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 having an inner diameter portion formed with an outer ring raceway surface, an inner ring having an outer diameter portion formed with an inner ring raceway surface, a plurality of rolling elements arranged between the outer ring raceway surface and the inner ring raceway surface, and a seal body that is attached to a seal holder fitting surface provided at the outer end of the inner diameter portion of the outer ring to seal the gap formed between the outer ring and inner ring. The seal body comprises a core metal, 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 surface roughness of the seal holder fitting surface is made rougher than the surface roughness of the outer peripheral surface of the outer ring.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 includes a core metal, a seal fixing portion attached to the core metal and in close contact with the seal holder fitting surface, and a seal member made of an elastic material having a seal lip portion; The surface roughness of the seal holder fitting surface is made rougher than the surface roughness of the outer peripheral surface of the outer ring. 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. [Figure 4] FIG. 4 is a cross-sectional view of a main part showing the shape of the outer ring. 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 of the cylindrical rollers 23 come into contact with the side faces of the protrusions 21b formed on the outer ring 21, 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 Figures 3 and 4. Figure 3 is a diagram showing the seal holder fitting surface and the seal body. Figure 4 is a cross-sectional view of a main part showing the shape of the outer ring.

[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 forms a step 32 between itself and the outer ring raceway surface 21a. The seal holder fitting surface 30 also has a ground relief groove 34 at its inner end.

[0023] The surface roughness of the seal holder fitting surface 30 is set to be greater than the surface roughness of the outer peripheral surface 21c of the outer ring 21. In this embodiment, the surface roughness of the outer peripheral surface 21c of the outer ring 21 is set to 0.20 μm or less in arithmetic mean roughness Ra (Ra≦0.20). The surface roughness of the seal holder fitting surface 30 is set to be greater than 0.20 μm and smaller than 6.3 μm (0.20 <Ra<6.3)。

[0024] The seal holder fitting surface 30 is formed by grinding the outer end of the outer ring 21 to create the outer shape of the seal holder fitting surface 30, and then the process of polishing the surface of the seal holder fitting surface 30 is partially omitted, so that each surface is processed to a predetermined surface roughness. Specifically, the outer peripheral surface 21c of the outer ring 21 is machined in the order of turning and then grinding (polishing process), while the seal holder mating surface 30 is machined only, omitting the grinding process, thereby enabling each to have the specified surface roughness.

[0025] Furthermore, the seal holder fitting surface 30 may be configured such that after the polishing process of the inner peripheral surface of the outer ring 21 is completed, the seal holder fitting surface 30 is machined to have a predetermined surface roughness. Specifically, when both seal holder fitting surface 30 and outer peripheral surface 21c of outer ring 21 are machined in the order of turning → grinding (polishing process), the grit size of the abrasive grains used in grinding is made different for seal holder fitting surface 30 and outer peripheral surface 21c of outer ring 21. In other words, by making the grit size of the grindstone used to grind seal holder fitting surface 30 larger than the grit size of the grindstone used to grind outer peripheral surface 21c of outer ring 21, it is possible to achieve the desired surface roughness for each.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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, 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] (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.

[0035] By making the surface roughness of the seal holder fitting surface 30 rougher than the surface roughness of the outer peripheral surface of the outer ring 21, the frictional force between the seal fixing portion 42 and the seal holder fitting surface 30 is increased. As a result, even if the outer ring 21 is deformed, the internal pressure of the bearing 20 increases, or the bearing 20 is subjected to continuous impact or vibration due to continuous use of the backup roll 15 in a harsh environment, it is possible to efficiently prevent the seal body 40 from slipping out of the seal holder fitting surface 30 or from rotating with it, using a simple and inexpensive configuration.

[0036] This configuration is highly versatile because it can be applied to any seal body 40 and can be made less likely to come off the seal holder fitting surface by adjusting the surface roughness of the seal holder fitting surface 30. In addition, since the seal holder fitting surface 30 is easy to process, costs can be kept low.

[0037] The present invention is not limited to the above-described embodiment, and modifications and improvements can be made as appropriate.

[0038] 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 includes a core metal, a seal fixing portion attached to the core metal and in close contact with the seal holder fitting surface, and a seal member made of an elastic material having a seal lip portion; The surface roughness of the seal holder fitting surface is made rougher than the surface roughness of the outer peripheral surface of the outer ring. Sealed rolling bearing. According to this configuration, the simple and inexpensive structure makes it difficult for the seal body to come off the seal holder mating surface, and prevents the seal body from falling off the bearing or rotating together with the bearing, even when the seal body is used continuously in harsh environments such as high temperatures and heavy loads.

[0039] (2) The arithmetic mean roughness Ra of the surface of the seal holder fitting surface is set to be greater than 0.20 μm. (1) A sealed rolling bearing according to the present invention. According to this configuration, the frictional force between the seal fixing portion and the seal holder fitting surface is increased, so that the seal body is less likely to come off the seal holder fitting surface with a simple and inexpensive configuration.

[0040] (3) The outer peripheral surface of the outer ring has a ground surface that is ground after turning, The seal holder fitting surface has a turned surface. A sealed rolling bearing according to (1) or (2). According to this configuration, part of the processing of the seal holder fitting surface can be omitted, thereby further reducing manufacturing costs.

[0041] (4) The seal holder fitting surface and the outer peripheral surface of the outer ring have ground surfaces that are ground after turning, the grain size of the grindstone used to grind the seal holder fitting surface is larger than the grain size of the grindstone used to grind the outer peripheral surface of the outer ring; A sealed rolling bearing according to (1) or (2). According to this configuration, the seal holder fitting surface and the outer peripheral surface of the outer ring can be easily and reliably made to have the desired arithmetic mean roughness. [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 21c Outer surface 22 Inner Circle 22a Inner ring raceway surface 23 Cylindrical roller 24 Collar Ring 24a Inner end face 24b Sliding surface 25 Retainer 26 Oil groove 30 Seal holder mating surface 32 Stepped section 34 Grinding undercut groove 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)

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 includes a core metal, a seal fixing portion attached to the core metal and in close contact with the seal holder fitting surface, and a seal member made of an elastic material having a seal lip portion; The surface roughness of the seal holder fitting surface is made rougher than the surface roughness of the outer peripheral surface of the outer ring. Sealed rolling bearing.

2. The arithmetic mean roughness Ra of the surface of the seal holder fitting surface is greater than 0.20 μm.

2. A sealed rolling bearing according to claim 1.

3. the outer peripheral surface of the outer ring has a ground surface that is ground after turning, The seal holder fitting surface has a turned surface.

3. A sealed rolling bearing according to claim 1 or 2.

4. the seal holder fitting surface and the outer peripheral surface of the outer ring have ground surfaces that are ground after turning, the grain size of the grindstone used to grind the seal holder fitting surface is larger than the grain size of the grindstone used to grind the outer peripheral surface of the outer ring; 3. A sealed rolling bearing according to claim 1 or 2.

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