Harmonic reducer flexible bearing test bench and loading abutting surface calculation method

Abstract

A kind of harmonic reducer flexible bearing test bench, including rack, driving module, loading module and data acquisition module are arranged on the rack, the driving module is connected with the bearing to be measured and is used to drive the eccentric rotation of the bearing to be measured, the loading module is abutted on the bearing to be measured and applies loading force to the bearing to be measured, the data acquisition module collects each detection data of the bearing to be measured in detection process, the loading module includes loading block and loading ring belt, one side of the loading block is used to cooperate with loading ring belt, the other side of the loading block is abutted on the bearing to be measured.The beneficial effects of the present application are: by setting loading block as intermediate transmission element, the direct contact of loading ring belt and the bearing to be measured is effectively isolated, so as to reduce the loading force fluctuation caused by uncertain contact area, improve the accuracy and repeatability of test data.

Description

Technical Field

[0001] This invention relates to a bearing test bench, and more particularly to a flexible bearing test bench for harmonic reducers and a method for calculating the loading contact surface. Background Technology

[0002] Harmonic reducers, as high-precision transmission devices, are widely used in industrial robots, aerospace equipment, and precision instruments. Flexible rolling bearings are key components, responsible for achieving elastic deformation to transmit motion and torque. In application, flexible bearings are typically mounted on the wave generator of the harmonic reducer. Through cooperation with the flex wheel and rigid wheel, they bear cyclic loads and achieve deceleration. During operation, the outer ring of the bearing undergoes periodic elastic deformation driven by the wave generator, thereby driving the flex wheel to rotate and complete high-precision positioning and power transmission. This process requires the bearing to remain stable under high-speed, high-load conditions; therefore, its performance and life testing are crucial. Load tests are typically conducted on a dedicated test bench to simulate actual working conditions to evaluate its fatigue characteristics and reliability.

[0003] However, existing flexible bearing test benches for harmonic reducers have significant drawbacks. First, to accurately determine the loading wrap angle between the actual flexible wheel and the bearing outer ring (i.e., the angle formed by the arc surface of the contact area between the flexible wheel and the outer diameter surface of the bearing outer ring during rotation at the center), it is usually necessary to manufacture the flexible wheel and steel wheel in-house before testing. Furthermore, since different batches of bearings use different flexible wheels and steel wheels, this undoubtedly increases production costs. Second, the load is applied by directly attaching a belt-type loading mechanism to the bearing outer ring. Because the contact area between the belt and the bearing outer ring is difficult to precisely control and determine, the actual applied force during loading is unstable, fluctuating between high and low. This fluctuation in loading force severely affects the accuracy and repeatability of test data, making the assessment of bearing fatigue life and performance unreliable, thus impacting product optimization and quality control. Therefore, it is urgent to improve the loading mechanism to enhance the stability of the test and the reliability of the data. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a test bench for flexible bearings in harmonic reducers that solves the problem of inaccurate measurements caused by unstable loading forces.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A flexible bearing test bench for harmonic reducers includes a frame, on which a drive module, a loading module, and a data acquisition module are arranged. The drive module is connected to the bearing under test and is used to drive the bearing under test to rotate eccentrically. The loading module abuts against the bearing under test and applies a loading force to the bearing under test. The data acquisition module collects various test data of the bearing under test during the test process. The loading module includes a loading block and a loading ring belt. One side of the loading block is used to cooperate with the loading ring belt, and the other side of the loading block abuts against the bearing under test.

[0006] The beneficial effects of this invention are as follows: By setting a loading block as an intermediate transmission element, direct contact between the loading ring and the bearing under test is effectively isolated, thereby reducing the fluctuation of loading force caused by the uncertainty of the contact area and improving the accuracy and repeatability of the test data. The design of the loading block allows the loading force to be distributed more evenly on the bearing, avoiding local stress concentration and thus improving the reliability of fatigue life testing. In addition, this structure simplifies the control of the loading process and facilitates stable testing under various working conditions. As a preferred embodiment, the loading block can be made of rigid material, with a groove structure on the side that mates with the loading ring, which fixes the loading ring by a snap-fit ​​method to ensure that relative slippage does not occur during force transmission; the side of the loading block that contacts the bearing under test can be designed as a plane or a curved surface to adapt to different bearing outer ring shapes, achieving smooth force transmission through the principle of mechanical contact. As another preferred embodiment, the loading block can integrate a guiding element, such as a protrusion or slider on the side of the loading block, which mates with the guide groove on the test bench frame to restrict the degree of freedom of the loading block other than the loading direction, thereby further stabilizing the loading process and reducing lateral interference.

[0007] Furthermore, the loading force applied to the bearing under test by the loading block is a radial loading force, and the loading block is located above the bearing under test.

[0008] By placing the loading block relatively above the bearing under test and applying a radial loading force, the self-weight of the loading block can enhance its contact stability with the bearing, reducing the influence of external vibration or displacement on the loading force, thereby further improving measurement accuracy. This arrangement ensures that the loading force is always radial, which better reflects the stress conditions under actual working conditions and helps obtain more realistic fatigue performance data. As a preferred approach, the loading block can be designed as a module with a counterweight structure. Its bottom contact surface with the bearing is covered with wear-resistant material, and it naturally presses down under gravity to ensure that the loading force remains constant during bearing rotation. The upper part of the loading block can be equipped with a connection interface for fixing to a loading ring or other force-applying element, and the radial force can be applied through leverage or direct transmission. As another preferred approach, the position of the loading block can be adjusted by a height adjustment mechanism. For example, a height-adjustable support base can be set on the frame, and the loading block can be installed on it. The relative height between the loading block and the bearing can be finely adjusted by thread or hydraulic means, thereby precisely controlling the magnitude and direction of the loading force and avoiding force deviations caused by installation errors.

[0009] Furthermore, the loading module also includes a force-applying block connected to an external load, with the two ends of the loading ring respectively fitted onto the force-applying block and the loading block.

[0010] By introducing a force-applying block and fitting the two ends of the loading ring belt onto the force-applying block and the loading block respectively, the external input and transmission of the loading force are realized, making the loading process more flexible and controllable, and facilitating the adjustment of the load size according to different test requirements. This structure reduces the complexity of the loading system while improving force transmission efficiency, reducing energy loss, and ensuring that the loading force is accurately applied to the bearing under test. As a preferred approach, the force-applying block can be designed as a module with pulleys or a rotating shaft. The loading ring belt connects to the loading block after passing around the guide wheel on the force-applying block. The pulley reduces frictional resistance, making the loading force transmitted more smoothly. The force-applying block can also integrate a force sensor to monitor the applied load value in real time and adjust the external load through a feedback mechanism to achieve closed-loop control. As another preferred approach, the connection between the force-applying block and the loading ring belt can adopt a quick-disassembly structure, such as using clips or pins for fixation, which facilitates the replacement of loading ring belts or force-applying blocks of different specifications to adapt to various test scenarios. A sliding base can be set at the bottom of the force-applying block, which cooperates with the test bench guide rail, allowing the force-applying block to move in the loading direction, thereby dynamically adjusting the point of application and magnitude of the loading force.

[0011] Furthermore, the loading module also includes two fixed frames connected to the frame and symmetrically arranged on both sides of the loading block. Each fixed frame is provided with a sliding guide rail, and the loading block is provided with a limiting protrusion that cooperates with the sliding guide rail for each fixed frame on each side.

[0012] By symmetrically arranging the fixed frame, sliding guide rail, and limiting protrusions, the motion freedom of the loading block is effectively constrained, preventing lateral displacement or tilting during testing. This ensures that the loading force is always applied in the predetermined direction, improving the stability of the test and the reliability of the data. This guiding structure also facilitates the installation and adjustment of the loading block, reducing human error. As a preferred option, the sliding guide rail can be a linear guide rail or a V-groove design, with the limiting protrusions correspondingly embedded in the guide rail. Vertical movement of the loading block is achieved through rolling or sliding cooperation, while horizontal displacement is restricted. The guide rail surface can be coated with a low-friction coating to reduce motion resistance, making the loading block move more smoothly during force application. As another preferred option, the fixed frame can be designed as an adjustable bracket, with its connection point to the frame secured by bolts. This allows adjustment of the angle and position of the fixed frame to accommodate bearing tests of different sizes. The limiting protrusions can integrate buffer elements, such as springs or rubber pads, to absorb impact vibrations during loading, further stabilizing the loading force and extending the service life of the equipment.

[0013] Furthermore, the force-applying block is provided with a force-applying rod for connecting to the load.

[0014] By incorporating a force-applying rod on the force-applying block, diverse load connection methods are provided, making the source of loading force more flexible. It can be applied manually or automatically controlled, thus adapting to testing requirements of varying precision. This design simplifies the introduction of external loads, improves testing efficiency, and facilitates integration into automated systems. As a preferred approach, the force-applying rod can be designed as a multi-segment structure with standard interfaces at its ends, such as threaded holes or quick-connect couplings, for connecting weight hooks or servo motor push rods. Driving the force-applying rod with a servo motor allows for precise programmable control of the loading force, such as using PID algorithms to adjust the output force value, ensuring a smooth and fluctuation-free loading process. Alternatively, the force-applying rod can integrate a force measurement unit, such as a strain gauge or piezoelectric sensor, to collect applied load data in real time and feed it back to the control system via a data acquisition module, enabling dynamic calibration and compensation of the loading force. The installation position of the force-applying rod can be designed to be adjustable, for example, by adjusting the angle of the force-applying rod via hinges or sliders to optimize the force transmission path and reduce unnecessary bending moments.

[0015] Furthermore, the loading block is provided with a nesting groove on the side facing the loading ring for the loading ring to be nested in, and the loading block is provided with a loading boss on the side facing the bearing to be tested that abuts against the bearing to be tested. The end face of the loading boss corresponding to the outer diameter surface of the outer ring of the bearing to be tested is set in a corresponding arc surface.

[0016] By incorporating nested grooves and loading bosses, and employing an arc-shaped design on the end face of the loading boss, the tightness of the fit between the loading block, the loading ring, and the bearing under test is enhanced, reducing force transmission losses caused by contact gaps and thus improving the stability and uniformity of the loading force. This structure makes the loading process more closely resemble the actual working condition of the bearing, helping to obtain more accurate fatigue life data. As a preferred approach, the nested groove can be designed as a T-shaped or U-shaped groove structure. After the loading ring is embedded, it is fixed by a pressure plate or locking device to prevent the ring from coming out under load. The inner wall of the nested groove can be machined into a rough surface or have anti-slip textures added to increase friction and ensure no relative sliding between the loading ring and the loading block. As another preferred approach, the arc surface of the loading boss can be designed based on the curvature of the bearing outer ring, and its surface is covered with an elastic material layer, such as polyurethane or rubber, to buffer local stress and increase the contact area. The fit between the arc surface and the bearing outer ring can be achieved with high consistency through precision machining, so that the loading force is evenly distributed when the bearing rotates.

[0017] The present invention also provides a method for calculating the loading abutment surface of a loading block, which is implemented according to the following steps:

[0018] S1. Establish a geometric model by constructing the assembly model of the flexible wheel, rigid wheel, wave generator, and experimental flexible bearing of the harmonic reducer based on the input parameters and data.

[0019] S2, Set up the finite element model;

[0020] S3, the loading wrap angle is obtained by solving the CAE analysis software, and the contact area between the loading block and the outer ring of the bearing is confirmed by the loading wrap angle.

[0021] Step S2 is achieved through the following steps:

[0022] S21, Material Definition: Set the material parameters for the flexible wheel, rigid wheel, wave generator, and experimental flexible bearing;

[0023] S22, Mesh generation: Mesh generation is performed on the assembly model of the flexible wheel, rigid wheel, wave generator, and experimental flexible bearing;

[0024] S23, Contact Settings: Define five sets of contact pairs in the test flexible bearing, where the rolling elements, inner ring, outer ring, outer surface of the wave generator, and tooth surface are in contact with each other, and set the friction coefficient corresponding to each contact pair;

[0025] S24, Load and constraint settings: Apply torque loads to the wave generator, the outer surface of the rigid wheel, and the flange of the flexible wheel in the CAE analysis software.

[0026] The beneficial effects of the above solution are as follows: First, for the actual contact scenario between the flexible wheel and the outer ring of the bearing under test, the customized loading block accurately replicates the contact area and contact shape under real working conditions, avoiding the data distortion caused by contact simulation deviations in traditional testing, and ensuring that the test results can truly reflect the performance status of the bearing in the actual assembly environment. Second, by vertically setting the loading block above the radial direction of the bearing under test, the loading boss can always stably abut against the surface of the bearing outer ring. During the testing process, the loading position does not need to be frequently adjusted to cover the entire outer diameter surface of the bearing outer ring, effectively avoiding the detection blind spots that may exist in traditional local testing methods, and improving the comprehensiveness and accuracy of key indicators such as the dimensional accuracy and surface roughness of the bearing outer ring. Third, this solution does not rely on complex multi-station testing equipment or high-precision customized fixtures. The loading block has a simple structure and strong versatility, which can adapt to the testing needs of various bearing specifications, significantly reducing equipment procurement and maintenance costs, while simplifying the testing operation process and reducing labor and time costs, providing an economical and efficient solution for enterprises to carry out batch bearing testing. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0028] Figure 2 This is a partial enlarged view of the loading module in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the structure of the loading block in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the structure of the fixing frame according to an embodiment of the present invention. Detailed Implementation

[0031] An embodiment of the present invention provides a test bench for flexible bearings of harmonic reducers, such as... Figure 1-4 As shown: The system includes a frame (not shown), which serves as a support structure made of rigid material to ensure stability. The frame (not shown) houses a drive module 2, a loading module 3, and a data acquisition module (not shown). The drive module 2 is connected to the bearing under test 5 and drives its rotation. The drive module 2 typically includes existing technology components such as a motor and transmission mechanism, capable of simulating speed and torque under actual working conditions. The loading module 3 rests against the bearing under test 5 and applies a loading force to test its performance under load. The data acquisition module (not shown) collects various test data of the bearing under test 5 during the testing process, such as vibration, temperature, and displacement parameters. The data acquisition module (not shown) can integrate sensors and data processing units, which are common technologies in this field.

[0032] The loading module 3 includes a loading block 31, a loading ring 32, and a force-applying block 33. One side of the loading block 31 has a nesting groove 312 for the loading ring 32 to nest and engage. The other side of the loading block 31 has a loading boss 313 that abuts against the bearing 5 under test. The addition of the loading block 31 avoids measurement errors caused by direct contact between the loading ring 32 and the bearing 5 under test. The loading block 31 is positioned relatively above the bearing 5 under test, allowing it to better abut against the bearing 5 using its own weight, applying radial loading force to improve measurement stability and accuracy. The force-applying block 33 is connected to an external load. The two ends of the loading ring 32 are respectively fitted onto the force-applying block 33 and the loading block 31, facilitating the application of force to the bearing 5 under test via an external force source.

[0033] The loading module 3 also includes two fixed frames 34, symmetrically arranged on both sides of the loading block 31 and connected to the frame (not shown in the figure). Each fixed frame 34 is equipped with a sliding guide rail 341. The loading block 31 is provided with a limit protrusion 311 corresponding to each fixed frame 34, which cooperates with the sliding guide rail 341. This structure can both cooperate with the force application block 33 to move the loading block 31 within the sliding guide rail 341 to adjust the magnitude of the loading force, and prevent the loading block 31 from shifting position during the test, ensuring the accuracy of the direction and point of application of the loading force. The force application block 33 is provided with a force application rod 331 for connecting an external load. For example, the force application rod 331 can be equipped with a hook for hanging weights, or connected to a servo motor to achieve more precise load control, thereby adapting to different testing requirements. The nesting groove 312 on the side of the loading block 31 facing the loading ring 32 is used to nest the loading ring 32. The end face of the loading boss 313 on the side facing the bearing 5 to be tested is set with an arc surface, which matches the outer diameter surface of the outer ring of the bearing 5 to be tested, forming a better contact relationship and further improving the measurement accuracy.

[0034] The arc-shaped area of ​​the loading boss 313 facing the bearing 5 under test is obtained in the following way:

[0035] S1. Establish a geometric model by constructing the assembly model of the flexible wheel, rigid wheel, wave generator, and experimental flexible bearing of the harmonic reducer based on the input parameters and data.

[0036] S2, Setting up the finite element model, step S2 is achieved through the following steps:

[0037] S21, Material Definition: Set the material parameters for the flexible wheel, rigid wheel, wave generator, and experimental flexible bearing;

[0038] S22, Mesh generation: Mesh generation is performed on the assembly model of the flexible wheel, rigid wheel, wave generator, and experimental flexible bearing;

[0039] S23, Contact Settings: Define five sets of contact pairs in the test flexible bearing, where the rolling elements, inner ring, outer ring, outer surface of the wave generator, and tooth surface are in contact with each other, and set the friction coefficient corresponding to each contact pair;

[0040] S24, Load and constraint settings: Apply torque loads to the wave generator, the outer surface of the rigid wheel, and the flange of the flexible wheel in the CAE analysis software.

[0041] S3, the loading wrap angle is obtained by solving the CAE analysis software, and the contact area between the loading block 31 and the outer ring of the bearing is confirmed by the loading wrap angle.

[0042] The contact area obtained through step S3 is the arc-shaped area of ​​the loading boss 313 facing the bearing 5 to be tested.

[0043] During operation, the drive module 2 starts and drives the bearing under test 5 to rotate eccentrically, simulating the actual load state of the bearing in the harmonic reducer. An external load is applied through the force rod 331 on the force application block 33, and the force is transmitted to the loading block 31 via the loading ring 32. The loading block 31, using its own weight and the arc surface design of the loading boss 313, applies a stable radial loading force to the bearing under test 5. The fixed frame 34 and the sliding guide rail 341 guide the movement of the loading block 31, and the limiting boss 311 ensures that the loading block 31 does not deviate, thus ensuring the accurate application of the loading force. The data acquisition module (not shown in the figure) collects data such as bearing vibration and temperature in real time during the test for subsequent analysis and evaluation of bearing performance. The entire device has a reasonable structure, is easy to operate, and can effectively improve the reliability and repeatability of the test.

[0044] The above embodiments are merely one preferred embodiment of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included within the protection scope of the present invention.

Claims

1. A flexible bearing test bench for harmonic reducers, comprising a frame, wherein a drive module, a loading module, and a data acquisition module are mounted on the frame; the drive module is connected to the bearing under test and is used to drive the bearing under test to rotate eccentrically; the loading module abuts against the bearing under test and applies a loading force to the bearing under test; and the data acquisition module collects various test data of the bearing under test during the testing process, characterized in that: The loading module includes a loading block and a loading ring belt. One side of the loading block is used to cooperate with the loading ring belt, and the other side of the loading block abuts against the bearing under test. The loading force applied by the loading block to the bearing under test is a radial loading force, and the loading block is located above the bearing under test. The side of the loading block facing the loading ring belt is provided with a nesting groove for the loading ring belt to be nested therein. The side of the loading block facing the bearing under test is provided with a loading boss that abuts against the bearing under test. The end face of the loading boss corresponding to the outer diameter surface of the outer ring of the bearing under test is arranged in a corresponding arc surface. The contact area and angle between the loading boss and the outer ring of the bearing under test are consistent with the load area of ​​the bearing under test in the harmonic reducer.

2. The test bench for flexible bearings of harmonic reducers according to claim 1, characterized in that: The loading module also includes a force-applying block connected to an external load, and the two ends of the loading ring are respectively sleeved on the force-applying block and the loading block.

3. The test bench for flexible bearings of harmonic reducers according to claim 2, characterized in that: The loading module also includes two fixed frames connected to the frame and symmetrically arranged on both sides of the loading block. Each fixed frame is provided with a sliding guide rail, and the loading block is provided with a limiting protrusion that cooperates with the sliding guide rail for each fixed frame on each side.

4. The test bench for flexible bearings of harmonic reducers according to claim 2, characterized in that: The force-applying block is equipped with a force-applying rod for connecting the load.

5. A method for calculating the contact area between the loading block and the bearing to be tested on a test bench for a flexible bearing of a harmonic reducer according to any one of claims 1-4, comprising the following steps: S1. Establish a geometric model. By inputting parameters and data, construct the assembly model of the flexible wheel, rigid wheel, wave generator, and experimental flexible bearing of the harmonic reducer. S2, Set up the finite element model; S3, the loading wrap angle is obtained by solving the CAE analysis software, and the contact area between the loading block and the outer ring of the bearing is confirmed by the loading wrap angle.

6. The method for calculating the contact area between the loading block and the bearing to be tested according to claim 5, characterized in that: Step S2 is achieved through the following steps: S21, Material Definition: Set the material parameters for the flexible wheel, rigid wheel, wave generator, and experimental flexible bearing; S22, Mesh generation: Mesh generation is performed on the assembly model of the flexible wheel, rigid wheel, wave generator, and experimental flexible bearing; S23, Contact Settings: Define five sets of contact pairs in the test flexible bearing, where the rolling elements, inner ring, outer ring, outer surface of the wave generator, and tooth surface are in contact with each other, and set the friction coefficient corresponding to each contact pair; S24, Load and constraint settings: Apply torque loads to the wave generator, the outer surface of the rigid wheel, and the flange of the flexible wheel in the CAE analysis software.

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