Method and device for testing contact state of rolling body and raceway of rolling bearing

Abstract

The invention belongs to the field of bearing testing, and particularly relates to a method and a device for testing the contact state of a rolling body and a raceway of a rolling bearing. The device comprises a driving shaft, a tested bearing is provided with an inner ring sleeve and an outer ring sleeve, the inner ring sleeve and the outer ring sleeve are provided with an inner ring limiting structure and an outer ring limiting structure respectively, and the inner ring sleeve is provided with an inner containing groove used for containing a fiber grating sensor on the inner circumference of an inner ring of the tested bearing. The outer ring sleeve is provided with an outer containing groove used for containing a fiber grating sensor on the periphery of the outer ring of the tested bearing, the inner ring sleeve and the outer ring sleeve are respectively provided with through holes which are communicated with the inner containing groove and the outer containing groove so that a connecting line connected with the fiber grating sensor can penetrate out, and the connecting line penetrating out of the inner ring sleeve is connected with a fiber slip ring. According to the method, fiber bragg grating strings are respectively arranged on the inner ring and the outer ring of a tested bearing, the outer ring is fixed, the inner ring is driven to rotate, and the contact area distribution of the rolling bearing is judged through the central wavelength variation of the fiber bragg grating strings, or whether a three-point or four-point contact ball bearing has multi-point contact is judged.

Description

Technical Field

[0001] This invention belongs to the field of bearing testing, and in particular relates to a testing method and apparatus for testing the contact state of rolling elements and raceways in rolling bearings. Background Technology

[0002] Rolling bearings typically consist of an inner ring, an outer ring, rolling elements, and a cage. Under different operating conditions, the distribution and size of the contact areas within the rolling bearing vary, directly reflecting the bearing's load distribution, fatigue life, friction and wear characteristics. Furthermore, as a special type of rolling bearing, three-point or four-point contact ball bearings can be used in complex operating conditions where both radial and bidirectional axial forces are simultaneously applied. Due to the unique "peach-shaped" raceway structure of this type of bearing, under complex conditions such as high speed and variable load, a third contact point is formed between the rolling elements and the non-load-bearing inner ring, causing the bearing to enter a multi-point contact state. This leads to raceway slippage damage and wear of the rolling element cat's eye ring, resulting in premature bearing failure.

[0003] Existing technologies lack sufficient experimental research on the contact area distribution of rolling bearings, and studies on three- or four-point contact ball bearings are mostly limited to theoretical analysis or parameter testing such as temperature rise, vibration, and slippage. There is a lack of testing methods for the contact state of rolling elements and raceways under dynamic conditions, which consequently affects bearing operational safety. Therefore, it is necessary to research testing methods and devices for the contact state of rolling elements and raceways under dynamic conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a testing apparatus for the contact state between rolling elements and raceways in rolling bearings, thereby addressing the technical problem of the lack of existing methods for testing this contact state. A further purpose of this invention is to provide a testing method for the contact state between rolling elements and raceways in rolling bearings, thereby addressing the same technical problem.

[0005] To achieve the above objectives, the technical solution provided by this invention for a testing device that can be used to test the contact state between rolling elements and raceways in rolling bearings is as follows: A testing device for the contact state of rolling elements and raceways in rolling bearings includes a base with a drive shaft capable of outputting rotational power. The bearing under test is equipped with an inner ring sleeve that can be anti-rotated by the drive shaft and an outer ring sleeve fixed relative to the base. The inner and outer ring sleeves are respectively provided with an inner ring limiting structure for fixing the inner ring of the bearing under test and an outer ring limiting structure for fixing the outer ring of the bearing under test. The inner ring sleeve has an inner receiving groove for accommodating a fiber optic grating sensor on the inner circumference of the inner ring of the bearing under test, and the outer ring sleeve has an outer receiving groove for accommodating a fiber optic grating sensor on the outer circumference of the outer ring of the bearing under test. The inner and outer ring sleeves are respectively provided with through holes communicating with the inner receiving groove and the outer receiving groove for a connecting wire to pass through, and the connecting wire passing through the inner ring sleeve is connected to a fiber optic slip ring.

[0006] This invention is a pioneering invention, and its beneficial effects are as follows: By setting fiber optic grating sensors on the inner circumferential surface of the inner ring and the outer circumferential surface of the bearing under test, and by connecting the fiber optic grating sensor on the inner circumferential surface of the bearing under test through the through hole of the inner ring sleeve to the fiber optic slip ring, and by connecting the fiber optic grating sensor on the outer circumferential surface of the bearing under test through the through hole of the outer ring sleeve, the change in the center wavelength of the fiber optic grating sensor can be obtained without damaging the structure of the bearing under test. The change in center wavelength reflects the strain generated by the rolling element on the inner raceway on the inner ring and the outer raceway on the outer ring of the bearing under test, thereby obtaining the contact state between the rolling element and the raceway of the bearing under test.

[0007] As a further improvement, the inner ring sleeve is composed of an inner ring left sleeve, an inner ring middle sleeve, and an inner ring right sleeve. The diameter of the inner ring middle sleeve is smaller than that of the inner ring left sleeve and the inner ring right sleeve. The annular end faces of the inner ring left sleeve and the inner ring right sleeve, whose diameters extend beyond the inner ring middle sleeve, are used to stop and fit with the two ends of the inner ring of the bearing under test, respectively. The outer circumferential surface of the inner ring middle sleeve is used to make a clearance fit with the inner ring of the bearing under test, and together with the annular end face, it forms the inner ring limiting structure. The inner ring groove is provided on the inner ring middle sleeve.

[0008] As a further improvement, the outer ring sleeve is formed by two arc-shaped cylindrical walls. The inner arc surface of the arc-shaped cylindrical wall is provided with an outer groove for accommodating the outer ring of the bearing under test. The two side walls of the outer groove are respectively used to block the two ends of the outer ring of the bearing under test and form an outer ring limiting structure. The outer receiving groove is provided on the bottom wall of the outer groove. The through hole of the outer ring sleeve is provided on either arc-shaped cylindrical wall.

[0009] As a further improvement, the length of the drive shaft is sufficient to penetrate the inner ring sleeve, and the drive shaft is provided with a communicating center hole and a radial through hole, the radial through hole communicating with the through hole on the inner ring sleeve.

[0010] As a further improvement, one end of the drive shaft is connected to a detachable slip ring retainer. The slip ring retainer has a slip ring mounting hole coaxial with the drive shaft. The fixed end of the fiber optic slip ring passes through the slip ring mounting hole and is led out, while the rotating end faces the center hole and is connected to the connecting line.

[0011] As a further improvement, the drive shaft is provided with a shoulder for stopping one end of the inner ring sleeve, and a retaining ring is connected to stop the other end of the inner ring sleeve.

[0012] As a further improvement, the base is also provided with a radial loading mechanism for applying radial load to the outer ring sleeve and an axial loading mechanism for applying axial load.

[0013] As a further improvement, the outer circumferential surface of the outer sleeve is provided with a notch, and the radial loading mechanism has a loading head that matches the notch.

[0014] As a further improvement, the axial loading mechanism includes a loading stud, on which a loading nut and a pressure sensor are sequentially connected in sequence along the direction close to the outer ring sleeve, and a loading sleeve for abutting against the end of the outer ring sleeve is provided between the pressure sensor and the outer ring sleeve.

[0015] To achieve the above objectives, the technical solution provided by this invention for testing the contact state between rolling elements and raceways in rolling bearings is as follows: A test method for the contact state of rolling elements and raceways in rolling bearings is provided. Based on the type of bearing under test and the test content, at least one fiber optic grating sensor is fixed on the outer circumferential surface of the outer ring and the inner circumferential surface of the inner ring of the bearing under test. The outer ring of the bearing under test is fixed, and the inner ring of the bearing under test is driven to rotate. The fiber optic grating sensor is connected to a data acquisition device, and the change in the center wavelength of the fiber optic grating sensor is analyzed to determine the contact area distribution of the rolling bearing, or to determine whether multi-point contact occurs in three-point or four-point contact ball bearings.

[0016] This invention is a pioneering invention, and its beneficial effects are as follows: By setting fiber optic grating sensors on the inner circumferential surface of the inner ring and the outer circumferential surface of the outer ring of the bearing under test, and placing the bearing under test under dynamic conditions, the center wavelength of the fiber optic grating sensor will change according to the contact state of the rolling elements and raceways of the bearing under test. By connecting the fiber optic grating sensor to a data acquisition device, the change in the center wavelength of the fiber optic grating sensor can reflect the strain generated by the rolling elements on the inner raceway located on the inner ring of the bearing under test and on the outer raceway located on the outer ring of the bearing under test, thereby obtaining the contact state of the rolling elements and raceways of the bearing under test. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the testing device for the contact state between rolling elements and raceways in a rolling bearing according to the present invention. Figure 2 for Figure 1 A magnified view of a portion of region A in the middle; Figure 3 for Figure 1 A schematic diagram showing the mounting position of the fiber Bragg grating sensor on the rolling bearing. Explanation of reference numerals in the attached figures: 1. Electronic universal testing machine; 2. Loading sleeve support; 3. Stud support; 4. Loading stud; 5. Loading nut; 6. Pressure sensor; 7. Loading sleeve; 8. Fiber optic slip ring; 9. Slip ring support; 10. Rotary flange; 11. Inner ring sleeve stop nut; 12. Inner ring left sleeve; 13. Bearing under test; 13-1. Inner ring; 13-2. Outer ring; 13-3. Rolling element; 14. Outer ring upper cylinder wall; 15. Inner ring middle sleeve; 16. Inner ring right sleeve; 17. Drive shaft; 18. Bearing housing; 19. Auxiliary outer sleeve; 20. Auxiliary inner sleeve; 21. Auxiliary bearing; 22. Auxiliary stop nut; 23. Flexible coupling; 24. Servo motor; 25. Motor support; 26. Base; 27. Fiber optic grating string; 28. Outer ring lower cylinder wall; 29. ​​Loading head; 30. Operating hole. Detailed Implementation

[0018] To address the technical problem of the lack of testing methods for the contact state between the rolling elements and raceways of rolling bearings in existing technologies, the basic technical concept of this invention is as follows: fiber optic grating strings are respectively arranged on the inner circumferential surface of the inner ring and the outer circumferential surface of the outer ring of the rolling bearing. The connecting lines of the fiber optic grating strings on the inner and outer rings are respectively led out radially from the inner ring sleeve and radially outward from the outer ring sleeve. Based on the change in the center wavelength of the fiber optic grating strings, the contact state between the rolling elements and raceways of the rolling bearing under dynamic loading conditions can be determined, thereby determining the contact area distribution of the rolling bearing, or determining whether multi-point contact occurs in three-point or four-point contact ball bearings.

[0019] The present invention will be further described in detail below with reference to the embodiments.

[0020] Specific embodiments of the testing device for the contact state of rolling elements and raceways in rolling bearings provided by this invention are as follows: like Figure 1 , Figure 2 and Figure 3 As shown, fiber Bragg grating strings 27 are fixed on the inner circumferential surface of the inner ring 13-1 and the outer circumferential surface of the outer ring 13-2 of the bearing under test 13. When the bearing under test 13 is a double-half inner ring angular contact ball bearing, the fiber Bragg grating strings 27 are respectively arranged on the inner circumferential surface of the double-half inner ring and the outer circumferential surface of the outer ring, and the fiber Bragg grating strings 27 on the inner and outer circumferential surfaces are aligned axially with the bearing under test 13. It should be noted that the fiber Bragg grating string 27, as a fiber Bragg grating sensor, has the advantages of light weight, small size, and easy bending. The arrangement position of the fiber Bragg grating string 27 on the double-half inner ring angular contact ball bearing should be within the contact angle range, that is, the position of the fiber Bragg grating string 27 can change with the contact state between the rolling element 13-3 and the raceway, so as to ensure that the fiber Bragg grating string 27 can generate wavelength changes when the contact state between the rolling element 13-3 and the raceway changes. In addition, the measuring points of the fiber Bragg grating string 27 should be set according to the size of the bearing under test 13 and the number of rolling elements 13-3.

[0021] like Figure 1 and Figure 2 As shown, the testing device for the contact state of rolling elements and raceways in rolling bearings includes a base 26, a motor support 25 fixedly connected to the base 26, and a drive motor, such as a servo motor 24, mounted on the motor support 25. The output end of the servo motor 24 is connected to a drive shaft 17. An inner ring sleeve, the bearing under test 13, and an outer ring sleeve are sequentially connected to the drive shaft 17. The inner ring sleeve is anti-rotationally connected to the drive shaft, and the outer ring sleeve is fixed relative to the base. The inner ring sleeve has an inner receiving groove to accommodate the fiber optic grating string 27 located on the inner circumferential surface of the inner ring 13-1 of the bearing under test 13. The inner ring sleeve also has an inner ring limiting structure for fixing the inner ring 13-1 of the bearing under test 13, so that the rotational power of the drive shaft 17 is transmitted to the inner ring 13-1 of the bearing under test 13 through the inner ring sleeve. The outer ring sleeve has an outer receiving groove to accommodate the fiber optic grating string 27 located on the outer circumferential surface of the outer ring 13-2 of the bearing under test 13. The outer ring sleeve also has an outer ring limiting structure for fixing the outer ring 13-2 of the bearing under test 13, so that the outer ring sleeve is fixed relative to the drive shaft 17, thereby allowing the inner ring 13-1 of the bearing under test 13 to rotate at high speed relative to the outer ring 13-2. It should be noted that the inner receiving groove and the outer receiving groove are relative to the bearing under test 13; the inner receiving groove is actually located on the outer circumferential surface of the inner ring sleeve, and the outer receiving groove is actually located on the inner circumferential surface of the outer ring sleeve.

[0022] like Figure 1 and Figure 2 As shown, the fiber Bragg grating string 27 disposed on the inner circumferential surface of the inner ring 13-1 of the bearing under test 13 is connected to a connecting wire. Preferably, the output end of the fiber Bragg grating string 27 is welded to the connecting wire. Since the length of the drive shaft 17 extends through the inner ring sleeve, in order to enable the connecting wire of the fiber Bragg grating string 27 disposed on the inner circumferential surface of the inner ring 13-1 of the bearing under test 13 to be connected to the acquisition device for acquiring the center wavelength of the fiber Bragg grating, the drive shaft 17 is provided with a central hole and a radial through hole communicating with the central hole. The inner ring sleeve is provided with a through hole communicating with the inner storage groove and the radial through hole. The connecting wire of the fiber Bragg grating string 27 placed in the inner storage groove passes through the through hole, the radial through hole and the central hole in sequence to connect to the fiber optic slip ring 8 and be led out. Specifically, the fiber optic slip ring 8 has a fixed end and a rotating end. The fixed end of the fiber optic slip ring 8 is used to connect to the acquisition device for acquiring the center wavelength change of the fiber optic grating string 27. The rotating end of the fiber optic slip ring 8 faces the center hole and is connected to the connecting line of the fiber optic grating string 27 placed in the inner slot, so as to ensure that the connecting line of the fiber optic grating string 27 will not become entangled when the test bearing 13 rotates at high speed.

[0023] like Figure 1 and Figure 2As shown, a fiber Bragg grating string 27 disposed on the outer circumferential surface of the outer ring 13-2 of the bearing under test 13 is connected to a connecting wire. Preferably, the output end of the fiber Bragg grating string 27 is soldered to the connecting wire. To enable the connecting wire of the fiber Bragg grating string 27 disposed on the outer circumferential surface of the outer ring 13-2 of the bearing under test to be connected to a data acquisition device for the center wavelength of the fiber Bragg grating, a through hole is provided on the outer ring sleeve along the radial direction of the outer ring sleeve. The connecting wire of the fiber Bragg grating string 27, placed in the outer receiving groove, passes through this through hole and is led out. Further, after the connecting wire of the fiber Bragg grating string 27 is led out, it is connected to a data acquisition device and a signal analysis instrument to acquire and analyze the center wavelength information of the fiber Bragg grating string 27. For example, a fiber Bragg grating demodulator and signal analysis software can be used.

[0024] When the servo motor 24 is started, under the dynamic condition of the drive shaft 17 rotating, the change in the center wavelength of the fiber optic grating string 27 fixed on the inner circumferential surface of the inner ring 13-1 and the outer circumferential surface of the outer ring 13-2 of the rolling bearing is collected and analyzed by the acquisition device and signal analysis instrument. This allows for the testing of the contact state between the rolling element 13-3 and the inner raceway of the inner ring 13-1, and between the rolling element 13-3 and the outer raceway of the inner ring 13-2.

[0025] Based on the above implementation methods, such as Figure 2 As shown, the outer ring sleeve is formed by two semi-circular cylindrical walls: an upper outer ring wall 14 and a lower outer ring wall 28. The inner arc surfaces of both the upper and lower outer ring walls 14 and 28 are provided with outer grooves to accommodate the outer ring 13-2 of the test bearing 13. The width of the outer groove is equal to the width of the outer ring 13-2. The two sidewalls of the outer groove are respectively fitted to the two ends of the outer ring 13-2. The bottom wall of the outer groove has an outer receiving groove to avoid the fiber optic grating string 27 on the outer circumference of the outer ring 13-2. The two sidewalls of the outer groove constitute the outer ring limiting structure. The outer ring sleeve fixes the outer ring 13-2 of the test bearing 13 through the outer ring limiting structure, thereby keeping the outer ring 13-2 fixed relative to the drive shaft 17 and the inner ring 13-1. It should be noted that, in order to allow the fiber optic grating string 27 fixed on the outer circumferential surface of the outer ring 13-2 of the bearing under test to be led out, a through hole is provided on the lower cylinder wall 28 of the outer ring, which is radially arranged along the lower cylinder wall 28 and communicates with the outer receiving groove. The connecting wire of the fiber optic grating string 27 fixed on the outer circumferential surface of the outer ring 13-2 of the bearing under test passes through the through hole and is connected to the acquisition device and signal analysis instrument. The acquisition device and signal analysis instrument collect and analyze the change in the center wavelength of the fiber optic grating string 27 located on the outer ring 13-2, thereby determining the contact state between the rolling element 13-3 and the raceway.

[0026] It should be noted that the outer ring 13-2 can be held in a fixed state by clamping the two sidewalls of the outer groove. On this basis, the bottom wall of the outer groove can be pressurized to fit the outer circumference of the outer ring 13-2 by the cooperation of the two semi-circular cylindrical walls 14 and 28 of the outer ring, so as to further strengthen the fixation of the outer ring 13-2.

[0027] Based on the above implementation methods, such as Figure 1 and Figure 2 As shown, to facilitate the installation of the double-half inner ring angular contact ball bearing, the inner ring sleeve includes an inner ring left sleeve 12, an inner ring middle sleeve 15, and an inner ring right sleeve 16. The drive shaft 17 is equipped with a shoulder that axially stops the inner ring right sleeve 16 and a retaining ring that axially stops the inner ring left sleeve 12, such as an inner ring sleeve retaining nut 11 threadedly connected to the drive shaft 17. The inner ring left sleeve 12 and the inner ring right sleeve 16 are located at both ends of the inner ring middle sleeve 15, respectively. The inner ring receiving groove is provided on the inner ring middle sleeve 15. The inner ring left sleeve 12 and the inner ring right sleeve 16 are provided with a notch at the end near the inner ring middle sleeve 15 to avoid the inner ring 13-1 and simultaneously stop and restrict the axial position of the inner ring 13-1. The inner ring left sleeve 12 and the inner ring right sleeve 16 are both in contact with the end of the inner ring middle sleeve 15. The notch can be used to avoid the inner ring 13-1 of the bearing under test 13, and can also limit the axial position of the inner ring 13-1.

[0028] On the adjacent end faces of the inner ring left sleeve 12 and the inner ring middle sleeve 15, the annular end face of the portion of the inner ring left sleeve 12 whose diameter exceeds the diameter of the inner ring middle sleeve 15 is in a stop-fitting relationship with the left end of the inner ring 13-1 of the bearing under test 13. On the adjacent end faces of the inner ring right sleeve 16 and the inner ring middle sleeve 15, the annular end face of the portion of the inner ring right sleeve 16 whose diameter exceeds the diameter of the inner ring middle sleeve 15 is in a stop-fitting relationship with the right end of the inner ring 13-1 of the bearing under test 13. The outer circumferential surface of the inner ring middle sleeve 15 is in a clearance fit with the inner ring 13-1 of the bearing under test 13. The inner ring 13-1 of the bearing under test 13 is kept fixed to the inner ring middle sleeve 15 under the pressure of the end faces of the inner ring left sleeve 12 and the inner ring right sleeve 15. Thus, it can be seen that the two annular end faces and the inner ring middle sleeve 15 together constitute the inner ring limiting structure that fixes the inner ring 13-1 to the inner ring sleeve. The inner ring sleeve fixes the inner ring 13-1 of the test bearing 13 through the inner ring limiting structure, thereby transmitting the rotational power of the drive shaft 17 to the inner ring 13-1 of the test bearing 13. The inner ring 13-1 drives the rolling element 13-3 to roll in the raceway located on the outer surface of the inner ring 13-1 and the inner surface of the outer ring 13-2. In addition, the inner ring sleeve 15 is provided with a radially arranged through hole communicating with the inner receiving groove, so that the fiber optic grating string 27 fixed on the inner surface of the inner ring 13-1 can be led out through the through hole and the central hole and radial through hole on the drive shaft 17.

[0029] When installing the double-ring inner ring angular contact ball bearing, first connect the outer ring upper cylinder wall 14 and the outer ring lower cylinder wall 28 to the outer ring 13-2 of the bearing under test 13. Then, assemble the inner ring left sleeve 12, the left half of the inner ring of the bearing under test 13, the inner ring middle sleeve 15, the remaining part of the bearing under test 13 excluding the left half of the inner ring, and the inner ring right sleeve 16 in sequence. Then, fit the assembled parts onto the drive shaft 17, with the right end face of the inner ring right sleeve 16 abutting against the shaft shoulder of the drive shaft 17. Finally, install the inner ring sleeve stop nut 11. The shaft shoulder and the inner ring sleeve stop nut 11 together provide axial positioning for the bearing under test 13, the inner ring sleeve, and the outer ring sleeve.

[0030] In other embodiments, the outer ring sleeve can also be composed of multiple segments, as long as it can fix the outer ring 13-2 of the bearing under test 13 and lead out the output end of the fiber Bragg grating string 27 fixed on the outer circumferential surface of the outer ring 13-2. Some outer ring sleeves can also be divided into multiple outer ring sub-sleeves along the axial direction at the location of the fiber Bragg grating string 27. For example, based on two axially distributed fiber Bragg grating strings 27, they can be divided into an outer ring right sleeve, an outer ring middle sleeve, and an outer ring left sleeve.

[0031] In other embodiments, the inner ring sleeve may only be provided as the inner ring middle sleeve. By providing a notch on the shoulder of the drive shaft 17, the shoulder simultaneously abuts against the right end face of the inner ring middle sleeve and the right end face of the inner ring 13-1. By connecting a washer on the drive shaft 17, the washer and the inner ring sleeve stop nut 11 abut against the left end face of the inner ring middle sleeve and the left end face of the inner ring 13-1, respectively, thereby achieving the fixation of the inner ring 13-1 of the bearing under test 13.

[0032] In other embodiments, for example, when the tested rolling bearing is a single inner ring angular contact ball bearing, a fiber optic grating string 27 can be provided only at the middle position of the inner ring 13-1 and the outer ring 13-2. Then, the inner ring sleeve is divided into two sections along the axial direction, and receiving grooves are opened at the end faces of the adjacent outer peripheral surfaces of the two sections, so that the fiber optic grating string 27 is enclosed between the outer peripheral surface of the inner ring 13-1 and the outer peripheral surface of the inner ring sleeve. By providing a through hole on the inner ring sleeve to connect the receiving groove and the radial through hole on the drive shaft 17, the connecting wires of the fiber optic grating string 27 placed in the receiving groove pass through the through hole, the radial through hole and the central hole in sequence to connect to the fiber optic slip ring 8 and achieve the lead-out.

[0033] In other embodiments, when the drive shaft does not fully penetrate the inner sleeve, the inner sleeve still includes an inner left sleeve, an inner middle sleeve, and an inner right sleeve. The inner middle sleeve is provided with a content receiving groove for accommodating the fiber Bragg grating string 27, and also with a through hole communicating with the content receiving groove. The portion of the inner sleeve located to the right of the through hole is connected to the drive shaft and is interference-fitted with the drive shaft. The portion of the inner sleeve located to the left of the through hole protrudes from the end of the drive shaft, thereby allowing the connecting wires connected to the fiber Bragg grating string 27 to be directly led out.

[0034] In this case, to reliably fix the inner ring sleeve to the drive shaft, axially aligned holes are provided on the left, middle, and right inner ring sleeves. The left, middle, and right inner ring sleeves are then fixedly connected as a whole using bolts or pins. First, the bearing under test 13 is installed onto the inner ring sleeve. Then, the inner ring sleeves are connected as a whole. Finally, the inner ring sleeve is fixed to the drive shaft. For example, spot welding can be used, which not only fixes the inner ring sleeve and the drive shaft but also facilitates the removal of the weld points after testing, allowing the inner ring sleeve and the bearing under test 13 to be removed.

[0035] Based on the above implementation methods, such as Figure 2 As shown, a rotating flange 10 is connected to one end of the drive shaft 17, which has a central hole. The rotating flange 10 serves as a slip ring fixing component, connecting to the rotating end of the fiber optic slip ring 8. A slip ring mounting hole, coaxial with the drive shaft 17, is provided on the rotating flange 10, and the fixed end of the fiber optic slip ring 8 extends from the slip ring mounting hole. Specifically, the rotating end of the fiber optic slip ring 8 is connected to the slip ring mounting hole of the rotating flange 10. A slot matching the fixed end is provided on the slip ring support 9, and the fixed end of the fiber optic slip ring 8 is connected to the slip ring support 9 through the slot. The slip ring support 9 is fixedly connected to the base 26 to restrict the rotation of the fixed end of the fiber optic slip ring 8. Furthermore, the slip ring mounting hole on the rotating flange 10 can support the connecting wires of the fiber optic grating string 27, preventing the ends of the connecting wires of the fiber optic grating string 27 from disconnecting from the rotating end of the fiber optic slip ring 8 during the rotation of the drive shaft 17. In addition, a radially extending operating hole 30 is provided on the side wall of the rotary flange 10, allowing operators to connect the fiber optic slip ring 8 to the fiber optic grating string 27 via the operating hole 30, making operation more convenient. In other embodiments, the rotary flange 10 can be omitted, and the fixed end of the fiber optic slip ring 8 can be directly connected to an external acquisition device and signal analysis instrument. In this case, it is best to reinforce the connection point between the end of the connecting line to the fiber optic grating string 27 and the rotary end of the fiber optic slip ring 8.

[0036] Based on the above-described embodiments, the base 26 is further provided with a radial loading mechanism for applying radial loads to the outer ring sleeve and an axial loading mechanism for applying axial loads. Specifically, under the dynamic condition of the drive shaft 17 rotating, the axial loading mechanism and the radial loading mechanism can apply axial and radial loads to the outer ring sleeve individually or simultaneously, enabling the testing device to simulate complex working conditions such as high speed and variable load, thereby making the operating state of the tested bearing 13 more consistent with the real situation and making the test results more realistic. In addition, the load directly impacts the outer ring 13-2 of the tested bearing 13 through the outer ring sleeve, reducing the load loss transmitted in the middle, making the relationship between the change in the center wavelength of the fiber optic grating string 27 and the applied load more accurate, and making the contact state between the tested rolling element 13-3 and the raceway more accurate.

[0037] As a preferred implementation method, such as Figure 1 As shown, the outer circumferential surface of the outer ring sleeve has a notch, and the radial loading mechanism has a loading head 29 that matches the width of the notch to apply a radial load to the tested bearing 13 through the outer ring sleeve. Specifically, the loading head 29 is connected to the electronic universal testing machine 1. When applying the radial load, the loading head 29 is first controlled to descend and align with the notch on the outer circumferential surface of the outer ring sleeve, thereby further restricting the rotational freedom of the outer ring 13-2 of the tested bearing. The radial load is applied by a matching computer software electrically connected to the universal testing machine and transmitted to the outer ring 13-2 through the upper cylinder wall 14 of the outer ring, thereby achieving precise control of the radial loading load on the tested bearing 13. In other embodiments, the radial load can also be applied directly to the outer circumferential surface of the outer ring sleeve through the piston rod of the hydraulic cylinder.

[0038] As a preferred implementation method, such as Figure 1As shown, the axial loading mechanism includes a loading stud 4. A loading nut 5 and a pressure sensor 6 are sequentially connected to the loading stud 4 along the direction close to the outer ring sleeve. A loading sleeve 7 is provided between the pressure sensor 6 and the outer ring sleeve for contacting the end of the outer ring sleeve, so as to apply an axial load to the tested bearing 13 through the outer ring sleeve. Specifically, the loading stud 4 is connected to the base 26 through a stud support 3, and the loading sleeve 7 is connected to the base 26 through a loading sleeve support 2. An axial load is generated by tightening the loading nut 5, and this axial load is transmitted to the outer ring 13-2 of the tested bearing 13 through the pressure sensor 6, the loading sleeve 7, and the outer ring sleeve, achieving precise control of the axial load. The pressure sensor 6 is used to display the magnitude of the applied axial load. The contact between the loading sleeve 7 and the end face of the outer ring sleeve allows the axial load to be applied evenly to the outer ring sleeve and the outer ring 13-2 of the tested bearing 13. Furthermore, the loading sleeve 7 is also provided with a slot, through which the fixing part of the fiber optic slip ring 8 can pass to connect to the fiber optic grating demodulator. In other embodiments, the loading sleeve 7 may not have a slot, but instead a central through hole is provided in the loading stud 4, through which the fixing part of the fiber optic slip ring 8 can pass to connect to the fiber optic grating demodulator. Alternatively, the axial loading mechanism may directly use a hydraulic cylinder, applying an axial load to the end of the outer sleeve by means of the extension and retraction of the piston rod of the hydraulic cylinder.

[0039] During testing, under the dynamic condition of drive shaft 17 rotation, radial and axial loads are applied through radial and axial loading mechanisms. Besides obtaining the change in center wavelength using a fiber Bragg grating demodulator and analysis software, data can be recorded when the center wavelength data of the measurement points on the fiber Bragg grating string 27 stabilizes. This process is repeated three times under the same conditions, and the center wavelength test data from each measurement point on the fiber Bragg grating string 27 in the three tests are averaged. By analyzing the change in the center wavelength of the fiber Bragg grating, the contact state between the rolling element 13-3 of the tested bearing 13 and the raceway is determined. Repeating the test three times under the same conditions ensures the accuracy and reliability of the test data, thereby improving the accuracy of the test results.

[0040] Based on the above implementation methods, such as Figure 1 As shown, the drive shaft 17 is connected to the output end of the drive device via a flexible coupling 23. Specifically, the output shaft of the servo motor 24 is connected to the drive shaft 17 via the flexible coupling 23. The flexible coupling 23 can absorb the vibration caused by the power transmission of the drive device, thereby reducing the impact of the servo motor 24 on the load borne by the test bearing 13.

[0041] Based on the above implementation methods, such as Figure 1As shown, an auxiliary bearing 21 is also connected to the drive shaft 17 located between the flexible coupling 23 and the inner ring sleeve. The auxiliary bearing 21 can be a pair of tapered roller bearings. Specifically, the outer ring 13-2 of the auxiliary bearing 21 is fixed to the bearing housing 18 through the auxiliary outer sleeve 19, and the inner ring 13-1 of the auxiliary bearing 21 is connected to the drive shaft 17 through the auxiliary inner sleeve 20. The left end face of the auxiliary bearing 21 abuts against the shoulder on the drive shaft 17, and the right end face of the auxiliary bearing 21 is fixed by the auxiliary stop nut 22. The auxiliary bearing 21 can absorb some of the vibration caused by the rotation of the drive shaft 17, improve the stability of the drive shaft 17 during rotation, and at the same time reduce the impact load of the drive shaft 17 on the tested bearing 13, improve the accuracy of the change in the center wavelength of each measuring point on the fiber optic grating string 27, and thus improve the accuracy of the judgment of the contact state between the rolling element 13-3 and the raceway.

[0042] Specific implementation of the test method for the contact state of rolling elements and raceways in rolling bearings provided by this invention: A test method for the contact state of rolling elements and raceways in rolling bearings is provided. Based on the type of bearing under test and the test content, at least one fiber optic grating sensor is fixed on the outer circumferential surface of the outer ring and the inner circumferential surface of the inner ring of the bearing under test. The outer ring of the bearing under test is fixed, and the inner ring of the bearing under test is driven to rotate. The fiber optic grating sensor is connected to a data acquisition device, and the change in the center wavelength of the fiber optic grating sensor is analyzed to determine the contact area distribution of the rolling bearing, or to determine whether multi-point contact occurs in three-point or four-point contact ball bearings.

[0043] Specifically, the testing apparatus described in the above embodiments of the testing apparatus for the contact state of rolling elements and raceways of rolling bearings can be used to test the contact state of rolling elements and raceways of rolling bearings.

[0044] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. 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 testing device for the contact condition of rolling elements and raceways in rolling bearings, characterized in that, The device includes a base with a drive shaft that can output rotational power. The bearing under test is equipped with an inner ring sleeve that can be connected to the drive shaft to prevent rotation and an outer ring sleeve that is fixed relative to the base. The inner and outer ring sleeves are respectively provided with an inner ring limiting structure for fixing the inner ring of the bearing under test and an outer ring limiting structure for fixing the outer ring of the bearing under test. The inner ring sleeve is provided with an inner receiving groove for accommodating a fiber optic grating sensor on the inner circumference of the inner ring of the bearing under test. The outer ring sleeve is provided with an outer receiving groove for accommodating a fiber optic grating sensor on the outer circumference of the outer ring of the bearing under test. The inner and outer ring sleeves are respectively provided with through holes that communicate with the inner receiving groove and the outer receiving groove for the connecting wires of the fiber optic grating sensor to pass through. The connecting wires passing through the inner ring sleeve are connected to a fiber optic slip ring.

2. The testing device for the contact state of rolling elements and raceways in rolling bearings according to claim 1, characterized in that, The inner ring sleeve consists of an inner ring left sleeve, an inner ring middle sleeve, and an inner ring right sleeve. The diameter of the inner ring middle sleeve is smaller than that of the inner ring left sleeve and the inner ring right sleeve. The annular end faces of the inner ring left sleeve and the inner ring right sleeve, whose diameters extend beyond the inner ring middle sleeve, are used to stop and fit with the two ends of the inner ring of the bearing under test. The outer circumferential surface of the inner ring middle sleeve is used to make a clearance fit with the inner ring of the bearing under test, and together with the annular end face, it forms the inner ring limiting structure. The inner ring groove is provided on the inner ring middle sleeve.

3. The testing device for the contact state of rolling elements and raceways in rolling bearings according to claim 2, characterized in that, The outer ring sleeve is formed by two arc-shaped cylindrical walls. The inner arc surface of the arc-shaped cylindrical wall is provided with an outer groove for accommodating the outer ring of the bearing under test. The two side walls of the outer groove are respectively used to block the two ends of the outer ring of the bearing under test and form an outer ring limiting structure. The outer receiving groove is provided on the bottom wall of the outer groove. The through hole of the outer ring sleeve is provided on either arc-shaped cylindrical wall.

4. The testing apparatus for the contact state of rolling elements and raceways in rolling bearings according to any one of claims 1-3, characterized in that, The drive shaft is long enough to penetrate the inner ring sleeve, and the drive shaft is provided with a central hole and a radial through hole, the radial through hole being connected to the through hole on the inner ring sleeve.

5. The testing device for the contact state of rolling elements and raceways in rolling bearings according to claim 4, characterized in that, One end of the drive shaft is connected to a detachable slip ring retainer. The slip ring retainer has a slip ring mounting hole that is coaxial with the drive shaft. The fixed end of the fiber optic slip ring passes through the slip ring mounting hole and is led out, while the rotating end faces the center hole and is connected to the connecting line.

6. The testing device for the contact state of rolling elements and raceways in rolling bearings according to claim 4, characterized in that, The drive shaft is provided with a shoulder for stopping one end of the inner ring sleeve, and is connected with a retaining ring for stopping the other end of the inner ring sleeve.

7. The testing apparatus for the contact state of rolling elements and raceways in rolling bearings according to any one of claims 1-3, characterized in that, The base is also equipped with a radial loading mechanism for applying radial load to the outer ring sleeve and an axial loading mechanism for applying axial load.

8. The testing apparatus for the contact state of rolling elements and raceways in rolling bearings according to claim 7, characterized in that, The outer circumferential surface of the outer sleeve is provided with a notch, and the radial loading mechanism has a loading head that matches the notch.

9. The testing apparatus for the contact state of rolling elements and raceways in rolling bearings according to claim 7, characterized in that, The axial loading mechanism includes a loading stud, and a loading nut and a pressure sensor are sequentially connected to the loading stud along the direction close to the outer ring sleeve. A loading sleeve is provided between the pressure sensor and the outer ring sleeve for abutting against the end of the outer ring sleeve.

10. A test method for the contact state between rolling elements and raceways in rolling bearings, characterized in that, Depending on the type of bearing under test and the test content, at least one fiber optic grating sensor is fixed on the outer circumferential surface of the outer ring and the inner circumferential surface of the inner ring of the bearing under test. The outer ring of the bearing under test is fixed, and the inner ring of the bearing under test is driven to rotate. The fiber optic grating sensor is connected to the acquisition device, and the change in the center wavelength of the fiber optic grating sensor is analyzed to determine the contact area distribution of the rolling bearing, or to determine whether multi-point contact occurs in a three-point or four-point contact ball bearing.

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