A rolling method for a steel for an ultra-wide saw blade

Abstract

A rolling method of super-wide saw blade steel, relying on the existing equipment of 5000mm wide plate mill, through the control of blank shape design, homogenization high temperature heating and rolling schedule, successfully rolls out the super-wide saw blade steel with the maximum width of 4850mm and the thickness deviation of-0.4~+0.4mm. The method achieves a high rolling hit rate and yield rate, and can stably and batch produce.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of medium plate production, and relates to a rolling method for super-wide saw blade steel. BACKGROUND

[0002] The medium plate rolling mill has a width advantage, but as the length of the work roll body of the rolling mill increases, the plate shape control and adjustment precision of the rolling mill become more and more difficult. In the prior art, the width of greater than or equal to 4800 mm belongs to an ultra-wide limit specification in the medium plate production process, and needs to be rolled by a rolling mill with a roll diameter of greater than or equal to 5000 mm, which has exceeded the rolling mill equipment capacity of most steel enterprises. Even if the equipment capacity of a few steel enterprises can meet the requirement, it has reached the capacity limit of the rolling mill.

[0003] The saw blade steel with a diameter of greater than or equal to 4800 mm has characteristics of high strength and high hardness, and it is extremely difficult to control the plate shape and thickness uniformity in the production process of the super-wide specification plate. Many problems such as tilting, steel jamming, frame scraping and rolling waste easily occur in the rolling process, the rolling hit rate is low, and the normal production process and cost are greatly affected. Therefore, it is an urgent problem to develop a stable rolling process in the development process of the super-wide thin plate. SUMMARY

[0004] The application aims to provide a rolling method for super-wide saw blade steel, solve the problem of low rolling hit rate which easily occurs in the production process of the existing super-wide saw blade steel, and realize the capacity of the medium plate rolling mill to stably roll out super-wide steel plates in batches.

[0005] The technical scheme of the application is as follows:

[0006] A rolling method for super-wide saw blade steel, the production steel plate has a thickness of 10-16 mm and a width of greater than or equal to 4800 mm, and the rolling method comprises the following process steps:

[0007] (a) rolling the continuous casting billet to a thickness of 150-180 mm, and controlling the rolling length of the steel plate to be less than or equal to 20 m;

[0008] (b) using a walking beam type heating furnace, the billet has a temperature of 1250-1280 ℃ when it is discharged, and the temperature difference between the upper surface and the lower surface is controlled to be within ±15 ℃;

[0009] (c) using double-stand rolling, arranging rolling in the early stage of the roll period, and the rolling mileage is less than or equal to 30 kilometers; the cooling water of the rough rolling mill table, the finishing rolling mill table and the intermediate rolling mill table is turned off, the opening amount of the cooling water in the middle part of the work roll body is adjusted to 60%-70%, and the opening amount of the cooling water on both sides is adjusted to 30%-40%;

[0010] (d) using full-heat rolling process, controlling 5-7 passes in rough rolling, and controlling the thickness of the rolled piece to be 65-75 mm after the rough rolling is completed;

[0011] (e) Finish rolling is controlled for 9 to 11 passes, the biting speed is 1.3 to 1.6 m / s, and the rolling speed is 2 to 5 m / s;

[0012] (f) After rolling, hot straightening is performed directly without water cooling, with straightening performed in 1 to 3 passes to obtain steel for ultra-wide saw blades with a maximum width of 4850 mm and a thickness deviation of -0.4 to +0.4 mm.

[0013] Preferably, in step (a), the blank is flame-cut to be square, and the diagonal length deviation is controlled within 15 mm.

[0014] Preferably, in step (d), the rough rolling adopts the "horizontal rolling-longitudinal rolling-horizontal rolling" rolling mode, that is, the descaled billet is first sent directly from the front extension roller of the machine to the front of the four-roll roughing mill, rotated 90°, and the steel is fed horizontally for pre-forming rolling; then the rolled piece is rotated 90°, and the steel is fed longitudinally for widening rolling, and the length of the rolled piece is rolled to the target width; then the rolled piece is rotated 90°, and all the steel is fed horizontally for extension rolling.

[0015] Preferably, in step (e), the finishing mill descales at the entrance only in the first pass.

[0016] The creative principle of the present invention: The present invention ensures the accurate size and shape of the rolled product by limiting the billet material type, rough rolling mode, etc., thereby avoiding problems such as skewing, frame scraping, and thick / thin rolling that are prone to occur during the rolling process. The use of small billet material type design and billet size restrictions provide conditions for obtaining accurate size and shape during the rough rolling process. Rough rolling adopts three-time steel-turning length-to-width rolling, that is, after the first steel-turning, pre-forming (transverse) rolling is carried out to obtain accurate billet thickness and fan-shaped ends before widening (longitudinal) rolling to reduce the barrel shape during longitudinal rolling, laying a good foundation for the hot-rolled plate thickness and plate width accuracy in the further widening rolling stage; the second steel-turning is carried out for widening rolling to the burr width of the finished product, and then turned 90° to enter the extension rolling stage, providing rolled products with uniform size for finishing rolling. The use of uniform high-temperature heating, high-temperature rolling technology and control of descaling passes and methods can not only effectively reduce the rolling force, but also reduce the temperature drop of the rolled piece during the finishing rolling process, thereby ensuring the uniformity of the thickness in the longitudinal direction of the steel plate during rolling.

[0017] The present invention has the following beneficial effects: Through controlling billet profile design, uniform high-temperature heating, and rolling procedures, the present invention successfully rolled saw blade steel with a maximum width of 4850mm and a thickness deviation of -0.4 to +0.4mm on a 5000mm wide and heavy plate mill. This method achieves high rolling accuracy and yield rates, enabling stable, mass production. DETAILED DESCRIPTION

[0018] The present invention is further described below with reference to the embodiments. Example 1

[0019] The key process steps for rolling the 11 mm thick super-wide steel plate are as follows:

[0020] (a) The continuous casting billet is rolled to a thickness of 150 mm, and the billet is cut square with the fire, with the length deviation of the diagonal line controlled within 15 mm; the length of the mother plate is about 15.2 m.

[0021] (b) A walking beam heating furnace is used, with the core of the slab being discharged at a temperature of 1263℃, the upper surface being at a temperature of 1278℃, and the lower surface being at a temperature of 1268℃, with a temperature difference of 10℃.

[0022] (c) A double-stand rolling process is used, with the rolling being arranged in the early stage of the roll period, with the rolling distance being 10.2 km. The cooling water of the roughing and finishing roll ways and the intermediate roll way is turned off; the cooling water in the middle part of the working roll body is adjusted to an open amount of 65%, and the cooling water on both sides is adjusted to an open amount of 32%.

[0023] (d) A full hot rolling process is used, with 5 passes of rough rolling. After the scaling of the billet, the billet is directly sent to the four-roll roughing mill from the pre-rolling table, and is rotated by 90°, and is pre-formed by 1 pass of rolling in the transverse direction; then the rolled piece is rotated by 90°, and is spread by 2 passes of rolling in the longitudinal direction, so that the length of the rolled piece is rolled to the target width; then the rolled piece is rotated by 90°, and is extended by 2 passes of rolling in the transverse direction. After the rough rolling is completed, the thickness of the rolled piece is 65 mm, and the rolled piece is rotated by 90° at the outlet of the rough rolling mill, and is sent to the inlet of the finishing rolling mill along the conveying roll way.

[0024] (e) The finishing rolling is performed by 11 passes, with the last pass being skipped. After the rolled piece is rotated by 90°, the rolled piece is extended by all passes of rolling in the transverse direction.

[0025] In order to reduce the temperature drop during rolling, only the first pass of the finishing rolling mill is scaled at the inlet, and the biting speed and the rolling speed are further controlled. The thickness of the rolled piece, the biting speed and the rolling speed in each pass during rolling are shown in Table 1.

[0026] According to the above technical scheme, the width of the steel plate produced is 4850 mm, and after the head and tail of the rolled piece are removed, the cutting amount is reduced from more than 1000 mm to within 500 mm, and the thickness deviation is within the range of -0.4~+0.4 mm. Example 2

[0027] The key process steps for rolling the 15 mm thick super-wide steel plate are as follows:

[0028] The continuous casting billet is rolled to a thickness of 156 mm, and the billet is cut square with the fire, with the length deviation of the diagonal line controlled within 15 mm; the length of the mother plate is about 15.6 m.

[0029] (b) Adopting a walking beam heating furnace, the slab core tapping temperature is 1255℃, the upper surface temperature is 1267℃, the lower surface temperature is 1258℃, and the temperature difference is 9℃.

[0030] (c) Adopting double stand rolling, arranging rolling in the early stage of the roll period, the rolling mileage is 15.6 kilometers. The rough and finish rolling ways and the intermediate roller way cooling water are closed; the working roller body middle cooling water opening amount is adjusted to 65%, and the two sides cooling water opening amount is adjusted to 32%.

[0031] (d) Adopting full hot rolling process, rough rolling 5 passes. First, the descaled billet is directly sent to the four-roll roughing mill from the front extension roller way, and rotated 90°, and then transversely fed to perform preforming rolling 1 pass; then the rolled piece is rotated 90°, and longitudinally fed to perform spreading rolling 3 passes to roll the length of the rolled piece to the target width; then the rolled piece is rotated 90°, and the remaining 1 pass is fed transversely to perform extension rolling. After rough rolling, the rolled piece thickness is 70mm, and the rolled piece is rotated 90° at the outlet of the rough rolling mill and sent to the entrance of the finish rolling mill along the conveying roller way.

[0032] (e) Finish rolling 9 passes. After rotating the rolled piece by 90°, all are transversely fed to perform extension rolling.

[0033] In order to reduce the temperature drop in the rolling process, only the first pass of the finish rolling mill is descaled at the entrance, and the biting speed and rolling speed are further controlled. The rolled piece thickness, biting speed and rolling speed of each pass in the rolling process are shown in Table 2.

[0034] Table 1 Rolling process parameters of the steel plate of Example 1

[0035] .

[0036] Table 2 Rolling process parameters of the steel plate of Example 2

[0037] .

Claims

1. A method for rolling steel for ultra-wide saw blades, producing steel plates with a thickness of 10 to 16 mm and a width of ≥ 4800 mm, characterized in that The process steps include: (a) Roll the continuous casting slab to a thickness of 150-180 mm, and control the steel plate rolling length to ≤ 20 m; (b) Using a walking beam heating furnace, the billet tapping temperature is 1250-1280°C, and the temperature difference between the upper and lower surfaces is controlled within ±15°C; (c) Use double-stand rolling, arrange rolling in the early stage of the roll rolling period, and the rolling mileage is ≤30 kilometers; turn off the cooling water of the roughing, finishing and intermediate roller tables, adjust the cooling water opening volume of the middle part of the work roll body to 60%-70%, and adjust the cooling water opening volume of the two sides to 30%-40%; (d) Using full hot rolling process, the rough rolling is controlled to 5 to 7 passes, and the thickness of the rolled product is controlled to be 65 to 75 mm after the rough rolling is completed; (e) Finish rolling is controlled for 9 to 11 passes, the biting speed is 1.3 to 1.6 m / s, and the rolling speed is 2 to 5 m / s; (f) After rolling, hot straightening is performed directly without water cooling, with straightening performed in 1 to 3 passes to obtain steel for ultra-wide saw blades with a maximum width of 4850 mm and a thickness deviation of -0.4 to +0.4 mm.

2. The method for rolling steel for ultra-wide saw blades according to claim 1, characterized in that: In step (a), the blank is required to be square when flame-cut, and the diagonal length deviation is controlled within 15 mm.

3. The method for rolling steel for ultra-wide saw blades according to claim 1, characterized in that: In step (d), the rough rolling adopts the "cross rolling-longitudinal rolling-cross rolling" rolling mode, that is, the descaled billet is first directly fed into the four-roll roughing mill from the front extension roller, rotated 90°, and steel is fed horizontally for pre-forming rolling; then the rolled piece is rotated 90°, steel is fed longitudinally for widening rolling, and the length of the rolled piece is rolled to the target width; then the rolled piece is rotated 90°, and all steel is fed horizontally for stretching rolling.

4. The method for rolling steel for ultra-wide saw blades according to claim 1, characterized in that: In step (d), after the rough rolling is completed, the rolled piece is rotated 90 degrees and sent to the finishing mill for further rolling.

5. The method for rolling steel for ultra-wide saw blades according to claim 1, characterized in that: In step (e), in the first pass of finish rolling, the workpiece is rotated 90° and then all the steel is fed transversely for elongation rolling.

6. The method for rolling steel for ultra-wide saw blades according to claim 1, characterized in that: In step (e), the finishing mill is descaled at the entrance only in the first pass.