DE102007033904A1 - Angular ball bearing i.e. spindle ball bearing, for machine tool, has outboard with internal diameter gradient increasingly formed in neighboring region adjoining at flange of bearing surface in axial extension along direction of balls - Google Patents

Abstract

The bearing (1) i.e. spindle ball bearing, has balls (4) moveably arranged in a cage (5) e.g. plastic cage, between an outer ring (3) and an inner ring. External diameter gradient of the cage is decreasingly formed in a starting region (13) that lies opposite to a flange (7) of an outboard (6) along an axial extension in a direction of the balls. Internal diameter gradient of the outboard is increasingly formed in a neighboring region adjoining at a flange of a bearing surface (9) in the axial extension along the direction of the balls.

Description

Field of the invention

The The invention relates to an angular contact ball bearing, in particular a Spindle bearings, for a machine tool with an outer ring, an inner ring, a plurality of balls and a cage, with the balls in the cage between the outer ring and the inner ring are rotatably mounted, wherein the outer ring having an outboard facing the balls Side surface a part runway surface for the balls and its radially inwardly directed top surface a guide surface for the cage forms, so that the cage outboard at least on one side is and wherein the partial raceway surface and the guide surface a common peripheral edge or edge region form.

such Angular contact ball bearings are used, for example, as spindle bearings used in machine tools, these often for high speeds, z. B. over 15,000 revolutions / minute are designed. Especially with these high-speed rolling bearings, it has proved to be advantageous that the cages are not guided by rolling elements, but guided on the shoulders or Borden a bearing ring become. This causes problems with friction the rolling elements in the pockets are bypassed, as the Game of rolling elements in the cage pockets can be chosen large enough.

Such angular contact ball bearings are for example from the document DE 21 08 562 C2 or the publication DE 33 078 45 known.

In spite of This already adapted to the high speeds of construction Angular contact ball bearings, the friction development plays an increasing role, in particular by the friction in the angular contact ball bearings resulting temperature can cause problems. In the described type of angular contact ball bearings, there are two Main sources of friction that lead to a temperature increase of the rolling bearing can lead, namely on the one hand, the rolling contact and second, the cage friction on the guide board.

Of the Invention is based on the object, an angular contact ball bearing to suggest which improved operating characteristics at high Revs.

These Task is by an angular contact ball bearing with the features of claim 1. Preferred or advantageous embodiments The invention will become apparent from the dependent claims, the following description and / or the attached figures.

According to the invention proposed an angular contact ball bearing, so a ball bearing, its pressure angle preferably more than 10 ° with the radial plane includes. The angular contact ball bearing is for suitable for use as a spindle bearing in a machine tool and / or formed and preferably biased in the axial direction and / or prestressed.

The Angular contact ball bearing comprises an outer ring, a Inner ring and a plurality of balls, which in a cage spaced apart between the outer ring and inner ring are rotatably mounted. Preferably, the angular contact ball bearing designed as a single-row angular contact ball bearings, in modified Embodiments is also a multi-row arrangement of Balls conceivable.

outer ring and inner ring may also be components of a more complex Be unit, so the inner ring, for example, integral or integral part of a shaft or the like and / or the outer ring integral or one-piece Part of a rotatably mounted functional element.

Of the Outer ring has an outboard, which for example is rectangular in cross-section in the coarse shape, and its the side faces facing the balls a partial raceway surface forms for the balls. The career for the balls will thus in total by the part runway surface of the outboard and by a bearing surface in the outer ring formed, this is the track for the balls in the outer ring a unitary structure, with the curvature of the track bigger, especially a bit bigger designed as the ball diameter and / or realized as osculation is. The radially inwardly directed top surface is preferably at least largely concentric Ring surface to the central axis of the angular contact ball bearing formed, which is a guide surface for the Cage forms. The transition between partial runway surface and guiding surface is characterized by a common, circumferential edge or a common, circumferential edge region educated. The preferably one-piece cage realized as an outboard cage.

According to the invention it is proposed that the outer diameter profile of the cage in one of the edge of the outboard opposite start-up area in the axial extent in the direction of the balls is decreasing ausgebil det. The starting area is preferably defined as the area which touches the edge of the outboard when the cage is tilted, and / or which has the smallest distance to this edge. This start-up region thus has an axially outer first diameter and an axially inner lie Second second diameter, wherein the first diameter is formed larger than the second diameter and disposed between the two diameter portions of the starting region. In particular, the starting region is rotationally symmetrical about the central axis of the angular contact ball bearing.

alternative or in addition, the inner diameter curve of the outboard in a neighboring area of the guide surface adjoining the edge increasingly formed in the axial direction in the direction of the balls. Preferably, the starting region and the neighboring region are in the axial direction realized in the direction of the balls diverging from each other.

at The invention has been recognized that in angular contact ball bearings with outboard cages the danger is that the cage at high speeds within the cage guide game and the cage game slightly tilts, leaving the cage on the edge between Guide surface and part track surface starts. Because of the cage in the edge badly lubricated, the cage comes in one Mixed friction area, resulting in increased friction and hence resulting in increased wear and a additional temperature development in the starting area or in the area of the cage guide surface of the Cage has the consequence. To the operating behavior of the angular contact ball bearing Especially at high speeds to improve, the invention proposes to execute the start-up area and / or the neighboring area that the cage does not tilt on the edge when slightly tilted between part track surface and guide surface can run up.

the According to the idea of the invention it is therefore preferred that said Diameter course or the mentioned diameter curves in the start-up area and / or in the neighboring area is designed or are that a particular edged edition of the edge on the starting area is excluded even with a tilting of the cage during operation. In the inventive design of the angular contact ball bearing is preferably the field of tension between cage play, Caged guide play, diameter and diameter course taken into account. So must the slope of the diameter profile or the courses more pronounced in a larger game to be in a smaller game, because of a larger one Play the possible tilt angle of the cage larger can fail.

at a constructive implementation of the invention, it is preferred if the outer diameter profile of the cage, in particular the starting area of the cage and / or the inner diameter course of the outer ring, in particular the neighboring area, respectively is formed concavely curved in the axial direction. Alternatively, the areas mentioned can also be crowned or be realized bevelled.

at Another advantageous alternative is the inner diameter profile of the outer ring, in particular the adjacent area conical tapered, in particular formed with a constant cone angle, wherein it is preferably provided that the cone angle to the maximum Tilting angle of the cage is equal to or greater is trained.

at a preferred embodiment in particular for assembly reasons is the outer diameter curve of the cage in axial extent mittsymmetrisch to the cage center educated. The execution ensures that the cage is installed in the angular contact ball bearing so that it can not be confused is, since this rotated in this embodiment also by 180 ° can be mounted.

at an exemplary embodiment of the invention are the changes the diameter, for example, on an angular contact ball bearing for a shaft with a diameter between 50 and 150 mm, in the range of 0.2 mm to 2 mm, preferably between 0.4 mm and 1 mm and in particular between 0.6 mm and 0.8 mm.

Even though the invention in principle applicable to all cage types is, it is preferable if the cage as a plastic cage or formed as a hard tissue cage. Further is it is preferred if the cage is a cylindrical coarse mold has, so that this inexpensive from a round material by - Example - machining can be produced.

The Invention advantages are particularly evident when the angular contact ball bearings is designed for high speeds, ie speeds greater 15,000 revolutions per minute, preferably larger 30,000 revolutions per minute and in particular greater than 60,000 Revolutions per minute.

at a relative definition of the scope, it is preferable if the angular contact ball bearing has a nominal value in the form of the product of revolution multiplied by the pitch circle diameter of more than 1.5 million mm / min, preferably up to 3.5 million mm / min.

In order to further improve the operating behavior of the angular contact ball bearing, it is optionally additionally proposed that the center of gravity of the cage is offset off-center in the axial direction in the direction of the starting side of the cage. After the cage is outboard, such a displacement of the center of gravity causes the length of the lever arms for imbalances is shortened, so that the tilt tendency of the cage is effectively reduced. The displacement of the center of gravity is preferably realized constructively in that the inner diameter profile of web portions of the cage between the balls in the direction of the start side of the cage is increasingly formed.

Further Features, advantages and effects of the invention will become apparent the following description of preferred embodiments the invention. Showing:

1 a schematic cross section through an angular contact ball bearing according to the prior art;

2 the angular contact ball bearing in 1 in detail at a tilt of the cage;

3 a schematic cross section of another angular contact ball bearing as an embodiment of the invention;

4 a detail of the angular contact ball bearing in 3 ;

5 a schematic cross section of another angular contact ball bearing in detail as a second embodiment of the invention;

6 a schematic cross section of another angular contact ball bearing as a third embodiment of the invention;

7 a schematic cross section of another angular contact ball bearing as a fourth embodiment of the invention.

each other corresponding or identical parts are in the figures each with provide the same reference numerals.

The 1 shows a schematic cross-sectional view of an angular contact ball bearing 1 according to the prior art. The angular contact ball bearing 1 includes an inner ring 2 , an outer ring 3 and a plurality of balls 4 which is in a cage 5 between the inner ring 2 and the outer ring 3 are rotatably mounted. The outer ring 3 has an outboard 6 on which to guide the balls 4 and the cage 5 is trained.

The 2 shows in the same representation, the angular contact ball bearing 1 in the 1 at a tilt of the cage 5 , as it can occur, for example, at high speeds. As can be seen from the detailed illustration, the cage runs 5 against an edge 7 of the outboard 6 at. In the area of the edge start, sufficient lubrication can not be ensured, so that it can not be ruled out that it is in the area of the edge 7 to an increased friction and consequently to a greater wear or to an increase in temperature in the angular contact ball bearing 1 can come.

The 3 shows in the same representation as in 1 another angular contact ball bearing 1 as a first embodiment of the invention. Also this angular contact ball bearing 1 shows an inner ring 2 , an outer ring 3 , Balls 4 and a cage 5 , where the cage 5 through the outboard 6 is guided.

The 4 shows a detail of the angular contact ball bearing 1 in 3 , As can be seen in particular from this figure, the free side of the outboard 6 functionally divided into two subareas: A first subarea is as one to the central axis 8th of angular contact ball bearing 1 concentrically arranged guide surface 9 trained, against which the cage 5 starts radially on the outside. A second subarea is made by a part runway surface 10 formed on which the balls 4 roll in the direction of rotation. start-up range 9 and part runway surface 10 are by the edge 7 separated from each other.

The cage 5 has side rings 11 on which over bridges 12 are integrally connected to each other and is formed, for example, as a hard tissue cage. Radially outside is the cage 5 designed so that this through the guide surface 9 of the outboard 6 is feasible. In a start-up area 13 which is opposite to the edge 7 is arranged, and to the the edge 7 could potentially start at a tilt (as in eg 2 shown) shows the outer diameter of the cage 5 in the axial direction in the direction of the balls 4 a decreasing or decreasing course. This decreasing or decreasing profile ensures that even with a tilting of the cage 5 the edge 7 not edged at the starting area 13 runs, but the cage 5 in the start-up area 13 through the guide surface 9 the outer ring is guided flat.

As can be seen from the presentation in the 3 gives, is the outer diameter of the cage 5 symmetrical to a plane perpendicular to the central axis 8th of angular contact ball bearing 1 aligned and in the center of the angular contact ball bearing 1 is arranged, formed. The course of the outer diameter may optionally be convex, curved, in particular with a fixed radius of curvature or also be formed as straight bevels. As a result, the startup area 13 for example, frusto-conical and / or concave, but with the outer diameter of a first outer diameter at the beginning of the starting region 13 to a second outer diameter at the axially inner end of the starting area 13 reduced. The changes tion of the outer diameter is between 0.1 mm to 2 mm depending on the cage and / or ball clearance and the size of the angular contact ball bearing 1 ,

The 5 shows a detail of an angular contact ball bearing 1 as a second embodiment of the invention. In this embodiment, the start-up area 13 formed without bending and / or as a concentric annular surface to the central axis 8th realized, whereas a neighboring area 14 which directly adjoins the edge 7 adjoins and part of the guide surface 9 forms formed with an inner diameter profile, which is increasingly formed in the axial direction in the direction of the angular contact ball bearing inside. In the 5 the neighboring area shows a curved course with a curvature R _K , alternatively the neighboring area 14 depending but also beveled or formed with a different curvature. The thus curved neighboring area 14 provides in a similar way as the start-up area 13 making sure that the edge is prevented 7 edged on the radial outside of the cage 5 runs.

In further embodiments of the invention, both measures, ie the adapted neighboring area 14 and the customized startup area 9 be realized.

The 6 shows in a schematic cross-sectional view of another embodiment of an angular contact ball bearing 1 which is analogous to the 3 and 4 a curved start-up area 13 having. In contrast to the embodiment in the 3 and 4 shows the embodiment in the 6 that the free inner diameter of the cage 5 is formed from the start-side opposite side decreasing in the direction of the start-up side. Through the shown inner diameter curve is achieved that the center of mass of the cage 5 along the central axis 8th is moved in the direction of the starting area, so that the tilting tendency of the cage 5 is reduced. This embodiment is based on the consideration that the center of gravity is pushed closer to the guide surfaces, so that the length of the lever arm of the center of gravity is effectively reduced.

The 7 shows in a schematic cross-sectional view of a fourth embodiment of the invention, which substantially with the embodiment in the 5 in contrast to the representation in the 5 the angular contact ball bearing 1 in the neighboring area 14 has a cone-shaped course with a constant over the course cone angle alpha. It is preferably provided that the cone angle alpha equal to or greater than the maximum tilt angle of the cage 5 is pronounced relative to a radial plane formed perpendicular to the bearing axis.

1

Angular contact ball bearings

2

inner ring

3

outer ring

4

Bullet

5

Cage

6

outboard

7

edge

8th

central axis

9

Guide surface start-up range

10

Part raceway surface

11

side ring

12

web

13

start-up range

14

adjacent area

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 2108562 C2 [0003]
• - DE 3307845 [0003]

Claims (10)

Angular contact ball bearings ( 1 ), in particular spindle bearings, for a machine tool with an outer ring ( 3 ), an inner ring ( 2 ), a plurality of balls ( 4 ) and a cage ( 5 ), whereby the balls ( 4 ) in the cage ( 5 ) between the outer ring ( 3 ) and the inner ring ( 2 ) are rotatably mounted, wherein the outer ring ( 3 ) an outboard ( 6 ), of which the balls ( 4 ) facing side surface a part of the raceway surface ( 10 ) for the balls and its radially inwardly directed top surface a guide surface ( 9 ) for the cage ( 5 ) forms, so that the cage ( 5 ) is guided outboard at least on one side, and wherein the partial raceway surface ( 10 ) and the guiding surface ( 9 ) a common peripheral edge ( 7 ) or edge region, characterized in that the outer diameter profile of the cage ( 5 ) in one of the edges ( 7 ) of the outboard ( 6 ) opposite starting area ( 13 ) in the axial direction in the direction of the balls ( 4 ) is designed to decrease, and / or that the inner diameter curve of the outboard ( 6 ) in one to the edge ( 7 ) adjacent neighboring area ( 14 ) of the guide surface ( 9 ) in the axial direction in the direction of the balls ( 4 ) is increasingly formed. Angular contact ball bearings ( 1 ) according to claim 1, characterized in that said diameter profile in the starting area ( 13 ) and / or in the neighboring area ( 14 ) is formed so that an edged edition of the edge ( 7 ) on the start-up area ( 14 ) even with a tilting of the cage ( 5 ) is excluded during operation. Angular contact ball bearings ( 1 ) according to claim 1 or 2, characterized in that the outer diameter profile of the cage ( 5 ), in particular the start-up area ( 13 ) of the cage ( 5 ) and / or the inner diameter profile of the neighboring area ( 14 ) is concavely curved in each case in the axial direction. Angular contact ball bearings ( 1 ) according to claim 1 or 2, characterized in that the outer diameter profile of the cage ( 5 ), in particular the start-up area ( 13 ) of the cage ( 5 ) is formed tapering in the axial direction in the direction of the balls, wherein the cone angle preferably the maximum tilt angle of the cage ( 5 ) corresponds. Angular contact ball bearings ( 1 ) according to one of the preceding claims, characterized in that the outer diameter profile of the cage ( 5 ) is formed in the axial extent mittsymmetrisch. Angular contact ball bearings ( 1 ) according to any one of the preceding claims, characterized in that the outer diameter curve and / or the inner diameter curve over the entire starting region shows a change in diameter between 0.2 mm and 2 mm, preferably between 0.4 mm and 1 mm. Angular contact ball bearings ( 1 ) according to one of the preceding claims, characterized in that the cage is designed as a plastic cage or hard tissue cage. Angular contact ball bearings ( 1 ) according to one of the preceding claims, characterized by a design with a nominal number in the form of the product n · dm (rotational speed in revolution per minute multiplied by the pitch circle diameter in mm) of more than 1.5 million mm / min. Angular contact ball bearings ( 1 ) according to one of the preceding claims, characterized in that the center of gravity of the cage in the axial extension off-center in the direction of the start-up side of the cage ( 5 ) is offset. Angular contact ball bearings ( 1 ) according to one of the preceding claims, characterized in that the inner diameter profile of web portions of the cage ( 5 ) between the balls ( 4 ) in the direction of the start side of the cage ( 5 ) is increasingly formed.