Process and production line for manufacturing ultrathin hot rolled strips based on the thin slab technique
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B22D-011/12
B22D-011/16
출원번호
US-0501663
(2003-08-28)
등록번호
US-7343961
(2008-03-18)
우선권정보
IT-MI2002A1996(2002-09-19)
국제출원번호
PCT/IT03/000523
(2003-08-28)
§371/§102 date
20040715
(20040715)
국제공개번호
WO04/026497
(2004-04-01)
발명자
/ 주소
Arvedi,Giovanni
출원인 / 주소
Arvedi,Giovanni
대리인 / 주소
Lucas & Mercanti, LLP
인용정보
피인용 횟수 :
6인용 특허 :
4
초록▼
Ultrathin hot rolled steel strips are obtained from thin slabs using a continuous casting process and production line. The process and production line includes a secondary cooling system, a roughing mill, an induction heating zone to fix temperatures of the intermediate strip chosen between 1000 and
Ultrathin hot rolled steel strips are obtained from thin slabs using a continuous casting process and production line. The process and production line includes a secondary cooling system, a roughing mill, an induction heating zone to fix temperatures of the intermediate strip chosen between 1000 and 1400�� C., a final rolling zone to reduce the thickness of the hot finished strip while keeping a controlled temperature of the hot rolled strip from the last stand of the finishing rolling mill higher than 750�� C. The strip is cooled between the last stand of the finishing rolling mill and the coiling station using a specific T.T.T diagram (time-temperature-transformation) for steel quality and strip thickness. A control system is also provided with a master system and six further peripheric sub-systems.
대표청구항▼
The invention claimed is: 1. Process for the continuous production of an ultrathin hot rolled steel strip from a thin slab obtained by continuous casting in a mould, comprising: a continuous casting step (1); a pre-transformation (5) subsequent to the continuous casting step (1); an induction heati
The invention claimed is: 1. Process for the continuous production of an ultrathin hot rolled steel strip from a thin slab obtained by continuous casting in a mould, comprising: a continuous casting step (1); a pre-transformation (5) subsequent to the continuous casting step (1); an induction heating (8); and a final transformation (18) with previous plastic stretching (17), descaling (17a) and subsequent cooling and coiling, characterized by: the slab leaving the mould with a central crown at each side; a reduction of a slab thickness in continuous casting during solidification (3.1) by 60% at maximum, from 100 to 70 mm, until a reduction from 80 to 40 mm; a secondary cooling during a liquid steel core reduction step (3B) of the continuous casting step (1), performed by spray nozzles (3a), with the following characteristics: specific water delivery between 0.6 and 3.0 liters per kg of cast steel, decreasing cooling density in the direction of the slab advancement due to liquid core reduction, and selective control of cooling fluid flow rates between a front side and a back side of the slab; said pre-transformation being a roughing step of the thin slab upon solidification at a surface temperature of the slab >1100�� C. with not more than four passes to obtain an intermediate strip (5.3) having different thicknesses chosen in the range from 30 to 8 mm with a central crown of up to 0.4 mm at each side; said induction heating (8) being adapted to fix various temperatures of the intermediate strip chosen between 1000 and 1400�� C. and overheating function of a head and tail; said plastic stretching (17) combined with descaling (17a) to eliminate scale from the surface of the intermediate strip; said final transformation (18) being a rolling step down to a thickness of a finished strip of 0.4 mm as a minimum with not more than six passes and a controlled temperature of a hot rolled strip at an exit therefrom >750�� C. (AC1); and a controlled cooling (14) of a strip (13) in the time between the end of a final rolling (18) and the coiling until a minimum temperature of 200�� C., according to a corresponding T.T.T. diagram (14.1) specific for a steel quality of the strip thickness. 2. Process according to claim 1, characterized in that said roughing step (5) occurs directly after the slab solidification with a hot core (7) of the slab at a temperature of less than 1450�� C., near the temperature of steel solidification (7.1) higher than 1100�� C., thereby with an inverted temperature gradient (7.2) throughout half thickness of the slab. 3. Process according to claim 2, characterized in that immediately after the roughing step (5), the intermediate strip (5.3) is subjected to a crosswise separation step by cutting (10). 4. Process according to claim 3, characterized in that directly after the separation of the intermediate strip, a withdrawal (11) of plate-shaped sheets is possible by means of a cross-wise transportation. 5. Process according to claim 1, characterized in that the intermediate strip (5.3) is either directly guided to said final transformation (18) immediately after induction heating (8) in case of continuous rolling (15) or is subject to an intermediate winding (16.1) before the final rolling. 6. Process according to claim 1, characterized in that the intermediate strip (5.3) is rolled in a controlled way through six passes in a finishing mill at a maximum to a finished hot rolled strip (13) with a minimum thickness of 0.4 mm and a temperature of transformation in a range at the exit of the finishing mill from the sixth pass of final rolling (18) in a range (24) between a minimum of 750�� C. (AC1). 7. Process according to claim 6, characterized in that the intermediate strip (5.3) enters the finishing mill (18) at different speeds between 0.2 and 5.0 m/s. 8. Process according to claim 6, characterized in that between the sixth rolling pass and the coiling step, the finished hot rolled strip (13) is carried in a thermally controlled way and in the time to a final temperature higher than 200�� C. through a thermally controlled management (14) according to the T.T.T. diagram (14.1). 9. Process according to claim 8, characterized in that the thermally controlled management (14) in the time of the hot finished strip (13) with a determined thickness and chemical composition (steel analysis) by means of a cooling strategy via a cooling line (19.1), (20.1, as well as to an isolation or heating line (20.3) based on the corresponding T.T.T. diagram (14.1) desired structures and properties of the material are obtained and consequently desired steel quality between the sixth rolling pass and the coiling step. 10. Process according to claim 9, characterized in that the finished hot rolled strip (13) is wound with the desired properties of the material. 11. Process according to claim 9, characterized in that the finished strip (13) with the desired properties of the material is directly brought to subsequent working steps (20.2) without preliminary winding. 12. Process according to claim 1, comprising a process control system (22) provided with specific parameters for the steel type quality according to the T.T.T. diagram (14.1) for a treatment rolling (14) of thermo-mechanical nature, consisting in a main master system (22.7) and six process subsystems (from 22.1 to 22.6) for programming, performing and controlling the process. 13. Production line for carrying out the process of claim 1, comprising a continuous casting machine (1), for the continuous casting of thin slabs (3) with a mould having a width of 2.2 m at maximum and an exit (or outlet) for a thickness of 100-70 mm of the slab at a position (3.1) immediately downstream of the mould exit having production lines connected thereto, namely: a roughing mill (5) with not more than four rolling stands; an induction heating path (8); a finishing mill (18) with not more than six rolling stands; at least one coiling station (20); and a cooling line between the finishing mill (18) and the coiling station (20), characterized by the fact that said continuous casting machine (1) is able to give a crowned shape of the cross section of the slabs, and the production line further comprising: a roller table (3) for reducing the slab (3.1) thickness during solidification from 100 to 70 mm at the mould exit up to a solidification thickness (3.2) of 80-40 mm within the roller table itself at a casting speed of 10 m/mm; a secondary spray cooling system (3B) by means of spray nozzles in correspondence with the casting machine (1); said roughing mill (5) being equipped with rolls suitable to obtain a crown of up to 0.4 mm at each side; said induction heating path (8) having a length of 40 m at maximum, immediately downstream of the roughing mill (5) with temperatures of intermediate strip (8.1) upon leaving said path (8) of 1100-1400�� C. and suitable to control overheating of a head and tail of the intermediate strip by means of a temperature regulation algorithm; and a plastic stretching device (17) combined with a descaling device (17a), placed before said finishing mill (18), composed of a battery of upper and lower rolls in a total number of at least three. 14. Production line according to claim 13, characterized in that said roughing mill (5) is placed directly at the end of the continuous casting machine (1) at a distance of 10 m therefrom. 15. Production line according to claim 13, characterized in that immediately after the roughing mill (5) there is provided a shearing device. 16. Production line according to claim 15, characterized in that immediately after the transverse cutting device or shears (10) there is provided a cross-wise transportation device for the removal of plates from the intermediate strip. 17. Production line according to claim 13, characterized in that between the induction heating path (8) arid the plastic stretching device (17) there is provided an intermediate winding station (16.1) immediately upstream of the finishing mill (18). 18. Production line according to claim 13, characterized in that the distance between the stands of the finishing mill (18) is of 6 in at maximum. 19. Production line according to claim 13, characterized in that immediately after the last stand of the finishing mill (18) there is provided a coiling station (19) in the form of a carousel coiler, being preceded by an intensive cooling line (19.1). 20. Production line according to claim 19, comprising an additional conventional cooling line for hot rolled strip (20.1) with at least one downcoiler station (20) at the end of the production line. 21. Production line according to claim 20, characterized in that the cooling lines (19.1; 20.1) are equipped with an isolating line and/or an induction heating furnace (20.3). 22. Production line according to claim 13, characterized in that the hot rolled strip, being rolled and cooled according to a programmed thermo-mechanical rolling (14) is directly brought to the subsequent working line without preliminary coiling. 23. Production line according to claim 13, comprising a process control system (22) consisting in a "master" main system (22.7) and additional six peripheral subsystems (22.1-22.6) for programming, guiding and controlling the production line. 24. Production line according to claim 23, characterized in that the process control system (22) receives from a programming central computer system parameters depending on steel quality for thermo-mechanical rolling (14) according to the T.T.T. diagram (14.1), the hot rolled strip when leaving the finishing mill (18) has a temperature in a range AC3/AC1 (24) of said T.T.T. diagram (14.10 between 900 and 750�� C.
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이 특허에 인용된 특허 (4)
Kajiwara Toshiyuki (Katsushika-ku JPX) Yoshimura Yasutsugu (Hitachi JPX) Horii Kenji (Hitachi JPX) Seki Koichi (Hitachi JPX) Shimogama Hironori (Hitachi JPX) Nishino Tadashi (Hitachi JPX) Hanzawa Chu, Hot strip rolling plant and method directly combined with continuous casting.
Pleschiutschnigg Fritz-Peter,DEX, Method and apparatus for high-speed continuous casting plants with a strand thickness reduction during solidification.
Arvedi, Giovanni, Process and relative production line for the direct manufacture of finished pressed or deep drawn pieces from ultrathin hot rolled strip cast and rolled in-line.
Klein, Christoph; Bilgen, Christian; Klinkenberg, Christian; Pander, Michael; Neumann, Luc; Rosenthal, Dieter; Cecere, Cosimo Andreas, Method for producing a metal strip by casting and rolling.
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