JP6882915B2 - Tapered roller bearing - Google Patents

Description

The present invention relates to tapered roller bearings.

With recent efforts to reduce fuel consumption, bearings are becoming smaller in automobile transmissions and differentials. Along with this, the space allowed for bearings has become smaller, and it has become necessary for small bearings to receive high loads. Further, the adoption of the aluminum housing reduces the rigidity of the case included in the bearing and increases the axial inclination, so that the bearing is required to have durability even in a highly misaligned environment. Due to the above background, there are an increasing number of cases where tapered roller bearings, which are small bearings but can receive a large load including misalignment, are used.

As a part of such fuel saving, for example, in the bearing parts disclosed in Japanese Patent Application Laid-Open No. 2009-197904 (Patent Document 1), it has been proposed to obtain a crowning contour line represented by a logarithmic function. .. Further, for example, in Japanese Patent Application Laid-Open No. 2003-226918 (Patent Document 2), in order to extend the life, a nitride layer refined by a special heat treatment called FA treatment (crystal grain refinement strengthening treatment) is included. Bearing parts having such a configuration are disclosed.

JP-A-2009-197904 Japanese Unexamined Patent Publication No. 2003-226918

However, since a configuration having both a crowning contour line represented by a logarithmic function and a miniaturized nitrided layer by FA processing has not been proposed so far, it cannot be said that the contribution to fuel efficiency of automobiles is sufficient. It was.

Further, it is known that the torque loss of the conical roller bearing increases due to the increase of the lubricating oil flowing from the inner diameter side of the cage to the inner ring side. For this reason, it is necessary to further reduce fuel consumption and torque loss by making the structure in which the lubricating oil flowing from the inner diameter side of the cage to the inner ring side quickly escapes from the notch to the outer ring side on the outer diameter side. ..

Therefore, an object of the present invention is to provide a conical roller bearing which can reduce torque loss during use and can further extend the service life and improve durability.

The conical roller bearing according to the present invention includes an outer ring, an inner ring, a plurality of conical rollers, and a cage. The outer ring has an outer ring raceway surface on the inner peripheral surface. The inner ring has an inner ring raceway surface on the outer peripheral surface, and is arranged radially inward with respect to the outer ring. The plurality of conical rollers are arranged between the outer ring raceway surface and the inner ring raceway surface, and have a rolling surface that contacts the outer ring raceway surface and the inner ring raceway surface. The cage includes a plurality of pockets arranged at predetermined intervals in the circumferential direction, and each of the plurality of conical rollers is housed and held in each of the plurality of pockets. The cage includes a small annular portion connected on the small-diameter end face side of the conical roller, a macrocyclic portion connected on the large-diameter end face side of the conical roller, and a plurality of pillar portions connecting these annular portions. The pocket is formed in a trapezoidal shape in which the portion for accommodating the small diameter side of the conical roller is on the narrow side and the portion accommodating the large diameter side is on the wide side. A notch is provided in the narrow pillar portion of the pocket of the cage so as to have a width from the boundary between the small annular portion and the pillar portion toward the large annular portion, so that the inflow flows from the inner diameter side of the cage to the inner ring side. The lubricating oil to be used is quickly escaped from the notch to the outer ring side on the outer diameter side, and the pocket-side edge of the small annular portion has a shape in which the bottom portion on the narrow side of the pocket extends to the pillar portion. At least one of the outer ring, the inner ring and the plurality of conical rollers includes a nitrogen-enriched layer formed on the surface layer of the outer ring raceway surface, the inner ring raceway surface or the rolling surface. The distance from the outermost surface of the surface layer to the bottom of the nitrogen-enriched layer is 0.2 mm or more. Crowning is formed on the rolling surface of the conical roller. The sum of the drop amount of the crowning is a generatrix of the rolling surface of the tapered rollers and y-axis, the generatrix orthogonal direction in y-z coordinate system with the z-axis, K _{1, K 2,} z _m design parameters, the Q Load, L is the length of the effective contact part of the rolling surface of the conical roller in the generatrix direction, E'is the equivalent elastic coefficient, and a is from the origin on the generatrix of the rolling surface of the conical roller to the end of the effective contact part. When the length of A = 2K ₁ Q / πLE', it is expressed by the equation (1).

According to the present invention, the torque loss during use can be reduced by allowing the lubricating oil flowing from the inner diameter side of the cage to the inner ring side to quickly escape from the notch to the outer ring side on the outer diameter side. Conical roller bearings can be provided. Further, it is possible to provide a conical roller bearing which can further extend the life and improve the durability.

It is the schematic sectional drawing which shows the rough structure of the conical roller bearing which concerns on this embodiment. It is an enlarged sectional view of the main part of the conical roller bearing shown in FIG. It is a partial cross-sectional schematic diagram of the conical roller of the conical roller bearing shown in FIG. It is a schematic cross-sectional view of the enlarged partial of the conical roller shown in FIG. It is a yz coordinate diagram which shows an example of a crowning shape. It is a schematic diagram which illustrated the microstructure of a bearing part, especially the former austenite grain boundary. It is a figure which shows the time when the crowning which the contour line is represented by a logarithmic function is provided. It is the figure which superposed the contour line of the roller which provided the crowning and the straight part of a partial arc, and the contact surface pressure on the rolling surface of a roller. It is schematic cross-sectional view which shows in more detail than FIG. 1 in order to define the large flange surface and the small flange surface of the conical roller bearing of this embodiment. It is an enlarged sectional view of the main part of FIG. It is a development plan view of the cage of the conical roller bearing which concerns on this embodiment. It is the schematic cross-sectional view which shows in more detail than FIG. 1 in order to define the large collar, the small collar and the relief part of the conical roller bearing of this embodiment. It is a figure which shows the crowning shape of the conical roller bearing of FIG. It is a figure which shows the relationship between the generatrix direction coordinate of the conical roller of FIG. 12 and the drop amount. It is a figure which shows the relationship between the maximum value of the equivalent stress of Mises, and the logarithmic crowning parameter. It is a figure which shows the crowning shape of the conical roller included in the conical roller bearing which concerns on the 1st modification with respect to FIG. It is a figure which shows the crowning shape of the conical roller included in the conical roller bearing which concerns on the 2nd modification with respect to FIG. It is a flowchart for demonstrating the manufacturing method of a conical roller bearing. It is a schematic diagram which shows the heat treatment pattern in the heat treatment process of FIG. It is a schematic diagram which shows the modification of the heat treatment pattern shown in FIG. It is a schematic diagram which illustrated the microstructure of the bearing component as a comparative example, especially the former austenite grain boundary. It is a developed plan view of the cage of the conical roller bearing of this embodiment, which is different from FIG. It is a developed plan view of the modification of the cage of the conical roller bearing of this embodiment. It is a vertical cross-sectional view which shows the differential which includes the conical roller bearing which concerns on this embodiment. It is a vertical sectional view which shows the transmission which comprises the conical roller bearing which concerns on this embodiment. It is sectional drawing which shows the flow of the lubricating oil into the bearing of the conical roller bearing in FIG. 24. It is a graph which shows the result of the torque measurement test.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Hereinafter, the conical roller bearing of the present embodiment will be described step by step with reference to FIG. 1 and FIG. 9 described later. First, with reference to FIGS. 1 to 4, the features of the portion of the conical roller bearing of the present embodiment, excluding the features first appearing in FIG. 9, which will be described later, will be described.

The conical roller bearing 10 shown in FIG. 1 mainly includes an outer ring 11, an inner ring 13, a roller 12 as a plurality of conical rollers, and a cage 14. The outer ring 11 has a ring shape, and has a raceway surface 11A as an outer ring raceway surface on the inner peripheral surface. The inner ring 13 has a ring shape, and has a raceway surface 13A as an inner ring raceway surface on the outer peripheral surface. The inner ring 13 is arranged on the inner diameter side of the outer ring 11 so that the raceway surface 13A faces the raceway surface 11A. In the following description, the direction along the central axis of the conical roller bearing 10 is the "axial direction", the direction orthogonal to the central axis is the "diameter direction", and the direction along the arc centered on the central axis is the "circumferential direction". ".

The rollers 12 are arranged on the inner peripheral surface of the outer ring 11. The roller 12 has a rolling surface 12A as a roller rolling surface, and is in contact with the raceway surface 13A and the raceway surface 11A on the rolling surface 12A. The plurality of rollers 12 are arranged at a predetermined pitch in the circumferential direction by a cage 14 made of synthetic resin. As a result, the roller 12 is rotatably held on the annular orbit of the outer ring 11 and the inner ring 13. Further, in the conical roller bearing 10, each apex of the cone including the raceway surface 11A, the cone including the raceway surface 13A, and the cone including the locus of the rotation axis when the roller 12 rolls is one point on the center line of the bearing. It is configured to intersect at. With such a configuration, the outer ring 11 and the inner ring 13 of the conical roller bearing 10 can rotate relative to each other. The cage 14 is not limited to the resin, and may be made of metal.

The material constituting the outer ring 11, the inner ring 13, and the roller 12 may be steel. The steel has at least 0.6% by mass or more and 1.2% by mass or less of carbon, 0.15% by mass or more and 1.1% by mass or less of silicon, and manganese in parts other than the nitrogen-enriched layers 11B, 12B, and 13B. Is included in an amount of 0.3% by mass or more and 1.5% by mass or less. The steel may further contain 2.0% by mass or less of chromium.

In the above configuration, if carbon exceeds 1.2% by mass, the material hardness is high even if spheroidizing annealing is performed, which hinders cold workability, and a sufficient amount of cold work is performed when cold work is performed. , Processing accuracy cannot be obtained. In addition, the carburized nitriding treatment tends to cause an over-carburized structure, and there is a risk that the crack strength is lowered. On the other hand, when the carbon content is less than 0.6% by mass, it takes a long time to secure the required surface hardness and the amount of retained austenite, or the internal hardness required for quenching after reheating is obtained. It becomes difficult to get rid of.

The reason why the Si content is 0.15 to 1.1% by mass is that Si can increase tempering resistance and softening resistance to ensure heat resistance and improve rolling fatigue life characteristics under lubrication mixed with foreign matter. Is. If the Si content is less than 0.15% by mass, the rolling fatigue life characteristics under lubrication with foreign substances are not improved, while if the Si content exceeds 1.1% by mass, the hardness after normalizing becomes too high. Inhibits cold workability.

Mn is effective in ensuring the quench hardening ability of the carburized nitride layer and the core portion. If the Mn content is less than 0.3% by mass, sufficient quenching and curing ability cannot be obtained, and sufficient strength cannot be secured in the core portion. On the other hand, when the Mn content exceeds 1.5% by mass, the curing ability becomes excessive, the hardness after normalizing becomes high, and the cold workability is impaired. In addition, it stabilizes austenite too much and excessively increases the amount of retained austenite in the core portion, which promotes dimensional change over time. Further, when the steel contains 2.0% by mass or less of chromium, carbides and nitrides of chromium are precipitated in the surface layer portion, and the hardness of the surface layer portion can be easily improved. The reason why the Cr content is 2.0% by mass or less is that the cold workability is remarkably lowered when it exceeds 2.0% by mass, and the hardness of the surface layer portion is determined even if it is contained in excess of 2.0% by mass. This is because the effect of improvement is small.

Needless to say, the steel of the present disclosure contains Fe as a main component and may contain unavoidable impurities in addition to the above elements. Inevitable impurities include phosphorus (P), sulfur (S), nitrogen (N), oxygen (O), aluminum (Al) and the like. The amount of each of these unavoidable impurity elements is 0.1% by mass or less.

From a different point of view, the outer ring 11 and the inner ring 13 are preferably made of a steel material which is an example of a bearing material, for example, JIS standard SUJ2. The roller 12 may be made of a steel material which is an example of a bearing material, for example, JIS standard SUJ2. Further, the roller 12 may be made of another material, for example, a Sialon sintered body.

As shown in FIG. 2, nitrogen-enriched layers 11B and 13B are formed on the raceway surface 11A of the outer ring 11 and the raceway surface 13A of the inner ring 13. In the inner ring 13, the nitrogen-enriched layer 13B extends from the raceway surface 13A to the small collar surface and the large flange surface described later. The nitrogen-enriched layers 11B and 13B are regions in which the nitrogen concentration is higher than that of the unnitrided portion 11C of the outer ring 11 or the unnitrided portion 13C of the inner ring 13, respectively. Further, a nitrogen-enriched layer 12B is formed on the surface of the roller 12 including the rolling surface 12A. The nitrogen-enriched layer 12B of the roller 12 is a region where the nitrogen concentration is higher than that of the unnitrided portion 12C of the roller 12. The nitrogen-enriched layers 11B, 12B, and 13B can be formed by any conventionally known method such as carburizing nitriding treatment and nitriding treatment.

The nitrogen-enriched layer 12B may be formed only on the rollers 12, the nitrogen-enriched layer 11B may be formed only on the outer ring 11, or the nitrogen-enriched layer 13B may be formed only on the inner ring 13. Good. Alternatively, a nitrogen-enriched layer may be formed on two of the outer ring 11, the inner ring 13, and the roller 12.

As shown in FIG. 3, the rolling surfaces 12A (see FIG. 2) of the rollers 12 are located at both ends and are centrally connected between the crowning portions 22 and 24 on which the crowning is formed and the crowning portions 22 and 24. Including part 23. No crowning is formed in the central portion 23, and the shape of the central portion 23 in the cross section in the direction along the center line 26, which is the rotation axis of the roller 12, is linear. A chamfered portion 21 is formed between the small end surface 17 which is the left end surface of the roller 12 and the crowning portion 22. A chamfered portion 25 is also formed between the large end surface 16 which is the right end surface and the crowning portion 24.

Here, in the method for producing the roller 12, when the treatment for forming the nitrogen-enriched layer 12B (carburizing nitriding treatment) is performed, the roller 12 is not crowned, and the outer shape of the roller 12 is the dotted line in FIG. The surface is 12E before processing, which is indicated by. After the nitrogen-enriched layer is formed in this state, the side surface of the roller 12 is processed as shown by the arrow in FIG. 4 as a finishing process, and the crowning portion 22 is formed as shown in FIGS. 3 and 4. , 24 is obtained.

The depth of the nitrogen-enriched layer 12B at the roller 12, that is, the distance from the outermost surface of the nitrogen-enriched layer 12B to the bottom of the nitrogen-enriched layer 12B is 0.2 mm or more. Specifically, the first measurement point 31, which is the boundary point between the chamfered portion 21 and the crowning portion 22, the second measuring point 32, which is a position where the distance W is 1.5 mm from the small end surface 17, and the rolling surface of the roller 12. At the third measurement point 33, which is the center of 12A, the depths T1, T2, and T3 of the nitrogen-enriched layer 12B at each position are 0.2 mm or more. Here, the depth of the nitrogen-enriched layer 12B means the thickness of the nitrogen-enriched layer 12B in the radial direction orthogonal to the center line 26 of the rollers 12 and toward the outer peripheral side. The values of the depths T1, T2, and T3 of the nitrogen-enriched layer 12B are set according to the process conditions such as the shape and size of the chamfered portions 21 and 25, the process for forming the nitrogen-enriched layer 12B, and the finishing conditions. It can be changed as appropriate. For example, in the configuration example shown in FIG. 4, the crowning 22A is formed after the nitrogen-enriched layer 12B is formed as described above. Therefore, as shown in FIG. 4, the depth T2 of the nitrogen-enriched layer 12B is smaller than the other depths T1 and T3. However, by changing the process conditions described above, the magnitude relationship between the values of the depths T1, T2, and T3 of the nitrogen-enriched layer 12B can be appropriately changed.

Further, regarding the nitrogen-enriched layers 11B and 13B in the outer ring 11 and the inner ring 13, the thickness of the nitrogen-enriched layers 11B and 13B, which is the distance from the outermost surface to the bottom of the nitrogen-enriched layers 11B and 13B, is 0.2 mm. That is all. Here, the thicknesses of the nitrogen-enriched layers 11B and 13B mean the distances to the nitrogen-enriched layers 11B and 13B in the direction perpendicular to the outermost surfaces of the nitrogen-enriched layers 11B and 13B.

The shape of the crowning formed on the crowning portions 22 and 24 of the roller 12 is defined as follows. _{That is, the sum of the crowning drop amounts has K 1} , K ₂ , and z _m as design parameters in the y-z coordinate system in which the bus of the rolling surface 12A of the roller 12 is the y-axis and the direction orthogonal to the bus is the z-axis. , Q is the load, L is the length of the effective contact portion of the rolling surface 12A on the roller 12 in the direction of the bus, E'is the equivalent elastic modulus, and a is the effective contact part from the origin taken on the bus of the rolling surface of the roller 12. When the length to the end of is A = 2K ₁ Q / πLE', it is expressed by the following equation (1).

In FIG. 5, the generatrix of the roller 12 is set as the y-axis, the origin O is set at the center of the effective contact portion of the inner ring 13 or the outer ring 11 and 12 on the generatrix of the roller 12, and the origin O is set in the direction orthogonal to the bus (radial direction). An example of crowning represented by the above equation (1) is shown in the yz coordinate system taking the z-axis. In FIG. 5, the vertical axis is the z-axis and the horizontal axis is the y-axis. The effective contact portion is a contact portion with the inner ring 13 or the outer ring 11 and 12 when no crowning is formed on the rollers 12. Further, since each crowning of the plurality of rollers 12 constituting the conical roller bearing 10 is usually formed line-symmetrically with respect to the z-axis passing through the central portion of the effective contact portion, only one crowning 22A is shown in FIG. ing.

The load Q, the length L of the effective contact portion in the generatrix direction, and the equivalent elastic modulus E'are given as design conditions, and the length a from the origin to the end of the effective contact portion is a value determined by the position of the origin. Is.

In the above equation (1), z (y) indicates the drop amount of the crowning 22A at the position y in the generatrix direction of the roller 12, and the coordinates of the starting point O1 of the crowning 22A are (a-K ₂ a, 0). Therefore, the range of y in the equation (1) is y> (a-K ₂ a). Further, in FIG. 5, since the origin O is located at the center of the effective contact portion, a = L / 2. Further, since the region from the origin O to the start point O1 of the crowning 22A is the central portion (straight portion) where the crowning is not formed, when 0 ≦ y ≦ (a−K ₂ a), z (y) = It becomes 0.

The design parameter K ₁ means the magnification of the load Q, and geometrically, the degree of curvature of the crowning 22A. The design parameter K ₂ means the ratio of the generatrix length ym of the crowning 22A to the generatrix length a from the origin O to the end of the effective contact portion (K ₂ = ym / a). Design parameters z _m is meant the maximum drop amount of drop amount, i.e. crowning 22A at the end of the effective contact portion.

Here, the crowning at the time shown in FIG. 7, which will be described later, is a full climbing with a design parameter K ₂ = 1 and no straight portion, and a sufficient drop amount is secured so that edge load does not occur. However, if the amount of drop is excessive, the removal allowance generated from the material taken during processing becomes large, which leads to an increase in cost. Therefore, the design parameters K ₁ , K ₂ , and z _m of the equation (1) are optimized as follows.

Various methods can be adopted as the optimization method for the design parameters K ₁ , K ₂ , z _m , and for example, a direct search method such as the Rosenblock method can be adopted. Here, since the damage of the surface starting point on the rolling surface of the roller depends on the surface pressure, by setting the objective function of the optimization as the surface pressure, it is possible to obtain crowning that prevents the oil film on the contact surface from running out under dilute lubrication. Can be done.

Further, when logarithmic crowning is applied to the rollers, it is preferable to provide a straight portion (central portion 23) at the central portion of the rolling surface in order to ensure the machining accuracy of the rollers. In this case, K ₂ may be set to a constant value, and K ₁ and z _m may be optimized.

FIG. 6 shows the microstructure in the nitrogen-enriched layer 12B. The particle size of the old austenite crystal in the nitrogen-enriched layer 12B in the present embodiment has a particle size number of JIS standard of 10 or more, which is sufficiently finer than that of a conventional general hardened product.

Here, a method for measuring the nitrogen concentration will be described. For bearing parts such as the outer ring 11, roller 12, and inner ring 13, the cross section perpendicular to the surface of the region where the nitrogen-enriched layers 11B, 12B, and 13B are formed is lined in the depth direction by EPMA (Electron Probe Micro Analysis), respectively. Perform analysis. In the measurement, each bearing component is cut from the measurement position in the direction perpendicular to the surface to expose the cut surface, and the measurement is performed on the cut surface. For example, with respect to the roller 12, the cut surface is exposed by cutting the roller 12 in the direction perpendicular to the center line 26 from each position of the first measurement point 31 to the third measurement point 33 shown in FIG. The nitrogen concentration is analyzed by the EPMA at a plurality of measurement positions located 0.05 mm inward from the surface of the roller 12 on the cut surface. For example, the measurement positions are determined at five locations, and the average value of the measurement data at the five locations is defined as the nitrogen concentration of the roller 12.

Regarding the outer ring 11 and the inner ring 13, after exposing the central axis and the cross section along the radial direction orthogonal to the central axis with the central portion in the central axis direction of the bearing as the measurement position on the raceway surfaces 11A and 13A, The nitrogen concentration of the cross section is measured by the same method as described above.

How to measure the distance from the outermost surface to the bottom of the nitrogen-enriched layer:
For the outer ring 11 and the inner ring 13, the hardness distribution of the cross section to be measured in the above nitrogen concentration measuring method is measured in the depth direction from the surface. A Vickers hardness measuring machine can be used as the measuring device. In the cone roller bearing 10 after tempering at 500 ° C. × 1 h, hardness measurement is performed at a plurality of measurement points arranged in the depth direction, for example, measurement points arranged at intervals of 0.5 mm. Then, a region having a Vickers hardness of HV450 or higher is designated as a nitrogen-enriched layer.

Regarding the roller 12, in the cross section at the first measurement point 31 shown in FIG. 3, the hardness distribution in the depth direction is measured as described above, and the region of the nitrogen-enriched layer is determined.

As the method for measuring the crystal grain size of the former austenite, the method specified in JIS standard G0551: 2013 is used. The cross section to be measured shall be the cross section measured by the method for measuring the distance to the bottom of the nitrogen-enriched layer. This makes it possible to measure the particle size number of the old austenite crystal.

The crowning shape of the roller 12 can be measured by any method. For example, the crowning shape may be measured by measuring the shape of the roller 12 with a surface texture measuring machine.

As described above, the nitrogen-enriched layers 11B, 12B, and 13B having sufficiently finely divided old austenite crystal grain size are formed in at least one of the outer ring 11, the inner ring 13, and the roller 12 as a conical roller. Therefore, it is possible to improve the Charpy impact value, fracture toughness value, crush strength, etc. while having a high rolling fatigue life.

Further, since the rolling surface 12A of the roller 12 is provided with crowning (so-called logarithmic crowning) in which the contour line is represented by a logarithmic function so that the sum of the drop amounts is represented by the above equation (1), it is conventional. It is possible to suppress a local increase in surface pressure and suppress the occurrence of wear on the rolling surface 12A of the roller 12 as compared with the case where the crowning represented by the partial arc is formed.

Here, the effect of the logarithmic crowning described above will be described in more detail. FIG. 7 is a diagram showing the contour line of the roller provided with crowning whose contour line is represented by a logarithmic function and the contact surface pressure on the rolling surface of the roller in an overlapping manner. FIG. 8 is a diagram showing the contour line of a roller having an auxiliary arc between the crowning of the partial arc and the straight portion and the contact surface pressure on the rolling surface of the roller. The vertical axis on the left side of FIGS. 7 and 8 indicates the amount of crowning drop (unit: mm). The horizontal axis of FIGS. 7 and 8 indicates the axial position (unit: mm) of the roller. The vertical axis on the right side of FIGS. 7 and 8 shows the contact surface pressure (unit: GPa).

When the contour line of the rolling surface of the conical roller is formed into a shape having a crowning of a partial arc and a straight portion, as shown in FIG. 8, the gradient at the boundary between the straight portion, the auxiliary arc, and the crowning is continuous. However, if the curvature is discontinuous, the contact surface pressure will increase locally. Therefore, there is a risk of oil film running out and surface damage. If a lubricating film having a sufficient film thickness is not formed, wear due to metal contact is likely to occur. When the contact surface is partially worn, metal contact is more likely to occur in the vicinity thereof, so that the contact surface is worn more and the conical roller is damaged.

Therefore, when the rolling surface of the conical roller as the contact surface is provided with a crowning whose contour line is represented by a logarithmic function, for example, as shown in FIG. 7, a crowning represented by a partial arc of FIG. 8 is provided. The local surface pressure is lower than in the case, and the contact surface can be less likely to be worn. Therefore, even when the thickness of the lubricating film becomes thin due to a small amount of lubricant existing on the rolling surface of the conical roller or a decrease in viscosity, wear of the contact surface is prevented and damage to the conical roller is prevented. Can be done. In FIGS. 7 and 8, the origin O of the horizontal axis is located at the center of the effective contact portion of the inner ring or the outer ring in the Cartesian coordinate system in which the direction of the generatrix of the roller is the horizontal axis and the direction perpendicular to the generatrix is the vertical axis. Is set to show the outline of the roller, and the contact surface pressure is also shown with the surface pressure as the vertical axis. As described above, by adopting the above-described configuration, the conical roller bearing 10 exhibiting a long life and high durability can be realized.

In the conical roller bearing 10, the nitrogen concentration in the nitrogen-enriched layers 11B, 12B, and 13B at a depth of 0.05 mm from the outermost surface is 0.1% by mass or more. In this case, since the nitrogen concentration on the outermost surfaces of the nitrogen-enriched layers 11B, 12B, 13B can be set to a sufficient value, the hardness of the outermost surfaces of the nitrogen-enriched layers 11B, 12B, 13B can be sufficiently increased. Further, it is preferable that the above-mentioned conditions such as the particle size of the old austenite crystal particle size, the distance to the bottom of the nitrogen-enriched layer, and the nitrogen concentration are at least satisfied at the first measurement point 31 in FIG.

In the conical roller bearing 10, at least one of the outer ring 11, the inner ring 13, and the roller 12 on which the nitrogen-enriched layers 11B, 12B, and 13B are formed is made of steel. The steel has at least 0.6% by mass or more and 1.2% by mass or less of carbon (C) and silicon (Si) in the portions other than the nitrogen-enriched layers 11B, 12B and 13B, that is, the unnitrided portions 11C, 12C and 13C. ) Is contained in an amount of 0.15% by mass or more and 1.1% by mass or less, and manganese (Mn) is contained in an amount of 0.3% by mass or more and 1.5% by mass or less. In the tapered roller bearing 10, the steel may further contain 2.0% by mass or less of chromium. In this case, the nitrogen-enriched layers 11B, 12B, and 13B having the configurations specified in the present embodiment can be easily formed by using a heat treatment or the like described later.

In the conical roller bearing 10, _{at least one of the design parameters K 1} , K ₂ , z _m in the above formula (1) uses the contact surface pressure between the roller 12 and the outer ring 11 or the roller 12 and the inner ring 13 as the objective function. Optimized.

The design parameters K ₁ , K ₂ , z _m are determined by optimizing any one of the contact surface pressure, stress, and life as an objective function, and the damage at the surface origin depends on the contact surface pressure. Here, according to the above embodiment, since the design parameters K ₁ , K ₂ , and z _m are set by optimizing the contact surface pressure as an objective function, wear of the contact surface is prevented even under conditions where the lubricant is lean. You can get the crowning you can.

In the conical roller bearing 10, at least one of the outer ring 11 and the inner ring 13 includes nitrogen-enriched layers 11B and 13B. In this case, the nitrogen-enriched layers 11B and 13B having a fine crystal structure are formed in at least one of the outer ring 11 and the inner ring 13 to obtain the outer ring 11 or the inner ring 13 having a long life and high durability. be able to.

In the conical roller bearing 10, the roller 12 includes a nitrogen-enriched layer 12B. In this case, by forming the nitrogen-enriched layer 12B having a fine crystal structure on the rollers 12, the rollers 12 having a long life and high durability can be obtained.

FIG. 9 is shown as a mode having features closer to the present embodiment on the premise of the basic configuration of FIG. With reference to FIG. 9, the conical roller bearing 10 of the present embodiment is provided with a large collar surface 18 on the large diameter side of the raceway surface 13A of the inner ring 13 and a small collar surface 19 on the small diameter side. A large end surface 16 that contacts the large collar surface 18 is provided on the large diameter side of the roller 12, and a small end surface 17 that contacts the small collar surface 19 is provided on the small diameter side of the roller 12.

The large flange surface 18 is formed via a large-diameter side end portion of the raceway surface 13A and a ground portion. The large flange surface 18 guides the roller 12 by coming into contact with the large end surface 16 of the roller 12 when the conical roller bearing 10 is used. The small flange surface 19 is formed via a small diameter side end portion of the raceway surface 13A and a ground portion.

Further, as shown enlarged in FIG. 10, the small flange surface 19 of the inner ring 13 is finished to be a ground surface parallel to the small end surface 17 of the roller 12, and the roller 12 is in the initial assembled state shown by the alternate long and short dash line in the drawing. Is in surface contact with the small end surface 17 of the above. The small end surface 17 has a gap between the small end surface 17 and the small flange surface 19 of the roller 12. The small flange surface 19 of the inner ring 13 is formed in a state where the roller 12 shown by the solid line is settled in a normal position, that is, in a state where the large end surface 16 of the roller 12 is in contact with the large flange surface 18 of the inner ring 13. The gap δ with the small end surface 17 is within the dimensional regulation range of δ ≦ 0.4 mm. As a result, the number of rotations required for the roller 12 to settle in the normal position during the break-in operation can be reduced, and the break-in operation time can be shortened.

As shown in FIG. 11, the cage 14 has a small annular portion 106 connected on the small-diameter end face side of the roller 12, a large annular portion 107 connected on the large-diameter end face side of the roller 12, and these small annular portions 106. A trapezoidal pocket 109 is formed, which is composed of a plurality of pillars 108 connecting the annular portions 107, and the portion for accommodating the small diameter side of the roller 12 is the narrow side and the portion for accommodating the large diameter side is the wide side. There is. The pockets 109 are arranged at predetermined intervals in the circumferential direction of the conical roller bearing 10. Further, the cage 14 accommodates and holds each of the plurality of rollers 12 in each of the plurality of pockets 109. Two notches 110a and 110b are provided on the pillar portions 108 on both sides of the pocket 109 on the narrow side and the wide side, respectively, and the dimensions of the notches 110a and 110b are 1.0 mm in depth. , The width is 4.6 mm.

The inner diameter side of the cage 14 is provided by providing a notch in the pillar portion on the narrow side of the pocket 109 of the cage 14 so as to have a width from the boundary between the small annular portion 106 and the pillar portion toward the macrocyclic portion 107. Lubricating oil flowing from the inner ring side to the inner ring side is quickly escaped from the notch to the outer ring side on the outer diameter side, and the edge of the small annular portion 106 on the pocket 109 side is extended to the pillar portion on the narrow side of the pocket 109. It has an extended shape.

Summarizing the above, for example, the conical roller bearing 10 of the present embodiment shown in FIG. 9 includes an outer ring 11, an inner ring 13, and a plurality of rollers 12. The outer ring 11 has a raceway surface 11A on the inner peripheral surface. The inner ring 13 has a raceway surface 13A on the outer peripheral surface, and is arranged radially inward with respect to the outer ring 11. The plurality of rollers 12 are arranged between the raceway surface 11A and the raceway surface 13A, and have a rolling surface 12A in contact with the raceway surface 11A and the raceway surface 13A. The cage 14 includes a plurality of pockets 109 arranged at predetermined intervals in the circumferential direction, and each of the plurality of rollers 12 is accommodated and held in each of the plurality of pockets 109. The cage 14 includes a small annular portion 106 connected on the small-diameter end face side of the roller 12, a large annular portion 107 connected on the large-diameter end face side of the roller 12, and a plurality of pillar portions 108 connecting these annular portions 106, 107. including. The pocket 109 is formed in a trapezoidal shape in which the portion for accommodating the small diameter side of the roller 12 is on the narrow side and the portion for accommodating the large diameter side is on the wide side. The notches 110a and 110b are provided in the narrow pillar portion 108 of the pocket 109 of the cage 14 so as to have a width from the boundary between the small annular portion 106 and the pillar portion 108 toward the large annular portion 107 to hold the cage. Lubricating oil flowing from the inner diameter side of the vessel 14 to the inner ring 13 side is made to quickly escape from the notches 110a and 110b to the outer ring 11 side on the outer diameter side, and the edge of the small annular portion 106 on the pocket 109 side is formed on the pocket 109. The shape is such that the bottom portion on the narrow width side extends to the pillar portion 108. At least one of the outer ring 11, the inner ring 13, and the plurality of rollers 12 includes nitrogen-enriched layers 11B, 12B, 13B formed on the surface layer of the raceway surface 11A, the raceway surface 13A, or the rolling surface 12A. .. The distance from the outermost surface of the surface layer to the bottom of the nitrogen-enriched layers 11B, 12B, 13B is 0.2 mm or more. Crowning portions 22 and 24 are formed on the rolling surface 12A of the roller 12. _{For the sum of the drop amounts of the crowning portions 22 and 24, K 1} , K ₂ , and z _m are designed in the y-z coordinate system in which the generatrix of the rolling surface of the conical roller is the y-axis and the generatrix orthogonal direction is the z-axis. Parameters, Q is the load, L is the length of the effective contact part of the rolling surface of the conical roller in the generatrix direction, E'is the equivalent elastic coefficient, and a is the effective contact part from the origin taken on the generatrix of the rolling surface of the conical roller. When the length to the end of is A = 2K ₁ Q / πLE', it is expressed by the above equation (1). Both the above description and the following description are based on the premise that the conical roller bearing 10 of the present embodiment has the characteristics described above in this paragraph.

The conical roller bearing used for the part where the lubricating oil flows in from the outside is provided with a notch in the pocket of the cage, and the notch is provided so that the lubricating oil that flows in separately on the outer diameter side and the inner diameter side of the cage is provided. Some of them are designed to pass through the bearing to improve the circulation of lubricating oil inside the bearing. However, in a conical roller bearing in which the lubricating oil is divided into the outer diameter side and the inner diameter side of the cage and flows into the bearing, torque loss occurs when the proportion of the lubricating oil flowing from the inner diameter side of the cage to the inner ring side increases. It turned out to be bigger. The reason for this is considered as follows.

That is, since the lubricating oil flowing from the outer diameter side of the cage to the outer ring side has no obstacle on the inner diameter surface of the outer ring, it smoothly passes along the raceway surface to the large diameter side of the conical roller and inside the bearing. However, the lubricating oil that flows from the inner diameter side of the cage to the inner ring side has a large bearing on the outer diameter surface of the inner ring, so when it passes along the raceway surface to the large diameter side of the conical roller. It is blocked by a large diameter and easily stays inside the bearing. Therefore, when the proportion of the lubricating oil flowing from the inner diameter side of the cage to the inner ring side increases, the amount of the lubricating oil staying inside the bearing increases, and this staying lubricating oil becomes a flow resistance against the rotation of the bearing and torques. The loss is expected to increase.

Therefore, in the conical roller bearing 10 according to the first embodiment, the lubricating oil flowing from the inner diameter side of the cage to the inner ring side is supplied by providing a notch in the column portion on the narrow side of the trapezoidal pocket of the cage. On the narrow side of the pocket that houses the small diameter side of the tapered roller, it quickly escapes from the notch to the outer ring side, reducing the amount of lubricating oil that reaches the large collar along the raceway surface of the inner ring, and stays inside the bearing. The amount of lubricating oil has been reduced so that torque loss due to the flow resistance of the lubricating oil can be reduced.

Further, as shown in FIGS. 12 and 13, in the conical roller bearing of the present embodiment, the first grinding relief portion 43 is formed at the corner where the raceway surface 13A and the large collar 41 intersect, and the raceway surface 13A and A second grinding relief portion 44 is formed at a corner with the small collar 42. The raceway surface 13A has a straight bus line extending in the inner ring axis direction. A raceway surface 11A facing the raceway surface 13A is formed on the inner circumference of the outer ring 2 to be without a collar, and the raceway surface 11A has a straight bus line extending in the outer ring axial direction.

As shown in FIGS. 12 and 13, crowning 22A and 22B as the crowning portion 22 and crowning 24A and 24B as the crowning portion 24 are formed on the rolling surface 12A on the outer circumference of the roller 12, and both ends of the roller 12 are formed. The chamfered portions 21 and 25 are provided on the surface. The crowning portions 22 and 24 of the rolling surface 12A can be considered as the crowning forming portions where the crowning is formed. Here, the crowning forming portion is specifically formed as a contact portion crowning portion 27 and a non-contact portion crowning portion 28. Of these, the contact portion crowning portion 27 is in the axial range of the raceway surface 13A and is in contact with the raceway surface 13A. The non-contact portion crowning portion 28 deviates from the axial range of the raceway surface 13A and becomes non-contact with the raceway surface 13A.

The contact portion crowning portion 27 and the non-contact portion crowning portion 28 are lines in which the bus lines extending in the roller axis direction are represented by different functions and are smoothly continuous with each other at the connection point P1. In the vicinity of the connection point P1, the curvature R8 of the generatrix of the non-contact portion crowning portion 28 is set to be smaller than the curvature R7 of the generatrix of the contact portion crowning portion 27. The above-mentioned "smoothly continuous" means that the bus is continuous without forming a corner, and ideally, the generatrix of the contact portion crowning portion 27 and the generatrix of the non-contact portion crowning portion 28 are continuous points with each other. By continuing to have a common tangent, that is, the generatrix is a continuously differentiable function at the continuation point.

According to this configuration, since the crowning portion is formed on the rolling surface 12A on the outer periphery of the roller 12, the grindstone can act on the rolling surface 12A more and more than when the crowning portion is formed only on the raceway surface 13A. Therefore, it is possible to prevent processing defects on the rolling surface 12A. The crowning portions 22 and 24 formed on the rolling surface 12A can reduce the surface pressure and the stress of the contact portion and extend the life of the conical roller bearing 10. Further, in the vicinity of the connection point P1 between the contact portion crowning portion 27 and the non-contact portion crowning portion 28, the curvature R8 of the generatrix of the non-contact portion crowning portion 28 is smaller than the curvature R7 of the generatrix of the contact portion crowning portion 27. Therefore, it is possible to reduce the amount of drops at both ends of the roller 12. Therefore, for example, the grinding amount can be suppressed as compared with the conventional single arc crowning, the processing efficiency of the roller 12 can be improved, and the manufacturing cost can be reduced.

The generatrix of the contact portion crowning portion 27 is formed by a logarithmic curve of logarithmic crowning represented by the following equation.

The contact portion crowning portion 27 represented by the logarithmic crowning can reduce the surface pressure and the stress of the contact portion and extend the life of the conical roller bearing 10.

_{By the way, when the crowning is optimized by using the mathematical optimization method for K 1} and z _m of the above equation (1), the crowning is as shown in the “logarithm” of FIG. 14 under this condition. At this time, the maximum drop amount of crowning of the roller 12 is 69 μm. However, the region G in FIG. 14 is a crowning portion 24B facing the first grinding relief portion 43 and the second grinding relief portion 44 of the inner ring 13 of FIG. 12, and does not come into contact with the inner ring 13. Therefore, the region of G of the roller 12 does not have to be logarithmic crowning, and may be a straight line, an arc, or other function. Even if the region of G of the roller 12 is a straight line, an arc, or another function, the entire roller 12 has the same surface pressure distribution as in the case of logarithmic crowning, and is functionally comparable.

The mathematical optimization method of logarithmic crowning will be described.
By appropriate selection of K _1, z _m in a function expression representing the logarithm crowning can be designed optimal logarithmic crowning.

Crowning is generally designed to reduce the maximum surface pressure or stress at the contact. Here, it is considered that the rolling fatigue life occurs according to the Mises yield condition, and K ₁ and z _m are selected so as to minimize the maximum value of the Mises equivalent stress.

K ₁ , z _m can be selected using an appropriate mathematical optimization method. Various algorithms have been proposed for mathematical optimization methods, and one of them, the direct search method, is capable of performing optimization without using the variable coefficients of the function, and has the purpose. This is useful when functions and variables cannot be directly represented by mathematical formulas. Here, finding the optimal value of K _1, z _m using a Rosenbrock method, which is one of the direct search method.

Under the above conditions, that is, when a radial load of 35% of the basic dynamic load rating acts on the tapered roller bearing, nominal number 30316, and the misalignment is 1/600, the maximum value sMises_max of the equivalent stress of Mises and the logarithmic crowning parameter K ₁ , z _m have the relationship as shown in FIG. If K ₁ , z _{m is given an appropriate initial value and K 1} , z _m is modified according to the rules of the Rosenbrok method, the optimum combination of values in FIG. 15 is reached, and sMises_max becomes the minimum.

As long as the contact between the roller 12 and the inner ring 13 is considered, the crowning in the region G in FIG. 14 may have any shape, but considering the contact with the outer ring 2 and the formability of the grindstone at the time of processing, At the connection point P1 with the logarithmic crowning portion, it is not desirable that the gradient is smaller than the gradient of the logarithmic crowning portion. For the crowning of the region of G, it is not desirable to give a gradient larger than the gradient of the logarithmic crowning portion because the amount of drop increases. That is, it is desirable that the crowning in the region of G and the logarithmic crowning are designed so that the gradients match and are smoothly connected at the connection point P1. In FIG. 14, the case where the crowning of the region G of the roller 12 is a straight line is illustrated by a dotted line, and the case where it is an arc is illustrated by a thick solid line. When the crowning in the region of G is a straight line, the drop amount Dp of the crowning of the roller 12 is, for example, 36 μm. When the crowning in the region of G is an arc, the drop amount Dp of the crowning of the roller 12 is, for example, 40 μm.

The generatrix of the non-contact portion crowning portion 28 may be an arc in either or both of the large diameter side portion and the small diameter side portion. In this case, the drop amount Dp can be reduced as compared with the generatrix of the entire roller rolling surface represented by, for example, a logarithmic curve. Therefore, the amount of grinding can be reduced. As shown in FIG. 16, the generatrix of the non-contact portion crowning portion 28 may be a straight line in either or both of the large-diameter side portion and the small-diameter side portion (in the example of FIG. 16, the large-diameter side). Only the part of is a straight line). In this case, the drop amount Dp can be further reduced as compared with the case where the generatrix of the non-contact portion crowning portion 28 is an arc.

A part or all of the generatrix of the contact portion crowning portion 27 may be represented by the logarithmic crowning represented by the above formula (1). The contact portion crowning portion 27 represented by the logarithmic crowning can reduce the surface pressure and the stress of the contact portion and extend the life of the tapered roller bearing.

As shown in FIG. 17, the generatrix of the contact portion crowning portion 27 is formed by a straight portion 27A (synonymous with the central portion 23 in FIG. 3) formed flat along the roller axis direction and a logarithmic curve of logarithmic crowning. It may be represented by the portion 27B.

In order to ensure the processing accuracy of crowning, it is desirable that the straight portion 27A exists on the outer circumference of the roller 12. Therefore, assuming that the crowning portions 22 and 24 are symmetrical between the small diameter side portion and the large diameter side portion with reference to the center in the roller axial direction, K ₂ among the design parameters in the logarithmic crowning equation (1) is It is fixed and K ₁ and z _m are the objects of design.

Hereinafter, a method for manufacturing a conical roller bearing will be described with reference to FIGS. 18 to 21.
As shown in FIG. 18, first, the parts preparation step (S100) is carried out. In this step (S100), members to be bearing parts such as an outer ring 11, an inner ring 13, a roller 12, and a cage 14 are prepared. Crowning has not yet been formed on the member to be the roller 12, and the surface of the member is the unprocessed surface 12E shown by the dotted line in FIG. Further, the roller 12 is formed so as to have the large end surface 16 and the small end surface 17 as shown in FIG. 9, and the inner ring 13 is formed so as to have the large collar surface 18 and the small collar surface 19 as shown in FIG. ..

Next, the heat treatment step (S200) is carried out. In this step (S200), a predetermined heat treatment is performed in order to control the characteristics of the bearing component. For example, in order to form the nitrogen-enriched layers 11B, 12B, 13B according to the present embodiment in at least one of the outer ring 11, the roller 12, and the inner ring 13, carburizing nitriding treatment or nitriding treatment, quenching treatment, and tempering treatment are performed. Perform processing etc. An example of the heat treatment pattern in this step (S200) is shown in FIG. FIG. 19 shows a heat treatment pattern showing a method of performing primary quenching and secondary quenching. Figure 20 is a material in the course quenching cooled to below the A ₁ transformation point temperature, then, shows a heat treatment pattern reheated shows the final quenching Ru method. In these figures, in the treatment T ₁ , carbon and nitrogen are diffused in the steel substrate, and after the carbon is sufficiently dissolved, the steel base is cooled to less than _{the A 1 transformation point.} Next, in the treatment T ₂ in the figure, the heat is reheated to a lower temperature than the treatment T ₁ , and oil quenching is performed from there. Then, for example, a tempering treatment at a heating temperature of 180 ° C. is carried out.

According to the above heat treatment, the crack strength is improved and the aging dimensional change rate is reduced while carburizing and nitriding the surface layer portion of the bearing component, rather than normal quenching, that is, carburizing and nitriding the bearing component and then quenching once. Can be done. According to the heat treatment step (S200), in the nitrogen-enriched layers 11B, 12B, and 13B having a hardened structure, the particle size of the former austenite crystal grains is compared with the microstructure in the conventional hardened structure shown in FIG. Therefore, it is possible to obtain a microstructure as shown in FIG. 6, which is less than half. The bearing component that has undergone the above heat treatment has a long life against rolling fatigue, can improve crack strength, and can reduce the rate of dimensional change over time.

Next, the processing step (S300) is carried out. In this step (S300), finishing is performed so that the final shape of each bearing component is obtained. As for the roller 12, the crowning 22A and the chamfered portion 21 are formed by machining such as cutting as shown in FIG.

Next, the assembly step (S400) is carried out. In this step (S400), the conical roller bearing 10 shown in FIG. 9 is obtained by assembling the bearing parts prepared as described above. In this way, the conical roller bearing 10 shown in FIG. 1 can be manufactured.

Hereinafter, an example of the cage 14 of the conical roller bearing 10 of the present embodiment, which is different from FIG. 11, will be described with reference to FIG. 22. This has basically the same configuration as the cage 14 of FIG. 11, but the configuration of the notch of the cage 14 is different. As shown in FIG. 22, a notch 110c is also provided in the small annular portion 106 on the narrow side of the pocket 109, and the total area of the three notches 110a and 110c on the narrow side is the two cuts on the wide side. It is larger than the total area of the notch 110b. The notch 110c has a depth of 1.0 mm and a width of 5.7 mm.

In the modified example shown in FIG. 23, the depth of each notch 110a of the pillar portion 108 on the narrow width side is 1.5 mm, which is formed deeper than each notch 110b of the pillar portion 108 on the wide width side, and is formed on the narrow side. The total area of each notch 110a is larger than the total area of each notch 110b on the wide side.

As shown in FIG. 1, a radial inward collar 50 facing the outer diameter surface of the small collar 42 of the inner ring 13 is provided on the outer side of the small annular portion 106 of the cage 14 in the axial direction. As shown in FIG. 26, the gap δ between the inner diameter surface of the collar 50 of the opposed small annular portion 106 and the outer diameter surface of the small collar 42 of the inner ring 13 is 2.0% of the outer diameter dimension of the small collar 42. It is set narrowly below.

Finally, FIGS. 24 and 25 show an example in which the conical roller bearing 10 of the present embodiment is applied to an automobile differential and a transmission. FIG. 24 shows a differential of an automobile using the above-mentioned tapered roller bearing 10. This differential is connected to a propeller shaft (not shown), and a drive pinion 122 inserted through the differential case 121 is meshed with a ring gear 124 attached to the differential gear case 123 and attached to the inside of the differential gear case 123. The pinion gear 125 is meshed with the side gear 126 connected to the drive shaft (not shown) inserted from the left and right into the differential gear case 123, and the driving force of the engine is transmitted from the propeller shaft to the left and right drive shafts. It has become like. In this differential, the drive pinion 122 and the differential gear case 123, which are power transmission shafts, are supported by a pair of conical roller bearings 10a and 10b, respectively.

When each of the conical roller bearings 10a and 10b rotates at high speed and the lower part thereof is immersed in the oil bath, as shown by the arrow in FIG. 26, the lubricating oil of the oil bath is transferred from the small diameter side of the roller 12 to the outer diameter side of the cage 14. The lubricating oil that flows into the bearing from the outer diameter side of the cage 14 to the outer ring 11 passes through the raceway surface 11A of the outer ring 11 to the larger diameter side of the roller 12 and is divided into the inner diameter side and the inner diameter side. It flows out from the inside. On the other hand, the lubricating oil flowing from the inner diameter side of the cage 14 to the inner ring 13 side is held because the gap δ between the collar 50 of the small annular portion 106 of the cage 14 and the small collar 42 of the inner ring 13 is set narrow. Much less than the lubricating oil flowing in from the outer diameter side of the vessel 14, and most of the lubricating oil flowing in from this gap δ passes through the notch 10a provided in the pillar portion 108 on the narrow side of the pocket 109. Then, it moves to the outer diameter side of the cage 14. Therefore, the amount of the lubricating oil that reaches the large collar 41 along the raceway surface 13A of the inner ring 13 as it is becomes very small, and the amount of the lubricating oil that stays inside the bearing can be reduced.

In the conical roller bearing according to each of the above examples of the present embodiment, the lubricating oil flowing from the inner diameter side of the cage to the inner ring side is supplied by providing a notch in the small annular portion on the narrow side of the trapezoidal pocket. The amount of lubricating oil that escapes from the notch in the small annular portion to the outer ring side and reaches the large bearing along the raceway surface of the inner ring can be further reduced, and the torque loss due to the flow resistance of the lubricating oil can be further reduced. ..

By providing a notch at least in the pillar portion on the wide side of the trapezoidal pocket, the conical rollers can be slidably contacted with the pillar portion in a well-balanced manner.

By making the total area of the notches provided on the narrow side of the trapezoidal pocket wider than the total area of the notches provided on the wide side of the trapezoidal pocket, it reaches the large brim along the raceway surface of the inner ring. The amount of lubricating oil can be reduced to further reduce the torque loss due to the flow resistance of the lubricating oil. Since the inflowing lubricating oil escapes from the notch on the narrow width side to the outer ring side on the outer diameter side more than the notch on the wide width side, the torque loss due to the flow resistance of the lubricating oil can be further reduced.

An axially inward collar facing the outer diameter surface of the small collar of the inner ring is provided on the axially outer side of the small annular portion of the cage, and the inner diameter surface of the collar of the opposed small annular portion and the small collar of the inner ring are provided. By setting the gap between the outer diameter surface and the outer diameter of the inner ring to 2.0% or less of the outer diameter of the small collar of the inner ring, the amount of lubricating oil flowing from the inner diameter side of the cage to the inner ring side can be reduced, and the amount of lubricating oil can be reduced. The torque loss due to the flow resistance can be further reduced.

Hereinafter, an example of the use of the conical roller bearing 10 according to the present embodiment will be described. The above-mentioned conical roller bearing 10 is suitable for, for example, an automobile differential or transmission. That is, it is preferable to use the tapered roller bearing 10 as an automobile tapered roller bearing. The conical roller bearing 10 of the present embodiment may be incorporated for supporting the gear shaft of a power transmission device such as a transmission. With reference to FIG. 25, the manual transmission 100 is a constantly meshing manual transmission, which includes an input shaft 111, an output shaft 112, a counter shaft 113, gears 114a to 114k, and a housing 115. It has.

The input shaft 111 is rotatably supported with respect to the housing 115 by a tapered roller bearing 10. A gear 114a is formed on the outer circumference of the input shaft 111, and a gear 114b is formed on the inner circumference.

On the other hand, the output shaft 112 is rotatably supported by the housing 115 by the conical roller bearing 10 on one side (right side in the figure), and is rotatable to the input shaft 111 by the rolling bearing 120A on the other side (left side in the figure). Is supported by. Gears 114c to 114g are attached to the output shaft 112.

The gear 114c and the gear 114d are formed on the outer circumference and the inner circumference of the same member, respectively. The members on which the gears 114c and 114d are formed are rotatably supported by the rolling bearing 120B with respect to the output shaft 112. The gear 114e is attached to the output shaft 112 so as to rotate integrally with the output shaft 112 and to slide in the axial direction of the output shaft 112.

Further, each of the gear 114f and the gear 114g is formed on the outer periphery of the same member. The member on which the gear 114f and the gear 114g are formed is attached to the output shaft 112 so as to rotate integrally with the output shaft 112 and to slide in the axial direction of the output shaft 112. When the member forming the gear 114f and the gear 114g slides to the left side in the drawing, the gear 114f can mesh with the gear 114b, and when the member slides to the right side in the drawing, the gear 114g and the gear 114d It can be meshed.

Gears 114h to 114k are formed on the counter shaft 113. Two thrust needle roller bearings are arranged between the counter shaft 113 and the housing 115, whereby an axial load (thrust load) of the counter shaft 113 is supported. The gear 114h is always in mesh with the gear 114a, and the gear 114i is in constant mesh with the gear 114c. Further, the gear 114j can mesh with the gear 114e when the gear 114e slides to the left side in the drawing. Further, the gear 114k can mesh with the gear 114e when the gear 114e slides to the right side in the drawing.

Next, the shifting operation of the manual transmission 100 will be described. In the manual transmission 100, the rotation of the input shaft 111 is transmitted to the counter shaft 113 by meshing the gear 114a formed on the input shaft 111 and the gear 114h formed on the counter shaft 113. Then, the rotation of the counter shaft 113 is transmitted to the output shaft 112 by meshing the gears 114i to 114k formed on the counter shaft 113 with the gears 114c and 114e attached to the output shaft 112. As a result, the rotation of the input shaft 111 is transmitted to the output shaft 112.

When the rotation of the input shaft 111 is transmitted to the output shaft 112, by changing the gear that meshes between the input shaft 111 and the counter shaft 113 and the gear that meshes between the counter shaft 113 and the output shaft 112. , The rotation speed of the output shaft 112 can be changed stepwise with respect to the rotation speed of the input shaft 111. Further, the rotation of the input shaft 111 can be directly transmitted to the output shaft 112 by directly engaging the gear 114b of the input shaft 111 and the gear 114f of the output shaft 112 without going through the counter shaft 113.

The shifting operation of the manual transmission 100 will be described in more detail below. When the gear 114f does not mesh with the gear 114b, the gear 114g does not mesh with the gear 114d, and the gear 114e meshes with the gear 114j, the driving force of the input shaft 111 is the gear 114a, the gear 114h, the gear 114j, and the gear 114j. It is transmitted to the output shaft 112 via the gear 114e. This is, for example, the first speed.

When the gear 114g meshes with the gear 114d and the gear 114e does not mesh with the gear 114j, the driving force of the input shaft 111 is via the gear 114a, the gear 114h, the gear 114i, the gear 114c, the gear 114d and the gear 114g. It is transmitted to the output shaft 112. This is, for example, the second speed.

When the gear 114f meshes with the gear 114b and the gear 114e does not mesh with the gear 114j, the input shaft 111 is directly connected to the output shaft 112 by meshing with the gear 114b and the gear 114f, and the driving force of the input shaft 111 is reduced. It is directly transmitted to the output shaft 112. This is, for example, the third speed.

As described above, the manual transmission 100 includes a conical roller bearing 10 to rotatably support the input shaft 111 and the output shaft 112 as rotating members with respect to the housing 115 arranged adjacent thereto. There is. As described above, the conical roller bearing 10 according to the above embodiment can be used in the manual transmission 100. The conical roller bearing 10 with reduced torque loss and improved life is suitable for use in a manual transmission 100 in which a high surface pressure is applied between the rolling element and the raceway member.

By the way, in transmissions or differentials, which are power transmission devices for automobiles, in addition to using low-viscosity lubricating oil, there is a tendency to reduce the amount of oil in order to save fuel consumption, which is sufficient for conical roller bearings. It may be difficult to form an oil film. Further, when the transmission or differential is used in a low temperature environment (for example, -40 ° C to -30 ° C), the viscosity of the lubricating oil increases. Oil may not be adequately supplied to conical roller bearings. For this reason, conical roller bearings for automobiles are required to have seizure resistance and improved life. Therefore, the above requirements can be satisfied by incorporating the above-mentioned tapered roller bearing 10 having improved seizure resistance and life into the transmission or the differential.

As an example, a tapered roller bearing using the cage shown in FIG. 11 (Example A) and a tapered roller bearing using the cage shown in FIG. 22 (Example B) were prepared. Further, as a comparative example, a conical roller bearing using a cage having no notch in the pocket (Comparative Example A) and a conical roller bearing having a notch in the center of the pillar between the pockets of the cage (comparison). Example B) and a conical roller bearing (Comparative Example C) in which notches are provided in the small annular portion and the large annular portion at both ends in the axial direction of the cage pocket are prepared. The dimensions of each conical roller bearing are 100 mm in outer diameter, 45 mm in inner diameter, and 27.25 mm in width, and the parts other than the notch of the pocket are the same.

Torque measurement tests using a vertical torque tester were performed on the conical roller bearings of the above example and the comparative example. The test conditions are as follows.
・ Axial load: 300 kgf
-Rotation speed: 300 to 2000 rpm (100 rpm pitch)
-Lubrication conditions: Oil bath lubrication (lubrication oil: 75W-90)
FIG. 27 shows the result of the torque measurement test. The vertical axis of the graph of FIG. 27 represents the torque reduction rate with respect to the torque of Comparative Example A using a cage having no notch in the pocket. Comparative Example B in which the notch is provided in the central portion of the pillar portion of the pocket and Comparative Example C in which the notch is provided in the small annular portion and the large annular portion of the pocket also have a torque reduction effect, but the narrow side of the pocket is observed. In Example A in which a notch was provided in the pillar portion of the above, a superior torque reduction effect was recognized as compared with these comparative examples, and a notch was also provided in the small annular portion on the narrow width side to form the notch on the narrow width side. In Example B in which the total area is wider than that on the wide side, a further excellent torque reduction effect is recognized.

Further, the torque reduction rate at 2000 rpm, which is the maximum rotation speed of the test, was 9.5% in Example A and 11.5% in Example B, and was excellent even under the conditions of use at high speed rotation in differentials and transmissions. A torque reduction effect can be obtained. The torque reduction rates of Comparative Example B and Comparative Example C at a rotation speed of 2000 rpm are 8.0% and 6.5%, respectively.

<Sample>
As a sample, sample No. Four types of cones 1 to 4 were prepared as samples. The model number of the conical roller was 30206. As the material of the conical roller, JIS standard SUJ2 material (1.0 mass% C-0.25 mass% Si-0.4 mass% Mn-1.5 mass% Cr) was used.

Sample No. For No. 1, after carburizing, nitriding and quenching, logarithmic crowning according to the present embodiment shown in FIG. 5 was formed at both ends. The carburizing and nitriding treatment temperature was 845 ° C., and the holding time was 150 minutes. The atmosphere of the carburizing nitriding treatment was RX gas + ammonia gas. Sample No. Regarding 2, the sample No. After carburizing, nitriding and quenching in the same manner as in No. 1, the partial arc crowning shown in FIG. 8 was formed.

Sample No. For No. 3, after the heat treatment pattern shown in FIG. 20 was carried out, logarithmic crowning according to the present embodiment shown in FIG. 5 was formed at both ends. The carburizing and nitriding treatment temperature was 845 ° C., and the holding time was 150 minutes. The atmosphere of the carburizing nitriding treatment was RX gas + ammonia gas. The final quenching temperature was 800 ° C.

Sample No. For No. 4, after the heat treatment pattern shown in FIG. 20 was carried out, logarithmic crowning according to the present embodiment shown in FIG. 5 was formed at both ends. In order to make the nitrogen concentration in the nitrogen-enriched layer at a depth of 0.05 mm from the outermost surface of the sample 0.1% by mass or more, the carburizing nitriding treatment temperature was set to 845 ° C. and the holding time was set to 150 minutes. The atmosphere of the carburizing nitriding treatment was RX gas + ammonia gas. Furthermore, the atmosphere inside the furnace was strictly controlled. Specifically, unevenness in the temperature inside the furnace and unevenness in the atmosphere of ammonia gas were suppressed. The final quenching temperature was 800 ° C. The above-mentioned sample No. 3 and sample No. 4 corresponds to the embodiment of the present invention. Sample No. 1 and sample No. 2 corresponds to a comparative example.

<Experimental content>
Experiment 1: Life test A life test device was used. As the test conditions, the conditions of test load: Fr = 18 kN, Fa = 2 kN, lubricating oil: turbine oil 56, and lubrication method: oil bath lubrication were used. In the life test apparatus, the two conical roller bearings as the test piece are arranged so as to support both ends of the support shaft. A cylindrical roller bearing for applying a radial load to the conical roller bearing via the support shaft is arranged at the central portion of the support shaft in the extending direction, that is, the central portion of the two tapered roller bearings. Then, by applying a radial load to the cylindrical roller bearing for load loading, the radial load is applied to the conical roller bearing as the test piece. Further, the axial load is transmitted from one conical roller bearing to the support shaft through the housing of the life test device, and the axial load is applied to the other conical roller bearing. As a result, the life test of the tapered roller bearing is performed.

Experiment 2: Life test under eccentric load The same test equipment as the life test in Experiment 1 above was used. The test conditions are basically the same as those in Experiment 1 above, but the test was performed with an axial inclination of 2/1000 rad applied to the central axis of the roller and an eccentric load applied.

Experiment 3: Rotational torque test Sample No. Torque measurement tests were performed on 1 to 4 using a vertical torque tester. As the test conditions, the conditions of test load: Fa = 7000N, lubricating oil: turbine oil 56, lubrication method: oil bath lubrication, and rotation speed: 5000 rpm were used.

<Result>
Experiment 1: Life test Sample No. 4 showed the best results and was considered to have a long life. Sample No. 2 and sample No. Reference numeral 3 is sample No. Although it did not reach the result of No. 4, it showed a good result and was judged to be sufficiently practical. On the other hand, sample No. As for 1, the result showed the shortest life.

Experiment 2: Life test under eccentric load Sample No. 4 and sample No. 3 showed the best results and was considered to have a long life. Next, sample No. 1 is sample No. 4 and sample No. Although it was less than 3, it showed relatively good results. On the other hand, sample No. No. 2 shows a worse result than the result at the time of the above experiment 1, and it is considered that the life is shortened due to the eccentric load condition.

Experiment 3: Rotational torque test Sample No. 1. Sample No. 3. Sample No. 4 showed a sufficiently small rotational torque, and good results were obtained. On the other hand, sample No. In No. 2, the rotational torque was larger than that of the other samples.

Based on the above results, the sample No. 4 showed good results in all the tests, and was the best overall result. In addition, sample No. Sample No. 3 is also No. 3. 1 and sample No. It showed better results than 2.

The features described in each example included in the above-described embodiments may be applied so as to be appropriately combined within a technically consistent range.

The embodiments and examples disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

10 Conical roller bearing, 11 outer ring, 11A, 13A raceway surface, 11B, 12B, 13B nitrogen enriched layer, 11C, 12C, 13C unnitrided part, 12 rollers, 12A rolling surface, 12E unprocessed surface, 13 inner ring, 14 Cage, 16 large end surface, 16A convex part, 16B concave part, 16C arc, 16s spherical surface, 17 small end surface, 18 large flange surface, 18a conical surface, 18b flank surface, 18c chamfer, 19 small flange surface, 21,25 chamfered part , 22, 24 crowning part, 22A crowning, 23 center part, 26 center line, 27 contact part crowning part, 27A straight part, 27B part formed by logarithmic curve, 28 non-contact part crowning part, 31 first measurement point, 32 2nd measurement point, 33 3rd measurement point, 41 large collar, 42 small collar, 43 1st grinding relief part, 44 2nd grinding relief part, 50 collar, 100 manual transmission, 106 small ring part, 107 large ring part , 108 pillars, 109 pockets, 110a, 110b, 110c notches, 111 input shafts, 112 output shafts, 113 counter shafts, 114a-114k gears, 115 housings, 121 differential cases, 122 drive pinions, 123 differential gear cases, 124 ring gear, 125 pinion gear, 126 side gear, 190 slime, 200 contact ellipse.

Claims (11)

An outer ring having an outer ring raceway surface on the inner peripheral surface,
An inner ring having an inner ring raceway surface on the outer peripheral surface and arranged radially inward with respect to the outer ring,
A plurality of conical rollers arranged between the outer ring raceway surface and the inner ring raceway surface and having a rolling surface in contact with the outer ring raceway surface and the inner ring raceway surface.
It includes a plurality of pockets arranged at predetermined intervals in the circumferential direction, and includes a cage for accommodating and holding each of the plurality of conical rollers in each of the plurality of pockets.
The cage includes a small annular portion connected on the small-diameter end face side of the conical roller, a macrocyclic portion connected on the large-diameter end face side of the conical roller, and a plurality of pillar portions connecting these annular portions.
The pocket is formed in a trapezoidal shape in which the portion for accommodating the small diameter side of the conical roller is on the narrow side and the portion accommodating the large diameter side is on the wide side.
The cage is provided with a notch in the pillar portion on the narrow side of the pocket of the cage so as to have a width from the boundary between the small annular portion and the pillar portion toward the macrocyclic portion. The lubricating oil flowing from the inner diameter side to the inner ring side is quickly escaped from the notch to the outer ring side on the outer diameter side, and the edge of the small annular portion on the pocket side is formed on the narrow side of the pocket. The shape is such that the bottom part extends to the pillar part.
Before conical this filtrate number of Kifuku comprises a nitriding layer formed on the surface layer before Kitendo surface,
Crowning is formed on the rolling surface of the conical roller.
_{The sum of the drop amounts of the crowning has K 1} , K ₂ , and z _m as design parameters in the y-z coordinate system in which the generatrix of the rolling surface of the conical roller is the y-axis and the generatrix orthogonal direction is the z-axis. , Q is the load, L is the length of the effective contact portion of the rolling surface of the conical roller in the generatrix direction, E'is the equivalent elastic coefficient, and a is from the origin taken on the generatrix of the rolling surface of the conical roller. When the length to the end of the effective contact portion is A = 2K ₁ Q / πLE', it is expressed by the equation (1).
From the outermost surface of the surface layer to the nitrogen-enriched layer at the first measurement point, which is the boundary point between the chamfered portion of the conical roller and the crowning forming portion where the crowning is formed on the rolling surface of the conical roller. The distance to the bottom is T1, the distance at the second measurement point 1.5 mm from the small end surface of the conical roller is T2, and the distance to the center of the rolling surface of the conical roller is at the third measurement point. Assuming that the distance is T3, the conical roller bearing in which the T1, the T2 and the T3 are 0.2 mm or more.

The conical roller bearing according to claim 1, wherein the former austenite crystal particle size in the nitrogen-enriched layer has a JIS standard particle size number of 10 or more. The conical roller bearing according to claim 1 or 2, wherein the nitrogen concentration in the nitrogen-enriched layer at a depth of 0.05 mm from the outermost surface is 0.1% by mass or more. The conical roller bearing according to any one of claims 1 to 3, wherein at least one _{of K 1} , K ₂ , and z _m of the above formula (1) is optimized with the surface pressure as an objective function. The crowning-forming portion in which the crowning is formed on the rolling surface of the conical roller is a contact portion crowning portion in the axial range of the inner ring raceway surface and in contact with the inner ring raceway surface, and the axial direction of the inner ring raceway surface. Including a non-contact portion crowning portion that is out of range and is non-contact with the inner ring raceway surface.
In the contact portion crowning portion and the non-contact portion crowning portion, the generatrix extending in the roller axis direction is a line represented by a function different from each other and smoothly continuous at the connection point.
The conical roller bearing according to any one of claims 1 to 4, wherein the curvature of the generatrix of the non-contact portion crowning portion is smaller than the curvature of the generatrix of the contact portion crowning portion in the vicinity of the connection point. The conical roller bearing according to claim 5, wherein the generatrix of the non-contact portion crowning portion is a straight line in either or both of the large diameter side portion and the small diameter side portion. The conical roller bearing according to claim 5 or 6, wherein a part or all of the generatrix of the contact portion crowning portion is represented by logarithmic crowning. The conical roller bearing according to any one of claims 1 to 7, wherein a notch is also provided in the small annular portion on the narrow width side of the pocket. The conical roller bearing according to any one of claims 1 to 8, wherein a notch is also provided in at least the pillar portion on the wide side of the pocket. The total area of the notches provided on the narrow side of the pocket is larger than the total area of the notches provided on the wide side of the pocket.
The conical roller bearing according to claim 9, wherein the inflowing lubricating oil escapes from the notch on the narrow width side to the outer ring side on the outer diameter side more than the notch on the wide side. An axially inward collar facing the outer diameter surface of the small collar of the inner ring is provided on the axially outer side of the small annular portion of the cage, and the inner diameter surface of the collar of the opposed small annular portion is provided. The cone according to any one of claims 1 to 10, wherein the gap between the inner ring and the outer diameter surface of the small collar of the inner ring is 2.0% or less of the outer diameter dimension of the small collar of the inner ring. Roller bearing.

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