CN117619889A - Flexible production line and production process for endless rolled strip steel - Google Patents

Abstract

The invention discloses a flexible production line and a flexible production process of endless rolled strip steel. The production line is arranged behind the continuous casting machine and comprises a pre-rolling unit, a tunnel furnace, a rough rolling unit, an induction heating device, a finishing mill unit, a laminar flow cooling device and a coiling unit which are sequentially arranged; the pre-rolling mill group is used for pre-rolling or idle; the distance between the rough rolling and the finishing mill group is 15-45 m; the tunnel furnace is used for carrying out uniform temperature treatment; the induction heating device is used for temperature regulation. The three units comprising the pre-rolling unit are arranged in the production line, the tunnel furnace and the induction heating device are adopted in the heating process, the distance between the rough rolling unit and the finish rolling unit is improved, and the device has the applicable capability of wider steel flux, compact structure and reasonable arrangement. The production line is applicable to the variation range of the steel passing amount of 3-10t/min, and realizes continuous endless rolling of finished strip steel with the thickness of 0.7-25.4 mm.

Description

Flexible production line and production process for endless rolled strip steel

Technical Field

The invention relates to the technical field of continuous casting and rolling steel, in particular to a flexible production line and a flexible production process of endless rolled strip steel with wide steel flux applicability. The typical production line is to pass the steel quantity change range of 3-10t/min on the same production line, so as to realize continuous casting and continuous rolling endless rolling of the strip steel.

Background

Compared with the conventional hot rolled strip steel, the headless continuous casting and rolling process flow is compact, the energy consumption is low, and the metal yield and the production rhythm are obviously improved; the continuous casting has high drawing speed and high production efficiency. The endless rolling omits the strip steel threading and tail flicking processes during single rolling, the precision and stability of the strip steel size and performance are obviously improved, the thickness specification of the strip steel which can be stably produced is as low as 0.8mm, the realization of replacing cold with heat is realized, and the production cost of the strip steel is reduced. Continuous casting and rolling technology is used as a revolutionary hot rolled strip steel production technology, has many advantages which are not possessed by conventional hot continuous rolling, but certain requirements on steel passing quantity are put on in order to realize endless rolling.

Such as: the matching condition of a furnace machine under the conditions of a steel supply period of 30min and a slab thickness of 110mm of a 120t converter is shown in Table 1; the matching conditions of the two 120t converters and the furnace machine are shown in Table 2 under the conditions of a steel supply period of 30min and a slab thickness of 110 mm.

Table 1 a 120t converter machine match

Table 2 matching condition of two 120t converter machines

As can be seen from the calculations in tables 1 and 2, it is substantially impossible to achieve endless rolling on one line, subject to the limitations of rolling speed and casting speed; flexibility and adaptability are greatly limited. Different steel passing amounts often relate to a plurality of production lines, so that investment is increased, and market adaptability and production cost are affected.

Disclosure of Invention

According to one embodiment of the invention, the invention aims to provide a flexible production line and a production process of endless rolled strip steel with wide steel throughput adaptability, wherein the production line can be applicable to the steel throughput change range of 3-10t/min, realize continuous endless rolling of finished strip steel with the thickness of 0.7-25.4 mm, and solve the problems of limited flexibility and adaptability of the conventional rolling process.

The above object can be achieved by the following embodiments of the present invention:

according to one aspect of the invention, the invention provides a flexible production line for endless rolled strip steel, which comprises a pre-rolling unit, a tunnel furnace, a roughing unit, an induction heating device, a finishing unit, a laminar flow cooling device and a coiling unit which are sequentially arranged;

wherein, the rolling whole line adopts continuous endless rolling; the pre-rolling mill group is used for pre-rolling or emptying continuous casting billets and comprises at least 1 pre-rolling stand arranged along the rolling direction; the roughing mill unit comprises at least 3 roughing stands arranged along the rolling direction; the finishing mill group comprises 3-5 finishing mill frames arranged along the rolling direction; the distance between the rough rolling unit and the finish rolling unit is 15-50 m; the tunnel furnace is arranged between the pre-rolling unit and the rough rolling unit and is used for carrying out uniform temperature treatment on the intermediate billet I from the pre-rolling unit; the induction heating device is arranged between the rough rolling unit and the finishing mill unit and is used for adjusting the temperature of the rough rolled intermediate billet II.

Optionally, a first high-pressure water descaling device is arranged in front of the pre-rolling mill group and is used for primarily descaling the continuous casting billets which enter the pre-rolling mill group in advance; a second high-pressure water descaling device is arranged in front of the roughing mill set and is used for performing secondary descaling on the intermediate billet I which enters the roughing mill set in advance; a third high-pressure water descaling device is arranged in front of the finishing mill group and is used for descaling the intermediate billet II which enters the finishing mill group for three times.

According to another aspect of the invention, the invention provides a flexible production process of endless rolled strip steel, comprising:

the continuous casting billet from the continuous casting machine enters a pre-rolling mill set for pre-rolling or is free to pass through, so as to obtain an intermediate billet I; wherein the rolling reduction is 20-40 mm during pre-rolling; the steel passing amount of the production line ranges from 3 t/min to 10t/min;

the intermediate blank I is subjected to temperature compensation by using a tunnel furnace, and enters a roughing mill for rolling after temperature compensation to obtain an intermediate blank II; wherein, the first pass of rough rolling is not less than 40mm, the second pass is not less than 30mm and the third pass is not less than 16 mm;

the intermediate blank II is subjected to temperature regulation by utilizing an induction heating device, and is subjected to dynamic recovery and recrystallization for 5-25 seconds, and enters a finishing mill group for rolling to obtain finished strip steel; wherein, the thickness of the finished strip steel is 0.7-25.4 mm;

and (5) cooling the finished strip steel sequentially, cutting, and collecting the finished strip steel into rolls.

Optionally, the temperature compensation process by using the tunnel furnace comprises the following steps: ensuring the temperature difference of the intermediate billet I to be within 15 ℃ before entering a roughing mill for rolling; controlling the temperature equalizing time in the transportation process within the range of 8-15 min; ensuring that the structure state of the blank is in an austenite region; ensuring that the temperature of the intermediate billet I at the inlet of the roughing stand is not lower than 940 ℃.

Optionally, the step of adjusting the temperature by using an induction heating device includes: determining a temperature system according to rolling requirements; and adopting the temperature system to regulate the temperature. Further, the step of determining the temperature system according to the rolling requirement comprises the following steps: when austenite rolling is carried out, the temperature of the intermediate blank II at the inlet of the finish rolling frame is 965-995 ℃ through temperature adjustment; when ferrite rolling is performed, the temperature of the intermediate billet II at the inlet of the finish rolling stand is 885-915 ℃ by temperature adjustment.

Optionally, the step of rolling in the finishing mill group includes: and controlling the outlet temperature of the strip steel in the finish rolling frame according to the rolling requirement. Further, when austenite rolling is carried out, controlling the outlet temperature of the strip steel in a finish rolling frame to be 825-855 ℃; when ferrite rolling is carried out, the outlet temperature of the strip steel in a finish rolling frame is controlled to be 755-785 ℃.

Optionally, the step of collecting the roll includes: and controlling the coiling temperature of the strip steel according to the rolling requirement. Further, when austenite rolling is performed, the coiling temperature of the strip steel is controlled to be 350-700 ℃; when ferrite rolling is performed, the coiling temperature of the strip steel is controlled to be 650-750 ℃.

Optionally, the generating process further includes: and determining whether the pre-rolling mill group performs pre-rolling according to the steel passing amount. Further, when the steel passing amount is more than or equal to a preset value, a pre-rolling unit is adopted to pre-roll the continuous casting billet; and when the steel passing amount is less than a preset value, the pre-rolling unit performs blank processing on the continuous casting billet. Further, the preset value is set in a range of 4.0t/min to 8.0t/min.

Optionally, before the continuous casting slab enters the pre-rolling mill set, the method further comprises: preliminary descaling is carried out by adopting a first high-pressure water descaling device, wherein the descaling pressure is 3-10 bar; before the intermediate billet I enters the roughing mill train, the method further comprises: performing secondary descaling by adopting a second high-pressure water descaling device, wherein the descaling pressure is 380bar; before the intermediate billet II enters the finishing mill group, the method further comprises the following steps: and (3) performing three times of descaling by adopting a third high-pressure water descaling device, wherein the descaling pressure is 380bar.

Optionally, the thickness of the continuous casting blank is 140-160 mm; the thickness of the intermediate blank I is 110-120 mm; the thickness of the intermediate blank II is 5-35 mm.

Optionally, the continuous casting outlet temperature of the continuous casting billet is 1000-1060 ℃.

The beneficial effects are that: according to one embodiment of the invention, three units comprising the pre-rolling unit are arranged in the production line, a tunnel furnace and an induction heating device are adopted in the heating process, and the distance between the rough rolling unit and the finish rolling unit is improved, so that the flexibility and the adaptability of the production line are improved, the production line has wide steel throughput adaptability ranging from 3 t/min to 10t/min, and finished strip steel with the thickness of 0.7-25.4 mm can be continuously endless rolled. Based on the production line, the production process disclosed by the invention is adopted, whether the pre-rolling mill set participates in preparing a large-scale steel flux change or not is adopted, and the material structure is controlled under the optimal supercooling degree and temperature combination condition through the control of the whole process temperature and the structure.

Compared with the prior art, the embodiment of the invention has the following advantages:

1. according to some embodiments of the invention, the provided process paths of pre-rolling, rough rolling and finish rolling can realize the production of continuous casting billets with two or more billet thicknesses in a tunnel furnace and subsequent rolling, effectively solve the problems of continuous casting and continuous rolling of strip steel with the steel passing amount variation range of 3-10t/min on one production line, and have wider application range of steel types, thickness and width and more flexible production.

2. According to some embodiments of the invention, a tunnel furnace is arranged between pre-rolling and rough rolling, the tunnel furnace realizes temperature compensation of the intermediate billet I after rough rolling, the temperature difference of the intermediate billet I before rolling is controlled to be +/-15 ℃, the temperature equalizing time in the transportation process is controlled to be 8-15 min, the structure state is in an austenite region, rolling is carried out by adopting large reduction, an as-cast structure is crushed, and preparation of the structure state and the uniform temperature state is completed for further rolling. And the composition segregation in the solidification process is effectively eliminated, and particularly, the chemical composition of the high-strength steel with high alloy composition is fully homogenized before rolling, so that single-phase austenite with uniform composition is obtained, and the production of the high-strength steel, the dual-phase steel and part of excellent steel is facilitated.

3. According to some embodiments of the invention, the spacing between the roughing mill group and the finishing mill group is controlled to be 15-50 m, so that the dynamic recovery and recrystallization time is 5-25 s before finishing rolling, thereby obtaining a more compact and uniform austenite structure and providing preparation for further controlling the shape, the dimensional accuracy and the rolling stability.

4. According to some embodiments of the invention, an induction heating device is arranged between rough rolling and finish rolling, the heating temperature of the intermediate billet II after rough rolling is adjusted through induction heating, and a temperature system is flexibly formulated according to requirements, so that the rolling production line adopts a headless mode to finish rolling to produce various multi-variety multi-specification strip steel with rolling thickness of 0.7-25.4 mm.

5. According to some optional embodiments of the invention, a high-pressure water rough descaling device is arranged in front of the pre-rolling mill group to perform preliminary descaling, wherein the descaling pressure is as follows: 3-10 bar; the high-pressure in-water descaling device is arranged in front of the roughing stand for secondary descaling, and the descaling pressure is as follows: 380bar; the high-pressure water fine descaling device is arranged in front of the finish rolling frame for three times of descaling, and the descaling pressure is as follows: 380bar. The three-stage descaling can avoid the defect of scale residue on the surface of the finished strip steel caused by pressing the scale into the strip steel in the rolling stage, and can obviously improve the surface quality of the strip steel.

In addition, the production line has wider application range to steel types, thickness and width, has the advantages of low cost, high production rate, high product quality and the like, and the strip steel produced by adopting the production line and the production process has good strength, bending index, uniform structure and good surface quality; the method is simple and easy to implement, has flexible and efficient organization state, can be suitable for continuous casting and rolling endless rolling production of the strip steel with the steel passing quantity ranging from 3 t/min to 10t/min, has stable quality control and wide popularization prospect, is a current technical development trend, and is also a market demand place.

Additional advantages, objects, and features of embodiments of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and other advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the specification.

Drawings

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in the following preferred detail with reference to the accompanying drawings, in which:

fig. 1 is a schematic layout view of a flexible production line of endless rolled steel strip for continuous casting of steel strip in an embodiment of the present invention.

Reference numerals: the continuous casting machine comprises a continuous casting machine 1, a high-pressure water descaling device 2, a pre-rolling mill group 3, a pendulum shear 4, a tunnel furnace 5, a waste billet pushing and stacking device 6, a high-pressure water descaling device 7, a roughing mill group 8, a rotary drum flying shear 9, an induction heating device 10, a high-pressure water fine descaling device 11, a finishing mill group 12, an ultra-fast cooling device 13, a laminar cooling device 14, a high-speed flying shear 15, a coiling unit 16, a continuous casting billet 201, an intermediate billet I202, an intermediate billet II 203 and strip steel 204.

Detailed Description

The technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

According to the invention, the flexible production line of the endless rolled strip steel for strip steel continuous casting comprises a pre-rolling unit, a tunnel furnace, a rough rolling unit, an induction heating device, a finishing mill unit, a laminar flow cooling device and a coiling unit which are sequentially arranged. The pre-rolling mill group is used for pre-rolling or emptying continuous casting billets. The distance between the rough rolling unit and the finish rolling unit is 15-50 m. The tunnel furnace is arranged between the pre-rolling unit and the roughing unit and is used for carrying out temperature equalization treatment on the intermediate billet I coming out of the pre-rolling unit. The induction heating device is arranged between the rough rolling unit and the finishing mill unit and is used for adjusting the temperature of the rough rolled intermediate billet II. In addition, continuous endless rolling is adopted in the whole rolling process. The pre-rolling train comprises at least 1 pre-rolling stand arranged in the rolling direction. The roughing train comprises at least 3 roughing stands arranged in the rolling direction. The finishing mill group comprises 3-5 finishing mill frames arranged along the rolling direction.

In an alternative embodiment, a first high-pressure water descaling device is also arranged in front of the pre-rolling mill group and is used for primarily descaling the continuous casting billets entering the pre-rolling mill group. The second high-pressure water descaling device is arranged in front of the roughing mill set and is used for performing secondary descaling on the intermediate billet I which enters the roughing mill set in advance. A third high-pressure water descaling device is arranged in front of the finishing mill group and is used for descaling the intermediate billet II which enters the finishing mill group for three times.

According to the flexible production process of the endless rolled strip steel for strip steel continuous casting provided by the embodiment of the invention, the flexible production process comprises the working procedures of pre-rolling, soaking in a tunnel furnace, rough rolling, induction heating, finish rolling, laminar cooling, coiling and the like. Specifically, the method comprises the following steps:

and S10, pre-rolling or emptying a continuous casting billet with the thickness of 140-160 mm from an outlet of the continuous casting machine through a pre-rolling mill set consisting of 1 two-roll mill along the rolling direction to obtain an intermediate billet I with the thickness of 110-120 mm. Wherein the rolling mill rolling reduction is 20-40 mm during pre-pressing.

In addition, the continuous casting drawing speed of the continuous casting machine can be 5.5-6 m/min. The continuous casting outlet temperature of the continuous casting blank can be 1030+/-30 ℃.

In an alternative embodiment, it is determined whether the pre-rolling train is pre-rolled based on the amount of steel passing. Further, when the steel passing amount is more than or equal to a preset value, a pre-rolling unit is adopted to pre-roll the continuous casting billet; and when the steel passing amount is less than a preset value, the pre-rolling unit performs blank processing on the continuous casting billet. Wherein the preset value is set to be 4.0 t/min-8.0 t/min. Of course, it is also possible to determine whether the pre-rolling train is pre-rolled directly from the thickness of the continuous casting billet, for example if the thickness of the continuous casting billet is greater than 120mm; and (5) carrying out blank passing at a speed of less than or equal to 120mm.

In a specific embodiment, when the steel flux is more than or equal to 6.0t/min, a pre-rolling unit is adopted to pre-roll the continuous casting billet; and when the steel flux is less than 6.0t/min, the pre-rolling unit performs blank treatment on the continuous casting billet. And whether the pre-rolling mill group participates or not is used for preparing a wide range of steel passing amount change, and the control of the material structure under the optimal supercooling degree and temperature combination condition is realized by combining the temperature and structure control of the whole process.

And S20, after the intermediate blank I is subjected to temperature compensation through a tunnel furnace, continuously rolling through a roughing mill set consisting of 3 or more four-high rolling mill sets which are sequentially arranged along the rolling direction, and obtaining an intermediate blank II with the thickness of 5-35 mm. Wherein, rough rolling unit adopts the suppression of big screw down volume, and specific screw down volume is: the first pass of rough rolling is not less than 40mm, the second pass is not less than 30mm and the third pass is not less than 16mm.

The tunnel furnace is arranged between the pre-rolling and the rough rolling, and the temperature equalization of the intermediate billet I after the pre-rolling is realized through the temperature compensation of the tunnel furnace. In the preferred embodiment, the temperature is compensated by a tunnel furnace to ensure that the temperature difference of the intermediate blank I is controlled to be +/-15 ℃ before rolling, the temperature equalizing time in the transportation process is controlled to be 8-15 min, and the structure state is in an austenite region; in addition, the temperature of the intermediate billet I at the inlet of the roughing stand is not lower than 940 ℃ by supplementing the temperature of the tunnel furnace. The uniform temperature of the intermediate billet I after pre-rolling is realized through the four core control requirements.

In addition, the large reduction rolling is adopted to crush the cast structure, so as to prepare the structure state and the uniform temperature state for further rolling. And the composition segregation in the solidification process is effectively eliminated, and particularly, the chemical composition of the high-strength steel with high alloy composition is fully homogenized before rolling, so that single-phase austenite with uniform composition is obtained, and the production of the high-strength steel, the dual-phase steel and part of excellent steel is facilitated.

Step S30, the intermediate blank II is subjected to temperature regulation by using an induction heating device, and after the temperature regulation, the intermediate blank II enters a finishing mill group formed by 3-5 four-roller mills which are sequentially arranged along the rolling direction to continuously roll finished strip steel with the thickness of 0.7-25.4 mm; the finished strip steel is subjected to controlled cooling sequentially through an ultra-fast cooling device and a laminar flow cooling device, and the cooled finished strip steel is collected into rolls through a coiling machine after being cut by a high-speed flying shear.

Based on the condition that the distance between a rough rolling unit and a finishing mill unit in a production line is 15-50 m, an induction heating device is arranged between rough rolling and finishing rolling, the heating temperature of a rough rolled intermediate billet II is adjusted through induction heating, and a temperature system is flexibly formulated according to requirements, so that the rolling production line adopts a headless mode to finish rolling and produce various and multi-specification strip steel with rolling thickness of 0.7-25.4 mm. Here, the temperature regime is set according to the type of structure of the rolled product, for example, austenite, ferrite, etc., as needed. Different steel grades have different temperature control requirements.

The induction heating device is used for heating and controlling the temperature of the intermediate blank II, realizing the temperature switching required by austenite rolling and ferrite rolling, ensuring the dynamic recovery and recrystallization time before finish rolling for 5-25 s, obtaining a more compact and uniform austenite structure, and providing tissue preparation for further controlling the shape, the dimensional accuracy and the rolling stability. During the finish rolling stage, the intermediate blank II is rolled by austenite temperature rolling in at least 3 continuous finish rolling frames or ferrite temperature rolling in at least 3 continuous finish rolling frames.

In an alternative embodiment, the austenitic rolling is performed with the intermediate billet II at an entry temperature of 980 ℃ + -15 ℃ in the finishing stand, the strip steel at an exit temperature of 840 ℃ + -15 ℃ in the finishing stand, and the strip steel coiling temperature of 350 ℃ -700 ℃. When ferrite rolling is carried out, the temperature of the intermediate blank II at the inlet of a finish rolling frame is 900+/-15 ℃, the temperature of the strip steel at the outlet of the finish rolling frame is 770+/-15 ℃, and the coiling temperature of the strip steel is 650-750 ℃.

In an alternative embodiment, the process further comprises three stages of descaling, each of which is performed before the blanks enter the roughing mill train and before the blanks enter the finishing mill train. The descaling configuration can avoid the defect of scale residue on the surface of the finished strip steel caused by pressing the scale into the strip steel in the rolling stage, and can obviously improve the surface quality of the strip steel. Further, when a high-pressure water descaling device is arranged in front of the pre-rolling mill set to perform preliminary descaling, the descaling pressure is controlled to be 3-10 bar. When a high-pressure water descaling device is arranged in front of the roughing stand to perform secondary descaling, the descaling pressure is controlled as follows: 380bar. The high-pressure water descaling device is arranged in front of the finish rolling frame for three times of descaling, and the descaling pressure is as follows: 380bar.

In an alternative embodiment, the process further comprises finish rolling and accident handling of the post-finish rolling process. In the production line adopted by the process, a pendulum shear is arranged on a rolling production line between a pre-rolling stand and a tunnel furnace, a billet pushing and stacking device is arranged on the rolling production line between the tunnel furnace and a rough rolling stand, and a rotary drum flying shear is arranged between the rough rolling stand and an induction heating device for accident treatment and head and tail shearing. The method can comprise the following steps: when accidents occur in the working procedures of finish rolling and post-finish rolling, a finishing mill frame is lifted to form a roll gap, continuous casting is carried out, a fixed-length billet with the length of 23.9m is sheared by a swinging shear, the scrap steel is removed after the rolled piece between the swinging shear and the accident shear is broken, the fixed-length shear is carried out on the intermediate billet I after rough rolling by the swinging shear and is sent to a tunnel furnace for soaking, at the moment, the continuous casting pulling speed is controlled to be 3.0-3.5 m/min, the advancing speed of the tunnel furnace is controlled to be 3.5m/min, and the strip threading rolling is carried out again after the accident treatment is completed.

Fig. 1 schematically shows a flexible production line for endless rolled strip steel in continuous casting, which is provided by an embodiment of the invention, and comprises a continuous casting machine 1, a high-pressure water descaling device I2, a pre-rolling mill group 3, a pendulum shear 4, a tunnel furnace 5, a waste billet pushing-out and stacking device 6, a high-pressure water descaling device II 7, a rough rolling mill group 8, a rotary drum flying shear 9, an induction heating device 10, a high-pressure water descaling device III 11, a finishing mill group 12, an ultra-fast cooling device 13, a laminar cooling device 14, a high-speed flying shear 15 and a coiling unit 16 which are connected in sequence.

Wherein, the pre-rolling unit 3 includes 1 two-roll mill that sets up along the rolling direction, and the roughing unit 8 includes 3 four-roll mill that set gradually along the rolling direction, and the finishing mill unit 12 includes 5 four-roll mill that set gradually along the rolling direction, and the coiling unit 16 includes 3 recoilers that set gradually along the rolling direction.

In the production line provided according to an embodiment of the present invention, the roughing mill group and finishing mill group are controlled to have a pitch of 15 to 50m, for example, 15m,20m,25m,30mm,35m,40m,45m,50m, etc., which allows a dynamic recovery and recrystallization time of 5 to 25s before finishing, thereby obtaining a more compact and uniform austenitic structure, providing a preparation for further controlling the plate shape, dimensional accuracy and rolling stability.

In an alternative embodiment, the distance between the outlet of the continuous casting machine and the centre line of the roll stand of the pre-rolling train is 5-8 m. The distance between the center line of the rolling frame of the pre-rolling mill set and the tunnel furnace mouth is 6-10 m. The distance between the outlet of the tunnel furnace and the central line of the first rolling stand of the roughing mill set is 6-10 m. The distance between the adjacent roughing stands of the roughing mill set is 4-5 m. The distance between the rough rolling unit and the finishing rolling unit is controlled to be 15-45 m. The distance between the center lines of adjacent finishing frames of the finishing mill group is 4-5 m. The center line distance between the last finishing mill frame of the finishing mill group along the rolling direction and the first coiling machine of the coiling machine group along the rolling direction is 50-120 m.

As shown in FIG. 1, in this example, the interval between the outlet of the continuous casting machine 1 and the center line of the rolling stand of the pre-rolling mill group was 6.9m, the interval between the center line of the rolling stand of the pre-rolling mill group and the center line of the first rolling stand of the roughing mill group was 8.9m, the interval between the outlet of the tunnel furnace and the center line of the first rolling stand of the roughing mill group was 8.65m, the interval between the adjacent roughing stands of the roughing mill group was 5m, the interval between the roughing mill group and the center line of the finishing mill group was controlled to be 25.5m, the intervals between the center lines of the adjacent finishing mill stands of the finishing mill group were 5m,4.8m and 4.8m in this order, and the interval between the center line between the last finishing mill stand of the finishing mill group and the first rolling stand of the rolling mill group in the rolling direction was 83.95m.

The production line of the embodiment comprises the following steps: 1) After being subjected to preliminary descaling by a high-pressure water descaling device 2, a continuous casting billet 201 with the thickness of 150mm cast by the continuous casting machine 1 enters a pre-rolling mill group 3, the rolling reduction of the rolling mill is 30mm, and an intermediate billet I202 with the thickness of 120mm is obtained. Wherein the continuous casting pulling speed of the continuous casting machine 1 is 5.5-6 m/min, and the continuous casting outlet temperature of the continuous casting billet 201 is 1030+/-30 ℃. 2) The intermediate billet I202 is subjected to secondary descaling by a high-pressure water descaling device II 7 after being subjected to temperature equalization by the tunnel furnace 5, and the intermediate billet I202 subjected to secondary descaling is continuously rolled into an intermediate billet II 203 with the thickness of 5-35 mm by 3 four-high rolling mills sequentially arranged along the rolling direction. 3) The intermediate blank II 203 is subjected to temperature adjustment by an induction heating device 9 and then is subjected to three-time descaling by a high-pressure water descaling device III 11, and the intermediate blank II 203 subjected to three-time descaling is continuously rolled into a finished strip steel 204 with the thickness of 0.7-25.4 mm by 5 finishing rolling frames which are sequentially arranged along the rolling direction; the finished strip steel 204 is cooled by the ultra-fast cooling device 13 and the laminar cooling device 14 in sequence, and the cooled finished strip steel 204 is cut by the high-speed flying shears 15 and then is collected into rolls by a coiling machine.

More specifically, a complete continuous casting and rolling process of the continuous casting and rolling continuous strip rolling line shown in fig. 1 is adopted, as follows:

the full-line equipment is ready for casting, pre-rolling, rough rolling, finish rolling and coiling, the pre-swinging roll gap is in place, the continuous casting machine 1 is started for casting, when the dummy bar head passes through the last segment of the sector section, the hydraulic cylinder of the dummy bar removing device acts, the head of the dummy bar is lifted, the casting blank is separated from the dummy bar, and the dummy bar rapidly runs and is stored on the storage rack. And rolling the 150mm thick casting blank into an intermediate blank I202 with the thickness of 120mm through a pre-rolling mill set. When the casting blank is conveyed to the pendulum shear, the blank head is cut, and then the pendulum shear carries out automatic cutting with fixed length, multiple length cutting or a headless mode according to the process requirements. And (5) conveying the casting blank with the fixed length, the multiple length or the headless mode after being cut by the pendulum shear to a tunnel furnace through a conveying roller way.

The strip steel sequentially passes through a high-pressure water descaling device I2, a pre-rolling mill group (R0), a pendulum shear 4, a tunnel furnace 5, a high-pressure water descaling device II 7, a rough rolling mill group 8 (R1, R2 and R3), a rotary drum flying shear 9, an induction heating device 10, a high-pressure water descaling device III 11, a finishing mill group 12 (F1, F2, F3, F4 and F5), an ultra-fast cooling device 13, a laminar cooling device 14, a high-speed flying shear 15 and a coiling unit 16, and after rolling parameters are adjusted by 2-3 fixed-length billets (the fixed length is 23.9 m), the strip steel starts endless rolling; after the current coil weight reaches the standard, shearing by a high-speed flying shear 15, and finishing the threading switching of different coiling machines of the next coil of strip steel by a quick switching device of a coiling unit 16; during endless rolling, the strip steel is produced according to the principle that the thickness of the strip steel is reduced from thickness to thickness and then reduced from thickness to thickness, and the strip rolling process involves dynamic specification change of a rolling mill and strip-carrying channeling of a roller.

The roll replacement of the finishing mill can occur for 1-3 times at the same casting time, the swing shear carries out fixed-length shearing on the rough rolled intermediate billet I and sends the intermediate billet I to the tunnel furnace for soaking, at the moment, the continuous casting pulling speed is controlled to be 3.0-3.5 m/min, the advancing speed of the tunnel furnace is controlled to be 3.5m/min, three-end two-branch fixed-length billets are usually adopted, the roll replacement process is completed, and the whole process is about 8-10 minutes.

Until the casting end is approached, the rolled piece continues to finish rolling, and the casting is finished.

In addition, for endless rolling production, the rolling piece stacking or breaking accidents easily occur in the finish rolling process, so that the accident treatment of the production line is considered in time, the continuous casting of the current ladle molten steel is ensured as much as possible, and the loss is reduced. Therefore, in the production process provided by an embodiment of the present invention, the accident treatment plan of the rolling line is as follows: when accidents occur in the working procedures after finish rolling and finish rolling, a finishing mill frame is lifted to form a roll gap, continuous casting is carried out, a fixed-length billet with the length of 23.9m is sheared by a swinging shear, the scrap steel is removed after the rolled piece between the swinging shear and the accident shear is broken, the fixed-length shear is carried out on the intermediate billet I after rough rolling by the swinging shear and is sent to a tunnel furnace for soaking, at the moment, the pulling speed of continuous casting is controlled to be 3.0-3.5 m/min, the advancing speed of the tunnel furnace is controlled to be 3.5m/min, and the continuous casting is carried out again after the accidents are processed. In addition, when the treatment time is long, the waste blank is transported to the area of the blank pushing and stacking device 5, the waste blank is pushed out of the rolling line, and the casting is completed.

Example 1

The following will specifically explain the process flow of producing the strip steel 204 by the rolling process of 150mm in thickness of the continuous casting slab in the present invention by way of examples.

The steel strip comprises the following chemical components in percentage by mass: less than or equal to 0.045% of C, less than or equal to 0.15% of Mn, less than or equal to 0.035% of Si, less than or equal to 0.020% of P, less than or equal to 0.005% of S, less than or equal to 0.08% of Nb+Ti, less than or equal to 0.05% of Als, and the balance of Fe and impurities.

Molten steel is cast into a continuous casting blank with the thickness of 150mm through a high-speed continuous casting process, the continuous casting drawing speed is controlled to be 5.5m/min, and the surface temperature of a continuous casting blank at a continuous casting outlet is 1030+/-30 ℃. After scale on the surface of a casting blank is removed by high-pressure water, the casting blank is rolled by a 1-frame pre-rolling mill set (R0) to obtain an intermediate blank I with the thickness of 120mm. At this time, the temperature was reduced to 950.+ -. 40 ℃.

And (5) adopting a tunnel furnace to supplement the temperature to 1005+/-10 ℃. And then removing scale on the surface of the casting blank by high-pressure water, wherein the temperature is about 1000+/-10 ℃ when rough rolling is carried out, and the thickness of the intermediate blank II is changed into 10mm after rolling by 3 rough rolling frames (R1, R2 and R3). The large rolling reduction is adopted to crush the cast structure, so as to prepare the structure state and the uniform temperature state for further rolling. And the component segregation in the solidification process is effectively eliminated, and particularly, the chemical cost of the high-strength steel with high alloy components is sufficiently homogenized before rolling, so that the single-phase austenite with uniform components is obtained. At this time, the temperature was slightly lowered to 980.+ -. 10 ℃.

The intermediate transportation channel has 10-12 s of dynamic recovery and recrystallization time, so as to obtain more compact and uniform austenite structure. The inlet temperature of the induction heating device is reduced to 920+/-10 ℃, the temperature is regulated to 950+/-10 ℃ by the induction heating device, and then the steel is descaled by the high-pressure water descaling device and then enters the finishing mill group 12 for rolling. Passing through 5 finishing mill groups (F1, F2, F3, F4 and F5), wherein the temperature at the inlet of a first finishing mill frame F1 is 950+/-10 ℃, the finish rolling is changed into strip steel 204 with the thickness of 0.8mm, the speed of the strip steel 204 at the finish rolling outlet is 13.55m/s, and the temperature at the finish rolling outlet is 900+/-10 ℃. Finally, the temperature of the strip steel 204 at the inlet of the coiling machine is 700+/-10 ℃ through the control of ultra-fast cooling after rolling and laminar cooling, and the strip steel curling and bundling are completed.

Example 2

The following will specifically explain the process flow of producing the strip steel 204 by the rolling process of 120mm in continuous casting thickness in the present invention by way of examples.

The strip steel of a certain continuous casting and rolling production line comprises the following chemical components in percentage by mass: c is less than or equal to 0.15%, si is less than or equal to 0.03%, mn is less than or equal to 0.15%, P is less than or equal to 0.015%, S is less than or equal to 0.008%, als is less than or equal to 0.04%, and the balance is Fe and impurities.

The molten steel is cast into a continuous casting blank 201 with the thickness of 120mm through a high-speed continuous casting process, the continuous casting drawing speed is controlled to be 5.5m/min, the surface temperature of the continuous casting blank at a continuous casting outlet is 1030+/-10 ℃, the intermediate blank I is cooled to 920+/-40 ℃ after being subjected to descaling through high-pressure water and then being rolled through 1 pre-rolling mill sets (R0).

And (5) adopting a tunnel furnace to supplement the temperature to 955+/-10 ℃. The intermediate billet I with the thickness of 20mm is rolled by 3 roughing stands (R1, R2 and R3) at the rough rolling temperature of 950+/-10 ℃ after the descaling by high-pressure water, and the cast structure is crushed by adopting large rolling reduction, so that the preparation of the structure state and the uniform temperature state is finished for further rolling. And the component segregation in the solidification process is effectively eliminated, and particularly, the chemical cost of the high-strength steel with high alloy components is sufficiently homogenized before rolling, so that the single-phase austenite with uniform components is obtained. At this point the temperature was slightly reduced to 900 ℃ ± 10 ℃.

The intermediate transportation channel has 10-15s of dynamic recovery and recrystallization time, so that a more compact and uniform austenite structure is obtained, the inlet temperature of the induction heating device is reduced to 920+/-10 ℃, the temperature is regulated to 950+/-10 ℃ by the induction heating device, and the austenite structure enters a finishing mill group for rolling after descaling by the high-pressure water descaling device. Rolling by 5 finishing mill groups 12 (F1, F2, F3, F4 and F5), wherein the temperature at the inlet of a first finishing mill frame F1 is 950+/-10 ℃, the finish rolling is finished to obtain strip steel 204 with the thickness of 3.5mm, the speed of the finish rolling outlet strip steel 204 is 8.0m/s, the finish rolling outlet temperature is 770+/-10 ℃, and finally the temperature of the strip steel 204 at the inlet of a coiling machine is 650+/-10 ℃ by controlling ultra-fast cooling and laminar cooling after rolling, so that the strip steel is coiled and bundled.

The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims (10)

1. The flexible production line of the endless rolled strip steel is characterized by comprising a pre-rolling unit, a tunnel furnace, a rough rolling unit, an induction heating device, a finishing mill unit, a laminar flow cooling device and a coiling unit which are sequentially arranged; wherein, the rolling whole line adopts continuous endless rolling;

the pre-rolling mill group is used for pre-rolling or emptying continuous casting billets and comprises at least 1 pre-rolling stand arranged along the rolling direction;

the roughing mill unit comprises at least 3 roughing stands arranged along the rolling direction;

the finishing mill group comprises 3-5 finishing mill frames arranged along the rolling direction;

the distance between the rough rolling unit and the finish rolling unit is 15-50 m;

the tunnel furnace is arranged between the pre-rolling unit and the rough rolling unit and is used for carrying out uniform temperature treatment on the intermediate billet I from the pre-rolling unit;

the induction heating device is arranged between the rough rolling unit and the finishing mill unit and is used for adjusting the temperature of the rough rolled intermediate billet II.

2. The endless rolled steel strip flexible production line of claim 1, wherein,

a first high-pressure water descaling device is arranged in front of the pre-rolling mill group and is used for primarily descaling the continuous casting billets which enter the pre-rolling mill group in advance;

a second high-pressure water descaling device is arranged in front of the roughing mill set and is used for performing secondary descaling on the intermediate billet I which enters the roughing mill set in advance;

a third high-pressure water descaling device is arranged in front of the finishing mill group and is used for descaling the intermediate billet II which enters the finishing mill group for three times.

3. A process for the flexible production of endless rolled steel strip using the flexible production line of endless rolled steel strip as claimed in any one of claims 1 to 2, comprising:

the continuous casting billet from the continuous casting machine enters a pre-rolling mill set for pre-rolling or is free to pass through, so as to obtain an intermediate billet I; wherein the rolling reduction is 20-40 mm during pre-rolling; the steel passing amount of the production line ranges from 3 t/min to 10t/min;

the intermediate blank I is subjected to temperature compensation by using a tunnel furnace, and enters a roughing mill for rolling after temperature compensation to obtain an intermediate blank II; wherein, the first pass of rough rolling is not less than 40mm, the second pass is not less than 30mm and the third pass is not less than 16 mm;

the intermediate blank II is subjected to temperature regulation by utilizing an induction heating device, and is subjected to dynamic recovery and recrystallization for 5-25 seconds, and enters a finishing mill group for rolling to obtain finished strip steel; wherein, the thickness of the finished strip steel is 0.7-25.4 mm;

and (5) cooling the finished strip steel sequentially, cutting, and collecting the finished strip steel into rolls.

4. A process for the flexible production of endless rolled steel strip according to claim 3, characterized in that it comprises, during the temperature compensation by means of a tunnel furnace:

ensuring the temperature difference of the intermediate billet I to be within 15 ℃ before entering a roughing mill for rolling;

controlling the temperature equalizing time in the transportation process within the range of 8-15 min;

ensuring that the structure state of the blank is in an austenite region;

ensuring that the temperature of the intermediate billet I at the inlet of the roughing stand is not lower than 940 ℃.

5. The process for producing endless rolled steel strip according to claim 4, wherein the step of temperature-adjusting by means of an induction heating device comprises: determining a temperature system according to rolling requirements; adopting the temperature system to regulate the temperature;

wherein, according to the rolling demand, confirm the step of temperature system, include:

when austenite rolling is carried out, the temperature of the intermediate blank II at the inlet of the finish rolling frame is 965-995 ℃ through temperature adjustment;

when ferrite rolling is performed, the temperature of the intermediate billet II at the inlet of the finish rolling stand is 885-915 ℃ by temperature adjustment.

6. The process for producing a flexible endless rolled steel strip according to claim 5, wherein the step of rolling in the finishing mill group comprises: controlling the outlet temperature of the strip steel in the finish rolling frame according to the rolling requirement;

wherein, when austenite rolling is carried out, the outlet temperature of the strip steel in a finish rolling frame is controlled to be 825-855 ℃;

when ferrite rolling is carried out, the outlet temperature of the strip steel in a finish rolling frame is controlled to be 755-785 ℃.

7. The process for producing endless rolled steel strip according to claim 6, wherein the step of collecting the coil comprises: controlling the coiling temperature of the strip steel according to the rolling requirement;

wherein, when austenite rolling is carried out, the coiling temperature of the strip steel is controlled to be 350-700 ℃;

when ferrite rolling is performed, the coiling temperature of the strip steel is controlled to be 650-750 ℃.

8. A process for the flexible production of endless rolled steel strip according to claim 3, further comprising: determining whether the pre-rolling mill group performs pre-rolling according to the steel passing amount;

when the steel passing amount is more than or equal to a preset value, a pre-rolling unit is adopted to pre-roll the continuous casting billet;

when the steel passing amount is less than a preset value, the pre-rolling unit performs blank processing on the continuous casting blank;

the setting range of the preset value is 4.0 t/min-8.0 t/min.

9. A process for producing endless rolled steel strip according to claim 3, wherein,

before the continuous casting billet enters the pre-rolling mill set, the method further comprises: preliminary descaling is carried out by adopting a first high-pressure water descaling device, wherein the descaling pressure is 3-10 bar;

before the intermediate billet I enters the roughing mill train, the method further comprises: performing secondary descaling by adopting a second high-pressure water descaling device, wherein the descaling pressure is 380bar;

before the intermediate billet II enters the finishing mill group, the method further comprises the following steps: and (3) performing three times of descaling by adopting a third high-pressure water descaling device, wherein the descaling pressure is 380bar.

10. A process for the flexible production of endless rolled steel strip according to claim 3, characterized in that,

the thickness of the continuous casting blank is 140-160 mm; the thickness of the intermediate blank I is 110-120 mm; the thickness of the intermediate blank II is 5-35 mm;

and/or the continuous casting outlet temperature of the continuous casting blank is 1000-1060 ℃.