Seal for a rolling mill cylinder and sealing assembly for a related rolling cylinder

Abstract

Annular seal (1) for a cylinder neck (3) of a rolling cylinder (2) including an annular body (8) made of elastomeric material, carrying two respective annular lips (13b,c) configured to apply a dynamic sliding seal in use on a fixed annular element (14) of a sealing assembly (17) for the rolling cylinder; in which each lip (13b,c) includes an annular root portion (19), an annular middle portion (20) carried obliquely cantilevered by the root portion, an annular head portion (21) carried cantilevered by the annular middle portion (20) and having an annular sealing ridge (22) and an annular stiffening rib (24) opposite the annular ridge, and an annular hinge portion (26) configured to allow a relative rotation between the root portion (19) and the middle portion (20) to determine a double hydraulic sealing contact against the fixed annular element (14), by means of the annular ridge (22) and an extrados stretch (25) of the annular middle portion (20).

Description

[0001] SEAL FOR A ROLLING MILL CYLINDER AND SEALING ASSEMBLY FOR A

[0002] RELATED ROLLING CYLINDER

[0003] D E S C RI PTI O N

[0004] Technical field of the invention

[0005] The present invention relates to a seal for a rolling mill cylinder. Specifically, the invention relates to a seal configured to create in use a hydraulic seal on a cylinder neck of rolling cylinders in a rolling mill for flat products. The invention also relates to a sealing assembly for a related rolling cylinder.

[0006] Prior art

[0007] US4165881 describes a flexible seal and a sealing assembly that uses said seal and is configured for use in rolling mills for flat products, in which the rolling cylinders or rollers are, as is known, mounted on oil-film bearings to allow them to rotate with low friction. Specifically, the seal in US4165881 is configured to be mounted on an end neck of the rolling cylinder, which is a tapered portion of the rolling cylinder that separates the portion of the cylinder intended to cooperate with the products being rolled and is therefore exposed to contaminants such as water and mill scale (water-side cylinder portion), and the support portion of the rolling cylinder, which operates in contact with the lubricating oil (oil-side cylinder portion).

[0008] When the seal is being arranged in its working position on the cylinder neck, which usually has a truncated-cone or curved shape tapering towards the oil side, the seal may be deformed, which may then compromise its correct positioning and / or hydraulic sealing action, notwithstanding the seal in US4165881 being provided with a cylindrical helical spring to counteract this phenomenon.

[0009] A similar problem can also be caused by the axial compression of the seal at the cylinder neck, which could affect the correct position of the radially outer dynamic sealing (sliding) lips of the seal, which are radially cantilevered from the side opposite the cylinder neck, on which the seal conversely applies a static seal.

[0010] These drawbacks are not fully compensated for by making the seal from two different elastomeric materials, as provided for in US4099731. Furthermore, this document only teaches how to make a main annular body of the seal and the sealing lip part thereof from two different elastomers, a stiffer elastomer for the annular body and a softer elastomer for the sealing lips, without providing any guidance on how to select the hardness / stiffness of the elastomers for the specific application.

[0011] Finally, US6729625B2 describes a seal of the above type, in which the dynamically sealing lips are partially coated with an anti-friction substance or plate, which does not however solve the described drawbacks, despite helping to reduce the sliding friction of the dynamic sealing lips.

[0012] Summary of the invention

[0013] The purpose of the present invention is to provide a seal for a rolling cylinder configured to create in use a hydraulic seal at a cylinder neck of a rolling cylinder in a rolling mill, in particular for flat products, which is not affected by the drawbacks described above. The invention is also intended to provide a sealing assembly for a rolling cylinder using such a seal.

[0014] According to the present invention, a seal is provided for a rolling cylinder, in particular configured to create in use a hydraulic seal at a cylinder neck of a rolling cylinder in a rolling mill, in particular for flat products, and a related sealing assembly for a rolling cylinder, having the features set out in the attached claims.

[0015] More specifically, the invention consists of the specific shape of the sealing lips, which can compensate for any incorrect positioning of the radially outer dynamic sealing lips resulting from deformation of the seal as a whole caused by misalignment or deformation, as mentioned above.

[0016] If necessary, an appropriate hardness may also be selected for the elastomeric material used to form the annular body containing the spring and / or the radial arms or appendages carrying the dynamic sealing lips.

[0017] Brief description of the drawings

[0018] The invention is described below with reference to the attached drawings showing a non-limiting example embodiment thereof, in which :

[0019] - Figure 1 is a schematic radial sectional view of a seal according to the invention for a cylinder neck of a rolling cylinder, showing a radial profile, for simplicity only schematically and with a dashed line, the seal according to the invention being shown with a component thereof, which can vary, as detailed below, and which is indicated only schematically by a block;

[0020] - Figure 2 is a highly magnified radial sectional view, also only schematic, of a dynamic sliding sealing lip from Figure 1;

[0021] - Figure 3 is a magnified schematic radial sectional view of a detail of the seal in Figure 1;

[0022] - Figure 4 is a schematic, further magnified view of a radially outer part of the same detail as Figure 3 and a portion of a component of a sealing assembly for a rolling cylinder associated with the seal in Figure 1; and

[0023] - Figure 5 is a schematic scaled-down radial sectional view of a sealing assembly for a rolling cylinder according to the invention, including a possible embodiment of the seal in Figure 1.

[0024] Detailed description

[0025] With reference to Figures 1 to 5, reference sign 1 denotes, as a whole, an annular seal for a known rolling cylinder 2, which is shown for simplicity in Figure 1 only schematically, only partially and with a dashed line, and a corresponding axial portion thereof is shown in Figure 5.

[0026] The seal 1 is configured to create in use a hydraulic seal at a cylinder neck 3 of the rolling cylinder 2 in a rolling mill, in particular a rolling mill for flat products, which is known and not shown for simplicity.

[0027] The seal 1 has an oil side 4, oriented in use towards a known support portion 5 of the rolling cylinder 2, and a water side 6 oriented in use towards an operational portion 7 of the rolling cylinder 2.

[0028] The support portion 5 cooperates with an oil-film bearing, which is known and not illustrated for simplicity, which enables the rolling cylinder 2 to rotate with low friction about an axis A (Figure 1). The operational portion 7 is intended to cooperate with the products to be rolled, and therefore is the portion that is exposed in use to contaminants such as water and mill scale, which could move towards the oil-film bearing. The seal 1 therefore has the dual function of providing a hydraulic seal for the oil, on the oil side 4, to prevent it from leaking outwards, specifically to the water side 6, and a hydraulic seal against any contaminants moving from the water side 6 to the oil side 4.

[0029] Forthis purpose, the seal 1 comprises an annular body 8 made of elastomeric material, and an elastic stiffening element 9 for the annular body 8 (shown in Figure 1 only schematically by a block) embedded in an axial middle portion or central axial portion 18 of the annular body 8.

[0030] In preferred embodiments of the invention, the elastic stiffening element consists of a helical spring 9 wound / curved about the axis A, forming a ring 10, for example a toroidal ring. Figure 5 shows a non-limiting possible embodiment of the helical spring 9 wound about the axis A to form the ring 10 coaxial with the axis A.

[0031] In any case, the spring or elastic stiffening element 9 is embedded in the annular body 8, and is for example co-moulded with the elastomeric material forming the annular body 8.

[0032] The seal 1 also comprises a pair of radial annular flanges 11 and 12, which are also made of elastomeric material and are integral with the annular body 8, for example moulded in one piece with the annular body. The flanges 11 and 12 delimit the axial middle portion 18 of the annular body 8 on opposite sides.

[0033] The flanges 11 and 12 extend radially cantilevered from the outside of the annular body 8, forming, in radial section such as that shown in Figure 1, respective cantilevered radial arms of the annular body 8.

[0034] Each cantilevered radial arm or flange 11 and 12 is provided with a respective annular sealing lip, respectively a first lip 13b extending radially cantilevered, as shown, from the flange 11 and a second lip 13c extending radially cantilevered from the flange 12, on the side opposite the lip 13b.

[0035] The lips 13b and 13c are configured to apply in use a dynamic sliding seal on a fixed annular element 14 (shown with a dashed line in Figure 1 and in detail in Figure 5) of an annular sealing assembly 17 (Figure 5) for the rolling cylinder 2, arranged at its cylinder neck 3, to protect a respective oil-film bearing supporting the cylinder 2, which is known and not shown in its entirety for simplicity.

[0036] The sealing assembly 17 is positioned radially about the outside of the cylinder neck 3, between the oil side 4 and the water side 6 of the seal 1, which also define a corresponding operational oil side and an operational water side of the sealing assembly 17.

[0037] The first and second annular sealing lips 13b and 13c are elastically deformable, are made of an elastomeric material, and are integral with the annular body 8 as a whole.

[0038] According to a first aspect of the invention, the lips 13b and 13c are similar in shape, but symmetrically opposite, so that in a radial section such as the one in the attached Figures 1 to 5, they have the same axially oriented V shape, i.e. having the vertex arranged parallel to the axis A of symmetry, but with the vertices oriented in opposite directions, specifically the vertex of the V of the lip 13b is oriented towards the water side 6 and the vertex of the V of the lip 13c is oriented towards the oil side 4.

[0039] In more detail, each first and second annular lip 13b and 13c, respectively, comprises an annular root portion 19 extending radially cantilevered from the respective flange 11 and 12. According to one aspect of the invention, the root portions 19 of the lips 13b and 13c taper radially outwards, the thickness thereof measured axially (i.e. along the axis A), thinning radially outwards.

[0040] Furthermore, each first and second annular lip 13b and 13c, respectively, comprises an annular middle portion 20 carried radially cantilevered by the annular root portion 19 radially on the outside thereof and oriented obliquely to the root portion 19, so that the annular middle portion 20 of the first lip 13b extends cantilevered on the water side 6, while the annular middle portion 20 of the second lip 13c extends cantilevered on the oil side 4.

[0041] Finally, each first and second annular lip 13b and 13c respectively comprises an annular head portion 21 carried radially cantilevered by the annular middle portion 20 on the opposite side to the root portion 19, constituting the actual hydraulic seal portion of the respective annular lip 13b, 13c.

[0042] For this purpose, each head portion 21 in turn comprises an annular ridge 22 radially defining on the outside a sealing edge 23, which defines the radially outermost diameter of the respective lip 13b, 13c and is configured to cooperate in use, forming a fluid-tight contact, with the fixed annular element 14 of the sealing assembly 17, as shown. Each head portion 21 also comprises an annular stiffening rib 24 (Figures 2 and 4), shaped in radial section as a wedge with a rounded vertex, extending cantilevered from the rest of the respective lip 13b, 13c on the side opposite the annular ridge 22, and on the side opposite an annular extrados stretch 25 of the annular middle portion 20.

[0043] Hereinafter, "extrados stretch" means an annular surface stretch 25 that laterally delimits the annular portion 20 radially on the outside thereof.

[0044] The annular ridge 22 is also configured in such a way that the sealing edge 23 is arranged substantially flush with, but removed from, the extrados stretch 25 of the corresponding annular middle portion 20 of the same lip 13b or 13c.

[0045] Each annular lip 13b, 13c also comprises a first annular hinge portion 26 (Figures 2 and 4) which elastically connects the annular root portion 19 of each lip 13b, 13c with the respective annular middle portion 20. In Figure 4, the relative centre of rotation in the hinge portions 26 between the cantilevered radial annular portions 19 and 20 that is defined / formed by each hinge portion 26 is shown by a dot, by way of example and not to scale. According to an important aspect of the invention, the first annular hinge portion 26 of each annular lip 13b, 13c is also configured to allow in use the annular middle portion 20, i.e. the seal 1 mounted on the cylinder neck 3 as part of the sealing assembly 17, to rotate relatively towards the root portion 19, thereby determining continuously, i.e. in all operating conditions of the seal 1, a double hydraulic seal contact of the seal 1 against the fixed annular element 14 of the sealing assembly 17, simultaneously by means of the annular ridge 23 and by means of at least part of the extrados stretch 25 of the annular middle portion 20 of each lip 13b, 13c.

[0046] According to the preferred embodiments, the root portion 19 of each lip 13b, 13c is configured in such a way that its thickness measured in the axial direction is progressively reduced, radially towards the outside, continuously, and thus each annular root portion 19 is axially delimited by two radial frustoconical surfaces converging towards each other.

[0047] Furthermore, according to an aspect of the invention already mentioned above, the root portion 19 of each sealing lip 13b, 13c is arranged obliquely to the respective flange 11, 12 and with an inclination opposite to the inclination of the respective annular middle portion 20, thereby providing the lips 13b, 13c, in radial section, with axially arranged opposing V shapes, with the respective vertices of the V shapes oriented towards each other.

[0048] Preferably, the subtended angle between the annular portions 19 and 20 of each lip 13b, 13c is an angle close to 90° and even more preferably an acute angle.

[0049] According to a preferred aspect of the invention, each first and second sealing lip 13b and 13c also comprises a second annular hinge portion 27 (Figures 2 and 4) which elastically connects the annular middle portion 20 with the annular head portion 21, also shown in Figure 4 as a dot representing the centre of rotation, by way of example only and not to scale.

[0050] The hinge portion 27 is configured to allow the annular head portion 21 to rotate in use relative to the annular middle portion 20 to help maintain a constant double hydraulic seal contact against the fixed annular element 14, while simultaneously keeping both the sealing edge 23 and at least part of the extrados stretch 25 in contact with the latter.

[0051] According to a preferred aspect of the invention, the extrados stretch 25 of the intermediate portion 20 of each of the first and second sealing lips 13b, 13c is coated at least in part with an anti-friction layer 28 having a low coefficient of friction.

[0052] The anti-friction layer 28 preferably completely covers the entire extrados stretch 25 of the annular middle portion 20 of each first and second sealing lip 13b, 13c.

[0053] The anti-friction layer 28 is preferably made of a composite material comprising bronze and mainly polytetrafluoroethylene (PTFE). In essence, the antifriction layer 28 consists of a composite coating or plate comprising 40% bronze and 60% PTFE.

[0054] According to further features of the invention, a metal annular band 29, preferably made of spring steel and co-moulded integral with the annular body 8, is fastened to the radial outside of the axial middle portion 18.

[0055] With reference to Figure 5, according to preferred embodiments of the invention, the elastic stiffening element 9 of the annular body 8 does not consist of a conventional helical spring annularly wound about itself about the axis A of symmetry, essentially forming a three-dimensional toroidal structure, but instead consists of a helical spring 9 that, while still annularly wound about the axis A to form a ring 10 of which the axis A is simultaneously the axis of symmetry and the axis of winding / curvature of the spring 9, but formed by a plurality of coils 15 (Figure 5) arranged radially in series with each other, which have an elongated shape in the direction of the axis A of symmetry, which is also the axis of annular winding of the helical spring 9, so that the axial extension of each coil 15 is greater than its radial extension.

[0056] In the non-limiting example shown, the coils 15 have, in radial section, a trapezoidal shape with the major base oriented towards the oil side 4, but other shapes are possible, such as rectangular, or oval or elliptical.

[0057] Also according to the preferred embodiments, an axial branch of each coil 15, specifically the radially outermost branch, extends under the entire metal annular band 29 (Figure 5) and under the second annular flange 12, and a radial branch of each coil 15, in the example shown defining the major base of the trapezium formed by each coil 15, extends inside the annular body 8 until substantially flush with a front face 16 of the annular body 8 delimiting the oil side 4 of the seal 1 or in any case oriented towards the oil side 4 of the sealing assembly 17.

[0058] According to one possible aspect of the invention, to further improve the sealing performance of the annular lips 13b and 13c, in particular when provided with the anti-friction layer 28, in addition to the described shape of the lips themselves, the overall stiffness of the seal 1 is also improved not only by the presence of the spring 9 with axially elongated coils 15, but simultaneously because the annular body 8 can be made of a first elastomeric material having a first selected hardness, typically 70 Shore D or higher, while the lips 13b and 13c and optionally the radially outer ends of the flanges 11 and 12, can be made from a second elastomeric material having a second selected hardness that is less than the first selected hardness, for example equal to or not less than 50 Shore D.

[0059] Finally, it is clear from the above that the invention also relates to a sealing assembly 17 for a rolling cylinder 2, the sealing assembly 17 being configured to create a hydraulic seal in use at a cylinder neck 3 of the rolling cylinder 2 in a rolling mill, in particular a rolling mill for flat products, between an oil side 4, oriented in use towards a support portion 5 of the rolling cylinder, and a water side 6 oriented in use towards an operational portion 7 of the rolling cylinder 2. According to the invention, this sealing assembly 17 comprises an annular seal 1 as described above, a fixed annular element 14 which is substantially rigid and arranged radially on the outside of the annular seal 1 and an annular sealing element 30 carried integrally on the front of the fixed annular element 14, on the side thereof oriented towards the water side 6, that is configured to cooperate slidingly with a front face of the operational portion 7 of the rolling cylinder 2, radially outside the annular seal 1.

[0060] The fixed and substantially rigid annular element 14 (Figure 4) is provided, towards the seal 1, with a first and second radially inner lateral sliding surface, specifically denoted by the reference signs 31 and 32, configured respectively to cooperate slidingly with the first annular lip 13b and the second annular sealing lip 13c. The sliding surfaces 31 and 32 are also schematically shown with a dashed line in Figure 3.

[0061] According to one aspect of the invention, the first and second sliding surfaces 31 and 32 are axially separated from each other by a radial flange 33 of the fixed annular element 14. The flange 33 extends radially cantilevered inside the fixed annular element 14, between the first and second elastomer flanges 11 and 12 of the annular body 8 of the seal 1, facing both.

[0062] The sealing assembly 17 also comprises an annular shoulder member 35 (Figure 5), configured to be rotationally fixed in use to the rolling cylinder 2, radially between the annular sealing element 30 and the annular seal 1.

[0063] The annular seal 1 is also configured to be rotationally fixed to the rolling cylinder 2, in order to cooperate with a static hydraulic seal on the cylinder neck 3, by means of a radially inner lateral surface 36 of the elastomer annular body 8 provided with (Figure 1) a plurality of sealing ridges 37 and at least one sealing lip 38 extending obliquely cantilevered towards the front face 16 of the annular body 8 delimiting it on the oil side 4.

[0064] The annular seal 1 also comprises a frontal annular static hydraulic sealing lip 39 (Figures 1 and 5), which extends axially cantilevered from the annular body

[0065] 8 on the side opposite the front face 16 delimiting the annular body 8 on the oil side 4.

[0066] In combination, the annular shoulder member 35 is shaped in radial section as a circular channel with a concavity oriented towards the seal 1 and configured to cooperate with the frontal annular lip 39 of the annular seal 1 to press it in use against the cylinder neck 3, the radially inner edge 40 thereof (Figure 5) being inserted into the fixed annular element 14.

[0067] Finally, according to a significant aspect of the invention, the first and second elastomer flanges 11 and 12 of the annular seal 1 and / or the respective first and second annular sealing lips 13b, 13c are configured in such a way that the sealing edge 23 of the annular ridge 22 of the first lip 13b has a smaller diameter than the sealing edge 23 of the annular ridge 22 of the second lip 13c. In combination with this, the first sliding surface 31 is arranged further inwards radially than the second sliding surface 32. This asymmetry makes it possible to further compensate for positioning errors of the sealing lips 13b, c caused by assembly stresses and / or axial pressures acting on the cylinder neck 3.

[0068] For the same reason, the first sliding surface 31 is defined by a radially internal cylindrical lateral surface of the fixed annular element 14 which is slightly eccentric in relation to the axis A of symmetry of the annular body 8 of the seal 1, where "slightly" means an eccentricity of a few tenths of a millimetre. In particular, the eccentricity of the sliding surface 31 in relation to the axis A and in relation to the cylindrical sliding surface 32 is between 7 and 8 tenths of a millimetre.

[0069] The novel solution described herein for the production of a seal 1 for the cylinder neck 3 of a rolling cylinder 2 provides three main advantages:

[0070] • the double contact means that the contact force of the seal 1 against the stationary element 14 is shared and reduced;

[0071] • the contact with the PTFE or PTFE / bronze anti-friction layer 28 mainly allows the forces to be carried on the extrados stretch 25 with less friction, thereby reducing the phenomenon of hardening of the rubber lip 13 due to heat, guaranteeing a better seal; and

[0072] • the service life of the sealing lip 13 is extended considerably. All of the objectives of the invention are thus achieved.

Claims

C LA I M S1. Annular seal (1) for a rolling cylinder (2), the seal presenting an oil side (4) and a water side (6) and comprising an annular body (8) made of an elastomeric material having an axis of symmetry (A), an elastic stiffening element (9) arranged embedded in an axial middle portion (18) of the annular body (8) bounded between a first and a second radial annular flange (11,12) made of elastomeric material, obtained integral with the annular body (8) and provided, respectively, with a first and a second elastically deformable annular sealing lip (13b, 13c) made of elastomeric material, configured to exert in use a dynamic sliding seal on a fixed annular element (14) of a sealing assembly serving the rolling cylinder (2); characterized in that each first and second annular lip (13b, 13c) comprises:(a) an annular root portion (19) extending radially cantilevering from a respective said flange (11,12);(b) an annular middle portion (20) arranged oblique to the axis of symmetry (A) and cantilevering radially on the outside from the respective annular root portion (19), the annular middle portion (20) of the first lip (13b) extending cantilevered to the water side (6) and the annular middle portion (20) of the second lip (13c) extending cantilevered to the oil side (4) and including an extrados stretch (25) facing away from the axis of symmetry (A);(c) an annular head portion (21) carried radially cantilevered from the annular middle portion (20) and comprising in turn a radially outer annular ridge (22), one sealing edge (23) of which is configured to cooperate in use with the fixed annular element (14), and an annular stiffening rib (24) extending cantilevered from the side opposite to the annular ridge (23) and the extrados stretch (25) of the annular middleportion (20); and(d) a first annular hinge portion (26) that elastically connects the annular root portion (19) with the annular middle portion (20), and configured to allow in use the annular middle portion (20) to rotate relatively towards the root portion (19) resulting in a constant double hydraulic seal contact against the fixed annular element (14), simultaneously by means of the annular ridge (22) and at least part of the extrados stretch (25) of the annular middle portion.

2. Seal according to claim 1, characterized in that said root portion(19) is configured so that it tapers radially outwardly, thinning radially outwardly a thickness thereof measured in the axial direction, said thickness measured in the axial direction preferably tapering progressively, radially outwardly; and by the fact that said sealing edge (23) of the annular ridge of each of the first and second lips is arranged substantially flush with, but spaced apart from, the extrados stretch (25) of the corresponding annular middle portion of the same lip.

3. Seal according to claim 1 or 2, characterized in that each of the first and second sealing lips (13b, 13c) further comprises a second annular hinge portion (27) elastically connecting the annular middle portion (20) with the annular head portion (21) and configured to allow in use the annular head portion (21) to rotate relative to the annular middle portion(20) to constantly contribute to maintain a double hydraulic seal contact against said fixed annular element (14); the root portion (19) of each first and second sealing lip (13b, 13c) being arranged obliquely to the respective first and second flanges (11,12) and at an angle opposite to that of the respective annular middle portion (20).

4. Seal according to one of the preceding claims, characterized in that said extrados stretch (25) of the middle portion of each of the first andsecond sealing lips (13b, 13c) is coated at least in part with an anti-friction layer (28) having a low coefficient of friction.

5. Seal according to claim 4, characterized in that said anti-friction layer (28) completely covers the extrados stretch (25) of the annular middle portion (20) of each first and second sealing lip.

6. Seal according to claim 4 or 5, characterized in that said antifriction layer (28) is made of a composite material including bronze and polytetrafluoroethylene, with predominance of the latter.

7. Seal according to any of the preceding claims, characterized in that said axial middle portion (18) bears radially on the outside, attached to it, a metal annular band (29), preferably made of a spring steel; and in that said elastic stiffening element (9) of the annular body (8) consists of a helical spring (9) wound on itself in a ring fashion around said axis of symmetry (A), the helical spring being formed by a plurality of coils (15) arranged radially to each other in series, which have an elongated shape in the direction of said axis (A) of symmetry, which is also the axis of winding of the helical spring (9) to a ring, so that the axial extension of each coil (15) is greater than its radial extension; and in that an axial branch of each coil (15) extends under all of said metal annular band (29) and all the way under said second annular flange (12), and a radial branch of each coil (15) extends within the annular body (8) up to substantially flush with a front face (16) of the annular body bounding said oil side (4) of the seal.

8. Sealing assembly (17) for a rolling cylinder (2) configured to realize in use a hydraulic seal at a cylinder neck (3) of the rolling cylinder in a rolling mill, in particular a flat-product rolling mill, between an oil side (4) facing in use towards a support portion (5) of the rolling cylinder, and a water side (6) facing in use towards an operational portion (7) of the rolling cylinder, characterized in that it comprises: an annular seal (1)according to one of claims 1 to 7; a stationary and substantially rigid annular element (14) arranged radially on the outside of the annular seal (1) and provided towards the latter with a first and a second radially inner lateral sliding surface (31,32) for, respectively, said first and second annular sealing lips (13b, 13c), said first and second sliding surfaces (31,32) being axially separated from each other by a flange (33) of the stationary annular element (14) extending radially cantilevered within the same and between said first and second flanges (11,12) of the annular body (8) of the seal, facing both; an annular sealing element (30) carried integral with and frontally from the stationary annular element (14), on the water side (6) and configured to cooperate in sliding manner with a front face of the operational portion (7) of the rolling cylinder, radially outside the annular seal (1) and an annular shoulder member (35) configured to be keyed angularly integral in use with the rolling cylinder (2), radially between said annular sealing element (30) and said annular seal (1), the latter being configured to be also keyed angularly integral with the rolling cylinder (2), cooperating with a static hydraulic sealing action on the cylinder neck (3) by means of a radially inner lateral surface (36) of the annular elastomeric body (8) provided with a plurality of sealing ridges (37) and by at least one sealing lip (38) extending obliquely cantilevered towards a front face (16) of the annular body (8) delimiting the same on the oil side (4).

9. Sealing assembly (17) according to claim 8, characterized in that the annular seal (1) further comprises a frontal annular lip (39) for a static hydraulic sealing, extending axially cantilevering from the annular body (8) on the side opposite to said front face (16) of the annular body delimiting the annular body from the oil side (4); said annular shoulder member (35) being further configured to cooperate with the frontal annular lip (39) of the annular seal (1) to press it in use against the cylinder neck, insertingitself with a radially inner edge (40) thereof within said stationary annular element (14).

10. Sealing assembly (17) according to claim 8 or 9, characterized in that said first and second flanges (11,12) of the annular seal (1) and / or respective first and second annular sealing lips (13b, 13c) thereof are configured such that the sealing edge (23) of the annular ridge (22) of the first lip (13b) has a diameter smaller than the sealing edge (23) of the annular ridge (22) of the second lip (13c); and in that, in combination, the first sliding surface (31) is arranged radially further inward than the second sliding surface (32); the first sliding surface (31) being defined by a radially inner cylindrical lateral surface of the stationary annular element (14), which is preferably slightly eccentric to the axis of symmetry (A) of the annular body (8) of the seal by a few tenths of a millimeter.

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