JP5163512B2 - Rolling bearing - Google Patents

Description

  The present invention relates to a rolling bearing, and more particularly to a rolling bearing that can improve bearing life, static strength, rigidity, and the like of the bearing.

FIG. 7 shows a general contact state when a heavy load is applied between the roller 1 and the inner ring 2 in the rolling bearing.
The illustrated roller 1 is a tapered roller and has R chamfers 1a at both ends. The outer peripheral surface of the roller 1 excluding the R chamfer 1a is the rolling surface 1b.
In FIG. 7, symbol s1 is the width (radius) dimension of the R chamfer 1a, and symbol s2 is the length of the rolling surface 1b.

  The inner ring 2 is provided on an inner ring raceway surface 2a on which the roller 1 rolls, a large collar 2b provided on one side of the inner ring raceway surface 2a and pressing one end surface of the roller 1, and provided on the other side of the inner ring raceway surface 2a. A small collar 2c for pressing the other end surface of the roller 1 is provided.

  Further, at the position where the inner ring raceway surface 2a of the inner ring 2 intersects the large brim 2b and the position where the inner ring raceway surface 2a intersects the small brim 2c, escapes 2d and 2e for avoiding interference with the chamfer 1a, respectively. Is formed.

  In FIG. 7, reference numeral s3 denotes a large raceway raceway clearance dimension indicating a decrease in the inner raceway surface due to the large collar 2b side relief 2d, and reference symbol s4 denotes a decrease in the inner ring raceway surface due to the small collar 2c side relief 2e. The raceway clearance dimension on the small brim side shown, symbol s5 is the length of the inner ring raceway surface 2a.

  In such a rolling bearing, the contact surface of the roller or the bearing ring may be crowned so that the contact surface pressure acting on the roller is uniform and uniform.

  Here, the term “crowning” refers to giving a slight curvature to the raceway surface or the roller bus for the main purpose of preventing an edge load generated at the contact portion with the raceway. Usually, such crowning is applied to either or both of the raceway surfaces and / or rollers of the inner and outer rings.

  Conventionally, as a crowning curve indicating the shape of the crowning, there has been known a rolling bearing using a logarithmic curve capable of uniforming the stress generated when the rollers are vertically pressed against the raceway with a predetermined load in the axial direction. .

  On the other hand, the load acting on the rolling bearing varies in various ways with the rotation of the rolling bearing, such as high load, light load, moment load, etc. Generally, in order to prevent plastic deformation of the rolling contact portion, the most severe load conditions A crowning shape in which the logarithmic crowning drop amount (crowning amount) is increased so that the maximum contact surface pressure at that time becomes a certain value or less is used.

However, such a crowning has a large drop at the center part, so the contact length is shortened under light load to medium load conditions that are frequently used, and peeling occurs early from the center part, resulting in a shorter bearing life. There was a problem of lowering.
In order to solve this problem, there has been proposed a crowning-shaped rolling bearing composed of a combination curve in which a central portion is a straight line and an end portion is a logarithmic curve (see, for example, Patent Document 1).

JP 2005-155663 A

  In a conventional roller bearing equipped with reliefs 2d and 2e on both sides of the inner ring raceway surface 2a in order to avoid interference with the R chamfer 1a of the roller 1, as shown in FIG. 7, the raceway surface due to the reliefs 2d and 2e. Therefore, the length s5 of the inner ring raceway surface is shorter than the length s2 of the rolling surface.

  As a result, the contact surface pressure between the roller 1 and the inner ring 2 has peaks p1 and p2 at which the surface pressure suddenly increases at both ends of the raceway surface adjacent to the relief, as shown in the contact surface pressure distribution curve f1 in FIG. As a result, the excessive surface pressure acts locally between the roller 1 and the inner ring 2, which causes inconveniences such as a reduction in bearing life.

Moreover, since the crowning shape of the rolling bearing described in Patent Document 1 is a curve in which the straight line at the center and the logarithmic curve at the end are combined, the joint between the straight line and the logarithmic curve is smoothly continued. However, there is a problem that a contact pressure peak occurs at the joint, and as a result, an edge load occurs at the joint under a high load operating condition, resulting in a decrease in bearing life.
Further, even under light load to medium load conditions, further improvement has been demanded in order to make it possible to extend the life of the bearing by effectively utilizing the effective contact length.

  The present invention aims to solve the above-described problems, and provides a rolling bearing that can improve the contact surface pressure distribution between the roller and the inner ring and improve the bearing life, the static strength, the rigidity, and the like of the bearing. It is another object of the present invention to provide a rolling bearing capable of achieving both prevention of edge load generation under high load conditions and prevention of reduction in bearing life under light to medium load conditions.

The above object is achieved by the following configuration.
(1) An outer ring having an outer ring raceway surface formed on an inner peripheral surface, an inner ring having an outer ring raceway surface formed on an outer peripheral surface, and a rollable arrangement between the outer ring raceway surface and the inner ring raceway surface. A rolling bearing comprising a plurality of rollers,
While eliminating or reducing the escape of the inner ring raceway surface, the length of the inner ring raceway surface is set larger than the length of the rolling surface of the roller,
A rolling bearing characterized in that the chamfer dimension of the inner ring raceway surface is reduced or the chamfered shape is changed to C chamfering so that the chamfering of the roller does not interfere with the inner ring by eliminating or reducing the clearance.

  (2) The rolling surface of the roller is subjected to circular logarithmic crowning composed of a circular curve at the center of the rolling surface and a combined curve of the circular curve and logarithmic curve at both ends of the rolling surface. The rolling bearing according to (1) above, which is characterized.

  (3) The rolling bearing according to (2), wherein the shape of the logarithmic logarithmic crowning is determined based on the following formula (1).

The function if (a, b, c) is a function that is replaced with the expression b when the conditional expression a is satisfied, and is replaced with the expression c when the conditional expression a is not satisfied.
here,
Center length L ₁ : L ₁ = r ₁ × (le / 2)
End length L ₂ : L ₂ = (le / 2) −L ₁
Arc radius of the central part R: R = (D ₁ ² + L ₁ ² ) / (2 × D ₁ )
x: coordinates with the center of the crowning as the origin : Effective crowning length (length of rolling surface)
r ₁ : ratio of central length to effective crowning length (2L ₁ / le)
D ₁ : Drop amount at the joint between the center and the end D ₂ : Logarithmic curve component of drop amount at the end of the effective crowning length k: Parameters for adjusting the roundness of the logarithm (0 <k <1)
It is.

  In the rolling bearing of the present invention, the clearance of the inner ring raceway surface is abolished or reduced, and the length of the inner ring raceway surface is set larger than the length of the roller rolling surface. Compared with conventional rolling bearings that are smaller than the length of the surface, the contact length and contact area between the rolling surface of the roller and the inner ring raceway surface increases, and as a result, the contact between the roller rolling surface and the inner ring raceway surface increases. The contact surface pressure distribution between them has no abrupt surface pressure change and a gentle surface pressure change distribution. Further, overall reduction in surface pressure can be obtained.

It is a longitudinal cross-sectional view of one embodiment of a rolling bearing. It is the expanded sectional view which showed the contact state of the roller and inner ring | wheel in a rolling bearing. It is explanatory drawing of the synthetic | combination curve of the circular arc curve and logarithmic curve which comprise circular arc logarithmic crowning shape. It is a graph which shows the measured value of the lifetime improvement rate (life UP rate) in each Example of a rolling bearing. It is a graph which shows the measured value of the static strength improvement rate (static strength UP rate) in each Example of a rolling bearing. It is a graph which shows the measured value of the axial rigidity improvement rate (rigidity UP rate) in each Example of a rolling bearing. It is the expanded sectional view which showed the contact state of the roller and inner ring in the conventional rolling bearing.

Hereinafter, preferred embodiments of a rolling bearing according to the present invention will be described in detail with reference to the drawings.
1 is a longitudinal sectional view of an embodiment of a rolling bearing according to the present invention, FIG. 2 is an enlarged sectional view showing a contact state between a roller and an inner ring in the rolling bearing shown in FIG. 1, and FIG. It is explanatory drawing of the synthetic | combination curve of the circular arc curve and logarithmic curve which comprise the circular arc logarithmic crown shape given to the rolling surface of the roller shown.

  As shown in FIG. 1, the rolling bearing 10 of this embodiment includes an outer ring 11 having an outer ring raceway surface 11a formed on the inner peripheral surface, an inner ring 12 having an inner ring raceway surface 12a formed on the outer peripheral surface, and an outer ring. The roller 13 which is a some rolling element arrange | positioned so that rolling is possible between the raceway surface 11a and the inner ring raceway surface 12a, and the holder | retainer 14 which hold | maintains the space | interval of the some roller 13 are provided.

In the case of the rolling bearing 10 of the present embodiment, a tapered roller or a cylindrical roller can be applied to the roller 13.
The rollers 13 have R chamfers 13b (see FIG. 2) at both ends. The outer peripheral surface excluding the R chamfer 13b portion of the roller 13 is a rolling surface 13a of the roller.

In FIG. 2, the symbol w1 is the width (radius) dimension of the R chamfer 13b, and the symbol le is the length of the rolling surface 13a used in the following equation (1).
In the case of the present embodiment, the R chamfer 13b of the roller 13 has a width of the R chamfer 13b in order to avoid the R chamfer 13b from interfering with the inner ring 12 due to the abolition of the escape on the inner ring raceway surface 12a described later. The dimension w1 is not changed and is set to a dimension larger than usual or C chamfering.

  The inner ring 12 is provided with a large collar 12b for pressing one end surface of the roller 13 on one side of the inner ring raceway surface 12a on which the roller 13 rolls, and the other end surface of the roller 13 is pressed on the other side of the inner ring raceway surface 12a. A small collar 12c is provided.

In the case of the rolling bearing 10 of the present embodiment, the inner ring raceway surface 12 a eliminates the conventional relief for avoiding interference with the rollers 13.
However, in order to enable polishing of the inner ring raceway surface 12a and the inner side surface of each brim and at the same time prevent stress concentration, the minimum necessary curved recesses 16 and 17 are provided at both ends of the inner ring raceway surface 12a. ing. In other words, it can be said that the grinding clearance is reduced.

The dimensions w3 and w4 shown in FIG. 2 are dimensions in which the curved recesses 16 and 17 reduce the length of the inner ring raceway surface 12a.
A length T obtained by subtracting these dimensions w3 and w4 from the total length of the roller 13 is the length dimension of the inner ring raceway surface 12a.

The dimensions w3 and w4 are much smaller than the conventional clearances 2d and 2e (see FIG. 7), and are set smaller than the R chamfer 13b of the roller 13.
While eliminating the conventional relief on the inner ring raceway surface 12a, as described above, by setting the dimensions w3 and w4 of the curved recesses 16 and 17, the length T of the inner ring raceway surface 12a in the present embodiment is It is set larger than the length le of the rolling surface 13a.

Further, in the case of the present embodiment, the inner ring raceway surface 12a of the inner ring 12 substantially eliminates the clearance, so that the boundary between the polished surface and the non-polished surface cannot be distinguished in processing. Therefore, it is difficult to accurately process the arcuate curve or logarithmic crowning shape on the inner ring raceway surface 12a.
Therefore, in the rolling bearing 10 of the present embodiment, the crowning applied to the inner ring raceway surface 12a and the outer ring raceway surface 11a is an arc crowning having a slight sag at the ends.

  On the other hand, the crowning applied to the rolling surface 13a of the roller 13 is for the purpose of making the contact surface pressure between the outer ring raceway surface 11a and the inner ring raceway surface 12a as uniform as possible and eliminating the occurrence of edge load. The central portion of 13a is an arc curve, and the ends on both sides of the center portion are arc log crowning composed of a composite curve of the arc curve and logarithmic curve.

  In the present embodiment, the shape of the arc logarithmic crowning applied to the rolling surface 13a of the roller 13 is determined based on, for example, the following formula (1).

In the above equation (1), the function if (a, b, c) is a function that is replaced by the equation b when the conditional equation a is satisfied, and is replaced by the equation c when the conditional equation a is not satisfied. is there.
here,
Center length L ₁ : L ₁ = r ₁ × (le / 2)
End length L ₂ : L ₂ = (le / 2) −L ₁
Arc radius of the central part R: R = (D ₁ ² + L ₁ ² ) / (2 × D ₁ )
x: coordinates with the center of the crowning as the origin : Effective crowning length (length of rolling surface)
r ₁ : ratio of central length to effective crowning length (2L ₁ / le)
D ₁ : Drop amount at the joint between the center and the end D ₂ : Logarithmic curve component of drop amount at the end of the effective crowning length k: Parameters for adjusting the roundness of the logarithm (0 <k <1)
It is.

Note that the crowning shape formed by the above equation (1) will be supplementarily described with reference to FIG.
The arc curve A in FIG. 3 is obtained from the arc equation portion of the equation (1) (the first half portion of the equation (1)), and the logarithmic curve B in FIG. 3 is obtained from the logarithmic equation portion (the second half portion of the equation (1)). .
In the present invention, the composite curve C applied to the crowning at both ends of the rolling surface of the roller is obtained as the sum of the arc curve A and the logarithmic curve B.

In the example shown in FIG. 2, the crowning shape of the range of the central director of L ₁ is due to the arc curve A in FIG. 3, the crowning shape of the range of the end portion length L ₂ is due to the synthesis curve C in FIG. 3 It has become a thing.

As described above, in the rolling bearing 10 of the present embodiment, the clearance le of the inner ring raceway surface 12a is abolished or reduced, and the length T of the inner ring raceway surface 12a is made longer than the length of the rolling surface 13a of the roller 13. Therefore, compared with the conventional rolling bearing in which the length of the inner ring raceway surface is smaller than the length of the roller rolling surface, the contact length between the rolling surface 13a of the roller 13 and the inner ring raceway surface 12a The contact area increases, and as a result, the contact surface pressure distribution between the rolling surface 13a of the roller 13 and the inner ring raceway surface 12a changes rapidly as shown in the contact surface pressure distribution curve f2 in FIG. There is no distribution of surface pressure. Further, overall reduction in surface pressure can be obtained.
Accordingly, it is avoided that excessive surface pressure acts locally between the roller 13 and the inner ring 12, and at the same time, the contact surface pressure distribution between the roller 13 and the inner ring 12 decreases in the direction in which the surface pressure decreases. As a result, the bearing life, the static strength, the rigidity, etc. of the bearing can be improved.

  Further, in the rolling bearing 10 of the present embodiment, the R chamfer 13b dimension of the roller 13 is reduced as compared with the conventional one so that the R chamfer 13b of the roller 13 does not interfere with the inner ring 12 due to the substantial elimination of the clearance. There are no inconveniences caused by interference with the 13 chamfers 13b.

Further, in the rolling bearing 10 of the present embodiment, the crowning applied to the rolling surface 13a of the roller 13 is an arc logarithm whose center is an arc curve and whose end is a composite curve of an arc curve and a logarithmic curve. Because it is crowning, the joint between the center part and the end part can be made a smooth joint with no peak compared to the case of the conventional rolling bearing in which the center part has a linear shape. The occurrence of a contact pressure peak can be prevented. In addition, since the crowning shape in the center is an arc curve, the amount of drop in the center is suppressed from being excessive compared to the logarithmic curve up to the center. The contact length under load conditions can be increased.
Therefore, it is possible to prevent the occurrence of an edge load when a high load is applied to the bearing, and further to prevent a decrease in bearing life under light to medium load conditions, and to eliminate the escape of the inner ring raceway surface 12a. The effect | action and effect by having performed can be improved further.

  Further, the inner ring raceway surface 12a, which has eliminated the escape to avoid the interference with the R chamfer 13b of the roller 13, cannot accurately distinguish the boundary between the polished surface and the non-polished surface in processing. It is difficult to apply crowning. However, when the crowning is applied to the rolling surface 13a of the roller 13 as in the present embodiment, a highly accurate crowning shape can be formed relatively easily, and the bearing performance of the arc logarithmic crowning can be easily achieved. Improvements can be made.

In order to confirm the operation and effect of the above-described embodiment, performances such as a bearing life, a static strength of the bearing, and an axial rigidity were measured for specific examples of the above-described embodiment.
In each of the examples, as described in the embodiment, the escape of the inner ring raceway surface 12 a is abolished, and the length T of the inner ring raceway surface is made longer than the length le of the rolling surface 13 a of the roller 13. Measurement was performed on five samples that were set large and the rated load was changed by changing the contact length between the inner ring raceway surface 12a and the rolling contact surface 13a. In addition, the dimension of the R chamfer 13b of the roller 13 is reduced so that the R chamfer 13b of the roller 13 does not interfere with the inner ring 12 by abolishing the escape. Further, the rolling surface 13a of the roller 13 is subjected to the crowning shown in the above formula (1).

FIG. 4 is a graph showing the measured value of the life improvement rate (life UP rate) in each example, and FIG. 5 is a graph showing the measured value of the static strength improvement rate (static strength UP rate) in each example. 6 is a graph showing the measured value of the axial rigidity improvement rate (rigidity UP rate) in each Example.
The improvement rate in each figure is a performance improvement rate based on the performance of a standard rolling bearing in which a conventional relief is formed on the inner ring raceway surface of each example.
As shown in the graphs of FIGS. 4 to 6, in each of the examples, the sample (4) → (2) → where the improvement rate of the rated load is large in the bearing life, the static strength of the bearing, and the axial rigidity. Each performance improvement was confirmed in the order of (1) → (3) → (5).

  In the above embodiment, the chamfer dimension of the roller is reduced so that the R chamfer 13b of the roller 13 does not interfere with the inner ring by eliminating the clearance on the inner ring raceway surface 12a. Instead, the chamfered shape of the roller 13 is changed. It is also effective to change to C chamfering.

DESCRIPTION OF SYMBOLS 10 Rolling bearing 11 Outer ring 11a Outer ring raceway surface 12 Inner ring 12a Inner ring raceway surface 13 Roller 13a Rolling surface 14 Cage f2 Contact surface pressure distribution curve

Claims (3)

An outer ring having an outer ring raceway surface formed on an inner peripheral surface, an inner ring having an outer ring raceway surface formed on an outer peripheral surface, and a plurality of rollers rotatably disposed between the outer ring raceway surface and the inner ring raceway surface A rolling bearing comprising:
While eliminating or reducing the escape of the inner ring raceway surface, the length of the inner ring raceway surface is set larger than the length of the rolling surface of the roller,
A rolling bearing characterized in that the chamfer dimension of the inner ring raceway surface is reduced or the chamfered shape is changed to C chamfering so that the chamfering of the roller does not interfere with the inner ring by eliminating or reducing the clearance.   The rolling surface of the roller is characterized by an arc logarithmic crowning composed of an arc curve at the center of the rolling surface and both ends of the rolling surface composed of a combined curve of an arc curve and a logarithmic curve. The rolling bearing according to claim 1. The rolling bearing according to claim 2, wherein the shape of the arc logarithmic crowning is determined based on the following formula (1).

The function if (a, b, c) is a function that is replaced with the expression b when the conditional expression a is satisfied, and is replaced with the expression c when the conditional expression a is not satisfied.
here,
Center length L ₁ : L ₁ = r ₁ × (le / 2)
End length L ₂ : L ₂ = (le / 2) −L ₁
Arc radius of the central part R: R = (D ₁ ² + L ₁ ² ) / (2 × D ₁ )
x: coordinates with the center of the crowning as the origin : Effective crowning length (length of rolling surface)
r ₁ : ratio of central length to effective crowning length (2L ₁ / le)
D ₁ : Drop amount at the joint between the center and the end D ₂ : Logarithmic curve component of drop amount at the end of the effective crowning length k: Parameters for adjusting the roundness of the logarithm (0 <k <1)
It is.

Images