Axial motion harmonic reducer based on engagement of screw pair

Abstract

The application provides an axial motion harmonic reducer based on thread pair engagement, and relates to the technical fields of harmonic transmission and precise linear driving, and comprises a cam, a power input end is connected to the cam, a flexible bearing is arranged on the outer part of the cam, a thread flexspline is mounted on the outer part of the flexible bearing, the outer thread of the thread flexspline is engaged with the inner thread of a thread rigid wheel, the rotary motion of the cam is converted into the relative axial displacement between the thread rigid wheel and the thread flexspline through the engagement of the thread pair between the outer thread of the thread flexspline and the inner thread of the thread rigid wheel, the reduction and linear transmission functions are integrated in a single compact unit, the transmission chain is significantly shortened, the axial size and the overall volume are reduced, the gap and the elastic deformation accumulation caused by the series mechanism are reduced, higher positioning accuracy and axial stiffness can be obtained, the continuous engagement of the thread pair is also beneficial to the smooth motion, the thread engagement process is continuous helical surface sliding, compared with discrete tooth engagement, vibration and noise can be reduced.

Description

Technical Field

[0001] This invention relates to the field of harmonic drive and precision linear drive technology, specifically to an axial motion harmonic reducer based on threaded pair meshing. Background Technology

[0002] Harmonic reducers are precision devices that transmit motion and power through the elastic deformation waves of a flexible wheel. They have advantages such as large transmission ratio, small size, high precision, and strong load-bearing capacity, and are widely used in fields such as robot joints and aerospace. Traditional harmonic reducers consist of a wave generator, a flexible wheel, and a rigid wheel. They rely on the difference in the number of teeth between the flexible wheel and the rigid wheel (usually 2) to reduce and transmit circumferential rotational motion. However, when converting rotational motion into high-precision, high-thrust linear motion, it is usually necessary to use the harmonic reducer in series with linear transmission components such as ball screws. This combination scheme has problems such as long axial dimension of the system, complex structure, large cumulative error, high cost, and efficiency loss. Summary of the Invention

[0003] This invention provides an axial motion harmonic reducer based on threaded pair meshing, which solves the technical problems mentioned above, where when converting rotary motion into high-precision, high-thrust linear motion, it is usually necessary to use a harmonic reducer in series with linear transmission components such as ball screws. This combination scheme has the problems of long axial dimension of the system, complex structure, large cumulative error, high cost and efficiency loss.

[0004] To solve the above-mentioned technical problems, the present invention discloses an axial motion harmonic reducer based on threaded pair meshing, including a cam, the cam being connected to a power input end, a flexible bearing being movably sleeved on the outside of the cam, a threaded flexible wheel being mounted on the outside of the flexible bearing, and the external thread of the threaded flexible wheel meshing with the internal thread of the threaded rigid wheel.

[0005] Preferably, when the threaded rigid wheel is fixedly mounted on the housing, the threaded flexible wheel is connected to a power output end, and when the threaded flexible wheel is fixedly mounted on the housing, the threaded rigid wheel is connected to a power output end.

[0006] Preferably, the external thread of the threaded flexible wheel and the internal thread of the threaded rigid wheel have the same thread shape, the same thread direction, and the same thread pitch.

[0007] Preferably, the outer periphery of the cam has an elliptical profile, and the specific shape of the elliptical profile is such that the radial section of the cam is a theoretical ellipse, a cosine ellipse or other elliptical curve, and the axial section is a rectangle.

[0008] Preferably, the cam is provided with several through holes evenly distributed around its circumference, a bushing is fixedly provided in the middle of the cam, mounting holes are provided through the front and rear ends of the bushing, a keyway is provided on the side end of the mounting hole, the mounting hole is transitionally fitted with the power input end, the keyway is interference fitted with the connecting key, the connecting key is interference fitted with the mating groove of the power input end, and several guide positioning grooves are evenly distributed around the side end of the bushing.

[0009] Preferably, the flexible bearing includes a flexible inner ring and a flexible outer ring. The flexible inner ring has a mounting hole inside, which corresponds to and engages with a cam. The flexible inner ring has a groove and a cage symmetrically arranged in the front-rear direction on its outer side. The cage is fitted onto the outside of the flexible inner ring. Several open slots are provided at the ends of the cages on the front and rear sides that are close to each other. The several open slots are evenly distributed circumferentially on the cage. Balls are movably arranged in the open slots. The balls are movably arranged in the groove. The flexible outer ring is fitted onto the outside of the cage. The inner ring of the flexible outer ring has a groove symmetrically arranged in the front-rear direction. Balls are movably arranged in the groove.

[0010] Preferably, the flexible inner ring has symmetrical positioning openings on the upper and lower sides at both ends.

[0011] Preferably, the flexible inner ring is provided with symmetrical limiting rings on the front and rear sides, and the limiting rings are provided with symmetrical positioning extrusion blocks on the upper and lower sides, and the positioning extrusion blocks are matched with the positioning openings.

[0012] Preferably, it also includes a support and positioning mechanism, which includes several connecting rods that are correspondingly arranged in several through holes. A rotating shaft is provided on the front side of the connecting rod, and rotating plates are symmetrically arranged on the left and right sides of the rotating shaft. A connecting hole is provided at the end of the rotating plate away from the rotating shaft. The connecting hole is matched with the positioning rod. The middle part of the positioning rod is matched with the positioning hole in the middle of the extrusion positioning block. The threaded section of the positioning rod away from the head is threadedly connected to the bolt. The diameter of the head of the positioning rod is larger than that of the rod part. A guide block is fixedly provided at the end of the extrusion positioning block near the bushing. The guide block is slidably connected to the guide positioning groove. The extrusion positioning block is in contact with the bushing and is in contact with the power input end.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. Highly integrated structure: The reduction and linear transmission functions are integrated into a single compact unit, which significantly shortens the transmission chain and reduces the axial dimension and overall volume; 2. Smoother and more continuous transmission: Threaded meshing is line contact or surface contact, and the meshing process is a continuous helical surface sliding. Compared with discrete tooth meshing, it can reduce vibration and noise. In the meshing area, the helical surface of the threaded flexible wheel and the helical surface of the threaded rigid wheel form a continuous line contact or small area contact. The transmission process is uninterrupted. Theoretically, it can completely eliminate the impact and backlash generated by traditional tooth meshing when meshing in and out, and achieve extremely smooth motion transmission. 3. Achieve ultra-high reduction ratio: Utilizing the kinematic principle of harmonic drive, a reduction ratio much greater than that of traditional ball screws or planetary roller screws can be achieved in a single-stage transmission, thereby obtaining extremely high thrust output; 4. High precision and high rigidity: It reduces the backlash and elastic deformation accumulation caused by the serial mechanism, which theoretically can achieve higher positioning accuracy and axial rigidity. The continuous meshing of the threaded pair is also conducive to smooth movement. 5. Flexible design: By selecting different pitches and number of thread starts, the required reduction ratio, linear motion stroke and output speed can be flexibly designed. For certain types of threads (such as rectangular and trapezoidal threads), the processing and precision testing methods are more mature and convenient than those for complex harmonic gear tooth profiles. The precision processing and testing technologies (such as grinding, cyclone milling and laser interferometry) are relatively mature, which may reduce the manufacturing threshold and cost of high-precision transmission pairs. 6. Potential cost and performance advantages: The simplified system structure may reduce the overall cost. For certain types of threads, the machining may be simpler than that of complex harmonic gear tooth profiles. Continuous helical surface contact can distribute the load more evenly along the contact line, avoiding the severe stress concentration phenomenon at the root of the traditional tooth, which helps to improve the fatigue life of the threaded flexible gear and the load-bearing capacity of the entire mechanism. Attached Figure Description

[0014] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the structure of the present invention. Figure 2 ; Figure 3 This is a schematic diagram of the cam structure of the present invention; Figure 4 This is a schematic diagram of the flexible bearing structure of the present invention; Figure 5 This is a schematic diagram of the flexible inner ring connection structure of the present invention; Figure 6 This is a schematic diagram of the connection structure between the threaded rigid wheel and the threaded flexible wheel of the present invention; Figure 7 This is a schematic diagram of the threaded flexible gear structure of the present invention; Figure 8 This is a schematic diagram of the threaded steel wheel structure of the present invention; Figure 9 This is a schematic diagram of the support and positioning mechanism structure of the present invention; Figure 10 for Figure 9 A magnified structural diagram of region A in the diagram.

[0015] In the diagram: 1. Threaded rigid wheel; 2. Threaded flexible wheel; 3. Cam; 4. Bushing; 5. Flexible inner ring; 6. Flexible outer ring; 7. Mounting hole; 8. Cage; 9. Through hole; 10. Ball bearing; 11. Groove 1; 12. Opening groove; 13. Positioning port; 14. Limiting ring; 15. Positioning extrusion block; 16. Bolt; 17. Connecting rod; 18. Rotating plate; 19. Extrusion positioning block; 20. Guide positioning groove; 21. Positioning rod; 22. Rotating shaft; 23. Keyway; 24. Positioning hole. Detailed Implementation

[0016] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0017] Furthermore, in this invention, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions and features of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0018] The present invention provides the following embodiments. Example 1: This embodiment of the invention provides an axial motion harmonic reducer based on threaded pair meshing, such as... Figures 1-2 As shown, it includes a cam 3, which is connected to a power input end. A flexible bearing is movably sleeved on the outside of the cam 3, and a threaded flexible wheel 2 is installed on the outside of the flexible bearing. The external thread of the threaded flexible wheel 2 meshes with the internal thread of the threaded rigid wheel 1.

[0019] The working principle of the above technical solution is as follows: Cam 3 is placed inside the flexible bearing. The long axis of cam 3 expands the flexible bearing, causing the open end of the flexible bearing to deform from a circle to an ellipse. Cam 3 forces the threaded flexible wheel 2 to undergo periodic elastic deformation through the flexible bearing. In the region along the long axis of cam 3, the external thread of the threaded flexible wheel 2 is pressed into the internal thread of the threaded rigid wheel 1. In the region along the short axis of cam 3, the external thread of the threaded flexible wheel 2 disengages from the internal thread of the threaded rigid wheel 1. As cam 3 rotates, the engagement area between the external thread of the threaded flexible wheel 2 and the internal thread of the threaded rigid wheel 1 moves accordingly, causing a relative axial displacement between the threaded flexible wheel 2 and the threaded rigid wheel 1. Specifically, the rotational motion of cam 3 is transmitted through the interaction between the external thread of the threaded flexible wheel 2 and the internal thread of the threaded rigid wheel 1. The meshing action of the threaded pair is converted into relative axial displacement between the threaded rigid wheel 1 and the threaded flexible wheel 2. With each rotation of the cam 3, any point on the threaded flexible wheel 2 will move forward or backward a certain distance axially relative to the threaded rigid wheel 1. Ultimately, the threaded flexible wheel 2 (or the threaded rigid wheel 1, depending on the fixed and output components) will generate linear motion along the axis of the threaded rigid wheel 1, realizing the conversion of rotary motion into linear motion. This solves the technical problems that usually require the use of harmonic reducers and linear transmission components such as ball screws in series when converting rotary motion into high-precision, high-thrust linear motion. Such a combination scheme has the problems of long axial dimension of the system, complex structure, large cumulative error, high cost and efficiency loss.

[0020] Example 2: Based on Example 1, such as Figures 1-8 As shown, when the threaded rigid wheel 1 is fixedly mounted on the outer shell, the threaded flexible wheel 2 is connected to a power output end; when the threaded flexible wheel 2 is fixedly mounted on the outer shell, the threaded rigid wheel 1 is connected to a power output end. The external thread of the threaded flexible wheel 2 has the same thread shape, the same thread direction, and the same thread pitch as the internal thread of the threaded rigid wheel 1. The outer periphery of cam 3 is an elliptical profile. The specific shape of the elliptical profile is that the radial section of cam 3 is a theoretical ellipse, a cosine ellipse or other elliptical curve, and the axial section is a rectangle. Cam 3 is provided with several through holes 9 evenly distributed around its circumference. A bushing 4 is fixedly provided in the middle of cam 2. Mounting holes 7 are provided through both the front and rear ends of bushing 4. A keyway 23 is provided on the side end of mounting hole 7. Mounting hole 7 is transitionally fitted with power input end. Keyway 23 is interference fitted with connecting key. Connecting key is interference fitted with mating groove of power input end. Several guide positioning grooves 20 are evenly distributed around the side end of bushing 4.

[0021] The working principle of the above technical solution is as follows: The interference fit between the connecting key and the power input end's mating groove and keyway 23 enables the installation of the power input end and cam 3. When the threaded rigid wheel 1 is fixedly mounted on the housing, the threaded flexible wheel 2 is connected to the power output end. At this time, the threaded rigid wheel 1 acts as a fixed component, and the threaded flexible wheel 2 acts as an output component. The threaded flexible wheel 2 moves linearly along the axis of the threaded rigid wheel 1 (threaded flexible wheel 2). The cam 3 has an elliptical profile. By increasing the contact area between the cam 3 and the flexible bearing, the contact friction between the cam 3 and the flexible bearing is increased, thereby improving the connection stability between the cam 3 and the flexible bearing. This prevents the threaded flexible wheel 2 from driving the flexible bearing to move synchronously during linear movement, thus preventing the cam 3 from separating from the flexible bearing. When the threaded flexible wheel 2 is fixedly mounted on the outer shell, the threaded rigid wheel 1 is connected to the power output end. At this time, the threaded flexible wheel 2 is a fixed component, and the threaded rigid wheel 1 is an output component. The threaded rigid wheel 1 moves linearly along the axis of the threaded rigid wheel 1 (threaded flexible wheel 2). At this time, the cam 3 can be an elliptical profile, so that the cam 3, the flexible bearing and the threaded flexible wheel 2 are connected as one unit, and the threaded rigid wheel 1 can move linearly relative to the threaded flexible wheel 2.

[0022] Example 3: Based on Example 1, such as Figures 4-5 As shown, the flexible bearing includes a flexible inner ring 5 and a flexible outer ring 6. The flexible inner ring 5 has a mounting hole inside, which corresponds to and cooperates with the cam 3. The flexible inner ring 5 has a groove 11 and a cage 8 symmetrically arranged in the front-rear direction on the outside. The cage 8 is sleeved on the outside of the flexible inner ring 5. The cage 8 on the front and rear sides has a number of open slots 12 at the end that are close to each other. The number of open slots 12 are evenly distributed on the cage 8 in the circumferential direction. The ball 10 is movably arranged in the open slot 12. The ball 10 is movably arranged in the groove 11. The flexible outer ring 6 is sleeved on the outside of the cage 8. The inner ring of the flexible outer ring 6 has a groove 2 symmetrically arranged in the front-rear direction. The ball 10 is movably arranged in the groove 2. The flexible inner ring 5 has symmetrical positioning openings 13 on both the front and rear ends and the upper and lower sides; The flexible inner ring 5 is provided with symmetrical limiting rings 14 on the front and rear sides, and the upper and lower sides of the limiting ring 14 are provided with symmetrical positioning extrusion blocks 15, which are matched with the positioning opening 13.

[0023] The working principle of the above technical solution is as follows: By changing the contact friction between cam 3 and flexible inner ring 5, the contact friction between cam 3 and flexible bearing can be changed. After cam 3 and flexible inner ring 5 are engaged, the long axis of cam 3 opens flexible inner ring 5, making flexible inner ring 5 present an elliptical profile. Flexible inner ring 5 opens cage 8 and flexible outer ring 6 through ball 10. Flexible outer ring 6 squeezes flexible wheel 4 into an elliptical profile, thereby realizing the transmission of elliptical profile of cam 3 to threaded flexible wheel 4. When cam 3 rotates, it drives flexible inner ring 5 to rotate synchronously. Flexible inner ring 5 drives threaded flexible wheel 4 to deform synchronously through ball 10 and flexible outer ring 6, so that the external thread of threaded flexible wheel 4 and the internal thread of threaded rigid wheel 1 alternately mesh / disengage, realizing torque transmission and high reduction ratio transmission. Positioning ports 13 are provided at both ends of the flexible inner ring 5. After the cam 3 engages with the flexible inner ring 5, the flexible inner ring 5 can deform into an elliptical shape. At this time, the long axis of the cam 3 is oriented towards the positioning port 13, opening the positioning port 13. Then, the positioning pressing block 15 is moved towards the flexible inner ring 5, so that the positioning pressing block 15 engages with the positioning port 13, keeping the flexible inner ring 5 stationary. The cam 3 is rotated 90° so that the short axis of the cam 3 is oriented towards the positioning port 13. At this time, due to the long axis of the cam 3 pushing the other parts of the flexible inner ring 5 to deform, the positioning port 13 is pulled to contract. The positioning port 13 can press and fix the positioning pressing block 15, so that after the cam 3 engages with the flexible inner ring 5, the flexible inner ring 5 is connected to the limiting ring 14. The setting of the limiting ring 14 can prevent the cam 3 and the flexible inner ring 5 from moving relative to each other along the axis of the threaded rigid wheel 1 (threaded flexible wheel 2), so that the cam 3 and the flexible inner ring 5 can be separated, ensuring that the cam 3 and the flexible inner ring are connected. The connection stability of 5, the setting of groove 1 36 and groove 2, ensures that the flexible inner ring 5, ball 10 and flexible outer ring 6 remain stationary in the axial direction of the threaded rigid wheel 1 (threaded flexible wheel 2), preventing the flexible bearing and cam 3 from disengaging when the threaded flexible wheel 2 or threaded rigid wheel 1 moves, which would affect the operation of the harmonic reducer of this application. When the cam 3 is removed from the flexible inner ring 5, the flexible inner ring 5 is kept stationary, and the cam 3 is rotated 90° so that the long axis of the cam 3 faces the positioning port 13 and opens the positioning port 13. The positioning pressing block 15 on the limiting ring 14 is no longer pressed by the positioning port 13. At this time, the limiting ring 14 can be moved away from the flexible inner ring 5 to complete the disassembly of the limiting ring 14. There is no need to set fasteners between the limiting ring 14 and the flexible inner ring 5. The limiting ring 14 is self-locked by the compression deformation of the flexible inner ring 5 by the cam 3, which facilitates the installation and disassembly of the limiting ring 14, and thus facilitates the maintenance and replacement of the flexible bearing.

[0024] Example 4: Based on Example 2, such as Figures 1-10As shown, it also includes a support and positioning mechanism, which includes several connecting rods 17 arranged one-to-one in several through holes 9. A rotating shaft 22 is provided on the front side of the connecting rod 17. Rotating plates 18 are symmetrically arranged on the left and right sides of the rotating shaft 22. A connecting hole is provided at the end of the rotating plate 18 away from the rotating shaft 22. The connecting hole is correspondingly engaged with the positioning rod 21. The middle part of the positioning rod 21 is correspondingly engaged with the positioning hole 24 in the middle of the extrusion positioning block 19. The threaded section of the positioning rod 21 away from the head is threadedly connected with the bolt 16. The diameter of the head of the positioning rod 21 is larger than that of the rod part of the positioning rod 21. A guide shaped block is fixedly provided at the end of the extrusion positioning block 19 near the bushing 4. The guide shaped block is slidably connected with the guide positioning groove 20. The extrusion positioning block 19 fits against the bushing 4 and is in corresponding contact with the power input end.

[0025] The working principle of the above technical solution is as follows: When installing the extrusion positioning block 19, insert the integrally connected guide shaped block into the guide positioning groove 20. At this time, the extrusion positioning block 19 is in contact with the bushing 4, and the extrusion positioning block 19 can move radially along the bushing 4. After the extrusion positioning block 19 contacts the power input end, control the rotating plate 18 to rotate, so that the connecting hole of the rotating plate 18 is connected to the positioning hole 24 in the middle of the extrusion positioning block 19. Then, insert the positioning rod 21 into the connecting hole and the positioning hole 24. Finally, the connection between the extrusion positioning block 19 and the rotating plate 18 is completed by the cooperation of the bolt 16 and the positioning rod 21. At this time, the extrusion positioning block 19 cannot move radially along the bushing 4. The extrusion positioning block 19 can support and position the power input end. The extrusion positioning block 19 can support the power input end, which is equivalent to applying prestress to the power input end, ensuring that the power input end and the cam 3 rotate synchronously as a whole, avoiding the power input end from deflecting, increasing the extrusion stress between the power input end and the cam 3, causing wear or even deformation between the power input end and the cam 3. When disassembling the extrusion positioning block 19, separate the bolt 16 from the positioning rod 21, and then pull the extrusion positioning block 19 upward to separate the guide irregular block from the guide positioning groove 20, thus completing the disassembly of the extrusion positioning block 19 and the cam 3. The diameter of connecting rod 17 is slightly smaller than the diameter of through hole 9, while the diameter of rotating shaft 22 is larger than the diameter of through hole 9. Because the guide shaped block integrally connected to the extrusion positioning block 19 is inserted into the guide positioning groove 20, the extrusion positioning block 19 can only move up and down. Simultaneously, the extrusion positioning block 19 is limited by the input end, preventing it from moving downwards. When the extrusion positioning block 19 moves upwards, it pushes the rotating plate 18 to rotate. The rotating plate 18 then pushes the connecting rod 17 to slide along through hole 9. After the rotating shaft 22 contacts the bushing 4, the connecting rod 17 cannot move. Therefore, when installing the connecting rod 17, the connecting rod 17 will be... Rod 17 is inserted into through hole 9 and rotating shaft 22 contacts bushing 4. At this time, connecting rod 17 cannot move backward. Then, rotating plate 18 is controlled to rotate until the connecting hole of rotating plate 18 is connected to the positioning hole 24 in the middle of extrusion positioning block 19. At this time, extrusion positioning block 19 applies target prestress to the power input end. After bolt 16 is engaged with positioning rod 21, extrusion positioning block 19 and connecting rod 17 are installed with cam 3. The three can move synchronously. When disassembling connecting rod 17 and extrusion positioning block 19, only bolt 16 needs to be loosened. The operation is simple and convenient.

[0026] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An axial motion harmonic reducer based on threaded pair meshing, characterized in that: Includes a cam (3), which is connected to a power input end. A flexible bearing is movably sleeved on the outside of the cam (3), and a threaded flexible wheel (2) is installed on the outside of the flexible bearing. The external thread of the threaded flexible wheel (2) meshes with the internal thread of the threaded rigid wheel (1).

2. The axial motion harmonic reducer based on threaded pair meshing according to claim 1, characterized in that: When the threaded rigid wheel (1) is fixedly mounted on the outer shell, the threaded flexible wheel (2) is connected to the power output end.

3. The axial motion harmonic reducer based on threaded pair meshing according to claim 1, characterized in that: The external thread of the threaded flexible wheel (2) and the internal thread of the threaded rigid wheel (1) have the same thread shape, the same thread direction, and the same thread pitch.

4. The axial motion harmonic reducer based on threaded pair meshing according to claim 1, characterized in that: The outer periphery of the cam (3) is an elliptical profile. The specific shape of the elliptical profile is that the radial section of the cam (3) is a theoretical ellipse, a cosine ellipse or other elliptical curve, and the axial section is a rectangle.

5. An axial motion harmonic reducer based on threaded pair meshing according to claim 1, characterized in that: The cam (3) is provided with several through holes (9) evenly distributed around its circumference. The cam (2) is fixedly provided with a bushing (4) at its middle part. The bushing (4) is provided with mounting holes (7) at both ends. The side end of the mounting hole (7) is provided with a keyway (23). The mounting hole (7) is transitionally fitted with the power input end. The keyway (23) is interference-fitted with the connecting key. The connecting key is interference-fitted with the mating groove of the power input end. The side end of the bushing (4) is provided with several guide positioning grooves (20) evenly distributed around its circumference.

6. An axial motion harmonic reducer based on threaded pair meshing according to claim 1, characterized in that: The flexible bearing includes a flexible inner ring (5) and a flexible outer ring (6). The flexible inner ring (5) has a mounting hole inside, which corresponds to and cooperates with the cam (3). The flexible inner ring (5) has a groove (11) and a cage (8) symmetrically arranged in the front-back direction on the outside. The cage (8) is fitted on the outside of the flexible inner ring (5). The cage (8) on the front and back sides has several open slots (12) at the end that are close to each other. The several open slots (12) are evenly arranged on the cage (8) in the circumferential direction. The ball (10) is movably arranged in the open slot (12). The ball (10) is movably arranged in the groove (11). The flexible outer ring (6) is fitted on the outside of the cage (8). The inner ring of the flexible outer ring (6) has a groove (2) symmetrically arranged in the front-back direction. The ball (10) is movably arranged in the groove (2).

7. An axial motion harmonic reducer based on threaded pair meshing according to claim 6, characterized in that: The flexible inner ring (5) has symmetrical positioning openings (13) on the upper and lower sides at both ends.

8. An axial motion harmonic reducer based on threaded pair meshing according to claim 7, characterized in that: The flexible inner ring (5) is symmetrically provided with limiting rings (14) on the front and back sides, and the upper and lower sides of the limiting ring (14) are symmetrically provided with positioning extrusion blocks (15), which are correspondingly matched with the positioning port (13).

9. An axial motion harmonic reducer based on threaded pair meshing according to claim 5, characterized in that: It also includes a support positioning mechanism, which includes several connecting rods (17) that are arranged one-to-one in several through holes (9). A rotating shaft (22) is provided on the front side of the connecting rod (17). Rotating plates (18) are symmetrically arranged on the left and right sides of the rotating shaft (22). A connecting hole is provided at the end of the rotating plate (18) away from the rotating shaft (22). The connecting hole is correspondingly matched with the positioning rod (21). The middle part of the positioning rod (21) is correspondingly matched with the positioning hole (24) in the middle of the extrusion positioning block (19). The threaded section of the positioning rod (21) away from the head is threadedly connected to the bolt (16). The head diameter of the positioning rod (21) is larger than the rod part of the positioning rod (21). A guide shaped block is fixedly provided at the end of the extrusion positioning block (19) near the bushing (4). The guide shaped block is slidably connected to the guide positioning groove (20). The extrusion positioning block (19) fits against the bushing (4) and is in contact with the power input end.

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