JP2001182753A - Double row tapped-roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double row tapered-roller bearing which enables increase in the rate of change of dynamic torque which corresponds to the change in a preload and a easiness of work in setting a desired preload. SOLUTION: A combined roughness σS of rolling contact area between rolling contact surfaces 14, 14 of each tapered roller 4, 4 and each race way of the inner and outer race is set to a comparatively small value of les than 0.2 μm Ra, whereas a combined roughness σL of sliding surface between an end face 13 on the larger radius side of each of the tapered rollers and a side face 12 of a flange 11 on the larger radius side is set to a comparatively larger value exceeding 0.2 μm Ra.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A double row tapered roller bearing according to the present invention is incorporated in a rotary support portion to which a large radial load and a thrust load is applied, such as a rotary shaft of a cylinder of a printing press, to rotate various members such as the cylinder. Use to support freely.

[0002]

2. Description of the Related Art A double-row tapered roller bearing 1 as shown in FIG. 1, for example, is widely used to constitute a rotary support portion to which a large radial load and a thrust load are applied. The double row tapered roller bearing 1 includes an inner ring assembly 2 and an outer ring assembly 3
And a plurality of tapered rollers 4. The inner ring assembly 2 has a pair of inner ring elements 6, 6 having a conical convex inner ring track 5 on each outer peripheral surface, with the inclination directions of the inner ring tracks 5, 5 being opposite to each other. Combine with. The outer ring assembly 3 has a pair of outer ring elements 8, 8 each having a conical outer raceway 7 on the outer peripheral surface thereof, in a state where the inclination directions of the outer raceways 7, 7 are opposite to each other. The outer ring spacer 9 abuts the outer ring spacer 9. The tapered rollers 4, 4 are provided between the inner raceway 5, 5 on the outer peripheral surface of each inner race element 6, 6 and the outer raceway 7, 7 on the outer peripheral surface of each outer race element 8, 8. Cage 1
It is provided so as to roll freely while being held by 0 and 10. The outer ring spacer 9 is provided with a lubricating oil passage 15 for feeding lubricating oil into the double-row tapered roller bearing 1.

When a cylinder of a printing press is supported by the double-row tapered roller bearing 1 as described above, the inner ring assembly 2 is mounted on a rotating shaft projecting coaxially with the cylinder on both axial end surfaces of the cylinder. Fix externally. After the inner ring assembly 2 is externally fitted and fixed to the rotating shaft in this way, before the outer ring assembly 3 is fitted into the housing, the pair of inner ring elements 6, 6 constituting the inner ring assembly 2 are provided. By pressing them toward each other, a desired preload is applied to each of the tapered rollers 4, 4. Thereafter, the outer ring assembly 3 is internally fitted and fixed to the fixed bearing housing. For example, in the case of a double-row tapered roller bearing incorporated in a rotary support portion of a cylinder of a printing press, such a preload needs to be regulated to an appropriate value for the following reason. First, the minimum value of the preload is regulated from the viewpoint of maintaining print quality. If the preload is too low and the rigidity of the double-row tapered roller bearing 1 is insufficient, the displacement of the cylinder cannot be suppressed and print quality deteriorates, such as occurrence of double. Conversely, the maximum value of the preload is restricted from the viewpoint of ensuring the durability of the double-row tapered roller bearing 1. If the preload is too high, the rolling fatigue life of the inner and outer raceways 5, 7 and the rolling surfaces of the tapered rollers 4, 4 will be reduced, and the durability of the double row tapered roller bearing 1 will be insufficient. .

In order to ensure the printing quality and the durability of the double-row tapered roller bearing 1, it is necessary to regulate the preload of the double-row tapered roller bearing 1 to an appropriate value. For this purpose, the preload of the double-row tapered roller bearing 1 for rotatably supporting the cylinder of the printing press can be obtained from the dynamic torque (rotation torque) of the double-row tapered roller bearing 1 during low-speed rotation.
This has been done conventionally. That is, double row tapered roller bearing 1
2 increases as the preload (preload) increases, as indicated by the solid line a in FIG. Therefore, a pair of inner ring elements 6, 6 constituting the inner ring assembly 2 of the double row tapered roller bearing 1 are applied with loads in directions approaching each other until the dynamic torque matches a predetermined preload (set preload). The predetermined preload is applied to the double-row tapered roller bearing 1. still,
The reason why the preload is applied to the double-row tapered roller bearing 1 in this manner is to enable the preload to be adjusted according to the quality of printing.

[0005]

As described above, when the preload is applied to the double-row tapered roller bearing 1 on the basis of the dynamic torque of the double-row tapered roller bearing 1, the preload is changed with respect to the change in the preload. It is important that the change in torque is large in order to perform accurate preload application. Conversely, if the change in the dynamic torque with respect to the change in the preload is small, it is difficult to accurately apply the preload based on the dynamic torque.

However, in the case of the conventional double-row tapered roller bearing 1, the change in dynamic torque (inclination angle of the dashed line b in FIG. 2) with respect to the change in preload near the set preload is small and is based on the dynamic torque. It is difficult to accurately apply preload. In particular, in an actual printing press or the like, after the preload applying operation, the outer ring assembly 3 of the double row tapered roller bearing 1 is internally fitted and fixed in the housing. There is a possibility that the preload applied to the double-row tapered roller bearing 1 in a later state is out of an allowable range. When the preload is out of the allowable range in this manner, the printing quality is deteriorated (when the preload is too small) or the durability of the double row tapered roller bearing 1 is impaired (the preload becomes excessive). If you have).

On the other hand, the change of the dynamic torque with respect to the change of the preload is indicated by a broken line c in FIG. 2, and the change of the dynamic torque with respect to the change of the preload near the set preload (see the two-dot chain line d in FIG. 2). If the inclination angle is increased, it is easy to accurately apply the preload based on the dynamic torque. Therefore, even if the preload change due to the fitting error is considered, it is easy to keep the preload given to the double-row tapered roller bearing 1 within an allowable range after the assembly is completed. In view of such circumstances, the present invention has been made to realize a double-row tapered roller bearing having a large change in dynamic torque with respect to a change in preload.

[0008]

The double-row tapered roller bearing of the present invention has the same structure as the above-mentioned conventional double-row tapered roller bearing.
An inner ring assembly having a double row of inner ring raceways each having a conical convex shape on the outer peripheral surface and inclined in opposite directions to each other; and an outer ring assembly having a double row of outer ring raceways each having a conical concave shape on the inner peripheral surface. A plurality of tapered rollers provided in a freely rolling manner between each of these outer raceways and the inner raceways, and formed on the outer peripheral surface of the large-diameter end of each of the inner races,
An outward flange-shaped large-diameter flange portion whose side surface is opposed to the large-diameter end surface of each of the tapered rollers is provided.

In particular, in the double-row tapered roller bearing of the present invention, the combined roughness (square) of the contact portion (rolling contact portion) between the rolling surface of each of the above-mentioned tapered rollers and each of the above-mentioned inner raceway and outer raceway is preferred. The average roughness of the contact portion (sliding contact portion) between the large-diameter end face of each of these tapered rollers and the side surface of the large-diameter flange portion is greater than the average roughness. Further preferably, the combined roughness of the contact surface between the rolling surface of each of the tapered rollers and each of the inner raceway and the outer raceway is less than 0.2 μmRa, and the large-diameter side end face of each of the tapered rollers and the large-diameter The combined roughness of the contact portion with the side surface of the side flange portion is set to a value exceeding 0.2 μmRa.

[0010]

In the case of the double row tapered roller bearing of the present invention constructed as described above, the dynamic torque with respect to the change of the preload is secured while ensuring the separation life of the inner and outer raceways and the rolling surfaces of the respective tapered rollers. It is easy to increase the change and keep the preload within an allowable range. That is, as the synthetic roughness of the contact portion between the large-diameter end surface of each tapered roller and the side surface of the large-diameter flange portion is increased, the rate at which the dynamic torque increases with an increase in the preload increases. That is, as the preload increases, the surface pressure of the contact portion between the large-diameter end face of each of the tapered rollers and the side surface of the large-diameter flange increases, and the dynamic torque increases. Since the combined roughness of the contact portions is large, the rate at which the dynamic torque increases with an increase in the surface pressure (an increase in the preload) increases. On the other hand, since the combined roughness of the rolling contact surface between the rolling surface of each tapered roller and each of the inner and outer raceways is small, the oil film parameter of each of these rolling contact portions (the rolling contact portion, The ratio (T / σ) of the oil film thickness T to the combined roughness σ can be equal to or greater than a predetermined value. For this reason, the separation life between the rolling surface of each tapered roller and each of the inner ring and outer ring raceways can be lengthened, and the durability of the double row tapered roller bearing can be ensured.

As described above, in the case of the double row tapered roller bearing of the present invention, each of the tapered roller bearings is compared with the combined roughness of the abutting portions of the rolling surfaces of the tapered rollers with the inner ring raceway and the outer ring raceway. By increasing the synthetic roughness of the contact portion between the large-diameter side end surface of the roller and the side surface of the large-diameter flange portion, the rate at which the dynamic torque increases with an increase in the preload is increased. And the separation life of the inner race and the outer race is increased. Therefore, it is possible to ensure both rigidity and durability of the double-row tapered roller bearing.

In particular, the combined roughness of the abutting portion between the rolling surface of each of the tapered rollers and each of the inner raceway and the outer raceway is 0.2 μm.
mRa, and the combined roughness of the contact portion between the large-diameter end face of each of the tapered rollers and the side face of the large-diameter flange portion is 0.2 μmR.
When the value exceeds a, it is possible to achieve both high rigidity and high durability of the double-row tapered roller bearing at a high level.

On the other hand, in the case of the conventional double-row tapered roller bearing, the combined roughness of the contact portion between the rolling surface of each tapered roller and each of the inner ring raceway and the outer ring raceway and the size of each of these tapered rollers are large. The combined roughness of the contact portion between the radial end surface and the side surface of the large-diameter flange portion has been made as small as possible. For this reason, the rate at which the dynamic torque increases with an increase in the preload is small, and accurate preload cannot be applied, so that it is impossible to achieve both the rigidity and durability of the double-row tapered roller bearing.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure of a double-row tapered roller bearing of the present invention is the same as that of a conventionally known double-row tapered roller bearing as shown in FIG. The feature of the double-row tapered roller bearing of the present invention lies in that the combined roughness of each part is devised in order to realize a double-row tapered roller bearing having a large change in dynamic torque with respect to a change in preload. Since the configuration and operation of the other parts are the same as those of the conventional structure described above, the description of the equivalent parts will be omitted or simplified, and the following description will focus on the characteristic parts of the present invention.

Each of the inner ring elements 6, 6 constituting the inner ring assembly 2
Outer flange-shaped large-diameter flange 1 on the outer peripheral surface of the large-diameter end
1, the side surface 12 of the large-diameter flange 11 is opposed to the large-diameter end surface 13 of each of the tapered rollers 4, 4. During operation of the double-row tapered roller bearing 1, these side surfaces 12 and the large-diameter end surface 13 are in sliding contact. The rolling surfaces 14, 14 of the tapered rollers 4, 4, the inner raceways 5, 5, and the outer raceways 7, 7
Are in contact with each other (rolling contact). For example, as an embodiment of the present invention, in the case of a double-row tapered roller bearing that rotatably supports the end of a cylinder of a printing machine with respect to a housing, the inner diameters R6 of the inner ring elements 6, ₆ are about 180 mm, and the outer rings are The outer diameter D8 of the elements 8, ₈ is about 250 mm, the assembly width W2 of the inner ring assembly ₂ is about 106 mm, and the assembly width W3 of the outer ring assembly ₃ is about 84 mm. When such a double row tapered roller bearing 1 is used, it is rotated at a speed of about 12 sec ^-1 (rpm) while lubricating with lubricating oil equivalent to VG100, and a dynamic torque is measured to obtain a predetermined preload. Has been granted. The measurement of the dynamic torque is performed by the outer ring assembly 3 described above.
A cord (tangential force) required to wind the cord around the outer diameter part and rotate the outer ring assembly 3, thereby pulling the cord
Is measured by a Push Pull Gauge, and the measured value is used as a substitute for the dynamic torque. In this measurement operation, since an axial load is applied to the outer ring assembly 3, the outer ring elements 8, 8 and the outer ring spacer 9 rotate integrally.

In particular, in the case of the double-row tapered roller bearing 1 of the present invention, the rolling surfaces 14, 14 of the tapered rollers 4, 4 and the inner raceways 5, 5, and the outer raceways 7, 7 are in contact with each other. The combined roughness σ _S of the contact portion (rolling contact portion) is set to a relatively small value of less than 0.2 μmRa. For this purpose, for example, the roughness of each of the inner raceways 5, 5 is set to 0.07 μmRa, the roughness of each of the outer raceways 7, 7 is set to 0.06 μmRa, and the rolling surface 14 of each of the rolling elements 4, 4 is formed. Roughness 0.08μmR
a. In this case, the combined roughness σ _SI of the rolling contact portions between the rolling surfaces 14 of the tapered rollers 4 and the inner ring raceways 5 and 5 is (0.07 ² +0.08 ² ) ^1/2 = 0.11
μmRa, and the rolling surface 14 of each of the above tapered rollers 4, 4
Roughness σ of the rolling contact portion between the outer ring raceways 7 and 7
_SO is (0.06 ² +0.08 ² ) ^1/2 = 0.10 μm
Ra.

On the other hand, the combined roughness σ _L of the contact portion (sliding contact portion) between the large-diameter end surface 13 of each of the tapered rollers 4, 4 and the side surface 12 of the large-diameter flange portion 11 is given by: It is a relatively large value exceeding 0.2 μmRa. For this purpose, for example, the roughness of the large-diameter side end surface 13 of each of the tapered rollers 4, 4 is set to 0.1.
The roughness of the side surface 12 of the large diameter flange 11 is set to 0.2 μmRa. In this case, the large diameter side end face 1
3 and the side surface 12 of the large diameter side flange portion 11 have a combined roughness σ _L of (0.15 ² +0.2 ² ) ^1/2 = 0.25 μm.
mRa.

In the case of the double-row tapered roller bearing 1 of the present invention constructed as described above, the separation life of the inner ring and outer ring raceways 5, 7 and the rolling surfaces 14, 14 of the tapered rollers 4, 4 is described. , The change in dynamic torque with respect to the change in preload can be increased as shown by the broken line c in FIG. The preload applied to the double-row tapered roller bearing 1 can be easily set within an allowable range centered on the set preload. That is,
In the case of the double-row tapered roller bearing 1 of the present invention, as shown by the broken line c in FIG. 2, the change in the dynamic torque with respect to the change in the preload near the set preload (the inclination angle of the two-dot chain line d in FIG. 2). )
And it is easy to accurately apply the preload based on the dynamic torque. Therefore, even if the preload change due to the fitting error is considered, it is easy to keep the preload given to the double-row tapered roller bearing 1 within an allowable range after the assembly is completed.

That is, the large-diameter end faces 13 of the tapered rollers 4, 4 abut against the side faces 12 of the large-diameter flange 11 provided on the outer peripheral faces of the large-diameter ends of the inner ring elements 6, 6. Combined roughness σ
_{As L} is increased to, for example, 0.25 μm Ra,
The rate at which the dynamic torque increases with an increase in the preload increases. That is, as the preload applied to the double-row tapered roller bearing 1 increases, the contact portion between the large-diameter end surface 13 of each of the tapered rollers 4 and 4 and the side surface 12 of the large-diameter flange 11 is increased. The surface roughness of the contact portion increases, and the dynamic torque increases. However, since the combined roughness σ _L of the contact portion is large, the rate of increase in the dynamic torque with the increase of the surface pressure (increase of the preload) increases. .

On the other hand, the combined roughness σ _S of the rolling contact portions between the rolling surfaces 14, 14 of the tapered rollers 4, 4 and the inner and outer races 5, 7 is 0.10 μm Ra, Alternatively, since it is as small as 0.11 μmRa, the oil film parameter Λ (the ratio T / σ between the oil film thickness T and the combined roughness σ at the rolling contact portion) of each of the rolling contact portions can be set to a predetermined value or more. For this reason, the rolling surfaces 14, 1 of the respective tapered rollers 4, 4 are provided.
4 and the inner ring / outer ring raceways 5 and 7 can be extended, and the durability of the double row tapered roller bearing 1 can be ensured.

As described above, the double-row tapered roller bearing 1 according to the present invention.
In the case of the above, the rolling surfaces 14, 1 of the above-described tapered rollers 4, 4
4 and the than composite roughness sigma _S of the rolling contact portion between the inner ring raceway 5, 5 and the outer ring raceway 7, 7, each of the tapered rollers 4,
The synthetic roughness σ _L of the contact portion between the large-diameter side end surface 13 of FIG. 4 and the side surfaces 12 of the large-diameter flanges 11, 11 is increased (σ _S <σ _L ).
By doing so, the rate at which the dynamic torque increases with an increase in the preload is increased, and the rolling surface 1 of each of the tapered rollers 4, 4 is increased.
4, 14 and the above-mentioned inner and outer raceways 5, 7 have a longer peeling life. Therefore, it is possible to ensure both rigidity and durability of the double-row tapered roller bearing 1.

In particular, the rolling surface 1 of each of the tapered rollers 4, 4 described above.
4,14 and the composite roughness sigma _S of the contact portion rolling between the respective inner ring raceways 5,5 and the outer ring raceway 7 and 7 below 0.2MyumRa, the large diameter side end face of each of the tapered rollers 4, 4 13 And the large-diameter flanges 11 and 11 have a combined roughness σ _L of 0.2 μm Ra (more preferably 0.25 μm).
When the value exceeds mRa), it is possible to achieve both high rigidity and high durability of the double-row tapered roller bearing 1 at a high level.
In the following, the reason why the double row tapered roller bearing 1 can achieve both high rigidity and high durability by controlling the combined roughness σ _S , σ _L of the above-described portions within the above ranges will be described.

[0023] In order to impart a preload to the double row tapered roller bearing 1 such as shown in FIG. 1, the axial direction of the load (preload) F _a to load this double row tapered roller bearing 1, the double row tapered roller bearing the ratio of the basic dynamic load rating C _r of 1 (F _a / C
_The effect of _r ) on the life of the double-row tapered roller bearing 1 is as shown in FIG. In the case of the double-row tapered roller bearing 1 for supporting both ends of the cylinder of the printing press, in consideration of the characteristics as shown in FIG. A preload of about 3% of the basic dynamic load rating of the row tapered roller bearing 1 is applied. The inner diameter dimension R ₆ is 150 to 200 mm, outside diameter D ₈ 220
～280Mm, the width W ₂ of the inner ring assembly 2 is about 90～120Mm, double row tapered roller bearing for the cylinder of the printing press 1
In this case, the load for applying the preload is about 5 to 10 KN.

Therefore, as described above, a load for applying a preload to the double-row tapered roller bearing 1 before the outer ring assembly 3 is fitted and fixed in the housing is applied to the double-row tapered roller bearing 1. The reason why the basic dynamic load rating is set to about 3% will be described below. In the case of the double-row tapered roller bearing 1 for supporting the cylinder of the printing press, the load factor ε during operation is set to 1.0, preferably 1.1 in order to increase the rigidity with emphasis on printing quality. I'm going over it. This condition is the lower limit of the preload. Note that the load factor is a numerical value indicating the size of the load zone, and a value exceeding 1.0 indicates that all the tapered rollers 4, 4
Means that there is no play in the radial direction in the double row tapered roller bearing 1. Accordingly, the cylinder supported by the double-row tapered roller bearing 1 having an angular load factor ε exceeding 1.0 does not rattle, thereby preventing the occurrence of printing double.

In the case of a double-row tapered roller bearing for supporting the cylinder of a printing press, the radial load during operation of the printing press is very small, and is at most about 2% of the basic dynamic load rating. the radial load applied to double-row tapered roller bearings during operation of the printing press F _r, a thrust load F _a, when the contact angle of this double row tapered roller bearing and alpha, is set to the preload, F _r / since it is _{F a = 2/3 = 0.67} , if the contact angle α of the bearing 0.52rad (30 °) _{below, F r · tanα / F a} < becomes 0.385, epsilon>
1.0 is satisfied. It should be noted that the value of ε and F _r · tanα / F _a
There is a correlation between the _{values, F r · tanα / F a} <0.5
In the case of 268, ε> 1.0. As will be described later, the preload increases during operation of the double-row tapered roller bearing, and the load factor increases. Therefore, the load factor at the time of setting the preload may be set to be 1 or more.

On the other hand, the upper limit of the preload is set so that the life time of the sheet-fed press is 100,000 hours or more, and that of the rotary press is 40,000 hours or more. As mentioned above, the radial load during operation of double row tapered roller bearings to support the printing cylinder is very small,
This value is about 2% of the basic dynamic load rating. The rotation speed during operation is about 100 to 350 min ^-1 for a sheet-fed press, and about 600 min ^{-1 for} a rotary press. Taking into account the reduced life due to preload and the above operating conditions shown in FIG. 3 described above, if the preload during operation is reduced to 0.1 times or less of the basic dynamic rated load by a simple calculation, the required life It is understood that can be satisfied. In the actual design, the preload is set to a value of about 0.08 times the basic dynamic load rating with some margin. The preload increases when the outer ring assembly 3 is fitted to the housing after the preload is set. Furthermore, since the temperature of the inner ring assembly 2 becomes higher than the temperature of the outer ring assembly 3 during operation, the preload increases further due to the difference in the amount of thermal expansion between the two assemblies 2 and 3.

On the other hand, the composite roughness σ _L of the contact portion between the large-diameter end faces 13, 13 of the tapered rollers 4, 4 and the side faces 12 of the large-diameter flanges 11, 11 is used as a parameter, and FIG. 4 shows the relationship between the preload applied to the row tapered roller bearing 1 and the dynamic torque of the double row tapered roller bearing 1. In FIG. 4, the vertical axis represents the tangential force because, as described above, the force at the time of pulling the string wound around the outer diameter portion of the outer ring assembly 3 is used as a substitute for dynamic torque. .
Further, the horizontal axis is a dimensionless amount, that is, a load (preload load) F in the axial direction applied to the double-row tapered roller bearing 1 described above.
and _a, the basic dynamic load rating C _r of the double row tapered roller bearing 1
(F _a / C _r ) so as to be applicable to double-row tapered roller bearings having different dimensions.

[0028] From such a 4, is 5~10KN (F _a / C _r corresponding to the preload to be applied to the double row tapered roller bearing 1 for supporting an end portion of the printing machine cylinder 0.025
0.040), the change in the tangential force based on the change in the preload (change in the tangential force / change in the preload) is calculated, and the relationship between the calculated value and the resultant roughness σ _L of the contact portion is calculated. FIG. 5 shows a graph. The reason why the vertical axis in FIG. 5 is set to the tangential force gradient is the same as that in which the vertical axis in FIG. 4 is set to the tangential force.

As described above, the preload of the double-row tapered roller bearing for supporting the cylinder of the printing press is 5 to 10 KN, but at least the setting error of the preload is 20% or less (1 KN).
Below). The scale (measurement accuracy) of the Push Pull Gauge used for measurement is usually 0.1 kgf (about 1 N). In order to ensure the measurement accuracy of 1 KN, the tangential force gradient needs to be 0.001 (= 1/1000) or more. As is clear from FIG. 5, the tangential force gradient is 0.001.
Is a point where the synthetic roughness is about 0.2 μmRa. Therefore, as described above, the combined roughness σ _L of the contact portion between the large-diameter side end surfaces 13, 13 of the tapered rollers 4, 4 and the side surfaces 12 of the large-diameter flange portions 11, 11 is set to 0. The value exceeds 2 μmRa (more preferably, 0.25 μmRa).

Next, the rolling surface 1 of each of the above-mentioned tapered rollers 4 and 4 will be described.
The reason why the combined roughness σ _S of the rolling contact portions of the inner and outer raceways 5 and 5 and the outer raceways 7 and 7 is less than 0.2 μmRa will be described. Relationship between the combined roughness σ _S of the rolling contact portions between the rolling surfaces 14, 14 of the tapered rollers 4, 4 and the respective inner ring and outer ring raceways 5, 7, and the oil film parameter Λ of each of the rolling contact portions. Is as shown in FIG.
FIG. 6 is based on the result of calculation based on the above-described bearing specifications and operating conditions. The relationship between the oil film parameter Λ and the life of a general rolling bearing including a general double-row tapered roller bearing is as shown in FIG. In other words, the life of the tapered roller bearing becomes longer as the oil film parameter 大 き く increases. If the oil film parameter 程度 is about 1.5, a sufficient life can be secured. Then, the value of the combined roughness σ at which the oil film parameter な る of 1.5 can be obtained is about 0.2 μmRa as can be seen from FIG. Therefore, the rolling surfaces 14, 14 of the tapered rollers 4, 4 and the inner raceways 5, 5,
The double-row tapered roller bearing 1 having a combined roughness σ _S of a rolling contact portion with the outer ring raceways 7 and 7 of less than 0.2 μm Ra.
To ensure a long service life.

[0031]

Since the present invention is constructed and operates as described above, a double row tapered roller bearing having a large change in dynamic torque with respect to a change in preload is realized, and the durability of the double row tapered roller bearing is improved. It is possible to improve the performance of various devices such as a printing machine while securing the same.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a double-row tapered roller bearing to which the present invention is applied.

FIG. 2 is a diagram showing a relationship between a preload applied to a double-row tapered roller bearing and a dynamic torque of the double-row tapered roller bearing.

FIG. 3 is a diagram showing a relationship between a preload applied to a double-row tapered roller bearing and the life of the double-row tapered roller bearing.

FIG. 4 shows the preload applied to the double-row tapered roller bearing and the dynamics of the double-row tapered roller bearing, using the combined roughness of the contact portion between the large-diameter end face of the tapered roller and the side face of the large-diameter flange as a parameter. FIG. 4 is a diagram illustrating a relationship with torque.

FIG. 5 is a diagram showing a relationship between a combined roughness of a contact portion between a large-diameter end surface of a tapered roller and a side surface of a large-diameter flange portion and a torque gradient indicating a rate of change in dynamic torque.

FIG. 6 is a diagram showing a relationship between a combined roughness between a raceway surface and a rolling surface of a tapered roller and an oil film parameter.

FIG. 7 is a graph showing a relationship between an oil film parameter and the life of a rolling bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Double row tapered roller bearing 2 Inner ring assembly 3 Outer ring assembly 4 Tapered roller 5 Inner ring raceway 6 Inner ring element 7 Outer ring raceway 8 Outer ring element 9 Outer ring spacer 10 Cage 11 Large diameter side flange part 12 Side surface 13 Large diameter side end face 14 Rolling surface 15 Lubricating oil flow path

Claims (2)

[Claims] 1. An inner ring assembly having a plurality of rows of inner ring raceways each having a conical convex shape on the outer peripheral surface and inclined in opposite directions, and a plurality of rows of outer ring raceways each having a conical concave shape on the inner peripheral surface. An outer ring assembly having, a plurality of tapered rollers each of which is rotatably provided between each of the outer ring raceways and each of the inner ring raceways, formed on the outer peripheral surface of the large diameter end of each of the inner rings, In a double-row tapered roller bearing having an outwardly flanged large-diameter flange portion whose side surface is opposed to the large-diameter end surface of each of the tapered rollers, the rolling surface of each of the tapered rollers and each of the inner rings are provided. The synthetic roughness of the contact portion between the large-diameter end face of each of these tapered rollers and the side surface of the large-diameter flange portion is larger than the synthetic roughness of the contact portion between the raceway and the outer ring raceway. Double row tapered roller bearing. 2. The method according to claim 1, wherein the combined roughness of the contact surface between the rolling surface of each tapered roller and each of the inner raceway and the outer raceway is less than 0.2 μmRa, and the large-diameter end face of each of the tapered rollers and the large-diameter flange. The double-row tapered roller bearing according to claim 1, wherein a combined roughness of a contact portion with a side surface of the portion is set to a value exceeding 0.2 µmRa.