JP2006300261A - Ball bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a torque increase and heating during high speed rotation by preventing the deformation of a synthetic resin cage due to centrifugal force during high speed rotation to suppress temperature rise due to interference between a pocket face and a ball and between the cage and a seal member and suppress the movement of the cage and noises of collision with the ball and to make extra grease contributive to lubrication. <P>SOLUTION: This ball bearing comprises the cage 4 consisting of two resin molded annular bodies 11. The annular bodies 11 in wavy shape are combined to form the pocket which holds the ball 3 between pocket faces 12a, and their joint plate portions 13 are connected to each other. In the inner periphery of an outer ring 2 apart from a seal groove 8, a grease sump is provided ranging from a raceway surface 7, which is formed with a recessed portion 9 ranging to the peripheral direction. A depth A of the recessed portion 9 in the radial direction is 2-10% of a diameter B of the ball 3, and a width C from a side face 2a of the outer ring 2 to the edge of the recessed portion 9 is 1.2-1.8 times a width D of the seal groove 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ball bearing in which a plurality of balls assembled between an outer ring and an inner ring are held by a cage made of a synthetic resin.

  In general, an apparatus that performs high-speed rotation is required to have high rotation accuracy, high rigidity, low vibration, quietness, long life, and the like.

  Therefore, high-strength and self-lubricating brass machined cages and surface-treated steel plate cages have been applied to high-speed rotation bearings. Further, in a bearing incorporated in a motor used for high-speed rotation, a large centrifugal force acts on a cage that holds a ball, and therefore, a corrugated cage made of a steel plate is usually adopted.

  By the way, although the steel plate corrugated cage is inexpensive, a relatively large collision sound (cage sound) may be generated due to the collision between the ball and the cage.

  In addition, grease deterioration cannot be avoided due to the generation of metal wear powder due to sliding between the metal cage and the ball.

  Therefore, in recent years, a cage made of a synthetic resin having a self-lubricating property that is lighter than brass and easy to manufacture has been adopted. Synthetic resin cages, like metal cages, generate wear powder due to sliding with the ball, but since they are resin components, they have little effect on grease.

  As the synthetic resin cage, those shown in FIGS. 8 (I) and (II) are known. The retainer shown in FIG. 8I is called a crown-shaped retainer, and a pair of opposing claws 31 are provided on one side surface of the retainer body 30 at equal intervals in the circumferential direction, and a pocket 32 is provided between the opposing pair of claws 31. Is forming.

  The retainer shown in FIG. 8 (II) has the same configuration as the retainer shown in FIG. 8 (I) and has a groove-like grease reservoir extending in the radial direction of the retainer at a position opposed to the inner periphery of the pocket 32. 34 is formed.

  By the way, in the crown-shaped cage shown in FIGS. 8 (I) and (II), in a high-speed rotation region where the dn value represented by the product of the bearing inner diameter and the rotation speed (bearing inner diameter × rotation speed) exceeds 350,000, The claw 31 is deformed to the outer diameter side due to centrifugal force, and the inner surface of the pocket 32 comes into strong contact with the ball 34 or interferes with a seal member that prevents leakage of grease from the bearing, thereby causing friction at the contact portion. There is a problem that the temperature of the bearing suddenly rises due to heat generation due to heat, and the rotational resistance increases.

  Further, since the ball 35 is assembled from the opening 32 a of the pocket 32, the opening 32 a needs to be about 80% or more of the spherical diameter of the ball 35. For this reason, it is difficult to manage the amount of movement of the cage in the axial direction to a small value, the amount of movement of the cage in the axial direction is relatively large, and a relatively loud collision sound (holding) at the time of collision with the ball 35 There is also a problem of generating instrumental sound.

  Here, as shown in FIG. 8 (II), if the grease reservoir 34 is provided on the inner surface of the pocket 32, the grease can be held in the grease reservoir 34. Therefore, the contact portion between the ball 35 and the inner surface of the pocket 32 is formed. Although the lubrication can be satisfactorily lubricated, the grease reservoir 34 becomes an undercut at the time of mold release after molding of the cage, and considering the deformation of the claw 31, the limit is about 0.2 mm, which is deep. The grease reservoir 34 cannot be formed, and the amount of grease retained is limited.

  For components other than cages, it is possible to reduce the temperature rise of the bearing by reducing the ball diameter or decreasing the number, but since the basic load rating and rigidity of the bearing are reduced, all the required items I couldn't be satisfied.

  Further, when rotating at high speed, the grease enclosed in the vicinity of the ball is driven to the vicinity of the seal member by the rotation and revolution of the ball, but these are surplus grease that does not contribute to lubrication. To increase the life of the bearing, it is necessary to increase the amount of grease that contributes to lubrication. However, if a large amount of grease is filled, problems such as increased rotational torque, large heat generation, and grease leakage to the outside of the bearing was there.

  An object of the present invention is to prevent a plastic resin cage from being deformed by a centrifugal force during high-speed rotation, and to suppress a temperature rise due to interference between a pocket surface and a ball, and a cage and a seal member. In addition to reducing the amount of movement of the cage, suppressing the impact sound with the ball, the excess grease driven to the position of the seal member by the rotation and revolution of the ball is made into grease that contributes to lubrication as much as possible, and high speed The object is to provide a ball bearing which prevents the problems of large torque during rotation and heat generation.

  In order to solve the above problems, a plurality of balls and a cage for holding the balls are incorporated between the outer ring and the inner ring, a seal member is provided between the inner periphery of the outer ring and the outer periphery of the inner ring, and grease is applied. In the enclosed ball bearing, the cage is composed of two resin-molded annular bodies, each annular body having an arcuate pocket wall portion having a hemispherical pocket surface on the inner periphery, and the pocket wall portion. Combining plate portions extending in the circumferential direction from the end portion are corrugated alternately, and the corrugated annular body is combined to form a pocket for holding a ball between the pocket surfaces. Connected to each other, a grease reservoir formed by a concave portion continuous in the circumferential direction is provided on the inner periphery of the outer ring at a position away from the seal groove, and the radial depth of the concave portion is set. 2-10% of the diameter of the ball The width of the side surface of the outer ring to the edge of the recess, and a 1.2 to 1.8 times the width of the seal groove.

This deep groove ball bearing becomes more preferable when the following configuration is added.
1) The grease is a grease in which the base oil is ester oil and the thickener is a lithium-based grease, or the base oil is a mixed oil of polyalphaolein oil and ester oil, and the thickener is a diurea-based grease.
2) The amount of the grease enclosed is 50 to 100% with respect to the volume of the static space.
3) The ball is made of ceramic.
4) The bearing accuracy shall be JIS grade 5 or higher.

  In the present invention, the stationary space refers to a space obtained by removing a space through which the ball and the cage pass from a space surrounded by the inner ring, the outer ring, and the seal member.

  By making the two resin-molded annular bodies into a waveform in which the arcuate pocket wall portions and the coupling plate portions are alternately continuous in the circumferential direction, a strong annular body can be obtained. By coupling at the coupling plate portion, a highly rigid cage can be obtained.

  For this reason, even if the bearing is rotated at a high speed, the cage is not deformed by centrifugal force, and the pocket surface is in strong contact with the ball, or the cage is in contact with the sealing member that prevents grease leakage in the bearing. It is possible to prevent the temperature rise of the bearing due to heat generation at the contact portion.

  In addition, the contact pressure between the pocket surface of the cage and the ball is almost constant, and the cage does not interfere with the sealing member, so that the rotational resistance of the bearing does not increase, and the outer ring and the inner ring are always smoothly connected. Relative rotation is possible.

  As described above, in the present invention, the cage that holds the plurality of balls assembled between the outer ring and the inner ring is formed of two resin-molded corrugated annular bodies, thereby obtaining a very rigid cage. Therefore, when the bearing rotates at high speed, the cage is not deformed by centrifugal force and the pocket surface does not come into strong contact with the ball, or the cage does not come into contact with the seal member. A ball bearing with low resistance can be obtained.

  Further, the grease pushed out from the raceway surface by the balls accumulates in the concave portion connected to the raceway surface, and the grease accumulated in the concave portion is continuously supplied to the rolling portion. For this reason, this ball bearing is excellent in lubricity even in a high-speed rotation region, and hardly causes increase in rotational torque and temperature.

  FIG. 1 shows an embodiment of the deep groove ball bearing of the present invention. This deep groove ball bearing includes an inner ring 1, an outer ring 2, a ball 3 between the inner ring 1 and the outer ring 2, a cage 4 that holds the ball 3, and a seal that holds grease between the inner ring 1 and the outer ring 2. It consists of member 5.

  On the outer periphery of the inner ring 1 and the inner periphery of the outer ring 2, raceway surfaces 6 and 7 having an arcuate cross section are formed continuously in the circumferential direction, and the ball 3 rolls on the inner surfaces of the raceway surfaces 6 and 7. . Further, a seal groove 8 connected to the side surface 2 a of the outer ring 2 is continuously formed in the circumferential direction on the inner periphery of the outer ring 2, and a ring-shaped seal member 5 is incorporated in the seal groove 8. Grease is enclosed in a space surrounded by the seal member 5, the inner ring 1 and the outer ring 2.

  On the inner periphery of the outer ring 2, a recess 9 that is continuous in the circumferential direction is formed at a position away from the seal groove 8. The recess 9 is continuous with the raceway surface 7 and is pushed out of the raceway surface 7 by the balls 3 rolling on the raceway surface 7 or receives the centrifugal force generated by the revolution of the balls 3 and the cage 4 in the direction of the outer ring 2. The moved grease is stored.

  When this deep groove ball bearing is used, the grease pushed out from the raceway surface 7 by the balls 3 is accumulated in the concave portion 9, and the grease accumulated in the concave portion 9 is continuously supplied to the rolling portion. For this reason, this deep groove ball bearing is excellent in lubricity even in a high-speed rotation region, and hardly causes an increase in rotational torque and a temperature.

  The depth A in the radial direction of the recess 9 shown in FIG. 2 is preferably set to 2 to 10% of the diameter B of the ball 3. When the depth A of the recess 9 is 2% or more of the diameter B of the ball 3, the amount of grease in the recess 9 can be increased. That is, it is possible to increase the grease that can contribute to lubrication, prevent an increase in torque and high heat generation at high speed rotation, and ensure a long life of the bearing. If the depth A of the recess 9 is 10% or more of the diameter B of the ball 3, the allowable axial load may be reduced, so that it is 10% or less.

  The width C from the side surface 2 a of the outer ring 2 shown in FIG. 2 to the edge of the recess 9 is preferably set to 1.2 to 1.8 times the width D of the seal groove 8. When the width C from the side surface 2a of the outer ring 2 to the edge of the recess 9 is 1.2 times or more the width D of the seal groove 8, the thickness of the wall 10 formed between the seal groove 8 and the recess 9 is increased. Thus, it is possible to prevent the wall 10 from being cracked or chipped. If it is 1.8 times or less, the width of the recess 9 is widened to ensure the amount of grease accumulated in the recess 9, preventing problems such as increased torque and large heat generation during high-speed rotation of the bearing, and ensuring a long life. be able to.

  As shown in FIGS. 3 and 4, the retainer 4 includes two annular bodies 11 and 11. Each annular body 11 has a corrugated shape in which arc-shaped pocket wall portions 12 and coupling plate portions 13 extending in the circumferential direction from the end portions of the pocket wall portions 12 are alternately formed in the circumferential direction. Consists of.

  Synthetic resins include polyamide (PA66, PA46, etc.), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyimide (PI) and other engineering plastic single materials, or glass fibers, carbon fibers and other short fibers. Thus, a reinforced composite material can be used.

  A hemispherical pocket surface 12a along the outer periphery of the ball 3 is formed on the inner periphery of the pocket wall portion 12, and arcuate surfaces 12b are provided at both ends of the pocket surface 12a.

  Here, when connecting the two annular bodies 11, 11, a pin hole 14 is formed in the coupling plate portion 13 that abuts each other, and the tip of the rivet 15 inserted into the pin hole 14 is caulked. .

  As described above, the two synthetic resin annular bodies 11 forming the cage 4 are strong in strength by making the arcuate pocket wall portions 12 and the coupling plate portions 13 alternately continuous in the circumferential direction. An annular body 11 can be obtained. For this reason, by combining and integrating the two annular bodies 11, the highly rigid cage 4 can be formed, and the cage 4 is not deformed by centrifugal force even if the bearing rotates at a high speed.

  Therefore, when the bearing rotates at high speed, the pocket surface 12a does not come into strong contact with the ball 3 or the cage 4 does not interfere with the seal member 5, and heat generation due to friction at the contact portion is prevented, and the temperature of the bearing is prevented. The rise can be suppressed. Further, the rotational resistance of the bearing does not increase, and the outer ring 1 and the inner ring 2 can be rotated relatively smoothly.

  Hereinafter, other embodiments relating to the cage 4 incorporated in the ball bearing of the present invention will be described with reference to FIGS. The cage 4 is composed of two annular bodies 16 and 16, and each annular body 16 is formed of synthetic resin and has the same shape.

  As shown in FIG. 5, the annular body 16 has a corrugated planar shape, and hemispherical pockets 17 along the outer periphery of the ball 3 are provided at equal intervals in the circumferential direction on one side surface thereof.

  Further, the annular body 16 is inserted into an engagement hole 19 penetrating both side surfaces of a coupling portion 18 formed between adjacent pockets 17 and the engagement hole 19 formed in the other annular body 16. An engaging claw 20 is formed.

  An engagement step portion 19 a is formed on the inner periphery of the engagement hole 19, while a hook portion 20 a that is engaged with the engagement step portion 19 a is provided at the distal end portion of the engagement claw 20.

  A flat surface 21 is formed on the other side of the coupling portion 18.

  The two annular bodies 16, 16 are combined so that the hemispherical pockets 17 face each other, and are joined and integrated by engagement of the engagement claws 20 with the engagement holes 19, and the cage 4 shown in FIG. 7 is assembled.

  Here, the cage 4 is assembled by incorporating a plurality of balls 3 between the outer ring 2 and the inner ring 1 and then two annular bodies 16, 16 in an annular space formed between both wheels from both sides of the two rings. And the engaging claw 20 is inserted into the engaging hole 19.

  Thus, since the retainer 4 can be assembled by the engagement of the engagement claw 20 with the engagement hole 19, the assembly is easy, and the annular body 16 is engaged by the engagement of the engagement hole 19 and the engagement claw 20. Therefore, the cage 4 having high rigidity can be obtained and can be used for high-speed rotation.

  Moreover, since the two annular bodies 16 forming the cage 4 have the same shape, the cage 4 can be molded with one type of molding die, and the cage 4 can be obtained at a low cost. Management of 16 is also easy.

  As shown in this embodiment, the engagement claw 20 has a dimensional relationship in which the tip 20b does not make a business trip from the flat surface 21 of the coupling portion 18, so that when the cage 4 is assembled, The cage 4 can be easily assembled by receiving the flat surface 21 and pushing the flat surface 21 of the other annular body 16.

  As grease to be sealed in the bearing, grease with base oil as ester oil and thickener as lithium, or base oil as mixed oil of polyalphaolein oil (PAO) and ester oil, and grease as thickener as diurea It is preferable to use it. When this grease is used, since the lubricating performance is not easily deteriorated even at a high temperature in the high-speed rotation region, the bearing has a longer life.

  The amount of grease filled is preferably 50 to 100% with respect to the volume of the static space. Here, the stationary space refers to a space obtained by removing the space through which the ball 3 and the cage 4 pass during rotation of the bearing from the space surrounded by the inner ring 1, the outer ring 2, and the seal member 5. Leakage of grease in the high-speed rotation range can be prevented by setting the amount of grease filled to 100% or less with respect to the volume of the static space. By setting it to 50% or more, the rolling part can be reliably secured even in the high-speed rotation range. Can be lubricated.

  The ball 3 is preferably made of ceramic. When ceramic is used, the ball 3 becomes lighter than when bearing steel is used as the material, and thus the centrifugal force acting on the ball 3 is reduced, and the temperature rise of the bearing due to friction can be suppressed. Of course, the material of the ball 3 may be bearing steel.

  This deep groove ball bearing has a precision of JIS grade 5 or higher, thereby improving the rotational runout accuracy and ensuring good balance during high-speed rotation. Further, by setting the radial internal clearance to JIS CM to C4, it is possible to prevent seizure due to a decrease in the radial internal clearance even if the inner ring expands due to a temperature rise or centrifugal force in a high-speed rotation range. Furthermore, if the material of the inner ring 1 and the outer ring 2 is a high-temperature and long-life bearing steel, the bearing life can be extended more reliably.

  High-temperature long-life bearing steel is a steel material containing Si or Al and having an oxygen content of 13 ppm or less, and then tempered at a high temperature of 230 ° C. to 300 ° C. What has dimensional stability is mentioned.

Sectional drawing which shows embodiment of the ball bearing of this invention Sectional drawing explaining the recessed part of the ball bearing of FIG. The top view which shows the holder | retainer integrated in the ball bearing of FIG. FIG. 3 is an enlarged sectional view of the cage of FIG. Sectional drawing explaining the modification of the holder | retainer of FIG. FIG. 5 is a perspective view of the cage shown in FIG. Sectional view of the cage shown in FIG. (I), (II) are cross-sectional views showing a cage assembled in a conventional ball bearing

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 2a Side surface 3 Ball 4 Cage 5 Seal member 6, 7 Track surface 8 Seal groove 9 Recess 11 Annular body 12 Pocket wall part 12a Pocket surface 13 Connection plate part A Depth of recess B Diameter of ball C Diameter of outer ring Width D from side to edge of recess D Width of seal groove

Claims (6)

  In a ball bearing in which a plurality of balls and a cage for holding the balls are incorporated between the outer ring and the inner ring, a seal member is provided between the inner circumference of the outer ring and the outer circumference of the inner ring, and grease is sealed, the cage Is composed of two resin-molded annular bodies, each annular body having an arcuate pocket wall portion having a hemispherical pocket surface on the inner periphery, and a coupling plate extending in the circumferential direction from the end of the pocket wall portion And the corrugated annular body is combined to form a pocket for holding a ball between the pocket surfaces, and the coupling plate portions are connected to each other to seal the outer ring. A grease reservoir formed by a recess that is continuous in the circumferential direction is provided on the inner circumference at a position away from the groove, and the depth of the recess in the radial direction is 2 to 10% of the diameter of the ball. And the edge of the recess from the side of the outer ring Ball bearing widths, characterized in that was 1.2 to 1.8 times the width of the seal groove at.   The ball bearing according to claim 1, wherein the grease is a grease in which the base oil is ester oil and the thickener is lithium.   2. The ball bearing according to claim 1, wherein the grease is a grease in which the base oil is a mixed oil of polyalphaolein oil and ester oil, and the thickener is diurea.   The ball bearing according to any one of claims 1 to 3, wherein an amount of the grease enclosed is 50 to 100% with respect to a volume of the static space.   The ball bearing according to claim 1, wherein a material of the ball is ceramic.   The ball bearing according to any one of claims 1 to 5, wherein the accuracy of the bearing is JIS grade 5 or higher.

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