Welding-free spherical tooth transmission shaft

Abstract

The utility model belongs to the technical field of transmission shafts, and particularly relates to a non-welding spherical tooth transmission shaft which comprises an inter-shaft connecting pipe, a first spherical tooth coupler and a second spherical tooth coupler are symmetrically connected to the two ends of the inter-shaft connecting pipe, each of the first spherical tooth coupler and the second spherical tooth coupler comprises a spherical tooth seat, and spherical tooth shafts are connected to the spherical tooth seats in a meshed mode. The self-aligning ball gear is characterized in that one end, close to the ball gear seat, of the ball gear shaft is fixedly connected with a self-aligning assembly, and an arc-shaped surface is arranged at the position, corresponding to the self-aligning assembly, of the ball gear seat. The faults of transmission efficiency reduction, abnormal sound and the like caused by center offset of the outer spherical tooth part after the inner and outer spherical teeth are worn are avoided, the service life of the product is prolonged, and the use effect is improved.

Description

Technical Field

[0001] This utility model belongs to the field of transmission shaft technology, and in particular relates to a weld-free ball gear transmission shaft. Background Technology

[0002] Ball gear drive shafts are drive shafts with a special tooth profile. Because they can withstand high torque and impact loads, they are widely used in engineering machinery, agricultural machinery and industrial equipment.

[0003] Chinese utility model patent application number 202121968357.0 discloses a ball-tooth type flexible universal coupling, wherein the ball teeth, ball seat and ball cap form a first ball-tooth coupling and a second ball-tooth coupling. The first ball-tooth coupling is installed at one end of the pipe through a detachable component, and the second ball-tooth coupling is integrally connected to the other end of the pipe by welding.

[0004] Using welding methods can lead to localized deformation and material degradation of parts due to localized heating during the welding process, affecting the precision and mechanical properties of the parts and reducing their service life. Furthermore, during long-term use, wear on the inner and outer ball teeth can cause excessive play in the clearance between them, which not only reduces power transmission efficiency but also causes vibration and abnormal noise, affecting the performance. Utility Model Content

[0005] The main technical problem this utility model aims to solve is to provide a weld-free ball tooth transmission shaft. The connection method between the ball tooth shaft and the shaft connecting pipe is changed to a cold and hot assembly process, which ensures the mechanical performance of each component. Furthermore, through the cooperation of the steel ball and the spring, the center of the outer ball tooth and the second spherical cavity always keep coincident, avoiding the failures such as reduced transmission efficiency and abnormal noise caused by the center offset of the outer ball tooth after the wear of the inner and outer ball teeth, thereby improving the service life of the product and enhancing its performance.

[0006] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0007] A weld-free ball gear drive shaft includes an inter-shaft connecting pipe, with a first ball gear coupling and a second ball gear coupling symmetrically connected to both ends of the inter-shaft connecting pipe. Both the first ball gear coupling and the second ball gear coupling include a ball gear seat, and a ball gear shaft is meshed on the ball gear seat. The characteristic feature is that a self-aligning component is fixedly connected to one end of the ball gear shaft near the ball gear seat, and an arc-shaped surface is provided on the ball gear seat at a position corresponding to the self-aligning component.

[0008] The following are further optimizations of the above technical solution by this utility model:

[0009] One end of the ball tooth seat has a first spherical cavity, and a number of inner spherical teeth are provided in the first spherical cavity. The ball tooth shaft includes an outer spherical tooth part provided inside the first spherical cavity. A number of outer spherical teeth are fixedly provided on the outer surface of the outer spherical tooth part at positions corresponding to the inner spherical teeth. The outer spherical teeth are meshed with the inner spherical teeth.

[0010] Further optimization: A self-aligning groove is provided at one end of the outer ball tooth near the first spherical cavity. A self-aligning component is fixedly connected in the self-aligning groove. The self-aligning component includes a spring. One end of the spring is fixedly connected to the bottom of the self-aligning groove, and the other end is fixedly connected to a steel ball. The end of the steel ball away from the spring abuts against the arc-shaped surface.

[0011] Further optimization: The arc-shaped surface is set on the bottom surface of the first spherical cavity at a position corresponding to the steel ball. The radius of the arc-shaped surface is adapted to the movement trajectory of the steel ball, and the arc length of the arc-shaped surface is adapted to the deflection angle of the outer spherical teeth.

[0012] Further optimization: A mounting flange is fixedly connected to the other end of the ball tooth seat opposite to the first spherical cavity. A ball cap is also assembled and connected to the end of the ball tooth seat away from the mounting flange. A second spherical cavity is opened inside the ball cap. The second spherical cavity is connected to the first spherical cavity.

[0013] Further optimization: The part of the outer ball tooth located outside the ball cap is fixedly connected to a connecting shaft. An external spline is provided on the outside of the connecting shaft, and an internal spline is provided on the inner wall of the shaft connecting tube. The internal spline and the external spline are connected in a mating manner.

[0014] Further optimization: A second sealing component is fixedly connected to the outer side of each end of the shaft connecting pipe, and the other ends of the two second sealing components are fixedly connected to the first ball gear coupling and the second ball gear coupling, respectively. A first sealing component is provided between the second spherical cavity and the outer ball tooth.

[0015] Further optimization: A first lubrication hole and a first vent hole are provided on the ball tooth seat, and a second lubrication hole and a second vent hole are provided at corresponding positions on the ball cap. The first lubrication hole and the second lubrication hole are interconnected to form a lubrication oil passage. One end of the lubrication oil passage is connected to the first spherical cavity, and a lubrication oil nozzle is fixedly installed at the other end. The first vent hole and the second vent hole are interconnected to form an exhaust channel. One end of the exhaust channel is connected to the first spherical cavity, and an exhaust valve is fixedly installed at the other end.

[0016] Further optimization: A limiting part is provided between the outer ball tooth and the connecting shaft, and a dustproof sleeve is also provided on the outer side of the shaft connecting pipe near the end of the first ball tooth coupling. A third sealing component is fixedly installed on the inner side of the dustproof sleeve near the end of the shaft connecting pipe.

[0017] The present invention adopts the above technical solution and has the following beneficial effects:

[0018] The connection method between the ball gear shaft and the shaft connecting pipe of this utility model is changed from welding to a cold and hot assembly process, which prevents the parts from being deformed by heat during the welding process or the metallographic structure from being destroyed by high temperature. This can not only improve the accuracy of the ball gear drive shaft, but also ensure the material's strength, hardness, shear force and torque and other required mechanical properties.

[0019] This invention, by setting up a self-aligning component, ensures that even with slight wear of the inner and outer ball teeth, the outer ball tooth always remains concentric with the second spherical groove. This avoids power transmission efficiency reduction, vibration, abnormal noise, and other faults caused by play in the outer ball tooth, and extends the service life of the drive shaft.

[0020] This invention features an arc-shaped surface on the bottom surface of the first spherical cavity. The steel ball in the self-aligning assembly abuts against the arc-shaped surface, ensuring that the straight-line distance between the center of the steel ball and the deflection center of the outer spherical tooth remains constant during the process of the steel ball undergoing angular displacement to its limit position as the outer spherical tooth moves. This avoids changes in the meshing clearance between the inner and outer spherical teeth due to the steel ball losing contact with the bottom surface of the first spherical cavity, thus affecting the transmission efficiency.

[0021] This invention improves the material and heat treatment process of the ball gear shaft, making its service life longer than that of the ball gear seat it mates with. Thus, during maintenance, only the ball gear seat that is easy to disassemble and assemble needs to be replaced, thereby extending the working life of the entire transmission shaft.

[0022] This utility model is equipped with a two-stage sealing mechanism, which completely seals the space enclosed by the ball tooth seat and the ball cap, effectively preventing moisture and dirt from the external environment from entering the cavity, avoiding corrosion and wear of internal parts, further improving product quality and reducing the failure rate.

[0023] This utility model is equipped with a lubricating nozzle, through which lubricating oil is injected to lubricate the components inside the spherical cavity, preventing wear between the inner and outer spherical teeth. It is also equipped with an exhaust valve to promptly discharge waste gas from the spherical cavity, preventing damage to the seals.

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a front view of the first embodiment of the present invention;

[0026] Figure 2 This is a cross-sectional view of the internal structure of the first embodiment of the present invention;

[0027] Figure 3 This is a cross-sectional view of the ball tooth seat according to the first embodiment of this utility model;

[0028] Figure 4This is a cross-sectional view of the ball tooth shaft according to the first embodiment of this utility model;

[0029] Figure 5 This is a cross-sectional view of the ball cap according to the first embodiment of this utility model;

[0030] Figure 6 This is a cross-sectional view of the inter-shaft connecting pipe according to the first embodiment of this utility model.

[0031] Figure 7 This is a cross-sectional view of the internal structure of the second embodiment of the present invention.

[0032] In the figure: 1. Inter-shaft connecting pipe; 101. Connecting hole; 2. First ball-tooth coupling; 3. Second ball-tooth coupling; 4. Ball tooth seat; 401. Mounting flange; 402. First spherical cavity; 403. Inner ball tooth; 404. First threaded hole; 405. First vent hole; 406. First lubrication hole; 5. Ball tooth shaft; 501. Outer ball tooth part; 502. Outer ball tooth; 503. Connecting shaft; 504. Self-aligning groove; 6. Self-aligning assembly; 601. Spring; 602. Steel ball; 7. Ball cap; 701. Second spherical cavity; 702. Second threaded hole; 703. Second vent hole; 704. Second lubrication hole; 8. First sealing assembly; 9. Second sealing assembly; 10. Third sealing assembly; 11. Lubricating oil nozzle; 12. Vent valve; 13. Limiting part; 14. Dustproof sleeve; 15. Arc-shaped surface. Detailed Implementation

[0033] Example 1: As Figure 1-6 As shown, a weldless ball gear drive shaft includes an inter-shaft connecting pipe 1. A first ball gear coupling 2 and a second ball gear coupling 3 are symmetrically connected to both ends of the inter-shaft connecting pipe 1. The first ball gear coupling 2 and the second ball gear coupling 3 have the same structure and include a ball gear seat 4. A ball gear shaft 5 is meshed on the ball gear seat 4. A self-aligning component 6 is fixedly connected to one end of the ball gear shaft 5 near the ball gear seat 4. An arc-shaped surface 15 is provided on the ball gear seat 4 at a position corresponding to the self-aligning component 6.

[0034] One end of the ball tooth seat 4 is provided with a first spherical cavity 402, and a plurality of inner spherical teeth 403 are provided in the first spherical cavity 402. The other end of the ball tooth seat 4 opposite to the first spherical cavity 402 is fixedly connected with a mounting flange 401 for fixed connection with an external transmission component.

[0035] The ball tooth shaft 5 includes an outer ball tooth portion 501 disposed inside the first spherical cavity 402. A plurality of outer ball teeth 502 are fixedly disposed on the outer surface of the outer ball tooth portion 501 at positions corresponding to the inner ball teeth 403. The outer ball teeth 502 mesh with the inner ball teeth 403 to transmit power and torque.

[0036] A ball cap 7 is also fitted and connected to the end of the ball tooth seat 4 away from the mounting flange 401. The ball tooth seat 4 and the ball cap 7 are detachably connected. In this embodiment, a plurality of first threaded holes 404 are opened on the outer side of the ball tooth seat 4 along the circumferential direction. A second threaded hole 702 is opened at the corresponding position on the ball cap 7. A fixing bolt is screwed into the second threaded hole 702. The fixing bolt passes through the second threaded hole 702 and is screwed into the first threaded hole 404, connecting the two into a whole, which facilitates disassembly and assembly and maintenance and replacement of internal components.

[0037] In addition to this embodiment, the ball tooth seat 4 and the ball cap 7 can also be connected by riveting or other detachable connection methods to improve the ease of maintenance of the product.

[0038] The inner side of the ball cap 7 is provided with a second spherical cavity 701. The inner diameter of the second spherical cavity 701 is the same as the outer diameter of the end of the outer ball tooth 501 away from the ball tooth seat 4. The second spherical cavity 701 and the first spherical cavity 402 are connected to form a spherical space that encloses the outer ball tooth 501.

[0039] like Figure 2-3 As shown, a self-aligning groove 504 is provided at one end of the outer spherical tooth 501 near the first spherical cavity 402. A self-aligning assembly 6 is fixedly connected in the self-aligning groove 504. The self-aligning assembly 6 includes a spring 601. One end of the spring 601 is fixedly connected to the bottom of the self-aligning groove 504, and the other end is fixedly connected to a steel ball 602. An arc-shaped surface 15 is provided on the bottom surface of the first spherical cavity 402 at a position corresponding to the steel ball 602. The end of the steel ball 602 away from the spring 601 abuts against the arc-shaped surface 15.

[0040] Specifically, the end of the self-aligning groove 504 away from the arc-shaped surface 15 is a circular blind hole. The inner diameter of the circular blind hole is adapted to the outer diameter of the spring 601, and the height is less than the height of the spring 601 in its natural state, so that the spring is initially in a compressed state. The other end of the self-aligning groove 504 is a spherical groove. The inner diameter of the spherical groove is adapted to the outer diameter of the steel ball 602, and the height of the spherical groove is greater than the radius of the steel ball 602, so as to prevent the spring 601 from pushing the steel ball 602 out of the spherical groove.

[0041] The radius of the arc surface 15 is adapted to the movement trajectory of the contact surface of the steel ball 602, and the arc length of the arc surface 15 is adapted to the limit deflection angle of the ball tooth shaft 5. This ensures that when the ball tooth shaft 5 swings within the designed deflection angle range, the steel ball 602 always contacts the arc surface 15. In other words, during the process of the steel ball 602 undergoing angular displacement to the limit position with the outer ball tooth part 501 of the ball tooth shaft 5, the straight-line distance from the center of the steel ball 602 to the deflection center of the outer ball tooth part 501 remains unchanged. This avoids the change in the meshing clearance between the inner ball tooth 403 and the outer ball tooth 502 due to the steel ball 602 losing contact with the bottom surface of the first spherical cavity 402, which would affect the transmission efficiency.

[0042] Initially, the steel ball 602 is fully engaged with the spherical groove of the self-aligning groove 504, and the spring 601 is in a compressed state. Under the restoring force of the spring 601, the steel ball 602 is pushed to abut against the arc-shaped surface 15, and the outer spherical tooth 501 abuts against the second spherical cavity 701. This ensures that the outer spherical tooth 501 and the second spherical cavity 701 are concentric, and there is a gap between the inner spherical tooth 403 and the outer spherical tooth 502 that allows for normal meshing. At the same time, the spring 601 also plays a buffering role in the meshing between the inner spherical tooth 403 and the outer spherical tooth 502.

[0043] When the inner ball tooth 403 and the outer ball tooth 502 wear out, the gap between them will increase, causing the outer ball tooth 501 to wobble and the ball center to shift. This will not only reduce the power transmission efficiency, but also cause vibration and abnormal noise, affecting the performance.

[0044] When the outer ball tooth 501 moves away from the second spherical cavity 701, the spring 601 is further compressed. Under the restoring force of the spring 601, the outer ball tooth 501 is pushed back to its original position and re-aggregates against the second spherical cavity 701. This ensures that even with slight wear on the inner ball tooth 403 and the outer ball tooth 502, the outer ball tooth 501 remains concentric with the second spherical cavity 701, extending the service life of the first ball tooth coupling 2 and the second ball tooth coupling 3 and reducing the frequency of maintenance and replacement of parts.

[0045] The outer ball tooth 501 is fixedly connected to the part outside the ball cap 7 with a connecting shaft 503. The two ends of the shaft connecting tube 1 are provided with connecting holes 101, and the connecting shaft 503 is interference-fitted with the connecting holes 101.

[0046] In some existing technologies, welding is used to fix the separate ball gear shaft 5 to the inter-shaft connecting pipe 1. However, the local high temperature during welding will cause local heat deformation of the parts, reduce the precision of the parts, and cause defects such as material deterioration, stress concentration and uneven composition due to local heat. Ultimately, this leads to a decrease in indicators such as strength, toughness and fatigue resistance, and reduces its service life.

[0047] In this embodiment, the connecting shaft 503 and the connecting hole 101 are connected and installed using a hot and cold assembly process, which can effectively avoid the above-mentioned defects and improve product quality. Specifically, the connecting shaft 503 is subjected to low-temperature treatment while the inter-shaft connecting tube 1 is subjected to high-temperature treatment. The gap between the connecting shaft 503 and the connecting hole 101 is increased by utilizing the principle of thermal expansion and contraction. Then, the two are assembled into one. The hot and cold assembly process is a commonly used production process in current mechanical production, and will not be described in detail in this utility model.

[0048] A first lubrication hole 406 is provided on the ball tooth seat 4, and a second lubrication hole 704 is provided at the corresponding position on the ball cap 7. The first lubrication hole 406 and the second lubrication hole 704 are both through holes and are interconnected to form a lubrication oil channel. One end of the lubrication oil channel is connected to the first spherical cavity 402, and the other end is fixedly installed with a lubrication oil nozzle 11. Lubricating oil is injected into the lubrication oil nozzle 11, and the lubricating oil enters the interior of the first spherical cavity 402 through the lubrication oil channel, forming lubrication between the inner ball tooth 403 and the outer ball tooth 502, reducing the friction between the two, reducing power loss, and reducing heat generation.

[0049] The friction between the inner ball teeth 403 and the outer ball teeth 502 generates heat, causing the gas in the sealed space formed by the first spherical cavity 402 and the second spherical cavity 701 to expand. At the same time, the high temperature will cause some components in the lubricating oil to undergo chemical reactions, producing some waste gas. If these excess gases are not discharged in time, they will cause the seals to deform, break, or even fail. Therefore, an exhaust assembly is also required on the ball tooth drive shaft.

[0050] The ball tooth seat 4 and the ball cap 7 are respectively provided with a first vent hole 405 and a second vent hole 703 at corresponding positions. The first vent hole 405 and the second vent hole 703 are connected to each other to form an exhaust channel. One end of the exhaust channel is connected to the first spherical cavity 402, and the other end is fixedly installed with an exhaust valve 12 to discharge excess gas in the sealed space. At the same time, when adding lubricating oil, the exhaust channel can also be used to detect whether the lubricating oil is full, so as to avoid insufficient lubricating oil filling and reduced lubrication effect.

[0051] To prevent the lubricating oil in the spherical cavity from overflowing from the gap between the ball tooth shaft 5 and the ball cap 7, a first sealing component 8 is fixedly installed between the second spherical cavity 701 and the outer ball tooth portion 501. In this embodiment, the first sealing component 8 is an O-ring seal. An annular groove is provided on the spherical surface of the outer ball tooth portion 501 near the second spherical cavity 701. The cross-sectional shape of the annular groove is adapted to the shape of the O-ring seal. The O-ring seal is fixedly installed in the annular groove.

[0052] In addition to this embodiment, the first sealing component 8 can also be a rectangular sealing ring or a D-shaped sealing ring. The annular groove on the outer ball tooth 501 is adapted to the cross-sectional shape of the sealing ring to prevent lubricating oil from overflowing and affecting the lubrication effect.

[0053] Ball gear drive shafts are mainly used in engineering machinery, agricultural machinery, industrial equipment and other fields. They work in harsh environments. For example, a large amount of water vapor is generated during the steel rolling process, and ball gear drive shafts used in engineering machinery such as excavators and loaders are covered with oil and mud.

[0054] To prevent moisture, dirt, and other contaminants from the external environment from entering the spherical space formed by the first spherical cavity 402 and the second spherical cavity 701, which could cause corrosion or wear of internal components, a second sealing component 9 is fixedly connected to the outer side of each end of the shaft connecting pipe 1. The other ends of the two second sealing components 9 are fixedly connected to the first ball-tooth coupling 2 and the second ball-tooth coupling 3, respectively.

[0055] In this embodiment, the second sealing component 9 can be made of nitrile rubber or other materials with good flexibility and resistance to oil and water. One end of the second sealing component 9 is sleeved on the outside of the inter-shaft connecting pipe 1, and the other end is sleeved on the outside of the ball cap 7. Both ends of the second sealing component 9 are equipped with clamps to fix the second sealing component 9 to the inter-shaft connecting pipe 1 and the ball cap 7 together, forming a sealed space inside to isolate external moisture and dirt.

[0056] Due to the long-term meshing friction between the inner ball teeth 403 and the outer ball teeth 502, even with sufficient lubrication, wear will occur after prolonged operation. Since the ball tooth seat 4 is easier to disassemble and replace than the ball tooth shaft 5, a material with higher strength than the ball tooth seat 4 is selected when manufacturing the ball tooth shaft 5. Furthermore, a more optimized heat treatment process is used for the outer ball teeth 502 to improve the service life of the ball tooth shaft 5. This allows the ball tooth drive shaft to continue to be used simply by repairing or replacing the ball tooth seat 4, thus extending the working life of the ball tooth drive shaft.

[0057] Example 2: Figure 7 As shown, based on the above embodiment 1, the difference between embodiment 2 and embodiment 1 is that the first ball gear coupling 2 is slidably installed at one end of the inter-shaft connecting pipe 1. Specifically, an external spline is provided on the outer side of the connecting shaft 503 on the first ball gear coupling 2, and an internal spline is provided on the inner wall of the connecting hole 101 on the side corresponding to the first ball gear coupling 2 on the inter-shaft connecting pipe 1. The internal spline and the external spline are clearance-fitted, so that the first ball gear coupling 2 can slide axially in the inter-shaft connecting pipe 1. In this way, when the distance between the transmission components installed at both ends of the first ball gear coupling 2 and the second ball gear coupling 3 changes, the first ball gear coupling 2 can be adaptively adjusted through the spline extension part.

[0058] A limiting part 13 is also provided between the outer ball tooth portion 501 of the first ball tooth coupling 2 and the connecting shaft 503 to limit the axial displacement of the first ball tooth coupling 2. One end of the second sealing component 9 located on one side of the first ball tooth coupling 2 is fixedly connected to the outside of the ball cap 7 and the other end is fixedly connected to the outside of the limiting part 13.

[0059] A dustproof sleeve 14 is also provided on the outer side of the end of the inter-shaft connecting pipe 1 near the first ball gear coupling 2. When the first ball gear coupling 2 slides away from the inter-shaft connecting pipe 1, it is used to protect the exposed spline part and prevent dust and other debris from falling on the spline and causing sliding jamming.

[0060] The dustproof sleeve 14 has an installation hole at one end near the limiting part 13, and a threaded installation hole is also provided at the corresponding position on the limiting part 13. The bolt passes through the installation hole on the dustproof sleeve 14 and screws into the threaded installation hole on the limiting part 13, thus fixing one end of the dustproof sleeve 14 to the limiting part 13. The other end of the dustproof sleeve 14 is slidably connected to the inter-shaft connecting pipe 1.

[0061] A third sealing component 10 is fixedly installed on the inner side of the dustproof sleeve 14 near the end of the inter-shaft connecting pipe 1. In this embodiment, the third sealing component 10 is an O-ring, which seals the dustproof sleeve 14 and the inter-shaft connecting pipe 1 to protect the internal spline.

[0062] The ball gear drive shaft of this utility model adopts a cold and hot assembly process to assemble the ball gear shaft 5 and the inter-shaft connecting pipe 1 together, which prevents component defects caused by welding operations and improves product quality. At the same time, a self-aligning component 6 is set to compensate for the gap after the inner ball gear 403 and the outer ball gear 502 mesh and wear, and avoids transmission instability, abnormal noise and other faults caused by the axial movement of the outer ball gear 501, further improving the service life of the product.

[0063] For those skilled in the art, any changes, modifications, substitutions, and variations made to the implementation methods without departing from the principles and spirit of this utility model, based on the teachings of this utility model, still fall within the protection scope of this utility model.

Claims

1. A weldless ball gear drive shaft, comprising an inter-shaft connecting pipe (1), wherein a first ball gear coupling (2) and a second ball gear coupling (3) are symmetrically connected to both ends of the inter-shaft connecting pipe (1), wherein both the first ball gear coupling (2) and the second ball gear coupling (3) include ball gear seats (4), and ball gear shafts (5) are meshed on the ball gear seats (4), characterized in that: A self-aligning component (6) is fixedly connected to one end of the ball gear shaft (5) near the ball gear seat (4), and an arc-shaped surface (15) is provided on the ball gear seat (4) at the position corresponding to the self-aligning component (6).

2. The weldless ball gear drive shaft according to claim 1, characterized in that: One end of the ball tooth seat (4) is provided with a first spherical cavity (402), and a plurality of inner ball teeth (403) are provided in the first spherical cavity (402). The ball tooth shaft (5) includes an outer ball tooth part (501) provided inside the first spherical cavity (402). A plurality of outer ball teeth (502) are fixedly provided on the outer surface of the outer ball tooth part (501) at a position corresponding to the inner ball teeth (403). The outer ball teeth (502) mesh with the inner ball teeth (403).

3. The weldless ball gear drive shaft according to claim 2, characterized in that: The outer spherical tooth (501) has a self-aligning groove (504) at one end near the first spherical cavity (402). A self-aligning assembly (6) is fixedly connected inside the self-aligning groove (504). The self-aligning assembly (6) includes a spring (601). One end of the spring (601) is fixedly connected to the bottom of the self-aligning groove (504), and the other end is fixedly connected to a steel ball (602). The end of the steel ball (602) away from the spring (601) abuts against the arc surface (15).

4. The weldless ball gear transmission shaft according to claim 3, characterized in that: The arc surface (15) is set on the bottom surface of the first spherical cavity (402) at a position corresponding to the steel ball (602). The radius of the arc surface (15) is adapted to the movement trajectory of the contact surface of the steel ball (602), and the arc length of the arc surface (15) is adapted to the deflection angle of the outer spherical tooth (501).

5. A weld-free ball gear drive shaft according to claim 4, characterized in that: A mounting flange (401) is fixedly connected to the other end of the ball tooth seat (4) opposite to the first spherical cavity (402). A ball cap (7) is also assembled and connected to the end of the ball tooth seat (4) away from the mounting flange (401). A second spherical cavity (701) is opened inside the ball cap (7). The second spherical cavity (701) and the first spherical cavity (402) are connected. A first sealing assembly (8) is provided between the second spherical cavity (701) and the outer ball tooth part (501).

6. A weld-free ball gear drive shaft according to claim 5, characterized in that: A connecting shaft (503) is fixedly connected to the part of the outer ball tooth (501) located outside the ball cap (7), and connecting holes (101) are opened at both ends of the shaft connecting tube (1).

7. A weld-free ball gear drive shaft according to claim 6, characterized in that: The connecting shaft (503) of the first ball gear coupling (2) and the second ball gear coupling (3) is press-fitted with the corresponding connecting hole (101). The connecting shaft (503) is assembled in the connecting hole (101) by hot and cold assembly. A second sealing component (9) is fixedly connected to the outer side of each end of the shaft connecting pipe (1). The other ends of the two second sealing components (9) are fixedly connected to the ball caps (7) of the first ball gear coupling (2) and the second ball gear coupling (3).

8. A weld-free ball gear drive shaft according to claim 6, characterized in that: The connecting shaft (503) of the second ball gear coupling (3) is interference-fitted with the connecting hole (101) on the corresponding side. The connecting shaft (503) is assembled in the connecting hole (101) by hot and cold assembly. The connecting shaft (503) of the first ball gear coupling (2) is provided with an external spline on the outside. The connecting hole (101) on the corresponding side of the first ball gear coupling (2) is provided with an internal spline. The internal spline and the external spline are matched. The first ball gear coupling (2) is slidably installed in the connecting pipe (1).

9. A weld-free ball gear transmission shaft according to claim 8, characterized in that: A limiting part (13) is provided between the outer ball tooth part (501) of the first ball tooth coupling (2) and the connecting shaft (503). A dustproof sleeve (14) is also provided on the outer side of the shaft connecting pipe (1) near the end of the first ball tooth coupling (2). A third sealing component (10) is fixedly installed on the inner side of the dustproof sleeve (14) near the end of the shaft connecting pipe (1).

10. A weld-free ball gear drive shaft according to claim 7 or 9, characterized in that: The ball tooth seat (4) is provided with a first lubrication hole (406) and a first vent hole (405). The ball cap (7) is provided with a second lubrication hole (704) and a second vent hole (703) at the corresponding positions. The first lubrication hole (406) and the second lubrication hole (704) are connected to each other to form a lubrication oil passage. One end of the lubrication oil passage is connected to the first spherical cavity (402), and the other end is fixedly installed with a lubrication oil nozzle (11). The first vent hole (405) and the second vent hole (703) are connected to each other to form an exhaust channel. One end of the exhaust channel is connected to the first spherical cavity (402), and the other end is fixedly installed with an exhaust valve (12).

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