Seal member and rolling bearing with seal

Abstract

To provide a seal member capable of maintaining excellent water resistance and muddy water resistance over a long period of time.SOLUTION: A large number of fine protrusions 23 are formed on an outer side surface of a sealing member 5 so as to form a water-repellent surface with a water contact angle θ of 90° or more.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a seal member and a sealed rolling bearing using the seal member. [Background technology]

[0002] Sealed rolling bearings are often used as bearings that support rotating shafts in automobiles, industrial machines, etc. Sealed rolling bearings have an outer ring, an inner ring disposed radially inside the outer ring, multiple rolling elements incorporated in an annular bearing space formed between the outer ring and the inner ring, and annular sealing members that close the axial end openings of the bearing space between the outer ring and the inner ring (see, for example, Patent Documents 1 and 2).

[0003] This sealed rolling bearing has the end openings of the bearing space physically sealed with a sealing member, so that even when used in an environment exposed to foreign matter such as water or muddy water, it is possible to prevent the foreign matter from entering the bearing space.

[0004] Furthermore, in the sealed rolling bearing of Patent Document 1, in order to improve water resistance and muddy water resistance in harsh environments, the outer surface of the seal member (the side of the seal member opposite the bearing space side) is coated with a water-repellent film (such as a PTFE film) to prevent water or muddy water from accumulating on the seal lip of the seal member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-332990 A [Patent Document 2] JP 2020-133770 A Summary of the Invention [Problem to be solved by the invention]

[0006] The sealed rolling bearing of Patent Document 1 has a water-repellent coating (such as a PTFE coating) on ​​the outer surface of the seal member, and therefore exhibits excellent water resistance and muddy water resistance in the early stages of use.

[0007] However, since the water-repellent coating (such as a PTFE coating) gradually peels off and deteriorates over time, the water-repellent properties of the outer surface of the seal member gradually decrease. Therefore, the sealed rolling bearing of Patent Document 1 has a problem in that it is difficult to maintain water resistance and muddy water resistance over a long period of time.

[0008] An object of the present invention is to provide a seal member capable of maintaining excellent water resistance and muddy water resistance for a long period of time. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a seal member having the following configuration. [Configuration 1] In a sealing member that prevents foreign matter from entering from the outside to the inside, A sealing member, characterized in that a large number of fine protrusions are formed on an outer side surface of the sealing member so that the outer side surface becomes a water-repellent surface with a contact angle of water of 90° or more.

[0010] By adopting this configuration, the outer side surface of the seal member is a water-repellent surface with a water contact angle of 90° or more, so water or muddy water can be prevented from accumulating in the sealing portion of the seal member, and excellent water resistance and muddy water resistance can be obtained. Here, the water repellency of the outer side surface of the seal member is physically imparted by the lotus effect caused by forming a large number of fine protrusions, so the water repellency is unlikely to decrease over time. Therefore, it is possible to maintain excellent water resistance and muddy water resistance for a long period of time.

[0011] [Configuration 2] A sealing member as described in configuration 1, in which the value of A / (B×C) is 0.26 or less, where B (μm) is the diameter of the tip surfaces of the numerous fine protrusions, A (μm) is the distance between the tip surfaces of the numerous fine protrusions, and C (μm) is the height of the numerous fine protrusions.

[0012] By adopting this configuration, it is possible to reliably impart water repellency due to the lotus effect to the outer side surface of the seal member.

[0013] [Configuration 3] Each of the numerous fine protrusions has a circular tip surface, and the diameter B (μm) of the tip surface is 80 μm or less; the numerous fine protrusions are uniformly arranged in a square or equilateral triangular lattice pattern, and the distance A (μm) between the tip surfaces of the fine protrusions is 120 μm or less; 3. The sealing member according to claim 1 or 2, wherein the height C (μm) of the numerous fine protrusions is 80 μm or less.

[0014] When this configuration is adopted, the size of the tip face of each of the fine protrusions formed on the outer side of the sealing member is sufficiently smaller than the size of a water drop, and the fine protrusions are uniformly arranged in a lattice of minute squares or equilateral triangles that are sufficiently smaller than the size of a water drop.Furthermore, the area ratio of the tip faces of the fine protrusions is sufficiently small, so that the contact angle of water on the outer side of the sealing member is reliably 90° or greater, making it possible to reliably impart water repellency due to the lotus effect.

[0015] [Configuration 4] The seal member is made of a circular plate-shaped core metal and rubber vulcanized and bonded to the core metal, 4. The sealing member according to any one of configurations 1 to 3, wherein the numerous fine protrusions are formed on the surface of the rubber.

[0016] When this configuration is adopted, the sealing member is formed using a molding die in which a large number of micro recesses corresponding to the large number of micro projections on the outer side surface of the sealing member are formed on the inner surface of the cavity, so that the large number of micro projections can be easily formed. Furthermore, since rubber is generally a hydrophobic material, it is possible to impart particularly excellent water repellency by forming a large number of micro projections.

[0017] [Configuration 5] The sealing member is made of a metal core having a circular ring shape and a resin bonded to the metal core, 4. The sealing member according to any one of configurations 1 to 3, wherein the numerous fine protrusions are formed on the surface of the resin.

[0018] By adopting this configuration, a large number of fine protrusions can be easily formed by forming the sealing member using a molding die in which a large number of fine recesses are formed on the inner surface of a cavity corresponding to the large number of fine protrusions on the outer side of the sealing member.

[0019] [Configuration 6] the outer side surface of the seal member has a non-projection surface between adjacent micro-projections; 6. The sealing member according to any one of configurations 1 to 5, wherein the surface roughness Ra of the non-projection surface is set to 0.35 μm or less.

[0020] By adopting this configuration, when a sealing member is formed using a molding die, the non-protruding surfaces between adjacent micro-protrusions of the sealing member correspond to the inner surface of the cavity of the molding die, and since the surface roughness Ra of the inner surface of the cavity of the molding die is 0.35 μm or less, a large number of micro-recesses corresponding to the large number of micro-protrusions on the outer side surface of the sealing member can be precisely formed on the inner surface of the cavity, and as a result, it becomes possible to precisely form a large number of micro-protrusions on the outer side surface of the sealing member.

[0021] [Configuration 7] 7. The sealing member according to any one of configurations 1 to 6, wherein the numerous fine protrusions are coated with a film made of a water-repellent material.

[0022] The present invention also provides a sealed rolling bearing using the above-mentioned seal member, having the following configuration. [Configuration 8] The outer ring and an inner ring disposed radially inside the outer ring; a plurality of rolling elements installed in an annular bearing space formed between the outer ring and the inner ring; and a seal member according to any one of configurations 1 to 7, which closes one axial end opening of the bearing space.

[0023] [Configuration 9] A seal lip is formed at a radially inner end of the seal member and is in sliding contact with an outer periphery of the inner ring, 9. A sealed rolling bearing according to configuration 8, wherein an outer periphery of the inner ring is formed with a cylindrical surface extending in the axial direction with a constant outer diameter from the portion with which the seal lip slides and connected to an axial end face of the inner ring.

[0024] With this configuration, a cylindrical surface is formed on the outer periphery of the inner ring that extends axially at a constant outer diameter from the portion where the seal lip slides and connects to the axial end face of the inner ring, so that water repelled by the outer side surface of the seal member is less likely to accumulate in the portion where the seal lip on the outer periphery of the inner ring slides, compared to when the portion where the seal lip on the outer periphery of the inner ring slides is formed as a recessed groove, thereby achieving excellent water resistance and muddy water resistance. Effect of the Invention

[0025] The seal member of the present invention has an outer side surface that is water-repellent with a water contact angle of 90° or more, so that water or muddy water can be prevented from accumulating in the sealing portion of the seal member, and excellent water resistance and muddy water resistance can be obtained. Here, the water repellency of the outer side surface of the seal member is physically imparted by the lotus effect caused by forming a large number of fine protrusions, so that the water repellency is unlikely to decrease over time. Therefore, it is possible to maintain excellent water resistance and muddy water resistance for a long period of time. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a cross-sectional view showing a sealed rolling bearing using a seal member according to an embodiment of the present invention. [Diagram 2] Enlarged view of the seal member and its surroundings in Figure 1 [Diagram 3] FIG. 3 is an enlarged cross-sectional view showing a number of fine protrusions formed on the axially outer side surface of the seal member shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a modification of the fine protrusion shown in FIG. [Diagram 5] FIG. 4 is a view of the numerous fine protrusions shown in FIG. 3, viewed from the tip side of the fine protrusions. [Figure 6] FIG. 6 is a diagram showing a modified example of the arrangement of the fine protrusions shown in FIG. 5. [Figure 7] An illustration showing the contact angle of water DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] 1 shows a sealed rolling bearing using a seal member 5 according to an embodiment of the present invention. This sealed rolling bearing has an outer ring 1, an inner ring 2 arranged coaxially on the radial inside of the outer ring 1, a plurality of rolling elements 4 assembled at intervals in the circumferential direction in an annular bearing space 3 formed between the outer ring 1 and the inner ring 2, an annular seal member 5 that closes one axial end opening of the bearing space 3, an annular seal member 6 that closes the other axial end opening of the bearing space 3, and a cage 7 that maintains the circumferential spacing of the plurality of rolling elements 4. A lubricant is sealed in the bearing space 3.

[0028] The inner circumference of the outer ring 1 is formed with an outer ring raceway groove 8 with which the rolling elements 4 roll, a pair of outer ring shoulders 9 located axially outward of the outer ring raceway groove 8, and a pair of seal fixing grooves 10 located axially outward of the outer ring shoulders 9. The pair of outer ring shoulders 9 are bank-shaped portions extending circumferentially on both sides of the outer ring raceway groove 8 in the axial direction. The seal fixing grooves 10 are grooves extending circumferentially formed adjacent to the axially outward sides of the outer ring shoulders 9. Seal members 5, 6 are fitted and fixed in the pair of seal fixing grooves 10, respectively.

[0029] The outer periphery of the inner ring 2 is formed with an inner ring raceway groove 11 with which the rolling elements 4 roll, a pair of inner ring shoulders 12 located axially outward of the inner ring raceway groove 11, and a pair of cylindrical surfaces 13 located axially outward of the inner ring shoulders 12. The pair of inner ring shoulders 12 are bank-shaped portions extending circumferentially on both sides of the inner ring raceway groove 11 in the axial direction. The cylindrical surfaces 13 are formed adjacent to the axially outward sides of the inner ring shoulders 12. A seal lip 14 formed at the radially inner ends of the seal members 5 and 6 is in sliding contact with the cylindrical surfaces 13.

[0030] Here, the rolling elements 4 are balls. The rolling elements 4 are radially sandwiched between an outer ring raceway groove 8 and an inner ring raceway groove 11. The outer ring raceway groove 8 and the inner ring raceway groove 11 are grooves whose cross sections perpendicular to the circumferential direction are concave arc-shaped.

[0031] The sealing member 5 blocks the end opening of the bearing space 3 between the outer ring 1 and the inner ring 2, thereby preventing foreign matter such as water or muddy water from entering the bearing space 3 from the outside (left side in the figure) to the inside (right side in the figure).

[0032] 2, the seal member 5 is composed of an annular plate-shaped core metal 15 and rubber 16 vulcanization-bonded to the core metal 15. The core metal 15 is formed by press-molding a steel plate such as a cold-rolled steel plate or a stainless steel plate. The core metal 15 has an annular plate portion 17 perpendicular to the axial direction, an annular rim-bent portion 18 formed by bending the radial outer end of the annular plate portion 17 axially inward, and an inclined portion 19 extending axially inward from the radial inner end of the annular plate portion 17 toward the radial inner side.

[0033] The rubber 16 is made of a rubber material such as nitrile rubber or acrylic rubber. The rubber 16 is bonded to the surface of the core metal 15 by vulcanizing the rubber 16 while the core metal 15 is placed in the mold for forming the seal member 5. The rubber 16 has an outer surface rubber portion 20 bonded to the axially outer side surface of the annular plate portion 17 and the inclined portion 19 of the core metal 15, an outer peripheral rubber portion 21 extending radially outward from the bent edge portion 18 of the core metal 15, and a seal lip 14 extending radially inward from the inclined portion 19 of the core metal 15. The outer peripheral rubber portion 21 is fitted into the seal fixing groove 10 on the inner circumference of the outer ring 1. The seal lip 14 is in sliding contact with the cylindrical surface 13 on the outer circumference of the inner ring 2. The cylindrical surface 13 extends axially from the portion where the seal lip 14 is in sliding contact with the cylindrical surface 13 at a constant outer diameter and is connected to the axial end surface 22 of the inner ring 2.

[0034] As shown in Fig. 3 and Fig. 5, a large number of fine protrusions 23 are formed on the side surface of the seal member 5 shown in Fig. 2 opposite to the bearing space 3 side (axially outer side). These fine protrusions 23 are formed on the surface of the rubber 16. Specifically, the fine protrusions 23 are formed on the axially outer side surfaces of the outer peripheral rubber part 21, the outer surface rubber part 20, and the seal lip 14, as shown by the thick lines in Fig. 2. In the figure, an example is shown in which a large number of fine protrusions 23 are formed on the axially outer side surfaces of the outer peripheral rubber part 21, the outer surface rubber part 20, and the seal lip 14, respectively, but the large number of fine protrusions 23 may be formed only on the axially outer side surfaces of the outer surface rubber part 20 and the seal lip 14 among the outer peripheral rubber part 21, the outer surface rubber part 20, and the seal lip 14.

[0035] As shown in Fig. 5, the numerous fine projections 23 are uniformly arranged in a square lattice pattern. Each of the numerous fine projections 23 has a circular tip surface 24. Here, the interval A (μm) between the tip surfaces 24 of the fine projections 23 shown in Figs. 3 and 5 is set to 120 μm or less, the diameter B (μm) of the tip surface 24 of the fine projections 23 shown in Fig. 3 is set to 80 μm or less, and the height C (μm) of the fine projections 23 shown in Fig. 3 is set to 80 μm or less. In addition, the dimensions of the fine projections 23 are set so that the value of A / (B × C) is 0.26 or less when the diameter of the tip surface 24 of the fine projections 23 shown in Fig. 3 is B (μm), the interval between the tip surfaces 24 of the fine projections 23 is A (μm), and the height of the fine projections 23 is C (μm).

[0036] 3, a flat non-projection surface 25 is formed between adjacent fine projections 23. The surface roughness Ra of the non-projection surface 25 is set to 0.35 μm or less.

[0037] By forming a large number of fine protrusions 23 as shown in Fig. 3 and Fig. 5, the side surface of the sealing member 5 shown in Fig. 2 becomes a water-repellent surface with a water contact angle θ (see Fig. 7) of 90° or more due to the lotus effect. The water contact angle θ can be measured by the sessile drop method defined in the Japanese Industrial Standard JISR3257:1999 "Testing Method for Wettability of Glass Substrate Surfaces". The lotus effect refers to an effect in which, when a surface in contact with water is a surface on which a large number of fine protrusions 23 are formed, arranged with fine gaps between them that prevent water from entering, the contact state of water becomes point contact with the tip surface 24 of the fine protrusions 23, resulting in a large contact angle θ of water. The contact angle θ of water at this time can be calculated by the Cassie-Baxter formula. Note that in Fig. 7, the size of the fine protrusions 23 is exaggerated to make the fine protrusions 23 easier to understand, but the actual fine protrusions 23 are extremely small.

[0038] The Cassie-Baxter equation is as follows, where the area fraction of substance 1 is f1, the area fraction of substance 2 is f2, the contact angle of water on the surface of substance 1 is θ1, and the contact angle of water on the surface of substance 2 is θ2. cosθ=f1cosθ1+f2cosθ2 Here, if substance 2 is air, the contact angle θ2 is 180°, and since f2=1-f1, the condition θ1≧90° can be found by modifying the Cassie-Baxter equation as follows: f1≦1 / (1+cosθ1) Furthermore, if the rubber material forming the rubber 16 of the seal member 5 is substance 1 and the contact angle θ1 of water on the surface of substance 1 is 70°, the above formula becomes as follows: f1≦0.745

[0039] In this sealed rolling bearing, the side of seal member 5 shown in Fig. 2 opposite to bearing space 3 (the left side in the figure) is a water-repellent surface with a water contact angle θ (see Fig. 7) of 90° or more, so water or muddy water can be prevented from accumulating in the sealed portion of seal member 5, and excellent water resistance and muddy water resistance can be obtained. Here, the water repellency of the side surface of seal member 5 is physically imparted by the lotus effect caused by forming a large number of fine protrusions 23 as shown in Figs. 3 and 5, so that the water repellency is unlikely to decrease over time. Therefore, it is possible to maintain excellent water resistance and muddy water resistance for a long period of time.

[0040] In addition, in this sealed rolling bearing, as shown in Figures 2 and 3, the size of the tip surface 24 of each of the fine protrusions 23 formed on the side of the seal member 5 is sufficiently smaller than the size of a water droplet (usually a few mm), and as shown in Figure 5, these fine protrusions 23 are uniformly arranged in a fine square lattice pattern sufficiently smaller than the size of a water droplet.Furthermore, the area ratio f1 of the tip surface 24 of the fine protrusions 23 (the ratio of the area of ​​the tip surface 24 to the total area of ​​the surface on which the fine protrusions 23 are formed) is sufficiently small, so that the contact angle θ of water on the side of the seal member 5 is reliably 90° or more, making it possible to reliably impart water repellency due to the lotus effect.

[0041] Furthermore, in this sealed rolling bearing, the numerous fine protrusions 23 shown in Figures 3 and 5 are formed on the surface of the rubber 16 shown in Figure 2, so that by forming the seal member 5 shown in Figure 2 using a molding die having a large number of fine recesses formed on the inner surface of a cavity corresponding to the numerous fine protrusions 23 shown in Figures 3 and 5, it is possible to easily form the numerous fine protrusions 23 shown in Figures 3 and 5. Furthermore, since the rubber 16 is generally a hydrophobic material, by forming the numerous fine protrusions 23, it is possible to impart particularly excellent water repellency.

[0042] 2, this sealed rolling bearing has a cylindrical surface 13 formed on the outer periphery of the inner ring 2 that extends axially at a constant outer diameter from the portion where the seal lip 14 slides and connects to the axial end face 22 of the inner ring 2, so that water repelled by the side of the seal member 5 is less likely to accumulate in the portion of the outer periphery of the inner ring 2 where the seal lip 14 slides, compared to when the portion of the outer periphery of the inner ring 2 where the seal lip 14 slides is formed as a recessed groove. This provides excellent water resistance and muddy water resistance.

[0043] Furthermore, in this sealed rolling bearing, the surface roughness Ra of the non-projection surface 25 shown in Fig. 3 is set to 0.35 µm or less. That is, when the seal member 5 shown in Fig. 2 is formed using a molding die, the non-projection surface 25 between adjacent fine projections 23 shown in Fig. 3 corresponds to the inner surface of the cavity of the molding die, and the surface roughness Ra of the inner surface of the cavity of the molding die is set to 0.35 µm or less. Therefore, a large number of fine recesses corresponding to the large number of fine projections 23 shown in Fig. 3 can be formed accurately on the inner surface of the cavity of the molding die, and as a result, it is possible to form the large number of fine projections 23 shown in Fig. 3 accurately.

[0044] In the sealed rolling bearing of this embodiment, a test was conducted to confirm that when a large number of fine protrusions 23 are formed on the side surface of the seal member 5, the side surface of the seal member 5 becomes a water-repellent surface with a water contact angle θ of 90° or more due to the lotus effect. The test results are shown in Table 1. [Table 1]

[0045] From this test result, it can be confirmed that a surface with an A / (B×C) value of 0.26 or less has a water-repellent surface with a water contact angle θ of 90° or more. The rubber 16 of the sealing member 5 used in this test is formed from a rubber material with a water contact angle θ1 of 70°.

[0046] In the above embodiment, as shown in Fig. 5, a large number of fine protrusions 23 are uniformly arranged in a square lattice pattern, but as shown in Fig. 6, a large number of fine protrusions 23 may be uniformly arranged in a regular triangular lattice pattern. In addition, in the above embodiment, as shown in Fig. 3, a cylindrical fine protrusion 23 is used as an example, but as shown in Fig. 4, a truncated cone-shaped fine protrusion 23 may be used. Even in this case, the same effects as those of the above embodiment can be achieved. The shape of the fine protrusions 23 can be a triangular pyramid, a square pyramid, a triangular prism, a square prism, a hemisphere, or the like.

[0047] In the above embodiment, the seal member 5 is formed of the annular plate-shaped core metal 15 and the rubber 16 vulcanized and bonded to the core metal 15, but the seal member 5 may be formed of the annular plate-shaped core metal 15 and a resin bonded to the core metal 15, and a large number of fine protrusions 23 may be formed on the surface of the resin. Even in this case, as in the above embodiment, the seal member 5 is formed using a molding die in which a large number of fine recesses corresponding to the large number of fine protrusions 23 on the side surface of the seal member 5 are formed on the inner surface of the cavity, so that a large number of fine protrusions 23 can be easily formed.

[0048] It is also possible to coat the fine projections 23 with a film made of a material that is water repellent.

[0049] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0050] 1 Outer ring 2. Inner Circle 3 Bearing space 4 Rolling elements 5. Sealing material 13 Cylindrical Surface 14 Sealing lip 15 Core wire 16 Rubber 22 Axial end face 23 Microscopic protrusions 24 Tip surface of fine projection 25 Non-protruding surface A: Distance between the tip faces of the fine projections B: Diameter of the tip of the micro-projection C. Height of micro projection

Claims

1. A sealing member (5) for preventing the intrusion of foreign matter from the outside to the inside, A sealing member characterized in that a large number of fine protrusions (23) are formed on the outer side surface of the sealing member (5) so that the outer side surface becomes a water-repellent surface with a water contact angle (θ) of 90° or more.

2. 2. The sealing member according to claim 1, wherein the diameter of the tip surfaces (24) of the numerous fine protrusions (23) is B (μm), the distance between the tip surfaces (24) of the numerous fine protrusions (23) is A (μm), and the height of the numerous fine protrusions (23) is C (μm), the value of A / (B x C) is 0.26 or less.

3. Each of the numerous fine projections (23) has a circular tip surface (24), and the diameter B (μm) of the tip surface (24) is 80 μm or less; The numerous fine projections (23) are uniformly arranged in a square or equilateral triangular lattice pattern, and the distance A (μm) between the tip faces (24) of the fine projections (23) is 120 μm or less; 3. The sealing member according to claim 1, wherein the height C (μm) of the numerous fine projections (23) is 80 μm or less.

4. The seal member (5) is composed of a circular plate-shaped core metal (15) and a rubber (16) vulcanized and bonded to the core metal (15).

3. The seal member according to claim 1, wherein the numerous fine projections (23) are formed on the surface of the rubber (16).

5. The seal member (5) is composed of a circular plate-shaped core metal (15) and a resin bonded to the core metal (15), 3. The sealing member according to claim 1, wherein the numerous fine projections (23) are formed on the surface of the resin.

6. The outer side surface of the seal member (5) has a non-projected surface (25) between adjacent micro-projections (23), 3. The seal member according to claim 1, wherein the surface roughness Ra of the non-projection surface is set to 0.35 [mu]m or less.

7. 3. The sealing member according to claim 1, wherein the numerous fine projections (23) are coated with a film made of a water-repellent material.

8. An outer ring (1), an inner ring (2) disposed radially inside the outer ring (1); a plurality of rolling elements (4) installed in an annular bearing space (3) formed between the outer ring (1) and the inner ring (2); 3. A sealed rolling bearing comprising: a seal member (5) according to claim 1 or 2, which closes one axial end opening of the bearing space (3).

9. A seal lip (14) that slides against the outer periphery of the inner ring (2) is formed at the radially inner end of the seal member (5), 9. A sealed rolling bearing according to claim 8, wherein a cylindrical surface (13) is formed on the outer periphery of the inner ring (2), the cylindrical surface (13) extending in the axial direction with a constant outer diameter from the portion with which the seal lip (14) slides and connects to an axial end face (22) of the inner ring (2).

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