Rolling bearings

Abstract

To provide rolling bearings with stable sealing performance. [Solution] The rolling bearing comprises inner and outer rings 2 and 3, a plurality of rolling elements, and a contact-type sealing member 6 that closes the bearing space between the inner and outer rings 2 and 3. The sealing member 6 comprises a seal tilt suppression means St, a grease flow suppression means GS, and a radial change amount reduction means Rcr. The seal tilt suppression means St suppresses the inner circumferential portion 13 of the sealing member 6 from tilting inward in the axial direction. The grease flow suppression means GS suppresses the flow of grease from the inner circumferential surface of the sub-lip 16 to the inner diameter side tip of the main lip 15, and also brings the main lip 15 into a desired contact state with the seal groove 7. The radial change amount reduction means Rcr reduces the radial change amount of the main lip 15 to a predetermined value or less within the range of the overlap.

Description

Technical Field

[0001] The present invention relates to a rolling bearing and a technique capable of stabilizing the sealing performance.

Background Art

[0002] In a rolling bearing 50 for a servo motor shown in FIG. 20, there is a model in which an encoder 52 is arranged near a motor 51. For such a model, in order to prevent malfunction of the encoder 52 due to dust generated inside the bearing and adhesion of seal wear powder to the encoder 52, a low-dust generation rolling bearing 50 with a contact seal is required.

[0003] As prior arts, there are Patent Documents 1 and 2. Both of these prior documents propose a rolling bearing capable of reducing the amount of dust generated from the inside of the bearing even when the internal pressure of the bearing increases during rotation. Specifically, it defines the relative position of the core metal and the sub-lip, the tip shape of the contact seal lip in contact with the seal groove, and the inclined surface of the seal groove.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The above two prior documents are improvement proposals regarding dust generation from the inside of the bearing, and there is no problem as a shape proposal regarding dust generation property. Both of these prior documents have a structure in which the seal contacts the axially outer surface of the inner ring seal groove, and are effective regarding dust generation from the inside of the bearing due to an increase in internal pressure.

[0006] On the other hand, in order to stabilize the sealing performance of a contact seal, it is necessary to stabilize the contact state between the inner ring seal groove and the inner diameter lip of the seal (hereinafter referred to as the "inner ring contact area"). In previous literature, the seal is inserted into the inner ring seal groove with an overlap, and the radial variation of the inner ring contact area within the overlap range is large. Also, depending on the contact state with the outer diameter lip, the inner ring contact area can rotate in a direction that creates a gap between it and the inner ring seal groove. For this reason, if the overlap changes due to the oscillation of the inner ring or changes in internal pressure during bearing rotation, the contact state of the inner ring contact area becomes unstable and the sealing performance becomes unstable.

[0007] Furthermore, base oil adhering to the bearing side of the seal surface (hereinafter referred to as the "inner surface of the seal") can travel along the seal and reach the tip of the inner diameter lip. Therefore, there is a possibility that the base oil that reaches the tip of the inner diameter lip may seep out to the outside. Furthermore, the shape of the seal makes it prone to assembly defects, such as the inner diameter lip not fitting completely into the inner ring seal groove, or defects occurring in the inner diameter lip due to contact between the push-in jig and the inner diameter lip.

[0008] The objective of the present invention is to provide a rolling bearing with stable sealing performance. [Means for solving the problem]

[0009] The rolling bearing of the present invention comprises an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a sealing member that closes the bearing space between the inner ring and the outer ring, wherein the sealing member has a main lip that contacts the seal groove of the inner ring with an overlap, and a secondary lip that protrudes axially inward from its base end and does not contact the seal groove, and grease is sealed in the bearing space. The sealing member is A seal tilt suppression means that prevents the inner circumferential portion of the seal member from tilting inward in the axial direction, A grease flow suppression means that suppresses the flow of grease from the inner circumferential surface of the sub-lip to the inner diameter side tip of the main lip, Within the aforementioned tightening allowance range, a radial change amount reduction means for reducing the radial change amount of the main lip to a predetermined value or less, It is equipped. The aforementioned "desired contact state" refers to a state in which the main lip is properly inserted into and in contact with the seal groove without buckling or the like, and in which no defects occur at the tip of the main lip. The aforementioned "specified value" is a value arbitrarily determined by design, etc., and is determined by finding an appropriate value through either or both of the following: testing and simulation. The "range of the overlap" is determined from the position of the contact portion of the main lip with respect to the seal groove when the overlap is minimized and the position of the contact portion when the overlap is maximized, when the inner and outer rings are displaced relatively in the axial direction.

[0010] In this configuration, the seal tilt suppression means prevents the inner circumference portion of the seal member from tilting axially inward, that is, axially toward the rolling element from the bearing end face. This seal tilt suppression means reduces the rotational movement range of the seal member compared to conventional structures. Therefore, the seal position of the seal member after bearing insertion is stable, and the position of the seal member is less likely to shift even when subjected to reaction forces due to contact between the outer surface of the seal groove of the inner ring and the main lip.

[0011] The grease flow suppression means suppresses the flow of grease from the inner circumferential surface of the sub-lip to the inner diameter side tip of the main lip. As a result, the base oil of the grease flowing along the inner surface of the seal cannot reach the inner diameter side tip of the main lip, thus reducing the amount of dust generated from inside the bearing compared to conventional structures.

[0012] The radial variation reduction means reduces the radial variation of the main lip to a predetermined value or less within the range of the aforementioned interference fit. Therefore, even if the interference fit changes during bearing rotation due to the oscillation of the inner ring or pressure changes inside the bearing, the sealing performance with respect to the seal groove of the inner ring can be stabilized. This allows for a reduction in rotational torque compared to conventional structures.

[0013] The sealing member has a core metal, a constricted portion located radially inward from the inner diameter of the core metal and decreasing in thickness toward the inner diameter, a bent portion connected to the inner diameter of the constricted portion, and the main lip connected to the inner diameter of the bent portion. The means for reducing radial variation ensures that, at the maximum interference fit, the maximum axially outward protrusion position Pk of the bent portion is axially outward from the bottom Ks of the axially outward portion of the constricted portion, and is the same as or axially inward from the axial position Tm of the end face of the inner or outer ring. In this case, the bent portion Be does not protrude from the bearing end face. By making the sealing member 6 this shape, the amount of elastic deformation at the bent portion Be increases. As a result, the rotation center of the approximately circular range of motion of the contact portion 15c of the main lip 15 moves axially toward the opposite side of the bearing, making it easier to set the position of the contact portion 15c at the center of the interference fit near directly below the rotation center. This makes the radial variation Δa of the contact portion 15c of the main lip 15 smaller than in conventional structures.

[0014] It is desirable that the axial wall thickness Ta at the bottom of the constricted portion is greater than the radial wall thickness Tb from the inner diameter portion of the constricted portion to the inner circumferential surface of the bent portion. In this case, the amount of elastic deformation on the inner diameter side of the constricted portion can be increased. Therefore, the amount of radial change in the contact portion of the main lip within the interference fit range can be made even smaller than in conventional structures.

[0015] The seal tilt suppression means has an inclined surface on the outer peripheral portion of the seal member that contacts the seal groove of the outer ring, which slopes inward toward the inner diameter as it moves axially inward, and the angle of the inclined surface may be set in the following relationship with respect to a plane perpendicular to the axial direction. 0° < Angle of the inclined surface ≤ Angle of inclination of the inner surface in the seal groove of the outer ring In this case, since the inclined surface of the sealing member is positioned substantially along the inner surface of the seal groove of the outer ring, the position of the sealing member inserted into the bearing is more easily stabilized.

[0016] The grease flow suppression means may be provided with uneven portions between the inner peripheral surface of the sub-lip and the axially inner surface of the main lip. The surface extending from the inner peripheral surface of the sub-lip to the axially inner surface of the main lip is referred to as the "seal back surface". In this case, the base oil of the grease flowing along the seal inner surface is blocked at the seal back surface and allowed to escape in the circumferential direction.

[0017] As a method of providing unevenness on the seal back surface of the grease flow suppression means, a convex portion is provided at the minimum inner diameter position of the seal back surface. In this case, it becomes easier to make the radial dimension B (FIG. 8) of the tip at the seal back surface of the main lip larger than the outer diameter dimension A (FIG. 8) of the end face of the inner ring. With this grease flow suppression means, the design freedom is increased and the insertability of the main lip into the seal groove is improved.

[0018] The seal member may be provided only on one axial side or on both axial sides of the rolling bearing. When the seal member is provided only on one axial side, the number of parts can be reduced and the processing man-hours for the seal groove etc. can be reduced, achieving cost reduction. When the seal member is provided on both axial sides, it is possible to suppress the outflow of grease from the inside of the bearing and the intrusion of foreign matter from the atmosphere side.

[0019] The grease contains a base oil and a thickener. The base oil contains a synthetic hydrocarbon oil and an ether oil, and is a mixed oil having a kinematic viscosity at 40 °C of 120 mm 2 / s or more. The thickener is an aliphatic diurea compound and an alicyclic diurea compound, and is contained in an amount of 12 to 15 parts by mass with respect to 100 parts by mass of the total amount of the base oil and the thickener. The grease may have a work penetration of 200 to 240 and contain a solid organic acid metal salt at 20 °C. The work penetration is measured in accordance with JIS (Japanese Industrial Standards) K 2220. The larger the work penetration value of the grease, the softer it is.

[0020] According to this configuration, by adding a solid organic acid metal salt at 20°C to a grease with a predetermined base oil and thickener combination, the organic acid metal salt can dissolve without affecting the surface tension of the base oil, and in the event of insufficient base oil supply and concerns about wear, it can protect the steel surface as an extreme pressure agent. Applying such a grease is even more effective against dust generation from inside the bearing. [Effects of the Invention]

[0021] The rolling bearing of the present invention comprises an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a sealing member that closes the bearing space between the inner ring and the outer ring, wherein the sealing member has a main lip that contacts the seal groove of the inner ring with an overlap, and a sub-lip that protrudes axially inward from its base end and does not contact the seal groove, and grease is sealed in the bearing space, wherein the sealing member comprises a seal tilt suppression means that suppresses the inner circumferential portion of the sealing member from tilting axially inward, a grease flow suppression means that suppresses the flow of grease from the inner circumferential surface of the sub-lip to the inner diameter tip of the main lip, and a radial change amount reduction means that reduces the radial change amount of the main lip to a predetermined value or less within the overlap range. As a result, the sealing performance of the rolling bearing is stable. [Brief explanation of the drawing]

[0022] [Figure 1] This is a longitudinal cross-sectional view of a rolling bearing according to the first embodiment of the present invention. [Figure 2] This is an enlarged cross-sectional view showing a magnified view of the sealing member of the rolling bearing. [Figure 3] This is an enlarged cross-sectional view of the lip and other parts of the sealing component. [Figure 4] This is an enlarged cross-sectional view comparing the outer peripheral portion of the seal member in question with that of a conventional seal member. [Figure 5] This is an enlarged cross-sectional view showing the outer peripheral portion of the sealing member and the conventional sealing member, together with the sealing groove of the outer ring. [Figure 6] This is a perspective view of the sealing member of the rolling bearing. [Figure 7A] This is an enlarged cross-sectional view showing a modified example of the outer peripheral portion of the sealing member. [Figure 7B] This is an enlarged cross-sectional view showing another modified example of the outer peripheral portion of the sealing member. [Figure 8] This is an enlarged cross-sectional view of the main part of the sealing member. [Figure 9] This is an enlarged cross-sectional view of a key part illustrating the effects when the orientation of the sealing member is different. [Figure 10] This is an enlarged cross-sectional view of the key parts of the sealing member, illustrating the constricted portion, bent portion, etc. [Figure 11] This figure shows the radial change in the main lip of the sealing member within the overlap range. [Figure 12] This is a longitudinal cross-sectional view of a rolling bearing according to a second embodiment of the present invention. [Figure 13] This is a longitudinal cross-sectional view of a rolling bearing according to a third embodiment of the present invention. [Figure 14] This is a perspective view of the cage of the rolling bearing. [Figure 15] This figure shows the relationship between the main lip's tightening allowance and contact force, as determined by analysis. [Figure 16] This is a longitudinal cross-section of a rotary torque testing machine. [Figure 17] This figure shows the results of a comparison of the torque of individual seals based on torque tests. [Figure 18] These are enlarged cross-sectional views of the main lip, etc., of the sealing member in each embodiment. [Figure 19] This diagram shows the steps involved in inserting the sealing member into the sealing groove. [Figure 20] This is a schematic diagram showing rolling bearings and the like for a servo motor. [Modes for carrying out the invention]

[0023] [First Embodiment] A rolling bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 11 and Figures 15 to 19. This rolling bearing is applicable to industrial machinery such as servo motors, vehicles, etc. However, the rolling bearing is not limited to these applications and can be applied to various machines, devices, etc.

[0024] <Outline configuration of a rolling bearing> Figure 1 shows a cross-section (longitudinal section) of the rolling bearing 1 as viewed by cutting it through a virtual plane containing the bearing axis. The same applies to the cross-sectional views of other embodiments. The rolling bearing 1 is a deep groove ball bearing comprising an inner ring 2, an outer ring 3, balls (rolling elements) 4, a cage 5, and a sealing member 6. Multiple balls 4 interposed between the raceway surfaces 2a and 3a of the inner and outer rings 2 and 3 are held at regular intervals in the circumferential direction by the cage 5. The cage 5 is, for example, a so-called crown-shaped cage with an opening on one side of the axial direction of a pocket Pt. The sealing member 6 is attached to the outer ring 3 and closes the bearing space, which is the annular space between the inner ring 2 and the outer ring 3. In this example, sealing members 6, 6 are attached to both sides of the axial direction on the inner circumferential surface of the outer ring. Grease is sealed in the bearing space between the inner and outer rings 2 and 3.

[0025] In this specification, rolling bearings are sometimes simply referred to as "bearings." In the following description, the direction of the bearing axis, which is the bearing center axis AX, is referred to as the "axial direction," the direction perpendicular to the bearing center axis AX is referred to as the "radial direction," and the direction around the bearing center axis AX is referred to as the "circumferential direction." Furthermore, the side facing the bearing center axis AX is referred to as the "inner diameter side," and the side moving away from the bearing center axis AX is referred to as the "outer diameter side."

[0026] <Regarding the seal structure, etc.> Each sealing member 6 is a contact seal in which the main lip 15 contacts the sealing groove 7 of the inner ring 2. The sealing groove 7 is formed in the circumferential direction on the outer surface of the inner ring 2, and a sealing groove 9 for fixing the sealing member is provided on the inner surface of the outer ring 3 opposite each sealing groove 7. As shown in Figure 2, the sealing member 6 is made by molding rubber material 11 onto a core metal 10, and the outer peripheral portion 8 of the sealing member 6 is fitted into the sealing groove 9 of the outer ring 3 and fixed in place.

[0027] <Outer ring seal groove> The seal groove 9 of the outer ring 3 has an inner surface 9a, a groove bottom surface 9c, and an outer surface 9b in sequence, extending outward in the axial direction. As shown in Figure 1, the inner surface 9a connects to the outer ring shoulders provided on both sides of the raceway surface 3a in the axial direction. The inner surface 9a is formed as an inclined surface that slopes outward towards the outer diameter as it extends outward in the axial direction, taking into consideration machinability when cutting the seal groove 9.

[0028] As shown in Figure 2, the groove bottom surface 9c, which smoothly connects to the inner surface 9a, has a shape that is recessed towards the radial outer diameter. The outer surface 9b smoothly connects to the groove bottom surface 9c and is formed as an inclined surface that slopes towards the inner diameter as it extends axially outward. In Figure 2, a portion of the outer peripheral portion 8 of the seal member 6 is shown as being embedded in the seal groove 9 of the outer ring 3, but this portion is an overlap and is actually fitted into the seal groove 9 in an elastically deformed state.

[0029] A main lip 15 is provided on the inner circumference portion 13 of the sealing member 6, which contacts the outer surface 7c of the sealing groove 7 of the inner ring 2. In Figure 2, a portion of the main lip 15 is shown as being embedded in the sealing groove 7 of the inner ring 2, but this portion is an overlap and actually contacts the sealing groove 7 in an elastically deformed state.

[0030] <Air vent> As shown in Figure 6, the outer peripheral portion 8 of the sealing member 6 is provided with one or more air holes 12 to release the internal pressure of the rolling bearing. These air holes 12 include radial air holes 12a, 12a formed along the radial direction and axial air holes 12b formed along the axial direction. The air holes 12a, 12b each consist of grooves provided on the outer peripheral portion of the sealing member 6. These radial air holes 12a, 12a and axial air holes 12b are provided at different circumferential positions. The number of air holes 12a, 12b and their circumferential positions are not limited to those shown in Figure 6.

[0031] As shown in Figures 2 and 6, the radial air holes 12a, 12a and the axial air hole 12b are in communication via the groove bottom surface 9c of the seal groove 9. Therefore, when the rolling bearing 1 (Figure 1) rotates, the internal pressure of the bearing can be released to the outside through the two radial air holes 12a, 12a and the axial air hole 12b.

[0032] <Inner ring seal groove> As shown in Figure 1, the seal groove 7 of the inner ring 2 has an inner surface 7a, a groove bottom surface 7b, and an outer surface 7c in order from the axial outward direction. Here, in the seal groove 7, the side surface in the direction of the bearing interior is called the inner surface 7a, and the side surface in the direction of the bearing exterior is called the outer surface 7c. The inner surface 7a connects to the inner ring shoulders provided on both sides of the raceway surface 2a in the axial direction and is formed as an inclined surface that slopes inward toward the inner diameter as it extends outward in the axial direction. The groove bottom surface 7b, which smoothly connects to this inner surface 7a, has a shape that is recessed toward the inner diameter. The outer surface 7c connects smoothly to the groove bottom surface 7b and is formed as an inclined surface that slopes outward toward the outer diameter as it extends outward in the axial direction.

[0033] As shown in Figure 2, the rubber material 11 in the sealing member 6 is typically made of nitrile rubber, but other materials such as acrylic rubber, silicone rubber, or fluororubber may be used depending on the operating temperature.

[0034] <Lip> As shown in Figure 3, the inner circumferential portion 13 of the sealing member 6 that extends radially inward beyond the inner diameter of the core metal 10 is made of the rubber material 11. The inner circumferential portion 13 has a constricted portion 14 in which the wall thickness decreases towards the inner diameter, a bent portion Be, a main lip 15 that contacts the sealing groove 7 (Figure 2) with an overlap, and a sub-lip 16. These constricted portion 14, bent portion Be, main lip 15, and sub-lip 16 are integrally molded. Integral molding means that the constricted portion 14, bent portion Be, main lip 15, and sub-lip 16 are not made by combining multiple elements, but are molded from a single material as part or as a whole of a single object, for example by injection molding.

[0035] The constricted portion 14 is located radially inward from the inner diameter portion of the mandrel 10, and its wall thickness decreases towards the inner diameter side. The bent portion Be connects to the inner diameter portion of the constricted portion 14 and extends axially outward, bending, or elastically deforming, the inner circumference portion 13 including the main lip 15. The main lip 15 connects to the inner diameter portion of the bent portion Be. The sub-lip 16 connects to the axially inner surface of the bent portion Be. The sub-lip 16 protrudes axially inward from its base end, which connects to the axially inner surface of the bent portion Be, and, as shown in Figure 1, is not in contact with the seal groove 7 of the inner ring 2. A labyrinth seal Rs is formed between the tip of the sub-lip 16 and the inner surface 7a of the seal groove 7.

[0036] As shown in Figure 3, the outer surface of the bent portion Be facing the axially outer portion of the constricted portion 14 is formed as an inclined surface Bea that slopes inward toward the inner diameter as it extends axially outward. The angle α1 between this inclined surface Bea of ​​the bent portion Be and the axially outer portion of the constricted portion 14 is set to an acute angle within the range of the overlap that the main lip 15 contacts the seal groove 7 (Figure 2).

[0037] The main lip 15 has a lip body portion 15b that is inclined axially inward as it approaches the inner diameter, and a contact portion 15c provided on the outer surface portion of the lip body portion 15b at the tip. The inner surface of the lip body portion 15b is provided with a convex portion 15ba that protrudes axially inward. The contact portion 15c is also referred to as the inner diameter side tip. The contact portion 15c contacts the seal groove 7 (Figure 2) of the inner ring 2. Specifically, the contact portion 15c is formed in an R shape that is normal to the outer surface 7c (Figure 2) of the seal groove 7. The outer diameter surface 15ca of the contact portion 15c is inclined toward the inner diameter side as it is directed outward in the axial direction and smoothly connects to the aforementioned R shape.

[0038] <Means for preventing seal collapse: outer diameter lip portion, inclined surface> As shown in Figure 2, the seal member 6 is equipped with a seal tilt suppression means St that prevents the inner circumference portion 13 from tilting inward in the axial direction. Specifically, the seal tilt suppression means St is such that the inner surface 8a of the outer circumference portion 8 of the seal member 6 that contacts the seal groove 9 of the outer ring 3 has an inclined surface 8aa that slopes inward towards the inner diameter as it moves inward in the axial direction. Here, in the outer circumference portion 8 of the seal member 6, the side surface in the direction of the inside of the bearing is called the inner surface 8a. The axial inward direction refers to the axial direction from the bearing end face toward the rolling elements inside the bearing.

[0039] Figure 4 is an enlarged cross-sectional view comparing the outer peripheral portions 8,80 of the sealing member 6 of this embodiment (Figure 4(b)) with those of the conventional sealing member 60 (Figure 4(a)). In the conventional example shown in Figure 4(a), the inner surface 80a of the outer peripheral portion 80 of the sealing member 60 is provided on a plane perpendicular to the axial direction. In this case, as shown in Figure 5(a), when the sealing member 60 is inserted along the inclination of the inner surface 9a, the rotational range of the entire sealing member 60 is large, causing the entire sealing member 60 to tilt inward in the axial direction.

[0040] In contrast, the sealing member 6 shown in Figure 4(b) has the aforementioned inclined surface 8aa on the inner surface 8a of the outer peripheral portion 8. The angle α of this inclined surface 8aa is set to the following relationship with respect to a plane perpendicular to the axial direction, as shown in Figure 5(b). 0° < Angle of the inclined surface α ≤ Angle of inclination of the inner surface 9a in the seal groove 9 of the outer ring 3 It is more preferable that the angle α of the inclined surface is set in the following relationship with respect to a plane perpendicular to the axial direction. The angle of inclination of the inner surface 9a in the seal groove 9 of the outer ring 3 is -1° ≤ angle of the inclined surface α ≤ angle of inclination of the inner surface 9a in the seal groove 9 of the outer ring 3.

[0041] <Modified example: Figure 7A, inclined surface + flat surface> As shown in Figure 7A, the inner surface 8a of the outer peripheral portion 8 of the seal member 6 may have an inclined surface 8aa and a flat surface 8ab connected to the inner diameter edge of the inclined surface 8aa. The flat surface 8ab is provided, for example, parallel to a plane perpendicular to the axial direction. In this case, the flat surface 8ab can be used as a reference surface when defining the angle α of the inclined surface 8aa. This makes it possible to make the angle α of the inclined surface 8aa more precise, and the seal position of the seal member 6 when inserted into the bearing is more stable.

[0042] <Modified version: Figure 7B, inclined surface + flat surface + convex part> As shown in Figure 7B, a plurality of protrusions 17 may be provided on the flat surface 8ab in the circumferential and radial directions. When the bearing is inserted into this seal member 6, the protruding tip of each protrusion 17 contacts the inner surface of the seal groove of the outer ring in an elastically deformed state. In this case, the pressing force of each protrusion 17 makes the seal position of the seal member 6 more stable when the bearing is inserted than in the seal structure of Figure 7A.

[0043] <Grease flow suppression means: reverse slope + uneven surface> As shown in Figure 8, the sealing member 6 is equipped with a grease flow suppression means GS. The grease flow suppression means GS suppresses the flow of grease from the inner circumferential surface 16b of the sub-lip 16 to the inner diameter side tip portion 15c of the main lip 15. At the same time, the grease flow suppression means GS brings the main lip 15 into a desired contact state with the seal groove 7 of the inner ring 2. Specifically, the grease flow suppression means GS has an inverted inclination shape on the inner circumferential surface 16b of the sub-lip 16, which slopes outward toward the outer diameter as it moves axially outward, and a convex portion 15ba provided on the inner surface of the lip body portion 15b that protrudes axially inward. Here, the direction from the sub-lip 16 toward the outside of the bearing is referred to as the axial outward direction.

[0044] A layer of irregularities Un is provided between the inner circumferential surface 16b of the sub-lip 16 and the seal back surface Sm, which is the surface extending to the axial inner surface of the main lip 15. The seal back surface Sm, excluding the convex portion 15ba, corresponds to the concave portion. This layer of irregularities Un, consisting of the concave portion and the convex portion 15ba, constitutes the grease flow suppression means GS. In other words, the grease flow suppression means GS is provided by a layer of irregularities Un provided between the inner circumferential surface 16b of the sub-lip 16 and the surface extending to the axial inner surface of the main lip 15.

[0045] Even when the inner diameter tip 15c is in contact with the seal groove 7, the inner circumferential surface 16b of the sub-lip 16 is shaped to incline towards the outer diameter as it moves axially outward. As shown in Figure 3, the inclination angle α2 of the inner circumferential surface 16b with respect to the axial direction is set to, for example, about 1° to 20° by testing or simulation. However, the inclination angle α2 is not limited to the above angle. The inverted inclination shape of the sub-lip 16 suppresses the flow FL of grease from the inner circumferential surface 16b of the sub-lip 16 to the inner diameter tip 15c of the main lip 15. In this example, the entire inner circumferential surface 16b of the sub-lip 16 has an inverted inclination shape, but it is not limited to this shape. For example, a part of the inner circumferential surface 16b in the axial direction may have an inverted inclination shape, and the other part of the inner circumferential surface 16b may have a flat shape that is substantially parallel to the axial direction.

[0046] The protrusion 15ba blocks the base oil Ky of the grease flowing along the inner surface of the seal, allowing it to escape in the circumferential direction. Furthermore, as shown in Figure 8, by providing the protrusion 15ba on the back surface Sm of the seal, it becomes easier to make the radial dimension B of the tip of the main lip 15 on the back surface Sm of the seal larger than the outer diameter dimension A of the end face of the inner ring 2. In other words, when the protrusion 15ba is provided on the back surface Sm of the seal, it is easier to increase the radial dimension B of the tip of the main lip 15 on the back surface Sm of the seal compared to when the protrusion 15ba is not provided on the back surface Sm of the seal. This grease flow suppression means GS increases the degree of design freedom and is effective in improving the insertability of the main lip 15 into the seal groove 7 and suppressing base oil leakage.

[0047] When the axial direction of the rolling bearing is aligned vertically, that is, even when the seal member 6 is in the position shown in Figure 9, the base oil Ky of the grease is blocked by the protrusion 15ba on the back of the seal. Therefore, the amount of dust generated from inside the bearing can be reduced compared to conventional structures.

[0048] <Means for reducing radial change amount> In Figure 11, the solid line indicates the position of the contact portion 15c when the set tightening allowance is at its minimum, the dashed-dot line indicates the position of the contact portion 15c when the tightening allowance is approximately in the middle, and the dashed-dot line indicates the position of the contact portion 15c when the tightening allowance is at its maximum. As shown in Figures 10 and 11, the sealing member 6 is equipped with a radial change amount reduction means Rcr that reduces the radial change amount Δa of the contact portion 15c of the main lip 15 to a predetermined value or less within the range of the tightening allowance. The radial change amount reduction means Rcr reduces the radial change amount Δa within the range of the tightening allowance by changing the seal shape of the inner circumference portion 13 located on the inner diameter side of the core metal 10.

[0049] Specifically, the bent portion Be, which bends on the inner diameter side of the constricted portion 14, is made to protrude axially toward the bearing side, that is, axially toward the outside. As a result of this protrusion of the bent portion Be axially toward the outside, the angle α1 formed by the inclined surface Bea of ​​the bent portion Be and the axially outward portion of the constricted portion 14 becomes an acute angle within the range of the aforementioned interference fit.

[0050] The axial protrusion amount of the bent portion Be is such that, in the state of maximum interference fit, the bottom Ks of the constricted portion 14 < the maximum protrusion position Pk of the bent portion Be ≤ the end face (also called the [width face]) of the inner or outer ring. In other words, the radial change amount reducing means Rcr ensures that, when the interference fit is at its maximum, the maximum axially outward protrusion position Pk of the bent portion Be is axially outward from the bottom Ks of the axially outward portion of the constricted portion 14, and is the same as or axially inward with respect to the axial position Tm of the end face of the inner or outer ring. Here, axially inward refers to the direction inside the bearing. Furthermore, the axial wall thickness Ta at the bottom Ks of the constricted portion 14 is greater than the radial wall thickness Tb (wall thickness at the base of the constricted portion) from the inner diameter portion of the constricted portion 14 to the inner circumferential surface Beb of the bent portion Be.

[0051] <About grease> The grease sealed in the rolling bearing 1 in Figure 1 is preferably a low-dusting grease as described below. The grease contains a base oil and a thickener. The base oil contains synthetic hydrocarbon oil and ether oil, and has a kinematic viscosity of 120 mmHg at 40°C. 2 The oil mixture has a viscosity of 1 / s or higher. The thickener is an aliphatic diurea compound and an alicyclic diurea compound, and is present in an amount of 12 to 15 parts by mass per 100 parts by mass of the total amount of the base oil and the thickener. The grease has a mixed consistency of 200 to 240 and contains organic acid metal salts that are solid at 20°C.

[0052] In detail, this kinematic viscosity is the kinematic viscosity of the mixed oil, which is 120 mm at 40°C. 2 / s~160mm 2 / s is preferred, 125mm 2 / s~140mm 2 / s is preferable.

[0053] Poly-α-olefin oil (PAO oil) is more preferred as the synthetic hydrocarbon oil. PAO oil is a mixture of α-olefins or oligomers or polymers of isomerized α-olefins. Specific examples of α-olefins include 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 1-docosene, and 1-tetradocosene, and mixtures of these are usually used.

[0054] Examples of ether oils include polyphenyl ether oil, alkyl diphenyl ether oil, alkyl triphenyl ether oil, and alkyl tetraphenyl ether oil. Among these, alkyl diphenyl ether oil is preferred in terms of durability at high temperatures, and it is more preferable that alkyl diphenyl ether oil makes up 50% by mass or more of the total base oil (mixed oil). Examples of alkyl diphenyl ether oils include monoalkyl diphenyl ether oil, dialkyl diphenyl ether oil, and polyalkyl diphenyl ether oil.

[0055] The base oil may be a mixture of synthetic hydrocarbon oil and ether oil only, or a mixture with other oils added. The other oils can be any oil commonly used in rolling bearings, without any particular restrictions. Examples include paraffinic mineral oil, naphthenic mineral oil, ester oil, silicone oil, and fluorinated oil.

[0056] The thickeners used in greases are mixtures of aliphatic diurea compounds and alicyclic diurea compounds. These diurea compounds are obtained by reacting a diisocyanate component with a monoamine component. Aliphatic diurea compounds are obtained from an aliphatic monoamine as the monoamine component and a diisocyanate component, while alicyclic diurea compounds are obtained from an alicyclic monoamine as the monoamine component and a diisocyanate component. Examples of diisocyanate components include phenylenediisocyanate, tolylenediisocyanate, diphenyldiisocyanate, diphenylmethanediisocyanate, octadecanediisocyanate, decanediisocyanate, and hexanediisocyanate. Examples of aliphatic monoamines include hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, stearylamine, and oleylamine. Examples of alicyclic monoamines include cyclohexylamine. In the present invention, it is preferable that the content of aliphatic diurea compounds in the thickener is greater than the content of alicyclic diurea compounds.

[0057] A base grease is obtained by blending a diurea compound as a thickener with a base oil. The base grease using a diurea compound as a thickener is prepared by reacting a diisocyanate component with a monoamine component in the base oil. The thickener is included in an amount of 12 to 15 parts by mass per 100 parts by mass of the total amount of base oil and thickener.

[0058] The organic acid metal salts used in greases are salts of a substituent-containing aliphatic or aromatic compound, such as an organic carboxylic acid, an organic sulfonic acid such as alkylbenzene sulfonic acid, an organic sulfuric acid such as alkyl sulfonic acid, an organic phosphonic acid such as alkyl phosphonic acid, or an organic phosphinic acid such as alkyl phosphinic acid, with a metal ion. The above organic acid metal salts only need to be solid at 20°C, that is, have a melting point above 20°C, and the organic acids and metal ions constituting the organic acid metal salts can be selected as appropriate. The melting point of the organic acid metal salt is preferably 100°C or higher, and more preferably 150°C or higher.

[0059] The metal constituting the organic acid metal salt can be any metal capable of forming a salt with the organic acid, such as lithium, sodium, potassium, magnesium, calcium, barium, zinc, or aluminum. The metal salt is preferably a sodium salt or a calcium salt, and more preferably a sodium salt.

[0060] The organic acid constituting the organic acid metal salt may have substituents such as halogen groups, hydroxyl groups, amino groups, alkyl groups, alkoxy groups, and epoxy groups on the aliphatic or aromatic groups in its molecular structure. Furthermore, it is preferable that the organic acid does not contain sulfur atoms or phosphorus atoms in its molecular structure, and it is more preferable that its constituent atoms are selected from carbon atoms, hydrogen atoms, nitrogen atoms, and oxygen atoms. Examples of such organic acids include organic carboxylic acids having 2 to 18 carbon atoms, such as acetic acid, propionic acid, butyric acid, hexanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, oleic acid, and linoleic acid. Among these, organic carboxylic acids having 10 to 18 carbon atoms are preferred, and linear organic carboxylic acids without substituents are even more preferred.

[0061] Specifically, organic acid metal salts that can be used include sodium acetate (melting point 324°C), calcium acetate (melting point 160°C), sodium stearate (melting point 220°C), and calcium stearate (melting point 179°C).

[0062] The amount of organic acid metal salt blended in the grease is preferably 0.5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and even more preferably 1 to 3 parts by mass, per 100 parts by mass of the total amount of base oil and thickener.

[0063] The grease preferably further contains an antioxidant as an additive. As antioxidants, amine-based antioxidants, phenol-based antioxidants, sulfur-based antioxidants, etc., can be used, and among these, amine-based antioxidants are preferred. Examples include phenyl-1-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, phenothiazine, N,N'-diisopropyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, and dialkyldiphenylamine (DDPA).

[0064] Furthermore, other additives such as rust inhibitors, esters, and oily agents such as alcohols may be added to the grease as needed. For example, it is preferable to add a rust inhibitor to ensure the rust-preventive performance of the grease itself. While there are no particular limitations on the rust inhibitor, ester-based rust inhibitors are preferred. Examples of ester-based rust inhibitors include partial esters of polyhydric alcohols such as sorbitan, sorbitol, pentaerythritol, sucrose, and glycerin with carboxylic acids such as oleic acid and lauric acid, and succinic acid half-esters. It is more preferable that the amount of ester-based rust inhibitor included is 0.2 to 0.6 parts by mass per 100 parts by mass of the total amount of base oil and thickener.

[0065] It is preferable that the grease does not contain additives that include phosphorus or sulfur atoms in its molecular structure. When these additives are included in the grease, the surface tension of the base oil decreases, which tends to increase the amount of dust generated. Examples of such additives include phosphate esters such as tricresyl phosphate, phosphite esters such as tricresyl phosphite, thiophosphates, thiophosphites, zinc alkyldithiophosphate (ZnDTP), molybdenum alkyldithiophosphate (MoDTP), and zinc dithiocarbamate (ZnDTC) as extreme pressure agents.

[0066] The consistency of grease (JIS K 2220) is in the range of 200 to 240. From the viewpoint of suppressing dust generation, a consistency in the range of 200 to 220 is preferable.

[0067] <Relationship between closing margin and leakage> In an embodiment of a rolling bearing 1 equipped with the aforementioned seal collapse suppression means St, grease flow suppression means GS (Figure 8), and radial change amount reduction means Rcr (Figure 10), and in a comparative example of a prior art rolling bearing, the relationship between the overlap (small, medium, large) and leakage was confirmed under the same bearing size, same grease filling amount, and specified operating conditions. In Figure 11, a "small" overlap is indicated by the solid line at the contact portion 15c of the main lip 15, a "medium" overlap is indicated by the dashed-dotted line at the contact portion 15c, and a "large" overlap is indicated by the double-dotted-dotted line.

[0068] In the comparative example, base oil leakage was observed at small, medium, and large tightening tolerances. In contrast, in the example, there was no base oil leakage at small, medium, and large tightening tolerances. In the example, the contact at the contact portion 15c of the main lip 15 is stable, improving sealing performance and exhibiting greater effectiveness against dust generation and base oil leakage. In the example, the contact at the contact portion 15c is stable, making the main lip 15 more elastically deformable. As a result, as shown in Figure 15, the example shows less fluctuation in contact force within the tightening tolerance range and a decrease in rotational torque compared to the comparative example.

[0069] <Rotational Torque> Figure 16 is a schematic longitudinal cross-sectional view of the rotational torque testing machine MT. Rotational torque was measured using the rotational torque testing machine MT shown in Figure 16 for the examples and comparative examples. In this rotational torque testing machine MT, the outer ring 3 is fitted and fixed to the housing Hs, and the inner ring 2 is fitted and fixed to the rotating shaft Sh. The inner ring 2 rotates as the rotating shaft Sh is rotated by a rotational drive source (not shown). A predetermined axial load is applied to one end face of the outer ring 3 via the housing Hs.

[0070] The bearing size for the example and comparative example was "6900", with an inner ring inner diameter of 10 mm, an outer ring outer diameter of 22 mm, and a width of 6 mm. The rotational torque was determined according to the following procedure (1) to (3). (1) Using a bearing in which a sealing member 6 is attached to only one side (one side) in the axial direction, the rotational torque T1 at a constant rotation is measured. (2) Measure the rotational torque T2 of the bearing with the sealing member 6 removed. (3) Calculate the rotational torque of the seal member alone (seal-only torque) from T1-T2. The above procedure was performed for both the example and comparative example, with n=3 and a rotational speed of 3600 min⁻¹. -1 Time: 30 min. (Using average data from 10 mins before the end of the test)

[0071] According to the torque comparison results of individual seals based on torque tests (average of n=3), as shown in Figure 17, the embodiment can reduce the individual seal torque by 25% compared to the comparative example.

[0072] <Effects and Effects> As described above, the rolling bearing 1 in Figure 1 is configured such that the seal tilt suppression means St prevents the entire seal member 6, including the inner circumference portion 13 (Figure 2), from tilting inward in the axial direction. As shown in Figure 5(b), the seal tilt suppression means St has an inclined surface 8aa on the inner surface 8a of the outer circumference portion 8 of the seal member 6 that contacts the seal groove 9 of the outer ring 3, which is inclined toward the inner diameter as it moves inward in the axial direction. This inclined surface 8aa reduces the rotational movement range of the seal member 6 compared to conventional structures.

[0073] Therefore, the sealing position of the sealing member 6 is stable when the bearing is inserted, and even when subjected to a reaction force due to the contact between the outer surface 7c of the sealing groove 7 of the inner ring 2 shown in Figure 2 and the main lip 15, the position of the sealing member 6 is less likely to shift. In this way, the sealing performance of the rolling bearing can be stabilized. In addition, since the change in the clamping force due to the bearing is reduced, robustness is improved.

[0074] As shown in Figure 6, an air hole 12 is provided on the outer circumference of the seal member 6 to release the internal pressure of the rolling bearing 1 (Figure 1). Therefore, by releasing the internal pressure of the bearing through the air hole 12 when the rolling bearing 1 (Figure 1) rotates, it is possible to suppress excessive changes in the tightening allowance of the seal member 6 and the outflow of grease caused by an increase in the internal pressure of the bearing.

[0075] As shown in Figure 3, the grease flow suppression means GS includes a reverse inclination shape in which the inner circumferential surface 16b of the sub-lip 16 is inclined toward the outer diameter as it moves axially outward. This reverse inclination shape of the sub-lip 16 suppresses the flow FL of grease from the inner circumferential surface 16b of the sub-lip 16 to the inner diameter side tip 15c of the main lip 15. In other words, when the axial direction of the rolling bearing is along the horizontal axis, the base oil Ky of the grease flowing along the inner surface of the seal can accumulate on the inner circumferential surface 16b of the sub-lip 16 and more reliably suppress its flow to the inner diameter side tip 15c of the main lip 15. As a result, the amount of dust generated from inside the bearing can be reduced compared to conventional structures.

[0076] As shown in Figure 18, the protrusion 15ba of the grease flow suppression means GS blocks the base oil Ky of the grease flowing along the inner surface of the seal, allowing it to escape in the circumferential direction. As shown in Figure 8, by providing the protrusion 15ba on the back surface Sm of the seal, it becomes easier to make the radial dimension B of the tip of the main lip 15 on the back surface Sm of the seal larger than the outer diameter dimension A of the end face of the inner ring 2. This prevents the main lip 15 from being properly inserted into and contacting the seal groove 7 without buckling, and prevents defects from occurring at the tip of the lip of the main lip 15. This grease flow suppression means GS increases the degree of design freedom and is effective in improving the insertability of the main lip 15 into the seal groove 7 and suppressing base oil leakage.

[0077] As shown in Figures 10 and 11, the radial change amount reduction means Rcr reduces the radial change amount Δa of the contact portion 15c of the main lip 15 to a predetermined value or less within the range of the interference fit. Therefore, even if the interference fit changes due to the oscillation of the inner ring 2 or pressure changes inside the bearing during bearing rotation, the sealing performance of the inner ring 2 with respect to the seal groove 7 can be stabilized. This reduces the amount of dust generated from inside the bearing and prevents foreign matter from entering from outside the bearing.

[0078] The axial protrusion amount of the bent portion Be is such that, in the state of maximum interference fit, the bottom Ks of the constricted portion 14 < the maximum protrusion position Pk of the bent portion Be ≤ the end face of the inner or outer ring. In this case, there is no change in the maximum distance on the axial side opposite the bearing for the entire seal member, and the bent portion Be does not protrude from the bearing end face. By making the seal member 6 this shape, the amount of elastic deformation at the bent portion Be increases. As a result, the rotation center of the approximately circular range of motion of the contact portion 15c of the main lip 15 moves axially toward the side opposite the bearing, making it easier to set the position of the contact portion 15c at the center of the interference fit to be near directly below the rotation center. This makes it possible to reduce the radial change amount Δa of the contact portion 15c of the main lip 15 compared to the conventional structure.

[0079] Furthermore, if the wall thickness Ta of the constricted portion is greater than the wall thickness Tb at the base of the constricted portion, the amount of elastic deformation on the inner diameter side of the constricted portion 14 can be increased. As a result, the amount of radial change Δa of the contact portion 15c of the main lip 15 within the interference fit range can be made even smaller than in conventional structures.

[0080] In addition to the sealing member 6 being equipped with a means Rcr for reducing radial change, the contact portion 15c connected to the lip body portion 15b is formed in an R shape that is normal to the outer surface 7c of the sealing groove 7. As a result, even when the internal pressure of the rolling bearing 1 (Figure 1) increases during rotation, the main lip 15 can suppress the intrusion of foreign matter from the atmosphere and suppress changes in the surface pressure distribution of the main lip 15. Therefore, it is possible to suppress unwanted increases in torque and unwanted overheating of the main lip 15.

[0081] As shown in Figure 18, by providing a bent portion Be, the contact area Ar between the main lip 15 and the insertion jig can be made wider than in conventional seal structures when the main lip 15 is inserted into the seal groove 7 (Figure 10). This increases the design flexibility of the insertion jig. As shown in Figure 19, the jig Jg can be used to push the lower inner diameter side of the bent portion Be inward in the axial direction. This makes it easier for the main lip 15 to move outward when the seal member 6 is inserted into the bearing, improving the ease of insertion of the main lip 15 into the seal groove 7. By providing the bent portion Be, the main lip 15 becomes more elastically deformable, improving the ease of seal insertion.

[0082] Furthermore, with respect to the grease, by adding a solid organic acid metal salt at 20°C to a specified combination of base oil and thickener, the organic acid metal salt can dissolve without affecting the surface tension of the base oil, and in cases where the supply of base oil is insufficient and wear is a concern, it can protect the steel surface as an extreme pressure agent. Applying such a grease is even more effective against dust generation from inside the bearing.

[0083] <Regarding other embodiments> In the following description, parts corresponding to matters previously described in each embodiment will be denoted by the same reference numerals, and redundant explanations will be omitted. When only a part of the configuration is described, the other parts of the configuration will be the same as those in the previously described embodiment unless otherwise specified. Identical configurations will produce the same effects. Not only are combinations of the parts specifically described in each embodiment possible, but partial combinations of embodiments are also possible, provided that there are no particular problems with the combination.

[0084] [Second embodiment: Figure 12, one-sided seal] As shown in Figure 12, the sealing member 6 may be provided only on one axial side of the rolling bearing 1. In this case, the number of parts and the number of machining steps for seal grooves, etc., can be reduced compared to a rolling bearing with sealing members on both axial sides, thereby reducing costs.

[0085] [Third embodiment: Figures 13-14, resin-made retainer] As shown in Figures 13 and 14, the retainer 5 is made of synthetic resin and may be a two-piece retainer formed by engaging two identical annular bodies 5a, 5a. This retainer 5 holds the ball 4 in pockets Pt, which have a cylindrical shape in the axial direction. Each annular body 5a has a plurality of semi-cylindrical pocket wall portions 5c and a plurality of connecting plate portions 5b. The pockets Pt are formed when two pocket wall portions 5c, 5c are combined with each other in the axial direction. The pockets Pt are arranged circumferentially. The retainer 5 has engaging holes Ka and engaging claws Kb in the connecting plate portions 5b between the pockets Pt that engage with each other. The retainer 5 is assembled by engaging the engaging claws Kb in the engaging holes Ka and engaging the two identical annular bodies 5a, 5a. The pocket shape of the retainer 5 may be spherical.

[0086] In each embodiment, it is also possible to omit the air holes on the outer periphery of the sealing member. In other words, the sealing member may be configured without air holes. In deep groove ball bearings, corrugated steel cages may be used. Rolling bearings are not limited to deep groove ball bearings; they can be applied to various types of bearings, including angular contact ball bearings, tapered roller bearings, and cylindrical roller bearings. The grease used to seal rolling bearings is not limited to the low-dusting grease mentioned above. For example, general-purpose grease may be used.

[0087] While embodiments for carrying out the present invention have been described above based on the embodiments, the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0088] 1...Rolling bearing, 2...Inner ring, 3...Outer ring, 4...Ball (rolling element), 6...Seal member, 7...Seal groove, 8...Outer circumference portion, 8aa...Inclined surface, 9...Seal groove, 10...Core metal, 13...Inner circumference portion, 14...Neck portion, 15...Main lip, 16...Sub-lip, Be...Bent portion, St...Seal collapse suppression means, GS...Grease flow suppression means, Rcr...Radial change amount reduction means, Un...Uneven portion

Claims

1. A rolling bearing comprising an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a sealing member that closes the bearing space between the inner ring and the outer ring, wherein the sealing member has a main lip that contacts the seal groove of the inner ring with an overlap, and a secondary lip that protrudes axially inward from its base end and does not contact the seal groove, and grease is sealed in the bearing space, The sealing member is A seal tilt suppression means that prevents the inner circumferential portion of the seal member from tilting inward in the axial direction, A grease flow suppression means that suppresses the flow of grease from the inner circumferential surface of the sub-lip to the inner diameter side tip of the main lip, Within the aforementioned tightening allowance range, a radial change amount reduction means for reducing the radial change amount of the main lip to a predetermined value or less, A rolling bearing equipped with [a specific feature].

2. A rolling bearing according to claim 1, wherein the sealing member comprises a core metal, a constricted portion located radially inward from the inner diameter portion of the core metal and decreasing in wall thickness toward the inner diameter side, a bent portion connected to the inner diameter portion of the constricted portion, and the main lip connected to the inner diameter portion of the bent portion, wherein the means for reducing radial variation is such that, at the maximum interference fit, the maximum axially outward protrusion position Pk of the bent portion is axially outward from the bottom Ks of the axially outward portion of the constricted portion, and is the same as or axially inward with respect to the axial position Tm of the end face of the inner ring or outer ring.

3. A rolling bearing according to claim 2, wherein the axial wall thickness Ta at the bottom of the constricted portion is greater than the radial wall thickness Tb from the inner diameter portion of the constricted portion to the inner circumferential surface of the bent portion.

4. A rolling bearing according to claim 1 or claim 2, wherein the seal tilt suppression means has an inclined surface on the outer circumference of the seal member, the inner surface that contacts the seal groove of the outer ring, which is inclined toward the inner diameter as it moves toward the axially inward direction, and the angle of the inclined surface is set in the following relationship with respect to a plane perpendicular to the axial direction. 0° < Angle of the inclined surface ≤ Angle of inclination of the inner surface in the seal groove of the outer ring

5. A rolling bearing according to claim 1 or claim 2, wherein the grease flow suppression means is provided with an uneven surface between the inner circumferential surface of the sub-lip and the axially inner surface of the main lip.

6. A rolling bearing according to claim 5, wherein, as a method for providing irregularities on the back surface of the seal of the grease flow suppression means, a protrusion is provided at the minimum inner diameter position on the back surface of the seal.

7. A rolling bearing according to claim 1 or claim 2, wherein the sealing member is provided on only one axial side or on both axial sides of the rolling bearing.

8. In the rolling bearing according to claim 1 or claim 2, the grease comprises a base oil and a thickener. The base oil comprises synthetic hydrocarbon oil and ether oil, and has a kinematic viscosity of 120 mm at 40°C. ２ A mixed oil of / s or more, The thickener is an aliphatic diurea compound and an alicyclic diurea compound, and is present in an amount of 12 to 15 parts by mass per 100 parts by mass of the total amount of the base oil and the thickener, and the grease has a mixed consistency of 200 to 240 and contains an organic acid metal salt that is solid at 20°C, for a rolling bearing.

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