A method of assembling a reducer assembly

Abstract

This invention relates to the field of reducer manufacturing technology and discloses a reducer assembly method, which proceeds sequentially according to the following steps: retaining ring installation, press-fit bearing one, cage installation, press-fit bearing two, external snap ring, flat key installation, planetary gear installation, inspection, and packaging. Before assembly, the parts are checked for cleanliness and damage; assembly only begins after confirmation. During the assembly of bearing one, the cage, and bearing two, corresponding specialized tooling is used, namely, the first tooling, the second tooling, and the third tooling. The use of these specialized tooling and the establishment of positioning references effectively ensures the coaxial accuracy between components such as the housing, bearings, and cage during the assembly process, guaranteeing the reducer assembly quality and resulting in excellent low-vibration and low-noise performance.

Description

Technical Field

[0001] This invention relates to the field of speed reducer manufacturing technology, and more specifically to a speed reducer assembly method. Background Technology

[0002] A speed reducer is a mechanical device used to reduce the speed of an input shaft and increase the torque of an output shaft. It is typically used in applications requiring high torque and low speed, such as in industrial machinery, automotive drivetrains, robots, and other heavy equipment. The speed reducer works by using the meshing of gears to convert speed into torque.

[0003] The assembly process of the reducer assembly includes steps such as cleaning and inspecting the components, rust prevention and lubrication, and assembling the assembly housing. During assembly, the fitting precision of the components must be strictly controlled, such as ensuring the concentricity of the reducer shaft and the motor shaft, to reduce vibration and noise.

[0004] Vibration and noise levels are crucial indicators of reducer assembly quality. Existing reducers typically require ensuring coaxiality between multiple components or locations, such as bearings, bearing bores, and the output shaft, to guarantee vibration and noise performance. However, these components need to be assembled sequentially in multiple stages, making it difficult to achieve the high precision required for centering during assembly, thus compromising coaxial centering accuracy. Summary of the Invention

[0005] The technical problem solved by this invention is that existing reducers have difficulty achieving high-precision centering accuracy during the sequential assembly of multiple components such as bearings and cages, which makes it difficult to guarantee coaxial centering accuracy during assembly.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for assembling a speed reducer assembly comprises the following steps:

[0008] Retaining ring installation: Install the two retaining rings into the corresponding positions in the first through hole. When assembling, the smooth surface of the upper retaining ring should face upward and the smooth surface of the lower retaining ring should face downward. After assembly, check whether there is any jamming when the retaining rings rotate.

[0009] Press-fit bearing one: Place the housing on the base with the inner teeth facing upwards. At this time, the first through hole and the first positioning post are in micro-clear clearance fit. Then, place the bearing on the second positioning post. The bearing slides down through the second positioning post to the chamfer position of the connecting end face. Under the guidance of the chamfer, it is in a flat state. At this time, press down the guide sleeve to press the bearing one into the first through hole. After the press-fit is completed, visually check whether the top surface of the bearing is lower than the height of the connecting end face.

[0010] Cage installation: Place the housing with a bearing installed on it on the positioning seat with the inner teeth facing upward. At this time, the first through hole of the housing is in micro-clear clearance fit with the second positioning shaft. Then, place the cage on the fourth positioning shaft with the pin on top. At this time, the cage is fixed on the fourth positioning shaft by the attraction of the magnet set in the fourth positioning shaft. Then, drive the middle plate to move downward, thereby pressing the output shaft of the cage into the bearing hole.

[0011] Press-fit bearing 2: After the cage is assembled, the housing is placed on the fixed seat with the inner teeth facing down. At this time, the inscribed circle formed by the three pins is centered and positioned with the central axis. Then, bearing 2 is sleeved on the protrusion. Under the action of the magnet, bearing 2 is attracted to the protrusion. Then, the power mechanism drives the pressure cylinder to move downward. During this process, the output shaft abuts against the protrusion, causing the slider to move upward relative to the pressure cylinder. After the bearing is separated from the protrusion, the pressure cylinder moves downward, driving bearing 2 downward until bearing 2 is pressed into the first through hole to complete the press-fit operation of bearing 2.

[0012] Installation of external retaining spring and parallel key: Before installing the external retaining spring, install the adjusting shim, then install the external retaining spring so that the external retaining spring presses against the adjusting shim, and then install the parallel key into the parallel keyway. After installation, secure it with a rubber band.

[0013] Planetary gear installation: First, apply a measured amount of lubricating grease to the internal gear position of the second through hole of the housing. Then, install the three planetary gears on the three pins respectively. Then, insert the input washer into the second through hole and flatten the input washer against the end face of the internal gear.

[0014] Inspection and packaging: The assembled products are inspected, and those that pass the inspection are packaged.

[0015] In one aspect of the present invention: before assembly, the retaining ring is inspected to ensure that the parts are clean and undamaged. Assembly is only started after confirming that there are no errors. During the assembly process, care must be taken not to scratch the inner wall of the first through hole.

[0016] In one aspect of the present invention, the clearance dimension of the micro-clear fit is set at 0.01 mm.

[0017] In one aspect of the present invention: the attraction force of the magnet inside the fourth positioning shaft is greater than the weight of the cage, but less than the overall weight of the cage and housing after they are pressed together.

[0018] In one aspect of the present invention: after the bearing is press-fitted, check whether the retaining ring groove in the middle of the planetary gear cage is completely exposed outside the end face of the inner ring of the bearing; at the same time, rotate the planetary gear cage to check whether there is any jamming.

[0019] In one aspect of the present invention: after the planetary gears are installed, the retainer is rotated to ensure that the grease is fully lubricated to the internal gears and planetary gears.

[0020] In one aspect of the present invention, the testing process is as follows: the decibel value during operation is tested in a quiet room, and the product is observed to meet the requirements: <52 decibels, and there is no obvious abnormal noise.

[0021] In one aspect of the present invention: axial limiting of the power mechanism during the pressing process of pressing together bearing one, cage and bearing two.

[0022] The beneficial effects of this invention are as follows: By employing corresponding special tooling during the assembly of bearing one, the cage, and bearing two, the coaxial accuracy between components such as the housing, bearing, and cage during the assembly process is effectively guaranteed, ensuring the assembly quality of the reducer and giving the reducer excellent low vibration and low noise performance.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a schematic diagram of the reducer in this invention;

[0026] Figure 2 This is a schematic diagram of the reducer of the present invention after the retaining ring is assembled;

[0027] Figure 3 This is a schematic diagram of the structure used in the first tooling of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the reducer of the present invention after the bearing is assembled;

[0029] Figure 5 This is a three-dimensional structural schematic diagram of the second tooling of the present invention;

[0030] Figure 6 This is a structural schematic diagram of the cross-section of the second tooling of the present invention;

[0031] Figure 7 This is a schematic diagram of the reducer structure after the cage is assembled.

[0032] Figure 8 This is a schematic diagram of the structure of the third tooling before pressing and fitting in this invention;

[0033] Figure 9 This is a schematic diagram of the structure of the third tooling after pressing and fitting according to the present invention;

[0034] Figure 10 This is a schematic diagram of the structure of the reducer bearing after two press fits in this invention;

[0035] Figure 11 This is a schematic diagram of the structure of the planetary gears of the reducer in this invention after assembly.

[0036] The attached figures are labeled as follows:

[0037] 1. Housing; 2. Retaining ring; 3. Bearing; 4. Cage; 5. Planetary gear; 6. Base; 7. Guide sleeve; 8. First positioning post; 9. Second positioning post; 10. Upper plate; 11. Middle plate; 12. Lower plate; 13. Guide post; 14. Positioning seat; 15. Connecting seat; 16. Fixed seat; 17. Pressure cylinder; 18. Central shaft; 19. Slider; 20. External snap ring; 21. Flat key. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0040] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0041] The applicant currently has a type of speed reducer, such as Figure 1As shown, the assembly includes a housing 1, retaining rings 2, bearings 3, a cage 4, and planetary gears 5. The housing 1 has a first through-hole (Φ32) and a second through-hole with different diameters. The diameter of the second through-hole is larger than that of the first through-hole. The first through-hole is used to install the bearing 3, and the inner wall of the second through-hole has internal teeth to mate with the planetary gears 5. The junction of the first and second through-holes forms an annular connecting end face. The end of the first through-hole near the second through-hole has a chamfer to guide the bearing 3 during placement. Two slots are formed on the inner wall of the first through-hole for installing the retaining rings 2. The retaining rings 2 limit one side of the bearing 3 and position it. The retaining rings 2 should include at least one smooth surface that contacts the bearing 3 during installation to ensure assembly accuracy. Two bearings 3 are respectively installed on the outer sides of the two retaining rings 2 to support the output shaft. The cage 4 includes a connecting disc, one side of which is fixedly connected to the output shaft, and the other side is fixed with three pins. The three pins can enclose an inscribed cylindrical surface, and the inscribed circle is coaxial with the connecting disc and the output shaft. After assembly, it is coaxial with the first through hole, bearing 3, etc. The planetary gears 5 are subsequently installed on the three pins respectively.

[0042] During assembly, the concentricity of the first through hole in housing 1, bearing 3, output shaft, and other components is closely related to the vibration and noise levels of the finished reducer. Since these components need to be assembled sequentially in multiple stages, ensuring concentricity is difficult. Therefore, guaranteeing concentricity and improving assembly quality while maintaining efficiency is a pressing issue. To address this, the applicant proposes a reducer assembly method and its dedicated tooling structure, which effectively ensures assembly accuracy and maximizes assembly efficiency during the reducer assembly process.

[0043] Please see Figure 1-11 This invention relates to a method for assembling a speed reducer assembly, which is carried out in the following steps:

[0044] Please see Figure 2 Installation of retaining rings 2: Insert the two retaining rings 2 into their respective positions within the first through hole. Installation can be performed using internal clamps, paying attention to the orientation of the smooth surfaces of the retaining rings 2. The smooth surface of the upper retaining ring 2 should face upwards, and the smooth surface of the lower retaining ring 2 should face downwards, ensuring proper contact and fit between the smooth surfaces and the bearing 3 to guarantee assembly accuracy. During assembly, care must be taken not to scratch the inner wall of the first through hole to avoid affecting product quality. Before assembly, check that the parts are clean and undamaged. Once confirmed to be in good condition, begin assembly. After assembly, rotate the retaining rings 2 to check for any jamming during rotation.

[0045] Please see Figure 3-4 Press-fit bearing 1: In this process, a first tooling is used for auxiliary assembly. The first tooling includes a base 6 and a guide sleeve 7. The size of the base 6 is larger than the outer diameter of the housing 1. The base 6 can be configured with two sections of different sizes to ensure the stability of the base 6 and to avoid the tooling being too heavy. A first positioning post 8 is fixedly installed on the base 6. The outer diameter of the first positioning post 8 matches the outer diameter of the first through hole. This allows the first positioning post 8 to have a micro-clearance fit with the first through hole, i.e., the clearance is relatively small, thereby ensuring the coaxial positioning accuracy during the press-fit process. The clearance size of the micro-clearance is set at about 0.01 mm. A second positioning post 9 is coaxially fixedly connected to the end of the first positioning post 8 away from the base 6. The outer diameter of the second positioning post 9 matches the diameter of the inner hole of the bearing 3, allowing the second positioning post 9 to have a clearance fit with the inner hole of the bearing 3. The size of the guide sleeve 7 matches the size of the outer ring of the bearing 3. The guide sleeve 7 is used to press the outer ring of the bearing 3. The upper end of the guide sleeve 7 is connected to a power mechanism, which is used to drive the guide sleeve 7 to move up and down to provide press-fit power. The lower end of the guide sleeve 7 has a first cavity, the size of which matches the size of the inner ring of the bearing 3, to avoid obstructing the inner ring of the bearing 3. The guide sleeve 7 also has a second cavity, the inner diameter of which matches the outer diameter of the second positioning post 9, allowing the second cavity to form a micro-clearance fit with the second positioning post 9. The guide sleeve 7 should have a channel for venting. Since the guide sleeve 7 and the positioning post below have a micro-clearance fit, providing a venting channel can reduce downward pressure resistance, ensure downward pressure stability, and avoid affecting the press-fit quality.

[0046] The specific operation process of press-fitting bearing 1 is as follows: The housing 1 is placed on the base 6 with its inner teeth facing upwards. At this time, the first through hole and the first positioning post 8 are in a slight clearance fit, thus making the first through hole of the housing 1 and the first positioning post 8 coaxial and centered. Then, the bearing 3 is placed on the second positioning post 9, with the bearing 1 coaxial and centered with the second positioning post 9. The bearing 3 slides down through the second positioning post 9 to the chamfered position of the connecting end face, where it is flat under the guidance of the chamfer. At this time, the guide sleeve 7 is pressed down, pressing the bearing 1 into the first through hole. During the pressing process, the chamfer acts as a guide, reducing the pressing resistance. After pressing is completed, visually inspect whether the top surface of the bearing 3 is lower than the height of the connecting end face. Otherwise, further inspection is performed, or it is classified as a defective product. The second chamber of the guide sleeve 7 and the second positioning post 9 are fitted with a micro-gap to ensure the stability and accuracy of the pressing process. At the same time, it can ensure that the bearing 3 is in a flattened state. Based on the coaxiality of the first positioning post 8 and the second positioning post 9, the pressing accuracy of the bearing 1 is guaranteed, that is, the coaxiality quality between the bearing 1 and the first through hole of the housing 1 is guaranteed.

[0047] Please see Figure 5-7 Cage 4 Installation: During this process, a second tooling is used for assisted assembly. This second tooling is a dedicated elastic magnetic integrated tooling, comprising an upper plate 10, a middle plate 11, and a lower plate 12 arranged in parallel. Each of the upper plate 10, middle plate 11, and lower plate 12 has a central hole. This central hole can be machined simultaneously by stacking the three plates to ensure concentricity accuracy. The upper plate 10 and lower plate 12 are fixedly connected by multiple guide posts 13. The holes in the upper plate 10, middle plate 11, and lower plate 12 used for connecting the guide posts 13 can also be machined simultaneously by stacking to ensure centering accuracy. The middle plate 11 has multiple through holes, through which it slides with the guide posts 13. A sleeve structure can also be provided at the through holes of the middle plate 11 to ensure connection stability and accuracy with the guide posts 13. A compression spring is fitted on the guide post 13 between the middle plate 11 and the lower plate 12 for the reset action of the middle plate 11. A positioning seat 14 is provided at the center hole of the lower plate 12. The positioning seat 14 can be fixedly connected to the lower plate 12. The positioning seat 14 includes a positioning body, a first positioning shaft that mates with the center hole, and a second positioning shaft that mates with the first through hole of the housing 1. The first positioning shaft and the second positioning shaft are respectively located at both ends of the positioning body, and the size of the positioning body is larger than the size of the first positioning shaft and the second positioning shaft. A connecting seat 15 is fixedly provided at the center hole of the middle plate 11. The connecting seat 15 includes a connecting body, a third positioning shaft, and a fourth positioning shaft. The third positioning shaft is used to mate with the center hole of the middle plate 11 for centering and positioning. The fourth positioning shaft is used to mate with the inscribed circular surface enclosed by the three pins on the retainer 4 to center and position the retainer 4. The positioning seat 14 and the connecting seat 15 can be machined simultaneously by grinding, such as the connecting body and the positioning body, the first positioning shaft and the third positioning shaft being machined together. This can effectively ensure the concentricity accuracy between the positioning seat 14 and the connecting seat 15, thereby ensuring the centering accuracy of the top and bottom structures, and ultimately ensuring the centering accuracy of the cage 4, the housing 1, the bearing 3, etc. during the assembly process. A magnet is fixedly installed inside the fourth positioning shaft. The attractive force of this magnet is greater than the weight of the cage 4, but less than the overall weight of the cage 4 and the housing 1 after they are pressed together.

[0048] The specific operation procedure for installing cage 4 is as follows:

[0049] The housing 1, with a bearing 3 installed, is placed on the positioning seat 14 with its inner teeth facing upwards. At this time, the first through hole of the housing 1 is in micro-clear clearance fit with the second positioning shaft, ensuring that the housing 1 and the entire bottom structure (lower plate 12, positioning seat 14) maintain the same centering accuracy. Then, the retainer 4 is placed on the fourth positioning shaft with the pins facing upwards. The retainer 4 is then fixed to the fourth positioning shaft by the attraction of a magnet. At this time, the three pins are located on the outside of the fourth positioning shaft. Through the three pins and the fourth positioning shaft, the retainer 4 and the entire upper structure (middle plate 11) are kept in the same position. The centering accuracy of the cage 4 (including the connecting seat 15, upper plate 10, etc.) is maintained uniformly. This is achieved by the side of the fourth positioning shaft engaging with the sides of the three pins, and the end face of the fourth positioning shaft engaging with the end face of the connecting plate of the cage 4. This ensures the centering and end runout accuracy of the cage 4 assembly. Then, the middle plate 11 is driven downwards by a press or other equipment, pressing the output shaft of the cage 4 into the bearing 3 hole. During this process, the centering accuracy between the center holes of the upper and lower structures of the guide post 13 is unified, effectively ensuring the centering accuracy of the cage 4, housing 1, bearing 3, etc. After pressing, during the upward reset of the middle plate 11, the magnetic force of the magnet is insufficient to hold the pressed product, causing the cage 4 to detach from the upper structure. The pressed product can then automatically fall off, allowing for more efficient pressing of the next product. After detachment, the product is inspected and transferred to a transfer container for the next processing step. The inspection process involves rotating the cage 4 to check for any jamming.

[0050] Please see Figure 8-10 Press-fit bearing two:

[0051] In this process, a third tooling is used for auxiliary assembly. The third tooling includes a fixed base 16 and a pressure cylinder 17. The fixed base 16 can be provided with a fixing structure or have fixing holes for fixing. A central shaft 18 is fixedly mounted on the fixed base 16. The outer diameter of the central shaft 18 matches the size of the inscribed circle formed by three pins, so as to place the product after the previous pressing step and use the three pins for positioning. The upper end of the pressure cylinder 17 can be connected to a power mechanism, such as a press. The size of the pressure cylinder 17 matches the size of the outer ring of the bearing 3 for pressing the outer ring of the bearing 2. A stepped portion is provided inside the lower end of the pressure cylinder 17. The size of the through hole formed by the stepped portion matches the outer diameter of the output shaft. A slider 19 is slidably mounted inside the pressure cylinder 17. A compression spring is connected to one side of the slider 19 away from the stepped portion, and a protrusion is coaxially fixed to the other side. The outer diameter of the protrusion matches the inner diameter of the bearing 3, and a magnet is provided inside the protrusion. Under normal conditions, the slider 19 is located at the lower end of the pressure cylinder 17 under the action of the compression spring and is limited to the extreme position under the action of the step, so that the protrusion is outside the pressure cylinder 17 for mounting the bearing 3.

[0052] The specific operation process for press-fit bearing 2 is as follows:

[0053] After the cage 4 is assembled, the housing 1 is placed on the fixed seat 16 with the inner teeth facing down. At this time, the inscribed circle formed by the three pins is centered and positioned with the central shaft 18. Then, the bearing 2 is fitted onto the protrusion. Under the action of the magnet, the bearing 2 is attracted to the protrusion, and the bearing 3 and the protrusion (i.e., slider 19 and pressure cylinder 17) are centered and positioned. Then, the pressure cylinder 17 is driven to move downward by the power mechanism (press). During this process, the output shaft abuts against the protrusion, causing the slider 19 to move upward relative to the pressure cylinder 17, so that the bearing 3 is disengaged from the protrusion. The pressure cylinder 17 moves downward, driving the bearing 2 downward until the bearing 2 is pressed into the first through hole, completing the pressing action of the bearing 2. Then, the pressure cylinder 17 returns to its original position, and the protrusion returns to its original position at the same time, so as to continue the next pressing action. After the pressing is completed, check whether the retaining ring groove in the middle of the cage 4 (output shaft) is completely exposed outside the inner ring end face of the bearing 3; at the same time, check whether there is any jamming when rotating the cage 4.

[0054] Please see Figure 1 Installation of the outer retaining circlip 20 and the flat key 21: A retaining circlip groove is provided on the output shaft for fitting an outer retaining circlip 20. The retaining circlip is used to fix the axial freedom of the bearing 3. To prevent the bearing 3 from moving axially, 1-2 adjusting shims are installed before fitting the outer retaining circlip 20. Then, the flat key 21 is installed. The output shaft of the cage 4 is provided with a flat key groove. The flat key 21 is installed into the flat key groove. After installation, it is temporarily fixed by binding with a rubber band.

[0055] Please see Figure 11 Planetary gear installation: First, apply a measured amount of lubricating grease to the internal gear position of the second through hole in housing 1. Then, install the three planetary gears onto the three pins respectively. Next, insert the input washer into the second through hole, ensuring the input washer is flush against the end face of the internal gear. After installation, rotate the retainer 4 to ensure the grease fully lubricates the internal gears and planetary gears 5. The lubricating grease can be applied using a grease applicator for measured application.

[0056] Testing and Packaging: After all products are assembled, their decibel levels are tested in a quiet room. The decibel level must meet the requirement of <52 decibels, with no noticeable abnormal noise. After passing the test, the products are packaged in special liners and cartons for warehousing and shipment.

[0057] Because the retaining ring 2 has limited bearing capacity, excessive pressure will cause it to deform, thus affecting product quality. Therefore, when pressing bearing 1, cage 4, and bearing 2, it is necessary to axially limit the power mechanism (pressing components: guide sleeve 7, middle plate 11, and pressure cylinder 17) during the pressing process. This axial limiting can be achieved by installing a pressure sensor on the press and setting the press pressure, so that the press presses down at the set pressure. At the same time, an upper limit threshold for the press pressure can be set (this pressure threshold is less than the bearing capacity threshold of the retaining ring 2 to avoid damage to the retaining ring 2), or the pressing stroke of the press can be limited. This can be achieved by installing a position sensor or distance sensor and cooperating with a PLC control system to limit the press stroke.

[0058] The three pins on cage 4 facilitate machining accuracy. Therefore, during the press-fitting of cage 4 and bearing 2, the inscribed circle formed by the three tangent points on the inner sides of the three pins is selected as the positioning datum. This effectively ensures the centering accuracy of the press-fitting of cage 4 and bearing 2. During the press-fitting of bearing 1, cage 4, and bearing 2, appropriate specialized tooling is used. By setting the positioning datum and adjusting the positional accuracy of the tooling relative to the pressing component of the power mechanism, the bottom structure of the tooling can be fixed. This allows the product to be placed directly during the press-fitting process, ensuring the centering accuracy of the press-fitting process.

[0059] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the scope of the claims.

Claims

1. A method for assembling a speed reducer assembly, the speed reducer comprising a housing (1), a retainer ring (2), a bearing (3), a cage (4) and a planet wheel (5), the housing (1) having a first through hole and a second through hole with different diameters, the diameter of the second through hole being larger than that of the first through hole, the first through hole being used for mounting the bearing (3), and the inner wall of the second through hole being provided with internal teeth for matching the planet wheel (5), characterized in that, Follow these steps in sequence: Retaining ring (2) installation: Install the two retaining rings (2) into the corresponding positions in the first through hole respectively. When assembling, the smooth surface of the upper retaining ring (2) faces upward and the smooth surface of the lower retaining ring (2) faces downward. After assembly, check whether there is any jamming when the retaining rings (2) rotate. Press-fit bearing 1: A first tooling is used for auxiliary assembly. The first tooling includes a base (6) and a guide sleeve (7). The size of the base (6) is larger than the outer diameter of the housing (1). A first positioning post (8) is fixedly installed on the base (6). The outer diameter of the first positioning post (8) matches the outer diameter of the first through hole. A second positioning post (9) is coaxially fixedly connected to the end of the first positioning post (8) away from the base (6). The outer diameter of the second positioning post (9) matches the inner diameter of the bearing (3). The size of the guide sleeve (7) matches the inner diameter of the bearing (3). The outer ring of the bearing (3) is matched with the size of the outer ring. The guide sleeve (7) is used to press the outer ring of the bearing (3). The housing (1) is placed on the base (6) with the inner teeth facing upward. At this time, the first through hole and the first positioning post (8) are in micro-clear fit. Then the bearing is set on the second positioning post (9). The bearing (3) slides down to the chamfer position of the connecting end face through the second positioning post (9). Under the guidance of the chamfer, it is in a flat state. At this time, the guide sleeve (7) is pressed down to press the bearing into the first through hole. After the pressing is completed, visually check whether the top surface of the bearing is lower than the position height of the connecting end face. Cage (4) Installation: The second tooling is used for auxiliary assembly. The second tooling is an elastic magnetic integrated tooling, which includes an upper plate (10), a middle plate (11) and a lower plate (12) arranged in parallel. The upper plate (10), the middle plate (11) and the lower plate (12) are all provided with a central hole. The upper plate (10) and the lower plate (12) are fixedly connected by multiple guide posts (13). A positioning seat (14) is provided at the central hole of the lower plate (12). The positioning seat (14) includes a positioning body, a first positioning shaft that mates with the central hole and a second positioning shaft that mates with the first through hole of the housing (1). A connecting seat (15) is fixedly provided at the central hole of the middle plate (11). The connecting seat (15) includes a connecting body, a third positioning shaft and a fourth positioning shaft. The third positioning shaft is used to cooperate with the center hole of the middle plate (11) for centering and positioning. The fourth positioning shaft is used to cooperate with the inner tangent circular surface enclosed by the three pins on the retainer (4) to center and position the retainer (4). A magnet is fixedly installed inside the fourth positioning shaft. The housing (1) with a bearing (3) is placed on the positioning seat (14) with the inner teeth facing upward. At this time, the first through hole of the housing (1) is in micro-clear clearance cooperation with the second positioning shaft. Then the retainer (4) is placed at the fourth positioning shaft with the pin on top. At this time, the retainer (4) is fixed on the fourth positioning shaft under the attraction of the magnet installed inside the fourth positioning shaft. Then the middle plate (11) is driven to move downward, thereby pressing the output shaft of the retainer (4) into the bearing (3) hole. Press-fit bearing 2: Assisted assembly is performed using a third tooling, which includes a fixed base (16) and a pressure cylinder (17). A central shaft (18) is fixedly mounted on the fixed base (16). The outer diameter of the central shaft (18) matches the size of the inscribed circle formed by the three pins. A stepped portion is provided inside the lower end of the pressure cylinder (17). The size of the through hole formed by the stepped portion matches the outer diameter of the output shaft. A slider (19) is slidably mounted inside the pressure cylinder (17). A compression spring is connected to one side of the slider (19) away from the stepped portion, and a protrusion is coaxially fixed to the other side. The outer diameter of the protrusion matches the inner diameter of the bearing (3). The hole size is matched, and a magnet is provided inside the protrusion; after the housing (1) after the cage (4) is assembled, it is placed on the fixed seat (16) with the inner teeth facing down. At this time, the inner circle formed by the three pins is centered and positioned with the central shaft (18). Then the bearing 2 is sleeved on the protrusion. Under the action of the magnet, the bearing 2 is attracted to the protrusion. Then the pressure cylinder (17) is driven to move downward through the power mechanism. During this process, the output shaft abuts against the protrusion, so that the slider (19) moves upward relative to the pressure cylinder (17). After the bearing (3) is separated from the protrusion, the pressure cylinder (17) moves downward to drive the bearing 2 to move downward until the bearing 2 is pressed into the first through hole to complete the pressing action of the bearing 2. Installation of outer snap ring (20) and flat key (21): Before installing the outer snap ring (20), install the adjusting shim, then install the outer snap ring (20) so that the outer snap ring (20) presses the adjusting shim, then install the flat key (21) into the groove of the flat key (21), and after installation, fix it by binding with a rubber ring; Planetary gear installation: First, apply a measured amount of lubricating grease to the inner tooth position of the second through hole of the housing (1), then install the three planetary gears on the three pins respectively, and then insert the input washer into the second through hole, with the input washer flat against the end face of the inner tooth. Inspection and packaging: The assembled products are inspected, and those that pass the inspection are packaged.

2. The method of claim 1, wherein, Before assembly, check whether the part is clean and undamaged. After confirming that there are no errors, start the assembly process. During the assembly process, be careful not to scratch the inner wall of the first through hole.

3. The method of claim 1, wherein, The clearance dimension for micro-clear fit is set at 0.01 mm.

4. The method of claim 1, wherein, The attraction force of the magnet inside the fourth positioning shaft is greater than the weight of the cage (4) and less than the overall weight of the cage (4) and the housing (1) after they are pressed together.

5. The method of claim 1, wherein, After the bearing is press-fitted, check whether the retaining ring groove in the middle of the cage (4) is completely exposed outside the inner ring end face of the bearing (3); at the same time, rotate the cage (4) to check for any jamming.

6. The method of claim 1, wherein, After the planetary gears are installed, rotate the cage (4) to fully lubricate the grease with the internal gears and planetary gears (5).

7. The method of claim 1, wherein The testing process is as follows: the decibel value during operation is tested in a quiet room, and the product is observed to see if it meets the requirements: <52 decibels, and there is no obvious abnormal noise.

8. The method of claim 1, wherein, Axial limiting during the pressing process of the power mechanism when pressing bearing 1, cage (4) and bearing 2.

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