CN118119458A - Method and apparatus for hot rolling metal rolled stock - Google Patents

Abstract

The invention relates to a method for hot rolling a metal rolled stock, using a plurality of rolling devices arranged in a rolling mill, wherein the method comprises providing a semifinished product having a thickness of greater than or equal to 150mm as rolled stock, wherein the rolled stock is rolled in the rolling mill from a first large starting cross section to a relatively smaller target cross section by a gradual reduction in thickness, characterized in that the reduction in thickness from the starting cross section to the target cross section is effected by means of only a single rolling device or by means of a plurality of similar rolling devices of the single rolling mill stand type. The invention also relates to a hot rolling installation for carrying out said method.

Description

Method and apparatus for hot rolling metal rolled stock

Technical Field

The invention relates to a method for hot rolling a metal rolled stock using at least one rolling device, wherein the method comprises providing a semifinished product having a thickness of greater than or equal to 150mm as rolled stock, and wherein the rolled stock is rolled from a first large starting cross section (Anstichquerschnitt) to a relatively smaller target cross section by a gradual thickness reduction.

Background

In the prior art, slab-like or flat slabs are usually produced by hot rolling using continuous casting slabs having a large initial thickness or a large initial cross section. In the production of thick plates, different process stages are required for shaping and for achieving the mechanical properties of the plate. In a rolling mill, a slab is first heated as a raw material and rolled into a sheet. For final rolled thicknesses of up to about 200mm, slabs with a thickness of 300 to 500mm are generally used. Most continuous cast slabs being rolled are supplied or purchased from an upstream steelworks. Alternatively, the slab is rolled from an ingot up to about 1000mm thick.

Based on the need to roll a block or slab with a high initial thickness, for example in order to produce a thick plate, the block or slab is first subjected to a first reduction in thickness in a so-called roughing stand. Roughing stands are generally designed to be able to roll a rolled stock of a larger initial rolling cross section. The roughing stands can be arranged in groups of roughing stands within the pass line and are designed to ensure a large roll lift (Walzenaufgang) of the work rolls. In a subsequent production step, the slab is rolled to the desired target thickness in a so-called finishing stand. The task of the finishing stand is to adjust the thickness and the contour of the roll gap by appropriate measures, which ensure the required thickness tolerance and the desired flatness of the finished product.

The construction of such a rolling train comprises providing at least two different rolling devices having different rolling stand types. The investment costs of the production line/pass line thus configured are high. Maintenance and repair require correspondingly high costs.

Depending on the number of roughing stands and finishing stands and the distance from each other, it may be necessary to heat the rolled stock simultaneously to maintain the desired temperature range for the forming process. Thereby resulting in higher energy consumption.

In order to increase the productivity of the rolling train, it is fundamentally desirable to process semifinished products having as large an initial rolling cross section as possible. For this purpose, for example, in DE 28 32 073A, a method is proposed in which, in the extension of the pass line on the side facing away from the rolling mill train, the heated rolled stock is rolled from the pusher furnace in a reversible pass (REVERSIERSTICHEN) into an initial rolling cross section of the continuous or semi-continuous rolling mill train and is brought into the first stand of the rolling mill train by being guided through the pusher furnace for initial rolling.

In the prior art, for example, from WO 2020/18710A1, a rolling mill stand with high-lift work rolls using a work roll bending and displacement system is basically known.

Disclosure of Invention

The object of the present invention is to provide an economical rolling process for producing sheet material, which, in addition to being inexpensive to invest in purchase, has the characteristic of low energy consumption and therefore reduced CO ₂ emissions.

The object on which the invention is based is achieved by the features of the independent claims 1 and 9. Advantageous embodiments of the invention result from the dependent claims.

One aspect of the invention relates to a method for hot rolling a metal rolled stock using at least one rolling device, wherein the method comprises providing a semifinished product having a thickness of greater than or equal to 150mm as rolled stock, wherein the rolled stock is rolled in a rolling train from a first large starting cross section to a relatively smaller target cross section by a gradual thickness reduction, wherein the thickness reduction from the starting cross section to the target cross section is achieved by means of only a single rolling device or by means of a plurality of similar rolling devices of a single rolling stand type.

The invention can be summarized as follows: the semifinished product according to the invention having a large initial cross section and a large initial thickness is finish-rolled from the starting cross section or from the starting thickness to the target thickness only in a single rolling stand or in rolling stands of the same type, wherein the rolling train is not divided into a roughing stand and a finishing stand according to the invention. This results in a significant reduction in the investment costs of the rolling plant.

Semifinished products in the form of slabs having a thickness greater than or equal to 550mm obtained by ingot casting or continuous casting are conveniently provided as rolled stock.

Within the framework of the invention, it is advantageous if the reduction in thickness of the rolled stock from the starting cross section up to the target cross section is achieved in a single heating of the rolled stock, i.e. all rolling passes are carried out within the required temperature window without further heating of the rolled stock.

A preferred variant of the method according to the invention is characterized in that only rolling devices with work roll axial displacement and bending devices are used, and further preferably with at least one pair of work rolls with roll crowns (Walzenbombierung), particularly preferably with S-grinding. By moving the work rolls in opposite directions, the roll gap profile is caused to continuously vary.

The roll gap contour can thus be influenced in a targeted manner in the pass line from the first roll stand to the last roll stand or from the first roll direction to the last roll direction. A higher pass reduction or thickness reduction is thereby achieved, so that the number of rolling devices required in the rolling mill train as a whole is reduced.

The method is advantageously characterized by using a rolling device with a maximum roll lift of at least 900mm, preferably at least 1000 mm.

In particular for rolling so-called slabs having a final rolling thickness of 150 mm and above, a higher initial thickness of the rolled stock is required, since the specific ratio of initial thickness to final rolling thickness should not be too low in order to obtain a good core quality of the slab. Advantageously, the method according to the invention therefore provides that the ratio (degree of deformation) of the initial thickness of the initial cross section of the rolled stock to the target thickness of the target cross section of the rolled stock is between 2 and 3, preferably between 2 and 5.

According to the invention, the method comprises using at least one rolling device with at least one upper and lower work roll and with at least one upper and lower support roll, the work rolls and the support rolls being supported in a common rolling stand, the work rolls being adjustable relative to each other to set a predetermined roll gap and the work rolls being respectively operatively connected to at least one bending device, wherein the upper work roll is assigned a first bending device and the lower work roll is assigned a second bending device, the second bending device comprising bending cylinders which are arranged in a fixed position in the vertical direction, and the upper work roll being able to be fine-tuned or jointly guided between the rolling passes by means of the first bending device in order to set the height of the roll gap in the vertical direction. The rolling device according to the invention is characterized in particular in that the first bending device comprises a bending arm which cooperates with a bending cylinder which is arranged in a fixed manner, and in that the working rolls are preferably adjustable in the axial direction and in the vertical direction.

In the sense of the present invention, a bending arm is understood to be a connecting element bridging the spatial separation from the bending cylinder to the point of action of the bending force on the work roll mount. The structural and spatial separation of the first bending device from the second bending device enables a maximum roll lift of at least 900mm, preferably 1200mm, particularly preferably 1350mm.

In order to jointly guide the upper work rolls during the adjustment of the roll gap, the path of travel of the first bending device follows the path of travel of the vertical adjustment of the roll gap height, so that contact between the upper work rolls and the upper support rolls is ensured for the rolling process. The first bending device is structurally separate from the roll adjustment device.

In the rolling stand for the method according to the invention, the bending device for the upper work rolls is essentially arranged separately from the balancing system for the upper support rolls. By arranging the bending cylinder of the first bending device in a fixed position in the vertical direction and preferably significantly above the work roll mount, a relatively high roll lift is ensured with good guidance of the work roll mount in the frame window. This separation simplifies the accessibility of the two devices for maintenance.

Advantageously, the bending arms of the first bending device together guide the upper work roll when the height of the roll gap is adjusted in the vertical direction.

The height of the roll gap is preset before the start of rolling (rolling pass). For this purpose, the top roll adjustment device moves the upper support roll into position, in which it is held against gravity by the support roll balancing device. The upper work roll follows this vertical movement, wherein the upper work roll is held by the arms of the bending device. The bending cylinder and the upper work roll initially follow the movement of the upper backup roll between rolling passes. The additional travel of the bending cylinder causes the work rolls to bend and thus has the desired effect on the roll gap profile during the pass. In addition, the roll gap profile is affected by the axial displacement of the arcuate work rolls.

Another aspect of the invention relates to a hot rolling plant, in particular for carrying out the method according to the invention. The hot rolling installation is characterized by a single rolling device or a plurality of similar rolling devices of the single rolling stand type, which are preferably arranged directly one after the other along a pass line, wherein the pass line is formed by only similar rolling devices of the single rolling stand type. In the sense of the invention, directly one after the other means that no facilities such as melting furnaces are arranged between the individual rolling stands. However, lateral guides for the rolled stock can be provided between the rolling stands.

Preferably, at least one rolling device is configured 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 S-grinding.

The hot rolling installation of the above-mentioned type preferably comprises at least one rolling device with at least one upper and lower work roll and with at least one upper and lower support roll, the work rolls and the support rolls being supported in a common rolling stand, the work rolls being adjustable relative to one another to set a predetermined roll gap and the work rolls being each operatively connected to at least one bending device, wherein the upper work roll is assigned a first bending device and the lower work roll is assigned a second bending device, the second bending device comprising bending cylinders which are arranged in a stationary manner in the vertical direction and the upper work roll being able to be fine-tuned or jointly guided between the rolling passes by means of the first bending device to set the height of the roll gap in the vertical direction. The rolling device according to the invention is characterized in particular in that the first bending device comprises a bending arm which cooperates with a bending cylinder which is arranged in a fixed manner, and in that the working rolls are preferably adjustable in the axial direction and in the vertical direction.

Drawings

The invention is explained below using the embodiments shown in the drawings.

The drawings show:

fig. 1 shows a schematic view of a rolling plant according to the invention;

Fig. 2 shows a longitudinal section of a first variant of a rolling device with a pair of work rolls and a pair of support rolls that can be used in the rolling method according to the invention;

FIG. 3 shows a cross section taken along line B-B in FIG. 1, illustrating a first variation of an axial displacement device for an upper work roll;

Fig. 4 shows a view corresponding to fig. 3, which shows a second variant of the axial displacement device for the upper work roll;

fig. 5 shows a longitudinal section of a rolling device according to a second variant;

Fig. 6 shows a cross section of the upper transverse body of the roll stand of the rolling device in fig. 5, illustrating an alternative embodiment of the fixation of the bending cylinder of the upper bending device; and

Fig. 7 shows a cross section taken along line B-B in fig. 6.

Detailed Description

Reference is first made to fig. 1. Shown is an arrangement of a rolling plant 100 comprising a single rolling device 1 to which semifinished products having a thickness greater than or equal to 150mm are delivered as rolled stock by means of a feed roller table 101. The rolled stock is reduced in the reversibly driven rolling device 1 to a final thickness of, for example, 5mm by means of a plurality of passes. The width of the rolled stock is given by an upsetting frame 102 arranged along the pass line after the rolling device 1. The finished rolled product first reaches the pre-straightener 104 and then reaches the hot straightener 105 via the exit table 103. A usual device for descaling the raw material before the rolling device 1 and for cooling the finished rolled product is not specified in this example.

Fig. 2 shows a rolling device 1 for use in a method and a rolling plant according to the invention. The rolling device 1 comprises a rolling stand 2 with two work rolls 3 and 4 and two support rolls 5, 6. The rolling stand 2 described in the exemplary embodiment is configured as a four-roll stand, but it can also have other configurations. A roll gap 7 is formed between the work rolls 3, 4, into which roll gap 7 the rolled stock is pulled during operation of the rolling device 1. The height 8 (also referred to as the roll lift) of the roll gap 7 is adjustable in the rolling device 1 according to the invention, i.e. by means of an upper roll adjustment 28 and a lower roll adjustment (not shown). Furthermore, as described below, the work rolls 3, 4 are also axially adjustable, so that the contour of the roll gap 7 can also be influenced by the axial adjustment of the work rolls 3, 4 relative to each other.

The work rolls 3, 4 and the support rolls 5, 6 are held in a rolling mill stand 2 comprising two roll stands 31, one on the operating side and one on the drive side. The roller housing 31 is constructed as a closed frame, wherein all rolling forces are balanced by internal forces. The roll stand 2 accommodates support roll mounts 9, 10 and work roll mounts 11, 12, which are each displaceably arranged in a window 32 formed by the roll stand. The support roller mounts 9, 10 support the lower support roller 5 and the upper support roller 6, wherein the support roller mount 10 shown in the figures supports the upper support roller 6 and the support roller mount 9 supports the lower support roller 5.

Between the support roller mountings 9, 10 are arranged work roller mountings 11, 12, in which work rollers 3,4 are supported in the work roller mountings 11, 12. The upper work roll mounting 12 supports the upper work roll 4 and the lower work roll mounting 11 supports the lower work roll 3.

The work roll mount 11 accommodating the lower work roll 3 is displaceably arranged in a fixed block 13. The block 13 accommodates a bending cylinder 14 so as to be able to bend the lower work roll 3. The bending cylinder 14 acting on the work roll mounting 11 of the lower work roll 3 is part of the second lower bending device. Instead of the blocks, the rolling stand 2 may also have a thickening to accommodate bending cylinders 14 (not shown).

The balancing arm 33 engages on the support roller mount 10 for the upper support roller 6, by means of which the dead weight of the support roller 6 can be compensated by means of a balancing cylinder (not shown). For this purpose, the balancing arms 33 are provided with hook-shaped thickenings which engage under corresponding projections of the support roller mount 10.

The work roll bending and/or work roll balancing of the upper work roll 4 is achieved by bending cylinders 15 operatively connected to the upper work roll 4 by bending arms 16. The bending cylinder 15 and the bending arm 16 are part of a first upper bending device. The bending cylinder 15 is mounted in a stationary manner on the upper transverse body 34 of the roller housing 2 or on the upper transverse body 34 of the roller housing 2 and passes through a recess 35 of the roller housing 2. The bending cylinder 15 extends substantially vertically. In the extension of the bending cylinder 15, bending arms 16 are attached thereto, each having a thickening 17 at the lower end. The thickened portion 17 of the flexure arm 16 engages under the lateral lug-shaped projection of the work roll mount 12 of the upper work roll 4.

The bending cylinder is preferably designed for a large stroke, which exceeds the work roll wear plus the roll lift.

The bending arm 16 is guided vertically by means of the guide element 18 into a recess 36 of the rolling stand 2 or into a roll stand 31 of the rolling stand 2. When adjusting the height 8 of the roll gap 7, the upper work roll 4 and the upper support roll 6 are guided together by a curved arm 16 which is joined below the work roll mount 12 by a thickening 17.

The bending cylinders 14, 15 act on the outer edge regions of the work rolls 3, 4 and thus exert in the edge regions of the work rolls 3, 4 a force directed vertically outwards from the roll gap 7, which corresponds to the force of the rolled stock acting in the middle region of the work rolls 3, 4, in order to counteract the separation of the work rolls 3, 4 by bending of the rolled stock.

In the first embodiment of the invention shown in fig. 2, bending cylinders 14, 15 are used to achieve a so-called positive work roll bending. In order to increase the adjustment range for influencing the profile by means of so-called negative work roll bending, additional piston-cylinder systems 19, 20 are provided, each acting vertically.

Fig. 5 shows a second embodiment of a rolling device 1 according to the invention. Like parts are provided with like reference numerals. In contrast to the exemplary embodiment according to fig. 2, the bending cylinder 15 of the first upper bending device protrudes from below partially into the arrow-pocket recess 35 of the upper transverse body 34 of the rolling stand 2 in the upper region of the window 32.

The embodiment according to fig. 5 also differs from the embodiment according to fig. 2 in that a window-like recess 36 is provided in the bending arm 16, into which a correspondingly configured shoulder (Leiste) 37 of the work roll mount 12 for the upper work roll 4 engages. Therefore, the work roll mounts 12 for the upper work rolls 4 are fixed in vertically opposite directions so that the upper work rolls 4 can be bent positively and negatively by means of the bending cylinders 15.

Fig. 6 shows an alternative variant in which the bending cylinder 15 is fixedly secured to the roll stand 2. Here, a plurality of bending cylinders 15 are arranged outside the roll stand 31 of the rolling stand 2 and each bending cylinder 15 acts on an extension 30 of a bending arm 16.

The rolling device 1 according to the invention further comprises axial displacement means 21, which are arranged at the outer edge areas of the work rolls 3,4, respectively.

An axial displacement device 21 for axially displacing the work rolls 3, 4 is provided on the work roll mounts 11, 12 on the operating side and comprises a hydraulically actuatable piston cylinder unit. The piston of the piston cylinder unit is connected to a holding arm 24 guided in the corresponding mount. The locking members provided on the outer sides of the two cross beams (Holm) of the roll stand 31 on the operating side prevent the horizontal movement of the holding arms 24 during the rolling operation and thus the axial movement of the pistons 22 of the piston cylinder units. The axial displacement of the work rolls 3, 4 supported in the work roll mounts 11, 12 is achieved by applying pressure to the piston side or the rod side of the piston cylinder unit.

Fig. 3 shows a cross section of the rolling device 1 according to fig. 2, taken along the line B-B in fig. 5, which shows the structure of the axial displacement device 21 and its co-action with the upper work rolls 4. The axial displacement device 21 comprises at least one hydraulically acting piston 22 which is arranged on a holding arm 24 via a bearing 25. The retaining arms 24 are arranged to slide horizontally in the work roll mountings 11, 12 and are surrounded by lateral retaining means 29 which are fixed on the outside of the mill stand 2 and prevent the retaining arms 24 from moving horizontally in the direction of the roll axis 23. Thus, the piston 22 of the axial displacement device 21 is also fixed in the axial direction. The retaining arm 24 is movable in a vertical direction in a lateral retaining means 29.

From the cross section shown in fig. 3, it can also be seen that the guide elements 18 on the profiled outer side of the bending arm co-operate with correspondingly configured guide grooves 38 of the roller frame 31 or with a transverse beam of the roller frame 31.

Fig. 4 shows an alternative embodiment of the axial displacement device 21. Like parts have like reference numerals in fig. 4. The axial displacement device 21 according to fig. 4 differs from the axial displacement device shown in fig. 3 in that the holding device 29 is fixed to the bending arm 16 and is thus guided jointly when adjusting the height 8 of the roll gap 7.

Fig. 7 shows an alternative embodiment for guiding the bending arm 16 in the rolling stand. The bending arm 16 is provided on its side facing the cross beam of the roller housing 31 with a guide groove 38, which surrounds a corresponding guide contour 39 of the cross beam of the roller housing 31.

List of reference numerals

1 Rolling device 22 piston

2 Axis of the work rolls of the roll stand 23

3 Lower work roll 24 holding arm

4 Upper working roll 25 support

5 Lower support roller 26 bearing

6 Upper support roller 27 cylinder shell

7 Roll gap 28 upper roll adjusting device

Height (size) 29 lateral holding device of 8 roll gaps

9 Extension of the bending arm of the backup roll mount 30

10 Support roller mounting 31 roller frame

11 Work roll mount 32 window

Balance arm of support roller on 12 work roller mounting piece 33

13 Bending block 34 transverse body

14 Grooves of the lateral body of the bending cylinder 35 of the lower work roll

15 Bending cylinder 36 roll stand groove of working roll

16 Curved arm 37 shoulder

Thickening 38 guide groove of 17 bending arm

18 Guide elements 39 guide the profile

19 Piston cylinder system 100 rolling plant

20 Piston cylinder system 101 feeding roller way

21 Axial shift 102 upsetting machine frame

103 Exit roller way 104 pre-straightening machine

105 Hot straightener

Claims (11)

1. A method for hot rolling a metal rolled stock, the method using at least one rolling device, wherein the method comprises providing as rolled stock a semifinished product having a thickness of greater than or equal to 150mm, wherein the rolled stock is rolled from a first large starting cross section into a relatively smaller target cross section by gradual thickness reduction, characterized in that the thickness reduction from the starting cross section to the target cross section is achieved by means of only a single rolling device or by means of a plurality of similar rolling devices of a single rolling stand type.

2. A method according to claim 1, characterized in that the semifinished product obtained by ingot casting or continuous casting is provided as a rolled stock in the form of a slab having a thickness of 550mm or more.

3. Method according to claim 1 or 2, characterized in that the thickness reduction from the start-rolled cross section up to the target cross section is achieved in a single heating of the rolled stock.

4. A method according to any one of claims 1-3, characterized in that the method uses only a rolling device with a work roll axial displacement and bending device, preferably with a work roll pair comprising a roll crown, particularly preferably with a roll shape of S-grinding.

5. Method according to any one of claims 1 to 4, characterized in that the method uses a rolling device with a maximum roll lift of at least 900mm, preferably at least 1000 mm.

6. Method according to any one of claims 1 to 5, characterized in that the ratio of the initial thickness of the initial cross section of the rolled stock to the target thickness of the target cross section of the rolled stock is between 2 and 5, preferably between 2 and 3.

7. Method according to any one of claims 1 to 6, characterized in that the method uses at least one rolling device (1) with at least one upper working roll (4) and lower working roll (3) and with at least one upper support roll (6) and lower support roll (5), wherein the working rolls (3, 4) and the support rolls (5, 6) are supported in a common rolling stand (2), the working rolls (3, 4) being adjustable relative to each other to set a predetermined roll gap (7), and the working rolls (3, 4) being operatively connected with at least one bending device respectively, wherein the upper working roll (4) is assigned at least one first bending device and the lower working roll (3) is assigned at least one second bending device, the second bending device comprising bending cylinders (14) which are arranged fixedly in the vertical direction and by means of which the upper working rolls (4) can be bent in the vertical direction by means of the first bending devices with the bending arms (7) or the bending cylinders (8) are arranged fixedly in the axial direction, wherein the bending cylinders (16) are jointly settable and wherein the bending cylinders (8) are arranged in the axial direction.

8. Method according to claim 7, characterized in that the bending arm (16) of the first bending device brings the upper work roll (4) during the adjustment of the height (8) of the roll gap (7).

9. Hot rolling plant, preferably for carrying out the method according to any one of claims 1 to 8, characterized in that it has a single rolling device or a plurality of similar rolling devices of a single rolling stand type, which are preferably arranged directly one after the other along a rolling line, wherein the rolling line is formed by only similar rolling devices of a single rolling stand type.

10. Hot rolling plant according to claim 9, characterized in that the rolling means in the pass line comprise at least one rolling means with a work roll axial displacement and bending device, preferably with a work roll pair comprising a roll crown, particularly preferably with a roll shape of S-grinding.

11. Hot rolling plant according to claim 9 or 10, characterized in that the hot rolling plant comprises at least one rolling device (1) with at least one upper working roll (4) and lower working roll (3) and with at least one upper support roll (6) and lower support roll (5), wherein the working rolls (3, 4) and the support rolls (5, 6) are supported in a common roll stand (2), the working rolls (3, 4) being adjustable relative to each other to set a predetermined roll gap (7), and the working rolls (3, 4) being operatively connected with at least one bending device respectively, wherein the upper working roll (4) is assigned at least one first bending device and the lower working roll (3) is assigned at least one second bending device, the second bending device comprising bending cylinders (14) which are arranged fixedly in the vertical direction and by means of which the upper working rolls (4) can be set with the bending arms (8) in the vertical direction and wherein the bending cylinders (16) are arranged fixedly in the vertical direction and wherein the bending arms (15) are jointly adjustable.