Scraping device

Abstract

The invention relates to a scraping device (100) for applying a coolant onto the surface of a working roll in a roll stand (200) and for partitioning the material being rolled by means of the working roll from the coolant flowing from the working roll. The scraping device (100) has a scraper tip (110) and a main part (120) as a support for the scraper tip. The main part is equipped with a cooling channel (120) which is designed to supply a coolant to a slot nozzle which is formed on the scraper tip (110). In order to prevent the geometry of the outlet opening of the slot nozzle from changing in an undesired manner when the scraping device (100) is engaged against the surface of a working roll (210), the upper and lower flow guide surfaces of the slot nozzle (140) are designed to run preferably parallel to each other in the depth direction (y) at least over a specified wear length.

Description

[0001] Scraper device

[0002] The invention relates to a stripping device for applying a coolant to the surface of a work roll in a rolling stand and for shielding a rolled stock rolled by the work roll from the coolant that would otherwise flow down from the work roll. Furthermore, the invention relates to a system comprising the stripping device according to the invention and an adjusting device for adjusting the stripping device against the work roll, and to a rolling stand with said system. Finally, the invention also relates to a method for operating said system.

[0003] Particularly during the hot rolling of metallic rolled stock, a considerable heat flow is introduced into the work rolls of the rolling stand by the hot rolled stock and the forming work performed during hot rolling, which heats them up. A certain amount of heating is actually desirable to form a so-called thermal crown. However, the heating must be kept limited in order not to exceed the range of the sensible thermal crown. A further effect of the introduction of heat into the work roll is the fact that the heat not only remains on the surface of the work roll, but also penetrates into the interior of the work roll. If the resulting temperature differences between the interior and exterior of the roll are too great, this can lead to the formation of cracks and, as a result, even to chipping.In this respect, the aim is to use a roll cooling system that starts immediately after the rolling stock leaves the contact area with the work roll during rolling.

[0004] European patent application EP 0 662 359 A1 discloses a stripping device with an internal cooling channel that opens into a gap nozzle for applying a fluid, in this case air, to the surface of a work roll at the exit of a rolling stand. The function of this stripping device is based on the Prandtl-Meyer corner flow phenomenon, a phenomenon that occurs at extremely high air velocities, approximately the speed of sound, so that an injector-like discharge of air creates a vacuum. The stripping device is not intended for direct application to the surface of the work roll; rather, a gap, albeit a small one, remains between the surface of the work roll and the tip of the stripping device.

[0005] If this stripping device were operated with coolant water instead of air, the operating principle provided by the prior art would be abandoned. Furthermore, if the design principle were simply applied, the remaining gap would have the disadvantage that at least a residual amount of water would flow through this gap onto the surface of the rolled stock; this is undesirable. Furthermore, if the stripping device disclosed in the aforementioned European patent application were operated with liquid coolant, it would have the disadvantage that a pool of cooling water would form above the stripping device. This pool would remain motionless in the wedge-shaped area between the stripping device and the outer surface of the work roll and would heat up there, forming a so-called dead water zone.In order to prevent the two disadvantages mentioned above and to cool the roll as early as possible after contact with the rolling stock, it is already known in the prior art to place scraper devices against the surface of the roll.

[0006] However, this adjustment has the disadvantage that the wiper tip and the curved flow guide surface, which together form the slotted nozzle in EP 0 662 359 A1, are 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 slotted nozzle outlet, which would lead to an uncontrolled discharge of the high-energy air flow from the slotted nozzle.The invention is based on the object of 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 adjusting device, a known rolling stand with the system and a method for operating the system in such a way that the said disadvantage of an undesirable change in the geometry of the outlet opening of the gap nozzle when the stripping device is adjusted against the surface of the work roll is effectively prevented.

[0007] This object is achieved with regard to the stripping device by the subject matter of patent claim 1. Accordingly, the stripping device according to the invention is characterized in that the upper and lower flow guide surfaces - starting from the outlet opening of the gap nozzle - are designed to converge or diverge to one another, preferably parallel to one another, at least over a predetermined wear length I of the gap nozzle in the depth direction y at an angle of less than 15° in the flow direction of the coolant.

[0008] The terms “bottom” and “top” refer to the spatial arrangement of the stripping device according to the invention as shown in the figures.

[0009] When the stripping device is positioned against the surface of the work roll, the stripper tip and the gap nozzle are subject to abrasion in the region of the wear length I, particularly during hot rolling. The claimed parallel design and arrangement of the upper and lower flow guide surfaces to one another advantageously ensures that the cross-section of the gap nozzle is and remains geometrically unchanged over the wear length, even when the stripping device is positioned against a work roll and the gap nozzle is thereby worn and increasingly shortened at its cooling water outlet end due to the positioning. The cooling of the work roll and the cooling efficiency are therefore not negatively affected when the gap nozzle according to the invention is used, advantageously even in the event of wear. The cooling efficiency is also comparatively high because the distance between the front end of the stripper tip and the front end of the gap nozzle is 10 mm.between the surface of the work roll and the outlet opening of the gap nozzle is very small. This applies equally to an upper and a lower work roll in the rolling stand.

[0010] In principle, the two preferably parallel flow guide surfaces can be uneven, e.g., wave-shaped—also in the present invention. However, the exit angle at which the cooling medium exits the gap nozzle would then change depending on the wear-related abrasion of the gap nozzle. According to a first embodiment, it is therefore advantageous if the two flow guide surfaces are not only parallel, but also flat. The exit angle then advantageously remains the same regardless of the extent of the abrasion of the gap nozzle.

[0011] According to a further embodiment, a nozzle cover plate, the underside of which forms the upper flow guide surface of the gap nozzle, and / or the wiper tip are each detachably attached to the base body as a wear part. In the event of wear, they can then advantageously be easily separated from the base body and inexpensively replaced with corresponding new parts.

[0012] The nozzle cover plate is made of a softer material than the wiper tip. This ensures that the coolant can flow out even if the wiper tip becomes worn, as the flow can always be directed onto the roll surface.

[0013] If a collecting space for the coolant is formed in the stripping device upstream of the gap nozzle, this has the advantage that the coolant is evenly distributed over the entire width of the upstream collecting space, preferably over the entire width of the gap nozzle, when it exits the gap nozzle and exits the gap nozzle evenly, ie with the same pressure or the same volume flow across the width.

[0014] According to a further embodiment, the collecting chamber is divided widthwise into a plurality of zones, which can be individually switched on or off for the flow of coolant through the gap nozzle, as required in the specific case. Preferably, individual connections for the coolant supply are also assigned to each zone. The individual and / or group-based control of the coolant supply in the individual zones advantageously allows the cooling capacity of the stripping device to be individually adjusted zone by zone and, optionally, also by quantity across the width.

[0015] According to a further embodiment of the invention, a separating plate is arranged between the upper and lower flow guide surfaces, which is designed in the form of a comb with prongs, wherein the prongs are aligned towards the outlet opening of the gap nozzle. At least some of the spaces between the prongs are in fluid communication with the cooling channel, in particular with the collecting space for the coolant. The thickness of the separating plate determines the height of the gap nozzle and thus also the size of the opening cross-section of the gap nozzle. Due to the elongated extension of the prongs in the depth direction, the spaces between the prongs are also elongated. By feeding the coolant into these spaces, preferably at the base of the prongs, the coolant is advantageously aligned by the prongs for a right-angled exit from the gap nozzle even before it exits.At the same time, the separator plate, in combination with the upstream collecting chamber, ensures an even distribution of the supplied cooling water into the area of ​​the outlet opening of the slotted nozzle. The optional formation of the zones within the slotted nozzle, as already mentioned, can be achieved using corresponding blocking elements within the collecting chamber. Alternatively, the zones can also be formed by a suitable design of the separator plate. The prongs with their respective spaces are then only formed in the width area of ​​the slotted nozzle that is to be open as a zone for the flow of the coolant; in the adjacent areas in the width direction of the slotted nozzle, which are to be blocked against the passage of the coolant, this can be achieved by designing the separator plate without prongs. The separator plate then acts as a seal for the collection chamber over the respective desired width areas.The separating plate then covers or closes the openings of the cooling channel between the tines so that no more coolant can pass through.

[0016] With regard to said system, the above-mentioned object of the invention is achieved by the subject matter of claim 10.

[0017] With regard to the rolling stand, the above-mentioned object of the invention is achieved by the subject matter of claim 11.

[0018] 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 comprise an adjusting device for adjusting the stripping device against an upper and / or lower work roll. The stripping devices are then arranged above and / or below the rolled rolling stock and in this way advantageously at least largely prevent contact of the upper side and / or the underside of the rolling stock with 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 there for the lower stripping device to be adjusted against the lower work roll by weight.

[0019] The claimed rolling stand can have 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 stock to a predetermined target flatness, and / or the actual profile of the rolled stock to a predetermined target profile. The stripping device according to the invention then serves as an actuator in conjunction with a valve for the coolant, which can preferably be controlled by the control device or the regulating device. With the aid of the adjusting device, the stripping device is adjusted against the surface of the work roll, and with the aid of the valve, the speed at which the coolant emerges from the gap nozzle is varied in such a way that the said actual values ​​can be converted into the said target values.Alternatively or additionally, the zones within the scraper device can also be individually activated or deactivated for the stated purpose.

[0020] The above-mentioned object is finally achieved by the method according to claim 13 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.

[0021] The description includes 4 figures, where

[0022] Figure 1 shows the stripping device according to the invention in a longitudinal section;

[0023] 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

[0024] Figure 4 shows the stripping device according to the invention with an associated adjusting device in a rolling stand.

[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 identical reference numerals.

[0026] 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 stand and to shield a rolled stock rolled with the aid of the work roll from the coolant. 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 connection 130-i, with i = 1-1, with I e N, in a fluid-conducting manner to a slotted nozzle 140 on the stripper tip 110. The outlet opening of the slotted 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 delimited 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 side 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 regarded as part of the stripper tip 110. When the stripping device 100 is positioned against a work roll 210 during operation of the rolling stand, the stripper tip 110, together with the gap nozzle 140, i.e., in particular, together with the nozzle cover plate 146, is subject to wear as a result of abrasion. This potential wear area is indicated by the hatched reference numeral 180 in Figure 1. The work roll 210, indicated by a solid line in Figure 1, shows the initial state in which the work roll is positioned against the front end 112 of the still unused stripper tip 110.In contrast, the dashed line shows the position of the work roll 210 after wear has occurred.

[0027] In order to ensure that the abrasion and wear of the gap nozzle 140 does not lead to an undesirable change in the geometry of the outlet opening of the gap nozzle and thus to an uncontrolled discharge of water from the gap nozzle, the upper and lower flow guide surfaces 142, 144 in the gap nozzle 140 according to the invention - starting from the outlet opening of the gap nozzle 140 for the coolant - are aligned parallel to one another in the depth direction y at least over a predetermined wear length I of the gap nozzle.

[0028] In addition, the lower and upper flow guide surfaces 144, 142 can also be planar or flat, as shown in Figure 1. 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 with which the coolant impinges on the surface of the work roll remains constant at a constant angle of attack of the scraper device 100 against the work roll 210, even with continuous abrasion of the gap nozzle 140.

[0029] In particular, the nozzle cover plate 146 and / or the wiper tip 110 are advantageously detachably attached to the base body 120 as wearing parts.

[0030] Figure 1 further shows that the cooling channel 122 has a collecting chamber 125 for the coolant, which is arranged upstream of the gap nozzle 140 opposite to the flow direction -y of the coolant and preferably extends in the width direction x over the entire width of the gap nozzle 140. The collecting chamber 125 is covered in Figure 1 with a cover plate 126.

[0031] Figure 2 shows the stripping device 100 according to the invention in an open state in a perspective view. In Figure 2, the stripping device is open in particular in that the cover plate 126 for the collecting chamber and the nozzle cover plate 146 of the gap nozzle 140 have been removed. While Figure 1 only shows the front part of the stripping device 100 up to the collecting chamber 125 in a longitudinal section, Figure 2 also shows rear regions of the base body 120 with the connections 130 for supplying the coolant. It can be seen that the individual connections 130 for supplying the coolant are each assigned their own channels, which open into the collecting chamber 125. The collecting chamber 125 is in fluid communication with the spaces between each two adjacent prongs 155 of the separating plate 150 via the slots 159 visible in Figure 2 and via the opening 158 of the cooling channels.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 guided out of the wiping nozzle evenly and in a directed manner by the tines 155, as indicated by the arrows in Figure 2, parallel to their longitudinal extension.

[0032] The stripping device 100 according to the invention can be divided into individual zones Z1...Z4 in the width direction x. The division into zones is optional and can be implemented, for example, by providing optional separating webs 127 within the collecting chamber 125. Preferably, each of the zones is then assigned its own connection 130-i for supplying the coolant. Alternatively or in addition to providing the webs 127, individual zones within the gap nozzle 140 can also be implemented by providing the separating plate 150 with the said prongs 155 only in the desired zones. In the remaining areas in the width direction, in which no zone or no discharge of the coolant is desired, this can also be implemented by designing the separating plate 150 in these width areas such that it covers the openings 158.This would then prevent the coolant from escaping through these openings 158 in the respective width areas.

[0033] Figure 3 shows the structure of the gap nozzle 140 according to the invention again in an exploded view. The underside forms the wiper tip 110 with the aforementioned openings 158 as fluid-conducting connections between the collection chamber 125 and the spaces between the prongs 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.

[0034] Figure 4 shows a rolling stand 200 with an upper and a lower work roll 210 for rolling rolled stock. Preferably, at the exit of the rolling stand 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.

[0035] Alternatively or in addition to the upper stripping device 100, a lower stripping device 100 can also be provided for positioning against the lower work roll 210 of the rolling stand 200. A lower positioning device is not necessarily required to position the lower stripping device 100; as an alternative to a lower positioning device, the lower stripping 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 stock to a predetermined target flatness, and / or the actual profile of the rolled stock to a predetermined target profile.The lower and / or upper stripping device 100 according to the invention serves as an actuator in conjunction with a valve for the coolant that can be controlled by the control device or the regulating device. With the aid of the valve, the exit velocity at which the coolant exits the gap nozzle 140 of the respectively activated stripping device 100 is then suitably varied in such a way that the said actual values ​​are adjusted or regulated to the said predetermined target values. As described above, the said actuator is also suitable for controlling the exit of the coolant zone-by-zone in the width direction x.

[0036] The stripping device 100 in conjunction with the adjusting device 160 forms the system in the sense of the invention.

[0037] The method according to the invention for operating the system according to the invention comprises in particular the following steps:

[0038] - Positioning the stripping device 100 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, the 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 at which the coolant exits the gap nozzle 140 is then suitably varied with the aid of said valve, controlled by the control device or regulating device 220, such that at least one of the above-mentioned actual variables is adjusted or regulated to the associated predetermined target variables. 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; ie in certain operating conditions it may be useful to switch the pumping system according to the invention

[0040] Stripping device 100 can be positioned against the surface of a work roll 210 even without escaping coolant.

[0041] List of reference symbols

[0042] 100 scraper device

[0043] 110 scraper tip

[0044] 112 front end of the scraper tip

[0045] 120 basic bodies

[0046] 122 cooling channel

[0047] 125 assembly room

[0048] 126 Cover plate collecting chamber

[0049] 127 dividers (optional)

[0050] 130 Connection for supplying the coolant

[0051] 140 gap nozzle

[0052] 142 upper flow guide surface

[0053] 144 lower flow guide surface

[0054] 146 Nozzle cover plate

[0055] 148 finishing bar

[0056] 150 dividing plate

[0057] 155 tines

[0058] 158 openings of the cooling channels between 2 tines

[0059] 160 Adjustment device

[0060] 180 wear area

[0061] 200 rolling stands

[0062] 210 work roll

[0063] 220 control device

[0064] I Wear length x Width direction y Depth direction

[0065] -y flow direction of coolant z height direction

[0066] Z1, Z2, Z3, Z4 individual zones

Claims

Patent claims:

1. A scraper device (100) for applying a liquid coolant to the surface of a work roll (210) of a rolling stand (200) and for separating a rolled material rolled with the aid of the work roll from the coolant flowing down from the work roll, comprising - a scraper tip (110); and - a base body (120) as a support for the wiper tip (110), wherein the base body (120) has a cooling channel (122) inside for the coolant for fluid-conducting connection of at least one port (130) for supplying the coolant to a gap nozzle (140) formed on the wiper tip (110) for applying the coolant to the work roll (210), wherein the gap nozzle (140) is set back in the depth direction (y) relative to the front end (112) of the wiper tip (110); and wherein the cooling channel (122) inside the gap nozzle (140) is bounded by an upper flow guide surface (142) and a lower flow guide surface (144);characterized in that the upper and lower flow guide surfaces (142, 144) are designed to converge or diverge towards each other, preferably parallel to each other, at least over a predetermined wear length (I) of the slot nozzle (140) in the depth direction (y) at an angle of less than 15° in the flow direction of the coolant.

2. Scraper device (100) according to claim 1 , characterized in that the upper and the lower flow guide surface (142, 144) are each flat. A wiper device (100) according to any one of the preceding claims, characterized in that the upper flow guide surface (142) is formed by the underside of a nozzle cover plate (146) and the lower flow guide surface (144) by the upper side of the wiper tip (110). A wiper device (100) according to any one of the preceding claims, characterized in that the nozzle cover plate (146) and / or the wiper tip (110) are detachably attached to the base body (120) as wear parts. A wiper device (100) according to claim 3 or 4, characterized in that the nozzle cover plate (120) is made of a softer material than the wiper tip (110).A wiper device (100) according to one of the preceding claims, characterized in that the cooling channel (122) has a collecting chamber (125) for the coolant located upstream of the slot nozzle against the flow direction (-y) of the coolant, which preferably extends over the entire width of the slot nozzle (140). A wiper device (100) according to claim 6, characterized in that the collecting chamber (125) is divided in the width direction (x) into a plurality of zones (Z1, Z2, Z3) which can be individually switched on or off for the flow of the coolant through the slot nozzle (140) – depending on the requirements in each individual case; and that preferably individual connections (130-i) are provided for the supply. of the coolant to the individual zones (Z1, Z2, Z3). Wiper device (100) according to one of the preceding claims, characterized in that a separating plate (150) is arranged between the lower and the upper flow guide surface (142, 144), the separating plate being designed in the form of a comb with teeth (155) oriented towards the outlet opening of the slot nozzle (140), wherein at least some of the openings (158) between the teeth (155) are in fluid-conducting communication with the cooling channel (122), in particular the collecting chamber (125) for the coolant. Wiper device (100) according to claim 8, characterized in that the teeth (155) on the separating plate (150) are formed only in the at least one zone across the width of the slot nozzle that is provided for a flow of the coolant.System comprising a stripping device (100) according to one of the preceding claims; and an adjusting device (160) for adjusting the stripping device (100) against the surface of a work roll (210) in a rolling mill stand (200). Rolling mill stand (200) with at least one work roll (210) for rolling material; characterized in that, preferably in the exit of the rolling mill stand, at least one stripping device (100) according to one of claims 1 to 9 is provided; that an upper adjusting device (160) is provided for adjusting the stripping device (100) against an upper work roll (210). and / or that no lower adjusting device or a lower adjusting device is provided for positioning the stripper (100) against a lower work roll (210). Rolling stand according to claim 11, characterized by a control device or regulating device (220) 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, in each case by suitable variation of the speed at which the coolant exits the gap nozzle (140) and / or by variation of the zones (Z1, Z2, Z3) from which the coolant exits the gap nozzle (140) with the stripper, preferably in conjunction with a controllable valve for the coolant, in each case as an actuator. Method for operating the system according to claim 10, comprising the following steps: - Positioning the stripper device against the work roll in a rolling mill stand so that the stripper tip and the nozzle cover plate press against the work roll simultaneously; and - optional pumping of the coolant through the at least one connection (130) for supplying the coolant through the cooling channel (122) and through the gap nozzle (140) onto a work roll (210) in a rolling stand (200); characterized in that the speed at which the coolant exits the gap nozzle (140), preferably - if necessary - in combination with activation of at least individual zones of the gap nozzle, as control variables The process is varied in such a suitable manner that the actual thermal crowning of the work rolls adjusts to a predetermined target crowning, the actual flatness of the rolled material adjusts to a predetermined target flatness, and / or the actual profile of the rolled material adjusts to a predetermined target profile. The method according to claim 13, characterized in that the coolant is at least substantially water. The method according to claim 13 or 14, characterized in that the pumping of the coolant can be speed-controlled and / or switched on or off.

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