Metal additive manufacturing bearing retainer of lattice topology non-uniform gradient porous structure and machining method of metal additive manufacturing bearing retainer

Abstract

The invention discloses a metal additive manufacturing bearing retainer of a lattice topology non-uniform gradient porous structure and a machining method of the metal additive manufacturing bearing retainer, belongs to the field of bearing retainer design, and aims to solve the problems of unreasonable porous structure distribution, limited mechanical properties and surface frictional wear in the prior art. The retainer body is an annular retainer body, a plurality of pockets used for containing rolling bodies are machined in the outer circle face of the retainer body at equal intervals in the circumferential direction, the retainer body is of a non-uniform gradient porous structure prepared in a metal additive manufacturing mode, and the area, large in stress and serious in abrasion, in the retainer body is a high-stress area. A non-bearing area in the retainer body is a light-weight area, the porosity of a high-stress area is low, the porosity of the light-weight area is high, a transition area is arranged between the high-stress area and the light-weight area, and the porosity of the transition area is arranged from the low porosity to the high porosity in a smooth gradient mode. The bearing retainer is mainly light in weight and reasonable in structural design.

Description

Technical Field

[0001] This invention relates to the field of bearing cage design, specifically to a metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology and its processing method. Background Technology

[0002] As one of the main components of a bearing, the bearing cage plays a crucial role in guiding the movement of rolling elements, preventing rolling element detachment, and evenly distributing the rolling element load during bearing operation. Traditional bearing cages are usually solid metal structures with a large mass. At high speeds, this large mass and high moment of inertia can easily generate significant centrifugal force and inertial torque, leading to increased overall bearing energy consumption, decreased dynamic stability, and potentially causing vibration and noise, thus affecting the bearing's operational accuracy and stability.

[0003] To achieve lightweight design and improve the lubrication performance of bearing cages, the industry is increasingly adopting porous polymer materials to fabricate cages. These cages are typically formed using powder cold pressing-hot sintering or special injection molding processes, creating a three-dimensional interconnected microporous network within them. This network acts as a storage carrier for lubricating oil, achieving self-lubrication. Compared to metal cages, porous polymer cages offer significant advantages such as lower density, higher oil content, better vibration damping and noise reduction properties, and stronger corrosion resistance.

[0004] However, porous polymer cages face severe mechanical performance bottlenecks in practical applications. First, their tensile and shear strengths are significantly lower than those of metallic materials. Under high-speed, high-load conditions, critical stress areas such as the pocket beam and guide surface are prone to plastic deformation or even structural failure. Second, the intrinsic wear resistance of polymers is poor, and continuous contact and friction with rolling elements can easily lead to loss of pocket shape accuracy, thus affecting the rolling element trajectory and exacerbating bearing vibration. Furthermore, the porous structure further weakens the macroscopic mechanical properties of the material, and the polymer matrix has limited temperature resistance, leading to softening and accelerated creep at high temperatures, severely restricting its reliability under extreme conditions.

[0005] In recent years, with the development of additive manufacturing technology, porous structures have been introduced into bearing cage design to achieve weight reduction. Most current metal porous structures are uniformly or regularly distributed. While this achieves weight reduction to some extent, the uniformly distributed pore structure fails to fully consider the differences in stress, temperature, and wear conditions experienced by different areas of the bearing during actual operation. Specifically, the effective load-bearing area decreases due to porosity in high-stress areas such as around the pockets and guide surfaces, making them prone to localized stress concentration, fatigue crack initiation, and early failure.

[0006] In addition, porous structures formed directly by additive manufacturing have a large surface roughness, especially in areas that are in direct contact with the rolling elements, such as the inner wall of the pocket. The porous structure may cause micro-pits, and the unevenness of the surface will aggravate friction and wear, cause stress concentration, increased vibration, and even the peeling off of the rolling elements, affecting the motion accuracy and service life of the bearing.

[0007] Therefore, the existing technology faces the following pressing problems: uniform polymer porous structures struggle to balance lightweight design with the mechanical performance requirements of critical areas; additively manufactured porous structures struggle to achieve the required geometric accuracy and surface quality on precision-fitted surfaces; and there is a lack of a cage design and manufacturing scheme that can achieve integrated optimization of structural performance and function. Therefore, this paper proposes a metal additively manufactured bearing cage with a non-uniform gradient porous structure in its lattice topology. This cage can achieve regional optimization matching of structural strength, motion accuracy, and heat dissipation capacity while reducing mass and inertial forces, and ensures structural reliability through densification treatment of critical contact surfaces. Summary of the Invention

[0008] In order to solve the problems of unreasonable porous structure distribution, limited mechanical properties and surface friction and wear in the prior art, this invention provides a metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology and its processing method.

[0009] A metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology is disclosed. The cage includes a cage body, which is an annular frame. Multiple pockets for accommodating rolling elements are machined at equal intervals along the circumferential direction on the outer circumferential surface of the cage body. The cage body is a non-uniform gradient porous structure prepared by metal additive manufacturing. The areas of the cage body with high stress and severe wear are high-stress areas, and the non-load-bearing areas are lightweight areas. The porosity of the high-stress areas is low, and the porosity of the lightweight areas is high. The area between the high-stress areas and the lightweight areas is a transition area, and the porosity of the transition area is smoothly gradiented from low porosity to high porosity.

[0010] Furthermore, the cage is a round-hole type multi-hole cage or a truss type multi-hole cage;

[0011] Furthermore, the crystal structure of the high-stress region is a Gyroid topology or a Diamond topology, the porosity of the high-stress region is 30%–50%, and the pore size is 0.1 mm–0.3 mm. The crystal structure of the lightweight region is a BCC topology or a Primitive topology, the porosity of the lightweight region is 60%–80%, and the pore size is 0.5 mm–1 mm.

[0012] Furthermore, the inner surface of the pocket is provided with a smooth surface ring along the circumference. The radial width of the smooth surface ring is 0.5mm-2mm, the roundness error of the smooth surface ring is ≤0.01mm, and the surface roughness Ra of the smooth surface ring is ≤0.25μm.

[0013] Furthermore, the smooth surface rings have a nearly fully dense structure;

[0014] Furthermore, the smooth surface ring has a porous structure, with a porosity of <20%;

[0015] A metal additive manufacturing method for a bearing cage with a non-uniform lattice topology gradient porous structure, the method comprising the following steps:

[0016] Step 1: Establish a three-dimensional model of a cage with a gradient porous structure based on the bearing's operating parameters;

[0017] Step 2: Based on the three-dimensional model of the gradient porous structure cage established in Step 1, a semi-finished porous structure cage is manufactured using metal additive manufacturing.

[0018] Step 3: Perform hole finishing on the semi-finished graded porous structure cage obtained in Step 2 and subsequent heat treatment to obtain the finished porous structure cage;

[0019] Step 4: Conduct quality inspection and acceptance of the finished gradient porous structure cage obtained in Step 3;

[0020] Furthermore, the specific steps for establishing a three-dimensional model of the cage with a gradient porous structure based on the bearing's operating parameters in step 1 are as follows:

[0021] Step 1a: Analyze the operating conditions of the bearing and divide the functional areas of the gradient porous structure cage;

[0022] Step 1b: Use design software to create a 3D model of the gradient porous structure cage for the different functional areas defined in Step 1a;

[0023] Step 1c: Integrate and check the 3D model obtained in Step 1b, and use the checked model to plan the additive manufacturing path;

[0024] Furthermore, the specific steps for manufacturing the porous structure cage semi-finished product using metal additive manufacturing in step 2 are as follows:

[0025] Step 2a: Select additive manufacturing equipment and prepare additive manufacturing materials and additive substrates;

[0026] Step 2b: Set the process parameters of the additive manufacturing equipment selected in Step 2a and prepare a gradient porous structure cage semi-finished product using the selected additive material;

[0027] Step 2c: After the gradient porous structure cage semi-finished product in step 2b is prepared, take out the formed workpiece and recover and sieve the unmelted metal powder;

[0028] Furthermore, the specific steps in step 3 for performing hole-filling finishing and subsequent heat treatment on the gradient porous structure cage semi-finished product to obtain the porous structure cage finished product are as follows:

[0029] Step 3a: Remove the obtained gradient porous structure cage semi-finished product from the substrate using wire cutting, and perform preliminary cleaning on the gradient porous structure cage semi-finished product;

[0030] Step 3b: Perform precision machining on the pocket guide surface of the semi-finished gradient porous structure cage after cleaning in step 3a;

[0031] Step 3c: Heat-treat the semi-finished gradient porous structure cage that has undergone precision machining of the pocket guide surface in step 3b to obtain the finished gradient porous structure cage.

[0032] The beneficial effects of this application compared to the prior art are:

[0033] The metal additive manufacturing bearing cage with a non-uniform gradient porous structure and its processing method proposed in this invention achieve breakthrough optimizations in multiple dimensions, including structural design, performance, manufacturing process, and application adaptability, compared to existing technologies. Specific beneficial effects are as follows:

[0034] 1. This application provides a metal additive manufacturing bearing cage with a non-uniform gradient porous structure in its lattice topology. Addressing the significant differences in stress, wear, and temperature across different regions during bearing operation, this non-uniform gradient porous design employs a dense lattice structure with 30%–50% low porosity and small pore sizes of 0.1 mm–0.3 mm in high-stress, high-wear areas such as around the pockets, crossbeams, and guide surfaces. Its high stiffness and wear resistance effectively resist localized stress concentration, fatigue crack initiation, and plastic deformation, solving the problem of insufficient load-bearing capacity in key areas of traditional uniform porous structures. It also achieves lightweighting in areas such as the web and non-load-bearing regions. The region employs a loose lattice structure with 60%–80% high porosity and 0.5mm–1mm large pore size to maximize weight reduction. Compared to traditional solid metal cages, the mass can be reduced by 30%–50%, significantly reducing centrifugal force and inertial torque during high-speed operation and lowering the overall energy consumption of the bearing. At the same time, a transition zone is set between the high-stress zone and the lightweight zone. Through the smooth gradient change of porosity and pore size, stress abrupt changes at the junction of different structural regions are avoided, ensuring the structural integrity of the cage under complex stress conditions, reducing the risk of early failure, and improving the dynamic stability of the bearing under high-speed and high-load conditions.

[0035] The non-uniform gradient porous structure provided in this application not only achieves lightweighting, but its internal three-dimensional interconnected microporous network can also serve as a lubricating oil storage carrier. Combined with the differentiated design of porosity in different regions, high porosity regions can store more lubricating oil, while low porosity and high stress regions can achieve slow penetration of lubricating oil through micropores, forming a continuous and stable lubricating film and improving the lubrication conditions of the friction interface. At the same time, the optimized heat conduction path design of the porous structure allows heat in high-temperature regions to diffuse rapidly through the porous network, improving the heat dissipation capacity of the cage and avoiding material performance degradation caused by local overheating, which is especially suitable for the use requirements under high-temperature conditions.

[0036] 2. This application provides a metal additive manufacturing bearing cage with a non-uniform gradient porous structure in its crystal topology. A smooth surface ring is designed on the inner surface of the pocket. Through a fully dense or ultra-low porosity structure design and subsequent precision machining, the problem of increased friction and wear caused by surface roughness and micro-pits in traditional additive manufacturing porous structures is completely solved. The smooth contact interface reduces the friction coefficient between the rolling elements and the pocket, preventing loss of pocket shape accuracy, ensuring the consistency of the rolling element's trajectory, significantly reducing vibration and noise during bearing operation, and improving operational accuracy. Simultaneously, the metal matrix itself has superior wear resistance compared to polymers. Combined with the design of a dense lattice structure in the high-stress area, the wear resistance of key friction parts such as the pocket edge and guide surface is greatly improved, extending the service life by 2-3 times compared to porous polymer cages. Furthermore, the high-precision machining of the smooth surface ring reduces the risk of scratches and peeling on the rolling element surface, indirectly extending the overall service life of the bearing.

[0037] 3. The present application provides a method for processing a metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology. It adopts an integrated manufacturing route of additive manufacturing, pocket finishing and heat treatment. It fully leverages the advantages of metal additive manufacturing in forming complex internal gradient porous structures and realizing personalized designs. It can accurately control the porosity, pore size and topological configuration of different regions. Furthermore, through subsequent subtractive processing such as wire cutting and precision turning and boring, it ensures the geometric accuracy and surface quality of the smooth surface ring of the pocket. It solves the problem that direct forming by additive manufacturing is difficult to meet the requirements of precision mating surfaces.

[0038] During additive manufacturing, by optimizing process parameters such as laser power, scanning speed, and layer thickness, combined with measures such as powder pretreatment and inert gas protection in the forming chamber, the forming quality of the gradient porous structure is ensured. The recycling, sieving, and reuse of unmelted metal powder reduces material loss. The smooth surface ring provides two design options: fully dense and ultra-low porosity, which can be flexibly selected according to working conditions and manufacturing costs, balancing economic efficiency while ensuring performance.

[0039] Subsequent vacuum heat treatment effectively eliminates the internal stress generated during additive manufacturing and machining. Through solution treatment and aging treatment, the microstructure of the metal material is optimized, enabling the cage to achieve excellent strength, toughness and creep resistance while maintaining its lightweight advantage, thus meeting the reliability requirements under extreme working conditions.

[0040] 4. This application provides a method for processing a metal additive manufacturing bearing cage with a non-uniform gradient porous structure in crystal topology. The temperature resistance of the metal matrix is ​​far superior to that of the polymer. Combined with the heat dissipation design of the gradient porous structure and the mechanical strengthening of the high-stress area, the cage can be adapted to extreme working conditions such as high temperature, high speed, and high load. This breaks through the application limitations of porous polymer cages in high temperature and high load scenarios and can be widely used in high-end equipment fields such as aerospace, high-speed machine tools, and new energy vehicle transmission systems. Based on the specific working parameters of the bearing, the functional areas are divided through finite element simulation analysis, and the personalized design of the porous structure is realized by combining 3D modeling software. The porosity distribution, pore size and topology can be quickly adjusted for bearings of different models and working conditions to meet diverse bearing design needs and improve the product customization service capability.

[0041] This application achieves multiple goals of lightweight, high strength, low wear, and high precision in bearing cages through structural design innovation and manufacturing process optimization. It solves the core problems in existing technologies, such as difficulty in balancing structural performance, poor surface quality, and limited adaptability to operating conditions. It significantly improves the operating stability, service life, and overall performance of bearings, and has important engineering application value and market prospects. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of the cage described in this application (round hole type multi-hole cage);

[0043] Figure 2 This is a schematic diagram of the structure of the cage described in this application (truss-type perforated cage).

[0044] Figure 3 This is a schematic diagram of the crystal structure (Gyroid topology) of the high-stress region in the cage described in this application.

[0045] Figure 4 This is a schematic diagram of the crystal structure (Diamond topology) of the high-stress region in the cage described in this application.

[0046] Figure 5 This is a partially enlarged cross-sectional view of the gradient porous structure in the cage described in this application;

[0047] Figure 6 This is a schematic diagram illustrating the principle of the gradient porous structure in the cage described in this application;

[0048] In the diagram: 1. Cage body, 2. Pocket, 3. High stress zone, 4. Lightweight zone, 5. Smooth surface ring, and 6. Transition zone. Detailed Implementation

[0049] Specific implementation method one: Combining Figures 1 to 6 This embodiment describes a metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology. The cage includes a cage body 1, which is an annular frame. Multiple pockets 2 for accommodating rolling elements are equidistantly machined along the circumferential direction on the outer circumferential surface of the cage body 1. The cage body 1 is characterized by being a non-uniform gradient porous structure prepared by metal additive manufacturing. The areas of the cage body 1 subjected to high stress and severe wear are high-stress regions 3, and the non-load-bearing regions are lightweight regions 4. The high-stress region 3 has low porosity, the lightweight region 4 has high porosity, and a transition region 6 exists between the high-stress region 3 and the lightweight region 4. The porosity of the transition region 6 is smoothly gradientd from low to high porosity.

[0050] The metal additive manufacturing bearing cage with a non-uniform gradient porous structure provided in this embodiment can be a circular hole type porous cage or a truss type porous cage. Through metal additive manufacturing, the hole shape, hole diameter, and porosity in the gradient porous structure can be precisely controlled. When designing the cage, it can be further subdivided into a high-stress zone 3, a lightweight zone 4, and a transition zone 6 according to the different load-bearing capacities of the bearing under operating conditions. The high-stress zone 3 is located around the cage pockets, crossbeams, guide surfaces, and other areas with high stress and severe wear. The porosity in the high-stress zone 3 can be designed to be 30%–50%, and the hole diameter to be 0.1mm–0.3mm. Simultaneously, the high-stress zone 3… The crystal structure is relatively dense, and a Gyroid or Diamond topology can be used to ensure sufficient mechanical strength, stiffness and wear resistance. The lightweight region 4 is located in the web, non-load-bearing area and other parts of the cage. The porosity in the lightweight region 4 can be designed to be 60%-80% and the pore size can be designed to be 0.5mm-1mm. At the same time, the crystal structure of the lightweight region 4 is relatively loose, and a BCC or Primitive topology can be used to achieve maximum weight reduction. The transition region 6 is between the high-stress region 3 and the lightweight region 4. A smooth transition function is set to achieve a smooth gradient transition of porosity and pore size to avoid stress concentration.

[0051] The non-uniform gradient porous metal bearing cage provided in this embodiment achieves an optimized spatial distribution of porosity, pore size, and topological configuration based on the stress conditions of different parts of the bearing through metal additive manufacturing processes. This allows the cage to be lightweight while ensuring the mechanical performance of key components.

[0052] Specific Implementation Method Two: Combining Figures 1 to 6This embodiment differs from specific embodiment one in that the inner surface of the pocket 2 is provided with a smooth surface ring 5 along the circumference. The radial width of the smooth surface ring 5 is 0.5mm-2mm, the roundness error of the smooth surface ring 5 is ≤0.01mm, and the surface roughness Ra of the smooth surface ring 5 is ≤0.25μm. Other components and connection methods are the same as in specific embodiment one.

[0053] In this embodiment, a smooth surface ring 5 is innovatively added to the inner wall of the solid pocket, avoiding the problems of micro-stress concentration and poor surface integrity that exist when the gradient porous structure is used as a friction pair. This ensures the smoothness, low noise, and high precision of the rolling element movement, and extends the service life of the cage and the rolling element. The smooth surface ring 5 can be designed in two ways depending on the manufacturing cost and working conditions: one is a near-fully dense structure with extremely low surface roughness, which can maximize the smoothness of the guide surface of the smooth surface ring 5; the other is a porous structure with ultra-low porosity (porosity <20%). The surface roughness of this structure is not as good as that of the near-fully dense structure, but it can still meet the requirements of smooth rolling element movement and low noise. At the same time, the manufacturing materials of the ultra-low porosity porous structure are lower than those of the near-fully dense structure, which has better economic benefits.

[0054] Specific implementation method three: Combining Figures 1 to 6 This embodiment describes a method for fabricating a metal additive manufacturing bearing cage with a non-uniform gradient porous structure in crystal topology. The method is implemented through the following steps:

[0055] Step 1: Establish a three-dimensional model of a cage with a gradient porous structure based on the bearing's operating parameters;

[0056] Step 1a: Analyze the operating conditions of the bearing and divide the functional areas of the gradient porous structure cage;

[0057] The bearing's operating conditions include the bearing's design speed, expected load (radial and axial), operating temperature range, and lubrication conditions. These operating conditions are input into finite element analysis software to perform static, dynamic, and thermal distribution simulations on the cage. ABAQUS can be used as the finite element analysis software to accurately identify high-stress areas (such as rolling element contact areas and pocket edges), high-wear areas, and high-temperature areas. Based on the simulation results, the cage is divided into different functional areas: high-strength area, lightweight area, and transition area.

[0058] Step 1b: For the different functional regions divided in Step 1a, a three-dimensional model of the gradient porous structure cage is created using design software. In this step, TPMS (Triple Period Minimal Surface) professional lattice design software or three-dimensional structure design software (such as nTop, Solidworks) is used to design a non-uniform gradient porous structure. In the high-stress region, a lattice structure with low porosity, small pore size, and high stiffness is designed. In the lightweight region, a lightweight lattice structure with high porosity and large pore size is designed. In the transition region, a smooth transition function is set between different regions to achieve a smooth gradient transition of porosity and pore size to avoid stress concentration. The pocket surface is reinforced. On the inner surface of the cage pocket, an annular region is designed with extremely low porosity (<20%) or near-completely dense porosity, and a machining allowance of 0.1-0.3 mm is reserved radially to allow for subsequent finishing to create a smooth surface and ensure smooth guidance of the rolling elements.

[0059] Step 1c: Integrate and check the 3D model obtained in Step 1b, and use the checked model to plan the additive manufacturing path. Integrate the overall 3D model of the gradient porous structure, dense ring and cage by Boolean operation to form an integrated 3D digital model, and check for model errors. Under the premise of ensuring that the model is error-free, slice and plan the path. Import the final 3D model into the operating software of the additive manufacturing equipment, slice it, set the layer thickness (20-60μm), generate the laser scanning path, and optimize the design of the support structure.

[0060] Step 2: Based on the three-dimensional model of the gradient porous structure cage established in Step 1, a semi-finished porous structure cage is manufactured using metal additive manufacturing.

[0061] Step 2a: Select additive manufacturing equipment and prepare additive manufacturing materials and additive substrates;

[0062] Additive manufacturing equipment typically employs high-precision selective laser melting (SLM) equipment. The additive material is a high-temperature alloy metal powder with good sphericity and uniform particle size distribution, such as Inconel 718 or Ti6Al4V. Before additive processing, the powder needs to be dried in a vacuum drying oven at 80-120℃ for 2-4 hours to remove moisture. The substrate is an alloy substrate compatible with the powder material, and its surface flatness is checked and cleaned.

[0063] Step 2b: Set the process parameters of the additive manufacturing equipment selected in Step 2a and prepare a gradient porous structure cage semi-finished product using the selected additive material:

[0064] The forming chamber is environmentally controlled by evacuating it to <1.0×10⁻² mbar and filling it with a high-purity inert protective gas, such as argon, to reduce the oxygen content to a safe level, typically below 100 ppm. Processing parameters are then set, with optimized laser power, scanning speed, and scanning spacing determined based on material properties and structural characteristics. The equipment then lays powder layer by layer, selectively melts, and cools and solidifies it according to the slice data, ultimately forming a cage blank with a complex internal gradient porous structure and dense pocket rings in one piece.

[0065] Step 2c: After the gradient porous structure cage semi-finished product in step 2b is prepared, take out the formed workpiece and recover and sieve the unmelted metal powder;

[0066] Step 3: Perform hole finishing on the semi-finished graded porous structure cage obtained in Step 2 and subsequent heat treatment to obtain the finished porous structure cage;

[0067] Step 3a: Remove the obtained gradient porous structure cage semi-finished product from the substrate using wire cutting, and perform preliminary cleaning on the gradient porous structure cage semi-finished product;

[0068] In this step, a slow wire EDM machine is used to separate the formed cage blank from the substrate, with a cutting allowance of about 1-2 mm. Air pressure sandblasting and ultrasonic cleaning (using ethanol or acetone solution) are used to thoroughly remove the unmelted powder adhering to the surface and inside the holes of the blank.

[0069] Step 3b: Perform precision machining on the pocket guide surface of the semi-finished gradient porous structure cage after cleaning in step 3a;

[0070] In this step, a special expansion mandrel or vacuum fixture is designed for the cage to ensure positioning accuracy and stability on a five-axis machining center. The precision machining of the pocket guide surface is carried out using CNC finishing. On a precision CNC machine tool (such as a precision machining center), polycrystalline diamond (PCD) tools are used to finish turning or boring the low porosity ring on the inner surface of the pocket in the semi-finished product of the gradient porous structure cage. A process strategy of small depth of cut, high speed, and slow feed is adopted, and it is carried out in two steps: roughing (removing most of the excess material) and finishing (ensuring the final dimensions and surface finish). After the ring is finished, the surface ripples and excess material formed during additive printing are removed, and a roundness tester and a surface roughness tester are used to check to ensure that the geometric accuracy, dimensional tolerance and surface roughness of the pocket meet the design requirements.

[0071] Step 3c: The semi-finished gradient porous structure cage, after precision machining of the guide surface in step 3b, is subjected to heat treatment to obtain the finished gradient porous structure cage.

[0072] In this step, the finished cage is placed in a vacuum heat treatment furnace and heated at a fixed rate to a temperature below the solidus. After holding at this temperature for 1-2 hours, it is cooled with the furnace to fully eliminate the internal stress generated during manufacturing and processing. According to the heat treatment specifications of the selected high-temperature alloy, solution treatment and aging treatment are carried out to optimize its microstructure and obtain the required comprehensive mechanical properties (strength, toughness and creep resistance).

[0073] Step 4: Conduct quality inspection and acceptance of the finished gradient porous structure cage obtained in Step 3;

[0074] In this step, the finished gradient porous structure cage is subjected to full-dimensional inspection by coordinate measuring machine and industrial CT scan to detect the molding quality of the internal porous structure. Performance sampling tests are also conducted. After the sampling tests are passed, the surface of the finished product is cleaned and then vacuum-sealed for rust prevention to prevent contamination and oxidation.

[0075] The method for manufacturing a metal additive bearing cage with a non-uniform gradient porous structure in this embodiment adopts an integrated manufacturing route of additive manufacturing, pocket finishing and heat treatment. It fully leverages the advantages of metal additive manufacturing in forming complex internal gradient porous structures and realizing personalized designs, and can precisely control the porosity, pore size and topological configuration of different regions. Furthermore, through subsequent subtractive processing such as wire cutting and precision turning and boring, the geometric accuracy and surface quality of the smooth surface ring of the pocket are guaranteed, which solves the problem that direct forming in additive manufacturing is difficult to meet the requirements of precision mating surfaces. Through the synergistic design of the gradient porous structure and the solid pocket edge, a perfect combination of lightweight and high strength of the bearing cage is achieved, which is particularly suitable for high-end equipment fields such as aerospace.

[0076] The present invention has been disclosed above with preferred embodiments, but it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed structure and technical content to create equivalent embodiments without departing from the scope of the present invention. However, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

[0077] Example:

[0078] This embodiment uses the Inconel 718 high-temperature alloy gradient porous cage for aero-engines as an application background to describe the technical solution of this application in detail:

[0079] Step 1: Establish a three-dimensional model of a cage with a gradient porous structure based on the bearing's operating parameters;

[0080] Step 1a: Analyze the operating conditions of the bearing and divide the functional areas of the gradient porous structure cage;

[0081] The operating conditions of the bearing containing this cage include: bearing design speed dn value ≥ 2.0 × 10⁻⁶. 6 mm·r / min, operating temperature range -54℃ to 350℃, intermittent peak temperature 538℃, lubrication method is a combination of oil injection lubrication and self-lubrication;

[0082] The ANSYS Workbench software was used to perform transient dynamic analysis and steady-state thermal analysis on the solid cage model. The above working condition parameters were input into the software during the analysis.

[0083] The analysis results are as follows: The maximum equivalent stress of the cage is concentrated in the root region where the pocket and the crossbeam connect, reaching 450 MPa; the highest temperature occurs on the guide surface of the pocket, at approximately 280°C. Based on the analysis results, the cage is divided into regions:

[0084] High-stress zone: Within 3mm of the pocket, all crossbeams, connecting bridges, and other critical load-bearing components. High fatigue strength and wear resistance are required.

[0085] Lightweight areas: Non-critical load-bearing parts such as the main body web of the cage and non-connected areas inside the window openings. Minimize weight reduction as much as possible.

[0086] Transition zone: Located between the high-stress zone and the lightweight zone, with a width of approximately 2mm;

[0087] Step 1b: Use design software to create a 3D model of the gradient porous structure cage for the different functional areas defined in Step 1a;

[0088] Parametric modeling was performed using the nTopology platform.

[0089] High-strength region: imparts a lattice structure to Gyroid, with porosity linearly varying from 15% at the root of the pocket to 25% in the middle of the crossbeam, and a pore size of 0.15mm;

[0090] Lightweight region: imparts a BCC lattice structure with a porosity of 70% and a pore size of 1.0 mm;

[0091] Transition zone: The porosity is set to smoothly transition from 25% to 70%, and the pore size is set to transition from 0.15mm to 1.0mm. The topology is smoothly and gradually changed through field-driven mixing of Gyroid and BCC.

[0092] Pocket surface reinforcement design: Create a smooth surface ring with a radial width of 1.2 mm on the inner surface of all pockets, set the porosity of this area to 90% (nearly dense), and reserve a finishing allowance of 0.25 mm inward radial direction;

[0093] Step 1c: Integrate and check the 3D model obtained in Step 1b, and use the checked model to plan the additive manufacturing path;

[0094] Model integration and output: Integrate all structural domains with the outer contour of the cage and export it as an STL file. The total weight of the model is reduced by about 42% compared to the solid cage. Import the 3D model into the operating software of the additive manufacturing equipment, perform slicing, set the layer thickness to 20μm, generate the laser scanning path, and optimize the design of the support structure.

[0095] Step 2: Based on the three-dimensional model of the gradient porous structure cage established in Step 1, a semi-finished porous structure cage is manufactured using metal additive manufacturing.

[0096] Step 2a: Select additive manufacturing equipment and prepare additive manufacturing materials and additive substrates;

[0097] The additive manufacturing equipment uses an EOS M 290 SLM machine. The powder material is Inconel 718 alloy powder with a particle size range of 15-53μm, which meets the ASTM F3055 standard. The substrate is a 316L stainless steel plate. After surface flatness verification and cleaning, it is preheated to 80℃.

[0098] Step 2b: Set the process parameters of the additive manufacturing equipment selected in Step 2a and prepare a gradient porous structure cage semi-finished product using the selected additive material:

[0099] The molding chamber was evacuated and filled with argon gas three times to ensure that the oxygen content was <80ppm;

[0100] The additive manufacturing printing parameters were set as follows: laser power: 280 W; scanning speed: 1000 mm / s; scanning spacing: 0.11 mm; layer thickness: 30 μm; scanning strategy: stripe scan, rotating 67° per layer. The continuous printing time under the above process parameters was approximately 28 hours. The molten pool signal was monitored during the printing process, and the process was stable. After the additive printing was completed, a gradient porous structure cage semi-finished product was obtained.

[0101] Step 2c: After the gradient porous structure cage semi-finished product is prepared in step 2b, it is cooled to below 100°C in the molding chamber, the additively molded workpiece is taken out, and the unmelted metal powder is recovered and sieved.

[0102] Step 3: Perform hole finishing on the semi-finished graded porous structure cage obtained in Step 2 and subsequent heat treatment to obtain the finished porous structure cage;

[0103] Step 3a: Remove the obtained gradient porous structure cage semi-finished product from the substrate using wire cutting, and perform preliminary cleaning on the gradient porous structure cage semi-finished product;

[0104] The retainer blank was separated from the substrate using an Agie Charmilles CUT 2000 slow wire EDM machine, followed by sandblasting (100-mesh white corundum, pressure 0.4 MPa) and two rounds of ultrasonic cleaning (15 minutes each).

[0105] Step 3b: Perform precision machining on the pocket guide surface of the semi-finished gradient porous structure cage after cleaning in step 3a;

[0106] Tooling design: A precision mandrel based on the principle of hydraulic expansion was designed and manufactured with a positioning accuracy of 0.003mm;

[0107] Equipment and cutting tools selection: Machining is performed on a Haas UMC-750 five-axis machining center using a PCD precision boring tool;

[0108] Finishing process parameters: spindle speed 8000 rpm, depth of cut 0.05 mm, feed rate 500 mm / min.

[0109] Processing results: According to the MarForm MMQ 400 roundness tester, the maximum roundness error of all pockets is 0.007mm, and the average Ra value is 0.23μm, which meets the design requirements;

[0110] Step 3c: Heat-treat the semi-finished gradient porous structure cage after the precision machining of the guide surface of the pocket in step 3b to obtain the finished gradient porous structure cage.

[0111] Stress-relief annealing: In a vacuum furnace, the temperature is increased to 1065℃ at 20℃ / min, held for 2 hours, and then cooled to 300℃ in the furnace before being removed and air-cooled.

[0112] Solution treatment and aging: Solution treatment (955℃ / 2h / Oil Quench), followed by standard double aging (718℃ / 8h, Furnace Cool to 621℃ / 8h, Air Cool).

[0113] After stress-relief annealing and solution aging, a gradient porous structure cage is obtained.

[0114] Step 4: Conduct quality inspection and acceptance of the finished gradient porous structure cage obtained in Step 3;

[0115] Dimensions and morphology: Coordinate measuring machine (CMM) measurements showed that all critical dimensions met the drawing requirements. Industrial CT scans confirmed that the internal gradient porous structure was well-formed with no significant defects, and the dense rings were tightly bonded to the porous matrix without delamination.

[0116] Performance testing: Sampled parts were tested on a high-speed bearing test bench at dn=2.2×10 6 After 200 hours of continuous operation under mm·r / min conditions, the temperature rise was 15% lower than that of similar solid cages, the vibration value was reduced by 20%, and the cage structure was intact after disassembly and inspection, with only slight wear on the working surface of the pocket.

[0117] Performance tests show that the non-uniform gradient porous structure cage fabricated using the processing method provided in this application can meet the actual working conditions and is superior to the traditional solid cage structure in terms of vibration damping and temperature resistance.

Claims

1. A metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology, the cage comprising a cage body (1), the cage body (1) being an annular frame, and having a plurality of pockets (2) for accommodating rolling elements machined at equal intervals along the circumferential direction on the outer circumferential surface of the cage body (1), characterized in that: The cage body (1) is a non-uniform gradient porous structure prepared by metal additive manufacturing. The area with high stress and severe wear in the cage body (1) is the high stress area (3). The non-load-bearing area in the cage body (1) is the lightweight area (4). The porosity of the high stress area (3) is low porosity, and the porosity of the lightweight area (4) is high porosity. The area between the high stress area (3) and the lightweight area (4) is the transition area (6). The porosity of the transition area (6) is smoothly gradient from low porosity to high porosity.

2. The metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology according to claim 1, characterized in that: The cage is a round-hole multi-hole cage or a truss-type multi-hole cage.

3. The metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology according to claim 1, characterized in that: The high-stress region (3) has a Gyroid topology or a Diamond topology, and its porosity is 30%–50% with a pore size of 0.1 mm–0.3 mm. The lightweight region (4) has a BCC topology or a Primitive topology, and its porosity is 60%–80% with a pore size of 0.5 mm–1 mm.

4. The metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology according to claim 3, characterized in that: The inner surface of the pocket (2) is provided with a smooth surface ring (5) along the circumference. The radial width of the smooth surface ring (5) is 0.5mm-2mm, the roundness error of the smooth surface ring (5) is ≤0.01mm, and the surface roughness Ra of the smooth surface ring (5) is ≤0.25μm.

5. The metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology according to claim 4, characterized in that: The smooth surface ring (5) has a nearly fully dense structure.

6. The metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology according to claim 4, characterized in that: The smooth surface ring (5) has a porous structure and a porosity of <20%.

7. A method for manufacturing a bearing cage using metal additive manufacturing with a non-uniform gradient porous structure in lattice topology according to any one of claims 1 to 6, characterized in that: The method is implemented through the following steps: Step 1: Establish a three-dimensional model of a cage with a gradient porous structure based on the bearing's operating parameters; Step 2: Based on the three-dimensional model of the gradient porous structure cage established in Step 1, a semi-finished porous structure cage is manufactured using metal additive manufacturing. Step 3: Perform hole finishing on the semi-finished graded porous structure cage obtained in Step 2 and subsequent heat treatment to obtain the finished porous structure cage; Step 4: Conduct quality inspection and acceptance of the finished gradient porous structure cage obtained in Step 3.

8. The method for manufacturing a bearing cage with a non-uniform gradient porous structure in lattice topology using metal additive manufacturing according to claim 7, characterized in that: The specific steps for establishing a three-dimensional model of a cage with a gradient porous structure based on the bearing's operating parameters in step 1 are as follows: Step 1a: Analyze the operating conditions of the bearing and divide the functional areas of the gradient porous structure cage; Step 1b: Use design software to create a 3D model of the gradient porous structure cage for the different functional areas defined in Step 1a; Step 1c: Integrate and check the 3D model obtained in Step 1b, and use the checked model to plan the additive manufacturing path.

9. The method for fabricating a metal additive manufacturing bearing cage with a non-uniform gradient porous structure in lattice topology according to claim 7, characterized in that: The specific steps for manufacturing the porous structure cage semi-finished product using metal additive manufacturing in step 2 are as follows: Step 2a: Select additive manufacturing equipment and prepare additive manufacturing materials and additive substrates; Step 2b: Set the process parameters of the additive manufacturing equipment selected in Step 2a and prepare a gradient porous structure cage semi-finished product using the selected additive material; Step 2c: After the gradient porous structure cage semi-finished product is prepared in step 2b, take out the formed workpiece and recover and sieve the unmelted metal powder.

10. The method for manufacturing a bearing cage with a non-uniform gradient porous structure in lattice topology according to claim 7, characterized in that: The specific steps in step 3 of performing hole-filling finishing and subsequent heat treatment on the semi-finished graded porous structure cage to obtain the finished porous structure cage are as follows: Step 3a: Remove the obtained gradient porous structure cage semi-finished product from the substrate using wire cutting, and perform preliminary cleaning on the gradient porous structure cage semi-finished product; Step 3b: Perform precision machining on the pocket guide surface of the semi-finished gradient porous structure cage after cleaning in step 3a; Step 3c: Heat-treat the semi-finished gradient porous structure cage that has undergone precision machining of the pocket guide surface in step 3b to obtain the finished gradient porous structure cage.

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