Antifriction bearing cage

Abstract

An antifriction bearing cage is disclosed including cage pockets that are used for guiding rolling elements, in particular balls, and are formed by two lateral rings having a common axis of symmetry (R) and by webs interconnecting the lateral rings. The lateral rings are designed as single pieces along with the webs and contain a fabric. The fabric is composed of at least two types of different fibers which impart highly anisotropic properties to the fabric.

Claims

1. An anti-friction bearing cage comprising cage pockets that are provided for guiding rolling elements and are formed by two lateral rings having a common axis of symmetry (R), connecting pieces connecting said lateral rings to define the cage pockets, wherein the lateral rings are formed integrally with the connecting pieces and contain a fabric, and the fabric is constructed from at least two types of different fibers, wherein the different types of fibers are contained in the fabric in a different arrangement from each other.

2. The anti-friction bearing cage according to claim 1, wherein the fabric contains a first type of the fiber that is oriented predominantly in a circumferential direction of the lateral rings and a second type of the fiber that is oriented predominantly in an axial direction.

3. The anti-friction bearing cage according to claim 2, wherein the fibers oriented predominantly in the circumferential direction have a higher tensile strength than the fibers oriented predominantly in the axial direction.

4. The anti-friction bearing cage according to claim 3, wherein synthetic fibers are provided as the fibers oriented in the circumferential direction and natural fibers are provided as the fibers oriented in the axial direction.

5. The anti-friction bearing cage according to claim 4, wherein the fibers oriented in the circumferential direction are selected from the group consisting of aramid fibers, basalt fibers, boron fibers, glass fibers, carbon fibers, PET fibers, and PTFE fibers.

6. The anti-friction bearing cage according to claim 4, wherein the fibers oriented in the axial direction are selected from the group consisting of bamboo fibers, cotton fibers, flax fibers, hemp fibers, jute fibers, ramie fibers, and sisal fibers.

7. The anti-bearing bearing cage according to claim 2, wherein fibers oriented in the circumferential direction have a lower coefficient of thermal expansion than the fibers oriented in the axial direction.

8. An anti-friction bearing comprising a number of rolling elements and an anti-friction bearing cage according to claim 1.

9. The anti-friction bearing according to claim 8, wherein balls are provided as the rolling elements.

10. The anti-friction bearing according to claim 9, wherein the bearing is a spindle ball bearing.

11. The anti-friction bearing according to claim 8, wherein cylindrical rollers are provided as the rolling elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An embodiment of the invention is explained in more detail below with reference to the accompanying drawings. Shown are:

(2) FIG. 1 a spindle ball bearing constructed as an angular contact ball bearing in a section view, and

(3) FIG. 2 a fabric contained in the cage of the anti-friction bearing according to FIG. 1 in a schematic view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) An anti-friction bearing cage 1 is provided for guiding rolling elements 10, namely balls, of an anti-friction bearing marked overall with the reference symbol 9. The ball bearing 9 is constructed as a single-row angular contact ball bearing and is used as a fast-running spindle ball bearing in a machine tool. In terms of the principle function of the anti-friction bearing 9, reference is made to the prior art cited above, in particular, DE 10 2006 007 925 A1.

(5) The balls 10 of the anti-friction bearing 9 roll on bearing rings 11, 12, namely an inner ring 11 and an outer ring 12. The rotational axis of the ball bearing 9 identical with the axis of symmetry of the anti-friction bearing cage 1 is designated with R. The anti-friction bearing cage 1 is an outer rim-guided cage, wherein, between the outer periphery of the anti-friction bearing cage 1 and the inner periphery of the outer ring 12, a guidance clearance FS is given. Alternatively, the anti-friction bearing cage 1 is guided in a not shown way also by the rolling elements 10 or by the inner ring 11, that is, as a rolling element-guided or inner rim-guided cage.

(6) Each rolling element 10 of the ball bearing 9 is guided in a cage pocket 5 of the anti-friction bearing cage 1. The walls of the cage pockets 5 can have cylindrical shapes, as can be seen in FIG. 1. Alternatively, the cage pockets 5 could have spherically shaped surfaces. In each case, the anti-friction bearing cage 1 has two closed lateral rings 2, 3, wherein connecting pieces 4 extend between and are connected integrally to these lateral rings 2, 3, forming the cage pockets 5. The connecting pieces 4 and cage pockets 5 are provided with reference numbers only in FIG. 2 for the sake of clarity, although only a part of the anti-friction bearing cage 1 is visible in this representation.

(7) The anti-friction bearing cage 1 is constructed from a fabric 6 that is embedded in a plastic matrix made from epoxy resin or phenol resin. The fabric 6 shown symbolically in FIG. 2 is constructed from fibers 7 running in the warp direction, that is, in the circumferential direction of the anti-friction bearing cage 1, and fibers 8 running in the weft direction, that is, in the axial direction of the anti-friction bearing cage 1. The fibers 7, 8 differ from each other greatly in terms of their composition and mechanical properties, so that the fabric 6 has extremely anisotropic properties.

(8) The fibers 7 running in the circumferential direction are high-strength synthetic fibers, for example, carbon fibers, or a mixture of different fibers designed for high tensile strength. For example, the fibers 7 running in the circumferential direction are a combination of two or three different types of fibers. The fibers 7 are selected in each case such that a rotation of the anti-friction bearing cage 1 leads to merely a slight expansion of the anti-friction bearing cage 1 and thus associated reduction of the guidance clearance FS, even at high rotational speed characteristic values of the ball bearing 9. The associated possible design of the ball bearing 9 with low guidance clearance FS ensures that, in each rotational speed range, there can be, at most, low eccentricity of the anti-friction bearing cage 1, which would lead to centrifugal and friction forces.

(9) In comparison with the forces acting in the tangential direction of the anti-friction bearing cage 1, the anti-friction bearing cage 1 is exposed to only relatively low forces in the axial direction even for operation at high rotational speeds. Accordingly, the fibers 8 of the fabric 6 running in the axial direction are not selected primarily from the aspect of tensile strength. Instead, homogeneous or mixed fibers are selected as the fibers 8 running in the weft direction of the fabric 6, which provides for good lubrication properties of the anti-friction bearing cage 1. In the embodiment, these are cotton fibers that are distinguished by good lubricant storage capacities.

(10) Due to the combination of different fibers 7, 8 in the same fabric 6, the anti-friction bearing cage 1 has a significantly more filigree construction with simultaneously increased load capacity and service life in comparison with conventional cages of spindle ball bearings.

LIST OF REFERENCE NUMBERS

(11) FS Guidance clearance R Rotational axis 1 Anti-friction bearing cage 2 Lateral ring 3 Lateral ring 4 Connecting piece 5 Cage pocket 6 Fabric 7 Fiber running in circumferential direction 8 Fiber running in axial direction 9 Ball bearing 10 Rolling element, ball 11 Inner ring 12 Outer ring