Rolling bearing element and method for producing rolling bearing element

Abstract

A rolling bearing element (1), in particular a bearing ring, has a plurality of 3D printed layers (7, 11, 12), in which at least one subset of the layers (7, 11, 12) is constructed from a plurality of layer portions (8, 9, 10) which are arranged one on the other in the respective layers (7, 11, 12) and are made of different materials, and in which at least one subset of the layers (7, 11, 12) is formed from a plurality of layer portions (8, 9, 10) which are arranged one on the other in the respective layers (7, 11, 12). Same layer portions (8, 9, 10) of a plurality of the layers (7, 11, 12) are arranged directly one above the other, and this results in material delamination in a direction transverse to the built 3D printed layer (7, 11, 12).

Description

Technical Field

[0001] The invention relates to an additively manufactured rolling bearing element. The invention also relates to a method for producing such a rolling bearing element. Background Art

[0002] A bearing component is known from WO 2012 / 022616 A1, which is manufactured by means of a 3D printing process. The production of a rolling bearing cage is described in detail in WO 2012 / 022616 A1. In addition, the possibility of additive manufacturing of bearing rings is mentioned. In any case, it is provided that a thin nanocrystalline coating is applied to the base body of the bearing component. The nanocrystalline coating increases the mechanical strength and chemical resistance of the bearing component.

[0003] In DE 10 2017 115 803 A1, the possibility of deposit welding in connection with the production of bearing components is discussed. It is proposed to apply a layer of heat-resistant material representing a second component part to a component part made of a high-temperature alloy by deposit welding, wherein a rolling element raceway is formed on the second layer. In general, DE 10 2017 115 803 A1 relates to components of aircraft engines.

[0004] Spraying processes that can be used in the production of bearing components are disclosed in documents DE 10 2012 203 110 A1 and DE 10 2006 023 690 A1. In both cases, provision is made for spraying molten metal onto a tubular workpiece.

[0005] Other possibilities for material application are described, for example, in WO 2019 / 185626 A1. In this case, the material pattern located on the base is transferred to the substrate.

[0006] Compared to the above-mentioned prior art, the invention is based on the object of expanding the possibilities of using additive processes in the production of rolling bearing components, thereby seeking a particularly favorable ratio between production effort and achievable product properties. Summary of the invention

[0007] According to the invention, this object is achieved by a rolling bearing element having the features of claim 1. The object is also achieved by a method for producing a rolling bearing element according to claim 9. The configurations and advantages of the invention explained below in conjunction with the production method also apply analogously to the device, i.e. the rolling bearing element, and vice versa.

[0008] The rolling bearing element has a plurality of 3D printed layers, wherein at least a subset of these layers is built up from a plurality of layer parts which are arranged one next to the other in the relevant layer and are made of different materials. Within the layer stack forming the rolling bearing element, identical layer parts in a plurality of the layers are arranged directly one above the other and this results in a delamination of the material in a direction transverse to the built up 3D printed layers.

[0009] In general, this results in layers that are at least partially orthogonal to one another, i.e. in intersecting directions. On the one hand, these are layers that are built up on top of one another during additive manufacturing. On the other hand, the layering in the transverse direction results from the fact that each individual 3D printed layer is formed from several adjacent parts, wherein identical parts of a plurality of layers together produce a layered region that extends essentially orthogonally to the superimposed 3D printed layers.

[0010] The overall structure of the rolling bearing element can therefore be viewed as matrix-like in cross section, but a strictly rectangular row-column pattern does not necessarily have to exist. Instead, the 3D printed layers are to be understood as rows, while the so-called columns formed by identical layer parts do not necessarily have a uniform width or run perpendicular to the rows. In all cases, however, there is a cross-structure of 3D printed layers on the one hand and layers of different materials on the other. It has been shown that this makes it possible to manufacture rolling bearing elements with an acceptable amount of effort and that the material properties of different volumes and surface areas can be well adapted to the respective requirements.

[0011] Rolling bearing elements can generally be produced by additively producing a plurality of layers, in each of which different materials which differ from one another at least in terms of their electrical conductivity are arranged one next to another in geometrically defined layer portions, wherein identical layer portions are produced directly one above the other in a plurality of the layers, so that a material layering is formed in a direction transverse to the constructed additively manufactured layers.

[0012] According to various possible embodiments, at least one of the layer parts is constructed from a metallic material and another layer part is constructed from an electrically insulating material. The electrically insulating material can in particular contain at least one of the materials glass and ceramic in the form of a frit. The frit is an initially powdered material made of glass and / or ceramic, which forms a solid component, in this case a rolling bearing element, under the influence of temperature during additive manufacturing. The thickness of the electrically insulating layer of the rolling bearing element, which can also be manufactured from glass, ceramic or glass ceramic in other ways, is 0.1 mm to 1 mm in a typical design.

[0013] High-speed steel grade 1.3344 (X130WMoCrV 6-5-4-3) is particularly suitable as a metallic material for the functional area, ie the raceways, of rolling bearing elements, which can be processed using 3D printing methods.

[0014] Workpieces made of steel with material number 1.3344 can be produced, among other things, using powder metallurgy and are characterized by a homogeneous material structure with a tough material matrix and a very high content of fine, evenly distributed carbides. The properties remain stable even at extremely high application temperatures of up to 400°C.

[0015] In this case, surface hardnesses of 60 HRC and above can be achieved using steel grade 1.3344PM without subsequent heat treatment. In a typical approach, rolling bearing elements are finished after additive manufacturing only by grinding and / or honing, ie machining with geometrically undefined cutting edges.

[0016] In a central volume region of the rolling bearing element between the electrically insulating layer forming the first workpiece surface on the one hand and the metal layer made of a highly elastic material on the other hand, a further metal layer made of a relatively low-elasticity metal material may be present.

[0017] The rolling bearing element can be, for example, a rolling element or a bearing ring. Special forms of rolling elements, for example planetary elements of a planetary roller screw drive, can also be produced by this process depending on the application.

[0018] If the rolling bearing element is designed as an inner ring of a rolling bearing, the diameter of the bore of the bearing ring can, for example, be in the range of 5 mm to 70 mm, or even larger. In all cases, an advantage of the manufacturing process is that the electrically insulating layer, including the electrically insulating layer on the bore of the annular workpiece, can be produced in a single manufacturing step, i.e. during the additive manufacturing of the rolling bearing element.

[0019] The hole of the inner ring is a relatively small area compared to the other surfaces of the rolling bearing. Therefore, the electrical insulation at this point minimizes the capacitance and thus the transmission of alternating current in comparison with a spatially more extensive insulating layer, such as an insulating layer on the outer peripheral surface of the outer ring. If the bearing ring has at least one rim, the insulating layer can be located, for example, on one of the rims, on both rims, or on neither rim.

[0020] In all cases in which the metal parts of rolling bearing elements form the rolling element raceways, in the area of ​​the layer providing the rolling element raceways, each layer in this area can be constructed from three different layer parts arranged one next to the other, namely a metal raceway part, a central layer part of the same metal and an insulating part, while in the area of ​​the layer separated from the rolling element raceways, each layer is constructed from only two different layer parts, namely an insulating part and a part with a composition consistent with the central layer part.

[0021] The thickness of the layer of material providing the rolling element raceway is not necessarily uniform. For example, the thickness of the layer portion providing the rolling element raceway measured along the normal direction of a plane tangential to the rolling element raceway decreases from the center of the rolling element raceway outwards. At the same time, both the cylindrical surface and the end surface of the rolling bearing element can be formed by the electrically insulating layer portion.

[0022] Typically, the material layer used as a rolling element raceway is also referred to as a functional layer. In various possible designs, the material thickness of the functional layer is in the range of 0.3 mm to 5 mm depending on the bearing size, which corresponds to, for example, 2% to 10%, in particular about 5%, of the rolling element diameter assigned to the bearing.

[0023] Additive manufacturing of rolling bearing elements also has the advantage that cooling and / or lubrication channels can be produced during the manufacturing process through the rolling bearing element. In the same way, the cavity can be formed to minimize the mass of the rolling bearing element and thus also minimize the moment of inertia associated with the operation of the rolling bearing. In addition, among other things, it is also possible to prepare a sealing seat of suitable material properties so that machining steps are eliminated.

[0024] The thermal expansion coefficients of the various materials of which rolling bearing elements are additively constructed - some metallic and some non-metallic - must be coordinated with one another so that matching expansion coefficients are ideal. The heating of the various materials, which are usually in powder form, is usually performed using a laser. Laser processing not only solidifies the individual material layers, but also creates a strong connection between the different material parts. In order to make the connection between the different materials more resilient, interlocking geometries can be provided between the individual layer parts.

[0025] The rolling bearing element is particularly suitable for use under conditions that would normally increase wear. Keywords in this context include thin oils, long grease life and high speeds. Furthermore, the rolling bearing element is particularly suitable for use in electric motors, since the passage of electric current is prevented by means of the insulating non-metallic layer. The rolling bearing comprising the rolling bearing element can be any known type of bearing, for example a ball bearing, a cylindrical roller bearing, a barrel roller bearing or a tapered roller bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In the accompanying drawings:

[0027] Figure 1 A rolling bearing, a single-row angular contact ball bearing, is shown in cross section.

[0028] Figure 2 Shown according to Figure 1 Additively produced inner rings of rolling bearings,

[0029] Figure 3 A schematic diagram showing the layer structure of the inner ring. DETAILED DESCRIPTION

[0030] The rolling bearing, generally indicated by 1, is designed as an angular contact ball bearing in an exemplary embodiment. The ball bearing 1 comprises: an inner ring 2; a plurality of rolling elements 3, i.e. balls, which are optionally guided in a cage (not shown); and an outer ring 4. The bearing rings 2, 4 and the rolling elements 3 are collectively referred to as rolling bearing elements 2, 3, 4. The rolling elements 3 roll on the raceway 5 of the inner ring 2 and the raceway 6 of the outer ring 4. In the following, the inner ring 2 is analyzed in more detail, whereby the outer ring 4 can be manufactured in the same way or in any other way. The bore of the inner ring 2 is indicated by 13 and has a cylindrical wall 14, whereby the wall 14 can also have a slightly conical shape. In general, the rolling bearing 1 is suitable for absorbing radial forces and axial forces in one direction in a manner known per se.

[0031] The inner ring 2 has a partially curved profile on its outer side, ie, on its side where the raceway 5 is provided. The partially curved profile is designed according to the pressure angle required for the ball bearing 1 .

[0032] The entire inner ring 2 is additively manufactured, printed in individual layers 7, 11 that are built up. Each layer 7, 11 is made of a different powdered starting material that is heated by a laser during additive manufacturing. In the portion of the inner ring 2 where the raceway 5 is formed, each layer 7 consists of three mutually distinguishable parts 8, 9, 10. In detail, this is an insulating part 8 forming a cylindrical wall 14, a central layer part 9 made of a metal material, and the same metal part 10 forming the raceway 5.

[0033] The raceway portion 10 is made of 1.3344 grade high speed steel and has a surface hardness of at least 60 HRC. In contrast, the hardness of the central layer portion 9 is lower. The central layer portion 9 provides a slight but technically relevant ductility to the inner ring 2. Overall, the layer portions 8, 9, 10 represent material layers which are substantially transversely aligned with the layers 7, 11 arranged horizontally in the figure.

[0034] like Figure 1 and Figure 2As indicated in , the thickness of the raceway layer 10 measured in the radial direction of the rolling bearing 1 is not uniform within the raceway layer 10. The maximum thickness of the raceway layer 10 is present at the point where the mechanical load from the rolling elements 3 is greatest, i.e. in the region through which the pressure line extends. As in the present case, the inclined pressure line means that the rolling bearing 1 is able to absorb radial forces and axial forces. In the direction of the edge of the raceway 5, i.e. in the direction of the lower mechanical load on the raceway 5, the thickness of the raceway portion 10 decreases. On the outside of the raceway 5, the raceway portion 10 is completely omitted, as shown in FIG. Figure 3 In this area, there are layers denoted by 11, which are formed only from layer parts 8, 9. Regardless of the fact that layer part 9 in this case extends to the surface of the inner ring 2, this layer part is always referred to as central layer part 9. A special function is provided in the end layer denoted by 12: in this case, the insulating part 8 extends over almost the entire layer 12, so that the required electrical insulation effect is provided not only on the cylindrical wall 14, but also on almost the entire end face of the inner ring 2. Figure 3 Different from the structure schematically shown in FIG. 8 , the end surface layer 12 can also be completely formed as the insulating layer 8 .

[0035] Reference numerals list

[0036] 1Rolling bearings, ball bearings

[0037] 2Inner ring

[0038] 3Rolling elements, balls

[0039] 4 Outer ring

[0040] 5 Inner raceway

[0041] 6 Outer ring raceway

[0042] 7 The first type of layer is constructed from three layers

[0043] 8-layer insulation

[0044] 9 Central layer

[0045] 10-layer raceway section

[0046] 11 A second type of layer constructed from two layers

[0047] 12 End surface layer

[0048] 13 Holes of inner ring

[0049] 14 Hole wall

Claims

1. A rolling bearing element (1), comprising a plurality of 3D printed layers (7, 11, 12), wherein: At least a subset of these layers (7, 11, 12) is built up from a plurality of layer parts (8, 9, 10) which are arranged one next to another in the relevant layer (7, 11, 12) and are made of different materials, and wherein the same layer parts (8, 9, 10) in a plurality of these layers (7, 11, 12) are arranged directly one above the other and this results in material delamination in a direction transverse to the built 3D printed layers (7, 11, 12).

2. The rolling bearing element (1) according to claim 1, characterized in that At least one of the layer parts (9, 10) is made of a metallic material and the other layer part (8) is made of an electrically insulating material.

3. The rolling bearing element (1) according to claim 2, characterized in that The electrically insulating material includes at least one of a material glass and a ceramic in the form of a frit.

4. The rolling bearing element (1) according to claim 2 or 3, characterized in that Steel with material number 1.3344 is provided as the metallic material for at least one layer part (9, 10).

5. The rolling bearing element (1) according to any one of claims 2 to 4, characterized in that The rolling element raceways (5, 6) are formed from a plurality of metal layer portions (10) stacked one on top of the other.

6. The rolling bearing element (1) according to claim 3, characterized in that In the area of ​​the layer (7) providing the rolling element raceways (5, 6), each layer (7) is constructed from three different layer parts (8, 9, 10) arranged one next to the other, namely a metal raceway part (10), a central layer part (9) of the same metal and an insulating part (8), while in the area of ​​the layer (11) spaced apart from the rolling element raceways (5, 6), each layer (11) is constructed from only two different layer parts (8, 9), namely an insulating part (8) and a part (9) having a composition consistent with that of the central layer part (9).

7. The rolling bearing element (1) according to claim 5 or 6, characterized in that The rolling bearing element is designed as a bearing ring.

8. The rolling bearing element (1) according to claim 7, characterized in that The thickness of the layer portion (10) providing the rolling element raceway (5, 6) measured along the normal direction of a plane tangent to the rolling element raceway (5, 6) decreases outward from the center of the rolling element raceway (5, 6), and both the cylindrical surface (14) and the end surface are formed by the electrically insulating layer portion (8).

9. A method for producing a rolling bearing element (1), wherein: A plurality of layers (7, 11, 12) are produced in an additive manner, in each of which different materials which differ from one another at least in terms of electrical conductivity are arranged one next to another in geometrically defined layer portions (8, 9, 10), wherein a plurality of the layers (7, 11, 12) are produced directly one above the other in identical layer portions (8, 9, 10), so that a material stratification is formed in a direction transverse to the additively manufactured layers (7, 11, 12) being constructed.

10. The method according to claim 9, characterized in that After additive manufacturing, the surface of the rolling bearing element (1) is finished by machining with geometrically undefined cutting edges.

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