Method for manufacturing a bearing component

Abstract

A method for manufacturing a bearing component (2) is disclosed, the method comprising the following steps: Providing (S2) a green body (1) having the desired shape of the bearing component, Converting (S3) the green body (1) into a porous carbon body, and Infiltration (S4) of the carbon body with at least one liquid and / or gaseous substance, wherein the green body (1) comprises at least one polymer-based binder and at least one carbonizable bio-based filler material.

Description

Technical field

[0001] The present invention relates to a method for manufacturing a bearing component according to the preamble of claim 1. Technical background

[0002] Bearings are generally known for enabling relative rotational movement between two components. Under harsh operating conditions, such as increased loads combined with higher temperatures, thinner lubricant films, and / or insufficient lubrication, the components of a bearing can suffer surface-initiated fatigue, known as micropitting, which can further lead to indentations, surface-initiated spalling, and galling.

[0003] Under such challenging conditions, it may be necessary to use at least one component in the bearing made of a more resistant material. Ceramics, in particular, are characterized by their hardness and abrasion resistance, chemical stability, and temperature resistance. However, the production of ceramics is energy-intensive, making the manufacture of a ceramic bearing component relatively expensive and resulting in a relatively high carbon footprint. Additionally, depending on the application, the ceramic used may be too brittle and therefore prone to breakage under heavy loads.

[0004] It is therefore an object of the present invention to provide a method for manufacturing a bearing component that enables improved fracture toughness of the bearing component while being cost-effective and having an improved CO2 balance. Summary of the invention

[0005] This problem is solved by a method for manufacturing a bearing component according to claim 1.

[0006] The following describes a method for manufacturing a bearing component, the method comprising the following steps: Providing a green body, Converting the green body into a porous carbon body, wherein the green body and / or the carbon body is provided with the desired shape of the bearing component and Infiltration of the carbon body with at least one liquid and / or gaseous substance.

[0007] To improve the fracture toughness of the bearing component while simultaneously manufacturing it cost-effectively and with an improved CO2 balance, the green body contains at least one polymer-based binder and at least one carbonizable, bio-based filler material. Specifically, the polymers used can be bio-based polymers, such as lignin, non-bio-based polymers, such as PEEK, and / or mixtures thereof.

[0008] The bearing component can be, in particular, a plain bearing component or a rolling bearing component. For example, the bearing component can be an outer ring, an inner ring, a housing, part of a housing, a bearing sleeve, a raceway, or the like.

[0009] For example, the green body can be provided directly in the desired shape of the bearing component. Alternatively, the desired shape of the bearing component can be formed from the provided green body. Or, additionally, the desired shape of the bearing component can be machined from the carbon body. Since the volume of the green body may change during its transformation into the porous carbon body, shaping the carbon body ensures that the bearing component has the desired dimensions. The volume change that can occur during the transformation of the green body into the carbon body can depend on factors such as the polymer-based binder used, the bio-based filler material used, the manufacturing process for the green body, etc.

[0010] The liquid or gaseous substance can be a metal, semimetal, metal salt, polymer, hydrocarbon, or the like. Furthermore, the substance can be a mixture of several substances. For example, the substance can include silicon, aluminum, magnesium, titanium, copper, alloys, and / or semimetal-containing substances such as silicon tetrachloride, which are particularly suitable for infiltrating a carbon body. In particular, if the carbon body is to be infiltrated with a mixture of several substances, at least one substance can be the main substance, and the other substances can be present as additives with a proportion of up to 20 wt%. For example, silicon can be used as the main substance, and metal and / or metal alloys as additives. The additives can be particularly suitable for modifying the material properties of the finished bearing component.For example, the sliding behavior of the surface and / or a surface layer can be improved by a suitable choice of additives.

[0011] The bio-based filling material can consist of wood, cellulose, cellulose fiber, lignin, and / or other natural fibers. For example, the wood can be derived from wood processing waste such as sawdust, wood dust, or similar materials. The other natural fibers can be waste products such as biomass waste, paper waste, or waste from the grain industry, such as rice hulls, chaff, husks, or bran. Depending on the size of the starting material, the bio-based filling material can be directly compressed with the polymer-based binder, or it can be reduced to a desired particle size using appropriate methods. Since the bio-based filling material is sustainable, it can improve the CO2 footprint of the bearing component and its production.Furthermore, a bearing component that is at least partially made from a green body containing at least some biologically based filler material exhibits improved mechanical properties, such as improved strength.

[0012] Furthermore, by appropriately selecting the polymer binder content, particle size and other process parameters during the production of the green body, such as temperature, pressure, atmospheric composition, etc., the mechanical properties, such as fracture toughness or strength, of the finished bearing component can be adjusted.

[0013] Preferably, the polymer-based binder comprises at least one thermoset and / or one crosslinkable thermoplastic. Advantageously, thermoset binders retain their shape under heat, so that the shape of the green body is essentially preserved when it is converted into the porous carbon body. This makes it possible, in particular, to obtain a green body that is structurally stable enough to be converted into a porous carbon body without distortion.

[0014] Alternatively or additionally, polymer-based binders such as phenolic resins, lignin, and / or dimensionally stable, crosslinkable, curable plastics, such as PEEK, can be used. A mixture of a thermoplastic binder and a thermosetting binder can also be used.

[0015] According to a preferred embodiment, the green body is produced by extrusion, pressing, cutting, turning, milling, 3D printing, and / or another additive manufacturing process. This allows for the production of a green body that can have any desired shape. Depending on the type of biological filler material, the green body may still be surrounded by loose particles of the filler material after the binder has cured or dried. Therefore, depending on the manufacturing process of the green body, it may be necessary to at least partially remove the green body from residual filler material, for example, if the green body is formed in a powder bed, and / or to separate it from loose, unsolidified particles. However, it should be noted that this step may be omitted in other manufacturing processes for the green body.Furthermore, a (fine) cleaning of the green body can follow to remove any adhering particle residue. This cleaning can be done, for example, by vacuuming up the loose particles. However, the type of cleaning is not restricted, and all known methods can be used.

[0016] Furthermore, depending on the chosen manufacturing process for the green body, at least one additive may be added to the mass consisting of at least one polymer-based binder and at least one carbonizable, bio-based filler material, which is suitable for making the mass usable for the chosen manufacturing process. For example, if the green body is formed by 3D printing, at least one additive for 3D printing may be added to the at least one polymer-based binder and the at least one carbonizable, bio-based filler material.

[0017] Preferably, the proportion of the bio-based filler material in the green body is between 5 wt.% and 90 wt.%. Depending on the application, the proportion of the bio-based filler material in the green body can even more preferably be between 40 wt.% and 90 wt.%. In particular, the bio-based filler material can have a particle size between 0.0001 and 2.0 mm, preferably between 0.05 and 0.5 mm.

[0018] According to a further preferred embodiment, the conversion of the green body into the porous carbon body is carried out by pyrolysis of the green body. Preferably, the pyrolysis process is carried out under a virtually oxygen-free atmosphere. A virtually oxygen-free atmosphere is understood to mean, in particular, an atmosphere containing less than 3% residual oxygen. This can be, for example, a protective gas atmosphere and / or a vacuum. For example, the protective gas atmosphere can comprise argon, nitrogen, or other suitable gases or gas mixtures. Furthermore, the pyrolysis process can be carried out at a temperature of at least 400°C, particularly at a temperature between 500°C and 3000°C. This enables sufficient conversion of the contained carbon to form the porous carbon body.

[0019] Furthermore, the carbon body can be infiltrated with silicon. Preferably, the carbon body can be infiltrated with liquid and / or gaseous silicon. In particular, the liquid and / or gaseous silicon can include additives. Silicon carbide is formed by infiltrating the porous carbon body with silicon. Silicon carbide ceramics are characterized in particular by their hardness and abrasion resistance, chemical stability, and temperature resistance. Compared to conventional materials used in bearing components, especially plain bearing components, such as bronze or coated bronze, silicon carbide exhibits improved performance. Moreover, the use of biological filler material allows for an improved CO2 balance.

[0020] When silicon infiltrates the porous carbon body, the carbon can react with the silicon to form SiC (silicon carbide). The carbon body, located above the melting point of silicon and essentially above the surface of a silicon bath, becomes saturated with silicon through capillary action. This typically results in a composite material containing SiC, unreacted carbon, and free silicon. It is therefore referred to as a C / Si / SiC composite.

[0021] Further advantages of a bearing component manufactured according to the described method include the possibility of using less lubricant, with simultaneously reduced wear, and an improved bearing component lifespan. Furthermore, bearing components obtained using the above-described method can exhibit improved tolerance to contaminated lubricants, be used at higher operating temperatures, and possess improved chemical stability. Additionally, compared to known plastic-coated bearing components, bearing components obtained using the above-described method can exhibit improved resistance to aging.

[0022] Furthermore, the process may also include at least one optional post-processing step, in particular polishing, honing, grinding, or the like, to obtain the bearing component.

[0023] Furthermore, a green body is also proposed which is produced according to the method described above, wherein the green body comprises at least a polymer-based binder and at least a carbonizable bio-based filler material.

[0024] Further advantages and advantageous embodiments are specified in the description, the drawings, and the claims. In particular, the combinations of features specified in the description and the drawings are purely exemplary, so that the features may also exist individually or in different combinations. Brief character description

[0025] The invention will now be described in more detail with reference to exemplary embodiments illustrated in the drawings. These exemplary embodiments and the combinations shown in them are purely illustrative and do not define the scope of protection of the invention. The scope of protection is defined solely by the pending claims.

[0026] They show: Fig. 1: a flowchart of a process for manufacturing a bearing component according to one embodiment, Fig. 2: a green body for the process of manufacturing a bearing component, and Fig. 3: a bearing component manufactured according to the procedure according to Fig. 1. Detailed description of the invention

[0027] In the following, identical or functionally equivalent elements are marked with the same reference symbols.

[0028] Fig. Figure 1 shows the steps for manufacturing a bearing component according to one embodiment. The bearing component can be, in particular, a plain bearing component or a rolling bearing component. For example, the bearing component can be an outer ring, an inner ring, a housing, part of a housing, a bearing sleeve, a raceway, or the like.

[0029] In a first step, S1, a composite material is produced by mixing at least one polymer-based binder and at least one biologically based filler material together.

[0030] The bio-based filling material can consist of wood, cellulose, cellulose fiber, lignin, and / or other natural fibers, such as wood processing waste, biomass waste, paper waste, waste from the grain industry, and the like. The polymer-based binder is preferably a thermoset, such as phenolic resins and / or lignin, which is a bio-based binder. Alternatively, other dimensionally stable, crosslinkable, curable plastics, such as PEEK, or a mixture of a thermoplastic binder and a thermoset binder can be used.

[0031] Preferably, the proportion of the biologically based filler material in the composite material is between 5 wt.% and 90 wt.% and has a particle size between 0.0001 and 2.0 mm, preferably between 0.05 and 0.5 mm.

[0032] In step S2, a green body of the bearing component is produced from the composite material by extrusion, pressing, cutting, turning, milling, 3D printing, and / or another additive manufacturing process, followed by curing of the binder. Depending on the type of biological filler material, the green body may still be surrounded by loose particles of the filler material after curing or drying of the binder. Therefore, depending on the manufacturing process, the green body can be extracted from a bed of filler powder or separated from the loose, unsolidified particles. Furthermore, the green body can undergo (fine) cleaning to remove any adhering particle residue. This cleaning can be carried out, for example, by suctioning the loose particles. However, the cleaning method is not restricted, and all known methods can be used.

[0033] Subsequently, in step S3, the green body is converted into a porous carbon body by pyrolysis. This is preferably carried out in an oxygen-free atmosphere. A protective gas atmosphere, for example of argon, nitrogen, or other suitable gases or gas mixtures, and / or a vacuum can be used. Advantageously, the pyrolysis process is carried out at a temperature of at least 400°C. This enables sufficient conversion of the carbon to form the porous carbon body. Alternatively, the desired shape of the bearing component can also be machined directly from the carbon body.

[0034] Finally, to obtain the bearing component, the carbon body is infiltrated with liquid silicon in step S4. This liquid silicon can contain additives such as metals, metal alloys, metal salts, or the like. Alternatively, the carbon body can be infiltrated with gaseous silicon. Infiltration of the carbon body with silicon primarily forms silicon carbide. Silicon carbide ceramics are characterized by their hardness and abrasion resistance, chemical stability, and temperature resistance. Typically, this results in a composite material containing unreacted carbon and free silicon in addition to SiC. It is therefore referred to as a C / Si / SiC composite.

[0035] The additives can be particularly suitable for modifying the material properties of the finished bearing component. For example, the sliding behavior of a surface layer of the formed silicon carbide ceramic can be improved by selecting appropriate additives. Alternatively, the green body 1 can also be infiltrated with other liquid or gaseous substances such as metals, metalloids, metal salts, polymers, hydrocarbons, or the like. Furthermore, the green body can also be infiltrated with a mixture of several substances.

[0036] Fig. Figure 2 shows a green body 1 that was obtained after step S2 and Fig. Figure 3 shows the finished bearing component 2. As can be seen from the comparison of the Fig. 2 and Fig.As can be seen in Figure 3, the green body 1 does not lose its basic shape when converted into the porous carbon body by a pyrolysis process. However, it is possible that the volume of the green body 1 may change during this conversion. The volume change that can occur during the conversion of the green body 1 into the carbon body can depend on factors such as the polymer-based binder used, the bio-based filler material used, the manufacturing process for the green body, etc.

[0037] In summary, a manufacturing process for a bearing component is proposed that makes it possible to obtain a bearing component that not only has improved fracture toughness, but is also cost-effective and can be manufactured with an improved CO2 balance.

[0038] Since the bio-based filler material is sustainable, the CO2 footprint of the bearing component and its production can be improved. Compared to conventional materials used in bearing components, especially plain bearings, such as bronze or coated bronze, silicon carbide offers enhanced performance. Furthermore, the use of this bio-based filler material also contributes to an improved CO2 footprint. Additional advantages of a bearing component manufactured using this method include the ability to use less lubricant, reduced wear, and an extended service life.

[0039] Furthermore, the bearing components obtained by the above-described method can exhibit improved tolerance to contaminated lubricants, be used at higher operating temperatures, and have improved chemical stability. Additionally, compared to known plastic-coated bearing components, the bearing components obtained by the above-described method can exhibit improved resistance to aging. Reference symbol list S1-S4 process steps 1 Green body 2 Bearing component

Claims

[1] Method for producing a bearing component (2), the method comprising the following steps: Providing (S2) a green body (1), Converting (S3) the green body (1) into a porous carbon body, wherein the green body (1) and / or the carbon body is provided with the desired shape of the bearing component, and Infiltrating (S4) the carbon body with at least one liquid and / or gaseous substance, characterized by , that the green body (1) comprises at least one polymer-based binder and at least one carbonizable biologically based filler material. [2] The method of claim 1, wherein the biologically based filler material comprises wood, cellulose, cellulose fiber, lignin and / or natural fibers. [3] The method according to claim 1 or 2, wherein the polymer-based binder comprises at least one thermoset and / or a crosslinkable thermoplastic. [4] Method according to one of the preceding claims, wherein the green body (1) is produced by extrusion, pressing, cutting, turning, milling, 3D printing and / or an additive manufacturing process. [5] Method according to one of the preceding claims, wherein a proportion of the biologically based filling material in the green body (1) is at least 5 wt.%, preferably between 5 and 90 wt.%. [6] Method according to one of the preceding claims, wherein converting the green body (1) into the porous carbon body comprises pyrolyzing the green body (1). [7] Process according to claim 6, wherein the pyrolysis process is carried out under an oxygen-free atmosphere, in particular under a protective gas atmosphere and / or in a vacuum. [8] A process according to claim 6 or 7, wherein the pyrolysis process is carried out at a temperature of at least 400°C. [9] Method according to one of the preceding claims, wherein the carbon body is infiltrated at least with silicon. [10] Method according to one of the preceding claims, wherein the method further comprises at least one optional post-processing step, in particular polishing, honing, grinding, etc., in order to obtain the bearing component. [11] Green body (1) for the method for producing a bearing component (2) according to one of claims 1 to 10, wherein the green body (1) comprises at least one polymer-based binder and at least one carbonizable biologically based filler material.

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