A cross-roller bearing

Abstract

The application relates to the technical field of precision machinery transmission, in particular to a cross roller bearing. The cross roller bearing is composed of a bearing outer ring, a bearing inner ring and cylindrical rollers, the bearing outer ring is a non-continuous closed circle structure, one or more fracture openings are arranged on the bearing outer ring, and the bearing outer ring is composed of multiple segments of outer rings; the outer ring is made of nodular cast iron or amorphous alloy, and one or more stress grooves are machined before controllable fracture. According to the application, the bearing outer ring is designed as a non-continuous closed circle structure and controllable fracture is realized, bearing assembly is facilitated, and production efficiency and product quality are effectively improved.

Description

Technical Field

[0001] This application relates to the field of precision mechanical transmission technology, and in particular to a crossed roller bearing. Background Technology

[0002] In the field of mechanical transmission, bearings, as core components, play a crucial role in the operation of the entire mechanical system due to their performance and manufacturing process. With the continuous development of industrial technology, the requirements for the precision, stability, and reliability of mechanical equipment are becoming increasingly stringent. The rotational accuracy and rigidity of bearings have become important factors in improving the overall performance of equipment. Crossed roller bearings, as a special type of bearing, are widely used in various precision machinery, robotics, aerospace, and other high-end fields due to their unique design that enables high load capacity and high-precision rotation within a limited space. Improving their performance is of great significance in promoting the development of these industries.

[0003] In the past, for bearings with crossed cylindrical roller structures, a design of integral thin-walled crossed roller bearings with both inner and outer rings was typically used to improve the bearing's rotational accuracy and rigidity. Specifically, a mounting hole was created in the middle of the outer diameter surface of the outer ring to accommodate the rollers. To ensure assembly stability, a mounting plug was fitted tightly into the mounting hole. A through hole was created laterally in the mounting plug to position it, and a locating pin was inserted into this hole. This method was the standard approach for solving the assembly and positioning problems of crossed roller bearings at the time, and it met the needs of certain applications to some extent.

[0004] However, this existing technology has significant drawbacks. To ensure high positioning accuracy of the assembly plug, the machining precision of the assembly plug needs to be significantly improved, which undoubtedly increases equipment and manufacturing costs. Furthermore, although the assembly plug is formed together with the raceway, it must be removed before the rollers are assembled. After the rollers are installed, the assembly plug is then put back in place. During this process, the axial and radial errors between the V-groove and the V-raceway below the assembly plug are difficult to accurately locate, causing the rollers to run unevenly in the raceway, affecting product performance and lifespan. Additionally, because the mounting holes for assembling the rollers are too small, and two adjacent rollers in a crossed roller bearing must be arranged in a cross shape, automated assembly is not possible, requiring manual loading, resulting in low assembly efficiency and high costs. Summary of the Invention

[0005] The purpose of this application is to provide a crossed roller bearing.

[0006] The above-mentioned technical objective of this application is achieved through the following technical solution: a crossed roller bearing, comprising an outer ring, an inner ring, and cylindrical rollers; the inner circumferential surface of the outer ring and the outer circumferential surface of the inner ring are both machined with a plurality of roller grooves adapted to the cylindrical rollers; the inner ring is concentrically mounted on the radially inner side of the outer ring; the cylindrical rollers are arranged in a cross shape in the roller grooves between the inner ring and the outer ring; the outer ring is a discontinuous closed circle, and one or more fracture points are provided on the outer ring.

[0007] By adopting the above technical solution, the bearing outer ring is designed as a discontinuous closed circular structure (segmented through one or more fracture points) and multi-segment structure is formed through controllable fracture. This effectively solves the automated assembly problem caused by the narrow assembly holes in existing integral outer ring crossed roller bearings. Compared to a fixed two-segment structure, it further improves assembly flexibility—the number of fracture points can be flexibly set according to bearing size and load requirements (e.g., one fracture point forming a C-shaped opening structure, or multiple fracture points forming a multi-segment splicing structure), adapting to more scenarios. Utilizing a magnetic tooling base for adsorption and positioning of the cylindrical rollers and elastic auxiliary tools for fixing the spliced ​​outer ring, efficient and precise roller loading and stable outer ring splicing are achieved, significantly improving efficiency. This improves assembly efficiency and reduces labor costs. Furthermore, by utilizing the dense fit and negligible plastic deformation of the fracture surfaces after multi-segment outer ring splicing, it avoids the axial and radial errors caused by the repositioning of plugs in traditional assembly, ensuring the dimensional accuracy of the roller raceways, reducing roller running resistance, and significantly improving the bearing's rotational accuracy, structural rigidity, and service life. In addition, the bearing outer ring adopts material properties adapted for controllable fracture and a stress groove design, ensuring the controllability of the fracture process and the structural stability after splicing, providing reliable technical support for the large-scale application of crossed roller bearings in high-precision transmission scenarios. By machining multiple roller grooves on the inner circumferential surface of the bearing outer ring and the outer circumferential surface of the bearing inner ring, the number and distribution of rollers can be flexibly designed according to the bearing's load-bearing requirements. The coordinated load-bearing capacity of multiple grooves disperses radial force, axial force, and overturning moment, significantly improving the overall load-bearing capacity and deformation resistance of the bearing. At the same time, the independent arrangement of multiple grooves can achieve orderly separation and precise positioning of the cylindrical rollers, avoiding frictional wear or motion interference caused by mutual contact of rollers during high-speed operation, reducing operating noise and energy loss. In addition, the multi-groove structure design allows the bearing to maintain basic transmission performance through the normal operation of other grooves even when minor wear occurs in some rollers or grooves, extending the bearing's service life. It also provides a modular design basis for crossed roller bearings of different precision grades and load-bearing requirements, enhancing the product's adaptability and application flexibility.

[0008] Optionally, the outer ring of the bearing is made of ductile iron or amorphous alloy.

[0009] By adopting the above technical solution, when ductile iron is selected as the material for the bearing outer ring, its advantages of high hardness and brittle fracture characteristics after heat treatment are fully utilized: it ensures the structural strength and wear resistance required for the bearing outer ring roller raceway, meeting the load-bearing capacity requirements of precision transmission scenarios; at the same time, it can precisely fracture along the stress groove during controlled fracture, with minimal plastic deformation at the fracture point, and can restore the initial dimensions after splicing, with a dense and seamless fracture surface, effectively maintaining the dimensional accuracy of the roller raceway. Meanwhile, ductile iron is widely available and has low processing costs, which helps reduce bearing manufacturing costs. Mature and stable heat treatment processes (such as quenching and tempering) can optimize material uniformity, providing a reliable foundation for subsequent processes and improving production stability and economy. When amorphous alloys are selected, their unique structure with disordered atomic arrangement provides high strength, high hardness, and low plasticity. Plastic deformation during fracture is highly controllable, and the fracture surface is clean and with minimal gaps after breaking along a pre-set stress groove. Their absence of grain boundaries also endows the roller raceways with superior surface integrity, reducing raceway friction loss and making them suitable for high-frequency, high-speed, and high-precision transmission scenarios. Furthermore, the flexible molding process of amorphous alloys, combined with injection / die casting and graphene-assisted technology, allows for precise control of the molding accuracy of the outer ring's split structure, reducing subsequent grinding allowances and further improving production efficiency and product performance consistency, thus expanding the application potential of bearings in high-end equipment. These two materials are suitable for different application scenarios and cost requirements, providing diverse and reliable options for bearing design and manufacturing.

[0010] Optionally, the bearing outer ring is a continuous closed circle before controllable fracture, and one or more stress grooves are machined along the circumferential direction on the outer circular surface and / or the two axial end faces; the one or more fracture openings are formed by controllable fracture along the stress grooves, and the bearing outer ring is a discontinuous closed circle after fracture.

[0011] By adopting the above technical solution, stress grooves are machined at one or more preset positions on the outer circular surface and / or axial end face before the controllable fracture of the bearing outer ring. This can accurately guide the fracture position, enabling the bearing outer ring to achieve controllable fracture along a preset path. This avoids irregular cracks or excessive plastic deformation during the fracture process, ensuring that the fracture surfaces of each segment of the outer ring after fracture are regular and have high conformity. At the same time, the stress grooves reduce the tension required for fracture, reduce the load requirements on the fracture tooling, and improve the stability and controllability of the fracture process. Combined with the brittle fracture characteristics of the material, there is almost no plastic deformation at the fracture point. After splicing, the initial dimensional accuracy can be restored, ensuring the continuity and consistency of the roller grooves. This lays the foundation for the smooth operation of the rollers during subsequent assembly. In addition, the standardized fracture path facilitates process uniformity in mass production, improving the efficiency and reliability of machining non-continuous closed circular outer ring structures.

[0012] Optionally, the two semicircular outer rings are provided with unique corresponding splicing marks for precise splicing of the two semicircular outer rings.

[0013] By adopting the above technical solution and setting unique corresponding splicing marks on the two semicircular outer rings, precise alignment of the two semicircular outer rings can be quickly achieved during assembly. This avoids steps or deviations in the roller raceway caused by splicing misalignment, ensuring that the inner roller raceway of the spliced ​​bearing outer ring forms a continuous and complete annular structure, guaranteeing the smooth operation of the cylindrical rollers within the raceway. At the same time, the unique corresponding mark design simplifies the splicing operation process. Whether it is manual or automated assembly, the correct splicing position can be quickly identified through the mark, reducing adjustment time during assembly, improving assembly efficiency, and effectively avoiding part loss or rework caused by mismatch. This further enhances the stability and consistency of the bearing production process, providing a reliable guarantee for quality control in mass production.

[0014] Optionally, the roller raceway surface of the outer ring of the bearing is subjected to high-frequency quenching or surface coating treatment.

[0015] By employing the above-mentioned technical solutions, high-frequency quenching or surface coating treatment of the roller raceway surface of the bearing outer ring can significantly improve the hardness, wear resistance, and fatigue resistance of the raceway surface, effectively reducing frictional loss between the cylindrical rollers and the raceway during high-speed cross-rotation and extending the service life of the bearing. Simultaneously, high-frequency quenching can form a uniform hardened layer on the raceway surface, creating a good strength-toughness match with the toughness of the substrate. Surface coating further optimizes the lubrication performance and corrosion resistance of the raceway surface, adapting to the needs of different working conditions. Furthermore, the surface treatment process can compensate for insufficient material hardness, ensuring that the roller raceway maintains stable dimensional accuracy under long-term load and frequent operation, reducing bearing accuracy degradation caused by raceway wear, thereby improving the reliability and stability of crossed roller bearings in precision transmission scenarios.

[0016] Optionally, a sealing ring may also be included, which is disposed at the axial end between the outer ring and the inner ring of the bearing.

[0017] By adopting the above technical solution, a sealing ring is installed at the axial end between the outer and inner rings of the bearing. This effectively prevents external dust, moisture, impurities, etc., from entering the roller raceways inside the bearing, avoiding wear or jamming of the cylindrical rollers and raceways by contaminants, and ensuring stable operation of the bearing under complex working conditions. At the same time, the sealing ring can reduce the loss of grease inside the bearing, maintain good lubrication between the rollers and raceways, reduce friction loss and extend maintenance cycles, further improving the service life of the bearing. In addition, the installation of the sealing ring can also enhance the axial sealing performance of the bearing. By forming a closed space through tight fit with the inner and outer rings, it reduces the accuracy fluctuations caused by assembly clearances, ensuring that the bearing maintains stable rotational accuracy and structural rigidity during long-term use, and meeting the sealing requirements of high-precision transmission scenarios.

[0018] Optionally, a retainer may also be included for separating and positioning the cylindrical rollers, and the structure of the retainer is adapted to the split design of the outer ring of the bearing to achieve a complete ring or segmented assembly.

[0019] By adopting the above technical solutions and setting a retainer adapted to the split design of the bearing outer ring, the cylindrical rollers can be effectively separated and positioned, avoiding collisions or friction between the rollers during high-speed cross-rotation, reducing wear and noise caused by contact, and improving the smoothness of bearing operation. At the same time, the complete annular or segmented structure design of the retainer, combined with the assembly characteristics of the split outer ring, solves the problem that traditional integral outer ring bearings cannot be equipped with a complete annular retainer. It retains the precise guiding function of the integral annular retainer for the rollers, while the segmented structure adapts to manual or automated assembly scenarios, simplifying the assembly process and ensuring the alignment accuracy of the rollers in the raceway. In addition, the adaptable design of the retainer and the split outer ring allows for visual adjustment of the relative position of the rollers and the retainer during assembly, avoiding assembly misalignment caused by space constraints, further ensuring the continuity of the roller raceway and the rotational accuracy of the bearing, extending the bearing's service life, and providing flexible and reliable structural support for precision transmission requirements under different working conditions.

[0020] In summary, this application has at least the following beneficial effect: 1. By designing the bearing outer ring as a discontinuous closed circular structure (segmented through one or more fracture points) and forming a multi-segment structure through controlled fracture, the automated assembly problem caused by the narrow mounting holes in existing integral outer ring crossed roller bearings is effectively solved. Compared to a fixed two-segment structure, this design further improves assembly flexibility—the number of fracture points can be flexibly set according to bearing size and load requirements (e.g., one fracture point forming a C-shaped opening structure, or multiple fracture points forming a multi-segment splicing structure), adapting to more scenarios. Utilizing a magnetic tooling base for adsorption and positioning of the cylindrical rollers and elastic auxiliary tools for fixing the spliced ​​outer ring, efficient and precise roller loading and stable outer ring splicing are achieved, significantly improving efficiency. This improves assembly efficiency and reduces labor costs. Furthermore, by utilizing the dense fit and negligible plastic deformation of the fracture surfaces after multi-segment outer ring splicing, it avoids the axial and radial errors caused by the repositioning of plugs in traditional assembly, ensuring the dimensional accuracy of the roller raceways, reducing roller running resistance, and significantly improving the bearing's rotational accuracy, structural rigidity, and service life. In addition, the bearing outer ring adopts material properties adapted for controllable fracture and a stress groove design, ensuring the controllability of the fracture process and the structural stability after splicing, providing reliable technical support for the large-scale application of crossed roller bearings in high-precision transmission scenarios. By machining multiple roller grooves on the inner circumferential surface of the bearing outer ring and the outer circumferential surface of the bearing inner ring, the number and distribution of rollers can be flexibly designed according to the bearing's load-bearing requirements. The coordinated load-bearing capacity of multiple grooves disperses radial force, axial force, and overturning moment, significantly improving the overall load-bearing capacity and deformation resistance of the bearing. At the same time, the independent arrangement of multiple grooves can achieve orderly separation and precise positioning of the cylindrical rollers, avoiding frictional wear or motion interference caused by mutual contact of rollers during high-speed operation, reducing operating noise and energy loss. In addition, the multi-groove structure design allows the bearing to maintain basic transmission performance through the normal operation of other grooves even when minor wear occurs in some rollers or grooves, extending the bearing's service life. It also provides a modular design basis for crossed roller bearings of different precision grades and load-bearing requirements, enhancing the product's adaptability and application flexibility.

[0021] 2. By pre-setting one or more stress grooves on the outer ring of the bearing and applying directional tension in conjunction with the fracture expansion fixture, precise and controllable fracture of the outer ring along the stress grooves is achieved. The stress concentration effect ensures a stable fracture path, avoiding irregular cracks or excessive plastic deformation that may occur when fractured without pre-set grooves. This results in high consistency of the fracture surfaces of each outer ring segment after fracture, minimal loss of dimensional accuracy, and restoration of the initial structural integrity after splicing. Simultaneously, the flexible distribution of stress grooves ensures the symmetry and rationality of the discontinuous closed circular structure after fracture, laying the foundation for precise splicing during subsequent assembly. The concentric positioning of the fracture expansion fixture further ensures the stability and consistency of the fracture process. This method is simple to operate and highly controllable, reducing excessive reliance on equipment precision and achieving uniformity of bearing outer ring fracture quality in mass production. It provides key process support for the large-scale manufacturing of cross roller bearings with discontinuous closed circular outer ring structures. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a crossed roller bearing; Figure 2 This is a schematic diagram of the assembly of a crossed roller bearing; Figure 3 This is a flowchart illustrating the steps involved in assembling a crossed roller bearing. Figure 4 This is a schematic diagram of controlled fracture of the outer ring of a bearing; Figure 5 This is a flowchart illustrating the steps of a method for controlling the fracture of the outer ring of a bearing.

[0023] Figure Labels 1. Bearing outer ring; 2. Bearing inner ring; 3. Cylindrical roller; 4. Roller groove; 5. Stress groove; 6. Magnetic fixture holder; 7. Fracture fixture holder. Detailed Implementation

[0024] The present application will be further described in detail below with reference to the accompanying drawings.

[0025] Example 1 In this embodiment, refer to Figures 1-5A crossed roller bearing includes an outer ring 1, an inner ring 2, cylindrical rollers 3, and a sealing ring. The inner circumferential surface of the outer ring 1 and the outer circumferential surface of the inner ring 2 are both machined with several roller grooves 4 adapted to the cylindrical rollers 3. The roller grooves 4 can be designed as single-row or multi-row structures according to the bearing's rigidity requirements. When used in light-load, high-precision applications, a single-row roller groove 4 can be provided, with the cylindrical rollers 3 arranged in a cross pattern. When used in heavy-load, high-rigidity applications, a multi-row (two or more rows) roller groove 4 is preferred. The inner ring 2 is concentrically mounted radially inside the outer ring 1. The cylindrical rollers 3 are arranged in a cross pattern within the roller grooves 4 between the inner ring 2 and the outer ring 1. The sealing ring is located at the axial end between the outer ring 1 and the inner ring 2. This structural design enables the bearing to operate stably, achieving high-precision rotation and load-bearing functions. This is because the cross-shaped arrangement of the rollers in the raceway can effectively distribute the load, improve the rigidity and rotational accuracy of the bearing, while the seal can prevent dust, debris and other contaminants from entering the bearing and ensure the bearing's service life.

[0026] Specifically, the bearing outer ring 1 is a discontinuous closed circular structure with one or more fracture points, composed of multiple outer ring segments spliced ​​together. The bearing outer ring 1 is made of ductile iron or amorphous alloy. Ductile iron, after heat treatment, possesses high hardness and brittle fracture characteristics, making it suitable for manufacturing bearing outer rings 1 that require fracture and reassembly. The special material properties of ductile iron result in minimal plastic deformation during fracture, ensuring that the fractured area recovers its initial dimensions after reassembly, thus guaranteeing the dimensional accuracy of the outer ring raceway. Besides ductile iron, metals with tensile strength ≥800MPa and elongation not exceeding 3% (such as zirconium-based alloys, gallium-based alloys), ceramics, or composite materials can also be used. Amorphous alloys, due to their unique structure of disordered atomic arrangement, also exhibit controllable plastic deformation during fracture, making them suitable for processing this discontinuous closed circular structure. This enriches material options and meets the diverse performance requirements of bearing outer rings under different operating conditions.

[0027] Before controlled fracture, stress grooves 5 are machined at one or more locations along the circumference on the outer circular surface and / or the two axial end faces of the bearing outer ring 1. Each segment of the outer ring is formed by controlled fracture along the stress grooves 5. There are various methods for machining the stress grooves 5, such as wire cutting and laser cutting. Wire cutting is a high-precision machining method that can ensure the dimensional and shape accuracy of the stress grooves 5; laser cutting has the advantage of high processing speed. By machining the stress grooves 5 at these locations, the bearing outer ring 1 can accurately fracture into multiple segments along the location of the stress grooves 5 when subjected to tension. Alternatively, another method of machining and assembling the stress grooves can be used, in which the stress groove 5 is machined only at one point in the circumferential direction before controlled fracture of the bearing outer ring 1. After machining, the outer ring is subjected to a fracture expansion operation, and after fracture, the entire outer ring forms a C-shaped structure. Subsequently, an external force is applied along the single opening to expand it. Utilizing the elastic deformation capability of the outer ring material, the opening is widened to accommodate the rollers, allowing for roller assembly. After assembly, the outer ring, through its own elastic recovery characteristics, can provide stable constraint on the rollers. This method is advantageous in scenarios with specific requirements for ease of assembly. Furthermore, actual assembly tests have shown that bearings assembled using this method meet design requirements for both roller smoothness and overall bearing stability under subsequent simulated operating conditions.

[0028] Each segment of the broken outer ring 1 of the bearing has a unique corresponding splicing mark for precise splicing. These marks can be engravings, numbers, letters, etc., as long as they ensure that the segments of the outer ring can be accurately matched during splicing. For example, "A1" can be engraved on one segment of the outer ring, and "A2" can be engraved on the corresponding segment. By aligning "A1" and "A2" during splicing, precise splicing can be achieved.

[0029] The roller raceway 4 of the outer ring 1 of the bearing is subjected to high-frequency quenching or surface coating treatment. High-frequency quenching can improve the hardness and wear resistance of the roller raceway 4 surface, while surface coating treatment can further improve the performance of the raceway surface, such as reducing the coefficient of friction. For example, a titanium nitride coating can be used for the surface coating, which has good hardness and wear resistance and can effectively improve the service life of the bearing.

[0030] Specifically, the bearing inner ring 2 is concentrically located inside the bearing outer ring 1, and its outer circumferential surface is machined with roller grooves 4 adapted to the cylindrical rollers 3. The bearing inner ring 2 can be made of conventional bearing steel, which has high strength and toughness and can meet the requirements of bearing use. The bearing inner ring 2 can be machined using conventional processes such as forging, turning, and grinding to ensure its dimensional accuracy and surface quality.

[0031] Cylindrical rollers 3 are arranged in a cross shape within the roller groove 4 between the inner ring 2 and the outer ring 1 of the bearing. The cylindrical rollers 3 are typically made of bearing steel, and their surfaces are precision-machined to achieve high dimensional accuracy and surface finish. The size and shape of the cylindrical rollers 3 must be compatible with the roller groove 4 to ensure smooth rolling within the groove.

[0032] A sealing ring is located at the axial end between the outer ring 1 and the inner ring 2 of the bearing. The sealing ring can be made of elastic materials such as rubber or silicone, and its shape is usually annular. The function of the sealing ring is to prevent dust, debris, etc., from entering the bearing, and also to prevent lubricating oil leakage, ensuring the normal operation of the bearing.

[0033] The implementation principle of this embodiment is as follows: The crossed roller bearing of this embodiment adopts a non-continuous closed circular structure for the outer ring 1 and an integral inner ring 2. Utilizing the special properties of ductile iron, one or more fracture surfaces are formed in the outer ring 1 through the machining of stress grooves 5 and controlled fracture. This design solves the problems of difficult positioning accuracy of the assembly plug and low assembly efficiency of the rollers in the prior art. The setting of splicing marks ensures the accuracy of the outer ring splicing, high-frequency quenching or surface coating treatment improves the performance of the roller raceway 4, and the addition of a sealing ring enhances the protective performance of the bearing. These improvements make the bearing assembly more convenient, enabling automated mass production, improving production efficiency, reducing production costs, and ensuring the bearing's precision and service life, representing a significant advancement compared to the prior art.

[0034] Example 2 Reference Figures 2-3 The assembly method of the crossed roller bearing provided in this application includes the following steps: S101: Concentrically mount the bearing inner ring 2 onto the magnetic fixture 6. The magnetic fixture 6 can achieve magnetic adsorption using an electromagnetic chuck or permanent magnet. During operation, carefully place the bearing inner ring 2 onto the magnetic fixture 6, ensuring concentricity. Use the magnetism of the magnetic fixture 6 to fix the bearing inner ring 2 in place, preventing it from moving during subsequent operations.

[0035] S102: The cylindrical rollers 3 are placed sequentially in a cross shape in the roller grooves 4 outside the inner ring 2 of the bearing, using either manual or automated equipment. The cylindrical rollers 3 are magnetically attracted by the magnetic fixture 6 to prevent them from falling out. If placed manually, the operator must place the cylindrical rollers 3 one by one into the roller grooves 4 in a cross-shaped arrangement. If using automated equipment, a robotic arm or similar device can be used, and its movements can be programmed to accurately place the cylindrical rollers 3 in the designated positions. Due to the magnetic effect of the magnetic fixture 6, the cylindrical rollers 3 are attracted within the roller grooves 4 and will not fall out.

[0036] S103: Assemble the segments of the non-continuous closed circular bearing outer ring 1 according to the uniquely corresponding splicing marks, and fit them onto the outer circumference of the bearing inner ring 2 and cylindrical roller 3. During splicing, the operator needs to carefully observe the splicing marks, accurately align each segment of the outer ring, and then slowly fit it onto the outer circumference of the bearing inner ring 2 and cylindrical roller 3.

[0037] S104: An elastic auxiliary tool is fitted onto the outside of the assembled bearing outer ring 1 to maintain the assembled bearing outer ring 1. The auxiliary tool can be a rubber band, plastic ring, etc. By fitting the auxiliary tool onto the outside of the assembled bearing outer ring 1, its elastic contraction force is used to tightly splice the various sections of the outer ring together and prevent them from coming apart.

[0038] S105: Place the assembled bearing outer ring 1, bearing inner ring 2, and cylindrical rollers 3 together in a demagnetizing device for demagnetization. Common AC demagnetizers can be used. Place the assembled bearing into the demagnetizing device and follow the operating instructions to remove magnetism from the bearing and ensure its normal operation.

[0039] The implementation principle of this embodiment is as follows: The assembly method of this embodiment uses a magnetic tooling seat 6 to fix the inner ring 2 of the bearing and attract the cylindrical roller 3, making the placement of the cylindrical roller 3 more convenient and stable, and avoiding the problem of the roller falling off during manual operation. The outer ring, with its discontinuous closed circular structure, is spliced ​​according to markings, and elastic auxiliary tools are used to maintain the splicing state, ensuring the accuracy and stability of the outer ring splicing. Finally, demagnetization is performed to remove the magnetism from the bearing, avoiding the influence of magnetism on bearing performance. The entire assembly process is simple to operate, can achieve automated mass production, improves production efficiency, and represents a significant improvement compared to the manual loading method of the prior art.

[0040] Example 3 Reference Figures 4-5 The method for controlled fracture of the bearing outer ring provided in this application includes the following steps: S201: Position the stress groove 5 on the outer ring 1 of the thin-walled cross bearing. The stress groove 5 is located at one or more positions along the circumferential direction on the outer circular surface and / or the two axial end faces of the bearing outer ring 1. Concentrically fit the bearing outer ring 1 onto the expansion and fracture fixture 7. When positioning the stress groove 5, precise measurements can be taken using measuring tools to ensure the accurate position of the stress groove 5. The design of the expansion and fracture fixture 7 needs to ensure that the bearing outer ring 1 can be accurately fixed in the center position and that tension can be applied to the stress groove 5 from the inside.

[0041] S202: Tension is applied from the inner side of the bearing outer ring 1 to the stress groove 5 via the expansion fixture 7, causing the bearing outer ring 1 to fracture controllably along the stress groove 5, forming one or more fracture points, resulting in a discontinuous closed circle. The expansion fixture 7 can apply tension using hydraulic devices, mechanical transmission devices, etc. When applying tension, it is necessary to increase the tension slowly, causing the bearing outer ring 1 to gradually fracture along the stress groove 5, avoiding inaccurate fracture location or excessive fracture.

[0042] The implementation principle of this embodiment is as follows: The controllable fracture method of this embodiment applies tension by precisely machining the stress groove 5 and using the fracture expansion fixture 7. Utilizing the brittle fracture characteristics of ductile iron, the outer ring 1 of the bearing can be accurately fractured along a preset path, forming one or more fracture surfaces. Furthermore, the plastic deformation at the fracture point is minimal, ensuring dimensional accuracy after reassembly. This method solves the problem of controlling the fracture location and accuracy in existing technologies, providing an effective solution for the manufacturing of crossed roller bearings. It makes bearing production more efficient and precise, offering significant advantages over traditional machining methods.

[0043] Example 4 In this embodiment, the crossed roller bearing also includes a retainer for separating and positioning the cylindrical rollers 3. The structure of the retainer is adapted to the discontinuous closed circle design of the bearing outer ring 1, enabling complete annular or segmented assembly. This achieves a retainer assembly process that is difficult to accomplish with traditional integral outer ring bearings. Specifically, the retainer can be selected from the following three structural forms according to the bearing precision requirements and assembly scenario: The integrated circular retainer has an overall annular structure with several evenly spaced pockets along its circumference that fit the cylindrical rollers 3. The spacing between these pockets matches the cross-shaped arrangement of the roller raceways 4. Because the outer ring 1 of the bearing is a non-continuous closed circular structure, the integrated circular retainer can be directly fitted onto the outside of the rollers after the cylindrical rollers 3 are placed into the inner ring raceways. This eliminates the need for installation through narrow mounting holes, solving the problem of traditional integral outer rings being unable to accommodate integrated circular retainers. This ensures that the rollers do not move during high-speed operation and significantly reduces operating noise.

[0044] One-piece retainer with slit: An axial slit is made on the outer circumference of the one-piece circular retainer, and an overlapping structure that can elastically return to its original position is set at the slit. During assembly, the retainer can be inserted into the outside of the roller by spreading the slit, and the material elasticity will cause the slit to close automatically. It is suitable for manual or semi-automatic assembly scenarios, which not only maintains the stability of the one-piece structure, but also simplifies the assembly operation.

[0045] Split-type retainer: It consists of several independent spacers, each spacer corresponding to the gap position of two adjacent rollers. During assembly, the spacers need to be inserted into the inner ring groove one by one while the cylindrical rollers 3 are being placed. Although the installation of a single spacer is slightly more difficult than that of an integral retainer, thanks to the non-continuous closed circle design of the bearing outer ring 1, the position of the spacers can be adjusted by visual operation before splicing the outer ring, avoiding the retainer misalignment problem caused by the limited assembly space under the traditional integral outer ring.

[0046] In this embodiment, the addition of a retainer further optimizes the motion trajectory of the cylindrical roller 3. Through the contact guidance between the retainer and the roller, direct friction between the rollers is reduced, lowering the coefficient of friction during bearing operation. Simultaneously, it prevents the rollers from tilting or shifting when subjected to overturning moments, improving the rotational stability of the bearing. All three retainer structures rely on the discontinuous closed-circle characteristic of the bearing outer ring 1 to achieve assembly feasibility, providing flexible selection options for different application scenarios.

[0047] The implementation principle of this embodiment is as follows: by designing three types of crossed roller retainer structures adapted to the non-continuous closed circular outer ring structure, the limitations of traditional integral outer ring bearings caused by assembly space constraints in retainer selection are overcome. The integral circular retainer achieves the assembly of a complete annular structure by utilizing the non-continuous characteristics of the outer ring; the retainer with notches balances structural stability and assembly convenience; and the split retainer reduces installation difficulty through visual operation before the outer ring is assembled. All three solutions improve the bearing's operating accuracy and service life through precise matching between the retainer and the rollers, further expanding the application scenarios of crossed roller bearings in the field of precision transmission.

[0048] Example 5 The method also includes: S301: When using the brittle fracture process, a directional tension is applied to the bearing outer ring 1 made of zirconium-based or gallium-based amorphous alloy along the position of the preset stress groove 5. By utilizing the brittle fracture characteristics of the material, the bearing outer ring 1 undergoes brittle fracture along the stress groove 5, forming a rough, irregular and unique fracture surface. S302: After fracture, inspect the integrity of the fracture surface to prevent defects and ensure the uniqueness of the splicing surface of each outer ring and the integrity of the whole ring after splicing. S303: When using injection molding or die casting, single or multiple layers of graphene sheets are placed at one or more positions along the circumferential direction in the mold cavity to divide the cavity into multiple segments. After injecting zirconium-based or gallium-based amorphous alloy materials, the high temperature resistance and ultra-thin properties of graphene are utilized to make the material separate along the position of the graphene sheet, forming a separation similar to a brittle fracture effect, and forming nanoscale gaps between the segments. S304: After the material is pressed and formed, it is taken out and the segments are spliced ​​into a whole circle. After grinding, it is used for assembly; or a graphene sheet is placed in the mold to form a single-opening structure. During assembly, an external force is applied along the opening to make it open. After the roller is inserted, the external force is released to reset it.

[0049] In this embodiment, the discontinuous closed circular structure of the bearing outer ring 1 can be precisely segmented through two innovative processes, further improving splicing accuracy and production efficiency. The first process involves adding zirconium-based amorphous alloy or gallium-based amorphous alloy as alternative materials to ductile iron. These materials have a tensile strength ≥1500MPa and an elongation ≤1%, possessing both high hardness and controllable brittle fracture characteristics. A V-shaped stress groove 5 with a depth of 0.3-0.5mm and a width of 0.1-0.2mm is machined on the outer circular surface of the bearing outer ring 1 using laser etching. The etching trajectory can be symmetrically distributed along the circumference or distributed as needed, depending on the required number of fracture surfaces, ensuring a stress concentration factor of ≥3.5. A hydraulic fracture fixture 7 is used, and the fracture force loading rate (0.5-1kN / s) is precisely controlled by a PLC, causing the material to undergo brittle fracture along the stress groove 5. The fracture surface roughness Ra ≤1.6μm and the plastic deformation layer thickness ≤50μm. After the fracture, each outer ring segment was inspected using a coordinate measuring machine. The flatness error of the splicing surface was ≤0.005mm, and the angle deviation was ≤0.01°, achieving micron-level precision in the splicing.

[0050] The second process involves using zirconium-based or gallium-based amorphous alloys with a glass transition temperature (Tg) ≤ 400℃ and a crystallization temperature (Tx) ≥ 500℃. Single-layer or multi-layer graphene is prepared using chemical vapor deposition (CVD) with a thickness of 0.34-3 nm, an area ≥ 100 mm², and thermal stability ≥ 1000℃. A corresponding number of graphene sheets are installed at one or more positions along the circumferential direction within the mold cavity of the outer ring 1 of the bearing, or a single graphene sheet is installed along the diameter. The graphene sheets are fixed to the inner wall of the mold cavity using a high-temperature resistant resin (such as polyimide). The amorphous alloy is heated to the supercooled liquid phase region (Tg + 50℃) and injected into the mold cavity at a pressure of 100-200 MPa. The graphene sheets divide the material into multiple segments or annular structures with single openings, with the gap width equal to the thickness of the graphene sheet (nanometer level). After molding and cooling to room temperature, the outer rings are demolded and precisely spliced ​​together using a vacuum adsorption fixture. The nanoscale gaps are seamlessly joined by intermolecular forces, resulting in a roundness error of ≤0.003mm for the spliced ​​outer rings. The spliced ​​outer rings are then precision ground to remove the residual graphene layer (thickness ≤3nm), ensuring a surface roughness Ra ≤0.05μm for the roller groove 4 and dimensional tolerances controlled within ±0.002mm.

[0051] When using a single sheet of graphene to form a single-opening outer ring, a radial force is applied along the opening during assembly using a specialized fixture. This causes the notch to open to 1.2-1.5 times the roller diameter. After quickly inserting the cylindrical roller 3, the external force is released, and the material's elastic recovery enables self-closure. The residual gap at the opening is ≤0.01mm, ensuring smooth roller operation. This process, combining the nanoscale thickness characteristics of graphene with the superplastic forming capabilities of amorphous alloys, breaks through the precision limits of traditional mechanical splitting processes, achieving sub-micron level splicing accuracy. Simultaneously, the single-opening structure design provides a new approach to roller assembly, avoiding the damage to the bearing structure integrity caused by traditional assembly holes. This process is suitable for applications such as robot joints and optical instruments where bearing precision and stability are extremely high. While ensuring bearing rotational accuracy (≤0.001mm), it improves production efficiency by 30%-50%.

[0052] The implementation principle of this embodiment is as follows: Near-net-shape forming is achieved in the superplastic forming region of the amorphous alloy in the supercooled liquid phase region, while the atomic-level thickness of graphene serves as a physical separating layer, enabling nanoscale precision material separation. This method avoids stress concentration and thermal deformation problems in traditional machining, ensuring that the bearing outer ring maintains extremely high dimensional accuracy and surface quality even after segmentation. The single-opening structure cleverly utilizes the elastic modulus of the amorphous alloy to achieve controllable elastic deformation during assembly, ensuring smooth roller insertion while maintaining structural integrity through elastic restoring force. Both processes optimize the performance of the discontinuous closed-circle design of the bearing outer ring through precise control of the material's microstructure and processing parameters, providing a reliable technical path for the mass production of high-precision crossed roller bearings.

[0053] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape, and principle of this application, especially those involving structural designs where the outer ring of the bearing is a non-continuous closed circle, should be covered within the scope of protection of this application.

Claims

1. A crossed roller bearing, characterized in that, The bearing includes an outer ring (1), an inner ring (2), and cylindrical rollers (3); the inner circumferential surface of the outer ring (1) and the outer circumferential surface of the inner ring (2) are both machined with several roller grooves (4) adapted to the cylindrical rollers (3); the inner ring (2) is concentrically assembled on the radial inner side of the outer ring (1); the cylindrical rollers (3) are arranged in a cross shape in the roller grooves (4) between the inner ring (2) and the outer ring (1); the outer ring (1) is a non-continuous closed circle, and one or more fracture points are provided on the outer ring (1).

2. The crossed roller bearing according to claim 1, characterized in that, The outer ring (1) of the bearing is made of ductile iron or amorphous alloy.

3. The crossed roller bearing according to claim 1, characterized in that, Before controlled fracture, the outer ring (1) of the bearing is a continuous closed circle, and one or more stress grooves (5) are machined along the circumferential direction on the outer circular surface and / or the two axial end faces; the one or more fracture openings are formed by controlled fracture along the stress grooves (5), and after fracture, the outer ring (1) of the bearing is a discontinuous closed circle.

4. A crossed roller bearing according to claim 1, characterized in that, The two semicircular outer rings are provided with unique corresponding splicing marks for precise splicing of the two semicircular outer rings.

5. A crossed roller bearing according to claim 1, characterized in that, The surface of the roller groove (4) of the outer ring (1) of the bearing is subjected to high-frequency quenching or surface coating treatment.

6. A crossed roller bearing according to claim 1, characterized in that, It also includes a sealing ring, which is disposed at the axial end between the outer ring (1) and the inner ring (2) of the bearing.

7. A crossed roller bearing according to claim 1, characterized in that, It also includes a retainer for separating and positioning the cylindrical rollers (3), and the structure of the retainer is adapted to the split design of the outer ring (1) of the bearing to achieve a complete ring or segmented assembly.

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