JPH06210334A - Strip crown and strip shape control method in strip rolling - Google Patents

Abstract

(57) [Summary] [Purpose] Larger build-up between the front stands with thicker plate thickness so that the plate crown and plate shape are the final finished shape, and there is no change in shape between the rear stand with thin plate thickness. The purpose of this is to reduce the size of the strip to prevent the shape of the strip from being disturbed and to reduce operational troubles due to automatic control of rolling. [Structure] A shape change coefficient ξ that sets an allowable range of a rolling shape of a stand 6 that controls a work roll 2 is calculated based on rolling conditions such as a sheet width, a sheet thickness, a roll diameter, and the shape change coefficient ξ is set. The allowable range of the rolling shape is widened so that the front-stage stands that do not exceed the specified index value can be formed into a substantially finished shape, and the allowable range of the rolling shape is narrowed so that the passing plate shape is not disturbed between the latter-stage stands that exceed the index value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate crown in plate rolling during hot rolling, and a plate shape control method for plate rolling in plate rolling.

[0002]

2. Description of the Related Art Conventionally, a strip crown and strip shape control method in hot strip rolling calculates the elastic deformation amount of a roll on the basis of a predicted load, a pass schedule, etc. to perform thermal expansion, thermal contraction,
In addition to predicting the roll profile due to wear, the ability to build the plate crown of a single stand was sought by the control end capacity of each stand. Then, within the allowable range of the rolling shape of each stand, determine the build schedule of the plate crown that can achieve the final finishing target value while checking whether it is within the allowable range of the rolling shape of the single stand, and determine the control end of each stand. The output was decided. However, in order to equalize the build-up capacity of the plate crown between the stands, the latter stand having a smaller plate thickness has a greater effect on the plate crown and the plate shape than the former stand having a thick plate thickness. However, the automatic control of the rolling shape reduces the plate thickness, and the plate crown is mainly controlled by the post-stand, which causes a problem that the strip shape in the post-finish stage tends to be disturbed, especially for thin and wide materials. However, there is a problem that the automatic control is difficult and the operator has to monitor the plate crown and the plate shape to control the stand.
As shown in Japanese Patent Publication No. 305, the dynamic control has a margin by calculating and determining a preset value of each stand control amount by a linear programming method so that the total sum of control amounts of each stand as an evaluation function becomes the minimum. Although a method of holding the sheet is also used, there is a problem that the sheet passing shape in the latter stage of finishing is apt to be disturbed similarly to the above, and the operator has to control the stand.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to increase the build-up of pre-stage stands having a large plate thickness such that the plate crown and the plate shape are finally finished, and the post-stand stand having a thin plate thickness. In the meantime, it is to reduce the change in shape to prevent the shape of the strip from being disturbed, and to reduce operational troubles due to automatic control of rolling.

[0004]

According to the present invention, a shape change coefficient ξ for setting an allowable range of a rolling shape of a stand for controlling a work roll is calculated on the basis of rolling conditions such as strip width, strip thickness and roll diameter. , The shape change coefficient ξ does not exceed the set index value.The allowable range of the rolled shape is expanded so that it can be built into a substantially finished shape between the former stands, and the strip shape is not disturbed between the latter stands exceeding the index value. The feature is that the allowable range of the rolled shape is narrowed.

[0005]

[Operation] The shape change coefficient of each stand calculated by calculating the shape change coefficient for each stand based on rolling conditions such as plate width, plate thickness, roll diameter, etc. and the index value of the shape change coefficient are compared. Set the allowable range of the rolling shape of each stand, expand the allowable range of the rolling shape of the front stand to be built into the final finish shape, and narrow the allowable range of the rolling shape of the latter stand to change the shape. Is made smaller and the plate material sent between the work rolls is built by the front stand so as to have a nearly final finish shape, and in the latter stand, the plate is passed so as to maintain a substantially constant shape so that the plate shape is not disturbed. To

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments. Reference numeral 1 denotes a rolling mill. The rolling mill 1 is composed of a work roll 2 for rolling a plate material and a backup roll 3 in contact with the work roll 2. The work roll 2 is controlled by a controller 4 in the amount of reduction. Reference numeral 5 is a calculation unit of the control device 4, and the calculation unit 5 is input with the limit value of the rolling shape of each stand 6 as an initial setting value, and the rolling condition data such as the plate thickness, plate width and roll diameter of the plate material. From stand 6
The shape change coefficient is calculated and the shape change coefficient is compared with the set index value. This index value is used to evaluate the width expansion amount of the plate material during rolling. The closer the index value is to 0, the larger the width expansion amount of the plate material. That is, it shows that the degree of appearance in the longitudinal shape is small when the plate crown is changed on the stand entrance / exit side. This indicates that the closer the index value is to 0, the larger the rolled shape can be made, and This means that the disturbance is reduced.

The shape change coefficient ξ is calculated by the following equation. ξ = c ₁ ⁻¹ / πtan ⁻¹ (c ₂ l _n (γ)) (1) where c ₁ : constant c ₂ : constant γ in equation (1) is expressed by the following equation (2) ). γ = h ^1.5 D ^0.5 / w ^2.0・ ・ ・ ・ ・ ・ ・ ・ (2) where h: Stand stand-out side plate thickness ( _mm ) w: Stand stand-out side plate width ( _mm ) D: Stand stand-out Side roll diameter ( _mm ) From the equation (1), the shape change coefficient ξ becomes smaller (0
Close to). That is, it becomes smaller on the front stage side of finishing and as the plate thickness target value increases. From the experience of the operation, it is known that the deformation of the sheet passing shape is small until the shape change coefficient ξ is around 0.2 (0.1 to 0.3), and based on this knowledge, for example, ξ> 0. The output of the control end of each stand 6 so as to narrow the allowable range of the rolling shape on the downstream side from the No. 2 stand, that is, on the downstream stand side, and to widen the allowable range of the rolling shape on the upstream side, that is, the preceding stand side where ξ <0.2. Is set.

In the thus constructed device, first, the control device 4 for controlling the amount of reduction of the work roll 2 of each stand 6 is provided.
The limit value of the rolling shape of each stand 6 is initially set in the calculation unit 5 of. The data of the rolling conditions such as the strip width, strip thickness and roll diameter of the strip to be rolled next is calculated by the arithmetic unit 5 of the controller 4.
Then, the shape change coefficient ξ is calculated from the equation (1).

When the shape change coefficient of the stand 6 is calculated by this calculation, the calculated value is compared with the set index value (0.1 to 0.3). Then, if the calculated value does not exceed the index value, the initially set limit value of the rolling shape is maintained. Then, the shape change coefficient of the next stand 6 is calculated based on the same equation (1) as the above, and is compared with the index value, and the calculated value does not exceed the index value. Is corrected as the former stand with the calculated value exceeding the index value as the latter stand, and the allowable range of the rolling shape is narrowed.

Then, the plate crown is built up by the front-stage stands, and the plate is rolled by the rear-stage stands so that the change of the shape is small, and the plate material is reduced by each front-stage stand at the limit value of the allowable range of the rolling shape. Between the work rolls 2 of the above, the almost finished shape is built at once. The plate material that is built up to a nearly final finish shape in the front stand is sent to the work roll 2 of the rear stand,
Since the latter stand has a narrow allowable range of the rolled shape so as to keep the plate material in a substantially constant shape, the plate material built in the former stage is rolled and sent out so that the shape is not disturbed.

[0011]

As is apparent from the above description, the present invention calculates the shape change coefficient of the stand and compares the calculated value with the index value, so that the calculated value that can make the rolled shape largely does not exceed the index value. When the finishing condition is set between the front stands, and the allowable range of the rolling shape is narrowed to reduce the change in the shape of the rear stand whose calculated value exceeds the index value, the rolling conditions become strict. It prevents the disorder of the shape. As a result, it is possible to perform stable striping, reduce the occurrence of defective products and dropped products, and increase the product yield rate.In addition, it is possible to reduce operating troubles when automatic control is applied. It is an extremely large thing to bring to the industry as a plate crown and plate shape control method in plate rolling that solves the above problem.

[Brief description of drawings]

FIG. 1 is a schematic view of a rolling mill showing an embodiment of the present invention.

FIG. 2 is a flowchart showing the control of the embodiment of the present invention.

[Explanation of symbols]

 1 rolling mill 2 work roll 4 control device 5 computing unit 6 stand

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Nagashima, 5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Co., Ltd. Nagoya Steel Works

Claims (1)

[Claims] 1. A stand for controlling a work roll (2)
Calculate the shape change coefficient ξ that sets the allowable range of the rolling shape in (6) based on the rolling conditions such as strip width, strip thickness, and roll diameter,
The allowable range of the rolling shape is expanded so that the shape change coefficient ξ does not exceed the set index value so as to create a substantially finished shape between the former stands, and the rolling shape is not disturbed between the latter stands that exceed the index value. A plate crown and a plate shape control method in plate rolling, characterized by narrowing the allowable range of the shape.