WO2015176768A1

WO2015176768A1 - Method for producing a bearing race for a rolling bearing

Info

Publication number: WO2015176768A1
Application number: PCT/EP2014/060639
Authority: WO
Inventors: Junbiao Lai; Otto Menig; Armin Olschewski; Arno Stubenrauch; Alexander De Vries
Original assignee: Aktiebolaget Skf
Priority date: 2014-05-23
Filing date: 2014-05-23
Publication date: 2015-11-26

Abstract

The invention relates to a method for producing a bearing race (1) for a rolling bearing, wherein at a radially outer or inner circumferential surface, an annular body has at least one raceway (2) for rolling bodies. At a radially inner or outer circumferential surface, the annular body has a cylindrical seat (3), wherein the cylindrical seat (3) is subjected to metal-cutting hard machining. In order to counteract the susceptibility of the bearing race to crack formation, the last machining step for the cylindrical seat (3) according to the invention is done by way of a honing operation, wherein the bearing race (1) is provided to be arranged with its cylindrical seat (3) on or in a component. The honing of the cylindrical seat (3) is carried out such that the radial difference (h_c) between the maximum and minimum values over the circumference of the cylindrical seat (3) is specified according to a mathematical relationship.

Description

The invention relates to a method for producing a bearing ring of a roller bearing, wherein an annular body is provided on a radially outer or inner circumferential surface with at least one raceway for rolling elements and wherein the annular body at a radially inner or outer peripheral surface with a cylindrical seat surface is provided, wherein the cylindrical seat surface is subjected to a machining hard machining.

Bearing rings of this type are arranged on or in a component. For example, a bearing inner ring can be arranged by means of a press fit on a shaft in order to fix it permanently during its service life on this component.

With appropriate load during the use of a rolling bearing, there are sometimes problems with crack formation in the raceway area. In this connection, it is known that cracks are formed on the raceway at high loads and in conjunction with slip occurring on the raceway surface in the axial direction. As a result, fretting corrosion on the bearing bore and on the supported shaft is very common. In addition, a circulation bend is relevant, which acts during the rotation of the bearing ring.

The effects mentioned limit the service life of the rolling bearing and sometimes lead to premature failure of storage. The invention has for its object to provide a generic method for producing a bearing ring, with which the tendency for cracking is at least greatly reduced. Also, the occurrence of fretting corrosion in the region of the cylindrical seat of the bearing is to be reduced by shaft deflection under load.

The solution to this problem by the invention is characterized in that the last processing step of the cylindrical seat surface is formed by a honing operation, wherein the bearing ring is provided to be arranged with its cylindrical seat, preferably with a press fit, on or in a component wherein the honing of the cylindrical seating surface is performed such that the radial difference between the maximum and minimum values above the circumference of the cylindrical seating surface is at most equal to the following value:

with: h _c : radial difference between maximum and minimum

Value of the radius over the circumference of the cylindrical seat m mm;

D: diameter of the cylindrical seat of the bearing ring in mm;

E: modulus of elasticity of the bearing ring material in N / mm ² ;

critical hoop stress in the bearing ring before application of an external load, possibly after the production of an interference fit, in N / mm ² (MPa);

nominal hoop stress in the bearing ring after its

Mounting, possibly caused by a press fit, m N / mm ² (MPa).

The critical hoop stress in the bearing ring before the application of an external load is preferably based on a value between 180 MPa and 220 MPa, preferably of 200 MPa. Preferably, a hard turning operation is performed before the honing operation to produce the cylindrical seating surface.

It may also be provided that a grinding operation is performed before the honing operation in order to produce the cylindrical seating surface.

It has surprisingly been found that a particularly good result is achieved when said honing operation - in particular with subsequent installation of the bearing ring by means of press fit - carried out to such an extent until said maximum radial difference between maximum and minimum value over the scope of cylindrical seat is present.

The raceway of the bearing ring is preferably hard-turned; it can also be hard-rolled.

The track and / or the cylindrical seat are preferably burnished.

The proposed method has proven particularly in bearing inner rings. However, bearing outer rings can also be produced in the same way. Particularly preferred bearing rings of tapered roller bearings and cylindrical roller bearings are produced according to the invention.

It has been found that the tendency to crack on the raceway of the bearing ring can be significantly reduced when the proposed method is used. Also, fretting corrosion can be reduced.

In the drawing, an embodiment of the invention is shown. Show it:

1 in radial section the bearing inner ring of a tapered roller bearing,

Fig. 2 for the cylindrical seat of the bearing inner ring of FIG. 1, the course of the radius of the seat over the circumference and

3 shows the maximum allowable radial difference between the maximum and minimum values of the radius according to the invention over the circumference of the cylindrical see seat surface as a function of the diameter of the cylindrical seat for different nominal hoop stresses in the bearing ring.

In Fig. 1, the radial section of a tapered roller bearing inner ring 1 is shown. The ring has in a known manner a conical raceway 2 and a cylindrical seat surface 3. It is not shown that the bearing ring 1 is arranged in the installed state with its cylindrical Sitzfiäche 3 with a press fit on a shaft. The interference fit will find application in many cases; but it is not mandatory for the present invention. If the bearing ring 1 is arranged on the shaft with a press fit, the bearing ring has a nominal hoop stress < _nom (in this case given in MPa, 1 Pa = 1 N / m ² ), which is caused by the interference fit. In Fig. 2, this voltage is illustrated.

Nominal hoop stress ⁽ nom is usually zero, but it can also be greater than zero, for example, in the case of a tapered roller bearing outer ring due to an axial load and thereby causing expansion of the ring caused a hoop stress in the ring becomes.

Furthermore, a critical hoop stress o _c (in MPa) can be defmierbar that may prevail in the bearing ring after manufacture, but before the application of an external load. This value is material-dependent and may be 200 MPa for steel, for example.

In Fig. 2 shows how the cylindrical bore with its nominal diameter D (in mm) changed in radius over the circumference of the bearing ring 1, of course, the course of the bore is shown greatly exaggerated. It turns out that due to the irregularity or waviness there is a radial difference between the maximum and the minimum value of the radius; this difference is denoted by h _c .

In the present case, the cylindrical bore 3 is first brought into its final shape by grinding; however, another mechanical machining operation follows the hole by honing. The raceway can be made classic, ie that the final contour is made by grinding. However, hard twisting and / or hard rolling is also possible here, possibly followed by honing.

A very advantageous result and a substantial improvement against cracks in the raceway are achieved if the radial difference hc does not exceed the following value:

As the course of hc looks, for various values the nominal hoop stress < _{nom is shown} over the diameter D and for steel as hoop material (E = 210,000 N / mm ² ) in FIG. Here is a critical hoop stress o _c of 200 MPa. The value hc represents the critical value of the unevenness of the bore. The formula given gives the value for h _c in mm, although the diameter D in mm is used.

It can be seen that, the closer the nominal voltage value approaches the critical voltage value, the smaller the degree of h _c, depending on the diameter D, in order to ensure a permanent avoidance of cracks on the track 2.

Accordingly, in the implementation of the idea according to the invention, the procedure is such that, based on the intended design and the planned use of the rolling bearing, it is first determined with which _{hoop stress} σ _ηοπι, for example, the bearing _{inner ring} will sit on its shaft. This results in particular from the intended fit between the cylindrical seat of the bearing ring and the shaft. For this purpose, appropriate computer programs can be used with which the nominal hoop stress in the bearing ring can be determined, which results from the intended interference fit. Then the critical hoop stress < _{c is determined} in the bearing ring, as it is present after the production of the press fit and before the application of an external load in the bearing ring. This value is material-dependent; an example of said voltage has been given above.

It can then be determined from the above-mentioned mathematical relationship how large the radial difference hc may be.

After grinding the cylindrical bore finally the honing process. The honing is carried out in such a way that the determined maximum radial difference amount is maintained, which is optionally checked by interactive measurement.

LIST OF REFERENCE NUMBERS

1 bearing ring

2 career

3 cylindrical seat

h _c radial difference between maximum and minimum

Value of the radius over the circumference of the cylindrical seat D Diameter of the cylindrical seat

E modulus of elasticity of the material of the bearing ring

o _c critical hoop stress in the bearing ring before the application of an external load and possibly after the production of a press fit

<5 _nom nominal hoop stress in the bearing ring, possibly caused by a press fit

Claims

P a n t a n s p r e c h e

Method for producing a bearing ring of a roller bearing

1. A method for producing a bearing ring (1) of a roller bearing, wherein an annular body is provided on a radially outer or inner Umfangsfiäche with at least one raceway (2) for rolling elements and wherein the annular body on a radially inner or outer Umfangsfiäche with a cylindrical seat ( 3), wherein the cylindrical seat surface (3) is subjected to a machining hard machining, characterized in that the last machining step of the cylindrical seat surface (3) is constituted by a honing operation, the bearing ring (1) being provided with its cylindrical part Seat (3), preferably with a press fit, to be arranged on one or in a component, wherein the honing of the cylindrical seat surface (3) is performed such that the radial difference amount (h _c ) between maximum and minimum value over the circumference of the cylindrical Seat (3) at most equal to the following W is:

With: h _c : radial difference between maximum and minimum

Value of the radius over the circumference of the cylindrical seat

(3) in mm;

D: diameter of the cylindrical seat of the bearing ring (1)

m mm;

E: modulus of elasticity of the material of the bearing ring (1) in N / mm ²

(MPa);

critical hoop stress in the bearing ring (1) before application of an external load, if necessary after the production of an interference fit, in N / mm ² (MPa);

σ _ηοπι : nominal _{hoop stress} in the bearing ring (1) after its

Assembly, possibly caused by a press fit,

m N / mm ² (MPa).

A method according to claim 1, characterized in that as a critical hoop stress (o _c ) in the bearing ring (1) prior to the application of an external load, a value between 180 MPa and 220 MPa is based, preferably of 200 MPa.

A method according to claim 1 or 2, characterized in that before the honing operation, a hard turning operation is performed to produce the cylindrical seat surface (3).

A method according to claim 1 or 2, characterized in that before the honing operation, a grinding operation is carried out to produce the cylindrical seat surface (3).

Method according to one of claims 1 to 4, characterized in that the raceway (2) is hard turned.

6. The method according to any one of claims 1 to 5, characterized in that the raceway (2) is hard-rolled.

7. The method according to any one of claims 1 to 6, characterized in that the raceway (2) and / or the cylindrical seat surface (3) are burnished.

8. The method according to any one of claims 1 to 7, characterized in that a bearing inner ring is produced with it.

9. The method according to any one of claims 1 to 7, characterized in that a bearing outer ring is produced with it.

10. The method according to any one of claims 1 to 9, characterized in that it produces a tapered roller bearing bearing ring or a cylindrical roller bearing bearing ring.