A wind power bearing fretting wear scale model test device and test method

Abstract

The application discloses a kind of wind power bearing micro-wear scale-down test device and test method, including test platform, load applying mechanism, tangential driving mechanism, upper test sample clamping mechanism and sensing detection component, load applying mechanism is used to vertically normal load to upper test sample;Tangential driving mechanism is used to bear lower test sample and drive lower test sample to reciprocate in horizontal direction relative to upper test sample;Upper test sample clamping mechanism is connected with the output end of load applying mechanism, and is slidably suspended above test platform along vertical direction;Sensing detection component includes pressure sensor and friction force sensor.The device and method can accurately simulate the linear contact micro-motion condition between cylindrical roller and raceway, while achieving the buffer application of normal load, independent measurement of normal and tangential load, and high-precision closed-loop control of tangential displacement.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, specifically to a scaled-down test device and method for fretting wear of wind turbine bearings. Background Technology

[0002] The main bearing of a wind turbine is a core component that supports the weight of the rotating impeller and hub, and bears and transmits complex loads. Its reliability directly affects the safe and stable operation and service life of the entire turbine. During the installation of the wind turbine blades, because the impeller is stationary or rotating at low speed, the rollers and raceways inside the main bearing are subjected to high contact pressure. At the same time, affected by factors such as installation vibration, wind load disturbance, and unbalanced torque, reciprocating relative sliding with extremely small amplitude (usually several micrometers to hundreds of micrometers) occurs between the contact interfaces, which is the phenomenon of "fretting wear". Fretting wear causes oxidation, fatigue spalling, and surface damage to the contact surface material, seriously shortening the bearing's service life and is one of the main failure modes of wind turbine main bearings.

[0003] Currently, research on bearing fretting wear mainly relies on two types of methods: one is actual machine testing, which involves conducting tests directly on full-size wind turbine main bearings. This method is extremely costly, time-consuming, and the operating parameters are difficult to control precisely. The other is general-purpose pin-disc or ball-plate fretting wear testing machines. These types of equipment have a single contact pair form and cannot truly simulate the line contact condition between cylindrical rollers and the outer raceway of the bearing. Moreover, most of them lack buffer and vibration isolation designs for wind turbine installation conditions, resulting in significant system vibration during load application, which affects the accuracy of test data.

[0004] In addition, existing fretting wear testing machines generally have the following shortcomings: First, there is a lack of elastic buffer between the load application system and the sensor, resulting in a large impact load when the electric or hydraulic cylinder is directly driven, and significant fluctuations in the pressure sensor readings; Second, the friction force measurement path and the normal load transmission path are coupled, leading to a large error in the calculation of the friction coefficient; Third, the upper sample clamp does not have a contact angle adjustment function, and when there are slight errors in sample processing or installation, it is impossible to ensure good contact between the upper and lower sample surfaces; Fourth, the tangential displacement control accuracy is insufficient, making it difficult to meet the requirement of accurate reproduction of the fretting wear characteristic displacement range (micrometer level). Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a scaled-down testing device and method for fretting wear of wind turbine bearings.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A scaled-down test device for fretting wear of wind turbine bearings, comprising: Test platform; The load application mechanism is fixed above the test platform and is used to apply a vertical normal load to the upward specimen; The tangential drive mechanism, set on the test platform, is used to support the lower specimen and drive the lower specimen to reciprocate in the horizontal direction relative to the upper specimen, so as to generate tangential micro-displacement. The upper specimen clamping mechanism is connected to the output end of the load application mechanism and is slidably suspended above the test platform in the vertical direction. It is used to clamp the upper specimen and transfer the normal load to the contact interface. The sensing and detection assembly includes a pressure sensor for detecting the normal load on the upper sample and a friction force sensor for detecting the tangential friction force on the upper sample. The loading direction of the load application mechanism is perpendicular to the motion direction of the tangential drive mechanism.

[0007] Furthermore, the load application mechanism includes a support plate, a lower plate of the electric cylinder, and an electric cylinder. The support plate is fixed on the test platform, the lower plate of the electric cylinder is installed on the top of the support plate, and the electric cylinder is fixed on the lower plate of the electric cylinder. The output end of the electric cylinder extends vertically downward through the lower plate of the electric cylinder. The upper sample clamping mechanism is connected to the support plate through a T-shaped adapter block. The T-shaped adapter block and the support plate are slidably engaged through a Z-direction guide rail and a Z-direction slider.

[0008] Furthermore, a buffer force transmission mechanism is provided between the output end of the electric cylinder and the upper sample clamping mechanism. The buffer force transmission mechanism includes an upper spring plate, a lower spring plate, and a heavy-duty spring. The upper spring plate is fixedly connected to the output end of the electric cylinder, the heavy-duty spring is installed between the upper spring plate and the lower spring plate, and the pressure sensor is fixed below the lower spring plate.

[0009] Furthermore, the buffer force transmission mechanism is characterized by including multiple linear bearings and multiple locking bolts. The linear bearings are fixedly mounted on the upper plate of the spring, the locking bolts pass through the linear bearings and are connected to the lower plate of the spring, the heavy-duty spring is fitted on the locking bolts and limited by the locking bolts, and the output end of the electric cylinder is fixedly connected to the upper plate of the spring through the electric cylinder nut.

[0010] Furthermore, the upper sample clamping mechanism includes a lower plate of the T-shaped transition block connected below the T-shaped transition block. An X-direction guide rail and an X-direction slider are provided below the lower plate of the T-shaped transition block. An upper sample clamping connecting plate is fixed below the X-direction slider. An upper sample clamp is provided on the upper sample clamping connecting plate. The friction sensor is installed between the upper sample fixture connecting plate and the friction sensor connecting plate. The X-direction guide rail and the X-direction slider allow the upper sample to move freely along the X-direction with the upper sample fixture, so as to transmit the tangential friction force to the friction sensor.

[0011] Furthermore, the upper sample fixture is hinged to an upper sample fixture attachment via a pin. The upper sample fixture attachment can swing around the pin in the Y direction to adjust the parallelism of the contact surfaces of the upper and lower samples. After adjustment, the upper sample fixture attachment is fixed by a locking device.

[0012] Furthermore, the tangential drive mechanism includes a slide table, a lower slide table plate, and an upper slide table plate. The lower slide table plate is fixed to the test platform, the slide table is mounted on the test platform via the lower slide table plate, the upper slide table plate is fixed to the top of the slide table, and the lower sample is mounted on the upper slide table plate via a lower sample clamp. The slide table is driven by a servo motor and performs controllable reciprocating motion in the horizontal direction.

[0013] Furthermore, it also includes a displacement detection component, which includes a grating fixedly mounted on the support plate and a grating ruler pasted on the upper plate of the slide. The grating and the grating ruler work together to read the displacement data of the slide in real time, and use the displacement feedback signal to perform closed-loop control of the reciprocating motion of the slide.

[0014] This invention also provides a test method for scaled-down testing of fretting wear in wind turbine bearings, which employs a test apparatus and includes the following steps: S1. Install the sample: Install and lock the upper sample in the upper sample clamping mechanism, install and lock the lower sample in the tangential drive mechanism, and adjust the parallelism of the contact surfaces of the upper and lower samples. S2. Apply load: Set the target load value, start the load application mechanism to drive the upper sample to move vertically downward until it contacts the lower sample. When the pressure sensor reading reaches the target load value, automatically stop pressurizing and maintain load stability. S3. Perform fretting wear test: preset displacement amplitude, frequency and number of cycles, start the tangential drive mechanism to reciprocate in the horizontal direction, drive the lower sample to generate tangential fretting displacement relative to the upper sample, and realize fretting wear; S4. Real-time data acquisition: While the test is being conducted, the pressure sensor acquires the normal load in real time, the friction sensor acquires the tangential friction force in real time, the friction coefficient is calculated, and the displacement time history curve of the tangential drive mechanism is recorded simultaneously. S5. End of test: When the reciprocating motion of the tangential drive mechanism reaches the preset number of cycles, the test will automatically stop, and the upper and lower samples will be removed for subsequent analysis.

[0015] Furthermore, in step S2, the load applied by the load application mechanism is buffered by the heavy-duty spring in the buffer force transmission mechanism and then transmitted to the pressure sensor. The external control system performs dynamic closed-loop control of the load application mechanism based on the feedback signal of the pressure sensor to maintain the stability of the normal load during the test.

[0016] The present invention has the following beneficial effects: The present invention provides a scaled-down test device and test method for fretting wear of wind turbine bearings: (1) Cylindrical rollers are used as upper specimens and bearing outer ring cut specimens are used as lower specimens to form a line contact pair that is consistent with the actual contact form of wind turbine main bearings. The obtained tribological data has direct guiding significance for the design optimization and installation process improvement of wind turbine bearings, and makes up for the defect of mismatch of contact form of general micro-motion testing machine. (2) A buffer force transmission mechanism consisting of a heavy-duty spring, a linear bearing and a plug bolt is set between the electric cylinder and the pressure sensor to effectively absorb the impact vibration at the output end of the electric cylinder, ensure the smoothness of the normal load application process, and significantly reduce the dynamic measurement error of the pressure sensor. (3) The upper sample clamping mechanism is specially equipped with X-direction guide rail and slider, so that the upper sample has the degree of freedom in the tangential direction. The tangential friction force is measured by an independent friction force sensor, which is completely decoupled from the normal load transmission path, fundamentally eliminating the load coupling error. The friction coefficient calculation result is accurate and reliable. (4) The upper sample fixture attachment is hinged by a pin and can swing in the Y direction to compensate for sample processing and installation errors, ensure that the upper and lower sample contact surfaces are fully fitted, and improve the repeatability of the test and the uniformity of contact stress distribution. (5) The slide table is driven by a servo motor and combined with grating displacement feedback to achieve precise closed-loop control of micron-level tangential displacement, which can accurately reproduce the micro-motion wear characteristics and ensure the accuracy and consistency of test parameters.

[0017] (6) By setting pressure sensors, friction sensors and gratings, dynamic adjustment of load, real-time monitoring of load and friction and precise control of slide movement range can be realized. After the test, material analysis of the sample can be carried out to analyze the micro-motion wear phenomenon under different working conditions and provide solutions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the upper sample clamping mechanism in this invention; Figure 3 This is a schematic diagram of the buffer force transmission mechanism in this invention; Figure 4 This is a schematic diagram of the tangential drive mechanism in this invention; Figures 1 to 4The reference numerals in the attached figures represent: 1-test platform, 2-upper specimen, 3-lower specimen, 4-pressure sensor, 5-friction sensor, 10-support plate, 11-lower plate of electric cylinder, 12-electric cylinder, 13-T-type adapter block, 14-Z-direction guide rail, 15-Z-direction slider, 16-upper plate of spring, 17-lower plate of spring, 18-heavy-load spring, 19-linear bearing, 20-plug bolt, 21-electric cylinder nut, 30-lower plate of T-type adapter block, 31-X-direction guide rail, 32-X-direction slider, 33-upper specimen fixture connecting plate, 34-upper specimen fixture, 35-friction sensor connecting plate, 36-pin, 37-upper specimen fixture attachment, 38-lower specimen fixture, 40-slide table, 41-lower plate of slide table, 42-upper plate of slide table, 50-grating, 52-grating fixing plate. Detailed Implementation

[0019] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0020] like Figures 1 to 4 As shown, a scaled-down test device for fretting wear of wind turbine bearings includes a test platform 1, a load application mechanism, a tangential drive mechanism, an upper sample clamping mechanism, a sensing and detection component, and a displacement detection component.

[0021] The load application mechanism is fixed above the test platform 1 and is used to apply a vertical normal load to the upper specimen 2. The tangential drive mechanism is mounted on the test platform 1 and is used to support the lower specimen 3 and drive it to reciprocate horizontally relative to the upper specimen 2, thereby generating tangential micro-displacement. The upper specimen clamping mechanism is connected to the output end of the load application mechanism and is slidably suspended vertically above the test platform 1, used to clamp the upper specimen 2 and transfer the normal load to the contact interface. The sensing and detection components include a pressure sensor 4 for detecting the normal load on the upper specimen 2 and a friction force sensor 5 for detecting the tangential friction force on the upper specimen 2. The loading direction of the load application mechanism is perpendicular to the movement direction of the tangential drive mechanism.

[0022] Among them, the upper sample 2 is a cylindrical roller, and the lower sample 3 is a cuboid sample cut from the outer ring of the bearing. The upper sample 2 and the lower sample 3 form a line contact to simulate the contact condition between the roller and the raceway of the wind turbine main bearing.

[0023] Test platform 1 serves as the mounting base for the entire machine. It is made of high-rigidity cast iron or steel base plate, and the surface is precision milled to ensure the flatness and perpendicularity of each mounting surface. Test platform 1 is equipped with T-slots to facilitate the flexible positioning and fixing of each component.

[0024] The load application mechanism is fixed above the test platform 1 and is used to apply a vertical normal load to the upward sample 2. The load application mechanism includes a support plate 10, a lower plate 11 for the electric cylinder, and an electric cylinder 12. Preferably, there are two support plates 10, which are symmetrically fixed on both sides of the test platform 1. During installation, the perpendicularity of the support plates 10 to the test platform 1 must be strictly ensured. The lower plate 11 for the electric cylinder is installed on top of the support plate 10, forming a portal frame structure, which provides a stable installation foundation for the electric cylinder 12. The electric cylinder 12 is preferably a servo electric cylinder. The electric cylinder 12 is fixedly installed on the lower plate 11 by a flange. The output end of the electric cylinder 12 extends vertically downward through the lower plate 11. The maximum output force of the electric cylinder 12 is set according to the test requirements, and can usually cover a load range of 100N to 5000N to meet the simulation requirements of different wind turbine bearing installation conditions. The electric cylinder 12 adjusts the magnitude and speed of the output force through the controller. When its output shaft moves downward, it transmits the load sequentially to the upper spring plate 16 and the subsequent buffer force transmission mechanism, and finally applies it to the contact interface between the upper sample 2 and the lower sample 3.

[0025] The upper sample clamping mechanism is connected to the support plate 10 via a T-shaped adapter block 13. The T-shaped adapter block 13 and the support plate 10 are slidably engaged via a Z-direction guide rail 14 and a Z-direction slider 15. The Z-direction guide rail 14 provides guidance for the vertical sliding of the upper sample clamping mechanism. The T-shaped adapter block 13 spans across the Z-direction sliders 15 on both sides, and the Z-direction sliders 15 are embedded in the Z-direction guide rail 14, allowing the T-shaped adapter block 13 to slide smoothly in the vertical direction (Z direction). The upper end face of the T-shaped adapter block 13 contacts the pressure sensor 4, and its lower part is connected to the X-direction motion component of the upper sample clamping mechanism via a lower plate 30 of the T-shaped adapter block.

[0026] In this invention, a buffer force transmission mechanism is provided between the output end of the electric cylinder 12 and the upper sample clamping mechanism. The buffer force transmission mechanism eliminates the impact vibration generated by the electric cylinder 12 during the application and holding of the load, and prevents the vibration from interfering with the reading of the pressure sensor 4 through the load transmission chain.

[0027] The buffer force transmission mechanism includes an upper spring plate 16, a lower spring plate 17, a heavy-duty spring 18, multiple linear bearings 19, and multiple locking bolts 20. The lower end of the output shaft of the electric cylinder 12 passes through the lower spring plate 11 and is fixedly connected to the upper spring plate 16 via the electric cylinder nut 21, thereby transmitting the output force of the electric cylinder 12 to the upper spring plate 16. The upper spring plate 16 is fixedly connected to the output end of the electric cylinder 12. The heavy-duty spring 18 is installed between the upper spring plate 16 and the lower spring plate 17, and the pressure sensor 4 is fixed below the lower spring plate 17. The linear bearings 19 are fixedly installed on the upper spring plate 16, and the locking bolts 20 pass through the linear bearings 19 and connect to the lower spring plate 17. The heavy-duty spring 18 is fitted onto the locking bolts 20 and is limited by the locking bolts 20.

[0028] Preferably, six linear bearings 19 are evenly arranged on the upper spring plate 16, with the axis of each linear bearing 19 parallel to the vertical direction (Z direction). Six bolts 20 pass through the corresponding linear bearings 19, with their lower ends threadedly connected to the lower spring plate 17 and their upper ends locked in place by nuts. The linear bearings 19 provide precise vertical guidance for the bolts 20, ensuring that the upper spring plate 16 and the lower spring plate 17 remain parallel at all times, while preventing lateral displacement of the upper spring plate 16 relative to the lower spring plate 17.

[0029] The heavy-duty spring 18 is fitted onto the stop bolt 20, with its upper end pressing against the lower surface of the upper spring plate 16 and its lower end pressing against the upper surface of the lower spring plate 17. During installation, by adjusting the tightness of the nut at the upper end of the stop bolt 20, an appropriate preload can be applied to the heavy-duty spring 18, ensuring that the spring is under compression from the outset. This eliminates system gaps and reduces impact vibrations during the initial application of load. The stiffness and preload of the heavy-duty spring 18 should be selected according to the test load range. It is recommended that the spring stiffness be such that the spring deformation under the maximum working load does not exceed 30% of the spring's free length, ensuring both buffering effect and sufficient load transfer capacity.

[0030] A pressure sensor 4 is fixedly mounted on the lower surface of the lower spring plate 17. When the electric cylinder 12 applies downward force, the load is transmitted through the path of the upper spring plate 16 → heavy-duty spring 18 → lower spring plate 17 → pressure sensor 4. During this process, the heavy-duty spring 18 plays an elastic filtering role, effectively attenuating the high-frequency impact components generated by the electric cylinder 12, so that the pressure sensor 4 can obtain a stable and reliable load reading.

[0031] In this invention, the upper sample clamping mechanism performs the dual functions of transferring the normal load to the upper sample 2 and independently measuring the tangential friction force. It is the core mechanism for achieving decoupled measurement of normal and tangential loads in this invention. The upper sample clamping mechanism is connected to the output end of the load application mechanism and is slidably suspended above the test platform 1 in the vertical direction. It is used to clamp the upper sample 2 and transfer the normal load to the contact interface.

[0032] The upper sample clamping mechanism includes a lower plate 30 of the T-shaped transition block connected below the T-shaped transition block 13. An X-direction guide rail 31 and an X-direction slider 32 are provided below the lower plate 30 of the T-shaped transition block. An upper sample clamping fixture connecting plate 33 is fixed below the X-direction slider 32. An upper sample clamping fixture 34 is provided on the upper sample clamping fixture connecting plate 33. The T-shaped adapter block 13 has a "T"-shaped cross-section. The wing plates at both ends are embedded in the Z-direction guide rails 14 on the two side support plates 10 via Z-direction sliders 15, so that the entire upper sample clamping mechanism can only move in the vertical direction (Z direction), and the movement in other directions is constrained. This guiding design ensures that the normal load is always transmitted in the vertical direction, preventing the upper sample 2 from shifting laterally during loading.

[0033] The lower plate 30 of the T-shaped adapter block is bolted to the lower end face of the T-shaped adapter block 13. An X-direction guide rail 31 and a friction sensor connecting plate 35 are mounted on the lower surface of the lower plate 30. The friction sensor 5 is installed between the upper sample fixture connecting plate 33 and the friction sensor connecting plate 35. The X-direction guide rail 31 and the X-direction slider 32 allow the upper sample 2 to move freely along the X-direction with the upper sample fixture 34, thereby transmitting the tangential friction force to the friction sensor 5.

[0034] The function of the X-direction guide rail 31 and the X-direction slider 32 is that when tangential micro-movement occurs between the upper sample 2 and the lower sample 3, the tangential friction force drives the upper sample 2 and the upper sample clamp 34 to make a slight displacement tendency along the X direction. This tangential force is transmitted to the friction force sensor 5 through the upper sample clamp connecting plate 33, and is independently measured by the friction force sensor 5. Since the X-direction guide rail 31 and the X-direction slider 32 completely release the tangential degree of freedom, the tangential friction force will not be transmitted through the normal load transmission path, thus realizing the complete decoupling measurement of the normal load and the tangential friction force, avoiding the problem of mutual interference between the two in traditional testing machines.

[0035] The upper sample clamp 34 is the main clamp for holding the upper sample 2. It has a pin 36 hole on its side and is hinged to the upper sample clamp attachment 37 through the pin 36. The upper sample clamp attachment 37 can swing slightly around the pin 36 in the Y direction (the horizontal direction perpendicular to the tangential micro-movement direction) to adjust the parallelism of the contact surface between the upper sample 2 and the lower sample 3. After adjustment, the upper sample clamp attachment 37 is fixed by the locking device.

[0036] The reason for setting an adjustable swing angle for the upper sample fixture attachment 37 is that during actual sample processing, there may be a slight angular deviation between the axial direction of the upper sample 2 (cylindrical roller) and the surface of the lower sample 3 (bearing outer ring cut sample). If no adjustment is made, the contact area will only have point contact or edge contact, and the required uniform line contact cannot be formed. By swinging the upper sample fixture attachment 37 around the pin 36, the above-mentioned angular deviation can be compensated, so that the upper sample 2 and the lower sample 3 can achieve sufficient line contact, ensuring uniform contact stress distribution and improving the repeatability of test results. After the angle adjustment is completed, the upper sample fixture attachment 37 is fixed by the locking screw to prevent the angle from changing during the test.

[0037] The upper sample 2 is installed in the positioning groove inside the upper sample fixture attachment 37. After installation, the upper sample 2 is locked by the lateral locking screw to prevent the upper sample 2 from sliding out along its axis during the test.

[0038] In this invention, the tangential drive mechanism is used to drive the lower sample 3 to move horizontally back and forth relative to the upper sample 2 in a precise and controllable manner, so as to simulate the fretting wear condition between the roller and the raceway during the installation of the wind turbine main bearing.

[0039] The tangential drive mechanism includes a slide table 40, a lower slide table plate 41, and an upper slide table plate 42. The lower slide table plate 41 is fixed to the test platform 1, and the slide table 40 is bolted to the test platform 1 via the lower slide table plate 41. The upper slide table plate 42 is fixed to the top of the slide table 40 and moves horizontally synchronously with the slide table 40. The slide table 40 integrates a servo motor and a lead screw guide mechanism. The lead screw has a lead of 5mm and a repeatability of not less than 0.01mm. The slide table 40 is driven by the servo motor and performs controllable reciprocating motion in the horizontal direction.

[0040] The lower sample clamp 38 is installed and fixed on the upper surface of the slide plate 42. The lower sample 3 is embedded in the positioning groove of the lower sample clamp 38 and fixed by locking screws. During installation, it is necessary to ensure that the upper surface of the lower sample 3 is level, so that its contact line with the upper sample 2 is parallel to the X direction (i.e., the tangential micro-motion direction).

[0041] In this invention, the device further includes a displacement detection component, which comprises a grating 50 fixedly mounted on the support plate 10 via a grating fixing plate 52 and a grating ruler attached to the upper slide plate 42. The grating ruler is attached to a corresponding position on the side of the upper slide plate 42 and moves horizontally together with the slide 40. The grating 50 and the grating ruler work together to read the displacement data of the slide 40 in real time, and use the displacement feedback signal for closed-loop control of the reciprocating motion of the slide 40.

[0042] The grating 50 and the grating ruler together constitute a high-precision linear displacement sensor. The grating 50 reads the position information of the grating ruler in real time and outputs the current displacement signal of the slide 40 to the controller. The controller compares the displacement feedback value with the set displacement command to form a position closed-loop control loop, dynamically correcting the displacement of the slide 40, thereby accurately maintaining the preset displacement amplitude throughout the test and ensuring the repeatability accuracy of the fretting wear displacement. The resolution of the grating 50 is preferably not less than 1μm to meet the accurate measurement requirements of the fretting wear characteristic displacement range (typically 5μm to 500μm).

[0043] This invention also provides a test method for scaled-down testing of fretting wear in wind turbine bearings, using a test apparatus and including the following steps: S1. Install the sample: Install and lock the upper sample 2 in the upper sample clamping mechanism, install and lock the lower sample 3 in the tangential drive mechanism, and adjust the parallelism of the contact surfaces of the upper sample 2 and the lower sample 3. Specifically, based on the model of the wind turbine main bearing to be simulated, upper sample 2 and lower sample 3 are prepared. Upper sample 2 is a cylindrical roller, and its material, heat treatment state, and surface roughness are consistent with those of the actual bearing roller. Lower sample 3 is a cuboid sample cut from the outer ring of the bearing, and the cut surface (i.e., the raceway surface) is machined to a surface roughness Ra≤0.25 to truly reflect the contact surface state between the wind turbine main bearing roller and the raceway. Upper sample 2 and lower sample 3 form a line contact, and the contact form is consistent with that of an actual cylindrical roller bearing.

[0044] During installation, first place the lower sample 3 into the positioning groove of the lower sample holder 38, with the raceway surface of the lower sample 3 facing upwards, and fix the lower sample 3 with the locking screws. Next, loosen the locking screws of the upper sample holder attachment 37, and put the upper sample 2 into the positioning groove of the upper sample holder attachment 37, without locking it yet; manually operate the device to slowly bring the upper sample 2 into contact with the lower sample 3, observe the contact line distribution between the upper sample 2 and the lower sample 3 visually or with a dial indicator, and adjust the swing angle of the upper sample holder attachment 37 appropriately until the contact line is evenly distributed along the entire contact length. Then tighten the fixing screws of the upper sample holder attachment 37, and then tighten the axial locking screws of the upper sample 2 to complete the installation.

[0045] S2. Apply load: Set the target load value, start the load application mechanism to drive the upper sample 2 to move vertically downward until it contacts the lower sample 3. When the reading of the pressure sensor 4 reaches the target load value, automatically stop pressurizing and maintain load stability. The load applied by the load application mechanism is buffered by the heavy-duty spring 18 in the buffer force transmission mechanism and then transmitted to the pressure sensor 4. The external control system performs dynamic closed-loop control of the load application mechanism based on the feedback signal of the pressure sensor 4 to maintain the stability of the normal load during the test.

[0046] Specifically, a target normal load value is set in the controller, and the electric cylinder 12 is started. The output shaft of the electric cylinder 12 moves slowly downward, driving the upper spring plate 16 downward through the electric cylinder nut 21. The heavy-duty spring 18 is compressed accordingly, and the load is buffered by the heavy-duty spring 18 and then transferred to the lower spring plate 17, which in turn acts on the pressure sensor 4. The real-time reading of the pressure sensor 4 is fed back to the controller through the data acquisition system. When the reading reaches the set target load value, the controller sends a stop command to the electric cylinder 12, and the output shaft of the electric cylinder 12 stops moving, maintaining the current load stability of the system. If load fluctuations are caused by changes in system stiffness during the test (such as changes in contact area due to wear of the contact surface), the controller can dynamically compensate for the load by adjusting the output displacement of the electric cylinder 12, maintaining the constant normal load of the contact interface, and realizing a true constant load fretting wear test.

[0047] S3. Perform fretting wear test: preset displacement amplitude, frequency and number of cycles, start the tangential drive mechanism to reciprocate in the horizontal direction, drive the lower sample 3 to generate tangential fretting displacement relative to the upper sample 2, and realize fretting wear; Specifically, the tangential fretting parameters are set in the control software: displacement amplitude, motion frequency, and total number of cycles. The displacement amplitude setting should cover the three typical areas of fretting wear: the adhesion zone, the mixed zone, and the sliding zone; a range of 5μm to 500μm is recommended. The motion frequency setting range is 0.1Hz to 10Hz to simulate different disturbance frequencies during actual installation operations. The total number of cycles is set according to the test objective, typically [missing value]. to Second-rate.

[0048] After the parameters are set, the tangential drive mechanism is activated. The servo motor drives the slide 40 to perform horizontal reciprocating motion according to the set displacement amplitude and frequency, causing the lower sample 3 to produce tangential micro-displacement relative to the stationary upper sample 2, thereby achieving micro-wear at the contact interface between the upper sample 2 and the lower sample 3. The grating 50 collects the actual displacement of the slide 40 in real time, and the accuracy of the displacement amplitude is ensured through closed-loop control.

[0049] S4. Real-time data acquisition: While the test is being conducted, the pressure sensor 4 acquires the normal load in real time, and the friction sensor 5 acquires the tangential friction force in real time. The friction coefficient is calculated, and the displacement time history curve of the tangential drive mechanism is recorded simultaneously. Specifically, while the fretting wear test is being conducted, the data acquisition system simultaneously acquires the following data at a sampling frequency of not less than 100Hz: the normal load output by the pressure sensor 4, the tangential friction force output by the friction sensor 5, and the displacement curve of the slide table 40 output by the grating 50.

[0050] The controller calculates the friction coefficient in real time and displays the friction coefficient-cycle count curve and the tangential force-displacement hysteresis loop curve on the control interface. The area of ​​the hysteresis loop represents the energy dissipated at the contact interface in each fretting cycle and is an important basis for judging the fretting wear state (adhesion, partial sliding, or complete sliding). All collected data is stored in real time to an external computer for subsequent analysis.

[0051] S5. End of test: When the reciprocating motion of the tangential drive mechanism reaches the preset number of cycles, the test will automatically stop, and the upper sample 2 and the lower sample 3 will be taken out for subsequent analysis.

[0052] Specifically, when the number of reciprocating cycles of the slide table 40 reaches the preset value N, the control system automatically stops the movement of the slide table 40 and controls the electric cylinder 12 to slowly unload, causing the upper sample 2 to disengage from the lower sample 3. After the upper sample 2 is vertically raised to a safe height by manual adjustment, the upper sample 2 and the lower sample 3 are taken out in sequence, and the following material analyses are performed according to the established plan: (a) the wear morphology of the sample surface is observed and analyzed using a stereomicroscope and a white light interferometer; (b) the microstructure and elemental content of the sample surface are analyzed using a scanning electron microscope combined with EDS; (c) the valence state of the elements on the sample surface is analyzed using X-ray photoelectron spectroscopy. By comprehensively comparing the tribological data and material analysis results under different working conditions (load, displacement amplitude, frequency, etc.), the influence law of each working condition parameter on the fretting wear behavior is revealed, providing quantitative data support for the optimized design and installation process improvement of wind turbine bearings.

[0053] Additionally, it should be noted that components not described in detail in this article are existing technologies.

[0054] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A scaled-down test device for fretting wear of wind turbine bearings, characterized in that, include: Experimental platform (1); The load application mechanism is fixed above the test platform (1) and is used to apply a vertical normal load to the upward specimen (2); A tangential drive mechanism is set on the test platform (1) to carry the lower specimen (3) and drive the lower specimen (3) to reciprocate in the horizontal direction relative to the upper specimen (2) to generate tangential micro-displacement. The upper sample clamping mechanism is connected to the output end of the load application mechanism and is slidably suspended above the test platform (1) in the vertical direction. It is used to clamp the upper sample (2) and transfer the normal load to the contact interface. The sensing and detection assembly includes a pressure sensor (4) for detecting the normal load on the upper sample (2) and a friction sensor (5) for detecting the tangential friction force on the upper sample (2). The loading direction of the load application mechanism is perpendicular to the movement direction of the tangential drive mechanism.

2. The scaled-down test device for fretting wear of wind turbine bearings according to claim 1, characterized in that, The load application mechanism includes a support plate (10), a lower plate of an electric cylinder (11), and an electric cylinder (12). The support plate (10) is fixed on the test platform (1). The lower plate of the electric cylinder (11) is installed on the top of the support plate (10). The electric cylinder (12) is fixed on the lower plate of the electric cylinder (11). The output end of the electric cylinder (12) extends vertically downward through the lower plate of the electric cylinder (11). The upper sample clamping mechanism is connected to the support plate (10) through a T-shaped adapter block (13). The T-shaped adapter block (13) and the support plate (10) are slidably engaged through a Z-direction guide rail (14) and a Z-direction slider (15).

3. The scaled-down test device for fretting wear of wind turbine bearings according to claim 2, characterized in that, A buffer force transmission mechanism is provided between the output end of the electric cylinder (12) and the upper sample clamping mechanism. The buffer force transmission mechanism includes an upper spring plate (16), a lower spring plate (17), and a heavy-duty spring (18). The upper spring plate (16) is fixedly connected to the output end of the electric cylinder (12). The heavy-duty spring (18) is installed between the upper spring plate (16) and the lower spring plate (17). The pressure sensor (4) is fixed below the lower spring plate (17).

4. The scaled-down test device for fretting wear of wind turbine bearings according to claim 3, characterized in that, The buffer force transmission mechanism also includes multiple linear bearings (19) and multiple plug bolts (20). The linear bearings (19) are fixedly installed on the upper spring plate (16). The plug bolts (20) pass through the linear bearings (19) and are connected to the lower spring plate (17). The heavy-duty spring (18) is fitted on the plug bolts (20) and is limited by the plug bolts (20). The output end of the electric cylinder (12) is fixedly connected to the upper spring plate (16) through the electric cylinder nut (21).

5. The scaled-down test device for fretting wear of wind turbine bearings according to claim 2, characterized in that, The upper sample clamping mechanism includes a lower plate (30) of the T-shaped transition block connected below the T-shaped transition block (13). An X-direction guide rail (31) and an X-direction slider (32) are provided below the lower plate (30). An upper sample clamping connecting plate (33) is fixed below the X-direction slider (32). An upper sample clamping fixture (34) is provided on the upper sample clamping connecting plate (33). The friction sensor (5) is installed between the upper sample fixture connecting plate (33) and the friction sensor connecting plate (35). The X-direction guide rail (31) and the X-direction slider (32) allow the upper sample (2) to move freely along the X direction with the upper sample fixture (34) to transmit the tangential friction force to the friction sensor (5).

6. The scaled-down test device for fretting wear of wind turbine bearings according to claim 5, characterized in that, The upper sample clamp (34) is hinged to an upper sample clamp attachment (37) via a pin (36). The upper sample clamp attachment (37) can swing around the pin (36) in the Y direction to adjust the parallelism of the contact surfaces of the upper sample (2) and the lower sample (3). After adjustment, the upper sample clamp attachment (37) is fixed by a locking device.

7. The scaled-down test device for fretting wear of wind turbine bearings according to claim 1, characterized in that, The tangential drive mechanism includes a slide table (40), a lower slide table plate (41), and an upper slide table plate (42). The lower slide table plate (41) is fixed on the test platform (1). The slide table (40) is installed on the test platform (1) through the lower slide table plate (41). The upper slide table plate (42) is fixed to the top of the slide table (40). The lower sample (3) is installed on the upper slide table plate (42) through the lower sample clamp (38). The slide table (40) is driven by a servo motor and performs controllable reciprocating motion in the horizontal direction.

8. The scaled-down test device for fretting wear of wind turbine bearings according to claim 2, characterized in that, It also includes a displacement detection component, which includes a grating (50) fixedly installed on the support plate (10) and a grating ruler pasted on the upper plate (42) of the slide. The grating (50) and the grating ruler cooperate to read the displacement data of the slide (40) in real time, and use the displacement feedback signal to perform closed-loop control of the reciprocating motion of the slide (40).

9. A test method for scaled-down testing of fretting wear in wind turbine bearings, characterized in that, The test is conducted using the test apparatus according to any one of claims 1 to 8, comprising the following steps: S1. Install the sample: Install and lock the upper sample (2) in the upper sample clamping mechanism, install and lock the lower sample (3) in the tangential drive mechanism, and adjust the parallelism of the contact surfaces of the upper sample (2) and the lower sample (3). S2. Apply load: Set the target load value, start the load application mechanism to drive the upper sample (2) to move vertically downward until it contacts the lower sample (3). When the reading of the pressure sensor (4) reaches the target load value, automatically stop pressurizing and keep the load stable. S3. Perform fretting wear test: preset displacement amplitude, frequency and number of cycles, start the tangential drive mechanism to make reciprocating motion in the horizontal direction, drive the lower sample (3) to generate tangential fretting displacement relative to the upper sample (2) to achieve fretting wear; S4. Real-time data acquisition: While the test is being conducted, the normal load is collected in real time by the pressure sensor (4), and the tangential friction force is collected in real time by the friction sensor (5). The friction coefficient is calculated, and the displacement time history curve of the tangential drive mechanism is recorded simultaneously. S5. End of test: When the reciprocating motion of the tangential drive mechanism reaches the preset number of cycles, the test will automatically stop, and the upper sample (2) and lower sample (3) will be taken out for subsequent analysis.

10. The test method for scaled-down testing of fretting wear of wind turbine bearings according to claim 9, characterized in that, In step S2, the load applied by the load application mechanism is buffered by the heavy-duty spring (18) in the buffer force transmission mechanism and then transmitted to the pressure sensor (4). The external control system dynamically closes the load application mechanism according to the feedback signal of the pressure sensor (4) to maintain the stability of the normal load during the test.

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