A plate production line and a production method

Abstract

The present application relates to the technical field of medium plate production, and particularly relates to a medium plate production line and a production method. The production line comprises a heating furnace, a descaling machine, a heat preservation cover, a rough rolling mill, a first sectional shear and a finishing rolling mill arranged in sequence along a rolling direction; the first sectional shear is used for dividing the rough-rolled intermediate blank into a first intermediate blank section and a second intermediate blank section; the first intermediate blank section enters the finishing rolling mill for rolling, and the second intermediate blank section returns to the heat preservation cover for heat preservation and then enters the finishing rolling mill for rolling; wherein the first intermediate blank section or the second intermediate blank section can continuously complete twice thinning when passing through two finishing rolling mills of the finishing rolling mill each pass. Thus, under the condition that the width of the cooling bed is limited, the efficient production of thin-gauge medium plates is realized by using long blanks, and the problems of low metal yield, large temperature drop caused by many finishing rolling passes, and limited production capacity caused by the non-parallel rough rolling and finishing rolling of the conventional production line are solved.

Description

Technical Field

[0001] This invention relates to the field of medium and heavy plate production technology, specifically to a medium and heavy plate production line and production method. Background Technology

[0002] Medium and heavy plates are important steel materials, widely used in shipbuilding, building structures, and engineering machinery. Currently, medium and heavy plate production lines mainly include heating furnaces, high-pressure water descaling devices, one or two medium and heavy plate rolling mills, cooling devices, hot straighteners, cooling beds, and shearing lines. In these conventional medium and heavy plate production lines, the width of the cooling bed is one of the key factors limiting capacity and yield. Because the steel plates require a long time to cool on the cooling bed, multiple plates need to be stored simultaneously, resulting in a large cooling bed area. When the length of the rolled steel plate exceeds the width of the cooling bed, a segmenting shear must be installed before the cooling bed to cut the steel plate into sections before it can be loaded onto the cooling bed. Therefore, the actual maximum length of rolled steel plates usually does not exceed twice the width of the cooling bed.

[0003] The limitation of cooling bed width has a significant impact on the production of thin-gauge products in medium and heavy plates. Taking the production of thin-gauge products with a thickness of 6-8mm as an example, the thickness of the raw slab is usually around 200mm. When the length of the rolled steel plate is 60m, the required length of the raw slab is only about 2.1m. Furthermore, because each raw slab undergoes multiple rolling passes on the mill, the head and tail of the steel plate experience significant temperature drops due to edge effects, resulting in lower temperatures than the middle of the plate and unstable rolling. This leads to the head and tail sections failing to meet product quality requirements, necessitating head and tail trimming on the shearing line. Therefore, for raw slabs with a length of only about 2.1m, the head and tail trimming losses account for a large proportion of the overall loss, resulting in a metal yield of only about 92% for medium and heavy plate production lines, significantly lower than the level of hot continuous rolling production lines. Furthermore, the production of thin-gauge products also presents challenges such as numerous rolling passes and rapid temperature drop. On one or two medium-thick plate mills, the number of rolling passes required to roll a single slab into a finished product typically exceeds 10, resulting in a long total rolling time and a continuous drop in steel plate temperature. When the temperature approaches or falls below 800℃, the steel's deformation resistance increases significantly, and process parameters such as rolling force approach the equipment's limits. In summary, conventional medium-thick plate production lines struggle to meet the requirements of hot rolling processes when producing thin-gauge products, leading to lower production efficiency and yield. Summary of the Invention

[0004] This invention addresses the problem of producing thin-gauge products using long billets in medium-thick plate production lines under conditions of limited cooling bed width, thereby shortening finishing rolling time, controlling rolling temperature drop, and improving metal yield.

[0005] To address the above problems, this invention provides a medium-thick plate production line and production method.

[0006] On one hand, the present invention provides a medium and heavy plate production line, including a heating furnace, a descaling machine, a heat insulation cover, a roughing mill, a first segment shear and a finishing mill arranged sequentially along the production line direction; The heating furnace is used to heat slabs; The descaling machine is used to descale the heated slab. The roughing mill is used to rough roll the descaled slab into an intermediate slab; The first segment shear is used to segment the intermediate billet into a first intermediate billet segment and a second intermediate billet segment along the rolling direction; wherein, when the first intermediate billet segment enters the finishing mill for finishing rolling, the second intermediate billet segment returns to the heat insulation cover for heat insulation; when the first intermediate billet segment performs the last pass of finishing rolling, the second intermediate billet segment enters the finishing mill from the heat insulation cover for finishing rolling. The heat insulation cover is located at the entrance of the roughing mill; The finishing mill unit includes two finishing mills, which are arranged adjacent to each other along the production line direction, and are used to perform two consecutive thinning operations on the first intermediate billet section or the second intermediate billet section passing through the two finishing mills in each pass.

[0007] Preferably, the rolling direction of the roughing mill is the same as that of the finishing mill, and the distance between the roughing mill and the finishing mill is greater than the maximum length of the steel plate rolled by the finishing mill.

[0008] Preferably, the system further includes a first steel-transfer device, which is located between the heating furnace and the descaling machine, and is used to transfer the slab to steel during the process of the slab being transported from the heating furnace to the descaling machine.

[0009] Preferably, the system further includes a vertical roll mill, which is located between the roughing mill and the first segment shear, and is used to adjust the width of the intermediate billet.

[0010] Preferably, the device further includes a second steel transfer device for transferring the intermediate billet, the second steel transfer device being located between the roughing mill and the insulation cover and / or between the roughing mill and the vertical roll mill.

[0011] Preferably, the assembly further includes a cooling device, a hot straightener, a second slitting shear, and a cooling bed, which are sequentially arranged along the production line direction after the finishing mill. The cooling device is used to cool the finished steel plate, the hot straightener is used to straighten the cooled steel plate, the second slitting shear is used to segment the straightened steel plate to obtain a mother plate and a daughter plate, and the cooling bed is used to air cool the mother plate and daughter plate.

[0012] Preferably, the assembly also includes an edge trimming machine, a length shear, and a stacking machine arranged sequentially after the cooling bed along the production line direction; the edge trimming machine is used to cut off the edges of the cooled mother and daughter plates; the length shear is used to cut the trimmed mother and daughter plates into finished steel plates; and the stacking machine is used to stack the finished steel plates.

[0013] On the other hand, the present invention also provides a method for producing medium-thick plates, using the medium-thick plate production line as described above, comprising the following steps: S1: After the slab is heated in a heating furnace, it is descaled by a descaling machine and then enters a roughing mill for multi-pass reversible rolling to obtain an intermediate slab; S2: When the roughing mill performs the last pass of steel removal on the same slab, the first segment shear cuts the intermediate slab into a first intermediate slab segment and a second intermediate slab segment along the current rolling direction of the roughing mill. S3: The first intermediate billet section enters the finishing mill for finishing rolling, and the second intermediate billet section returns to the insulation cover for insulation. S4: When the first intermediate billet segment is rolled in the last pass on the finishing mill, the second intermediate billet segment enters the finishing mill from the insulation cover along the current rolling direction of the finishing mill for finishing rolling; when the head of the second intermediate billet segment reaches the entrance of the finishing mill, the tail of the first intermediate billet segment leaves the exit of the finishing mill; wherein, the first intermediate billet segment or the second intermediate billet segment can continuously complete two thinning operations each time it passes through the two finishing mills of the finishing mill; S5: The first intermediate billet segment and the second intermediate billet segment are rolled sequentially by the finishing mill to obtain steel plates.

[0014] Preferably, in step S2, the first segmented shear is performed in the intermediate billet running state for follow-up shearing.

[0015] Preferably, in step S3, when the second intermediate billet is rolled in the finishing mill, the roughing mill rough rolls the next billet, and the rolling direction of the roughing mill is the same as the rolling direction of the finishing mill.

[0016] The beneficial effects of this invention are: This invention discloses a medium-thick plate production line. By configuring the finishing mill unit into two finishing mills and placing a first slitting shear between the roughing mill and the finishing mill unit, combined with the use of an insulation cover, it achieves segmented rolling of long billets and rapid continuous rolling in the finishing stage. Specifically, the first slitting shear divides the long intermediate billet after roughing into two parts, so that only the very front end and the very back end of a long billet need to be removed. The head and tail cutting losses are reduced by nearly half compared to two short billets, and the metal yield can be increased from about 92% in conventional medium-thick plate production lines to about 94%. The two finishing mills are arranged adjacent to each other along the production line direction to perform two consecutive thinning operations on the first or second intermediate billet segment passing through the two finishing mills in each pass, reducing the total number of passes and the total rolling volume in the finishing stage. The timing control manages the temperature drop during the finishing rolling process of thin-gauge products, preventing increased deformation resistance and excessive rolling force due to excessive temperature drop. The insulation hood is located between the descaling mill and the roughing mill, specifically at the roughing mill inlet. After the second intermediate billet is cut, it is conveyed in the reverse direction of rolling to the insulation hood for heat preservation, preventing it from being unable to be rolled due to excessively low temperature while waiting for finishing rolling. While the second intermediate billet is being rolled in the finishing mill, the roughing mill performs rough rolling on the next slab, achieving parallel operation of the roughing and finishing mills. Thus, under the condition of limited cooling bed width, the use of long-length billets enables efficient production of thin-gauge medium-thick plates, solving the problems of low metal yield, large temperature drop due to numerous finishing passes, and limited capacity due to the inability to perform roughing and finishing rolling in parallel on conventional production lines. This demonstrates economic benefits and promising application prospects.

[0017] The beneficial effects of the medium-thick plate production method of the present invention compared with the prior art are the same as those of the medium-thick plate production line described above, and will not be repeated here. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a medium-thick plate production line according to an embodiment of the present invention.

[0019] Among them: 1-Heating furnace; 2-First steel transfer device; 3-Descaling machine; 4-Insulation cover; 5-Roughing mill; 6-Vertical rolling mill; 7-First segment shear; 8-Finishing mill; 9-Cooling device; 10-Hot straightening machine; 11-Second segment shear; 12-Cooling bed; 13-Edge trimming shear; 14-Short length shear; 15-Stacking machine. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0021] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0022] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0023] To address the problems existing in the aforementioned related technologies, the present invention provides an anti-tangling guide plate and a cold continuous rolling mill, which will be described in detail below with reference to specific embodiments.

[0024] See Figure 1 As shown, in one aspect, an embodiment of the present invention provides a medium-thick plate production line, including a heating furnace 1, a descaling machine 3, a heat insulation cover 4, a roughing mill 5, a first slitting shear 7, and a finishing mill 8 arranged sequentially along the production line direction; the heating furnace 1 is used to heat the slab; the descaling machine 3 is used to descal the heated slab; the roughing mill 5 is used to rough roll the descaled slab into an intermediate slab; the first slitting shear 7 is used to segment the intermediate slab into a first intermediate slab segment and a second intermediate slab segment along the rolling direction; wherein, when the first intermediate slab segment enters the finishing mill 8 for finishing rolling, the second intermediate slab segment returns to the heat insulation cover 4 for heat insulation, and when the first intermediate slab segment undergoes the last pass of finishing rolling, the second intermediate slab segment enters the finishing mill 8 from the heat insulation cover 4 for finishing rolling; the heat insulation cover 4 is located at the entrance of the roughing mill 5; wherein, the finishing mill 8 includes two finishing mills, which are arranged adjacently along the production line direction, for continuously thinning the first intermediate slab segment or the second intermediate slab segment that passes through the two finishing mills twice in each pass.

[0025] Specifically, the heating furnace 1, descaling machine 3, insulation hood 4, roughing mill 5, first slitting shear 7, and finishing mill 8 are connected sequentially via roller conveyors. The heating furnace 1 heats the slab to the target temperature before it exits the furnace. The descaling machine 3 removes the iron oxide scale generated on the slab surface during heating. The descaled slab enters the roughing mill 5 for multi-pass reversible rolling, becoming an intermediate slab. The roughing mill 5 and finishing mill 8 are arranged separately, with the first slitting shear 7 positioned above the roller conveyor between them. During the final pass of the roughing mill 5, the first slitting shear 7 performs follow-up shearing while the intermediate slab is running, dividing the intermediate slab into a first intermediate slab segment and a second intermediate slab segment along the rolling direction. The first intermediate slab segment continues forward along the rolling direction, directly entering the finishing mill 8 for finishing. The second intermediate slab segment is conveyed in the reverse direction, passing under the roughing mill 5 and returning to the insulation hood 4 for insulation. A heat insulation cover 4 is installed above the roller table on the inlet side of the roughing mill 5 to reduce temperature loss of the second intermediate billet section during the waiting period. After the second intermediate billet section is heat-insulated, it passes under the roughing mill 5 again along the rolling direction and enters the finishing mill 8 for finishing rolling. The finishing mill 8 includes two finishing mills, the distance between the two finishing mills being less than the length of the intermediate billet section. When the intermediate billet section passes through the two finishing mills in sequence, its head enters the second finishing mill before leaving the first finishing mill. The intermediate billet section is simultaneously in both finishing mills and completes two pressings in sequence during the passage, achieving two consecutive pressings in one pass.

[0026] It should be noted that in this embodiment, by configuring the finishing mill unit 8 as two adjacent finishing mills arranged along the production line direction, two thinning (reduction) operations on the first or second intermediate billet section can be completed in one pass during the finishing stage. Taking the intermediate billet requiring 6 reductions as an example, in a conventional medium-thick plate production line, if a single-stand finishing mill is used for reversible rolling, the intermediate billet needs to travel back and forth 6 times on a single finishing mill, completing one reduction operation each time. This process is time-consuming, and the temperature of the intermediate billet continuously decreases during repeated passes. When the temperature approaches or falls below 800°C, the deformation resistance increases significantly, and the rolling force approaches the equipment limit. In this embodiment, however, the intermediate billet completes two reductions each time it passes through two finishing mills, requiring only 3 passes to complete 6 reductions. The number of passes is reduced by half compared to conventional single-stand reversible rolling, significantly shortening the total time of the finishing stage. The temperature drop of the intermediate billet during the finishing process is reduced, effectively avoiding the problems of increased deformation resistance and excessive rolling force caused by excessive temperature drop. The first slitting shear 7 is positioned between the roughing mill 5 and the finishing mill 8, dividing the rough-rolled intermediate billet in two. This allows thinner products, which would normally require short billets, to be produced as long billets. Since only the very front and the very back of a long billet need to be removed, the head and tail losses are reduced by nearly half compared to two short billets (which require removing four ends). This increases the metal yield from approximately 92% in conventional medium-thick plate production lines. Simultaneously, by placing the insulation hood 4 at the entrance of the roughing mill 5, the second intermediate billet segment, after being cut by the first slitting shear 7, is conveyed in the reverse direction of the rolling process to the insulation hood 4 for insulation, preventing the second intermediate billet segment from being unable to be rolled due to excessively low temperatures while waiting for finishing. During the insulation period of the second intermediate billet segment, the finishing mill 8 can perform finishing rolling on the first intermediate billet segment, achieving both finishing and waiting-to-warm-up operations and reducing idle waiting time on the production line. Thus, under the condition of limited width of cooling bed 12, the use of long blanks has enabled the efficient production of thin-specification products of medium and heavy plates, while solving the problems of low metal yield, many finishing rolling passes, large temperature drop and limited capacity of conventional medium and heavy plate production lines.

[0027] In one embodiment of the present invention, the rolling direction of the roughing mill 5 is the same as that of the finishing mill 8, and the interval between the roughing mill 5 and the finishing mill 8 is greater than the maximum length of the steel plate rolled by the finishing mill 8.

[0028] Specifically, during the heat preservation period of the second intermediate slab section when the insulation cover 4 is retracted, the roughing mill 5 begins rough rolling the next slab. When the next slab is rough rolled on the roughing mill 5 and the second intermediate slab section is finish rolled in the finishing mill 8, the rolling direction of the roughing mill 5 and the rolling direction of the finishing mill 8 remain the same, that is, the forward direction of the next slab on the roughing mill 5 is the same as the forward direction of the second intermediate slab section in the finishing mill 8. Taking the second intermediate slab section running from the entrance side to the exit side in the finishing mill 8 as an example, the next slab also runs from the entrance side to the exit side in the roughing mill 5; if the second intermediate slab section runs from the exit side to the entrance side in the finishing mill 8, then the next slab also runs from the exit side to the entrance side in the roughing mill 5. The interval between the roughing mill 5 and the finishing mill 8 is greater than the maximum length of the steel plate rolled by the finishing mill 8, so as to ensure that at any time, there is a sufficient safe distance between the next slab running at the exit of the roughing mill 5 and the second intermediate slab running at the entrance of the finishing mill 8 to avoid collision.

[0029] It should be noted that while the roughing mill 5 is roughing the next slab, the finishing mill 8 is finishing the second intermediate slab section; these are parallel operations performed simultaneously. The rolling direction of the next slab on the roughing mill 5 is the same as the rolling direction of the second intermediate slab section formed by the previous slab on the finishing mill 8 (i.e., co-directional rolling). Both run in the same direction, eliminating the risk of collision. Therefore, the distance between the roughing mill 5 and the finishing mill 8 only needs to be greater than the maximum length of the steel plate rolled by the finishing mill 8. Compared to the counter-directional rolling scheme, this saves approximately 0.5 times the production line space required for the maximum length of the steel plate, reducing costs while further improving the overall pace and capacity of the production line.

[0030] In one embodiment of the present invention, a first steel-transfer device 2 is further included. The first steel-transfer device 2 is disposed between the heating furnace 1 and the descaling machine 3, and is used to transfer the steel of the slab during the process of the slab being transported from the heating furnace 1 to the descaling machine 3.

[0031] Specifically, the first steel-turning device 2 is located in the roller conveyor area between the outlet of the heating furnace 1 and the inlet of the descaling mill 3, and is used to turn the slab before it enters the descaling mill 3. When the slab is a short-length slab and the width direction needs to be adjusted before the first rolling pass, after the slab exits the heating furnace 1, it is first rotated 90° by the first steel-turning device 2 to complete the steel-turning before entering the descaling mill 3 for descaling, and then entering the roughing mill 5 for rolling.

[0032] It should be noted that currently, the steel transfer device in medium and heavy plate production lines is usually located before the roughing mill 5 or the finishing mill. The slab needs to wait for the steel transfer to be completed before entering the mill, and this steel transfer operation consumes main line time, becoming a bottleneck in the production line's rhythm. In this embodiment, the first steel transfer device 2 is located between the heating furnace 1 and the descaling machine 3. The slab can complete the steel transfer operation during its transport from the heating furnace 1 to the descaling machine 3. Steel transfer and transport occur simultaneously, eliminating the need for a dedicated stop to wait for steel transfer before the mill. This shortens the interval between two adjacent slabs entering the roughing mill 5, improving the overall production line rhythm. Simultaneously, since no steel transfer device is set before the finishing mill 8, the intermediate slabs in the finishing stage can directly enter the finishing mill 8 without stopping for steel transfer, reducing the idle waiting time of the finishing mill 8 and further improving the continuity and rhythm of the finishing stage.

[0033] In one embodiment of the present invention, a vertical roll mill 6 is also included, which is located between the roughing mill 5 and the first slitting shear 7 and is used to adjust the width of the intermediate billet.

[0034] It should be noted that the vertical rolling mill 6 is located above the roller table on the inlet or outlet side of the roughing mill 5. When the vertical rolling mill 6 is located on the inlet side of the roughing mill 5, the slab undergoes lateral rolling on the vertical rolling mill 6 before entering the roughing mill 5 to control the width of the slab. When the vertical rolling mill 6 is located on the outlet side of the roughing mill 5, the intermediate slab after roughing undergoes width finishing rolling on the vertical rolling mill 6 to correct the width deviation generated during roughing. The vertical rolling mill 6 achieves the set width of the slab or intermediate slab by laterally pressing the edges of the slab or intermediate slab.

[0035] In one embodiment of the present invention, a second steel-transfer device for transferring intermediate billets is further included, the second steel-transfer device being disposed between the roughing mill 5 and the insulation cover 4 and / or between the roughing mill 5 and the vertical roll mill 6.

[0036] Specifically, the second steel transfer device can be set in the inlet side roller table area of ​​the roughing mill 5, or in the outlet side roller table area of ​​the roughing mill 5, or both on the inlet and outlet sides. For short-length billets, if they need to be transferred twice on the roughing mill 5, the transfer operation is completed by the second steel transfer device on the corresponding inlet or outlet side.

[0037] It should be noted that when short billets need to undergo a second transfer during roughing, the second transfer device provides the capability to complete the transfer at either the inlet or outlet side of the roughing mill 5, making the width control of short billets more flexible. The first transfer device 2 and the second transfer device are respectively set in different process positions, allowing the transfer to be performed at an appropriate position according to the rolling schedule of the short billets, avoiding the concentration of transfer operations in one location and thus avoiding disruption to the production line rhythm.

[0038] In one embodiment of the present invention, a cooling device 9, a hot straightener 10, a second slitting shear 11, and a cooling bed 12 are arranged sequentially after the finishing mill 8 along the production line direction; the cooling device 9 is used to cool the finished steel plate, the hot straightener 10 is used to straighten the cooled steel plate, the second slitting shear 11 is used to segment the straightened steel plate to obtain a mother plate and a daughter plate, and the cooling bed 12 is used to air cool the mother plate and daughter plate.

[0039] Specifically, the steel plate rolled by the finishing mill 8 is sequentially fed into the cooling device 9, hot straightener 10, second slitting shear 11, and cooling bed 12 via roller conveyors. The cooling device 9, located at the exit side of the finishing mill 8, is used to accelerate the cooling of the high-temperature steel plate after finishing, bringing it to the required process temperature. The hot straightener 10, located at the exit side of the cooling device 9, is used to straighten the cooled steel plate, eliminating shape defects generated during rolling and cooling. The second slitting shear 11, located at the exit side of the hot straightener 10, is used to segment the straightened steel plate; each segment is called a mother plate and a daughter plate. The cooling bed 12, located at the exit side of the second slitting shear 11, receives the mother and daughter plates and performs air cooling. The mother and daughter plates travel laterally on the cooling bed 12 perpendicular to the rolling direction, and after air cooling, they are removed from the cooling bed 12 and enter subsequent processes.

[0040] In one embodiment of the present invention, an edge trimming machine 13, a length shear 14, and a stacking machine 15 are arranged sequentially after the cooling bed 12 along the production line direction; the edge trimming machine 13 is used to cut off the edges of the cooled mother and daughter plates; the length shear 14 is used to cut the trimmed mother and daughter plates into finished steel plates; and the stacking machine 15 is used to stack the finished steel plates.

[0041] Specifically, the edge trimming machine 13 is located on the outlet side of the cooling bed 12 and is used to trim the edges of the air-cooled mother and daughter plates, removing burrs and irregular edges on both sides of the mother and daughter plates to ensure that the width of the mother and daughter plates meets the requirements of the finished product width. The length cutter 14 is located on the outlet side of the edge trimming machine 13 and is used to perform transverse length cutting on the trimmed mother and daughter plates, cutting them into finished steel plates that meet the order length requirements. The stacking machine 15 is located on the outlet side of the length cutter 14 and is used to stack the finished steel plates, neatly stacking them before storing them in the warehouse.

[0042] It should be noted that after the steel plate is air-cooled by the cooling bed 12, it is successively cut off by the edge trimming machine 13, cut into sections by the length cutter 14, and finally stacked into the warehouse by the stacking machine 15. This realizes the complete production process from intermediate billet to finished steel plate, ensuring the width and length accuracy of the product, and improving the yield and production efficiency of the medium and heavy plate production line.

[0043] On the other hand, the present invention also provides a method for producing medium-thick plates, using the medium-thick plate production line as described above, comprising the following steps: S1: After the slab is heated by the heating furnace 1, it is descaled by the descaling machine 3, and then enters the roughing mill 5 for multi-pass reversible rolling to obtain the intermediate slab; S2: When the roughing mill 5 performs the last pass of steel removal on the same slab, the first segment shear 7 cuts the intermediate slab into the first intermediate slab segment and the second intermediate slab segment along the current rolling direction of the roughing mill 5. S3: The first intermediate billet section enters the finishing mill 8 for finishing rolling, and the second intermediate billet section returns to the insulation cover 4 for insulation. S4: When the first intermediate billet section is rolled in the last pass on the finishing mill 8, the second intermediate billet section enters the finishing mill 8 from the insulation cover 4 along the current rolling direction of the finishing mill 8 for finishing rolling; when the head of the second intermediate billet section reaches the entrance of the finishing mill 8, the tail of the first intermediate billet section leaves the exit of the finishing mill 8; wherein, the first intermediate billet section or the second intermediate billet section can continuously complete two thinning operations when passing through the two finishing mills of the finishing mill 8 in each pass; S5: The first intermediate billet section and the second intermediate billet section are rolled sequentially by the finishing mill 8 to obtain steel plates.

[0044] It should be noted that this embodiment achieves segmented rolling of the long billet by dividing it into two parts after rough rolling using the first segment shear 7. Since only the very front end and the very back end of the long billet need to be removed, compared to the four ends required for two short billets, the head and tail losses are reduced by nearly half, improving metal yield. Simultaneously, the second intermediate billet section is kept warm under the insulation cover 4 while waiting for finishing rolling, while the first intermediate billet section is finished rolled in the finishing mill 8, achieving parallel operation of finishing rolling and waiting for warming. In step S4, by precisely controlling the timing of the second intermediate billet section's activation from the insulation cover 4, the tail end of the first intermediate billet section is just leaving the finishing mill 8 outlet when the head of the second intermediate billet section reaches the inlet of the finishing mill 8, achieving seamless connection between the first and second intermediate billet sections in the finishing mill 8. The finishing mill 8 does not need to wait or idle, maintaining continuous operation at all times. There is no time gap between the two intermediate billet sections, avoiding capacity loss and temperature drop due to waiting. In step S5, two finishing mills are used to achieve two consecutive pressings in one pass. During the passage of the intermediate billet through these two mills, the billet is simultaneously within both mills and undergoes two consecutive pressings. This allows the intermediate billet to complete two pressings in a single pass, reducing the total number of passes and rolling time in the finishing stage, and controlling the temperature drop of the intermediate billet during finishing. Thus, under the condition of limited width of the cooling bed 12, long billets are used to achieve efficient production of thin-gauge medium-thick plates, while simultaneously solving the problems of low metal yield, numerous finishing passes, large temperature drops, and limited capacity in conventional production lines.

[0045] In one embodiment of the present invention, in step S2, the first segmented shear 7 performs follow-up shearing while the intermediate billet is in operation.

[0046] Specifically, the first segment shear 7 initiates its shearing action during the final pass of the roughing mill 5. Its shearing speed is synchronized with the running speed of the intermediate billet, allowing the intermediate billet to be sheared without deceleration or stopping. The intermediate billet maintains its running speed as it passes through the first segment shear 7, which divides it in two during its journey.

[0047] In one embodiment of the present invention, in step S3, when the second intermediate billet is rolled in the finishing mill 8, the roughing mill 5 performs rough rolling on the next slab, and the rolling direction of the roughing mill 5 is the same as the rolling direction of the finishing mill 8.

[0048] It should be noted that while the second intermediate slab is being finished rolled in the finishing mill 8, the roughing mill 5 is simultaneously roughing the next slab, achieving parallel operation of the roughing mill 5 and the finishing mill 8. Since the rolling direction of the roughing mill 5 is the same as that of the finishing mill 8, the next slab, when exiting the roughing mill 5, moves in the same direction as the second intermediate slab entering the finishing mill 8. There is no risk of collision between them, eliminating the need to increase the distance between the roughing mill 5 and the finishing mill 8 to avoid collisions. Therefore, the distance between the roughing mill 5 and the finishing mill 8 only needs to be greater than the maximum length of the steel plate rolled by the finishing mill 8, without requiring additional safety distances, thus saving on production line length and investment costs.

[0049] In one embodiment of the present invention, the slab is made of carbon steel such as plain carbon steel or low alloy steel, and is produced using the aforementioned thick plate production line. The specific process parameters are as follows: The slab is a long-length slab and is rolled longitudinally. The slab thickness is 180~460mm, the width is 1500~2800mm, and the length is 1500~10000mm.

[0050] The slab is heated in heating furnace 1 at a temperature of 1150~1250℃ for approximately 2 hours. The slab is fully heated in the heating section and soaking section of heating furnace 1 to ensure temperature uniformity and reduce the temperature gradient inside the slab.

[0051] After exiting the furnace, the slab passes through a descaling machine 3 to remove surface iron oxide scale, and then enters a roughing mill 5 for multi-pass reversible rolling. The roughing stage consists of 9 passes, with an initial rolling temperature of 1100~1200℃ and a final rolling temperature of 1000~1100℃. The thickness of the intermediate slab after roughing is 38mm. The reduction amount in each pass of the roughing stage is allocated according to the rolling schedule, with larger reductions in the first few passes and gradually decreasing reductions in subsequent passes to ensure the shape and dimensional accuracy of the intermediate slab.

[0052] During the final pass of the roughing mill 5, the intermediate billet moves at a speed of approximately 1.5~3.5 m / s. The first segment shear 7 performs follow-up shearing while the intermediate billet is in motion, dividing the intermediate billet into two parts along the rolling direction: a first intermediate billet segment and a second intermediate billet segment. The shearing position is calculated and determined based on the thickness of the intermediate billet and the specifications of the finished product, ensuring that the length of the rolled piece obtained after segmentation by the finishing mill 8 is no greater than twice the width of the cooling bed 12. The length of the intermediate billet is approximately 43m, and the first segment shear 7 performs shearing at approximately 21.5m of the intermediate billet length, resulting in first and second intermediate billet segments, each approximately 21.5m in length.

[0053] The first intermediate billet section directly enters the finishing mill 8 for finishing rolling. Finishing mill 8 consists of two closely spaced finishing mills. The spacing between the two mills ensures that the intermediate billet section is simultaneously within both mills as it passes through, completing two consecutive reductions during the process. The finishing rolling stage comprises three passes, completing six reductions. Specifically, when finishing mill 8 finishes the first intermediate billet section, the reduction amount in each pass is allocated according to the rolling schedule, the maximum rolling speed is 7 m / s, and micro-tension control is maintained between the two mills. The tension value is determined based on the thickness of the intermediate billet section.

[0054] While the first intermediate billet section undergoes its final rolling pass in finishing mill 8, the second intermediate billet section enters finishing mill 8 from the insulation cover 4 along the rolling direction for finishing rolling. When the head of the second intermediate billet section reaches the entrance side of finishing mill 8, the tail of the first intermediate billet section just leaves the exit side of finishing mill 8, achieving a seamless connection. The finishing rolling passes, reduction, rolling speed, and tension control of the second intermediate billet section are the same as those of the first intermediate billet section. The first and second intermediate billet sections are rolled sequentially by finishing mill 8 to obtain a rolled piece with a thickness of 20 mm, a width of 2150 mm, and a length of 102.3 m. Since the cooling bed width is 60 m, the 102.3 m long rolled piece does not exceed twice the width of the cooling bed (120 m), and can subsequently be directly segmented by the second segment shear 11 and then air-cooled on cooling bed 12.

[0055] After finishing, the steel plate enters the cooling device 9 for laminar flow cooling. The cooling rate is set to 15℃ / s according to the product cooling regime, cooling the steel plate to 700℃. The cooled steel plate then enters the hot straightener 10 for straightening. The straightening temperature is 700℃, and the straightening force is set according to the thickness and width of the steel plate to eliminate plate shape defects and internal stress generated during rolling and cooling.

[0056] After straightening, the steel plate is segmented by the second segment shear 11 and then air-cooled on the cooling bed 12 to below 80°C. The edges are then removed by the edge trimming machine 13, and the plate is sheared into finished steel plates by the length shear 14. Finally, it is stacked and stored by the plate stacking machine 15. The finished steel plate specifications are: thickness 20mm, width 2150mm, and length 25m. In this embodiment, the metal yield of segmented rolling using long-length billets reaches 94%, which is about 2 percentage points higher than the metal yield of ordinary rolling in conventional medium-thick plate production lines (approximately 92%).

[0057] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A medium-thick plate production line, characterized in that, It includes a heating furnace (1), a descaling machine (3), a heat insulation cover (4), a roughing mill (5), a first segment shear (7), and a finishing mill (8) arranged sequentially along the production line direction; The heating furnace (1) is used to heat the slab; The descaling machine (3) is used to descale the heated slab; The roughing mill (5) is used to rough roll the descaled slab into an intermediate slab; The first segment shear (7) is used to segment the intermediate billet into a first intermediate billet segment and a second intermediate billet segment along the rolling direction; wherein, when the first intermediate billet segment enters the finishing mill (8) for finishing rolling, the second intermediate billet segment returns to the heat insulation cover (4) for heat insulation; when the first intermediate billet segment performs the last pass of finishing rolling, the second intermediate billet segment enters the finishing mill (8) from the heat insulation cover (4) for finishing rolling; The heat insulation cover (4) is located at the entrance of the roughing mill (5); The finishing mill (8) includes two finishing mills, which are arranged adjacent to each other along the production line direction, for continuously thinning the first intermediate billet section or the second intermediate billet section passing through the two finishing mills in each pass twice.

2. The medium-thick plate production line according to claim 1, characterized in that, The rolling direction of the roughing mill (5) is the same as that of the finishing mill (8), and the distance between the roughing mill (5) and the finishing mill (8) is greater than the maximum length of the steel plate rolled by the finishing mill (8).

3. The medium-thick plate production line according to claim 1, characterized in that, It also includes a first steel-transfer device (2), which is located between the heating furnace (1) and the descaling machine (3) and is used to transfer the slab to steel during the process of the slab being transported from the heating furnace (1) to the descaling machine (3).

4. The medium-thick plate production line according to claim 3, characterized in that, It also includes a vertical roll mill (6), which is located between the roughing mill (5) and the first segment shear (7) and is used to adjust the width of the intermediate billet.

5. The medium-thick plate production line according to claim 4, characterized in that, It also includes a second steel transfer device for transferring the intermediate billet, the second steel transfer device being located between the roughing mill (5) and the insulation cover (4) and / or between the roughing mill (5) and the vertical roll mill (6).

6. The medium-thick plate production line according to claim 1, characterized in that, It also includes a cooling device (9), a hot straightener (10), a second slitting shear (11), and a cooling bed (12) arranged sequentially after the finishing mill (8) along the production line direction; the cooling device (9) is used to cool the finished steel plate, the hot straightener (10) is used to straighten the cooled steel plate, the second slitting shear (11) is used to divide the straightened steel plate into sections to obtain mother and daughter plates, and the cooling bed (12) is used to air cool the mother and daughter plates.

7. The medium-thick plate production line according to claim 6, characterized in that, It also includes an edge trimming machine (13), a length shear (14), and a stacking machine (15) arranged sequentially after the cooling bed (12) along the production line direction; the edge trimming machine (13) is used to cut off the edges of the cooled mother and daughter plates; the length shear (14) is used to cut the trimmed mother and daughter plates into finished steel plates; the stacking machine (15) is used to stack the finished steel plates.

8. A method for producing medium-thick plates, using the medium-thick plate production line as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1: After the slab is heated by the heating furnace (1), it is descaled by the descaling machine (3) and then enters the roughing mill (5) for multi-pass reversible rolling to obtain the intermediate slab; S2: When the roughing mill (5) performs the last pass of steel removal on the same slab, the first segment shear (7) cuts the intermediate slab into a first intermediate slab segment and a second intermediate slab segment along the current rolling direction of the roughing mill (5); S3: The first intermediate billet section enters the finishing mill (8) for finishing rolling, and the second intermediate billet section returns to the insulation cover (4) for insulation; S4: When the first intermediate billet segment is rolled in the last pass on the finishing mill (8), the second intermediate billet segment enters the finishing mill (8) from the heat insulation cover (4) along the current rolling direction of the finishing mill (8) for finishing rolling; when the head of the second intermediate billet segment reaches the entrance of the finishing mill (8), the tail of the first intermediate billet segment leaves the exit of the finishing mill (8); wherein, the first intermediate billet segment or the second intermediate billet segment can continuously complete two thinning operations when passing through the two finishing mills of the finishing mill (8) in each pass; S5: The first intermediate billet segment and the second intermediate billet segment are rolled into steel plates by the finishing mill (8) in sequence.

9. The method for producing medium-thick plates according to claim 8, characterized in that, In step S2, the first segmented shear (7) performs follow-up shearing under the running state of the intermediate billet.

10. The method for producing medium-thick plates according to claim 8, characterized in that, In step S3, when the second intermediate billet is rolled in the finishing mill (8), the roughing mill (5) performs rough rolling on the next billet, and the rolling direction of the roughing mill (5) is the same as the rolling direction of the finishing mill (8).

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