JP2007170418A - Tapered roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To extend the life of a bearing by forming a crowning shape providing uniform contact surface pressure even if misalignment occurs in a front surface combination tapered roller bearing used for a worn gear reduction gear. <P>SOLUTION: A pair of tapered roller bearings 1 are used in front surface combination. One of an inner ring raceway surface 2a, an outer ring raceway surface 3a and a roller rolling surface 4a of the tapered roller bearing 1 has crowning. The crowning shape has a drop quantity of crowning on a small diameter side of the roller 4 in the inner ring raceway surface 2a, outer ring raceway surface 3a and the roller rolling surface 4a, smaller than a drop quantity of crowning on a large diameter side of the roller 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tapered roller bearing used in a worm gear reducer, and more particularly to the shape of a crowning of a raceway surface or a roller rolling surface of a tapered roller bearing.

  In order to extend the rolling fatigue life of the tapered roller bearing, it is necessary to reduce the contact surface pressure of the rolling surface at the raceway surface of the inner and outer rings. In order to reduce the contact surface pressure under a certain load, it is important to make the surface pressure distribution in the axial direction uniform. As a method for this, the raceway surface of the inner ring or outer ring of the tapered roller bearing or the rolling surface of the roller is used. A crowning process for forming a curved surface is known.

There have been many proposals for crowning in the past. Typical examples include Patent Documents 1 to 10. In particular, in Patent Document 3, in a double-row roller bearing for a railway vehicle, the drop amount due to crowning at the contact portion between the roller and the inner and outer rings is increased on the bearing center side, or on the smaller diameter side with respect to the larger diameter side of the roller. The invention is an invention in which the drop amount by crowning is increased to make the stress distribution uniform, and is applied to a tapered roller bearing used in the back combination.
No. 02554882 (No. 5-22845) Japanese Utility Model Publication No. 5-89943 JP-A-8-232960 Japanese Patent Application Laid-Open No. 2000-257637 JP 2000-346078 A Japanese Unexamined Patent Publication No. 2001-65574 (US6390685B1) JP 2001-82114 A (US6311660B1) Japanese Patent Laid-Open No. 2001-124089 JP 2001-241446 A Japanese Patent Laid-Open No. 2002-235749

  In the worm gear reducer, in order to facilitate assembly, as shown in FIG. 1, two tapered roller bearings 1 are often used in a front combination.

  In the worm gear reducer, power is transmitted from the worm shaft to the worm wheel. At that time, in the tapered roller bearing that supports the output shaft to which the worm wheel is attached due to the load acting on the worm wheel, the roller moves the inner ring raceway surface on the large diameter side of the roller by the force acting on the roller from the inner ring collar. A moment is generated that acts to press. This moment causes a phenomenon in which the stress increases at the contact portion on the large diameter side of the roller and the rolling fatigue life is shortened. In particular, in order to achieve a long service life, it is possible to extend the fatigue life by applying a crowning process so that the contact surface pressure distribution acts without causing edge stress at the contact part between the roller and the bearing ring. It is necessary to plan.

Further, in the worm gear reducer in which the tapered roller bearing is used in the front combination, as shown in FIG. 2, the deflection of the shaft 10 and the deformation of the housing 11 may occur due to the radial load W from the gear or the like. In that case, the center lines of the inner ring 2 and the outer ring 3 of the tapered roller bearing 1 are not parallel to each other, and a certain inclination angle is generated. Such deformation of the bearing is called misalignment. When misalignment occurs, an uneven load acts on the contact portion between the raceway surface 4 of the inner ring 2 and the outer ring 3, and the contact surface pressure distribution is uneven as shown by B in FIG. Become. If the contact surface pressure distribution is not uniform, the maximum contact surface pressure increases, and the fatigue life of the bearing decreases. In particular, in the worm gear reducer, when the tapered roller bearing 1 is used in the front combination, the amount of interference between the inner ring 2 and the outer ring 3 on the large diameter side of the roller 4 increases, and the contact surface pressure is reduced. 4 becomes larger on the larger diameter side.
Even for such misalignment due to shaft deflection or housing deformation, it is necessary to perform crowning so as to obtain a uniform contact surface pressure distribution.

  An object of the present invention is to extend the life of a bearing in a front combination tapered roller bearing having a crowning shape that can obtain a uniform contact surface pressure even if misalignment occurs.

The tapered roller bearing of the present invention is a tapered roller bearing in which a pair is used in a front combination in a worm gear reducer, and any of the inner ring raceway surface, the outer ring raceway surface, and the roller rolling surface has a crowning. The crowning shape is characterized in that the drop amount of the crowning on the small diameter side of the roller on the inner ring raceway surface, the outer ring raceway surface, and the roller raceway surface is smaller than the drop amount of the crowning on the large diameter side of the roller.
With the configuration of the present invention, the shape of the crowning is such that the inner ring raceway surface is on the small flange side, the outer ring raceway surface is on the small diameter side of the roller, and the roller rolling surface is on the small diameter side of the roller. Therefore, the stress of the contact portion does not increase on the large diameter side of the roller, and when the misalignment occurs, the fatigue life can be extended by making the contact surface pressure distribution almost uniform.

In the present invention, it is preferable that the crowning apex is present on the small side of the inner ring raceway surface, on the small diameter side of the roller on the outer ring raceway surface, and on the small diameter side of the roller on the roller rolling surface.
The contact portion on the large diameter side of the roller can also be provided by having a crowning apex on the small diameter side of the inner ring raceway surface, on the small diameter side of the roller on the outer ring raceway surface, and on the small diameter side of the roller on the roller rolling surface. An increase in stress can be prevented more effectively, and the fatigue life can be extended.

Further, the tapered roller bearing of the present invention has a central portion of the cross section formed by a straight line in any or all of the inner ring raceway surface, the outer ring raceway surface, and the roller rolling surface, and has crowning at both ends thereof. In the crowning shape, the amount of crowning drop on the small collar side on the inner ring raceway surface, the amount of crowning drop on the small diameter side of the roller on the outer ring raceway surface, and the amount of crowning drop on the small diameter side of the roller on the roller rolling surface Is smaller than the drop amount of the other crowning.
Also in the case of the configuration of the present invention, as described above, the stress at the contact portion does not increase on the large diameter side of the roller, and when the misalignment occurs, the fatigue life can be extended with a substantially uniform contact surface pressure distribution.

  The shape of the crowning is an arc shape having a single curvature, a continuous arc shape formed by a plurality of arcs, a shape expressed by a logarithmic curve, or a shape that can be expressed by a general function shape It is good. An appropriate crowning shape can be selected in accordance with the situation in which the bearing is used or the processing convenience.

The tapered roller bearing of the present invention is a tapered roller bearing in which a pair is used in a front combination in a worm gear reducer, and any of the inner ring raceway surface, the outer ring raceway surface, and the roller rolling surface has a crowning. The crowning shape of the inner ring raceway surface, outer ring raceway surface, and roller raceway surface is such that the drop amount of the crowning on the small diameter side of the roller is smaller than the drop amount of the crowning on the large diameter side of the roller. The contact surface pressure at the inner ring and the outer ring can be made substantially uniform, and the fatigue life of the bearing can be extended.
Further, in any or all of the inner ring raceway surface, the outer ring raceway surface, and the roller rolling surface, the central portion of the cross section is formed in a straight line, and has crowning at both ends thereof. Is the drop amount of the crowning on the small side, the drop amount of the crowning on the small diameter side of the roller on the outer ring raceway surface, the drop amount of the crowning on the small diameter side of the roller on the roller rolling surface, and the drop amount of the other crowning When the misalignment is smaller, the contact surface pressure at the inner ring and the outer ring can be made substantially uniform when misalignment occurs, and the fatigue life of the bearing can be extended.

  A first embodiment of the present invention will be described with reference to FIGS. 3, 4 and 5. The tapered roller bearing 1 includes an inner ring 2, an outer ring 3, and a plurality of tapered rollers 4 interposed between the inner and outer rings 2 and 3. The inner ring 2 is formed with a raceway surface 2a having a conical surface on the outer periphery, and has a large collar 2b and a small collar 2c on the large diameter side and the small diameter side of the raceway surface 2a, respectively. The outer ring 3 is formed with a raceway surface 3a opposite to the raceway surface 2a of the inner ring 2 on the inner periphery, and is free of wrinkles. The outer periphery of the tapered roller 4 is formed as a rolling surface 4a, and is freely rollable between both the raceway surfaces 2a and 3a. Each tapered roller 4 is put in a pocket of a cage (not shown) and is held at a predetermined interval in the circumferential direction.

  The rolling surface 4a of the tapered roller 4 has a shape having a crowning, and chamfers 4aa and 4ab are obliquely formed at both ends. In the case of FIG. 3 and FIG. 4, full crowning is performed, and the crowning shape is an arc shape having a single curvature around the point O. The apex P of the crowning exists on the smaller diameter side than the center CC of the tapered roller 4 in the rotation axis direction, and the drop amount d1 on the small diameter side is smaller than the drop amount d2 on the large diameter side. The drop amounts d1 and d2 are distances from the tangent to the crowning vertex P to the end of the crowning.

  FIG. 5 is an example in which the roller rolling surface of FIG. 4 has a linear portion at the center of the roller rolling surface 4a. Both end portions of the roller rolling surface 4a are formed by circular arcs having a single curvature with the point O as the center. However, in the middle, it is divided by a straight portion to form two circular arcs at both ends, and the drop amount d1 on the small diameter side is smaller than the drop amount d2 on the large diameter side.

  If the crowning shape shown in FIG. 4 and FIG. 5 is used, when the misalignment occurs, the bias of the load acting on the contact surface with the raceway surface 4a of the raceway surfaces 2a and 3a of the inner and outer rings 2 and 3 is reduced. The contact surface pressure distribution can be made substantially uniform. For example, the contact surface pressure distribution when misalignment occurs is indicated by A in FIG. When this is compared with the case (B) where the crowning vertex is located at the axial center of the tapered roller 4, it can be seen that there is a difference in the magnitude of the maximum contact surface pressure. FIG. 11A shows the inner and outer ring raceway surfaces or roller rolling surfaces of the tapered roller bearing, the inner ring raceway surface on the small side, the outer ring raceway surface on the small diameter side, and the roller rolling surface. The example which calculated the contact surface pressure in case a crowning vertex exists in the small diameter side is represented.

As shown in FIG. 6, the crowning shape may be a continuous arc shape formed by a plurality of arcs. In this example, an arc centered on the point O1 and an arc centered on the point O2 are formed, and both arcs are smoothly continuous at the crowning apex P. Also in this case, the crowning apex P is present on the smaller diameter side than the center CC of the tapered roller 4 in the rotation axis direction, and the drop amount d1 on the small diameter side is smaller than the drop amount d2 on the large diameter side. Yes.
Further, the crowning shape may be a shape that can be expressed by a logarithmic curve or other general functional form other than the shape that can be expressed by an arc.
Moreover, as shown in FIG. 7, in the roller rolling surface 4a, the center part of the rolling surface in the cross section along an axial direction may be formed in the straight line, and crowning may be formed only in the roller both ends. Also in this case, the drop amount d1 on the small diameter side is smaller than the drop amount d2 on the large diameter side.
In either case, the contact pressure distribution can be made substantially uniform when misalignment occurs.

8, 9 and 10 show a second embodiment. In this embodiment, the raceways 2a and 3a of the inner ring 2 and the outer ring 3 are crowned. Both the raceway surfaces 2a and 3a are subjected to full crowning, and the crowning shape is an arc shape having a single curvature centered on the point Oin or the point Oout. The crowning vertices Pin and Pout are present on the smaller diameter side than the center CC of the tapered roller 4 in the rotational axis direction, and both the inner ring raceway surface 2a and the outer ring raceway surface 3a have a smaller diameter drop amount d1 on the larger diameter side. Is smaller than the drop amount d2.
Further, as shown in FIG. 10, the raceway surfaces 2a and 3a of the inner ring 2 and the outer ring 3 are formed such that the central part in the cross section along the radial direction is a straight line, and the crowning is formed only at both ends of the roller. good. Also in this case, the drop amount d1 on the small diameter side is smaller than the drop amount d2 on the large diameter side.
Also in this case, the same operation and effect as the case where the rolling surface 4a of the tapered roller 4 is crowned can be obtained.

  Also, for the raceways 2a and 3a of the inner ring 2 and the outer ring 3, the crowning shape is a continuous arc shape formed by a plurality of arcs, a shape expressed by a logarithmic curve, or a general function form. The shape can be expressed, and in this case, the same operation and effect as described above can be obtained.

(A) is the front view which represented a part of worm gear reducer where the tapered roller bearing was used by front combination, and (B) is the side view which represented the part in the cross section. It is explanatory drawing which shows the generation | occurrence | production state of misalignment. It is sectional drawing which abbreviate | omitted a part of tapered roller bearing concerning 1st Embodiment of this invention. It is a figure which shows the crowning shape of the bearing. It is a figure which shows a different crowning shape. It is a figure which shows further different crowning shape. It is a figure which shows further different crowning shape. It is sectional drawing which abbreviate | omitted a part of tapered roller bearing concerning 2nd Embodiment of this invention. It is a figure which shows the crowning shape of the bearing. It is a figure which shows the crowning shape of the same same bearing. It is a graph which shows distribution of contact surface pressure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Tapered roller bearing 2 ... Inner ring 2a ... Inner ring raceway surface 3 ... Outer ring 3a ... Outer ring raceway surface 4 ... Tapered roller 4a ... Roller rolling surface P, P1, P2, Pin, Pout ... Crowning vertex d1, d2, ... Drop amount

Claims (4)

  In the worm gear reducer, a pair of tapered roller bearings used in front combination, and any of the inner ring raceway surface, the outer ring raceway surface, and the roller rolling surface has a crowning, and the crowning shape is an inner ring raceway. A tapered roller bearing characterized in that a drop amount of the crowning on the small diameter side of the roller on the surface, outer ring raceway surface, and roller raceway surface is smaller than a drop amount of the crowning on the large diameter side of the roller.   2. The tapered roller bearing according to claim 1, wherein the inner ring raceway surface has a crowning apex on the small flange side, the outer ring raceway surface on the small diameter side of the roller, and the roller rolling surface on the small diameter side of the roller.   In a worm gear reducer, a pair of tapered roller bearings are used in front combination, and the central part of the cross section is formed by a straight line in any or all of the inner ring raceway surface, outer ring raceway surface and roller rolling surface It has a crowning at both ends, and the crowning shape is such that the inner ring raceway surface has a smaller crowning drop amount and the outer ring raceway surface has a smaller diameter crowning drop amount. The tapered roller bearing is characterized in that the drop amount of the crowning on the small diameter side of the roller is smaller than the drop amount of the other crowning.   In Claim 1 or Claim 3, the shape of the crowning is an arc shape having a single curvature, a continuous arc shape formed by a plurality of arcs, a shape expressed by a logarithmic curve, or a general shape Tapered roller bearings with shapes that can be expressed in functional form.

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