Tapered roller bearing

Abstract

This invention provides a low-cost tapered roller bearing that can form a sufficient oil film between the large end face of the tapered roller and the large flange of the inner ring, even when using low-viscosity lubricating oil. [Solution] The large flange 8 has a chamfered portion 17, a large flange surface 15 with a straight cross-section, a relief R portion 20 with a convex arc-shaped cross-section that curves away from the large end surface 9 of the conical roller 3, and a relief straight portion 21 that smoothly extends radially outward from the relief R portion 20 so as to be tangent to the relief R portion 20.

Description

Technical Field

[0001] This invention relates to a tapered roller bearing.

Background Art

[0002] In an automobile transmission (manual transmission (MT), automatic transmission (AT), dual clutch transmission (DCT), continuously variable transmission (CVT), transmission of a hybrid electric vehicle (HEV)), a speed reducer of an electric vehicle (EV), a differential mechanism of an automobile, etc., a tapered roller bearing, which is a bearing capable of simultaneously supporting a radial load and an axial load, is often used (for example, Patent Document 1).

[0003] A tapered roller bearing has an outer ring, an inner ring coaxially arranged radially inside the outer ring, and a plurality of tapered rollers incorporated at intervals in the circumferential direction between the outer ring and the inner ring. On the outer circumference of the inner ring, a tapered inner ring raceway surface with which a plurality of tapered rollers rollingly contact and a large collar formed to project radially outward from the large-diameter side end of the inner ring raceway surface are provided. When the bearing rotates, the large collar of the inner ring slidably contacts the large end face of the tapered roller while receiving a part of the axial load. Therefore, in a tapered roller bearing, it is important to ensure lubrication between the large end face of the tapered roller and the large collar of the inner ring.

[0004] Here, the applicant of the present application has already proposed the one in Patent Document 2 as a tapered roller bearing capable of improving the lubricity between the large end face of the tapered roller and the large collar of the inner ring. The tapered roller bearing of Patent Document 2 has a large collar surface having a straight cross section in which the large collar of the inner ring contacts the large end face of the tapered roller, and a relief R portion having a convex arc-shaped cross section that smoothly continues radially outside the large collar surface and curves in a direction away from the large end face of the tapered roller. The radially outer end of the relief R portion intersects a chamfer portion that slopes radially inward from the outer diameter surface of the large collar toward the tapered roller.

[0005] In the tapered roller bearing described in Patent Document 2, a wedge-shaped gap is formed between the large end face of the tapered roller and the relief radius portion of the large flange of the inner ring. As a result, lubricating oil is easily drawn into this wedge-shaped gap, providing excellent lubrication between the large end face of the tapered roller and the large flange of the inner ring. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2007-024168 [Patent Document 2] Japanese Patent Publication No. 2000-170775 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, there has been a trend towards miniaturizing automobile drive units in order to increase the interior space of automobiles. Furthermore, there is a trend towards increasing the output of automobile drive units, and in addition, there is a trend towards using lower viscosity lubricants than before in order to improve the fuel efficiency of automobiles. As a result, smaller bearings are required for use in automobiles, while the load on the bearings increases, and furthermore, it tends to become more difficult to form an oil film inside the bearings.

[0008] In particular, in tapered roller bearings, the large end face of the tapered roller and the large flange of the inner ring slide in contact, so it is important to ensure lubrication between the large end face of the tapered roller and the large flange of the inner ring. However, when low viscosity lubricant is used, it is difficult to form a sufficient oil film between the large end face of the tapered roller and the large flange of the inner ring. It will become more difficult to accomplish.

[0009] Therefore, the inventors of the present invention investigated whether it would be possible to further improve the lubricity between the large end face of the tapered roller and the large flange of the inner ring by further improving the tapered roller bearing of Patent Document 2 in order to make the tapered roller bearing compatible with low viscosity lubricating oil.

[0010] On the other hand, since low cost is required for bearings, it is preferable that the components of the bearings have a shape that can be processed in a short amount of time.

[0011] The problem that this invention aims to solve is to provide a low-cost tapered roller bearing that can form a sufficient oil film between the large end face of the tapered roller and the large flange of the inner ring, even when using low-viscosity lubricating oil. [Means for solving the problem]

[0012] To solve the above problems, this invention provides a tapered roller bearing with the following configuration. Outer ring and, An inner ring is coaxially arranged radially inward of the outer ring, It comprises a plurality of tapered rollers arranged between the outer ring and the inner ring at circumferential intervals, In a tapered roller bearing, the outer circumference of the inner ring is provided with a conical inner ring raceway surface on which the plurality of tapered rollers roll and make contact, and a large flange formed projecting radially outward from the large-diameter end of the inner ring raceway surface, The tapered roller bearing is characterized in that the large flange has a chamfered portion that slopes radially inward from the outer diameter surface of the large flange toward the tapered roller, a large flange surface with a cross-section that contacts the large end surface of the tapered roller, a relief R portion that smoothly extends radially outward from the large flange surface and has a convex arc-shaped cross-section that curves away from the large end surface of the tapered roller, and a relief straight portion that smoothly extends radially outward from the relief R portion so as to be tangent to the relief R portion and has a straight cross-section that intersects the chamfered portion.

[0013] In this configuration, the relief straight section with a straight cross-section has a greater contact angle hysteresis for the lubricating oil than the relief R section with a convex arc-shaped cross-section, and therefore has a higher ability to retain lubricating oil due to surface tension. As a result, it provides superior lubrication between the large end face of the conical roller and the large flange of the inner ring compared to a design where the entire area from the large flange to the chamfer is a relief R section without a relief straight section. Furthermore, it is possible to shorten the grinding time of the large flange compared to a design where the entire area from the large flange to the chamfer is a relief R section without a relief straight section, resulting in lower costs.

[0014] The ratio of the width dimension of the relief radius portion to the width dimension of the relief straight portion, when measured in a direction parallel to the large flange surface, can be set within the range of 9:1 to 3.5:6.5.

[0015] The relief straight portion is preferably formed at an angle of 2° to 15° with respect to the large flange surface.

[0016] By setting the angle between the relief straight section and the large flange surface to 2° or more, even if the tapered roller skews, it is possible to avoid the large end face of the tapered roller contacting the boundary between the relief straight section and the chamfered section, thereby preventing oil film breakdown between the large end face of the tapered roller and the relief straight section. Furthermore, by setting the angle between the relief straight section and the large flange surface to 15° or less, the grinding depth when forming the relief straight section and relief radius section by grinding can be effectively reduced, thereby effectively shortening the grinding time of the large flange.

[0017] If the tapered roller has a recessed portion formed by circularly concaving the center of the large end face of the tapered roller, it is preferable that the recessed portion is formed such that the boundary between the large end face of the tapered roller and the recessed portion is located radially inward from the radially outer end of the large flange face.

[0018] By doing so, even when the lubrication conditions of the bearing deteriorate and the large end face of the tapered roller wears due to contact with the large flange surface, the stable behavior of the tapered roller can be ensured. That is, if the nub is formed such that the boundary between the large end face of the tapered roller and the nub is located radially outside rather than radially inside the radial outer end of the large flange surface, a region where the large end face of the tapered roller does not come into contact with the large flange surface and does not wear will remain. Therefore, when the large end face of the tapered roller wears due to contact with the large flange surface, especially when skew or the like occurs, the contact state between the large end face of the tapered roller and the large flange becomes unstable, and the behavior of the tapered roller may become unstable. On the other hand, if the nub is formed such that the boundary between the large end face of the tapered roller and the nub is located radially inside the radial outer end of the large flange surface, the entire large end face of the tapered roller comes into contact with the large flange surface, and the large end face of the tapered roller wears over the entire surface. Therefore, even when the large end face of the tapered roller wears due to contact with the large flange surface, the contact state between the large end face of the tapered roller and the large flange becomes surface contact and stable, and the stable behavior of the tapered roller can be ensured.

[0019] It is preferable to set the distance from the intersection of the relief straight portion and the chamfered portion to the large flange surface in the range of 10 μm to 150 μm.

[0020] By setting the distance from the intersection of the relief straight portion and the chamfered portion to the large flange surface to be 10 μm or more, even when the tapered roller is skewed, the large end face of the tapered roller can be prevented from hitting the intersection of the relief straight portion and the chamfered portion, and local strong impact on the large end face of the tapered roller can be prevented. Also, by setting the distance from the intersection of the relief straight portion and the chamfered portion to the large flange surface to be 150 μm or less, the grinding depth when forming the relief straight portion, the relief R portion, and the large flange surface by grinding can be effectively suppressed, and the grinding time of the large flange can be effectively shortened.

[0021] It is preferable that the width dimension of the large flange surface is 1.5 mm or more.

[0022] By doing so, since the width dimension of the large chamfer surface is large, when performing superfinishing on the large chamfer surface, it is possible to use a superfinishing grindstone of a large size, and the accuracy of the inclination angle of the large chamfer surface can be improved.

[0023] Preferably, the surface roughness of the large chamfer surface is 0.08 μm Ra or less.

[0024] By doing so, since the surface roughness of the large chamfer surface is small, the skew of the tapered roller can be suppressed to be small.

Effect of the Invention

[0025] The tapered roller bearing of this invention has a relief straight portion that smoothly continues to the radially outer side of the relief R portion, and the relief straight portion having a straight cross section has a larger lubricating oil contact angle hysteresis and a higher ability to hold lubricating oil by surface tension than the relief R portion having a convex arc-shaped cross section. Therefore, the lubricity between the large end face of the tapered roller and the large chamfer of the inner ring is superior to that in the case where all of the portion from the large chamfer surface to the chamfer portion is made into a relief R portion without providing the relief straight portion. Also, the grinding time of the large chamfer can be shortened and the cost can be reduced compared to the case where all of the portion from the large chamfer surface to the chamfer portion is made into a relief R portion without providing the relief straight portion.

Brief Description of the Drawings

[0026] [Figure 1] Cross-sectional view of the tapered roller bearing according to an embodiment of this invention [Figure 2] Enlarged view of the vicinity of the contact portion between the tapered roller and the large chamfer in FIG. 1 [Figure 3] Enlarged view of the vicinity of the large chamfer surface in FIG. 2 [[ID=3l]] [Figure 4] Enlarged view of the vicinity of the relief R portion and the relief straight portion in FIG. 3 [[ID=Z3]] [Figure 5] Explanatory view showing the relationship between the tapered roller, the inner ring, and the cone center in FIG. 1 [Figure 6] View showing the grinding cost when forming the large chamfer surface, the relief R portion, and the relief straight portion of the large chamfer shown in FIG. 3 by grinding [Figure 7]Figure 8 shows the grinding allowance when forming the flange surface and relief radius of the large flange by grinding. [Figure 8] Figure 3 shows a comparative example where the relief straight section is omitted, and the entire area from the flange surface to the chamfered section is a relief radius. [Modes for carrying out the invention]

[0027] Figure 1 shows a tapered roller bearing according to an embodiment of the present invention. This tapered roller bearing comprises an outer ring 1, an inner ring 2 coaxially arranged radially inward of the outer ring 1, a plurality of tapered rollers 3 assembled between the outer ring 1 and the inner ring 2 at circumferential intervals, and a cage 4 that maintains the circumferential intervals of the plurality of tapered rollers 3.

[0028] The inner circumference of the outer ring 1 has a conical outer ring raceway surface 5 on which the tapered rollers 3 roll and make contact. The outer circumference of the inner ring 2 has a conical inner ring raceway surface 6 on which the tapered rollers 3 roll and make contact, a small flange 7 projecting radially outward from the small diameter end of the inner ring raceway surface 6, and a large flange 8 projecting radially outward from the large diameter end of the inner ring raceway surface 6.

[0029] The inner ring raceway surface 6 and the outer ring raceway surface 5 are radially opposite each other with a tapered roller 3 in between. The outer ring raceway surface 5 and the inner ring raceway surface 6 are conical surfaces that intersect at a common point (cone center O shown in Figure 5) located on the centerline of the inner ring 2. When the bearing rotates, each tapered roller 3 rotates on its own axis while revolving around the centerline of the inner ring 2 between the outer ring raceway surface 5 and the inner ring raceway surface 6. The large flange 8 contacts the large end surface 9 of the tapered roller 3 with sliding during bearing rotation, supporting a portion of the axial load.

[0030] The tapered roller 3 has a small end face 10 facing the small flange 7 of the inner ring 2, a large end face 9 facing the large flange 8 of the inner ring 2, a conical roller rolling surface 11 that rolls and contacts the outer ring raceway surface 5 and the inner ring raceway surface 6, a small diameter side roller chamfer 12 connecting the roller rolling surface 11 and the small end face 10, a large diameter side roller chamfer 13 connecting the roller rolling surface 11 and the large end face 9, and a recessed portion 14 (see Figure 2) in the center of the large end face 9 of the tapered roller 3.

[0031] As shown in Figure 2, the large flange 8 has a large flange surface 15 with a straight cross-section that contacts the large end face 9 of the tapered roller 3, a cylindrical outer diameter surface 16, and a chamfered portion 17 that slopes radially inward from the outer diameter surface 16 toward the tapered roller 3. A groove 18 with a concave arc-shaped cross-section is formed at the intersection of the large flange surface 15 and the inner ring raceway surface 6.

[0032] The width dimension a of the large flange surface 15 is set to 1.5 mm or more (preferably 1.6 mm or more, more preferably 1.7 mm or more) and 3.0 mm or less. The large flange surface 15 is a super-finished surface that has undergone super-finishing processing, and its surface roughness is set to 0.005 μmRa or more and 0.080 μmRa or less (preferably 0.050 μmRa or less). The chamfered portion 17 has a shape with a convex arc cross-section. The width dimension of the chamfered portion 17 when measured in a direction parallel to the large flange surface 15 is set to 0.2 mm or more (preferably 0.4 mm or more) and 1.2 mm or less. Setting the width dimension of the chamfered portion 17 to 0.2 mm or more (preferably 0.4 mm or more) can prevent dents and other defects, and setting the width dimension of the chamfered portion 17 to 1.2 mm or less can shorten the turning time when forming the chamfered portion 17.

[0033] As shown in Figure 3, the large flange 8 has a relief R portion 20 that smoothly extends radially outward from the large flange surface 15 and has a convex arc-shaped cross-section that curves away from the large end surface 9 (see Figure 2) of the tapered roller 3, and a relief straight portion 21 that has a straight cross-section that smoothly extends radially outward from the relief R portion 20 so as to be tangent to the relief R portion 20. The radius of curvature R of the cross-section of the relief R portion 20 is greater than the radius of curvature of the cross-section of the chamfered portion 17. As shown in Figure 4, the straight line of the cross-section of the relief straight portion 21 does not smoothly extend to the chamfered portion 17 so as to be tangent to the chamfered portion 17, but rather intersects with the chamfered portion 17 so as to form an intersection point.

[0034] As shown in Figure 2, the diameter e of the recessed portion 14, which is a circular recess in the center of the large end face 9 of the conical roller 3, is set such that the boundary between the large end face 9 and the recessed portion 14 (the lower end position of diameter e in the figure) is located radially inward (below in the figure) from the radial outer end of the large flange face 15 (the boundary between the large flange face 15 and the relief R portion 20; the upper end position of the width dimension a of the large flange face 15 in the figure).

[0035] As shown in Figure 3, the distance d from the intersection of the relief straight section 21 and the chamfered section 17 to the large flange surface 15 (hereinafter referred to as "relief drop amount d") is set in the range of 10 μm or more (preferably 15 μm or more, more preferably 20 μm or more) and 150 μm or less. The ratio of the width dimension b of the relief radius section 20 to the width dimension c of the relief straight section 21 when measured in a direction parallel to the large flange surface 15 is set in the range of 9:1 to 3.5:6.5. The width dimension b+c of the combined area of ​​the relief radius section 20 and the relief straight section 21 when measured in a direction parallel to the large flange surface 15 (hereinafter referred to as "relief width b+c") is set in the range of 15 to 60% of the width dimension a of the large flange surface 15.

[0036] As shown in Figure 4, the angle θ between the relief straight section 21 and the large flange surface 15 is set in the range of 2° to 15°.

[0037] As shown in Figure 5, the inclination angle α of the large flange surface 15 (the angle that the large flange surface 15 makes with respect to the direction perpendicular to the axis) is set to be perpendicular to the straight line connecting the contact point between the large flange surface 15 and the large end surface 9 of the tapered roller 3 and the cone center O. The angle ρ that this straight line makes with respect to the inner ring raceway surface 6 is set to be between β / 8 and β / 5 with respect to the central angle β of the tapered roller 3. When the angle ρ is β / 8 or larger, the large end surface 9 of the tapered roller 3 can be stably brought into contact with the large flange surface 15, and when the angle ρ is β / 5 or smaller, it is possible to suppress the temperature rise due to contact between the large end surface 9 of the tapered roller 3 and the large flange surface 15.

[0038] The inner ring 2 of the tapered roller bearing described above can be manufactured, for example, as follows. First, a raw material having a large flange 8 is formed by forging. Next, the large flange 8 of the raw material is turned to form the outer diameter surface 16 and chamfered portion 17 shown in Figure 6. Then, as shown in Figure 6, a grinding wheel G1 having shapes corresponding to the relief straight portion 21, the relief radius portion 20, and the large flange surface 15 is pressed against the large flange 8 to form the relief straight portion 21, the relief radius portion 20, and the large flange surface 15. After that, a superfinishing wheel is pressed against the portion of the large flange surface 15 to improve the surface roughness of the large flange surface 15.

[0039] As shown in Figure 3, this tapered roller bearing has a relief straight section 21 that smoothly extends radially outward from the relief R section 20. The relief straight section 21, with its straight cross-section, has a larger contact angle hysteresis for the lubricating oil than the relief R section 20, which has a convex arc-shaped cross-section, and therefore has a higher ability to retain the lubricating oil due to surface tension. As a result, as shown in Figure 8, it has superior lubrication between the large end face 9 of the tapered roller 3 and the large flange 8 of the inner ring 2 compared to a bearing without a relief straight section 21, where the entire area from the large flange surface 15 to the chamfered section 17 is the relief R section 20. Even when using low-viscosity lubricating oil, a sufficient oil film can be formed between the large end face 9 of the tapered roller 3 and the large flange 8 of the inner ring 2. The low-viscosity lubricating oil referred to here is 3-6 mm at an oil temperature of 100°C. 2 / second (The viscosity of conventional lubricating oils is 6-12 mm at an oil temperature of 100°C.) 2 It is ( / second).

[0040] Furthermore, as shown in Figure 3, this tapered roller bearing has a relief straight section 21 that smoothly extends radially outward from the relief R section 20. Therefore, as shown in Figure 8, it is possible to shorten the grinding time of the large flange 8 compared to a bearing where the relief straight section 21 is omitted and the entire area from the large flange surface 15 to the chamfered section 17 is made up of the relief R section 20.

[0041] A description will be given with reference to FIGS. 6 and 7. FIG. 6 is a diagram for explaining the grinding process of the large collar 8 having a relief straight portion 21 that smoothly continues to the radially outer side of the relief R portion 20 as shown in FIG. 3. In FIG. 6, the grinding wheel G1 has a shape corresponding to the relief straight portion 21, the relief R portion 20, and the large collar surface 15 shown in FIG. 3. By pressing this grinding wheel G1 against the large collar 8, grinding starts from the portion corresponding to the relief straight portion 21 (see FIG. 3), and finally, the shaded portion in the figure is cut off by the grinding wheel G1, thereby forming the relief straight portion 21, the relief R portion 20, and the large collar surface 15 shown in FIG. 3. The dimension s in FIG. 6 is the distance from the grinding wheel G1 to the machining start point of the large collar 8, and the dimension t1 in FIG. 6 is the distance from the portion of the grinding wheel G1 corresponding to the large collar surface 15 to the large collar 8.

[0042] On the other hand, FIG. 7 is a diagram for explaining the grinding process of the large collar 8 in which, as shown in FIG. 8, no relief straight portion 21 is provided and the entire portion from the large collar surface 15 to the chamfer portion 17 is made into the relief R portion 20. In FIG. 7, the grinding wheel G2 has a shape corresponding to the relief R portion 20 and the large collar surface 15. By pressing this grinding wheel G2 against the large collar 8, grinding starts from the relief R portion 20, and finally, the shaded portion in the figure is cut off by the grinding wheel G2, thereby forming the relief R portion 20 and the large collar surface 15. The dimension s in FIG. 7 is the distance from the grinding wheel G2 to the machining start point of the large collar 8, and the dimension t2 in FIG. 7 is the distance from the portion of the grinding wheel G2 corresponding to the large collar surface 15 to the large collar 8. The dimension s in FIG. 6 and the dimension s in FIG. 7 are of the same size.

[0043] Comparing FIGS. 6 and 7, the relationship s < t1 < t2 holds for the dimension s in FIGS. 6 and 7, the dimension t1 in FIG. 6, and the dimension t2 in FIG. 7. That is, the machining distance (grinding depth) of grinding in FIG. 6 is smaller than the machining distance (grinding depth) of grinding in FIG. 7. Therefore, as shown in FIG. 3, the grinding time of the large collar 8 when a relief straight portion 21 that smoothly continues to the radially outer side of the relief R portion 20 is provided can be shortened compared to the grinding time of the large collar 8 when, as shown in FIG. 8, no relief straight portion is provided and the entire portion from the large collar surface 15 to the chamfer portion 17 is made into the relief R portion 20.

[0044] As shown in Figure 4, in this tapered roller bearing, the angle θ that the relief straight portion 21 makes with respect to the large flange surface 15 is 2° or more. Therefore, even if the tapered roller 3 skews, the large end surface 9 of the tapered roller 3 is prevented from contacting the boundary between the relief straight portion 21 and the chamfered portion 17, and oil film breakdown between the large end surface 9 of the tapered roller 3 and the relief straight portion 21 can be prevented. In addition, since the angle θ that the relief straight portion 21 makes with respect to the large flange surface 15 is 15° or less, the grinding depth when forming the relief straight portion 21, the relief radius portion 20 and the large flange surface 15 by grinding can be effectively reduced, and the grinding time of the large flange 8 can be effectively shortened.

[0045] Furthermore, as shown in Figure 2, in this tapered roller bearing, the boundary between the large end face 9 of the tapered roller 3 and the recessed portion 14 is located radially inward from the radial outer end of the large flange surface 15. Therefore, even if the lubrication conditions of the bearing deteriorate and the large end face 9 of the tapered roller 3 wears down due to contact with the large flange surface 15, stable behavior of the tapered roller 3 can be ensured.

[0046] In other words, if the boundary between the large end face 9 and the concave portion 14 of the cone roller 3 is the large flange surface 15 If the recessed portion 14 is formed so as to be located radially outward rather than radially inward from the radial outer end, a region will remain on the large end face 9 of the tapered roller 3 that does not come into contact with the large flange surface 15 and therefore does not experience wear. In contrast, when the large end face 9 of the tapered roller 3 wears down due to contact with the large flange surface 15, especially if skew occurs, the contact state between the large end face 9 and the large flange 8 of the tapered roller 3 may become unstable, potentially leading to unstable behavior of the tapered roller. If the boundary between the large end face 9 of the tapered roller 3 and the tapered portion 14 is formed such that the boundary is located radially inward from the radial outer end of the large flange surface 15, the entire surface of the large end face 9 of the tapered roller 3 will be in contact with the large flange surface 15, and the large end face 9 of the tapered roller 3 will wear across its entire surface. As a result, even when the large end face 9 of the tapered roller 3 wears down due to contact with the large flange surface 15, the contact state between the large end face 9 of the tapered roller 3 and the large flange 8 will stabilize as surface contact, ensuring stable behavior of the tapered roller 3.

[0047] Furthermore, as shown in Figure 3, this tapered roller bearing has a relief drop amount d of 10 μm or more, so even if the tapered roller 3 skews, it is possible to avoid the large end face 9 of the tapered roller 3 contacting the intersection of the relief straight portion 21 and the chamfered portion 17, thereby preventing localized strong contact on the large end face 9 of the tapered roller 3. In addition, since the relief drop amount d is 150 μm or less, the grinding depth when forming the relief straight portion 21, the relief radius portion 20 and the large flange surface 15 by grinding can be effectively suppressed, and the grinding time of the large flange 8 can be effectively shortened.

[0048] Furthermore, in this tapered roller bearing, the width dimension a of the large flange surface 15 shown in Figure 3 is 1.5 mm or more (preferably 1.6 mm or more, more preferably 1.7 mm or more). Because the width dimension a of the large flange surface 15 is large, it is possible to use a larger size superfinishing grinding wheel when superfinishing the large flange surface 15, thereby improving the accuracy of the inclination angle α of the large flange surface 15 (see Figure 5). Specifically, the inclination angle α of the large flange surface 15 can be superfinished so that it falls within a range of ±15' (preferably ±10', more preferably ±7') of the design value set so that the angle ρ made by the straight line connecting the contact position of the large end surface 9 of the tapered roller 3, which is perpendicular to the large flange surface 15, and the cone center O, with respect to the inner ring raceway surface 6 is between β / 8 and β / 5 with respect to the central angle β of the tapered roller 3. This stabilizes the contact between the large end face 9 and the large flange face 15 of the tapered roller 3, making it possible to stably suppress the amount of skew of the tapered roller 3 even when using low-viscosity lubricant. Table 1 shows the relationship between the width dimension a of the large flange face 15 and the inclination angle α of the large flange face 15.

[0049] [Table 1]

[0050] Furthermore, this tapered roller bearing has a large flange surface 15 with a surface roughness of 0.08 μmRa or less. Because the surface roughness of the large flange surface 15 is small, it is possible to keep the skew of the tapered roller 3 to a minimum. Table 2 shows the relationship between the surface roughness of the large flange surface 15 and the amount of skew of the tapered roller 3.

[0051] [Table 2]

[0052] A sample of the tapered roller bearing according to the above embodiment was manufactured and evaluated. The configuration of the tapered roller bearing used at this time is as follows. • Bearing size: Inner ring inner diameter 70mm, outer ring outer diameter 150mm, bearing width 40mm • Width dimension a of the large flange 15: 3.5 mm • Surface roughness of flange 15: 0.078 μmRa • Clearance drop d: 60mm • Width dimension a of the chamfered part: 0.8 mm • Relief width b+c: 0.69mm

[0053] Furthermore, the test conditions are as follows: • Test axial load: P / C = 0.11 • Test rotation speed: 3000 r / min Lubrication conditions: The tapered roller bearing was immersed in lubricating oil (differential oil), removed, left for 30 minutes, and then operated without lubrication.

[0054] The results of the above test showed that seizure occurred between the large end face 9 and the large flange 8 of the tapered roller 3 400 seconds after the start of operation of the tapered roller bearing. On the other hand, when the same evaluation test was performed on a tapered roller bearing without relief radius 20 and relief straight section 21, seizure occurred 75 seconds after the start of operation of the tapered roller bearing. From these results, it can be seen that a tapered roller bearing with relief radius 20 and relief straight section 21 on the large flange 8 has approximately five times the lifespan compared to a tapered roller bearing without relief radius 20 and relief straight section 21 on the large flange 8.

[0055] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0056] 1 Outer ring 2 Inner ring 3 yen water droplet 6. Inner ring raceway surface 8 Large Brim 9 Big end face 14. Nusumi section 15 Large flange 16 Outer diameter surface 17 Chamfered section 20 Escape R Club 21 Escape Straight Section a. Width dimension of the large flange d Escape drop amount θ is the angle that the relief straight section makes with respect to the flange surface.

Claims

1. Outer ring (1) and, An inner ring (2) is coaxially arranged radially inward of the outer ring (1), The device comprises a plurality of tapered rollers (3) arranged between the outer ring (1) and the inner ring (2) at circumferential intervals, The outer circumference of the inner ring (2) is provided with a conical inner ring raceway surface (6) on which the plurality of tapered rollers (3) roll and make contact, and a large flange (8) formed projecting radially outward from the large diameter end of the inner ring raceway surface (6). In a tapered roller bearing in which the large end face (9) of the tapered roller (3) contacts the large flange face (15) of the large flange (8), The aforementioned conical roller (3) has a recessed portion (14) in the center of the large end face (9) of the conical roller (3), A tapered roller bearing characterized in that the boundary between the large end face (9) of the tapered roller (3) and the recessed portion (14) is located radially inward from the radially outer end of the large flange face (15).

2. The tapered roller bearing according to claim 1, wherein the width dimension (a) of the large flange surface (15) is 1.5 mm or more.

3. The tapered roller bearing according to claim 1 or 2, wherein the surface roughness of the large flange surface (15) is 0.08 μmRa or less.

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