Motor rotor precision bearing assembly tool and assembly method thereof

Abstract

The application discloses a motor rotor precision bearing assembly tool, which comprises a pressing mandrel and a pressing sleeve. The pressing mandrel comprises a top block and a protruding block, the top block is provided with a sinking groove, the protruding block is provided with a clearance groove, and the sinking groove and the clearance groove are provided with a clearance hole. The upper part of the pressing sleeve is provided with a step. The pressing sleeve is provided with a bearing mounting shaft. The bearing mounting shaft is provided with a positioning groove and a containing groove, and the positioning groove and the containing groove are provided with a shaft hole. The shaft hole is provided with a center positioning shaft. The center positioning shaft is provided with a center. The containing groove is provided with a center spring. The center positioning shaft is provided with a return spring. The motor rotor precision bearing assembly tool can realize accurate pre-alignment of the bearing and the rotor shaft, ensure that the assembly coaxial degree and dynamic balance precision meet the process requirements, improve the one-time pressing assembly qualified rate, and greatly reduce the quality risk and production cost of rotor shaft pressing injury and bearing scrapping. Correspondingly, the application also provides a motor rotor precision bearing assembly method.

Description

Technical Field

[0001] This invention relates to assembly fixtures for motor components, specifically to a precision bearing assembly fixture for a motor rotor and its assembly method. Background Technology

[0002] The locomotive fuel pump motor is a core power component of the locomotive's fuel supply system, and the assembly precision of its rotor assembly directly determines the motor's operational stability and service life. The assembly of the rotor shaft and precision bearings is a critical process. The rotor shaft and bearing inner rings must be aligned with high precision, press-fitted in one step, and both coaxiality and balance must meet the process design requirements. If there is a deviation in the bearing assembly position, it will cause damage to the rotor shaft surface, rendering it unusable. Furthermore, it will cause uneven stress on the bearing inner ring, leading to premature damage and ultimately rendering the entire rotor assembly unusable. If substandard products flow into the downstream assembly stage and are eventually put into operation, they can cause serious safety accidents such as motor overheating and winding burnout, threatening the safe operation of the locomotive.

[0003] The current industry standard for this assembly process is as follows: the rotor is placed vertically on the hydraulic press table without any bearing alignment assistance. The bearing is directly fitted onto the rotor shaft end and then pressed in. The entire process relies entirely on the operator's experience for manual alignment and pressing, without any dedicated alignment fixtures. This assembly method is highly susceptible to human error, easily leading to misalignment between the bearing and the rotor shaft. This can result in quality defects such as rotor shaft damage and bearing failure, resulting in a low product assembly pass rate, high production costs, and the risk of defective products causing safety accidents.

[0004] Therefore, there is an urgent need for an assembly method that can accurately guarantee the alignment accuracy of the bearing and the rotor shaft and achieve stable one-time press-fit qualification in order to solve the above-mentioned problems existing in the current technology. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a precision bearing assembly fixture for motor rotors. This fixture employs a specific structural design to achieve precise pre-alignment of the bearing and rotor shaft, ensuring that assembly coaxiality and dynamic balance accuracy meet process requirements. This improves the first-pass yield rate, significantly reduces the quality risks and production costs associated with rotor shaft damage and bearing failure, and eliminates the potential for motor burnout and locomotive safety threats caused by substandard products entering the market. Correspondingly, this application also provides a method for assembling precision bearings for motor rotors.

[0006] Regarding the tooling, the technical solution of this application is as follows:

[0007] A precision bearing assembly fixture for a motor rotor includes a clamping mandrel and a clamping sleeve. The clamping mandrel has an inverted U-shaped structure, including a top block and a protrusion. The top block has a countersunk groove, and the protrusion has a relief groove. A relief hole is provided between the countersunk groove and the relief groove. The upper part of the clamping sleeve has a step. The outer circumferential surface of the top block slides with the inner circumferential surface of the clamping sleeve, and the bottom surface of the top block abuts against the stepped surface of the step. A bearing mounting shaft is provided in the clamping sleeve, and the two slide with each other. The upper end of the bearing mounting shaft has a positioning groove, and the lower end has a receiving groove. A shaft hole is provided between the positioning groove and the receiving groove. The inner circumferential surface of the positioning groove slides with the outer circumferential surface of the protrusion. The shaft hole contains... A central positioning shaft is inserted, and the two are slidably engaged; the upper end of the central positioning shaft is located in a recess and is axially limited by a limiting member; the lower end of the central positioning shaft is provided with a center point, which extends out of the lower end face of the bearing mounting shaft; a center point spring is provided in the receiving groove, one end of the center point spring abuts against the bottom of the receiving groove, and the other end abuts against the center point; a return spring is sleeved on the central positioning shaft, the upper end of the return spring abuts against the bottom of the clearance groove, and the lower end abuts against the bottom of the positioning groove; the lower part of the bearing mounting shaft, relative to the clamping sleeve, protrudes for mounting the bearing, its outer circumference is cylindrical, and its axis coincides with the axis of the central positioning shaft.

[0008] Compared with existing technologies, the precision bearing assembly fixture for motor rotors of this invention allows for precise pre-alignment of the bearing and rotor shaft by first mounting the bearing on the bearing mounting shaft and then placing the entire fixture on the rotor shaft. The center and positioning hole work together to automatically center the bearing, achieving accurate pre-alignment. Then, by pressing down on the mandrel and using the squeezing action of the clamping sleeve, the bearing is pressed into the rotor shaft, thus completing the assembly of the motor rotor bearing. This improves the first-pass yield while ensuring that the coaxiality and dynamic balance accuracy meet process requirements, significantly reducing the quality risks and production costs associated with rotor shaft damage and bearing failure. It eliminates the potential for substandard products entering the market and causing motor burnout or threatening locomotive safety. Furthermore, after assembly, the clamping sleeve and mandrel automatically reset under spring action. Removing the fixture also allows the center to reset under spring action, effectively reducing manual operation steps and minimizing the time required for batch assembly.

[0009] As an optimization, in the aforementioned precision bearing assembly fixture for the motor rotor, the inner circumferential surface of the step and the outer circumferential surface of the top block are interference-fitted to form a fixed structure. Thus, the clamping mandrel and the compression sleeve form an integral structure, preventing the clamping sleeve from falling off when the bearing is not installed; furthermore, the interference fit eliminates the need for additional fasteners such as screws, resulting in a simpler and more compact overall structure, and ensuring the alignment of the connecting components.

[0010] As an optimization, in the aforementioned precision bearing assembly fixture for motor rotors, the clamping sleeve includes a set of clamping modules distributed circumferentially and an upper elastic clamping ring that clamps the clamping modules; the upper end of the top block is threadedly connected to an upper wedge ring; the lower end of the top block is provided with an A-connecting groove in the radial direction, and the clamping module is provided with an A-connecting post correspondingly, the A-connecting post slidingly engaging with the A-connecting groove and providing axial and circumferential limiting for the clamping module; the upper end of the clamping module is provided with a partial conical surface structure, which engages with the outer circumferential surface of the upper wedge ring to form a wedge mechanism; when the upper wedge ring moves downward, the clamping module moves radially outward along the clamping mandrel under the squeezing action of the upper wedge ring, achieving expansion; when the upper wedge ring moves upward, the clamping module moves radially inward along the clamping mandrel under the clamping action of the upper elastic clamping ring, achieving contraction; the bearing is installed The shaft includes an inner ring of the base, a set of bearing mounting modules distributed circumferentially on the outer side of the inner ring, and a lower elastic clamping ring that clamps the bearing mounting modules. The lower part of the inner ring is threadedly connected to a lower wedge-shaped ring. A B-connecting groove is radially provided on the inner ring, and a corresponding B-connecting post is provided on each bearing mounting module. The B-connecting post slides into the B-connecting groove, providing axial and circumferential limiting for the bearing mounting module. The lower end of the bearing mounting module has a partially conical structure that engages with the outer circumferential surface of the lower wedge-shaped ring to form a wedge mechanism. When the lower wedge-shaped ring moves upward, the bearing mounting module expands radially outward along the inner ring under the squeezing action of the lower wedge-shaped ring. When the lower wedge-shaped ring moves downward, the bearing mounting module contracts radially inward along the inner ring under the clamping action of the lower elastic clamping ring. Therefore, by adjusting the heights of the upper and lower wedge-shaped rings, the size of the clamping sleeve can be adjusted, and the size of the bearing mounting shaft can be adjusted simultaneously, thus adapting to bearings of different inner diameters and improving the practicality of the tooling. For mass production, assembly fixtures can be made for different bearing specifications. However, for small-batch production, especially for non-standard sized bearing assembly, making separate assembly fixtures will affect production efficiency. The design of this invention, which can be adjusted to adapt to bearings of different sizes, can avoid the trouble of specially manufacturing fixtures and help improve enterprise production efficiency.

[0011] As an optimization, in the aforementioned precision bearing assembly fixture for motor rotors, a set of removable shims is provided between the clamping sleeve and the bearing. This allows for the addition or removal of shims to accommodate bearings of different heights, further improving the practicality of the fixture. The shims can be quickly obtained through machining as needed; when the axial dimensions of the bearing and the fixture are incompatible, shims can be added or removed to make them compatible.

[0012] As an optimization, in the aforementioned precision bearing assembly fixture for the motor rotor, the clamping module has an A mounting groove, in which the upper elastic clamping ring is positioned; the bearing mounting module has a B mounting groove, in which the lower elastic clamping ring is positioned. Embedding the elastic clamping ring into the corresponding mounting groove prevents axial displacement of the ring body under force, ensuring it remains in the preset working position and guaranteeing a uniform and stable clamping force output. Furthermore, there are multiple upper and lower elastic clamping rings, arranged equidistantly along the axial direction. This improves the radial constraint force on the clamping module and bearing mounting module, resulting in a more uniform stress distribution on the structure.

[0013] As an optimization, in the aforementioned precision bearing assembly fixture for the motor rotor, both the A connecting groove and the B connecting groove are dovetail groove structures. Correspondingly, the cross-sections of the A connecting column and the B connecting column are both matching isosceles trapezoidal structures. This structure ensures both axial and circumferential limiting functions for the clamping module and the bearing mounting module, while also facilitating the manufacturing and assembly of the fixture.

[0014] As an optimization, in the aforementioned precision bearing assembly fixture for the motor rotor, the limiting component is a nut, which is threadedly connected to the upper end of the central positioning shaft. Using a nut as the limiting component offers the advantage of ease of implementation.

[0015] Regarding the method, the technical solution of this application is as follows:

[0016] A method for assembling precision bearings for motor rotors, which is achieved using the aforementioned precision bearing assembly fixture for motor rotors, includes the following specific steps:

[0017] ① Place the motor rotor on the press's worktable; and install the bearing onto the bearing mounting shaft; in this step, before installing the bearing, adjust the dimensions of the bearing mounting shaft to fit the bearing's inner diameter;

[0018] ② Align the tip of the center positioning shaft with the positioning hole on the motor rotor shaft, and then place the assembly fixture on the end face of the motor rotor shaft to achieve automatic centering;

[0019] ③ Start the press and press down, tighten the mandrel, compress the return spring, and drive the clamping sleeve to move down, pressing the bearing down and installing it on the motor rotor shaft;

[0020] ④ After the bearing is installed in place, the press is lifted and reset. The clamping mandrel moves upward and reset under the action of the reset spring. Then the entire assembly fixture can be removed.

[0021] Compared with the prior art, the assembly method of the precision bearing for motor rotor of this application can realize the standardized assembly of precision bearing for motor rotor, ensure that the coaxiality and dynamic balance accuracy of the assembly meet the process requirements, improve the first-time press-fit qualification rate, significantly reduce the quality risks and production costs of rotor shaft crushing and bearing scrapping, and eliminate the hidden dangers of unqualified products entering the market and causing motor burnout and threatening the safe operation of locomotives. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the assembly tooling for the precision bearing of the motor rotor in Example 1;

[0023] Figure 2 yes Figure 1 A cross-sectional view;

[0024] Figure 3 This is a schematic diagram of the bearing assembly process in Example 1;

[0025] Figure 4 This is a schematic diagram of the motor rotor in Example 1;

[0026] Figure 5 This is a schematic diagram of the bearing structure in Example 1;

[0027] Figure 6 This is a schematic diagram of the assembly tooling for the precision bearing of the motor rotor in Example 2;

[0028] Figure 7 yes Figure 6 A cross-sectional view (with shims);

[0029] Figure 8 This is a schematic diagram of the structure of the compression mandrel and the inner ring of the base in Example 2;

[0030] Figure 9 This is a structural schematic diagram of the clamping module and bearing mounting module in Example 2.

[0031] The markings in the attached diagram are as follows: 1-Clamping mandrel, 11-Top block, 111-Sunk, 112-A connecting groove, 12-Protrusion, 121-Leaning groove, 13-Leaning hole, 14-Upper wedge ring; 2-Center positioning shaft, 21-Center; 3-Limiting component; 4-Clamping sleeve, 41-Step, 42-Shaft hole, 43-Clamping module, 431-A mounting groove, 432-A connecting post, 44-Upper elastic clamping ring; 5-Bearing mounting shaft, 51-Positioning groove, 52-Accommodation groove, 53-Shaft hole, 54-Bearing mounting module, 541-B mounting groove, 542-B connecting post, 55-Inner ring of the base, 551-B connecting groove, 56-Lower elastic clamping ring, 57-Lower wedge ring; 6-Center spring; 7-Reset spring; 8-Washer. Detailed Implementation

[0032] The present application will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present application. In the following embodiments, content not described in detail or shown in detail in the accompanying drawings is common knowledge in the art.

[0033] Example 1 (see Figures 1-5 ):

[0034] A precision bearing assembly fixture for a motor rotor includes a clamping mandrel 1 and a clamping sleeve 4. The clamping mandrel 1 has an inverted U-shaped structure, including a top block 11 and a protrusion 12. The top block 11 has a countersunk groove 111, and the protrusion 12 has a relief groove 121. A relief hole 13 is provided between the countersunk groove 111 and the relief groove 121. The upper part of the clamping sleeve 4 has a step 41. The outer peripheral surface of the top block 11 slides with the inner peripheral surface of the clamping sleeve 4, and the bottom surface of the top block 11 abuts against the stepped surface of the step 41. A bearing mounting shaft 5 is provided in the clamping sleeve 4, and the two slide with each other. The upper end of the bearing mounting shaft 5 has a positioning groove 51, and the lower end has a receiving groove 52. A shaft hole 53 is provided between the positioning groove 51 and the receiving groove 52. The inner peripheral surface of the positioning groove 51 and the outer peripheral surface of the protrusion 12 are... The shaft hole 53 is fitted with a sliding fit; a central positioning shaft 2 is inserted through the shaft hole 53, and the two are slidably fitted; the upper end of the central positioning shaft 2 is located in the recess 111 and is axially limited by the limiting member 3; the lower end of the central positioning shaft 2 is provided with a center point 21, which extends out of the lower end face of the bearing mounting shaft 5; a center point spring 6 is provided in the receiving groove 52, one end of the center point spring 6 abuts against the bottom of the receiving groove 52, and the other end abuts against the center point 21; a return spring 7 is sleeved on the central positioning shaft 2, the upper end of the return spring 7 abuts against the bottom of the relief groove 121, and the lower end abuts against the bottom of the positioning groove 51; the lower part of the bearing mounting shaft 5, which is exposed relative to the clamping sleeve 4, is used to install the bearing, and its outer circumference is cylindrical, and its axis coincides with the axis of the central positioning shaft 2.

[0035] In this embodiment, the inner circumferential surface of the step 41 is interference-fitted with the outer circumferential surface of the top block 11 to form a fixed structure. Thus, the clamping mandrel 1 and the compression sleeve 4 form an integral structure, preventing the clamping sleeve 4 from falling off when the bearing is not installed; furthermore, the interference fit eliminates the need for additional fasteners such as screws, resulting in a simpler and more compact overall structure, and ensuring the alignment of the connecting components.

[0036] In this embodiment, the limiting member 3 is a nut, and the limiting member 3 is threadedly connected to the upper end of the central positioning shaft 2. The use of a nut as the limiting member 3 has the advantage of being easy to implement.

[0037] When the precision bearing assembly fixture for the motor rotor in this embodiment is used in conjunction with the press, the following steps are included:

[0038] ① Place the motor rotor shaft on the press's worktable; install the bearing onto the bearing mounting shaft 5;

[0039] ② Place the assembly fixture containing the bearing on the motor rotor shaft, align the center point 21 of the center positioning shaft 2 with the positioning hole on the motor rotor shaft, and then place the assembly fixture on the end face of the motor rotor shaft to achieve automatic centering.

[0040] ③ Start the press and press down, press the mandrel 1 to compress the return spring 7, and drive the pressing sleeve 4 to move down, pressing the bearing down to install it on the motor rotor shaft;

[0041] ④ After the bearing is installed in place, the press is lifted and reset. Under the action of the reset spring 7, the clamping mandrel 1 moves upward and resets. Then the entire assembly fixture can be removed.

[0042] Example 2 (see Figures 6-9 ):

[0043] Unlike Embodiment 1, in this embodiment, the clamping sleeve 4 includes a set of clamping modules 43 distributed circumferentially and an upper elastic clamping ring 44 that clamps the clamping modules 43; the upper end of the top block 11 is threadedly connected to an upper wedge ring 14; the lower end of the top block 11 is provided with an A connecting groove 112 radially, and the clamping module 43 is correspondingly provided with an A connecting post 432, which slides with the A connecting groove 112 and forms axial and circumferential clamping on the clamping module 43. The clamping module 43 has a partially conical structure at its upper end, which cooperates with the outer peripheral surface of the upper wedge ring 14 to form a wedge mechanism. When the upper wedge ring 14 moves downward, the clamping module 43 moves radially outward along the clamping mandrel 1 under the squeezing action of the upper wedge ring 14, thus expanding. When the upper wedge ring 14 moves upward, the clamping module 43 moves radially inward along the clamping mandrel 1 under the clamping action of the upper elastic clamping ring 44, thus contracting. The bearing mounting shaft 5 includes a base. The system comprises an inner ring 55, a set of bearing mounting modules 54 distributed circumferentially on the outer side of the inner ring 55, and a lower elastic clamping ring 56 that clamps the bearing mounting modules 54. A lower wedge-shaped ring 57 is threadedly connected to the lower part of the inner ring 55. A B-connecting groove 551 is radially provided on the inner ring 55, and a corresponding B-connecting post 542 is provided on the bearing mounting module 54. The B-connecting post 542 slides with the B-connecting groove 551 and provides axial and circumferential limiting for the bearing mounting module 54. The lower end of the bearing mounting module 54 has a partially conical structure that engages with the outer circumferential surface of the lower wedge-shaped ring 57 to form a wedge mechanism. When the lower wedge-shaped ring 57 moves upward, the bearing mounting module 54 expands radially outward along the inner ring 55 under the squeezing action of the lower wedge-shaped ring 57. When the lower wedge-shaped ring 57 moves downward, the bearing mounting module 54 contracts radially inward along the inner ring 55 under the clamping action of the lower elastic clamping ring 56.

[0044] During operation, if it is necessary to increase the size of the bearing mounting shaft 5, the upper wedge ring 14 can be rotated to move it downward, causing the clamping module 43 to expand, and then the lower wedge ring 57 can be rotated to move it upward, causing the bearing mounting module 54 to expand. Conversely, if it is necessary to decrease the size of the bearing mounting shaft 5, the lower wedge ring 57 can be rotated to move it downward, causing the bearing mounting module 54 to contract, and then the upper wedge ring 14 can be rotated to move it upward, causing the clamping module 43 to contract.

[0045] In this embodiment, both the upper wedge ring 14 and the lower wedge ring 57 are provided with an internal hexagonal pattern. When adjusting the size of the bearing mounting shaft 5, an internal hexagonal wrench can be used.

[0046] In this embodiment, a set of removable shims 8 is provided between the clamping sleeve 4 and the bearing. Shims 8 can be added or removed to accommodate bearings of different heights, further improving the practicality of the tooling; and the shims 8 can be quickly obtained through machining as needed.

[0047] In this embodiment, the clamping module 43 is provided with an A mounting groove 431, and the upper elastic clamping ring 44 is disposed in the A mounting groove 431; the bearing mounting module 54 is provided with a B mounting groove 541, and the lower elastic clamping ring 56 is disposed in the B mounting groove 541. Embedding the elastic clamping ring into the corresponding mounting groove can prevent the ring from shifting axially when subjected to force, and always keep it in the preset working position, ensuring a uniform and stable output of clamping force.

[0048] In this embodiment, there are multiple upper elastic clamping rings 44 and lower elastic clamping rings 56, which are arranged at equal intervals along the axial direction. This can improve the radial constraint force on the clamping module 43 and the bearing mounting module 54, and the structure is subjected to more uniform stress.

[0049] In this embodiment, both the A connecting groove 112 and the B connecting groove 551 are dovetail groove structures. Correspondingly, the cross-sections of the A connecting column 432 and the B connecting column 542 are both matching isosceles trapezoidal structures. This ensures both the axial and circumferential limiting functions for the clamping module 43 and the bearing mounting module 54, and also facilitates the manufacturing and assembly of the tooling.

[0050] When the precision bearing assembly fixture for the motor rotor in this embodiment is used in conjunction with the press, the following steps are included:

[0051] ① Adjust the dimensions of the bearing mounting shaft 5 to match the bearing inner diameter (after adjustment, the bearing inner ring can form a transition fit with the corresponding part on the bearing mounting shaft 5); specifically: when it is necessary to increase the dimensions of the bearing mounting shaft 5, first rotate the upper wedge ring 14 downward, and the clamping module 43 moves radially outward along the clamping mandrel 1 under the squeezing action of the upper wedge ring 14; then rotate the lower wedge ring 57 upward, and the bearing mounting module 54 moves radially outward along the inner ring 55 of the base under the squeezing action of the lower wedge ring 57, completing the expansion; when it is necessary to decrease the dimensions of the bearing mounting shaft 5, first rotate the lower wedge ring 57 downward, and the bearing mounting module 54 moves radially inward along the inner ring 55 of the base under the clamping action of the lower elastic clamping ring 56; then rotate the upper wedge ring 14 upward, and the clamping module 43 moves radially inward along the clamping mandrel 1 under the clamping action of the upper elastic clamping ring 44, completing the contraction;

[0052] ② Place the motor rotor shaft on the press workbench; according to the height of the bearing, set the shim 8 so that after the bearing is installed on the assembly fixture, the inner hole of the bearing abuts against the outer circumferential surface of the bearing mounting shaft 5, the upper end face of the bearing abuts against the lower end face of the clamping sleeve 4, and the lower end face of the bearing is flush with the lower end face of the bearing mounting shaft 5.

[0053] ③ Place the assembly fixture containing the bearing on the motor rotor shaft, so that the center point 21 on the center positioning shaft 2 is aligned with the positioning hole on the motor rotor shaft to achieve automatic centering;

[0054] ④ Start the press and press down, press the mandrel 1 to compress the return spring 7, and drive the pressing sleeve 4 to move down, pressing the bearing down to install it on the motor rotor shaft;

[0055] ⑤ After the bearing is installed in place, the press is lifted and reset. Under the action of the reset spring 7, the clamping mandrel 1 moves upward and resets. Then the entire assembly fixture can be removed.

[0056] The foregoing general description of the invention and its specific embodiments should not be construed as a limitation on the technical solution of the invention. Those skilled in the art, based on the disclosure of this application, can add, reduce, or combine the disclosed technical features in the foregoing general description and / or specific embodiments (including examples) without departing from the constituent elements of the invention, to form other technical solutions within the scope of protection of this application.

Claims

1. A precision bearing assembly fixture for an electric motor rotor, characterized in that: It includes a clamping mandrel (1) and a clamping sleeve (4); the clamping mandrel (1) has an inverted U-shaped structure, including a top block (11) and a protrusion (12), the top block (11) is provided with a countersunk groove (111), the protrusion (12) is provided with a relief groove (121), and a relief hole (13) is provided between the countersunk groove (111) and the relief groove (121); the upper part of the clamping sleeve (4) is provided with a step (41), and the outer peripheral surface of the top block (11) is flush with the clamping sleeve. (4) The inner circumferential surface of the top block (11) slides in fit with the stepped surface of the step (41); the clamping sleeve (4) is provided with a bearing mounting shaft (5), and the two slide in fit; the upper end of the bearing mounting shaft (5) is provided with a positioning groove (51), and the lower end is provided with a receiving groove (52), and a shaft hole (53) is provided between the positioning groove (51) and the receiving groove (52); the inner circumferential surface of the positioning groove (51) slides in fit with the outer circumferential surface of the protrusion (12). The shaft hole (53) is fitted with a central positioning shaft (2), and the two are slidably fitted. The upper end of the central positioning shaft (2) is located in the recess (111) and is axially limited by the limiting member (3). The lower end of the central positioning shaft (2) is provided with a center point (21), which extends out of the lower end face of the bearing mounting shaft (5). The receiving groove (52) is provided with a center point spring (6), one end of which abuts against the bottom of the receiving groove (52) and the other end abuts against the center point (21). The central positioning shaft (2) is fitted with a return spring (7), the upper end of which abuts against the bottom of the relief groove (121) and the lower end of which abuts against the bottom of the positioning groove (51). The lower part of the bearing mounting shaft (5) is exposed relative to the clamping sleeve (4) for installing the bearing. Its outer circumference is cylindrical and its axis coincides with the axis of the central positioning shaft (2).

2. The precision bearing assembly fixture for motor rotors according to claim 1, characterized in that: The inner circumferential surface of the step (41) is interference-fitted with the outer circumferential surface of the top block (11) to form a fixed structure.

3. The precision bearing assembly fixture for motor rotors according to claim 2, characterized in that: The clamping sleeve (4) includes a set of clamping modules (43) distributed circumferentially and an upper elastic clamping ring (44) that clamps the clamping modules (43); the upper end of the top block (11) is connected to the upper wedge ring (14) by a thread; the lower end of the top block (11) is provided with an A connecting groove (112) in the radial direction, and the clamping module (43) is provided with an A connecting post (432) corresponding to it. The A connecting post (432) slides with the A connecting groove (112) and forms axial and circumferential clamping on the clamping module (43). The upper end of the clamping module (43) is provided with a partial conical surface structure, which cooperates with the outer peripheral surface of the upper wedge ring (14) to form a wedge mechanism. When the upper wedge ring (14) moves down, the clamping module (43) moves radially outward along the clamping mandrel (1) under the squeezing action of the upper wedge ring (14) to achieve expansion. When the upper wedge ring (14) moves up, the clamping module (43) moves radially inward along the clamping mandrel (1) under the clamping action of the upper elastic clamping ring (44) to achieve contraction. The bearing mounting shaft (5) includes a base inner ring (55), a set of bearing mounting modules (54) distributed circumferentially on the outside of the base inner ring (55), and a lower elastic clamping ring (56) that clamps the bearing mounting modules (54); the lower part of the base inner ring (55) is connected to a lower wedge ring (57) by a thread; the base inner ring (55) is provided with a B connecting groove (551) radially, and the bearing mounting module (54) is provided with a corresponding B connecting post (542), the B connecting post (542) and the B connecting groove (551) are slidably fitted, and the bearing mounting is supported. The module (54) forms axial and circumferential limits; the lower end of the bearing mounting module (54) is provided with a local conical structure, which cooperates with the outer circumferential surface of the lower wedge ring (57) to form a wedge mechanism; when the lower wedge ring (57) moves upward, the bearing mounting module (54) moves radially outward along the inner ring (55) of the base under the squeezing action of the lower wedge ring (57) to achieve expansion; when the lower wedge ring (57) moves downward, the bearing mounting module (54) moves radially inward along the inner ring (55) of the base under the clamping action of the lower elastic clamping ring (56) to achieve contraction.

4. The precision bearing assembly fixture for motor rotors according to claim 3, characterized in that: The lower end of the compression sleeve (4) is provided with a set of removable gaskets (8).

5. The precision bearing assembly fixture for motor rotors according to claim 4, characterized in that: The clamping module (43) is provided with an A mounting groove (431), and the upper elastic clamping ring (44) is located in the A mounting groove (431); the bearing mounting module (54) is provided with a B mounting groove (541), and the lower elastic clamping ring (56) is located in the B mounting groove (541).

6. The precision bearing assembly fixture for motor rotors according to claim 5, characterized in that: The upper elastic clamping ring (44) and the lower elastic clamping ring (56) are multiple and are arranged at equal intervals along the axial direction.

7. The precision bearing assembly fixture for motor rotors according to claim 6, characterized in that: Both the A connecting groove (112) and the B connecting groove (551) are dovetail groove structures. Correspondingly, the cross-sections of the A connecting column (432) and the B connecting column (542) are both matching isosceles trapezoidal structures.

8. The precision bearing assembly fixture for motor rotors according to claim 1, characterized in that: The limiting component (3) is a nut, and the limiting component (3) is threadedly connected to the upper end of the central positioning shaft (2).

9. A method for assembling a precision bearing for a motor rotor, wherein the method is implemented using the precision bearing assembly fixture for a motor rotor as described in any one of claims 1-8, and the specific steps are as follows: ① Place the motor rotor on the press worktable; and install the bearing onto the bearing mounting shaft (5); ② Align the tip (21) of the center positioning shaft (2) with the positioning hole on the motor rotor shaft, and then place the assembly fixture on the end face of the motor rotor shaft to achieve automatic centering; ③ Start the press and press down, press the mandrel (1) to compress the return spring (7), and drive the pressing sleeve (4) to move down, pressing the bearing down to install it on the motor rotor shaft; ④ After the bearing is installed in place, the press is lifted and reset. The mandrel (1) is moved up and reset under the action of the reset spring (7). The entire assembly fixture can then be removed.

10. A method for assembling a precision bearing for a motor rotor, wherein the method is implemented using the precision bearing assembly fixture for a motor rotor as described in claims 3-8, and the specific steps are as follows: ① Place the motor rotor on the press workbench; and install the bearing onto the bearing mounting shaft (5); in this step, before installing the bearing, adjust the size of the bearing mounting shaft (5) to match the bearing inner diameter; ② Align the tip (21) of the center positioning shaft (2) with the positioning hole on the motor rotor shaft, and then place the assembly fixture on the end face of the motor rotor shaft to achieve automatic centering; ③ Start the press and press down, press the mandrel (1) to compress the return spring (7), and drive the pressing sleeve (4) to move down, pressing the bearing down to install it on the motor rotor shaft; ④ After the bearing is installed in place, the press is lifted and reset. The mandrel (1) is moved up and reset under the action of the reset spring (7). The entire assembly fixture can then be removed.

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