Roller cooling

Abstract

The present invention relates to a roller (1) for metal transport, a system (30) for processing metal, and a method (100) for cooling a roller (1) for metal transport. The roller (1) for metal transport comprises: i) a shaft (2) which is rotatably mounted at its two opposing shaft ends (2a, 2b); ii) a coolant guide (6) wound helically around the shaft (2); and iii) a jacket (4) encompassing the coolant guide (6) completely, such that the coolant guide (6) is arranged between the shaft (2) and the jacket (4). The coolant guide (6) is designed such that the flow characteristics (C) of a coolant flow (K) guided by the coolant guide (6) vary over a roller width (B).

Description

field of technology

[0001] The present invention relates to a roller for metal transport, a system for processing metal and a method for cooling a roller for metal transport. State of the art

[0002] In metalworking plants, metal products such as strands, slabs, billets, strips, and / or the like must be transported, for example, through or between rolling stands or rolling stand groups, descalers, edge heaters, heating devices, cutting devices, and / or the like. The metal product is typically at a high temperature to facilitate or even make processing possible. Consequently, rollers used to transport the hot metal inevitably heat up considerably as well.

[0003] High temperatures on these rollers can, however, have several disadvantages. For example, high temperatures can reduce the service life of a welded coating applied to the roller surface to reduce wear. Furthermore, the strength of the roller material can be reduced. In unfavorable cases, unwanted deformation of the rollers can also occur.

[0004] Therefore, rollers used in such systems are typically cooled to reduce their surface temperature. Several approaches are known for this purpose. For example, a bore can be provided along the roller axis through which a coolant flows. To dissipate the heat immediately after it is transferred to the roller, an annular gap through which the coolant flows can also be provided beneath the roller shell, i.e., below the roller surface. So-called spiral cooling systems have proven even more effective, in which the coolant is guided in a helical pattern beneath the roller shell from one end of the roller to the other.

[0005] However, even with such cooling, inhomogeneous temperature distributions across the roll width, i.e., along the roll axis, cannot be ruled out. Due to increased contraction pressure in the roll center, heat transfer from the metal product to the roll is often better there than at the roll ends. This can lead to higher temperatures in the roll center, which, due to the associated greater thermal expansion, can cause radial bulges ("ridges") in the roll center. These bulges can press into the metal product and thus adversely or unintentionally affect its contour. The effects of such deformed rolls on, for example, a metal strip, can still be measurable on the strip surface even after a rolling process in a finishing mill and thus negatively impact the strip's quality. Summary of the invention

[0006] Against this background, it is an object of the present invention to improve roll cooling, in particular to provide a roll cooling system with which a uniform temperature distribution over the roll width can be achieved and thus local expansions can be avoided.

[0007] This problem is solved by a roller for metal transport, a plant for processing metal and a method for cooling a roller for metal transport according to the independent claims.

[0008] Preferred embodiments are the subject of the dependent claims and the following description.

[0009] According to a first aspect of the invention, the roller for metal transport, in particular for strand transport, slab transport and / or strip transport, comprises: i) a shaft which is rotatably mounted at the two opposing shaft ends; ii) a coolant guide wound helically around the shaft; and iii) a jacket encompassing the coolant guide completely, such that the coolant guide is arranged, in particular radially, between the shaft and the jacket. The coolant guide is designed such that the flow characteristics of a coolant flow guided by the coolant guide, in particular from one roller end to the opposite roller end, vary across the roller width.

[0010] A roll width within the meaning of the invention is preferably an axial extent of the roll. The roll width can also be referred to as the roll length. The roll width or roll length can be understood as the length of the roll measured in the axial direction. Preferably, the roll width or roll length is determined by the outer layer, i.e., the axial extent of the outer layer.

[0011] A flow characteristic within the meaning of the invention is preferably a parameter characterizing the flow of the coolant. A flow characteristic can, for example, be a coolant pressure, a flow velocity, a degree of turbulence, and / or the like.

[0012] One aspect of the invention is based on the approach of guiding a coolant non-uniformly through a roller to be cooled, thereby intensifying the removal of heat absorbed by the roller in at least one section of the roller. For example, heat can be selectively removed from a predetermined section of the roller, such as the center of the roller.

[0013] For this purpose, the coolant flow path around the roller is preferably designed such that the flow characteristics of the coolant vary across the roller width. This varying flow characteristic allows the cooling capacity to be varied across the roller width, meaning that different sections of the roller can be cooled to varying degrees. For example, more heat per unit of time can be absorbed by the coolant in one roller section than in another. Such cooling can also be referred to as "zone cooling." This effectively counteracts the deformations of the roller that typically occur due to the inevitable heating of the roller upon contact with the transported metal product, such as freshly rolled metal strip. Depending on the specific design of the coolant flow path, this can, for example, prevent bulging, i.e.,a radial, thermally induced widening of the roller in the center of the roller is suppressed or at least reduced.

[0014] The coolant flow is advantageously designed such that the coolant flow is guided between a shaft and a shell of the roller. For example, the coolant flow can be designed such that the coolant flow is guided in a helical or spiral shape around the shaft. The coolant flow is advantageously designed in such a way that the flow characteristics of the coolant flow change at least once along its path through the roller, particularly in a predetermined section of the roller.

[0015] Preferred embodiments of the invention and their further developments are described below. These embodiments and further developments can each be combined with one another and with the aspects of the invention described below, unless expressly excluded.

[0016] In a preferred embodiment, the coolant flow defines a coolant channel. The coolant channel can have an angular, in particular rectangular, e.g., square, round, or other cross-section. Preferably, the cross-section of this coolant channel varies across the roll width. The coolant channel can therefore narrow or widen, particularly in sections. This allows zones or sections with higher or lower flow velocities to be created. In particular, the flow velocity of the coolant can thus be locally controlled. In one or more predetermined sections, more heat can be dissipated per unit of time, and consequently, the cooling capacity can be locally increased.

[0017] In another preferred embodiment, the pitch of the coolant guide, which is helically wound around the shaft, varies across the roll width. The coolant guide can, for example, comprise or be formed by a web that helically winds around the shaft. The resulting spiral is advantageously covered by the shell, thus defining a coolant channel between the shaft and the shell. The pitch of this web, which is helically wound around the shaft, can vary across the roll width.

[0018] A pitch within the meaning of the invention is preferably an axial distance, relative to the roller extension, which the coolant guide or the web travels during one turn around the shaft. The pitch can thus define the width, relative to the roller axis, of the area occupied by one turn of the coolant guide or the web around the shaft. Consequently, the pitch can also be understood as the distance between the turns of the coolant guide or the web around the shaft.

[0019] Preferably, the cross-section of the coolant channel and / or the slope of the coolant guide, in particular the web, is / are smaller in a first roller section than in at least a second section. This allows, for example, the flow velocity of the coolant to be specifically increased within the first roller section, thereby enabling more heat to be removed from the first roller section per unit of time. The first roller section can thus be cooled more effectively than the second roller section.

[0020] It is also possible to provide several first roller sections in which the cross-section of the coolant channel and / or the pitch of the coolant guide, in particular the web, is / are smaller than in at least one second roller section. In particular, several roller sections with different cross-sections and / or different pitches, and consequently different cooling capacities, can also be implemented. In this way, the cooling profile of the roller can be adapted to the respective circumstances or requirements.

[0021] In a further preferred embodiment, the cross-section of the coolant channel and / or the pitch of the coolant guide, in particular the web, is smaller in the region of the roller center than in the region of the opposing roller ends. For this purpose, the first roller section can be provided in the region of the roller center, while two second sections are located in the region of the roller ends. The first roller section can thus be arranged between two second roller sections. This allows more heat to be dissipated from the roller center per unit of time than from the region at the two roller ends. Consequently, the cooling capacity in the roller center can be specifically increased, so that radial bulging of the roller in the center, where the heat of the transported metal product is concentrated, is reliably avoided or at least reduced.

[0022] A roller center within the meaning of the invention is preferably the center of the roller with respect to its axial extent.

[0023] Advantageously, the coolant channel tapers towards the center of the roller. The coolant guide, especially the rib, can be wound more tightly around the shaft in the area of ​​the roller center than at the opposite roller ends.

[0024] Alternatively, the cross-section of the coolant channel and / or the pitch of the coolant guide, particularly the web, is larger in the area of ​​the roller center than in the area of ​​the opposing roller ends. The coolant channel can widen towards the roller center. The coolant guide, particularly the web, can be wound more tightly around the shaft in the area of ​​the two opposing roller ends than in the roller center. This makes it possible to cool the roller ends more effectively than the roller center. This can be advantageous in some applications, e.g., when using the roller in the area of ​​an edge heater.

[0025] In a further preferred embodiment, a first roller section, in which the cross-section of the coolant channel and / or the pitch of the coolant guide, in particular the web, is / are smaller than in at least one second roller section, comprises substantially 20% to 50% of the total roller width. The first roller section is preferably located in the central region of the roller. The first roller section can therefore be situated between two second roller sections. The width of the first roller section, substantially 20% to 50% of the total roller width, makes it possible to selectively dissipate heat from the area of ​​highest heat accumulation. A width of substantially 30% of the total roller width for the first roller section has proven particularly effective in preventing or at least reducing radial bulging in the center of the roller.

[0026] In a further preferred embodiment, a transition zone is provided between the first roller section and the second roller section, in which the cross-section of the coolant channel and / or the pitch of the coolant guide, in particular the web, is / are larger than in the first roller section. In the transition zone, the cross-section of the coolant channel and / or the pitch of the coolant guide, in particular the web, from the first roller section preferably gradually matches the cross-section of the coolant channel and / or the pitch of the coolant guide, in particular the web, preferably continuously. For example, the coolant channel can thus, at least in the transition zone, taper or widen increasingly towards the center of the roller, so that the flow velocity of the coolant continuously increases or decreases. This makes it possible to avoid or at least reduce turbulence that could unintentionally impair the coolant flow.Therefore, the transition zone can be conducive to laminar flow through the roller.

[0027] The roller sections can be manufactured individually and then joined, particularly connected, for example, for manufacturing reasons. This can also result in an abrupt transition between the two cross-sections of the coolant channel in the first and second roller sections, or between the gradients of the coolant guide in the first and second roller sections.

[0028] In a further preferred embodiment, the cross-section of the coolant channel and / or the pitch of the coolant guide, in particular the web, is / are substantially 40% to 70% smaller, and more specifically 45% to 60% smaller, in a first roller section than in at least a second roller section. The pitch at the edge of the roller can, for example, be 80 mm, while a pitch of 35 mm to 45 mm is provided in the roller center. The pitch in the region of the roller center (the first roller section) can therefore be approximately twice as large as in the region of the roller ends (the second roller sections). This also makes it possible to double the flow velocity of the coolant. Such reductions in cross-section or pitch have proven particularly advantageous in reducing the heat transfer coefficient from approximately 10,000 W / m²K in the region of the second roller sections to approximately 20.to be able to increase the temperature in the first roller section to 000 W / m²K. This can be advantageous in terms of a compromise between increased cooling capacity in the first roller section and the associated pressure drop in the coolant flow, which must be compensated for by pump technology.

[0029] In a further preferred embodiment, an additional coolant guide is provided, wound helically around the shaft. The coolant guide and the additional coolant guide (which can also be referred to as the first and second coolant guides) are preferably designed, and in particular wound around the shaft, such that coolant can be guided in two separate coolant flows between the jacket and the shaft. For example, the coolant guide and the additional coolant guide can be wound around the shaft in the manner of a double helix. With an additional coolant guide, even more flexible cooling is possible, in particular a flexible cooling profile across the width of the roller. If necessary, the cooling capacity can also be adjusted more precisely.

[0030] As mentioned above, the coolant flow is preferably formed by a web that runs helically around the shaft. This helical web allows for the implementation of a so-called "spiral cooling" system.

[0031] The web can be formed from a sheet of metal or wire. The web conveniently defines the walls of a coolant channel between the jacket and the shaft. The coolant can thus be guided once around the shaft between two turns of the web.

[0032] Preferably, the distance between the walls varies across the roller width. As mentioned above, this can be achieved by varying the pitch of the web across the roller width. The coolant can then flow in a spiral around the shaft and along the jacket in the space between the webs. This allows for extensive cooling of the jacket. In this way, the area over which no coolant flows can be reduced to a minimum, namely to the contact line of the web on the inside of the jacket.

[0033] According to a second aspect of the invention, a metal processing plant includes a roller according to the first aspect of the invention. The plant, for example, a casting and rolling mill, may include one or more rolling stands for rolling slabs and / or pre-rolled metal strips, for example, a roughing mill and a finishing mill. The roller may be used in such a plant as a drive roller (so-called "pinch roll"), as a guide or deflection roller, as a support or transport roller, and / or the like. In such a plant, more reliable transport of the metal product to be processed or the processed product is possible. In particular, it prevents unwanted deformations of the metal product caused by thermal deformation of a roller during transport within the plant.As a result, higher quality end products can be produced in such a plant.

[0034] According to a third aspect of the invention, in a method for cooling a roller for metal transport, particularly a roller according to the first aspect of the invention, a coolant flow is guided from one roller end to the opposite roller end by means of a coolant guide enclosed by a roller shell in a helical fashion around a shaft of the roller, such that the flow characteristics of the coolant flow vary across the roller width. Advantageously, a constant quantity of coolant is guided through the roller per unit of time. The coolant flow through the roller is thus preferably constant. Due to the varying flow characteristics of the coolant flow across the roller width, different sections or zones of the roller can be cooled to varying degrees. In this way, the cooling capacity can be specifically increased in an area that is exposed to particularly high thermal loads.This allows for a more uniform temperature across the width of the roll. In particular, radial bulging, i.e., thermal expansion, of the roll in the center area due to heat concentration there can be avoided or at least reduced.

[0035] In a preferred embodiment, the coolant flow is guided by the coolant guide such that the flow velocity of the coolant varies across the roller width. For example, the flow velocity in a first roller section can be increased compared to at least a second roller section. It can be provided, for instance, that the flow velocity in the region of the roller center is increased compared to the regions at the two opposing roller ends. This allows more heat per unit time to be carried away by the coolant in the region of the roller center, and consequently, a higher cooling capacity can be achieved in the roller center. Brief description of the drawings

[0036] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of an exemplary embodiment, which is explained in more detail in conjunction with the drawings. These drawings show: Fig. 1 is an example of a method for cooling a metal transport roller shown in cross-section, Fig. 2 is an example of a metal transport roller in a three-dimensional representation, Fig. 3 is an example of a flow characteristic, and Fig. 4 is an example of a metal processing plant.

[0037] Where appropriate, the same reference numerals are used in the figures for the same or corresponding elements of the invention. Description of the embodiments

[0038] FIG 1 Figure 100 shows a method 100 for cooling a roller 1 for metal transport, shown in cross-section and schematically. The roller 1 has a shaft 2 which is rotatably mounted at its two opposing shaft ends 2a, 2b. The shaft 2 is, at least partially, surrounded by a shell 4, which provides a contact surface for the metal product to be transported on its outer surface 4a, i.e., on the side facing away from the shaft 2. A coolant guide 6 is arranged radially between the shaft 2 and the shell 4 and is wound helically around the shaft 2. In the present example, the coolant guide 6 is formed by a web 8 which winds up the shaft 2 in an axial direction, i.e., in a direction parallel to a longitudinal axis L of the roller 1, between the two roller ends 1a, 1b (see Figure 100). FIG 2 ).

[0039] The web 8 forms the walls of a coolant channel 10, through which a coolant flow K can be guided from one roller end 1a to the other roller end 1b. The coolant channel 10 thus formed is accessible via axial bores 12a and 12b in each of the two shaft ends 2a and 2b. Coolant can be introduced through one of the axial bores 12a, which then, after flowing through the coolant channel 10, exits through the other axial bore 12b. In method 100, the coolant flow K can therefore be guided helically from one roller end 1a around the shaft 2 to the other roller end 1b by means of the coolant guide 6.

[0040] The coolant guide 6, which is wound helically around the shaft 2, is designed such that the flow characteristics of the coolant flow K around the shaft 2 vary over a width B of the roller 1. For this purpose, in the present example, the pitch of the web 8 wound helically around the shaft 2 in a first roller section 14, which is arranged in the region of the roller center M, is smaller than in a second roller section 16 at each of the two roller ends 1a, 1b.

[0041] Due to the smaller pitch of the web 8 in the first roller section 14, the number of turns per unit length (in the axial direction) is increased there. This results in the coolant channel 10 narrowing in the region of the roller center M, i.e., the cross-sectional area of ​​the coolant channel 10 in the region of the roller center M is smaller than at the two roller ends 1a, 1b. Consequently, the flow velocity of the coolant flowing through the coolant channel 10 increases.

[0042] Consequently, more heat can be dissipated per unit time in the first roller section 14 at the roller center M than in the second roller sections 16 at the two roller ends 1a, 1b. Thus, the roller 1 can be cooled more effectively in the region of the roller center M. This counteracts radial bulging of the roller 1 in the region of the roller center M, which is caused, for example, by increased heat transfer from a metal product transported by the roller 1 to the roller shell 4.

[0043] FIG 2 shows an example of roller 1 for metal transport from FIG 1 in a three-dimensional representation. Clearly visible are the shaft 2 and the coolant guide 6, which is wound helically around the shaft, at least in sections. The casing of the roller 1 is in FIG 2 not shown so that the view of the coolant guide 6 is unobstructed.

[0044] The axial extent of the shell (not shown), i.e., its extent in a direction parallel to a longitudinal axis L of the roller 1, defines the roller width B, also referred to as the roll length. The shaft 2 extends axially beyond the shell, i.e., beyond the roller width B. In particular, the shaft 2 projects from the end faces 18a, 18b of the roller 1 at the two opposite roller ends 1a, 1b. Beyond the two end faces 18a, 18b, i.e., at the shaft ends 2a, 2b defined in this way, the shaft 2 can be mounted, for example, by means of suitable bearings to allow rotation.

[0045] The coolant guide 6 extends axially between the two end faces 18a, 18b or roller ends 1a, 1b. The coolant guide 6 is helically wound around the shaft 2, so that a coolant flow is ensured over the FIG 2 The coolant flowing in and out of the roller end 2a, 2b can be guided in a spiral from one roller end 1a around the shaft 2 to the other roller end 1b via an invisible axial bore in the two shaft ends 2a, 2b. The pitch of the coolant guide 6 around the shaft 2 is not constant. In the example shown, the pitch decreases in the region of the roller center M. In particular, the pitch in a first roller section 14, which in this example is located in the region of the roller center M, is smaller than in two second roller sections 16, each of which extends from a roller end 1a, 1b to the first roller section 14. As discussed in connection with FIG 1 As described above, this can increase the cooling performance in the area of ​​the roller center M.

[0046] As in FIG 2 As is clearly visible, the coolant guide 6 in this example has a web 8 that sits on the shaft 2. The web can, for example, be formed by a sheet metal part that is welded or otherwise attached to the shaft 2. The contact line between the web 8 and the shaft 2 forms a helical or spiral line. Similarly, the contact line between the web 8 and the (not shown) outer shell also forms such a helical or spiral line. However, other configurations of the coolant guide 6 are also conceivable. For example, the coolant guide could have a tube that is wound helically around the shaft 2. Compared to such a configuration, the web 8 has the advantage that the area exposed to the coolant flow on the inner surface of the outer shell is maximized.

[0047] FIG 3 Figure 1 shows an example of a flow characteristic C, which characterizes a coolant flow guided by a coolant guide in a roller used for metal transport. The flow characteristic C comprises the flow velocity v of the flowing coolant as a function of a coordinate x on a longitudinal axis of the roller. The flow velocity v is plotted against the coordinate x over a roller width B.

[0048] How FIG 3 As can be seen, the flow characteristic C varies across the roller width B. In the present example, the flow velocity v in a first roller section 14, located in the region of a roller center M, is increased compared to the flow velocity v in two second roller sections 16 in order to ensure increased cooling capacity in the region of the roller center M. Such a sectionally increased flow velocity v can be achieved, for example, by a coolant channel within the roller whose cross-section is reduced section by section.

[0049] A transition zone 20 can be provided between the first roller section 14 and the two second roller sections 16. In the transition zones 20, the flow velocity v in the first roller section 14 can transition into the flow velocities v in the two second roller sections 16. In the present example, the flow velocity v with respect to the roller width B therefore only changes within the transition zones 20. In the first roller section 14 and the two second roller sections 16, the flow velocity v is essentially constant.

[0050] FIG 4 Figure 1 shows an example of a plant 30 for processing metal strip 32. The plant 30 shown, purely as an example, has a rolling mill with two rolling stands 34 and a cooling line 36 to reduce the thickness of the metal strip 32 and subsequently cool it. Passive transport or support rollers 38 are arranged upstream of the rolling mill, between the rolling mill and the cooling line 36, and within the cooling line 36. These rollers transport and support the metal strip 32. For clarity, only some of the transport rollers 38 are labeled. In a transport direction T downstream of the cooling line 36, two pinch rollers 1 are arranged. The metal strip 32 is clamped between these rollers, and at least one of them is driven by a motor. The pinch rollers 1 thus allow the metal strip 32 to be actively transported out of the cooling line 36, for example, to a reel.

[0051] The pressure rollers 1 are preferably as shown in FIG 1 and FIG 2 The pressure rollers 1 are preferably zone-cooled rollers 1, such as those shown in FIG 1 or 2 are shown in which the flow characteristics of a coolant flow vary across a roller width.

[0052] Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without leaving the scope of protection of the invention. Reference symbol list

[0053] 1 Roller 1a, 1b Roller end 2 Shaft 2a, 2b Shaft end 4 Shell 4a Shell outer side 6 Coolant guide 8 Web 10 Coolant channel 12a, 12b Axial bore 14 First roller section 16 Second roller section 18a, 18b End face 20 Transition area 30 Plant 32 Metal strip 34 Rolling mill 36 Cooling line 38 Transport roller 100 procedures BRollenbreite MRollenmitte KKooling flow CSlowflow characteristic vflow velocity xcoordinate LLlongitudinal axis Ttransport direction

Claims

1. Roller (1) for metal transport, comprising - a shaft (2) which is rotatably mounted at the two opposing shaft ends (2a, 2b), - a coolant guide (6) wound helically around the shaft (2), - a jacket (4) encompassing the coolant guide (6) completely, such that the coolant guide (6) is arranged between the shaft (2) and the jacket (4), wherein the coolant guide (6) is designed such that a flow characteristic (C) of a coolant flow (K) guided by the coolant guide (6) varies over a roller width (B).

2. Roller (1) according to claim 1, wherein the coolant guide (6) defines a coolant channel (10) whose cross-section varies over the roller width (B).

3. Roller (1) according to claim 1 or 2, wherein a pitch with which the coolant guide (6) is wound helically around the shaft (2) varies over the roller width (B).

4. Roller (1) according to one of claims 2 or 3, wherein the cross-section of the coolant channel (10) and / or the slope of the coolant guide (6) in the region of a roller center (M) is / are smaller than in the region of opposing roller ends (1a, 1b).

5. Roller (1) according to one of claims 2 or 3, wherein the cross-section of the coolant channel (10) and / or the slope of the coolant guide (6) in the area of ​​the roller center (M) is / are larger than in the area of ​​the opposing roller ends (1a, 1b).

6. Roller (1) according to one of claims 2 to 5, wherein a first roller section (14), in which the cross-section of the coolant channel (10) and / or the slope of the coolant guide (6) is / are smaller than in at least a second roller section (16), is substantially 20% to 50%, preferably about 30%, of the total roller width (B).

7. Roller (1) according to one of claims 2 to 6, wherein a transition area (20) is provided between a first roller section (14) and a second roller section (16) in which the cross-section of the coolant channel (10) and / or the slope of the coolant guide (6) is / are larger than in the first roller section (14), in which the cross-section of the coolant channel (10) and / or the slope of the coolant guide (6) from the first roller section (14) is / are adapted to the cross-section of the coolant channel (10) and / or the slope of the coolant guide (6).

8. Roller (1) according to one of claims 2 to 7, wherein the cross-section of the coolant channel (10) and / or the slope of the coolant guide (6) in a first roller section (14) is / are substantially 40% to 70% smaller, in particular substantially 45% to 60% smaller, than in at least a second roller section (16).

9. Roller (1) according to one of the preceding claims, with a further coolant guide wound helically around the shaft, wherein the coolant guide (6) and the further coolant guide are designed such that coolant can be guided in two separate coolant flows (K) between shell (4) and shaft (2).

10. Roller (1) according to one of the preceding claims, wherein the coolant guide (6) is formed by a web (8) extending helically around the shaft (2), which defines the walls of a coolant channel (10) between the shell (4) and the shaft (2), wherein the distance between the walls varies over the roller width (B).

11. Plant (30) for processing metal, comprising a roller (1) according to one of the preceding claims.

12. Method (100) for cooling a roller (1) for metal transport, in particular a roller (1) according to one of claims 1 to 10, wherein a coolant flow (K) from a roller end (1a) is guided helically around a shaft (2) of the roller (1) to the opposite roller end (1b) by means of a coolant guide (6) such that a flow characteristic (C) of the coolant flow (K) varies over the roller width (B).

13. Method (100) according to claim 12, wherein the coolant flow (K) is guided by means of the coolant guide (6) such that the flow velocity (v) of the coolant varies over the roller width (B).

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