Method for reprocessing used rolling bearing and rolling bearing produced thereby

Abstract

The invention relates to a method for retreating a used rolling bearing (10) comprising a rolling bearing component made of a metal base material (2). According to the invention, a used rolling bearing (10) is provided which comprises at least one rolling bearing ring (1a, 1b) and a plurality of rolling bodies (1c), the rolling bearing ring (1a, 1b) and / or the rolling bodies (1c) formed from the metal base material (2) forming a retreatable rolling bearing component. After the rolling bearing component is separated and the at least one rolling bearing component to be fed to the retreatment is identified, a surface region of the at least one rolling bearing component to be retreated is removed, which surface region corresponds to a raceway region (6, 7) of the rolling bearing component to be retreated. A raceway layer (4) is formed after the application of the metal repair material (3).

Description

Technical Field

[0001] The invention relates to a method for reprocessing a used rolling bearing, which comprises rolling bearing components, such as rolling bearing rings or rolling bodies, consisting of a metallic base material, and to a reprocessed rolling bearing produced thereby. Background Art

[0002] EP 2 373 456 B1 discloses a method for repairing a metal product having an open defect, wherein cold forging is performed to close the open defect and then laser build-up welding is performed to cover the cold forging defect with a metal layer.

[0003] In the field of rolling bearing technology, it is known to reprocess bearing components with only moderate wear and tear and to reuse them by reworking the surface of the bearing rings by removing material. In order to compensate for the ring dimensions that change due to the material removal, such bearing rings are combined with rolling element groups that are designed to be relatively larger in size.

[0004] Bearing components made of cost-intensive high-performance materials are of particular interest in terms of recycling. Usually, powders are processed by hot isostatic pressing to form cylinders whose outer diameter is limited due to production conditions. However, the functionality of these high-performance materials is usually required only in the area of ​​functional surfaces, such as bearing rings or raceways of bearing bodies.

[0005] DE 10 2019 216 995 A1 already describes a bearing component having a basic body forming the bearing component and at least one coating applied to the basic body. In this case, the basic body is formed in particular from unalloyed steel, unalloyed tempered steel, standard rolling bearing steel, cast iron or other metal alloys. As a coating, a hard material, in particular an alloy steel, is applied to the basic body. The formation of the coating is carried out by build-up welding. It is also mentioned that build-up welding can also be used for the reprocessing of used large bearing rings.

[0006] DE 10 2017 115 803 A1 discloses a method for producing a metal component having two component sections made of different metal materials. Here, a layer made of high-temperature-resistant steel is applied by build-up welding to a carrier made of a high-temperature alloy, where a rolling track is formed. Summary of the invention

[0007] The object of the present invention is to reuse a used rolling bearing and to provide a method for reprocessing such a used rolling bearing.

[0008] The object is achieved with a method for reprocessing a used rolling bearing comprising rolling bearing components consisting of a metallic base material by means of the following steps:

[0009] A used rolling bearing is provided, the rolling bearing comprising at least one rolling bearing ring and a plurality of rolling bodies, wherein the rolling bearing ring and / or the rolling bodies formed from a metallic base material form a reprocessable rolling body component,

[0010] at least separating the reprocessable rolling element components and identifying at least one rolling element bearing component to be fed to reprocessing from a plurality of reprocessable rolling element bearing components,

[0011] removing at least one surface region of the rolling bearing component to be reprocessed in order to prepare a receiving region for receiving the metallic repair material, said surface region corresponding to the raceway region of the rolling bearing component to be reprocessed,

[0012] Optionally, the intermediate layer material is applied to the metallic base material in the receiving region,

[0013] Applying the metallic repair material to the metallic base material or, if applicable, to the intermediate layer material in the receiving region to form the raceway layer, wherein the metallic repair material is melted with the metallic base material or, if applicable, with the intermediate layer material,

[0014] performing remachining of the exposed surface of the raceway layer to provide at least one reprocessed rolling bearing component, and

[0015] At least one reprocessed rolling bearing component is assembled with the remaining rolling bearing components of the used rolling bearing to form a reprocessed rolling bearing.

[0016] Furthermore, in order to ensure the reprocessing of the rolling bearing component while maintaining the internal and / or external geometry, the removed surface area is replaced, that is to say restructured. For this purpose, a raceway layer of sufficient thickness and hardness is applied. Furthermore, the application of a raceway layer is also suitable for forming a high-quality rolling bearing component with improved properties in terms of wear resistance and durability in the sense of upcycling, provided that the repair material has a higher wear resistance than the removed material of the metallic base material.

[0017] Preferably, the surface area is removed by turning. However, other removal methods, such as milling or grinding, can also be used. Combinations of different removal methods can also be used.

[0018] The at least one rolling element component to be reprocessed is in particular a rolling element bearing ring, and the removal in the raceway region is carried out in the range of D / 100 to D / 20 of the diameter D of the rolling element of the rolling element bearing. Preferably, the removal is carried out in the range of 0.5% to 5%, preferably 0.5% to 1.5%, of the diameter D of the rolling element of the rolling element bearing. In this case, the removal is usually carried out in the range of 0.4 mm to 10 mm.

[0019] The at least one rolling bearing component to be reprocessed is preferably a rolling bearing ring and has, in particular, a bore diameter of greater than or equal to 50 mm, in particular greater than or equal to 120 mm.

[0020] The metallic base material is preferably selected from rolling bearing steels, quenched and tempered steels, structural steels or case-hardened steels.

[0021] The repair material is preferably steel with the following proportions:

[0022] 0 to 10 wt% Mo,

[0023] 0 to 19 wt.% W,

[0024] 0 to 5 wt% V,

[0025] 3.5 to 5 wt% Cr,

[0026] 0 to 11 wt% Co,

[0027] 0.75 to 1.2 wt% C,

[0028] The remainder is iron and unavoidable impurities or other elements such as Mn, Si, Cu, Ni, P, S, whose proportion is less than 0.5% by weight.

[0029] In particular, steel of type 1.3344 (X130WMoCrV 6-5-4-3) is used. Since no heat treatment is applied, there may be residual austenite (up to about 30%) which has a hardness of the constructed material of more than 62 HRC.

[0030] Alternatively, the repair material is preferably a martensitic stainless steel, such as type 1.4034 (X46Cr13), or a hard metal based on tungsten carbide in a nickel bond matrix, which is also known on the market under the name “Cermadur”.

[0031] As the intermediate layer material, in particular, non-hardenable steel with a carbon content of less than 0.15% is used. This should improve the adhesion to the base material and the production of the repair material on the intermediate layer material. The application of the intermediate layer material to the base material is preferably carried out in the same way as the application of the repair material described below.

[0032] The application of the metallic repair material can be carried out by any material application method, wherein a metallic connection is formed between the base material and the repair material. The application is carried out in particular by means of a directed energy deposition method (Directed Energy Deposition DED), for example by means of a laser, an electron beam or a plasma discharge. In this case, a powder or a metal wire is melted in a receiving area on the surface of the metallic base material or on an intermediate layer material in the receiving area. As a result, a wave structure is obtained in the transition area between the base material and the repair material or between the intermediate layer material and the repair material, which wave structure is visible in the micrograph and can be influenced by the process parameters in the directed energy introduction method.

[0033] The heat-affected zone generated here may extend beyond the intermediate layer material into the base material, with the wave pattern extending over the region corresponding to the distance measured between the middle of the wave crest and the middle of the wave trough, wherein the distance is at least 50 μm. This ensures a particularly tight and pore-free connection between the base material and the repair material. The wave pattern and the extension of the heat-affected zone are dependent on coating parameters such as power, coating speed and coating width.

[0034] In a preferred embodiment of the method, the exposed surface of the raceway layer facing away from the base material is reworked and resolidified by cutting. The flatness and surface roughness of the exposed surface of the raceway layer are thus adapted to the requirements in the application of the rolling bearing component.

[0035] In particular, the raceway layer is fine-machined as remachining in the form of a cutting operation, preferably honing. The fine machining is particularly carried out in such a way that the amplitude density distribution has a negative slope with an Rsk value of less than -0.5, so that the surface has a plateau characteristic. Depending on the depth of resolidification, the surface is smooth-rolled (small depth of action), fixed-rolled (medium depth of action) or ring-rolled (simultaneous heat treatment).

[0036] The reprocessed rolling bearing component is either not subsequently subjected to further heat treatment, wherein the metallic repair material has a Rockwell hardness of at least 60 HRC. Alternatively, the reprocessed rolling bearing component can be subsequently subjected to heat treatment and have a Rockwell hardness of at least 63 HRC.

[0037] In the case of a rolling bearing produced according to the method according to the invention, the metallic repair material has a Rockwell hardness of at least 60 HRC. The metallic base material preferably has a lower hardness than this.

[0038] In particular, the metallic repair material has a hardness of more than 62 HRC without a subsequent hardness-increasing process such as carbonitriding or heat treatment.

[0039] The rolling bearing component is a rolling element or a bearing ring. The rolling bearing component is used in particular for rolling bearings of the type of ball bearings, roller bearings, spherical roller bearings, tapered roller bearings, etc. In ball bearings and spherical roller bearings, rolling bearing rings are particularly suitable for treatment by means of the method according to the invention. However, in roller bearings and tapered roller bearings, in addition to rolling bearing rings, rolling elements are also suitable for treatment in the method according to the invention.

[0040] The thickness of the raceway layer varies in accordance with the size of the rolling bearing component and the loads to be received in the application. The at least one rolling element component to be reprocessed is preferably a rolling bearing ring, and the coating in the raceway region is carried out in the range of D / 100 to D / 20 of the diameter D of the rolling element of the rolling bearing. Preferably, the thickness of the raceway layer in the rolling bearing ring corresponds to 0.5% to 5%, preferably 0.5% to 1.5%, of the diameter D of the rolling element of the relevant bearing, and is thus usually in the range of 0.4 mm to 10 mm.

[0041] In the transition zone between base material and repair material or between intermediate layer material and repair material, the materials melt together and are thus cohesively connected. A drop in hardness directly following the transition zone is measurable. The transition zone describes a characteristic wave profile that is essentially achieved by coating methods with directed energy introduction and can be influenced by process parameters as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 and Figure 2 The method according to the invention and the reprocessed rolling bearing component will be explained by way of example. Thus, it is shown that:

[0043] Figure 1 shows a section through a used rolling bearing in the form of a ball bearing; and

[0044] Figure 2 The micrograph shows a section through a reprocessed rolling bearing component. DETAILED DESCRIPTION

[0045] Figure 1 A section through a used rolling bearing 10 in the form of a ball bearing selected by way of example is shown. A first rolling bearing component (= outer ring) in the form of a rolling bearing ring 1a is made of a metallic base material 2 (cf. Figure 2 ) and has a raceway region 7. The second rolling bearing component (=inner ring) in the form of a bearing ring 1b is made of a metallic base material 2 (cf. Figure 2) and has a raceway area 6. The rolling element 1c is formed of a ceramic material. In addition, there is a cage 9 for holding the rolling element 1c. Here, a rolling bearing component in the form of a bearing ring 1a or an outer ring is selected for reprocessing. The raceway area 7 of the used rolling bearing component is fed to the reprocessing in such a way that a surface area of ​​the bearing ring 1a is removed to prepare a receiving area for receiving the metal repair material 3, the surface area corresponding to the raceway area 7 damaged due to wear during use of the rolling bearing 10.

[0046] Subsequently, the metallic repair material 3 is applied in the receiving region to form the raceway layer 4, wherein the metallic repair material 3 is melted with the base material 2. The exposed surface 5 of the raceway layer 4 facing away from the base material 2 (see Figure 2 ) is subjected to reprocessing. As a result, a reprocessed rolling bearing component 11 is present, which can be used again in a rolling bearing 10 as a bearing ring 1a or an outer ring together with other, unprocessed components of the used rolling bearing 10 to form a reprocessed rolling bearing. An intermediate layer material can optionally be arranged between the base material 2 and the repair material 3, wherein the intermediate layer material is then first melted with the base material 2 and the repair material 3 is subsequently melted with the intermediate layer material.

[0047] Figure 2 The micrograph shows a section through a reprocessed rolling bearing component 11. The base material 2 has a raceway layer 4 made of a repair material 3, which is formed by means of a directed energy introduction method. In the transition region 12 where the base material 2 and the repair material 3 are fused, a wave structure is present. The distance A between the median of the wave crest and the median of the wave trough (see dashed line) is at least 50 μm. The exposed surface 5 of the raceway layer 4 facing away from the base material 2 is reprocessed by grinding.

[0048] Reference numerals list

[0049] 1a, 1b Rolling bearing ring

[0050] 1c Rolling element

[0051] 2 Basic metal materials

[0052] 3 Metal repair materials

[0053] 4 Roller layer

[0054] 5 Exposed surface of raceway layer

[0055] 6 Roller area

[0056] 7 Roller area

[0057] 9 Cage

[0058] 10 Rolling bearings

[0059] 11 Reprocessed rolling bearing components

[0060] 12 Transition Zone

[0061] A Spacing.

Claims

1. A method for reprocessing a used rolling bearing (10), the rolling bearing comprising a rolling bearing component consisting of a metallic base material (2), the method comprising the following steps: A used rolling bearing (10) is provided, the rolling bearing comprising at least one rolling bearing ring (1a, 1b) and a plurality of rolling bodies (1c), wherein the rolling bearing ring (1a, 1b) and / or the rolling bodies (1c) formed from the metallic base material (2) form a reprocessable rolling body component, at least separating the reprocessable rolling element components and identifying at least one rolling element bearing component to be fed to reprocessing from a plurality of reprocessable rolling element bearing components, removing at least one surface area of ​​the rolling bearing component to be reprocessed in order to prepare a receiving area for receiving a metallic repair material (3), said surface area corresponding to a raceway area (6, 7) of the rolling bearing component to be reprocessed, Optionally, an intermediate layer material is applied to the metallic base material in the receiving region, The metallic repair material (3) is applied to the metallic base material or, if necessary, to the intermediate layer material in the receiving area to form a raceway layer (4), wherein the metallic repair material (3) is melted with the metallic base material (2) or, if necessary, with the intermediate layer material, performing reprocessing of the exposed surface (5) of the raceway layer (4) to provide at least one reprocessed rolling bearing component (11), and The at least one reprocessed rolling bearing component (11) is assembled with the remaining rolling bearing components of the used rolling bearing (10) to form a reprocessed rolling bearing.

2. The method according to claim 1, wherein the removal of the surface region is performed by means of turning.

3. A method according to claim 1 or 2, wherein the at least one rolling element component to be reprocessed is a rolling bearing ring (1a, 1b) and the removal in the raceway area (6, 7) is carried out in the range of D / 100 to D / 20 of the diameter (D) of the rolling element (1c) of the rolling bearing (10).

4. The method according to any one of claims 1 to 3, wherein the at least one rolling bearing component to be reprocessed is a rolling bearing ring (1a, 1b) and has a bore diameter of greater than 50 mm.

5. The method according to any one of claims 1 to 4, wherein the metallic base material (2) is selected from rolling bearing steel, quenched and tempered steel, structural steel or case-hardened steel.

6. Method according to any one of claims 1 to 5, wherein the metal repair material (3) is selected from: steel of the type 1.3344 (X130WMoCrV 6-5-4-3) or martensitic stainless steel, in particular martensitic stainless steel of the type 1.4034 (X46Cr13), or hard metal based on nickel combined with tungsten carbide in a matrix.

7. The method according to claim 1, wherein a non-hardenable steel having a carbon content of less than 0.15% is selected as the intermediate layer material.

8. The method according to any one of claims 1 to 7, wherein the application of the metallic repair material (3) is carried out by means of a directed energy introduction method.

9. The method according to any one of claims 1 to 8, wherein the exposed surface (5) of the raceway layer (4) is reworked by machining and resolidified.

10. The method according to claim 1, wherein the reprocessed rolling bearing component (11) is subsequently fine-machined.

11. A reprocessed rolling bearing manufactured according to the method according to any one of claims 1 to 10, wherein the metal repair material (3) has a Rockwell hardness of at least 60 HRC.

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