Robot joint with adjustable friction torque and use method

Abstract

The invention discloses a friction torque adjustable robot joint and a using method, and belongs to the field of robots, a plurality of robot joints can be combined for use, and each robot joint is structurally characterized in that a rotating shaft is placed in a barrel-shaped cavity of a pressure loading structure; positioning bolts are placed on the end surfaces of the rotating shafts; the lower limb connecting device is of a U-like integrated structure, is connected with the rotating shaft through a positioning bolt, and is matched with a fastening screw for installation; the upper limb connecting clamping head is of a U-like integrated structure and is installed in cooperation with the pressure loading structure, the gasket, the saddle-shaped spring and the pre-tightening force adjusting bolt. Robot joints can be independently mounted to realize a one-way adjusting function; angle adjustment in two directions can be achieved through combined installation of the upper limb connecting clamping head. Coordination and unification of position keeping stability and posture adjusting smoothness can be achieved, the risk of joint failure caused by serious abrasion possibly caused by large friction force is reduced, a self-lubricating polymer material with good abrasion resistance is introduced to serve as the rotating shaft, and the performance degradation rate of the joint after long-term repeated use is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of robots and relates to a robot joint with adjustable frictional torque and a usage method thereof. Background Art

[0002] Mechanical joints are important connectors between various moving parts of robots, responsible for maintaining the relative positions and adjusting the postures of the parts. When in the position-holding state, the frictional force between the joint friction pairs must be large enough to resist the torque generated by external loads. However, when performing posture adjustment, it is desired that the frictional force between the joint friction pairs is relatively small to ensure the smoothness of the adjustment process, and at the same time, it is necessary to ensure that the performance of the joint friction pairs decays less after multiple uses. Obviously, the above functional requirements are contradictory. In addition, in the humanoid robot (doll) involved in the present invention, the entire joint needs to be covered with a simulation skin, and the joint posture adjustment can only be performed manually, and the covering material cannot be damaged during use, which further improves the design requirements and difficulties.

[0003] To solve the above problems, one way is to design a locking-relaxing mechanism on the joint, that is, use this mechanism for locking and limiting when position holding is required, and adjust this mechanism to the relaxed state during posture adjustment to greatly reduce the adjustment torque; the other way is to set a torque adjustment mechanism in the joint to make the maximum holding torque provided by the joint as close as possible to the actually required position holding torque, thereby reducing the frictional resistance during posture adjustment. Unfortunately, the joint structures in current robots are complex. In particular, the joints in dolls mainly still use bolts and gaskets for pressurization, having disadvantages such as limited adjustment range and serious wear after long-term use resulting in insufficient holding torque.

[0004] In view of the deficiencies of the existing joint technology and the special requirements of doll joints, the present invention provides a mechanical joint with good position holding and posture adjustment functions and a usage method thereof. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a novel robot joint, and the innovations are as follows: First, a special force - adding structure is designed to adjust the pressure and frictional torque of the friction interface to meet the requirements of position holding and attitude adjustment under different load conditions, so that the holding torque of the joint is only slightly greater than the rated holding torque, ensuring that the joint can maintain its position under the action of external loads and that the adjustment torque required for attitude adjustment is not too large, achieving the coordinated unity of the stability of position holding and the smoothness of attitude adjustment; Second, by designing a rotating shaft, a relatively large friction interface area is formed on its outer surface and the diameter of the rotating shaft is appropriately increased to increase the distance between the frictional force and the rotating shaft, so that a relatively large total frictional torque can be formed even when the interface frictional force is small to meet the requirements of the rated holding torque, reducing the risk of joint failure caused by severe wear possibly due to large frictional force; Third, by introducing a polymer material with better self - lubricating and anti - wear properties as the rotating shaft, the performance attenuation rate after long - term repeated use of the joint is significantly reduced.

[0006] In order to achieve the above - mentioned purpose, the technical solution adopted by the present invention is as follows:

[0007] A robot joint with adjustable frictional torque, and multiple robot joint components can be combined for use. The robot joint component includes a pressure - loading structure 1, a rotating shaft 2, a lower - limb connecting device 3, a positioning pin 4, a fastening screw 6, an upper - limb connecting chuck 7, a pre - tightening force adjusting bolt 8, a gasket 9, a saddle - shaped spring 10, and a limit bolt 11. The rotating shaft 2 is placed inside the pressure - loading structure 1; the positioning pin 4 is placed on the end face of the rotating shaft 2; the lower - limb connecting device 3 is an integrated structure similar to a U - shape, connected to the rotating shaft 2 through the positioning pin 4 and installed in cooperation with the fastening screw 6; the upper - limb connecting chuck 7 is an integrated structure similar to a U - shape, and is installed in cooperation with the pressure - loading structure 1, the gasket 9, the saddle - shaped spring 10, and the pre - tightening force adjusting bolt 8. Specifically:

[0008] The main body of the pressure - loading structure 1 is a barrel - shaped cavity 1 - 1 with an opening on one side, and the barrel - shaped cavity 1 - 1 is used to place the rotating shaft 2; on the opening side of the pressure - loading structure 1, an upper side pressing plate 1 - 2 and a lower side pressing plate 1 - 3 extend radially outward respectively, and the upper side pressing plate 1 - 2 and the lower side pressing plate 1 - 3 are flush; first through - holes 1 - 4 are provided at corresponding positions on the upper side pressing plate 1 - 2 and the lower side pressing plate 1 - 3 for passing through the pre - tightening force adjusting bolt 8; two second through - holes 1 - 5 are provided at corresponding positions on both front ends of the upper side pressing plate 1 - 2 and the lower side pressing plate 1 - 3 for placing the limit bolt 11.

[0009] The rotating shaft 2 is cylindrical as a whole and is placed in the barrel - shaped cavity 1 - 1 of the pressure - loading structure 1. Four blind holes 2 - 1 are symmetrically provided on each end face of the rotating shaft 2 for placing the positioning pin 4.

[0010] The described lower limb connecting device 3 is an integrated U-shaped structure, including a middle plate and U-shaped fin structures 3-1 located on both sides of the middle plate; four third through holes 3-2 are provided at corresponding positions on the fins 3-1 on both sides, and the positioning pins 4 pass through the 4 third through holes 3-2 and enter the 4 blind holes 2-1 on the rotating shaft 2, so that the lower limb connecting device 3 and the rotating shaft 2 do not rotate relative to each other; one first threaded hole 3-3 is also provided on each of the fins 3-1 on both sides, which is used in cooperation with the fastening screw 6; a second threaded hole 3-4 is provided in the middle of the middle plate as a reserved interface for the robot limb component.

[0011] The upper limb connection chuck 7 described above is an integrated U-shaped structure, including a middle plate and U-shaped thin fins 7-1 and U-shaped thick fins 7-2 located on both sides of the middle plate. Among them, the U-shaped thin fins 7-1 are thinner and have better elasticity, while the U-shaped thick fins 7-2 are thicker and have greater stiffness. The distance between the inner surfaces of the two fins is slightly greater than the distance between the outer surfaces of the upper and lower pressure plates of the pressure loading structure 1, so that the upper and lower pressure plates of the pressure loading structure 1 can be inserted between the U-shaped thin fins 7-1 and the U-shaped thick fins 7-2; a fourth through hole 7-3 is provided on the U-shaped thin fin 7-1, and a third threaded hole 7-4 corresponding to it is provided on the U-shaped thick fin 7-2. The two holes are coaxial and correspond to the first through hole 1-4 on the upper and lower pressure plates of the pressure loading structure 1. Among them, the diameter of the fourth through hole 7-3 is large and can accommodate the saddle spring 10. The diameter of the third threaded hole 7-4 is small and corresponds to the size of the pre-tightening force adjusting bolt 8 for it to screw in the pre-tightening force adjusting bolt 8, while the diameter of the first through hole 1-4 on the upper and lower pressure plates of the pressure loading structure 1 is between the two. In actual use, the pre-tightening force adjusting bolt 8 is sequentially passed through the gasket 9, the saddle spring 10, the fourth through hole 7-3, the first through hole 1-4 and the third threaded hole 7-4 to form a force application structure composed of a bolt-gasket-thin fin-saddle spring-upper and lower pressure plates-thick fin, which is used to adjust the pressure and friction force between the barrel-shaped cavity 1-1 of the pressure loading structure 1 and the surface of the rotating shaft 2, and realize the function of maintaining the joint position or adjusting the posture; two fifth through holes 7-5 are provided on both sides of the U-shaped thin fin 7-1 close to the middle plate, and two fourth threaded holes 7-6 are provided at the corresponding positions on both sides of the U-shaped thick fin 7-2 close to the middle plate. The limit bolt 11 is sequentially passed through the fifth through hole 7-5, the second through hole 1-5 and the fourth threaded hole 7-6 to limit the relative rotation of the pressure loading structure 1 and the upper limb connection chuck 7; a fifth threaded hole 7-7 is provided at the middle position of the middle plate as a reserved interface with the robot limb component; a groove 7-8 is provided in the middle of the middle plate for positioning when two upper limb connection chucks 7 are interconnected; the material is locally removed near the thicker fin 7-2 on one side of the groove 7-8, so that the groove 7-8 is square, and the fifth threaded hole 7-7 is located at the center of the square groove 7-8, so as to ensure that when the two upper limb connection chucks 7 are interconnected with the groove 7-8 against the groove 7-8, the two threaded holes 7-7 are exactly coaxial, so that the two upper limb connection chucks 7 can be connected by a threaded rod, but there is a 90 o degree relative rotation angle, so as to realize the movement of the joint in two rotational degrees of freedom.

[0012] Furthermore, the pressure loading structure 1 is made of a metal material. The rotating shaft 2 is made of a polymer material with good anti-wear and self-lubricating properties. The lower limb connection device 3 is made of a metal material. The upper limb connection chuck 7 is made of a metal material.

[0013] Further, there are 8 positioning pins 4 in total, which are made of metal materials; the positioning pins 4 are used to limit the relative rotation between the lower limb connecting device 3 and the rotating shaft 2.

[0014] Further, the robot joint further includes 2 end cover plates 5, which are respectively arranged at the outer ends of the fins on both sides of the lower limb connecting device 3. There are through holes in the middle of the end cover plates, corresponding to the first threaded holes 3-3 on the fins on both sides of the lower limb connecting device 3; the end cover plates 5 are made of metal materials and are used to prevent the positioning pins 4 from sliding out axially.

[0015] Further, there are 2 fastening screws 6 in total, which are made of metal materials. First, they pass through the through holes on the end cover plates 5, and then cooperate with the first threaded holes 3-3 on the lower limb connecting device 3 to press the end cover plates 5 onto the fin structures on both sides of the lower limb connecting device 3, ensuring that the positioning pins 4 are tightly pressed into the 4 blind holes 2-1 of the rotating shaft 2.

[0016] Further, the pre-tightening force adjusting bolt 8 is sequentially inserted into the gasket 9, the saddle spring 10, the fourth through hole 7-3 on the upper limb connecting chuck 7, the first through hole 1-4 on the pressure loading structure 1, and the third threaded hole 7-4 on the upper limb connecting chuck 7, forming a bolt-gasket-thin fin-saddle spring-upper and lower pressing plates-thick fin force application structure, adjusting the pressure and friction force between the barrel-shaped cavity 1-1 of the pressure loading structure 1 and the surface of the rotating shaft 2, and realizing the functions of joint position holding or attitude adjustment; the pre-tightening force adjusting bolt 8, the gasket 9, and the saddle spring 10 are all made of metal materials.

[0017] Further, there are two limit bolts 11 in total, which are sequentially inserted into the fifth through hole 7-5 on the upper limb connecting chuck 7, the second through hole 1-5 of the pressure loading structure 1, and the fourth threaded hole 7-6 on the upper limb connecting chuck 7 to limit the relative rotation between the pressure loading structure 1 and the upper limb connecting chuck 7.

[0018] An installation and use method of a robot joint with adjustable frictional torque includes the following steps:

[0019] S1: Place the cylindrical rotating shaft 2 into the cylindrical barrel 1-1 of the pressure loading structure 1;

[0020] S2: Insert the U-shaped fin structures on the lower limb connecting device 3 from both sides of the pressure loading structure 1, adjust the lower limb connecting device 3 to a proper position so that the third through holes 3-2 on it correspond to the blind holes 2-1 on the rotating shaft 2 in the pressure loading structure 1 one by one. Insert all 4 positioning pins 4 into the third through holes 3-2 and the blind holes 2-1. The length of the positioning pin 4 should be greater than the depth of the blind hole 2-1 and at the same time not greater than the sum of the depth of the blind hole 2-1 and the depth of the third through hole 3-2.

[0021] S3: Press the end cover plate 5 at the corresponding position on the outer side of the U-shaped fin on the lower limb connecting device 3, and screw the fastening screw 6 into the first threaded hole 3-3 to prevent the positioning pin 4 from slipping out of the third through hole 3-2, so that there is no relative rotation between the lower limb connecting device 3 and the cylindrical rotating shaft 2.

[0022] S4: Repeat S2 and S3 to install and fix the 4 positioning pins 4 and the cover plate 5 on the other end face of the U-shaped fin on the lower limb connecting device 3 with the fastening screw 6.

[0023] S5: Installation of the upper limb connecting chuck 7 under the single-way adjustment and two-way adjustment functions:

[0024] (1) Installation and use of a single upper limb connecting chuck 7 with a single-way adjustment function:

[0025] S5.1: Insert the upper and lower pressure plates of the pressure loading structure 1 into the inner side of the U-shaped fin of the upper limb connecting chuck 7, adjust the position to align the first through hole 1-4, the fourth through hole 7-3 and the third threaded hole 7-4, and then insert the pre-tightening force adjusting bolt 8 through the gasket 9, the saddle spring 10, the fourth through hole 7-3, the first through hole 1-4 and the third threaded hole 7-4 in sequence to form a bolt-gasket-thin fin-saddle spring-upper and lower pressure plates-thick fin force application structure. At this time, only partially screw the pre-tightening force adjusting bolt 8 into the third threaded hole 7-4 so that the pressure loading structure 1 and the upper limb connecting chuck 7 can still rotate relative to each other for the implementation of subsequent steps.

[0026] S5.2: Adjust the relative position of the upper and lower pressure plates of the pressure loading structure 1 and the upper limb connecting chuck 7 to align the fifth through hole 7-5, the second through hole 1-5 and the fourth threaded hole 7-6. Insert the two limit bolts 11 into the fifth through hole 7-5 on the upper limb connecting chuck 7 and the second through hole 1-5 of the pressure loading structure 1 in sequence, and finally screw them into the fourth threaded hole 7-6 on the upper limb connecting chuck 7 to limit the relative rotation between the pressure loading structure 1 and the upper limb connecting chuck 7.

[0027] S5.3: According to the actual requirements, adjust the depth of the pre-tightening force adjusting bolt 8 screwed into the third threaded hole 7-4, that is, adjust the pressure and frictional force applied by the adjusting bolt-saddle spring-pressure plate force application structure between the inner surface of the pressure loading structure 1 and the surface of the rotating shaft 2 to adapt to different rated load requirements, and complete the installation of a single robot joint with a one-way adjustment function;

[0028] S5.4: Under the action of an external force equal to or less than the rated load, the joint will remain stationary, that is, the joint is in a position holding state; if an external force greater than the rated load is applied to the joint, relative rotation along the axis direction of the rotating shaft 2 can be generated between the rotating shaft 2 and the pressure loading structure 1, driving the same relative rotation of the lower limb connecting device 3 and the upper limb connecting chuck 7, that is, realizing the one-way attitude adjustment of the joint.

[0029] (2) Installation and use of two upper limb connecting chucks 7 with a two-way adjustment function:

[0030] S5.5: Snap the two upper limb connecting chucks 7 in the way of groove 7-8 facing groove 7-8, and the directions of the two grooves will differ by 90 o , and then use a screw of appropriate length to screw into the threaded hole 7-7. When screwing in, inject sealant between the screw and the threaded hole, and wait for it to cure to firmly connect the two upper limb connecting chucks 7;

[0031] S5.6: Insert the upper and lower pressure plates of the pressure loading structure 1 assembled in steps S1~S4 into the inner side of the U-shaped fins of any one of the upper limb connecting chucks 7 assembled in step S5.5, adjust the position to align the first through hole 1-4, the fourth through hole 7-3 and the third threaded hole 7-4, and then sequentially insert the pre-tightening force adjusting bolt 8 through the gasket 9, the saddle spring 10, the fourth through hole 7-3, the first through hole 1-4 and the third threaded hole 7-4 to form a bolt-gasket-thin fin-saddle spring-upper and lower pressure plates-thick fin force application structure. At this time, only partially screw the pre-tightening force adjusting bolt 8 into the third threaded hole 7-4 so that the pressure loading structure 1 and the upper limb connecting chuck 7 can still rotate relative to each other for subsequent steps;

[0032] S5.7: Adjust the relative position of the upper and lower pressure plates of the pressure loading structure 1 and the upper limb connecting chuck 7 to align the fifth through hole 7-5, the second through hole 1-5 and the fourth threaded hole 7-6. Insert the two limit bolts 11 sequentially into the fifth through hole 7-5 on the upper limb connecting chuck 7 and the second through hole 1-5 of the pressure loading structure 1, and finally screw them into the fourth threaded hole 7-6 on the upper limb connecting chuck 7 to limit the relative rotation of the pressure loading structure 1 and the upper limb connecting chuck 7;

[0033] S5.8: According to actual requirements, adjust the depth of the pre-tightening force adjusting bolt 8 screwed into the third threaded hole 7-4, that is, adjust the pressure and friction force applied by the adjusting bolt - gasket - thin fin - saddle spring - upper and lower pressure plates - thick fin force application structure between the inner surface of the pressure loading structure 1 and the surface of the rotating shaft 2 to adapt to different rated load requirements, and complete the installation of one of the two joints with two-way adjustment function;

[0034] S5.9: Repeat steps S1~S4 to complete the installation of another set of lower limb connecting devices 3, rotating shafts 2 and their supporting components;

[0035] S5.10: Insert the upper and lower pressure plates of the pressure loading structure 1 assembled in step S5.9 into the inner side of the U-shaped fins of the other upper limb connecting chuck 7 assembled in step S5.5, adjust the position to align the first through hole 1-4 with the fourth through hole 7-3 and the third threaded hole 7-4, and then sequentially insert the pre-tightening force adjusting bolt 8 through the gasket 9, saddle spring 10, fourth through hole 7-3, first through hole 1-4 and third threaded hole 7-4 to form a bolt - gasket - thin fin - saddle spring - upper and lower pressure plates - thick fin force application structure. At this time, only partially screw the pre-tightening force adjusting bolt 8 into the third threaded hole 7-4 so that the pressure loading structure 1 and the upper limb connecting chuck 7 can still rotate relative to each other for subsequent steps;

[0036] S5.11: Adjust the relative position of the upper and lower pressure plates of the pressure loading structure 1 and the upper limb connecting chuck 7 to align the fifth through hole 7-5, the second through hole 1-5 and the fourth threaded hole 7-6. Insert the two limit bolts 11 sequentially into the fifth through hole 7-5 on the upper limb connecting chuck 7 and the second through hole 1-5 of the pressure loading structure 1, and finally screw them into the fourth threaded hole 7-6 on the upper limb connecting chuck 7 to limit the relative rotation of the pressure loading structure 1 and the upper limb connecting chuck 7;

[0037] S5.12: According to actual requirements, adjust the depth of the pre-tightening force adjusting bolt 8 screwed into the third threaded hole 7-4, that is, adjust the pressure and friction force applied by the adjusting bolt - saddle spring - pressure plate force application structure between the inner surface of the pressure loading structure 1 and the surface of the rotating shaft 2 to adapt to different rated load requirements, and complete the installation of the series compound joint with two-way adjustment function;

[0038] S5.13: Since the two upper limb connecting chucks 7 assembled in step S5.5 are coaxial but differ by 90 o, so the two joints in step S5.12 can achieve rotational angle adjustment in two directions, and are suitable as joints at the shoulders and waists of robots, etc. Since the force - adding structures composed of bolts - gaskets - thin fins - saddle springs - upper and lower pressure plates - thick fin plates of the two joints are independent of each other, the holding torques of the two joints in two directions can be independently adjusted according to the actual rated load requirements. Under the action of an external force equal to or less than the rated load, the joints will remain stationary, that is, the joints are in a position - holding state. If an external force greater than the rated load is applied to the joints in different directions, the joints can be rotated in the corresponding directions, ultimately realizing the two - way attitude adjustment of the joints.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The main body of the pressure - loading structure in the present invention is a barrel - shaped cavity with an opening on one side. The friction between the inner wall of the barrel - shaped cavity and the rotating shaft can be increased or decreased through the bolt - saddle spring - pressure plate force - adding structure, which can meet the position - holding and attitude - adjustment requirements under different rated external load conditions, has relatively low requirements for the machining accuracy of components, and is convenient for installation and adjustment. The direction of the adjusting torque of the pre - tightening force adjusting bolt is perpendicular to the rotating direction of the joint friction pair, avoiding the loosening of the pre - tightening force adjusting bolt that may occur during the long - term use of the joint.

[0041] (2) The main body of the friction pair in the present invention is a column - shaped rotating shaft, and the contact area between the friction pairs is large. Under the same external load conditions, only a small friction force between the friction pairs is sufficient to generate a large enough total friction torque to resist the external load, and the lower friction force can effectively reduce the friction and wear during long - term use. In addition, the rotating shaft is made of a polymer material with good anti - wear and self - lubricating properties, which can further prevent the attenuation of joint performance after long - term use.

[0042] (3) The structures of the components in the present invention are relatively simple, and castings or some standard parts can be used, which have good versatility. The connection method mainly uses bolt and pin connections, greatly reducing the processing cost and installation difficulty, and improving the convenience of use.

[0043] (4) Through simple assembly, the present invention can prepare a single - set robot joint with a single - way adjustment function, or a composite joint with a two - way attitude - adjustment function can be composed of two sets of joints in series, which can meet the connection requirements between different limbs or body parts of a humanoid robot. Brief Description of the Drawings

[0044] Figure 1 Exploded schematic diagram of a single - set joint structure with a single - way attitude - adjustment function;

[0045] Figure 2 Schematic diagram of the pressure - loading structure;

[0046] Figure 3 Schematic diagram of a cylindrical rotating shaft

[0047] Figure 4 Schematic diagram of the lower limb connecting device

[0048] Figure 5 Schematic diagram of the upper limb connecting chuck

[0049] Figure 6 Schematic diagram of the overall single - set joint with one - way attitude adjustment function

[0050] Figure 7 Cross - sectional view of the single - set joint with one - way attitude adjustment function

[0051] Figure 8 Schematic diagram of the single - set joint with one - way attitude adjustment function after attitude adjustment

[0052] Figure 9 Schematic diagram of the overall composite joint with two - way attitude adjustment function

[0053] In the figure: 1 pressure - loading structure, 2 rotating shaft, 3 lower limb connecting device, 4 positioning pin, 5 end cover plate, 6 fastening screw, 7 upper limb connecting chuck, 8 pre - tightening force adjusting bolt, 9 gasket, 10 saddle - shaped spring, 11 limit bolt;

[0054] 1 - 1 barrel - shaped cavity, 1 - 2 upper side pressing plate, 1 - 3 lower side pressing plate, 1 - 4 first through - hole, 1 - 5 second through - hole; 2 - 1 blind hole; 3 - 1 U - shaped fin structure, 3 - 2 third through - hole, 3 - 3 first threaded hole, 3 - 4 second threaded hole; 7 - 1 U - shaped thin fin, 7 - 2 U - shaped thick fin, 7 - 3 fourth through - hole, 7 - 4 third threaded hole, 7 - 5 fifth through - hole, 7 - 6 fourth threaded hole, 7 - 7 fifth threaded hole, 7 - 8 groove. Detailed implementation manners

[0055] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0056] A robot joint with adjustable frictional torque, the robot joint includes a pressure - loading structure 1, a rotating shaft 2, a lower limb connecting device 3, a positioning pin 4, a fastening screw 6, an upper limb connecting chuck 7, a pre - tightening force adjusting bolt 8, a gasket 9, a saddle - shaped spring 10, and a limit bolt 11. Specifically:

[0057] The main body of the described pressure loading structure 1 is a barrel-shaped cavity 1-1 with an opening on one side. The barrel-shaped cavity 1-1 is used to place the rotating shaft 2. On the opening side of the pressure loading structure 1, an upper pressing plate 1-2 and a lower pressing plate 1-3 extend radially outward respectively, and the upper pressing plate 1-2 is flush with the lower pressing plate 1-3. At corresponding positions on the upper pressing plate 1-2 and the lower pressing plate 1-3, there are first through holes 1-4 for passing through the pre-tightening force adjusting bolts 8. At corresponding positions at the front ends on both sides of the upper pressing plate 1-2 and the lower pressing plate 1-3, there are two second through holes 1-5 each for placing the limit bolts 11.

[0058] The whole rotating shaft 2 is cylindrical and is placed in the barrel-shaped cavity 1-1 of the pressure loading structure 1. On both end faces of the rotating shaft 2, 4 blind holes 2-1 are symmetrically arranged on each side for placing the positioning pins 4.

[0059] The described lower limb connecting device 3 is an integrated structure similar to a U shape, including a middle plate and U-shaped fin structures 3-1 on both sides of the middle plate. At corresponding positions on the two fin structures 3-1, there are four third through holes 3-2 each. The positioning pins 4 pass through the 4 third through holes 3-2 and enter the 4 blind holes 2-1 on the rotating shaft 2, so that the lower limb connecting device 3 and the rotating shaft 2 do not rotate relative to each other. On each of the two fin structures 3-1, there is also a first threaded hole 3-3 for cooperating with the fastening screw 6. In the middle of the middle plate, there is a second threaded hole 3-4.

[0060] The described upper limb connecting chuck 7 is an integrated structure similar to a U shape, including a middle plate and U-shaped thin fins 7-1 and U-shaped thick fins 7-2 on both sides of the middle plate. Among them, the U-shaped thin fins 7-1 are thinner and have better elasticity, while the U-shaped thick fins 7-2 are thicker and have greater rigidity. The distance between the inner surfaces of the two fins is slightly greater than the distance between the outer surfaces of the upper and lower pressing plates of the pressure loading structure 1, so that the upper and lower pressing plates of the pressure loading structure 1 can be inserted between the U-shaped thin fins 7-1 and the U-shaped thick fins 7-2. There is a fourth through hole 7-3 on the U-shaped thin fin 7-1, and a third threaded hole 7-4 corresponding to it on the U-shaped thick fin 7-2. The two holes are coaxial and correspond to the first through holes 1-4 on the upper and lower pressing plates of the pressure loading structure 1. Among them, the diameter of the fourth through hole 7-3 is larger and can accommodate the saddle spring 10. The diameter of the third threaded hole 7-4 is smaller and corresponds to the size of the pre-tightening force adjusting bolt 8 for screwing in the pre-tightening force adjusting bolt 8, and the diameter of the first through hole 1-4 on the upper and lower pressing plates of the pressure loading structure 1 is between the two.

[0061] Specifically, there are 8 positioning pins 4 in total; the robot joint further includes 2 end cover plates 5, which are respectively arranged at the outer ends of the fins on both sides of the lower limb connecting device 3. Through holes are provided in the middle of the end cover plates, corresponding to the first threaded holes 3-3 on the fins on both sides of the lower limb connecting device 3. There are 2 fastening screws 6 in total. The pre-tightening force adjusting bolt 8 is sequentially inserted into the gasket 9, the saddle spring 10, the fourth through hole 7-3, the first through hole 1-4 and the third threaded hole 7-4 to form a bolt-gasket-thin fin-saddle spring-upper and lower pressure plates-thick fin force application structure, realizing the functions of joint position holding or attitude adjustment. There are two limit bolts 11 in total, which are sequentially inserted into the fifth through hole 7-5, the second through hole 1-5 and the fourth threaded hole 7-6 to limit the relative rotation of the pressure loading structure 1 and the upper limb connecting chuck 7.

[0062] Embodiment 1: A single set of robot joints with one-way adjustment function

[0063] A design and usage method of a single set of robot joints with adjustable frictional torque and one-way adjustment function. The specific structure is referred to Figures 1 to 8 . It includes a pressure loading structure 1, a rotating shaft 2, a lower limb connecting device 3, a positioning pin 4, an end cover plate 5, a fastening screw 6, an upper limb connecting chuck 7, a pre-tightening force adjusting bolt 8, a gasket 9, a saddle spring 10, and a limit bolt 11. The specific installation and usage steps are as follows:

[0064] S1: Place the cylindrical rotating shaft 2 in the cylindrical barrel 1-1 of the pressure loading structure 1. The rotating shaft is made of a polymer material with good anti-wear and self-lubricating properties, including nylon, polyimide, polyether ether ketone, and polyoxymethylene. In this embodiment, polyoxymethylene is used for preparation;

[0065] S2: Insert the U-shaped fin structure on the lower limb connecting device 3 from both sides of the pressure loading structure 1, adjust the lower limb connecting device 3 to a suitable position so that the third through hole 3-2 on it corresponds to the blind hole 2-1 on the rotating shaft 2 in the pressure loading structure 1 one by one. Insert all 4 positioning pins 4 into the third through hole 3-2 and the blind hole 2-1. The length of the positioning pin 4 should be greater than the depth of the blind hole 2-1, and at the same time, it should not be greater than the sum of the depth of the blind hole 2-1 and the depth of the third through hole 3-2;

[0066] S3: Press the end cover plate 5 at the corresponding position on the outside of the U-shaped fin on the lower limb connecting device 3, and screw the fastening screw 6 into the first threaded hole 3-3 to prevent the positioning pin 4 from slipping out of the third through hole 3-2, so that there is no relative rotation between the lower limb connecting device 3 and the cylindrical rotating shaft 2;

[0067] S4: Repeat S2 and S3, and install and fix the 4 positioning pins 4 and the cover plate 5 on the other end face of the U-shaped fin of the lower limb connecting device 3 with the fastening screws 6;

[0068] S5: Insert the upper and lower pressure plates of the pressure loading structure 1 into the inner side of the U-shaped fin of the upper limb connecting chuck 7, adjust the position to align the first through hole 1-4 with the fourth through hole 7-3 and the third threaded hole 7-4, and then sequentially insert the pre-tightening force adjusting bolt 8 through the gasket 9, the saddle spring 10, the fourth through hole 7-3, the first through hole 1-4 and the third threaded hole 7-4 to form a bolt-gasket-thin fin-saddle spring-upper and lower pressure plates-thick fin force application structure. At this time, only partially screw the pre-tightening force adjusting bolt 8 into the third threaded hole 7-4 so that the pressure loading structure 1 and the upper limb connecting chuck 7 can still rotate relative to each other for subsequent steps to be implemented;

[0069] S6: Adjust the relative position of the upper and lower pressure plates of the pressure loading structure 1 and the upper limb connecting chuck 7 to align the fifth through hole 7-5, the second through hole 1-5 and the fourth threaded hole 7-6. Insert the two limit bolts 11 sequentially into the fifth through hole 7-5 on the upper limb connecting chuck 7 and the second through hole 1-5 of the pressure loading structure 1, and finally screw them into the fourth threaded hole 7-6 on the upper limb connecting chuck 7 to limit the relative rotation of the pressure loading structure 1 and the upper limb connecting chuck 7;

[0070] S7: According to actual requirements, adjust the depth of the pre-tightening force adjusting bolt 8 screwed into the third threaded hole 7-4, that is, adjust the pressure and friction force applied by the bolt-saddle spring-pressure plate force application structure between the inner surface of the pressure loading structure 1 and the surface of the rotating shaft 2 to meet different rated load requirements, and complete the installation of a single robot joint with a one-way adjustment function. See Figures 6 to 8 ;

[0071] S8: Under the action of an external force equal to or less than the rated load, the joint will remain stationary, that is, the joint is in a position holding state; if an external force greater than the rated load is applied to the joint, a relative rotation along the axis of the rotating shaft 2 can be generated between the rotating shaft 2 and the pressure loading structure 1, driving the same relative rotation of the lower limb connecting device 3 and the upper limb connecting chuck 7, that is, realizing the one-way attitude adjustment of the joint.

[0072] Embodiment 2: Series composite robot joint with two-way adjustment function

[0073] A series composite robot joint with adjustable friction torque and two-way adjustment function and its installation and use method. The specific structure refers to Figures 1 to 5 and Figure 9. It includes a pressure loading structure 1, a rotating shaft 2, a lower limb connecting device 3, a positioning pin 4, an end cover plate 5, a fastening screw 6, an upper limb connecting chuck 7, a pre-tightening force adjusting bolt 8, a gasket 9, a saddle spring 10, and a limit bolt 11. The specific installation and usage steps are as follows:

[0074] S1: Place the cylindrical rotating shaft 2 into the cylindrical barrel 1-1 of the pressure loading structure 1. The rotating shaft is made of a polymer material with good anti-wear and self-lubricating properties, including nylon, polyimide, polyetheretherketone, and polyoxymethylene. In this embodiment, polyoxymethylene is used for preparation;

[0075] S2: Insert the U-shaped fin structure on the lower limb connecting device 3 from both sides of the pressure loading structure 1. Adjust the lower limb connecting device 3 to a suitable position so that the third through hole 3-2 on it corresponds to the blind hole 2-1 on the rotating shaft 2 in the pressure loading structure 1 one by one. Insert all 4 positioning pins 4 into the third through hole 3-2 and the blind hole 2-1. The length of the positioning pin 4 should be greater than the depth of the blind hole 2-1, and at the same time, it should not be greater than the sum of the depth of the blind hole 2-1 and the depth of the third through hole 3-2;

[0076] S3: Press the end cover plate 5 at the corresponding position outside the U-shaped fin on the lower limb connecting device 3, and screw the fastening screw 6 into the first threaded hole 3-3 to prevent the positioning pin 4 from slipping out of the third through hole 3-2, so that there is no relative rotation between the lower limb connecting device 3 and the cylindrical rotating shaft 2;

[0077] S4: Repeat S2 and S3 to install and fix the 4 positioning pins 4 and the cover plate 5 on the other end face of the U-shaped fin on the lower limb connecting device 3 with the fastening screw 6;

[0078] S5: Snap the two upper limb connecting chucks 7 in a groove 7-8 against a groove 7-8 manner. The directions of the two grooves will differ by 90 o , and then use a screw rod of appropriate length to screw it into the threaded hole 7-7. When screwing in, inject sealant between the screw rod and the threaded hole and wait for it to cure to make the two upper limb connecting chucks 7 firmly connected;

[0079] S6: Insert the upper and lower pressure plates of the pressure loading structure 1 assembled in steps S1 - S4 into the inner sides of the U-shaped fins of any one of the upper limb connection chucks 7 assembled in step S. Adjust the position to align the first through hole 1-4 with the fourth through hole 7-3 and the third threaded hole 7-4. Then, sequentially insert the pre-tightening force adjusting bolt 8 through the gasket 9, the saddle spring 10, the fourth through hole 7-3, the first through hole 1-4, and the third threaded hole 7-4 to form a bolt-gasket-thin fin-saddle spring-upper and lower pressure plates-thick fin force application structure. At this time, only partially screw the pre-tightening force adjusting bolt 8 into the third threaded hole 7-4 so that the pressure loading structure 1 and the upper limb connection chuck 7 can still rotate relative to each other for subsequent steps to be implemented;

[0080] S7: Adjust the relative position of the upper and lower pressure plates of the pressure loading structure 1 and the upper limb connection chuck 7 to align the fifth through hole 7-5, the second through hole 1-5, and the fourth threaded hole 7-6. Insert the two limit bolts 11 sequentially into the fifth through hole 7-5 on the upper limb connection chuck 7 and the second through hole 1-5 of the pressure loading structure 1, and finally screw them into the fourth threaded hole 7-6 on the upper limb connection chuck 7 to limit the relative rotation of the pressure loading structure 1 and the upper limb connection chuck 7;

[0081] S8: According to actual requirements, adjust the depth of the pre-tightening force adjusting bolt 8 screwed into the third threaded hole 7-4, that is, adjust the pressure and friction force applied by the bolt-gasket-thin fin-saddle spring-upper and lower pressure plates-thick fin force application structure between the inner surface of the pressure loading structure 1 and the surface of the rotating shaft 2 to meet different rated load requirements, and complete the installation of a single set of joints in the series composite joint with a two-way adjustment function;

[0082] S9: Repeat steps S1 - S4 to complete the installation of the other set of the lower limb connection device 3, the rotating shaft 2, and its supporting components;

[0083] S10: Insert the upper and lower pressure plates of the pressure loading structure 1 assembled in step S9 into the inner sides of the U-shaped fins of the other upper limb connection chuck 7 assembled in step S5. Adjust the position to align the first through hole 1-4 with the fourth through hole 7-3 and the third threaded hole 7-4. Then, sequentially insert the pre-tightening force adjusting bolt 8 through the gasket 9, the saddle spring 10, the fourth through hole 7-3, the first through hole 1-4, and the third threaded hole 7-4 to form a bolt-gasket-thin fin-saddle spring-upper and lower pressure plates-thick fin force application structure. At this time, only partially screw the pre-tightening force adjusting bolt 8 into the third threaded hole 7-4 so that the pressure loading structure 1 and the upper limb connection chuck 7 can still rotate relative to each other for subsequent steps to be implemented;

[0084] S11: Adjust the relative positions of the upper and lower pressure plates of the pressure loading structure 1 and the upper limb connection chuck 7 so that the fifth through-hole 7-5, the second through-hole 1-5, and the fourth threaded hole 7-6 are aligned. Insert the two limit bolts 11 successively into the fifth through-hole 7-5 on the upper limb connection chuck 7 and the second through-hole 1-5 of the pressure loading structure 1, and finally screw them into the fourth threaded hole 7-6 on the upper limb connection chuck 7 to restrict the relative rotation between the pressure loading structure 1 and the upper limb connection chuck 7;

[0085] S12: According to actual requirements, adjust the depth of the pre-tightening force adjusting bolt 8 screwed into the third threaded hole 7-4, that is, adjust the pressure and friction force applied by the bolt-saddle spring-pressure plate force application structure between the inner surface of the pressure loading structure 1 and the surface of the rotating shaft 2 to meet different rated load requirements, and complete the installation of the series-connected composite robot joint with a two-way adjustment function. For details, see Figure 9 ;

[0086] S13: The two upper limb connection chucks 7 assembled in step S5 are coaxial but differ by 90 o , so the two sets of joints installed in step S12 can achieve rotational angle adjustment in two directions and are suitable as joints for the shoulder and waist of a robot, etc. Since the force application structures composed of bolts, gaskets, thin fins, saddle springs, upper and lower pressure plates, and thick fin plates of the two joints are independent of each other, the holding torques of the two joints in two directions can be independently adjusted according to actual rated load requirements. Under the action of an external force equal to or less than the rated load, the joint will remain stationary, that is, the joint is in a position holding state. If an external force greater than the rated load is applied to the joint in different directions, the joint can rotate in the corresponding direction, and finally the two-way attitude adjustment of the joint is achieved.

[0087] The above embodiments only represent the implementation modes of the present invention, but should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those skilled in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A robot joint with adjustable frictional torque, characterized in that, The described robot joint includes a pressure loading structure (1), a rotating shaft (2), a lower limb connecting device (3), a positioning pin (4), a fastening screw (6), an upper limb connecting chuck (7), a pre-tightening force adjusting bolt (8), a gasket (9), a saddle spring (10), and a limit bolt (11); specifically: The main body of the described pressure loading structure (1) is a barrel-shaped cavity (1-1) with an opening on one side, and the rotating shaft (2) is placed inside the barrel-shaped cavity (1-1); The positioning pin (4) is placed on the end face of the rotating shaft (2); The described lower limb connecting device (3) is an integrated structure similar to a U shape, is connected to the rotating shaft (2) through the positioning pin (4), and is installed in cooperation with the fastening screw (6); The described upper limb connecting chuck (7) is an integrated structure similar to a U shape, and is installed in cooperation with the pressure loading structure (1), the gasket (9), the saddle spring (10), and the pre-tightening force adjusting bolt (8).

2. The robot joint with adjustable frictional torque according to claim 1, wherein The described robot joint specifically is: On the opening side of the pressure loading structure (1), an upper side pressing plate (1-2) and a lower side pressing plate (1-3) extend radially outward respectively; first through holes (1-4) are provided on the upper side pressing plate (1-2) and the lower side pressing plate (1-3) for passing through the pre-tightening force adjusting bolt (8); two second through holes (1-5) are provided at the front ends on both sides of the upper side pressing plate (1-2) and the lower side pressing plate (1-3) for placing the limit bolt (11); The rotating shaft (2) is cylindrical, and blind holes (2-1) are symmetrically provided at both end faces for placing the positioning pin (4); The described lower limb connecting device (3) includes a middle plate and U-shaped fin structures (3-1) located on both sides of the middle plate; four third through holes (3-2) are provided on each of the two side fins (3-1), and the positioning pin (4) passes through the third through holes (3-2) and enters the blind holes (2-1), so that the lower limb connecting device (3) and the rotating shaft (2) do not rotate relative to each other; one first threaded hole (3-3) is also provided on each of the two side fins (3-1) for cooperating with the fastening screw (6); a second threaded hole (3-4) is provided in the middle of the middle plate as a reserved interface for the robot limb component; The upper limb connection chuck (7) described above includes a middle plate, and U-shaped thin fins (7-1) and U-shaped thick fins (7-2) located on both sides of the middle plate. The upper pressing plate (1-2) and the lower pressing plate (1-3) are inserted between the U-shaped thin fins (7-1) and the U-shaped thick fins (7-2). A fourth through hole (7-3) is provided on the U-shaped thin fin (7-1), and a third threaded hole (7-4) is provided on the U-shaped thick fin (7-2). The two holes are coaxial and correspond to the position of the first through hole (1-4) during installation. The diameter of the fourth through hole (7-3) is larger for placing the saddle spring (10), and the diameter of the third threaded hole (7-4) is smaller for screwing in the pre-tightening force adjusting bolt (8). On both sides of the U-shaped thin fin (7-1) near the middle plate, there is a fifth through hole (7-5) respectively. At the corresponding positions on both sides of the U-shaped thick fin (7-2) near the middle plate, there is a fourth threaded hole (7-6) respectively. The limit bolt (11) passes through the fifth through hole (7-5), the second through hole (1-5) and the fourth threaded hole (7-6) in sequence to limit the relative rotation between the pressure loading structure (1) and the upper limb connection chuck (7). A fifth threaded hole (7-7) is provided at the middle position of the middle plate as a reserved interface with the robot limb component. The middle plate is provided with a groove (7-8) for positioning when two upper limb connection chucks (7) are interconnected. The pre-tightening force adjusting bolt (8) passes through the gasket (9), the saddle spring (10), the fourth through hole (7-3), the first through hole (1-4) and the third threaded hole (7-4) in sequence, and is used to adjust the pressure and friction force between the barrel-shaped cavity (1-1) and the rotating shaft (2), so as to realize the function of maintaining the joint position or adjusting the posture.

3. The robot joint with adjustable frictional torque according to claim 2, wherein The groove (7-8) on the middle plate of the upper limb connecting chuck (7) is locally removed near the U-shaped thick fin (7-2) so that the groove (7-8) is square, and the fifth threaded hole (7-7) is located at the center of the directional groove (7-8). Ensure that the two fifth threaded holes (7-7) are exactly coaxial when the two upper limb connecting chucks (7) are interconnected, and then connect the two upper limb connecting chucks (7) through a threaded rod, but there is a relative rotation angle of 90 o degrees between them, realizing the movement of the joint in two rotational degrees of freedom.

4. A robot joint with adjustable frictional torque according to claim 2, characterized in that, There are two limit bolts (11) in total, which pass through the fifth through hole (7-5) on the upper limb connection chuck (7), the second through hole (1-5) of the pressure loading structure (1) and the fourth threaded hole (7-6) on the upper limb connection chuck (7) in sequence to limit the relative rotation between the pressure loading structure (1) and the upper limb connection chuck (7).

5. A robot joint with adjustable frictional torque according to claim 2, characterized in that, The upper pressing plate (1-2) and the lower pressing plate (1-3) in the pressure loading structure (1) are flush. The diameter of the first through hole (1-4) in the pressure loading structure (1) is between the fourth through hole (7-3) and the third threaded hole (7-4) of the upper limb connection chuck (7).

6. The robot joint with adjustable frictional torque according to claim 2, characterized in that, The robot joint also includes two end cover plates (5), which are respectively arranged at the outer ends of the fins on both sides of the lower limb connection device (3). There is a through hole in the middle of the end cover plate, which corresponds to the first threaded hole (3-3) on the fins on both sides of the lower limb connection device (3) to prevent the positioning pin (4) from sliding out axially.

7. A robot joint with adjustable frictional torque according to claim 2, characterized in that, The length of the positioning pin (4) is greater than the depth of the blind hole (2-1), and at the same time, it cannot be greater than the sum of the depth of the blind hole (2-1) and the depth of the third through hole (3-2).

8. A method for using a robot joint with adjustable frictional torque according to any one of claims 1-7, characterized in that, When including the following steps: S1: Place the cylindrical rotating shaft (2) into the barrel-shaped cavity (1-1) of the pressure loading structure (1); S2: Insert the U-shaped fin structure on the lower limb connecting device (3) from both sides of the pressure loading structure (1), and insert the positioning pin (4) into the third through hole (3-2) and the blind hole (2-1). S3: Press the end cover plate (5) against the outside of the U-shaped fin on the lower limb connecting device (3), and screw the fastening screw (6) into the first threaded hole (3-3) so that the lower limb connecting device (3) and the cylindrical rotating shaft (2) have no relative rotation. S4: Repeat S2 and S3 to install and fix the positioning pin (4) and the end cover plate (5) on the other end face of the U-shaped fin of the lower limb connecting device (3) with the fastening screw (6). S5: Installation of the upper limb connecting chuck (7) under the single one-way adjustment and two-way adjustment functions (1) Installation and use of a single upper limb connecting chuck (7) with a one-way adjustment function S5.1: Insert the upper and lower pressure plates of the pressure loading structure (I) into the inner side of the U-shaped fin of the upper limb connecting chuck (7), and sequentially pass the pre-tightening force adjusting bolt (8) through the gasket (9), the saddle spring (10), the fourth through hole (7-3), the first through hole (1-4) and the third threaded hole (7-4). At this time, only partially screw the pre-tightening force adjusting bolt (8) into the third threaded hole (7-4) so that the pressure loading structure (1) and the upper limb connecting chuck (7) can still rotate relative to each other. S5.2: Adjust the relative position of the upper and lower pressure plates of the pressure loading structure (1) and the upper limb connecting chuck (7), and sequentially insert the two limit bolts (11) into the fifth through hole (7-5) on the upper limb connecting chuck (7) and the second through hole (1-5) of the pressure loading structure (1), and finally screw them into the fourth threaded hole (7-6) on the upper limb connecting chuck (7) to limit the relative rotation of the pressure loading structure (1) and the upper limb connecting chuck (7). S5.3: According to actual requirements, adjust the depth of the pre-tightening force adjusting bolt (8) screwed into the third threaded hole (7-4), that is, adjust the pressure and friction force applied by the adjusting bolt-saddle spring-pressure plate force application structure between the inner surface of the pressure loading structure (1) and the surface of the rotating shaft (2) to adapt to different rated load requirements, and complete the installation of a single robot joint with a one-way adjustment function. S5.4: Under the action of an external force equal to or less than the rated load, the joint will remain stationary, that is, the joint is in a position holding state; if an external force greater than the rated load is applied to the joint, relative rotation along the axis direction of the rotating shaft (2) can be generated between the rotating shaft (2) and the pressure loading structure (1), driving the same relative rotation of the lower limb connecting device (3) and the upper limb connecting chuck (7), that is, realizing the one-way attitude adjustment of the joint. (2) Installation and use of two upper limb connecting chucks (7) with two-way adjustment functions S5.5: Snap the two upper limb connection chucks (7) into each other with the grooves (7-8) facing each other. The directions of the two grooves differ by 90 o , and screw the screw into the threaded hole (7-7) to connect the two upper limb connection chucks (7); S5.6: Insert the upper and lower pressure plates of the pressure loading structure (1) assembled in steps S1 - S4 into the inner side of the U - shaped fins of any one of the upper limb connection chucks (7) assembled in step S5.5, align the first through - hole (1 - 4) with the fourth through - hole (7 - 3) and the third threaded hole (7 - 4). Then, insert the pre - tightening force adjusting bolt (8) successively through the gasket (9), the saddle spring (10), the fourth through - hole (7 - 3), the first through - hole (1 - 4) and the third threaded hole (7 - 4). At this time, only partially screw the pre - tightening force adjusting bolt (8) into the third threaded hole (7 - 4) so that the pressure loading structure (1) and the upper limb connection chuck (7) can still rotate relative to each other; S5.7: Adjust the relative position of the upper and lower pressure plates of the pressure loading structure (1) and the upper limb connection chuck (7) to align the fifth through - hole (7 - 5), the second through - hole (1 - 5) and the fourth threaded hole (7 - 6). Insert the two limit bolts (11) successively into the fifth through - hole (7 - 5) on the upper limb connection chuck (7) and the second through - hole (1 - 5) of the pressure loading structure (1), and finally screw them into the fourth threaded hole (7 - 6) on the upper limb connection chuck (7) to limit the relative rotation between the pressure loading structure (1) and the upper limb connection chuck (7); S5.8: According to the actual requirements, adjust the depth of the pre - tightening force adjusting bolt (8) screwed into the third threaded hole (7 - 4) to meet different rated load requirements, and complete the installation of one of the two joints with two - way adjustment functions; S5.9: Repeat steps S1 - S4 to complete the installation of another set of lower limb connection devices (3), the rotating shaft (2) and their supporting components; S5.10: Insert the upper and lower pressure plates of the pressure loading structure (1) assembled in step S5.9 into the inner side of the U - shaped fins of the other upper limb connection chuck (7) assembled in step S5.

5. Insert the pre - tightening force adjusting bolt (8) successively through the gasket (9), the saddle spring (10), the fourth through - hole (7 - 3), the first through - hole (1 - 4) and the third threaded hole (7 - 4). At this time, only partially screw the pre - tightening force adjusting bolt (8) into the third threaded hole (7 - 4) so that the pressure loading structure (1) and the upper limb connection chuck (7) can still rotate relative to each other; S5.11: Adjust the relative position of the upper and lower pressure plates of the pressure loading structure (1) and the upper limb connection chuck (7) to align the fifth through - hole (7 - 5), the second through - hole (1 - 5) and the fourth threaded hole (7 - 6). Insert the two limit bolts (11) successively into the fifth through - hole (7 - 5) on the upper limb connection chuck (7) and the second through - hole (1 - 5) of the pressure loading structure (1), and finally screw them into the fourth threaded hole (7 - 6) on the upper limb connection chuck (7) to limit the relative rotation between the pressure loading structure (1) and the upper limb connection chuck (7); S5.12: According to the actual requirements, adjust the depth of the pre - tightening force adjusting bolt (8) screwed into the third threaded hole (7 - 4) to adapt to different rated load requirements and complete the installation of the series - type composite joint.

9. The method of using a robot joint with adjustable frictional torque according to claim 8, characterized in that, In S5.5, sealant is injected between the screw and the threaded hole (7-7), and after it cures, the two upper limb connection chucks (7) are firmly connected.

10. The usage method of a robot joint with adjustable frictional torque according to claim 8, characterized in that In S5.12, the series compound joint has a two-way adjustment function to achieve the adjustment of the rotation angle in two directions; Independently adjust the holding torques of the two robot joints in two directions according to the actual rated load requirements. Under the action of an external force equal to or less than the rated load, the robot joints are in a position holding state; if an external force greater than the rated load is applied to the robot joints in different directions, the robot joints will rotate in the corresponding directions; ultimately, the two-way attitude adjustment of the robot joints is achieved.

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