A bearing static angular stiffness measuring device and measuring method

Abstract

The application relates to a bearing static angular rigidity measuring device and a measuring method, and belongs to the technical field of bearing measurement. The measuring device comprises a mechanical main body; a measuring tool, the measuring tool comprising a bearing seat, a loading mandrel and a balancing mandrel, the bearing seat being installed on the front panel of the mechanical main body, a measured bearing being installed in the bearing seat, a bearing outer ring of the measured bearing being fixed on the bearing seat, and a bearing inner ring end face being clamped by the loading mandrel and the balancing mandrel; a displacement measuring assembly being provided with two sets, each set comprising a displacement sensor and a height measuring mechanism; and a loading mechanism for applying a vertical loading force to the loading mandrel. The measuring method adopts the measuring device, calculates the bearing angular rigidity under the loading force from the overturning moment and the bearing angular change, and draws an angular rigidity change curve. The application greatly improves the detection efficiency of the angular rigidity of cross-roller bearings, reduces the measurement cost and the measurement workload, improves the measurement precision, and has great application prospects.

Description

Technical Field

[0001] This invention belongs to the field of bearing measurement technology, specifically relating to a bearing static angular stiffness measuring device and method. Background Technology

[0002] Crossed roller bearings, as a key basic component, have become a "core joint" in high-end equipment manufacturing due to their ability to simultaneously withstand radial, axial, and overturning moment loads, and their superior performance such as high rotational accuracy and high rigidity. Their performance directly determines the final accuracy, reliability, and lifespan of equipment such as CNC machine tools, industrial robots, precision rotary tables, and radar satellite antennas.

[0003] Among numerous performance indicators, angular stiffness is a core parameter measuring a bearing's ability to resist the relative tilting of the inner and outer rings caused by overturning moments. High angular stiffness means less deformation under the same load, which is the cornerstone for ensuring the motion accuracy, dynamic response speed, and system stability of equipment. As fields such as intelligent manufacturing, aerospace, and semiconductor equipment develop towards ultra-precision and high dynamics, almost stringent requirements are placed on the angular stiffness performance of crossed roller bearings, necessitating precise quantitative testing methods to match these requirements.

[0004] In applications such as machine tool spindles, robot joints, precision rotary tables (e.g., the fourth axis of a CNC machine tool), and radar antenna bases, bearings need to withstand overturning moments from workpieces, cutting tools, or arm extensions. High angular stiffness can greatly suppress minute deflections caused by these moments, ensuring the stability of the rotation axis and thus guaranteeing machining accuracy, repeatability, and pointing accuracy. Insufficient angular stiffness can lead to "head-down" or "head-up" phenomena under load, resulting in dimensional deviations, robot end effector position drift, or radar beam pointing errors.

[0005] Currently, the bearing angular stiffness measuring devices used in the industry measure the deformation displacement of the structural component by applying direct or indirect radial loading to the component on which the bearing is installed, and then calculate the bearing angular stiffness under different loading forces through mathematical calculations.

[0006] For example, in patent publication CN108956144A, the crossed roller bearing to be tested is mounted on a base and supported by a turntable. The outer ring of the crossed roller bearing is fixed to the base by an upper pressure plate with a ring of bolts, and the inner ring of the crossed roller bearing is fixed to the turntable by a lower pressure plate with another ring of bolts. A torque measuring shaft is connected to the center of the turntable, and a radial loading force is applied to the torque measuring shaft through a radial loading module on the side of the base. In this structure, the probes of the two displacement sensors can only contact the surface of the turntable, with the contact positions located above the upper and lower pressure plates, respectively, indirectly detecting the relative displacement between the inner and outer rings of the crossed roller bearing.

[0007] For example, in the patent with publication number CN118310701A, the bearing to be tested is installed on the spindle, and the spindle is radially loaded by a counterweight. The detector measures the change in height of the upper edge of the outer wall of the spindle, and then calculates the angular stiffness of the bearing.

[0008] The above two patents have the following problems: (1) The displacement detection device cannot directly measure the displacement change of the bearing end face, but indirectly measures the turntable or spindle. As a result, due to bearing assembly error, turntable or spindle assembly gap, and the interference of the turntable and spindle deformation after being loaded on the measurement results, the accuracy and reliability of the indirect detection results are low; (2) It cannot adapt to the measurement of different bearing models and has poor versatility; (3) It is difficult to achieve automatic loading; (4) In the patent CN118310701A, the spindle is installed horizontally, and the overturning moment generated by the weight of the spindle will also interfere with the detection results, resulting in poor accuracy of the final angular stiffness. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a bearing static angular stiffness measuring device and method, solving the problem of low accuracy in the measurement results of existing angular stiffness measuring devices, and providing practical data support for bearing design, manufacturing, and selection.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is: a bearing static angular stiffness measuring device, comprising: The mechanical body is supported on the frame; The measuring fixture includes a bearing housing, a loading mandrel, and a balancing mandrel. The bearing housing is mounted on the front plate of the machine body. The bearing to be tested is mounted in the bearing housing. The outer ring of the bearing to be tested is fixed on the bearing housing. The inner ring of the bearing is clamped by the loading mandrel and the balancing mandrel. The balancing mandrel is located inside the bearing housing, and the loading mandrel extends out of the bearing housing. The measuring fixture has reserved measurement positions for testing the inner ring of the bearing. The displacement measurement assembly includes two sets, which are installed on the mechanical body. Each displacement measurement assembly includes a displacement sensor and a height measurement mechanism. The displacement sensors of the two sets are located above and below the measuring fixture, respectively, and are used to measure the displacement change of the bearing inner ring end face during loading. The height measurement mechanism is used to measure the distance between the probe of the displacement sensor and the reference position in the vertical direction. A loading mechanism, mounted on the frame, is used to apply a vertical loading force to the loading mandrel.

[0011] Furthermore, the front panel of the mechanical body is provided with a central positioning hole, and the bearing seat is provided with a central positioning block. The central positioning block and the central positioning hole are convex and concave to achieve precise and stable positioning of the bearing seat.

[0012] Furthermore, the balancing mandrel and the loading mandrel are fixedly connected to clamp the inner ring of the bearing, and the balancing mandrel balances the additional overturning torque introduced by the loading mandrel.

[0013] Furthermore, the balancing mandrel and the loading mandrel are connected by a thread.

[0014] Furthermore, the loading mandrel is provided with a clamping step for clamping the inner ring of the bearing, and the side of the loading mandrel is provided with a clearance surface to expose the inner ring of the bearing.

[0015] Furthermore, the measuring fixture also includes an outer ring clamping plate for fixing the outer ring of the bearing. The outer ring clamping plate is fixed on the end face of the bearing housing. The outer ring clamping plate is divided into two halves, and a measuring window is formed between the two outer ring clamping plates. The measuring window is located outside the clearance surface on the loading mandrel. The probe of the displacement sensor measures the displacement of the bearing inner ring end face through the measuring window.

[0016] Furthermore, the displacement measurement assembly also includes a Y-axis adjustment mechanism, a Z-axis adjustment mechanism, and a measuring frame. The displacement sensor is mounted on the measuring frame, the measuring frame is connected to the sliding end of the Z-axis adjustment mechanism, the fixed end of the Z-axis adjustment mechanism is connected to the sliding end of the Y-axis adjustment mechanism, and the fixed end of the Y-axis adjustment mechanism is mounted on the mechanical body.

[0017] Furthermore, the height measuring mechanism includes a grating ruler and a grating reading head. The grating ruler is fixed on the mechanical body, and the grating reading head is installed on the sliding end of the Y-axis adjustment mechanism.

[0018] Furthermore, the loading mechanism includes a servo electric cylinder, a spring, a guide shaft, a force sensor, a joint bearing, and a loading head, connected sequentially from bottom to top.

[0019] This invention also proposes a method for measuring the static angular stiffness of a bearing, using the aforementioned bearing static angular stiffness measuring device. The method comprises the following steps: After adjusting the upper and lower displacement measuring components into position, the vertical distance between the two displacement sensor probes and the center of the bearing being measured is measured by the height measuring mechanism; the loading mechanism applies a loading force to the loading mandrel, and the two displacement sensors respectively measure the displacement change at the corresponding position of the bearing inner ring. Combining the distance between the displacement sensor probe position and the bearing center measured by the height measuring mechanism, the bearing angle change is calculated using an inverse trigonometric function; the overturning moment is calculated based on the lever arm of the loading mandrel and the loading force, and the bearing angular stiffness under this loading force is calculated from the overturning moment and the bearing angle change; as the loading force increases, a series of loading forces and corresponding bearing angle changes are calculated, ultimately yielding the angular stiffness change curve.

[0020] The beneficial effects of this invention are: the bearing static angular stiffness measuring device proposed in this invention adopts a modular design, has a simple structure, is easy to operate, can effectively measure the static angular stiffness of crossed roller bearings, and can plot the angular stiffness curve in real time, providing a favorable means for measuring the angular stiffness of bearings and providing practical data support for the selection of crossed roller bearings.

[0021] The measuring device and method proposed in this invention greatly improve the detection efficiency of the angular stiffness of crossed roller bearings, reduce the measurement cost and workload, and improve the measurement accuracy, and have great application prospects. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the bearing static angular stiffness measuring device described in this invention. Figure 2 This is a side sectional view of the mechanical body in the bearing static angular stiffness measuring device of the present invention; Figure 3 This is a schematic diagram of the mechanical body in the bearing static angular stiffness measuring device of the present invention; Figure 4 This is a right-side view of the mechanical body in the bearing static angular stiffness measuring device of the present invention; Figure 5 This is a schematic diagram of the measuring fixture in the bearing static angular stiffness measuring device of the present invention; Figure 6 This is a cross-sectional view of the measuring fixture in the bearing static angular stiffness measuring device of the present invention; Figure 7 This is a schematic diagram of the front end of the measuring fixture in the bearing static angular stiffness measuring device of the present invention; Figure 8 This is a schematic diagram of the loading mandrel in the bearing static angular stiffness measuring device of the present invention; Figure 9 This is a schematic diagram of the structure of the balance mandrel in the bearing static angular stiffness measuring device of the present invention; Figure 10 This is a schematic diagram of the loading mechanism in the bearing static angular stiffness measuring device of the present invention; Figure 11 This is a cross-sectional view of the loading mechanism in the bearing static angular stiffness measuring device of the present invention; Figure 12 This is a schematic diagram of the displacement measuring component in the bearing static angular stiffness measuring device of the present invention; Figure 13 A schematic diagram of the testing method using the aforementioned bearing static angular stiffness measuring device; Markings in the diagram: 1. Main body of the machine; 2. Displacement measurement assembly; 3. Frame; 4. Loading mechanism; 5. Measuring fixture; 6. Center positioning hole; 7. Bearing housing; 8. Outer ring clamping plate; 9. Loading mandrel; 10. Balancing mandrel; 11. Center positioning block; 12. Front panel; 13. Grating ruler; 14. Grating reading head; 15. Bearing outer ring; 16. Bearing inner ring; 17. Measuring window; 18. Threaded head; 19. Clearance surface; 20. Pressure. 21. Tight step, 22. Internal threaded hole, 23. Servo electric cylinder, 24. Loading head, 25. Spring, 26. Guide shaft, 27. Force sensor, 28. Spherical bearing, 29. Vertical guide rail, 30. Connecting block, 31. Y-axis adjusting handle, 32. Right angle adapter block, 33. Y-axis slider, 34. Fixing block, 35. Limiting piece, 36. Locking screw, 37. Z-axis slider, 38. Push-pull handle, 39. Measuring frame, 30. Displacement sensor. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the embodiments, but this should not be construed as limiting the invention in any way.

[0024] Example 1: As Figure 1 As shown, a bearing static angular stiffness measuring device includes a mechanical body 1, two sets of symmetrically arranged displacement measuring components 2, a frame 3, a loading mechanism 4, and a measuring fixture 5.

[0025] The frame 3 is used to mount the mechanical body 1 and the loading mechanism 4, and to provide necessary support and positioning for the various components of the measuring device.

[0026] like Figure 2 As shown, the mechanical body 1 is a box structure, which can be assembled from six steel plates or other metal plates, and has the self-rigidity and positioning accuracy required for rigidity testing. The base plate of the mechanical body 1 is fixed on the frame 3, and the front panel 12 at the front of the mechanical body 1 is provided with a central positioning hole 6 and a mounting thread hole.

[0027] like Figure 2 , 3As shown in Figures 5-7, the measuring fixture 5 is used to install the bearing to be tested vertically on the front panel 12 in front of the main body 1, and is positioned by the central positioning hole 6. The measuring fixture 5 includes a bearing housing 7, an outer ring clamping plate 8, a loading mandrel 9, and a balancing mandrel 10. The bearing housing 7 is installed on the front panel 12 of the main body 1, and a central positioning block 11 is provided on the back of the bearing housing 7. The central positioning block 11 is in a convex-concave fit with the central positioning hole 6 to achieve the center positioning of the bearing housing 7. The bearing to be tested is installed in the mounting groove at the front end of the bearing housing 7. The outer ring clamping plate 8 is connected to the front end face of the bearing housing 7 by screws so as to press the outer ring 15 of the bearing to be tested into the bearing housing 7. The bearing housing 7 has a groove in the center for installing the balancing mandrel 10, and the end face of the balancing mandrel 10 presses against the inner end face of the inner ring 16 of the bearing to be tested.

[0028] like Figure 8 As shown, one end of the loading mandrel 9 is provided with an annular pressing step 20, which is used to press against the outer end face of the bearing inner ring 16, and together with the balancing mandrel 10, clamps the bearing inner ring 16 of the bearing under test. The center of the loading mandrel 9 is fixedly connected to the center of the end face of the balancing mandrel 10. Specifically, the center of the end face of the loading mandrel 9 is provided with a threaded head 18, and the center of the end face of the balancing mandrel 10 is provided with an internal threaded hole 21. The loading mandrel 9 is fixedly connected to the balancing mandrel 10 through the threaded engagement of the threaded head 18 and the internal threaded hole 21, and clamps the bearing inner ring 16. At the same time, this method can be applied to clamping the inner rings of bearings of different thicknesses by adjusting the screw depth of the threaded head 18. After the loading mandrel 9 is fixed, the bearing outer ring 15 of the bearing under test is fixed, and the bearing inner ring 16 bears the overturning moment transmitted by the loading mandrel 9. After the balancing mandrel 10 is fixedly connected to the loading mandrel 9, it can offset the overturning moment introduced by the weight of the loading mandrel 9, and avoid introducing interference terms in the measurement. In other embodiments, the positions of the threaded head 18 and the internal threaded hole 21 can be changed, achieving the same technical effect.

[0029] refer to Figure 6 , 7 and Figure 2 As shown, while the outer ring clamping plate 8 clamps the outer ring 15 of the bearing, in order to expose the inner ring 16 of the bearing so that the displacement measuring component 2 can measure the displacement change of the end face of the inner ring 16 of the bearing, the outer ring clamping plate 8 adopts a two-lobed design. The circumferential end faces of the two outer ring clamping plates 8 are arranged at intervals to form symmetrical measuring windows 17 on the upper and lower sides. The end face of the inner ring 16 of the bearing is exposed through the measuring window 17, and the probe of the displacement measuring component 2 can extend into the measuring window 17 to measure the displacement change of the end face of the inner ring 16 of the bearing.

[0030] For example Figure 8As shown, in order to accommodate the measuring window 17, a portion of the outer circumference of the loading mandrel 9 is cut off axially, forming a relief surface 19 to avoid obstructing the bearing inner ring 16. Through the cooperation of the relief surface 19 and the measuring window 17, a portion of the end face of the bearing inner ring 16 can be exposed for measurement by the probe of the displacement measuring assembly 2.

[0031] like Figure 12 As shown, the displacement measuring assembly 2 includes a Y-axis adjustment mechanism, a Z-axis adjustment mechanism, a measuring frame 38, and a displacement sensor 39. The displacement sensor 39 is fixed to one end of the measuring frame 38, and the other end of the measuring frame 38 is fixed to the sliding end of the Z-axis adjustment mechanism. The fixed end of the Z-axis adjustment mechanism is connected to the sliding end of the Y-axis adjustment mechanism via a right-angle adapter block 31, and the fixed end of the Y-axis adjustment mechanism is fixedly mounted on the mechanical body 1.

[0032] Specifically, the sliding end of the Y-axis adjustment mechanism is a Y-axis slider 32, and the fixed end is a vertical guide rail 28. The vertical guide rail 28 is fixedly installed on the mechanical body 1. The Y-axis slider 32 is slidably connected to the vertical guide rail 28, and the sliding between the two is achieved through a gear and rack mechanism. The gear in the gear and rack mechanism is connected to the Y-axis adjustment handle 30 on the outside of the Y-axis slider 32. Rotating the Y-axis adjustment handle 30 can drive the Y-axis slider 32 to move vertically. The Y-axis slider 32 is also connected to a connecting block 29, which is used to connect to the grating reading head 14 (e.g., ...). Figure 4 As shown, the grating reading head 14 works in conjunction with the grating ruler 13 mounted on the mechanical body 1 as a height measuring mechanism to measure the distance between the probe of the displacement sensor 39 and the center of the bearing being measured. During measurement, it is necessary to calibrate the grating reading to 0 when the probe of the displacement sensor 39 is located at the center of the bearing being measured.

[0033] Specifically, the sliding end of the Z-axis adjustment mechanism is a Z-axis slider 36, and the fixed end is a fixed block 33. The fixed block 33 is fixedly connected to the right-angle adapter block 31 by screws. The Z-axis slider 36 is slidably connected to the track surface of the fixed block 33. A limiting piece 34 with an elongated hole is also connected to the side of the fixed block 33. The position of the elongated hole corresponds to the Z-axis slider 36. A locking screw 35 passes through the elongated hole and is connected to the Z-axis slider 36. After the locking screw 35 is tightened, the position of the Z-axis slider 36 can be locked to prevent slippage during measurement. Loosening the locking screw 35 allows the Z-axis slider 36 to be pushed and pulled horizontally. The range of movement is limited by the length of the elongated hole. The purpose is to horizontally adjust the position of the displacement sensor 39 to adapt to bearings of different thicknesses, so that the probe of the displacement sensor 39 is within the range of the displacement sensor 39. To facilitate pushing and pulling the Z-axis slider 36, a push-pull handle 37 is also provided on the Z-axis slider 36.

[0034] In this invention, the Y direction refers to the vertical direction, and the Z direction refers to the direction parallel to the axis of the bearing being measured. Therefore, the Z direction and the Y direction are perpendicular to each other.

[0035] In this invention, the displacement measuring component 2 is configured as two sets, located directly above and below the measuring fixture 5, respectively, for measuring the bearing under test from both vertical and horizontal directions.

[0036] The loading mechanism 4 is used to apply a force to the loading mandrel 9, which in turn applies an overturning moment to the inner ring 16 of the bearing. Figure 1 , 10 As shown in Figure 11, the loading mechanism 4 is mounted on the frame 3 and located in front of the main mechanical body 1. It includes a servo electric cylinder 22, a spring 24, a guide shaft 25, a force sensor 26, a joint bearing 27, and a loading head 23, connected sequentially from bottom to top. The servo electric cylinder 22 drives the loading head 23 to apply a loading force to the loading mandrel 9 from bottom to top, and the force sensor 26 measures the magnitude of the loading force in real time for calculating the overturning moment. Furthermore, the end of the loading head 23 is designed in an arc shape that matches the shape of the loading mandrel 9 for better fit against the surface of the loading mandrel 9.

[0037] Example 2: This example uses the bearing static angular stiffness measuring device described in Example 1 to measure the static angular stiffness of the crossed roller bearing. The measurement principle is as follows: Figure 13 As shown, before loading, the inner ring end face of the bearing (i.e., the vertical line passing through point O in the figure) is in a vertical state. The grating reading of the displacement sensor 39 probes of the upper and lower displacement measuring components 2 (i.e., displacement measuring point one and displacement measuring point two in the figure) at the center position of the bearing being measured (i.e., the horizontal line position passing through point O) is 0. When the probe of the displacement sensor 39 moves to the end face of the inner ring 16 of the bearing, the grating reading head 14 reads the grating reading of the grating ruler 13, and the distance from the probe of the displacement sensor 39 of the upper and lower displacement measuring components 2 to the center of the bearing being measured is measured, which is recorded as b1 and b2 respectively (the lower displacement sensor 39 is the opposite of the center of the bearing). (Displacement measuring point 1 corresponds to displacement measuring point 2, and the upper displacement sensor 39 corresponds to displacement measuring point 2). After applying a vertically upward loading force to the loading mandrel 9, the end face of the bearing inner ring 16 undergoes a certain displacement. The displacement changes of the bearing inner ring 16 before and after loading are measured by the two displacement sensors 39 and recorded as a1 and a2, respectively. The bearing angle changes θ1 and θ2 are then calculated using the inverse trigonometric function arctan(a / b). The force sensor 26 can measure the loading force F. Combined with the lever arm length L of the loading mandrel 9 (which can be directly measured), the applied overturning moment can be calculated as M = F × L. Therefore, based on the bearing angular stiffness K... α=M / θ can be used to calculate two angular stiffnesses. Averaging these values ​​yields the bearing angular stiffness under that applied force. By slowly increasing the applied force, a series of applied forces F and angular changes θ can be measured, ultimately yielding a series of angular stiffnesses K. α And the angular stiffness curve was plotted using testing software.

[0038] Based on the above principles, the method for measuring the static angular stiffness of a bearing includes the following steps: S1, the bearing to be tested is mounted on the loading mandrel 9, which is connected to the balancing mandrel 10 to press the inner ring 16 of the bearing to be tested. S2, then install the overall structure after S1 on the bearing housing 7, and install the outer ring clamping plate 8 to clamp the outer ring 15 of the bearing; S3, adjust the upper and lower displacement measurement components 2 so that the probe of the displacement sensor 39 contacts the end face of the inner ring 16 of the bearing through the measurement window 17 as displacement measurement point one and displacement measurement point two. Read the grating reading of the grating reading head 14 and the reading of the displacement sensor 39 at this time respectively. The two grating readings are used as the distances b1 and b2 between the displacement measurement point and the center of the bearing being measured. The reading of the displacement sensor 39 is used as the reference for displacement measurement. S4, a certain loading force F is applied to the loading mandrel 9 by the loading mechanism 4, and the reading of the displacement sensor 39 is recorded at the same time. Based on the change in the reading of the displacement sensor 39 before and after loading, the displacement changes a1 and a2 of the bearing inner ring 16 at different positions corresponding to the two displacement measuring points before and after loading are obtained. S5. Based on the inverse trigonometric function, calculate the bearing angle change θ1 corresponding to displacement measuring point one using a1 and b1, and calculate the bearing angle change θ2 corresponding to displacement measuring point two using a2 and b2; calculate the overturning moment M=F×L using the applied force F and the lever arm L of the loading mandrel, and then calculate the bearing angular stiffness K. α =M / θ, calculate the bearing angular stiffness K corresponding to displacement measuring point 1. α1 = M / θ1 and the bearing angular stiffness K corresponding to displacement measuring point two α2 = M / θ2, and for K α1 and K α2 By averaging the values, the bearing angular stiffness under that applied force can be obtained. S6. Repeat steps S4 and S5 to obtain the bearing angular stiffness under different loading forces and plot the angular stiffness curve.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the specific implementation of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the pending claims.

Claims

1. A bearing static angular stiffness measuring device, characterized in that, include: The mechanical body (1) is supported and connected to the frame (3); The measuring fixture (5) includes a bearing housing (7), a loading mandrel (9), and a balancing mandrel (10). The bearing housing (7) is mounted on the front panel (12) of the main body (1). The bearing to be measured is mounted in the bearing housing (7). The outer ring (15) of the bearing to be measured is fixed on the bearing housing (7). The inner ring (16) of the bearing is clamped by the loading mandrel (9) and the balancing mandrel (10), which are fixedly connected. The balancing mandrel (10) balances the additional overturning moment introduced by the loading mandrel (9). The balancing mandrel (10) is located inside the bearing housing (7). The loading mandrel (9) extends out of the bearing housing (7), and the side of the loading mandrel (9) is provided with a clearance surface (19) to expose the inner bearing ring (16); the measuring fixture (5) also includes an outer ring clamping plate (8) for fixing the outer ring (15) of the bearing. The outer ring clamping plate (8) is two-lobed, and a measuring window (17) is formed between the two outer ring clamping plates (8). The measuring window (17) is located outside the clearance surface (19) on the loading mandrel (9). The probe of the displacement sensor (39) measures the displacement of the end face of the inner ring (16) of the bearing through the measuring window (17); The displacement measurement assembly (2) is provided in two sets and installed on the mechanical body (1). The displacement measurement assembly (2) includes a displacement sensor (39) and a height measuring mechanism. The displacement sensors (39) of the two sets of displacement measurement assemblies (2) are located above and below the measuring fixture (5) respectively, and are used to measure the displacement change of the bearing inner ring (16) end face during loading. The height measuring mechanism is used to measure the distance between the probe of the displacement sensor (39) and the reference position in the vertical direction. The loading mechanism (4) is mounted on the frame (3) and is used to apply a vertical loading force to the loading mandrel (9).

2. The bearing static angular stiffness measuring device according to claim 1, characterized in that, The front panel (12) of the mechanical body (1) is provided with a central positioning hole (6), and the bearing seat (7) is provided with a central positioning block (11). The central positioning block (11) and the central positioning hole (6) are in convex-concave fit to achieve precise and stable positioning of the bearing seat (7).

3. The bearing static angular stiffness measuring device according to claim 1, characterized in that, The balancing mandrel (10) and the loading mandrel (9) are connected by threads.

4. The bearing static angular stiffness measuring device according to claim 1, characterized in that, The loading mandrel (9) is provided with a clamping step (20) for clamping the inner ring (16) of the bearing.

5. The bearing static angular stiffness measuring device according to claim 1, characterized in that, The outer ring clamping plate (8) is fixed on the end face of the bearing housing (7).

6. The bearing static angular stiffness measuring device according to claim 1, characterized in that, The displacement measuring assembly (2) further includes a Y-axis adjustment mechanism, a Z-axis adjustment mechanism and a measuring frame (38). The displacement sensor (39) is mounted on the measuring frame (38). The measuring frame (38) is connected to the sliding end of the Z-axis adjustment mechanism. The fixed end of the Z-axis adjustment mechanism is connected to the sliding end of the Y-axis adjustment mechanism. The fixed end of the Y-axis adjustment mechanism is mounted on the mechanical body (1).

7. The bearing static angular stiffness measuring device according to claim 6, characterized in that, The height measuring mechanism includes a grating ruler (13) and a grating reading head (14). The grating ruler (13) is fixed on the mechanical body (1), and the grating reading head (14) is installed on the sliding end of the Y-axis adjustment mechanism.

8. The bearing static angular stiffness measuring device according to claim 1, characterized in that, The loading mechanism (4) includes a servo electric cylinder (22), a spring (24), a guide shaft (25), a force sensor (26), a joint bearing (27), and a loading head (23) connected in sequence from bottom to top.

9. A method for measuring the static angular stiffness of a bearing, characterized in that, The method uses the bearing static angular stiffness measuring device according to any one of claims 1-8. The steps are as follows: After the upper and lower displacement measuring components (2) are adjusted to the position, the vertical distance between the probes of the two displacement sensors (39) and the center of the bearing under test is measured by the height measuring mechanism; the loading mechanism (4) applies a loading force to the loading mandrel (9), and the two displacement sensors (39) respectively measure the displacement change at the corresponding position of the bearing inner ring (16). Combined with the distance between the position of the displacement sensor probe and the center of the bearing measured by the height measuring mechanism, the bearing angle change is calculated according to the inverse trigonometric function; the overturning moment is calculated according to the lever arm of the loading mandrel (9) and the loading force, and the bearing angular stiffness under the loading force is calculated from the overturning moment and the bearing angle change; as the loading force increases, a series of loading forces and corresponding bearing angle changes are calculated, and finally the angular stiffness change curve is obtained.

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