WIPERING DEVICE

Description

[0001] The invention relates to a stripping device for applying a coolant to the surface of a work roll in a rolling mill and for separating the rolled material from the coolant that would otherwise flow off the work roll. Furthermore, the invention relates to a system comprising the stripping device according to the invention, an adjusting device for positioning the stripping device against the work roll, and a rolling mill with said system. Finally, the invention also relates to a method for operating said system.

[0002] Particularly during the hot rolling of metallic rolled stock, a significant heat flow is introduced into the work rolls of the rolling stand by the hot stock itself and the forming work performed during the hot rolling process, thus heating them up. A certain degree of heating is even desirable for the formation of a so-called thermal crown. However, the heating must be limited to avoid exceeding the range of the useful thermal crown. Another effect of the heat input into the work roll is that the heat does not remain only on the surface of the work roll but also penetrates its interior. If the resulting temperature differences between the inside and outside of the roll are too great, cracks can form, and subsequently, spalling can occur.Therefore, the use of a roller cooling system is being pursued, which starts immediately after the rolled material leaves the contact area with the work roller during rolling.

[0003] European patent application EP 0 662 359 A1 discloses a stripping device with an internal cooling channel opening into a nozzle for applying a fluid, in this case air, to the surface of a work roll at the exit of a rolling mill stand. The function of this stripping device is based on the Prandtl-Meyer phenomenon, which occurs at extremely high air velocities, approximately the speed of sound, causing an injector-like outlet of air to create a vacuum. The stripping device is not intended for direct contact with the surface of the work roll; rather, a small gap remains between the surface of the work roll and the tip of the stripping device.

[0004] Operating this stripping device with coolant water instead of air would deviate from the operating principle provided for in the prior art. Furthermore, simply transferring the design principle would result in the remaining gap having the disadvantage that at least some residual water would flow through this gap onto the surface of the rolled material; this is undesirable. In addition, the stripping device disclosed in the aforementioned European patent application, if operated with liquid coolant, would have the disadvantage that a pool of coolant would form above the stripping device. This pool would remain stagnant in the wedge-shaped area between the stripping device and the outer surface of the work roll and would heat up there as a so-called dead water zone.To prevent the two aforementioned disadvantages and to cool the roller as soon as possible after contact with the rolled material, it is already known in the prior art to position scraping devices against the surface of the roller.

[0005] However, this positioning has the disadvantage that the wiper tip and the curved flow guide surface, which together form the slot nozzle in EP 0 662 359 A1, are then subject to wear due to abrasion. The consequence of this abrasion of the curved flow guide surfaces would be a change in the geometry of the slot nozzle outlet, which would lead to an uncontrolled release of the high-energy airflow from the slot nozzle.

[0006] German patent application DE 10 2011 084 735 A1 relates to a stripper for a work roll of a rolling mill, wherein the stripper has a stripper tip for contacting the work roll. A first shielding element is provided to shield the annealed rolled material from cooling water. A second shielding element is provided to shield the first shielding element from thermal stress caused by the rolled material. The coolant is sprayed onto the work roll by means of a cooling water spray device.

[0007] German patent application DE 1 139 460 A discloses a scraper device for applying a liquid coolant to the surface of a work roll of a rolling mill according to the preamble of claim 1.

[0008] The invention is based on the objective of further developing a known stripping device with a cooling channel for applying a liquid coolant to the work roll, a known system consisting of the known stripping device and an adjustment device, a known rolling stand with the system, and a method for operating the system in such a way that the aforementioned disadvantage of an undesirable change in the geometry of the nozzle outlet opening when the stripping device is adjusted against the surface of the work roll is effectively prevented and that the cooling water supplied to the area of ​​the nozzle outlet opening is distributed uniformly.

[0009] This problem is solved with respect to the scraping device by the subject matter of claim 1.

[0010] The terms "below" and "above" refer to the arrangement of the scraper device according to the invention in space as shown in the figures.

[0011] When the stripper device is positioned against the surface of the work roll, the stripper tip and the gap nozzle are subject to abrasion in the area of ​​the wear length 1, particularly during hot rolling. The claimed parallel design and arrangement of the upper and lower flow guide surfaces to each other advantageously ensures that the cross-section of the gap nozzle remains geometrically unchanged over the wear length, even when the stripper device is positioned against a work roll and the gap nozzle is thereby worn down and increasingly shortened at its cooling water outlet end due to the positioning. Therefore, the cooling of the work roll and the cooling efficiency are not negatively affected when using the gap nozzle according to the invention, advantageously even in the case of its wear. The cooling efficiency is also comparatively high because the distance between the front end of the stripper tip and the gap nozzle is relatively small.The surface area of ​​the work roll and the outlet opening of the gap die are only small. This applies equally to an upper and a lower work roll in the rolling stand.

[0012] According to the invention, a separating plate is arranged between the upper and lower flow guide surfaces. This separating plate is designed in the form of a comb with teeth, the teeth of which are oriented towards the outlet opening of the slotted nozzle. At least some of the spaces between the teeth are in fluid-conducting communication with the cooling channel, in particular with the collecting chamber for the coolant. The thickness of the separating plate determines the height of the slotted nozzle and thus also the size of the opening cross-section of the slotted nozzle. Due to the elongated extension of the teeth in the depth direction, the spaces between the teeth are also elongated. By supplying the coolant, preferably at the base of the teeth, into these spaces, the coolant is advantageously aligned by the teeth for a perpendicular exit from the slotted nozzle even before it exits.At the same time, the separating plate, in combination with the upstream collection chamber, ensures an even distribution of the supplied cooling water into the area of ​​the outlet opening of the slot nozzle.

[0013] In principle, the two preferably parallel flow guide surfaces – even in the present invention – can be uneven, e.g., corrugated. However, in that case, the exit angle at which the cooling medium exits the nozzle would change depending on the wear-related material loss of the nozzle. According to a first embodiment, it is therefore advantageous if the two flow guide surfaces are not only parallel but also planar. Then the exit angle advantageously remains constant regardless of the extent of material loss in the nozzle.

[0014] According to a further embodiment, a nozzle cover plate, the underside of which forms the upper flow guide surface of the slot nozzle, and / or the wiper tip are each detachably attached to the base body as wear parts. In case of wear, they can then advantageously be easily separated from the base body and inexpensively replaced with corresponding new parts.

[0015] The nozzle cover plate is made of a softer material than the wiper tip. This ensures that the coolant continues to flow even if the wiper tip wears down, as a flow can always be directed onto the roller surface.

[0016] If a collection chamber for the coolant is formed in the wiper device upstream of the slot nozzle, this has the advantage that the coolant is distributed evenly over the entire width of the upstream collection chamber, preferably over the entire width of the slot nozzle, when exiting the slot nozzle, and exits the slot nozzle evenly, i.e. with the same pressure or the same volume flow across the width.

[0017] According to a further embodiment, the collection chamber is divided widthwise into a plurality of zones, which can be individually activated or deactivated to control the flow of coolant through the slot nozzle, depending on the specific requirements. Preferably, each zone also has its own individual connections for supplying the coolant. The individual and / or group control of the coolant supply in the individual zones advantageously allows the cooling capacity of the scraper device to be adjusted zone by zone and, optionally, also in terms of quantity across the width.

[0018] The previously mentioned optional zone configuration within the nozzle can be achieved either by means of appropriate blocking elements within the collection chamber or, alternatively, by a suitable design of the separating plate. The tines, with their respective gaps, are then only required in the width of the nozzle that is intended to be open for coolant flow. In the adjacent widths of the nozzle, which are to be blocked from coolant passage, this can be accomplished by designing the separating plate without tines. The separating plate then acts as a seal for the collection chamber across the desired widths. The separating plate covers or closes the openings of the cooling channel between the tines, preventing any coolant from passing through.

[0019] With regard to the said system, the above-mentioned problem of the invention is solved by the subject matter of claim 9.

[0020] With regard to the rolling mill, the above-mentioned problem of the invention is solved by the subject matter of claim 10.

[0021] The advantages of the claimed system and the claimed rolling stand correspond to the advantages mentioned above with reference to the claimed stripping device. In addition to the stripping device, the system and the rolling stand each also include an adjusting device for positioning the stripping device against an upper and / or lower work roll. The stripping devices are then arranged above and / or below the rolled material and thus advantageously prevent, at least to a large extent, contact between the top and / or bottom of the rolled material and the coolant applied to the work roll by the stripping device. An adjusting device is not necessarily required on the underside, because it may be sufficient for the lower stripping device to be positioned against the lower work roll by the force of gravity.

[0022] The claimed rolling mill stand can include a control device or a regulating device for controlling or regulating the actual thermal crown of the work rolls to a predetermined target crown, the actual flatness of the rolled material to a predetermined target flatness, and / or the actual profile of the rolled material to a predetermined target profile. The stripping device according to the invention then serves as an actuator in conjunction with a coolant valve, preferably controllable by the control device or the regulating device. With the aid of the adjusting device, the stripping device is positioned against the surface of the work roll, and with the aid of the valve, the speed at which the coolant exits the nozzle is varied such that the aforementioned actual values ​​can be converted to the aforementioned target values.Alternatively or additionally, the zones within the scraper device can also be individually activated or deactivated for the aforementioned purpose.

[0023] The aforementioned problem is ultimately solved by the method according to claim 12 for operating the system according to the invention. The advantages of this method correspond to the advantages previously mentioned with regard to the said control or regulating devices.

[0024] The description includes 4 figures, whereby Figure 1 shows the stripping device according to the invention in a longitudinal section; Figure 2 shows the stripping device according to the invention in an open state in a perspective top view; Figure 3 shows the individual components of the gap nozzle according to the invention in an exploded view; and Figure 4 shows the stripping device according to the invention with an associated adjusting device in a rolling mill stand. shows.

[0025] The invention is described in detail below with reference to the figures mentioned, in the form of exemplary embodiments. In all figures, identical technical elements are designated by the same reference numerals.

[0026] Figure 1 Figure 1 shows the stripping device 100 according to the invention in a longitudinal section. The stripping device 100 serves to apply a coolant to the surface of a work roll of a rolling mill and to seal off a rolled stock from the coolant after it has been rolled with the aid of the work roll. The stripping device 100 has a stripper tip 110 and a base body 120 as a carrier for the stripper tip 110. The base body has a cooling channel 122 for the coolant inside it. The cooling channel 122 connects at least one port 130-i with i = 1-I to I ∈ ℕ fluid-conducting with a gap nozzle 140 at the stripper tip 110. The outlet opening of the gap nozzle 140 is set back in the depth direction y relative to the front end 112 of the stripper tip. The cooling channel 122 is bounded within the gap nozzle by an upper flow guide surface 142 and a lower flow guide surface 144. The lower flow guide surface 144 is advantageously formed by the upper surface of the stripper tip 110, while the upper flow guide surface 142 is formed by the underside of a nozzle cover plate 146. The nozzle cover plate 146 can also be considered part of the stripper tip 110. When the stripper device 100 is engaged during operation of the rolling stand against a work roll 210, the stripper tip 110 is subject to the gap nozzle 140, i.e., in particular, the

[0027] Nozzle cover plate 146 is subject to wear due to abrasion. This potential wear area is located in Figure 1Marked with the reference number 180, hatched. The in Figure 1 The solid line indicates the initial state of the work roll 210, in which the work roll is positioned against the front end 112 of the still unused scraper tip 110. In contrast, the dashed line shows the position of the work roll 210 after wear has begun.

[0028] To ensure that the aforementioned abrasion and wear of the slot nozzle 140 does not lead to an undesirable change in the geometry of the outlet opening of the slot nozzle and thus to an uncontrolled outflow of water from the slot nozzle, the upper and the lower flow guide surfaces 142, 144 of the slot nozzle 140 according to the invention - starting from the outlet opening of the slot nozzle 140 for the coolant - are aligned parallel to each other in the depth direction y over at least a predetermined wear length I of the slot nozzle.

[0029] Additionally, the lower and upper flow guide surfaces 144, 142 can also be planar or flat, as shown in Figure 1 shown. In contrast to a non-planar design of the flow guide surfaces, which is also possible in principle, their planar design offers the advantage that the flow angle at which the coolant hits the surface of the work roll remains constant with a constant angle of attack of the scraper device 100 against the work roll 210, even with continuous wear of the gap nozzle 140.

[0030] In particular, the nozzle cover plate 146 and / or the wiper tip 110 are advantageously detachably attached to the base body 120 as wear parts.

[0031] In Figure 1It can further be seen that the cooling channel 122 has a collecting chamber 125 for the coolant, located upstream of the slot nozzle 140 against the flow direction -y of the coolant, and which preferably extends in the width direction x over the entire width of the slot nozzle 140. The collecting chamber 125 is in Figure 1 covered with a cover plate 126.

[0032] Figure 2 Figure 1 shows the inventive scraper device 100 in the open state in a perspective view. The scraper device is in Figure 2 in particular opened insofar as the cover plate 126 for the collection chamber and the nozzle cover plate 146 of the slot nozzle 140 were removed. While Figure 1 only the front part of the scraper device 100 up to the collection chamber 125 has been shown in a longitudinal section, shows Figure 2also rear areas of the base body 120 with the connections 130 for supplying the coolant. It can be seen that each of the connections 130 for supplying the coolant has its own channels, which lead into the collection chamber 125. The collection chamber 125 is located above the in Figure 2 The coolant flows through the visible slots 159 and via the opening 158 of the cooling channels in fluid-conducting connection with the spaces between each pair of adjacent tines 155 of the separating plate 150. The thickness of the separating plate 150 in the z-direction simultaneously defines the height of the opening of the gap nozzle 140 and thus also determines the size of the opening cross-section of the gap nozzle 140. The coolant is conveyed through the tines 155, as described in Figure 2 As indicated by the arrows, the material is directed evenly and in a straight line parallel to its longitudinal extent out of the wiper nozzle.

[0033] The scraper device 100 according to the invention can be subdivided into individual zones Z1...Z4 in the lateral direction x. The subdivision into zones is optional and can be achieved, for example, by providing optional separating bars 127 within the collection chamber 125. Preferably, each zone is then assigned its own connection 130-i for supplying the coolant. Alternatively or additionally to providing the bars 127, the formation of individual zones within the gap nozzle 140 can also be achieved by the separating plate 150 being formed with the aforementioned prongs 155 only in the desired zones. In the remaining areas in the lateral direction, where no zone or coolant discharge is desired, this can also be achieved by the separating plate 150 being designed in these lateral areas to cover the openings 158.This would then prevent the coolant from escaping through these openings 158 in the respective width ranges.

[0034] Figure 3 Figure 1 shows the structure of the inventive gap nozzle 140 again in an exploded view. The underside forms the wiper tip 110 with the aforementioned openings 158 as fluid-conducting connections between the collecting chamber 125 and the spaces between the tines 155 of the separating plate 150. The upper side of the wiper tip 110 forms the aforementioned lower flow guide surface 144 of the gap nozzle. The opposite upper control guide surface 142 is formed by the underside of the nozzle cover plate 146. Finally, the wiper tip 110, the separating plate 150, and the nozzle cover plate 146 are screwed together via a cover plate 148.

[0035] Figure 4Figure 1 shows a rolling mill 200 with an upper and a lower work roll 210 for rolling material. Preferably, at the exit of the rolling mill 200, the stripping device 100 according to the invention is positioned against the upper work roll 210 by means of an upper positioning device, for example a cylinder 160.

[0036] Alternatively or additionally to the upper stripper device 100, a lower stripper device 100 can also be provided for positioning against the lower work roll 210 of the rolling stand 200. Positioning the lower stripper device 100 does not necessarily require a lower positioning device; alternatively, the lower stripper device can also be positioned simply by utilizing the force of gravity. The rolling stand 200 advantageously has a control device or a regulating device 220 for controlling or regulating, for example, the actual thermal crown of the work rolls 210 to a predetermined target crown, the actual flatness of the rolled material to a predetermined target flatness, and / or the actual profile of the rolled material to a predetermined target profile.The lower and / or upper wiper device 100 according to the invention, in conjunction with a valve for the coolant that can be controlled by the control device or the regulating device, serves as an actuator. The valve is used to vary the exit velocity at which the coolant exits the nozzle 140 of the respective wiper device 100 in such a way that the actual values ​​are adjusted or regulated to the predetermined target values. As described above, the actuator is also suitable for controlling the coolant exit zone by zone in the lateral direction x.

[0037] The scraping device 100, in conjunction with the adjusting device 160, forms the system according to the invention.

[0038] The inventive method for operating the inventive system comprises in particular the following steps: The stripper device 100 is positioned against the work roll 210 in a rolling stand 200 such that the stripper tip 110 and the nozzle cover plate 146 simultaneously press against the work roll 210. After positioning, coolant is optionally pumped through the at least one connection 130, through the cooling channel 112, and through the gap nozzle 140 onto the surface of the work roll 210 in the rolling stand 200. The pressure or volume flow rate at which the coolant exits the gap nozzle 140 is then varied by means of the aforementioned valve, controlled by the control device or regulating device 220, such that at least one of the above-mentioned actual values ​​is adjusted or regulated to the corresponding predetermined setpoint values. According to the invention, the coolant is a cooling fluid, in particular water.

[0039] The pumping of the coolant can be switched on or off; i.e., in certain operating conditions it may be advantageous to position the scraper device 100 according to the invention against the surface of a work roll 210 even without coolant escaping. Reference symbol list

[0040] 100 Scraper device 110 Scraper tip 112 Front end of scraper tip 120 Base body 122 Cooling channel 125 Collection chamber 126 Collection chamber cover plate 127 Dividing bars (optional) 130 Coolant supply connection 140 Slotted nozzle 142 Upper flow guide surface 144 Lower flow guide surface 146 Nozzle cover plate 148 End plate 150 Dividing plate 155 Tines 158 Cooling channel openings between 2 tines 160 Adjustment device 180 Wear area 200 Rolling stand 210 Work roll 220 Control device Wear length x Width direction y Depth direction -y Coolant flow direction z Height direction Z1, Z2, Z3, Z4 individual zones

Claims

1. Scraper device (100) for application of a liquid coolant to the surface of a work roll (210) of a roll stand (200) and for screening a rolling material, which is rolled with the help of the work roll, from coolant flowing down from the work roll, comprising - a scraper tip (110); and - a base body (120) as carrier of the scraper tip (110), wherein the base body (120) has in the interior thereof a cooling channel (122) for the coolant and for fluid-conducting connection of at least one connection (130) for feed of the coolant, with a nozzle, which is formed at the scraper tip (110), for application of the coolant to the work roll (210), wherein the nozzle is set back in depth direction (y) relative to the front end (112) of the scraper tip (110), wherein the cooling channel (122) is bounded within the nozzle by an upper flow guide surface (142) and a lower flow guide surface (144), wherein the upper and lower flow guide surfaces (142, 144) are formed convergently or divergently relative to one another, preferably extending parallelly to one another, at least over a predetermined wear length (I) of the slot nozzle (140) in depth direction (y) at an angle of less than 15° in flow direction of the coolant; characterised in that the nozzle is a slot nozzle (140); and a separating plate (150), which is configured in the form of a comb with tines (155) oriented towards the outlet opening of the slot nozzle (140), is arranged between the lower and upper flow guide surfaces (142, 144), wherein at least individual ones of the openings (158) between the tines (155) are in fluid-conducting connection with the cooling channel (122) for the coolant.

2. Scraper device (100) according to claim 1, characterised in that the upper and lower flow guide surfaces (142, 144) are each formed to be flat.

3. Scraper device (100) according to one of the preceding claims, characterised in that the upper flow guide surface (142) is formed by the lower side of a nozzle cover plate (146) and the lower flow guide surface (144) by the upper side of the scraper tip (110).

4. Scraper device (100) according to any one of the preceding claims, characterised in that the nozzle cover plate (146) and / or the scraper tip (110) is or are respectively detachably secured as a wear part or wear parts to the base body (120).

5. Scraper device (100) according to claim 3 or claim 4, characterised in that the nozzle cover plate (146) is made from a softer material than the scraper tip (110).

6. Scraper device (100) according to any one of the preceding claims, characterised in that the cooling channel (122) has a collecting space (125), which is upstream of the slot nozzle counter to the flow direction (-y) of the coolant and preferably extends over the entire width of the slot nozzle (140), for the coolant.

7. Scraper device (100) according to claim 6, characterised in that the collecting space (125) is subdivided in width direction (x) into a plurality of zones (Z1, Z2, Z3) which according to need in the individual case can be individually connected or blocked with respect to throughflow of coolant through the slot nozzle (140); and preferably respective individual connections (130-i) for feed of the coolant to the individual zones (Z1, Z2, Z3) are provided.

8. Scraper device (100) according to claim 7, characterised in that the tines (155) are formed at the separating plate (150) only in the at least one zone over the width of the slot nozzle, which is provided for throughflow of the coolant.

9. System comprising a scraper device (100) according to any one of the preceding claims and an adjusting device (160) for adjusting the scraper device (100) against the surface of a work roll (210) in a roll stand (200).

10. Roll stand (200) with at least one work roll (210) for the rolling of rolling material, characterised in that preferably at least one scraper device (100) according to any one of claims 1 to 8 is provided in the outlet of the roll stand; an upper adjusting device (160) is provided for adjusting the scraper device (100) against an upper work roll (210); and / or no or a lower adjusting device is provided for adjusting the scraper device (100) against a lower work roll (210).

11. Roll stand according to claim 10, characterised by a control device or regulating device (22) for control or regulation of the actual thermal cambering of the work rolls to a predetermined target cambering, the actual planarity of the rolling material to a predetermined target planarity and / or the actual profile of the rolling material to a predetermined target profile in each instance by appropriate variation of the rate at which the coolant issues from the slot nozzle (140) and / or by variation of the zones (Z1, Z2, Z3) from which the coolant issues from the slot nozzle (140), by the scraper device, preferably in conjunction with a controllable valve for the coolant, as respective setting element.

12. Method of operating the system according to claim 9 with the scraper device according to claim 7, comprising the following steps: - adjusting the scraper device against the work roll in a roll stand so that the scraper tip and the nozzle cover plate simultaneously press against the work roll; and - optionally pumping the coolant through the at least one connection (130) for feed of the coolant through the cooling channel (122) and through the slot nozzle (140) onto a work roll (210) in a roll stand (200); characterised in that the rate at which the coolant issues from the slot nozzle (140) is appropriately varied in such a way, preferably in combination with, if required, activation of at least individual zones of the slot nozzle as setting variables, that the actual thermal cambering of the work rolls is set to a predetermined target cambering, the actual planarity of the rolling material is set to a predetermined target planarity and / or the actual profile of the rolling material is set to a predetermined target profile.

13. Method according to claim 12, characterised in that the coolant is at least substantially water.

14. Method according to claim 12 or 13, characterised in that pumping of the coolant can be regulated in rotational speed and / or switched on or off.