A method for eliminating edge waves of hot-rolled free-rolled strip

Abstract

The present application relates to a kind of methods for eliminating hot rolling free rolling strip edge wave, adopt "narrow-wide-narrow-wide-narrow-wide" "bamboo joint shape" rolling mode, specifically includes:1) the product in the temperature range of 1210~1240 ℃ is carried out free rolling;2) when the length of rolling strip reaches 40~45 kilometers, start to carry out reverse wide free rolling, the longest rolling cycle of whole finishing work roll is 110 kilometers;3) the maximum width of reverse wide transition material is less than 300mm with the width difference of product before rolling;4) the hot rolling strip with thickness of 1.2~25.4mm is divided into more than 5 thickness levels, and the thickness of the first block of transition material is not less than two thickness levels of main rolling material.In solving the problem of rolling shape of reverse wide product, the advantage of changing strip crown of rolling mill is fully utilized to control hot rolling shape by crown, solve the problem of shape, realize wide material and narrow material alternate rolling in cycle, and improve production capacity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of hot rolling, and particularly relates to a method for eliminating edge wave of hot-rolled free-rolling strip steel. BACKGROUND

[0002] Strip shape is an important quality index of hot-rolled strip steel, and hot-rolled free rolling is a necessary way to realize flexible production organization and improve production efficiency of a hot rolling mill train and break through the bottleneck of production capacity of the hot rolling mill train. The traditional rolling mode of hot rolling is limited by the shape distortion of a bearing roll gap caused by serious non-uniform wear of a hot rolling work roll surface and out-of-control strip shape in the case of "batch same width rolling" or "large reverse width rolling", and the strip steel edge wave defect is easily generated, and the rolling mill changes the roll frequently, which seriously affects the release of the rolling line capacity. The hot-rolled free rolling is essentially a strip shape control problem, and in order to realize the hot-rolled free rolling and improve the production capacity of the hot rolling mill train, the roll wear amount needs to be reduced, the roll wear needs to be uniform, and the strip steel edge wave in the free rolling needs to be controlled. After studying the rolling process, roll wear and rolling stability data, the previous "coffin shape" rolling method of "narrow-wide-narrow" according to the width is changed to solve the strip steel edge wave defect problem. SUMMARY

[0003] The purpose of the present application is to provide a method for eliminating the edge wave of hot-rolled free-rolling strip steel, and a "bamboo joint shape" rolling method of "narrow-wide-narrow-wide-narrow-wide" is adopted to perform reverse width rolling of thick gauge products, solve the rolling strip shape problem of reverse width products, and improve the hot rolling capacity.

[0004] In order to achieve the above purpose, the present application realizes the following technical scheme:

[0005] A method for eliminating the edge wave of hot-rolled free-rolling strip steel adopts a "bamboo joint shape" rolling mode of "narrow-wide-narrow-wide-narrow-wide", and specifically includes the following steps:

[0006] 1) Free rolling is performed on products with an out-of-furnace temperature in the range of 1210-1240℃;

[0007] 2) When the length of the rolled strip steel reaches 40-45 kilometers, reverse width free rolling is started, and the longest rolling cycle of the entire finishing work roll is 110 kilometers;

[0008] 3) The maximum width difference of the reverse width transition material and the width of the previous product is less than 300mm;

[0009] 4) The hot-rolled strip steel with a thickness of 1.2-25.4mm is divided into more than 5 thickness levels, and the thickness of the first block of transition material is not less than two thickness levels of the main rolled material;

[0010] 5) When the length of the rolled strip steel is greater than 40 kilometers, high-level surface quality products are not rolled;

[0011] 6) Hot rolling free rolling, negative CVC roll shifting amount of 80-100mm at the work roll of the upstream stands of the finishing mill; and simultaneously, positive CVC roll shifting amount of 80-100mm at the downstream stands of the finishing mill;

[0012] 7) During the free rolling process, the flatness of the strip steel is controlled between -100iu and +50iu;

[0013] 8) When rolling low-carbon and ultra-low-carbon series hot-rolled raw materials, the target crown control amount of the strip steel is 70-80μm;

[0014] 9) During the free rolling process, when rolling wide and thick plates with a rolling thickness greater than 10mm and a width greater than 1500mm in reverse wide rolling, the roll shape is reshaped to make the edge wear of the roll uniform.

[0015] The high-grade surface quality product is one of pickled automobile sheet, O5-grade cold-rolled raw material and automobile surface plate.

[0016] The upstream stands of the finishing mill are F1-F4 stands, and the downstream stands of the finishing mill are F5-F7 stands.

[0017] Compared with the prior art, the method has the following beneficial effects:

[0018] The method adopts a "bamboo joint" rolling method of "narrow-wide-narrow-wide-narrow-wide", breaks the traditional thinking concept, and continues to produce by rolling thick specifications in reverse wide rolling when "narrow-wide" is changed. The rolling distance of the finishing mill in the hot rolling rolling cycle reaches more than 70km, and the longest cycle is 110km. The production time is greatly increased, the yield is increased, the roll changing time is reduced, the roll consumption is greatly reduced, and the loss of the heating furnace and the rolling mill is relatively reduced. When solving the problem of the rolling shape of the reverse wide product, the advantage of changing the crown of the strip steel is fully utilized to control the hot rolling shape by the crown, solve the problem of the shape, realize the alternate rolling of the wide material and the narrow material in the cycle, improve the production capacity, reduce the daily roll changing frequency, improve the rolling mill operation rate, and realize the full release of the production capacity of the hot rolling rolling line. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a schematic diagram of the target width change of the finished strip steel.

[0020] In the figure: 1-reverse wide free rolling. DETAILED DESCRIPTION

[0021] The application will be described in detail below with reference to the accompanying drawings of the specification, but it should be pointed out that the implementation of the application is not limited to the following embodiments.

[0022] A method for eliminating the edge wave of the hot rolling free rolling strip steel, comprising:

[0023] 1) seeFigure 1 According to the hot-rolled product steelmaking requirements, the target tapping temperature is set to meet the product within the range of 1210-1240°C based on the tapping temperature and surface quality grade. The surface quality is guaranteed, and the "bamboo joint" rolling mode is adopted to gradually promote the cross-rolling of cold-rolled low-carbon, ultra-low-carbon steel and cold-rolled high-strength steel with a yield strength difference of more than 100 MPa.

[0024] Table 1 Production method for eliminating edge waves of hot-rolled free-rolled strip steel of the embodiment

[0025]

[0026]

[0027] 2) After the length of the rolled strip steel reaches 40-45 kilometers, reverse wide free rolling is started, and the longest rolling cycle of the entire finishing work roll can reach 110 kilometers.

[0028] 3) The maximum width difference of the transition material and the width of the previous product before rolling should be less than 300 mm. For example, if the width of the previous product is 1200 mm, the width of the first block of the transition material should be less than 1500 mm.

[0029] 4) The hot-rolled strip steel with a thickness of 1.2-25.4 mm is divided into 8 thickness levels, as shown in Table 2, and the thickness of the first block of the free-rolled transition material should not be less than two thickness levels of the main rolled material. For example, when the main rolled material is in the thickness level of 1.2-2 mm, the thickness of the first block of the free-rolled transition material should be in the level of 3.0-4.0 mm, and the subsequent rolling is for products with a thickness of 5.0 mm or more.

[0030] Table 2 Thickness level table of hot-rolled strip steel / mm

[0031]

[0032] 5) When the total length of the rolled strip steel is greater than 40 kilometers, no high-grade surface quality products such as pickling plate, automobile surface plate, O5 automobile plate, pipeline steel, thin specification, wide plate limit, pattern plate, and export products are rolled.

[0033] 6) During the hot-rolled free rolling, the negative CVC roll shift amount of the upstream stands of the finishing mill is increased by 80-100 mm, and the strip steel crown is increased by 10 μm. At the same time, the positive CVC shift amount of the downstream stands of the finishing mill is increased by 80-100 mm, and the flatness priority principle is adopted to solve the edge wave of the reverse wide strip steel product.

[0034] 7) During the free rolling process, the flatness of the strip steel is controlled between -100iu and +50iu.

[0035] 8) When rolling the low-carbon and ultra-low-carbon series of hot-rolled raw materials, the target crown control amount is changed, and the target crown of the strip steel is adjusted from 50 μm to 70-80 μm, reducing the occurrence of the crown of the cold-rolled system product.

[0036] 9) In the free rolling process, the rolling thick specification wide plate is reshaped when rolling in reverse, so that the edge wear of the roller is uniform, and the shape distortion of the roll gap caused by reverse rolling is reduced.

Claims

1. A method for eliminating edge waviness in hot-rolled free-rolled strip steel, characterized in that, The rolling process employs a "narrow-wide-narrow-wide-narrow-wide" "bamboo-joint" pattern, specifically including: 1) Products with a furnace exit temperature range of 1210~1240℃ are subjected to free rolling; 2) When the length of the rolled strip reaches 40-45 kilometers, reverse width free rolling begins, and the longest rolling cycle of the entire finishing work roll is 110 kilometers. 3) The maximum width difference between the reverse width transition material and the width of the previous product before rolling is less than 300mm; 4) Divide hot-rolled strip steel with a thickness of 1.2 to 25.4 mm into more than 5 thickness grades, and the thickness of the first transition material to be freely rolled shall not be less than two thickness grades of the main rolled material; 5) When the length of the strip rolled by the rolls is greater than 40 kilometers, high-grade surface quality products shall not be rolled. 6) During hot rolling free rolling, the work rolls of the upstream stand of the finishing mill are negatively skewed, with a CVC skew amount of 80-100mm; at the same time, the CVC skew amount of 80-100mm is increased in the downstream stand of the finishing mill. 7) During the free rolling process, the flatness of the strip is controlled between -100iu and +50iu; 8) When cold rolling low-carbon and ultra-low-carbon series hot-rolled raw materials, the target crown of the strip should be controlled at 70-80 μm; 9) During free rolling, when rolling thick plates with a thickness greater than 10mm and a width greater than 1500mm in reverse width rolling, the roll shape is reshaped to make the edge of the roll wear uniform.

2. The method for eliminating edge waviness in hot-rolled free-rolled strip steel according to claim 1, characterized in that, The high-grade surface quality product is one of the following: pickled automotive sheet, O5 grade cold-rolled raw material, and automotive surface sheet.

3. The method for eliminating edge waviness in hot-rolled free-rolled strip steel according to claim 1, characterized in that, The upstream stand of the finishing mill is the finishing mill F1 to F4 stand, and the downstream stand of the finishing mill is the finishing mill F5 to F7 stand.

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