Spherical tooth harmonic transmission mechanism

Abstract

The invention discloses a spherical tooth harmonic transmission mechanism which is characterized in that a disc I and a disc II are respectively supported on a hollow shaft on the corresponding side of a driving cam, the disc I is supported in a bearing outer ring, and the disc II is fixed with the bearing outer ring; one of the disc I and the disc II is provided with n radial chutes, and the other one is provided with a harmonic channel; a steel ball tooth is arranged in each radial sliding groove, the harmonic channel makes contact with all the steel ball teeth, and the contour face of the driving cam makes contact with all the steel ball teeth. A flexible gear in a traditional harmonic transmission mechanism is replaced by the spherical teeth, accurate movement of the spherical teeth and the first disc or the second disc is achieved, the situation that the flexible gear continuously bears large alternating stress and elastic deformation in the transmission process is effectively avoided, the fatigue abrasion problem of the flexible gear is solved, and the service life of the spherical tooth harmonic transmission mechanism is prolonged; moreover, the reduction ratio can be flexibly adjusted by setting the number of steel ball teeth and the number of waves of a harmonic channel; the device is simple in structure and high in bearing capacity.

Description

Technical Field

[0001] The invention belongs to the field of mechanical transmission, and in particular relates to a ball tooth harmonic transmission mechanism. Background Art

[0002] Harmonic gearing is a new transmission technology that uses elastic deformation to transmit power and motion. Its unique advantages are profoundly impacting the development of multiple industrial sectors. This technology offers significant advantages, including a large transmission ratio, high precision, and a compact structure.

[0003] The single-stage transmission ratio of a harmonic gear drive typically ranges from 50 to 250, significantly simplifying the transmission's hierarchy and structural complexity. In terms of precision, the unique meshing principle and tooth backlash adjustment mechanism can reduce tooth backlash to a minimum or even zero, significantly improving motion and positioning accuracy. Transmission errors can typically be controlled within a range of 1 to 3 inches. Furthermore, the compact design of harmonic gear drives enables them to be smaller and lighter than traditional gear drives, while maintaining the same transmission ratio and load capacity, eliminating the need for numerous gear elements and complex support structures. These advantages have led to their widespread application in a wide range of fields, including aerospace, robotics, optical instruments, automotive industry, and medical devices.

[0004] However, practical applications of harmonic gearing technology still face several pressing challenges. First, the flexspline, a core component, is subjected to high alternating stresses and elastic deformation during the transmission process, which can easily lead to fatigue wear. This not only severely impacts the flexspline's service life but also reduces transmission accuracy, making it unsuitable for applications with a transmission ratio of less than 35. Fatigue damage to the flexspline is particularly prominent under long-term high-load conditions.

[0005] Secondly, the complex tooth design of harmonic gears requires the flexible wheel to have both good elasticity and high precision, which places extremely high demands on the manufacturing process. This increases production difficulty and cost, limiting the widespread application of harmonic gear transmission.

[0006] Furthermore, due to the inherent limitations of the elastic deformation of the flexspline, the other key component, the flexible bearing, suffers from insufficient rigidity, poor high-speed performance, and high cost, resulting in a relatively limited load-bearing capacity for harmonic gears. In scenarios requiring high torque and power transmission, larger harmonic gears are often required, or multiple harmonic gears are combined, which undoubtedly increases the size and structural complexity of the transmission system.

[0007] Finally, the efficiency of harmonic gearing cannot be ignored. Due to the continuous deformation of the flexspline and the friction during meshing, the efficiency of harmonic gearing is generally lower than that of traditional gearing, especially at high speeds, where the efficiency loss is more significant. Summary of the Invention

[0008] The purpose of the present invention is to provide a ball tooth harmonic transmission mechanism, which has the advantages of simple structure, large transmission ratio and flexible adjustment, high precision, strong bearing capacity and long service life.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] The present invention provides a ball tooth harmonic transmission mechanism, comprising a driving cam, a steel ball tooth, a disc 1, a disc 2 and a bearing outer ring; an integrally formed hollow shaft is provided on both sides of the driving cam, and the disc 1 and the disc 2 are respectively supported on the hollow shaft on the corresponding side through bearings, and the disc 1 is supported in the bearing outer ring, and the disc 2 is fixed to the bearing outer ring; the steel ball tooth is connected to the driving cam, the disc 1 and the disc 2 in the following manner: the end face of the disc 1 is provided with n radial grooves uniformly distributed along the circumferential direction, n≥6; the disc 2 is provided with a harmonic groove, and the harmonic groove is composed of z tooth profiles uniformly distributed along the circumferential direction and connected end to end, z≥8; all radial grooves of the disc 1 are directly opposite to the harmonic grooves of the disc 2, a steel ball tooth is provided in each radial groove of the disc 1, and the harmonic groove of the disc 2 is in contact with all the steel ball teeth, and the profile surface of the driving cam is in contact with all the steel ball teeth.

[0011] Preferably, the connection method between the steel ball teeth and the driving cam, disc one and disc two is replaced as follows: the end face of disc one is provided with n radial grooves uniformly distributed along the circumferential direction, n≥6; disc one is provided with a harmonic groove, and the harmonic groove is composed of z tooth profiles uniformly distributed along the circumferential direction and connected end to end, z≥8; all radial grooves of disc two are directly opposite to the harmonic grooves of disc one, and a steel ball tooth is provided in each radial groove of disc two, and the harmonic groove of disc one is in contact with all steel ball teeth, and the profile surface of the driving cam is in contact with all steel ball teeth.

[0012] Preferably, the number of tooth profiles of the harmonic channel is z=n+m, where n is the number of radial slots, and m is the order of the profile of the driving cam, which is 2 or 3; the profile of the driving cam adopts a standard ellipse, a quasi-ellipse, a three-wave shape or a three-convex star shape.

[0013] Preferably, the radial sliding groove is a single arc raceway or a double arc raceway that is symmetrical on both sides, and the radius of the two arcs in the single arc raceway or the double arc raceway is 1.04-1.11 times the radius of the steel ball tooth.

[0014] More preferably, the harmonic channel is an envelope surface formed by sweeping the profiles of all tooth profiles along the entire circumference of the harmonic channel with a 1 / 4 arc as the generatrix, and the radius of the 1 / 4 arc is 1.04-1.11 times the radius of the steel ball tooth.

[0015] Preferably, the end surface of the first disk is provided with n radial sliding grooves uniformly distributed along the circumferential direction, the second disk is provided with a harmonic channel, and when the first disk rotates to output, the reduction ratio i=n / (nz).

[0016] Preferably, the end surface of the first disc is provided with n radial sliding grooves uniformly distributed along the circumferential direction, the first disc is provided with a harmonic channel, and when the first disc rotates to output, the reduction ratio is i=z / (zn).

[0017] More preferably, the steel ball gear is replaced by a metal ceramic ball gear.

[0018] More preferably, the harmonic channel, each radial sliding groove and the profile of the driving cam are all treated with a surface nano-coating.

[0019] More preferably, the theoretical profile of the driving cam is obtained by the polar coordinate equation r1=r b +e·sin(m·t) is designed, and the theoretical profile of all tooth profiles of the whole cycle of the harmonic channel is obtained by the polar coordinate equation r2=r b +e·sin(z·t) is designed, where r b is the base circle radius, and e is the half-wave height.

[0020] The present invention has the following beneficial effects:

[0021] 1. The present invention uses ball teeth to replace the flexspline in a traditional harmonic drive mechanism, effectively preventing the flexspline from being subjected to continuous large alternating stresses and elastic deformation during the transmission process, thereby resolving the problem of fatigue wear on the flexspline. Furthermore, by designing n radial grooves uniformly distributed along the circumference of disk one and a harmonic channel on disk two, or n radial grooves uniformly distributed along the circumference of disk two and a harmonic channel on disk one, the ball teeth can be moved within the radial grooves to form a movable gear tooth portion, maintaining tangential contact with the drive cam and the harmonic channel, thereby achieving precise movement of the ball teeth and disk one or disk two, thereby achieving precise movement of the entire spherical tooth harmonic drive mechanism and extending the service life of the spherical tooth harmonic drive mechanism. Furthermore, the manufacturing process of the flexspline in a traditional harmonic gear drive is complex, costly, and has limited load-bearing capacity. In contrast, the ball teeth in the present invention have a simple structure, are relatively simple to manufacture, are relatively cost-effective, and have a strong load-bearing capacity.

[0022] 2. The present invention realizes a reduction ratio i=n / (nz) when the disk one rotates and outputs by designing n radial grooves uniformly distributed along the circumference of disk one and a harmonic channel of disk two, or realizes a reduction ratio i=z / (zn) when the disk one rotates and outputs by designing n radial grooves uniformly distributed along the circumference of disk two and a harmonic channel of disk one. Moreover, by setting two parameters, namely the number of steel ball teeth and the wave number of the harmonic channel, different reduction ratios can be realized, and the reduction ratio can be flexibly adjusted to meet different application requirements, thereby providing a more flexible and efficient reducer design scheme, which can achieve the best transmission effect under different working conditions.

[0023] 3. The present invention constructs a sinusoidal polar coordinate equation for the profile of the driving cam and the profile of all tooth profiles of the entire circumference of the harmonic channel, thereby ensuring the precise matching of the profile of the driving cam and the profile of all tooth profiles of the entire circumference of the harmonic channel with the ball gear, thereby further improving the service life of the ball gear harmonic transmission mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a cross-sectional view of the overall structure of Example 1 of the present invention.

[0025] Figure 2 This is an exploded view of Example 1 of the present invention.

[0026] Figure 3 This is a stereoscopic diagram of the assembly of the disc 1 and the steel ball gear in Example 1 of the present invention.

[0027] Figure 4 Schematic diagram of the contact between the steel ball tooth, the driving cam and the harmonic channel in the present invention.

[0028] Figure 5 This is a structural stereogram of the disc 1 in Example 1 of the present invention.

[0029] Figure 6 This is a schematic diagram of the radial sliding groove in the present invention being a single arc raceway or a double-sided symmetrical double arc raceway.

[0030] Figure 7 It is a structural stereogram of the driving cam in the present invention.

[0031] Figure 8 This is a structural stereogram of the disc 2 in Example 1 of the present invention.

[0032] Figure 9 This is a cross-sectional view of the overall structure of Example 2 of the present invention.

[0033] Figure 10 Schematic diagram of the three-wave drive cam profile in the present invention.

[0034] Figure 11 It is a schematic diagram of the double-wave drive cam profile in the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings.

[0036] Example 1

[0037] like Figures 1 to 8 As shown, a ball tooth harmonic transmission mechanism includes a driving cam 2, a steel ball tooth 4, a disc 1 3, a disc 2 1 and a bearing outer ring 6; an integrally formed hollow shaft is provided on both sides of the driving cam 2, and the disc 1 3 and the disc 2 1 are respectively supported on the hollow shaft on the corresponding side through bearings, and the disc 1 3 is supported in the bearing outer ring 6, and the disc 2 1 is fixed to the bearing outer ring 6 (for example, fixed by bolts 8); in this embodiment, the steel ball tooth 4 is connected to the driving cam 2, the disc 1 3 and the disc 2 1 in the following manner: an end surface of the disc 1 3 is provided with n radial grooves 32 uniformly distributed along the circumferential direction, n ≥ 6; the disc 2 1 is provided with a harmonic groove 11, the harmonic groove 11 is composed of z tooth profiles uniformly distributed along the circumferential direction and connected end to end, z ≥ 8; all radial grooves of the disc 1 3 are opposite to the harmonic grooves of the disc 2 1, and a steel ball tooth 4 is provided in each radial groove of the disc 1 3, thereby forming a movable gear of the tooth portion, as shown in FIG. Figure 3 As shown, the harmonic grooves of Disc 2 1 are in contact with all the steel ball teeth 4, and the profile of the driving cam 2 is in contact with all the steel ball teeth 4. In this embodiment, Disc 2 1 is fixed to the bearing outer ring 6. When the driving cam rotates, the steel ball teeth 4 always maintain contact with the harmonic grooves of Disc 2 1 and the profile of the driving cam 2. Since Disc 2 1 is fixed, the rotational motion of the driving cam is transmitted to each steel ball tooth. Each steel ball tooth moves within the corresponding radial groove of Disc 1 and rolls along the harmonic groove of Disc 2 1, thereby driving Disc 1 3 to rotate, achieving the precise motion of the ball tooth harmonic transmission mechanism of the present invention. Among them, the connection holes 7 uniformly distributed along the circumference of Disc 1 3 are used to connect the load. When Disc 1 3 rotates, it drives the load to rotate together.

[0038] This embodiment uses a movable gear consisting of a disc 1 (3) and steel ball teeth (4) to replace the flexspline in a conventional harmonic drive mechanism. This effectively prevents the flexspline from being subjected to continuous high alternating stress and elastic deformation during the transmission process, thereby addressing the problem of fatigue wear on the flexspline. Furthermore, by designing n radial grooves uniformly distributed along the circumference of disc 1 and harmonic grooves on disc 2, precise movement of the steel ball teeth with discs 1 and 2 can be achieved, thereby extending the service life of the harmonic drive mechanism. Furthermore, while the manufacturing process for the flexspline in conventional harmonic gear transmissions is complex and costly, the steel ball teeth in this embodiment are relatively simple and cost-effective to manufacture, effectively reducing production costs.

[0039] Example 2

[0040] like Figure 4 、 Figure 7 and Figure 9 As shown, the difference from Example 1 is that the connection method between the steel ball tooth 4 and the disk 1 3 and the disk 2 1 is different. The connection method is specifically as follows: the end face of one end of the disk 2 1 is provided with n radial grooves 32 uniformly distributed along the circumferential direction, n ≥ 6; the disk 1 3 is provided with a harmonic groove 11, and the harmonic groove 11 is composed of z tooth profiles uniformly distributed along the circumferential direction and connected end to end, z ≥ 8; all the radial grooves of the disk 2 1 are directly opposite to the harmonic grooves of the disk 1 3, and a steel ball tooth 4 is provided in each radial groove of the disk 2 1. The tooth portion movable gear composed of the disk 2 1 and each steel ball tooth 4 replaces the flexible wheel in the traditional harmonic transmission mechanism, and the harmonic groove of the disk 1 3 is in contact with all the steel ball teeth 4, and the profile of the driving cam 2 is in contact with all the steel ball teeth 4. In this embodiment, Disc 2 1 is also fixed to the bearing outer ring 6. When the drive cam rotates, the steel ball gears 4 always maintain contact with the harmonic grooves of Disc 1 3 and the profile of the drive cam 2. Since Disc 2 1 is fixed, the rotational motion of the drive cam is transmitted to each steel ball gear. Each steel ball gear moves within the corresponding radial groove of Disc 2 1 and provides thrust to the harmonic groove of Disc 1 3, thereby driving the rotation of Disc 1 3. This embodiment, by designing n radial grooves uniformly distributed along the circumference of Disc 2 1 and the harmonic grooves of Disc 1 3, can achieve precise movement of the steel ball gears and Discs 1 and 2, thereby achieving precise movement of the ball gear harmonic transmission mechanism of this embodiment. The connection holes 7 uniformly distributed along the circumference of Disc 1 3 are used to connect to the load. When Disc 1 3 rotates, it drives the load to rotate together.

[0041] Example 3

[0042] Based on Example 1 or Example 2, the number of tooth profiles in the harmonic channel is further defined as z = n + m, where n is the number of radial slots and m is the order of the drive cam profile, i.e., the number of periodic protrusions in the drive cam profile in polar coordinates. This design ensures that during rotation of the drive cam, each steel ball tooth can smoothly move within the radial slot and maintain conjugate contact with the drive cam and the harmonic channel. In this way, the tooth portion can function as a movable gear, while simultaneously achieving precise motion transmission and simultaneous contact between multiple steel balls and teeth.

[0043] Example 4

[0044] Based on Example 3, the order m of the driving cam's profile is further limited to 2 or 3. This design can simplify the cam structure, increase the transmission ratio, and reduce manufacturing costs. Furthermore, the driving cam's profile can adopt different shapes, such as a standard ellipse, a quasi-ellipse, a three-wave shape, or a three-convex star shape. The corresponding harmonic channel curve can be obtained using a conjugate relationship to meet different transmission requirements.

[0045] Example 5

[0046] Based on Example 1 or 2, the radial groove 32 is a single arc raceway or a double arc raceway symmetrical on both sides, and the radius of the two arcs in the single arc raceway or the double arc raceway is 1.04-1.11 times the radius of the steel ball tooth.

[0047] Example 6

[0048] Based on Example 1 or 2, the harmonic channel is an envelope surface formed by sweeping along the profiles of all tooth profiles of the harmonic channel with a 1 / 4 arc as the main line, and the radius of the 1 / 4 arc is 1.04-1.11 times the radius of the steel ball tooth.

[0049] The present invention ensures that the steel ball gear always maintains good contact with the harmonic channel during movement by designing the harmonic channel as a 1 / 4 arc as the envelope surface formed by the movement of the busbar, thereby improving the transmission stability. The radial groove 32 of the disc 1 3 or the disc 2 1 is a double arc raceway that can provide a better guiding effect, further improving the movement stability and transmission accuracy of the steel ball gear in the harmonic channel. In particular, the radius of the two arcs in the double arc raceway and the 1 / 4 arc radius of the harmonic channel are designed to be 1.04-1.11 times the radius of the steel ball. While ensuring the smooth movement of the steel ball gear, it can control the contact area between the steel ball gear and the double arc raceway and the harmonic channel, increase its load-bearing capacity, reduce wear, and extend its service life.

[0050] Example 7

[0051] Based on Example 1, that is, when the end surface of one end of disk 1 is provided with n radial grooves uniformly distributed along the circumferential direction, disk 2 is provided with a harmonic channel, and disk 1 rotates to output, the reduction ratio i=n / (nz).

[0052] Example 8

[0053] On the basis of Example 2, n radial grooves uniformly distributed along the circumferential direction are provided on one end surface of the disk 2 1 , a harmonic channel is provided on the disk 1 3 , and when the disk 1 3 rotates for output, the reduction ratio is i=z / (zn).

[0054] In Examples 7 and 8, the number of steel ball teeth and the number of harmonic channel waves (tooth profile number) are key parameters. By adjusting these two parameters, different reduction ratios can be achieved, allowing for flexible adjustment to suit different application requirements. Compared to the prior art, this invention provides a more flexible and efficient reducer design, capable of achieving optimal transmission performance under varying operating conditions.

[0055] Example 9

[0056] Based on Example 1 or 2, the disc 3 is supported in the bearing outer ring 6 in the following manner: both the disc 3 and the bearing outer ring 6 are provided with a V-shaped raceway 31, and a plurality of cross rollers 5 uniformly distributed along the circumferential direction are provided between the V-shaped raceways of the disc 3 and the bearing outer ring 6. The cross rollers are composed of two rollers whose axes are arranged to cross each other at 90 degrees.

[0057] Example 10

[0058] Based on any of the above embodiments, the steel ball teeth are replaced with Si3N4 (silicon nitride) or ZrO2 (zirconium oxide) metal ceramic ball teeth. Both Si3N4 and ZrO2 are high-strength, high-hardness materials with good fatigue resistance and high-temperature resistance, excellent mechanical properties and wear resistance, and low density, which can reduce the weight of the overall structure, further improve the transmission efficiency and response speed, and are suitable for high-load and high-speed operation occasions. ZrO2 material has higher toughness and crack resistance, and is suitable for application environments that require high reliability and long life. The application of these materials can significantly improve the service life and transmission accuracy of the ball tooth harmonic drive mechanism, reduce maintenance costs and downtime.

[0059] Therefore, by replacing the steel ball gear with Si3N4 or ZrO2 metal ceramic ball gear, Example 10 provides a more durable and efficient ball gear harmonic drive mechanism.

[0060] Example 11

[0061] Based on any of the above embodiments, the disc 2 1 is provided with an assembly step surface, and contacts the assembly step surface of the bearing outer ring 6, and the assembly step surface of the disc 2 1 and the assembly step surface of the bearing outer ring 6 are both ground, thereby reducing the axial spacing between the disc 2 and the disc 1, so as to eliminate the transmission gap, effectively improve the overall accuracy and stability of the ball gear harmonic transmission mechanism, reduce the transmission backlash, and extend the service life of the ball gear harmonic transmission mechanism to maintain accuracy.

[0062] Example 12

[0063] Based on any of the above embodiments, the harmonic groove, each radial groove, and the profile of the drive cam 2 are all treated with a surface nano-coating. Nano-coating treatment can form a uniform and dense protective layer on the surface of the material. This protective layer can not only improve the surface hardness and wear resistance, effectively reduce friction and wear, but also improve corrosion resistance, thereby extending the service life. As a result, the reliability and stability of the entire ball tooth harmonic transmission mechanism are significantly improved. Through surface nano-coating treatment, the harmonic groove, each radial groove, and the profile of the drive cam 2 can maintain a low friction coefficient and high wear resistance even in a long-term, high-load working environment, thereby reducing maintenance frequency and cost, and improving the overall efficiency and service life of the transmission system.

[0064] Specifically, the nano-coating treatment technology can be achieved by physical vapor deposition (PVD), chemical vapor deposition (CVD), etc. More preferably, the coating material can be selected from nano-ceramic materials with high hardness and high wear resistance, such as titanium nitride (TiN), chromium nitride (CrN), etc.

[0065] Example 13

[0066] In Example 3, the theoretical profile of the driving cam (the actual profile is the theoretical profile minus the ball tooth radius) is calculated by the polar coordinate equation r1=r b +e·sin(m·t) is designed, and the theoretical profile of all tooth profiles of the entire cycle of the harmonic channel (the actual profile is the theoretical profile plus the ball tooth radius) is obtained by the polar coordinate equation r2=r b +e·sin(z·t) is designed, where r b is the base circle radius (i.e., the value of r1 and r2 when the polar angle t=0, which is the average of the maximum and minimum values of r1 or r2), and e is the half-wave height (i.e., the difference between the maximum and mean values of r1 or r2).

[0067] For a clearer explanation, two specific examples of the theoretical polar coordinate equations of the tooth profiles of the entire cycle of the harmonic channel and the theoretical polar coordinate equations of the driving cam are given below:

[0068] ① Take r b =30mm, e=0.3, z=39, n=36, then r1=30+0.3sin(3t), r2=30+0.3sin(39t), at this time, the theoretical profile of the driving cam is as follows Figure 10 As shown, the order of the profile of the driving cam is m=3, that is, the profile of the driving cam is a three-convex star curve.

[0069] ② Take r b =30mm, e=0.3, z=38, n=36, then r1=30+0.3sin(2t), r2=30+0.3sin(38t), at this time, the theoretical profile of the driving cam is as follows Figure 11 As shown, the order of the profile of the driving cam is m=2, that is, the profile of the driving cam is a quasi-elliptical curve.

[0070] The construction of the polar coordinate equations ensures that the profile of the driving cam and the profiles of all tooth profiles of the entire circumference of the harmonic channel are precisely matched with the ball teeth.

Claims

1. A ball tooth harmonic drive mechanism, comprising a driving cam, a disc 1 and a bearing outer ring, characterized in that: It also includes a steel ball tooth and a disc 2; an integrally formed hollow shaft is provided on both sides of the driving cam, and the disc 1 and the disc 2 are respectively supported on the hollow shaft on the corresponding side through bearings, and the disc 1 is supported in the outer ring of the bearing, and the disc 2 is fixed to the outer ring of the bearing; the connection method between the steel ball tooth and the driving cam, disc 1 and disc 2 is: the end face of disc 1 is provided with n radial grooves uniformly distributed along the circumference, n≥6; disc 2 is provided with a harmonic groove, and the harmonic groove is composed of z tooth profiles uniformly distributed along the circumference and connected end to end, z≥8; all radial grooves of disc 1 are directly opposite to the harmonic grooves of disc 2, and a steel ball tooth is provided in each radial groove of disc 1, and the harmonic groove of disc 2 is in contact with all steel ball teeth, and the profile surface of the driving cam is in contact with all steel ball teeth.

2. The ball tooth harmonic drive mechanism according to claim 1, characterized in that: The connection method between the steel ball teeth and the driving cam, disc one and disc two is replaced as follows: the end surface of disc one is provided with n radial grooves uniformly distributed along the circumferential direction, n≥6; disc one is provided with a harmonic groove, and the harmonic groove is composed of z tooth profiles uniformly distributed along the circumferential direction and connected end to end, z≥8; all radial grooves of disc two are directly opposite to the harmonic grooves of disc one, and a steel ball tooth is provided in each radial groove of disc two, and the harmonic groove of disc one is in contact with all the steel ball teeth, and the profile surface of the driving cam is in contact with all the steel ball teeth.

3. A ball tooth harmonic drive mechanism according to claim 1 or 2, characterized in that: The number of tooth profiles of the harmonic channel is z=n+m, where n is the number of radial slots and m is the order of the profile of the driving cam, which is 2 or 3; the profile of the driving cam adopts a standard ellipse, a quasi-ellipse, a three-wave shape or a three-convex star shape.

4. The ball tooth harmonic drive mechanism according to claim 1 or 2, characterized in that: The radial chute is a single arc raceway or a double arc raceway symmetrical on both sides, and the radii of the two arcs in the single arc raceway or the double arc raceway are both 1.04-1.11 times the radius of the steel ball tooth.

5. The ball tooth harmonic drive mechanism according to claim 1 or 2, characterized in that: The harmonic channel is an envelope surface formed by sweeping along the profiles of all tooth profiles of the harmonic channel using a quarter arc as a generatrix, and the radius of the quarter arc is 1.04-1.11 times the radius of the steel ball tooth.

6. The ball gear harmonic drive mechanism according to claim 1, characterized in that: Reduction ratio i=n / (nz).

7. The ball tooth harmonic drive mechanism according to claim 2, characterized in that: The reduction ratio is i=z / (zn).

8. A ball tooth harmonic drive mechanism according to claim 1, 2, 6 or 7, characterized in that: The steel ball gear is replaced by a metal ceramic ball gear.

9. A ball tooth harmonic drive mechanism according to claim 1, 2, 6 or 7, characterized in that: The harmonic channel, each radial sliding groove and the profile surface of the driving cam are all treated with a surface nano-coating.

10. The ball tooth harmonic drive mechanism according to claim 3, characterized in that: The theoretical profile of the driving cam is given by the polar coordinate equation r1=r b +e·sin(m·t) is designed, and the theoretical profile of all tooth profiles of the whole cycle of the harmonic channel is obtained by the polar coordinate equation r2=r b +e·sin(z·t) is designed, where r b is the base circle radius, and e is the half-wave height.

Images