Sealed rolling bearing

Abstract

To provide a sealed rolling bearing that, with a simple and low-cost configuration, prevents a seal body from falling off the bearing or rotating with the bearing, even when used continuously in a severe environment such as a high temperature and a heavy load.SOLUTION: A sealed rolling bearing comprises an outer ring, an inner ring, a plurality of rolling elements, and a seal body that is attached to a seal holder fitting surface provided at the outer end of an inner diameter portion of the outer ring to seal the gap formed between the outer ring and the inner ring. The seal body comprises a core metal with an L-shaped cross section that has a cylindrical portion and a circular ring portion bent from the outer end of the cylindrical portion toward the inner ring, a seal fixing portion that is attached to the core metal and comes in close contact with the seal holder fitting surface, and a seal member that is made of an elastic material and has a seal lip portion. The seal holder fitting surface and the outer ring raceway surface are connected via a step portion extending radially, and an engagement groove continuous with the step portion is provided at the axial inner end of the seal holder fitting surface.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a sealed rolling bearing, and more particularly to a sealed rolling bearing used in, for example, a rolling mill in a steel mill. [Background technology]

[0002] Conventionally, rolling mills for producing plate material from ferrous materials have often been multi-stage rolling mills consisting of work rolls that compress and clamp the ferrous material during rolling, one or more intermediate rolls that support the outer circumferential surfaces of the work rolls so that they can roll freely, and backup rolls that support the intermediate rolls from the outside to prevent the work rolls from deflecting, thereby obtaining plate material of a uniform thickness.

[0003] In order to manufacture plate products with high shape precision, large amounts of rolling water are sprayed onto the rolls in rolling mills to cool the rolls, lubricate the spaces between the rolls, i.e., between the work rolls and backup rolls, and lubricate the rolled material and the rolls.

[0004] Seals are used in bearing housings to prevent rolling water from seeping into the bearings. However, if rolling water seeps into the bearings due to a high-temperature environment, foreign matter such as scale, or improper maintenance, poor lubrication can occur, potentially leading to early bearing damage.

[0005] Patent Document 1 discloses a sealed rolling bearing that is equipped with a core, a slinger, and a seal lip attached to the core and in contact with the slinger, and that has an exhaust hole in the core to release pressure, in order to prevent rolling water from entering the bearing while responding to the increasing pressure inside the bearing that has accompanied the recent increase in speed of rolling mills aimed at high productivity, efficiency, and rationalization. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-137090 Summary of the Invention [Problem to be solved by the invention]

[0007] The seal body described in Patent Document 1 is intended to release the pressure inside the bearing to the outside space by means of a vent hole formed in the core metal, but because bearings used in rolling mills for steel manufacturing equipment are used in harsh environments such as high temperatures and heavy loads, there is a possibility that the seal body will fall off the bearing or rotate with it due to deformation of the outer ring that serves as the seal holder, an increase in the internal pressure of the bearing, continuous impacts and vibrations, etc. Furthermore, manufacturing the seal body is costly.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide a sealed rolling bearing that has a simple, low-cost configuration and prevents the seal body from falling off the bearing or rotating with the bearing, even when used continuously in harsh environments such as high temperatures and heavy loads. [Means for solving the problem]

[0009] The above object of the present invention is achieved by the following configuration [1]. [1] An outer ring having an outer ring raceway formed on its inner diameter portion; an inner ring having an inner ring raceway surface formed on an outer diameter portion thereof; a plurality of rolling elements disposed between the outer ring raceway surface and the inner ring raceway surface; a seal body attached to a seal holder fitting surface provided on an outer end of an inner diameter portion of the outer ring, and sealing a gap formed between the outer ring and the inner ring; A sealed rolling bearing comprising: the seal body comprises a core metal having an L-shaped cross section and including a cylindrical portion and a circular ring portion bent from an outer end of the cylindrical portion toward the inner ring, and a seal member made of an elastic material and including a seal fixing portion attached to the core metal and in close contact with the seal holder fitting surface, and a seal lip portion, the seal holder fitting surface and the outer ring raceway surface are connected via a step portion extending in the radial direction, an engaging groove continuous with the step portion is provided at an axial inner end of the seal holder fitting surface; Sealed rolling bearing. [Effects of the Invention]

[0010] According to the present invention, a simple and low-cost configuration can prevent the seal body from falling off the bearing or rotating with the bearing, even when the bearing is used continuously in a harsh environment such as high temperature and high load. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing a group of rolling rolls of a multi-stage rolling mill according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a main part showing a bearing provided in a backup roll. [Figure 3] FIG. 3 is a view showing the seal holder fitting surface and the seal body. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described below. Fig. 1 is a cross-sectional view showing a group of rolls of a multi-stage rolling mill according to the present invention. Fig. 2 is a cross-sectional view of a main part showing bearings provided in backup rolls. As shown in FIG. 1, a multi-stage rolling mill 10 has a plurality of types of roll groups provided in a housing 11, and rolls a conveyed steel material (rolled member) P to a uniform thickness by the roll group. The rolling roll group includes a pair of work rolls 12 for rolling the steel material P, a plurality of first intermediate rolls 13 (two on the top and two on the bottom, a total of four in the embodiment shown in Figure 1) that rotatably support the pair of work rolls 12, and a plurality of second intermediate rolls 14 (three on the top and three on the bottom, a total of six in the embodiment shown) that rotatably support these first intermediate rolls 13. Each second intermediate roll 14 is backed up by a plurality of backup rolls 15 (four on each side, total eight in the first embodiment) assembled to a backup roll shaft 16 and composed of a plurality of bearings 20. Note that six to eight bearings 20 are usually attached to one backup roll 15.

[0013] The second intermediate roll 14 is rotatably supported at a mounting position within the housing 11 via a rolling bearing.

[0014] The backup rolls 15 are attached to the housing 11 via saddles (not shown) or the like arranged between a plurality of bearings 20 arranged side by side. The backup rolls 15 control the position in a direction perpendicular to the backup roll shafts 16 via the saddles, thereby controlling the thickness of the steel material P. Each backup roll shaft 16 is always maintained in a stationary state (non-rotating state).

[0015] As shown in FIG. 2, the bearing 20 has an outer ring 21, an inner ring 22, cylindrical rollers 23 as rolling elements, a flange ring 24, a cage 25, and a seal body 40.

[0016] The outer ring 21 has outer ring raceway surfaces 21a formed on both sides of a protrusion 21b provided in the widthwise center of the inner diameter portion. The outer ring 21 also has seal holder fitting surfaces 30, 30 formed by cutting out the outer side of the outer ring raceway surface 21a in the widthwise direction. A seal body 40 is fitted onto the seal holder fitting surface 30.

[0017] Inner ring 22 has an inner ring raceway surface 22a formed on the outer diameter portion thereof, which is flat and stepless over the entire length in a cross section taken along the axis. The width of inner ring 22 is narrower than that of outer ring 21, and is formed to be approximately the same as the dimension between the outer end faces of two rows of cylindrical rollers 23 assembled to outer ring 21.

[0018] The cylindrical rollers 23 are aligned in two rows and interposed between the outer ring raceway surface 21a and the inner ring raceway surface 22a so as to be able to roll freely. The inner end faces 23a of the cylindrical rollers 23 come into contact with the side faces of the protrusions 21b formed on the outer ring 21, thereby restricting movement in a direction toward each other. The cylindrical rollers 23 are also held in place by a cage 25, arranged at predetermined intervals in the circumferential direction.

[0019] The flange ring 24 has an outer diameter DS that is larger than the outer diameter D1 of the inner ring 22 and smaller than the inner diameter D2 of the outer ring 21. The outer peripheral surface of the flange ring 24 faces radially opposite a seal holder fitting surface 30 formed on the inner diameter portion of the outer ring 21. This configuration can be seen in FIG. 2. The flange ring 24 has an inner end surface 24a that abuts against the outer end surfaces of the inner ring 22 and the cylindrical rollers 23, and a sliding contact surface 24b that is an outer peripheral surface that faces the seal holder fitting surface 30 in the radial direction and against which the seal body 40 slides. The abutment of the inner end surface 24a of the flange ring 24 with the outer end surfaces of the cylindrical rollers 23 restricts the pair of cylindrical rollers 23 from moving away from each other. A plurality of oil grooves 26 are formed at predetermined intervals on the inner end surface 24a of the flange ring 24, through which lubricating oil is conveyed and supplied by compressed air from a lubricating oil supply source (not shown).

[0020] In such a multi-stage rolling mill 10, the outer rings 21 of the bearings 20 are in pressure contact with the plurality of second intermediate rolls 14 and are positioned so as to be rotatable together with the second intermediate rolls 14. In this case, pressure from each outer ring 21 acts on the pair of work rolls 12 via the second intermediate rolls 14 and the first intermediate rolls 13, thereby preventing deflection of the work rolls 12. As a result, the transported steel material P is rolled to a uniform thickness by the pair of work rolls 12.

[0021] Next, the specific configurations of the seal holder fitting surface 30 and the seal body 40 will be described with reference to Fig. 3. Fig. 3 is a diagram showing the seal holder fitting surface and the seal body.

[0022] The seal holder fitting surface 30 is provided at the outer end of the inner diameter portion of the outer ring 21. The seal holder fitting surface 30 has a larger diameter than the outer ring raceway surface 21a and is connected to the outer ring raceway surface 21a via a locking groove 33 and a step portion 32. The step portion 32 extends radially from the end of the outer ring raceway surface 21a, specifically in a direction perpendicular to the seal holder fitting surface 30 (outer ring raceway surface 21a), and is connected to the locking groove 33.

[0023] The locking groove 33 is an annular groove formed between the axial inner end of the seal holder fitting surface 30 and the step 32. When the seal holder fitting surface 30 is formed on the outer ring 21 by turning, the locking groove 33 is usually formed by widening the axial width of a grinding relief groove formed at the axial inner end of the seal holder fitting surface 30 for post-processing grinding finish. The locking groove 33 extends in the axial direction and has a bottom 33a whose axially inner end is connected to the step 32, and an edge 33b that rises in a direction perpendicular to the axially outer end of the bottom 33a. The step 32 is formed so as to rise in the perpendicular direction from the axially inner end of the locking groove 33 (bottom 33a). This configuration can be seen in Figure 3. The axial width of the locking groove 33 need only be such that when the seal body 40 is fitted to the seal holder fitting surface 30, a locking piece 45 is formed by elastic deformation of the seal body 40, and is set appropriately depending on the shape of the seal body 40 and the type of elastic body.

[0024] The seal body 40 has a core metal 41, a seal member 46 having a seal fixing portion 42 and a seal lip portion 43, and a garter spring 44 which is a biasing member.

[0025] The core metal 41 is a metal member formed in a ring shape along the seal holder fitting surface 30, and has a cylindrical portion 41a formed along the inside of the seal holder fitting surface 30, and a circular ring portion 41b bent from the outer end of the cylindrical portion 41a toward the inner ring 22 (flange ring 24) side, and is formed with an L-shaped cross section.

[0026] The outer and inner diameter sides of the cylindrical portion 41a and the outer and inner axial sides of the annular portion 41b are covered with a seal member 46. The inner end of the cylindrical portion 41a is formed so as to come into contact with the step portion 32 when the seal body 40 is pressed into the seal holder fitting surface 30 and attached. This configuration can be seen in FIG.

[0027] The seal member 46 is made of an elastic material such as rubber. The seal member 46 has a seal fixing portion 42 that comes into close contact with the seal holder fitting surface 30, an outer wall portion 47 that continues from the seal fixing portion 42 and extends radially inward and covers the outside of the circular ring portion 41 b, an inner wall portion 48 that covers the inside of the circular ring portion 41 b, and a seal lip portion 43 that extends radially inward from the portion where the outer wall portion 47 and the inner wall portion 48 are connected and comes into sliding contact with the sliding surface 24 b of the flange ring 24.

[0028] The seal fixing portion 42 is fixed to the entire outer peripheral surface of the cylindrical portion 41 a. As a result, when the seal body 40 is pressed into the seal holder fitting surface 30, the seal fixing portion 42 is pressed against the seal holder fitting surface 30 and elastically deforms, so that the seal body 40 is firmly fitted to the seal holder fitting surface 30. The interference between the seal fixing portion 42 and the seal holder fitting surface 30 is set to 87 to 400 μm. At this time, a part of the seal fixing portion 42 bulges into the locking groove 33 to form a locking piece 45 .

[0029] The seal lip portion 43 has a base end portion 43a, a first lip portion 43b, a second lip portion 43c, and a biasing member support portion 43d.

[0030] The first lip portion 43b extends from a base end portion 43a on the inner diameter side of the circular ring portion 41b of the core metal 41 toward the outer circumferential surface of the flange ring 24 and makes sliding contact with the sliding surface 24b of the flange ring 24 on the outer side in the width direction. The second lip portion 43c extends axially inward from the first lip portion 43b and comes into sliding contact with the widthwise inner side of the sliding contact surface 24b of the flange ring 24. The second lip portion 43c has a V-shaped cross section that protrudes toward the sliding contact surface 24b, and thereby comes into line contact with the sliding contact surface 24b. The biasing member support portion 43d is an annular recess formed along the seal body 40 on the outer diameter side of the second lip portion 43c, and is an arc-shaped recess in cross section into which the garter spring 44 is fitted.

[0031] The garter spring 44 is attached to the biasing member support portion 43d to bias the annular second lip portion 43c (and the first lip portion 43b) radially inward, thereby enabling the first lip portion 43b and the second lip portion 43c of the seal lip portion 43 to more reliably contact the sliding surface 24b.

[0032] (Action and effect) According to the above-described configuration, the gap formed between the outer ring 21 and the inner ring 22 (rib ring 24) can be sealed with a simple configuration by the seal body 40 fitted to the seal holder fitting surface 30. This makes it possible to efficiently prevent lubricating oil from leaking from inside the bearing 20. Furthermore, even when a large amount of rolling water is sprayed onto each roll for lubrication between the work roll 12 and the backup roll 15, lubrication between the steel material P and the work roll 12, and cooling of each roll, it is possible to efficiently prevent rolling water from penetrating into the inside of the bearing 20.

[0033] Furthermore, since a part of the seal fixing portion 42 constitutes the locking piece 45, the seal body 40 can be prevented from slipping out of the seal holder fitting surface 30 or from rotating along with the seal holder fitting surface 30, even if the outer ring 21 is deformed, the internal pressure of the bearing 20 increases, or the bearing 20 is subjected to continuous impacts, vibrations, etc. due to continuous use of the backup roll 15 in a harsh environment.

[0034] More specifically, after the seal body 40 is pressed into the seal holder fitting surface 30, the elastic force of the seal fixing portion 42 causes it to return slightly toward the opening of the seal holder fitting surface 30, causing a portion of the seal fixing portion 42 to bulge into the locking groove 33. This portion of the seal fixing portion 42 bulging within the locking groove 33 catches on an edge 33b formed on the axially outer side of the locking groove 33, and acts as a locking piece 45 that prevents the seal body 40 from slipping out of the seal holder fitting surface 30. This configuration can be seen in Figure 3.

[0035] According to this configuration, the locking groove 33, which serves as a grinding relief required for post-processing grinding finish when forming the seal holder fitting surface 30, can also be used as a restriction groove that prevents the seal body 40 from slipping out of the seal holder fitting surface 30. Therefore, the seal body 40 can be prevented from falling off the bearing 20 with a configuration that reduces costs.

[0036] The present invention is not limited to the above-described embodiment, and modifications and improvements can be made as appropriate.

[0037] As described above, the present specification discloses the following: (1) an outer ring having an outer ring raceway formed on its inner diameter; an inner ring having an inner ring raceway surface formed on an outer diameter portion thereof; a plurality of rolling elements disposed between the outer ring raceway surface and the inner ring raceway surface; a seal body attached to a seal holder fitting surface provided on an outer end of an inner diameter portion of the outer ring, and sealing a gap formed between the outer ring and the inner ring; A sealed rolling bearing comprising: the seal body comprises a core metal having an L-shaped cross section and including a cylindrical portion and a circular ring portion bent from an outer end of the cylindrical portion toward the inner ring, and a seal member made of an elastic material and including a seal fixing portion attached to the core metal and in close contact with the seal holder fitting surface, and a seal lip portion, the seal holder fitting surface and the outer ring raceway surface are connected via a step portion extending in the radial direction, an engaging groove continuous with the step portion is provided at an axial inner end of the seal holder fitting surface; Sealed rolling bearing. According to this configuration, the seal body is engaged with the seal holder mating surface with a simple structure, so that the seal body can be prevented from falling off the bearing or rotating together with the bearing, even when used continuously in harsh environments such as high temperatures and heavy loads.

[0038] (2) The locking groove has a bottom portion extending in the axial direction and an edge portion rising in a direction perpendicular to the axial outer end of the bottom portion. (1) A sealed rolling bearing according to the present invention. According to this configuration, a part of the seal fixing portion that bulges out within the locking groove is caught on the edge portion, and therefore acts as a locking piece that prevents the seal body from slipping out from the seal holder fitting surface.

[0039] (3) The axial width of the locking groove is formed wider than the grinding relief groove. A sealed rolling bearing according to (1) or (2). According to this configuration, the grinding relief groove is formed wide so that it functions as a locking groove, which reduces the amount of work required for processing and keeps costs low.

[0040] (4) A part of the seal fixing portion that is in close contact with the seal holder fitting surface bulges into the locking groove due to elastic force. The sealed rolling bearing according to any one of (1) to (3). According to this configuration, the elastic force of the seal fixing portion is utilized to lock the seal body, which simplifies the configuration and allows for further reduction in manufacturing costs.

[0041] (5) The locking groove is formed in a circular ring shape. The sealed rolling bearing according to any one of (1) to (4). According to this configuration, the locking groove can be formed simply and at low cost. [Explanation of symbols]

[0042] 10 Multi-stage rolling mill 11. Housing 12 Work rolls 13 First intermediate roll 14 Second intermediate roll 15 Backup Roll 16 Backup roll shaft 20 Bearings 21 outer ring 21a Outer ring raceway 21b Convex part 22 Inner Circle 22a Inner ring raceway surface 23 Cylindrical roller 23a Inner end surface 24 Collar Ring 24a Inner end face 24b Sliding surface 25 Retainer 26 Oil groove 30 Seal holder mating surface 32 Stepped section 33 Locking groove 33a bottom 33b Edge 40 Seal body 41 Core 41a Cylindrical part 41b Circular part 42 Seal fixing part 43 Seal lip 43a Proximal end 43b First lip 43c Second lip 43d biasing member support portion 44 Garter spring (biasing member) 45 Locking piece

Claims

1. an outer ring having an outer ring raceway surface formed on an inner diameter portion; an inner ring having an inner ring raceway surface formed on an outer diameter portion thereof; a plurality of rolling elements disposed between the outer ring raceway surface and the inner ring raceway surface; a seal body attached to a seal holder fitting surface provided on an outer end of an inner diameter portion of the outer ring, and sealing a gap formed between the outer ring and the inner ring; A sealed rolling bearing comprising: the seal body comprises a core metal having an L-shaped cross section, the core metal having a cylindrical portion and a circular ring portion bent from an outer end of the cylindrical portion toward the inner ring, and a seal member made of an elastic material, the seal member having a seal fixing portion attached to the core metal and in close contact with the seal holder fitting surface, and a seal lip portion; the seal holder fitting surface and the outer ring raceway surface are connected via a step portion extending in the radial direction, an engaging groove continuous with the step portion is provided at an axial inner end of the seal holder fitting surface; Sealed rolling bearing.

2. The locking groove has a bottom portion extending in the axial direction and an edge portion rising in a direction perpendicular to the axial outer end of the bottom portion.

2. A sealed rolling bearing according to claim 1.

3. The axial width of the locking groove is formed wider than the grinding relief groove.

2. A sealed rolling bearing according to claim 1.

4. a part of the seal fixing portion that is in close contact with the seal holder fitting surface bulges into the locking groove due to elastic force; 2. A sealed rolling bearing according to claim 1.

5. The locking groove is formed in a circular ring shape. A sealed rolling bearing according to any one of claims 1 to 4.

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