WO2013143695A1

WO2013143695A1 - Solid-film lubricated rolling bearing

Info

Publication number: WO2013143695A1
Application number: PCT/EP2013/000929
Authority: WO
Inventors: Matthias MARQUART; Bernd Sauer
Original assignee: Technische Universität Kaiserslautern
Priority date: 2012-03-27
Filing date: 2013-03-27
Publication date: 2013-10-03
Also published as: DE102012006027A1

Abstract

The invention relates to a solid-film lubricated rolling bearing comprising a first bearing ring (3) and a second bearing ring (6) which is arranged coaxially and at a distance from the first bearing ring, the opposite surfaces thereof (4, 7) forming circular raceways (5, 8) for rolling elements (9). The rolling elements (9) are maintained in pockets (17) of an annular cage (11, 11'. 11'') arranged between the first bearing ring (3) and the second bearing ring (6). According to the invention, in order to increase the service life of the rolling bearing (1), one or more pockets (17) comprise at least one guiding surface (19) for stabilizing the cage run and at least one lubricating surface (18) for reducing the wear and tear. The at least one guiding surface (19) and the at least one lubricating surface (18) are made of different materials or different material compositions. In order to stabilize the cage run, the cage (11, 11', 11'') comprises at least one bearing surface (22, 28) which is concentric to the axis (2), said bearing surface forming a sliding bearing with a concentric bearing surface (4, 8) on the first bearing ring (3) or the second bearing ring (6).

Description

Description:

Solid lubricated rolling bearing Technical field:

The invention relates to a solid lubricant bearing according to the preamble of independent claim 1. Prior art:

Rolling bearings generally have two relatively rotatable bearing rings, rolling elements rolling between the bearing rings allowing relative movement of the rings relative to each other with a much lower friction compared to plain bearings. For this reason, rolling bearings are widely used both as radial bearings and as thrust bearings.

For a uniform load transfer from one bearing ring to the other is a

uniform distribution of the rolling elements over the circumference of the bearing rings desired. For this purpose, a ring-like cage between the two bearing ring, with a number of rolling elements corresponding number of pockets, which are intended to receive the rolling elements and arranged at a uniform circumferential distance. The cage follows the

Circular movement of the rolling elements about the bearing axis, guided by the surfaces in contact with the rolling surfaces of the pockets, especially the sides of the pockets stabilize the cage cage. In order not to affect the concentricity of the rolling bearing, should therefore be as little axial play between the pockets and rolling elements.

The life of a rolling bearing is essentially dependent on the material and

Processing quality of the individual bearing parts and the influences acting from the outside on the bearing influences such as load, dirt, moisture, temperature and the like. These factors, in their entirety, cause wear and tear which, when reached to a certain extent, affects the functioning of the rolling bearing.

In most cases, a grease or oil lubrication of rolling bearings has proven to achieve the maximum possible life of a rolling bearing. However, these have the great disadvantage that they are unsuitable in certain environments such as for use in a vacuum or at high temperatures at the bearing. Evaporate there

CONFIRMATION COPY Fats or oils, which causes a loss of lubricity. But even in environments with special requirements for cleanliness and hygiene, such as papermaking or the production of food, fluid lubricants pose a risk of contaminating the product to be manufactured.

As an alternative to grease or oil lubrication, therefore, lubrication with solid lubricants is known for certain applications, for example with graphite, molybdenum disulfide, polytetrafluoroethylene (PTFE) or soft metals. Solid lubricants fundamentally differ in their mode of action from fluid lubricants, since with solid lubricants in the

Rolling contact always has solid state friction. The coefficient of friction is thus usually an order of magnitude higher than for grease or oil lubrication.

Thus, from DE 199 81 108 B4 a rolling bearing with solid lubrication is known in which an inner ring is rotatable via rolling elements relative to an outer ring. To guide the rolling elements, an annular cage with uniformly distributed over the circumference pockets is provided between the outer ring and inner ring. Each bag serves to hold two

Rolling element with intermediate spacer, wherein the spacer consists of a self-lubricating solid. In contact with the rolling elements of the

Solid lubricant transferred to the rolling elements and further on the inner ring and outer ring. By suitable design and dimensioning of the spacers, it is possible to use in the manufacture of the rolling bearing, the spacers in the annular space between the inner ring and outer ring between two rolling elements and subsequently secured in this position by means of the cage against falling out; The spacers are thus loose between the rolling elements and bearing rings.

In addition, from DE 41 39 426 A1 a solid-lubricated deep groove ball bearing is known, which is composed of an outer ring and an inner ring, which have on their opposite sides running surfaces for a number of spherical rolling elements. The rolling elements are held by a ring-like cage at a uniform circumferential distance. The dry lubrication of the bearing is achieved by the running surfaces of the two bearing rings and the surfaces of the rolling elements are provided with a dry lubricating film. It proves to be disadvantageous that the lubricating film consumes relatively quickly on the running surfaces and surfaces compared to the grease or oil lubrication. In order to obtain a sufficient solid lubrication over a longer period, it is also known, the solid lubricant from a depot within the bearing by contact with the rolling elements on their surface, from where the solid lubricant reaches the running surfaces (transfer lubrication). Such a solution is disclosed in DE 42 10 060 A1, the rolling bearing also has an outer bearing ring and inner bearing ring with an intermediate cage, which forms pockets for receiving the rolling elements. Two solid lubricant bodies, which line the lateral areas of the pockets and form part-spherical receptacles for spherical rolling bodies, serve as depots.

From the US 4,492,415, DE 41 33 813 A1 and DE 10 2009 012 241 A1 solutions are known in which the entire cage is made of a doped with solid lubricant material to create solid lubricant depots. In this case, the cage may be integrally formed (US 4,492,415) or composed of segments (DE 10 2009 012 241 A1). All the aforementioned embodiments have the disadvantage that with increasing wear of the solid lubricant body or of the cage, the clearance between the rolling elements and the cage becomes larger, suffering from smoothness and the life of such a bearing.

DE 2 210 299 finally shows a solid lubricant bearing in the form of an axial deep groove ball bearing, in which therefore the two bearing rings are not radially, but axially opposite. The there disclosed, consisting of a solid lubricant cage is formed in two parts, wherein the two cage parts are clamped by means of spring elements axially against their associated treads. From the contact of the cage parts with the running surfaces results in the solid lubrication.

DESCRIPTION OF THE INVENTION Against this background, the object of the invention is to further increase the service life of a solid-lubricated roller bearing.

This object is achieved by a roller bearing having the features of patent claim 1. Advantageous embodiments will be apparent from the dependent claims.

The invention is based on the idea that the life of a solid-lubricated roller bearing significantly depends on the one hand, a continuous adequate lubrication of the moving bearing parts is present and on the other hand, a quiet and stable cage cage and thus concentricity of the bearing is guaranteed. The latter sets next to a high material and manufacturing quality of the bearing and an exact guidance of the cage during its rotation ahead.

As a solid lubricant in the context of the invention thereby substances are understood that are used in the solid state between two bodies to reduce friction and to reduce wear. These include both polymers such as

Polytetrafluorethylene (PTFE), polyamide and polyethylene as well as materials with layer structure such as graphite, molybdenum disulfide and boron nitride, as well as soft metals and

Metal oxides. These substances remain firm even at temperatures above 200 ° C. A permanently good solid lubrication is achieved in the prior art by the

Bags are formed by a body doped with solid lubricant, the contact surface of the rolling body concerned both the solid lubrication and the leadership of the cage. It is in the nature of things that these bodies consume over time and thus involve loss of the exact guidance of the cage. With the solutions known from the prior art, it is thus not possible to combine the two above-mentioned requirements for permanent lubrication and high concentricity properties.

It is the merit of the invention to solve this problem by a functional subdivision of the rolling elements receiving pockets of the cage, in which a first part of the pocket is formed by guide surfaces, which ensure a stable cage barrel and formed in the second part of lubricating surfaces is, which consist of a doped with solid lubricant material. Guide surfaces and lubricating surfaces form within the cage rigid, immovable surfaces that follow one another in the circumferential direction. The guide surfaces forming parts are made of a relatively wear-resistant material such as brass and the like, so that the guiding effect is maintained permanently.

On the other hand, the lubricating surfaces form contact areas with the rolling elements, from which the solid lubricant is released and transferred to the rolling elements, from where it subsequently reaches the raceways. The guide surfaces are thus formed wear-resistant to the lubricating surfaces. As a result, although the lubricating surfaces wear out gradually, the lateral stability of the cage, which is necessary for concentricity, is still maintained by the wear-resistant guide surfaces which are effective in the direction of travel.

According to the invention, the cage is guided not only by the rolling elements, but additionally by a sliding bearing on one of the bearing rings. Preferably, the bearing surface forming the sliding bearing is arranged on the rotating bearing ring, ie the bearing ring with which the rotating Component is connected. In rolling bearings with inner ring and outer ring, the formation of a sliding bearing with the inner ring is preferred. Due to the sliding contact of the cage on the rotating bearing ring, a tangential force is transmitted to the cage in the contact zone. The cage is thus pushed by the rotating bearing ring, with the result that the rolling elements are always in contact with the lubricating surface. The resulting between rolling elements and lubricating surface contact force ensures a continuous and effective solid lubrication of the bearing, even if the cage pockets already

due to wear are increased. Rolling bearings according to the invention therefore have an exceptionally long service life in comparison with known solid lubricant-lubricated roller bearings.

According to an advantageous embodiment of the invention, the pockets of circumferential openings are formed in the cage, are inserted into the insert parts, the material each having the function-dependent properties. For example, in a simple

Embodiment of the invention, the cage made of a relatively wear-resistant material, so that the side surfaces of the opening form the guide surfaces. In the opening then an insert of a doped with solid lubricant material can be used, from which the solid lubricant is transferred to the rolling elements and treads.

In a further development of this embodiment, the guide surfaces of a

Insert be made of appropriately wear-resistant material, which is inserted into the openings. In such an embodiment, the material for the cage can be chosen freely, regardless of its ability to form guide surfaces.

Likewise, it is conceivable that the cage essentially consists of a material doped with solid lubricant, in the pocket openings of which insert parts are used which form the guide surfaces. Brief description of the drawings:

The invention is described below with reference to an illustrated in the drawings

Embodiment explained in more detail, wherein further features and advantages of the invention will become apparent. As far as appropriate, the same reference numerals are used for identical or functionally identical features. It shows

Fig. 1 is an oblique view of a first embodiment of an inventive

Rolling bearing in a partially broken view,

2 is a view in the axial direction of the rolling bearing shown in Fig. 1,

3 shows a section through the rolling bearing shown in FIGS. 1 and 2 along the line III - III shown in FIG. 2,

4 shows a section through the rolling bearing shown in FIGS. 1 to 3 along the line IV - IV shown in FIG. 3,

5 is an oblique view of the cage of the rolling bearing shown in FIGS. 1 to 4,

Fig. 6 is an oblique view of the cage of another embodiment of a

rolling bearing according to the invention,

7 is a view in the radial direction on the cage shown in Fig. 6,

8 is a view in the axial direction on the cage shown in FIGS. 6 and 7,

9a shows a partial view of a further embodiment of the pocket-forming region of a cage according to the invention,

9b is a partial view of a development of the embodiment shown in Fig. 9a,

10 shows an oblique view of a further embodiment of a cage according to the invention,

Fig. 11 is an oblique view of the cage shown in Fig. 10 in ready to install state and

Fig. 12 is a view in the radial direction on the cage shown in Fig. 11. Detailed representation of the embodiments:

1 to 5 show a first embodiment of a rolling bearing 1 according to the invention in the form of a radial ball bearing, whose axis of rotation is designated 2. The rolling bearing 1 comprises a concentric to the axis 2 outer ring 3, the inner circumference 4 has a circumferential, circular cross-section in the recess, which forms an outer raceway 5. At a radial distance from the outer ring 3, a turn to the axis 2 concentric, smaller diameter inner ring 6 is arranged along the outer circumference 7 also surrounds an inner race 8 forming recess with circular arc-shaped cross-section. In which between outer ring 3 and inner ring 6 adjusting annular space can be seen a number of spherical rolling elements 9, which engage with a part of its spherical surface while maintaining a necessary clearance play positively in the raceways 5 and 8. In the present embodiment, the outer ring 3 is the rigid bearing part and the inner ring 5, the rotating bearing part, which may be reversed in other embodiments, however. The clockwise pointing direction is designated 10.

In order to ensure a uniform load transfer from the inner ring 6 in the outer ring 7, a ring-like cage 11 is arranged in the annular space between the outer ring 3 and inner ring 6 concentric to the axis 2, which holds all the rolling elements 9 in a uniform circumferential distance to each other; the rolling elements 9 are thus distributed uniformly over the circumference of the rolling bearing 1.

As is apparent in particular from Fig. 5, which shows the cage 11 in an isolated view, the cage 11 is composed of frame-like segments 12, each segment 12 is formed by two parallel, pointing in the direction of 10 peripheral webs 14, the perpendicular to about extending axial webs 13 are connected. Axial webs 13 and peripheral webs 14 form in this way rectangular frame openings, in each of which a first insert member 15 and second insert member 16 are inserted positively. The two insert parts 15 and 16 thus sit rigidly and immovably in the frame opening and extend with respect to the running direction 10 in each case to the middle of the frame opening and have at the facing axially extending edges in each case a semicircular recess, which together form a circular pocket 17 , which in turn is intended to receive a rolling element 9. The inserts 15 and 16 are arranged in this way in the circumferential direction successively. The first insert part 15 is arranged in the rear half of the frame opening relative to the running direction 10 and consists of a solid lubricant, for example Molybdenum disulfide (MoS2), doped material. The soffit surface of the semicircular

Recess forms a rigid contact surface with the rolling elements 9 and at the same time a lubricating surface 18. In the present embodiment, the extends

lubricating surface over half the circumference of the rolling element. 9

The second insert 16 is in the front with respect to the direction 10 of the

Inserted frame opening and consists of a compared to the first insert part 15 more wear-resistant material such as brass. The soffit surfaces of the

semicircular recess are also in contact with the rolling elements 9 and form in this way guide surfaces 19, with which the cage 11 against the

Rolling elements 9 is supported. By concerns of the guide surfaces 19 on the rolling elements 9 of the cage 11 is guided during rotation of the inner ring 6. In particular, the lateral regions of the guide surface 19 formed by the two legs of the second insert part 1G ensure lateral stability.

For insertion of the inserts 5 and 16, the peripheral webs 14 are detachably formed from the rest of the cage 11, which is particularly simple, for example, when the individual peripheral webs 14 are connected to form a ring. After loosening the peripheral webs 14, the insert parts 15 and 16 are axially insertable into the frame openings, wherein the position securing the insert parts 15 and 16 respectively via a groove 20 (FIG. 3) on the outer edges of the inserts 15, 16 takes place, the Axial webs 13 and circumferential webs 14 receives positively. After inserting the inserts 15 and 16, the peripheral webs 14 are rejoined together with the rest of the cage 11, which can be done by means of snap-in connections, screws, rivets or gluing.

Another - not shown - embodiment provides to insert the inserts radially from the inside out into the frame openings. They form along the

Frame opening extending edges of the inserts from a lateral projection on the cylindrical shaft of the insert parts. The projection runs when inserting the insert parts in the manner of a stop on the inner circumference of the cage and thus limits the insertion depth of the insert parts.

In contrast to the second insert part 16, which maintains a clear radial distance to the inner ring 6, the insert member 15 forms a radial projection 21 in the direction of the axis 2, which extends to the outer periphery 7 of the inner ring 6 to the outer periphery 7 a flat guide 22 of the cage 11 on the inner ring 6 to obtain. The cage 11 is thus guided in the radial direction with its projection 21 along the outer circumference 7 of the inner ring 6 and in the axial direction by the pockets 17 forming guide surfaces 19, resulting in a total of a very stable and quiet cage cage.

FIGS. 6 to 8 show an alternative embodiment of a cage 11 'which, for example, can be inserted in the rolling bearing 1 described therein instead of the cage 11 described in FIGS. 1 to 5. The cage 11 'consists essentially of a one-piece ring 25 made of a wear-resistant material, such as brass or a suitable plastic. The running direction of the cage 11 during operation of the rolling bearing 1 is again indicated by the arrow 10. About the circumference of the ring 25 has a number of openings 26 which in

uniform circumferential distance from each other are arranged. The upstream in the direction of rotation 10 part of each opening 26 is complementary to the associated part of the

Rolling body 9 is formed, so enclosing in this way the rolling elements 9 over its half circumference and thereby forms a guide surface 19 which cooperates with the rolling elements 9.

The rear in the direction 10 part of the opening 26 has a rectangular shape and serves to receive an insert part 15 'of a material doped with solid lubricant. The

Insert part 15 'fits with three peripheral sides form fit in the rear part of the opening 26. The fourth side again has a complementary to the associated peripheral portion of the rolling body 9 shaped recess which forms the lubricating surface 18 and forms together with the opening 26 a circular pocket 17 , An insert 15 'is inserted from the inside radially outward in the rear part of the opening 26, wherein an integrally formed on the insert part 15', the three outer sides circumferential collar acts as a stop and limits the insertion depth.

In this way, the insert members 15 'with their radially inwardly facing projections 27 from a plurality of radially acting bearing surfaces 28, with which the cage 11' slidably supported on the outer circumference of the inner ring 6.

FIGS. 9a and b respectively show a plan view of further embodiments of FIGS.

inventive pockets 17 for receiving the rolling elements 9

Rolling bearing 1 is again indicated by 10. The part marked with the reference numeral 23 may be part of a cage ring or cage segment or else a separate one Insert that can be used in a cage ring.

In the embodiment shown in FIG. 9a, the guide surfaces 19 forming the pockets 17 continue on both sides of the rolling body 9 counter to the running direction 10. The

Guide surface 19 thus comprises two plane-parallel partial regions 19 ', whose distance corresponds to the axial width of the rolling elements 9 and whose length in the circumferential direction preferably corresponds to at least 0.5 times or at least 0.75 times the diameter of the rolling element. The area between the partial regions 19 'of the guide surface 19 serves for

Receiving an insert part 15 ", the lubricating effective surface 18 together with the guide surface 19, the pocket 17 for receiving a rolling element 9 forms.

Fig. 9a also shows in dashed line the pocket 17 in the state of advanced wear. It can be seen that the insert 15 "with increasing operating time of the

Rolling bearing 1 is smaller. Due to the two plane-parallel partial regions 19 ', however, the lateral guidance is maintained. Only in the direction of 10 creates a certain game.

The embodiment shown in Fig. 9b of a bag 17 according to the invention provides a

Further development of the previously described is, in which the wear-related increase in the pocket 17 and thus the game between the rolling elements 9 and cage 11 is compensated. For this purpose, the insert 15 "in the direction 10 is displaceable between the

Guide surfaces 19 'is held and biased by a spring element 29 in the direction of the rolling body 9. The spring element 29 thus ensures a constant contact force between the rolling body 1 and the insert part 15 "over the life of the rolling bearing 1. A further embodiment of a cage 11" according to the invention is shown in FIGS. The cage 11 "in turn comprises a single-piece ring 30 of a relatively wear-resistant material The ring 30 has pairwise opposed openings 31 each extending over a peripheral portion including two adjacent rolling elements 9. This results in a slit-like shape of the openings 31 a pronounced longitudinal extension direction in the circumferential direction, wherein each end of the opening 31 marks the region of a pocket 17. In each of the two end regions, one can see a guide surface 19, as has already been described in the context of the previously described embodiments.

In order to complete two pockets 17, in each case an insert part 15 '"of a material doped with solid lubricant is inserted rigidly and non-displaceably into the openings 31. The front and rear ends of the insert parts 15''in the running direction 10 are in their shape Rolling bodies 9 adapted and form with each of these a contact surface, which forms a lubricating surface 18 together with the guide surface 19, a circular pocket 17 for receiving spherical rolling elements 9. Similar to the embodiment described in FIGS. 6 to 8, the insert parts 15 "along their two longitudinal edges have an axial projection 24 which limits the radial insertion depth in the course of insertion of the insert parts 15"'. On the other hand, the radially inwardly directed projection 27 of the insert parts 15 "'enables the formation of a bearing surface 28, with which the cage 11 is supported on the outer circumference of the inner ring 6 and in this way receives a guide in the radial direction.

It is understood that the invention is not limited to the feature combinations of the embodiments described above, but also combinations of

Features of different embodiments includes. Likewise, the invention includes not only spherical rolling elements but also cylindrical, needle-shaped or otherwise formed

Rolling elements. Also within the scope of the invention are not only radial bearings, as described in FIGS. 1 to 12, but also thrust bearings. Furthermore, it is not necessary that each of the pockets 17 is formed in accordance with the invention. Rather, even such a pocket 17 is sufficient to accomplish the solid lubrication of the rolling bearing 1. Preferably, however, at least two or more pockets 17 according to the invention are distributed uniformly over the circumference of the cage 11, 11 ', 11 ".

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Claims

claims:

1. Solid lubricated roller bearing having a first bearing ring (3) and a coaxially and spaced second bearing ring (6) with their opposite surfaces (4, 7) circular raceways (5, 8) for rolling elements (9) form, wherein the rolling elements (9) in

Pockets (17) of an annular, between the first bearing ring (3) and second bearing ring (6) arranged cage (11, 11 ', 11 ") are held, wherein one or more pockets (17) at least one guide surface (19) for stabilizing the Cage run and at least one lubricating surface (18) for reducing wear, wherein the at least one guide surface (19) and the at least one lubricating surface (18) of different materials or different material compositions are formed, characterized in that the cage (11, 11 ', 11 ") at least one to the axis (2) concentric bearing surface (22, 28) which forms a sliding bearing with a concentric bearing surface (4, 8) on the first bearing ring (3) or second bearing ring (6).

2. Rolling bearing according to claim 1, characterized in that the bearing surface (22, 28) of a radial projection (21, 27) of the lubricating effective surface (18) forming the cage part is formed.

3. Rolling bearing according to claim 1 or 2, characterized in that the cage (11, 11 ', 11 ") in the circumferential direction of frame-like segments (12) is composed and at least in a frame opening to form at least one pocket (17) an insert part ( 15, 15 ', 15 ", 15"') is inserted, the rolling body (9) facing side forms the lubricating surface (18).

4. Rolling bearing according to one of claims 1 to 3, characterized in that the cage (11, 11 ', 11 ") in the circumferential direction of frame-like segments (12) is composed and at least in a frame opening to form at least one pocket (17) Inserted part (16) is used, the rolling body (9) facing side forms the guide surface (19).

5. Rolling bearing according to claim 1 or 2, characterized in that the cage (11, 11 ', 11 ") consists of a one-piece ring (25, 30) distributed over the circumference openings (26, 31) and at least in an opening (26, 31) for forming at least one pocket (17) an insert part (15, 15 ', 15 ", 15"') is inserted, whose the rolling body (9) facing side of the

lubricating surface (18) forms.

6. Rolling bearing according to claim 1 or 2, characterized in that the cage (11, 11 ', 11 ") consists of a one-piece ring (25, 30) distributed over the circumference openings (26, 31) and at least in an opening (26, 31) for forming at least one pocket (17) an insert part (15, 15 ', 15 ", 15"') is inserted, the rolling body (9) facing side forms the guide surface (19).

7. Rolling bearing according to one of claims 3 to 5, characterized in that the at least one frame opening or opening (31) for forming two respective rolling elements (9) receiving pockets (17) is determined and between the two pockets (17) an insert part (15 "') is inserted, the two rolling bodies (9) facing sides each form the lubricating surface (18).

8. Rolling bearing according to one of claims 1 to 7, characterized in that the at least one guide surface (19) and / or the lubricating surface (18) at least partially surround the rolling elements (9), preferably over half the circumference of the rolling body (9 ).

9. Rolling bearing according to claim 8, characterized in that the guide surface (19) on both sides of the rolling body (9) in the tangential direction with respect to the raceways (5, 8) continue and that the lubricating effective surface (18) forming the insert part (15 '. ) is disposed between the continued guide surfaces (19).

10. Rolling bearing according to one of claims 3 to 9, characterized in that the lubricating effective surface (18) forming the insert part (15 ') in the direction of the rolling body (9) displaceably mounted within a guide and biased against the rolling elements (9).

11. Rolling bearing according to one of claims 3 to 10, characterized in that the radial projection (21, 27) for forming a bearing surface (22, 28) of which the lubricating surface (18) forming the insert part (15, 15 ', 15 " , 15 "') is formed.

12. Rolling bearing according to one of claims 1 to 11, characterized in that the first bearing ring (3) and second bearing ring (6) are arranged radially or axially opposite one another.

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