Seal for the neck of a 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, a coil spring (9) wound to form a ring (10) and embedded in the annular body and a pair of radial annular flanges (11,12) made of elastomeric material and integral with the annular body, each being provided with a respective annular sealing lip (13) configured to apply in use a dynamic sliding seal on a fixed annular element (14) of a sealing assembly for the rolling cylinder; in which the coil spring (9) is formed by coils (15) all of which have the same radially flattened shape, so that in an axial section of the coil spring (9) wound into a ring, each coil (15) has a length, measured along an axis (A) about which the coil spring (9) is wound about itself to form the ring (10), greater than the height of the coil (15) measured radially to the winding axis (A).

Description

[0001] SEAL FOR THE NECK OF A ROLLING CYLINDER

[0002] E S C R I PTI O N

[0003] Technical field of the invention

[0004] The present invention relates to a seal for necks of the rolling cylinder. Specifically, the invention relates to a seal for necks of the rolling cylinder configured to create in use a static hydraulic seal on the conical neck of the rolling cylinder and a dynamic hydraulic seal on the outside in a rolling mill for flat products.

[0005] Prior art

[0006] 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 a conical 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).

[0007] When the seal is being arranged in its working position on the cylinder neck, which usually has a frustoconical 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 coil spring to counteract this phenomenon.

[0008] A similar drawback 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 extend radially cantilevered from the side opposite the cylinder neck, on which the seal conversely applies a static seal.

[0009] These drawbacks are not fully compensated for by making the seal from two different elastomeric materials, as provided for in US4099731.

[0010] 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.

[0011] Summary of the invention

[0012] The purpose of the present invention is to provide a seal for a rolling cylinder configured to create in use a hydraulic seal on 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.

[0013] The present invention provides a seal for a rolling cylinder, in particular configured to create in use a hydraulic seal on a cylinder neck of a rolling cylinder in a rolling mill, in particular for flat products, having the features set out in the attached claims.

[0014] More specifically, the invention consists of a combination of a particular shape of coil spring and of the annular body of the seal, which accommodates the coil spring wound into a ring.

[0015] 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.

[0016] Brief description of the drawings

[0017] The invention is described below with reference to the attached drawings showing a non-limiting example embodiment thereof, in which :

[0018] - Figure 1 is a schematic radial sectional view of a seal according to the invention for a rolling cylinder neck, a radial profile of which is also shown only schematically and with dashed lines; - Figure 2 is a scaled-down axial longitudinal view, also only schematic, of an annular spring forming an essential component of the seal in Figure 1;

[0019] - Figure 3 is a magnified three-quarter perspective top view of the spring in Figure 2 in a straightened configuration; and

[0020] - Figure 4 is a schematic view, further magnified, of a detail of a circumferential section of the annular spring in Figure 2, shown for greater clarity in a partially straightened configuration.

[0021] Detailed description

[0022] With reference to Figures 1 to 4, reference sign 1 denotes, as a whole, an annular seal for a known rolling cylinder 2, which is shown for simplicity only schematically, only partially and with hatching.

[0023] 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 either.

[0024] 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.

[0025] The support portion 5 cooperates with an oil-film bearing, which is known and not illustrated for simplicity, which enables the rolling cylinder 3 and the seal 2 to rotate with low friction about an axis A. 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.

[0026] For this purpose, the seal 1 comprises an annular body 8 made of elastomeric material, a coil spring 9 wound / curved to form a ring 10 and embedded in the annular body 8, for example co-moulded with the elastomeric material forming it, and a pair of radial annular flanges 11 and 12, also made of elastomeric material and integral with the annular body 8, for example moulded in one piece therewith.

[0027] The flanges 11 and 12 extend radially cantilevered from the outside of the annular body 8, forming, in radial section as shown in Figure 1, respective cantilevered radial arms of the annular body 8.

[0028] Each cantilevered radial flange or arm 11 and 12 has a respective annular sealing lip 13, of a known type, configured to apply in use a dynamic sliding seal on a fixed annular element 14 (shown with hatching in Figure 1) of a sealing assembly, which is known and not illustrated as a whole for simplicity, for the rolling cylinder 2.

[0029] According to an important aspect of the invention, the coil spring 9 is not formed by circular coils to define a substantially toroidal ring once curved about itself, but is formed by coils 15 (one of which is clearly illustrated in Figure 1, using dashed lines as it is inside the annular body 8) all having the same radially flattened shape, so that in an axial section (as in Figures 1 and 2) of the coil spring 9 wound to form the ring 10, each coil 15 has a length, measured along an axis A about which the coil spring 9 is wound about itself to form the ring 10, greater than the height of the coil 15 measured radially from the winding axis A, specifically perpendicular to the axis A.

[0030] The axis A of curvature, i.e. the winding axis, of the coil spring 9 forming the ring 10 coincides with the axis of rotation of the rolling cylinder 2 and with the axis of symmetry of the ring 10 formed by the set of sequentially arranged coils 15 of the curved spring 9.

[0031] The coil spring 9 of the seal 1 according to the invention is better illustrated in the detail in Figures 2 to 4.

[0032] The coil spring 9 is wound along a circular path about the winding axis A, to form the ring 10, and extends in an axial direction (i.e. parallel to the axis A), between a first front face 16 of the annular body 8, configured to define in use the oil side 4 of the seal 1, and an axial middle portion 18 of the annular body 8 arranged between the pair of radial annular flanges 11 and 12.

[0033] The coils 15 of the coil spring 9 extend axially within (are embedded in) the axial middle portion 18 of the elastomer annular body 8, and are arranged, according to an aspect of the invention, immediately below / at a radially outer lateral surface 19 of the axial middle portion 18 and up to the first flange 11, which is arranged on the water side 6 of the seal 1.

[0034] The axial length of the ring 10 defined by the coil spring 9 wound about the axis A, i.e. the axial length of the coils 15, is such that the spring 9 / the coils 15 do not extend below / to a root portion 20 of the radial flange 11, but do extend along / inside the entire axial middle portion 18 and below / to a root portion 21 of the flange 12.

[0035] According to one aspect of the invention, a given first radial branch 22 (Figures 1-3) of each coil 15 of the coil spring 9 wound into a ring and oriented towards the first front face 16 of the annular body 8 is tangential to respective lubrication grooves 26, which are otherwise known in the prior art and therefore not described in detail.

[0036] According to another aspect of the invention, a given axial branch 23 of each coil 15 of the coil spring 9 wound into a ring and oriented towards the radially outer lateral surface 19 of the axial middle portion 18 of the annular body 8 is arranged substantially flush with the radially outer lateral surface 19. Specifically, the branches 23 of the coils 15 at this point are the radially outer branches of the coils 15.

[0037] According to another aspect of the invention, the seal 1 also includes an annular band 27 forming a cylindrical sleeve and arranged radially inside the spring 9, in direct contact with the latter, at the axial middle portion 18. The annular band 27 extends over most of the radially outer lateral surface 19 and up to a second radial branch 25 (Figure 2) of each coil 15 of the coil spring 9 wound about the axis A to form the ring 10.

[0038] The radial branch 25 is opposite the corresponding first radial branch 22 of the same coil 15.

[0039] The annular band 27 is made of a metal material, preferably spring steel, and can be co-moulded with the annular body 8 together with the coil spring 9, making it integral therewith.

[0040] According to a preferred embodiment, shown in a non-limiting illustration in Figures 2 and 4, the coil spring 9 is wound to form the ring 10 on the annular band 27, which forms a cylindrical sleeve, which is inserted through all the coils 15 of the coil spring 9.

[0041] In essence, each coil 15 is, in the example shown, substantially resting on the cylindrical sleeve / annular band 27 with its radially outer axial branch 23 arranged immediately below or substantially flush with the radially outer lateral surface 19 delimited between the pair of annular flanges 11 and 12.

[0042] The coil spring 9 (Figure 3) has, before being wound into a ring about the axis A, first and second opposing ends 28 and 29, which are essentially hook-shaped and defined by incomplete coils 15.

[0043] These ends 28 and 29 are arranged on top of one another once the spring 9 is wound about the entire external diameter of the annular band / cylindrical sleeve 27.

[0044] The ends 28 and 29 therefore overlap and are hooked together when the spring 9 is wound about the axis A, so that they intersect across at least one complete coil 15b. In the example shown in Figure 4, two complete coils 15b are blocked between the two ends 28 and 29.

[0045] The axial length of the cylindrical sleeve 27 (along the axis A, which is also its axis of symmetry) is preferably less than the axial length of the coils 15 of the coil spring 9 and is arranged substantially against the radial branch 25 of each coil 15 of the spring 9 wound into a ring, which is the branch oriented towards the water side 6, as mentioned above.

[0046] According to one aspect of the invention, the coil spring 9 consists of a plurality of coils 15 made by repeated bending of a given continuous metal wire 30, preferably made from a spring steel, having a circular (preferable) or prismatic cross-section.

[0047] The metal wire 30 is bent so that each coil 15 has an elongated shape in the direction of the winding axis A of the coil spring 9 curved to form the ring 10. This shape is chosen, according to one aspect of the invention, from the group consisting of rectangular, trapezoidal, oval, elliptical, a combination thereof.

[0048] A rectangular shape, with rounded corners, as shown in Figures 3 and 4, is preferred. According to an embodiment not illustrated for simplicity, if the coils 15 are trapezoidal, which may also be preferred depending on the circumstances, the major base of the trapezium formed by the coils 15 is defined by the branches 22 and the height by the branch 23 and a respective branch facing it and oriented towards the axis A, which is not parallel to the branch 23, as with the rectangular form, but oblique with respect to the axis A, and specifically oriented towards the axis A from the face 16.

[0049] According to further aspects of the invention, the annular body 8 is delimited, towards the axis A, by a radially inner side wall 31 opposite the radially outer lateral surface 19. The side wall 31 is configured to form, in use, a static hydraulic seal with the cylinder neck 3 of the rolling cylinder 2; for example it has ridges or annular sealing lips 32. Furthermore, the side wall 31 is arranged obliquely to the axis A, so that the inside of the annular body 8 is tapered towards the oil side 4.

[0050] A radially inner portion 33 of the axial end of the coils 15 defined by the radial branch 25 of each coil 15 oriented towards the water side 6 is preferably completely embedded in the annular body 8 made of elastomeric material, but almost substantially flush or substantially flush with the radially inner side wall 31 of the annular body 8 (Figure 1). Obviously, if the coils 15 are trapezoidal, the radially inner branch of the coils 15, opposite the branch 23, is arranged with an inclination such as to follow the profile of the side wall 31 and therefore be substantially flush with the side wall 31.

[0051] The novel solution described herein for the production of a seal for the cylinder neck 3 of a rolling cylinder 2 provides four main advantages:

[0052] • the option of moulding all the parts of the seal 1 from a single elastomeric compound. Indeed, the presence of the spring 9 as described, together with the presence of the annular band 27, provides the seal 1 as a whole with sufficient rigidity that the whole annular body 8, the flanges 11 and 12 and the sealing lips 13 can be made from the same elastomeric compound, enabling the compound most suitable for the sealing lips 13 to be selected. These may in any case be provided with an anti-friction coating 34, for example made from a polytetrafluoroethylene;

[0053] • increased rigidity during storage and transport of the seal 1, thus preventing possible damage;

[0054] • distribution of the pressure resulting from assembly of the seal 1 on the cylinder neck 3, which is done by pushing the annular body 8 via a sleeve resting against the front face 16, with a good distribution of the pressure on the various internal points of contact of the seal 1 on the cylinder neck 3; and

[0055] • keeping the two radial arms defined by the flanges 11 and 12 in the correct axial positions to allow the sealing lips 13 to perform the dynamic sealing action optimally.

[0056] However, if it is necessary to further improve the sealing performance of the annular lips 13, in particular when provided with the anti-friction layer 34, in addition to the presence of the spring 9 with axially elongated coils 15, the annular body 8 can be made of a first elastomeric material having a first selected hardness, typically 70 Shore D or greater, while the lips 13 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.

[0057] All of the objectives of the invention are thus achieved.

Claims

C LA I M S1. Seal (1) for a rolling cylinder (2) configured to realize in use a hydraulic seal at a cylinder neck (3) of a rolling cylinder in a rolling mill, particularly a flat product rolling mill, the seal presenting 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 operating portion (7) of the rolling cylinder, the seal (1) comprising an annular body (8) made of an elastomeric material, a coil spring (9) wound to form a ring (10) and embedded in the annular body (8), and a pair of radial annular flanges (11,12), also made of elastomeric material and provided integral in one piece with the annular body (8), from which they project cantilevered radially on the outside of the annular body, forming in radial section respective cantilevered radial arms of the annular body (8), and which are each provided with a respective annular sealing lip (13) 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 the coil spring (9) is formed by coils (15) all having the same radially flattened shape, so that in an axial section of the coil spring (9) wound into a ring, each coil (15) has a length, measured along an axis (A) of winding of the coil spring (9) on itself to form said ring (10), greater than the height of the coil (15) measured radially to the axis of winding.

2. Seal according to claim 1, characterized in that the coil spring (9) wound around said winding axis (A) to form a ring (10), of which said winding axis (A) is the axis of symmetry, extends in an axial direction between a first front face (16) of the annular body (8) configured to define in use the oil side (4) of the seal and an axial middle portion (18) of the annular body disposed between said pair of radial annular flanges (11,12); the coils (15) of the coil spring (9) extending axially within the axial middle portion (18) of the annular body, immediately below a radially outer lateral surface (19) of the axial middle portion(18) and up to a first flange (11) of said pair of radial annular flanges, said first flange (11) being disposed on the water side (6) of the seal.

3. Seal according to claim 2, characterized in that a same first radial branch (22) of each coil (15) of the ring-wound coil spring (9) and facing the first front face (16) of the annular body is arranged substantially flush with said front face (16).

4. Seal according to claim 2 or 3, characterized in that an identical axial branch (23) of each coil (15) of the ring-wound coil spring (9) and facing said radially outer lateral surface (19) of the axial middle portion (18) of the annular body (8) is arranged substantially flush with said radially outer lateral surface(19) of the axial middle portion of the annular body.

5. Seal according to any one of claims 2 to 4, characterized in that it further comprises an annular band (27) conformed as a cylindrical sleeve and extending along most of the radially outer lateral surface (19) of the axial middle portion of the annular body and up to a second radial branch (25) of each coil (15) of the ring-wound coil spring (9) opposite the corresponding first radial branch (22) of the same coil; said cylindrical sleeve shaped annular band (27) being made of a metallic material, preferably a spring steel.

6. Seal according to claim 5, characterized in that said coil spring (9) is wound to form said ring (10) on the cylindrical sleeve formed by said annular band (27), which is inserted passing through all the coils (15) of said coil spring (9), each coil (15) substantially resting on said cylindrical sleeve (27) with a radially outer axial branch (23) thereof arranged immediately below or substantially flush with a radially outer lateral surface (19) of the axial middle portion (18) of the annular body (8) arranged between said pair of annular flanges (11,12).

7. Seal according to claim 6, characterized in that the coil spring (9) has a first and a second end (28,29) that is substantially hook-shaped, defined byincomplete coils, said first and second ends (28,29) being engaged with each other in overlap, so as to intersect straddling at least one complete coil (15); said cylindrical sleeve (27) preferably having an axial extension less than that of the coils (15) of said ring-wound coil spring (9) and being arranged substantially against a radial branch (25) of each coil (15) of the ring-wound coil spring facing said water side (6).

8. Seal according to any of the preceding claims, characterized in that said coil spring (9) is formed by a plurality of coils (15) made of the same continuous metal wire (30), preferably made of spring steel, having a circular or prismatic cross-section and bent so that each coil (15) has an elongated shape in the direction of said winding axis (A) of the coil spring (9) to form said ring (10) and chosen from the group consisting of: rectangular, trapezoidal, oval, elliptical, a combination thereof; a rectangular shape, having rounded vertices, being preferred.

9. Seal according to any one of the preceding claims, characterized in that said annular body (8) is bounded by a radially inner side wall (31) opposed to a radially outer lateral surface (19) of an axial middle portion (18) of the annular body (8) disposed between said pair of annular flanges (11,12) and configured to form in use, a static hydraulic seal with the cylinder neck (3) of the rolling cylinder; a radially inner portion (33) of an axial end of said coils (15) defined by a radial branch (25) of each coil (15) of the ring-wound coil spring facing said water side (6) being arranged completely embedded in the annular body (8) made of elastomeric material and nearly substantially flush or substantially flush with said radially inner side wall (31) of the annular body.

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