JPS61252917A - Locking device for ceramics bearing - Google Patents

Abstract

PURPOSE:To make a bearing accurately keepable to the specified position, by making both sides of a bearing inner ring and a bearing inner ring keeper contact with each other on a point, while maintaining the extent of clamping force with both ends of the inner ring. CONSTITUTION:The flank of a bearing inner ring keeper 3 at the side of a bearing inner ring 2a is formed into a conic surface in the same angle as that of the inner ring 2a. The bearing inner ring keeper 3, after being inserted into a shaft 1, makes both conic surfaces closely contact with each other, and presses the bearing inner ring 2a to a large diametral part of the shift 1, locking it tight thereto. In this connection, the flank at the opposite side to the inner ring keeper 3 of the bearing inner ring 2a is also formed into a conic surface. Accordingly, both come to point contact, absorbing an expansion difference, due to heat, between the shaft, the bearing inner ring and the bearing inner ring keeper, thus a bearing is keepable to the specified position in an accurate manner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device for a ceramic bearing suitable for use in high temperature, low temperature or other special environments.

[Conventional technology]

Ceramic bearings have recently come to be used in various fields because they have characteristics such as high heat resistance, wear resistance, corrosion resistance, chemical resistance, and high strength.

However, ceramic bearings generally have a smaller linear expansion coefficient than steel, so ceramic rollers
When installing a bearing on a rotating shaft, if you fix it with a locking screw as is done with ordinary steel bearings, if the environmental temperature rises during use, the shaft material (steel) and the bearing (ceramic Due to the linear expansion difference between the bearings (manufactured by the manufacturer), the dimensional difference between the bearing inner diameter and the shaft outer diameter becomes even larger (the interference is even larger), and as a result, an abnormally large tensile stress is applied to the bearing. However, in some cases, this alone may cause damage to the bearing. On the other hand, when the environmental temperature decreases, the interference becomes smaller, which loosens the bearing and causes vibration.

As a solution to this problem, there is a method of providing a predetermined gap between the inner diameter of the bearing and the outer diameter of the shaft, a method of inserting an elastic body between the inner circumference of the bearing and the outer circumference of the shaft (Japanese Patent Application Laid-Open No. 57-6121), etc. was proposed.

[Problem that the invention seeks to solve]

However, when using this method of mounting a bearing on a rotating shaft, it goes without saying that if there is a gap or lack of support rigidity in the installation, abnormal vibrations may occur during rotation, leading to early failure of the bearing. . Similarly, even if the bearing is installed correctly at the time of assembly, if the installation accuracy deteriorates in the usage environment, the result will be unusable, as described above.

Therefore, the present invention provides the following advantages: 1. When installing a bearing on a rotating shaft, the installation does not require a clearance; 2. Installation errors can be minimized; and 3. Excessive stress may occur due to changes in environmental temperature. 4. The installation does not cause any increase in errors due to changes in ambient temperature; 5. It can be easily used under various environmental conditions. The purpose is to provide a fixing device for ceramic bearings that can be used.

[Means and effects for achieving the object] According to the present invention, in a device for fixing a ceramic bearing to a shaft using a bearing inner ring holder and a tightening nut, both the side surface of the bearing inner ring and the side surface of the bearing inner ring holder are formed into a conical surface or By making one of the surfaces spherical and bringing them into close or point contact at a contact angle θ, relative movement of the contact surfaces or contact points occurs when the environmental temperature changes. The above problem can be solved by absorbing the difference in expansion due to

〔Example〕

Hereinafter, the present invention will be explained in more detail based on embodiments shown in the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, in which reference numeral 1 denotes a rotating shaft, and a bearing (ball bearing) 2 is attached to a small diameter portion at the end of the rotating shaft.

The bearing 2 has an inner ring 2a and an outer ring 2b made of ceramics. The inner diameter of the inner ring 2a is slightly larger than the outer diameter of the small diameter portion of the shaft 1, and both side surfaces thereof are beveled at an angle that expands outward to form a conical surface. The outer ring 2b of the bearing 2 is inserted and fixed into the axle box 5. Reference numeral 3 denotes a bearing inner ring holder, and its side surface on the bearing inner ring 2a side is a conical surface having the same angle as the side surface of the inner ring 2a.

After the bearing inner ring retainer 3 is inserted into the shaft 1, a tightening nut 4 screwed onto the threaded portion of the shaft l brings the conical surfaces on both sides into close contact, and presses and fixes the bearing inner ring 2a onto the large diameter portion of the shaft 1. Note that the side surface of the bearing inner ring 2a opposite to the inner ring retainer 3 is also a conical surface, and correspondingly, the stepped portion of the large diameter portion of the shaft 10 is also a conical surface.

Next, the present invention will be described in detail with reference to FIG. 2, which is an enlarged view of the portion indicated by arrow A in FIG.

In FIG. 2, solid lines indicate the assembled state at room temperature, and dotted and dashed lines indicate the state in which each part is displaced at high temperature.

The radius of the small diameter portion of the shaft 1 is ro, and the length is C excluding the threaded portion, into which the bearing inner ring 2a and bearing inner ring retainer 3 are fitted, and tightened with a tightening nut 4. .

The inner diameter of the bearing inner ring 2a is r (r>r), and the width at the radius between the sides is a. Further, the width at the position of the radius of the bearing inner ring presser 30 is b. And room temperature (
To), a+b=c. The bearing 2 is assembled with an annular gap of r-rQ between the bearing inner ring 2a and the shaft 1 at room temperature.

Consider a case where the environmental temperature rises by ΔT from room temperature T0 to T. Note that the shaft diameter r0 is the expected expansion difference Δ
The dimensions such as r0≦r−Δr are selected in consideration of r.

Therefore, on the contact surface between the bearing inner ring 2b and the bearing inner ring retainer 3, an arbitrary point P located at a mere distance from the shaft center is as follows. That is, 1. Displacement of the bearing due to temperature rise in the axial direction at point P (4P) is approximately as follows (rightward direction is assumed to be 10).

Amount of axial expansion...+aα, ΔT Axial component due to radial expansion...-Rα, ΔTtanθ Therefore, ΔP'=aα, Δ'1'-Rα, ΔTtanθ
2. Regarding the bearing inner ring presser, the displacement (ΔP") due to temperature rise in the axial direction at point P is similarly as follows.

Amount of axial expansion of shaft...10Cα3ΔTAmount of axial expansion of bearing inner ring holder...-bα, ΔτAxial component of radial expansion amount of bearing inner ring holder...-Rα, ΔTtanθ, therefore Δp
” se Cα3ΔT-1α, Δ'r-Rα, ΔTta
nθ3, to maintain the initial tightening force, ΔP'=Δ
P", so aαΔT−Rα1ΔTtanθ!=Qα, ΔT−t)α, ΔT−R(X*ΔTtanθ・
(1) That is, if a temperature difference occurs between the constituent members, the expected condition may be substituted for ΔT in the above equation. For example, due to heat generated by the bearing during operation, there may be a ∆ between the shaft and the bearing inner ring.
Considering the case where a temperature difference occurs in TB, the above equation (1) becomes
aα, (ΔT+ΔT))−Rα, (ΔT+ΔTn)ta
Since nθ=Cα3ΔT−bα, ΔT−Rα, ΔTtanθ, the value of θ may be corrected according to the following.

In reality, this correction amount is extremely small, and even if it is not corrected, the bearing fixing force increases, which is on the safe side, so it is often not necessary in practice.

In the above embodiment, the contact surfaces are both conical surfaces and are displaced in close contact, but one can be a conical surface and the other is a spherical surface for point contact, and the same result can be obtained in that case.

〔Effect of the invention〕

In the present invention, the bearing is fitted onto the shaft with a gap, the side surface of the bearing inner ring and the side surface of the bearing inner ring retainer are both conical surfaces, or one of them is a spherical surface, and both are brought into close or point contact at a contact angle θ. Even if the environmental temperature changes, the bearing inner ring will not be damaged by excessive tensile force, and even if the shaft and bearing inner ring retainer expand or contract, the tightening force on both ends of the inner ring will be maintained, so ceramics Bearings can always be held accurately in a predetermined position.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of an embodiment of the present invention. FIG. 2 is an enlarged sectional view of main parts for explaining the function. 1...Rotating shaft 2...Bearing 2a...Bearing inner ring 2b...Bearing outer ring 2C...Ball 3...Bearing inner ring retainer 4...Tightening nut 5...Axle box

Claims (2)

[Claims] (1) In a device that fixes a ceramic bearing to a shaft using a bearing inner ring holder and a tightening nut, both the side surface of the bearing inner ring and the side surface of the bearing inner ring holder are conical surfaces, or one of them is a spherical surface, and both are closely held at a contact angle θ. Or, by making point contact, a relative displacement occurs at the contact surface or the contact point when the environmental temperature changes, and the difference in expansion due to heat of the shaft, the bearing inner ring, and the bearing inner ring retainer is absorbed. Fixing device for ceramic bearings. (2) The contact angle θ is θ=tan^-^1 (cα_3-bα_2-aα_1)
/[R(α_2-α_1)] where α_1, α_2, α
_3 is the linear expansion coefficient of the bearing, bearing inner ring retainer, and shaft, respectively, and a, b, and c are the lengths of the bearing mounting portion of the shaft excluding the bearing inner ring, bearing inner ring retainer, and threaded portion at the radius R position, respectively. An apparatus according to claim 1.