JP2023155324A - tapered roller bearing - Google Patents

Abstract

To smoothly rotate a bearing that prevents a rapid temperature rise even when a tapered roller bearing is used under a severe lubricating condition.SOLUTION: Assuming an intersection point of a virtual line extending a bus line of a raceway surface 11 of an inner ring 10 to a grinding recess 13 side and a virtual line extending a bus line of a large collar surface 12a to the grinding recess 13 side as a reference point O2, the cut-off width of the grinding recess 13 from the reference point O2 to a large collar surface 12a as A, and the width of a chamfering 32 of a tapered roller 30 in a direction along the bus line of the large collar surface 12a as RC, the width RC is 0.7 mm or less, and A<RC. Assuming an acute angle made by a virtual line connecting from a contact point of the large collar surface 12a and a large end surface 33 of a tapered roller 30 to an apex O1 of a cone angle β of a rolling surface 31 with respect to the bus line of the raceway surface 11 as ρ, β/7≥ρ.SELECTED DRAWING: Figure 3

Description

The present invention relates to tapered roller bearings.

The rolling bearings that support the rotating parts must be suitable for the direction and magnitude of the load received by the rolling bearings and the space in which the bearings are installed. For applications that support the rotating parts of automobile transmissions (MT, AT, DCT, CVT, hybrid, etc.) or differentials, compactness is also required despite the usage conditions of radial loads, axial loads, and moment loads. . For this reason, tapered roller bearings are used which can carry radial loads and axial loads and have excellent load capacity.

During operation, a tapered roller bearing generates a thrust force that pushes the tapered rollers toward the larger diameter side. For this reason, the inner ring is formed with a large flange for supporting the large end surface of the tapered roller and guiding it in the revolution direction (circumferential direction) of the tapered roller. The large flange has a large flange surface for slidingly contacting the large end surfaces of the tapered rollers. The inner ring has a grinding relief formed around the entire circumference that connects the large collar surface and the raceway surface.

Generally, the shapes of the large end surface of the tapered roller and the large flange surface of the inner ring are designed so that they geometrically come into contact at only one point. During operation, the large end surface of the tapered roller slides into contact with the large flange surface of the inner ring in the direction of revolution, but due to the various loads and thrusts mentioned above, the sliding contact area generally moves around the designed contact point. It occurs in a long elliptical region with a short radial axis. If the sliding contact part is not sufficiently lubricated, heat will be generated and the temperature will rise rapidly.

When tapered roller bearings are operated at high speeds, such as in automobile transmissions, and the lubricating oil becomes hot, a good lubrication mode cannot be maintained at the sliding contact area between the large end surface of the tapered roller and the large flange surface of the inner ring, resulting in boundary lubrication. This may result in insufficient lubrication. In order to improve the seizure resistance during such high-temperature operation, the shape and surface properties of the large end surface of the tapered roller and the large flange surface of the inner ring have been devised (Patent Documents 1 to 3).

In Patent Document 1, when the radius of curvature of the large end face of the tapered roller is R, and the distance from the vertex of the cone angle of the tapered roller to the contact portion of the large flange surface is R _BASE , R/R _BASE is 0.75 to 0.75. By setting it in the range of 0.87, the wedge effect when the lubricating oil is dragged between the large end surface of the tapered roller and the large flange surface of the inner ring can be exhibited well, and the thickness of the oil film at the sliding contact area can be improved ( heat generation).

In Patent Document 2, the large end surface of the tapered rollers and the large end surface of the inner ring are formed by forming a relief surface that is shaped to move away from the large end surface of the tapered rollers from the outer diameter side edge of the large flange surface toward the chamfered inner diameter side edge of the large flange surface. The ability to form an oil film can be improved by increasing the drawing effect of lubricating oil to the contact portion with the collar surface.

In Patent Document 3, the aforementioned R/R _BASE is set in the range of 0.75 to 0.87, and when the actual radius of curvature of the large end face of the tapered roller is R _ACTUAL , R _ACTUAL /R is set to 0.5 or more. This suppresses heat generation on the large end surface of the tapered roller and the large flange surface of the inner ring even in harsh lubrication environments, improving seizure resistance. By introducing the coefficient, it is possible to expand the practical range of the ratio R _ACTUAL /R and select an appropriate bearing specification according to the usage conditions.

Japanese Patent Application Publication No. 2000-170774 Japanese Patent Application Publication No. 2000-170775 Japanese Patent Application Publication No. 2018-136027

However, in automotive transmissions and differentials, there is a trend to reduce the viscosity of lubricating oil and the amount of lubricating oil in the unit in order to improve fuel efficiency, and this trend is expected to continue in the future. Therefore, the lubrication conditions for rolling bearings become even more severe. In particular, in tapered roller bearings, it is even more important to ensure the thickness of the oil film at the sliding contact area between the large end surface of the tapered roller and the large flange surface of the inner ring, and to take into account the suppression of temperature rise by lubricating oil.

In view of the above-mentioned background, the problem to be solved by the present invention is to prevent rapid temperature rise and rotate the bearing smoothly even when the tapered roller bearing is used under severe lubrication conditions.

In order to achieve the above object, the present invention includes an inner ring, an outer ring, a plurality of tapered rollers arranged between the inner ring and the outer ring, and a cage that accommodates these tapered rollers, wherein the tapered rollers are a raceway surface in which the inner ring is formed in a conical shape, the raceway surface having a raceway surface formed in a shape, a chamfer continuous to a large diameter side of the rolling surface, and a large end surface continuous to the chamfer; In a tapered roller bearing having a large flange surface that receives a large end surface of the tapered roller, and a grinding relief formed in a groove shape that connects the large flange surface and the raceway surface, the generatrix of the raceway surface is directed to the grinding relief side. The intersection of the extended imaginary line and the imaginary line extending the generatrix of the large flange surface to the grinding relief side is set as a reference point, the width of the gap from the reference point to the large flange surface is defined as A, and the chamfering of the tapered roller is performed. When the width of the large flange surface in the direction along the generatrix is RC, the width RC is 0.7 mm or less, A<RC, the conical angle of the rolling surface is β, and the large flange surface is When the acute angle that an imaginary line connecting the contact point between the collar surface and the large end surface of the tapered roller to the vertex of the conical angle β makes with the generatrix of the raceway surface is ρ, a configuration in which β/7≧ρ is satisfied. Adopted.

According to the above configuration, the width RC of the chamfer of the tapered roller is set to 0.7 mm or less, and the width of the grinding relief gap A<width RC, which is a particularly small dimension, increases the width of the large flange surface, and the width of the tapered roller It can be made wide enough to receive the large end face. For this reason, we have optimized the contact relationship between the large flange surface and the large end surface of the tapered roller to better exert the wedge effect that acts between the large flange surface and the large end surface of the tapered roller, improving oil film formation ability. can be done. In addition, by setting the angle ρ, which indicates the radial height of the contact point between the large flange surface and the large end surface of the tapered roller, with respect to the reference point, to a range lower than β/7, it is possible to prevent slippage at the sliding contact area. It is possible to prevent the speed from increasing and suppress the amount of heat generated by the large flange surface, thereby preventing a sudden rise in temperature.

Specifically, when the approach angle of the grinding relief to the large flange surface of the inner ring is a, and the approach angle of the grinding relief to the raceway surface is b, a>b, and the distance from the reference point to the large When the clearance width up to the flange surface is A, and the clearance width from the reference point to the raceway surface is B, it is preferable that A<B. In manufacturing, in order to satisfy the gap width A of 0.5 mm or less, when the amount of grinding of the large flange surface changes during processing, the width of the large flange surface changes depending on the approach angle a of the grinding clearance. It is necessary to take this into consideration. The larger the approach angle a to the large flange surface, the smaller the amount of change in the width of the large flange surface when the amount of grinding of the large flange surface changes, so the larger the approach angle a is, the better. Furthermore, in consideration of the ease of discharging chips during turning machining for grinding relief, it is preferable to satisfy the relationships a>b and A<B.

When the depth of the grinding relief with respect to the raceway surface of the inner ring is c, and the depth of the grinding relief with respect to the large flange surface is d, it is preferable that c>d. In this way, the stress in the large flange caused by the load applied from the large end surface of the tapered rollers to the large flange surface of the inner ring can be reduced, and the strength of the large flange of the inner ring can be improved.

When the depth of the grinding relief with respect to the large flange surface of the inner ring is d, the depth d is preferably 0.3 mm or less. In this way, the strength of the inner ring's large flange can be surely improved.

When the approach angle of the grinding relief with respect to the large flange surface of the inner ring is a, it is preferable that 20°≦a≦50°. In this way, it is easy to control the gap width A when grinding the large flange surface.

The acute angle formed by the generatrix of the raceway surface with the central axis of the inner ring is θ, the large end diameter of the rolling surface of the tapered roller is Dw, the length of the tapered roller is L, and the large flange surface Let W be the width of , it is preferable that the width W is a value that satisfies the following equation 1.
W≧{Dw×(1/2)×Tanθ/(L/Dw)}...Formula 1
By doing this, the large flange surface is sufficiently opposed to the large end surface of the tapered roller, and even when the sliding contact area between the large end surface of the tapered roller and the large flange surface of the inner ring rises to the outside diameter side of the large flange, a good condition can be maintained. can maintain contact.

It is preferable that the grain size number of the prior austenite crystal grains on the large flange surface of the inner ring is No. 6 or higher. Such a large flange surface is suitable for delaying surface damage due to metal contact with the large end surface of the tapered roller.

It is preferable that the large flange surface of the inner ring is formed of a nitrided layer having a nitrogen content of 0.05 wt% or more. Such a large flange surface is suitable for delaying surface damage due to metal contact with the large end surface of the tapered roller.

It is preferable that the surface roughness of the large flange surface of the inner ring is 0.1 μmRa or less, and the surface roughness of the large end surface of the tapered roller is 0.12 μmRa or less. In this way, it is possible to improve the formation of an oil film between the large flange surface and the large end surface of the tapered roller.

When the set radius of curvature of the large end face of the tapered roller is R, and the basic radius of curvature from the vertex of the conical angle of the rolling surface to the large flange surface of the inner ring is R _BASE , R/R _BASE is 0.70. and 0.95 or less, and when R _ACTUAL is the actual radius of curvature of the large end surface of the tapered roller, R _ACTUAL /R of at least one tapered roller among the plurality of tapered rollers is 0.3 or more and 0. It may be less than .5. In this invention, since the ability to form an oil film on the large flange surface side can be improved, the ranges of R/R _BASE and R _ACTUAL /R can be relaxed compared to the tapered roller bearing of Patent Document 3. Since the yield of tapered rollers improves accordingly, tapered roller bearings can be provided at relatively low cost.

The tapered roller bearing according to the present invention has excellent seizure resistance under severe lubrication conditions, and is therefore suitable for use in supporting rotating parts of automobile transmissions or differentials.

As described above, by adopting the above configuration, the present invention optimizes the contact relationship between the large flange surface of the inner ring and the large end surface of the tapered roller, improves the ability to form an oil film, and prevents slippage at the sliding contact portion. Since it is possible to prevent speed increases, even when tapered roller bearings are used under severe lubrication conditions, rapid temperature rises can be prevented and the bearings can rotate smoothly.

A diagram showing the generatrix shape near the large flange surface of the tapered roller bearing according to the embodiment of the present invention. A cross-sectional view of a tapered roller bearing according to this embodiment A diagram showing the generatrix shape near the large flange surface in the ideal contact state between the large end face and the large flange surface of the tapered roller in Figure 2. Half-longitudinal section showing the design specifications of the tapered roller bearing in Figure 2 Schematic diagram showing the detailed shape of the large end face of the tapered roller in Figure 2 Schematic diagram showing the processed shape of the large end face of the tapered roller in Figure 5 Graph showing the relationship between the radius of curvature of the large end face of the tapered roller in Figure 2 and the oil film thickness A diagram showing an example of changing the generatrix shape near the large tsuba surface in Figure 1. A cross-sectional view showing an example of an automotive differential incorporating the tapered roller bearing shown in Figure 2. A sectional view showing an example of an automotive transmission incorporating the tapered roller bearing shown in Figure 2.

A tapered roller bearing according to an exemplary embodiment of the present invention will be described based on the accompanying drawings.

This tapered roller bearing shown in FIG. 2 includes an inner ring 10, an outer ring 20, a plurality of tapered rollers 30 arranged between the inner ring 10 and the outer ring 20, and a cage 40 that accommodates these tapered rollers 30. Be prepared. This tapered roller bearing is intended for use in automobile transmissions or differentials, mainly for passenger cars, and has an outer diameter of 150 mm or less.

As shown in FIGS. 2 and 3, the inner ring 10 includes a raceway surface 11 formed in a conical shape, a large flange 12 formed to have a larger diameter than the large-diameter side edge of the raceway surface 11, and a large flange 12. A grinding relief 13 formed from the base to the raceway surface 11, a small flange 14 formed to have a larger diameter than the small diameter side edge of the raceway surface 11, and a small diameter side grinding formed from the base of the small flange 14 to the raceway surface 11. It consists of a bearing ring having a relief 15 on the outer circumferential side.

As shown in FIG. 2, the outer ring 20 is a raceway ring having a conical raceway surface 21 on the inner circumferential side. Lubricating oil is supplied from the outside to the bearing internal space between the inner ring 10 and the outer ring 20.

The tapered roller 30 includes a rolling surface 31 formed in a conical shape, a chamfer 32 continuous to the large diameter side of the rolling surface 31, a large end surface 33 continuous to the chamfer 32, and a large end surface 33 formed on the opposite side of the large end surface 33. It consists of a rolling element having a small end surface 34 that is curved. The large end surface 33 and small end surface 34 of the tapered roller 30 include both side ends that define the roller length L of the tapered roller 30.

The plurality of tapered rollers 30 are arranged in a single row between the inner and outer raceway surfaces 11 and 21. The retainer 40 is made of an annular bearing component that maintains a plurality of tapered rollers 30 at equal intervals in the circumferential direction. Each tapered roller 30 is accommodated in pockets formed in the cage 40 at equal intervals in the circumferential direction.

Although the cage 40 in the illustrated example is a cage-shaped punched cage, the material and manufacturing method of the cage 40 are not particularly limited.

Here, the direction along the central axis CL, which is the center of rotation of the inner ring 10, is referred to as the "axial direction", and the direction perpendicular to the central axis CL is referred to as the "radial direction", and the direction around the central axis CL is referred to as the "radial direction". The circumferential direction that goes around once is called the "circumferential direction." The central axis CL of the inner ring 10 corresponds to the designed rotation center of this tapered roller bearing.

The inner and outer raceway surfaces 11 and 21 are surface portions on which the rolling surfaces 31 of the tapered rollers 30 can roll and are subjected to a radial load.

As shown in FIG. 4, the center axes of the inner ring 10, the outer ring 20, and the tapered rollers 30 are included in the same virtual axial plane, and the center axis (not shown) of the tapered rollers 30 is on the center axis CL of the inner ring 10. When the rollers are in a positional relationship that directly faces one point _O1 , the apex of each cone of the inner and outer raceway surfaces 11, 21 and the rolling surface 31 of the tapered roller 30 coincides with the point _O1 . The large end surface 33 of the tapered roller 30 is designed based on a spherical shape with a set radius of curvature R centered on a straight line connecting the point _O1 and the central axis of the tapered roller 30 in FIG.

Note that the conical shapes of the inner and outer raceway surfaces 11, 21 and the rolling surfaces 31 of the tapered rollers 30 are not limited to shapes with generatrix lines as straight lines, but include shapes with crowning. Here, the generatrix refers to a line segment that generates a certain kind of curved surface as a trajectory due to movement around an axis. For example, the generatrix of the raceway surface 11 is a line segment that forms the raceway surface 11 on a virtual axial plane that includes the center axis CL of the inner ring 10, and the generatrix of the raceway surface 31 is a line segment that forms the raceway surface 11 on a virtual axial plane that includes the center axis CL of the inner ring 10. This is a line segment forming a rolling surface 31 on a virtual plane. As the above-mentioned crowning shape, the full crowning shape or the cut crowning shape disclosed by the applicant in Patent Document 3 can be adopted, and as the cut crowning shape of the rolling surface 31, logarithmic crowning, for example, in Patent Document 3, can be adopted. The shape defined by the formula in the cited Japanese Patent No. 5037094 may be adopted.

As shown in FIGS. 2 and 3, the large flange 12 of the inner ring 10 has a large flange surface 12a that receives the large end surface 33 of the tapered roller 30, an outer diameter surface 12b that defines the outer diameter of the large flange 12, and a large flange. It has a collar chamfer 12c that connects the outer diameter side edge of the surface 12a and the outer diameter surface 12b around the entire circumference. The end surface of the large flange 12 opposite to the large flange surface 12a forms a part of the side surface of the inner ring 10.

The large flange surface 12a is a surface portion for slidingly contacting the large end surface 33 of the tapered roller 30 in the circumferential direction. The generatrix of the large flange surface 12a is a straight line inclined with respect to the radial direction. Therefore, the large flange surface 12a has a conical shape coaxial with the raceway surface 11. The large flange surface 12a may be geometrically shaped so that it can come into contact with the large end surface 33 of the tapered roller 30 at only one point, and its generatrix shape should be a medium concave shape (in this case, it will be a contact with a contact surface, For convenience, it is possible to change the shape to a medium convex shape, etc. (expressed as a point contact at the contact position with the large end surface), a medium concave bottom, and a medium convex shape.

The grinding relief 13 of the inner ring 10 is formed in the shape of a groove connecting the large collar surface 12a and the raceway surface 11. The grinding relief 13 is a circumferential groove for grinding and superfinishing the raceway surface 11 and the large flange surface 12a, and has a depth for each of the raceway surface 11 and the large flange surface 12a.

As shown in FIG. 2, the small flange 14 of the inner ring 10 prevents the plurality of tapered rollers 30 from falling off from the raceway surface 11 toward the small diameter side, and the tapered rollers 30, cage 40, and inner ring 10 form an assembly. It is a part for doing. The small flange 14 and the small diameter side grinding relief 15 adopted in conjunction with this formation are not essential parts as constituent elements of the inner ring.

The inner ring 10, the outer ring 20, and the tapered rollers 30 are each formed by processing required parts in the order of forging, turning, and grinding.

The raceway surface 11 and the large collar surface 12a of the inner ring 10 are formed by turning and grinding a forged body, and are polished by superfinishing.

As shown in FIGS. 1 and 3, the grinding relief 13 of the inner ring 10 is machined by turning based on a predetermined generatrix shape. The generatrix in the turning process of the grinding relief 13 is a large-diameter straight part inclined from the large collar surface 12a, a small-diameter straight part inclined from the raceway surface 11, and a circle connecting these large-diameter straight part and the small-diameter straight part. It is defined by an arcuate line part. Although grinding and super-up machining are not actively performed on the grinding clearance 13, when grinding the raceway surface 11 and the large flange surface 12a, the grinding wheel touches the large diameter side end of the raceway surface grinding area and the large flange surface grinding area. The inner edge will be slightly rounded. Therefore, almost the entire surface of the grinding relief 13 is made of a turned surface, but the connection part of the grinding relief 13 with the raceway surface 11 and the connection part with the large flange surface 12a is a slightly rounded ground surface or a super-finished surface. It has become.

Here, as shown in FIG. 1, the intersection of an imaginary line extending the generatrix of the raceway surface 11 of the inner ring 10 toward the grinding relief 13 side and an imaginary line extending the generatrix of the large collar surface 12a toward the grinding relief 13 side. Let it be the reference point _O2 . Let the approach angle of the grinding relief 13 with respect to the large collar surface 12a be a. Further, the approach angle of the grinding relief 13 with respect to the raceway surface 11 is assumed to be b. Further, the depth of the grinding relief 13 with respect to the raceway surface 11 is defined as c. Further, the depth of the grinding relief 13 with respect to the large flange surface 12a is d. Further, the width from the reference point _O2 to the large flange surface 12a is defined as A. Let the width from the reference point _O2 to the raceway surface 11 be B. Moreover, as shown in FIG. 3, the width that the chamfer 32 of the tapered roller 30 has in the direction along the generatrix of the large collar surface 12a is defined as RC.

The approach angles a, b, widths A, B, and depths c, d shown in FIG. 1 are physical quantities for defining the shape of the grinding relief 13. However, since the above-mentioned rounding of the connection portion between the grinding relief 13 and the raceway surface 11 and the large flange surface 12a is not stable, it is difficult to utilize it for regulating the approach angles a and b. Therefore, the inclination angle of the turning surface of the grinding relief 13 with respect to the raceway surface 11 and the large collar surface 12a is adopted as the approach angles a and b.

Specifically, the approach angle a of the grinding relief 13 is an acute angle that the large-diameter side linear portion of the generatrix of the grinding relief 13 forms with the inner diameter side edge of the large collar surface 12a. The approach angle b of the grinding relief 13 is an acute angle that the small-diameter side linear portion of the generatrix of the grinding relief 13 forms with the large-diameter side edge of the raceway surface 11 .

The width A of the grinding relief 13 is the length from the inner diameter side edge of the large flange surface 12a to the reference point _O2 in the direction along the generatrix of the large flange surface 12a. The width B of the grinding relief 13 is the length from the large diameter side edge of the raceway surface 11 to the reference point _O2 in the direction along the generatrix of the raceway surface 11.

The approach angle a of the grinding relief 13 is larger than the approach angle b. When the amount of grinding of the large flange surface 12a (the amount of cutting in the direction perpendicular to the generatrix of the large flange surface 12a) deviates from the target value during the grinding process, the width W of the large flange surface 12a shown in FIG. It will change depending on the approach angle a. Here, the width W of the large flange surface 12a is the distance between both ends of the generatrix of the large flange surface 12a. In the illustrated example, since the generatrix of the large flange surface 12a is linear, the length of the generatrix corresponds to the width W. The amount of change in the width W of the large flange surface 12a can be made smaller as the approach angle a shown in FIG. 1 is increased. That is, the larger the approach angle a is, the less sensitive the influence on the size of the slit width A will be when the amount of grinding of the large flange surface 12a fluctuates.

The approach angle a of the grinding relief 13 is preferably 20° or more and 50° or less. Within this range, even if the amount of grinding of the large flange surface 12a changes or fluctuates, the influence on the size of the width A is moderate, and the width A can be easily controlled. More preferably, the approach angle a is 30° or more and 40° or less.

The depth c of the grinding relief 13 is the depth of the grinding relief 13 taken in a direction perpendicular to an imaginary line extending the generatrix of the raceway surface 11 with the large-diameter side edge of the raceway surface 11 as a reference. The depth d of the grinding relief 13 is the depth of the grinding relief 13 considered in a direction perpendicular to an imaginary line extending the generatrix of the large flange surface 12a, with the inner diameter side edge of the large flange surface 12a as a reference.

The depth c of the grinding relief 13 is greater than the depth d. This is to prevent the wall thickness between the grinding relief 13 and the side surface of the inner ring 10 from becoming thin. In order to make this wall thickness sufficiently large, the depth d is preferably 0.3 mm or less.

The clearance width A of the grinding relief 13 is smaller than the clearance width B. If the width A is smaller than the width B, it is advantageous to make the approach angle a larger than the approach angle b. The grinding relief 13 is processed by turning. The chips at this time can be more easily discharged from the raceway surface 11 side, which allows a relatively wider space, than from the grinding relief 13 toward the large flange surface 12a. For this reason, turning can be performed more efficiently by discharging the chips toward the raceway surface 11 side. By satisfying the approach angle a>b and the gap width A<B of the grinding relief 13, the discharge pressure of chips is relatively small at the approach angle b and the gap width B side during turning, and the chips are transferred to the raceway surface 11 side. It becomes easier to be discharged. Therefore, turning workability can be improved and machining costs can be reduced.

As shown in FIG. 3, the width RC of the chamfer 32 of the tapered roller 30 is from the outer diameter side edge of the large end surface 33 to the large end side edge of the rolling surface 31 in the direction along the generatrix of the large collar surface 12a. is the length of In the illustrated example, the width RC of the chamfer 32 matches the length from the outer diameter side edge of the large end surface 33 to the reference point _O2 . The width RC of the chamfer 32 of the tapered roller 30 is 0.7 mm or less.

On the other hand, the width A of the grinding relief 13 is smaller than the width RC of the chamfer 32 of the tapered roller 30. The reason why the small width A is adopted is that the inner diameter of the large flange surface 12a is made small and the width W of the large flange surface 12a facing the large end surface 33 of the tapered roller 30 is made sufficiently large as shown in FIG. However, this is to prevent the sliding contact portion between the large end surface 33 of the tapered roller 30 and the large flange surface 12a from reaching the inner diameter side edge of the large flange surface 12a. Increasing the width W of the large flange surface 12a means that even if the position of the sliding contact between the large end surface 33 of the tapered roller 30 and the large flange surface 12a moves, the large end surface 33 of the tapered roller 30 and the large flange surface 12a are This is advantageous in maintaining good contact. The width A can be, for example, 0.5 mm or less.

Further, as shown in FIGS. 2 and 4, the acute angle formed by the generatrix of the raceway surface 11 with respect to the central axis CL of the inner ring 10 is θ. Further, the diameter of the large end of the rolling surface 31 of the tapered roller 30 is defined as Dw. In the geometric relationship between the inclination angle θ of the raceway surface 11, the large end diameter Dw of the rolling surface 31, and the roller length L shown in FIG. 2, the width W of the large collar surface 12a shown in FIG. This is a value that satisfies Equation 1.
W≧{Dw×(1/2)×Tanθ/(L/Dw)}...Formula 1

The above formula 1 is based on the lower limit value of the appropriate width W of the large flange surface 12a so that the large end surface 33 of the tapered roller 30 shown in FIGS. 2 and 3 and the large flange surface 12a of the inner ring 10 can be maintained in a good contact state. This is to determine. In other words, when a radial load (dynamic equivalent load when combined with an axial load) is applied to this tapered roller bearing, the load applied to the raceway surface 11 and the large flange surface 12a change according to the inclination angle θ of the raceway surface 11. The load to be applied is distributed between This distribution ratio is expressed as Tanθ, and is multiplied by the large end diameter Dw of the rolling surface 31, which is closely related to the bearing load capacity. Normally, the load applied during operation of a tapered roller bearing is about half or less of the bearing load capacity, so in order to take this into account, the large end diameter Dw of the rolling surface 31 is set by (1/2). Ride. Furthermore, considering that if the roller length L is long, the bearing rate on the raceway surface 11 in the above-mentioned distribution ratio becomes large, the relationship between the roller length L and the large end diameter Dw of the rolling surface 31 is also (L/ Dw) was taken into account as ^-1 . Based on this formula 1, the lower limit value of the width W of the large collar surface 12a was set according to the applied load. As a result, when the tapered rollers 30 become skewed or the large flange 12 of the inner ring 10 falls down due to a large moment load, and the sliding contact portion between the large end face 33 and the large flange surface 12a rises toward the outer diameter side of the large flange, You can also keep good contact.

Note that the upper limit value of the width W of the large flange surface 12a may be any number of mm for the purpose of supporting and guiding the large end surface 33 of the tapered roller 30, but it is preferably 3 times or less of the lower limit value determined by Equation 1. . If the width W of the large flange surface 12a is too large (that is, the outer diameter of the large flange surface 12a is too large), it becomes difficult for lubricating oil to reach the sliding contact area between the large end surface 33 of the tapered roller 30 and the large flange surface 12a. Good lubrication conditions cannot be ensured.

Here, as shown in FIG. 3, the acute angle that the large flange surface 12a makes with respect to the radial direction is defined as the flange surface angle α. Further, the height difference in the radial direction between the contact point between the large flange surface 12a and the large end surface 33 of the tapered roller 30 and the reference point _O2 is defined as a contact height H. The contact height H is uniquely determined by the combination of the basic radius of curvature R _BASE at the large end surface 33 of the tapered roller 30 and the collar surface angle α. Further, as shown in FIGS. 2 and 4, the conical angle of the rolling surface 31 of the tapered roller 30 is assumed to be β. The conical angle β of the rolling surface 31 is the central angle formed by the conical shape of the rolling surface 31 with its apex _O1 as the center. Also, let ρ be the acute angle that an imaginary line connecting the contact point between the large flange surface 12a of the inner ring 10 and the large end surface 33 of the tapered roller 30 to the apex _O1 of the conical angle β makes with the generatrix of the raceway surface 11. The angle ρ corresponds to the contact height H as shown in FIG. Here, if the large flange surface has a convex curvature toward the large end surface of the tapered roller or a concave curvature that moves away from the large end surface, the contact point between the deepest or highest part of the large flange surface and the large end surface should be Let the connecting angle be ρ.

The sliding speed in the circumferential direction at the contact point between the large collar surface 12a and the large end surface 33 of the tapered roller 30 depends on the contact height H. If the aforementioned contact point exists at the reference point _O2 , which is the virtual intersection of the raceway surface 11 of the inner ring 10 and the large collar surface 12a (contact height H=0), the sliding speed is zero and the reference point The higher the contact height H from point _O2 , the higher the sliding speed at that contact point. As described above, by adopting the small width A, it is possible to widen the large flange surface 12a toward the grinding relief 13 side and lower the contact height H. Therefore, the contact point between the large flange surface 12a and the large end surface 33 of the tapered roller 30 is set at a low position that satisfies β/7≧ρ. Setting the contact point at such a low position reduces the sliding speed at the sliding contact portion between the large flange surface 12a and the large end surface 33 of the tapered roller 30, suppresses heat generation on the large flange surface 12a, and This is effective in preventing a sudden rise in temperature of the surface 12a.

_{The ratio} R/ Regarding R _BASE and the ratio R _ACTUAL /R of the actual radius of curvature R _ACTUAL of the large end face 33 to the set radius of curvature R, it is possible to adopt the numerical range disclosed by the present applicant in Patent Document 3. The details and technical significance of these R/R _BASE and R _ACTUAL /R are as disclosed in Patent Document 3, so in the description of this embodiment, the gist of R/R _BASE and R _ACTUAL /R will be explained. stop.

That is, the set radius of curvature R of the large end surface 33 of the tapered roller 30 shown in FIG. 4 is the R dimension when the large end surface 33 is made of an ideal spherical surface in terms of design. As shown in FIG. 5, points P ₁ , P ₂ , P ₃ , P ₄ at the ends of the large end surface 33, a midpoint P ₅ between points P ₁ and P ₂ , and a midpoint between points P ₃ and P ₄ . P ₆ , radius of curvature R ₁₅₂ passing through points P ₁ , P ₅ , P ₂ , radius of curvature R ₃₆₄ passing through points P ₃ , P ₆ , P ₄ and radius of curvature passing through points P ₁ , P ₅ , P ₆ , P ₄ Considering the radius R ₁₅₆₄ , ideally R=R ₁₅₂ =R ₃₆₄ =R ₁₅₆₄ . Points P ₁ and P ₄ are connection points between the large end surface 33 and the chamfer 32 . Points P ₂ and P ₃ are connection points between the large end surface 33 and the relief portion 35 . In reality, as shown in FIG. 6, both ends of the large end surface 33 sag during the grinding process, so that R ₁₅₂ and R ₃₆₄ on one side cannot be made equal to R ₁₅₆₄ of the entire large end surface 33, and cannot be made smaller. I end up. R ₁₅₂ and R ₃₆₄ on one side of the large end face 33 after processing is referred to as the actual radius of curvature R _ACTUAL .

The set radius of curvature R and the actual radius of curvature R _ACTUAL are determined as follows. The radius of curvature R ₁₅₆₄ in FIG. 6 is an approximate circle passing through the four points P ₁ , P ₅ , P ₆ , and P ₄ shown in FIG. 5 . R ₁₅₂ = R ₃₆₄ = R ₁₅₆₄ was measured using "Surf Test, a surface roughness measuring device manufactured by Mitutoyo Co., Ltd." model name: SV-3100. The measurement method is to obtain the shape of the large end face 33 of the tapered roller 30 in the direction along the generatrix line using the measuring instrument, plot the points P ₁ , P ₂ , P ₃ , and P ₄ , and then plot the midpoints P _{5 and P 4} . The midpoint _P6 was plotted. The radius of curvature R ₁₅₂ was calculated as the radius of the circular arc passing through the points P ₁ , P ₅ , and P ₂ (the same applies to the radius of curvature R ₃₆₄ ). For the radius of curvature R ₁₅₆₄ , the approximate radius of the arc curve was calculated using a value obtained by taking four points using the command "input multiple times." The shape of the large end surface 33 in the direction along the generatrix was measured once in the diameter direction.

The large flange surface 12a of the inner ring 10 shown in FIG. 3 slides into contact only with a portion of the large end surface 33 of the tapered roller 30 shown in FIG. 6 having a radius of curvature R ₁₅₂ and a radius of curvature R ₃₆₄ on one side. The actual sliding contact between the large end surface 33 and the large brim surface 12a has an actual radius of curvature R _ACTUAL (R ₁₅₂ , R ₃₆₄ ) smaller than the set radius of curvature R (R ₁₅₆₄ ). Accordingly, the actual contact surface pressure between the large end face 33 and the large flange surface 12a and the skew angle of the tapered rollers 30 become larger than their respective design ideal values. If the skew angle or contact surface pressure increases in an environment where the oil film is insufficient, the sliding contact between the large end surface 33 and the large flange surface 12a becomes unstable, and the oil film parameter decreases. When the oil film parameter is less than 1, the large end face 33 and the large flange face 12a become boundary lubrication where metal contact begins, increasing the risk of seizure. Here, the oil film parameter is Λ (= h/σ ). Verification of the practical range of the ratio between the actual radius of curvature R _ACTUAL and the set radius of curvature R is influenced by the level of severity of the lubrication condition at the peak of the lubricant operating temperature between the large end face 33 and the large collar face 12a. do.

When the generatrix shape of the large flange surface 12a is linear and constant, the lubrication state between the large end surface 33 and the large flange surface 12a is determined by the actual radius of curvature _RACTUAL and the operating temperature of the lubricating oil, and in applications such as transmissions and differentials. Since the lubricating oil to be used is basically determined, the viscosity of that lubricating oil is also determined. Assuming an extremely severe temperature condition lasting 3 minutes (180 seconds) at 120°C as the maximum condition of the lubricating oil operating temperature at its peak, in the lubrication state that takes into account the viscosity characteristics of the lubricating oil to this assumed peak temperature condition. The threshold value for setting the ratio R _ACTUAL /R of the actual radius of curvature R _ACTUAL and the set radius of curvature R that does not cause a sudden temperature rise is determined as the flange lubrication coefficient. Rim lubrication coefficient = 120°C viscosity x (oil film thickness h) ² /180 seconds. The oil film thickness h is determined from Karna's equation. From the viewpoint of the contact surface pressure between the large end surface 33 and the large collar surface ^12a , the oil film thickness h, the skew angle, and the oil film parameters, R _ACTUAL / It is practical if R is set.

In the case of turbine oil ISO viscosity grade VG32, which is a lubricating oil often used in transmissions, the 120°C viscosity is 7.7 cSt (=7.7 mm ² /s). The 120° C. viscosity of VG32 is low, and the lubrication conditions are extremely severe when the viscosity of the lubricating oil is taken into account in addition to the assumed peak temperature conditions. For this reason, the aforementioned R _ACTUAL /R is preferably 0.8 or more. Further, in the case of SAE 75W-90, which is a gear lubricating oil often used in differentials, R _ACTUAL /R is preferably 0.5 or more.

The _ratio of the set radius of curvature R of _the large end face 33 of the tapered roller 30 shown in FIG. As shown in FIG. 7, R _BASE is related to the ability to form an oil film at the sliding contact portion between the large end surface 33 and the large flange surface 12a. The maximum Hertzian stress p at the sliding contact portion between the large brim surface 12a and the large end surface 33 decreases as R/R _BASE increases. Furthermore, the smaller the R/R _BASE , the larger the skew angle.

If the thickness of the oil film formed at the sliding contact portion between the large end surface 33 and the large flange surface 12a shown in FIG. 4 is t, then the vertical axis in FIG. 7 is the oil film thickness when R/R _BASE is 0.76. It is expressed as the ratio t/t ₀ to t ₀ . From FIG. 7, the oil film thickness t reaches a maximum when R/R _BASE is 0.76, and when R/R _BASE exceeds 0.9, the oil film thickness t rapidly decreases. In terms of the optimum value of the oil film thickness, it is particularly preferable that R/R _BASE is 0.75 or more and 0.87 or less.

In this tapered roller bearing, as described above, the width A of the grinding relief 13 is made small and the width W of the large collar surface 12a is widened toward the grinding relief 13 side, thereby improving the contact condition with the large end surface 33 of the tapered roller 30. Since the large flange surface 12a has been optimized so as to maintain R/R _BASE and R _{ACTUAL /R, it is also possible to widen the allowable ranges for each of R/R BASE and R ACTUAL} /R.

Specifically, R/R _BASE may be 0.70 or more and 0.95 or less, preferably 0.70 or more and 0.90 or less, and most preferably 0.75 or more and 0.87 or less.

Further, R _ACTUAL /R may be 0.3 or more, preferably 0.5 or more, and most preferably 0.8 or more. Regarding the finished tapered roller 30 in which R _ACTUAL /R is in the range of 0.3 or more and less than 0.5, there may be some slight movement of the sliding contact part, such as skew of the tapered roller 30 or collapse of the large flange 12 due to a large moment load. Even if there is a disturbance, good contact with the large end surface 33 of the tapered roller 30 can be maintained by optimizing the large collar surface 12a as described above.

Therefore, among the plurality of tapered rollers 30, it is assumed that finished tapered rollers 30 with R/R _BASE of 0.70 or more and 0.95 or less and R _ACTUAL /R of 0.3 or more and less than 0.5 are included. By allowing this, the yield of tapered rollers 30 can be improved.

The oil film parameter described above depends on the combined roughness of the large end surface 33 of the tapered rollers 30 and the large flange surface 12a of the inner ring 10. By mirror-finishing the large end surface 33 and the large flange surface 12a, it is possible to improve oil film formation and maintain a good oil film thickness. Specifically, the surface roughness of the large flange surface 12a is 0.1 μmRa or less, preferably 0.08 μmRa or less. Further, the surface roughness of the large end surface 33 is 0.12 μmRa or less, preferably 0.1 μmRa or less. Here, surface roughness refers to the arithmetic mean roughness Ra specified in JIS standard B0601:2013 "Geometric Product Specification (GPS) - Surface Texture: Contour Curve Method - Terms, Definitions and Surface Texture Parameters" means.

In addition, in order to prevent the large end surfaces 33 of the tapered rollers 30 from sliding into contact (edge contact) with the outer diameter side edge of the large flange surface 12a of the inner ring 10, a space between the large flange surface 12a and the flange chamfer 12c shown in FIG. A relief surface may also be formed. An example of the modification is shown in FIG. As shown in the figure, a relief surface 12d is formed between the large collar surface 12a and the collar side chamfer 12c. The flank surface 12d is curved toward the outer diameter surface 12b from the outer diameter side edge of the large collar surface 12a toward the collar side chamfer 12c. The generatrix of the flank surface 12d is in the shape of a circular arc line with a radius of curvature Rd.

Here, consider an imaginary intersection between an imaginary line extending the generatrix of the large tsuba surface 12a and an imaginary line extending the generatrix of the collar side chamfer 12c, and move from the imaginary intersection in a direction along the generatrix of the large tsuba surface 12a. The width _L1 of the flange chamfer 12b is defined as the distance to the position with the same diameter as the outer diameter surface 12b. The distance up to this point is defined as the width _L2 of the flank surface 12d. In order to prevent the width _L2 of the flank surface 12d from becoming too small, the radius of curvature Rd of the flank surface 12d is preferably 2 mm or less. Furthermore, in order to increase the width _L2 of the flank 12d, the width _L1 of the collar chamfer 12c is preferably 1 mm or less.

Further, it is preferable to further improve the function by optimizing the large flange surface 12a of the inner ring 10 as shown in FIGS. 1, 3, and 8, and by combining the heat treatment characteristics of the inner ring 10. That is, if the lubrication conditions in the sliding contact between the large end surface 33 of the tapered roller 30 and the large flange surface 12a are severe, there is a risk of surface damage due to metal contact, so the large flange surface 12a side is provided with characteristics that delay surface damage. Good.

Specifically, it is preferable that the grain size number of the prior austenite crystal grains in the large flange surface 12a of the inner ring 10 is No. 6 or higher. Here, the grain size number of the old austenite grain is defined as JIS standard G0551:2013 "Steel - Microscopic test method for grain size". Prior austenite crystal grains refer to austenite crystal grains after quenching. The boundaries (grain boundaries) between crystal grains of prior austenite are called prior austenite grain boundaries, and those surrounded by the prior austenite grain boundaries are prior austenite grains. The finer the grain size of the prior austenite crystal grains (the larger the grain size number), the more the progress of damage can be delayed by the grain boundaries. For this reason, for the metal base material structure in sliding contact such as the large flange surface 12a, grain size number 6 or higher is suitable, grain size number 10 or higher is more preferred, and grain size number 11 or higher is even more preferred.

Further, the large flange surface 12a of the inner ring 10 is preferably formed of a nitrided layer with a nitrogen content of 0.05 wt% or more, or the nitrogen penetration depth is preferably 0.1 mm or more. A nitrided layer with a nitrogen content of 0.05 wt% or more has temper softening resistance due to its nitrogen enrichment effect. Therefore, resistance to local heat generation due to sliding contact of the large flange surface 12a is increased. The nitrided layer is a layer with increased nitrogen content formed on the surface layer of the large flange surface 12a, and is realized by, for example, treatments such as carbonitriding, nitriding, and nitriding. The nitrogen content in the nitrided layer is preferably 0.1 wt% or more and 0.7 wt% or less. If the nitrogen content is 0.1wt% or more, it can be expected that the rolling life will be improved, especially under conditions of foreign matter contamination, but if it exceeds 0.7wt%, pores called voids may be formed or there may be too much retained austenite. There is a growing concern that the hardness will be lost and the lifespan will be shortened. The nitrogen content is a value in the surface layer 10 μm of the large flange surface 12a after grinding, and can be measured using, for example, an EPMA (wavelength dispersive X-ray microanalyzer).

The inner ring 10, outer ring 20, and tapered rollers 30 shown in FIG. 2 are made of high carbon chromium bearing steel (for example, SUJ2 material). These inner ring 10, outer ring 20, and tapered rollers 30 are subjected to heat treatment to form a nitrided layer. This heat treatment method may be the method disclosed in Patent Document 3, or may be another method. The materials of the inner ring 10, outer ring 20, and tapered rollers 30 are not limited to high carbon chromium bearing steel. For example, the inner ring 10 and the outer ring 20 may be made of carburized steel such as chromium steel or chromium molybdenum steel, and conventional carburizing, quenching and tempering may be applied as the heat treatment.

Tests were conducted to verify the effectiveness of this tapered roller bearing. The verification conditions and basic specifications of the test product in the first test are as follows (see FIGS. 1 to 3 as appropriate below).
<Verification conditions>
・Test bearing: Model number 32007X (JIS metric standard tapered roller bearing)
・Bearing size: φ35×φ62×18
・ Lubricating oil: Turbine oil ISO VG32 (viscosity 32mm ² /s @ 40
°C, 5.5 mm ² /s @ 100 °C)
・ Load conditions: Radial load = 0.3Cr (Cr is basic dynamic load rating)
・Rotation speed: 4000r/min
・Lubricating oil amount: Dripping oil amount 8 mL/min
<Quality of test product>
・_RACTUAL /R=0.54
- Width W of large tsuba surface 12a = 1.69
・Surface roughness of large flange surface 12a = 0.039μmRa
・Surface roughness of large end surface 33 = 0.032μmRa
・R/R _BASE = 0.75

In the first test, in addition to the above-mentioned basic specifications, the width RC of the chamfer 32 of the tapered roller 30 and the groove width A of the grinding relief 13 were set to be different, with the ratio of the conical angle β and the angle ρ being constant, as shown below. We evaluated various differences in specifications. Table 1 shows the evaluation results.

As shown in Table 1 above, when β/ρ is 8.0, the temperature rises even under severe lubrication conditions for test products 1 to 3 where the width RC of the chamfer 32 is 0.69 mm and the width A is less than the width RC. It is possible to suppress this and obtain sufficient bearing life. In test sample 4, the width RC was set to 0.65 mm, which is smaller than that of test sample 3, but the Nusumi width A was set to 0.77 mm, which is larger than width RC, which makes it easier to raise the temperature, but does not have a negative impact on the bearing life. The temperature is not high enough to cause damage. In test specimens 5 and 6 in which the width RC was further reduced and the width A was further increased, temperature rise could not be suppressed, and bearing life could not be expected. In other words, when β/ρ = 8.0 (β/8 = ρ), setting the width RC to 0.7 mm or less and making the Nusumi width A < width RC will suppress the temperature rise even under severe lubrication conditions. It is considered to be effective.

The verification conditions and basic specifications of the test product in the second test are as follows.
<Verification conditions>
・Test bearing: Model number 32007X (JIS metric standard tapered roller bearing)
・Bearing size: φ35×φ62×18
・ Lubricating oil: Turbine oil ISO VG32 (viscosity 32mm ² /s @ 40
°C, 5.5 mm ² /s @ 100 °C)
・ Load conditions: Radial load = 0.3Cr (Cr is basic dynamic load rating)
・Rotation speed: 4000r/min
・Lubricating oil amount: Dripping oil amount 8 mL/min
<Quality of test product>
・_RACTUAL /R=0.61
- Width W of large tsuba surface 12a = 1.71
・Surface roughness of large flange surface 12a = 0.023μmRa
・Surface roughness of large end surface 33 = 0.025μmRa
・R/R _BASE = 0.76

In the second test, in addition to the above-mentioned basic specifications, various tests were carried out in which the width RC of the chamfer 32 of the tapered roller 30 and the ratio of the cone angle β to the angle ρ were varied while keeping the width A constant. Differences in specifications were evaluated. Table 2 shows the evaluation results.

As shown in Table 2 above, when the width A is 0.7 mm, the test products 7 to 9, in which the width RC of the chamfer 32 is 0.65 mm and β/ρ is 7.1 or more, can be heated even under severe lubrication conditions. It is possible to suppress the rise and obtain sufficient bearing life. In test product 10, the width RC was set to 0.55 mm, which is smaller than test products 7 to 9, but β/ρ was set to 6.7, which is smaller than test products 7 to 9, making it easier to increase the temperature. The temperature should not reach a level that would adversely affect bearing life. In test specimens 11 and 12 in which the width RC was further reduced and β/ρ was further reduced, temperature rise could not be suppressed, and a long bearing life could not be expected. In other words, when the width A is 0.7 mm, setting the width RC to less than 0.7 mm and making β/ρ≧7 (β/7≧ρ) is effective in suppressing temperature rise even under severe lubrication conditions. It is thought that.

Considering the results of the first test and the second test together, setting the width RC to 0.7 mm or less, Nusumi width A < width RC, and β/7 ≥ ρ means that the temperature will increase even under severe lubrication conditions. It is considered to be particularly effective in suppressing

As described above, this tapered roller bearing has a particularly small dimension in which the width RC of the chamfer 32 of the tapered roller 30 is 0.7 mm or less, and the clearance width A<width RC of the grinding relief, so that the large flange surface 12a The width W can be made wide enough to receive the large end surface 33 of the tapered roller 30. For this reason, the contact relationship between the large flange surface 12a and the large end surface 33 is optimized, and the wedge effect acting between the large flange surface 12a and the large end surface 33 is well exerted, and the large flange surface 12a and the large end surface The ability to form an oil film at the sliding contact portion of No. 33 can be improved.

In addition, in this tapered roller bearing, since the conical angle β/7 of the tapered rollers 30≧the angle ρ, the radial contact height H of the large flange surface 12a of the inner ring 10 and the large end surface 33 with respect to the reference point _O2 is low. It is possible to prevent an increase in the sliding speed at the sliding contact portion between the large flange surface 12a and the large end surface 33, suppress the amount of heat generated by the large flange surface 12a, and prevent a sudden temperature rise.

In this way, this tapered roller bearing optimizes the contact relationship between the large flange surface 12a of the inner ring 10 and the large end surface 33 of the tapered rollers 30, improves the ability to form an oil film at the sliding contact part, and improves the sliding contact. Since it is possible to prevent the sliding speed from increasing at the parts, even when tapered roller bearings are used under severe lubrication conditions, sudden temperature rises can be prevented and the bearings can rotate smoothly.

For example, if the lubrication conditions are particularly severe and the lubrication of the sliding contact portion between the large flange surface 12a and the large end surface 33 is at the level of a boundary film, it is possible that the large flange surface 12a side will wear out. If the wear of the large flange surface 12a reaches the grinding relief 13 and the large end surface 33 and the inner diameter side edge of the large flange surface 12a come into contact with each other, a large stress concentration occurs, causing instability in the sliding behavior of the tapered rollers 30. occurs, raising concerns about rapid temperature rise. On the other hand, in this tapered roller bearing, even if the large flange surface 12a wears out, the width W of the large flange surface 12a is wide and it can be sufficiently opposed to the large end surface 33, and the grinding relief 13 (width A) is small. Because of the small size, the wear of the large flange surface 12a does not reach the boundary with the grinding relief 13 (the inner diameter side edge of the large flange surface 12a), and the inner diameter side edge area of the large flange surface 12a is maintained. In particular, even when the lubrication conditions are severe, the state in which the large flange surface 12a and the large end surface 33 are in proper contact can be maintained.

In addition, this tapered roller bearing has an approach angle a>b of the grinding relief 13 of the inner ring 10 and a width A<B, so that the grinding relief 13 has excellent lathe machinability, and the amount of grinding of the large flange surface 12a When it moves back and forth, it does not easily affect the amount of change in the width W of the large flange surface 12a (dimension of the width A), and the grinding process of the large flange surface 12a does not become difficult. Therefore, this tapered roller bearing has no concerns about processing costs and does not require particularly high costs.

Further, in this tapered roller bearing, since the depth of the grinding relief 13 of the inner ring 10 is c>d, the stress in the large flange 12 caused by the load applied from the large end surface 33 of the tapered roller 30 to the large flange surface 12a of the inner ring 10 is can be reduced, and the strength of the large tsuba 12 can be improved. This is advantageous in suppressing the collapse of the large flange 12 due to external disturbances, etc., and maintaining an appropriate state of contact between the large flange surface 12a and the large end surface 33.

Further, in this tapered roller bearing, since the depth d of the grinding relief 13 of the inner ring 10 is 0.3 mm or less, the strength of the large flange 12 can be surely improved.

In addition, in this tapered roller bearing, since the approach angle a of the grinding relief 13 of the inner ring 10 is in the range of 20°≦a≦50°, even if the amount of grinding of the large flange surface 12a fluctuates, the large flange surface 12a The amount of change in the width W (the width A) has a gentle influence on the dimensions, and the width W (the width A) of the large flange surface 12a can be easily controlled.

In addition, in this tapered roller bearing, since the width W of the large flange surface 12a of the inner ring 10 is a value that satisfies the above formula 1, the large flange surface 12a is sufficiently opposed to the large end surface 33 of the tapered roller 30, Good contact can be maintained even when the sliding contact portion between the large end surface 33 and the large flange surface 12a rises toward the outer diameter side of the large flange due to disturbance.

Furthermore, in this tapered roller bearing, the grain size number of the prior austenite crystal grains on the large flange surface 12a of the inner ring 10 is No. 6 or higher, so that surface damage due to metal contact with the large end surface 33 of the tapered roller 30 can be delayed. can.

In addition, in this tapered roller bearing, the large flange surface 12a of the inner ring 10 is formed of a nitrided layer with a nitrogen content of 0.05 wt% or more, thereby retarding surface damage caused by metal contact with the large end surface 33 of the tapered roller 30. can be done.

Further, in this tapered roller bearing, the large flange surface 12a of the inner ring 10 has a surface roughness of 0.1 μmRa or less, and the large end surface 33 of the tapered roller 30 has a surface roughness of 0.12 μmRa or less, so the large flange surface It is possible to improve oil film formation between the oil film 12a and the large end face 33 by improving oil film parameters.

Further, in this tapered roller bearing, R/R _BASE is 0.70 or more and 0.95 or less, and R _ACTUAL /R of at least one tapered roller 30 among the plurality of tapered rollers 30 is 0.3 or more and 0. Even if it is less than 5, it can be used under severe lubrication conditions, and the yield of the tapered roller 30 can be improved compared to the tapered roller bearing disclosed in Patent Document 3, and it can be provided at a relatively low cost. can.

This tapered roller bearing is used to support the rotating shaft of an automobile transmission or differential, and is suitable for supplying lubricating oil from the outside to the inside of the bearing by splashing or oil bath lubrication. An example of its use will be explained based on FIG. 9. FIG. 9 shows an example of an automobile differential.

The differential shown in FIG. 9 includes a drive pinion 104 rotatably supported on a housing 101 by two tapered roller bearings 102 and 103, a ring gear 105 that meshes with the drive pinion 104, and a differential gear mechanism (not shown). These are housed in a housing 101 filled with gear lubricating oil. This gear lubricating oil also serves as lubricating oil for each tapered roller bearing 102, 103, and is supplied to the side surface of the bearing by splashing or oil bath lubrication.

Another usage example of this tapered roller bearing will be explained based on FIG. 10. FIG. 10 shows an example of an automobile transmission.

The transmission shown in FIG. 10 is a multi-stage transmission that changes the gear ratio in stages, and a tapered roller bearing 202 rotatably supports its rotating shaft (for example, an input shaft 201 to which engine rotation is input). - 205 is provided with a tapered roller bearing according to any of the embodiments described above. The illustrated transmission switches the gear trains 206 and 207 to be used by selectively engaging a clutch (not shown), thereby changing the gear ratio of the rotation transmitted from the input shaft 201 to the output shaft side. Further, in this transmission, the lubricating oil (transmission lubricating oil) is splashed as the gears rotate, so that the lubricating oil is applied to the sides of each of the tapered roller bearings 202 to 205.

The tapered roller bearings 102, 103, 202 to 205 illustrated in FIGS. 9 and 10 correspond to the tapered roller bearings shown in FIG. However, during the initial lubrication at the start of operation, it prevents sudden temperature rise due to sliding contact between the large flange surface of the inner ring and the large end surface of the tapered roller, and is stable even when the operating temperature rises and the viscosity of the lubricating oil decreases. It is possible to maintain a good sliding contact and form a good oil film, thereby preventing damage to both surfaces.

However, this tapered roller bearing is not limited to transmission applications, but can be applied to other applications requiring extremely severe lubrication conditions. The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. Therefore, the scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

10 Inner ring 11 Raceway surface 12 Large flange 12a Large flange surface 13 Grinding relief 20 Outer ring 30 Tapered roller 31 Rolling surface 32 Chamfer 33 Large end surface 102, 103, 202-205 Tapered roller bearing 104 Drive pinion (rotating part)
201 Input shaft (rotating part)

Claims (11)

It comprises an inner ring, an outer ring, a plurality of tapered rollers arranged between the inner ring and the outer ring, and a cage that accommodates these tapered rollers,
The tapered roller has a rolling surface formed in a conical shape, a chamfer continuous to the large diameter side of the rolling surface, and a large end surface continuous to the chamfer,
A tapered roller in which the inner ring has a raceway surface formed in a conical shape, a large flange surface that receives a large end surface of the tapered roller, and a grinding relief formed in a groove shape that connects the large flange surface and the raceway surface. In bearings,
The intersection of an imaginary line extending the generatrix of the raceway surface to the grinding relief side and an imaginary line extending the generatrix of the large flange surface to the grinding relief side is set as a reference point, and from the reference point to the large flange surface. When the width of the tapered roller is A, and the width that the chamfer of the tapered roller has in the direction along the generatrix of the large flange surface is RC, the width RC is 0.7 mm or less, and A<RC,
Let β be the conical angle of the rolling surface, and let ρ be the acute angle that an imaginary line connecting the contact point between the large flange surface and the large end face of the tapered roller to the vertex of the conical angle β makes with the generatrix of the raceway surface. A tapered roller bearing characterized in that β/7≧ρ. When the approach angle of the grinding relief to the large flange surface of the inner ring is a, and the approach angle of the grinding relief to the raceway surface is b, a>b,
The tapered roller bearing according to claim 1, wherein A<B, where A is a width from the reference point to the large flange surface, and B is a width from the reference point to the raceway surface. The tapered roller bearing according to claim 1 or 2, wherein c>d, where c is the depth of the grinding relief with respect to the raceway surface of the inner ring, and d is the depth of the grinding relief with respect to the large collar surface. The tapered roller bearing according to any one of claims 1 to 3, wherein the depth d is 0.3 mm or less, where d is the depth of the grinding relief relative to the large flange surface of the inner ring. The tapered roller bearing according to any one of claims 1 to 4, wherein 20°≦a≦50°, where a is an approach angle of the grinding relief with respect to the large flange surface of the inner ring. The acute angle formed by the generatrix of the raceway surface with the central axis of the inner ring is θ, the large end diameter of the rolling surface of the tapered roller is Dw, the length of the tapered roller is L, and the large flange surface The tapered roller bearing according to any one of claims 1 to 5, wherein the width W is a value satisfying the following formula 1.
W≧{Dw×(1/2)×Tanθ/(L/Dw)}...Formula 1 7. The tapered roller bearing according to claim 1, wherein the grain size number of the prior austenite crystal grains on the large flange surface of the inner ring is No. 6 or higher. The tapered roller bearing according to any one of claims 1 to 7, wherein the large flange surface of the inner ring is formed of a nitrided layer having a nitrogen content of 0.05 wt% or more. The tapered roller according to any one of claims 1 to 8, wherein the large flange surface of the inner ring has a surface roughness of 0.1 μmRa or less, and the large end surface of the tapered roller has a surface roughness of 0.12 μmRa or less. bearing. When the set radius of curvature of the large end face of the tapered roller is R, and the basic radius of curvature from the vertex of the conical angle of the rolling surface to the large flange surface of the inner ring is R _BASE , R/R _BASE is 0.70. 0.95 or less,
Any one of claims 1 to 9, wherein R _ACTUAL /R of at least one tapered roller among the plurality of tapered rollers is 0.3 or more, where R _ACTUAL is the actual radius of curvature of the large end surface of the tapered roller. The tapered roller bearing described in item 1. The tapered roller bearing according to any one of claims 1 to 10, which supports a rotating part included in a transmission or a differential of an automobile.

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