WO2018233745A1

WO2018233745A1 - Method for producing a bearing ring by means of an additive manufacturing method and rolling element bearing having a bearing ring

Info

Publication number: WO2018233745A1
Application number: PCT/DE2018/100354
Authority: WO
Inventors: Carsten Merklein; Michael Pausch; Sven Claus
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2017-06-21
Filing date: 2018-04-13
Publication date: 2018-12-27
Also published as: DE102017113703A1

Abstract

The invention relates to a method for producing a bearing ring (2, 3) for a rolling element bearing (1). The invention further relates to a rolling element bearing (1) having two bearing rings (2, 3), namely an inner ring (2) and an outer ring (3), which are made from a ring material, wherein respective raceways (4, 5) for guiding rolling elements (6) are comprised by the inner ring (2) on an outer circumferential surface and by the outer ring (3) on an inner circumferential surface, wherein the rolling elements (6) roll on the raceways (4, 5), wherein the ring material comprises at least 1.29 to 2 wt% carbon, 0.5 to 0.6 wt% silicon, 0.2 to 0.4 wt% manganese, 3.8 to 4.8 wt% chromium, 2 to 5 wt% molybdenum, 3 to 5.1 wt% vanadium, 5 to 14.3 wt% tungsten and 0 to 11 wt% cobalt or alternatively 0.5 to 2 wt% carbon, at most 0.035 wt% sulfur, 3 to 5 wt% chromium, 1 to 4 wt% vanadium, 1 to 12 wt% tungsten and 2 to 12 wt% molybdenum, wherein at least one of the two bearing rings (2, 3) is produced at least by means of an additive manufacturing method.

Description

Name of the invention

METHOD FOR PRODUCING A BEARING RING THROUGH ADDITIVE PRODUCTION PROCESS AND BEARING BEARING WITH BEARING RING Field of the invention

The invention relates to a method for producing a bearing ring and a rolling bearing with a bearing ring. Background of the invention

EP 2 825 783 B1 discloses a pinion bearing arrangement of a transmission for a vehicle or aircraft, which comprises at least one roller bearing. At least one of the roller bearings is a ball bearing, wherein the ball bearing has an inner ring and an outer ring. Both rings have raceways for balls located inside the rings. At least one raceway has a radius and the balls have a diameter. The ratio of the radius of the track to the diameter of the ball, namely the osculation is 0.53. Further, at least one of the rings is formed of a ball bearing steel made by a powder metallurgy method. For this purpose, a powder metallurgy component is used, the 0.5 to 2.0 wt .-% C, at most 0.035 wt .-% S, 3.0 to 5.0 wt .-% Cr, 1, 0 to 4.0 Wt .-% V, 1, 0 to 12.0 wt .-% W and 2.0 to 12.0 wt .-% Mo contains. The surface of the raceways has a hardness between 65 HRC and 70 HRC and the balls of the at least one ball bearing are made of ceramic material.

Furthermore, DE 10 2010 019 587 A1 relates to a rolling bearing with bearing rings and with rolling elements, which are made of a powder-metallurgically produced Schnellar- beitsstahl, wherein the high-speed steel at least 1, 29 to 2 wt .-% carbon, 0.5 to 0.6 % By weight of silicon, 0.2 to 0.4% by weight of manganese, 3.8 to 4.8% by weight of chromium, 2 to 5% by weight of molybdenum, 3 to 5, 1% by weight Vanadium, 5 to 14.3 wt .-% tungsten and 0 to 1 1 wt .-% cobalt. Object of the invention

The object of the present invention is to further develop a method for producing a bearing ring and a rolling bearing with a bearing ring, and in particular to realize a resource-efficient production of the bearing ring.

DESCRIPTION OF THE INVENTION This object is achieved by a respective method having the features of claims 1 and 2 and by a respective roller bearing having the features of claims 6 and 7. Preferred or advantageous embodiments of the invention will become apparent from the dependent claims of the following description and the accompanying drawings.

According to a method according to the invention for producing a bearing ring for a roller bearing, the bearing ring is formed near net shape, at least by an additive manufacturing method, wherein the ring material of the bearing ring at least 1, 29 to 2 wt .-% carbon, 0.5 to 0.6 wt .-% Silicon, 0.2 to 0.4% by weight of manganese, 3.8 to 4.8% by weight of chromium, 2 to 5% by weight of molybdenum, 3 to 5, 1% by weight of vanadium, 5 to 14.3 wt .-% tungsten and 0 to 1 1 wt .-% cobalt.

According to an alternative method according to the invention for producing a bearing ring for a rolling bearing, the bearing ring is formed close to net shape, at least 0.5 to 2 wt .-% carbon, at most 0.035 wt .-% sulfur, 3 to 5% by weight of chromium, 1 to 4% by weight of vanadium, 1 to 12% by weight of tungsten and 2 to 12% by weight of molybdenum.

In other words, the production of the bearing ring by an additive manufacturing process or by a generative manufacturing process or a three-dimensional printing process. The additive manufacturing Driving allows a fast and cost-effective production of the bearing ring, wherein the production takes place in particular on the basis of computer-internal data models of informal or form neutral starting material by means of chemical and / or physical processes. In particular, a material powder with an alloy composition which essentially corresponds to the abovementioned alloy compositions is processed layer by layer into a bearing ring in the context of the additive production method. The alloy composition of the bearing ring in the final near-net state comprises at least 1.29 to 2% by weight of carbon, 0.5 to 0.6% by weight of silicon, 0.2 to 0.4% by weight of manganese, 3.8 to 4.8% by weight of chromium, 2 to 5% by weight of molybdenum, 3 to 5.1% by weight of vanadium, 5 to 14.3% by weight of tungsten and 0 to 1 1% by weight of cobalt or at least 0.5 to 2 wt .-% carbon, at most 0.035 wt .-% sulfur, 3 to 5 wt .-% chromium, 1 to 4 wt .-% vanadium, 1 to 12 wt .-% tungsten and 2 bis 12 wt .-% molybdenum. In particular, a laser or an electron beam is used in the processing of the material powder.

Furthermore, the production of the bearing ring by an additive manufacturing process offers the possibility to combine a high-performance material with the formation of an unusual geometry for a bearing ring. In particular undercuts, maximum on-board elevations and near the raceway opening oil supply channels, which can not be made possible by a conventional production of the bearing ring, starting from a powder metallurgically produced high-performance steel, can be realized.

Under near net shape is to be understood that the bearing ring is subjected to little or no rework. Thus, the geometry of the bearing ring is essentially determined by the additive manufacturing process. Using additive manufacturing processes, the smallest quantities are produced with a large variety of products. This represents a particular advantage over the classical powder metallurgical production route. The powder metallurgical production route essentially comprises the process steps of pressing, sintering and rolling. Preferably, at least one raceway, which is provided for guiding rolling elements, undergoes a finishing. The finishing is advantageously a mechanical processing, in particular a grinding or honing. Furthermore, it is also conceivable that an intermediate machining or the finishing process comprises stamping, forming, coating and / or heat treatment. For example, can be done after the application of material rolling or rolling to achieve a correspondingly high compression. According to a preferred embodiment, the additive manufacturing process comprises build-up welding. In particular, the additive manufacturing process includes laser powder buildup welding. In laser powder build-up welding, a relatively thin layer of material powder is laser-welded onto a substrate. As a result, the surface properties of a hybrid ring formed in this way, consisting of substrate and welded material, are adapted to the specific requirements, with a so-called tailored material being formed. Without a change in the substrate, certain properties such as a certain hardness, a certain wear resistance and / or a certain fatigue strength, which are required there, are achieved on the surface of the hybrid ring. The substrate is preferably a bearing ring blank. The outer layer produced by laser powder build-up welding improves the properties of the bearing ring and enables sustainable, application-specific production of the bearing ring. In the cladding process, the high-performance steel to be processed is supplied in a shape-neutral manner as a powder or in the form of a wire in a suitable machining head to an energy source such as a laser or an arc. By means of a carrier gas, the molten steel thus produced is guided onto the surface of a substrate carrier and solidifies there to form a solid shaped body. By suitable manipulation of the substrate carrier and processing head, it is thus possible to produce infinitely complex geometries close to the end.

According to a further preferred embodiment, the additive ferment a powder bed process. Powder bed processes are essentially to be understood as meaning Selective Laser Melting (LBM) and Selective Electron Beam Melting (EBM). The powder bed processes enable component production with maximum freedom from geometry.

In powder bed-based processes, a component is produced in layers by irradiation of a geometrically defined powder bed of the material to be processed with laser or electron beam. The introduced energy of the radiation used is to be chosen so that the powder bed completely melts in the irradiated area and an area of the underlying layer is melted to produce a firm bond, regardless of whether already solidified material of a previous irradiation is present. After irradiation, another layer of powder is applied, in which case the irradiation begins again. This process is repeated until the component to be manufactured is completely created.

An inventive rolling bearing has two bearing rings, namely an inner ring and an outer ring, which are formed from a ring material, wherein the inner ring on an outer peripheral surface and the outer ring on an inner peripheral surface each have a raceway for guiding rolling elements, wherein the rolling elements on the respective raceway roll, wherein the ring material at least 1, 29 to 2 wt .-% carbon, 0.5 to 0.6 wt .-% silicon, 0.2 to 0.4 wt .-% manganese, 3.8 to 4.8 Wt .-% chromium, 2 to 5 wt .-% molybdenum, 3 to 5.1 wt .-% vanadium, 5 to 14.3 wt .-% tungsten and 0 to 1 1 wt .-% cobalt, and wherein at least one of the two bearing rings is made at least by an additive manufacturing process. Alternatively, the annulus material may contain at least 0.5 to 2 wt% carbon, at most 0.035 wt% sulfur, 3 to 5 wt% chromium, 1 to 4 wt% vanadium, 1 to 12 wt% tungsten and 2 to 12 wt% molybdenum.

In particular, a hardness of a surface of the respective raceway is at least 62 HRC. The ring material in particular has an E-modulus of at least 220 MPa. Preferably, an osculation between the jewei- ligen career and the rolling elements, which are designed in particular as balls at least 1, 05. Furthermore, the respective raceway preferably has a surface roughness with a mean roughness value R _a of 0.005 to 0.03, with a skewness Rsk of 0.3 to -5 and with a slope Rku of 3 to 15.

A mean roughness value R _a is the arithmetic mean of the amounts of all profile values of the roughness profile of a surface. Furthermore, a skewness Rsk is a measure of the asymmetry of an amplitude density curve of the surface roughness. A negative skewness indicates a surface with good bearing behavior. The slope Rku is a measure of the steepness of the amplitude density curve of the surface roughness. For normally distributed profile values, the slope Rku is 3. The parameters skew Rsk and slope Rku are strongly influenced by individual peaks and valleys of the profile for the surface roughness.

The spherical rolling elements roll in preferably groove-shaped raceways on the inner ring and outer ring, so that the outer ring and the inner ring are rotatable relative to each other about an axis of rotation. The osculation indicates the relationship between raceway radius and ball diameter. Thus, the osculation can be calculated by forming the quotient between the respective raceway radius and the ball diameter.

If the radius of the respective track is equal to the diameter of the ball rolling on it, the osculation is 1. Accordingly, the osculation increases with increasing raceway radius. With increasing osculation, the contact area between ball and contact area decreases on the track, which has an advantageous effect on friction losses. With decreasing osculation increases accordingly the contact area between the ball and contact area of the track, at the same time increase the friction losses.

Preferably, the rolling elements are formed from a ceramic material or from the annular material. Consequently, the rolling elements are formed of a ceramic or of the annular material, which contains at least 0.5 to 2% by weight of carbon. substance, at most 0.035% by weight of sulfur, 3 to 5% by weight of chromium, 1 to 4% by weight of vanadium, 1 to 12% by weight of tungsten and 2 to 12% by weight of molybdenum, or from the ring material containing at least 1.29 to 2% by weight of carbon, 0.5 to 0.6% by weight of silicon, 0.2 to 0.4% by weight of manganese, 3.8 to 4.8 Wt .-% chromium, 2 to 5 wt .-% molybdenum, 3 to 5, 1 wt .-% vanadium, 5 to 14.3 wt .-% tungsten and 0 to 1 1 wt .-% cobalt.

According to a preferred embodiment, at least one of the two bearing rings on an uneven distribution of alloying elements. In other words, a functionally higher-grade mixture of the alloying elements on a track is used for the respective application. The high-grade mixture of the alloying elements changes with increasing distance to the raceway and is advantageously cheaper thereby. There is a mapping of a material gradient over the cross section of the bearing ring, wherein the mixture of alloying elements is used only where it is needed, namely in the raceway. In addition, additive manufacturing offers the possibility of not forming bearing rings completely, but only partially of powder metallurgical material. For example, if material is used as the starting material, its composition can be varied over the duration of the production process, thus influencing the composition of the annular material.

The use of a rolling bearing according to the invention is proposed for supporting a spindle shaft or for supporting a compressor shaft or for supporting a rotor shaft. Thus, the rolling bearing is particularly well suited for the storage of fast-rotating shafts. The rolling bearing according to the invention allows a noise and wear-optimized storage of the shaft.

Brief description of the drawings

Further measures improving the invention will be described in more detail below together with the description of a preferred embodiment of the invention with reference to FIGS. Showing: Figure 1 is a schematic perspective view of a rolling bearing according to the invention, and

Figure 2 is a schematic partial sectional view of a bearing assembly with the rolling bearing according to the invention according to Figure 1 and with a shaft.

DETAILED DESCRIPTION OF THE DRAWINGS According to FIG. 1, a rolling bearing 1 according to the invention for a machine tool, not shown here, comprises two bearing rings 2, 3, namely an inner ring 2 and an outer ring 3 and balls arranged radially between the inner ring 2 and the outer ring 3 as rolling elements 6. The rolling elements 6 are guided by a cage 8. The rolling bearing 1 is designed as a deep groove ball bearing.

In Figure 2, the rolling bearing 1 of Figure 1 supports a shaft 7. The shaft 7 is presently designed as a spindle shaft of the machine tool and only partially shown. The inner ring 2 has on an outer peripheral surface of a raceway 4 for guiding the rolling elements 6. Furthermore, the outer ring 3 on an inner circumferential surface on a raceway 5 for guiding the rolling elements 6. The rolling elements 6 roll on the respective raceway 4, 5 between the inner ring 2 and the outer ring 3, wherein the rolling elements 6 are formed of a ceramic material.

The inner ring 2 and the outer ring 3 are formed from a ring material, wherein the ring material in the present case at least 1, 29 to 2 wt .-% carbon, 0.5 to 0.6 wt .-% silicon, 0.2 to 0.4 wt % Of manganese, 3.8 to 4.8% by weight of chromium, 2 to 5% by weight of molybdenum, 3 to 5, 1% by weight of vanadium, 5 to 14.3% by weight of tungsten and 0 to 1 1 wt .-% cobalt. Alternatively, the ring material may contain at least 0.5 to 2 wt% carbon, at most 0.035 wt% sulfur, 3 to 5 wt% chromium, 1 to 4 wt% vanadium, 1 to 12 wt% tungsten and 2 to 12 wt% molybdenum. Both bearing rings 2, 3 were formed by an additive manufacturing process from a powder material near net shape. Further, the two raceways 4, 5 were subjected to finishing by grinding.

LIST OF REFERENCE NUMBERS

Rolling

Inner ring; bearing ring

Outer ring; bearing ring

career

Rolling

wave

Cage

Claims

claims

1 . Method for producing a bearing ring (2, 3) for a rolling bearing (1), wherein the bearing ring (2, 3) is formed close to the final shape at least by an additive manufacturing process, wherein the annular material of the bearing ring (2, 3) at least 1, 29 up to 2% by weight of carbon, 0.5 to 0.6% by weight of silicon, 0.2 to 0.4% by weight of manganese, 3.8 to 4.8% by weight of chromium, 2 to 5 Wt .-% molybdenum, 3 to 5, 1 wt .-% vanadium, 5 to 14.3 wt .-% tungsten and 0 to 1 1 wt .-% cobalt.

2. A method for producing a bearing ring (2, 3) for a rolling bearing (1), wherein the bearing ring (2, 3) is formed near the endkonturnah at least by an additive manufacturing process, wherein the annular material of the bearing ring (2, 3) at least 0.5 up to 2% by weight of carbon, at most 0.035% by weight of sulfur, 3 to 5% by weight of chromium, 1 to 4% by weight of vanadium, 1 to 12% by weight of tungsten and 2 to 12% by weight Molybdenum includes.

3. The method according to any one of claims 1 or 2, characterized in that at least one track (4, 5), which is provided for guiding rolling elements (6), is subjected to a finishing.

4. The method according to any one of the preceding claims, characterized in that the additive manufacturing process comprises a buildup welding.

5. The method according to any one of the preceding claims, characterized in that the additive manufacturing process comprises a powder bed process. 6. Rolling bearing (1) with two bearing rings (2, 3), namely an inner ring (2) and an outer ring (3), which are formed from a ring material, wherein the inner ring (2) on an outer peripheral surface and the outer ring (3) on an inner circumferential surface in each case a raceway (4, 5) for guiding Rolling bodies (6), wherein the rolling elements (6) roll on the respective track (4, 5), wherein the ring material at least 1, 29 to 2 wt .-% carbon, 0.5 to 0,

6 wt .-% silicon, 0.2 to 0.4 wt .-% manganese, 3.8 to 4.8 wt .-% chromium, 2 to 5 wt .-% molybdenum, 3 to 5.1 wt. % Vanadium, 5 to 14.3 wt .-% tungsten and 0 to 1 1 wt .-% cobalt comprises, characterized in that at least one of the two bearing rings (2, 3) is made at least by an additive manufacturing process.

7. rolling bearing (1) with two bearing rings (2, 3), namely an inner ring (2) and an outer ring (3), which are formed from a ring material, wherein the inner ring (2) on an outer peripheral surface and the outer ring (3) on an inner peripheral surface each have a track (4, 5) for guiding rolling elements (6), wherein the rolling elements (6) roll on the respective track (4, 5), wherein the ring material at least 0.5 to 2 wt .-% Carbon, at most 0.035% by weight of sulfur, 3 to 5% by weight of chromium, 1 to 4% by weight of vanadium, 1 to 12% by weight of tungsten and 2 to 12% by weight of molybdenum, characterized at least one of the two bearing rings (2, 3) is produced at least by an additive manufacturing method.

8. Rolling bearing (1) according to any one of claims 6 or 7, characterized in that the rolling elements (6) are formed of a ceramic material or the annular material.

9. Rolling bearing (1) according to one of the preceding claims, characterized in that at least one of the two bearing rings (2, 3) has an uneven distribution of alloying elements.

10. Use of a rolling bearing (1) according to any one of claims 6 to 4 for supporting a spindle shaft or for supporting a compressor shaft or for supporting a rotor shaft.