JPH06101008A - Shape controlling method of traveling hot dipped steel sheet - Google Patents

Abstract

PURPOSE:To control the flatness of the hot-dipped steel sheet with high precision by setting the rolles based on the movement of a sink roll and a support roll so that the form of the steel sheet may be flat in executing the hot dipping of the steel sheet. CONSTITUTION:After the surface of the steel sheet 1 passing through a hot dipping metallic bath is plated with a molten metal, the steel sheet is elevated in the vertical direction by the sink rall 2, and the adhered amount of the hot-dipping metal is controlled by a gas wiping nozzle 4 while the steel sheet is supporting by the support roll 3. Advancing/retreating driving devices 6, 7 of the sink roll 2 and the support roll 3 are driven with the movement of the respective rolls 2, 3 so as to make the deflection omega zero, the positions of both rolls 2, 3 controlled and the flatness of the hot-dipped steel sheet improved, by substituting the residual moment in the longitudinal and the width directions of the steel to be computed by a form control arithmetic device 5 by using data of the roll diameter, the roll arrangement and the material constants into the formula of the deflection omega of the steel sheet to be obtained by the formula I, based on the tensile property of the hot-dipped steel sheet and the restrictive property of the respective rolls 2, 3.

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 plated 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. Above all, 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 sheets are generally hot-rolled or cold-rolled steel sheets, passed through a preliminary oxidation furnace, then a reduction annealing furnace, and then a cooling furnace, and are passed through the sink roll of the hot-dip galvanizing bath by turning them to support rolls. It is run while being supported, and the plating metal in a molten state adhering to the surface is wiped by a gas wiping nozzle to a predetermined basis weight, and if necessary, further manufactured through an alloying heating furnace.

However, there is a problem in that the basis weight of the plated metal of the manufactured hot dip plated steel sheet varies greatly depending on the change in the shape in the sheet width direction, and the weldability or the adhesion 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 from 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 a shape detector, a method to judge the steel plate shape near the gas wiping nozzle to automatically control the operating end, a method to correct the shape in the steel plate width direction using electromagnetic force, and the previously operated data Based on this, there are a method of manually presetting the position of the sink roll or the support roll, a method of introducing a process computer, and a method of automatically presetting the position of the sink roll or the support roll according to the steel plate size, material, and the like.

However, in such a steel plate shape correction control method, a highly accurate shape detector is required, but since unsolidified molten zinc adheres to the steel plate in the vicinity of the gas wiping nozzle, contact is not made. Laser-type and electromagnetic-type non-contact type shape detectors are used because the type-type shape detector cannot be 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, 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. In addition, in order to detect the shape with high accuracy, it is necessary to increase the distance between the steel plate and the irradiation laser beam, but since many devices are installed around the gas wiping device, it is physically impossible to install it. It is possible.

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 method of controlling the shape correction while judging the shape of the steel sheet, it takes a considerable amount of time to finally flatten the steel sheet, which is a serious problem in terms of product quality. Also,
Based on experience, with respect to those that preset the position of the sink roll or the support roll, there is a large amount of hitting, and it is not possible to always expect highly accurate flattening of the steel plate shape.
Regarding presetting of 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 in order to make presetting possible in all patterns.

[0007]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art and provides a flat steel plate shape based on an equation calculated in consideration of tensile properties and roll restraint properties. The precise amount of movement of the sink roll or support roll is calculated, and based on the amount of movement obtained, presetting is performed using the forward / backward drive device of the sink roll or support roll to control the flatness of the steel plate with high accuracy. The purpose is.

[0008]

[Means for Solving the Problems] That is, the amount of deflection (ω) of the steel sheet obtained by the following equation from the tensile characteristics and the roll restraint characteristics of the plated steel sheet traveling through the sink roll or the support roll in the hot dip bath is A shape control arithmetic unit that calculates the movement amount by changing the wrap amount of the support roll or the support roll so that the steel plate shape that becomes 0 becomes flat, and the sink roll based on the movement amount, or It is a shape control method for running galvanized steel sheet characterized by performing presetting using an advancing / retreating drive device for moving a support roll.

[0009]

[Equation 2]

FIG. 1 shows an embodiment of the shape control device of the present invention. Reference numeral 1 is a steel plate on which a corrosion-resistant metal such as zinc or lead-tin is plated and which runs. The steel sheet 1 is plated by turning around a sink roll 2 in a hot dip bath, rising while being corrected in shape by a support roll 3, and having a predetermined coating weight by a gas wiping nozzle 4 and an electromagnetic wiping nozzle installed as necessary. After controlling to quantity, it rises. 5 is
It is a shape control computing device. Here, the calculation is performed in the following procedure. The wrapping angle of the roll is calculated from the roll diameter, roll arrangement, material constant, and the like by using the equation (5), and the processing curvature is obtained.

[0011]

[Equation 3] Here, p: horizontal distance between roll centers, H: roll lap amount, a: plate thickness

Assuming the strain at the center of the plate thickness, the strain ε _{x in the} longitudinal direction is satisfied by the relational expression such as the equation (6). ε _x = K _z + ε _c ……………………………………………… (6)

From the equation (6), in elastic deformation, Ho
In oke's law, plastic deformation
The stress distribution is calculated assuming that the -Reuss relational expression holds. The tension is obtained from the obtained stress distribution, and the convergence calculation is performed so that the equation (7) is satisfied at the given tension.

[Equation 4]

This is performed for each of the bending process and the bending-back process, and further repeated for the number of rolls. From the stress distribution in the longitudinal direction and the width direction in the bending-back process of the final roll, from the formula (8) to the longitudinal direction, Calculate the residual moment in the width direction.

[0015]

[Equation 5]

Next, the residual moments in the longitudinal and width directions obtained from the equation (8) are substituted into the equation of the amount of deflection obtained from the tensile characteristics and the restraint characteristics of the roll, that is, the equation (9),
Convergence calculation is performed by changing the wrap amount of the sync roll 2 or the support roll 3 until ω (x, y) = 0.
The wrap amount H _sink of the sink roll 2 or the wrap amount H of the support roll 3 such that ω (x, y) = 0.
_support ie to calculate the amount of movement of the sink roll 2 or the support roll 3.

[0017]

[Equation 6]

Reference numeral 6 is a forward / backward drive device for the sink rolls, and 7 is a forward / backward drive device for the support rolls. Operate the roll 3.

As described above, the roll diameter, roll arrangement, and
Substituting the residual moments in the longitudinal and width directions calculated using the material constants, the amount of movement of the sink roll 2 or the support roll 3 such that the amount of deflection becomes 0 is calculated, and the amount of movement obtained from this is calculated. Based on this, presetting can be performed using the forward / backward drive device of the sink roll 2 or the support roll 3, and the flatness of the steel sheet can be controlled with high accuracy. Also, if there is an error in the preset,
By performing feedback control of the movement amount of the sink roll 2 or the support roll 3 so that the flatness of the steel sheet can be controlled with higher accuracy.

[0020]

EXAMPLE A hot-dip galvanized steel sheet having a sheet thickness of 0.8 mm and a sheet width of 1850 mm, roll arrangement on the equipment, roll diameter,
Substituting the material constants into the equation (9) and calculating the moving amount of the sink roll and the support roll such that the bending amount becomes 0, the moving amount of the sink roll is 16 mm, and the moving amount of the support roll is 4 mm. As a result of presetting using the forward / backward drive device for the sink roll and the support roll based on the obtained moving amount, the steel plate shape is as shown in FIG. 2, and the shape control of the steel plate becomes possible. In addition, in the conventional method of presetting the position of the sink roll or the support roll based on the previously operated data,
While the amount of bending, that is, the amount of warpage, of the steel sheet can be controlled only at about 2 to 3 mm, the method of the present invention can control the amount of bending, that is, the amount of warpage to 1 mm or less.

[0021]

As described above, according to the shape control method of the present invention, the amount of movement of the sink roll or the support roll that makes the steel plate flat is obtained, and the rolls are preset based on this amount. With this, it becomes possible to control the flatness of the steel sheet with high accuracy, and the industrial effect thereof is very large.

[Brief description of drawings]

FIG. 1 shows a configuration of a shape control device.

FIG. 2 shows an example of a steel plate shape after presetting the moving amount of a sink roll and a support 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 symbols]

 DESCRIPTION OF SYMBOLS 1 Steel plate 2 Sync roll 3 Support roll 4 Wiping nozzle 5 Shape control calculation device 6 Sync roll forward / backward drive device 7 Support roll forward / backward drive device

Claims (1)

[Claims] 1. A deflection amount (ω) of a steel sheet obtained by the following equation (1) from the tensile characteristics and roll restraint characteristics of a plated steel sheet running through a sink roll or a support roll in a hot dip bath is 0. A run characterized by changing the wrap amount of the sink roll or the support roll and calculating the movement amount by performing convergence calculation, and driving the sink roll or the support roll forward and backward based on the movement amount to perform presetting. Shape control method for plated steel sheet. [Equation 1]