Harmonic reducer flexible bearing anti-creep structure

Abstract

A kind of harmonic reducer flexible bearing anti-creep structure, including bearing outer ring and bearing inner ring, rolling element is arranged between the bearing outer ring and bearing inner ring, the first arc and the second arc are respectively arranged in the direction of rolling element of the bearing outer ring and bearing inner ring, the rolling element operates between the first arc and the second arc, the outer diameter surface of the bearing outer ring towards flexspline is provided with groove.The utility model has the beneficial effects that: by setting up groove on the outer diameter surface of bearing outer ring, effectively increase the contact area and the matching friction force between bearing outer ring and bearing shell, to inhibit the creep phenomenon of bearing in the working process.

Description

Technical Field

[0001] This utility model relates to a bearing structure, and more particularly to an anti-creep structure for a flexible bearing in a harmonic reducer. Background Technology

[0002] Harmonic reducers are widely used in industrial robotics. As a key transmission component, the flexible bearing, its core component, plays a crucial role in power transmission. In industrial robot joints, the harmonic reducer uses the elliptical shape of a wave generator to drive the outer ring of the flexible bearing to undergo periodic elastic deformation. This deformation causes alternating engagement and disengagement between the flexible and rigid gears. During operation, the wave generator, driven by a motor, rotates. Its major axis causes the outer ring of the bearing to expand outward, pushing the flexible gear teeth to engage with the rigid gear teeth, while the minor axis disengages the engagement, thus achieving high-precision speed reduction and torque output. The flexible bearing not only supports the movement of the wave generator but also adapts to repeated deformation through its flexibility, ensuring smooth operation and precise positioning of the robot joint. It is widely used in automated scenarios such as assembly, welding, and material handling to meet the demands of high dynamic performance and compact structures.

[0003] However, existing harmonic reducers have significant drawbacks, primarily in the application of flexible bearings. During operation, the wave generator causes the outer ring of the flexible bearing to deform flexibly, driving the flex wheel to mesh with the rigid wheel. When the long axis of the flex wheel contacts the rigid wheel, the short axis is in a separated state. Under high torque, a micro-protrusion occurs on the outer ring surface at the contact point between the internal steel balls and the outer ring raceway, reducing the contact area of ​​the bearing's outer circle. This causes creep between the outer circle of the bearing and the flex wheel in the long axis direction, resulting in wear and slippage of the inner wall of the flex wheel and affecting the bearing's service life. Utility Model Content

[0004] To address the shortcomings of existing technologies, this invention provides an anti-creep structure for flexible bearings in harmonic reducers that prevents wear of the flexible wheel and reduction in bearing life caused by the creep of the flexible bearing.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a flexible bearing anti-creep structure for a harmonic reducer, comprising an outer bearing ring and an inner bearing ring, wherein a rolling element is disposed between the outer bearing ring and the inner bearing ring, and the outer bearing ring and the inner bearing ring are respectively provided with a first arc track and a second arc track in the direction of the rolling element, wherein the rolling element rotates between the first arc track and the second arc track, and a groove is provided on the outer diameter surface of the outer bearing ring facing the flexible wheel.

[0006] The beneficial effects of this invention are as follows: By setting grooves on the outer diameter surface of the bearing outer ring, the contact area and friction between the bearing outer ring and the bearing housing are effectively increased, thereby suppressing the creep phenomenon of the bearing during operation. This reduces the wear and slippage risk of the inner wall of the flexspline, extends the service life of the bearing, and improves the transmission stability and efficiency of the harmonic reducer. The groove structure enhances the fixation of the contact points through mechanical interlocking effect, preventing the reduction of contact area caused by micro-protrusion, while dispersing local stress and avoiding fatigue damage caused by stress concentration. As a preferred embodiment, the grooves can be designed as multiple grooves distributed circumferentially along the bearing outer ring, with the position of each groove corresponding to the movement trajectory of the rolling element, so that when the wave generator drives deformation, the grooves and the housing form multi-point contact, enhancing friction through the surface concave-convex interlocking mechanism. As another preferred embodiment, the grooves can be integrated into the surface texture of the bearing outer ring to form a continuous anti-slip area, maintaining stable contact performance under dynamic load, thereby optimizing the synergistic effect of the overall structure.

[0007] Furthermore, the center of the groove is on the same vertical line as the center of the first arc.

[0008] By aligning the center of the groove with the center of the first arc on the same vertical line, the groove is precisely aligned with the rolling element's trajectory during bearing deformation, maximizing friction enhancement and contact uniformity. This alignment optimizes the groove's involvement during deformation along both the major and minor axes, preventing creep and wear caused by poor local contact, while also improving the bearing's dynamic response and load distribution. As a preferred approach, the grooves can be arranged radially symmetrically along the bearing's outer ring, with the centerline of each groove coinciding with the centerline of the corresponding arc, providing consistent anti-creep performance in both the circumferential and axial directions, and enhancing surface interlocking through geometric alignment. Alternatively, the grooves can be designed as curved structures that match the arc shape to better adapt to geometric changes during deformation, ensuring stable contact characteristics under high-speed or high-torque conditions.

[0009] Furthermore, the depth of the trench is 3-5 micrometers.

[0010] By controlling the groove depth within the range of 3-5 micrometers, the requirements for enhanced surface contact and maintained structural strength are balanced, avoiding performance degradation or fatigue risks caused by excessive depth or shallow depth. The appropriate depth ensures that the groove effectively embeds into the housing surface during deformation, increasing the actual contact area without weakening the mechanical integrity of the bearing outer ring, thereby extending component life and reducing maintenance requirements. As a preferred approach, the groove can have a uniform depth distribution to provide stable frictional characteristics and load dispersion, optimizing contact performance through surface microstructure. Alternatively, the depth can gradually vary along the groove length to accommodate the deformation requirements of different load areas, ensuring consistent anti-creep performance during dynamic operation.

[0011] Furthermore, the width of the trench is b. In the formula, a is the straight line formed by connecting the center of the trench and the center of the first arc, and c is the straight line formed by connecting the edge of the trench and the center of the first arc.

[0012] By calculating the groove width based on geometric relationships, the matching between the groove dimensions and the bearing deformation characteristics is ensured, thereby optimizing the contact area and friction enhancement. This design method allows the groove to more effectively adapt to the flexible deformation driven by the wave generator, preventing local stress concentration or poor contact caused by dimensional mismatch, and improving the bearing's reliability and transmission accuracy. As a preferred approach, the groove can be designed with a width profile that coordinates with the arc motion trajectory, and the surface interlocking mechanism can be enhanced through geometric optimization to ensure stable anti-creep performance under load changes. As another preferred approach, the width can be dynamically adjusted in conjunction with the circumferential distribution of the bearing outer ring to simultaneously increase friction at multiple contact points, thereby reducing energy loss and heat generation.

[0013] Furthermore, the length of c is 1.35 times that of a.

[0014] By setting the length of 'c' to 1.35 times that of 'a', and referencing industry experience in optimizing wall thickness increases, the groove dimensions are coordinated with the bearing's deformation resistance, thereby enhancing anti-creep performance and structural durability. This proportional design allows the groove to more effectively distribute loads during deformation, preventing micro-protrusions and reducing the risk of wear on the flexspline's inner wall, thus improving overall transmission efficiency. As a preferred approach, the groove can be designed with a symmetrical geometric profile based on this proportion to form a stable anti-slip zone on the bearing's outer ring surface, optimizing contact uniformity through surface structure optimization. Alternatively, the proportion can be fine-tuned based on the bearing's dynamic load characteristics to ensure consistent performance under high-speed or high-torque conditions, thereby extending component lifespan.

[0015] Furthermore, inclined surfaces are provided on both sides of the groove, and the two ends of the inclined surfaces are respectively connected to the bottom of the groove and the outer diameter surface of the bearing outer ring.

[0016] By incorporating inclined surfaces on both sides of the groove, the contact transition between the groove and the bearing housing is optimized, reducing stress concentration and edge wear, thereby enhancing the stability and durability of the anti-creep effect. The inclined surface structure allows the groove to smoothly embed into the housing surface during deformation, improving the uniformity of the contact area and preventing slippage or fatigue damage caused by localized high points, while also enhancing the bearing's adaptability and reliability. As a preferred approach, the inclined surface can be designed as a gradually changing slope structure to provide a more uniform force distribution under load, enhancing frictional interlocking through a smooth surface transition. Alternatively, the inclined surface can be optimized in conjunction with the groove's depth and width to form a continuous anti-slip surface, ensuring stable performance during dynamic operation, thereby reducing maintenance needs and operating costs. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of an embodiment of the present utility model; Figure 2 This is a partial enlarged view of the groove in an embodiment of this utility model; Figure 3 This is a schematic diagram showing the contact between the bearing outer ring and the flexible wheel in the embodiment of this utility model when the flexible wheel is in the long shaft state; Figure 4 This is a schematic diagram showing the contact between the bearing outer ring and the flexible wheel when the flexure is in a long shaft state without grooves in this embodiment of the present invention. Detailed Implementation

[0018] This utility model embodiment provides a flexible bearing anti-creep structure for a harmonic reducer, as shown in the example below. Figure 1-4 As shown: The bearing includes an outer ring 1 and an inner ring 2. A rolling element 3, typically a steel ball or similar component, is positioned between the outer ring 1 and the inner ring 2 to reduce friction during bearing operation. The outer ring 1 has a first arc track 11 machined towards the rolling element 3, and the inner ring 2 has a second arc track 21 machined towards the rolling element 3. The rolling element 3 rolls between the first arc track 11 and the second arc track 21, thus achieving flexible deformation and power transmission of the bearing. To effectively prevent creeping during the operation of the harmonic reducer, a groove 12 is provided on the outer diameter surface of the outer ring 1 facing the flexure 4. The center of the groove 12 is aligned vertically with the center of the first arc track 11, ensuring that the position of the groove 12 corresponds to the contact area of ​​the rolling element 3. The depth of the groove 12 is designed to be 3-5 micrometers to increase surface roughness at the microscopic level without affecting the overall structural strength. The width of the groove 12 is determined by the formula... Calculations show that 'a' represents the straight-line distance connecting the center of the groove and the center of the first arc 11, and 'c' represents the straight-line distance connecting the edge of the groove and the center of the first arc 11. The length of 'c' is set to 1.35 times that of 'a', a ratio referencing industry practices that improve creep by increasing wall thickness. Furthermore, inclined surfaces 121 are machined on both sides of the groove 12, with the two ends of the inclined surfaces 121 smoothly connecting the bottom of the groove 12 and the outer diameter surface of the bearing outer ring 1, thereby optimizing stress distribution and assembly fit. The working principle of the anti-creep structure is as follows: When the harmonic reducer starts, the flexible bearing undergoes flexible deformation due to the wave generator (not shown in the figure) driving the outer ring 1 of the flexible bearing to mesh with the rigid wheel (not shown in the figure). When the long axis of the flexible wheel 4 contacts the rigid wheel (not shown in the figure), the short axis is in a separated state. Under a large torque force, the contact point between the internal rolling element 3 and the first arc track 11 of the flexible bearing produces a micro-protrusion on the surface of the outer ring 1 of the bearing. This micro-protrusion just matches the depth of the groove 12, so that the contact area between the outer ring 1 of the bearing and the flexible wheel 4 will not be reduced. The above embodiments are merely one preferred embodiment of the present utility model. Ordinary changes and substitutions made by those skilled in the art within the scope of the present utility model's technical solution are all included within the protection scope of the present utility model.

Claims

1. A flexible bearing anti-creep structure for a harmonic reducer, comprising an outer bearing ring and an inner bearing ring, wherein a rolling element is disposed between the outer bearing ring and the inner bearing ring, and the outer bearing ring and the inner bearing ring are respectively provided with a first arc track and a second arc track facing the rolling element, the rolling element rotating between the first arc track and the second arc track, characterized in that: The outer diameter surface of the bearing outer ring facing the flexure is provided with grooves.

2. The anti-creep structure for the flexible bearing of the harmonic reducer according to claim 1, characterized in that: The center of the groove is on the same vertical line as the center of the first arc.

3. The anti-creep structure for the flexible bearing of the harmonic reducer according to claim 2, characterized in that: The depth of the trench is 3-5 micrometers.

4. The anti-creep structure for the flexible bearing of the harmonic reducer according to claim 3, characterized in that: The width of the groove is b. In the formula, a is the straight line formed by connecting the center of the trench and the center of the first arc, and c is the straight line formed by connecting the edge of the trench and the center of the first arc.

5. The anti-creep structure for the flexible bearing of the harmonic reducer according to claim 4, characterized in that: The length of c is 1.35 times that of a.

6. The anti-creep structure for the flexible bearing of the harmonic reducer according to claim 1, characterized in that: Inclined surfaces are provided on both sides of the groove, and the two ends of the inclined surfaces are respectively connected to the bottom of the groove and the outer diameter surface of the bearing outer ring.

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