JP2017008964A - Sealed bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact seal type sealed bearing that is light-weight and compact and can attain high sealability, even in an environment having a cryogenic temperature of -100°C or less or a high temperature of 250°C or more, or an environment having large temperature change.SOLUTION: A sealed bearing 1 includes an inner ring 2 and an outer ring 3 as a bearing ring, a plurality of rolling bodies 4 held by a holder 5 between the inner and outer rings, and a seal body 6 arranged at an opening part between the inner and outer rings and sealing the internal space of the bearing. The sealing body 6 is formed of meta-type wholly aromatic polyamide fiber, one end part of the seal body is fixed to the outer ring, the other end part thereof slides while elastically contacting with the inner ring 2 by a predetermined elastically deformable amount, and thereby the seal body seals the internal space of the bearing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rolling bearing provided with a sealing device.

  Rolling bearings used in dusty environments may shorten the service life due to dust entering the inside of the bearing and scratching the raceway surface, and a sealing device is provided outside or inside the bearing. When the sealing device is provided outside the bearing, it may be necessary to reduce the size and weight in addition to the reason that the number of parts increases, and it is preferable to provide the sealing device inside the bearing.

  When a sealing device is provided inside the bearing, a sealing body is fixed to either the rotating side or the stationary side of the bearing ring, and dust penetration is prevented by reducing or eliminating the gap between the sealing body and the other bearing ring. It becomes a structure to prevent. In order to obtain a particularly high sealing performance, an elastomer, engineering plastic, fiber, or the like is employed as the sealing body, and a structure is employed in which the other raceway is elastically contacted and slid without gaps.

  In general, in order to improve the sealing performance by the sealing body, the amount of elastic deformation at the elastic contact portion must be increased, and the generated stress increases and wears easily, so there is a trade-off between torque and seal life. Become. In particular, in the case of engineering plastics, a large amount of elastic deformation cannot be set because of high rigidity and avoiding high surface pressure at the elastic contact portion. In particular, in applications where the temperature changes greatly, the relative distance between the seal body and the bearing of the sliding partner also changes with changes in the dimensions of the bearing and seal body due to temperature and changes in the internal clearance of the bearing. Without setting, there is a high risk of gaps.

  When applying a fiber as a sealing body, there is a gap between the fibers, and since the elasticity of the sealing body is exhibited by the movement of the fiber, the generated stress for deformation is much smaller compared to elastomers and engineering plastics. The elastic deformation amount of the elastic contact portion can be set large, and can be applied even in usages where the temperature change is large.

  The range of use of the sealing body is also limited by the modification of the material due to temperature. For example, silicone rubber, which is an elastomer, becomes brittle at about −60 ° C. at low temperatures and deteriorates due to main chain breakage at about 200 ° C. at high temperatures, so that the elasticity of the rubber required for the sealing body is lost. Polytetrafluoroethylene (PTFE) resin, which is an engineering plastic, begins to deteriorate at about 250 ° C, and becomes brittle at about -100 ° C at low temperatures. There is also a risk and it is difficult to use at extremely low temperatures.

  Traditionally, wool and polyester resin nonwoven fabrics have been widely used for fiber seals. However, the use temperature range of these fibers is also limited by the modification of the material. For example, polyester resin becomes brittle at about -70 ° C and melts at about 250 ° C. there were. In addition, woven fabrics and knitted fabrics can be expected to increase strength and prevent fibers from falling off. However, the regular orientation of the fibers may increase the dimensional change of the sealing body itself against temperature changes. There is.

Japanese Patent No. 3128062 Japanese Utility Model Publication No. 4-48336

  For example, Patent Document 1 and Patent Document 2 are proposed as specific examples of the sealing structure provided inside the bearing. Patent Document 1 describes a sealing structure using an elastomer or engineering plastic as a sealing body. Patent Document 1 uses an elastomer or engineering plastic that is an elastic body as a seal body, so that the seal body is elastically deformed at the contact portion between the seal body and the race (here, a sliding member fitted to a shaft). It has a structure that keeps hermetically sealed.

  However, when the temperature change is large, the relative position of the seal body and the sliding partner member changes due to the difference in the linear expansion coefficient between the seal body and the sliding counterpart member or the change in the bearing internal clearance. The positional relationship that maximizes the distance between the members must be calculated, and the amount of elastic deformation must be fitted in advance so that there is no gap. For example, even if only the dimensional change due to the difference in linear expansion coefficient is considered, the sliding counterpart member is bearing steel, the sealing body is slid at a position of PTFE resin, diameter 10 mm, the temperature change is 100 ° C., If an attempt is made to fit the amount of change in the distance of the sliding member to the seal body as an elastic deformation amount, the generated hoop stress slightly exceeds the tensile strength of the PTFE resin. Even in an environment where there is no temperature change, depending on the use temperature, for example, silicone rubber and PTFE resin cannot be applied because of the above-described material modification.

  Patent Document 2 describes a sealing structure in which a porous lip made of woven fabric or felt is used as a sealing body (filter seal having a through hole). In this device, a porous lip is used for the purpose of filtering the lubricating oil, and the porous lip is held by a core bar extending to the vicinity of the outer diameter of the inner ring to strengthen the waist.

  However, in Patent Document 2, there is no limitation regarding the material of the filter, and in reality, it is considered that a nonwoven fabric of wool or polyester resin is used as described above, and the operating temperature range is limited. . There is no knowledge about the amount of elastic deformation at the time of elastic contact of the porous lip with the raceway.

  As described above, there are no seal bodies that can be used at extremely low temperatures of −100 ° C. or lower or high temperatures of 250 ° C. or higher because of the modification of the materials of elastomers, engineering plastics, and fiber seal bodies that have been conventionally used. It was. In addition, a structure that can maintain hermeticity even when the temperature change is large has not been clarified.

  The present invention has been made in order to cope with such problems, and is lightweight, compact, and has high sealing performance even in an extremely low temperature of −100 ° C. or lower, an environment of 250 ° C. or higher, or an environment with a large temperature change. It is an object of the present invention to provide a contact seal type sealed bearing that can be realized.

  The sealed bearing of the present invention is a bearing disposed in a pair of race rings, a plurality of rolling elements interposed between the race rings, a cage for holding the rolling elements, and an opening between the pair of race rings. A sealed bearing comprising a sealing body for sealing an inner space, wherein the sealing body is formed of a meta-type wholly aromatic polyamide fiber, and one end of the sealing body is fixed to one of the bearing rings, The other end portion of the seal body is in sliding contact with the other of the raceway to seal the bearing inner space.

  The seal body is in sliding contact with the other race ring while being elastically deformed, and the diameter of the seal body is A (mm) when the diameter of the slide contact portion position with the seal body in the other race ring is defined as A (mm). The amount of elastic deformation in the direction is A / 100 (mm) or more.

  The seal body is a woven fabric, a nonwoven fabric, or a knitted fabric of the meta-type wholly aromatic polyamide fiber. Further, the seal body is selected from a structure in which a sliding contact portion with the other raceway is impregnated with a lubricating resin and a structure in which reinforcing fibers are knitted into at least a part other than the sliding contact portion. It is characterized by having at least one.

  The other raceway ring is characterized in that a peripheral surface having a diameter larger than a diameter of a sliding contact portion position with the seal body is provided between the seal body and the rolling element. Further, the other raceway ring has a groove on the rolling element side with respect to the sliding contact portion with the seal body or with respect to the sliding contact portion. Further, in the other race ring, a hard coating is formed at a sliding contact portion with the seal body.

  The raceway, the rolling element, and the cage are made of stainless steel, and at least one member selected from the raceway, the rolling element, and the cage has a solid lubricant film on the contact surface with the other member. It is formed.

  The sealed bearing is used in at least one temperature region selected from −100 ° C. or lower and 250 ° C. or higher, and is used under conditions where oil lubrication is not performed.

  The sealed bearing of the present invention uses a contact seal formed of a meta-type wholly aromatic polyamide fiber as a seal body that is disposed at both axial openings in a pair of bearing rings and seals the bearing inner space. It is a lightweight and compact sealed bearing that can be used even under high temperature conditions or in a wide operating temperature range.

  In particular, when the seal body is in sliding contact with the other race ring while being elastically deformed, and the diameter of the sliding contact portion position with the seal body in the other race ring is A (mm), the diameter of the seal body Since the amount of elastic deformation in the direction is set to A / 100 (mm) or more, the amount of elastic deformation at the sliding contact portion is set to be large, and the temperature is extremely low from −100 ° C. or lower to 250 ° C. or higher, or the temperature changes greatly. High sealing performance can be maintained even in the environment.

It is an axial sectional view showing an example of the sealed bearing of the present invention. It is an axial sectional view which shows the other example (step part) of the sealed bearing of this invention. It is an axial sectional view and an enlarged view showing another example (inclined part) of the sealed bearing of the present invention. It is an axial sectional view showing another example (trap groove) of the sealed bearing of the present invention.

  The sealed bearing of the present invention is a rolling bearing mainly used in a dust environment, and includes a sealing body to prevent dust from entering the inside of the bearing. This seal body also serves as a seal that suppresses leakage of these lubricants to the outside of the bearing when the bearing is used with oil or grease lubrication depending on the use conditions.

  The sealed bearing of the present invention is characterized in that the seal body of the rolling bearing is formed from a meta-type wholly aromatic polyamide fiber (meta-type aramid fiber). The meta-type wholly aromatic polyamide resin is a resin having a repeating unit as shown in the following formula. This resin is obtained, for example, by co-condensation polymerization of m-phenylenediamine and isophthalic acid chloride. In the present invention, a sealing body is formed from a meta-aramid fiber obtained by fiberizing this resin. Aramid fibers have a meta type and a para type due to the difference in their molecular skeletons. The para type is more rigid and high-strength compared to the meta type, and is a material for a sealing body that makes elastic contact with the raceway. It is not preferable. Examples of the meta-type aramid fiber that can be used in the present invention include Nomex (registered trademark) manufactured by DuPont Toray Kevlar and Conex (registered trademark) manufactured by Teijin.

  The sealing body in this invention should just be formed from the meta-type wholly aromatic polyamide fiber. That is, it may be a structure formed using a meta-type wholly aromatic polyamide fiber as a main material. Specifically, woven fabrics, non-woven fabrics or knitted fabrics with processed fibers, sheet materials in which the fiber direction is aligned in one direction and impregnated with a thermosetting resin such as epoxy resin or phenol resin, meta type wholly aromatic polyamide resin ( Examples thereof include a paper material obtained by producing a short fiber and a synthetic pulp from a polymer and dispersing the same in water and using a paper machine. Among these, it is preferable to use a woven fabric, a non-woven fabric, or a knitted fabric because it is excellent in sealing performance due to elastic contact, work surface, and the like.

  When pursuing weight reduction, cost reduction, etc., a nonwoven fabric sealing body is preferable. In order to increase the dustproof performance of the nonwoven fabric, the fiber diameter should be reduced and the density increased. Further, a woven fabric or a knitted fabric having an elastic knitting structure may be applied in view of the effect of preventing the fibers from falling off and the high rigidity of the sealing body.

  In order to improve the lubricity, the sliding contact portion may be impregnated with a lubricious resin having excellent heat resistance and lubricity depending on use conditions. However, when the temperature change is large, pay attention to the linear expansion coefficient of the resin. Partial impregnation may be performed. In addition, reinforcing fibers such as high-strength metal fibers may be knitted in a range that does not interfere with the sliding contact portion in order to reinforce the sealing body.

  Meta-type wholly aromatic polyamide fiber is chemically stable from the above structure, does not lose its fiber property even at extremely low temperatures such as -196 ° C, and can be used as a fiber up to a high melting point and decomposition point of 400 ° C or higher. In addition, since the glass transition point is in the vicinity of 270 ° C., the dimensional change of the fiber is very stable up to about 250 ° C. Therefore, when the meta-type wholly aromatic polyamide fiber is used as the seal body, the use temperature can be extended to a very low temperature or a high temperature. In general, if the fiber is a woven fabric or a knitted fabric, an increase in strength and prevention of fiber dropping can be expected. However, since the fibers are oriented, a dimensional change becomes remarkable. However, in the case of the meta-type wholly aromatic polyamide used in the present invention, the entire woven fabric against the temperature change even in the state where the fibers are regularly oriented as a woven fabric or a knitted fabric because of the high dimensional stability of the fiber itself. The dimensional change of becomes smaller.

  An example of the sealed bearing of the present invention will be described with reference to FIG. FIG. 1 is an axial cross-sectional view of a radial rolling bearing (deep groove ball bearing) using the above-described seal body. As shown in FIG. 1, the sealed bearing 1 includes an inner ring 2 having an inner ring rolling surface on an outer diameter surface and an outer ring 3 having an outer ring rolling surface on an inner diameter surface, which are arranged concentrically. It has a structure in which a plurality of rolling elements 4 are arranged between the running surface. The rolling elements 4 are held at equal intervals in the circumferential direction by a cage 5. The seal body 6 is a hollow disk-like structure disposed at both axial opening portions of the inner and outer rings which are track rings, and one end portion in the radial direction is fixed to the outer ring 3 and the other end portion in the radial direction. While sliding in contact with the outer diameter portion 8 of the inner ring 2, the bearing inner space is sealed. The seal body 6 is in elastic contact with the outer diameter portion 8 of the inner ring 2 (the seal body is in contact with the outer diameter portion of the inner ring while being elastically deformed).

  The seal body 6 is inserted into an annular groove 3 a provided on the inner diameter surface of the outer ring 3. A retaining ring 7 for fixing the seal body is further inserted into the annular groove 3 a, and the seal body 6 is fixed to the outer ring 3. The inner diameter of the seal body 6 is smaller than the diameter of the sliding contact portion position of the inner ring 2 with the seal body 6 (the diameter of the outer diameter part 8), and the operating temperature is maintained so as to keep the elastic contact with the outer diameter part of the inner ring 2. In contrast to the gap where the bearing internal gap becomes the maximum within the range, the gap is not generated when the radial relative displacement of the raceway is maximized, and the gap is changed when the diameter of the sliding contact portion changes due to temperature change. The value of the inner diameter is set so that it is not possible.

  The amount of elastic deformation of the seal body 6 differs from the generated stress depending on the density of the fiber, and may have a balance with torque. However, when the diameter of the outer diameter portion 8 of the inner ring 2 is A (mm), A / 100 If an elastic deformation amount of (mm) or more is provided in advance, the seal can be reliably maintained without generating a gap with respect to a change in the dimensions of the race.

  As a standard of the inner diameter of the seal body 6 in consideration of the elastic deformation amount, when the diameter of the outer diameter portion 8 of the inner ring 2 is A (mm), it is preferable to be (A−2 × A / 100) mm or less. Since the sealing body made of fibers generates less stress due to elastic contact, it is possible to set a sufficiently large amount of elastic contact against changes in the diameter of the sliding contact portion and differences in the bearing internal gap due to differences in operating temperature. Therefore, it can be used universally without changing the inner diameter of the seal body for each operating temperature of the bearing.

  Another example of the sealed bearing of the present invention will be described with reference to FIG. FIG. 2 is an axial cross-sectional view of a radial rolling bearing (deep groove ball bearing) using the above-described seal body. The sealed bearing 1 shown in FIG. 2 has the same configuration as that shown in FIG. 1 except that a step portion 9 is provided on the outer diameter surface of the inner ring 2. The step portion 9 is a sliding contact portion with the seal body 6. In the case of this form, the elastic deformation amount of the seal body 6 can be set similarly to the case shown in FIG. 1 with the diameter A ′ of the step portion 9 of the inner ring 2 as a reference. Here, the outer diameter surface of the inner ring 2 between the seal body 6 and the rolling element 4 is a peripheral surface having a diameter larger than the diameter (outer diameter) of the stepped portion 9. Accordingly, even if dust or dropped fibers enter the bearing from the sliding contact portion, it is possible to prevent these foreign substances from entering the contact portion between the rolling element and the raceway surface.

  Another example of the sealed bearing of the present invention will be described with reference to FIG. FIG. 3A is an axial sectional view of a radial rolling bearing (deep groove ball bearing) using the above-described seal body, and FIG. 3B is a partially enlarged view of FIG. The sealed bearing 1 shown in FIG. 3 has the same configuration as that shown in FIG. 1 except that the inclined portion 10 is provided on the outer diameter surface of the inner ring 2. The inclined portion 10 is a sliding contact portion with the seal body 6. The seal body 6 is inserted into an annular groove 3 a provided on the inner diameter surface of the outer ring 3 together with a retaining ring 7 for fixing the seal body, and is fixed to the outer ring 3. In the case of this form, the elastic deformation amount of the seal body is the same as the diameter B of the seal ring 6 fixed position and the diameter C of the sliding contact portion in the inner ring 2, and the sliding contact portion diameter A and the sealing body inner diameter in the case shown in FIG. Can be set similarly to the case shown in FIG.

  Here, the fixing position 10b of the seal body 6 is set to the bearing center side in the axial direction with respect to the contact point 10a with the seal body 6 on the side surface of the inclined portion 10 provided on both sides of the inner ring. Hold the seal. The amount of axial deflection of the seal body 6 is such that there is no gap when the relative displacement in the axial direction and radial direction of the bearing ring is maximum with respect to the gap where the bearing internal clearance is maximum within the operating temperature range. The gap is set so that there is no gap even when the diameter of the sliding contact portion changes due to temperature change.

  As a guide for the fixed position 10b of the seal body 6, assuming that the inner ring outer diameter B (mm) at the fixed position 10b and the diameter C (mm) at the sliding contact 10a, (BC)> (2 × B / 100 ) Mm. Since the fiber seal body generates less stress due to deflection, it is possible to set a sufficiently large deflection amount against the change in the diameter of the sliding contact portion and the change in the bearing internal clearance due to differences in operating temperature. Therefore, it can be used for a general purpose without changing the fixing position of the sealing body for each operating temperature of the bearing.

  Another example of the sealed bearing of the present invention will be described with reference to FIG. FIG. 4 is an axial cross-sectional view of a radial rolling bearing (deep groove ball bearing) using the above-described seal body. The sealed bearing 1 shown in FIG. 4 has the same configuration as that shown in FIG. 1 except that the groove 11 is provided on the outer diameter surface of the inner ring 2. The groove 11 is a groove that traps (captures) these foreign matters so as not to enter the inside of the bearing when dust or dropped fibers enter the sliding contact surface. This groove can be provided in the sliding contact portion with the seal body 6 or on the rolling element 4 side from the sliding contact portion.

  The sliding contact portions (the outer diameter portion 8 in FIG. 1, the step portion 9 in FIG. 2, the inclined portion 10 in FIG. 3, etc.) of the inner ring 2 are worn when dust enters the sliding contact surface. In order to prevent this, a hard film having a hardness higher than that of dust that is supposed to enter may be formed. In particular, in the case of extremely low temperature or high vacuum to which oil cannot be applied, the risk of wear at the sliding contact portion increases, so that the reliability is improved by applying a hard coating. The hard coating may be a single layer or a laminate of diamond like carbon (DLC), titanium nitride (TiN), chromium nitride (CrN), chromium nitride silicon (CrSiN), titanium aluminum nitride (TiAlN), titanium silicon nitride (TiSiN), etc. A film is mentioned. Furthermore, plating such as chrome plating, nickel plating, and zinc plating may be applied as the base of the hard coating.

As materials for bearing members (bearing rings, cages, rolling elements, retaining rings) other than the seal body in the sealed bearing, steel materials and ceramics generally used as bearing materials can be used without limitation. Steel materials include high carbon chromium bearing steel (SUJ1, SUJ2, SUJ3, SUJ4, SUJ5, etc .; JIS G 4805), carburized steel (SCr420, SCM420, etc .; JIS G 4053), stainless steel (SUS440C, etc .; JIS G 4303), High speed steel (M50 etc.), cold rolled steel, etc. are mentioned. Examples of the ceramic include silicon nitride (Si ₃ N ₄ ), silicon carbide (SIC), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), and sialon.

  When oil cannot be used due to extremely low temperature or high vacuum, stainless steel such as SUS440C is used as a material for the race ring, rolling element, and cage, and at least one member selected from these members is another member. It is preferable to form a solid lubricating film on the contact surface. The solid lubricant film can be formed by surface treatment such as sputtering using molybdenum disulfide, tungsten disulfide, graphite or the like as a material.

  In each of the above drawings, the deep groove ball bearing has been described as an example of the sealed bearing of the present invention, but the present invention is not limited to this. That is, the present invention can be applied to all types of bearings such as angular ball bearings, cylindrical roller bearings, tapered roller bearings, etc. by changing the shape and fixing method according to the allowable space, and the bearing type is not limited. . Moreover, it does not depend on rotation division, and is not limited to inner ring rotation or outer ring rotation.

  The sealed bearing of the present invention can realize a light, compact and high sealing performance even in an environment of -100 ° C. or lower, an environment of 250 ° C. or higher, or an environment with a large temperature change. Therefore, it can be suitably used as a sealed bearing used in a space dust environment where oil lubrication cannot be used.

1 Sealed bearing (rolling bearing)
2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6 Seal body 7 Retaining ring 8 Outer diameter part 9 Step part 10 Inclined part 11 Groove

Claims (9)

A pair of race rings, a plurality of rolling elements interposed between the race rings, a retainer for holding the rolling elements, and a seal body that is disposed in an opening between the pair of race rings and seals a bearing internal space A sealed bearing comprising:
The seal body is formed of a meta-type wholly aromatic polyamide fiber, one end of the seal body is fixed to one of the race rings, and the other end of the seal body is in sliding contact with the other of the race rings, A sealed bearing, wherein the bearing inner space is sealed. The seal body is in sliding contact with the other race ring while being elastically deformed,
The amount of elastic deformation in the radial direction of the seal body is not less than A / 100 (mm), where A (mm) is the diameter of the sliding contact portion position of the other race ring with the seal body. The sealed bearing according to claim 1.   The sealed bearing according to claim 1, wherein the seal body is a woven fabric, a nonwoven fabric, or a knitted fabric of the meta-type wholly aromatic polyamide fiber.   The seal body is at least selected from a structure in which a sliding contact portion with the other raceway is impregnated with a lubricating resin, and a structure in which reinforcing fibers are knitted into at least a part other than the sliding contact portion. 4. The sealed bearing according to claim 1, wherein the sealed bearing has one.   The other raceway ring has a peripheral surface larger in diameter than a diameter of a sliding contact portion with the seal body between the seal body and the rolling element. The sealed bearing according to any one of 4 to 4.   The said other track ring has a groove | channel on the said rolling element side rather than this sliding contact part or this sliding contact part, The any one of Claim 1-5 characterized by the above-mentioned. Sealed bearing.   The sealed bearing according to any one of claims 1 to 6, wherein a hard coating is formed on a sliding contact portion with the seal body in the other raceway ring. The race, the rolling element, and the cage are made of stainless steel,
The solid lubricant film is formed on the contact surface with the other member in at least one member selected from the raceway, the rolling element, and the cage. The sealed bearing according to any one of claims.   9. The sealed bearing is used in at least one temperature range selected from −100 ° C. or lower and 250 ° C. or higher, and is used under conditions where oil lubrication is not performed. The sealed bearing according to any one of the above.

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