HOT-ROLLING STAND FOR A HOT-ROLLING MILL AND FOR PRODUCING A FLAT METAL PRODUCT, HOT-ROLLING MILL AND METHOD FOR OPERATING A HOT-ROLLING MILL

Abstract

A hot-rolling stand (10) for a hot-rolling mill comprises an adjusting device (12), which is intended for receiving a pair of work rolls (17) and for positioning work rolls (18, 19; 20, 21) of the pair of work rolls (17) in relation to one another to define a roll gap. In order to create a hot-rolling stand (10) that can be adapted as flexibly as possible, the adjusting device (12) is designed to interchangeably accommodate, in the pair of work rolls (17), different roll diameter ranges by means of mutually complementary work rolls (18, 19; 20, 21).

Claims

1.-16. (canceled)

17. A hot-rolling stand (10) for a hot-rolling mill (1) and for producing a flat metal product, comprising: an adjusting device (12) that is provided for accommodating a pair of work rolls (17) and for positioning work rolls (18, 19; 20, 21) of the pair of work rolls (17) in relation to one another to define a roll gap, wherein the adjusting device (12) is designed to interchangeably accommodate, in the pair of work rolls (17), different roll diameter ranges of mutually complementary work rolls (18, 19; 20, 21), wherein a deviation between the different roll diameter ranges amounts to ≥6%, and wherein a pass line variation when using the different roll diameter ranges amounts to less than +/−20 mm.

18. The hot-rolling stand (10) according to claim 17, wherein the hot-rolling stand (10) is a roughing stand.

19. The hot-rolling stand (10) according to claim 17, wherein the hot-rolling stand (10) is a finishing stand.

20. The hot-rolling stand (10) according claim 17, wherein the deviation between the different roll diameter ranges amounts to ≥10%.

21. The hot-rolling stand (10) according to claim 17, wherein the adjusting device (12) comprises as components a wedge adjusting device (26) of a lower work roll (18; 20) of the pair of work rolls (17) and/or a hydraulic positioning device (27) of an upper work roll (19; 21) of the pair of work rolls (17) and/or in each case a work roll bending device (28, 29) of the lower (18; 20) and/or of the upper work roll (19; 21), wherein the components of the adjusting device (12) in each case have a corresponding range of adjustment to interchangeably accommodate the different roll diameter ranges of the pair of work rolls (17) with the mutually corresponding work rolls (18, 19; 20, 21).

22. The hot-rolling stand (10) according to claim 17, wherein the hot-rolling stand (10) supports a reversing operation or a one-way operation.

23. The hot-rolling stand (10) according claim 17, wherein the pass line variation amounts to less than +/−10 mm.

24. A hot-rolling mill (1) comprising at least one hot-rolling stand (10) according to claim 17.

25. The hot-rolling mill (1) according to claim 24, wherein a roughing rolling train (2) with at least one roughing stand (8) and a finishing rolling train (3) with at least one finishing stand (9) are provided, wherein the at least one roughing stand (8) of the roughing rolling train (2) and/or the at least one finishing stand (9) of the finishing rolling train (3) each is designed as the hot-rolling stand (10) according to claim 17.

26. A method for operating a hot-rolling mill (1), comprising the following method steps: a) checking a production sequence for operating parameters, the operating parameters including a pass reduction and an operating mode; b) checking a currently selected roll diameter range of work rolls (18, 19; 20, 21) of a pair of work rolls (17) of at least one hot-rolling stand (10) designed according to claim 17; c) checking whether the currently selected roll diameter range matches the operating parameters of the production sequence, wherein, if the currently selected roll diameter range does not match the operating parameters of the production sequence, a change of work rolls (18, 19; 20, 21) in pairs of the pair of work rolls (17) with a change of the roll diameter range of the work rolls (18, 19; 20, 21) is carried out at the at least one hot-rolling stand (10) and/or a change of the production sequence is carried out, and wherein subsequently the method is initiated again with step a), and wherein, if the currently selected roll diameter range does match the operating parameters of the production sequence, the rolling operation is carried out without any change.

27. The method according to claim 26, wherein, when the work rolls (18, 19; 20, 21) are changed in pairs, a change is made to a smaller roll diameter range if a pass reduction of ≥40% is detected in the hot-rolling mill (1).

28. The method according to claim 26, wherein, when the work rolls (18, 19; 20, 21) are changed in pairs, a change is made to a smaller roll diameter range if there are no breaks in operation in rolling steps for the production of individual, fully wound coils.

29. The method according to claim 26, wherein, when the work rolls (18, 19; 20, 21) are changed in pairs, a change is made to a larger roll diameter range if one pass of a roll stand is made for each fully wound coil.

30. The method according to claim 26, wherein the method steps are guided by a system configurator (44).

31. The method according to claim 30, wherein a calculation is carried out by the system configurator (44) taking into account geometric limits based on support rolls (13, 14) currently located in the at least one hot-rolling stand.

32. The method according to claim 30, wherein a calculation is carried out by the system configurator (44) taking into account process parameters selected from the group consisting of gripping conditions, rolling speed, roll rotational speed, drive rotational speed, and drive torque.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] An advantageous embodiment of the invention, which is explained below, is shown in the drawings.

[0040] FIG. 1 shows a schematic view of a hot-rolling mill;

[0041] FIG. 2 shows a schematic illustration of a hot-rolling stand of the hot-rolling mill of FIG. 1;

[0042] FIG. 3 is a sectional view of the hot-rolling stand of FIG. 2; and

[0043] FIG. 4 is a flow chart of a method for operating the hot-rolling mill of FIG. 1.

DETAILED DESCRIPTION

[0044] FIG. 1 shows a schematic view of a hot-rolling mill 1 designed in accordance with a preferred embodiment. In a production plant, this hot-rolling mill 1 can be connected in particular to an upstream continuous casting plant—which is not shown further here—and comprises a roughing rolling train 2, a finishing rolling train 3, a coiler 4 and shears 5 and 6.

[0045] In a main transport direction 7 of the hot-rolling mill 1, the entry-side roughing rolling train 2, which is composed of several roughing stands 8 arranged one behind the other, is initially followed by the shear 5, which is arranged between the roughing rolling train 2 and the finishing rolling train 3 in the main transport direction 7. The finishing rolling train has a plurality of finishing stands 9 arranged one behind the other, which are followed within the hot-rolling mill 1 in the main transport direction 7 initially by the shear 6 and at the end by the coiler 4. For reasons of simplification, no further known components, such as scale washers, heating devices, cooling devices, etc., are shown.

[0046] FIGS. 2 and 3 show views of a hot-rolling stand 10, which can specifically be one of the roughing stands 8 of the roughing rolling train 2 or one of the finishing stands 9 of the finishing rolling train 3. Thereby, the hot-rolling stand 10 is designed as a quarto roll stand and comprises two roll stands 11, of which only one is visible in this view, an adjusting device 12, a pair of support rolls and a pair of work rolls 17. Thereby, the pair of support rolls consists of an upper support roll 13 and a lower support roll 14, each of which is rotatably accommodated in an associated chock 15 or 16. Thereby, the support rolls 13 and 14 of the pair of support rolls form the pair of work rolls 17, which is used to form the rolled material fed to the hot-rolling stand 10.

[0047] As a special feature, work rolls 18 and 19 along with 20 and 21 with different roll diameter ranges can be accommodated in the hot-rolling stand 10, wherein, in FIG. 3, the left half shows an accommodation of work rolls 18 and 19 with a large roll diameter range and the right half shows an accommodation of work rolls 20 and 21 with a small roll diameter range. Each of the currently mounted work rolls 18 and 19 or 20 and 21, as the case may be, of the pair of work rolls thereby always has the same roll diameter range, wherein the work rolls 18 and 19 or 20 and 21 are changed in pairs when the roll diameter range is changed. Thereby, a deviation between the small roll diameter range and the large roll diameter range is ≥6%, preferably ≥10%. Thereby, the individual work rolls 18 or 19 or 20 or 21 are each rotatably guided in a corresponding chock 22 or 23 or 24 or 25, as the case may be.

[0048] Due to the different roll diameter ranges, there are also different strokes H1, H2, H3, H4, which are to be represented via the adjusting device 12 in order to position the work rolls 18 and 19 or 20 and 21 of the pair of work rolls while forming a required roll gap, that is, a distance between the respective work rolls 18 and 19 or 20 and 21, as the case may be. In order to adjust the respective stroke for realizing the respectively required roll gap, the adjusting device 12 comprises as components, in addition to the roll stands 11, a wedge adjusting device 26 of the lower support roll 14 and the lower work roll 18 or 20, a hydraulic positioning device 27 of the upper support roll 13 and the upper work roll 19 or 21 along with a work roll bending device 28 or 29 of each of the upper work roll 19 or 21 and the lower work roll 18 or 20, as the case may be. Thereby, the wedge adjusting device 26, the hydraulic positioning device 27 and the work roll bending devices 28 and 29 each have a range of adjustment in order to be able to realize the different strokes for representing the interchangeable accommodation of the work rolls 18 and 19 or 20 and 21 with the different roll diameter ranges. In addition, a roll balancer 30 is assigned to the upper support roll 13.

[0049] In the illustration of FIG. 3, with the small work roll diameter range used with the work rolls 18 and 19, an extension of the adjustable strokes of the adjusting device 12 is visible via assigned spacers, which can be part of the hydraulic positioning device 27, or the wedge adjusting device 26. The necessary strokes can thus be adjusted directly via the travel of the wedge adjusting device 26 and/or the hydraulic positioning device 27, or alternatively in combination with spacers that simplify the design of the adjusting device.

[0050] Via the adjusting device 12, the respective lower work roll 18 or 20 is to be adjusted with its upper edge at the height of a desired pass line 31 indicated in FIG. 2, while the respective upper work roll 19 or 21 is aligned with the lower work roll 18 or 20 to define the desired roll gap. If necessary, the roll gap is initially thereby selected to be larger for threading the rolled material and is subsequently reduced.

[0051] FIG. 2 also shows a drive of the respectively mounted work rolls 18 and 19 or 20 and 21 wherein, in the view in FIG. 2, the work rolls 18 and 19 with the small roll diameter region are indicated by dashed lines. Two drive motors 32 and 33, connected in tandem, are provided to drive the respective mounted work rolls 18 and 19 or 20 and 21 of the pair of work rolls. A shift coupling 45 can be provided between the drive motors 32, 33. The drive motors 32 and 33 are connected on the output side to a transmission gearbox 34, which may be in the form of a manual gearbox, which transmits a drive movement of the drive motors under a gear transmission ratio to a comb roller gearbox 35, via which the transmitted drive movement is transferred by means of spindles 36 and 37 in each case to the associated mounted work roll 18 or 19 or 20 or 21. For the transfer of the drive movements, the work rolls 18 and 19 or 20 and 21 have coupling sleeves 38 or 39 or 40 or 41 which are accommodated by associated sleeves 42 and 43 of the spindles 36 and 37.

[0052] It is clear that the different roll diameters of the work rolls result not only in stroke movements H1, H2 of the hydraulic positioning device 27 and the wedge adjusting device 26, but also in stroke movements (H3, H4) of the coupling sleeves 38, 39, 40, 41 and the work roll chocks 22, 23, 24, 25, which must be compensated for by the work roll bending devices 28, 29. The spindles 36, 37 used for both roll diameter ranges must be designed for a deflection resulting from the strokes.

[0053] The hot-rolling mill 1 shown in FIG. 1 is used to produce semi-finished products in the form of strips, wherein, depending on the requirements of the strip to be produced, this can be done in a single or batch operation, with which the rolled material arrives at the hot-rolling mill 1 in predetermined length sections corresponding to a finished coil and is threaded into the individual roll stand through a roll gap preset to the target thickness of the strip.

[0054] On the other hand, production can also take place in an endless operation, with which the rolled material is fed through the individual roll stands as an endless strip. During initial threading, the roll gap of each participating roll stand is set to the target thickness, wherein the first target thickness is selected to be so large that the pass can be made without any complications in terms of process technology. To adjust thinner strip lengths of the endless strip, a transition piece is manufactured, which piece has a wedge-shaped thickness progression over its strip length. For finishing, the rolled material/strip is only separated once by the shear 6 and wound into individual coils via the coiler 4.

[0055] For the design of the manufacturing process, the hot-rolling mill 1 has a system configurator 44, which is schematically indicated in FIG. 1. Among other things, this system configurator 44 is thereby capable, during the operation of the hot-rolling mill 1, of carrying out the operation of the hot-rolling mill 1 according to a method in accordance with the invention, the sequence of which is indicated in the flow diagram in FIG. 4.

[0056] Thereby, in a step S1, operating parameters of the production sequence currently to be represented are determined, wherein such operating parameters preferably comprise the parameters of pass reduction and operating mode. Upstream, downstream or parallel thereto, which roll diameter range of work rolls 18 and 19 or 20 and 21 of the pair of work rolls 17 of a hot-rolling stand 10 is currently implemented is also determined in a step S2, wherein, with such hot-rolling stand 10, as described above, it is possible to replace the work rolls 18 and 19 or 20 and 21 in pairs with work rolls with a different roll diameter range. Thereby, with the hot-rolling mill 1, one or more of the roughing stands 8 and/or one or more of the finishing stands 9 can be designed in this manner with interchangeable work rolls.

[0057] In a step S3, the system configurator 44 then checks whether the operating parameters recorded in step S1 match the respective roll diameter range of the individual hot-rolling stand 10 determined in step S2. If this is to be affirmed, a rolling operation is carried out in a step S4 without any change.

[0058] If, on the other hand, the result from step S3 is negative, the process proceeds to step S5 and/or step S6. Thereby, in step S5, a change is made to the production sequence and thus to the desired operating parameters, while in step S6, the system configurator 44 brings about a modification in the roll diameter range by changing the work rolls in pairs. Thereby, the goal of the system configurator 44 is to match the operating parameters and the respective roll diameter range.

[0059] Thereby, in step S6, the system configurator 44 takes into account geometric limits due to the support rolls 13 and 14 currently located in the individual hot-rolling stand 10, since only a corresponding stroke range can be represented via the support rolls 13 and 14 of the respective hot-rolling stand 10, and an additional replacement of the support rolls 13 and 14 is very costly. In addition, the system configurator 44 takes into account process parameters such as gripping conditions, rolling speed, roll rotational speed, drive rotational speed, and the like.

[0060] The function of the invention is described using the example of a three-stand roughing rolling train 2 with a roll diameter range 18, 19 of 850 mm and a roll diameter range 20, 21 of 1050 mm, respectively, which can be used in the hot-rolling mill 1 with the two operating modes of batch and endless. The permissible grinding range of both roll diameter ranges amounts to 100 mm. The rolled material in each case is a simple carbon steel.

[0061] As a rule, the system configurator 44 assigns various general parameters to the operating modes:

TABLE-US-00001 Operating Strip thickness Input Strip Finished strip mode Roughing stand speed thickness Endless Small Low Small Batch Large High Medium to large

[0062] Rolled material: carbon steel, “batch” operating mode

TABLE-US-00002 Roll Work roll Input Output Strip rotational Roll Forming diameter: thickness thickness speed speed torque temperature 1050 mm [mm] [mm] [m/s] [rpm] [kNm] [° C.] Stand 1 150 108 0.29 5.3 3950 1100 Stand 2 108 75 0.6 10.9 3230 1080 Stand 3 75 45 1.0 18.2 3680 1060
The absolute pass reduction amounts to 70%.

[0063] In this exemplary embodiment, it is clear that the mass flow (strip thickness times strip speed) and rolling moment are relatively high. The forming temperatures change only slightly due to the high strip speed. The system configurator 44 checks the operating parameters (initial thickness, strip speed, roll rotational speed, roll torque and forming temperature) that result from the intended operating mode of “batch” with the work roll diameter of 1050 mm used on the basis of the calculation model created by itself or by a connected calculation model and comes to the conclusion that the intended operating parameters and the roll diameter range used are suitable and that the rolling operation can be carried out under the planned conditions.

[0064] Rolled material: carbon steel, “endless” operating mode

TABLE-US-00003 Work roll Input Output Strip Roll Roll Forming diameter: thickness thickness speed rotational torque temperature 850 mm [mm] [mm] [m/s] speed [rpm] [kNm] [° C.] Stand 1 100 53 0.19 4.3 2400 1100 Stand 2 53 25 0.4 9.0 1780 1000 Stand 3 25 12 0.8 18.0 1115 941
The absolute pass reduction amounts to 88%.

[0065] In this exemplary embodiment, it is clear that the mass flow and rolling moment are relatively low, specifically 22% of the comparative value for the batch mode. As a result, the strip temperature changes significantly more, by an amount of 159° C. The system configurator 44 checks the operating parameters (initial thickness, strip speed, roll rotational speed, rolling torque and forming temperature) that result from the intended operating mode of “endless” with the work roll diameter of 850 mm used on the basis of the calculation model created by itself or by a connected calculation model and comes to the conclusion that the intended operating parameters and the roll diameter range used are suitable and that the rolling operation can be carried out under the planned conditions. Depending on the design case, it can be suggested by the system configurator 44 to roll with a modified shift stage of the transmission gearbox 34 or with only one drive motor 33 in order to realize the lower speeds and torques with optimum utilization of the motor.

[0066] If, in the same exemplary embodiment, a ∘ 1050 mm roll were used in the first pass, the comparable rotational speed would be 3.45 and would put a strain on the motor design. At the same time, the heat transfer would cause the forming temperature to drop even further, such that in unfavorable cases undesirable microstructural changes could occur. The system configurator 44 would come to the conclusion that either the intended rolling program is to be adjusted or a smaller roll diameter range is to be used to improve the unfavorable operating conditions.

[0067] The two sample calculations shown are designed for a standard product. Due to the variance with regard to the alloy, temperature range, rolled material width and input and output thickness, there are significantly larger spreads that must be taken into account by the design and calculations of the system configurator.

[0068] By means of the hot-rolling stand design in accordance with the disclosure, a hot-rolling mill, which can be flexibly adjusted to different finished products, process designs, dimensions, materials and/or quality requirements, can be realized.

LIST OF REFERENCE SIGNS

[0069] 1 Hot-rolling mill [0070] 2 Roughing rolling train [0071] 3 Finishing rolling train [0072] 4 Coiler [0073] 5 Shear [0074] 6 Shear [0075] 7 Main transport direction [0076] 8 Roughing stand [0077] 9 Finishing roll stand [0078] 10 Hot-rolling stand [0079] 11 Roll stands [0080] 12 Adjusting device [0081] 13 Upper support roll [0082] 14 Lower support roll [0083] 15 Chock [0084] 16 Chock [0085] 17 Pair of work rolls [0086] 18 Lower work roll [0087] 19 Upper work roll [0088] 20 Lower work roll [0089] 21 Upper work roll [0090] 22 Chock [0091] 23 Chock [0092] 24 Chock [0093] 25 Chock [0094] 26 Wedge adjusting device [0095] 27 Hydraulic positioning device [0096] 28 Work roll bending device [0097] 29 Work roll bending device [0098] 30 Roller balancer [0099] 31 Pass line [0100] 32 Drive motor [0101] 33 Drive motor [0102] 34 Transmission gearbox [0103] 35 Comb roller gearbox [0104] 36 Spindle [0105] 37 Spindle [0106] 38 Coupling sleeve [0107] 39 Coupling sleeve [0108] 40 Coupling sleeve [0109] 41 Coupling sleeve [0110] 42 Sleeve [0111] 43 Sleeve [0112] 44 System configurator [0113] 45 Shift coupling [0114] H1 Stroke of wedge adjusting device [0115] H2 Stroke of hydraulic positioning device [0116] H3 Stroke of upper work roll bending device/coupling sleeve [0117] H4 Stroke of lower work roll bending device/coupling sleeve [0118] S1 to S6 Individual steps