DE102021207953A1 - bearing arrangement - Google Patents

Abstract

Bearing arrangement comprising an outer (2) and an inner connection structure (3), and a roller bearing (4) with an inner ring (5), an outer ring (6) rotatably mounted relative to the inner ring (5) and at least one row of (5) and the outer ring (6) arranged to be able to roll on raceways (8), the inner ring (5) having an inner peripheral surface (9) and/or the outer ring (6) having an outer peripheral surface (10), in Area in which there is a press fit (11) with the associated connecting structure (3, 4) over a press fit width (BP) and with an oversize (M), with at least one peripheral groove (12, 13) with a groove depth that exceeds the oversize of the press fit (11) and a groove width (B1) in the range of 1% to 10% of the width (BP) of the press fit (11) is introduced.

Description

State of the art

The invention relates to a bearing arrangement according to the preamble of claim 1.

In the rotatable mounting of components relative to each other, roller bearings are used, which have at least one row of roller bodies to reduce friction. During operation, the rolling elements roll on raceways between an inner ring and an outer ring. The bearing rings are attached to so-called adjacent structures of the components. The connecting structures can be the components themselves, or they can be formed, for example, by flange-like end sections of the components, to which the bearing rings can be fastened, for example by screwing. If the component to be stored already has the appropriate dimensions, the connection structure can be formed by a section of the component itself, for example by a section of a shaft or hollow shaft, or can completely enclose it.

In bearing arrangements with rather small bearings, for example with a diameter of up to 30 cm, it is common that the inner ring can be fixed directly onto a shaft by means of an interference fit. In this case, a section of the shaft forms the internal connection structure for the rolling bearing. With such a press fit, the mechanical circumferential stresses introduced into the roller bearing ring due to the oversize fit cause contact pressure on the mating surface, which increases the friction between the roller bearing ring and the adjacent structure to such an extent that the longitudinal and transverse forces occurring during operation can be transmitted in the frictional contact of the mating surface. One speaks of a non-positive shaft-hub connection.

DE 10 2016 121 765 A1 describes a ball bearing for supporting a motor shaft. At this time, the inner ring of the rolling bearing and the rotating shaft are joined in a state of press fitting. Contrary to the inner ring, the outer ring is assembled on a housing inner peripheral surface in a loose fit state. Thus, when in use, creeping can occur between the outer ring and the housing. In order to suppress creeping, the rolling bearing has an annular groove formed in the mating surface of the outer ring and radially outside the raceway groove of the outer ring. The annular groove has a width that is larger than the width of the raceway groove of the outer ring. The migration of the outer ring is prevented in that an elastic deformation of the outer ring when rolled over by a highly loaded rolling body in the raceway depression remains essentially limited to the area of the annular depression. As a result, the deformation is not transmitted to the interface between the outer ring and the housing, which is why there is less relative displacement of the components. In addition, the groove reduces the contact surface between the outer ring and the housing, which results in a proportionally increased contact pressure with the same bearing load, which also contributes to reducing the relative displacement. The disadvantage is that DE 10 2016 121 765 A1 does not contain any advice on how to prevent creep in the press-fit condition of the inner ring.

Disclosure of Invention

The object of the invention is therefore to specify a roller bearing arrangement in which ring creep of a bearing ring fastened to the associated adjacent structure by means of a press fit is reduced during operation.

This object is achieved by a bearing arrangement having the features of claim 1.

This creates a bearing arrangement that includes an outer and an inner connecting structure, as well as a roller bearing with an inner ring, an outer ring that is rotatably mounted relative to the inner ring, and at least one row of rolling elements arranged to roll on raceways between the inner and outer rings. The inner ring has an inner peripheral surface and/or the outer ring has an outer peripheral surface, in the region of which there is a press fit with the respective associated connecting structure over a press fit width and with a predeterminable oversize. According to the invention, at least one circumferential groove is introduced into the peripheral surface in the area of the press fit with a groove depth that exceeds the oversize of the press fit, and the groove has a groove width in the range of 1% to 10% of the width of the press fit.

According to the invention, narrow circumferential grooves with a groove width of 1% to 10% of the width of the press fit are therefore provided in order to reduce ring creep in the press fit.

The invention thus turns away from the comparatively wide circumferential grooves known from the prior art, which are intended to cover the entire area of elastic deformation of the bearing ring in the axial direction and rely on increasing the contact pressure by reducing the fitting surface. That is the knowledge This is based on the fact that when mounting bearing rings by means of press fits, the resistance to migration that can be achieved with regard to critical bearing loads is limited by the maximum circumferential stresses (yield point) of the ring material and the effective ring cross-section that can be used to provide the circumferential stresses and thus the contact pressure in the fitting surface. Increasing the width of the groove leads to a reduction in the mating surface, but also to a reduction in the ring cross-section that can be used to build up the hoop stresses, since the hoop stresses are primarily generated in the area of the interference fit joint. For this reason, circumferential grooves can tend to weaken the interference fit from a certain width.

By contrast, the narrower grooves according to the invention make use of what is known as the edge carrier effect in the fitting joint in order to reduce ring creep without a significant reduction in the fitting surface occurring. While a reduction in the mating surface can have an ambivalent effect on the strength of the interference fit, the use of the edge beam effect according to the invention leads to a strong, non-linear, local increase in the joint pressure, which reduces the tendency to ring creep.

In order to make the effect of the grooves according to the invention understandable, both the physical basics of both the ring migration and the edge carrier effect are explained below.

When the ring creeps, there is a local, radial lowering or even elimination of the contact pressure as a result of the ring being rolled over by highly loaded rolling elements. In this case, the highly loaded rolling elements cause the bearing ring to bulge, which - similar to a carpet fold - is pushed forward by the movement of the rolling element. The ring material is thus shifted in the rollover direction by elastic deformation and is placed a little further ahead on the adjacent structure. This results in a relative movement between the bearing ring and the adjacent construction without the surfaces slipping or sliding. However, if this effect is repeated over many revolutions, damage patterns such as fretting corrosion can result. It is also conceivable that a pumping effect is triggered for the surrounding lubricant, which can lead to an undesired, large-area or even full-area loss of friction in the interference fit.

The edge beam effect describes the asymptotic increase in surface pressure at the edge of a contact surface between two contact partners, which is generally undesirable in mechanical engineering. The reason for the increase in contact pressure is the sudden loss of the contact surface with a locally essentially constant elastic restoring force along the contact joint. Measures are therefore regularly taken in mechanical engineering to reduce wear in the edge areas in order to reduce excessive pressure. For example, the rollers of a roller bearing can be designed with a convex profile in the edge area for this purpose.

In the solution according to the invention, the increase in the surface pressure occurring at the edge of the groove due to the edge carrier effect is exploited in a targeted manner in order to reduce ring creep. This is based on the knowledge that migration of the bearing ring in the interference fit can only occur if the contact pressure is removed locally over the entire axial width of the ring, i.e. a continuous path with local slip across the width of the bearing ring due to the buckling of the bearing ring is produced. The increased surface pressure in the area of the groove edges due to the edge carrier effect thus forms a protective barrier against local slippage, which reduces the tendency to ring creep.

In preferred embodiments, the roller bearing is a large roller bearing with an inside diameter of at least 800 mm. Since the fitting surface increases both in the circumferential direction and in the width direction of the bearing with increasing bearing ring diameter, but the ring cross-sectional area of the bearing rings typically only increases in proportion to the bearing ring diameter and the yield point as a material property remains the same, the achievable contact pressure and thus that of the press fit decreases locally transmittable forces with increasing bearing ring diameter. For this reason, the solution according to the invention can be used particularly advantageously in the area of large roller bearings, since the failure mechanism of so-called ring creep can occur more quickly here in the interference fit. In the case of small bearings, such as those used in the automotive industry, on the other hand, the contact pressure provided by the press fit is usually sufficient to prevent ring creep due to the smaller bearing diameter with the intended forces to be absorbed.

Preferably, at least two grooves are located within the press-fit width. Particularly in the case of multi-row bearings with correspondingly wide bearing rings, it is advantageous to interrupt the mating surface in the bearing ring with at least two grooves in order to reliably avoid continuous paths with local slip.

Provision can also preferably be made for the grooves taken together to have a total width of at most 20% of the width of the press fit. This ensures that a sufficiently large effective ring cross-section is available for the build-up of hoop stresses.

It is also advantageous if at least two of the grooves are provided in the area of the raceway of one of the rows of rolling bodies. Especially with wide rolling elements, such as rollers, at least two grooves in the area of the raceway can lead to a further reduction in the tendency to migrate.

Provision can preferably be made for the grooves to be formed with an edge angle in the range from 80° to 100° when viewed in cross section. Such an edge angle ensures on the one hand a stable support of the edge area by the ring material and on the other hand a sudden omission of the contact surface at the edge of the groove is realized. Both result in a further increase in the edge carrier effect desired according to the invention. In particular, it can be advantageous if the groove edges are designed with sharp edges. Sharp-edged groove edges can be formed by reducing a chamfer provided on the groove edge for manufacturing and/or assembly reasons.

The invention is preferably used in connection with roller bearings which are designed as roller bearings, for example as radial roller bearings, (double) tapered roller bearings or multi-row roller bearings. The groove is preferably arranged in the power flow of a row of rollers of the roller bearing.

The grooves preferably have a groove depth of at least 1 mm, particularly preferably at least 1.5 mm and particularly preferably at least 2 mm.

Further advantageous embodiments can be found in the following description and the dependent claims.

The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the attached figures.

character list

• 1 schematically shows a sectional view of a first embodiment of the invention with two circumferential grooves in the peripheral surface of the bearing ring,
• 2A until 2 C show schematic surface pressures in the press fit between a bearing ring and an associated adjacent construction depending on the formation of the fitting surface on the bearing ring; 2C corresponds to an inventive design of the bearing ring,
• 3A shows schematically a bearing ring with three circumferential grooves in a press fit with an inner connection construction according to a second embodiment of the invention,
• 3B shows a detailed representation of the bearing ring and the adjacent construction according to FIG 3A before assembly,
• 4A shows schematically a bearing ring with an alternative groove geometry in a press fit with an inner connection construction according to a third embodiment of the invention,
• 4B shows a detailed representation of section X of FIG 4A , and
• 5 shows schematically how the surface pressure that can be achieved in a press fit depends on the diameter of the bearing ring.

Embodiments of the invention

In the various figures, the same parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

In 1 a first exemplary embodiment of the bearing arrangement 1 according to the invention is shown. The bearing arrangement 1 comprises an outer connecting structure 2 and an inner connecting structure 3, as well as a roller bearing 4 with an inner ring 5, an outer ring 6 which is mounted such that it can rotate relative to the inner ring 5 and at least one row of roller bearings arranged between the inner ring 5 and the outer ring 6 on raceways 8 so that they can roll Rolling bodies 7. The inner ring 5 has an inner peripheral surface 9 and the outer ring 6 has an outer peripheral surface 10. In the area of the inside circumferential surface 9 of the inner ring 5 there is a press fit 11 with the inner connecting structure 3 assigned to the inner ring 3 over a press fit width BP and with an oversize M. Within the press fit width BP there is at least one circumferential groove in the circumferential surface 9, here two circumferential grooves 12, 13, with a groove depth T that exceeds the oversize M of the press fit 11 (cf. 3B) brought in. The grooves have a groove width B1 of about 10% of the press fit width BP. The illustrated groove width B1 is thus at the upper end of the range from 1% to 10% of the press-fit width BP.

Taken together, the two grooves 12, 13 thus have a total width of approximately 20% of the press-fit width BP.

The grooves 12, 13 can be formed continuously over the entire circumference of the peripheral surface 9, 10. However, embodiments are also conceivable in which the circumferential grooves are interrupted at one or more points over the circumference of the circumferential surfaces. In particular, it is conceivable that interruptions in the circumferential grooves are arranged in such a way that at least one groove is contained in each cross section of the bearing ring.

As in 1 the two grooves 12, 13 are shown in the region of the raceway 8 of the row of rolling elements 7. The grooves 12, 13 are thus preferably located in the force flow of the loads introduced by the rolling bodies 7 into the bearing ring 5 and to be transmitted to the adjacent structure 3. The inner connecting structure 3 can, for example, as in 1 shown, be a hollow shaft 15, the press fit with the hollow shaft 15 in the region of the inside peripheral surface 9 of the inner ring 5.

The grooves 12, 13 are preferably formed with a groove depth of at least 1 mm, particularly preferably at least 1.5 mm.

Unlike in the in 1 In the illustrated embodiment, it is in principle also conceivable for the outer ring 6 to be accommodated in the outer connection structure 2 by means of a press fit and to have at least one circumferential groove with the dimensions according to the invention on its outside peripheral surface 10 .

In 2A until 2C the edge beam effect is shown schematically using different geometries of a bearing ring 5 in contact with a connecting structure 3 . The surface pressures P occurring across the width of the bearing ring 5 are shown in the form of a bar chart. In the 2A and 2 B comparative examples are shown.

2A shows a bearing ring with rounded outer edges. As a result, the contact with the adjacent construction is gradually eliminated and there is only a slight increase P1 in the surface pressure at the edges of the contact surface. Such a pressure distribution is usually preferred in mechanical engineering because it reduces material stress and wear in most applications.

For comparison shows 2 B a bearing ring 5 with sharp outer edges. Due to the sudden loss of contact pressure on the outer edges and the rigidity of the protruding material of the connecting structure 3, significantly excessive surface pressures P2 occur in the area of the outer edges, which drop towards the center of the bearing ring 5 to a base level P0.

2C shows the effect of the groove according to the invention within the press fit width of the peripheral surface of the bearing ring 5. The groove edges can generate further increases P3 of the surface pressures within the press fit without the contact surface between the bearing ring 5 and the adjacent structure 3 having to be significantly reduced. The additional surface pressures P3 reduce the probability that there will be a continuous path of local slip over the entire width of the bearing ring 3.

In 3A 1 shows a second exemplary embodiment of the invention, in which the bearing ring 5, which is fastened to the connecting structure 3 with a press fit, has three circumferential grooves 12, 13, 14 within the width of the press fit BP. The grooves 12, 13, 14 have a width B1 and a groove depth T. The grooves 12, 13, 14 are preferably arranged within the width PL of the track 8. As shown, the bearing ring is preferably the inner ring 5 of the roller bearing 4, which is attached to the inner connecting structure 3. 3B shows the bearing arrangement 3B before assembling the press fit. The press fit has an oversize M, which corresponds to the difference in the radii of the adjacent structure 3 and the bearing ring 5. The groove depth T of the grooves 12, 13, 14 exceeds the oversize M of the press fit.

Otherwise, the above statements on the exemplary embodiment apply 1 for the second embodiment 3A and 3B corresponding.

4A shows a third exemplary embodiment of the bearing arrangement according to the invention with two circumferential grooves 12, 13 on the bearing ring 5. In contrast to the previous exemplary embodiments, the grooves 12, 13 are not designed in the form of a segment of a circle in cross section, but are box-shaped with a flattened groove base and steep groove flanks. The box-shaped groove geometry allows grooves 12, 13 to be formed with a larger groove width B2, which nevertheless have sharp groove edges for a given groove depth T.

In 4B is the detail section X of 4A shown enlarged to show the edge angle α1, α2 of the groove 12. Regardless of the rest of the groove geometry, the grooves 12, 13, 14 in the illustrated embodiments have a preferred edge angles α1, α2 in the range from 80° to 100°. Such an edge angle produces an abrupt transition from the contact surface of the press fit to the groove while at the same time the groove edge is stably supported, as a result of which the edge support effect is particularly strong. The edge of the groove is preferably formed with a sharp-edged chamfer that is as small as possible and limited by manufacturing restrictions.

Otherwise, the above statements on the exemplary embodiments apply 1 , 3A and 3B for the embodiment according to 4A and 4B corresponding.

5 Finally, FIG. 1 ). The representation is based on the assumption of a constant nominal stress of the bearing ring in the circumferential direction and a geometric similarity of proportions of the bearings with a linear relationship between the diameter D and the cross-sectional area of the bearing ring, as is usually empirically determined in the prior art. As in 5 shown, the contact pressure that can be achieved in a press fit under these conditions drops by a factor of about 10 from a bearing with a diameter of 30 mm to a bearing with a diameter of approx. 750 mm. For smaller roller bearings, the contact pressure in a press fit can therefore generally be selected so high that ring creep does not occur, or only to a tolerable extent, even without circumferential grooves.

The invention is therefore preferably used in large roller bearings with an inside diameter D of at least 800 mm. With such large bearings, the weakened local frictional connection between the bearing ring 5, 6 and the connecting structure 3, 2 due to the comparatively low contact pressure that can be achieved can be strengthened particularly effectively with the aid of the circumferential groove 12, 13, 14 according to the invention.

The invention is preferably used in bearing arrangements in which the press fit 11 has an average contact pressure P in the range from 1 MPa to 10 MPa in the unloaded state of the roller bearing 4 . In the case of press fits with contact pressures in this range, it has been found that the tendency to ring creep can be reduced particularly effectively by utilizing the edge carrier effect according to the invention.

Reference List

1

bearing arrangement

2

external connection construction

3

inner connection construction

4

slewing bearing

5

inner ring

6

outer ring

7

rolling elements

8th

career

9

inside peripheral surface

10

outside peripheral surface

11

interference fit

12, 13, 14

groove

15

hollow shaft

A

axis of the bearing

B1, B2

groove width

bp

press fit width

BL

width of the track

D

Inner diameter of the rolling bearing

M

interference fit

P, P0 to P3

contact pressure of the press fit

T

groove depth

X

detail cutout

α1, α1

edge angle of the groove

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 102016121765 A1 [0004]

Claims (9)

Bearing arrangement comprising an outer (2) and an inner connection structure (3), and a roller bearing (4) with an inner ring (5), an outer ring (6) rotatably mounted relative to the inner ring (5) and at least one row of (5) and the outer ring (6) arranged to be able to roll on raceways (8), the inner ring (5) having an inner peripheral surface (9) and/or the outer ring (6) having an outer peripheral surface (10), in Area in which there is a press fit (11) with the associated connecting structure (3, 4) over a press fit width (BP) and with an oversize (M), characterized in that within the press fit width (BP) in the peripheral surface (9; 10) at least one circumferential groove (12, 13, 14) with a groove depth (T) that exceeds the oversize (M) of the press fit (11) and a groove width (B1, B2) in the range of 1% to 10% of the press fit width ( BP) is introduced. bearing arrangement claim 1 , characterized in that the roller bearing (4) is a large roller bearing with an inner diameter (D) of at least 800 mm. bearing arrangement claim 1 or 2 , characterized in that at least two grooves (12, 13, 14) are arranged within the press-fit width (BP). bearing arrangement claim 3 , characterized in that the grooves (12, 13, 14) together have a total width of at most 20% of the press-fit width (BP). Bearing arrangement according to one of claims 3 or 4 , characterized in that at least two grooves (12, 13, 14) are provided in the region of the raceway (8) of one of the rows of rolling elements (7). Bearing arrangement according to one of Claims 1 until 5 , characterized in that the grooves (12, 13, 14) viewed in cross section are formed with an edge angle (α1, α2) in the range of 80° to 100°. Bearing arrangement according to one of Claims 1 until 6 , characterized in that the inner connecting structure (3) is a hollow shaft (15) and the press fit with the hollow shaft (15) is in the region of the inside peripheral surface (9) of the inner ring (5). Bearing arrangement according to one of Claims 1 until 7 , characterized in that the roller bearing (4) is a roller bearing. Bearing arrangement according to one of Claims 1 until 8th , characterized in that the grooves (12, 13, 14) are formed with a groove depth (T) of at least 1 mm, preferably at least 1.5 mm.

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