METHOD AND PLANT FOR HOT ROLLING OF METAL ROLLED MATERIAL

Description

[0001] The invention relates to a method for hot rolling metal rolling stock using at least one rolling device, wherein the method comprises the provision of semi-finished product with a thickness of greater than or equal to 150 mm as rolling stock and wherein the rolling stock is rolled from a first large initial cross-section with a gradual reduction in thickness to a relatively smaller target cross-section.

[0002] In the current state of the art, sheet-like or plate-like heavy plates are often produced by hot rolling from continuously cast slabs with relatively large initial thicknesses or large initial cross-sections. In heavy plate production, various process stages are required for shaping, but also for achieving the mechanical and technological properties of the plates. In a rolling mill, slabs are first heated as the starting material and rolled into sheet metal plates. For final rolling thicknesses of up to approximately 200 mm, slabs with a thickness of 300 to 500 mm are typically used. Continuous cast slabs are usually rolled out, which are provided by an upstream steelworks or purchased. Alternatively, slabs are rolled from cast ingots with a thickness of up to approximately 1000 mm.

[0003] Based on the requirement to roll blocks or slabs with a high initial thickness, for example for the production of thick sheet metal, the blocks or slabs are first subjected to an initial thickness reduction in so-called roughing stands. The roughing stands are normally designed to be able to roll larger cross-sections of the rolled stock. The roughing stands can be arranged in a roughing stand group within the rolling line and are constructed to ensure a large roll rise of the work rolls. In a downstream production step, the slabs are rolled down to the desired target thickness in so-called finishing stands. The task of the finishing stands is to ensure the thickness tolerances and the desired flatness required for the finished product by means of suitable measures for adjusting the thickness and contour of the roll gap.

[0004] The construction of such a rolling mill involves the provision of at least two different rolling devices with different types of rolling stands. The investment costs for such a production line / rolling line are high. Maintenance and repair work require correspondingly high expenditures.

[0005] Depending on the number and spacing of the roughing and finishing stands, it may be necessary to temporarily heat the rolled stock to maintain the desired temperature range for the forming process. This results in high energy consumption.

[0006] To improve the productivity of a rolling mill, it is generally desirable to process semi-finished products with the largest possible pass cross-section. For this purpose, DE 28 32 073 A, for example, proposes a process in which the heated rolling stock is rolled from a pusher furnace in the extension of the rolling line on the side facing away from the rolling mill in reversing passes to the pass cross-section of the continuous or semi-continuous rolling mill. The heated rolling stock is passed through the pusher furnace and brought to the pass cross-section in the first stand of the rolling mill.

[0007] Roll stands with a high rise of the work rolls with work roll bending and shifting systems are basically known in the prior art, for example from WO 2020 / 18710 A1.

[0008] A method according to the preamble of claim 1 is known, for example, from EP 0 726 101 A1. Further prior art is known from documents WO 2011 / 158091 A2, EP 0368 048 A2, DE 39 18 242 A1, DE 10 2008 409179 A1, JP 2012 147790 A, and WO 2004 / 069440 A1. The preambles of claims 1 and 8 are also based on WO 2011 / 158091 A2.

[0009] The invention is based on the object of providing an economical rolling process for the production of sheet metal, which, in addition to low investment costs, is characterized by low energy consumption and consequently also by reduced CO2 emissions.

[0010] The object underlying the invention is achieved with the features of patent claims 1 and 8. Advantageous embodiments of the invention emerge from the subclaims.

[0011] One aspect of the invention relates to a method for hot rolling metal rolling stock using at least one rolling device, the method comprising providing semi-finished product with a thickness of greater than or equal to 150 mm as rolling stock, the rolling stock being rolled in the rolling train from a first large initial cross-section with a stepwise thickness reduction to a relatively smaller target cross-section, the thickness reduction from the initial cross-section to the target cross-section being achieved exclusively by means of a single rolling device or by means of a plurality of similar rolling devices of a single rolling stand type.

[0012] The invention can be summarized as follows: according to the invention, semi-finished products with a large initial cross-section and a large initial thickness are finish-rolled from the initial cross-section or from the initial thickness to the target thickness in only a single rolling stand or exclusively in rolling stands of the same type. The invention does not provide for a division of the rolling mill into roughing stands and finishing stands. This significantly reduces the investment costs for a rolling mill. This is ensured by the use of a rolling stand with a particularly high roll pitch.

[0013] Advantageously, the rolled product provided is a semi-finished product obtained by ingot or continuous casting in the form of slabs with a thickness of greater than or equal to 550 mm.

[0014] Within the scope of the invention, it is advantageous if the thickness reduction of the rolling stock from the initial cross-section to the target cross-section is achieved in a single heating of the rolling stock, ie that all rolling passes are carried out without further heating of the rolling stock in a desired temperature window.

[0015] A preferred variant of the method according to the invention is characterized by the exclusive use of a rolling device with a work roll axial displacement and bending device and, furthermore, preferably with at least one pair of work rolls with a roll crown, particularly preferably with an S-shaped grind. By displacing the work rolls in opposite directions, the effect of a continuously variable roll gap contour is achieved.

[0016] This allows for targeted control of the roll gap contour from the first to the last rolling stand, or from the first to the last rolling direction within a rolling line. This results in a higher pass reduction or thickness reduction, thereby reducing the overall number of rolling fixtures required in the rolling mill.

[0017] The method is expediently characterized by the use of a rolling device with a maximum roll rise of at least 900 mm, preferably of at least 1000 mm.

[0018] Particularly for rolling so-called thick sheets with final rolling thicknesses of 150 mm and more, high initial thicknesses of the rolled stock are required, since a certain ratio of initial thickness to final rolling thickness should not be exceeded to ensure good core quality of the sheet. Therefore, it is advantageous if the method according to the invention provides that the ratio (degree of deformation) of an initial thickness of the initial cross-section of the rolled stock to a target thickness of the target cross-section of the rolled stock is between 2 and 3, preferably between 2 and 5.

[0019] According to the invention, the method comprises the use of at least one rolling device with at least one upper and one lower work roll and with at least one upper and one lower backup roll, wherein the work rolls and the backup rolls are mounted in a common rolling stand, the work rolls are adjustable relative to one another to set a predetermined roll gap and the work rolls are each operatively connected to at least one bending device, wherein a first bending device is assigned to the upper work roll and a second bending device is assigned to the lower work roll, the second bending device comprises bending cylinders which are arranged in a vertically fixed position and the upper work roll can be adjusted or moved along by means of the first bending device for vertically adjusting the height of the roll gap between the rolling passes.The rolling device according to the invention is characterized in particular in that the first bending device comprises bending arms which interact with stationary bending cylinders and wherein the working rolls are preferably axially and vertically adjustable.

[0020] A bending arm, as defined by the invention, is a connecting element that bridges the spatial separation between the bending cylinder and the point of action of the bending force on the work roll chocks. The structural and spatial separation of the first bending device from the second bending device enables a maximum roll opening of at least 900 mm, preferably 1200 mm, and particularly preferably 1350 mm.

[0021] To guide the upper work roll during roll gap adjustment, the stroke of the first bending device follows the travel path of the vertical adjustment of the roll gap height, ensuring contact between the upper work roll and the upper backup roll during the rolling process. The first bending device is structurally separate from a roll adjustment device.

[0022] In the rolling stands used for the process according to the invention, a decoupling of the bending device for the upper work roll from a balancing system for the upper backup roll is essentially provided. Because the bending cylinders of the first bending device are vertically fixed and preferably arranged significantly above the work roll chocks, a relatively high roll rise is ensured with good guidance of the work roll chocks in the frame window. This decoupling simplifies access to the two devices for maintenance purposes.

[0023] It is expediently provided that the bending arms of the first bending device carry the upper work roll when the height of the roll gap is adjusted vertically.

[0024] The height of the roll gap is preset before rolling begins (roll pass). For this purpose, an overhead roll adjustment moves the upper backup roll to the position in which it is held against the force of gravity by the backup roll balancing system. The upper work roll follows this vertical movement, held by the arms of the bending device. The bending cylinders, and thus also the upper work roll, initially follow the movement of the upper backup roll between rolling passes. An additional stroke of the bending cylinders bends the work roll and thus influences the contour of the roll gap as desired during the pass. The roll gap contour can also be influenced by axial displacement of the cambered work rolls.

[0025] A further aspect of the invention relates to a hot rolling mill according to claim 8.

[0026] In the context of the present invention, "immediately one after the other" means that no equipment such as furnaces or the like is arranged between the individual rolling stands. However, lateral guide devices for the rolled stock can be provided between the rolling stands.

[0027] Preferably, at least one of the rolling devices is provided with a work roll axial displacement and bending device and further preferably with at least one pair of work rolls with a roll crown, particularly preferably with an S-shaped cut.

[0028] The hot rolling mill of the type described above comprises at least one rolling device with at least one upper and one lower work roll and with at least one upper and one lower backup roll, wherein the work rolls and the backup rolls are mounted in a common rolling stand, the work rolls are adjustable relative to one another to set a predetermined roll gap and the work rolls are each operatively connected to at least one bending device, wherein a first bending device is assigned to the upper work roll and a second bending device is assigned to the lower work roll, the second bending device comprises bending cylinders which are arranged in a vertically fixed position and the upper work roll can be adjusted or moved along by means of the first bending device for vertically adjusting the height of the roll gap between the rolling passes.The rolling device according to the invention is characterized in particular in that the first bending device comprises bending arms which interact with stationary bending cylinders and wherein the working rolls are preferably axially and vertically adjustable.

[0029] The invention is explained below using an embodiment shown in the drawings.

[0030] They show: Figure 1 is a schematic representation of a rolling mill according to the invention, Figure 2 is a longitudinal section through a first variant of a rolling device with a pair of working rolls and a pair of backup rolls, which can be used in the rolling method according to the invention, Figure 3 is a cross section along the line BB in Figure 1 , which shows a first variant of an axial displacement device for the upper work roll, Figure 4 one of the Figure 3corresponding view showing a second variant of an axial displacement device for the upper working roll, Figure 5 a longitudinal section through a rolling device according to a second variant, Figure 6 a cross section through the upper crosshead of the roll stand of the rolling device in Figure 5 , which illustrates an alternative design of the fastening of the bending cylinders of the upper bending device, and Figure 7 shows a cross section along the line BB in Figure 6 .

[0031] First, reference is made to the Figure 1. Shown is the layout of a rolling mill 100 comprising a single rolling device 1, to which semi-finished products with a thickness of greater than or equal to 150 mm are fed as rolled stock via a feed roller table 101. The rolled stock is reduced in the reversibly operated rolling device 1 with several passes, for example to a final thickness of 5 mm. The width of the rolled stock is predetermined by an edging stand 102 arranged behind the rolling device 1 in the rolling line. Via an exit roller table 103, the finished rolled product first reaches a pre-leveling machine 104 and then a hot leveler 105. The usual units for descaling the starting material upstream of the rolling device 1 and for cooling the finished rolled product are not described in more detail in the exemplary embodiment.

[0032] The Figure 2shows a rolling device 1 for use in the method and in the rolling mill according to the invention. The rolling device 1 comprises a rolling stand 2 with two work rolls, 3 and 4, and two backup rolls 5, 6. The rolling stand 2 described in the exemplary embodiments is designed as a four-roll stand, but this can also have a different configuration. A roll gap 7 is formed between the work rolls 3, 4, into which the rolled stock is drawn during operation of the rolling device 1. The height 8 of the roll gap 7, also referred to as the roll rise, is adjustable in the rolling device 1 according to the invention, namely via an upper roll adjustment 28 and a lower roll adjustment (not shown). In addition, the work rolls 3, 4 are also axially adjustable, as will be described below, so that the contour of the roll gap 6 can also be influenced via the axial adjustment of the work rolls 3, 4 relative to one another.

[0033] The work rolls 3, 4 and the backup rolls 5, 6 are held in a rolling stand 2, which comprises two roll housings 31, one on the operating side and one on the drive side. The roll housings 31 are designed as closed frames in which all rolling forces are kept in balance by internal forces. The rolling stand 2 accommodates backup roll chocks 9, 10 and work roll chocks 11, 12, each of which is slidably arranged within the windows 32 formed by the roll housings. The backup roll chocks 9, 10 support the lower and upper backup rolls 5, 6, with the backup roll chock 10 shown in the drawing supporting the upper backup roll 6 and the backup roll chock 9 supporting the lower backup roll 5.

[0034] Between the backup roll chocks 9, 10, work roll chocks 11, 12 are arranged, within which the work rolls 3, 4 are mounted. The upper work roll chock 12 supports the upper work roll 4, whereas the lower work roll chock 11 supports the lower work roll 3.

[0035] The work roll chocks 11, which accommodate the lower work roll 3, are movably arranged in stationary blocks 13. The blocks 13 accommodate bending cylinders 14 for bending the lower work roll 3. The bending cylinders 14, which act on the work roll chocks 11 for the lower work roll 3, are part of the second, lower bending device. As an alternative to the blocks, the rolling stand 2 can also have thickened portions for accommodating the bending cylinders 14 (not shown).

[0036] Balancing arms 33 engage the support roller chock 10 for the upper support roller 6, via which the dead weight of the support roller 6 can be compensated by means of balancing cylinders (not shown). For this purpose, the balancing arms 33 are equipped with hook-shaped thickenings that engage under corresponding projections of the support roller chock 10.

[0037] The work roll bending and / or work roll balancing of the upper work roll 4 is achieved via bending cylinders 15, which are operatively connected to the upper work roll 4 via bending arms 16. The bending cylinders 15 and the bending arms 16 are part of the first, upper bending device. The bending cylinders 15 are fixedly mounted on an upper crosshead 34 of the roll stand 2 or supported on the upper crosshead 34 of the roll stand 2 and pass through recesses 35 in the roll stand 2. The bending cylinders 15 extend essentially vertically. Attached to the bending cylinders 15 are the bending arms 16, each having thickened portions 17 at their lower ends. The thickened portions 17 of the bending arms 16 engage under lateral, ear-shaped projections of the work roll chock 12 of the upper work roll 4.

[0038] The bending cylinders are preferably designed for a large stroke that exceeds the work roll wear plus the roll rise.

[0039] The bending arms 16 are guided vertically into recesses 36 of the rolling stand 2 or the roll housings 31 of the rolling stand 2 by means of guide elements 18. The upper work roll 4 and the upper backup roll 6 are guided by the bending arms 16, which engage under the work roll chock 12 with the thickened portions 17, when the height 8 of the roll gap 7 is adjusted.

[0040] The bending cylinders 14, 15 act on the outer edge regions of the work rolls 3, 4 and thus exert a force directed vertically outwards from the roll gap 7 in the edge region of the work rolls 3, 4, corresponding to the force of the rolling stock acting in the central region of the work rolls 3, 4, in order to counteract a bending apart of the work rolls 3, 4 by the rolling stock.

[0041] The bending cylinders 14, 15 are used in the Figure 2 The first embodiment of the invention shown serves to achieve a so-called positive work roll bending. To increase the adjustment range for profile influencing through a so-called negative work roll bending, additional piston-cylinder systems 19, 20 are provided, each acting vertically.

[0042] Figure 5 shows a second embodiment of the rolling device 1 according to the invention. Identical components are provided with the same reference numerals. In contrast to the embodiment according to Figure 2 There, the bending cylinders 15 of the first, upper bending device partially dip from below in the upper area of ​​the window 32 into quiver-shaped recesses 35 of the upper crosshead 34 of the rolling stand 2.

[0043] The embodiment according to Figure 5 further differs from that according to Figure 2that window-like recesses 36 are provided in the bending arms 16, into which correspondingly designed strips 37 of the work roll chocks 12 for the upper work roll 4 engage. Thus, the work roll chocks 12 for the upper work roll 4 are fixed in vertically opposite directions, so that the upper work roll 4 can be bent both positively and negatively by means of the bending cylinders 15.

[0044] Figure 6 shows an alternative variant of the stationary fastening of the bending cylinders 15 to the roll stand 2. Here, several bending cylinders 15 are arranged on the outside of the roll stand 31 of the roll stand 2 and each act on extensions 30 of the bending arms 16.

[0045] The rolling device 1 according to the invention also comprises axial displacement devices 21, which are each arranged at the outer edge regions of the work rolls 3, 4.

[0046] The axial displacement devices 21 for axially displacing the work rolls 3, 4 are provided on the operating-side work roll chocks 11, 12 and comprise hydraulically actuated piston-cylinder units. The piston of each piston-cylinder unit is connected to holding arms 24 guided in the corresponding chocks. Locks arranged on the outside of the two crosspieces of the operating-side roll stand 31 prevent horizontal movement of the holding arms 24 during rolling operation and thus axial movement of a piston 22 of the piston-cylinder unit. By applying pressure to the piston side or the rod side of the piston-cylinder unit, axial displacement of the work rolls 3, 4 mounted in the work roll chocks 11, 12 is achieved.

[0047] Figure 3 shows a cross section through the rolling device 1 according to Figure 5 , along lines BB in Figure 5, which illustrates the structure of an axial displacement device 21 and its interaction with the upper work roll 4. The axial displacement device 21 comprises at least one hydraulically acting piston 22, which is arranged on the holding arms 24 via an abutment 25. The holding arms 24 are arranged to slide horizontally in the work roll chocks 11, 12 and are encompassed by lateral holding devices 29, which are fixed on the outside of the rolling stand 2 and prevent a horizontal movement of the holding arms 24 in the direction of the roll axis 23. This also fixes the piston 22 of the axial displacement device 21 in the axial direction. The holding arms 24 are movable in the vertical direction in the lateral holding devices 29.

[0048] From the Figure 3The cross-section shown also shows the interaction of the guide elements 18 of the profiled outer sides of the bending arms with correspondingly designed guide grooves 38 of the roller stand 31 or the beams of the roller stand 31.

[0049] The Figure 4 shows an alternative design of the axial displacement devices 21. The same components are in Figure 4 are provided with the same reference numerals. The axial displacement device 21 according to Figure 4 differs from that in Figure 3 It is shown that the holding devices 29 are attached to the bending arms 16 and are thus carried along when adjusting the height 8 of the roll gap 7.

[0050] Figure 7shows an alternative design for guiding the bending arms 16 within the rolling stand. On their sides facing the beams of the roll stand 31, the bending arms 16 are provided with guide grooves 38 that engage around a corresponding guide profile 39 of the beams of the roll stand 31. List of reference symbols

[0051] 1 Rolling device 22 Pistons 2 Rolling stand 23 Axis of the work roll 3 lower work roll 24 Holding arm 4 upper work roll 25 abutment 5 lower support roller 26 warehouse 6 upper support roller 27 Cylinder housing 7 Roll gap 28 upper roller adjustment 8 Height of the roll gap 29 side holding device 9 Support roll chock 30 Extension of the bending arm 10 Support roll chock 31 Roller stand 11 Work roll chock 32 Window 12 Work roll chock 33 Balancing arms upper SW 13 Bending block 34 Crosshead 14 Bending cylinder lower work roll 35 Recesses-QH 15 Bending cylinder upper work roll 36 Recesses-WS 16 Bending arms 37 Afford 17 Thickening of the bending arm 38 Guide grooves 18 Guide element 39 Leadership profile 19 Piston-cylinder system 100 rolling mill 20 Piston-cylinder system 101 Feed roller conveyor 21 Axial displacement device 102 Edger 103 Exit roller conveyor 104 Pre-straightening machine 105 Hot straightening machine

Claims

1. Method for hot-rolling metal rolling material with use of at least one rolling device, wherein the method comprises provision of a semi-finished product with a thickness greater than or equal to 150 mm as rolling material, wherein the rolling material is rolled from a first, large initial pass cross-section to a comparatively smaller target cross-section with stepped thickness reduction, wherein the thickness reduction from the initial pass cross-section to the target cross-section is achieved exclusively by means of a single rolling device or with a plurality of identical rolling devices of a single roll stand type, wherein at last one of the rolling devices (1) comprises at least one upper and lower work roll (3, 4), wherein the rolling device (1) comprises at least one upper and one lower backing roll (5, 6), wherein the work rolls (3, 4) and the backing rolls (5, 6) are mounted in a common roll stand (2), the work rolls (3, 4) being adjustable relative to one another for setting a predetermined rolling gap (7), characterised in that the work rolls (3, 4) are each in operative connection with at least one bending device, wherein at least one first bending device is associated with the upper work roll (4) and at least one second bending device is associated with the lower work roll (3), the second bending device comprises bending cylinders (14) which are arranged vertically in stationary location and the upper work roll (4) is resettable or entrainable by means of the first bending device with a vertical setting of the height (8) of the rolling gap (7), wherein the first bending device comprises bending arms (16) which co-operate with bending cylinders (15) arranged in stationary location and wherein the work rolls (3, 4) are preferably axially and vertically adjustable, wherein the bending cylinders (15) of the first bending device are mounted in stationary location on an upper crosshead (34) of a roll housing (31) or are supported on the upper crosshead (34) of the roll housing (2) and pass through recesses (35) of the roll housing (2).

2. Method according to claim 1, characterised in that a semi-finished product, which is obtained by ingot casting or continuous casting, in the form of slabs with a thickness greater than or equal to 550 mm is provided as rolling material.

3. Method according to one of claims 1 and 2, characterised in that the thickness reduction from the initial pass cross-section to the target cross-section is achieved in a single heat of the rolling material.

4. Method according to any one of claims 1 to 3, characterised by exclusive use of rolling devices with a work-roll axial displacing and bending device, preferably with a work roll pair with a roll camber, particularly preferably with a roll form ground to S-shape.

5. Method according to any one of claims 1 to 4, characterised by use of rolling devices with a maximum roll rise of at least 900 mm, preferably of at least 1,000 mm.

6. Method according to any one of claims 1 to 5, characterised in that the ratio of an exit thickness of the exit cross-section of the rolling material to a target thickness of the target cross-section of the rolling material is between 2 and 5, preferably between 2 and 3.

7. Method according to claim 1, characterised in that the bending arm (16) of the first bending device entrains the upper work roll (4) when the height (8) of the rolling gap (7) is set.

8. Hot-rolling mill for carrying out the method according to any one of claims 1 to 7, wherein a single rolling device or a plurality of identical rolling devices, which are arranged in a rolling line preferably directly in succession, of a single roll stand type, wherein at least one the rolling devices (1) comprises at least one upper and lower work roll (3, 4) and at least one upper and one lower backing roll (5, 6), wherein the work rolls (3, 4) and the backing rolls (5, 6) are mounted in a common roll stand (2), the work rolls (3, 4) being adjustable relative to one another for setting a predetermined rolling gap (7), characterised in that the work rolls (3, 4) are each in operative connection with at least one bending device, wherein at least one first bending device is associated with the upper work roll (4) and at least one second bending device is associated with the lower work roll (3), the second bending device comprises bending cylinders (14) which are arranged vertically in stationary location and the upper work roll (4) is resettable or entrainable by means of the first bending device with a vertical setting of the height (8) of the rolling gap (7), wherein the first bending device comprises bending arms (16) which co-operate with bending cylinders (15) arranged in stationary location and wherein the work rolls (3, 4) are preferably axially and vertically adjustable, wherein the bending cylinders (15) of the first bending device are mounted in stationary location on an upper crosshead (34) of a roll housing (31) or are supported on the upper crosshead (34) of the roll housing (2) and pass through recesses (35) of the roll housing (2).

9. Hot-rolling mill according to claim 8, characterised in that at least one of the rolling devices in the rolling line comprises a work-roll axial displacing and bending device with a work roll pair with a roll camber, particularly preferably with a roll form ground to S-shape.