Composite oil bearing based on controllable TPMS structural core and additive manufacturing method

Abstract

The invention relates to the technical field of sliding bearing manufacturing, in particular to a composite oil-retaining bearing based on a controllable TPMS structural core and an additive manufacturing method, the composite oil-retaining bearing comprises a protective layer, the TPMS structural core is fixed in an inner hole of the protective layer, and a solid lubricating insert block is arranged in a hole of the TPMS structural core. Compared with a powder sintering bearing, the composite oil bearing provided by the invention has the advantages that the weight is obviously reduced, the communication porosity is greatly improved, the starting friction coefficient is reduced, the sealing reliability is improved, the maintenance period is prolonged, and the batch cost increase is controllable. Through TPMS structure optimization and two implementation modes, the differential requirements of solid lubrication-dominated working conditions and liquid lubrication-dominated working conditions can be met respectively.

Description

Technical Field

[0001] This invention relates to the field of sliding bearing manufacturing technology, and in particular to composite oil-impregnated bearings based on controllable TPMS structure cores and additive manufacturing methods. Background Technology

[0002] Current self-lubricating bearing technology still faces significant bottlenecks in terms of both mechanical and lubrication performance. Traditional powder-sintered liquid oil-impregnated bearings generally suffer from uncontrollable pore morphology, low connectivity, and uneven pore size distribution, resulting in unsatisfactory lubrication. Specifically, increased porosity leads to decreased mechanical properties, while decreased porosity weakens lubrication performance. This mutually restrictive relationship makes it difficult to achieve an ideal balance between oil-impregnation capacity, oil supply stability, and overall load-bearing strength. While solid-embedded bearings possess a certain load-bearing capacity, their lubrication performance also depends on the number of pores; increased pores lead to decreased mechanical properties, while decreased pores weaken lubrication, presenting a similar contradiction. Furthermore, existing solid-liquid composite lubrication schemes are often structurally complex, limiting their practical applications. Therefore, there is an urgent need to develop a new bearing structure that combines high specific strength, compact structure, and customizable performance. Summary of the Invention

[0003] The purpose of this invention is to provide a composite oil-impregnated bearing based on a controllable TPMS structure core and an additive manufacturing method, which can overcome the problems of pore structure defects, uncontrollable pores, and the contradiction between strength and lightweight in traditional powder sintered oil-impregnated bearings.

[0004] The technical solution of the present invention: A composite oil-impregnated bearing based on a controllable TPMS structure core includes a protective layer, the inner hole of which is fixed with a TPMS structure core, and the pores of the TPMS structure core contain solid lubricating inserts.

[0005] Furthermore, the solid lubricant block is made of high-purity graphite or PTFE-graphite composite material.

[0006] Furthermore, the inner hole of the TPMS structural core is fixed with a controllable oil seepage layer.

[0007] Furthermore, the protective layer is made of stainless steel, tin bronze, or titanium alloy.

[0008] Furthermore, the TPMS structural core is made of copper alloy powder or titanium alloy powder.

[0009] Furthermore, the material of the controllable oil seepage layer is stainless steel powder or titanium alloy powder.

[0010] Furthermore, the outer circumference of the controllable oil seepage layer is subjected to micro-arc oxidation or nitriding treatment to form a wear-resistant isolation layer.

[0011] An additive manufacturing method for composite oil-impregnated bearings based on a controllable TPMS structure core is as follows: Step 1: A protective layer is obtained by turning or cutting stainless steel, tin bronze, or titanium alloy tubing; the TPMS structural core is obtained by printing copper alloy powder or titanium alloy powder using metal additive manufacturing equipment. Step 2: Demold the printed TPMS structural core using wire cutting and perform stress-relief annealing; finish the protective layer to ensure its internal hole dimensions and geometric tolerances; bore or grind the internal holes of the TPMS structural core to achieve the specified surface roughness. Step 3: Press the solid lubricant insert into the pores of the TPMS structural core, and then perform ultrasonic cleaning, drying and visual inspection on the TPMS structural core. Step 4: Press the TPMS structural core into the inner hole of the protective layer with an interference fit to form a complete bearing assembly; Step 5: Apply oil to the bearing assembly; Step 6: Drain excess oil from the lubricated bearing assembly and clean and dry the working surfaces to obtain the final product.

[0012] Furthermore, in step 3, the solid lubricant block is made of high-purity graphite or PTFE-graphite composite material; the high-purity graphite or PTFE-graphite composite material block is pressed into the pores of the TPMS structural core by stamping. In step 5, high-temperature grease is applied and filled into the remaining space within the pores of the TPMS structural core of the bearing assembly.

[0013] Furthermore, step 1 also includes: using stainless steel powder or titanium alloy powder to print a controllable oil seepage layer using metal additive manufacturing equipment, and reserving a machining allowance for micro-arc oxidation or nitriding treatment on its outer circle; Step 2 also includes: performing micro-arc oxidation or nitriding treatment on the outer circle of the controllable oil seepage layer, and after the treatment is completed, it needs to be finely ground to the final fit size; Between steps 2 and 3, the following step is also included: pressing the controllable oil seepage layer into the inner hole of the TPMS structural core in an interference fit manner; In step 3, the solid lubricant block is made of high-purity graphite or PTFE-graphite composite material, and the high-purity graphite or PTFE-graphite composite material block is pressed into the pores of the TPMS structural core by stamping. In step 5, the bearing assembly is vacuum impregnated with oil to allow the silicone oil to penetrate into the remaining space in the pores of the TPMS structural core.

[0014] The beneficial effects of this invention are: The rapid development of additive manufacturing technology has created conditions for the preparation of porous materials with high precision and controllable pore structure. Among them, the three-period minimal surface (TPMS) structure, with its regular and controllable pore shape, excellent mechanical properties, and high pore connectivity, has become an ideal topological template for constructing lightweight, high-strength bearing cores. The TPMS structure has a high specific surface area and a highly interconnected pore network, which can effectively store lubricant and continuously release it during friction, maintaining an uninterrupted interfacial oil film. Its continuous curved surface helps guide the uniform flow and rapid penetration of lubricant, thereby significantly reducing the coefficient of friction and wear, achieving efficient and green lubrication. Based on this, this invention introduces the TPMS structure into the bearing load-bearing body, and optimizes its mechanical properties while ensuring structural lightweighting by precisely controlling porosity, wall thickness, and connectivity.

[0015] This invention also has good permeability and oil storage capacity, and can arrange lubrication units in an orderly manner, thereby effectively integrating lubrication function while prioritizing load-bearing performance, fundamentally solving the problem that traditional bearing mechanical performance and lubrication performance are difficult to improve in a coordinated manner.

[0016] In summary, the composite oil-impregnated bearing provided by this invention achieves significant weight reduction, a substantial increase in interconnected porosity, a lower starting friction coefficient, improved sealing reliability, extended maintenance cycles, and controllable increases in batch costs compared to powder-sintered bearings. Through TPMS structural optimization and two implementation modes, it can respectively meet the differentiated needs of solid lubrication-dominated and liquid lubrication-dominated operating conditions. Attached Figure Description

[0017] Figure 1 This is a structural diagram of a type A bearing; Figure 2 This is an exploded view of a type A bearing; Figure 3 This is a sectional view of a type A bearing; Figure 4 This is a structural diagram of a type B bearing; Figure 5 This is an exploded view of a type B bearing; Figure 6 This is a sectional view of a type B bearing; Figure 7 This is a sample image of a TPMS structure core printed using metal 3D printing.

[0018] In the diagram: 1. Protective layer; 2. TPMS structural core; 3. Solid lubricant insert; 4. Controllable oil seepage layer. Detailed Implementation

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] Please see Figures 1-3The present invention provides a first embodiment of a composite oil-impregnated bearing based on a controllable TPMS structure core. This bearing is a solid lubrication type, hereinafter referred to as Type A, and includes a protective layer 1. The inner hole of the protective layer 1 is fixed with a TPMS structure core 2, and the pores of the TPMS structure core 2 have solid lubrication inserts 3.

[0021] The solid lubricating block 3 is made of high-purity graphite or PTFE-graphite composite material.

[0022] The protective layer 1 is made of stainless steel, tin bronze, or titanium alloy.

[0023] The TPMS structural core 2 is made of copper alloy powder or titanium alloy powder.

[0024] The structural parameters of the TPMS core 2, including porosity, wall thickness to unit period ratio, interconnected porosity and permeability, can be adjusted during preparation according to working conditions.

[0025] This Type A bearing is suitable for oil-free or difficult-to-maintain environments such as high-temperature, high-speed micro motors.

[0026] Please continue reading. Figures 4-7 Based on the first embodiment, the present invention provides a second embodiment of a composite oil-impregnated bearing based on a controllable TPMS structural core 2. This bearing is a liquid lubrication type, hereinafter referred to as Type B. The inner hole of the TPMS structural core 2 is fixed with a controllable oil seepage layer 4, which together with the protective layer 1 radially constrains the TPMS structural core 2. The controllable oil seepage layer 4 is a porous structure, and the number of pores can be set according to the working conditions.

[0027] The controllable oil seepage layer 4 is made of stainless steel powder or titanium alloy powder; the outer circle of the controllable oil seepage layer 4 is treated with micro-arc oxidation or nitriding to form a wear-resistant isolation layer.

[0028] This type B bearing is used in applications where oil leakage is required or where lubrication is difficult to provide.

[0029] This invention provides an additive manufacturing method for composite oil-impregnated bearings based on a controllable TPMS structure core, the method being as follows: (1) Type A bearing: Step 1: A protective layer is obtained by turning or cutting stainless steel, tin bronze, or titanium alloy tubing; the TPMS structural core is obtained by printing copper alloy powder or titanium alloy powder using metal additive manufacturing equipment. Step 2: Demold the printed TPMS structural core using wire cutting and perform stress-relief annealing; finish the protective layer to ensure its internal hole dimensions and geometric tolerances; bore or grind the internal holes of the TPMS structural core to achieve the specified surface roughness. Step 3: Press the solid lubricant insert into the pores of the TPMS structural core, and then perform ultrasonic cleaning, drying and visual inspection on the TPMS structural core. Step 4: Press the TPMS structural core into the inner hole of the protective layer with an interference fit to form a complete bearing assembly; Step 5: Apply oil to the bearing assembly; Step 6: Drain excess oil from the lubricated bearing assembly and clean and dry the working surfaces to obtain the final product.

[0030] In step 3, the solid lubricant block is made of high-purity graphite or PTFE-graphite composite material; the high-purity graphite or PTFE-graphite composite material block is pressed into the pores of the TPMS structural core by stamping. In step 5, high-temperature grease is applied to fill the remaining space in the pores of the TPMS structural core of the bearing assembly. Since the solid lubricant block cannot quickly form an oil film in the initial stage of operation, it may cause some damage to the bearing and shaft when rotating. The grease is used to make up for this defect.

[0031] The TPMS core is designed as a high-porosity TPMS core with a Gyroid structure.

[0032] Type A bearings are primarily used in high-temperature, high-speed, and other oil-free or difficult-to-maintain environments. Vacuum impregnation mainly uses silicone oil. In these environments, silicone oil experiences a sharp drop in viscosity and an increase in evaporation at high temperatures, quickly drying out and failing. In contrast, high-temperature grease can maintain its colloidal structure with minimal evaporation loss. Therefore, high-temperature grease is used instead of vacuum impregnation to fill the remaining space within the pores of the TPMS structural core.

[0033] (2) Type B bearing: Step 1: A protective layer is obtained by turning or cutting stainless steel, tin bronze, or titanium alloy tubing; the TPMS structural core is obtained by printing copper alloy powder or titanium alloy powder using metal additive manufacturing equipment. Step 2: Demold the printed TPMS structural core using wire cutting and perform stress-relief annealing; finish the protective layer to ensure its internal hole dimensions and geometric tolerances; bore or grind the internal holes of the TPMS structural core to achieve the specified surface roughness. Step 3: Press the solid lubricant insert into the pores of the TPMS structural core, and then perform ultrasonic cleaning, drying and visual inspection on the TPMS structural core. Step 4: Press the TPMS structural core into the inner hole of the protective layer with an interference fit to form a complete bearing assembly; Step 5: Apply oil to the bearing assembly; Step 6: Drain excess oil from the lubricated bearing assembly and clean and dry the working surfaces to obtain the final product.

[0034] Step 1 further includes: using stainless steel powder or titanium alloy powder to print a controllable oil seepage layer through metal additive manufacturing equipment, and reserving a processing allowance for micro-arc oxidation or nitriding treatment on its outer circle. Step 2 also includes: performing micro-arc oxidation or nitriding treatment on the outer circle of the controllable oil seepage layer, and after the treatment is completed, it needs to be finely ground to the final fit size; Between steps 2 and 3, the following step is also included: pressing the controllable oil seepage layer into the inner hole of the TPMS structural core in an interference fit manner; In step 3, the solid lubricant block is made of high-purity graphite or PTFE-graphite composite material, and the high-purity graphite or PTFE-graphite composite material block is pressed into the pores of the TPMS structural core by stamping. In step 5, the bearing assembly is vacuum impregnated with oil to allow the silicone oil to penetrate into the remaining space in the pores of the TPMS structural core.

[0035] Due to capillary action, silicone oil forms a continuous liquid phase channel in the TPMS structural core and the controllable oil-permeable layer, providing a continuous oil supply. In contrast, high-temperature grease has high viscosity and hardly flows in the micropores, thus failing to provide oil permeation. Therefore, a vacuum impregnation method with grease is used instead of high-temperature lubricant to fill the remaining space within the pores of the TPMS structural core.

[0036] The method of the present invention will be further described below with reference to a specific embodiment: 1. 3D modeling and structural design: Using 3D modeling software (such as ntopology), precise models of the protective layer and the TPMS structural core are constructed. Core design steps include: accurately calculating and setting the interference fit dimensions between the protective layer and the TPMS structural core, as well as the specific assembly guide structure. In the TPMS structural core model, the embedding position, quantity, and size of the solid lubricant inserts are pre-planned, and their pore structure parameters (such as porosity and pore size distribution) are set. Differentiated design is implemented for different types: Type A (solid lubricant-specific type) TPMS structural core adopts a Gyroid-type TPMS structure, which has isotropic and high specific surface area characteristics, beneficial for grease retention and stable release, and is designed with high porosity (e.g., >60%) to maximize grease storage space. The TPMS core of the Type B (liquid lubrication type) adopts a Gyroid-type TPMS structure, which can provide higher stiffness and strength under medium porosity, and is suitable for high load-bearing conditions under liquid lubrication. It is designed with medium porosity (e.g., <60%) to balance oil storage and mechanical strength, and a three-dimensional model of a controllable oil seepage layer is established simultaneously.

[0037] 2. Component fabrication and forming: The TPMS structural core is integrally formed using selective laser melting technology, with titanium alloy powder as the preferred material. The printing process must be carried out under the protection of high-purity argon gas, and key process parameters such as laser power and scanning speed must be precisely controlled to ensure the integrity of the lattice structure and that the porosity meets the design tolerances.

[0038] The protective layer is made of stainless steel, tin bronze or titanium alloy tubing, which is machined to near the final size by precision CNC turning or slow wire cutting. The surface roughness of the inner hole that mates with the TPMS structural core needs to be controlled within a certain range to ensure the quality of the interference fit.

[0039] For the controllable oil seepage layer metal 3D fabrication of type B bearings, its outer circular surface needs to reserve a single-sided machining allowance for subsequent surface strengthening treatment. After micro-arc oxidation treatment to generate a layer with a thickness and microhardness exceeding that of the dense ceramic layer, precision grinding is then used to finally control the dimensional accuracy and surface roughness within the required accuracy to ensure precise fit with the TPMS structural core.

[0040] 3. Precision post-processing: The additively manufactured TPMS structural core is removed from the substrate via wire cutting to release internal stress. The inner bore of the TPMS structural core is then precision-machined (e.g., precision grinding) to achieve the target surface roughness, providing a good fit for the insertion of solid lubricating inserts. The protective layer is then precision-machined to the final dimensions specified in the design drawings. For special treatment of type B bearings: the outer circumference of the controllable oil seepage layer undergoes micro-arc oxidation or gas nitriding to generate a uniformly thick, high-hardness, and strongly bonded ceramic or nitride wear-resistant isolation layer. After treatment, this layer must be precision-ground to the final fit dimensions.

[0041] 4. Solid lubricant insert assembly: Pre-fabricated high-purity graphite or PTFE-graphite composite material blocks are precisely pressed into the pre-set holes in the TPMS structural core using a stamping method. After pressing, the components are cleaned using ultrasonic cleaning equipment to thoroughly remove processing residues and impurities. They are then dried and visually inspected to ensure there are no cracks or damage.

[0042] 5. Overall assembly: The TPMS structural core, with its pre-assembled solid lubricant insert, is pressed into the inner hole of the protective layer with a certain interference fit, forming a tight composite structure. For type B bearings, the controllable oil seepage layer must first be installed into the inner hole of the TPMS structural core before this step. The mating surfaces between the two can be designed with fine-pitch threads or elastic snap-fit ​​connections to facilitate future disassembly and maintenance, ultimately forming a three-layer assembly of "protective layer - TPMS structural core - controllable oil seepage layer".

[0043] 6. Differentiated lubrication treatment: Type A bearing treatment: A special pressurized grease injection device is used to force polyurea-based high-temperature grease into the pores of the TPMS structure.

[0044] Type B bearing treatment: Place the entire bearing assembly in a vacuum oil impregnation device and inject silicone oil. Then start the device, vacuum and maintain pressure for 20-40 minutes to allow the silicone oil to fully penetrate into every interconnected pore of the TPMS structure under pressure difference. After oil impregnation, remove the bearing and wipe the outer surface and end faces clean.

[0045] 7. Performance Testing and Application: Comprehensive performance testing is conducted on finished bearings, including but not limited to dimensional accuracy, oil content, crush strength, coefficient of friction, and durability testing.

[0046] Both types of bearings utilize optimized TPMS matrix structure design to achieve efficient synergy between solid lubrication and liquid lubrication during startup and operation, resulting in significantly superior overall performance compared to traditional products.

[0047] The TPMS core is not limited to the Gyroid structure, but may also adopt other three-period minimal surface (TPMS) structures, including but not limited to one or more combinations of Diamond, Primitive, I-WP and other TPMS structures.

[0048] The unit structure of the TPMS core in this invention adopts the Gyroid structure, but it is not limited to this. Other structures such as Lidinoid, Diamond, and Schwarz, as well as their variations, are also within the scope of this invention.

[0049] The above description is only a preferred embodiment of the present invention and should not be construed as a limitation of this application. All equivalent changes and modifications made in accordance with the scope of the patent application of the present invention should be covered by the present invention.

Claims

1. A composite oil-impregnated bearing based on a controllable TPMS structure core, characterized in that, It includes a protective layer, the inner hole of which is fixed with a TPMS structural core, and the pores of the TPMS structural core contain solid lubricating inserts.

2. The composite oil-impregnated bearing based on a controllable TPMS structure core according to claim 1, characterized in that, The solid lubricant block is made of high-purity graphite or PTFE-graphite composite material.

3. The composite oil-impregnated bearing based on a controllable TPMS structure core according to claim 2, characterized in that, The inner hole of the TPMS structural core is fixed with a controllable oil seepage layer.

4. The composite oil-impregnated bearing based on a controllable TPMS structure core according to claim 2 or 3, characterized in that, The protective layer is made of stainless steel, tin bronze, or titanium alloy.

5. The composite oil-impregnated bearing based on a controllable TPMS structure core according to claim 1, characterized in that, The TPMS structural core is made of copper alloy powder or titanium alloy powder.

6. The composite oil-impregnated bearing based on a controllable TPMS structure core according to claim 3, characterized in that, The controllable oil seepage layer is made of stainless steel powder or titanium alloy powder.

7. The composite oil-impregnated bearing based on a controllable TPMS structure core according to claim 3, characterized in that, The outer circumference of the controllable oil seepage layer is treated with micro-arc oxidation or nitriding to form a wear-resistant isolation layer.

8. An additive manufacturing method for composite oil-impregnated bearings based on a controllable TPMS structure core, characterized in that, The method for manufacturing the composite oil-impregnated bearing based on a controllable TPMS structure core as described in any one of claims 1-7 is as follows: Step 1: A protective layer is obtained by turning or cutting stainless steel, tin bronze, or titanium alloy tubing; the TPMS structural core is obtained by printing copper alloy powder or titanium alloy powder using metal additive manufacturing equipment. Step 2: Demold the printed TPMS structural core using wire cutting and perform stress-relief annealing; finish the protective layer to ensure its internal hole dimensions and geometric tolerances; bore or grind the internal holes of the TPMS structural core to achieve the specified surface roughness. Step 3: Press the solid lubricant insert into the pores of the TPMS structural core, and then perform ultrasonic cleaning, drying and visual inspection on the TPMS structural core. Step 4: Press the TPMS structural core into the inner hole of the protective layer with an interference fit to form a complete bearing assembly; Step 5: Apply oil to the bearing assembly; Step 6: Drain excess oil from the lubricated bearing assembly and clean and dry the working surfaces to obtain the final product.

9. The additive manufacturing method for a composite oil-impregnated bearing based on a controllable TPMS structural core according to claim 5, wherein in step 3, the solid lubrication block is made of high-purity graphite or PTFE-graphite composite material; the high-purity graphite or PTFE-graphite composite material block is pressed into the pores of the TPMS structural core by stamping. In step 5, high-temperature grease is applied and filled into the remaining space within the pores of the TPMS structural core of the bearing assembly.

10. The additive manufacturing method for a composite oil-impregnated bearing based on a controllable TPMS structure core according to claim 5, wherein step 1 further comprises: A controllable oil-permeable layer is obtained by printing stainless steel powder or titanium alloy powder using metal additive manufacturing equipment, and a machining allowance for micro-arc oxidation or nitriding treatment is reserved on its outer circle. Step 2 also includes: performing micro-arc oxidation or nitriding treatment on the outer circle of the controllable oil seepage layer, and after the treatment is completed, it needs to be finely ground to the final fit size; Between steps 2 and 3, the following step is also included: pressing the controllable oil seepage layer into the inner hole of the TPMS structural core in an interference fit manner; In step 3, the solid lubricant block is made of high-purity graphite or PTFE-graphite composite material, and the high-purity graphite or PTFE-graphite composite material block is pressed into the pores of the TPMS structural core by stamping. In step 5, the bearing assembly is vacuum impregnated with oil to allow the silicone oil to penetrate into the remaining space in the pores of the TPMS structural core.

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