to straighten the shape.

[0007]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art and enables the upper and lower support rolls to fix the shape of thick steel plate, correct asymmetric shape, and fix the vertical pass line of the steel plate. Using two relations, steel plate size / width, upper / lower support roll inter-mesh, and relational expression of steel plate warp amount which is a function of sink roll movement, steel plate size, upper / lower support roll The amount of movement of the sink roll that makes the steel plate shape flat easily is calculated only from the intermesh, and based on the amount of movement obtained, presetting is performed using the sink roll advancing / retreating device to determine the flatness of the steel plate. The purpose is to control with high precision.

[0008]

That is, the gist of the present invention is that the lower support roll is on the outer side and the upper support roll is on the inner side of the strip in the hot dip bath which rises around a sink roll installed in the hot dip bath. In the hot dip galvanizing method, the following (4)
From the relational expression in which the warp amount of the steel plate is represented by the linear relation of the sink roll movement amount as in the formula (5), the steel plate size,
Substituting the intermesh between the upper and lower support rolls, determining the coefficient of each term of the linear equation, calculating the amount of movement of the sink roll that makes the steel plate shape flat by equation (6), and moving It is a shape control method for a traveling plated steel sheet in which a sink roll is driven back and forth based on the amount and preset.

When a ≦ 1.6 ΔC = α (a, W, IM) S _shift + β (a, W, IM) = (α ₁ a + α ₂ a ² + α ₃ a ² W + α ₄ aIM + α ₅ a ² IM + Α ₆ a ² WIM + α ₇ aIM ² + α ₈ a ² IM ² ) S _shift + (β ₁ + β ₂ a + β ₃ a ² + β ₄ a ² W + β ₅ aIM + β ₆ a ² WIM + β ₇ aIM ² ) ……………… (4) In the case of 1.6 <a ≦ 3.2 ΔC = α (a, W, IM) S _shift + β (a, W, IM) = (α ₁ aW + α ₂ a ² W + α ₃ aWIM + α ₄ a ² WIM + α ₅ a ² WIM ² ) S _shift + (β ₁ + β ₂ aW + β ₃ a ² W + β ₄ aWIM + β ₅ a ² WIM + β ₆ aWIM ² ) (5) However, ΔC: Steel plate warp amount (mm) S _Shift: sink roll movement amount (mm) IM: intermeshing between the upper-lower support roll (mm) a: plate thickness (mm) W: Width _{(mm) α 1, α 2} , α 3, α 4, α 5, α 6, α 7, α 8 and _{β 1, β 2, β 3} , β 4, β 5, β 6, β 7: steel different constants S _Shift = the material of the - {β (a, W, IM) / α (a, W, IM)} ......... (6)

FIG. 1 shows an embodiment of the shape control device of the present invention. Reference numeral 1 denotes a steel strip, which runs through a corrosion-resistant plated metal such as zinc or lead-tin. That is, the steel sheet strip 1 is plated around the sink roll 2 in the hot dip bath, and is raised while the shape is corrected by the lower support roll 3 on the outer side of the strip and the upper support roll 4 on the inner side thereof, and the gas wiping nozzle 5 and Is raised after controlling a predetermined coating weight with an electromagnetic wiping nozzle installed as necessary. 6 is a shape control arithmetic device.
Here, the calculation is performed in the following procedure. From the steel plate size of the running steel plate, a ≦ 1.6, 1.6 <a ≦ 3.
The relational expression of 2 corresponds to the case.

When a ≦ 1.6 ΔC = α (a, W, IM) S _shift + β (a, W, IM) = (α ₁ a + α ₂ a ² + α ₃ a ² W + α ₄ aIM + α ₅ a ² IM + Α ₆ a ² WIM + α ₇ aIM ² + α ₈ a ² IM ² ) S _shift + (β ₁ + β ₂ a + β ₃ a ² + β ₄ a ² W + β ₅ aIM + β ₆ a ² WIM + β ₇ aIM ² ) ……………… (7) In the case of 1.6 <a ≦ 3.2 ΔC = α (a, W, IM) S _shift + β (a, W, IM) = (α ₁ aW + α ₂ a ² W + α ₃ aWIM + α ₄ a ² WIM + α ₅ a ² WIM ² ) S _shift + (β ₁ + β ₂ aW + β ₃ a ² W + β ₄ aWIM + β ₅ a ² WIM + β ₆ aWIM ² ) (8) However, ΔC: Steel plate warp amount (mm) S _Shift: sink roll movement amount (mm) IM: intermeshing between the upper-lower support roll (mm) a: plate thickness (mm) W: Width _{(mm) α 1, α 2} , α 3, α 4, α 5, α 6, α 7, α 8 and _{β 1, β 2, β 3} , β 4, β 5, β 6, β 7: steel Constant that varies depending on the material of

After dividing into cases, the plate thickness / width and the inter-mesh between upper and lower support rolls are substituted into the relational expression, and the respective coefficients are determined in the relational expression. Using the determined coefficient, the sink roll movement amount for flattening the steel plate shape from the following equation, that is, S for ΔC = 0
Determine the _shift . S _shift =-{β (a, W, IM) / α (a, W, IM)} (9) In the relational expression, the intermesh between the upper and lower support rolls means the lower part in FIG. The distance between the outside of the support roll (position a) and the outside of the upper support roll (position b), that is, IM.

Reference numeral 7 denotes an advancing / retreating drive device for the sink roll 2, which operates the sink roll 2 so that the amount of movement of the sink roll 2 calculated by the shape control computing device 6 is reached. As described above, the plate thickness and the plate width are substituted into the relational expression of the plate warp amount classified according to the plate thickness and the sink roll 2 movement amount, and S _shift that _ΔC = 0 is calculated, and obtained from this. Based on the amount of movement thus obtained, it is possible to perform presetting using the advancing / retreating drive device of the sink roll 2 and control the flatness of the steel sheet with high accuracy. Further, when an error occurs in the preset, the warp amount is calculated from the steel plate shape, and feedback control of the movement amount of the sink roll 2 is performed so that the warp amount becomes 0, thereby controlling the flatness of the steel plate with higher accuracy. It becomes possible to do.

[0014]

[Example] In a hot-dip galvanized steel sheet having a plate thickness of 0.8 mm and a plate width of 1850 mm, the plate thickness is 0.8 mm when the rolls are arranged such that the intermesh between the upper and lower support rolls is 4 mm. (5) is used. Further, in the hot-dip galvanized steel sheet, the respective coefficients of the equation (5) are α ₁ = −0.111 and α ₂ = 0.038.
7, α ₃ = 0.000028, α ₄ = −0.0027,
α ₅ = 0.0078, α ₆ = 0.0000027, α _{7
= 0.000502, α 8 = -0.00072,} β 1 =
−1.451, β ₂ = 3.72, β ₃ = −0.815,
β ₄ = 0.0054, β ₅ = −0.42, β ₆ = −0.
000032, β ₇ = 0.0422, substituting a = 0.8 and W = 1850 in the equation (5), the steel plate warp amount is 0.
When a _shift amount of the sync roll is calculated, that is, S _shift such that _ΔC = 0, the _shift amount of the sync roll is 9.4 mm, and the forward / backward drive device of the sync roll is calculated based on the obtained shift amount. As a result of performing presetting using, the shape of the steel plate is as shown in FIG. 3, and the shape of the steel plate can be controlled. Note that the conventional method of manually presetting the position of the sink roll based on the previously operated data results in an asymmetrical shape, and the warp amount of the steel sheet (difference between the maximum value and the minimum value of the steel sheet) is only about 2 to 3 mm. Whereas the control was impossible, the warp amount of the steel sheet can be controlled to 1 mm or less by using the method of the present invention.

[0015]

As described above, according to the method of the present invention, the shape of the hot-dip plated steel sheet, that is, the flatness can be controlled with high accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a shape control device.

FIG. 2 is an explanatory diagram of an intermesh between upper and lower support rolls.

FIG. 3 shows a warp amount of a steel plate shape after presetting a moving amount of a sink roll of a hot-dip galvanized steel plate having a plate thickness of 0.85 mm and a plate width of 1850 mm.

[Explanation of reference symbols] 1 steel strip 2 sink roll 3 lower support roll 4 upper support roll 5 wiping nozzle 6 shape control arithmetic unit 7 sink roll forward / backward drive unit

Claims (1)

[Claims] 1. A hot-dip plating method in which a lower support roll is arranged outside a strip in a hot-dip bath rising up around a sink roll installed in the hot-dip galvanizing bath, and an upper support roll is arranged inside the strip. For steel sheets, from the relational expressions such as the following equations (1) and (2), in which the warp amount of the steel sheet is expressed by the linear relation of the sink roll movement, the steel plate size and the intermesh between the upper and lower support rolls are calculated. Substituting it, determining the coefficient of each term of the linear equation, calculating the moving amount of the sink roll that makes the steel plate shape flat by the following formula (3), and driving the sink roll forward and backward based on the moving amount. A method for controlling the shape of a running plated steel sheet, which is characterized by presetting. When a ≦ 1.6 ΔC = α (a, W, IM) S _shift + β (a, W, IM) = (α ₁ a + α ₂ a ² + α ₃ a ² W + α ₄ aIM + α ₅ a ² IM + α ₆ a ² WIM + α ₇ aIM ² + α ₈ a ² IM ² ) S _shift + (β ₁ + β ₂ a + β ₃ a ² + β ₄ a ² W + β ₅ aIM + β ₆ a ² WIM + β ₇ aIM ² ) …………………… ( 1) In the case of 1.6 <a ≦ 3.2 ΔC = α (a, W, IM) S _shift + β (a, W, IM) = (α ₁ aW + α ₂ a ² W + α ₃ aWIM + α ₄ a ² WIM + α ₅ a ² WIM ² ) S _shift + (β ₁ + β ₂ aW + β ₃ a ² W + β ₄ aWIM + β ₅ a ² WIM + β ₆ aWIM ² ) ... (2) However, ΔC: Steel plate warp amount (mm) S _shift : Moving amount of sink roll (mm) IM: Intermesh between upper and lower support rolls (mm) a: Plate thickness (mm) W: Plate width (mm) α ₁ , Α ₂ , α ₃ , α ₄ , α ₅ , α ₆ , α ₇ , α ₈ and β ₁ , β ₂ , β ₃ , β ₄ , β ₅ , β ₆ , β ₇ : constants S that vary depending on the material of the steel sheet S _shift =-{β (a, W, IM) / α (a, W, IM)} ... (3)