Lightweight bearing cage for turbine engine and method of forming same

Abstract

A rolling bearing cage or rolling bearing cage segment includes: a first side ring or first side ring segment formed of an aluminum alloy AA2618; a second side ring or second side ring segment formed from an aluminum alloy AA2618; and at least one bridge formed of an aluminum alloy AA2618, the at least one bridge connecting the first side ring to the second side ring or connecting the first side ring segment to the second side ring segment.

Description

Technical Field

[0001] The present disclosure relates to a rolling-element bearing cage or a segment of a rolling-element bearing cage, and to a method for manufacturing a rolling-element bearing cage or a segment of a rolling-element bearing cage. Background Art

[0002] Rolling-element bearing cages or segments of rolling-element bearing cages are used in different rolling-element bearings to guide the rolling elements and space the rolling elements apart from each other. These cages and cage segments can have a variety of different configurations and can be made of a variety of different materials, for example, selected based on the type of bearing in which the cage will be used.

[0003] Some rolling-element bearing cages are sometimes made of brass or steel. Since one component of brass, namely copper, is a relatively scarce material, the acquisition cost of brass is relatively high. In addition, lead is used in many manufacturing processes for rolling-element bearing cages made of brass. On the other hand, steel bearing cages are typically silver-plated. Silver is also expensive, and the electroplating process must be carried out carefully to avoid harming workers or releasing potentially hazardous materials into the environment.

[0004] This can pose particular challenges for environmental and / or worker protection and increase the cost of brass bearing cages or coated steel bearing cages.

[0005] It is also known to manufacture bearing cages from certain aluminum alloys. For example, US10215234, which is published by the present applicant and incorporated herein by reference in its entirety, teaches that bearing cages suitable for certain environments can be formed using aluminum alloy AA6082 or aluminum alloy AA7020. These environments do not include high-temperature environments, such as those found in gas turbine engines. Therefore, there is still a need to use brass or materials other than aluminum for bearing cages that will be used in high-temperature environments. Summary of the Invention

[0006] Accordingly, there is a need to provide an improved rolling-element bearing cage or a segment of a rolling-element bearing cage that is simple to manufacture. This need is met by a rolling-element bearing cage or a segment of a rolling-element bearing cage according to the present disclosure or a method for manufacturing a rolling-element bearing cage or a segment of a rolling-element bearing cage.

[0007] The exemplary embodiments relate to a rolling bearing cage or a segment of a rolling bearing cage, which comprises aluminum alloy AA2618 as the material. Due to the use of this alloy as the material, in some exemplary embodiments, it can replace the conventional rolling bearing cages made of brass or steel. In addition, since this material is both suitable for forming the bearing cage and capable of withstanding high temperatures (such as the high temperatures that occur in gas turbine engines), the bearing cage formed of this alloy can be used in environments where the previous aluminum bearing cages cannot be used.

[0008] In addition, the material or the aluminum alloy may have a tensile strength of at least 420 MPa. Here, the tensile strength can be specified as the force per unit area and is a material parameter designated by the symbol R M . Additionally or alternatively, in some exemplary embodiments, the material may have a yield strength of at least 340 MPa. The yield strength can be, for example, a material parameter that specifies the tension applied to the body that causes a slight deformation of 0.2% after release, and is designated as R p0.2 . Additionally or alternatively, the material may also have a hardness of at least 120 HBW and an A5 elongation of at least 7%. Due to the mentioned mechanical values of the material, in some exemplary embodiments, the rolling bearing cage can obtain mechanical properties similar to or even better than those of conventional brass cages or cages made of other aluminum alloys. In some cases, the hardness of the selected material may also be related to post-treatment. For high (hardness) or high-strength alloys, in some exemplary embodiments, there may be a problem that the alloy cannot be riveted. In some cases where the hardness is too low or the material is too soft, cold welding may occur. In addition, too soft a material may not be able to be dried.

[0009] Additionally or alternatively, the rolling bearing cage may be lead-free. In some exemplary embodiments, the preventive measures for preventing lead from reaching the environment or for specifically protecting workers from lead can be omitted. In a similar manner, for example, the manufacturing of the rolling bearing cage can also be carried out in a lead-free manner so that lead does not appear as a processing aid or an intermediate product either. In some exemplary embodiments, the rolling bearing cage can be manufactured with the lowest possible burden on the environment.

[0010] In some exemplary embodiments, the rolling bearing cage is machined from a semi-finished product that has been heat-treated by T6 (such as T61 or T62). Therefore, in some exemplary embodiments, the rolling bearing cage can obtain the required mechanical properties.

[0011] The exemplary embodiments also relate to a method for manufacturing a rolling bearing cage or a rolling bearing cage segment. With this method, the rolling bearing cage or the rolling bearing cage segment is formed from aluminum alloy AA2618. Due to the use of this alloy as the material, in some exemplary embodiments, it is possible to replace conventional rolling bearing cages made of brass, steel, or other aluminum alloys. Additionally, in some exemplary embodiments, the rolling bearing cage made of AA2618 can have a low weight.

[0012] Furthermore, the step of forming the rolling bearing cage can include machining a semi-finished product made of aluminum alloy AA2618. Thus, in some exemplary embodiments, the cage geometry can be manufactured very precisely. Additionally, the desired surface properties of the cage can thereby be produced.

[0013] In some cases, the machining can be carried out in a dry state. Since no cooling lubricant or other liquid is used, in some exemplary embodiments, the cleaning work for the rolling bearing cage, the environment, and / or the machining tools can be reduced and / or even completely omitted. The collection and / or treatment of the cooling lubricant can also be omitted.

[0014] Additionally or alternatively, the method can include manufacturing a semi-finished product, wherein the manufacturing of the semi-finished product includes shaping a bar made of aluminum alloy. In some exemplary embodiments, the rolling bearing cage can then be machined from the semi-finished product that already has a favorable initial geometry. For example, the bar can be extruded. In other exemplary embodiments, a disk of the material can be subjected to a ring rolling process until it reaches approximately the correct dimensions, after which the ring-rolled semi-finished product can be machined to reach its desired dimensions.

[0015] In some cases, alternatively, the manufacturing of the semi-finished product can also include forming a tube. Thus, in some exemplary embodiments, for example, the machined volume in the radial inner region can be reduced. For example, the tube can be drawn for this purpose.

[0016] Additionally or alternatively, in some exemplary embodiments, the manufacturing of the semi-finished product includes forming a tube from a bar. Thus, in some exemplary embodiments, the semi-finished product can acquire the desired properties and the desired shape.

[0017] In addition, the method may include subjecting aluminum alloys, semi-finished products, bars, and / or tubes to a T6 heat treatment. In some exemplary embodiments, since the heat treatment is only performed on the tubes, the steps of manufacturing tubes from bars can be simplified. Due to the heat treatment taking place, in some exemplary embodiments, the semi-finished products (e.g., tubes) can acquire the described mechanical properties. The T6 heat treatment may include, for example, quenching in a solution and / or water and using a solid. Subsequently, aging may occur, for example, by air cooling. In some exemplary embodiments, the T6 heat treatment may only include the processes mentioned. Optionally, the T6 heat treatment may also include solution annealing, quenching, and artificial aging, or may consist entirely of these processes.

[0018] Additionally or alternatively, the method may include riveting a plurality of rolling bearing cage segments. Thus, in some exemplary embodiments, a rolling bearing cage can be assembled from a single part. This is advantageous, for example, for assembly and / or transportation purposes, especially for large rolling bearing cages. Here, the single part or rolling bearing cage segment can be, for example, a bridge, a side ring, a segment of a side ring, a flange, a segment of a bridge, and / or a rolling bearing cage segment that includes at least one bridge and at least one additional segment (e.g., a segment of a side ring).

[0019] For the implementation of the exemplary embodiments in their various design options, the exemplary embodiments and their respective features disclosed in the description, the following claims, and the drawings can be meaningful and can be implemented individually and in any combination. Description of the Drawings

[0020] These and other aspects of the present invention will be better understood after reading the following detailed description and the drawings, wherein:

[0021] Figure 1 is a perspective view of a rolling bearing cage according to an embodiment of the present disclosure.

[0022] Figure 2 is a flowchart showing a method for manufacturing a rolling bearing cage or a rolling bearing cage segment according to an embodiment of the present disclosure. Detailed Description

[0023] In the following description of the drawings, the same reference numerals indicate the same or similar components. In addition, for components and objects that appear multiple times in an exemplary embodiment or illustration and are described together in terms of one or more common features, a general reference numeral is used. Components or objects described using the same or general reference numerals may not only be presented as the same, but as an alternative, may be presented as different in terms of a single, multiple, or all features, for example, different in terms of their dimensions, as long as the specification does not explicitly or implicitly indicate otherwise.

[0024] The rolling bearing ( / rolling - element bearing) cage 1 is made of an aluminum alloy as the material. The aluminum alloy is AA2618. The rolling - bearing cage 1 includes a plurality of rolling - bearing cage segments ( / sections / segments) 3. The rolling - bearing cage segments 3 can also be made of AA2618. In some exemplary embodiments, due to the use of AA2618 as the material, conventional rolling - bearing cages made of Fe or other aluminum alloys can be replaced. In some additional exemplary embodiments (not shown), the rolling - bearing cage segments can have different shapes, or the cage can be formed in a unitary manner rather than being formed by a plurality of cage segments.

[0025] For bearing cages that will be used in certain environments, AA2618 is not the most suitable aluminum alloy. For example, the relatively low corrosion resistance and overall hardness of this alloy make it less than ideal for use in wheel bearings (e.g., in trucks, trains, and automobiles), where the bearing cage may be exposed to moisture or contaminants. However, despite this relatively low corrosion resistance and relatively low overall hardness, the aluminum alloy AA2618 has a relatively high hardness at high temperatures (e.g., above 150 °C) that occur in the environment of such a gas turbine engine. The aluminum alloy AA2618 also has a fatigue strength that makes it suitable for use as a bearing cage in a gas turbine engine. These properties make it possible to obtain the benefits of using an aluminum - alloy bearing cage in gas turbine engines and other high - temperature environments where it has hitherto been impossible or impractical to use an aluminum - alloy bearing cage.

[0026] Figure 1The rolling bearing cage 1 can be used for tapered roller bearings. In some additional exemplary embodiments (not shown), the rolling bearing cage or a section of the rolling bearing cage can also be configured for other rolling bearings, such as needle bearings, cylindrical roller bearings, barrel roller bearings, etc. The cage can be configured to be used with single-row bearings or with multi-row bearings. The rolling bearing cage can also be configured for multi-row tapered roller bearings.

[0027] Aluminum alloy AA2618 includes, in addition to aluminum (Al), copper (Cu) in a proportion of 1.9 to 2.7 weight percent, magnesium (Mg) in a proportion of 1.3 to 1.8 weight percent, iron (Fe) in a proportion of 0.9 to 1.3 weight percent, nickel (Ni) in a proportion of 0.9 to 1.2 weight percent, silicon (Si) in a proportion of 0.1 to 0.25 weight percent, titanium (Ti) in a proportion of 0.04 to 0.1 weight percent, and optionally zinc (Zn) in a proportion of 0.0 to 0.1 weight percent as alloying components.

[0028] Here, the rolling bearing cage 1 is entirely made of AA2618. In some additional exemplary embodiments (not shown), in addition to the aluminum alloy mentioned, the rolling bearing cage can also include other raw materials or materials, such as coatings, lubricants, and / or connection structures, etc. The connection structure can be, for example, a rivet. The coating can be silver or a physical vapor deposition ceramic coating, such as titanium nitride or chromium nitride.

[0029] Optionally, the rolling bearing cage 1 can be lead-free. In certain cases, the manufacturing of the cage can also occur without the use of lead.

[0030] Figure 2 A schematic depiction of a method 10 for manufacturing a rolling bearing cage or a section of the rolling bearing cage according to an exemplary embodiment is shown. In method 10, the rolling bearing cage or a section of the rolling bearing cage is formed from aluminum alloy AA2618 in process 12.

[0031] The properties of the material can be influenced by the individual alloying components of the selected alloy. For example, magnesium can increase the strength and hardness of the material, support its corrosion resistance, and improve its weldability. The higher strength can be generated, for example, due to solid solution strengthening. Through precipitation heat treatment, the hardness can potentially increase by more than 6%. Silicon can improve the heat treatability of the alloy and, in combination with magnesium (Mg), support corrosion resistance. In addition, under certain conditions, the fluidity can be improved and the shrinking can be reduced. Due to these properties, the use as a casting alloy is broadened. Zinc (Zn) can increase the strength and hardness and can reduce the shrinking and heat checking. In combination with magnesium (Mg), it may be possible to improve the heat treatability and strength of the alloy. In combination with iron, the casting ability can also be improved in some cases. It may also potentially affect the occurrence of intermetallic compounds. It may potentially increase the deformability and ductility of the material. In some cases, the shrinking may also be reduced thereby.

[0032] Process 12 (i.e., the formation of a rolling bearing cage) can include an additional process 14 in which the semi-finished product is machined. Here, the semi-finished product is made of aluminum alloy AA2618. The semi-finished product can be, for example, a prefabricated object. This can be generated, for example, at the start of the manufacturing process and then further processed. Here, they may be components that are pressed, drawn, deep drawn, rolled, and / or extruded. In some cases, the semi-finished product can be a metal sheet, rod, tube, plate, coil, etc. The semi-finished product can be, for example, a tube or rod.

[0033] For example, the metal cutting or machining of components of the semi-finished product can indicate machining methods such as turning, milling, boring, sawing, and / or grinding by removing excess raw material or material in the form of chips to turn the raw material or material into the desired form.

[0034] In some cases, the machining in process 14 can be carried out without using a cooling lubricant or another liquid. The selected material can be dried.

[0035] Optionally, method 10 may further include an additional process 16 for manufacturing a semi-finished product. Temporally, process 16 may be prior to process 12. The manufacture of the semi-finished product may include forming a rod from an aluminum alloy. In some cases, alternatively, the manufacture of the semi-finished product may also include forming a tube. Additionally or alternatively, in some exemplary embodiments, the manufacture of the semi-finished product in process 16 includes forming a tube from a rod. For example, the rod may be extruded. For example, the tube may be drawn from the rod. In some cases, the tube material may have a higher strength than the strength of the rod product.

[0036] Furthermore, in an additional process 18, the method may include subjecting the tube already manufactured from the rod to a T6 heat treatment. Because the heat treatment occurs, the material AA2618 may receive the following mechanical properties: a tensile strength R of at least 420 MPa m and a yield strength R of at least 340 MPa p0.2 , an A5 elongation of 7% and a minimum fatigue strength of 110 MPa.

[0037] These values apply to a 10% failure probability for 107 cycles of resistance to alternating rotating bending stress. In comparison, different heat treatments (e.g., T0 heat treatment) will only result in lower strength and a larger A5 elongation.

[0038] The T6 heat treatment may include, for example, a duplex sequence of solution / water-solid quenching followed by aging / air-cooling, or consist entirely of these. Optionally, the T6 heat treatment may also include solution annealing, quenching, and artificial aging, or consist entirely of these. Thus, after extrusion, the material may have other mechanical properties. In a manner similar to the variation of extrusion parameters, the variation may be too high. The relationship between temperature reduction and extrusion speed may determine the mechanical properties. Therefore, these also depend on the extruder and its machine capabilities. In some cases, the mechanical properties may be changed in a desired direction by heat treatment.

[0039] Additionally or alternatively, in process 20, method 10 may include riveting a plurality of rolling bearing cage segments. AA2618 can be riveted, which is a very important feature for some cage types. Thus, in some exemplary embodiments, a rolling bearing cage can be assembled from individual parts. Here, the individual parts or rolling bearing cage segments can be, for example, the bridge 5 or the side ring 7 as depicted in Figure 1 In addition, the individual parts can also be segments of the side ring 7, flanges, segments of the bridge 5, and / or rolling bearing cage segments that include at least one bridge and at least one additional segment (e.g., a segment of the side ring).

[0040] In an exemplary embodiment of method 10 for manufacturing a rolling bearing cage 1, the aluminum alloy AA2618 is formed into a bar, for example, an extruded bar. Then a tube is drawn from the bar. This can be referred to as the manufacture of a semi-finished product in process 16. Since it is formed into a tube, the strength of the material may perhaps be increased. Subsequently, in process 18, the tube is subjected to a T6 heat treatment. Since the heat treatment is only performed after being formed into a tube, in some exemplary embodiments, the forming itself can occur better. Subsequently, in process 14, the tube (which can also be referred to as tube material) is dry turned and / or milled. Thus, in some exemplary embodiments, the cage can obtain its geometry with the least possible contamination of the tool, workpieces, and the environment.

[0041] In the present application, all features of the rolling bearing cage disclosed in context can also be implemented in the rolling bearing cage segments.

[0042] For the implementation of the exemplary embodiments in their various design options, the exemplary embodiments and their respective features disclosed in the above description, the following claims, and the drawings can be meaningful and can be implemented individually and in any combination.

[0043] In some additional exemplary embodiments, features disclosed as device features in other exemplary embodiments can also be implemented as method features.

[0044] Furthermore, optionally, features implemented as method features in some exemplary embodiments can also be implemented as device features in other exemplary embodiments.

Claims

1. A rolling bearing cage, comprising aluminum alloy AA2618, wherein the rolling bearing cage is for a gas turbine engine; The aluminum alloy AA2618 has a tensile strength R of at least 420 MPa m , the aluminum alloy AA2618 has a yield strength R0.2 of at least 340 MPa p , the aluminum alloy AA2618 has a hardness of at least 120 HBW, and the aluminum alloy AA2618 has a minimum fatigue strength of 110 MPa.

2. A rolling bearing cage or a rolling bearing cage segment, comprising: A first side ring or a first side ring segment, formed of aluminum alloy AA2618; A second side ring or a second side ring segment, formed of aluminum alloy AA2618; And At least one bridge, formed of aluminum alloy AA2618, the at least one bridge connecting the first side ring to the second side ring, or connecting the first side ring segment to the second side ring segment; The rolling bearing cage is for a gas turbine engine; The aluminum alloy AA2618 has a tensile strength Rm of at least 420 MPa, the aluminum alloy AA2618 has a yield strength Rp0.2 of at least 340 MPa, the aluminum alloy AA2618 has a hardness of at least 120 HBW, and the aluminum alloy AA2618 has a minimum fatigue strength of 110 MPa.

3. The rolling bearing cage or rolling bearing cage segment according to claim 2, characterized in that, The rolling bearing cage is entirely formed of AA2618.

4. The rolling bearing cage or rolling bearing cage segment according to claim 2, characterized in that, The rolling bearing cage comprises a plurality of the rolling bearing cage segments joined together by rivets.

5. A method of manufacturing the rolling bearing cage according to claim 1 or the rolling bearing cage or the rolling bearing cage segment according to any one of claims 2 to 4, comprising: Providing a body from aluminum alloy AA2618; And Forming the body into a rolling bearing cage or forming the body into a rolling bearing cage segment, the rolling bearing cage comprising a first side ring, a second side ring and a plurality of bridges connecting the first side ring to the second side ring, the rolling bearing cage segment comprising a first side ring segment, a second side ring segment and at least one bridge connecting the first side ring segment to the second side ring segment.

6. The method according to claim 5, characterized in that, The body is a semi-finished body, and the forming step comprises machining the semi-finished body.

7. According to the method of claim 6, the machining is performed in a dry state.

8. The method according to claim 6, characterized in that The step of providing the body comprises forming a bar of aluminum alloy AA2618 into a tube.

9. The method according to claim 8, wherein The method further comprises performing a T6 heat treatment on the tube.

10. The method according to claim 5, wherein The method further comprises performing a T6 heat treatment on the body, or performing a T6 heat treatment on the bearing cage or on the bearing cage segment.

11. The method according to claim 5, characterized in that, The step of forming the body into a rolling bearing cage comprises forming a plurality of the bearing cage segments and riveting the plurality of bearing cage segments together.

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