Flexible gear with layered tooth heads for harmonic reducer

Abstract

The flexible gear comprises a flexible gear body, the flexible gear body is provided with the tooth head, the tooth head comprises a base body, a transition layer and a wear-resistant layer, the transition layer covers the surface of the base body, the wear-resistant layer covers the outer side of the transition layer, and the wear-resistant layer covers the outer side of the transition layer. The base body and the transition layer are connected through a physical interlocking structure. Through the three-layer structural design of the base body, the transition layer and the wear-resistant layer and physical interlocking connection between the base body and the transition layer, the bonding strength between the wear-resistant layer and the base body is remarkably improved, and the problem that the wear-resistant layer is prone to stripping in the prior art is solved. The transition layer is additionally arranged, the base body and the transition layer are connected through the physical interlocking structure, mechanical meshing is achieved, the binding force is enhanced, and the binding strength is greatly improved compared with traditional plane attachment. And meanwhile, the transition layer is arranged to effectively disperse the interface stress, and the interface cracking risk caused by stress mutation is reduced.

Description

Technical Field

[0001] This application belongs to the field of harmonic reducer technology, specifically relating to a flexible gear for a harmonic reducer with layered toothed heads. Background Technology

[0002] As a core component in the field of precision transmission, the reliability of the flexspline teeth of a harmonic reducer directly determines its service life and transmission accuracy. However, in existing flexspline tooth designs, there are significant defects in the bonding structure between the wear-resistant layer and the substrate, leading to problems such as easy peeling of the wear-resistant layer and short service life, which seriously restricts the performance improvement of harmonic reducers.

[0003] In traditional designs, flexible gear teeth typically employ a single wear-resistant layer directly coated onto the substrate surface. While this design is simple, the significant difference in thermal expansion coefficients and elastic moduli between the substrate and wear-resistant layer materials leads to stress concentration at the interface under alternating loads, causing the wear-resistant layer to peel off from the substrate surface. Furthermore, during the start-up and shutdown of the harmonic reducer or sudden load changes, the instantaneous impact load on the gear teeth further exacerbates the stress concentration at the interface, resulting in the failure of the bond between the wear-resistant layer and the substrate.

[0004] To address the above issues, while some solutions have attempted to improve performance through material replacement or complex processes, these methods involve material innovation or process limitations, making it difficult to balance processing costs and structural reliability. Utility Model Content

[0005] This application provides a flexible gear for a harmonic reducer with layered teeth to solve the technical problems of easy tooth breakage and poor durability of traditional flexible gears.

[0006] The technical solution adopted in this application is as follows:

[0007] A flexible wheel for a harmonic reducer with layered teeth includes a flexible wheel body, on which teeth are provided. Each tooth includes a base, a transition layer, and a wear-resistant layer. The transition layer covers the surface of the base, and the wear-resistant layer covers the outside of the transition layer. The base and the transition layer are connected by a physical interlocking structure.

[0008] The flex wheel for the harmonic reducer described in this application also includes the following additional technical features:

[0009] The hardness of the wear-resistant layer is greater than that of the substrate, the elastic modulus of the wear-resistant layer is greater than that of the substrate, and the elastic modulus of the transition layer is between that of the substrate and the wear-resistant layer.

[0010] The physical interlocking structure includes connecting protrusions evenly distributed on the surface of the substrate, and connecting grooves correspondingly disposed in the transition layer, wherein the connecting protrusions are embedded in the connecting grooves.

[0011] The width of the connecting protrusion is 0.05-0.1mm, and there are multiple connecting protrusions and connecting grooves, with the multiple connecting protrusions arranged at intervals on the outer surface of the substrate.

[0012] The distance between two adjacent connecting protrusions is L, where 0.1mm ≤ L ≤ 0.3mm.

[0013] The tooth root is provided with an arc-shaped groove, and the inner wall of the arc-shaped groove is provided with a plurality of elastic support protrusions at intervals. The elastic support protrusions are hemispherical, and the distance between two adjacent elastic support protrusions is 0.2-0.5mm.

[0014] The thickness of the transition layer gradually increases from the top of the tooth to the bottom of the tooth.

[0015] Due to the adoption of the above technical solution, the beneficial effects achieved by this application are as follows:

[0016] 1. This application significantly improves the bonding strength between the wear-resistant layer and the substrate through a three-layer structure design of "substrate-transition layer-wear-resistant layer" and a physical interlocking connection between the substrate and the transition layer, solving the problem of easy peeling of the wear-resistant layer in the prior art. Traditional flexible gear teeth directly coat the wear-resistant layer onto the substrate surface. Due to differences in material properties such as mismatched coefficients of thermal expansion and elastic modulus, shear stress concentration easily occurs at the interface under alternating loads, leading to peeling of the wear-resistant layer. In contrast, this application adds a transition layer and uses a physical interlocking structure to connect the substrate and the transition layer, achieving mechanical interlocking and enhanced bonding force, resulting in a significant improvement in bonding strength compared to traditional planar bonding. At the same time, the transition layer effectively disperses interface stress, reducing the risk of interface cracking caused by stress abrupt changes. In addition, the physical interlocking structure, through the interlocking design of protrusions and grooves, undergoes micro-deformation under impact loads, absorbing impact energy, reducing interface stress, and inhibiting the initiation and propagation of interface micro-cracks, which helps to improve the fatigue life of the gear teeth.

[0017] This structural design is also suitable for complex working conditions. For example, in high-temperature environments, the transition layer can buffer the thermal stress caused by the difference in thermal expansion coefficients between the substrate and the wear-resistant layer, preventing coating warping. When rotating at high speed, the mechanical interlocking of the physical interlocking structure can resist the peeling effect of centrifugal force on the wear-resistant layer, improving the durability of the tooth head in multiple ways.

[0018] 2. In a preferred embodiment of this application, the hardness of the wear-resistant layer is greater than that of the substrate, and the elastic modulus transitions gradually from the substrate to the wear-resistant layer, significantly optimizing the wear resistance, impact resistance, and material compatibility of the flexible gear tooth. This significantly reduces the surface wear rate during meshing, while the substrate maintains high toughness, preventing tooth breakage due to impact loads and achieving a synergistic performance of "hard exterior and tough interior." Simultaneously, the gradient design of the elastic modulus of the transition layer greatly reduces the interfacial shear stress between layers, preventing coating peeling caused by stress concentration. This gradient design also ensures that the wear-resistant layer primarily bears the surface friction load, while the transition layer bears the interfacial shear load, working together to protect the tooth. Furthermore, the gradient design of the elastic modulus allows for the use of more material combinations between the substrate and the wear-resistant layer without requiring strict matching of material properties, reducing processing difficulty and cost.

[0019] 3. As a preferred embodiment of this application, the physical interlocking structure consists of connecting protrusions on the substrate surface and connecting grooves in the transition layer. The mechanical interlocking design significantly improves the interfacial bonding strength and shear resistance. The embedded design of the connecting protrusions and grooves greatly increases the effective contact area between the substrate and the transition layer, thereby significantly improving the bonding strength. Simultaneously, the cooperation between the protrusions and grooves makes the connection between the substrate and the transition layer tighter, improving the shear strength of the interface. Furthermore, this structural design also has processing feasibility and cost advantages. The dimensions of the connecting protrusions (width 0.05-0.1mm, spacing 0.1-0.3mm) can be achieved through CNC milling or laser engraving, helping to reduce the manufacturing difficulty of the tooth tips. Moreover, during the meshing rotation of the flexible wheel and the rigid wheel, the tooth tips of the flexible wheel will continuously contact and collide. Especially when the flexible wheel speed is high, the tooth tips will continuously endure high-frequency vibrations caused by the impacts. The mechanical interlocking of the protrusions and grooves can suppress interfacial fretting wear caused by high-frequency vibrations and improve the tightness of the connection between the substrate and the transition layer under vibration, further improving the structural integrity of the tooth tips.

[0020] 4. As a preferred embodiment of this application, the arc-shaped groove provides deformation space for the tooth head. When the tooth head is subjected to a large external force, the tooth head undergoes a certain degree of elastic deformation and converts the stress into elastic potential energy required for elastic deformation. As the tooth head deforms, the inner wall of the arc-shaped groove squeezes the elastic support protrusion. The elastic support protrusion supports the tooth head, which helps to support the tooth head's return to its original position and prevents the tooth head from breaking due to excessive deformation. This helps to improve the structural strength and service life of the tooth head. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 This is a front view of a flexure wheel for a harmonic reducer according to one embodiment of this application;

[0023] Figure 2 for Figure 1 Enlarged view of part A;

[0024] Figure 3 This is a cross-sectional view of the tooth head according to one embodiment of this application;

[0025] Figure 4 This is a schematic diagram of the flex wheel structure of a harmonic reducer according to one embodiment of this application;

[0026] Figure 5 This is a schematic diagram of a toothed head according to one embodiment of this application.

[0027] List of components and reference numerals:

[0028] 1Flexspline body;

[0029] 2. Tooth tip, 21. Substrate, 22. Transition layer, 23. Wear-resistant layer;

[0030] 3 connecting protrusions;

[0031] 4. Connecting grooves;

[0032] 5. First lubrication groove;

[0033] 6. Second lubrication groove;

[0034] 7. Circular oil storage pits;

[0035] 8. Arc-shaped grooves;

[0036] 9. Elastic support protrusions. Detailed Implementation

[0037] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0038] Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below. It should be noted that, unless otherwise specified, the embodiments of this application and the features thereof can be combined with each other.

[0039] Furthermore, it should be understood in the description of this application that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0040] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0041] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0042] like Figures 1 to 5 As shown, a flexible wheel for a harmonic reducer with layered teeth includes a flexible wheel body 1, on which teeth 2 are provided. The teeth 2 include a base 21, a transition layer 22 and a wear-resistant layer 23. The transition layer 22 covers the surface of the base 21, and the wear-resistant layer 23 covers the outside of the transition layer 22. The base 21 and the transition layer 22 are connected by a physical interlocking structure.

[0043] This application significantly improves the bonding strength between the wear-resistant layer 23 and the substrate 21 through a three-layer structure design of "substrate 21-transition layer 22-wear-resistant layer 23" and a physical interlocking connection between the substrate 21 and the transition layer 22, solving the problem of easy peeling of the wear-resistant layer 23 in the prior art. Traditional flexible gear teeth 2 directly coat the wear-resistant layer 23 onto the surface of the substrate 21. Due to differences in material properties such as mismatched coefficients of thermal expansion and elastic modulus, shear stress concentration easily occurs at the interface under alternating loads, leading to peeling of the wear-resistant layer 23. This application adds a transition layer 22 and uses a physical interlocking structure to connect the substrate 21 and the transition layer 22, achieving mechanical interlocking and enhanced bonding force, resulting in a significant improvement in bonding strength compared to traditional planar bonding. Simultaneously, the transition layer 22 effectively disperses interface stress, reducing the risk of interface cracking caused by stress abrupt changes. In addition, the physical interlocking structure, through the interlocking design of protrusions and grooves, undergoes micro-deformation under impact load, absorbs impact energy, reduces interface stress, and inhibits the initiation and propagation of interface micro-cracks, which helps to improve the fatigue life of tooth 2.

[0044] This structural design is also suitable for complex working conditions. For example, in high-temperature environments, the transition layer 22 can buffer the thermal stress caused by the difference in thermal expansion coefficients between the substrate 21 and the wear-resistant layer 23, thus preventing the coating from warping. When rotating at high speed, the mechanical interlocking action of the physical interlocking structure can resist the peeling effect of centrifugal force on the wear-resistant layer 23, thereby improving the durability of the tooth 2 in multiple ways.

[0045] In a preferred embodiment of this application, the hardness of the wear-resistant layer 23 is greater than that of the substrate 21, the elastic modulus of the wear-resistant layer 23 is greater than that of the substrate 21, and the elastic modulus of the transition layer 22 is between that of the substrate 21 and the wear-resistant layer 23.

[0046] The wear-resistant layer 23 has a higher hardness than the substrate 21, and its elastic modulus gradually transitions from the substrate 21 to the wear-resistant layer 23, significantly optimizing the wear resistance, impact resistance, and material compatibility of the flexible gear tooth 2. This significantly reduces the surface wear rate during meshing, while the substrate 21 maintains high toughness, preventing the tooth 2 from fracturing due to impact loads, achieving a synergistic performance of "hard on the outside, tough on the inside." Simultaneously, the gradient design of the elastic modulus of the transition layer 22 greatly reduces the interfacial shear stress between layers, preventing coating peeling caused by stress concentration. This gradient design also ensures that the wear-resistant layer 23 primarily bears the surface friction load, while the transition layer 22 bears the interfacial shear load, working together to protect the tooth 2. Furthermore, the gradient elastic modulus design allows for the use of more material combinations between the substrate 21 and the wear-resistant layer 23 without requiring strict matching of material properties, reducing processing difficulty and cost.

[0047] Preferably, the transition layer 22 can be made of nickel-based alloy or titanium alloy, which has high strength and high toughness; the wear-resistant layer 23 is made of titanium nitride, diamond-like carbon film or tungsten carbide, which has high hardness and high wear resistance.

[0048] This application does not limit the type or molding method of the wear-resistant layer 23. In another embodiment, the wear-resistant layer is a dip-coated wear-resistant layer. When manufacturing the tooth, the substrate and transition layer are first manufactured to form a portion of the tooth. This portion of the tooth is placed in a heating device and heated to a certain temperature so that the surface of the transition layer reaches the activation state required for dip coating. Then, the heated portion of the tooth is immersed in the dip coating liquid to uniformly cover the surface of the wear-resistant layer with a dip coating film. The dip-coated tooth is then placed in a cooling device for rapid cooling so that the dip-coated wear-resistant layer solidifies on the outer surface of the transition layer. Then, the dip-coated wear-resistant layer is further polished and processed according to design requirements.

[0049] Specifically, the dip coating solution can be polyethylene, polyvinyl chloride, polytetrachloroethylene, etc.

[0050] As a preferred embodiment of this application, such as Figure 3 As shown, the physical interlocking structure includes connecting protrusions 3 evenly distributed on the surface of the substrate 21, and corresponding connecting grooves 4 disposed within the transition layer 22. The connecting protrusions 3 are embedded in the connecting grooves 4. The width of the connecting protrusions 3 is 0.05-0.1 mm, and there are multiple connecting protrusions 3 and connecting grooves 4, with the multiple connecting protrusions 3 arranged at intervals on the outer surface of the substrate 21. The distance between two adjacent connecting protrusions 3 is L, where 0.1 mm ≤ L ≤ 0.3 mm.

[0051] The physical interlocking structure consists of connecting protrusions 3 on the surface of the substrate 21 and connecting grooves 4 on the transition layer 22. This mechanical interlocking design significantly enhances the interfacial bonding strength and shear resistance. The embedded design of the connecting protrusions 3 and grooves greatly increases the effective contact area between the substrate 21 and the transition layer 22, thereby significantly improving the bonding strength. Simultaneously, the cooperation between the protrusions and grooves makes the connection between the substrate 21 and the transition layer 22 tighter, improving the shear strength of the interface. Furthermore, this structural design offers advantages in processing feasibility and cost. The dimensions of the connecting protrusions 3—0.05-0.1 mm in width and 0.1-0.3 mm in spacing—can be achieved through CNC milling or laser engraving, helping to reduce the manufacturing difficulty of the tooth head 2. Furthermore, during the meshing and rotation of the flexible wheel and the rigid wheel, the tooth 2 of the flexible wheel will continuously contact and collide. Especially when the speed of the flexible wheel is high, the tooth 2 will continuously bear the high-frequency vibration caused by the impact. The mechanical engagement of the protrusion and the groove can suppress the interfacial fretting wear caused by high-frequency vibration and improve the connection tightness between the substrate 21 and the transition layer 22 under the action of vibration, further improving the structural integrity of the tooth 2.

[0052] As a preferred embodiment of this application, such as Figure 4As shown, the outer surface of the wear-resistant layer 23 is provided with a first lubrication groove 5 and a second lubrication groove 6 at intervals. The first lubrication groove 5 extends along the rotation direction of the flexible wheel, and the second lubrication groove 6 is set at an angle to the first lubrication groove 5.

[0053] The outer surface of the wear-resistant layer 23 is provided with a first lubrication groove 5 and a second lubrication groove 6. The first lubrication groove 5 extends along the rotation direction of the flexible wheel, and the second lubrication groove 6 is set at an angle to the first lubrication groove 5. As the flexible wheel rotates, the lubricating oil in the first lubrication groove 5 and the second lubrication groove 6 is thrown out under the action of centrifugal force and continues to move along the outer surface of the wear-resistant layer 23 under the action of inertia, forming a dense oil film, which provides lubrication and protection for the tooth head 2. In addition, the staggered arrangement of the first lubrication groove 5 and the second lubrication groove 6 allows the lubricating oil flowing out of the two lubrication grooves to move in different directions along the outer surface of the wear-resistant layer 23, thereby improving the coverage of the wear-resistant layer 23 and further improving the lubrication coverage of the outer surface of the tooth head 2.

[0054] As a preferred embodiment of this implementation, such as Figure 4 As shown, a circular oil storage pit 7 is provided at the junction of the first lubrication groove 5 and the second lubrication groove 6.

[0055] The oil reservoir forms a local oil storage area at the junction of the lubrication groove, which allows the lubricant to be distributed more evenly on the outer surface of the wear-resistant layer 23 during meshing, extending the lubricant replenishment cycle, reducing the maintenance frequency, and improving the utilization efficiency of the flexible gear tooth 2.

[0056] In another preferred embodiment of this implementation, the width of the first lubrication groove 5 is L1 and the depth is D1, the width of the second lubrication groove 6 is L2 and the depth is D2, 0.1mm≤L1≤0.2mm, 0.05mm≤D1≤0.08mm; 0.05mm≤L2≤0.1mm, 0.03mm≤D2≤0.05mm; the included angle between the first lubrication groove 5 and the second lubrication groove 6 is α, 30°≤α≤60°.

[0057] The width, depth, and included angle of the first lubrication groove 5 and the second lubrication groove 6 are defined to optimize the lubrication groove design. The first lubrication groove 5 has a width of 0.1-0.2 mm and a depth of 0.05-0.08 mm, while the second lubrication groove 6 has a width of 0.05-0.1 mm and a depth of 0.03-0.05 mm. The included angle between the two sets of lubrication grooves is 30°-60°, ensuring that the lubricant forms a uniform lubricating film on the friction surface. This design, by optimizing the size and distribution of the lubrication grooves, significantly improves the utilization efficiency of the lubricant.

[0058] As a preferred embodiment of this application, such as Figure 5As shown, the tooth head 2 has an arc-shaped groove 8 at its root. The inner wall of the arc-shaped groove 8 is provided with multiple elastic support protrusions 9 at intervals. The elastic support protrusions 9 are hemispherical, and the distance between two adjacent elastic support protrusions 9 is 0.2-0.5mm.

[0059] The arc-shaped groove 8 provides deformation space for the tooth head 2. When the tooth head 2 is subjected to a large external force, it undergoes a certain degree of elastic deformation and converts the stress into elastic potential energy required for elastic deformation. As the tooth head 2 deforms, the inner wall of the arc-shaped groove 8 squeezes the elastic support protrusion 9. The elastic support protrusion 9 supports the tooth head 2, which helps to support the tooth head 2 to return to its original position and prevents the tooth head 2 from breaking due to excessive deformation. This helps to improve the structural strength and service life of the tooth head 2.

[0060] In a preferred embodiment of this application, the thickness of the transition layer 22 gradually increases from the top of the tooth 2 to the bottom of the tooth 2.

[0061] The thickness of the transition layer 22 gradually increases from the top of the tooth head 2 to the bottom of the tooth head 2, so that the stress dispersion effect and bonding strength of the transition layer 22 are optimized. The thick transition layer 22 at the tooth root enhances the bonding strength, makes the interface stress distribution more uniform, and reduces the local stress concentration system.

[0062] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0063] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0064] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A flexible gear for a harmonic reducer with layered teeth, characterized in that, The device includes a flexible wheel body, on which a tooth is provided. The tooth includes a base, a transition layer and a wear-resistant layer. The transition layer covers the surface of the base, and the wear-resistant layer covers the outside of the transition layer. The base and the transition layer are connected by a physical interlocking structure.

2. The flexible wheel for a harmonic reducer according to claim 1, characterized in that, The hardness of the wear-resistant layer is greater than that of the substrate, the elastic modulus of the wear-resistant layer is greater than that of the substrate, and the elastic modulus of the transition layer is between that of the substrate and the wear-resistant layer.

3. The flexible wheel for a harmonic reducer according to claim 1, characterized in that, The physical interlocking structure includes connecting protrusions evenly distributed on the surface of the substrate, and connecting grooves correspondingly disposed in the transition layer, wherein the connecting protrusions are embedded in the connecting grooves.

4. The flexible wheel for a harmonic reducer according to claim 3, characterized in that, The width of the connecting protrusion is 0.05-0.1mm, and there are multiple connecting protrusions and connecting grooves, with the multiple connecting protrusions arranged at intervals on the outer surface of the substrate.

5. The flexible wheel for a harmonic reducer according to claim 4, characterized in that, The distance between two adjacent connecting protrusions is L, where 0.1mm ≤ L ≤ 0.3mm.

6. The flexible wheel for a harmonic reducer according to claim 1, characterized in that, The tooth root is provided with an arc-shaped groove, and the inner wall of the arc-shaped groove is provided with a plurality of elastic support protrusions at intervals. The elastic support protrusions are hemispherical, and the distance between two adjacent elastic support protrusions is 0.2-0.5mm.

7. The flexible wheel for a harmonic reducer according to claim 1, characterized in that, The thickness of the transition layer gradually increases from the top of the tooth to the bottom of the tooth.

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