Device for sealing roll bearing

Abstract

The invention relates to a device for sealing roll bearings against contaminated cooling water, which also flows away from their end faces during the operation of a roll (1). The invention is characterized in that a gap (15) for a lubricant is sealed between a journal bushing arranged on the journal of the roller and a bearing bushing of a bearing housing (5) arranged coaxially with respect thereto, in which the roller (1) is rotatably mounted. The device for sealing according to the invention is of a multi-part construction; wherein a gap (15) is present between the annular shoulder (7), which is part of the seal, and the second leg (13) of the L-shaped annular profile (11). The annular shoulder (7) has an outflow groove (9) on the outer circumference thereof for discharging cooling water flowing down from the roll (1). In order to prevent the gap (15) and the region downstream of the gap (15) from being contaminated by contaminated cooling water and to prevent the L-shaped annular profile (11) arranged there from failing due to contamination, it is provided according to the invention that the outflow groove (9) must not only have a minimum height but also have a minimum height. The ratio of the height and width of the annular outflow groove to the diameter of the bottom of the outflow groove must be within a predetermined limit.

Description

TECHNICAL FIELD

[0001] The invention relates to a roll bearing sealing device for sealing a bearing for a rolling mill roll, in particular for rolling metal strips, against contaminated cooling water, which during operation of the rolling mill roll flows away at the end face of the rolling mill roll. In particular, a gap for a lubricant is sealed off, which is located between a journal bushing arranged on a journal of the rolling mill roll and a bearing bushing of a bearing housing or mounting, which is arranged coaxially to the journal bushing, in which the rolling mill roll is rotatably supported. BACKGROUND

[0002] Such roll bearing sealing devices are basically known from the prior art, for example from the international patent application WO 2005 / 061 139 A1. In Figure 3 The roll bearing sealing device disclosed in this document is shown in. It is configured to be arranged between an end face 10 of a rolling mill roll 1 and a mounting 5, also referred to as bearing housing, with a corresponding bearing bushing 6, in which the rolling mill roll 1 is rotatably supported with its roll journal 2. The roll bearing sealing device is of a multipart construction. It comprises an annular journal seal 4, which is arranged in front of it on the roll body side with an annular seal 8. The annular seal is fixedly connected with an annular shoulder 7 of the bearing housing 5. A sealing lip 18 of the annular seal is sealingly in contact against the end face of the rolling mill roll. An annular L-shaped profile 11 is fixedly connected with its first leg 12 to the end face 14 of the rolling mill roll 1. The sealing lip 18 of the annular seal is resting against this first leg 12. The annular second leg 13 of the L-shaped annular profile 11 radially further out encompasses the area of the annular seal 8 and the annular shoulder 7. The annular shoulder 7 has on its outer circumference an outwardly open outflow groove 9, which is not or only partially covered by the second leg 13 of the L-shaped annular profile 8.

[0003] In this connection, the document WO 2005 / 061 139 A1 discloses the preamble of claim 1.

[0004] In the document WO 2005 / 061 139 A1, the distance, i.e. the height, of the gap 15 between the annular shoulder 7 and the second leg 13 of the L-shaped profile 11 is considered to be advantageous at 0.5 mm to 1.5 mm. With this gap size, a deflection to be exerted by the rolling mill roll in operation can still be achieved. In addition, it is thereby made possible for the gap (labyrinth) to remain as narrow as possible, so that the contaminated cooling water, if present, can only enter the area of the sealing lip 18 through a path as narrow as possible. This has the positive or advantageous effect that this area is not so quickly contaminated and thus remains more functionally effective.

[0005] This described narrow design of the gap, while it can have the described effect in emergency situations, does not solve the root problem. The problem is that during the rolling operation, contaminated cooling water can accumulate in the run-off trough until it reaches the height of the gap, as it cannot be drained in sufficient quantity. If this happens, then contaminated cooling water can be undesirably sucked or drawn into the gap on the opening side of the gap towards the run-off trough and cause the described problem there.

[0006] The sucking of cooling water into the (annular) gap 15 is caused by two physical effects described below:

[0007] 1. The flow state formed between the second leg of the L-profile and the annular seal or annular shoulder, which is referred to in the literature as Couette flow. Couette flow is a flow driven by moving walls in a narrow gap. In the case of laminar flow, a linear velocity profile is formed between the two walls delimiting the gap. The gap geometry described in the WO document is formed by two cylinders nested in each other, wherein one cylinder wall rotates. Here a special case of the Couette flow occurs, the so-called Taylor-Couette flow. Due to the centrifugal force (rotation), a so-called Taylor vortex is formed, which is perpendicular to the axis of rotation. Due to the vortex topology formed, contaminated cooling water can be transported from one opening side of the gap to the other, i.e. here into the region of the sealing lip 18. Contaminated cooling water can be said to be sucked in unilaterally and is disadvantageously transported through the gap to the seal.

[0008] The lower limit of the Taylor vortex formation can be given by the Reynolds number Re: where: ; ; .

[0009] The Reynolds number must be greater than a certain value: where r represents the average radius of rotation. If this condition is met, the Taylor vortex described above occurs.

[0010] Examination of the devices known for roll sealing here and determination of the Reynolds number using these boundary conditions results, for almost all cases in practice, in a Reynolds number which is higher than the limit on the right side of equation (2). This means that the Taylor vortex described above can be assumed to occur and contaminated cooling water can be undesirably sucked through the gap into the region of the sealing lip 18.

[0011] 2. The second aspect of the same problem, which leads to the transport of possibly contaminated water through the gap, lies in the geometric variation of the time gap geometry as viewed in the circumferential direction. Since the roll neck bearing axis is never exactly concentric with the support roll axis in the operating state, but is misaligned (offset) towards it as a result of external loads, the height profile of the gap formed between the second leg of the L-shaped profile and the annular seal or annular shoulder is not uniform in the circumferential direction. There is a circumferential region in which the gap narrows, and there is also a circumferential region in which the gap widens. In the region in which the gap widens, possibly contaminated water is sucked in, and in the opposite region in which the gap narrows, it is squeezed out. This behaviour is similar to that of a plain bearing. When it is squeezed out, the possibly contaminated water is pressed into the region of the seal, which according to the disclosure of document WO 2005 / 061179 A1 should not be contaminated.

[0012] In order to prevent the ingress of possibly contaminated water into the vicinity of the gap between the second leg of the L-shaped profile and the annular seal or annular shoulder, document WO 2005 / 061139 A1 itself proposes the use of the outflow groove 9 disclosed therein at the outer periphery of the annular shoulder.

[0013] However, investigations have shown that the outflow groove at the outer periphery only fulfils its intended purpose if it meets certain dimensions. SUMMARY

[0014] It was therefore the object underlying the present invention to dimension the outflow groove at the outer periphery of the annular shoulder such that the gap, in particular at its inlet opening towards the outflow groove, and the region downstream of the gap between the end face of the roll body and the annular seal, is as far as possible prevented from being contaminated by contaminated cooling water.

[0015] This object is achieved by the subject matter of claim 1. According to this, the minimum height Hmin of the outflow groove is Hmin = 1.55 mm, and in addition the ratio of the height H and the width B of the outflow groove to the diameter D of the bottom of the outflow groove lies within the following limits , where the outflow coefficient K A = 0.00985 mm 3 / mm 2 and all dimensions are in [mm]; and H > Hmin.

[0016] This claimed physical relationship results from theoretical investigations and practical experience. The outflow channel thus dimensioned is considered to be optimal, in particular dimensioned sufficiently large to prevent contaminated cooling water from accumulating to the height of the inlet opening of the gap, and thus effectively to prevent the cooling water from being sucked into the gap as a result of the two effects described above. BRIEF DESCRIPTION OF DRAWINGS

[0017] The description is accompanied by three figures, in which

[0018] Figure 1 An outflow groove according to the application is shown in an enlarged cross-sectional view;

[0019] Figure 2 The lower and upper limits of the ratio claimed are shown; and

[0020] Figure 3 A roll chock sealing device according to the prior art is shown. DETAILED DESCRIPTION

[0021] The application is described in detail below in the form of examples with reference to the figures mentioned. In all the figures, identical technical elements are denoted by identical reference numerals.

[0022] The roll chock sealing device according to the application is based on the roll chock sealing device according to Figure 3 which is shown in the figure. Reference is made to the description of the prior art above and to the international patent application WO 2005 / 061 139 Al for a description thereof. The description also applies to the device according to the application, with the exception of the differences and additions described below.

[0023] As mentioned, the application relates to a special design of the outflow groove 9, which is in Figure 1 cross-sectional and enlarged view in the figure. It can be seen that the annular shoulder 7 is annular, and that the outflow groove 9 is configured on the outer circumference thereof. The bottom of the annular sealing element has a distance from the centre axis of the annular shoulder 7, which also corresponds to the centre axis of the roll journal 2 when the annular shoulder 7 is fitted on the roll journal 2, which distance is of the size of the diameter D. It can be seen that the left limiting wall of the outflow groove 9 is covered by the second leg 13 of the L-shaped annular profile 1 1, wherein a gap 15 is formed between the two elements. The reference numeral 12 denotes the first leg of the L-shaped annular profile 1 1, which is fixedly fitted on the end face of the roll body. The height H of the outflow groove more precisely denotes the distance between, for example, the bottom of the outflow groove 9 and the lower side of the second leg 13. The minimum height Hmin is the minimum value of this distance; H ≥ Hmin is satisfied. The reference numeral B denotes the width of the outflow groove 9.

[0024] The contribution of the inventor is that it has been realized that, in addition to the minimum height Hmin of the outflow groove, the ratio of the height H and the width B relative to the diameter D must lie within a certain range in order for the roll chock sealing device according to the application to fulfil its intended purpose.

[0025] If the ratio is too small, then the possibly contaminated cooling water accumulates at the gap 15 between the second leg 13 of the L profile 11 and the ring seal 8 and can be sucked into the gap by the two effects described above. The sucked-in contaminants cause an undesirable clogging in the gap and impede the function of the sealing lip in the downstream region.

[0026] If the ratio of the width B and the height H to the diameter D is too large, then the flow velocity of the flowing-off cooling water in the channel flow in the run-off groove 9 is so small that scale or dirt residues from the rolling process cannot be flushed away. These residues adhere ("sinter") in the run-off groove 9 due to their reactivity (corrosion, etc.) and cause the run-off groove to clog after a short operating time, i.e. additional run-off resistance is created; the run-off groove can no longer fulfill its original task of providing a sufficiently large discharge area for the possibly contaminated cooling water. In this case, the possibly contaminated cooling water also accumulates to the height of the gap 15 between the second leg 13 of the L profile 11 and the ring seal or the ring shoulder 7 and is sucked into the gap 15 and disadvantageously into the sealing system due to the two effects described above.

[0027] Theoretical studies and practical experience show that a minimum height Hmin = 1.55 mm must be present and the ratio of the height H and the width B to the diameter D must lie within the following limits: (1) where the run-off coefficient K A = 0.00985 mm 3 / mm 2 and all dimensions are in mm; and H > Hmin.

[0028] From this, such a run-off groove 9 is considered to be optimal, i.e. neither too small nor too large according to the criteria described above.

[0029] Figure 2 The value range is shown, within which the claimed ratio according to formula (1) is allowed to lie, the lower limit being 0.1 and the upper limit being 120. List of reference signs: 1 roll 2 roll journal 3 journal bushing 4 journal seal 5 mounting 6 bearing bushing 7 ring shoulder (bearing shoulder) 8 ring seal 9 run-off groove 10 end face 11 L-shaped ring profile 12 first leg 13 second leg 15 gap 18 sealing lip B width D diameter of the annular outflow groove at its bottom Hmin minimum height; minimum value of H H height of the outflow groove.

Claims

1. A device for sealing a roll bearing, the roll bearing having a bearing housing (5), the roll (1) being rotatably supported in the bearing housing by a roll journal (2), the device comprising: Journal seal (4); An annular seal (8) is located on the roller body side, positioned in front of the journal seal (4), and has a sealing lip (18). An annular shoulder (7) is arranged in the axial direction in front of the bearing housing (5), the annular seal (8) is fixedly connected to the annular shoulder, and the annular shoulder has a surrounding, outwardly open outflow groove (9) on its outer periphery. in, An annular profile (11) with an L-shaped cross-section is provided, the annular profile having a first leg (12) and a second leg (13); The annular profile (11) is fixedly connected to the end face (10) of the roll (1) via its first leg (12); The sealing lip (18) of the annular seal (8) abuts against the side of the first leg (12) away from the roller body in a sealing contact; and The second leg (13) of the L-shaped annular profile (11) covers and surrounds the area of ​​the annular shoulder (7) and the annular seal (8), forming a gap (15) and sealing towards the roller body; Its features are, For the minimum height Hmin of the outflow groove (9), the following holds: Hmin = 1.55 mm; and The ratios of the height H and width B of the outflow channel (9) relative to the diameter D of the bottom of the annular outflow channel are within the following limits. （1） Wherein, the outflow coefficient K A =0.00985mm 3 / mm 2 And all dimensions are in [mm]; and H ≥ Hmin.

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