US20080125297A1 - Roll With Rotating Shell - Google Patents
Roll With Rotating Shell Download PDFInfo
- Publication number
- US20080125297A1 US20080125297A1 US11/547,723 US54772304A US2008125297A1 US 20080125297 A1 US20080125297 A1 US 20080125297A1 US 54772304 A US54772304 A US 54772304A US 2008125297 A1 US2008125297 A1 US 2008125297A1
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- United States
- Prior art keywords
- pad
- shell
- pressure
- roll
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C13/00—Rolls, drums, discs, or the like; Bearings or mountings therefor
- F16C13/02—Bearings
- F16C13/022—Bearings supporting a hollow roll mantle rotating with respect to a yoke or axle
- F16C13/024—Bearings supporting a hollow roll mantle rotating with respect to a yoke or axle adjustable for positioning, e.g. radial movable bearings for controlling the deflection along the length of the roll mantle
- F16C13/026—Bearings supporting a hollow roll mantle rotating with respect to a yoke or axle adjustable for positioning, e.g. radial movable bearings for controlling the deflection along the length of the roll mantle by fluid pressure
- F16C13/028—Bearings supporting a hollow roll mantle rotating with respect to a yoke or axle adjustable for positioning, e.g. radial movable bearings for controlling the deflection along the length of the roll mantle by fluid pressure with a plurality of supports along the length of the roll mantle, e.g. hydraulic jacks
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
- B21B27/02—Shape or construction of rolls
- B21B27/03—Sleeved rolls
- B21B27/05—Sleeved rolls with deflectable sleeves
- B21B27/055—Sleeved rolls with deflectable sleeves with sleeves radially deflectable on a stationary beam by means of hydraulic supports
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
- D21G1/00—Calenders; Smoothing apparatus
- D21G1/02—Rolls; Their bearings
- D21G1/0206—Controlled deflection rolls
- D21G1/0213—Controlled deflection rolls with deflection compensation means acting between the roller shell and its supporting member
- D21G1/022—Controlled deflection rolls with deflection compensation means acting between the roller shell and its supporting member the means using fluid pressure
Abstract
The invention relates to a rolling mill roll with a rotating shell consisting of a tubular shell (1) rotatably mounted on a plurality of pads (3) holding the shell (1), whereby a hydrodynamic lift effect is created by introducing a lubricating fluid between the bering face (31) of the pad (3) and the internal face (13) of the shell (1).
According to the invention, the bearing face (31) of each pad is provided with three hydrostatic pockets, one middle pocket (5) and two upstream (7) and downstream (6) lateral pockets, respectively, which are fed with the same fluid under a pressure sufficient to allow an additional oil flow to be introduced into the dragged out film (4) with a local pressure increase, in order to broaden—in the upstream and downstream direction—the hydrodynamic lift angular sector (4) while maintaining, throughout the length thereof, the fluid quantity required for the desired lift effect.
Description
- This application is a National Stage entry of International Application No. PCT/FR2004/000954, filed Apr. 16, 2004, the entire specification claims and drawings of which are incorporated herewith by reference.
- The invention relates to a roll with rotating shell of the type consisting of a cylindrical tubular shell rotatably mounted about an elongated support beam and bearing on the said beam via holding means, and applies in particular to a back-up roll in a rolling mill for metal strip, especially steel strip.
- For some time it has been proposed to use, at first in paper-making and then, more recently, in metal strip rolling mills, rolls with a rotating shell, consisting of a stationary support shaft in the form of an elongated beam, surrounded by a tubular shell rotatably mounted about bearings defining an axis of rotation perpendicular to rolling axis, and bearing on the beam via a plurality of holding means distributed side by side along the length of the beam and centered in an axial bearing plane passing through the roll axis and an external face of the roll, and corresponding to the plane of transmission of the roll force load when the roll is part of a rolling mill.
- The tubular shell is relatively deformable and, in the case of a four-high or six-high rolling mill, the use of this type of roll as a back-up roll, by selectively actuating the different holding means, gives the external face of the roll a profile that allows the deflection of the shaft to be compensated and, besides, any fault in the evenness of the surface or in the thickness of the product caused in the course of rolling to be corrected. For this purpose, each means of holding the shell consists of a pad essentially centered in the bearing plane, disposed between the shell and the support beam and slideably mounted on the said support beam in a radial direction essentially extending in the roll load plane. Each pad bears on one side of the internal face of the shell, via a cylindrical bearing face, and on the other side on the support beam via an adjustable thrust means generally consisting of at least one hydraulic cylinder arranged between the support beam and the pad. It is thus possible to regulate the thrust of each pad individually in the radial direction, in order to give the tubular shell the desired profile and/or correct the distribution of thrust forces throughout the external bearing face.
- The tubular shell rotates on the bearing faces of the holding pads, and it is therefore necessary to introduce a lubricant between the bearing face of each pad and the internal face of the shell.
- For this purpose, each holding pad can be provided, on its bearing face, with at least one hydrostatic pocket consisting of a recess opening towards the outside and fed with a lubricant under a pressure corresponding to the thrust.
- As the hydrostatic pocket opens towards the outside, the lubricant fed in the said pocket under pressure may escape toward the edges of the pocket, forming a lubricating film in the gap between the bearing face of the pad and the shell.
- This leak rate remains fairly low so long as the external face of the pad is correctly centered with respect to the internal cylindrical face of the rotating shell but the said shell is subjected to stresses likely to cause deformation of the shell in a transverse direction, thereby causing the pad to shift and, consequently, increasing the leak rate. To remedy this, it is proposed in the document GB-A-2 060 822, in addition to the thrust cylinders exerting the main force at pad centre, to incorporate two side cylinders in which pressure may be varied so as to restore the concentricity of the pad with the shell. The pad width, in the transverse direction, is thus slightly increased but the angular sector covered by the circular bearing face does not exceed 45°.
- In this case, it is rather difficult to maintain the stability of the pad which, most often, must be linked to the support beam through a hinged-type rod so that it can be kept centered in the axial plane passing through the external bearing face of the shell.
- In such known arrangements, the lubricant feeding the hydrostatic pocket is simply taken from the fluid that feeds the thrust cylinder via a channel provided between the cylinder chamber and the hydrostatic pocket.
- Such a feeding mode could be appropriate when such devices were used, for example, in the paper industry. However, it was more difficult to apply them to metal strip rolling, in particular steel rolling, as the thrust loads sustained by the roll are extremely high and it is difficult to control the thrust cylinders if there is a variable leak rate for feeding the hydrostatic pocket.
- It has thus been proposed, in the document FR-A-2 572 313, to increase the aperture of the angular sector covered by the pad bearing face and to obtain a hydrodynamic effect in the lubricating film arranged in the gap between the said bearing face and the shell, by injecting oil under low pressure at the upstream end of the pad in the direction of rotation of the shell, and with a boosting flow rate which causes the rotating shell to drag out a sufficient quantity of oil so that a continuous oil film is formed in the gap between the shell and the pad, which escapes through the downstream end of the pad. An oil circulation is thus created, which ensures a hydrodynamic lift effect between the pad and the shell, allowing a high pressure to be obtained in the oil film which, in addition, is distributed over a larger surface.
- It is thus possible to exert very high thrust forces on the shell, e.g. for steel rolling.
- A further advantage of this arrangement is that the lubricant is not fed from the thrust cylinder chamber but through a separate circuit under low pressure. It is thus not necessary, as before, to maintain a leak rate in the high pressure circuit feeding the thrust cylinders.
- Besides, as a hydrodynamic lift effect is used, the pressure, which is very low at the upstream end of the gap between the pad and the shell, gradually increases due to the oil drag-out, reaches a peak which is angularly shifted downstream with respect to the roll load plane passing through the external bearing face, then very quickly decreases and becomes nil at the downstream end of the gap, at pad exit. This results in a self-centering of the pad by a wedge effect.
- However, prerequisite for obtaining this hydrodynamic lift effect, is that the rotational speed of the shell around the shaft is sufficient to drag along the oil injected upstream. Besides, the injected oil flow must be sufficient to ensure the circulation of the lubricant up to the pad exit by compensating for the lateral leaks.
- To avoid the shell contacting the pads in the event of faulty oil feeding or of shell rotation being stopped, it has been proposed in the document FR-A-2 572 313 already mentioned, to arrange a hydrostatic pocket in the central part of the pad, which is fed with a pressurized fluid which, at normal speed, mixes with the oil introduced upstream and carried by the rotating shell, and, at low speed, prevents direct contact by allowing the lubricating film to be formed.
- Besides, to adjust the shell profile and the distribution of bearing forces accurately, it is recommended to use a fairly large number of pads. Therefore, the bearing face of each pad which, as described above, must cover a large angular sector, has the form of an elongated rectangle of fairly small width compared with its length.
- This results in significant leaks at the side edges of each pad and, consequently, in a pressure drop entailing the risk of breakage of the lubricating film.
- The hydrodynamic lift effect created by oil circulation in the gap between the pad and the shell, therefore develops in a pressure area comprising, in the lengthwise direction of fluid circulation, an upstream portion for gradually increasing the fluid pressure from pad entry, a hydrodynamic lift central portion and a downstream portion for quick decrease in pressure at pad exit.
- Generally, the central lift part covers an angular sector of the pad subjected to a sufficient pressure to compensate for the global bearing force exerted on the tubular shell by the work roll.
- As mentioned above, it is necessary, especially when rolling metallic products, to produce high forces which, in addition, may significantly vary between the individual pads, in order to correct the shape and/or gauge defects found on the rolled strip, downstream of the rolling mill.
- Besides, transient excess pressures may occur, especially when threading the strip into the rolling stand or when a weld joining two successive strips, which may have different geometric or metallurgical properties, is passing through.
- The use of a hydrodynamic lift effect offers a number of advantages. However, it has been noticed that the various malfunctions that may occur during operation, in particular in the case of rolling, are likely to entail some instability of the pad and also an accidental contact with the shell due to a breakage of the lubricating film. Therefore, it may sometimes be difficult to maintain the reliability of the overall unit at a satisfactory level.
- The object of the invention is to remedy such disadvantages by a fairly simple arrangement which allows better control of the hydrodynamic film oil feeding and of pressure distribution on the bearing face of each pad, thus more easily maintaining relatively stable operating conditions.
- The invention therefore relates to a roll with a rotating shell of the type consisting of a tubular shell rotatably mounted about a stationary elongated support beam and bearing on the said beam via a plurality of pads, each provided with a cylindrical bearing face having nearly the same radius as the radius of the internal face of the shell, whereby the position and thrust of each pad can be adjusted through a hydraulic cylinder resting, on one side, on the beam, and on the other side, on the pad, and fed with a pressurized fluid, each pad being, in addition, fitted with an hydrostatic pocket provided in a central part of its bearing face and fed with a pressurized fluid, and besides, associated with means of introducing a lubricating fluid upstream of the gap between the pad bearing face and the internal face of the shell, so as to create a hydrodynamic lift effect in a pressure area which covers a large angular sector and comprises, in the shell rotational direction, an upstream portion for gradually increasing the pressure, a lift central portion and a downstream portion for quick decrease in pressure up to pad exit.
- According to the invention, the bearing face of each pad is fitted with two lateral pockets opening on both sides of the middle pocket, respectively, and fed with a fluid under a pressure sufficient to allow an additional oil flow to be introduced into the dragged out film with a local pressure increase, in order to broaden—in the upstream and downstream direction—the angular sector covered by the central hydrodynamic lift portion of the pad, thus improving the stability of said pad.
- In a particularly advantageous embodiment, each pocket of each pad is associated with a means of calibrating the flow rate input through the relevant pocket, whereby the pressure in said pocket is adjusted to a level at least sufficient to cause the calibrated flow to be discharged at the corresponding level of the fluid film, up to a maximum value of the thrust exerted by the pad on the shell.
- Consequently, the central lift part of the pressure area consists of a high pressure central pressure stage covering an angular sector nearly corresponding to the middle pocket, and two lateral pressure stages each extending on an angular sector associated with a lateral pocket, an upstream pressure stage having a lower pressure than that of the central pressure stage and a downstream pressure stage having a pressure between that of the central pressure stage and that of the upstream pressure stage.
- In a preferred embodiment, each middle pocket of a pad is individually fed by a pump delivering a calibrated flow and the lateral pockets of all the pads arranged on one side of the middle pocket are supplied in parallel from the same pipe connected to the same pump on which a plurality of individual feed pipes for each pocket, each fitted with a calibrating device for the fluid flow injected through said pocket into the dragged-out film, are connected in parallel.
- In a further embodiment, the roll includes at least three units, respectively consisting of the pockets arranged on all pads in the same position with respect to the bearing plane, upstream lateral, central and downstream lateral, respectively, and the pockets of each unit are fed in parallel from a joint piping provided lengthwise on the support beam and on which a plurality of individual feeding pipes for each pocket of said unit respectively, each fitted with an individual flow calibrating device in the corresponding, are connected in parallel.
- Besides, a roll with a rotating shell according to the invention can be used, either in a tandem rolling mill in which the product is always running in the same direction, or in a reversing rolling mill operating in both running directions.
- If, during operation, the shell rotates in a single rotational direction, the middle pocket of each pad is centered in a radial plane slightly angularly shifted downstream, in the direction of rotation, relative to the bearing plane. In that case, the downstream lateral pocket advantageously covers an angular sector which is nearly twice as large as the sector covered by the upstream lateral pocket.
- In the case of a reversing mill, the middle pocket is centered in the bearing plane P and the lateral pockets are symmetrical with respect to said bearing plane. In this case, the calibrated flow rates in both lateral pockets may be equal and the calibrated flow in the middle pocket is advantageously approx. twice as high as the flow rate in each lateral pocket.
- Other advantageous features within the scope of protection of the invention will be depicted in the following description of a particular embodiment, given by way of example and shown on the attached drawings.
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FIG. 1 is a cross-sectional schematic view of a roll according to the invention applied to a rolling mill. -
FIG. 2 is detailed cross-sectional view of a holding pad with associated hydraulic circuits. -
FIG. 3 is a bottom view of a holding pad. -
FIG. 4 is a longitudinal cross-sectional view of the roll, on which the oil feeding system is schematically shown. -
FIG. 5 is a 3-D diagram showing the pressure curve along the bearing face of a pad. -
FIG. 1 is a schematic cross-sectional view showing, by way of example, a four-high type rolling mill consisting of two work rolls T, T′ between which the rolled product M passes, and supported on the side opposite to the product on two back-up rolls S, S′ respectively, between which a roll force load is applied along a bearing plane P passing virtually through the roll axes. - At least one of the back-up rolls, e.g. the upper back-up roll S consists of a
tubular shell 1 rotatably mounted at its ends, through bearings A, A′ schematically shown inFIG. 4 , on asupport beam 11 extending inside thetubular shell 1, in a direction transverse to the rolling direction, said bearings A, A′ defining the rotational axis x′x of the shell. - As shown in
FIG. 4 , thetubular shell 1 bears on thebeam 11 through a plurality ofholding pads 3 distributed throughout its length and intercalated between the internalcylindrical face 13 of the shell and alower face 12 of thesupport beam 11. - Each
holding pad 3 is provided, on thetubular shell 1 side, with acylindrical bearing face 31 of a slightly smaller diameter than the diameter of theinner face 13 of the shell, and bears on thelower face 12 of thebeam 11 through at least one hydraulic cylinder 2 which, in the depicted example, includes onepiston 22 bearing on thebeam 11 and entering into arecess 33 machined on theface 32 of thepad 3 turned toward thebeam 11 and constituting the chamber of the hydraulic cylinder 2. Said cylinder is fed with fluid from a hydraulic power station H1 by a high pressure supply circuit, connected to each pad via apipe 21 passing through thebeam 11 and thepiston 22 and opening into thechamber 33 of the associated cylinder. - Each
pad 3 is thus associated with a cylinder 2 fed by aspecial circuit - Generally, such a system makes it possible, via a position and pressure control of each cylinder 2, to adjust the profile of the external bearing face as well as the distribution of thrust forces applied along said external bearing face, in particular to compensate for the deflection of the
support beam 11 and to correct gauge or flatness defects detected downstream on the rolled strip M. - To allow rotation of
rotating shell 1 applied on thestationary pads 3, it is necessary to intercalate a lubricating fluid film between the bearingface 31 of eachpad 3 and theinternal face 13 of the shell. - To this effect, each
pad 3 is normally provided with a hydrostatic pocket substantially centered in the bearing plane P and fed with pressurized oil, said pocket widely opening toward theinternal face 13 of the tubular shell in order to form a lubricating film 4 between theinternal face 13 of theshell 1 and the bearingface 31 of thepad 3. - It should, however, be noted that in the arrangement according to the invention, the bearing
face 31 of thepad 3 covers a circular sector with a very wide angular opening larger than 45°, which may exceed 90° and, preferably being in the order of magnitude of 100 or 110°. - Indeed, the distribution of bearing forces over such an aperture angle offers significant advantages.
- First of all, as mentioned above, an angular sector having a fairly great length allows a hydrodynamic lift effect to be created in the lubricating fluid film 4. In this case, oil can be fed under low pressure by a booster circuit G, at the upstream end of the
pad 3 and, through rotation of theshell 1, is caused to flow into the gap between said shell and thepad 3, with a gradual increase in pressure through wedge effect. - Besides, the fact that the
pads 3, distributed across the length of thetubular shell 1, are provided with a large angular opening ensures excellent centering of said shell relative to thebeam 11, with a transverse stability effect avoiding transverse deformation of the shell between the end bearings when the product is passing through. - However, to accurately adjust the force distribution along the external bearing face, it is necessary to use a good many adjacent pads, eg seven pads, as shown in
FIG. 4 . Consequently, to cover a large angular sector, the bearingface 31 of eachpad 3 should have a length L1 much greater than its width L2, as shown inFIG. 3 . - This results in increasing oil leaks at the side edges of each
pad 3, entailing a risk of pressure drop, and breakage of the lubricating film as well. - Indeed, considering the pressure distribution in a direction transverse to the pad, ie parallel to the axis of rotation, it appears that, due to the leakage, said pressure quickly decreases along the side edges of the pad and is at its maximum value only in the central part of the bearing face. Besides, due to a gradual increase of pressure through a hydrodynamic effect, the leak rate increases in the rotational direction and the width of the maximum pressure area therefore decreases between the entry and exit of the bearing face.
- In addition, as mentioned above, even in the case of the lift being produced by a hydrodynamic effect with low pressure oil feeding at pad entry, it is advantageous to additionally provide high pressure feeding in the central part of the pad, in the region of bearing plane P, to allow the lubricating film to be formed when the rolling mill is starting up and in case of insufficient rotational speed. To this effect, it is advantageous to provide, in the central part of the pad, a
hydrostatic pocket 5 extending over an angular sector, eg 10 to 20°. This central hydrostatic pocket is advantageous, even at high speed, because the fluid fed in the central part of the pad is able to mix with the film dragged out through the hydrodynamic effect if feed pressure exceeds the pressure reached through the hydrodynamic effect in the region of thiscentral pocket 5. It is thus possible to widen the pressure area at this central pocket both in the lengthwise rotational and transverse directions. - From pad entry, the pressure area thus consists of an upstream portion for a gradual increase in pressure, a central part constituting a maximum pressure stage in the region of the
central pocket 5 and a downstream portion for quick pressure decrease at pad exit. - Besides, the hydrodynamic lift effect created by the oil film 4 drag-out permits self-centering of the pad because a closure of the gap on the exit side increases the pressure through a wedge effect and, consequently, tends to re-centre the shell with respect to the pad.
- However, the leak rate also tends to increase and is likely to cause a breakage of the oil film, thereby causing the pad to contact the shell.
- Therefore, this entails a risk of instability which, according to the invention, will be eliminated by introducing an additional pressurized oil flow upstream and downstream of the
central pocket 5 in order to widen the angular sector covered by the hydrodynamic lift central part of the pad. - To this effect, as shown in
FIGS. 1 and 2 , the bearingface 31 of the pad is provided, on each side of themiddle pocket 5, with two downstream 6 and upstream 7 lateral pockets respectively and eachpocket - Oil injected into the three
pockets face 31, as schematically shown inFIG. 5 . - It is thus possible, through adjusting the flow rates in the three
pockets - To this effect, each
pocket -
FIG. 1 schematically shows an embodiment of the oil feeding system for eachpad 3. - As mentioned above, the thrust cylinders 2 associated with each
pad 3 respectively are fed with pressurized fluid from a hydraulic station H1, by acircuit chamber 33 of each cylinder 2. - Preferably, the
hydrostatic pockets pipes - As a matter of fact, for ease of operation of the servovalves designed to adjust the thrust forces sustained by the
pads 3, it is better that the cylinders 2 should be supplied with a low viscosity oil from the hydraulic station H1. On the other hand, thehydrostatic pockets -
FIG. 1 schematically shows a first embodiment of thecircuits pockets - The lubricant is fed from
tank 80 through apump 83 with fixed delivery, controlled byflow controller 88 and transferred back to the tank through an overfall system including an adjustablepermanent leak system 84. - In this embodiment the three
pockets pipe flow controller - Pressure values in each
feed circuit - As previously explained, some oil quantity escapes through the lateral edges of the pads but the most part is discharged at the rear end of each pad. The full quantity of oil, however, remains inside the
shell 1 which is closed at its ends by thebeam 11 and the bearings A, A′. The roll is advantageously provided with a collecting device extending throughout the shell length, above the downstream ends of all pads, in order to collect the oil escaping from the pads and transfer it back, through areturn circuit 86, to the hydraulic station H2. - In
FIG. 4 , a simple schematic axial sectional view, thepads 3 have been shown with a 90° rotation to represent the feeding circuits for the three pockets which, actually, are centered in the same plane in a direction transverse to the centerline. - Normally, the
adjacent pads 3 distributed across the full length of the shell are identical, each consisting of at least three pockets, upstream lateral 7, middle 5 anddownstream lateral 6, respectively, and arranged in the same position relative to the bearing plane P. - It is, therefore, particularly advantageous to combine the corresponding pockets into at least three units, downstream lateral E2, middle E1 and upstream lateral E3, the pockets of each unit being fed in parallel from a joint pipe extending along the
support beam 11. - As shown in
FIG. 2 , said joint pipes can be bored in thesupport beam 11, in a direction parallel to the axis of rotation x′x or the may consist of pipes attached to the side ofbeam 11. - Moreover, the two pocket units, upstream lateral E3 and downstream lateral E2 respectively, can advantageously be supplied under the same pressure from the
same pipe 60. - Thus, in the embodiment shown in
FIG. 2 , thebeam 11 is provided with three axial pipes, respectively 20 for feeding thethrust cylinders 2, 50 for feeding themiddle pockets -
Feed circuits pads 3 and which, for reasons of simplification, have been indicated on each side ofbeam 11 inFIG. 1 , advantageously consist ofpipes support beam 11 and connected in parallel to thefeed pipe 50 of the unit E1 ofmiddle pockets 5 and to thefeed pipe 60 of the units E3, E2 of lateral pockets, upstream 7 and downstream 6. -
Transverse pipes flexible hoses pipe 51 c, 61 c, 71 c bored in thepad 3 and opening, at one end, on one lateral side of thepad 3 and, at the other end, in thecorresponding pocket - In the embodiment shown in
FIGS. 1 and 2 , eachindividual circuit 51 abc, 61 abc, 71 abc is provided with a calibratingdevice beam 11, at the outlet of thetransverse pipe relevant pocket - As already explained, the
joint pipes support beam 11 but could also be attached to the beam side. -
Chamber 33 of the thrust cylinder of eachpad 3 is supplied with high pressure, low viscosity oil from the first hydraulic station H1 via acircuit 20 which can advantageously pass through a longitudinal bore in thebeam 11. Said circuit, including means of individually adjusting the position and pressure of eachpad 3, is well known and has, therefore, not been described or shown in details on the drawings. - In this first embodiment,
joint pipes middle pockets 5 on the one hand, and the two lateral pocket units, upstream E3 and downstream E2 respectively, on the other hand, to be supplied at different pressures, said pressures being adjusted to ensure continuous oil discharge throughout the bearing surface ofpad 3, taking into account the distribution of thrust force and hydrodynamic pressure in the lubricating film 4. - The hydraulic station H2 also comprises a
booster pump 87 for low pressure oil feeding at theentry 34 of thepad 3. The oil introduced through thelateral pockets 6, 7 is, of course, of the same nature and mixes with the lubricating film 4 dragged out due to the shell rotation. - Each pump 83 a, 83 b is associated with a
flow controller overfall device 84 a, 84 b. In this way, if the hydrodynamic pressure in the film 4 is sufficient at each point to ensure the hydrodynamic lift, the oil supplied bypumps - Generally, the rolling mill is designed to operate within a given rolling force range and the feed pressures in
joint pipes pocket individual circuits - The hydraulic feeding mode shown in
FIG. 1 is fairly economical as the hydraulic station H2 feeding thepockets - However, to guarantee the stability of pads, eg in case of sudden variation in the rolling force, it may be preferable, in a further improved embodiment, to use, for each pad, one pump for individual feeding of the middle pocket that sustains the bulk of the thrust force, in order to calibrate the oil flow to the required pressure at each pad.
-
FIG. 4 schematically shows such an embodiment consisting of a pumping unit 9 which comprises asmany pumps 91 as there arepads 3, each pump 91 feeding the middle pocket of a pad at the pressure required for discharging the calibrated flow, taking into account the thrust force applied on theshell 1 in the region of the relevant pad. - As depicted above, the two lateral pocket units E2, E3 can be fed through the
same pump 83 by acircuit 8 similar to the one that has previously been described with reference toFIG. 1 . - Advantageously, this
circuit 8 may include, downstream of thepump 83, asafety block 84 which limits the common pressure to the required level and adevice 88 for measuring and controlling the global flow rate in the two units E2, E3 of lateral pockets of thepads 3. -
FIG. 5 is a 3D-diagram showing, for a half pad placed on one side of the middle plane Q perpendicular to the axis of rotation, the pressure curve on the ordinate axis, as a function of the angular position along the bearingface 31 of the pad, indicated after development of said bearing face along the horizontal abscissa axis. - In the embodiment shown in
FIG. 5 , the upstream lateral pocket 7 covers an angular sector of approx. 10°, having its middle plane P1 inclined at approx. 25° relative to the bearing plane P on which themiddle pocket 5 is centered, and the middle plane P2 of thedownstream pocket 6, which also covers a sector of approx. 10°, is inclined at approx. 20° relative to said vertical bearing plane P. - The
middle pocket 5 is centered on the bearing plane P and covers an angular sector of approx. 20°. - The pad, however, remains of the type shown in
FIG. 2 and, therefore, comprises means of introducing, at theentry 34 of the pad, a lubricating fluid which is dragged out by the rotation ofshell 1 and creates a hydrodynamic lift effect. - Generally, the pressure diagram includes, as usual, an upstream zone A for gradual increase of the fluid pressure, a central zone B of maximum pressure and a downstream zone C for fast pressure decrease at exit of the pad. However, the two
lateral pockets 7, 6 significantly modify the shape of parts A and C of the diagram by creating therein two pressure stages, upstream 41 and downstream 42, respectively, on each side of acentral pressure stage 40 corresponding to themiddle pocket 5. - As the oil introduced at low pressure at the
entry 34 of the pad is gradually carried along, its hydrodynamic pressure is not very high at the upstream pocket 7 and may be, for example, in the embodiment shown, of the order of magnitude of 1/7 of the maximum pressure in themiddle pocket 5. However, the fact that an additional fluid quantity is injected at this level, which mixes with the lubricating film dragged along by the rotation, increases the pressure of said film and allows the upstream part A of the hydrodynamic lift zone to be widened in the upstream direction. - Besides, as mentioned above, the fact that the width L2 of the pad is small compared to its length L1 causes lateral oil leaks and the maximum pressure area tends to tighten in the direction of rotation of the shell. Introducing an additional oil flow through the upstream pocket 7 is a means of compensating for this leakage and, consequently, of longitudinally and transversely widening the
central pressure stage 40, which can thus cover a length and a width fairly close to the dimensions of themiddle pocket 5. - After exiting said
middle pocket 5, the leak rate further increases and the oil escapes from the gap between pad and shell with a risk of contact with the exit of the pad. - However, as shown on the diagram, the oil introduced through the
downstream pocket 6 must be at a fairly high pressure, higher than the pressure of the upstream pocket 7, and this additional calibrated oil flow permits the part C of the hydrodynamic lift zone to be widened in the downstream direction, thus avoiding any risk of contact with the pad and the shell. In practice, pressure in thedownstream pocket 6 may be about half the maximum pressure in themiddle pocket 5. - The angular sector covered by the hydrodynamic lift zone is thus widened in the upstream and downstream directions. Besides, injecting a pressurized fluid into the two
lateral pockets 6, 7 causes, by hydrostatic effect, thrust forces F1, F2 centered on the middle radial planes P1, P2 of bothpockets 6, 7 which are inclined at a minimum angle of 20° relative to the bearing plane P. - Expansion of the hydrodynamic lift angular sector and the fact that the shell is supported on three distant points considerably improves the stability of each pad. The back-up roll is thus able to sustain sudden variations in the thrust force applied by the work roll, without any risk of shift of the
shell 1 and of contact between said shell and the external faces 13 ofpads 3. - Of course, the invention is not limited to the details of the embodiments that have just been described by way of a simple example and alternative embodiments could be included without deviating from the scope of protection of the invention.
- In particular, it is possible to vary the angular sectors covered by the different pockets, and their angles of inclination relative to the middle plane. To reach the desired stability effect, the hydrodynamic lift zone should, however, cover a large angular sector, approx. one quadrant and, anyway, of at least 45° to 50°.
- Besides, should the shell always rotate in the same direction, it would be better that the middle plane P1 of the
downstream pocket 6 be more inclined with respect to the bearing plane P than the middle plane P2 of the upstream pocket 7. In addition, themiddle pocket 5 could be slightly shifted in the downstream direction, in the direction of rotation of theshell 1, in order to compensate for the deformation of the associated work roll in the reverse direction while the product is passing through. In this case, the middle plane P of themiddle pocket 5 would be slightly inclined with respect to the vertical plane. - However, this invention may also advantageously apply to the construction of reversing mills in which the rolls and, consequently the
tubular shell 1, are rotating alternately in one direction and the other. - In that case, the arrangement would be symmetric, as the
middle pocket 5 is centered on the vertical plane passing through the axis and the twolateral pockets 6 and 7 are equal and centered on inclined planes of the same angle relative to the vertical line, on each side thereof. - The reference marks inserted after the technical data mentioned in the claims are only aimed to facilitate the understanding thereof and do not constitute a limitation of the scope thereof.
Claims (19)
1. Roll with a rotating shell consisting of:
a stationary support (11) in the form of an elongated beam,
a tubular shell (1) having an internal face (13) and a cylindrical external face, surrounding the support beam (11) and rotatably mounted on said beam around a rotation axis, said shell being subjected to thrust forces distributed along an external face and directed virtually along a bearing plane (P),
a plurality of pads (3) holding the shell (1), intercalated between the internal face (13) of said shell and a bearing face of the support beam (11) and distributed, side by side, across the shell length, each pad (3) being shiftable along a radial direction passing through the rotation axis and comprising a cylindrical bearing face (31) having a radius nearly equal to that of the internal face (13) of the tubular shell (1) and extending over a large aperture angular sector,
means of individually adjusting the position and thrust of the pads (3) comprising, for each pad (3), at least one hydraulic cylinder (2) intercalated between the beam and the pad (3) and connected to a first pressurized fluid feeding circuit (20),
at least one hydrostatic pocket (5) provided in a middle part of the bearing face (31) of the pad and connected to a second pressurized fluid feeding circuit (50),
means of introducing, in a gap between the bearing face (31) of the pad (3) and the internal face (13) of the shell (1), a lubricating fluid forming a continuous film dragged out by the rotation of the shell (1) whereby a hydrodynamic lift effect is created in a pressure area (4) extending over a large aperture angular sector and comprising, in the direction of rotation of the shell (1), an upstream part (A) for gradually increasing the fluid pressure from pad entry, a maximum pressure central part B covering an angular sector substantially corresponding to the middle pocket (5), and a downstream part (C) for quick decrease in pressure up to pad exit,
characterized in that the bearing face (31) of each pad is provided with two lateral pockets, upstream (7) and downstream (6), opening on each side of the middle pocket (5) and supplied with fluid under a pressure sufficient to allow an additional oil flow to be introduced into the dragged out film with a local pressure increase, in order to broaden—in the upstream (4) and downstream direction—the hydrodynamic lift angular sector (4) by maintaining, throughout the length thereof, the fluid flow rate required for the desired lift effect.
2. Roll with a rotating shell as claimed in claim 1 , characterized in that each pocket (5, 6, 7) of each pad (3) is associated with a means of calibrating the flow introduced through the relevant pocket, the pressure in said pocket being adjusted at a value at least sufficient to cause the calibrated flow to be discharged at the corresponding level of the fluid film (4), up to a maximum value of the thrust exerted by the pad (3) on the shell (1).
3. Roll with a rotating shell as claimed in claim 2 , characterized in that the fluid introduced under pressure through the two lateral pockets (6, 7) determines thrust forces centered on two radial planes (P1, P2) inclined on each side of the bearing plane (P) and likely to maintain the pad stability.
4. Roll with a rotating shell as claimed in claim 1 , characterized in that the hydrodynamic lift zone (4) of the pad includes a high pressure central pressure stage extending over an angular sector substantially corresponding to the middle pocket (5), and two lateral pressure stages corresponding to the two lateral pockets (7, 6) respectively, one upstream pressure stage (41) in the upstream pressure increase part (A) and one downstream pressure stage (42) in the downstream part (C) for pressure decrease in the lift zone (4).
5. Roll with a rotating shell as claimed in claim 4 , characterized in that the upstream lateral pocket (7) is fed at a pressure lower than the pressure in the middle pocket (5) and that the downstream lateral pocket (6) is fed at a pressure between middle pocket (5) and upstream pocket (7) pressures.
6. Roll with a rotating shell as claimed in claim 4 , characterized in that the fluid introduced at the level of the upstream pressure stage (41) causes the hydrodynamic pressure to increase more rapidly as a result of the increased quantity of dragged out fluid and determines a longitudinal and transverse widening of the high pressure central pressure stage (40) by leak rate compensation in this region.
7. Roll with a rotating shell as claimed in claim 6 , characterized in that the fluid introduced in the region of the downstream pressure stage (42) causes the hydrodynamic lift zone (4) to widen as a result of the increased quantity of fluid dragged out up to pad (3) exit.
8. Roll with a rotating shell as claimed in claim 2 , characterized in that each middle pocket (5) is fed individually by a pump delivering a calibrated flow rate.
9. Roll with a rotating shell as claimed in claim 8 , characterized in that the lateral pockets (6) (7) of all pads (3) arranged on the same side of the middle pocket (5) are supplied in parallel from a common pipe connected to one single pump on which a plurality of individual fed pipes for each pocket are connected in parallel, each fitted with a device (62) (72) for calibrating the fluid flow injected through said pocket into the dragged out film.
10. Roll with a rotating shell as claimed in claim 2 , characterized in that it comprises at least three units (E3, E1, E2) consisting of the pockets arranged on all the pads (3) in the same position relative to the bearing plane (P), lateral upstream (7), middle (5) and lateral downstream (6), respectively, and the pockets of each unit (E3, E1, E2) are fed in parallel from a joint pipe (71, 51, 61) provided along the support beam (2) and on which a plurality of individual pipes feeding each pocket of the unit (E3, E1, E2), are connected in parallel, each fitted with an individual device (72, 52, 62) for calibrating the flow rate in the corresponding pocket (7, 5, 6).
11. Roll with a rotating shell as claimed in claim 10 , characterized in that the two lateral pocket units (E3, E2), upstream (7) and downstream (6) respectively, are fed in parallel from a common pipe (60) and that the fluid feed circuit consists of two branches, a first branch feeding all middle pockets (5) via a first common pipe (50) and a second branch feeding all lateral pockets (6, 7) via a second common pipe (60).
12. Roll with a rotating shell as claimed in claim 11 , characterized in that each pocket unit (75, 55, 65) is associated with an open-circuit controlled feeding system, comprising one pumping device (83) for feeding the circuit with a global flow rate under a common pressure, said flow rate and said pressure being adjusted to levels at least sufficient to cause the calibrated flow rates to be discharged through all the pockets of the unit up to a maximum value of the thrust force exerted by the shell (1).
13. Roll with a rotating shell as claimed in claim 2 , characterized in that the calibrated flow rates introduced through the two lateral pockets (6, 7) of each pad (3) are nearly equal and that the calibrated flow introduced through the middle pocket (5) is nearly twice as high as the flow in each lateral pocket (6, 7).
14. Roll with a rotating shell as claimed in claim 1 , in which the tubular shell (1) rotates, during operation, in a single direction relative to support beam (2), characterized in that the middle pocket (5) of each pad (3) is centered in a radial plane slightly angularly shifted downstream, in the direction of rotation, with respect to the bearing plane (P).
15. Roll with a rotating shell as claimed in claim 14 , characterized in that the downstream lateral pocket (6) covers an angular sector of the bearing face (31) nearly twice as large as the sector covered by the upstream lateral pocket (7).
16. Roll with a rotating shell as claimed in claim 15 , characterized in that the lateral pocket (7) arranged upstream, in the direction of rotation of the shell (1) covers a sector of approx. 10° centered in a radial plane inclined at about 20° relative to the bearing plane (P) and that the lateral pocket (6) arranged downstream covers a sector of approx. 20° centered in a plane inclined at about 30° relative to the bearing plane (P).
17. Roll with a rotating shell as claimed in claim 1 , characterized in that the bearing face of each pad (3) covers an angular sector of about one quadrant, up to 100°-110°.
18. Roll with a rotating shell as claimed in claim 1 , characterized in that it is operated hydrostatically from stop to a maximum shell rotation speed, the fluid flow injected through each of the three pockets (5, 6, 7) of each pad (3) being adjusted so as to maintain a continuous oil film throughout the surface of the pad, considering that said oil is dragged out by the rotating shell (1).
19. Roll with a rotating shell as claimed in claim 1 , characterized in that it constitutes at least one of the back-up rolls in a rolling stand for metallic strip.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/FR2004/000954 WO2005110635A1 (en) | 2004-04-16 | 2004-04-16 | Rotary casing roll |
Publications (1)
Publication Number | Publication Date |
---|---|
US20080125297A1 true US20080125297A1 (en) | 2008-05-29 |
Family
ID=34958055
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/547,723 Abandoned US20080125297A1 (en) | 2004-04-16 | 2004-04-16 | Roll With Rotating Shell |
Country Status (4)
Country | Link |
---|---|
US (1) | US20080125297A1 (en) |
EP (1) | EP1740326A1 (en) |
CN (1) | CN100546733C (en) |
WO (1) | WO2005110635A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10677286B2 (en) | 2016-05-26 | 2020-06-09 | Flender-Graffenstaden S.A.S. | Hydrodynamic bearing with injectors and deflectors |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FI123495B (en) * | 2012-04-24 | 2013-05-31 | Metso Paper Inc | Arrangement for damping the vibrations of the calender rollers |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4882922A (en) * | 1986-06-04 | 1989-11-28 | Clecim S. A. | Rolling mill roll with rotating shell |
US5967957A (en) * | 1995-07-26 | 1999-10-19 | Eduard Kusters Maschinenfabrik Gmbh & Co. | Roller assembly with internal supporting elements |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2942002C2 (en) * | 1979-10-17 | 1982-06-16 | Kleinewefers Gmbh, 4150 Krefeld | Pressure treatment roller |
DE3700439A1 (en) * | 1986-09-05 | 1988-03-17 | Escher Wyss Ag | DEFLECTION ADJUSTING ROLLER |
DE4133562A1 (en) * | 1991-10-10 | 1993-04-22 | Voith Gmbh J M | ROLLER WITH BEND COMPENSATION |
-
2004
- 2004-04-16 US US11/547,723 patent/US20080125297A1/en not_active Abandoned
- 2004-04-16 EP EP04742534A patent/EP1740326A1/en not_active Withdrawn
- 2004-04-16 WO PCT/FR2004/000954 patent/WO2005110635A1/en not_active Application Discontinuation
- 2004-04-16 CN CNB2004800427571A patent/CN100546733C/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4882922A (en) * | 1986-06-04 | 1989-11-28 | Clecim S. A. | Rolling mill roll with rotating shell |
US5967957A (en) * | 1995-07-26 | 1999-10-19 | Eduard Kusters Maschinenfabrik Gmbh & Co. | Roller assembly with internal supporting elements |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10677286B2 (en) | 2016-05-26 | 2020-06-09 | Flender-Graffenstaden S.A.S. | Hydrodynamic bearing with injectors and deflectors |
Also Published As
Publication number | Publication date |
---|---|
WO2005110635A1 (en) | 2005-11-24 |
EP1740326A1 (en) | 2007-01-10 |
CN1984728A (en) | 2007-06-20 |
CN100546733C (en) | 2009-10-07 |
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Legal Events
Date | Code | Title | Description |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |