Background of the invention

[0001] The invention relates to a front seal ring and kit, particularly for the front seal of a machine element that rotates with respect to another machine element, more particularly to divide a lubricating side, where a lubricating fluid (oil) operates, from a contaminated side, where various impurities are located that must not contaminate the lubricating side.

[0002] Specifically, but not exclusively, the invention can be usefully applied to make the front seal on rolling apparatuses, particularly on hot rolling cages of a wire-rod train.

[0003] Particularly, reference is made to a seal ring having two opposite front parts, each of which has a seal lip, in which one lip has to make a seal on the contaminated side and the other lip has to make a seal on the lubricating side.

[0004] Front seal rings of this type are already known, used particularly in hot rolling mills, in which the seal lip on the contaminated side has to protect from impurities deriving from rolling of the metal that are particularly abrasive and harmful, including ferrous dust, steel, cooling emulsions, etc. It is noted that in general the emulsions used have no significant lubricating effect on the elastomeric material with which the seal lips are made.

[0005] The aforesaid negative conditions are, normally, very penalising for achieving optimal seal ring performance, especially for relatively high rolling speeds. In practice, with high rolling speeds the average life of the seal rings is significantly reduced.

Summary of the invention

[0006] One object of the invention is to make a seal ring that is able to remedy one or more of the limits and drawbacks of the prior art disclosed above.

[0007] One object of the invention is to improve wear-resistance and the average working life of a front seal ring.

[0008] One advantage is to make available a seal ring that is particularly tough even in critical work conditions, for example for hot rolling mills with high rolling speeds.

[0009] One advantage is to provide a seal ring and/or a seal kit that are suitable, particularly, for a hot rolling mill, with a long average life of the ring and/or of the kit, even if used at high rolling speeds, for example the maximum speeds permitted by modern hot rolling mills.

[0010] One advantage is to provide a seal ring with an opposite double front seal lip that is constructionally simple and cheap. [0011] Such objects and advantages, and still others, are achieved by the seal ring and by the seal kit according to one or more of the claims set out below.

[0012] In one embodiment, a front seal ring, arranged for implementing the opposite front seal between two machine elements, one of which rotates in relation to the other, comprises an annular base body, made of elastomeric material, having a first (front) seal lip on the contaminated side, a second (front) seal lip on the lubricating side and at least one annular coating element (ribbon) made of hardwearing material (for example PTFE) applied to the aforesaid first contaminated sealing lip.

[0013] In one embodiment, a front seal kit, which is arranged for implementing opposite front seal between two machine elements one of which rotates in relation to the other, comprises a seal ring and an annular barrier element; the front seal ring may have a first (front) seal lip on the contaminated side, a second (front) seal lip on the lubricating side and at least one annular coating element (ribbon) made of hardwearing material applied to the first sealing lip on the contaminated side; the annular barrier element may have an annular fixing portion for fixing to a machine element, a (front and/or labyrinth) annular protection portion arranged facing the outside of the first seal lip to protect from impurities present outside and at least one second annular coating element made of hardwearing material applied to the annular protection portion.

Brief description of the drawings

[0014] The invention can be better understood and implemented with reference to the attached drawings that illustrate one embodiment thereof by way of not limiting example.

[0015] Figure 1 is a section of one embodiment of a seal ring made in accordance with the present invention.

[0016] Figure 2 shows an enlarged detail of figure 1.

[0017] Figure 3 shows a section view of the mounting zone of a seal kit, made in accordance with the present invention and comprising a seal ring made in accordance with the present invention in combination with a protection barrier element of the seal ring, in which the kit is mounted on a rolling cage.

[0018] Figure 4 is a section of one embodiment of a protection barrier element made in accordance with the present invention.

Detailed description

[0019] Referring to the aforesaid figures, overall with 1 a front seal ring has been indicated that is made in accordance with the present invention. [0020] The seal ring 1 may be used, for example, to make a suitable seal for a rotating element of a machine, particularly to make a (front) seal in the zone in which the lubricant operates and avoid not only lubricant leaks but also the entry of contaminating agents into the zone of the lubricant. Particularly, the seal ring 1 may comprise two lips 2 and 3 for opposite front seal that have the function of dividing a lubricating zone 4 (see figure 3) from a contaminated zone 5 that is more exposed to machining, containing the various impurities originating from machining (for example rolling, if the seal ring is applied to a rolling cage, as in the embodiment of figure 3).

[0021] The seal ring 1 may comprise, as in this embodiment, an annular base body 6, particularly made of elastomeric material, for example made of a single piece. The base body 6 may have, particularly, a first seal lip 2 on the contaminated side and a second seal lip 3 on the lubricating side. The base body 6 may have, for example, a central portion 7 arranged between the first seal lip 2 and the second seal lip 3. The central portion 7, the first seal lip 2 and the second seal lip 3 are integrated together to form the base body 6.

[0022] The seal ring 1 may comprise, particularly, at least one annular coating element 8 (ribbon or washer) made of a hardwearing material and applied (in an integral manner) to an outer surface of the first seal lip 2 on the contaminated side. The coating element 8 may be, at least partially, made of PTFE. The coating element 8 may be applied in a known manner, for example as disclosed in patent application EP 2278198, with a process that enables the (PTFE) coating element 8 to be coupled to the (rubber) first lip 2 of the seal ring 1 in an integral manner.

[0023] The seal ring 1 may be intended, in use (see figure 3), to be mounted on a first element 9 of a machine (for example a hot rolling cage, as in figure 3). The coating element 8 is intended, in use, for sliding seal contact against a second element 10 of the machine, in which the aforesaid first and second element 9 and 10 rotate reciprocally in relation to one another.

[0024] In the specific case, the first machine element 9 (on which the seal ring 1 is mounted) is the fixed element, whilst the second machine element 10 is the rotating element.

[0025] The coating element 8 may be arranged, as in the specific case, on a step 11 that emerges from the first seal lip 2. The coating element 8 may be arranged tilted in relation to an axis X of the seal ring 1.

[0026] The second seal lip 3 on the lubricating side may be devoid, particularly, of a coating made of hardwearing material. In other words, a coating element made of a hardwearing material, like the (ribbon or washer) element 8, may be applied, particularly, only to the first seal lip 2 on the contaminated side.

[0027] The seal ring 1 may comprise, as in this embodiment, at least one (metal) annular reinforcing element 12 that may be, at least partially, coupled to the central portion 7 of the ring 1. The reinforcing element 12 may be, at least partially, embedded in the central portion 7. The reinforcing element 12 may have, particularly, an L-shaped cross section. The reinforcing element 12 may have, as in this embodiment, an end portion that protrudes radially outside beyond an outer surface of the central portion 7 of the ring.

[0028] The central portion 7 may have, particularly, a maximum thickness that is greater than a maximum thickness of the first lip 2 and/or of the second lip 3. The central portion 7 may have an outer diameter that is less than an outer diameter of the first lip 2 and/or the second lip 3.

[0029] The seal ring 1 may be combined with an annular barrier element 13 to form a front seal kit.

[0030] The annular barrier element 13 may be arranged facing the outside of the first seal lip 2 to protect the latter from impurities.

[0031 ] The annular barrier element 13 (see figure 4) may comprise, particularly, an annular body 14 made of elastomeric material (for example a body made of a single piece), an outer (metal) protection ring 15 and a sliding ring 16 made of hardwearing material.

[0032] The annular barrier element 13 may have, for example, an annular fixing portion 17 intended for being fixed to an outer element (for example within a seat of an element of a rolling cage, for example the second element 10). The annular fixing portion 17 may comprise, as in this embodiment, a portion of the annular body 14. The annular fixing portion 17 may comprise, as in this embodiment, a portion of the protection ring 15.

[0033] The annular barrier element 13 may have, particularly, an annular protection portion 18 (with a labyrinth and/or a slide seal). The annular protection portion 18 may comprise, as in this embodiment, at least one portion (made of a hardwearing material) sliding on a machine element. Particularly, the annular protection portion 18 may comprise, as in this embodiment, at least one portion of the sliding ring 16. The annular protection portion 18 may comprise, as in this embodiment, at least one portion of the annular body 14. The annular protection portion 18 may comprise, as in this embodiment, at least one portion of the protection ring 15. [0034] The outer protection ring 15 may be used, particularly, to protect at least the annular protection portion 18 from attack by abrasive substances.

[0035] The seal ring 1 may be arranged, as in the embodiment of figure 3, to make a front seal (by the first seal lip 2 on the contaminated side) at least against the machine element (in the specific case, the second element 10) on which the annular barrier element 13 is mounted.

[0036] It is possible to arrange the barrier element 13 in such a manner that the protection portion 18 is in sliding contact (through the ring 16) with another machine element, for example the element (in the specific case, the first element 9) on which the central portion 7 of the seal ring 1 is mounted.

[0037] As said, the barrier element 13 may have the sliding ring 16 that gives rise to a coating element made of a hardwearing material and applied to the labyrinth protection portion 18, in the zone intended for the sliding contact with the outer element (first element 9). The sliding ring 16 may be, at least partially, made of PTFE.

[0038] The barrier element 13, particularly owing to the sliding contact against the element 9, is able to reduce significantly the entry of contaminating elements, compared with known solutions that use rings made completely of metal that, in order to avoid damage, have to maintain a certain clearance (for example of 0.1/0.2 mm) with respect to the element 9.

[0039] The (labyrinth and/or sliding) protection portion 18 forms a barrier that contributes to protecting the first seal lip 2 from the contaminated zone 5. The first lip 2, in turn, contributes to protecting the lubricating zone 4.

[0040] Particularly, there is at least one protection chamber 19 defined between the (labyrinth and/or sliding) protection portion 18, the first seal lip 2, the machine element (second element 10) that carries the barrier element 13 and the machine element (first element 9) that carries the seal ring 1. This protection chamber 19 acts as an effective barrier against the entry into the lubricating zone 4 of contaminants coming from the contaminated zone 5.