JP2643415B2 - bearing - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing or a sliding bearing, and more particularly to a use in which an annular body forming a bearing is attached to a mating member having a different coefficient of linear expansion from this. In this case, it is intended to prevent damage due to an increase in applied load or thermal stress accompanying a temperature change.

[Conventional technology]

Conventionally, as a bearing structure when the linear expansion coefficient of the bearing ring body and the mating member are different, for example, LUBRICATION ENGI
An article on rolling bearings with spacers is published on pages 407-415 of the July 1981 issue of NIEERING. This bearing is the second
As shown in the figure, a retainer 51 is provided between an inner ring (bearing ring) 20 attached to a shaft (mating member) 10 and an outer ring (bearing ring) 30 attached to a shaft box (mating member) (not shown). The shaft 10 is made of a steel material, and the inner race 20 is made of a ceramic material. The inner ring 20 is a tapered surface in which both end surfaces in the axial direction expand outwardly with respect to the central axis, and are fitted to the shaft 10 by loose fit, and both end surfaces of the inner ring 20 are tightly fitted to the shaft 10. The bearings are supported in the axial direction by spacers (fixed annular bodies) 40, 40 made of steel material fitted together, and the load acting on the bearing is transferred from both end surfaces of the inner ring 20 to the shaft via the spacers 40, 40. It has a structure to transmit to 10.

Regarding the support of the spacers 40, 40 with respect to the inner ring 10,
The opposite end faces of spacers 40, 40 are brought into contact with both end faces of
Are slidably held in the radial direction, or both end surfaces of the inner race 20 and the opposing end surfaces of the spacers 40, 40 are joined and fixed integrally.

[Problems to be solved by the invention]

In the above-mentioned rolling bearing, when the inner ring 20 is supported so as to be slidable in the radial direction through the spacers 40, 40, when a radial load is applied to the bearing, the inner ring 20 receives less than the load. Since the wedge action occurs to push the spacers 40 and 40 outward in the axial direction with a large force, the contact surface pressure on the both end faces of the inner ring 20 increases, resulting in wear, breakage, and the limit of the applied load. Inconveniences such as reaching and destroying occur.

Also, when the inner ring 20 and the spacers 40, 40 are assembled to the shaft 10, since the inner ring 20 has a loose fit, relative slippage occurs between the inner ring 20 and the spacers 40, 40, and accurate centering is performed. However, the assembling work requires skill and there is a problem in workability.

Similarly, when the spacers 40, 40 are integrally joined and fixed to the inner ring 20, when a radial load is applied to the bearing, both end surfaces of the inner ring 20 and the joint end surfaces of the spacers 40, 40 are connected. Between the inner ring 20
In order to prevent the joint from being damaged at the joint portion, it is necessary to strengthen the fixing force at the joint surface, and a high joining technique is required.

The present invention solves the above-described problem, greatly increases the load that can be transmitted to a mating member through a bearing annular body having a different linear expansion coefficient from that of the mating member, and reduces the load between the bearing annular body and the mating member. It is an object of the present invention to provide a bearing capable of easily assembling the bearing easily.

[Means for solving the problem]

According to the present invention, in order to achieve the above object, at least one of a bearing annular body attached to a mating member has a different linear expansion coefficient from a linear expansion coefficient of a mating member. In a bearing in which a pair of fixing annular bodies that axially support both end surfaces in the axial direction are firmly engaged with a mating member, the fixing annular body has a linear expansion coefficient equivalent to that of the mating member or the bearing annular body. Has a coefficient of linear expansion intermediate between the mating member and the bearing ring, and the fitting surface of the bearing ring to the mating member is firmly fitted at the latest when the bearing is used. The bearing has a dimension set so that the maximum stress caused by the load applied to the bearing, the fitting thereof, and the temperature change is smaller than the allowable maximum stress of the constituent material of the bearing annular body.

The fixing annular body may be configured separately from the bearing annular body to sandwich and support both axial end surfaces of the bearing annular body,
At least one of the fixing annular members may be joined to the axial end surface of the bearing annular member and integrally fixed.

The bearing ring may have at least one end face in the axial direction formed as a tapered face. The angle of the tapered surface with respect to the cross section perpendicular to the axis is preferably set such that a predetermined relationship is established corresponding to the axial length and the diameter at the center of the thickness of the bearing annular body.

[Action]

The bearing annular body of the present invention is firmly fitted to the mating member at the latest when used as a bearing due to a relative dimensional change based on a difference in linear expansion coefficient between the mating member and a temperature difference between the mating member and the bearing. The load applied to the annular body is borne not only by the facing end face between the fixing annular body but also by the fitting surface between the bearing annular body and the mating member.

Moreover, the dimensions of the fitting surface of the annular bearing body are set such that the applied load and the maximum stress generated by the fitting and temperature change are smaller than the allowable maximum stress of the constituent material. The annulus does not break under the applied load.

Also, a tapered surface is formed on the axial end surface of the bearing annular body,
If the angle is set so that a predetermined relationship is established with respect to the axial length and the diameter at the center of the thickness of the bearing annular body, the difference in the coefficient of linear expansion of each component when a temperature change occurs. It is possible to prevent concentration of thermal stress at a contact or joint portion between the bearing annular body and the fixed annular body and concentration of thermal stress at a fitting surface between the bearing annular body and the mating member.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a radial cylindrical roller bearing. In this cylindrical roller bearing, a cylindrical roller 50 is interposed between an outer ring 30 and an inner ring 20, which are annular bearing bodies, and the cylindrical roller 50 is held and guided by a retainer 51 to roll.

An inner ring 20, which is one bearing ring, has an inner peripheral surface (fitting surface) 21 fitted to the shaft 10 as a mating member, and an outer ring 30, which is the other bearing ring, has an outer peripheral surface not shown. It is fitted to a shaft box which is a mating member.

The outer ring 30 of the above-mentioned cylindrical roller bearing is made of ordinary bearing steel, but the inner ring 20 is made of a ceramic material such as silicon nitride, for example, and has a linear expansion coefficient α _j of a shaft made of steel. It is smaller than the linear expansion coefficient of 10 α _s. Both end surfaces 22a and 22b in the axial direction of the inner ring 20 are
From the inner peripheral edge, the diameter increases in the direction of opening outward with respect to the central axis, and is formed on a tapered surface having an inclination angle of θ ₁ , θ ₂ with respect to a section perpendicular to the axis, and is fitted to the shaft 10 by a predetermined amount described later. They are fitted with a clearance Δd.

Both end surfaces 22a, 22b of the inner ring 20 are supported in the axial direction by spacers 40, 40, which are a pair of fixing annular bodies. These spacers 40, 40 have a linear expansion coefficient α _{k of} which axis 10
Linear expansion coefficient of the inner ring 20 a similar linear expansion coefficient alpha _s of alpha
material having a value greater than _j, or smaller than the linear expansion coefficient of the shaft 10 alpha _s, metallic material having a value larger than the linear expansion coefficient alpha _j of the inner ring 20, for example, special cast iron, of aluminum nitride or the like created (Α _j <α _k ≦ α _s ) or a material whose linear expansion coefficient α _k is equal to the linear expansion coefficient α _j of the inner ring 20 and has a smaller value than the linear expansion coefficient α _s of the shaft 10. Alternatively, it is made of a metal material having a value larger than the coefficient of linear expansion α _j of the inner ring 20 and smaller than the coefficient of linear expansion α _s of the shaft 10, for example, a Kovar alloy, an Elinvar alloy, or the like (α _j ≦ α _k < α _s ). The above spacers 40, 40
The inner peripheral surface (fitting surface) 41a is tightly fitted to the shaft 10 or is tightly fitted by the fit. Also, the zama
The end faces 42 a of the inner ring 20 facing the inner ring 20 are the side end faces 22 of the inner ring 20.
a, 22b are formed on tapered surfaces having the same angles as the inclination angles θ ₁ , θ ₂ . The spacers 40, 40 have the opposite end surface 42a
The inner ring 20 may be attached to the shaft 10 in a state where the inner ring 20 is clamped by being in contact with both side end faces 22a, 22b. At least one of the spacers 40, 40 has its end face 42a joined to the end face of the inner ring 20 to form an integral body. What is fixed to the shaft 10 may be attached to the shaft 10. Spacer 40,4
As a method of fixing the “0” to the inner ring 20, a generally used joining method of a metal material and a ceramic material can be used.

As described above, the inner ring 20 is in a state of being supported in the axial direction by the pair of spacers 40, 40 fixedly fitted to the shaft 10, and in this state, the inner peripheral surface 21 of the inner ring 20 and the shaft 10 are supported. The clearance Δd formed between the outer ring and the outer ring
Decrease due to the difference in linear expansion coefficient between 20 and shaft 10, the amount of clearance reduction due to relative dimensional change based on the temperature difference between when the bearing is mounted and when it is used, and at the latest when used, the tight fit due to interference fit It is set to generate a match state.

The dimension of the inner peripheral surface 21 of the inner ring 20 is determined by the maximum stress generated in the inner ring 20 when the bearing is used, that is, the maximum tensile stress generated on the inner peripheral surface due to the interference fit due to the decrease in the fitting clearance Δd. The total of the maximum tensile stress generated when a radial load is applied to the bearing and the maximum tensile stress generated by a temperature change is set to be smaller than the allowable maximum tensile stress of the ceramic material constituting the inner ring 20. I have.

The tapered surfaces of both end surfaces 22a and 22b in the axial direction of the inner ring 20 are formed at an angle such that the diameter of the inner ring 20 is reduced in the inward opening direction with respect to the central axis from the outer peripheral edge, opposite to the outward opening direction. Is also good.

Further, the spacers 40, 40 may be firmly engaged with the shaft 10 by using a means such as screw fastening, bonding, or the like.

In the cylindrical roller bearing of the above construction, at ambient temperature T _a during installation of the bearing fitted with a gap Δd fit by clearance fit to the shaft 10 to the inner peripheral surface 21 of the inner ring 20, the temperature T _b at the time of use of the bearing Considering the case where the inner ring 20 is raised, the fitting clearance during use of the bearing decreases by (α _s −α _j ) (T _b −T _a ) d when the diameter of the shaft 10 is d. The shaft 10 is firmly fitted to the shaft 10 by an interference fit having an interference amount of (α _s −α _j ) (T _b −T _a ) d−Δd.

When the bearing is used in this state, the dimension of the inner peripheral surface 21 is set so that the maximum tensile stress generated in the inner ring 20 is smaller than the allowable maximum tensile stress of the constituent material. Transmits part of the load to the shaft 10 via the inner peripheral surface 21 thereof without being damaged by the applied load, and the remaining load is transmitted to the spacers 40, 40 via the side end surfaces 22a, 22b. Through to the shaft 10. In this way, the load acting on the bearing is transmitted to the shaft 10 by sharing the load between the inner ring 20 and the spacers 40, 40, so that the inner ring 20 supports the spacers 40 supporting the both end surfaces 22a, 22b. , 40 is only transmitted to the opposed end surfaces 42a of the spacers 40, 40 by increasing only a part of the load acting on the bearing.

Therefore, when the opposed end surfaces 42a of the spacers 40, 40 are in contact with and sandwiched between the both end surfaces 22a, 22b of the inner ring 20, the contact surface pressure is reduced, and the damage and wear of the contact portions are reduced, resulting in breakage. Because it becomes difficult, the durability increases, and the spacer is attached to the inner ring 20
Similarly, when the opposed end surfaces 42a of the 40, 40 are joined and fixed integrally, the load transmitted to the joined surface is reduced, so that the joined portion is less likely to be broken and the durability is increased.

In addition, by setting the inclination angles θ ₁ and θ ₂ of the tapered surfaces formed on both end surfaces 22a and 22b of the inner ring 20 as follows, when the temperature at the time of mounting and during use of the bearing changes,
The influence of thermal stress generated on the contact surface or joint surface between the spacers 40, 40 of the inner ring 20 and the fitting surface between the inner ring 20 and the shaft 10 can be prevented.

That is, the axial length at the center of the thickness of the inner ring 20 is
Let W _{P be} the diameter D _{P and} both end faces 22a, 2 due to temperature change ΔT.
The axial length changes Δx ₁ , Δx ₂ and the radial length changes Δy ₁ , Δy _{2 of} 2b are: Becomes When there is no relative change in axial and radial length, Therefore, _assuming α _s ≠ α _j and ΔT ≠ 0, solving the above equations (1), (2) and (3) gives tan θ ₁ + tan θ ₂ = 2W _P / D _P (4) .

Θ ₁ and θ ₂ in the above equation are both side end faces 22a and 22b of the inner ring 20.
Is positive when the diameter of the tapered surface is increased in the outward opening direction, and negative when the tapered surface is reduced in the inner opening direction.

In the above embodiment, the case where the inner ring made of a ceramic material is attached to the shaft made of a steel material has been described. However, the present invention is not limited to such a case. The same applies to the case where the bearing is attached to a shaft made of the material described above, by determining the linear expansion coefficient of the spacer material so that the predetermined relationship similar to the above holds for the material of the inner ring and the shaft. can do.

In addition, the support of the inner ring by the spacer is not limited to the case where tapered surfaces are formed on both axial end surfaces of the inner ring as in the above-described embodiment, but also the two axial end surfaces or one end surface of the inner ring with respect to the center axis. It may be formed on an orthogonal vertical plane.

Further, the present invention is applicable not only to bearings having different coefficients of linear expansion between the inner ring and the shaft, but also to bearings having different coefficients of linear expansion between the outer ring and the shaft box.

Further, the present invention can be applied not only to the case where the temperature during use of the bearing is higher than the temperature at the time of mounting, but also to the case where the temperature during use is lower than when the bearing is mounted. .

Further, the present invention can be applied to not only the rolling bearing but also the case where the inner peripheral side member of the slide bearing is attached to the shaft and the case where the outer peripheral side member (bearing main body) is attached to the shaft box. it can.

〔The invention's effect〕

As described above, according to the present invention, in a bearing in which the linear expansion coefficient of the bearing annular body is different from that of the mating member, the load acting on the bearing is applied only by the fixing annular body that supports both end surfaces of the bearing annular body. In addition, since the bearing ring itself can share and transmit to the mating member, the bearing load that can be applied increases, or if the bearing load is the same, the effect that the durability life becomes longer is obtained. Even in the case where the fixing annular body for supporting the annular body is integrally fixed to the bearing annular body, the difficulty in the joining technique is solved.

In particular, when a tapered surface is formed on the axial end surface of the bearing annular body and the tapered surface is set at a predetermined angle, concentration of thermal stress due to temperature change can be prevented.

Further, according to the present invention, even if the fixing annular body is separate from the bearing annular body, the clearance between the bearing annular body and the mating member can be reduced when the bearing is mounted. Not only does the work become easier, but it also maintains high precision concentricity with the mating member when using the bearing, and suppresses vibration and rotational runout during the temperature change process at the beginning of operation, resulting in high performance. And a reliable bearing can be obtained.

[Brief description of the drawings]

FIG. 1 is an upper half longitudinal sectional side view showing an embodiment in which the present invention is applied to a cylindrical roller bearing, and FIG. 2 is an upper half longitudinal sectional side view showing a conventional cylindrical roller bearing. In the figure, 10 is a shaft (a mating member), 20 is an inner ring (annular bearing),
Reference numeral 21 denotes the inner peripheral surface of the inner ring, 22a and 22b denote both end surfaces in the axial direction of the inner ring, 40 denotes a spacer (fixing annular body), and 42a denotes an opposite end surface of the spacer.

Claims (4)

(57) [Claims] At least one of a bearing annular body attached to a mating member has a linear expansion coefficient different from that of the mating member,
In a bearing in which a pair of fixing annular bodies that axially support both end surfaces in the axial direction of the bearing annular body are firmly engaged with a mating member, the fixing annular body is equivalent to the mating member or the bearing annular body. Has a linear expansion coefficient of the value, or has a linear expansion coefficient of a value intermediate between the mating member and the bearing ring, the fitting surface of the bearing ring to the mating member,
At the latest, it is set so that the bearing is firmly fitted when the bearing is used, and the load applied to the bearing and the maximum stress due to this fitting and temperature change are smaller than the allowable maximum stress of the material constituting the bearing ring. A bearing having dimensions. 2. The bearing according to claim 1, wherein at least one of the fixing annular members is integrally fixed to an axial end face of the bearing annular member. 3. The bearing according to claim 1, wherein at least one end face in the axial direction of the bearing annular body is a tapered surface. 4. The bearing ring body, wherein the angles θ ₁ , θ ₂ of both axial end surfaces of the bearing ring body with respect to the cross section perpendicular to the axis are positive when the opening is outward with respect to the central axis, and negative when the opening is inward with respect to the center axis. The bearing according to claim 3, wherein a relationship represented by tan θ ₁ + tan θ ₂ = 2 W _P / D _P is set between the axial length W _P and the diameter D _P at the center of thickness of the bearing.