JP5251431B2 - Tapered roller bearing - Google Patents

Description

  The present invention relates to a tapered roller bearing. More specifically, the contact surface pressure between the roller and the raceway surface is made appropriate so that edge load (concentrated load) can be prevented and the bearing life can be extended. The present invention relates to a tapered roller bearing with an improved crowning.

  In roller bearings such as cylindrical roller bearings and tapered roller bearings, crowning is sometimes applied to the contact surfaces of the rollers and the raceway rings so that the contact surface pressure acting on the rollers is 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 roller bearing using a logarithmic curve capable of uniforming the stress generated when the roller is vertically pressed against the raceway with a predetermined load in the axial direction. .

  On the other hand, the load acting on the roller bearing varies variously as the roller bearing rotates, such as high load, light load, moment load, etc. Generally, in order to prevent plastic deformation of the rolling contact part, the most severe load conditions A crowning bus bar shape in which the crowning amount of the logarithmic crowning is increased is used so that the maximum contact surface pressure at that time is less than a certain value.

However, such a crowning has a large amount of crowning at the center, so the contact length is shortened under light load to medium load conditions that are frequently used, and peeling occurs early from the center and the bearing life is shortened. There was a problem of lowering.
Therefore, in order to solve this problem, at least one of the outer ring raceway surface, the inner ring raceway surface, and the rolling surface of the roller is provided with a crowning shape including a combination curve in which the central portion is a straight line and the end portion is a logarithmic curve. A roller bearing is proposed (for example, see Patent Document 1).

JP 2005-155663 A

By the way, in the case of conventional tapered roller bearings, as disclosed in FIG. 1C of Patent Document 1, many outer ring raceway surfaces are set larger than the rolling surface of the rollers.
In such a tapered roller bearing, when the outer ring raceway surface has a crowning shape composed of a combination curve with the center portion being a straight line and the end portion being a logarithmic curve, the logarithmic curve causes a large drop on the crowning end portion of the outer ring raceway surface. Even if the amount is formed, if the crowning shape of the end part is out of the rolling surface of the roller, the large drop amount of the crowning end part is not utilized for the bearing operation, and the expected bearing performance cannot be obtained. The problem will arise.

Furthermore, since the crowning bus bar shape of the roller 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 continuous. There is a problem that a peak of contact pressure 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-mentioned problems, and can effectively utilize the large drop amount set at the crowning end by the crowning bus bar shape using a logarithmic curve, under the assumed high load condition. It is an object of the present invention to provide a tapered roller bearing capable of achieving both prevention of occurrence of edge load 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 tapered roller bearing comprising a plurality of tapered rollers,
The rolling surface of the tapered roller is crowned by an arc curve,
At least one of the outer ring raceway surface and the inner ring raceway surface is subjected to arc logarithmic crowning that forms a generatrix of an arc logarithmic curve composed of a circular curve at the center and a combined curve of the arc curve and logarithm at both ends,
In addition, the effective crowning length of the raceway surface to which the arc logarithmic crowning is applied is restricted to be shorter than the length of the rolling surface of the tapered roller so that the arc logarithmic crowning is within the rolling surface of the tapered roller. Tapered roller bearings characterized by

なお、関数if(a,b,c)は、条件式ａが成立する場合には、式ｂに置き換えられ、不成立の場合にあ、式ｃで置き換えられる関数である。
ここに、
中央部長さ Ｌ_１：Ｌ_１＝ｒ_１×（ｌe／２）
端部長さ Ｌ_２：Ｌ_２＝（ｌe／２）−Ｌ_１
中央部円弧半径 Ｒ：Ｒ＝（Ｄ_１ ^２＋Ｌ_１ ^２）／（２×Ｄ_１）
ｘ ：中央を原点とする座標
ｌe ：有効クラウニング長（有効軌道長さ）
ｒ_１ ：有効クラウニング長に対する中央部長さの比（２Ｌ_１／ｌ_ｅ）
Ｄ_１ ：中央部と端部とのつなぎ目における落ち量
Ｄ₂ ：有効クラウニング長の端における落ち量の対数曲線成分
ｋ ：対数部の丸みを調整するためのパラメータ（０＜ｋ＜１）
である。 (2) The tapered roller bearing according to (1), 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
Central arc radius R: R = (D ₁ ² + L ₁ ² ) / (2 × D ₁ )
x: coordinates with the origin at the center : Effective crowning length (effective trajectory length)
r ₁ : ratio of center length to effective crowning length (2L ₁ / l _e )
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 tapered roller bearing according to the present invention, at least one of the outer ring raceway surface and the inner ring raceway surface has a generatrix shape of an arc logarithmic curve composed of a circular curve at the center and a composite curve of the arc curve and logarithm at both ends. For example, a large drop amount necessary for preventing the occurrence of an edge load under a high load can be set at the crowning end portion.
In addition, the effective crowning length of the raceway surface to which the logarithmic arc crowning is applied is regulated so that the arc logarithmic crowning is within the rolling surface of the tapered roller. The portion can be brought into contact with the rolling surface of the tapered roller with certainty, and can effectively function to prevent the occurrence of edge load at the crowning end.

Hereinafter, preferred embodiments of a tapered roller bearing according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view of an embodiment of a tapered roller bearing according to the present invention, and FIG. 2 is a combination of an arc curve and a logarithmic curve constituting an arc logarithmic crowning shape applied to the raceway surface of the inner and outer rings shown in FIG. FIG. 3 is an explanatory diagram of a crowning center of an arc log crowning shape applied to the raceway surface of the inner and outer rings in the present invention, and FIG. 4 is a crowning end regulated by an arc logarithmic crowning shape applied to the raceway surface of the outer ring in the present invention. FIG. 5 is an explanatory view of the position of the crowning end portion regulated by an arc logarithmic crowning shape applied to the raceway surface of the inner ring in the present invention.

  As shown in FIG. 1, a tapered roller bearing 10 according to an 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 outer ring raceway surface 12a formed on the outer peripheral surface, and an outer ring. A tapered roller 13 that is a plurality of rolling elements disposed between the raceway surface 11a and the inner ring raceway surface 12a so as to be freely rollable, and a retainer 14 that holds a space between the plurality of rollers 13 are provided. .

  As shown in FIG. 1, the tapered roller 13 has a rolling surface 13a in a range obtained by removing the chamfered portions 13b at both ends from the entire length. A symbol s1 in FIG. 1 indicates the length of the rolling surface 13a. In the present embodiment, the rolling surface 13a is crowned by an arc curve.

  Reliefs 12d and 12e for avoiding interference with the chamfered portion 13b of the roller 13 are provided between the large collar 12b of the inner ring 12 and the inner ring raceway surface 12a, and between the small collar 12c and the inner ring raceway surface 12a, respectively. Is provided.

The outer ring raceway surface 11a and the inner ring raceway surface 12a are crowned within the range of the respective effective crowning lengths (effective track lengths).
Specifically, in each effective crowning length range, arc logarithmic crowning is performed in which the arc logarithm curve, which is composed of a circular curve at the center and a composite curve of the arc curve and logarithm at both ends, has a bus shape. ing.

The symbol s2 in FIG. 1 is the effective crowning length (effective track length) of the outer ring raceway surface 11a, and the symbol s3 is the effective crowning length (effective track length) of the inner ring raceway surface 12a.
Moreover, in FIG. 1, the code | symbol w2 has shown the range of the center part in the effective crowning length s2 of the outer ring raceway surface 11a, and the code | symbol v2 has shown the range of the edge part in the effective crowning length s2.
The symbol w3 indicates the range of the central portion of the outer ring raceway surface 12a in the effective crowning length s3, and the symbol v3 indicates the range of the end portion in the effective crowning length s3.

  The shape of the logarithmic logarithmic crowning applied to the outer ring raceway surface 11a and the inner ring raceway surface 12a is determined based on the following equation (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
Central arc radius R: R = (D ₁ ² + L ₁ ² ) / (2 × D ₁ )
x: coordinates with the origin at the center : Effective crowning length (effective trajectory length)
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. 2 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. 2 is obtained from the logarithmic equation portion (the second half portion of the equation (1)). .
In the present invention, the combined curve C applied to the crowning at both ends of the range of the effective crowning length of each track surface is obtained as the sum of the arc curve A and the logarithmic curve B.

The range indicated by reference numerals w2 and w3 in FIG. 1 corresponds to the central portion length L1 of the effective crowning length of each raceway surface, and is formed in a crowning shape by the arc curve A in FIG .
Further, the range indicated by reference signs v2 and v3 in FIG. 1 corresponds to the end length L2 of the effective crowning length of each raceway surface, and is formed in a crowning shape by the composite curve C in FIG.

  Furthermore, in the case of the present embodiment, the effective crowning length of each raceway surface subjected to arc logarithmic crowning so that the arc logarithmic crowning applied to each raceway surface 11a, 12a is within the width of the rolling surface 13a of the tapered roller 13. Is regulated.

The regulation of the end face position on each raceway surface 11a, 12a determines the crowning center which is the center of the effective crowning length on each raceway face 11a, 12a, and defines where the crowning center is located from the end face of the inner and outer rings.
As shown in FIG. 3, the crowning center c <b> 1 means the center of the effective crowning length le that secures the required drop amount H.

  In the case of the outer ring 11, as shown in FIG. 4, a distance Y from the end surface position k1 to the crowning center c1 is defined with reference to the end surface position k1 on the front side or the back side that contacts the pedestal 21.

  In the case of the inner ring 12, as shown in FIG. 5, the front surface or the rear surface end surface position k2 that contacts the pedestal 23 is used as a reference, or the end surface position k2 of the large brim 12b is used as a reference, and the crowning center is determined from the end surface position k2. Define the distance Z to c1.

  In the tapered roller bearing 10 of the present embodiment described above, the outer ring raceway surface 11a and the inner ring raceway surface 12a have a center portion w2, w3 having an arc curve A, and both end portions v2, v3 having an arc curve and a logarithmic curve. Arc logarithmic crowning, which is a generatrix of the arc logarithmic curve formed by the composite curve C, is applied, and a large drop amount necessary for preventing the occurrence of edge load under a high load is applied to the crowning end, for example. Can be set.

The tapered roller bearing 10 can be separated into an outer ring (CUP) 11 and other parts (CONE = a semi-assembled body in which a plurality of tapered rollers 13 and a cage 14 are assembled to the inner ring 12). In the assembled state assembled on the 12 side, the effective crowning lengths s2 and s3 of the raceway surfaces 11a and 12a to which the arc log crowning is applied are regulated so that the arc log crowning is within the rolling surface 13a of the tapered roller 13. For example, when a heavy load is applied, the crowning end portion having a large drop amount is surely brought into contact with the rolling surface 13a of the tapered roller 13 to effectively function to prevent the occurrence of an edge load at the crowning end portion. it can.
That is, the large drop amount set at the crowning end portion by the crowning bus shape using the logarithmic curve can be effectively utilized as expected.

Further, in the crowning applied to the outer ring raceway surface 11a or the inner ring raceway surface 12a in the present invention, the center part is an arc curve and the end part is an arc curve with respect to the range of the effective crowning length le that secures the required drop amount H. Compared to the case of a conventional roller bearing with a crowned linear shape at the center, since it is a logarithmic logarithmic crown that is a composite curve with a logarithmic curve, there is no peak in the joint between the center and the end. It is possible to form a joint, and it is possible to prevent the occurrence of a contact pressure peak at the joint. 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, the generation of edge load can be prevented when a high load is applied to the bearing, and further, the bearing life can be prevented from being reduced under light load to medium load conditions.

Furthermore, in order to confirm the operation and effect of the above-described embodiment, performance comparison was performed on the first and second examples, which are specific examples of the above-described embodiment, and the conventional product.
FIG. 6 is a measurement comparison diagram of radial stiffness characteristics in the first embodiment of the present invention and the conventional product, and FIG. 7 is a measurement comparison diagram of axial stiffness characteristics in the first embodiment of the present invention and the conventional product.

The characteristic polarities f1 and f2 shown in FIGS. 6 and 7 are for the developed product which is the tapered roller bearing of the first embodiment of the present invention, and the characteristic curves g1 and g2 are for the conventional product.
In FIG. 6, the displacement (μm) in the radial direction when a predetermined radial load is applied is measured and compared. In FIG. 7, the displacement (μm) in the axial direction when a predetermined axial load is applied is shown. It is measured.

Each of the first example and the conventional product in which the characteristic measurement of FIGS. 6 and 7 is performed is a tapered roller bearing having an inner diameter of 50 mm, an outer diameter of 100 mm, and a width of 25 mm.
The conventional tapered roller bearing has the same inner diameter, outer diameter, and width as in the first embodiment, but the crowning applied to the raceway surface of the inner and outer rings is straight at the center and logarithmic at the end. The crowning shape consists of a combination curve, and the effective crowning length of the inner and outer ring raceway surfaces is larger than the rolling surface of the tapered roller, so that the crowning end on the raceway surface deviates from the rolling surface of the tapered roller. It has become.

  It can be confirmed that the tapered roller bearing of the first embodiment of the present invention has less displacement than the conventional product for both radial load and axial load, and is rigid in both radial direction and axial direction. Was confirmed to be improved.

  FIG. 8 is a measurement comparison diagram of the durability test between the second embodiment of the present invention and the conventional product under a medium load condition, and FIG. 9 is a diagram under a high load condition of the second embodiment of the present invention and the conventional product. It is a measurement comparison figure of a durability test.

Characteristic polarities f3 and f4 shown in FIGS. 8 and 9 are for the developed product which is a tapered roller bearing of the second embodiment of the present invention, and characteristic curves g3 and g4 are for the conventional product.
FIG. 8 is a durability comparison in operation in a medium load region corresponding to a load of 0.4 Cr, and FIG. 9 is a durability comparison in operation in a high load region corresponding to a load of 1.6 Cr.

Each of the second embodiment and the conventional product in which the characteristic measurement of FIGS. 8 and 9 is performed is a tapered roller bearing having an inner diameter of 65 mm, an outer diameter of 105 mm, and a width of 18 mm.
The conventional tapered roller bearing has the same inner diameter, outer diameter, and width as in the first embodiment, but the crowning applied to the raceway surface of the inner and outer rings is straight at the center and logarithmic at the end. The crowning shape consists of a combination curve, and the effective crowning length of the inner and outer ring raceway surfaces is larger than the rolling surface of the tapered roller, so that the crowning end on the raceway surface deviates from the rolling surface of the tapered roller. It has become.

As shown in FIG. 8, in the case of operation in the middle load region, it was confirmed that the life of the second embodiment of the present invention was extended 1.35 times compared to the conventional product. . In addition, as shown in FIG. 9, in the case of operation in a high load region, it can be confirmed that the life of the second embodiment of the present invention is extended by 10 times compared to the conventional product. It was.
That is, in the examples of the present invention, it was confirmed that the life was improved in both the medium load region and the high load region, and it was confirmed that the crowning functioned effectively and the bearing performance was improved.

  In the above embodiment, both the outer ring raceway surface and the inner ring raceway surface are subjected to the arc logarithmic crowning based on the above formula (1), but the above formula is applied only to either the outer ring raceway surface or the inner ring raceway surface. Arc logarithmic crowning based on (1) may be applied.

It is a longitudinal cross-sectional view of one embodiment of the tapered roller bearing according to the present invention. It is explanatory drawing of the synthetic | combination curve of the circular arc curve and logarithmic curve which comprise the circular arc log crowning shape given to the track surface of an inner and outer ring. It is explanatory drawing of the crowning center of the logarithmic logarithmic shape given to the track surface of the inner and outer rings. It is explanatory drawing of the position of the crowning edge part controlled by the circular arc logarithmic crown shape given to the track surface of an outer ring. It is explanatory drawing of the position of the crowning edge part regulated by the circular arc logarithmic crown shape given to the track surface of an inner ring. It is a measurement comparison figure of the radial rigidity characteristic in the 1st example and a conventional product. It is a measurement comparison figure of the axial rigidity characteristic in the 1st example and a conventional product. It is a measurement comparison figure of the durability test under medium load conditions in the 2nd example and a conventional product. It is a measurement comparison figure of the durability test under high load conditions in a 2nd example and a conventional product.

Explanation of symbols

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 l _e , s2, s3 Effective crowning length (effective raceway length)
v2, v3 end w2, w3 center

Claims (2)

An outer ring having an outer ring raceway surface formed on the inner peripheral surface, an inner ring having an outer ring raceway surface formed on the outer peripheral surface, and a plurality of cones disposed between the outer ring raceway surface and the inner ring raceway surface so as to be freely rollable. A tapered roller bearing comprising rollers,
The rolling surface of the tapered roller is crowned by an arc curve,
At least one of the outer ring raceway surface and the inner ring raceway surface is subjected to arc logarithmic crowning that forms a generatrix of an arc logarithmic curve composed of a circular curve at the center and a combined curve of the arc curve and logarithm at both ends,
In addition, the effective crowning length of the raceway surface to which the arc logarithmic crowning is applied is restricted to be shorter than the length of the rolling surface of the tapered roller so that the arc logarithmic crowning is within the rolling surface of the tapered roller. Tapered roller bearings characterized by The tapered roller bearing according to claim 1, 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 × (l _e / 2)
End length L ₂ : L ₂ = (l _e / 2) −L ₁
Central arc radius R: R = (D ₁ ² + L ₁ ² ) / (2 × D ₁ )
x: coordinates with the origin at the center l _e : effective crowning length (effective trajectory length)
r ₁ : ratio of center length to effective crowning length (2L ₁ / l _e )
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)

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