JPS6410691B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a double-row thrust tapered roller bearing, and particularly to a thrust tapered roller bearing in which the end face of the inner ring of the bearing is fixed to the shaft via a collar. Among the intersection points of the generatrix lines and the cone centers of the tapered rollers, at least the intersection point of the generatrix line of the raceway surface is offset from the center axis of the bearing, and at least the intersection point of the raceway surface of the tapered rollers and the raceway surfaces of the inner ring and the outer ring is By applying crowning with a predetermined radius of curvature over the entire length of one surface, the generation of edge load and heat generation on the rolling contact surface of the tapered roller caused by the axial deflection of the inner ring is reduced, and the thrust load capacity is greatly increased. It was designed to increase the number of people.

For example, double-row thrust tapered roller bearings, which have a small volume and large thrust load capacity, are suitable as thrust bearings for roll necks in rolling mills, but in recent high-load rolling operations, the thrust loads generated on the rolls are extremely large. Become. In conventional double-row thrust tapered roller bearings, when such a large thrust load is applied, the load distribution between the raceway surface and the raceway surface on the tail side of the tapered roller becomes high, which not only causes edge load. It had the disadvantage that it could not withstand long-term use, such as the generation of abnormally high heat and seizure accidents.

In order to investigate the cause of this phenomenon, various experiments were repeated and it was found that it was caused by the axial deflection of the inner ring. In other words, edge load is caused by the tail side of the tapered roller coming into strong contact with the raceway surface due to the deflection of the inner ring, and it is particularly likely to occur when the crowning shape of the tapered roller is not appropriate. Due to deflection, the intersection of the generatrix lines of the inner ring raceway surface and the outer ring raceway surface deviates from the center axis (rotation center) of the bearing, which causes the tapered rollers in contact with the raceway surface to also shift, causing their cone centers to deviate from the center axis. This is due to the rotation difference that causes slippage on the contact surfaces.

Furthermore, we investigated the causes of axial deflection of the inner ring, and found that because the conventional inner ring has a thin wall thickness and the end face height of the collar for positioning the inner ring is low, the fixing force of the inner ring is insufficient, causing it to flex. We came to the conclusion that this is due to the fact that the situation is close to support. By the way, the conventional surface pressure at the end face of the inner ring and collar is 30Kg/ ^mm2 or more, and the maximum deflection of the inner ring in this case is calculated assuming that the inner ring is freely supported. ~40 times larger.

This invention has been made in view of the above points, and an object of the invention is to prevent the occurrence of edge load on the rolling contact surface between the tapered rollers and the raceway surface even when the inner ring is deflected in the axial direction. It is an object of the present invention to provide a thrust tapered roller bearing that suppresses heat generation, and also to provide a double-row thrust tapered roller bearing that has a large load capacity.

That is, the present invention, as in the embodiment of the rolling mill roll neck shown in the figure, is positioned and fixed between the shoulder 13 of the shaft (roll neck) 12 and the collar 43, or between the collars 42 and 43, and Tapered rollers 48 are arranged in double rows through a cage between an inner ring 41 that has a substantially uniform wall thickness throughout, and two outer rings 44 that are fitted into the housings 14 and 15 so as to sandwich the inner ring 41 therebetween. In the thrust tapered roller bearing 40, which is arranged in
Of the intersection P ₂ of the generatrix of the raceway surfaces 41a and 45 of the outer ring 44 and the cone center P ₁ of the tapered roller 48, at least the intersection P ₂ of the generatrix of the raceway surfaces 41a and 45 deviates from the center axis O-O of the bearing. and
Moreover, the intermediate portion 4 of at least one surface between the rolling surface of the tapered roller 48 and the raceway surfaces of the inner ring and the outer ring.
8c and both ends 48a, 48 on the head side and tail side
b are crowned with different radii of curvature, and the generatrix has a common tangent. This invention relates to a double-row thrust tapered roller bearing characterized by:

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which reference numeral 10 indicates a roll of a rolling mill, 12 indicates a roll neck, and 14 and 15 indicate a housing.
The large-diameter portion 12a of is supported in the radial direction by a radial tapered roller bearing 16. The radial tapered roller bearing 16 includes two double-row inner rings 17, two single-row outer rings 18, one double-row outer ring 19, and four rows of tapered rollers 20. 21 is a retainer, 22 is an outer ring spacer, and 23 is an inner ring spacer. The single-row outer ring 18 is positioned in the axial direction by a presser member 25 and a presser ring 26 fitted into the housing 14. Two seals 28 are fitted to the presser member 25 via spacers 29, and the seals 28 are fitted on the outer peripheral surface of a fillet ring 30 fitted to the shoulder of the roll 10 and the large diameter portion 12a of the roll neck 12. The lip is in sliding contact. Further, a seal 31 is fitted onto the axial end of the presser member 25 by a seal presser 32 and slidably contacts the fillet ring 30, and a seal 33 is provided between the seal presser 32 and the roll 10. Reference numeral 34 denotes an oil supply hole through which lubricating oil is forced to circulate.

The small diameter portion 12b of the roll neck 12 is provided with a thrust tapered roller bearing 40 of the present invention.
In this bearing, an intermediate ring 41 is fitted into a small diameter portion 12b of a roll neck 12, and collars 4 are attached to both end surfaces of the intermediate ring 41.
2 and 43 are brought into contact and positioned and fixed to form an inner ring, and outer rings 44 with flanges are fitted into the housings 14 and 15, respectively, so that there is a gap between the raceway surface 45 of the outer ring 44 and both end surfaces of the inner ring 41. It is configured as a double-row thrust bearing that supports the roll neck 12 in the axial direction by bringing the tapered rollers 48 into rolling contact with each other. 51 is a cage that holds and guides the tapered rollers 48; 52 is a spacer for positioning the outer ring 44; the spacer 52 is provided with an oil passage hole 53; A plurality of oil drain holes 55 communicating with the hole 53 are provided.

The guide surface (flange surface) 47 of the collar 46 of the outer ring 44 that comes into sliding contact with the large end surface 49 of the tapered roller 48 is as follows:
The large end surface 4 of the tapered roller 48 is formed into a spherical shape.
The radius of curvature of No. 9 is set in the range of 70% to 85% of the radius of curvature of the flange surface 47 of the outer ring 44, so that the contact state between the large end surface 49 of the tapered roller 48 and the flange surface 47 of the outer ring 44 is good. I'm trying to make it happen.

The outer ring 44 also includes a raceway surface 45 and a collar surface 47.
Oil supply hole 60 that opens at the boundary part (grinding part) with
and a plurality of oil supply holes 62 that open in the raceway surface 45 on the tail side are drilled from the rear side, and these oil supply holes 60, 62 are communicated with oil passages 64 provided in the housings 14, 15, respectively. be.

Furthermore, two seals 65 are disposed on both sides with a spacer 65 interposed between the housing 15 and the collar 43 for sealing.

The thrust bearing 40 is lubricated by using lubricating oil as an oil jet, which is injected from the oil supply holes 60 and 62 of the outer ring 44 through the oil passages 64 of the housings 14 and 15. It lubricates the sliding surface between the flange surface 47 of 44 and the contact surface between the raceway surfaces of the inner ring 41 and outer ring 44 and the rolling surface of the tapered rollers 48 through the oil supply hole 62, and circulates inside the bearing. After that, Maza 52
The oil drain hole 5 of the housing 14 passes through the oil passage hole 53 of the housing 14.
5 and is discharged to the outside.

A so-called offset configuration is provided between the intersection of the generating lines of the raceway surfaces 41a and 45 of the inner ring 41 and outer ring 44 of the thrust bearing 40 and the cone center of the tapered rollers 48. That is, in the conventional bearing, as shown in _FIG .
The intersection point P ₂ of the generatrix lines a and 45 is the central axis O of the bearing.
-O, but now the inner ring 41 is bent in the axial direction and tilted at an angle θ to the position shown by the broken line, and the generatrix of the rolling surface of the tapered rollers 48 is aligned with the raceway surface 4 of the outer ring 44.
If it is assumed that P _{2 coincides with the generatrix of 5, then P 2} will be a position P' ₂ shifted by a distance x from the central axis OO.

x=Ra−lγ/cosβ・tanθ/tan2β+tanθ Where, Ra=Length between the large end face of the tapered roller and the cone center (P ₁ P ₃ ) lγ=Length of generatrix of the rolling surface of the tapered roller (P ₃ P ₄ ) 2β = conical angle of tapered rollers In this way, as a result of the intersection point P ₂ of the cone center P ₁ and the raceway surface generatrix deviating from the central axis O-O, there is a gap between the rolling surface of the tapered rollers 48 and the raceway surface. Differential slip will occur.

Therefore, as shown in Figure b, the intersection P ₂ of the generatrix of the raceway surfaces 41 a and 45 of the inner ring 41 and the outer ring 44 is placed to the left of the center axis O-O, and the cone center P ₁ of the tapered roller 48 is placed on the center axis O- The raceway surface 4 of the inner ring 41 and the outer ring 44 is positioned on the right side of O.
The angle η formed by the generating lines of 1a and 45 is the tapered roller 48
The inclination angle θ of the inner ring 41 is made smaller than the cone angle 2β, so that η=2β−θ.

Let S 1 and S 2 be the distances between the cone center P ₁ and the intersection point P ₂ of the raceway surface generatrix from the central axis O- _O , respectively, then _{S 1 =} Ra・θ・sin2β S ₂ = Ra・θ [cosec(2β -θ)-sin2β] Here, Ra=P ₁ P ₃ = P ₀ P ₃ Therefore, the inner ring 41 of the bearing set in this way is subjected to a thrust load and deflects in the axial direction, as shown by the broken line. When tilted by angle θ, tapered roller 4
8 is also tilted by the same angle as this, and the cone center
Since P ₁ and the intersection point P ₂ of the raceway surface generatrix both coincide with the point P ₀ on the central axis O-O, the angle η ₀ formed by the raceway surface generatrix of the inner ring 41 and the outer ring 44 under load is: It is equal to the cone angle 2β of the tapered roller 48. As a result, no differential slip occurs between the rolling surface and the raceway surface of the tapered rollers 48.

Although the offset in the above embodiment is provided at both the intersection of the generatrix of the raceway surface and the cone center of the tapered roller, it is sufficient that at least the intersection of the generatrix of the raceway surface be offset.

Further, the rolling surface of the tapered rollers 48 of the bearing is crowned as shown in FIG. 3. The total effective length of the tapered roller 48 is lγ, and the head 48
The length of a and the tail part 48b is l ₁ respectively, and the length of the middle part 4 is
Assuming that the length of 8c is _l2 , the intermediate portion 48c is crowned with a radius of curvature _R2 , the head 48a and the tail 48b are crowned with a radius of curvature _R1 , and the generatrix of the intermediate portion 48c and the head 48a and The generating line of the tail portion 48b is a circular arc having a common tangent at its intersections A and B. The length l ₂ of the intermediate portion 48b is l ₂ =0.7lγ with respect to the total effective length lγ.
The radius of curvature R ₂ of the intermediate portion 48c is
8a and the radius of curvature R ₁ of the tail portion 48b,
Ensure that R ₂ ≧30R ₁ . In this way, the entire rolling surface of the tapered rollers 48 is crowned,
Furthermore, by making the radius of curvature R ₁ of both ends of the head portion 48a and the tail portion 48b significantly smaller than the radius of curvature R ₂ of the intermediate portion 48c, the occurrence of edge load on the rolling surface of the tapered roller 48 can be suppressed.

The above crowning may be applied to the raceway surfaces of the inner ring and the outer ring, or may be applied to both the tapered rollers and the inner ring and the outer ring.

Furthermore, in the above bearing, in order to suppress the axial deflection of the inner ring 41, the wall thickness of the inner ring 41 is set as follows. In FIG. 4, the inner ring 41
W is the wall thickness of the inner ring 41, and the radial length from the inner peripheral edge of the inner ring 41 to the intersection C between the raceway surface 41a of the inner ring 41 and the extension line of the generatrix of the large end surface 49 of the tapered roller 48 that contacts this (maximum contact height) Letting H) be H, the wall thickness W is increased so that W/H≧0.8. W/H
The upper limit of is limited by the allowable range of the assembly space of the bearing part, but can be up to about 1.1.

Further, the ratio Hc/H of the radial clearance Hc between the inner peripheral edge of the inner ring 41 and the inner peripheral edge of the cage 51 to the upper limit contact height H of the inner ring 41 is set such that Hc/H≧0.26. . Regarding the upper limit of Hc/H,
If Hc is excessively increased, the length of the tapered roller 48 will decrease with respect to the given upper limit contact height H.
Since this will result in a decrease in the bearing load rating, it is necessary to select it appropriately within the allowable range of the assembly space, but it can be up to about 0.35. By increasing the radial clearance Hc in this way, the height of the end surfaces of the collars 42 and 43 for positioning the inner ring 41 can be increased and brought into contact with both end surfaces of the inner ring 41.

By setting the dimensions of the inner ring 41 and the collars 42, 43 as described above, the bending rigidity of the inner ring 41 itself increases, and the roll neck 12b of the inner ring 41 increases.
Since the support for the inner ring 41 can be a strong fixed support, even if a large thrust load is applied to the inner ring 41, the axial deflection of the inner ring 41 can be reduced. However, the configuration that restricts the wall thickness of the inner ring and the configuration that restricts the end surface height of the collar are as follows.
It can be omitted if necessary.

In the embodiment described above, the collars 42 and 43 are brought into contact with both end surfaces of the inner ring 41 for positioning and fixing, but one collar 42 is omitted and the end surface of the inner ring 41 on the roll neck 12a side is attached to the shoulder 13 of the roll neck 12a. The same can be applied to a bearing that is fixed by being brought into contact with the bearing.

As described above, the thrust tapered roller bearing of the present invention has an offset configuration in which at least the intersection of the generatrix of the raceway surface and the cone center of the tapered roller is offset from the central axis of the bearing. Therefore, according to the present invention, when the inner ring receives a large thrust load and bends in the axial direction, the intersection point of the generatrix of the raceway surface and the cone center of the tapered rollers coincide on the central axis of the bearing, so that the inner ring is bent in the axial direction. Differential sliding of the rollers can be avoided, and heat generation due to sliding friction on the rolling contact surface between the tapered roller and the raceway surface can be effectively suppressed.

Further, the crowning applied to at least one of the rolling surface of the tapered rollers and the raceway surfaces of the inner ring and outer ring of the thrust tapered roller bearing of the present invention,
Unlike the conventional method in which two surfaces with different radii of curvature are connected smoothly by separate processing, the tapered roller raceway surface and the raceway surfaces of the inner ring and outer ring are connected at the middle and both ends of at least one surface. The crowning is a crowning with different radii of curvature where the generatrix has a common tangent line, so the surfaces with different radii of curvature form an extremely smooth connection, and there is no local contact at the connected part, and the crowning effect is fully exerted. At the same time, there is no need to add special processing to the connecting portions in the crowning process.

Therefore, the thrust tapered roller bearing of the present invention can be used as the most suitable bearing for the roll neck of a rolling mill where a large thrust load is generated, since the above-mentioned effects are combined and the thrust load capacity is greatly increased. .

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional side view showing an embodiment of the present invention, Fig. 2 shows the positional relationship between the cone center of the tapered roller and the intersection of the raceway surface generatrix of the raceway ring, and Fig. a shows the case where no offset is provided. Fig. 3 is a generatrix diagram of the rolling surface of the tapered roller of the present invention, and Fig. 4 is a sectional view showing the relative dimensions between the inner ring and the collar. be. In the figure, 12 is the roll neck (shaft), 13 is the shoulder of the roll neck, 14 and 15 are the housing, and 40
is the thrust bearing, 41 is the inner ring, 41a is the raceway surface of the inner ring, 42, 43 are the collars, 44 is the outer ring, 45 is the raceway surface of the outer ring, 48 is the tapered roller, P ₁ is the cone center of the tapered roller, P ₂ is the inner ring The intersection of the generatrix of the raceway surface with the outer ring, O-O, is the central axis of the bearing.

Claims (1)

[Scope of Claims] 1. An inner ring that is positioned and fixed between the shoulder of the shaft and the collar or between the collars and has a substantially uniform wall thickness throughout, and that is fitted into the housing so as to sandwich the inner ring. Tapered rollers are arranged in double rows between the two outer rings to be mounted, via a cage, and crowning is applied to at least one of the rolling surface of the tapered rollers and the raceway surfaces of the inner ring and the outer ring. In a thrust tapered roller bearing, at least the intersection of the generatrix of the raceway surfaces of the inner ring and the outer ring and the cone center of the tapered roller is offset from the central axis of the bearing, and The intermediate portion of at least one surface of the rolling surface and the raceway surfaces of the inner ring and the outer ring, and both ends of the head side and the tail side, are crowned with different radii of curvature and whose generatrix lines have a common tangent line. A double-row thrust tapered roller bearing featuring: 2. The length of the intermediate portion of at least one of the rolling surface of the tapered roller and the raceway surfaces of the inner ring and outer ring is 70% of the total effective length of the tapered roller, and the radius of curvature of the intermediate portion is equal to or greater than that of both ends. The double-row thrust tapered roller bearing according to claim 1, wherein the double-row thrust tapered roller bearing has a radius of curvature 30 times or more.