A method for producing an extreme wide and medium thick plate

Abstract

The application relates to a production method of an extreme-width medium plate, which realizes the successful rolling of the medium plate with the extreme width of greater than or equal to 4880 mm and the thickness of 40-60 mm on a 5000 mm wide plate rolling mill through the control of the blank shape design, blank heating and rolling process and the like, and a higher rolling hit rate is achieved, and the stable and batch production can be realized. The application does not need any additional investment or technical transformation, widens the width range of the existing steel plate production, and can meet the demand of various industries such as shipbuilding and container steel plate for the extreme-width steel plate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of medium-thick steel plate production, and relates to a production method of limit-width medium-thick plate. BACKGROUND

[0002] According to the traditional rolling theory, the maximum width of the finished product that can be produced by the rolling mill is the length size of the working roll body minus a certain size, for example, for a 5000mm rolling mill, the design limit rolling width specification is 4800mm. The limit width mainly depends on the rolling state of the roughing and finishing rolling mill groups and the rolling mill capacity of the finishing rolling mill group, that is, to ensure that the rolled piece does not deviate from the working roll body during rolling, and to prevent the rolled piece from running out of the roll and causing scrap, winding of the roll, and even accidents such as broken roll and broken shaft. The thickness specification mainly depends on the equipment capacity of the finishing rolling mill group, that is, the rolling mill load should not exceed the allowable capacity range of the finishing rolling mill group. The limit width specification is prone to many problems such as tilting, steel jamming, frame scraping, and rolling scrap during rolling, which becomes a key factor restricting the product expansion of the rolling mill. Therefore, the development of limit-width medium-thick plate is not only an urgent need of steel enterprises, but also a deepening understanding of the rolling process and an in-depth exploration of the limit capacity of the equipment, which has important engineering application value. SUMMARY

[0003] The present application aims to provide a production method of limit-width medium-thick plate, which widens the width range of the existing steel plate, solves the problem of low rolling hit rate that easily occurs in the production process of limit-width medium-thick plate, and realizes the ability to batch and stably roll out limit-width steel plate.

[0004] The technical scheme of the present application is as follows:

[0005] A production method of limit-width medium-thick plate, the thickness of the produced steel plate is 40-60mm, and the limit width is ≥4880mm, which comprises the following process steps:

[0006] (a) controlling the length of the billet to be between 4880-4890mm, and controlling the length of the steel plate to be ≤18m;

[0007] (b) using a walking beam type heating furnace, and controlling the billet delivery temperature to be 1200-1230℃;

[0008] (c) using single-stand rolling, and setting the maximum rolling force to be 88MN and the maximum torque to be 4000kN·m;

[0009] (d) sending the billet from the heating furnace to the front conveying roller of the rolling mill, so that the length direction of the billet is consistent with the feeding direction of the front conveying roller of the rolling mill; after the billet is descaled, it is directly sent to the front of the finishing rolling mill by the front conveying roller of the rolling mill;

[0010] (e) rotating the blank by 90°, transversely rolling in the finishing rolling mill set, controlling the rolling ≤19 passes; the throw-off distance is controlled at 3.2-3.5 m; the working position of the roller is controlled at 20-25 mm;

[0011] (f) after rolling, without opening water, sending to the hot straightening machine for straightening 1-3 passes.

[0012] Preferably, in step (a), the diagonal length deviation of the blank is controlled within 10 mm.

[0013] Preferably, in step (e), the biting speed is 1.2-1.5 m / s, and the rolling speed is 2-4 m / s.

[0014] In order to reduce the temperature drop of the rolled piece during rolling and reduce the rolling mill load, preferably, in step (e), the descaling ≤5 passes is controlled in the first 9 passes before rolling.

[0015] Preferably, in step (f), one group of head and tail side medium pressure water in the Mulpic device is opened for blowing to remove the surface re-oxidized scale.

[0016] Invention principle: The difficulty in developing the limit wide gauge medium plate lies in how to ensure that the rolled piece does not deviate from the working roller body during rolling and the rolling mill load does not exceed the allowable capacity range of the finishing rolling mill set. The technical principle involved in the method of the present invention includes:

[0017] Blank shape design: If the blank length is short, the blank needs to be rolled to the raw edge width, it is difficult to obtain accurate plate width, and it is easy to appear rolling wide or narrow, and it is difficult to turn the steel. The present invention adopts long blank shape design, the blank length is 4880-4890 mm, and the length is rolled when the width is ensured that the width of the rolled piece does not exceed the working roller body.

[0018] Blank heating: step beam heating furnace is adopted; the length of the blank has reached the design upper limit requirement of the step beam heating furnace, the present invention adopts single-row blank loading, the width direction of the blank is consistent with the step beam feeding direction, which can effectively avoid the blank from scratching the frame on the conveying roller.

[0019] Rolling process: transversely rolling in the finishing rolling mill set; increasing the heating temperature and controlling the rolling passes can reduce the temperature drop of the rolled piece during rolling, thereby effectively reducing the rolling mill load; controlling the biting speed, rolling speed and rolling force, etc. can ensure the stability during rolling. The present invention adopts full hot rolling process, the final rolling temperature is high, the rolled piece surface is easy to generate scale after rolling, the Mulpic device is opened to spray the side medium pressure water, which can effectively remove the surface re-oxidized scale and prevent the scale from being pressed in during the hot straightening process.

[0020] The present application has the following advantages: the present application realizes successfully rolling the medium plate with limit width ≥ 4880mm and thickness of 40-60mm on the 5000mm wide plate mill by controlling the blank shape design, blank heating and rolling process, etc. The present application method obtains higher rolling hit rate and can stably and batch produce. The present application does not need any additional investment or technical transformation, breaks through the limit width of equipment design, widens the width range of the existing production steel plate and can meet the demand of limit width medium plate in various industries such as shipbuilding and container steel plate. DETAILED DESCRIPTION

[0021] The present application will be further illustrated by the following examples.

[0022] The example is carried out in the 5000mm wide plate mill, four-roll reversible wide plate mill is adopted, and the maximum rolling force is 100MN. Example 1

[0023] The production method of limit width medium plate, the steel grade is Q345R, and the thickness is 46mm. The key process steps are:

[0024] (a) the blank length is controlled to be 4880mm, the diagonal length deviation is ≤10mm, and the steel plate length is about 15.2m.

[0025] (b) the step beam type heating furnace is adopted, the blanks are loaded in single row, the blank width direction is consistent with the step beam feeding direction, and the blank delivery temperature is 1205℃.

[0026] (c) single stand rolling is adopted, the maximum rolling force is set to be 88MN, and the maximum torque is 4000KN·m.

[0027] (d) the blank is sent from the heating furnace to the conveying roller before the rolling mill, so that the blank length direction is consistent with the conveying roller feeding direction before the rolling mill; after the blank is descaled, it is directly sent to the front of the finishing mill.

[0028] (e) the blank is rotated by 90°, the transverse rolling is carried out in the whole process of the finishing mill group, 19 passes are rolled, the last pass is empty, and the 1st, 3rd, 5th and 7th passes are descaled. The biting speed is 1.2m / s, the rolling speed is 2-4m / s, the throwing distance is 3.2m, and the roller working position is controlled to be 20-25mm.

[0029] (f) after rolling, water is not opened, only one group of middle pressure water in the Mulpic device in the head and tail side surface is opened for blowing, the surface reoxidized scale is removed, and then the hot straightening machine is used for straightening 3 times.

[0030] The rolling process parameters of example 1 are shown in table 1. The width of the produced steel plate is 4889.1mm, and the thickness is 46.2mm.

[0031] Table 1 Rolling process parameters of Example 1

[0032] . Example 2

[0033] Production method of limit wide medium plate, steel grade Q345R, thickness 52 mm, key process steps:

[0034] (a) The length of the blank is 4884 mm, the diagonal length deviation is less than or equal to 10 mm, and the length of the steel plate is about 13.6 m.

[0035] (b) A walking beam heating furnace is used, and the blank is loaded in a single row. The width direction of the blank is consistent with the feeding direction of the walking beam. The blank temperature is 1220℃.

[0036] (c) Single stand rolling is used, and the maximum rolling force is set to 88 MN, and the maximum torque is 4000 KN·m.

[0037] (d) The blank is sent from the heating furnace to the roller bed in front of the rolling mill, so that the length direction of the blank is consistent with the feeding direction of the roller bed in front of the rolling mill. After the blank is descaled, it is directly sent to the front of the finishing mill.

[0038] (e) The blank is rotated by 90°, and transverse rolling is performed throughout the finishing mill group. The rolling is performed in 15 passes, and the last pass is empty. Passes 1, 2, 4 and 6 are descaled. The biting speed is 1.5 m / s, the rolling speed is 2-4 m / s, the throwing distance is 3.5 m, and the working position of the roller is controlled at 20-25 mm.

[0039] (f) After rolling, no water is opened, only one group of medium pressure water on the head and tail side of the Mulpic device is opened for spraying, to remove the surface reoxidized scale, and then sent to the hot straightening machine for straightening in 3 passes.

[0040] The rolling process parameters of Example 2 are shown in Table 2. The width of the produced steel plate is 4891.4 mm, and the thickness is 52.5 mm.

[0041] Table 2 Rolling process parameters of Example 2

[0042] .

Claims

1. A method for producing an extreme wide and medium thick plate, the thickness of the steel plate being 40 to 60 mm, the extreme width being ≥ 4880 mm, characterized in that The process comprises the following steps: (a) controlling the length of the blank to be between 4880 and 4890 mm and the length of the steel plate to be ≤18 m; (b) using a walking beam heating furnace, loading the blank in a single row so that the width direction of the blank is consistent with the feeding direction of the walking beam, and the blank temperature after tapping is 1200-1230 °C; (c) using single-stand rolling, setting the maximum rolling force to be 88 MN and the maximum torque to be 4000 kN·m; (d) feeding the blank from the heating furnace to the roller bed in front of the rolling mill so that the length direction of the blank is consistent with the feeding direction of the roller bed in front of the rolling mill; after descaling, the blank is directly fed to the front of the finishing mill from the roller bed in front of the rolling mill; (e) rotating the blank by 90°, performing transverse rolling in the finishing mill group throughout, controlling the rolling to be ≤19 passes; the throw distance is controlled to be 3.2-3.5 m; and the working position of the roller is controlled to be 20-25 mm; (f) after rolling, without opening the water, the steel plate is fed to the hot straightening machine for straightening 1-3 passes.

2. A method of producing an ultra-wide heavy plate according to claim 1, characterized in that: In step (a), the diagonal length deviation of the blank is controlled to be within 10 mm.

3. A method of producing an ultra-wide heavy plate according to claim 1, characterized in that: In step (e), the biting speed is 1.2-1.5 m / s, and the rolling speed is 2-4 m / s.

4. The method of producing an ultra-wide heavy plate according to claim 1, characterized by: In step (e), the descaling is ≤5 passes in the first 9 passes before rolling.

5. A method of producing an ultra-wide heavy plate according to claim 1, characterized in that: In step (e), 1 group of medium-pressure water on the head and tail sides in the Mulpic device is opened for blowing to remove the surface regenerative oxide scale.