JPH02217612A - Bearing - Google Patents

Abstract

PURPOSE:To increase loads and make it possible to readily carry out accurate assembly by setting the coefficient of linear expansion of a fixing annular body in a specific relationship to that of its partner member and a bearing annular body, and setting the fitting face of the bearing annular body to be brought in a firm fitting state when the bearing is in use, and also setting the maximum stress smaller than the allowable maximum stress. CONSTITUTION:A spacer 40 (fixing annular body) has a coefficient of linear expansion equal to that of a shaft 10 (partner member) or that of an inner ring 20 (bearing annular body) or to the middle point between that of the shaft 10 and that of the inner ring 20, and the fitting face of the inner ring 20 against the shaft 10 is firmly fitted when the bearing is in use, and the maximum stress of the inner ring 20 is set smaller than the allowable maximum stress of the component material of the inner shaft 20. The inner ring 20 transfers a part of loads to the shaft 10 via an inner peripheral face 21 without braking the shaft, and the remaining loads are transferred to the shaft 10 through the spacer 40, 40. The contact surface pressure between the inner ring 20 and the spacer 40, 40 is therefore reduced, and damage and abrasion of the contact portions are reduced and durability is increased. Also, because the fitting clearance can be made smaller, assembling work is facilitated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to (1) a rolling bearing or a sliding bearing, and in particular, an annular body constituting the bearing is attached to a mating member having a linear expansion coefficient different from that of the annular body. This is to prevent damage caused by increased load, thermal stress due to temperature changes, etc. when used.

[Prior Art] Conventionally, as a bearing structure when the linear expansion coefficients of the bearing annular body and the mating member are different, for example, LtlBRrcAT
An article about rolling bearings with spacers is published on pages 407 to 415 of the July 1981 issue of ION ENGINEERING. This bearing, as shown in Figure 2,
Inner ring (bearing annular body) 2 attached to shaft (mating member) 10
0 and an outer ring (bearing annular body) 30 attached to an axle box (a mating member, not shown), cylindrical rollers 50 are held and guided by a cage 51, and the shaft 10 is made of steel. , the inner rings 20 are each made of ceramic material. The inner ring 20 has tapered surfaces that expand outwardly with respect to the central axis, and is fitted with a clearance fit on the shaft 10.
It is supported in the axial direction by spacers (fixing annular bodies) 40.
, 40 to the shaft 10.

To support the spacers 40, 40 with respect to the inner ring IO, the opposing end surfaces of the spacers 40, 40 are brought into contact with both end surfaces of the inner ring 20, and the inner ring 20 is slidably attached in the radial direction, or the inner ring 20 is Either side end surfaces and the opposing end surfaces of the spacers 40, 40 are joined and fixed integrally.

[Problem to be solved by the invention]

In the above rolling bearing, the inner ring 20 has a spacer of 40.40 mm.
If it is slidably supported in the radial direction through
When a radial load is applied to the bearing, the inner ring 20
Since a wedge action occurs that tries to push the spacers 40, 40 outward in the axial direction with a force greater than the load, the contact surface pressure on both end surfaces of the inner ring 20 increases, causing wear, damage, and load. This may cause inconveniences such as reaching its limit and destroying it.

Furthermore, when assembling the inner ring 20 and the spacers 40, 40 onto the shaft 10, since the inner ring 20 is a loose fit,
Relative slippage occurs between the inner ring 20 and the spacers 40, 40, making accurate centering difficult, and assembly requires skill, which poses a problem in terms of 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 In order to prevent the inner ring 20 from being damaged at the joint, it is necessary to strengthen the adhesion force at the joint surface, and advanced joining technology is required to prevent the inner ring 20 from being damaged at the joint. will be required.

The present invention solves the above problems, significantly increases the load that can be transmitted to the mating member through the bearing annular body having a coefficient of linear expansion different from that of the mating member, and also significantly increases the load that can be transmitted to the mating member through the bearing annular body and the mating member. [Means for Solving the Problems] In order to achieve the above object, the present invention aims to provide a bearing that can be easily assembled accurately. A pair of fixing annular bodies, in which at least one of the linear expansion coefficients is different from that of the mating member, are firmly attached to the mating member, and axially support both end surfaces of the bearing annular body having different linear expansion coefficients. In the bearing formed by the mating, the fixing annular body has a coefficient of linear expansion equivalent to that of the mating member or the bearing annular body, or a linear expansion coefficient of a value intermediate between that of the mating member and the bearing annular body. The fitting surface of the bearing annular body with respect to the mating member is firmly fitted at the latest when the bearing is in use, and the maximum stress due to the load applied to the bearing, this fitting, and temperature change is limited to the bearing annular body. The dimensions are set to be less than the maximum allowable stress of the materials of construction.

The fixing annular body may be separate from the bearing annular body and may be configured to support the bearing annular body by clamping both end surfaces of the bearing annular body in the axial direction, and at least one of the fixing annular bodies may be attached to the shaft of the bearing annular body. It may be joined to the direction end face and fixed integrally.

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

[Effect]

The bearing annular body of the present invention becomes tightly fitted to the mating member due to a relative dimensional change based on the difference in linear expansion coefficient and temperature difference between the bearing annular body and the mating member at the latest when used as a bearing. The load applied to the annular body is borne not only by the opposing end surface 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 mating surface of the bearing annular body are set so that the applied load and the maximum stress generated by this mating and temperature change are smaller than the maximum allowable stress of its constituent materials. The annular body will not break under the applied load.

In addition, if a tapered surface is formed on the axial end face of the bearing annular body and the angle is set so that a predetermined relationship is established with respect to the axial length and diameter at the thickness center of the bearing annular body, the temperature When a change occurs, the concentration of thermal stress at the contact or joint between the bearing annular body and the fixed annular body, or the thermal stress at the fitting surface between the bearing annular body and the mating member, based on the difference in linear expansion coefficient of each component. concentration can be prevented.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

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

The inner ring 20, which is one bearing annular body, has its inner circumferential surface (fitting surface) 21 fitted to the shaft 10, which is a mating member, and the outer circumferential surface of the other bearing annular body, the outer ring 30, is not shown. It is fitted into an axle 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, and its linear expansion coefficient αj is
The coefficient of linear expansion α is smaller than that of the shaft 10 made of steel. Both end surfaces 22a of this inner ring 20 in the axial direction
, 22b expands in diameter from the inner peripheral edge in the outward opening direction with respect to the central axis, and has a diameter of θ0. It is formed into a tapered surface with an inclination angle of θ2, and is fitted to the shaft 10 with a predetermined fitting clearance Δd, which will be described later.

Both end surfaces 22a and 22b of the inner ring 20 are supported in the axial direction by spacers 40 and 40, which are a pair of fixing annular bodies. The linear expansion coefficient α of these spacers 40° 40 is equivalent to the linear expansion coefficient α of the shaft 10, and the inner ring 2
Linear expansion coefficient α of 0.

or a metal material with a linear expansion coefficient α smaller than the linear expansion coefficient α of the shaft IO (or a linear expansion coefficient α of the inner ring 20), such as special cast iron, aluminum nitride, etc. or (αj〈α6≦α,),
Or, the linear expansion coefficient αk is the linear expansion coefficient α of the inner ring 20.
, and has a linear expansion coefficient α5 of the shaft 10, or a metal material having a linear expansion coefficient α5 larger than the linear expansion coefficient α of the inner ring 20 and smaller than the linear expansion coefficient α5 of the shaft 10, For example, it is made of Kovar alloy, Elinvar alloy, etc. (α, ≦α, <α,). The inner peripheral surfaces (fitting surfaces) 41a of the spacers 40, 40 are tightly fitted to the shaft 10 by a tight fit or a tight fit. In addition, the end surface 42 of the spacer 40.40 facing the inner ring 20
a is the inclination angle θ of both end surfaces 22a and 22b of the inner ring 20;
It is formed on a tapered surface having the same angle as 1θ2.

The spacer 40.40 may be attached to the shaft 10 with the opposing end surface 42a in contact with both end surfaces 22a, 22b of the inner ring 20 and sandwiching the inner ring 20, and at least one of the spacers 40.40 The end surface 42a may be joined to the end surface of the inner ring 20 and fixed integrally, and the end surface 42a may be attached to the shaft 10. As a method for fixing the spacer 40.degree. 40 to the inner ring 20, a generally employed method for joining metal and ceramic materials can be used.

As described above, the inner ring 20 is supported in the axial direction by the pair of spacers 40, 40 that are attached with a tight fit when the axle load is 0. In this state, the inner peripheral surface of the inner ring 20
The fitting clearance Δd formed between the inner ring 20 and the outer circumferential surface of the shaft 10 is determined by the relative difference based on the difference in linear expansion coefficient between the inner ring 20 and the shaft 10, and the temperature difference between when the bearing is installed and when it is in use. The clearance is reduced by the amount of reduction due to the dimensional change, and the setting is such that a tight fitting state due to interference fit is generated at the latest during use.

In addition, the dimensions of the inner peripheral surface 21 of the inner ring 20 are the maximum stress generated in the inner ring 20 when the bearing is used, that is, the maximum tensile stress generated in the inner peripheral surface due to interference fit due to a reduction in the fitting clearance Δd. , the sum of the maximum tensile stress that occurs when a radial load is applied to the bearing and the maximum tensile stress that occurs due to temperature change is set so that it is smaller than the allowable maximum tensile stress of the ceramic material that is the constituent material of the inner ring 20. There is.

Note that 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 decreases from the outer peripheral edge in the inward opening direction with respect to the central axis, contrary to the above-mentioned outward opening direction. Good too.

Further, the spacers 40, 40 may be firmly engaged with the shaft 10 by screw fastening, adhesion, or the like.

In the cylindrical roller bearing of the above configuration, when the bearing is installed, it is exposed to room temperature T, and the inner circumferential surface 21 of the inner ring 20 is fitted to the shaft 10 with a clearance Δd, and the temperature when the bearing is used rises to Tb. Considering the case where the bearing is used, the fitting clearance when using the bearing is (α, -αi) (Tb T, ) d, where d is the diameter of the shaft lO.
Since the inner ring 20 is (α,
-α, )(Tb-T,)a-Δd through interference fit, resulting in a tightly fitted state.

When the bearing is used in this state, the dimensions of the inner circumferential surface 21 are set so that the maximum tensile stress generated in the inner ring 20 is smaller than the maximum allowable tensile stress of its constituent materials. transmits a part of the load to the shaft 10 through its inner circumferential surface 21 without being damaged by the applied load, and the remaining load is transmitted to the respective spacers 40, 40 through both side end surfaces 22a, 22b. The axle load is transmitted to zero through the The load that acts on the bearing in this way is shared by the inner ring 20 and the spacers 40, 40 and transmitted to the shaft 10. , 40 axially outwardly, only a portion of the load acting on the bearing is increased and transmitted to the opposing end surfaces 42a of the spacers 40, 40.

Therefore, when the opposing end surfaces 42a of the spacers 40, 40 are in contact with and sandwiched between the opposite end surfaces 22a, 22b of the inner ring 20, the contact surface pressure is reduced, and the contact portions are less likely to be damaged or worn, and are not destroyed. Similarly, when the opposing end surfaces 42a of the spacers 40 and 40 are joined to the inner ring 20 and fixed together, the load transmitted to the joint surfaces is reduced. As a result, the joint part becomes difficult to break and durability increases.

Incidentally, the inclination angle θ1. By setting θ2 as shown below, if the temperature changes between when the bearing is installed and when it is in use, the contact surface or joint surface between the inner ring 20 and the spacer 40° 40, and between the inner ring 20 and the shaft 10. The influence of thermal stress generated on the fitting surface can be prevented.

That is, the axial length of the inner ring 20 at the center of wall thickness is W
7. Assuming the diameter as R, both end faces 2 due to temperature change ΔT
2a, 22b's axial length change ΔXI+ Δx2 and radial length change Δy7. Δy2 is as follows. The condition when there is no relative length change in the axial and radial directions is as follows. Therefore, assuming α, ≠ α4, ΔT≠0, the above formula (1)
, (2), (3), tan θ, +ta
n θ2 = 2 WP / D p ...
-(4) is obtained.

θ3 in the above equation. θ2 is both end surfaces 22a of the inner ring 20
, 22b is positive if the diameter thereof expands in the outward opening direction, and negative if the diameter decreases in the inward opening direction.

In the above embodiment, a case has been described in which an inner ring made of a ceramic material is attached to a shaft made of a steel material, but the present invention is not limited to such a case. The same applies to the case where the spacer is attached to a shaft made of a material of can do.

In addition, support of the inner ring by the spacer is not limited to forming tapered surfaces on both axial end surfaces of the inner ring as in the above embodiment, but also when supporting both axial end surfaces or one end surface of the inner ring with respect to the center axis. It may also be formed on perpendicular planes.

Further, the present invention can be applied not only to a bearing in which the inner ring and the shaft have different linear expansion coefficients, but also to a bearing in which the outer ring and the axle box have different linear expansion coefficients.

Furthermore, the present invention is applicable not only to cases where the temperature during use of the bearing is higher than the temperature at the time of installation, but also to cases where the temperature during use of the bearing is lower than the temperature at the time of installation. .

Furthermore, this invention is applicable not only to rolling bearings, but also when attaching the inner circumferential side member of a sliding bearing to the shaft and the outer circumferential side member (
When attaching the bearing body to the axle box, the same structure as above can be used.

[Effects of the Invention] As explained above, according to the present invention, in a bearing in which the coefficient of linear expansion of the bearing annular body is different from that of the mating member,
Because the load acting on the bearing can be transmitted to the mating member not only by the fixing annular body that supports both end surfaces of the bearing annular body, but also by the bearing annular body itself, the load that can be applied to the bearing increases. Alternatively, if the bearing load is the same, the durability life will be longer, and even if the fixing annular body that supports the bearing annular body is fixed integrally with the bearing annular body, there are difficulties in joining technology. is resolved.

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

Further, according to the present invention, even if the fixing annular body is separate from the bearing annular body, it is possible to reduce the fit clearance between the bearing annular body and the mating member when installing the bearing. Not only does this make the work easier, but it also maintains highly accurate concentricity with respect to the mating member when the bearing is used, and suppresses vibrations and rotational runout during the process of temperature changes in the early stages of operation, making it highly efficient. A bearing with good performance and reliability can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional side view of the upper half of a conventional cylindrical roller bearing without showing an embodiment in which the present invention is applied to a cylindrical roller bearing, and FIG. 2 is a vertical cross-sectional side view of the upper half of a conventional cylindrical roller bearing. In the figure, 10 is the shaft (mate member), 2o is the inner ring (bearing annular body), 21 is the inner peripheral surface of the inner ring, 22a, 22b are both end surfaces of the inner ring in the axial direction, 4o is a spacer (fixing annular body) , 42a are opposing end surfaces of the spacer.

Claims (4)

[Claims] (1) A pair of fixing annular bodies, in which at least one of the bearing annular bodies attached to the mating member has a coefficient of linear expansion different from that of the mating member, and which axially supports both end surfaces of the bearing annular body in the axial direction. In a bearing in which the fixing annular body is firmly engaged with a mating member, the fixing annular body has a coefficient of linear expansion equivalent to that of the mating member or the bearing annular body, or has a coefficient of linear expansion that is the same value as that of the mating member or the bearing annular body, or has a coefficient of linear expansion that is an intermediate value between the mating member and the bearing annular body. The fitting surface of the bearing annular body with respect to the mating member is in a hard fitting state at the latest when the bearing is in use, and the load applied to the bearing, this fitting, and the temperature A bearing characterized in that the dimensions are set such that the maximum stress caused by the change is smaller than the maximum allowable stress of the constituent material of the bearing annular body. (2) The bearing according to claim (1), wherein at least one of the fixing annular bodies is integrally fixed to an axial end surface of the bearing annular body. (3) The bearing according to claim (1) or (2), wherein at least one end surface in the axial direction of the bearing annular body is a tapered surface. (4) The angles θ_1 and θ_2 with respect to the cross section perpendicular to the axis of both end faces in the axial direction of the bearing annular body are positive when they open outward with respect to the central axis, and negative when they open inward, and the thickness center of the bearing annular body The bearing according to claim 3, wherein the relationship between the axial length W_P and the diameter D_P is set as follows: tanθ_1+tanθ_2=2W_P/D_P.