JP7186061B2 - ball bearing - Google Patents

Description

The present invention relates to a ball bearing incorporating an outer ring guide type retainer.

2. Description of the Related Art In a ball bearing provided with a retainer for rollingly holding balls as rolling elements, any one of inner ring guide, rolling element guide and outer ring guide is adopted as the guide type of the retainer. Of these, the outer ring guide type is considered suitable for ball bearings operated at high speeds. Insufficient lubricant between the outer peripheral surface of the retainer on which force acts and the inner peripheral surface of the outer ring, which is the guide surface, may cause the oil film to run out. Especially in the case of grease-lubricated bearings, fresh lubricant is not always supplied unlike oil-lubricated bearings. It is difficult to remain on the surface, and it is easy to cause the oil film to run out.

In addition, ball bearings incorporating an outer ring guide cage may whirling during operation by the amount of the guide gap between the outer circumference of the cage and the inner circumference of the outer ring, especially when the ball diameter is large. In this case, since the centrifugal force and inertial force of the cage itself also increase, the cage may not be able to keep up with the high-speed rotation range, and the vibration may suddenly increase.

By the way, in Patent Document 1, in a rolling bearing operated at high speed, in order to prevent the seizure of the rolling elements and the inner and outer rings in a short time when a lubricating device that supplies lubricating oil to the bearing fails. It has been proposed to form recesses in the side of the cage that holds the rolling elements on the side facing the inner ring, and to circulate the lubricating oil collected in the recesses between the raceway grooves of the inner and outer rings.

Japanese Utility Model Laid-Open No. 1-174629 (Fig. 3)

Even in a ball bearing incorporating an outer ring guide retainer, if recesses are formed on the side of the column of the retainer facing the inner ring as proposed in Patent Document 1, part of the lubricant collected in the recesses can be eliminated. It is thought that the portion enters between the outer peripheral surface of the cage and the inner peripheral surface of the outer ring, and acts in the direction of suppressing the occurrence of oil film breakage between the cage and the outer ring.

However, since the recesses of the cage of Patent Document 1 are only large enough that the bottoms do not reach the pitch circle of the balls, it is difficult to leave sufficient lubricant between the outer peripheral surface of the cage and the inner peripheral surface of the outer ring. Therefore, the effect of suppressing the occurrence of oil film breakage between the retainer and the outer ring may be limited.

Moreover, Patent Document 1 does not describe the influence of the recesses on the behavior of the retainer, and the problem of vibration caused by the instability of the behavior of the retainer in the high-speed rotation region is not solved.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a ball bearing incorporating an outer ring guide retainer to reliably suppress the occurrence of oil film breakage between the retainer and the outer ring, and to make it difficult for vibrations to occur in a high-speed rotation range. .

In order to solve the above problems, the present invention provides an outer ring having raceway grooves formed on its inner peripheral surface, an inner ring having raceway grooves formed on its outer peripheral surface, and a gap between the raceway grooves of the outer ring and the raceway grooves of the inner ring. and an outer ring guide type retainer that retains the balls in a rollable manner. The retainer includes annular portions disposed on both sides in the axial direction, A ball that has a plurality of pillars that are axially connected and arranged at predetermined intervals in the circumferential direction, and holds the balls in pockets formed between the pillars that are adjacent in the circumferential direction. In the bearing, at least a portion of the column portion of the retainer has a concave portion formed on a side facing the inner ring, and a peripheral edge portion of the concave portion contacts the ball radially outside the pitch circle of the ball. It was adopted.

According to the above configuration, at least a portion of the column portion of the retainer is formed with a recess extending to a position radially outside the pitch circle of the ball on the side facing the inner ring, and a large amount of lubricant is supplied to the recess. This makes it easy to supply lubricant between the outer peripheral surface of the cage and the inner peripheral surface of the outer ring. Since the cage rotates in a state where it is always pushed toward the inner peripheral surface of the outer ring, which is the guide surface, by the force received from the balls, the behavior of the cage is stable even in the high-speed rotation range, and vibration is less likely to occur. Become.

Here, at least a portion of the pillars of the retainer specifically has a flat or curved bottom of the recess, and contacts the ball at one location where the bottom of the recess is formed. can be

Further, in order to secure the strength of the retainer, it is desirable that the width dimension of the concave portion of the column portion is equal to or less than the width dimension of the pocket in the axial cross section of the retainer.

Furthermore, at least a part of the pillars of the retainer may have recesses formed not only on the side facing the inner ring but also on the side facing the outer ring. With this configuration, more lubricant can be retained, so the lubricant can be more stably supplied between the outer peripheral surface of the cage and the inner peripheral surface of the outer ring. Oil film breakage can be made more difficult to occur. However, in this case, since the radial thickness of the column portion of the cage is reduced, the thickness is t1, the load received by the balls is Q, the coefficient of friction between the balls and the outer ring is μ, and the cage is When the permissible shear strength of the material is σt and the thickness of the column in the circumferential direction is t2, the cage must be designed to satisfy the condition t1>2·Q·μ/(σt·t2). be.

As the material for the retainer, it is preferable to adopt phenol resin, which has excellent heat resistance and is suitable for high-speed operation of the bearing.

As described above, the ball bearing of the present invention can hold a large amount of lubricant in the recesses formed in at least a part of the column portion of the cage. This makes it possible to reliably prevent the oil film from running out between the cage and the outer ring. In addition, during operation of the bearing, the cage is always pushed toward the guide surface, the inner peripheral surface of the outer ring, by the force received from the balls. Since the retainer rotates in a state where it is pushed by the force, the behavior of the retainer is stable even in the high-speed rotation range, and vibration is less likely to occur. Therefore, compared with the conventional one, it has excellent stability and durability at high speed rotation.

FIG. 2 is a longitudinal front view of essential parts of the ball bearing of the first embodiment; FIG. 2 is a perspective view of a portion of the inner circumference of the retainer in FIG. 1 ; Vertical cross-sectional front view for explaining cage dimensions in Fig. 1 Cross-sectional view along the IV-IV line in Fig. 1 A graph showing the results of a high-speed operation test (air-oil lubrication) of the ball bearing in Fig. 1 in comparison with the conventional one. A graph showing the results of a high-speed operation test (grease lubrication) of the ball bearing in Fig. 1 in comparison with the conventional one. FIG. 2 is a vertical cross-sectional front view of a main part showing a modification of the retainer shape of the ball bearing of FIG. 1 Vertical front view of the essential part of the ball bearing of the second embodiment FIG. 9 is a longitudinal sectional front view of a main part showing a modification of the retainer shape of the ball bearing of FIG.

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show the ball bearing of the first embodiment. As shown in FIG. 1, this ball bearing comprises an outer ring 1 having a raceway groove 1a formed on its inner peripheral surface, and an inner ring 2 disposed radially inward of the outer ring 1 and having a raceway groove 2a formed on its outer peripheral surface. , an angular contact ball bearing comprising a plurality of balls 3 arranged between a raceway groove 1a of an outer ring 1 and a raceway groove 2a of an inner ring 2, and an outer ring guide type retainer 4 that retains each ball 3 so that it can roll freely. , which supports a high-speed rotating shaft (not shown). The outer ring 1, inner ring 2 and balls 3 are made of steel, and the retainer 4 is made of phenolic resin.

On the inner peripheral surface of the outer ring 1, a shoulder portion 1b is formed on one axial side (left side in FIG. 1) of the raceway groove 1a, and a counterbore 1c is formed on the other axial side (right side in FIG. 1). ing. On the outer peripheral surface of the inner ring 2, a small-diameter shoulder portion 2b is formed on one side of the raceway groove 2a in the axial direction, and a large-diameter shoulder portion 2c is formed on the other axial side of the raceway groove 2a. The small-diameter shoulder portion 2b of the inner ring 2 is designed to have a smaller diameter than usual in consideration of the supply or discharge of lubricant. Lubricating oil is supplied together with compressed air from an external lubricating device (not shown) to an annular space 5 (inside the bearing) formed between the outer ring 1 and the inner ring 2 to perform air-oil lubrication, or the annular space 5 is lubricated. Filled with grease for grease lubrication.

As shown in FIGS. 1 and 2, the retainer 4 includes annular portions 41 arranged on both sides in the axial direction, and a plurality of annular portions 41 arranged at predetermined intervals in the circumferential direction in a state where both annular portions 41 are axially connected. The ball 3 is held in a circular pocket 43 formed between the pillars 42 adjacent in the circumferential direction. A trapezoidal groove-shaped recess 42a (having a flat bottom and side walls) is formed on the side of each column 42 facing the inner ring 2 .

Here, as shown in FIG. 3, the recessed portion 42a of each column portion 42 of the retainer 4 has a widthwise dimension w1 set to be equal to or less than the widthwise dimension w2 of the pocket 43 in the axial cross section of the retainer 4. . Thereby, the strength design of the retainer 4 can be easily performed.

As shown in FIG. 4, each pillar 42 of the retainer 4 has a center portion of the portion where the bottom of the recess 42a is formed in the peripheral edge of the recess 42a. contact with the ball 3 on the outer side in the radial direction. As a result, the retainer 4 always receives a force in the direction of being pushed toward the inner peripheral surface of the outer ring 1 from the rolling balls 3 during operation of the bearing.

This ball bearing has the above-described structure, and recesses 42a are formed on the sides of the columns 42 of the retainer 4 facing the inner ring 2 so as to extend radially outward of the pitch circles C of the balls 3. Therefore, a large amount of lubricant can be held in the concave portion 42a. Therefore, the lubricant is easily supplied between the outer peripheral surface of the cage 4 and the inner peripheral surface of the outer ring 1, and the occurrence of oil film breakage between the cage 4 and the outer ring 1 can be reliably suppressed. Further, during operation of the bearing, the cage 4 rotates while being pushed toward the inner peripheral surface of the outer ring 1, which is the guide surface, by the force received from the balls 3. Therefore, the behavior of the cage 4 does not change even in the high-speed rotation range. Stable and less prone to vibration. Therefore, it is possible to improve the stability and durability at high speed rotation as compared with the conventional one.

In addition, in this ball bearing, the concave portion 42a of each column portion 42 of the retainer 4 is made larger than the conventional one, and the diameter of the small diameter shoulder portion 2b formed on one side of the inner ring 2 in the axial direction is made smaller than usual. , the lubricant is easily supplied between the retainer 4 and the outer peripheral surface of the inner ring 2 . Therefore, in the case of grease lubrication, the amount of grease enclosed can be increased, and in the case of air-oil lubrication, lubricating oil can be supplied from an oblique direction, which was not possible in the past. The dimensional restrictions on the nozzle-equipped spacer provided therebetween are relaxed, and the degree of freedom in designing the peripheral structure of the bearing can be improved.

Next, a high-speed operation test conducted to confirm the performance of the ball bearing of this embodiment will be described. In this high-speed operation test, an angular contact ball bearing having an inner ring inner diameter of 50 mm, an outer ring outer diameter of 90 mm, and a width of 20 mm, in which the recesses of the embodiment were formed in each column of the retainer (Example), and the column of the retainer With regard to the same specification as the example (conventional example) except that each concave portion is formed to a size that does not reach the pitch circle of the ball, first, the relationship between the rotation speed and the temperature rise of the outer ring was evaluated by air-oil lubrication and grease lubrication. compared. The results are shown in FIGS. 5 and 6. FIG.

As can be seen from FIGS. 5 and 6, it was confirmed that the temperature rise of the outer ring of the example is equal to or lower than that of the conventional example, even at high speed rotation, in both cases of air-oil lubrication and grease lubrication.

Subsequently, the ball bearings of the same example and the conventional example as described above were operated at a constant speed for a long time with grease lubrication, and the durability was compared. As a result, in the conventional example, when operated at 13000 rpm, vibration occurred after about 140 hours, and when disassembled, the oil film between the cage and the outer ring was broken. On the other hand, in the example, no abnormalities such as vibration occurred even after 150 hours of operation at 13000 rpm, and it was confirmed that even if the rotation speed was increased to 14000 rpm, it could be operated for about 150 hours. As a result, it was confirmed that the working example was greatly improved in stability and durability at high speed rotation compared to the conventional example.

FIG. 7 shows a modification of the retainer shape of the ball bearing of the first embodiment described above. In the retainer 4 of this modified example, the side wall of the concave portion 42a of the column portion 42 is formed with a concave curved surface. In this way, compared to the example of FIGS. 1 to 3 in which the recess 42a of the column 42 is formed in a trapezoidal groove shape, if the width dimension of the recess 42a is the same, the amount of lubricant retained can be increased to some extent. be able to.

FIG. 8 shows a second embodiment. The ball bearing of this embodiment is based on the first embodiment, and is formed with trapezoidal groove-like concave portions 42b on the side of each column portion 42 of the retainer 4 facing the outer ring 1 as well. Therefore, compared to the first embodiment, the amount of lubricant retained is greatly increased, and the lubricant can be more stably supplied between the outer peripheral surface of the cage 4 and the inner peripheral surface of the outer ring 1. and the outer ring 1.

In the second embodiment, the radial thickness of the pillars 42 of the retainer 4 is thinner than in the first embodiment. When μ is the coefficient of friction with the outer ring 1, σt is the allowable shear strength of the material of the cage 4, and t2 is the wall thickness of the column portion 42 in the circumferential direction, t1>2Qμ/(σt t2 ), it is necessary to design the cage so as to satisfy the condition

FIG. 9 shows a modification of the retainer shape of the ball bearing of the second embodiment. In the retainer 4 of this modified example, similarly to the modified example of the first embodiment shown in FIG. It is designed to be larger than the example in FIG.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the meaning described above, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

For example, in each of the embodiments described above, the recesses are formed in the respective column portions of the retainer, but only some of the column portions may form recesses. Also, the bottom of the recess is not limited to a flat surface as in each embodiment, and may be a curved surface.

As for the material of the cage, it is preferable to use phenolic resin, which has excellent heat resistance, as in each embodiment. can also There are no restrictions on the method of manufacturing the retainer, and press working, cutting, molding, etc. may be selected according to the material.

Of course, the present invention can also be applied to ball bearings other than the angular contact ball bearings of the embodiment, such as deep groove ball bearings.

1 Outer ring 1a Raceway groove 2 Inner ring 2a Raceway groove 3 Ball 4 Cage 5 Annular space 41 Annular portion 42 Column portion 42a Concave portion (inner ring side)
42b recess (outer ring side)
43 Pocket C ball pitch circle

Claims (5)

An outer ring having raceway grooves formed on its inner peripheral surface, an inner ring having raceway grooves formed on its outer peripheral surface, a plurality of balls arranged between the raceway grooves of the outer ring and the raceway grooves of the inner ring, and the respective balls. and an outer ring guide type retainer for rollingly holding the
The retainer has annular portions arranged on both sides in the axial direction, and a plurality of column portions arranged at predetermined intervals in the circumferential direction in a state in which both the annular portions are connected in the axial direction. In a ball bearing that holds the ball in a pocket formed between the pillars,
At least a part of the column portion of the retainer has a concave portion formed on a side facing the inner ring, and a peripheral edge portion of the concave portion contacts the ball radially outside a pitch circle of the ball. ball bearings. 2. At least a portion of the pillars of the retainer has a flat or curved bottom of the recess, and contacts the ball at one location where the bottom of the recess is formed. The ball bearing described in . 3. The ball bearing according to claim 1, wherein, in an axial cross section of said retainer, the width dimension of said concave portion of said column portion is equal to or less than the width dimension of said pocket. 4. The ball bearing according to any one of claims 1 to 3, wherein at least a portion of the column portion of the retainer has a recess formed on a side facing the outer ring. 5. A ball bearing according to any one of claims 1 to 4, wherein the material of said retainer is phenolic resin.

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