Adjustable mechanical joint with position keeping function and use method
By adopting the matching of tooth-like structures in mechanical joints and the use of return springs, the frictional contradiction between existing mechanical joints during position maintenance and posture adjustment is solved, and a high load and low friction joint design is achieved, which improves the stability and adjustment convenience of the joint.
Patent Information
- Application Number
- CN202510592085.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-09
- Publication Date
- 2025-06-20
AI Technical Summary
When existing mechanical joints need to maintain position and adjust posture at the same time, there is friction contradiction, resulting in poor movement and severe wear and failure after long-term use.
A mechanical joint with position holding and motion adjustment functions is designed, and the mating of a tooth-like structure and the use of a return spring are adopted. Position holding is achieved through the mating of a tooth-like structure, and position adjustment is achieved through the pressure adjustment of the return spring, reducing friction resistance.
It improves the load bearing capacity of mechanical joints, reduces friction losses, and achieves convenience of position holding and posture adjustment, avoids joint looseness caused by wear.
Smart Images
Figure CN120170790A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of robots and relates to a mechanical joint with position holding and adjusting functions and a usage method thereof. Background Art
[0002] A mechanical joint is an important connecting part between the movable parts of a robot or a doll, and is responsible for the functions of posture or position holding and adjustment. Conventional mechanical joints generally perform position holding based on the friction locking principle. Therefore, there must be sufficient friction force between their friction pairs to ensure that the joint does not become loose under the action of external loads. However, when posture adjustment is required, it is desired that the friction force between these friction pairs is relatively small, so as to ensure smooth movement and avoid wear of the friction pairs after repeated use, resulting in functional failure. Obviously, the above requirements are contradictory and need to be optimized and designed to be effectively solved. At the same time, in the specific application scenario of the simulation doll joint involved in the examples of the present invention, the outside of the joint is also coated with a skin-like tissue, and the operation of the joint can only be performed blindly by touch, and the coating layer cannot be damaged during use, which further improves the design requirements and difficulties.
[0003] The existing joint designs can be roughly divided into two categories: The first category uses ordinary bolt connections to achieve the function of position holding by increasing the pre-tightening force, increasing the friction coefficient of the friction pair, etc. However, it has the problem that the joint friction pair wears severely after repeated use, eventually leading to joint loosening. At the same time, when the external load is large, a sufficiently large pre-tightening force must be applied to ensure no loosening, but this also results in a large driving force required for position adjustment, making the operation more difficult. The second type of structure mainly uses elastic elements such as springs to apply a normal pressure to the friction parts to form sufficient friction force to achieve the function of position holding. Due to the self-adjustability of the elastic elements, this type of joint can still provide sufficient pressure and friction force to achieve position holding after the joint friction pair wears, but this type of joint generally has a low load-bearing capacity and also fails to solve the contradiction between the high friction force requirement during position holding and the low friction resistance during position adjustment.
[0004] In view of the deficiencies of the existing joint technology and the special requirements of the simulation doll joint, the present invention provides a mechanical joint design with position holding and motion adjustment functions. Summary of the Invention
[0005] In view of the deficiencies of the prior art, the present invention provides a new mechanical joint design, which solves the contradictions and problems faced by the joints designed based on the friction locking principle, effectively realizes the position holding function while using simple mechanism movement to reduce the position adjustment resistance, and avoids wear failure caused by long-term and frequent position adjustments.
[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:
[0007] An adjustable mechanical joint with a position-holding function, the adjustable mechanical joint includes an upper limb connecting device 1, a square rotating shaft 2, a lower limb connecting device 3, a spring pressure adjustment button 4, a limit buckle 5, an axial return spring 6, and an axial positioning spring 7. Specifically:
[0008] The upper end of the upper limb connecting device 1 is provided with a threaded rod 1-1 for connecting with the doll limb component; the lower end of the upper limb connecting device 1 is a sheet-like connecting structure 1-2, on which there is a square hole 1-3 for connecting with the square rotating shaft 2.
[0009] The square rotating shaft 2 is located in the middle position of the entire mechanical joint and passes through the lower square hole 1-3 in the upper limb connecting device 1, and the two are precisely matched to ensure the stability and reliability of the structure; because it is a square shaft and a square hole, there is no circumferential relative rotation between the square rotating shaft 2 and the upper limb connecting device 1, and only relative axial movement can occur.
[0010] The upper half of the lower limb connecting device 3 is a U-shaped fork arm structure 3-1, and the U-shaped fork arm 3-1 is provided with a toothed through hole 3-2 for circumferentially limiting the spring pressure adjustment button 4; there is a circumferential rotation amplitude expansion groove 3-3 at the bottom of the U-shaped fork arm structure 3-1 for increasing the circumferential rotation amplitude of the upper limb connecting device 1, and at the same time, it can also limit the axial movement of the upper limb connecting device 1; the lower part of the lower limb connecting device 3 is a threaded rod 3-4 for connecting with the doll limb component, and at the same time, the threaded rod and the mating nut are used to fix the limit buckle 5.
[0011] There are 2 spring pressure adjustment buttons 4 in total, symmetrically arranged on the outside of the U-shaped fork arm structure 3-1 of the lower limb connecting device 3; one end of the spring pressure adjustment button 4 is a pressurizing arc surface 4-1 for applying axial pressure to the axial return spring 6, and the arc surface design can also avoid damaging the imitation skin tissue covering it; the spring pressure adjustment button 4 is provided with a toothed structure 4-2, which cooperates with the toothed through hole 3-2 on the U-shaped fork arm 3-1 to limit the circumferential rotation of the joint; a chamfer is provided at the edge of the toothed structure 4-2, so that the toothed structure 4-2 can more easily slide into the toothed through hole 3-2 of the U-shaped fork arm of the lower limb connecting device under the restoring force of the return spring 6; the spring pressure adjustment button 4 is provided with a columnar transition structure 4-3 for cooperating with the limit buckle 5; a square blind hole 4-4 is provided inside the columnar transition structure for connecting and positioning with the square rotating shaft 2.
[0012] The described limit buckle 5 is an overall U-shaped fork arm structure. Semi-circular grooves 5-1 are provided on both sides of the U-shaped fork arms, forming a mating relationship with the columnar transition structure 4-3 in the spring pressure adjustment button 4, enabling the spring pressure adjustment button 4 to rotate relying on the inner wall surface of the semi-circular groove 5-1. At the same time, the opening radius of the semi-circular groove 5-1 is smaller than the outer diameter of the toothed structure 4-2 in the spring pressure adjustment button 4, thereby preventing the spring pressure adjustment button 4 from sliding out axially under the elastic force of the return spring 6. The limit buckle 5 has notches 5-2 opened on both sides at the bottom, corresponding to the circumferential rotation amplitude expansion grooves 3-3 in the lower limb connection device 3, playing a role in increasing the circumferential rotation amplitude of the upper limb connection device 1. The limit buckle 5 has a bolt hole 5-3 opened in the middle at the bottom, allowing the lower part threaded rod 3-4 of the lower limb connection device 3 to pass through it for bolt fixation.
[0013] There are 2 axial return springs 6 in total, symmetrically distributed on both sides of the sheet-like connection structure 1-2 in the upper limb connection device 1, and the square rotating shaft 2 passes through the spring 6. One end of the axial return spring 6 abuts against the side surface of the sheet-like connection structure 1-2 in the upper limb connection device 1, and the other end abuts against the inner end surface of the columnar transition structure 4-3 in the spring pressure adjustment button 4, pressing the spring pressure adjustment button 4 axially towards both sides against the limit buckle 5 to maintain the position.
[0014] There are 2 axial positioning springs 7 in total, symmetrically distributed at both ends of the square rotating shaft 2, preventing the square rotating shaft 2 from sliding unrestrictedly axially.
[0015] The installation process of an adjustable mechanical joint with a position holding function is as follows:
[0016] Place the positioning spring 7 into the square blind hole 4-4 in the left spring pressure adjustment button 4. Then, insert the left end of the square rotating shaft 2 successively through the return spring 6 and the square blind hole 4-4 in the spring pressure adjustment button 4 to compress the positioning spring 7. Insert the right end of the square rotating shaft 2 from the left side of the U-shaped fork arm of the lower limb connecting device 3 into the toothed through hole 3-2, then continue to insert it into the square hole 1-3 of the upper limb connecting device 1, and finally pass through the toothed through hole 3-2 on the right side of the U-shaped fork arm of the lower limb connecting device 3. Insert another return spring 6 through the right end of the square rotating shaft 2, then place another positioning spring 7 into the square blind hole 4-4 in the left spring pressure adjustment button 4, and align the square blind hole 4-4 of the other spring pressure adjustment button 4 with the right end of the square rotating shaft 2 and press it in. Align the bolt hole of the limit buckle 5 with the threaded rod 3-4 of the lower limb connecting device 3, press the lower limb connecting device 3 upward along the threaded rod 3-4 from bottom to top, and at the same time, press the spring pressure adjustment buttons 4 on the left and right sides with your hand, so that the fork arms on both sides of the limit buckle 5 press the toothed structure 4-2 on the spring pressure adjustment button 4 at the same time. Screw the nut onto the threaded rod 3-4 of the lower limb connecting device 3 to closely fit the limit buckle 5 with the lower limb connecting device 3, completing the installation and fixation of the entire mechanical joint.
[0017] The usage process of an adjustable mechanical joint with a position holding function is as follows:
[0018] In the position holding state, under the action of the elastic force of the return springs 6 pressing on both sides of the sheet-like connecting structure 1-2 of the upper limb connecting device 1, the spring pressure adjustment buttons 4 on the left and right sides are pushed outwards. However, the U-shaped fork arms on both sides of the limit buckle 5 will restrict the spring pressure adjustment buttons 4 from slipping outwards, so that the toothed structure 4-2 of the spring pressure adjustment button 4 just forms a fit with the toothed through hole 3-2 on the U-shaped fork arm of the lower limb connecting device 3, realizing locking and restricting relative rotation of each component, thereby keeping the relative position and posture of the entire doll limb joint unchanged. This state is called the position holding state, and can also be called the position locking state, posture holding state or posture locking state.
[0019] When position and posture adjustment are required, compress the spring pressure adjustment buttons 4 on the left and right sides towards the middle with your hand. The return springs 6 and positioning springs 7 are compressed, so that the toothed structure 4-2 of the spring pressure adjustment button 4 slides out of the toothed through hole 3-2 on the lower limb connecting device 3, completing unlocking. At this time, the upper limb connecting device 1 or the lower limb connecting device 3 can be rotated and adjusted. This state is called the position adjustment state or posture adjustment state.
[0020] Hold the position of the spring pressure adjustment button 4, rotate the upper limb connecting device 1 or the lower limb connecting device 3 to adjust the angle to the set angle, then remove the force applied to the spring pressure adjustment buttons 4 on both left and right sides. Utilize the restoring forces of the reset springs 6 and the detent springs 7 on both sides to move the toothed structure 4-2 of the spring pressure adjustment button 4 towards both sides. The chamfers on the toothed structure 4-2 can induce the toothed structure to slide into the toothed through holes 3-2 on the U-shaped fork arms of the lower limb connecting device 3, so that the two re-form a mating lock, and the mechanical joint returns to the position holding state.
[0021] Compared with the prior art, the present invention has the following beneficial effects:
[0022] (1) The present invention realizes position holding through the cooperation of toothed structures in the mechanical joint. The load that can be borne is greatly improved compared with the mechanical joint locked by friction. At the same time, the wear caused by repeated use of the joint is reduced, effectively solving the problem of joint loosening caused by wear during long-term repeated use.
[0023] (2) The present invention unlocks the toothed structure by applying an axial pressure to the reset spring, and can realize the conversion of the mechanical joint from the position holding state to the position adjustment state. The reset spring does not bear the torque required for joint position holding, so a spring with a smaller stiffness can be selected, greatly reducing the pressure that needs to be applied to the spring pressure adjustment button. At the same time, in the position adjustment state, the joint angle adjustment has almost no frictional resistance and requires very little driving force, thus effectively solving the contradiction between the joint driving force and the bearing capacity, significantly improving the convenience of joint adjustment, and also avoiding the risk of fracture failure of the doll joint and limb components due to excessive force.
[0024] (3) For the application of this example in the simulation doll joint, the adjustable position holding mechanical joint of the present invention is designed and optimized specifically to adapt to the inside of the doll, ensuring that it will not damage the external tissue structure during joint movement and adjustment, and is also convenient to operate when buried inside other materials. The precise joint design ensures smooth and fluent movement, and at the same time, the simple structure and reliable mechanical locking design ensure the economy, durability and stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 is an exploded schematic view of the structure of the present invention;
[0026] Figure 2 is a schematic view of the upper limb connecting device;
[0027] Figure 3 is a schematic view of the square rotating shaft;
[0028] Figure 4 is a schematic view of the lower limb connecting device;
[0029] Figure 5 Schematic diagram of the spring pressure adjustment button
[0030] Figure 6 Three-dimensional view of the spring pressure adjustment button
[0031] Figure 7 Schematic diagram of the limit buckle
[0032] Figure 8 Schematic diagram of the three-dimensional structure of the present invention (position locked state)
[0033] Figure 9 Front view and cross-sectional view of the present invention when in the position locked state
[0034] Figure 10 Schematic diagram of the three-dimensional structure of the present invention (position adjustment state)
[0035] Figure 11 (a) Front view and cross-sectional view of the present invention when in the position adjustment state Figure 11 (b) is Figure 11 Cross-sectional view A-A in (a)
[0036] In the figure: 1 is the upper limb connecting device, 2 is the square rotating shaft, 3 is the lower limb connecting device, 4 is the spring pressure adjustment button, 5 is the limit buckle, 6 is the axial return spring, 7 is the axial positioning spring, 1-1 is the threaded rod, 1-2 is the sheet-like connecting structure, 1-3 is the square hole, 3-1 is the U-shaped fork arm structure, 3-2 is the toothed through hole, 3-3 is the circumferential rotation amplitude expansion groove, 3-4 is the threaded rod, 4-1 is the pressurizing arc surface, 4-2 is the toothed positioning spline, 4-3 is the positioning square hole, 4-4 is the square blind hole, 5-1 is the semi-circular card slot, 5-2 is the notch, 5-3 is the bolt hole Detailed implementation mode
[0037] 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 in conjunction with the accompanying drawings of the embodiments of the present invention
[0038] An adjustable mechanical joint with a position holding function, the specific structure is as shown in Figures 1 to 10 It includes an upper limb connecting device 1, a square rotating shaft 2, a lower limb connecting device 3, a spring pressure adjustment button 4, a limit buckle 5, an axial return spring 6, and an axial positioning spring 7. Specifically
[0039] The upper end of the described upper limb connecting device 1 is provided with a threaded rod 1-1 for connecting with the limb component of the doll; the lower end of the upper limb connecting device 1 is a sheet-like connecting structure 1-2, on which there is a square hole 1-3 for connecting with the square rotating shaft 2.
[0040] The described square rotating shaft 2 is located at the middle position of the entire mechanical joint and passes through the lower square hole 1-3 in the upper limb connecting device 1, and the two are precisely matched to ensure the stability and reliability of the structure; due to the square shaft and square hole, there is no circumferential relative rotation between the square rotating shaft 2 and the upper limb connecting device 1, and only relative axial movement can occur.
[0041] The upper half of the described lower limb connecting device 3 is a U-shaped fork arm structure 3-1, and the U-shaped fork arm 3-1 is provided with a toothed through hole 3-2 for circumferentially limiting the spring pressure adjustment button 4; at the bottom of the U-shaped fork arm structure 3-1, there is a circumferential rotation amplitude expansion groove 3-3 for increasing the circumferential rotation amplitude of the upper limb connecting device 1 and also for restricting the axial movement of the upper limb connecting device 1; the lower part of the lower limb connecting device 3 is a threaded rod 3-4 for connecting with the limb component of the doll, and at the same time, the threaded rod and the mating nut are used to fix the limit buckle 5.
[0042] There are 2 described spring pressure adjustment buttons 4, symmetrically arranged on the outside of the U-shaped fork arm structure 3-1 of the lower limb connecting device 3; one end of the spring pressure adjustment button 4 is a pressurizing arc surface 4-1 for applying axial pressure to the axial return spring 6, and the arc surface design can also avoid damaging the artificial skin tissue covering it; the spring pressure adjustment button 4 is provided with a toothed structure 4-2, which cooperates with the toothed through hole 3-2 on the U-shaped fork arm 3-1 to limit the circumferential rotation of the joint; a chamfer is provided at the edge of the toothed structure 4-2, so that the toothed structure 4-2 can more easily slide into the toothed through hole 3-2 of the U-shaped fork arm of the lower limb connecting device under the restoring force of the return spring 6; the spring pressure adjustment button 4 is provided with a columnar transition structure 4-3 for cooperating with the limit buckle 5; a square blind hole 4-4 is provided inside the columnar transition structure for connecting and positioning with the square rotating shaft 2.
[0043] The described limit snap 5 is of an overall U-shaped fork arm structure. Semi-circular clamping grooves 5-1 are provided on both sides of the U-shaped fork arms, forming a mating relationship with the columnar transition structure 4-3 in the spring pressure adjustment button 4, enabling the spring pressure adjustment button 4 to rotate relying on the inner wall surface of the semi-circular clamping groove 5-1. At the same time, the opening radius of the semi-circular clamping groove 5-1 is smaller than the outer diameter of the toothed structure 4-2 in the spring pressure adjustment button 4, thereby preventing the spring pressure adjustment button 4 from sliding out axially under the elastic force of the return spring 6. The limit snap 5 has notches 5-2 opened on both sides at the bottom, corresponding to the circumferential rotation amplitude expansion grooves 3-3 in the lower limb connecting device 3, serving to increase the circumferential rotation amplitude of the upper limb connecting device 1. The limit snap 5 has a bolt hole 5-3 opened in the middle at the bottom, allowing the lower threaded rod 3-4 of the lower limb connecting device 3 to pass through it for bolt fixation.
[0044] There are 2 axial return springs 6 in total, symmetrically distributed on both sides of the sheet-like connecting structure 1-2 in the upper limb connecting device 1, and the square rotating shaft 2 passes through the spring 6. One end of the axial return spring 6 abuts against the side surface of the sheet-like connecting structure 1-2 in the upper limb connecting device 1, and the other end abuts against the inner end surface of the columnar transition structure 4-3 in the spring pressure adjustment button 4, pressing the spring pressure adjustment button 4 axially towards both sides against the limit snap 5 to maintain the position.
[0045] There are 2 axial positioning springs 7 in total, symmetrically distributed at both ends of the square rotating shaft 2, preventing the square rotating shaft 2 from sliding unrestrictedly axially.
[0046] The specific installation and adjustment steps of this embodiment are as follows:
[0047] S1: Place the positioning spring 7 in the square blind hole 4-4 in the left spring pressure adjustment button 4, and then sequentially pass the left end of the square rotating shaft 2 through the return spring 6 and the square blind hole 4-4 in the spring pressure adjustment button 4, pressing the positioning spring 7.
[0048] S2: Pass the right end of the square rotating shaft 2 through the toothed through hole 3-2 on the left side of the U-shaped fork arm of the lower limb connecting device 3, then continue to pass it through the square hole 1-3 of the upper limb connecting device 1, and finally pass it through the toothed through hole 3-2 on the right side of the U-shaped fork arm of the lower limb connecting device 3.
[0049] S3: Insert another reset spring 6 into the right end of the square rotating shaft 2. Then, place another such clamping spring 7 into the square blind hole 4-4 in the left spring pressure adjustment button 4. Align the square blind hole 4-4 of the other spring pressure adjustment button 4 with the right end of the square rotating shaft 2 and press it in to compress the clamping spring 7 tightly.
[0050] S4: Align the bolt hole of the limit buckle 5 with the threaded rod 3-4 of the lower limb connecting device 3. Press the lower limb connecting device 3 upward along the threaded rod 3-4 from bottom to top. At the same time, press the spring pressure adjustment buttons 4 on the left and right sides with your hand, so that the fork arms on both sides of the limit buckle 5 press the toothed structures 4-2 on the spring pressure adjustment buttons 4 simultaneously.
[0051] S5: Screw the nut onto the threaded rod 3-4 of the lower limb connecting device 3 to closely fit the limit buckle 5 and the lower limb connecting device 3, completing the installation and fixation of the entire mechanical joint. The installed joint as a whole is as shown in Figure 8 shown, and the relative position relationship of each component inside is as shown in Figure 9 shown. At this time, the toothed structure 4-2 on the spring pressure adjustment button 4 tightly cooperates with the toothed through hole 3-2 on the right side of the U-shaped fork arm of the lower limb connecting device 3 to complete circumferential positioning, that is, the joint is in the position holding state as shown in Figure 8 shown.
[0052] S6: Compress the spring pressure adjustment buttons 4 on the left and right sides toward the middle with your hand. The reset spring 6 and the clamping spring 7 are compressed, causing the toothed structure 4-2 on the spring pressure adjustment button 4 to slide out of the toothed through hole 3-2 on the lower limb connecting device 3, completing the unlocking. At this time, the overall state of the joint is as shown in Figure 10 shown, and the relative position relationship of each component inside is as shown in Figure 11 shown. At this time, the upper limb connecting device 1 or the lower limb connecting device 3 can be rotated and adjusted.
[0053] S7: Hold the position of the spring pressure adjustment buttons 4. Rotate the upper limb connecting device 1 or the lower limb connecting device 3 to adjust the angle to the set angle, then remove the force applied to the spring pressure adjustment buttons 4 on the left and right sides. Utilize the restoring force of the reset springs 6 and the clamping springs 7 on both sides to make the toothed structure 4-2 on the spring pressure adjustment button 4 move toward both sides. The chamfer on the toothed structure 4-2 can induce the toothed structure to slide into the toothed through hole 3-2 on the U-shaped fork arm of the lower limb connecting device 3, enabling the two to form a mating lock again, and the mechanical joint returns to the position holding state as shown in Figure 8 shown.
[0054] It should be noted that the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.
[0055] Unless otherwise defined, the technical terms or scientific terms used in this disclosure should have the ordinary meaning understood by those of ordinary skill in the art to which this disclosure belongs. The words such as "including" or "comprising" used in this disclosure mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. "Upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.
Claims
1. An adjustable mechanical joint with a position-holding function, characterized in that: The adjustable mechanical joint comprises an upper limb connection device (1), a square rotating shaft (2), a lower limb connection device (3), a spring pressure adjustment button (4), a limit buckle (5), an axial return spring (6), and an axial locking spring (7); The upper end structure of the upper limb connection device (1) is connected to the limb parts of the puppet, and the lower end structure is connected to the square rotating shaft (2); The upper part of the lower limb connection device (3) is a U-shaped fork arm structure (3-1), and the U-shaped fork arm structure (3-1) is provided with a tooth-shaped through hole (3-2) for circumferentially limiting the spring pressure adjustment button (4); the lower structure of the lower limb connection device (3) is connected to the limb parts of the puppet, and the lower structure is used to fix the limit buckle (5); There are two spring pressure adjustment buttons (4) symmetrically arranged on the outside of the U-shaped fork arm structure (3-1) of the lower limb connection device (3), used to apply axial pressure to the axial return spring (6), and used in conjunction with the limit buckle (5); the spring pressure adjustment button (4) is provided with a square blind hole (4-4) for connection and positioning with the square rotating shaft (2); The limit buckle (5) is a U-shaped fork arm structure, and the tops of the U-shaped forks on both sides cooperate with the middle structure of the spring pressure adjustment button (4); the limit buckle (5) has notches (5-2) on both sides of the bottom, corresponding to the circumferential rotation amplitude expansion slots (3-3) in the lower limb connection device (3); the limit buckle (5) has a bolt hole (5-3) in the middle of the bottom, which is threadedly connected to the lower structure of the lower limb connection device (3); There are two axial return springs (6) symmetrically distributed on both sides of the lower end structure in the upper limb connection device (1), and the square rotating shaft (2) passes through the axial return springs (6); There are two axial retaining springs (7) symmetrically distributed at both ends of the square rotating shaft (2) to prevent the square rotating shaft (2) from sliding unrestrictedly along the axial direction.
2. The adjustable mechanical joint with position holding function according to claim 1, characterized in that: The upper end structure of the upper limb connection device (1) is a threaded rod (1-1) which is connected to the limb parts of the puppet through the threaded rod (1-1); the lower end structure of the upper limb connection device (1) is a sheet-like connection structure (1-2) which is provided with a square hole (1-3) which is connected to the square rotating shaft (2).
3. The adjustable mechanical joint with position holding function according to claim 1, characterized in that: The square rotating shaft (2) is located in the middle of the entire mechanical joint and passes through the lower square hole (1-3) in the upper limb connecting device (1). The two are precisely matched; and there is no circumferential relative rotation between the square rotating shaft (2) and the upper limb connecting device (1), and only axial relative movement can be generated.
4. The adjustable mechanical joint with position holding function according to claim 1, characterized in that: The bottom of the U-shaped fork arm structure (3-1) is provided with a circumferential rotation range expansion slot (3-3), which increases the circumferential rotation range of the upper limb connection device (1) and limits the axial movement of the upper limb connection device (1); the lower structure of the lower limb connection device (3) is a threaded rod (3-4), which is connected to the puppet's limb parts through the threaded rod (3-4), and the threaded rod (3-4) is used to pass through the bolt hole (5-3) and is matched with a nut to achieve the fixation of the limit buckle (5).
5. The adjustable mechanical joint with position holding function according to claim 2, characterized in that: The outer end of the spring pressure regulating button (4) is a pressurizing arc surface (4-1), the inner end is provided with a toothed structure (4-2), and the middle part is provided with a columnar transition structure (4-3), which is used in conjunction with a limit buckle (5); specifically: The toothed structure (4-2) cooperates with the toothed through hole (3-2) on the U-shaped fork arm 3-1 to limit the circumferential rotation of the joint; the columnar transition structure (4-3) is used in conjunction with the limiting buckle (5), and the square blind hole (4-4) is arranged inside the columnar transition structure (4-3).
6. The adjustable mechanical joint with position-maintaining function according to claim 5, characterized in that: The edge of the toothed structure (4-2) is provided with a chamfer, so that the toothed structure (4-2) can easily slide into the toothed through hole (3-2) of the lower limb connecting device (3) under the action of the restoring force of the axial return spring (6).
7. The adjustable mechanical joint with position holding function according to claim 1, characterized in that: The U-shaped fork arms on both sides of the limit buckle (5) are provided with semicircular grooves (5-1), which form a matching relationship with the middle structure of the spring pressure regulating button (4), namely the columnar transition structure (4-3), so that the spring pressure regulating button (4) can rotate by relying on the inner wall surface of the semicircular groove (5-1).
8. The adjustable mechanical joint with position-maintaining function according to claim 7, characterized in that: The opening radius of the semicircular slot (5-1) is smaller than the outer diameter of the toothed structure (4-2) in the spring pressure regulating button (4), thereby preventing the spring pressure regulating button (4) from sliding out in the axial direction under the elastic force of the axial return spring (6).
9. The adjustable mechanical joint with position-maintaining function according to claim 5, characterized in that: The axial return spring (6) is symmetrically distributed on both sides of the sheet-like connection structure (1-2) in the upper limb connection device (1); one end of the axial return spring (6) abuts against the side of the sheet-like connection structure (1-2) in the upper limb connection device (1), and the other end abuts against the inner end surface of the columnar transition structure (4-3) in the spring pressure adjustment button (4), pressing the spring pressure adjustment button (4) axially toward both sides of the limit buckle (5).
10. A process for using the adjustable mechanical joint with position-keeping function according to any one of claims 1 to 9, characterized in that: The following steps are involved: In the position-holding state, the axial return springs (6) pressed on both sides of the sheet-shaped connection structure (1-2) of the upper limb connection device (1) push the spring pressure adjustment buttons (4) on the left and right sides to the sides under the action of elastic force, but the U-shaped fork arms on both sides of the limit buckle (5) restrict the spring pressure adjustment button (4) from slipping off to the sides, so that the toothed structure (4-2) of the spring pressure adjustment button (4) just matches with the toothed through hole (3-2) on the U-shaped fork arm on the lower limb connection device (3), thereby achieving locking and restricting the relative rotation of the components, so that the relative position and posture of the entire puppet limb joint remain unchanged. This state is called the position-holding state; When adjusting the position and posture, the spring pressure adjustment buttons (4) on the left and right sides are compressed toward the middle, the axial return spring (6) and the locking spring 7 are compressed, and the toothed structure (4-2) of the spring pressure adjustment button (4) slides out of the toothed through hole (3-2) on the lower limb connection device (3), completing the unlocking. At this time, the upper limb connection device (1) or the lower limb connection device (3) can be rotated and adjusted; this state is called the position adjustment state or the posture adjustment state; The position of the spring pressure adjustment button (4) is maintained, and after the upper limb connection device (1) or the lower limb connection device (3) is rotated to adjust the angle to a set angle, the force applied to the spring pressure adjustment buttons (4) on the left and right sides is removed, and the toothed structure (4-2) is moved to both sides by using the axial return spring (6) and the axial locking spring (7). The chamfer of the toothed structure (4-2) induces the toothed structure to slide into the toothed through hole (3-2) on the U-shaped fork arm on the lower limb connection device (3), so that the two are locked in a matched manner again and return to the position holding state.