DE102013225996A1 - Plastic roller bearing cage for a thrust bearing and thrust bearing - Google Patents

Abstract

A plastic roller bearing cage (1), namely axial ball bearing cage, comprises two cage rings (2, 6), namely a radially inner cage ring (2) and a radially outer cage ring (6), and a number by the cage rings (2, 6) and by this connecting cage webs (3) limited, designed to accommodate each rolling element cage pockets (4), wherein the cage rings (2, 6) with the cage webs (3) are integrally formed and contain solid lubricant. The cage rings (2, 6) are offset from each other in their axial direction.

Description

Field of the invention

The invention relates to a trained as Axialkugellagerkäfig plastic rolling bearing cage, which contains solid lubricant.

Background of the invention

A roller bearing cage for an axial ball bearing is for example from the DE 10 2008 004 033 B4 known. This is a cage made of sheet steel, which is approximately W-shaped in longitudinal section and has pockets for the rolling elements limiting webs, which limit the freedom of movement of the rolling elements in the radial, axial and tangential direction of the cage.

From the DE 10 2011 075 505 A1 An axial roller bearing with a wave-shaped cage is known, which can be made of a metallic strip material or of plastic. Rolling body pockets of the cage have, at least in sections, an approximately semicircular course.

A radial ball bearing cage is for example from the EP 1 830 082 B1 known. This rolling bearing cage is made of a resin composition containing reinforcing fibers and 3 to 40% by weight of spherical carbon. The spherical carbon used as the solid lubricant may have an average particle diameter of 100 μm or less.

Another ball bearing cage with a solid lubricant is from the JP 2010-053971 A known. In this ball bearing cage, substances which are supposed to reduce the friction are unevenly distributed, the maximum density of these substances being given on the inner surfaces of cage pockets.

Object of the invention

The invention has for its object, a rolling bearing cage, namely axial ball bearing cage, over the cited prior art, especially in terms of durability, even under unfavorable environmental conditions such as lack of lubrication, further develop.

Description of the invention

This object is achieved by a plastic roller bearing cage with the features of claim 1. Further, the object is achieved by such a plastic roller bearing cage exhibiting rolling bearing according to claim 9.

Trained as Axialkugellagerkäfig plastic rolling bearing cage has in known per se form two cage rings and a number by the cage rings and by these integrally connecting cage webs limited, each receiving a rolling element trained cage pockets, wherein the cage ring and the cage bars contain solid lubricant. The cage rings are offset from each other in the axial direction of the roller bearing cage.

The area in which the cage rings, when viewed in the axial direction, overlap is preferably at most 90% of the height of the roller bearing cage measured in the same direction. Thus, the area in which a plane normal to the bearing axis intersects both cage rings fills at most 90% of the height of the cage measured in the axial direction of the bearing.

The webs thus do not extend exclusively in the radial direction of the roller bearing cage, but are descriptive obliquely, describing a conical structure, wherein the oblique orientation of the webs can also be given by a gradation within the webs. In any case, a so-called N-profile of the roller bearing cage is formed by the offset between the cage rings in the axial direction. This profile has, on the one hand, the advantage of a higher resistance to deflection compared to a flatter cage and, on the other hand, it is characterized by good mold release in the production of the roller bearing cage by injection molding.

The minimum width of each cage bar of the rolling bearing cage is in a preferred embodiment at least 25% and at most 75% of the diameter of each cage pocket, wherein the diameter of the cage pocket is slightly larger than the diameter of a guided in the cage pocket rolling element. The width of the cage bars is measured in the circumferential direction of the cage; the width of the cage rings, however, measured in the radial direction of the cage and thus the entire camp.

Trained as a cage of a thrust ball bearing roller bearing cage filled in contrast to conventional thrust bearing cages formed between the bearing discs of the thrust bearing space, viewed in the axial direction of the bearing largely. Preferably, the height of the axial bearing cage measured in the axial direction of the rolling bearing corresponds to at least 85% of the distance between the bearing disks and thus of the rolling body diameter. On roller bearing cage are according to an advantageous development of several axially outwardly directed material elevations, which can start on a bearing disc of the bearing. Optionally located on both sides of the rolling bearing cage material surveys, so that the Rolling bearing cage can contact both bearing discs. In this case, a contact between the cage and at least one bearing disc can be given either permanently or only under certain operating conditions. In the latter case, for example, strong vibrations of the bearing represent such operating conditions. The tarnishing of the material elevations of the cage on a bearing disk on which the rolling elements roll, in this case has a damping effect. At the same time thereby increased solid lubricant is transferred to the bearing plate and from there in turn to the rolling elements.

The number of arranged on one and the same side of the rolling bearing cage material surveys may be less than the number of cage pockets in a possible embodiment. Likewise, designs are feasible in which there is a material collection on each web of the roller bearing cage or in the transition region between each web and the cage ring. Also, from each land of material elevations, which project beyond the cage rings in the axial direction, extend in both axial directions of the cage. In any case, the number of cage pockets is preferably straight, which offers manufacturing advantages, in particular in the manufacture of the rolling bearing cage by injection molding.

In a particularly advantageous embodiment, at least one of the cage rings of the axial bearing cage simultaneously fulfills a sealing function, wherein it can engage in at least one annular groove in a bearing disk or both bearing disks of the axial ball bearing. The realized by the cage ring seal is formed here either as a contact seal or non-contacting seal. Also in the embodiment with a sealing ring, the axial bearing cage can have at least one cage ring and / or radially between the cage rings, namely on the cage webs, protruding in the axial direction of the bearing material surveys, with which the cage can start on a bearing disk, wherein the material surveys can be located on exactly one end face or on both end faces of the thrust bearing cage.

Another, thus combinable design of the thrust bearing cage has substantially radially extending, preferably curved ribs, which may be located on one or both end sides of the thrust bearing cage. These ribs, which can reinforce individual webs or each web of the thrust bearing cage, on the one hand increase the stability of the cage and on the other hand support the distribution of lubricant - if present - or surrounding medium in the axial ball bearing. In the case of a media-lubricated thrust bearing, the ribs of the cage significantly contribute to the cooling of the bearing. As with the above-described design with frontal material elevations on the cage, a starting of the ribs of the cage on a bearing disc of the thrust bearing, at least under certain operating conditions, can be provided.

The plastic roller bearing cage is particularly suitable for use in a low-lubricated or only initially lubricated bearings. Under a poorly lubricated bearings are rolling bearings, which - apart from the solid lubricant contained in the rolling bearing cage - are operated completely unlubricated, as well as media-lubricated bearings. In the case of media lubrication, instead of a lubricant, a substance which does not primarily have lubrication function is present in the bearing. Such a substance may for example be a liquefied gas, which is conveyed in a pump equipped with the roller bearing. Likewise, the medium, which acts on the rolling bearing, in particular surfaces, which are exposed to rolling loads, wetted to act an acid or alkali. Also in rolling bearings, which are operated under water, especially in seawater, and whose components are exposed due to lack or incomplete sealing directly to the surrounding water, it is called mediengeschmierten camps.

Polyetheretherketone (PEEK) is particularly suitable as plastic for producing the roller bearing cage. A particularly suitable material is PEEK 10/10/10. The base material polyetheretherketone in this material, which is also available with the label FC30 available on the market, each 10% PTFE (polytetrafluoroethylene), graphite, and carbon fibers added. In addition or as an alternative to the solid lubricant graphite, molybdenum disulfide (MoS ₂ ) may also be present in the plastic of the roller bearing cage. As a suitable cage material in addition to PEEK 10/10/10 PEEK 10/10/2 should be mentioned in particular. While graphite ensures good lubrication properties of the cage even when there is humidity, MoS ₂ is particularly suitable as a solid lubricant in the absence of atmospheric moisture or under vacuum. As base materials from which the rolling bearing cage can be made, in addition to PEEK in particular polyamide-imides (PAI) and polyimides (PI) may be mentioned. A common characteristic of the materials mentioned is their suitability for operation at high temperatures. The continuous use temperature at which the plastic rolling bearing cage is operable is preferably above 150 ° C., in particular above 200 ° C. Even when the temperature limits mentioned are reached, the strength of the plastic rolling bearing cage is only slightly reduced.

The plastic roller bearing cage according to the invention can be used in one-sided loadable thrust bearings as well as in two-sided acting bearings, that is, in thrust bearings, which are resilient in both axial directions.

BRIEF DESCRIPTION OF THE DRAWING Several exemplary embodiments of the invention will be explained in greater detail below with reference to a drawing. Here are shown in a partially simplified representation:

1 an axial ball bearing with a plastic cage in a schematic sectional view,

2 a more detailed section of a plastic roller bearing cage for the camp 1 .

3 and 4 a modified embodiment of a plastic rolling bearing cage for a thrust bearing,

5 and 6 a further embodiment of a plastic rolling bearing cage for a thrust bearing.

Detailed description of the drawing

Corresponding or equivalent parts are indicated in all figures with the same reference numerals. Unless otherwise stated, the following statements, for example materials used, refer to all embodiments.

In 1 is a total with the reference numeral 10 characterized thrust ball bearing outlines which two bearing washers 11 . 12 namely a housing washer 11 and a wave washer 12 , between which includes balls 13 unroll as a rolling element. The rolling elements 13 are made by a rolling bearing cage made of plastic 1 guided. The axis of rotation of the axial ball bearing 10 corresponds to the center or symmetry axis of the roller bearing cage designated S 1 , The rolling bearing cage 1 is arranged substantially in a plane normal to the central axis S level.

The rolling bearing cage 1 has two cage rings 2 . 6 namely, an inner cage ring 2 and an outer cage ring 6 , on. The cage rings 2 . 6 connecting cage bars 3 ( 2 ) extend substantially in the radial direction of the rolling bearing 10 , Between two each in the circumferential direction of the rolling bearing cage 1 adjacent cage bars 3 and the cage rings 2 . 6 each is a cage pocket 4 formed, in which a rolling element 13 , namely a ball, can be used. The cage bags 4 are shaped so that the cage bars 3 during assembly of the rolling bearing 10 at most minimal deformation. It can thus also less elastic, brittle materials for the production of rolling bearing cage 1 be used. In rolling bearing cage 1 contained solid lubricants may be evenly or non-uniformly distributed in its volume and on its surface. The rolling elements 13 can be made of steel, for example bearing steel 100Cr6 or a corrosion-resistant steel, or of a ceramic material, for example silicon nitride.

In the axial direction of the rolling bearing 10 has the rolling bearing cage 1 a height Ha up to at least 85% of the distance between the bearing washers 11 . 12 which is in in 1 shown case is identical to the rolling element diameter designated DW, corresponds. The entire extent of the rolling bearing 10 in the axial direction is designated as depth T, the outer diameter with D. The designated D ₁ inner diameter of the housing plate 11 corresponds to the inner diameter of the wave washer designated d 12 , In the embodiment according to 1 are the two bearing washers 11 . 12 identically designed and therefore interchangeable. Deviating from this, embodiments are also possible in which the bearing washers 11 . 12 differ from each other. In a manner not shown are preferably in both bearing discs 11 . 12 Grooves are incorporated, which are the raceways for the rolling elements 13 form.

How out 1 As can be seen, the two cage rings 2 . 6 offset from each other in the axial direction. As a result, each cage ring 2 . 6 from the adjacent bearing disc 11 . 12 only slightly spaced. Is the rolling bearing 10 Vibrations exposed, so is a striking of the rolling bearing cage 1 at the bearing discs 11 . 12 not only possible, but also advantageous, since this is associated with a dampening effect. Moves an imaginary, to the center axis S of the bearing 10 normal plane in the axial direction through the rolling bearing cage 1 , according to the arrangement 1 From left to right, this plane cuts initially only the smaller, radially inner cage ring 2 , If the plane is moved further, it cuts both cage rings 2 . 6 , The corresponding, both cage rings 2 . 6 cutting area is called overlap area 14 designated. The thickness of the overlap area measured in the axial direction 14 is in all embodiments less than 90%, preferably less than 80%, measured in the same direction height Ha of the rolling bearing cage 1 , The rolling bearing cage 1 to 1 has an overlap area 14 on whose extent more than 50%, but less than 70% of the axial height Ha of the rolling bearing cage 1 is.

The embodiment according to 2 differs from the embodiment according to 1 in that none of the symmetry axis S of the rolling bearing cage 1 normal level exists, both cage rings 2 . 6 cuts. In other words. The two cage rings 2 . 6 are offset without overlap in the axial direction against each other. A median plane ME of the rolling bearing cage 1 that is axial between the cage rings 2 . 6 lies and none of the cage rings 2 . 6 cuts is in 2 indicated by a vertical dot-dash line. Next is in 2 marked by a horizontal dot-dash line the position of a partial circle cylinder TZ. On the surface of the pitch circle cylinder TZ is the pitch of the rolling bearing 10 that is, the circle passing through the centers of all rolling elements 13 is laid. Furthermore, in 2 reinforcing structures 15 . 16 of the rolling bearing cage 1 recognizable, which through each cage web 3 are formed and on the front sides of the rolling bearing cage 1 flush with the inner cage ring 2 or with the outer cage ring 6 to lock. This means that one to the axis of symmetry S of the rolling bearing cage 1 normal plane, which at the inner cage ring 2 is present, including the reinforcing structure 15 affected. In an analogous manner, one also touches the axis of symmetry S of the roller bearing cage 1 normal level, which is on the inner cage ring 2 opposite end face of the rolling bearing cage 1 the outer cage ring 6 tangent, including the reinforcing structure 16 ,

The cage bridge 3 including the reinforcing structures 15 . 16 thus extends in the axial direction of the rolling bearing cage 1 over its entire height Ha. The on the side of the inner cage cage 2 arranged reinforcing structure 15 extends in the radial direction of the roller bearing cage 1 beyond the partial circle cylinder TZ outwards. On the other hand, it lies on the side of the outer cage ring 6 arranged reinforcing structure 16 radially within the pitch circle cylinder TZ. Overall, this is the case for the rolling bearing cage 1 between the bearing discs 11 . 12 exploited available space in both the axial and in the radial direction to a considerable extent, through the cage webs 3 , which extend not only in the radial direction, but to a lesser extent in the axial direction and thus slightly conical, a particularly favorable ratio between mass and mechanical strength of the rolling bearing cage 1 given is. The rolling bearing cage 1 is thus particularly suitable for operation at high speeds, even under unfavorable lubrication conditions.

The rolling bearing cage 1 is produced by injection molding and has, in addition to the plastic used as a base material, namely PEEK, a solid lubricant, namely graphite and / or MoS ₂ , which, by way of transfer lubrication of surfaces of the rolling bearing cage 1 , especially from the cage pockets 4 , about the rolling elements 13 on the through the bearing washers 11 . 12 formed raceways of the bearing 10 is transferable. Compared to conventional thrust bearing cages is the rolling bearing cage 1 to 1 designed much more massive and provides a significant wear volume available, the permanent relubrication of the bearing 10 during its operation contributes, while the function of the designated wear in the rolling bearing cage 1 preserved in the long term. The rolling bearing cage 1 is particularly suitable for dry-running and only minimally or initially lubricated rolling bearings and able to absorb significant friction-shear stresses. The permanent temperature at which the plastic roller bearing cage 1 Equipped rolling bearings 10 is operable at least 150 ° C. The rolling bearing 10 is suitable, for example, for use in the food industry as well as in pharmaceutical production plants.

In the embodiment of the 3 and 4 are located on both ends of the rolling bearing cage 1 curved ribs 7 . 8th which the cage bars 3 reinforce and at the same time a medium, especially water, in which the rolling bearing 1 is operated. Like the reinforcing structures 16 . 15 in the exemplary embodiment 2 , also close the ribs 7 . 8th on the front sides of the roller bearing cage 1 flush with the outer cage ring 6 or with the inner cage ring 2 from. Every cage bridge 3 including the ribs located on it 7 . 8th thus extends in the axial direction of the roller bearing cage 1 over its entire height Ha.

Ribs 7 . 8th are so swung that one between a rib 7 . 8th and one through the symmetry axis S of the rolling bearing cage 1 extending radial ray included angle in the middle region of the rib 7 . 8th , that is, at the narrowest point of the cage web 3 , minimal and at the ends of the rib 7 . 8th is maximum. Ribs 7 . 8th are thus in their outer, the cage rings 2 . 6 adjacent areas are most tangentially aligned, while in their middle areas stronger, but not perfect, radially aligned.

Every cage bridge 3 has a circumferentially measured minimum width, designated BS, and at least 25% of the diameter DW in the cage pockets 4 guided balls 13 equivalent. The rolling element diameter DW is, apart from a Käfiebaschenspiel the rolling elements 13 in the cage pockets 4 , with the inner diameter of the partially spherical shaped cage pockets labeled DT 4 , ie with the cage pocket diameter, identical. In new condition of rolling bearing cage 1 are the rolling elements 13 very low in play in the cage pockets 4 guided.

In the embodiment of the 5 and 6 has the rolling bearing cage 1 on every cage web 3 two the two end faces of the rolling bearing cage 1 facing, ie axially outward, in axial plan view rectangular material surveys 5 on. Each material survey describes a section of a cylindrical body, whose axis of symmetry within the rolling bearing cage 1 lies and in the tangential direction of the cage rings 2 . 6 runs.

The material surveys 5 can in particular in the case of vibrations of the rolling bearing cage 1 having rolling bearing 10 on the bearing discs, not shown here 11 . 12 start. Here, on the one hand, the vibration is damped and on the other solid lubricant on the track of the bearing discs 11 . 12 transfer. In the course of operation of the rolling bearing 10 subject to the material surveys 5 scheduled wear. In new condition of rolling bearing cage 1 is measured in the axial direction height Ha much larger, in the embodiment of the 5 and 6 more than 30% but less than 50% larger than the distance between the outer faces of the cage rings, designated Hr 2 . 6 , that is the axial height of the roller bearing cage 1 without material surveys.

Due to the spherical shape of the cage pockets 4 fulfilled the rolling bearing cage 1 even with partially or completely removed material elevations 5 his function. An additional function is the rolling bearing cage 1 after the 5 and 6 by an annular circumferential sealing strip 9 met, which to the inner cage ring 2 is formed. In a similar way, the outer cage ring 6 be integrally connected to a sealing element or even have a sealing function.

LIST OF REFERENCE NUMBERS

1

 Plastic rolling bearing cage

2

 inner cage ring

3

 cage web

4

 cage pocket

5

 material elevation

6

 outer cage ring

7

 rib

8th

 rib

9

 sealing strip

10

 Axial ball bearings, roller bearings

11

 bearing disk

12

 bearing disk

13

 Ball, rolling elements

14

 overlap area

15

 reinforcing structure

16

 reinforcing structure

BS

 minimum width of a cage bar

d

 Inner diameter

D

 outer diameter

D ₁

 Inner diameter

DT

 Cage pocket diameter

DW

 rolling element

Ha

 axial height of the roller bearing cage

Mr

 Height of the rolling bearing cage without material elevations

ME

 midplane

S

 Central axis, symmetry axis

T

 depth

TZ

 Part circular cylinder

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008004033 B4 [0002]
• DE 102011075505 A1 [0003]
• EP 1830082 B1 [0004]
• JP 2010-053971 A [0005]

Claims (10)

Plastic roller bearing cage ( 1 ), namely axial ball bearing cage, with two cage rings ( 2 . 6 ), namely a radially inner cage ring ( 2 ) and a radially outer cage ring ( 6 ), and with a number through the cage rings ( 2 . 6 ) and by this connecting cage webs ( 3 ) limited, each receiving a rolling element trained cage pockets ( 4 ), whereby the cage rings ( 2 . 6 ) with the cage webs ( 3 ) are integrally formed, containing solid lubricant and offset from each other in the axial direction. Rolling bearing cage ( 1 ) according to claim 1, characterized in that an overlapping area ( 14 ) in which one to the central axis (S) of the cage rings ( 2 . 6 ) normal plane both cage rings ( 2 . 6 ), measured in the axial direction, at most 90% of the measured in the axial direction height (Ha) of the rolling bearing cage ( 1 ) occupies. Rolling bearing cage ( 1 ) according to claim 1 or 2, characterized in that this several in the axial direction of the cage rings ( 2 . 6 ) material surveys ( 5 ) having. Rolling bearing cage ( 1 ) according to claim 3, characterized in that the material surveys ( 5 ) at the cage webs ( 3 ) are formed. Rolling bearing cage ( 1 ) according to one of claims 1 to 4, characterized in that the minimum width (BS) of each cage web ( 3 ) at least 25% and not more than 75% of the diameter (DT) of the cage pockets ( 4 ) is. Rolling bearing cage ( 1 ) according to one of claims 1 to 5, characterized in that at least one cage ring ( 2 . 6 ) extending in the axial direction sealing strip ( 9 ) is formed. Rolling bearing cage ( 1 ) according to one of claims 1 to 6, characterized by on the cage webs ( 3 ), S-shaped curved ribs ( 7 . 8th ). Rolling bearing cage ( 1 ) according to one of claims 1 to 7, characterized in that it is made of PEEK 10/10/10. Rolling bearing comprising a number of rolling elements ( 13 ), namely balls, a plastic rolling bearing cage ( 1 ) according to claim 1, as well as two bearing discs ( 11 . 12 ), which the balls ( 13 ), wherein the measured in the axial direction height (Ha) of the rolling bearing cage ( 1 ) at least 85% of the distance (DW) between the bearing discs ( 11 . 12 ) corresponds. Use of a roller bearing cage ( 1 ) according to claim 1 in a lack-lubricated bearings.

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