CA2229255C - Long slab rolling process and apparatus - Google Patents
Long slab rolling process and apparatus Download PDFInfo
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- CA2229255C CA2229255C CA 2229255 CA2229255A CA2229255C CA 2229255 C CA2229255 C CA 2229255C CA 2229255 CA2229255 CA 2229255 CA 2229255 A CA2229255 A CA 2229255A CA 2229255 C CA2229255 C CA 2229255C
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- slab
- strip
- rolling
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- slab length
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
- B21B1/466—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a non-continuous process, i.e. the cast being cut before rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
- B21B1/24—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
- B21B1/26—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
Abstract
A long slab rolling process and apparatus for producing a plurality of coils from a single slab, comprises at least one continuous caster producing a cast metal slab, means to cut the slab into discrete lengths for rolling, a reheat furnace, a slab welder, an edger, rough and finish rolling mills to produce hot rolled metal strip, a runout cooling table to cool the hot rolled strip, a pair of pinch rolls and a pair of strip deflector tables to deflect the rolled strip downwardly from the rolling line and, in conjunction with a slowing of the speed of the second pinch roll, to form a loop of strip, a flying shear disposed downstream of the loop and adapted to cut the strip, a part of which is directed onto a first coiler and a remaining portion of which is directed onto a second coiler. In one embodiment of the invention, a second caster and cutter produces second cut slab lengths which are transferred to the reheating furnace after a slab length from the first caster has exited the furnace, and the head end of the second slab length is welded to the tail end of the first slab length.
Description
LONG SLAB ROLLING PROCESS AND APPARATUS
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to improved hot strip rolling mills and, more particularly, to such improved mills which have an ability to continuously produce a plurality of rolled coils from a single slab continuously cast from one or a number of heats of molten metal, e.g. steel.
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to improved hot strip rolling mills and, more particularly, to such improved mills which have an ability to continuously produce a plurality of rolled coils from a single slab continuously cast from one or a number of heats of molten metal, e.g. steel.
2. Description of the Prior Art Presently, in a hot strip rolling mill, each slab is sized to produce only one coil from that slab. This creates the following problems:
1. Because, during strip threading and tailing out, a portion of the strip is rolled without interstand strip tension, the quality of this part of the strip is inferior to the quality of the remaining part of the strip that is rolled with a controlled interstand strip tension.
2. A probability of strip cobbling during threading and tail out also increases.
1. Because, during strip threading and tailing out, a portion of the strip is rolled without interstand strip tension, the quality of this part of the strip is inferior to the quality of the remaining part of the strip that is rolled with a controlled interstand strip tension.
2. A probability of strip cobbling during threading and tail out also increases.
3. When rolling thin gage strip, e.g. 2 mm thick and thinner, the threading speed must be reduced to avoid air-lifting of the strip after it exits the mill.
4. It is necessary to cut the head and tail ends of each transfer bar, thus increasing yield losses.
5. A long length of reheat tunnel furnaces is required.
A typical present mill arrangement comprises a continuous caster coupled to a rolling line comprising a shear to cut the continuously cast slab into lengths to produce a single coil, a f first tunnel reheat furnace, an edger, one or more roughing stands, a second tunnel reheat furnace, a flying shear, finish rolling stands, a runout cooling table, and one or more coilers.
More recently, a continuous or endless hot rolling system has been developed. "Outline of Newly Built Chiba No. 3 Hot Strip Mill," Kawasaki Steel Technical Report No. 34, March 1996; "Endless Rolling Begins in Japan," New Steel, May 1996, pages 54-55;
"Endless Hot Strip Rolling at Kawasaki Steel Chiba Works, " Iron and Steel Engineer, February 1997, pages 41-47. In this process, slabs are reheated and rough rolled to sheet bars which, after holding in a coil box, then are joined head-to-tail by induction heating, finish rolled, cooled, sheared and coiled. Accordingly, every transfer bar, each corresponding to one coil, must be welded or otherwise joined. Moreover, the high speed at which down coiling is effected provides an inherently unreliable process.
SUMMARY OF THE INVENTION
In accordance with the present invention, the prior art mill arrangement is modified to increase the length of the first tunnel reheat furnace so as to accommodate all the slabs that can be produced from one heat of molten metal, and a movable welding machine for welding successive slabs together is introduced into the mill line after the first tunnel reheat furnace. The second tunnel reheat furnace is eliminated and a pair of pinch rolls and a pair of deflecting roller tables are installed after the runout cooling table, and a second flying shear is installed after the second pinch roll. By means of such modification, continuous (uninterrupted) rolling can be performed with the production of a plurality of coils from a single slab or from a plurality of slabs from a single heat or a plurality of heats and with a minimum requirement for welding or otherwise joining successive coils. By forming a loop of finish rolled strip by means of the deflecting roller tables, cutting and coiling the finished coils can be done at lower speed, thus minimizing or eliminating the disadvantages of high speed cutting and coiling.
Therefore this invention seeks to provide a long slab rolling process compx:~ising: (a) in a first continuous ~~aster, continuously casting a first heat of molten metal; (b) forming the cast metal of the entire first heat into one or more first slab length(s); (c) re:heating, in a first repeating zone which is at least as long a.s said first slab length, each first slab 7.0 length unti7_ a desired rolling temperature is attained along the entire ~~lab length; then, (d) rolling each first slab length into a strip; (~_) cutting the strip rolled from each first slab Length into a plurality of desired coil lengths; and (f) forming each coil. length of strip into a coil; said rolling 7.5 of each first slab length being carried out at a substantially constant rolling speed without interruption for said cutting and forming into a coil.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a ;ketch, in side elevation, of a a;0 continuous casting/rol:ling mill arrangement or the prior art, and Fi.g. 2 is a similar sketch of a modified continuous casting/roll.ing mill arrangement in accordance with the present invention.
~5 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Fi.g. 1 shows a typical present continuous casting/roll.ing mill a=r:rangement. In that arrangement, slab is continuously cast with one or two continuous casters 1 and 13, e.g. in a thickness range of from about 50 to about 100 mm.
30 Typical reductions in t=hickness are shown in Table 1.
Table 1 Typical Mill. Reductions Schedule and Speeds Slab Mill Train Thickness Slab Thickness After Rolling Pass,mm Speed,m/min mm 1 2 3 - 5 6 7 8 Enter Exit _-- 4 90 52 25 10..65.38 3.04 2.03 1.46 1.2 10 740 ._0 90 5-'-27 12..87.1 4.37 3.12 2.4 2.0 14.6 650 90 55 30 17.0 10.6 7.6 6.22 5.35 5.0 25.8 460 90 5~132 22.0 16.0 12.9 11.5 10.5 10.0 26.9 240 The continuously cast slab then is cut, by shear 2 7_5 (which can be either a crank-type shear or a torch cutter) into lengths to produce one coil from a cut slab. For example, to produce a coil of 1000 mm wide with a specific weight of 20 kg/mm from a 100 mm thick slab, the slab length will be approximate7.y 26 meters. The cut slab then is introduced into the first tunnel repeat furnace 3 where its temperaturE= is raised to about 1100-1:200°C. The length of the first repeat tunnel furnace L1 is determined by a required buffer tame, i.e.
a time during which the casting process can continue while the rolling mill. is not op~=rating. The length L1 usually is 25 selected to accommodatE=_ three or four cut slabs.
After reheat:ing in furnace 3, the slab enters edge 4.
Then, after rolling by the first roughing stand 5 and t=he second roughing stand 6, the slab is reduced in thickness to about 20-50 mm. The thus-obtained long transfer bar then ?0 enters the second repeat furnace 7 where its temperature is raised to about 1050-1:L00°C. The length L2 of the furnace 7 is selected to accommodate the longest transfer bar. For example, for a coil with a specific weight of 20 kg/mm, the length of the 20 mm thick transfer bar would be approximately 130 meters.
After shearing with t:h~? flying shear 8, the transfer b<~r is treaded through the f:i:nishing train 9 where it is reduced in thickness to about 1.0 tc> 12 mm.
When rollir~.g thin gauges, the threading speed of the last stand does not exceed about 10-11 meters/sec in order to prevent air-horning of the strip exiting this stand.
After the he<~d end of the strip is directed t=o and engaged on the coi.ler :L1 or 12 by any suitable known strip guiding means such as a belt wrapper as disclosed in U.S.
Patent No. 3,315,510 o=r a slotted coiler drum as disclosed in U.S. Patent No. 3,122,337. Thereafter strip tension i;~
established between the finishing mill and the coiler, the rolling line can be accelerated to either control the strip temperature or to increase the production rate, or to do both.
After rolling and before coiling, the strip is water cooled by the runout table cooling system 10.
4a If the second caster is used, the second cast slab is cut with a shearing machine 14 into the slab lengths from which only one coil is rolled. Each cut slab then is reheated in the tunnel furnace 15 and transferred to the rolling line by a transfer ferry 16.
To achieve the main objective of the invention--provision for continuous rolling as long as it is practically needed--the following principal modifications were made to the prior art arrangement as above-described:
1. A first tunnel furnace 17 is extended so that its length L3 is sufficient to accommodate all the slabs that can be produced by using one heat size. For example, if the heat weight is 160 tons and coil weight is 20 tons, then the first tunnel reheat furnace must have a capacity sufficient to accommodate the slabs for eight coils.
For coils with a specific weight of 20 kg/mm, the length L3 will be approximately 210 meters.
2. The second tunnel furnace 7 (Fig. 1) is completely eliminated, and the distance L4 between the roughing mills 5 and 6 and the finishing mill 9 is reduced to about 12-15 meters.
3. A movable welding machine 18 is installed at the end of the first tunnel reheat furnace 17.
4. Two pinch roll machines 19, 21 are installed after the runout table cooling system 10.
5. Two deflecting roller tables 22, 23 are installed between the pinch roll machines 19 and 21.
A typical present mill arrangement comprises a continuous caster coupled to a rolling line comprising a shear to cut the continuously cast slab into lengths to produce a single coil, a f first tunnel reheat furnace, an edger, one or more roughing stands, a second tunnel reheat furnace, a flying shear, finish rolling stands, a runout cooling table, and one or more coilers.
More recently, a continuous or endless hot rolling system has been developed. "Outline of Newly Built Chiba No. 3 Hot Strip Mill," Kawasaki Steel Technical Report No. 34, March 1996; "Endless Rolling Begins in Japan," New Steel, May 1996, pages 54-55;
"Endless Hot Strip Rolling at Kawasaki Steel Chiba Works, " Iron and Steel Engineer, February 1997, pages 41-47. In this process, slabs are reheated and rough rolled to sheet bars which, after holding in a coil box, then are joined head-to-tail by induction heating, finish rolled, cooled, sheared and coiled. Accordingly, every transfer bar, each corresponding to one coil, must be welded or otherwise joined. Moreover, the high speed at which down coiling is effected provides an inherently unreliable process.
SUMMARY OF THE INVENTION
In accordance with the present invention, the prior art mill arrangement is modified to increase the length of the first tunnel reheat furnace so as to accommodate all the slabs that can be produced from one heat of molten metal, and a movable welding machine for welding successive slabs together is introduced into the mill line after the first tunnel reheat furnace. The second tunnel reheat furnace is eliminated and a pair of pinch rolls and a pair of deflecting roller tables are installed after the runout cooling table, and a second flying shear is installed after the second pinch roll. By means of such modification, continuous (uninterrupted) rolling can be performed with the production of a plurality of coils from a single slab or from a plurality of slabs from a single heat or a plurality of heats and with a minimum requirement for welding or otherwise joining successive coils. By forming a loop of finish rolled strip by means of the deflecting roller tables, cutting and coiling the finished coils can be done at lower speed, thus minimizing or eliminating the disadvantages of high speed cutting and coiling.
Therefore this invention seeks to provide a long slab rolling process compx:~ising: (a) in a first continuous ~~aster, continuously casting a first heat of molten metal; (b) forming the cast metal of the entire first heat into one or more first slab length(s); (c) re:heating, in a first repeating zone which is at least as long a.s said first slab length, each first slab 7.0 length unti7_ a desired rolling temperature is attained along the entire ~~lab length; then, (d) rolling each first slab length into a strip; (~_) cutting the strip rolled from each first slab Length into a plurality of desired coil lengths; and (f) forming each coil. length of strip into a coil; said rolling 7.5 of each first slab length being carried out at a substantially constant rolling speed without interruption for said cutting and forming into a coil.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a ;ketch, in side elevation, of a a;0 continuous casting/rol:ling mill arrangement or the prior art, and Fi.g. 2 is a similar sketch of a modified continuous casting/roll.ing mill arrangement in accordance with the present invention.
~5 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Fi.g. 1 shows a typical present continuous casting/roll.ing mill a=r:rangement. In that arrangement, slab is continuously cast with one or two continuous casters 1 and 13, e.g. in a thickness range of from about 50 to about 100 mm.
30 Typical reductions in t=hickness are shown in Table 1.
Table 1 Typical Mill. Reductions Schedule and Speeds Slab Mill Train Thickness Slab Thickness After Rolling Pass,mm Speed,m/min mm 1 2 3 - 5 6 7 8 Enter Exit _-- 4 90 52 25 10..65.38 3.04 2.03 1.46 1.2 10 740 ._0 90 5-'-27 12..87.1 4.37 3.12 2.4 2.0 14.6 650 90 55 30 17.0 10.6 7.6 6.22 5.35 5.0 25.8 460 90 5~132 22.0 16.0 12.9 11.5 10.5 10.0 26.9 240 The continuously cast slab then is cut, by shear 2 7_5 (which can be either a crank-type shear or a torch cutter) into lengths to produce one coil from a cut slab. For example, to produce a coil of 1000 mm wide with a specific weight of 20 kg/mm from a 100 mm thick slab, the slab length will be approximate7.y 26 meters. The cut slab then is introduced into the first tunnel repeat furnace 3 where its temperaturE= is raised to about 1100-1:200°C. The length of the first repeat tunnel furnace L1 is determined by a required buffer tame, i.e.
a time during which the casting process can continue while the rolling mill. is not op~=rating. The length L1 usually is 25 selected to accommodatE=_ three or four cut slabs.
After reheat:ing in furnace 3, the slab enters edge 4.
Then, after rolling by the first roughing stand 5 and t=he second roughing stand 6, the slab is reduced in thickness to about 20-50 mm. The thus-obtained long transfer bar then ?0 enters the second repeat furnace 7 where its temperature is raised to about 1050-1:L00°C. The length L2 of the furnace 7 is selected to accommodate the longest transfer bar. For example, for a coil with a specific weight of 20 kg/mm, the length of the 20 mm thick transfer bar would be approximately 130 meters.
After shearing with t:h~? flying shear 8, the transfer b<~r is treaded through the f:i:nishing train 9 where it is reduced in thickness to about 1.0 tc> 12 mm.
When rollir~.g thin gauges, the threading speed of the last stand does not exceed about 10-11 meters/sec in order to prevent air-horning of the strip exiting this stand.
After the he<~d end of the strip is directed t=o and engaged on the coi.ler :L1 or 12 by any suitable known strip guiding means such as a belt wrapper as disclosed in U.S.
Patent No. 3,315,510 o=r a slotted coiler drum as disclosed in U.S. Patent No. 3,122,337. Thereafter strip tension i;~
established between the finishing mill and the coiler, the rolling line can be accelerated to either control the strip temperature or to increase the production rate, or to do both.
After rolling and before coiling, the strip is water cooled by the runout table cooling system 10.
4a If the second caster is used, the second cast slab is cut with a shearing machine 14 into the slab lengths from which only one coil is rolled. Each cut slab then is reheated in the tunnel furnace 15 and transferred to the rolling line by a transfer ferry 16.
To achieve the main objective of the invention--provision for continuous rolling as long as it is practically needed--the following principal modifications were made to the prior art arrangement as above-described:
1. A first tunnel furnace 17 is extended so that its length L3 is sufficient to accommodate all the slabs that can be produced by using one heat size. For example, if the heat weight is 160 tons and coil weight is 20 tons, then the first tunnel reheat furnace must have a capacity sufficient to accommodate the slabs for eight coils.
For coils with a specific weight of 20 kg/mm, the length L3 will be approximately 210 meters.
2. The second tunnel furnace 7 (Fig. 1) is completely eliminated, and the distance L4 between the roughing mills 5 and 6 and the finishing mill 9 is reduced to about 12-15 meters.
3. A movable welding machine 18 is installed at the end of the first tunnel reheat furnace 17.
4. Two pinch roll machines 19, 21 are installed after the runout table cooling system 10.
5. Two deflecting roller tables 22, 23 are installed between the pinch roll machines 19 and 21.
6. A second flying shear 24 is installed after the second pinch roll machine 21.
7. In the second caster line, the reheat furnace 15 and the short transfer ferry 16 (Fig. 1) are replaced with a long transfer ferry 20 that also serves as a reheat furnace and can accommodate the entire slab length corresponding to one heat size.
In operation, the process and apparatus of the invention can function in any one of three different modes.
In a ffirst mode, the invention can operate in accordance with the above-described and illustrated conventional casting by cutting the slab into lengths and rolling only one coil per cut slab length.
In a second mode, the invention operates as a continuous casting and rolling process in which cast slabs are cut into lengths to roll more than one coil per cut slab length and up to an entire heat size. Since casting speed is in the range or about 3 to 4.5 m/min, that is, slower than the entry speed of the rolling mill which is within the range of about 10 to 30 m/min (see Table 1), the casting cycle for one caster will be longer than the rolling cycle. After casting and cutting a required slab length (if the entire heat is not used), the slab is preheated in the tunnel furnace 17 and subsequently is rolled by the edger 4 and the horizontal mill stands 5, 6 and 9. The flying shear 8 generally will be used for shearing the head and tail ends of the bar rolled from each cut slab. At the beginning of rolling of each coil, both pinch roll machines 19 and 21 are disengaged from the strip and the deflecting tables 22 and 23 are maintained in a horizontal position, i.e. in line with the runout table 10. After arrival of the head end of the coil, the pinch roll machines are engaged with the strip and the deflecting roller tables 22 and 23 are lowered, 3o as illustrated in Fig. 2. The speeds of both the pinch roll machine 21 and coiler 11 or 12 (whichever is used at that time in the coiling process) are slowed to the speed optimum for shearing (approximately 1 to 5 m/min) . As a result of the difference in speed of the pinch roll machines 19 and 21, a temporary loop 26 (Fig. 2) is formed between those machines. At a predetermined time, the flying shear 24 will make a cut of the strip. Then the head end of the remaining portion of the strip is guided toward the previously unused coiler. As soon as a new portion of the strip enters the latter coiler, and the strip tension between the pinch roll machine 21 and that coiler is established, the speeds of both the pinch roll machine 21 and the newly used coiler is increased to mill exit speed. After the strip loop 26 is eliminated, the deflecting tables 22 and 23 are again raised to the mill pass lie and the pinch roll machines are disengaged from the strip.
A third mode of operation comprises operating the inventive process and apparatus by continuous casting in two casters and rolling the slab length corresponding to more than one heat. In this operative embodiment, the second caster 13 casts a slab, with cutting, if necessary, by the cutting machine 14. After a slab, produced by the first caster 1, leaves the reheat tunnel furnace 17, the cut slab length, produced by the second caster 13, is transf erred by the transfer ferry 2 0 to the rol l ing mi 11 1 ine .
This portion of the slab then is accelerated so that its head end gets in touch with the tail end of the slab, produced by the first caster 1, that is being rolled. After establishing such contact of the ends of the respective slabs, the speeds of both slabs are synchronized with each other. At the same time, the welding machine 18 starts moving along the mill line with the same speed as the slabs and performs a stick welding operation. After the welding procedure is completed, the welding machine returns to its initial position. Thereafter the operation can continue as in the second mode of operation to produce a plurality of coils of rolled metal strip.
Practice of the invention provides a means for producing multiple coils from longer slabs than possible with use of the prior art. It consequently reduces the number of times threading of the mill has to be done, thereby reducing yield losses in the form of scrapped lower quality strip rolled without interstand strip tension, reducing the risk of strip cobbling and reducing productivity losses due to the need to slow down the strip to avoid air-lifting during threading. The invention also reduces yield losses incident to the necessity of cutting out lower quality transfer bar head and tail portions.
In operation, the process and apparatus of the invention can function in any one of three different modes.
In a ffirst mode, the invention can operate in accordance with the above-described and illustrated conventional casting by cutting the slab into lengths and rolling only one coil per cut slab length.
In a second mode, the invention operates as a continuous casting and rolling process in which cast slabs are cut into lengths to roll more than one coil per cut slab length and up to an entire heat size. Since casting speed is in the range or about 3 to 4.5 m/min, that is, slower than the entry speed of the rolling mill which is within the range of about 10 to 30 m/min (see Table 1), the casting cycle for one caster will be longer than the rolling cycle. After casting and cutting a required slab length (if the entire heat is not used), the slab is preheated in the tunnel furnace 17 and subsequently is rolled by the edger 4 and the horizontal mill stands 5, 6 and 9. The flying shear 8 generally will be used for shearing the head and tail ends of the bar rolled from each cut slab. At the beginning of rolling of each coil, both pinch roll machines 19 and 21 are disengaged from the strip and the deflecting tables 22 and 23 are maintained in a horizontal position, i.e. in line with the runout table 10. After arrival of the head end of the coil, the pinch roll machines are engaged with the strip and the deflecting roller tables 22 and 23 are lowered, 3o as illustrated in Fig. 2. The speeds of both the pinch roll machine 21 and coiler 11 or 12 (whichever is used at that time in the coiling process) are slowed to the speed optimum for shearing (approximately 1 to 5 m/min) . As a result of the difference in speed of the pinch roll machines 19 and 21, a temporary loop 26 (Fig. 2) is formed between those machines. At a predetermined time, the flying shear 24 will make a cut of the strip. Then the head end of the remaining portion of the strip is guided toward the previously unused coiler. As soon as a new portion of the strip enters the latter coiler, and the strip tension between the pinch roll machine 21 and that coiler is established, the speeds of both the pinch roll machine 21 and the newly used coiler is increased to mill exit speed. After the strip loop 26 is eliminated, the deflecting tables 22 and 23 are again raised to the mill pass lie and the pinch roll machines are disengaged from the strip.
A third mode of operation comprises operating the inventive process and apparatus by continuous casting in two casters and rolling the slab length corresponding to more than one heat. In this operative embodiment, the second caster 13 casts a slab, with cutting, if necessary, by the cutting machine 14. After a slab, produced by the first caster 1, leaves the reheat tunnel furnace 17, the cut slab length, produced by the second caster 13, is transf erred by the transfer ferry 2 0 to the rol l ing mi 11 1 ine .
This portion of the slab then is accelerated so that its head end gets in touch with the tail end of the slab, produced by the first caster 1, that is being rolled. After establishing such contact of the ends of the respective slabs, the speeds of both slabs are synchronized with each other. At the same time, the welding machine 18 starts moving along the mill line with the same speed as the slabs and performs a stick welding operation. After the welding procedure is completed, the welding machine returns to its initial position. Thereafter the operation can continue as in the second mode of operation to produce a plurality of coils of rolled metal strip.
Practice of the invention provides a means for producing multiple coils from longer slabs than possible with use of the prior art. It consequently reduces the number of times threading of the mill has to be done, thereby reducing yield losses in the form of scrapped lower quality strip rolled without interstand strip tension, reducing the risk of strip cobbling and reducing productivity losses due to the need to slow down the strip to avoid air-lifting during threading. The invention also reduces yield losses incident to the necessity of cutting out lower quality transfer bar head and tail portions.
Claims (16)
1. A long slab rolling process comprising:
(a) in a first continuous caster, continuously casting a first heat of molten metal;
(b) forming the cast metal of the entire first heat into one or more first slab length(s);
(c) reheating, in a first repeating zone which is at least as long as said first slab length, each first slab length until a desired rolling temperature is attained along the entire slab length; then, (d) rolling each first slab length into a strip;
(e) cutting the strip rolled from each first slab length into a plurality of desired coil lengths; and (f) forming each coil length of strip into a coil;
said rolling of each first slab length being carried out at a substantially constant rolling speed without interruption for said cutting and forming into a coil.
(a) in a first continuous caster, continuously casting a first heat of molten metal;
(b) forming the cast metal of the entire first heat into one or more first slab length(s);
(c) reheating, in a first repeating zone which is at least as long as said first slab length, each first slab length until a desired rolling temperature is attained along the entire slab length; then, (d) rolling each first slab length into a strip;
(e) cutting the strip rolled from each first slab length into a plurality of desired coil lengths; and (f) forming each coil length of strip into a coil;
said rolling of each first slab length being carried out at a substantially constant rolling speed without interruption for said cutting and forming into a coil.
2. A process according to claim 1, wherein the rolling step comprises:
(a) edge rolling each of the repeated first slab lengths;
(b) rough rolling each of the first slab lengths into a transfer bar, and (c) finish rolling the transfer bar into strip of a desired final thickness.
(a) edge rolling each of the repeated first slab lengths;
(b) rough rolling each of the first slab lengths into a transfer bar, and (c) finish rolling the transfer bar into strip of a desired final thickness.
3. A process according to claim 2, further comprising cooling the finish rolled strip.
4. A process according to claim 3, comprising directing a first portion of the finish rolled strip onto a first coiler to form a first coil of strip and a second portion of the strip onto a second coiler to form a second coil of strip.
5. A process according to claim 4, wherein the strip cutting step comprises:
(a) passing the uncut strip through a pair of spaced-apart pinch roll machines disposed in a rolling line;
(b) slowing the speed of a downstream pinch roll machine and, with use of a pair of deflecting tables, downwardly deflecting the strip out of the rolling line, thereby forming a temporary loop in the uncut strip;
(c) with use of a flying shear, cutting the strip downstream from the loop to form a tail end of the first coil, and (d) directing a head end of a remaining portion of the strip onto a second coiler to form a second coil of strip from the same slab length.
(a) passing the uncut strip through a pair of spaced-apart pinch roll machines disposed in a rolling line;
(b) slowing the speed of a downstream pinch roll machine and, with use of a pair of deflecting tables, downwardly deflecting the strip out of the rolling line, thereby forming a temporary loop in the uncut strip;
(c) with use of a flying shear, cutting the strip downstream from the loop to form a tail end of the first coil, and (d) directing a head end of a remaining portion of the strip onto a second coiler to form a second coil of strip from the same slab length.
6. A process according to claim 5, further comprising:
(a) in a second continuous caster, continuously casting a second heat of molten metal;
(b) forming the cast metal from the second heat into the form of cut second slab lengths;
(c) after a first slab length has been repeated, transferring a second slab length into the repeating zone and repeating its therein, and (d) moving a head end of the repeated second slab length into contact with a tail end of the first slab length and welding it thereto.
(a) in a second continuous caster, continuously casting a second heat of molten metal;
(b) forming the cast metal from the second heat into the form of cut second slab lengths;
(c) after a first slab length has been repeated, transferring a second slab length into the repeating zone and repeating its therein, and (d) moving a head end of the repeated second slab length into contact with a tail end of the first slab length and welding it thereto.
7. A long slab rolling system comprising:
(a) a first continuous caster to continuously cast a first heat of molten metal into slab form;
(b) means to cut the cast slab into one or more first slab length(s);
(c) a reheating furnace to repeat each of the one or more first slab length(s) simultaneously along its entire length;
(d) means in a rolling line to roll each first slab length into strip;
(e) means to cut the strip rolled from each first slab length into a plurality of desired coil lengths; and (f) means to form each coil length of strip into a coil;
said cutting means and said means to form a coil being adapted to allow said rolling of each first slab length to be carried out at a substantially constant speed.
(a) a first continuous caster to continuously cast a first heat of molten metal into slab form;
(b) means to cut the cast slab into one or more first slab length(s);
(c) a reheating furnace to repeat each of the one or more first slab length(s) simultaneously along its entire length;
(d) means in a rolling line to roll each first slab length into strip;
(e) means to cut the strip rolled from each first slab length into a plurality of desired coil lengths; and (f) means to form each coil length of strip into a coil;
said cutting means and said means to form a coil being adapted to allow said rolling of each first slab length to be carried out at a substantially constant speed.
8. A system according to claim 7, further comprising:
(a) welding means disposed in the rolling line adjacent and downstream of the repeating furnace;
(b) edge rolling means disposed adjacent and downstream of the welding means to edge roll each of the reheated slab length;
(c) at least one rough rolling mill disposed in the rolling line downstream of the edge rolling means to rough roll each of the slab lengths into a transfer bar, and (d) at least one finish rolling mill disposed in the rolling line downstream of the rough rolling mill to finish roll the transfer bar into strip of a desired final thickness.
(a) welding means disposed in the rolling line adjacent and downstream of the repeating furnace;
(b) edge rolling means disposed adjacent and downstream of the welding means to edge roll each of the reheated slab length;
(c) at least one rough rolling mill disposed in the rolling line downstream of the edge rolling means to rough roll each of the slab lengths into a transfer bar, and (d) at least one finish rolling mill disposed in the rolling line downstream of the rough rolling mill to finish roll the transfer bar into strip of a desired final thickness.
9. A system according to claim 8, further comprising means disposed downstream of the finishing mill to cool the finish rolled strip.
10. A system according to claim 9, further comprising first and second coilers, and means to direct a first portion of the finish rolled strip onto the first coiler to form a first coil of strip and a second portion of the strip onto the second coiler to form a second coil of strip.
11. A system according to claim 10, further comprising:
(a) a pair of spaced-apart pinch roll machines disposed in the rolling line downstream of the finish rolling mill;
(b) a pair of deflecting tables disposed in the rolling line between the pinch roll machines and adapted to downwardly deflect the strip out of the rolling line and, in conjunction with a slowing of the speed of a downstream pinch roll machine, thereby to form a temporary loop in the uncut strip, and
(a) a pair of spaced-apart pinch roll machines disposed in the rolling line downstream of the finish rolling mill;
(b) a pair of deflecting tables disposed in the rolling line between the pinch roll machines and adapted to downwardly deflect the strip out of the rolling line and, in conjunction with a slowing of the speed of a downstream pinch roll machine, thereby to form a temporary loop in the uncut strip, and
12 (c) a flying shear disposed in the rolling line downstream from the loop and adapted to cut the strip into separate lengths for coiling.
12. A system according to claim 11, further comprising a second continuous caster for producing second cut slab lengths, a transfer ferry for transferring a second cut slab length to the repeating furnace after a first cut slab length has exited the repeating furnace.
12. A system according to claim 11, further comprising a second continuous caster for producing second cut slab lengths, a transfer ferry for transferring a second cut slab length to the repeating furnace after a first cut slab length has exited the repeating furnace.
13. A system according to claim 11, wherein the tunnel repeat furnace has a length sufficient to accommodate all the cut slab lengths that can be continuously cast from one heat of molten metal.
14. A system according to claim 12, wherein the transfer ferry also serves as a repeat furnace and has a length sufficient to accommodate all the cut slab lengths that can be continuously cast by the second caster from one heat of molten metal.
15. A process according to claim 1, further comprising:
(g) forming the cast metal of the entire first heat into one first slab length;
(h) in a second continuous caster, continuously casting a second heat of molten metal;
(i) forming the cast metal from the entire second heat into one second slab length;
repeating said second slab length in a second repeating zone which is at least as long as said second slab length until a desired rolling temperature is attained along the entire slab length; then (k) after the first slab length has been repeated and removed from the first repeating zone, transferring the second slab length in-line with such first slab length;
(l) moving a head end of such second slab length into contact with a tail end of such first slab length and welding it thereto;
(m) rolling such second slab length into a strip;
(n) cutting the strip rolled from the second slab length into a plurality of desired coil lengths; and (o) forming each. coil length of strip into a coil.
(g) forming the cast metal of the entire first heat into one first slab length;
(h) in a second continuous caster, continuously casting a second heat of molten metal;
(i) forming the cast metal from the entire second heat into one second slab length;
repeating said second slab length in a second repeating zone which is at least as long as said second slab length until a desired rolling temperature is attained along the entire slab length; then (k) after the first slab length has been repeated and removed from the first repeating zone, transferring the second slab length in-line with such first slab length;
(l) moving a head end of such second slab length into contact with a tail end of such first slab length and welding it thereto;
(m) rolling such second slab length into a strip;
(n) cutting the strip rolled from the second slab length into a plurality of desired coil lengths; and (o) forming each. coil length of strip into a coil.
16. A process according to claim 1, wherein the cast metal of the entire first heat is formed into one first slab length.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US84369497A | 1997-04-16 | 1997-04-16 | |
| US08/843,694 | 1997-04-16 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2229255A1 CA2229255A1 (en) | 1998-10-16 |
| CA2229255C true CA2229255C (en) | 2002-01-08 |
Family
ID=25290753
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2229255 Expired - Fee Related CA2229255C (en) | 1997-04-16 | 1998-02-12 | Long slab rolling process and apparatus |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0872288A3 (en) |
| CA (1) | CA2229255C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107088585A (en) * | 2017-06-09 | 2017-08-25 | 首钢京唐钢铁联合有限责任公司 | A kind of milling method of strip |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6289972B1 (en) * | 1999-05-21 | 2001-09-18 | Danieli Technology Inc. | Integrated plant for the production of rolled stock |
| KR101365044B1 (en) | 2013-01-31 | 2014-02-25 | 주식회사 갑우 | Annealing apparatus for ribbon of photovoltaic module |
| CN112068491B (en) * | 2020-09-02 | 2021-09-21 | 四川省达州钢铁集团有限责任公司 | Method for improving response speed of flying shear |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS589719A (en) * | 1981-07-08 | 1983-01-20 | Toshiba Corp | Necking preventing method in winding in hot strip mill facility |
| JPS5816707A (en) * | 1981-07-23 | 1983-01-31 | Sumitomo Metal Ind Ltd | Production of steel strip |
| JPS5850104A (en) * | 1982-05-10 | 1983-03-24 | Nippon Steel Corp | Hot rolling installation train for steel material |
| US5121873A (en) * | 1990-06-06 | 1992-06-16 | Hitachi Ltd. | Method of and apparatus for joining hot materials to be rolled to each other as well as continuous hot rolling method and system |
| JPH06106222A (en) * | 1992-09-28 | 1994-04-19 | Nkk Corp | Hot run table roll having elevating mechanism |
| JPH0788507A (en) * | 1993-09-24 | 1995-04-04 | Toshiba Corp | Continuous rolling device for hot steel strip |
| IT1267916B1 (en) * | 1994-03-31 | 1997-02-18 | Danieli Off Mecc | PROCEDURE FOR THE PRODUCTION OF BELT STARTING FROM THIN SLABS AND RELATIVE PLANT |
| CN1070393C (en) * | 1995-03-03 | 2001-09-05 | 株式会社东芝 | Hot-rolling method and arrangement |
| NL1003293C2 (en) * | 1996-06-07 | 1997-12-10 | Hoogovens Staal Bv | Method and device for manufacturing a steel strip. |
-
1998
- 1998-02-12 EP EP98102462A patent/EP0872288A3/en not_active Withdrawn
- 1998-02-12 CA CA 2229255 patent/CA2229255C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107088585A (en) * | 2017-06-09 | 2017-08-25 | 首钢京唐钢铁联合有限责任公司 | A kind of milling method of strip |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0872288A3 (en) | 1999-04-07 |
| EP0872288A2 (en) | 1998-10-21 |
| CA2229255A1 (en) | 1998-10-16 |
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