JP2007239929A - Roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller bearing which can reduce the rotational torque in a low-load application, assuring the load capacity in a high-load application. <P>SOLUTION: The roller bearing 10 is provided with an outer ring 11 having a track plane 11a in the inner peripheral surface, an inner ring 12 having a track plane 12a in the outer peripheral surface, and a plurality of rollers 13 rotatably arranged between both the track planes 11a, 12a. A crowning 14 is applied to the outer peripheral surface of the roller 13 to form a plurality of ridges 15 and bottoms 16 in the axial direction. In a predetermined load application, a plurality of the ridges 15 and bottoms 16 are brought in contact with the tack planes 11a, 12a by elastically deforming the outer peripheral surface of the roller 13 in the axial direction inward. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a roller bearing, and more particularly to a roller bearing used for a rotation support portion of various machines.

  Conventionally, by crowning the raceway surface of the bearing ring of the cylindrical roller bearing and arranging at least two peaks along the axial direction, edge loading is prevented and the cylindrical roller is brought into two-point contact with the raceway surface. A cylindrical roller bearing that stabilizes the cylindrical roller is known (for example, see Patent Document 1).

  As a technique for reducing the rotational torque of a tapered roller bearing, a tapered roller bearing in which various dimensions such as raceway surfaces of inner and outer rings and a radius of curvature of a tapered roller are optimized is known (for example, Patent Document 2 and 3).

  Furthermore, as a technology to suppress the temperature rise and rigidity reduction of the tapered roller bearing, a circumferential groove or a spiral groove is formed on either the rolling surface of the tapered roller or the raceway surface of the inner ring and the outer ring, and crowning is performed on the hill portion. A tapered roller bearing is known (for example, see Patent Document 4).

Japanese Utility Model Publication No. 62-199529 JP 2004-108429 A JP-A-11-210765 Japanese Utility Model Publication No. 62-822

  By the way, the main components of the rotational torque of the roller bearing are rolling friction, sliding friction, drag friction, cage friction, and buttocks sliding friction. The main components of the rotational torque of the ball bearing are rolling friction, drag friction, cage friction, ball spin friction, and gyro friction. Roller bearings have a larger load capacity than ball bearings and are suitable for use under high-load loads.

  However, the rolling element of the roller bearing is in line contact with the raceway surface of the race, and the rolling friction is lower than that of the ball bearing when the load is low compared to the point contact of the rolling element of the ball bearing. There is a problem that the torque increases and the rotational torque increases.

  The present invention has been made to eliminate such inconveniences, and an object of the present invention is to provide a roller bearing capable of reducing the rotational torque at the time of low load while securing the load capacity at the time of high load. Is to provide.

The above object of the present invention can be achieved by the following constitution.
(1) A roller bearing comprising an outer ring having a raceway surface on an inner peripheral surface, an inner ring having a raceway surface on an outer peripheral surface, and a plurality of rollers arranged to be freely rollable between both raceway surfaces, A plurality of crests and troughs are formed along the axial direction by crowning the outer peripheral surface of the roller, and a plurality of crests are formed by elastic deformation of the outer peripheral surface of the roller radially inward when a predetermined load is applied. And a valley bearing in contact with the raceway surface.
(2) The roller bearing according to (1), wherein the mountain portion has an arc-shaped cross section.
(3) The roller bearing according to (1), wherein the mountain portion has a trapezoidal cross section.

  According to the roller bearing of the present invention, a plurality of crests and troughs are formed along the axial direction by crowning the outer peripheral surface of the roller, so that only the top of the crest is in contact with the raceway surface when the load is low. Thus, a state close to a point contact or a partial line contact state is obtained. Thereby, rolling friction can be reduced and rotational torque can be lowered. In addition, since the roller has a plurality of crests on the outer peripheral surface, the stability of the rollers can be ensured even when the crest of the crest is close to point contact with the raceway surface. Sufficient bearing rigidity can be ensured. Furthermore, when a predetermined high load is applied, the plurality of crests and troughs come into contact with the raceway surface by elastic deformation in the radially inward direction of the outer circumference surface of the roller. As a result, the load capacity at high load can be secured.

  Hereinafter, each embodiment of the roller bearing according to the present invention will be described in detail with reference to the drawings applied to a tapered roller bearing.

(First embodiment)
First, with reference to FIG.1 and FIG.2, 1st Embodiment of the tapered roller bearing which concerns on this invention is described.
FIG. 1 is a cross-sectional view for explaining a first embodiment of a tapered roller bearing according to the present invention, and FIG. 2 is an enlarged view schematically showing a contact portion between the tapered roller and the raceway surface.

  As shown in FIG. 1, the tapered roller bearing (roller bearing) 10 of this embodiment includes an outer ring 11 having a raceway surface 11a on an inner peripheral surface, an inner ring 12 having a raceway surface 12a on an outer peripheral surface, and both raceway surfaces 11a. , 12a, and a plurality of tapered rollers (rollers) 13 disposed so as to roll freely.

  As shown in FIG. 2, the tapered roller bearing 10 of this embodiment is provided with two arcuate peaks 15 and 15 and one arcuate trough 16 by crowning the outer peripheral surface of the tapered roller 13. Are formed along the axial direction, and two crests 15 and 15 and one trough 16 are formed on the raceway surface 11a by elastic deformation of the outer peripheral surface of the tapered roller 13 radially inward when a predetermined high load is applied. , 12a.

  In the tapered roller bearing 10 configured as described above, as shown in FIG. 2, the top portions 15a and 15a of the two peak portions 15 and 15 of the tapered roller 13 are raceways 11a and 12a when no load and a low load are applied. , The contact portion between the tapered roller 13 and the raceway surfaces 11a and 12a becomes a state close to a point contact or a partial line contact state. Further, when a high load is applied, the two peak portions 15 and 15 and one trough portion 16 of the tapered roller 13 are in contact with the raceway surfaces 11a and 12a, and the contact portion between the tapered roller 13 and the raceway surfaces 11a and 12a is an axis. It is in a line contact state over almost the entire direction.

  As shown in FIG. 2, the tapered roller 13 is crowned by a distance from the end of the tapered roller 13 to the outer circumferential surface of the tapered roller 13 in the radial direction y from the raceway surface 11a (or 12a) at an arbitrary axial position x. Assuming that the amount is δ and the maximum crowning drop amount is δmax, δ can be obtained by the following equation (1). Here, in the formula (1), m is an elastic deformation amount when a desired rolling element is loaded when the tapered rollers 13 are not crowned and are flat. α is an additional amount of the elastic deformation amount of the tapered roller 13. L is a roller effective length.

In the tapered roller 13, the two crests 15 and 15 and the one trough 16 are elastically deformed inward in the radial direction when the rolling element is loaded (at a predetermined high load), and the raceways 11a and 12a are formed. However, since m is an elastic deformation amount assuming that there is no crowning, when there is crowning, line contact is made with a load smaller than the target rolling element load. Therefore, by applying α, the load that becomes line contact is aimed at and close to the rolling element load. In this embodiment, α = 1.2.
δ = (αm / 2) (cos (4πx / L) +1) − (1)

  According to the tapered roller bearing 10 of the present embodiment, the outer peripheral surface of the tapered roller 13 is crowned 14 to form the two peak portions 15 and 15 and one valley portion 16 along the axial direction. Sometimes, only the top portions 15a and 15a of the mountain portions 15 and 15 are in contact with the raceway surfaces 11a and 12a, resulting in a state close to point contact or a partial line contact state. Thereby, rolling friction can be reduced and rotational torque can be lowered. Moreover, since it has the two peak parts 15 and 15 in the outer peripheral surface of the tapered roller 13, the peak parts 15a and 15a of the peak parts 15 and 15 will be in the state close | similar to a point contact with respect to the track surfaces 11a and 12a. However, the stability of the tapered roller 13 can be ensured and sufficient bearing rigidity can be ensured. Further, when a predetermined high load is applied, the two crests 15 and 15 and the one trough 16 come into contact with the raceway surfaces 11a and 12a due to the elastic deformation of the outer peripheral surface of the tapered roller 13 in the radial direction. Since almost the entire outer peripheral surface of the roller 13 is in line contact with the raceway surfaces 11a and 12a, the load capacity at the time of high load load can be secured.

  In the case of a tapered roller bearing, on the small diameter side and the large diameter side, the small diameter side has a larger surface pressure and a lower peripheral speed than the large diameter side, so the radius of curvature R1 of the small diameter side peak portion is set to the large diameter side. By making it larger than the curvature radius R2 of the peak portion, the difference in the influence of the surface pressure and the peripheral speed on the small diameter side and the large diameter side can be reduced.

(Second Embodiment)
Next, a second embodiment of the tapered roller bearing according to the present invention will be described with reference to FIG. In addition, about the same or equivalent part as 1st Embodiment, the same code | symbol is attached | subjected to drawing, and the description is abbreviate | omitted or simplified.
FIG. 3 is an enlarged view schematically showing a contact portion between the tapered roller and the raceway surface of the second embodiment of the tapered roller bearing according to the present invention.

As shown in FIG. 3, the tapered roller bearing 20 of the present embodiment has a concave arc shape at the axial center of the outer peripheral surface of the tapered roller 23 provided with a convex arc-shaped crowning 24 a over the entire axial direction. By applying the crowning 24b, two arc-shaped peaks 25, 25 and one arc-shaped valley 26 are formed along the axial direction on the outer peripheral surface of the tapered roller 23, and at a predetermined high load load. The two crest portions 25 and 25 and the one trough portion 26 are brought into contact with the raceway surfaces 11a and 12a by elastic deformation of the outer peripheral surface of the tapered roller 23 inward in the radial direction. Thereby, the process of a tapered roller becomes easy compared with the said 1st Embodiment.
About another structure and an effect, it is the same as that of the said 1st Embodiment.

(Third embodiment)
Next, a third embodiment of the tapered roller bearing according to the present invention will be described with reference to FIG. In addition, about the same or equivalent part as 1st Embodiment, the same code | symbol is attached | subjected to drawing, and the description is abbreviate | omitted or simplified.
FIG. 4 is an enlarged view schematically showing a contact portion between a tapered roller and a raceway surface of a tapered roller bearing according to a third embodiment of the present invention.

  As shown in FIG. 4, the tapered roller bearing 30 of the present embodiment is provided with three arcuate peaks 35, 35, 35 and two arcuate troughs 36 by crowning the outer peripheral surface of the tapered roller 33. , 36 are formed along the axial direction, and three crests 35, 35, 35 and two troughs 36 are formed by elastic deformation radially inward of the outer peripheral surface of the tapered roller 33 when a predetermined high load is applied. , 36 is brought into contact with the raceway surfaces 11a, 12a. Thereby, since the number of the peak parts of the outer peripheral surface of a tapered roller is increased, compared with the said 1st Embodiment, the stability and bearing rigidity of a tapered roller can be improved.

In the case where the number of peak portions is three, the peak portion considering the influence of the surface pressure and the peripheral speed on the small diameter side and the large diameter side of the tapered roller bearing described for the case where the number of peak portions is two. The relationship between the radius of curvature R1 of the ridge on the small diameter side, the radius of curvature R3 of the ridge on the central portion, and the radius of curvature R2 of the ridge on the large diameter side is set as R1>R3> R2. The difference in the influence of the surface pressure and the peripheral speed between the small diameter side and the large diameter side can be reduced.
About another structure and an effect, it is the same as that of the said 1st Embodiment.

(Fourth embodiment)
Next, a fourth embodiment of the tapered roller bearing according to the present invention will be described with reference to FIG. In addition, about the same or equivalent part as 1st Embodiment, the same code | symbol is attached | subjected to drawing, and the description is abbreviate | omitted or simplified.
FIG. 5 is an enlarged view schematically showing a contact portion between a tapered roller and a raceway surface of a tapered roller bearing according to a fourth embodiment of the present invention.

As shown in FIG. 5, the tapered roller bearing 40 of the present embodiment is provided with a crowning 44 on the outer peripheral surface of the tapered roller 43 so that two trapezoidal peaks 45, 45 and one trapezoidal valley 46 are axially arranged. The two crests 45, 45 and the one trough 46 are formed on the raceway surfaces 11a, 12a by elastic deformation in the radial direction of the outer peripheral surface of the tapered roller 43 when a predetermined high load is applied. It is a thing made to contact. Thereby, since a peak part is made into a trapezoid shape and a top part is made into a linear shape, a fixed contact length can be ensured between the outer peripheral surface and raceway surface of a tapered roller until the time of predetermined high load load.
About another structure and an effect, it is the same as that of the said 1st Embodiment.

In addition, this invention is not limited to each embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.
For example, in each embodiment, the shape and size of the crest and trough formed on the outer peripheral surface of the tapered roller are set to be the same, but the shape and size of the crest and trough are the pressure generated in the tapered roller. It is arbitrarily set according to the distribution. Further, it can be equally applied to a cylindrical roller bearing.

  Below, the calculation performed in order to confirm the effect of the tapered roller bearing 10 (this Example) which concerns on this invention is demonstrated.

  For the calculation model of this example and comparative example of this calculation, a standard design tapered roller bearing HR33210J (inner diameter φ50 mm, outer diameter φ90 mm, width 32 mm) is used, and the main analysis condition is that the load is a pure axial load. The elastic deformation amount m was set to the rolling element load when P / C = 0.5.

  The tapered roller used in this example is the tapered roller 13 according to the first embodiment, and two arc-shaped peaks and one arc-shaped valley are along the axial direction on the outer peripheral surface of the tapered roller. Is formed.

  The tapered roller used in the comparative example is provided with a convex arc-shaped crowning over the entire axial direction, and one arc-shaped peak is formed along the axial direction on the outer peripheral surface of the tapered roller. Yes.

  In this calculation, the tapered roller and the raceway surface when the ratio of the dynamic equivalent load P and the basic dynamic load rating C of the above-described embodiment and comparative example is P / C = 0.2 and P / C = 0.5. And the contact lengths of the tapered roller, the outer ring raceway surface and the inner ring raceway surface in the range of P / C = 0.1 to 0.5 were calculated. The calculation results are shown in FIGS. 6 and 7, respectively.

  As is apparent from FIG. 6, when two crests and one trough are formed on the outer peripheral surface of the tapered roller as in the present embodiment, the surface pressure at the center of the roller is P / C = 0.2. It was confirmed that no surface pressure occurred, and when P / C = 0.5, it was confirmed that surface pressure was generated in the entire roller. Further, as apparent from FIG. 7, it was confirmed that the line contact length of the tapered roller increased stepwise up to the target rolling element load. From these calculation results, it was confirmed that the contact area of the tapered roller with respect to the raceway surface can be limited until the target rolling element load is reached, and that rolling friction can be reduced.

The rolling frictional resistance is obtained by the following formula (Source: NSK Technical Report CAT. No. 728e 2004 E-3 P. 170). In other words, by limiting the contact area, it is possible to reduce the effective length L _we rollers, can be reduced rolling friction M _R.

It is sectional drawing for demonstrating 1st Embodiment of the tapered roller bearing which concerns on this invention. It is the enlarged view which showed typically the contact part of a tapered roller and a track surface. It is the enlarged view which showed typically the contact part of the tapered roller and 2nd Embodiment of the tapered roller bearing which concerns on this invention. It is the enlarged view which showed typically the contact part of the tapered roller of 3rd Embodiment of the tapered roller bearing which concerns on this invention, and a raceway surface. It is the enlarged view which showed typically the contact part of the tapered roller and 4th Embodiment of the tapered roller bearing which concerns on this invention. It is a graph which shows the relationship between surface pressure distribution and the distance from a tapered roller edge part. It is a graph which shows the relationship between the contact length of a tapered roller, and P / C.

Explanation of symbols

10, 20, 30, 40 Tapered roller bearings (roller bearings)
11 outer ring 11a raceway surface 12 inner ring 12a raceway surface 13, 23, 33, 34 tapered roller (roller)
14, 24a, 24b, 34, 44 Crowning 15, 25, 35, 36 Mountain part 16, 26, 36, 46 Valley part

Claims (3)

A roller bearing comprising: an outer ring having a raceway surface on an inner circumferential surface; an inner ring having a raceway surface on an outer circumferential surface; and a plurality of rollers disposed so as to be able to roll between the both raceway surfaces,
The outer peripheral surface of the roller is crowned to form a plurality of crests and troughs along the axial direction, and the plurality of the outer peripheral surfaces of the rollers are elastically deformed radially inward when a predetermined load is applied. A roller bearing characterized in that a crest portion and a trough portion are brought into contact with the raceway surface.   The roller bearing according to claim 1, wherein the peak portion has an arc-shaped cross section. The roller bearing according to claim 1, wherein the peak portion has a trapezoidal cross section.

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