Rotor cage end torsional vibration characteristics test device and test method

Abstract

The present invention relates to the field of motor technology, and in particular to a device and method for testing the torsional vibration characteristics of a rotor cage end. The testing device includes two sets of clamping mechanisms, which are symmetrically distributed on the left and right and have a working area reserved therebetween. The clamping mechanism includes two clamping pieces symmetrically distributed front and back, the lower ends of the clamping pieces are fixed on a base plate, and the two clamping pieces are interspersed with a pair of adjusting bolts arranged front and back; an exciter; a clamping mechanism, located in the working area, including a connecting plate, which is parallel to the base plate and connected to the output end of the exciter, and a clamping piece suitable for clamping a guide bar is provided on the connecting plate; a force sensor; and an acceleration sensor. The testing device provided by the present invention can measure the torsional vibration characteristics of a single guide bar with two end rings, and then obtain the torsional vibration characteristics of the rotor cage end, thereby avoiding the use of an overall rotor test, reducing the test scale and test cost, and improving the test efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a device and method for testing torsional vibration characteristics of a rotor cage end. Background Art

[0002] The rotor cage consists of an iron core, conductive bars, and end rings. The iron core, part of the motor's main magnetic circuit, is made of stacked silicon steel sheets. The core's punched sheets have uniformly spaced slots. Multiple conductive bars are installed within these slots, with their ends extending from the core to form cantilevered ends. Two end rings are provided, connecting the two cantilevered ends of each conductive bar.

[0003] The rotor cage has the following structural characteristics: First, a periodic structure characterized by identical bars arranged periodically along the circumference; and second, a discontinuous structure characterized by the absence of contact between the end rings and the core, with torque transmitted through the bars. These structural characteristics inevitably lead to inherent torsional vibration at the rotor cage ends (the bars protrude significantly and exhibit significant elasticity; the moment of inertia of the rotor end, where the end rings and bars meet, differs from that of the core itself, resulting in uneven distribution of the inertia along the motor axis). During torsional vibration, alternating torsional stresses act on the components. As fatigue accumulates over time, small cracks and cuts gradually form, which then spread, expand, and merge. This gradually weakens the rotor cage bars, and insufficient strength at certain operating points can lead to bar fracture. Therefore, understanding the torsional vibration characteristics of the rotor cage ends and preventing and suppressing the effects of torsional resonance at the rotor cage ends can significantly improve the structural reliability of the rotor cage.

[0004] Existing rotor cage end torsional vibration testing is typically performed using end-to-end torsional vibration testing facilities. Due to the large size of the rotor cage, these tests are time-consuming and energy-intensive. They also require high test bench support capacity, complex clamping device design, and high transportation and testing costs. Summary of the Invention

[0005] In order to overcome the technical defects of the existing rotor cage end torsional vibration characteristic test, such as time-consuming and energy-consuming, high test tonnage support requirements, cumbersome clamping devices, and high transportation and testing costs, the present invention provides a rotor cage end torsional vibration characteristic test device and test method.

[0006] The present invention provides a device for testing the torsional vibration characteristics of a rotor cage end, comprising:

[0007] base plate;

[0008] Two sets of clamping mechanisms are both located on the base plate. The two sets of clamping mechanisms are symmetrically distributed left and right with a working area reserved between them. The clamping mechanisms include two clamping members symmetrically distributed front and back. The lower ends of the clamping members are fixed to the base plate. A clamping area suitable for clamping the end ring portion is formed between the two clamping members. The two clamping members are interspersed with a pair of adjusting bolts arranged front and back.

[0009] a vibration exciter mounted on the base plate and adapted to provide vibration in a front-to-back direction;

[0010] A clamping mechanism is located in the working area, the clamping mechanism includes a connecting plate, the connecting plate is parallel to the bottom plate and connected to the output end of the exciter, and the connecting plate is provided with a clamping piece suitable for clamping the guide bar;

[0011] A force sensor is mounted on the clamping mechanism or the vibration exciter;

[0012] The acceleration sensor is suitable for being installed on the portion of the guide bar that extends out of the clamping piece.

[0013] Optionally, the clamping member includes:

[0014] Two clamping plates, adapted to butt joint to clamp the middle portion of the guide bar, wherein the surfaces of the clamping plates adapted to contact the guide bar are provided with a clamping groove adapted to the guide bar;

[0015] Two hoops are respectively suitable for clamping the two ends of the clamping plate, and the hoops are fixed on the connecting plate.

[0016] Optionally, the hoop comprises:

[0017] The hoop body is formed by integrally forming a chassis and a U-shaped clamp, wherein the opening of the U-shaped clamp faces the chassis, and the chassis is fixed to the connecting plate;

[0018] The locking screw is screwed onto the wing of the U-shaped clamp and is suitable for compressing the guide bar inserted into the U-shaped clamp.

[0019] Optionally, the force sensor is mounted on the clamping plate.

[0020] Optionally, a support block is fixed between the two clamping members, and the support block is provided with a through hole larger in size than the adjusting bolt pair, and the adjusting bolt pair is inserted into the through hole.

[0021] Optionally, the clamping member includes an L-shaped plate integrally formed by a horizontal plate and a vertical plate, the vertical plate is perpendicular to the base plate, one end of the vertical plate away from the horizontal plate is fixed to the base plate, and the support block and the clamping area are both located at the position of the horizontal plate.

[0022] Optionally, the clamping member also includes a longitudinal plate, which is integrally formed with the horizontal plate and the vertical plate and is perpendicular to the horizontal plate and the vertical plate. The longitudinal plate is connected to the end of the vertical plate away from the horizontal plate and is fixed to the bottom plate. A reinforcing rib plate is connected between the longitudinal plate and the vertical plate.

[0023] The present invention provides a method for testing the torsional vibration characteristics of a rotor cage end, comprising the following steps:

[0024] S1. Determine the structural parameters of the rotor cage end: number of bars n , cantilever length of guide bar l 1. Guide bar cross-section width b , guide bar section height h , equivalent turning radius of the guide bar R , end ring length l 2. End ring outer diameter D , end ring inner diameter d ;

[0025] S2. Determine the overall torsional stiffness of the rotor cage end using the following formula: K :

[0026]

[0027] Where, K 1 is the torsional stiffness of the cantilever end guide bar, K 2 is the torsional stiffness of the end ring, G 1 is the shear modulus of the conductor bar, G 2 is the shear modulus of the end ring, E is the elastic modulus of the guide bar, I is the moment of inertia of the guide bar, β is the coefficient of pure torsion of a rectangular cross-section rod;

[0028] S3. Build the rotor cage end torsional vibration characteristic test device as described in any one of claims 1 to 7, and select a single conductor bar with two end rings, reinforce the conductor bar through the clamping mechanism, and make the conductor bar cantilever length also l 1. Clamp the end rings at both ends of a single guide bar through two sets of clamping mechanisms, and preset the tightening torque through the adjusting bolt pair. M ;

[0029] S4. Preset tightening torque by adjusting the adjusting bolt pair M The size of the single conductor bar with two end rings makes the equivalent stiffness of the transverse bending K 1= K ;

[0030] S5. Perform a frequency sweep test on a single conductor bar with two end rings to obtain the torsional vibration characteristics of the single conductor bar with two end rings, that is, the torsional vibration characteristics of the rotor cage end.

[0031] Optionally, step S4 includes the following sub-steps:

[0032] 1) Calculate the transverse bending stiffness of a single conductor bar with two end rings according to the following formula: K Theoretical value of natural frequency when ω' :

[0033]

[0034] Where, m is the total mass of the cantilever portion of the conductor bar and the two end rings;

[0035] 2) Perform a frequency sweep test and obtain a spectrum based on Fourier transform. Then, find the natural frequency measurement value of a single conductor bar with two end rings from the spectrum. ω 1;

[0036] 3) Comparison ω and ω' ;

[0037] 4) If they are equal, then the transverse bending stiffness of a single conductor bar with two end rings is K 1. If they are not equal, it is necessary to adjust the preset tightening torque of the adjusting bolt pair. M , and repeat steps 2) and 3) until the obtained ω 1'= ω' , then the transverse bending stiffness of a single conductor bar with two end rings is K 1.

[0038] The technical solution provided by the present invention has the following advantages compared with the prior art:

[0039] The rotor cage end torsional vibration characteristic testing device provided by the present invention is equipped with two sets of clamping mechanisms and a clamping mechanism, which can simulate the assembly state of the guide bars in the rotor cage and provide a hardware basis for experimental testing; it is also equipped with an exciter, a force sensor and an acceleration sensor. The exciter can provide a lateral bending environment, the force sensor can control the output parameters of the exciter, and the acceleration sensor can measure the vibration parameters of the guide bar, so that the device can measure the torsional vibration characteristics of a single guide bar with two end rings, and then obtain the torsional vibration characteristics of the rotor cage end.

[0040] The present invention provides a method for testing the torsional vibration characteristics of a rotor cage end. This method utilizes local model preparation and testing analysis, targeting the characteristic structure of the cage rotor's bar-end ring connection. This method determines the bending vibration characteristics of the cage model and, in turn, provides overall torsional vibration data for the cage rotor end. This method avoids the need for testing the entire rotor, reduces test scale and cost, and improves test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0043] Figure 1 Schematic diagram of the overall structure of the rotor cage end torsional vibration characteristics testing device according to an embodiment of the present invention;

[0044] Figure 2 Schematic diagram of the assembly structure of the clamping mechanism and the vibration exciter according to an embodiment of the present invention;

[0045] Figure 3 This is a schematic structural diagram of the clamping mechanism according to an embodiment of the present invention;

[0046] Figure 4 This is a schematic structural diagram of the clamping member according to an embodiment of the present invention;

[0047] Figure 5 It is the structural diagram of the rotor cage to be tested;

[0048] Figure 6 It is a schematic diagram of the structure of a single conductor bar with two end rings;

[0049] Figure 7 Schematic diagram of the deflection angle formed by the motion trajectory of the center point of a single conductor bar in the rotor cage;

[0050] Figure 8 is a schematic diagram of the deformation profile of the guide bar;

[0051] Figure 9-10 Schematic diagram of the structural parameters of the rotor cage end in step S1 of the method for testing the torsional vibration characteristics of the rotor cage end according to an embodiment of the present invention;

[0052] Figure 11 This is a vibration curve diagram of a single conductive bar with two end rings measured by the rotor cage end torsional vibration characteristic testing method described in an embodiment of the present invention.

[0053] in:

[0054] 1. Base plate; 2. Clamping mechanism; 21. Clamping part; 211. Horizontal plate; 212. Vertical plate; 213. Longitudinal plate; 214. Reinforcing rib plate; 22. Adjusting bolt pair; 23. Support block; 3. Vibrator; 4. Clamping mechanism; 41. Connecting plate; 42. Clamping part; 421. Clamp; 4222. Clamp; 4221. Chassis; 4222. U-shaped clamp; 4223. Locking screw; 5. Force sensor; 6. Acceleration sensor. DETAILED DESCRIPTION

[0055] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0056] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0057] First, the experimental principles of the test device and test method adopted in the present invention are explained.

[0058] like Figure 5 As shown, the rotor cage consists of a rotor core, a number of conductor bars and two end rings. The conductor bars extend outward from the rotor core to form two cantilever ends, and the two cantilever ends are respectively welded to the two end rings.

[0059] like Figure 6 As shown, a single conductor bar with two end ring portions comprises a conductor bar and two end ring portions, wherein the end ring portion is a portion where the end ring is connected to the single conductor bar.

[0060] like Figure 7 As shown in the figure, the original center point A of the guide bar moves to the center point B after the end is twisted, and the two bottom edges of the cantilever end of the guide bar are relatively deflected to form a deflection angle γ , we get through calculation and analysis:

[0061]

[0062] Where h is the cross-sectional height of the guide bar, a is the distance from the center O of the end face to the line segment AB, and R is the equivalent turning radius of the guide bar.

[0063] From the above formula, it can be deduced , indicating that the deflection angle is extremely small and approximately zero.

[0064] According to vibration theory, the bending vibration of the free restrained beam at any time can be considered as vibration in the plane, that is, its vibration curve can be considered as a plane curve. Combined with the structural characteristics of the rotor cage end, the vibration characteristics of the conductor bar can be calculated according to Figure 8 The equivalence is performed, that is, under certain conditions, the lateral vibration characteristics of the conductor bar are consistent with the torsional vibration characteristics.

[0065] In one embodiment, referring to Figures 1 to 4 The rotor squirrel cage end torsional vibration characteristic test device includes: a base plate 1; two sets of clamping mechanisms 2, both located on the base plate 1, the two sets of clamping mechanisms 2 are symmetrically distributed on the left and right and a working area is reserved between them, the clamping mechanism 2 includes two clamping members 21 symmetrically distributed front and back, the lower end of the clamping member 21 is fixed on the base plate 1, and a clamping area suitable for clamping the end ring is formed between the two clamping members 21, and the two clamping members 21 are interspersed with a front-to-back adjustment bolt pair 22; an exciter 3, installed on the base plate 1 and suitable for providing vibration in the front-to-back direction; a clamping mechanism 4, located in the working area, the clamping mechanism 4 includes a connecting plate 41, the connecting plate 41 is parallel to the base plate 1 and connected to the output end of the exciter 3, and a clamping member 42 suitable for clamping the guide bar is provided on the connecting plate 41; a force sensor 5, installed on the clamping mechanism 4 or the exciter 3; an acceleration sensor 6, suitable for being installed on the part of the guide bar extending out of the clamping member 42.

[0066] Specifically, the clamping member 21 includes an L-shaped plate integrally formed by a horizontal plate 211 and a vertical plate 212. The vertical plate 212 is perpendicular to the bottom plate 1, and the end of the vertical plate 212 away from the horizontal plate 211 is fixed to the bottom plate 1. Of course, as an alternative embodiment, the clamping member 21 can also have only the vertical plate 212 structure. Furthermore, the clamping member 21 also includes a longitudinal plate 213. The longitudinal plate 213 is integrally formed with the horizontal plate 211 and the vertical plate 212 and is perpendicular to the horizontal plate 211 and the vertical plate 212. The longitudinal plate 213 is connected to the end of the vertical plate 212 away from the horizontal plate 211 and is fixed to the bottom plate 1. A reinforcing rib plate 214 is connected between the longitudinal plate 213 and the vertical plate 212.

[0067] It is easy to understand that the adjusting bolt pair 22 is composed of a bolt and a nut. The bolt passes through the two clamping members 21 , with the bolt head placed on one side of the two clamping members 21 and the nut placed on the other side of the two clamping members 21 .

[0068] Specifically, the clamping member 42 comprises two clamping plates 421 adapted to butt joint and clamp the middle portion of the conductor bar. The surfaces of the clamping plates 421 that contact the conductor bar are provided with slots adapted to the conductor bar. Two hoops 422, adapted to clamp the ends of the clamping plates 421, are secured to the connecting plate 41. The use of two clamping plates 421 ensures that the cantilever length of the conductor bar is consistent with that of the conductor bar in the rotor cage structure. The slots better align with the rotor core's grip on the conductor bar, ensuring a secure clamping position. More specifically, the hoop 422 includes: a hoop 422 body, which is integrally formed by a chassis 4221 and a U-shaped clip 4222, the opening of the U-shaped clip 4222 faces the chassis 4221, and the chassis 4221 is fixed on the connecting plate 41; a locking screw 4223, which is screwed onto the wing of the U-shaped clip 4222 and is suitable for tightening the guide bar inserted into the U-shaped clip 4222.

[0069] Furthermore, when the clamping member 42 includes a clamping plate 421, the force sensor 5 is mounted on the clamping plate 421. The clamping plate 421 fits the guide bar and has a high degree of similarity in vibration state. Mounting the force sensor 5 on the clamping plate 421 helps ensure the accuracy of the vibration parameters output by the exciter 3.

[0070] The rotor cage end torsional vibration characteristic testing device of this embodiment is provided with two sets of clamping mechanisms 2 and a clamping mechanism 4, which can simulate the assembly state of the guide bars in the rotor cage and provide a hardware basis for experimental testing; it is also provided with an exciter 3, a force sensor 5 and an acceleration sensor 6. The exciter 3 can provide a lateral bending environment, the force sensor 5 can control the output parameters of the exciter 3, and the acceleration sensor 6 can measure the vibration parameters of the guide bar, so that the device can measure the torsional vibration characteristics of a single guide bar with two end rings, and then obtain the torsional vibration characteristics of the rotor cage end.

[0071] In some embodiments, a support block 23 is fixed between the two clamping members 21. The support block 23 defines a through-hole that is larger than the adjusting bolt pair 22, through which the adjusting bolt pair 22 is inserted. The support block 23 supports the two clamping members 21, preventing significant deformation at the location where the adjusting bolt pair 22 is inserted, thereby ensuring that the clamping torque is transmitted to the clamping area.

[0072] Furthermore, the support block 23 and the clamping area are both located where the transverse plate 211 is located.

[0073] In another embodiment, referring to Figures 1 to 4 、 Figures 9 and 10 The method for testing the torsional vibration characteristics of the rotor cage end includes the following steps:

[0074] S1. Determine the structural parameters of the rotor cage end: number of bars n , cantilever length of guide bar l 1. Guide bar cross-section widthb , guide bar section height h , equivalent turning radius of the guide bar R , end ring length l 2. End ring outer diameter D , end ring inner diameter d ;

[0075] S2. Determine the overall torsional stiffness of the rotor cage end using the following formula: K :

[0076]

[0077] Where, K 1 is the torsional stiffness of the cantilever end guide bar, K 2 is the torsional stiffness of the end ring, G 1 is the shear modulus of the conductor bar, G 2 is the shear modulus of the end ring, E is the elastic modulus of the guide bar, I is the moment of inertia of the guide bar, β is the coefficient of pure torsion of a rectangular cross-section rod;

[0078] S3. Build a rotor cage end torsional vibration characteristic test device as claimed in any one of claims 1 to 7, and select a single conductor bar with two end rings, reinforce the conductor bar through the clamping mechanism 4, and make the conductor bar cantilever length also l 1. Clamp the end rings at both ends of a single guide bar through two sets of clamping mechanisms 2, and adjust the preset tightening torque by adjusting the bolt pair 22. M ;

[0079] S4. Preset tightening torque by adjusting the adjusting bolt pair 22 M The size of the single conductor bar with two end rings makes the equivalent stiffness of the transverse bending K 1= K ;

[0080] S5. Perform a frequency sweep test on a single conductor bar with two end rings to obtain the torsional vibration characteristics of the single conductor bar with two end rings, that is, the torsional vibration characteristics of the rotor cage end.

[0081] Specifically, step S4 includes the following sub-steps:

[0082] 1 According to the following formula, the transverse bending stiffness of a single conductor bar with two end rings is calculated as follows: K Theoretical value of natural frequency when ω' :

[0083]

[0084] Where, m is the total mass of the cantilever portion of the conductor bar and the two end rings;

[0085] 2. Perform a frequency sweep test and obtain a spectrum based on Fourier transform. Then find the natural frequency measurement value of a single conductor bar with two end rings from the spectrum. ω 1;

[0086] 3 Comparison ω and ω' ;

[0087] 4 If they are equal, then the transverse bending stiffness of a single conductor bar with two end rings is K 1. If they are not equal, adjust the preset tightening torque of the adjusting bolt pair 22. M , and repeat steps 2 and 3 until the resulting ω 1'= ω' , then the transverse bending stiffness of a single conductor bar with two end rings is K 1.

[0088] The rotor cage end torsional vibration characteristics testing method provided in this embodiment utilizes localized model preparation and testing analysis to analyze the characteristic structure of the cage rotor's bar-end ring connection. This method determines the bending vibration characteristics of the cage model and, in turn, obtains overall torsional vibration characteristics data for the cage rotor end. This method avoids the need for testing the entire rotor, reduces test scale and cost, and improves test efficiency.

[0089] like Figure 11 As shown, is the first-order resonance frequency, is the second-order resonance frequency, and are the ±10% boundary points from the first-order resonance frequency, is the vibration magnitude of the first-order resonance frequency, and are the vibration magnitudes at the frequency points of and. Therefore, the amplification factor .

[0090] Based on the amplification factor and other torsional vibration characteristic parameters of the squirrel cage rotor end, such as the modal characteristics of the same-direction torsional vibration mode and the end reverse torsional vibration mode, and combined with the external circuit control characteristics of the traction motor, the influence of torsional vibration resonance on the squirrel cage end can be prevented and suppressed, thereby greatly improving the structural reliability of the squirrel cage rotor.

[0091] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments described herein, but is to be construed in the widest possible manner consistent with the principles and novel features disclosed herein.

Claims

1. A device for testing the torsional vibration characteristics of a rotor cage end, characterized in that: include: Bottom plate (1); Two sets of clamping mechanisms (2) are both located on the base plate (1). The two sets of clamping mechanisms (2) are symmetrically distributed left and right and a working area is reserved between them. The clamping mechanism (2) includes two clamping members (21) symmetrically distributed front and back. The lower ends of the clamping members (21) are fixed on the base plate (1). A clamping area suitable for clamping the end ring is formed between the two clamping members (21). The two clamping members (21) are interspersed with a front-to-back arranged adjustment bolt pair (22). A support block (23) is fixed between the two clamping members (21). The support block (23) is provided with a through hole larger than the adjusting bolt pair (22), the adjusting bolt pair (22) is inserted into the through hole, the clamping member (21) comprises an L-shaped plate integrally formed by a horizontal plate (211) and a vertical plate (212), the vertical plate (212) is perpendicular to the bottom plate (1), and one end of the vertical plate (212) away from the horizontal plate (211) is fixed to the bottom plate (1), and the support block (23) and the clamping area are both located at the position of the horizontal plate (211); a vibration exciter (3) mounted on the base plate (1) and adapted to provide vibration in a front-to-back direction; A clamping mechanism (4) is located in the working area, and the clamping mechanism (4) includes a connecting plate (41), the connecting plate (41) is parallel to the bottom plate (1) and connected to the output end of the exciter (3), and the connecting plate (41) is provided with a clamping member (42) suitable for clamping the guide bar; the clamping member (42) includes two clamping plates (421) and two hoops (422), the two clamping plates (421) are suitable for docking to clamp the middle part of the guide bar, the surface of the clamping plate (421) suitable for contacting the guide bar is provided with a groove adapted to the guide bar, and the two hoops (422) are respectively suitable for clamping the two ends of the clamping plate (421), and the hoops (422) are fixed on the connecting plate (41); A force sensor (5) mounted on the clamping plate (421); The acceleration sensor (6) is suitable for being mounted on the portion of the guide bar that extends outside the clamping member (42).

2. The rotor cage end torsional vibration characteristic testing device according to claim 1, characterized in that: The hoop (422) comprises: The hoop (422) body is formed integrally from a chassis (4221) and a U-shaped clamp (4222), the opening of the U-shaped clamp (4222) faces the chassis (4221), and the chassis (4221) is fixed on the connecting plate (41); The locking screw (4223) is screwed onto the wing of the U-shaped clamp (4222) and is suitable for tightening the guide bar inserted into the U-shaped clamp (4222).

3. The rotor cage end torsional vibration characteristic testing device according to claim 1, characterized in that: The clamping member (21) further includes a longitudinal plate (213), wherein the longitudinal plate (213) is integrally formed with the transverse plate (211) and the vertical plate (212) and is perpendicular to the transverse plate (211) and the vertical plate (212), the longitudinal plate (213) is connected to an end of the vertical plate (212) away from the transverse plate (211) and is fixed to the bottom plate (1), and a reinforcing rib plate (214) is connected between the longitudinal plate (213) and the vertical plate (212).

4. A method for testing the torsional vibration characteristics of a rotor cage end, characterized in that: The steps include: S1. Determine the structural parameters of the rotor cage end: number of bars n , cantilever length of the guide bar l 1. Guide bar cross-section width b , guide bar section height h , equivalent turning radius of the guide bar R , end ring length l 2. End ring outer diameter D , end ring inner diameter d ; S2. Determine the overall torsional stiffness of the rotor cage end using the following formula: K : ； Where, K 1 is the torsional stiffness of the cantilever end guide bar, K 2 is the torsional stiffness of the end ring, G 1 is the shear modulus of the conductor bar, G 2 is the shear modulus of the end ring, E is the elastic modulus of the guide bar, I is the moment of inertia of the guide bar, β is the coefficient of pure torsion of a rectangular cross-section rod; S3. Build the rotor cage end torsional vibration characteristic test device as described in any one of claims 1 to 3, and select a single conductor bar with two end rings, reinforce the conductor bar through the clamping mechanism (4), and make the conductor bar cantilever length also l 1. Clamp the end rings at both ends of a single guide bar by two sets of clamping mechanisms (2), and preset the tightening torque by the adjusting bolt pair (22). M ; S4. Preset tightening torque by adjusting the adjusting bolt pair (22) M The size of the single conductor bar with two end rings makes the equivalent stiffness of the transverse bending K 1= K ; S5. Perform a frequency sweep test on a single conductor bar with two end rings to obtain the torsional vibration characteristics of the single conductor bar with two end rings, that is, the torsional vibration characteristics of the rotor cage end.

5. The method for testing the torsional vibration characteristics of the rotor cage end according to claim 4, characterized in that: Step S4 includes the following sub-steps: 1) Calculate the transverse bending stiffness of a single conductor bar with two end rings according to the following formula: K Theoretical value of natural frequency when ω' : ； Where, m is the total mass of the cantilever portion of the conductor bar and the two end rings; 2) Perform a frequency sweep test and obtain a spectrum based on Fourier transform. Then, find the natural frequency measurement value of a single conductor bar with two end rings from the spectrum. ω ; 3) Comparison ω and ω' ; 4) If they are equal, then the transverse bending stiffness of a single conductor bar with two end rings is K 1; If they are not equal, it is necessary to adjust the preset tightening torque of the adjusting bolt pair (22) M , and repeat steps 2) and 3) until the obtained ω = ω' , then the transverse bending stiffness of a single conductor bar with two end rings is K 1.

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