JPH0447446Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention belongs to the technical field of tapered roller bearings.

[Conventional technology]

One of the problems with tapered roller bearings is that
Pseudo-indentation occurs due to relative slip in the axial direction between the inner and outer rings and the rolling elements caused by vibration.

This is because in the case of a tapered roller bearing, when it receives vibration from the direction perpendicular to the axis, a component force in the axial direction is generated between the inner and outer rings, and when it receives vibration from the axis direction, a component force in the direction perpendicular to the axis is generated. , Vibration from any of these directions causes relative displacement between the inner and outer rings and the rolling elements in the axial direction, and the rolling elements undergo relative sliding with the bearing ring while receiving vibration loads from the direction perpendicular to the axis. This is because this will be repeated, and as a result, this relative sliding surface will wear out. A lubricant film is difficult to form on sliding surfaces, and wear begins due to metal contact in the absence of lubricant. Next, the wear powder becomes oxidized wear powder due to oxygen in the atmosphere, and this intervening on the sliding surface further accelerates wear. This is a pseudo-indentation (false brinelling)
This causes an increase in vibration and sound, which impedes the normal operation of the bearing.

This is particularly a problem when tapered roller bearings that use grease as a lubricant are transported while attached to equipment.

In other words, during steady rotation, the grease sealed in the bearing is exposed to mechanical effects such as shear due to rotation, and the oil retained in the thickener oozes out onto the raceway and rolling surfaces, exerting a lubricating effect. When the bearing is not rotating, the oil in the grease does not provide sufficient lubrication, and this often causes bearing failure.

By the way, when the bearing rotates, concentrated stress may be generated at the ends of the rolling elements or on the sides of the raceway surface due to the influence of the load.

In order to alleviate the stress concentration of this bearing load, giving a curved surface with a slight curvature to the end of the rolling element or the side of the raceway surface is known as crowning the rolling element or raceway surface (for example, Unexamined Japanese Patent Publication 1973
−136).

Crowning is not only applied to the inner and outer ring raceway surfaces or the rolling surface near both ends of the rolling element, but also to form the entire rolling surface or raceway surface into a gentle curvature. However, in either case, most of the raceway surfaces and rolling surfaces are in line contact in order to increase the bearing load capacity, and as a result, relative movement in the axial direction between the inner and outer rings and the rolling elements In this case, sliding contact was dominant.

In this way, conventional crowning was aimed only at preventing stress concentration in the bearing and actually improving its life, and was not aimed at the problem of preventing pseudo-indentation, which is the problem in this specification. isn't it.

[The problem that the idea attempts to solve]

In order to prevent the occurrence of the above-mentioned false impressions, changing the lubricant from grease to lubricating oil, or changing to a higher consistency (softer) grease will improve the fluidity of the lubricant and improve the lubrication effect. It is necessary to improve this and/or to apply a large preload to the bearing to prevent relative slip between the rolling elements and the raceway.

However, if the consistency of the grease is increased or oil lubrication is used, a special bearing seal structure must be provided to prevent grease or oil leakage. Furthermore, when increasing the preload load, problems such as a reduction in the life of the bearing occur due to the increased load, so it is not easy to take practical countermeasures.

The present invention solves the above problems by improving the contact condition between the rolling elements and the raceway ring, and by creating a cone that can reduce the pseudo impressions that occur as a result of repeated relative sliding between the rolling element and the raceway ring due to vibration. The purpose is to provide roller bearings.

[Means to solve the problem]

In the present invention, the raceway surface or rolling surface of at least one of the inner and outer rings or the rolling elements of a tapered roller bearing has a convex arc-shaped axial cross section, and the radius of curvature R of the convex arc of the axial cross section is 400mm~1000
mm, so that the relative displacement between the inner and outer rings and the rolling elements caused by vibration of the tapered roller bearing occurs through rolling contact in the axial direction. shall be.

[Effect]

By forming the axial cross section of the rolling element rolling surface of the tapered roller bearing, or the rolling element rolling surface and the bearing ring raceway surface, into a convex arc shape, the inner and outer rings that are generated when the tapered roller bearing is subjected to vibration are Regarding the relative movement between the roller and the rolling element, the direction of movement can be entirely replaced by the axial direction, and the movement can be performed by rolling contact. As a result, relative slip between the inner and outer rings and the rolling elements can be eliminated, and the generation of false impressions can be prevented.

In this case, the radius of curvature R of the convex arc in the axial cross section is
By setting the distance between 400 mm and 1000 mm, it was possible to minimize the reduction in bearing life while ensuring a high effect in reducing pseudo-indentations.

〔Example〕

Figure 1 shows an example of a tapered roller bearing according to the present invention.
The raceway surfaces 5, 4 of the inner and outer rings 2, 1 are shaped like a convex arc surface,
That is, the axial cross sections of both raceway surfaces 5 and 4 are formed into a convex arc shape as shown in the figure.

The results of tests conducted using the present invention on tapered roller bearings used in automobile front wheels are described below.

Figure 2 shows an example of a convex arc surface formed on the outer ring raceway surface measured using a shape measuring machine, and the vertical magnification is 1000 times and the lateral magnification is 10 times relative to the actual dimensions.

Here, the height of the convex arc surface was determined by calculating the difference from the center height at the point where 0.5 mm at both ends was removed in order to eliminate the influence of sagging at both ends of the raceway ring. R is the radius of curvature of the convex arc surface, that is, the convex arc of the axial cross section.

FIG. 3 shows the acoustic values measured using parts of actual dimensions for the tapered roller bearing A to which the present invention is applied.
Tapered roller bearing A has an inner ring with an inner diameter of 29 mm, an outer ring with an outer diameter of 50.292 mm, and an assembled bearing width of 14.224 mm. The acoustic values in Figure 3 are based on a preload of approximately 60Kgf and a lubricant of NLGI consistency No. 2.
This is the acoustic value of a single bearing after a vibration test was conducted with a radial load of 400 kgf ± 350 kgf, a vibration speed of 21 Hz, and a vibration repetition rate of 1.5 x 10 ⁶ times. .

FIG. 4 shows the results of measuring the size of pseudo indentations on the inner and outer rings after the above test using a shape measuring machine and reading the total depth.

In the above test, the height of the convex arc surface of the inner ring raceway surface was approximately 10 μm, and the height of the convex arc surface of the rollers was 3 μm or less, and the results were confirmed in relation to the height of the convex arc surface of the outer ring raceway surface. It is.

From FIGS. 3 and 4, it can be seen that by machining the outer ring raceway surface with a convex arc surface, the pseudo indentation depth is reduced and the increase in bearing sound is suppressed.

FIG. 8 shows the acoustic values measured using parts of actual dimensions for the tapered roller bearing B to which the present invention is applied.
Tapered roller bearing B has an inner ring with an inner diameter of 17 mm, an outer ring with an outer diameter of 47 mm, and an assembled bearing width of 15.25 mm.
The acoustic values in Figure 8 are based on a preload of approximately 60 kgf, a lithium soap-based grease with an NLGI degree of No. 2 as a lubricant, and a radial load.
Vibration speed is 21 as a variable load of 400Kgf±350Kgf
This is an acoustic body made of a single bearing after a vibration test was conducted at Hz with a vibration repetition rate of 1.5 x 10 ⁶ times.

FIG. 9 shows the results of measuring the size of pseudo indentations on the inner and outer rings after the above test using a shape measuring machine, and reading the total depth.

[Effect of idea]

From the above results, the smaller the radius of curvature (the larger the height of the convex arc surface), the greater the effect.
When the radius of curvature exceeds 1000 mm and exceeds 1500 mm (the height of the convex arc surface is 7 to 8 μm or less for tapered roller bearing A, and 10 μm or less for tapered roller bearing B), the effectiveness ratio decreases slightly, so the radius of curvature The size should be less than 1000mm.

Here, we examined the results of machining the outer ring raceway surface into a convex arc surface, but the contact pattern for the inner ring raceway surface is the same as that for the outer ring, and the effect of forming the inner ring into the same convex arc surface is also can get. It is also assumed that the same effect can be obtained by forming the rolling elements into convex arcuate surfaces equivalent to the inner ring raceway surface or the outer ring raceway surface.

To prevent false indentations, the height of the convex arc surface should be large in order to ensure good rolling contact between the inner and outer rings and the rolling elements, but as the height of the convex arc surface increases, the life of the bearing will be reduced. The influence of the size of the convex arc surface was tested.

This bearing life test was conducted using the tapered roller bearing described above, with a thrust load of 1240 Kgf, lithium soap-based grease (NLGI consistency No. 2) for lubrication, and an inner ring rotation speed of 1125 rpm.

The results are shown in Figure 5, and the life of the bearing decreases as the height of the convex arc surface increases. Even when the circular arc surface is machined, the life of the bearing is approximately 75% of that when the convex arc surface is not machined, which indicates that the bearing is sufficiently durable for practical use. From this result, in order to maintain the bearing life to at least 70% of that without machining the convex arc surface, the radius of curvature of the convex arc surface must be 400 mm or more.

By the way, as mentioned above, in tapered roller bearings, in order to prevent concentrated load (edge load) that occurs on the end surface of the contact area between the roller rolling surface and the raceway surface of the bearing ring,
Alternatively, in order to reduce friction on the contact surfaces, crowning is usually performed on the roller rolling surfaces and/or the raceway surfaces of the raceway rings.

However, the amount of crowning that is normally performed is determined for the above purpose, and the value is also usually about 10 μm or less (R1000 mm or more), which is the effect of the present invention, that is, between the inner and outer rings and the rolling elements. In practice, it is not possible to obtain the effect of nearly rolling contact.

In order to prove the effectiveness of the present invention, the results of microscopic observation of the portion where the pseudo-indentation occurred after the vibration test are shown in FIGS. 6 and 7.

FIG. 6 shows the state of the outer ring raceway surface of a tapered roller bearing without implementing the present invention, and it can be seen that the entire surface is sliding violently in the axial direction, causing adhesive wear.

FIG. 7 shows the state of the outer ring raceway surface of a tapered roller bearing in which the present invention was implemented, and it can be seen that axial slippage is small and wear is reduced.

According to the present invention, since the raceway surface has a curvature as a convex arc surface in the axial direction, all relative movement between the rolling elements and the raceway surface due to vibration can be replaced as axial movement, and furthermore, their contact position can be changed. 1st
By sequentially moving as shown by the arrows in the figure, a contact state similar to rolling can be achieved. As a result,
This improves the repairability of the lubricating oil film at the contact portion between the rolling element and the raceway surface, and has the effect of reducing wear on the contact surface.
Therefore, the present invention has a configuration and effects that cannot be obtained by conventional crowning, and is highly practical.

[Brief explanation of drawings]

Fig. 1 is a half longitudinal sectional front view of the tapered roller bearing according to the present invention, Fig. 2 is an enlarged diagram of the height of the convex arc surface of the outer ring raceway surface in the embodiment, and Fig. 3 is a graph of the bearing acoustic value of the embodiment. , Fig. 4 is a graph showing the relationship between the height of the convex arc surface of the outer ring raceway surface and the indentation depth of the inner and outer rings, and Fig. 5 is a graph showing the relationship between the height of the convex arc surface of the outer ring raceway surface and the bearing life ratio. Figure 6 is an enlarged photograph showing the adhesive wear condition of the conventional product, Figure 7 is an enlarged photograph showing the condition of the outer ring raceway of the present invention, Figure 8 is a graph of the bearing acoustic value of another example, and Figure 9. is a graph showing the relationship between the height of the convex arc surface of the outer ring raceway surface and the indentation depth of the inner and outer rings. 1... Outer ring, 2... Inner ring, 4, 5... Raceway surface,
R...Radius of curvature of a convex arc in the axial cross section.

Claims (1)

[Claims for Utility Model Registration] (1) The raceway surface or rolling surface of at least one of the inner and outer rings or rolling elements of a tapered roller bearing has a convex arc-shaped axial cross section, and the outer axial cross section The radius of curvature R of the convex arc is 400
mm to 1000 mm, and is configured so that the relative displacement between the inner and outer rings and the rolling elements caused by vibration of the tapered roller bearing is performed by rolling contact in the axial direction. roller bearings. (2) The raceway surfaces of the inner ring and the outer ring have the convex arc-shaped axial cross section, as claimed in Claim No.
Tapered roller bearings described in (1).