Metamorphic spherical pair structure

Abstract

The metamorphic ball pair structure comprises a ball seat and a ball head, a ball socket is formed in the ball seat in a concave mode, the ball head is connected into the ball socket in a ball pair mode, at least two restraining hole grooves are formed in the socket wall of the ball socket at intervals, and a restraining rod which can be selectively inserted into at least one restraining hole groove is connected to the ball head. The restraining rod can be arranged in the restraining hole groove in a sliding or rotating mode, and freedom degree restraining of the ball head in the specific direction is achieved through sliding or rotating of the restraining rod in the restraining hole groove. The corresponding degree of freedom can be switched according to working condition requirements, and the motion mode of the robot is adjusted, so that more complex operation is achieved, and different working scenes are coped with.

Description

Technical Field

[0001] The present invention relates to the technical field of ball pair structures, in particular to a metamorphic ball pair structure. Background Art

[0002] Metamorphic mechanisms were first proposed in 1995 during a study on a multi-fingered robotic arm for decorative gift box packaging. This type of mechanism is unique in its "reconfigurability"—its structure can instantly change its topology during operation through the merging and separation of components, or through singular changes in geometry, thereby achieving changes in the mechanism's configuration, degrees of freedom, or the number of active components. This mechanism enables metamorphic mechanisms to flexibly switch functions across different operational tasks or environments, demonstrating high adaptability and reconfigurability. It is widely used in cutting-edge technology fields such as robotics, medical devices, wearables, and aerospace.

[0003] The metamorphic ball pair, developed on this basis, is an innovative design that deeply integrates traditional ball pairs with metamorphic concepts. Traditional ball pairs are essential components for achieving complex spatial motion, but their degrees of freedom are typically fixed. Metamorphic ball pairs, on the other hand, introduce controllable structural adjustment mechanisms (such as variable stiffness, locking devices, magnetically controlled structures, or smart materials) that allow the pair to dynamically change its degrees of freedom or restricted directions during motion, depending on the mission requirements. This allows for seamless transitions from fully free rotation to partially restricted motion.

[0004] The core of the metamorphic spherical joint design lies in achieving controllable switching of motion degrees of freedom and flexible reconstruction of spatial motion modes. This allows it to actively adjust its state according to working conditions in complex mission environments. Therefore, how to design a metamorphic spherical joint structure that can switch degrees of freedom and motion modes requires further consideration. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a metamorphic ball substructure that can switch degrees of freedom and motion modes according to needs.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A metamorphic ball pair structure includes a ball seat and a ball head. A ball socket is formed on the ball seat. The ball head and ball pair are connected to the ball socket. At least two constraint holes are spaced apart on the socket wall of the ball socket. A constraint rod is connected to the ball head and can be selectively inserted into at least one constraint hole. The constraint rod can be slidably or rotatably set in the constraint hole. The sliding or rotation of the constraint rod in the constraint hole can realize the constraint of the freedom of the ball head in a specific direction.

[0008] As an optimization, at least two guide slide holes are recessed at intervals on the ball head, and the number of guide slide holes is less than or equal to the number of the constraint slots. The guide slide holes extend along the radial direction of the ball head, and each guide slide hole is provided with the constraint rod coaxial with the guide slide hole. The constraint rod is slidably connected to the corresponding guide slide hole and can slide along the centerline direction of the guide slide hole, so that the outer end of the constraint rod can slide out or slide into the guide slide hole. When the ball head is in a specific position, the positions of at least two of the constraint rods correspond to the positions of the same number of constraint slots. Different constraint rods can be controlled as needed, and can be extended to constrain or slid into and hidden by sliding. Moreover, when the ball head is in a special position, the constraint can be switched between different constraint slots by replacing the constraint rod without changing the current position of the ball head, thereby achieving a change in the degree of freedom.

[0009] As an optimization, a rotating cavity is provided at the center of the ball head, and the center lines of all the guide sliding holes are located on the same plane and are connected to the rotating cavity. A return spring connected thereto is provided between the constraint rod and the guide sliding hole. When the return spring is in a natural state, the outer end of the constraint rod is located in the guide sliding hole, and the inner end of the constraint rod is recessed with a guide socket along the center line direction of the constraint rod. A guide plug rod that can slide with it along the center line direction of the guide socket is provided in the guide socket on the same center line. A return spring connected thereto is provided between the inner end of the guide plug rod and the bottom of the guide socket. When the return spring is in a natural state, the outer end of the guide plug rod extends out of the guide socket and extends into the rotating cavity. A rotating cavity is provided on the ball head along its radial direction. The centerline of the rotating shaft is perpendicular to the plane where the centerlines of all the guide sliding holes are located. The inner end of the rotating shaft passes through the ball head and extends into the rotating cavity. The outer end of the rotating shaft extends outside the ball socket. The inner end of the rotating shaft is rotatably connected to the cavity wall of the rotating cavity. The shaft body of the rotating shaft and the ball head are rotatably matched. The shaft body of the rotating shaft located in the rotating cavity is provided with an outer protrusion. When the rotating shaft rotates around its centerline, the outer protrusion can respectively abut the inner end of the corresponding guide plug rod and push the guide plug rod inward to squeeze the return spring. When the position of the constraint rod corresponds to the position of the constraint hole slot, the outer protrusion can squeeze the return spring through the guide plug rod, so that the return spring can push the constraint rod to extend outward and insert into the constraint hole slot. When the rotating shaft rotates, the outer protrusion on it can also rotate, so that the outer protrusion can abut on different guide plug rods during the rotation process. When the outer protrusion abuts against the guide rod, the guide rod can squeeze the return spring, and the other end of the return spring will push the constraint rod. When the constraint rod corresponds to the position of the constraint hole slot, the constraint rod can extend outward to the constraint hole slot to achieve constraint; when the constraint rod extends outward, the constraint rod will also exert a force on the return spring. When the outer protrusion withdraws its external resistance to the guide rod, the return spring returns to its position, and the spring force generated in the process will drive the constraint rod to retract into the guide slide hole.In addition, when the ball head needs to maintain its current state and switch to another degree of freedom, it is necessary to rotate the rotation axis so that the outer protrusion selects the corresponding constraint rod. If the number of constraint rods is too large, there will be other useless constraint rods between the currently selected constraint rod and the constraint rod that needs to be switched subsequently. When the positions of these useless constraint rods in the middle correspond to the wall of the ball socket, the constraint rod cannot extend outward, so the constraint rod will block the outer protrusion and the rotation axis can no longer be rotated. In order to avoid this problem, the present application slides a guide rod and a return spring between the constraint rod and the guide rod at the inner end of the constraint rod. When the outer protrusion rotates to the guide rod corresponding to the middle useless constraint rod, the extrusion of the outer protrusion will cause the guide rod to be inserted into the guide socket and squeeze the return spring at the same time. Therefore, the guide rod will not hinder the continued rotation of the outer protrusion. After the outer protrusion rotates, the guide rod loses the abutment of the outer protrusion, and the rebound of the return spring will cause the guide rod to move outward and return to its position.

[0010] As an optimization, the outer protrusion is a cam sleeved on the rotating shaft, the cam and the rotating shaft are key-connected, and a retaining spring is clamped on the shaft body of the rotating shaft to limit the movement of the cam along the center line direction of the rotating shaft.

[0011] As an optimization, the rotating shaft and the ball head are rotatably connected together via a bearing.

[0012] As an optimization, the rotating shaft is located above the outer protrusion and within the rotating cavity, and a convex ring is circumferentially protruding around the rotating shaft. The rotating shaft is located above the convex ring and within the rotating cavity, and a pressure ring and a preload spring are arranged from bottom to top on the shaft. The two ends of the preload spring respectively abut the pressure ring and the cavity wall of the rotating cavity. The preload spring can provide spring force to press the pressure ring against the convex ring. This can prevent the outer protrusion from colliding with the guide rod and generating noise when the rotating shaft is loose.

[0013] As an optimization, the rotating shaft is located outside the ball head and is sleeved with a limit sleeve which is coaxial with the rotating shaft, and the limit sleeve is fixedly connected to the ball head at one end facing the ball head, and a spring top bead is embedded in the shaft body of the rotating shaft corresponding to the position of the limit sleeve along the radial direction of the rotating shaft, and a plurality of limit holes are penetrated on the sleeve body of the limit sleeve at the position corresponding to the spring top bead around the circumferential direction of the limit sleeve, and the limit holes extend along the radial direction of the limit sleeve, and the number of limit holes is consistent with the number of the constraint rods. Through the rotation of the rotating shaft, the round balls on the spring top bead can be respectively stuck in the corresponding limit holes to limit the rotation of the rotating shaft, and when the round balls on the spring top bead abut against one of the limit holes, the outer protrusion can correspondingly abut against one of the guide rods and cause the guide rod to squeeze the return spring. When the rotating shaft is rotated and the outer protrusion pushes the constraint rod into the constraint hole groove, the round ball on the spring top ball will also extend into one of the limiting holes. By limiting the round ball through the limiting hole, the rotating shaft can be positioned, the constraint rod can be kept pushed outward, and the constraint state between the constraint rod and the constraint hole groove can be achieved.

[0014] As an optimization, the ball head is composed of two hemispheres, and the rotating cavity and the guide sliding hole are both formed by closing grooves recessed on the circular planes of the two hemispheres.

[0015] As an optimization, the outer end of the guide rod is a round head end, so that when the outer convex part rotates past, the round head end of the guide rod can better guide the outer convex part.

[0016] As an optimization, the guide slide hole is provided with a reset bar hole extending parallel to the centerline of the guide slide hole on both sides of the hole wall. The restraining rod has protruding reset bumps on both sides of the rod body that extend into the corresponding reset bar hole and can slide with the reset bar hole along its extension direction. The reset bumps are provided with reset springs on one side of each of the reset bar holes, and the two ends of the reset springs are connected to the reset bumps and the ends of the reset bar hole, respectively. The reset springs on both sides of the reset bumps can limit the position of the restraining rod in the absence of external force. When the return springs push the restraining rod outward, one of the reset springs on both sides of the reset bump is in a compressed state, and the other is in a stretched state. This can provide spring force to reset the restraining rod when the return springs lose their spring force.

[0017] Compared with the existing technology, the present invention has the following beneficial effects: the present invention can switch the corresponding degrees of freedom according to the working conditions and adjust its own motion mode, thereby realizing more complex operations and coping with different working scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the appearance of an embodiment of the present invention;

[0019] Figure 2 Schematic diagram of the internal structure of an embodiment of the present invention;

[0020] Figure 3 Schematic diagram of five motion modes in an embodiment of the present invention;

[0021] Figure 4 is a flow chart of switching sports modes in an embodiment of the present invention;

[0022] Figure 5 Schematic diagram of the arrangement of branches in an embodiment of the present invention;

[0023] Figure 6 Schematic diagram of the arrangement of the kinematic pairs of the branch chain in an embodiment of the present invention;

[0024] Figure 7 Schematic diagram of the motion mode of the branched motion pair in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] like Figure 1 and Figure 2 As shown, a metamorphic ball pair structure in this specific embodiment includes a ball seat 1 and a ball head 2. The ball seat 1 is concavely formed with a ball socket, and the ball head 2 is connected to the ball socket. At least two constraint holes are spaced apart on the socket wall of the ball socket. The ball head 2 is connected to a constraint rod 3 that can be selectively inserted into at least one constraint hole. The constraint rod 3 can be slidably or rotatably arranged in the constraint hole. By sliding or rotating the constraint rod 3 in the constraint hole, the freedom of the ball head 2 in a specific direction is constrained.

[0027] In this specific embodiment, at least two guide sliding holes are recessed on the ball head 2 at intervals, and the number of guide sliding holes is less than or equal to the number of the constraint hole grooves. The guide sliding holes are extended in the radial direction of the ball head 2, and each guide sliding hole is provided with the constraint rod 3 coaxial with it. The constraint rod 3 is slidably connected to the corresponding guide sliding hole and can slide along the center line direction of the guide sliding hole, so that the outer end of the constraint rod 3 can slide out or slide into the guide sliding hole. When the ball head 2 is located at a specific position, the positions of at least two of the constraint rods 3 correspond to the positions of the same number of constraint hole grooves.

[0028] In this specific embodiment, a rotating cavity is provided at the center of the ball head 2, and the center lines of all the guide sliding holes are located on the same plane and are connected to the rotating cavity. A return spring connected thereto is provided between the constraint rod 3 and the guide sliding hole. When the return spring is in a natural state, the outer end of the constraint rod 3 is located in the guide sliding hole, and the inner end of the constraint rod 3 is recessed with a guide socket along the center line direction of the constraint rod 3. A guide plug rod 4 that can slide with it along the center line direction of the guide socket is provided in the guide socket on the same center line. A return spring connected thereto is provided between the inner end of the guide plug rod 4 and the bottom of the guide socket. When the return spring is in a natural state, the outer end of the guide plug rod 4 extends out of the guide socket and extends into the rotating cavity. A rotating axis is provided on the ball head 2 along its radial direction. 5. The centerline direction of the rotating shaft 5 is perpendicular to the plane where the centerlines of all the guide sliding holes are located. The inner end of the rotating shaft 5 passes through the ball head 2 and extends into the rotating cavity, and the outer end of the rotating shaft 5 extends out of the ball socket. The inner end of the rotating shaft 5 is rotatably connected to the cavity wall of the rotating cavity, and the shaft body of the rotating shaft 5 is rotatably matched with the ball head 2. The rotating shaft 5 is located in the rotating cavity and is provided with an outer convex portion on the shaft body. When the rotating shaft 5 rotates around its centerline direction, the outer convex portion can respectively abut against the inner end of the corresponding guide plug 4 and push the guide plug 4 to move inward to squeeze the return spring. When the position of the constraint rod 3 corresponds to the position of the constraint hole groove, the outer convex portion can squeeze the return spring through the guide plug 4, so that the return spring can push the constraint rod 3 to extend outward and be inserted into the constraint hole groove.

[0029] In this specific embodiment, the outer protrusion is a cam 6 mounted on the rotating shaft 5. The cam 6 and the rotating shaft 5 are connected by a key. A retaining spring is clamped on the shaft of the rotating shaft 5 to limit the movement of the cam 6 along the center line direction of the rotating shaft 5.

[0030] In this specific embodiment, the rotating shaft 5 and the ball head 2 are rotatably connected together via a bearing.

[0031] In this specific embodiment, the rotating shaft 5 is located above the outer convex portion and is located in the rotating cavity. There is a convex ring circumferentially protruding around the rotating shaft 5. The rotating shaft 5 is located above the convex ring and is located in the rotating cavity. A pressure ring 7 and a preload spring 8 are provided from bottom to top on the shaft. The two ends of the preload spring 8 are respectively abutted against the pressure ring 7 and the cavity wall of the rotating cavity. The preload spring 8 can provide spring force for the pressure ring 7 to press against the convex ring.

[0032] In this specific embodiment, the rotating shaft 5 is located outside the ball head 2 and is sleeved with a limit sleeve 9 that is coaxial with the rotating shaft 5. The limit sleeve 9 is fixedly connected to the ball head 2 at one end facing the ball head 2. A spring top ball 10 is embedded in the shaft body of the rotating shaft 5 corresponding to the position of the limit sleeve 9 along the radial direction of the rotating shaft 5. The position of the spring top ball 10 on the sleeve body of the limit sleeve 9 is circumferentially provided with a plurality of limit holes 11 around the limit sleeve 9. The limit holes 11 extend along the radial direction of the limit sleeve 9. The number of limit holes 11 is consistent with the number of the constraint rod 3. Through the rotation of the rotating shaft 5, the round balls on the spring top ball 10 can be respectively inserted into the corresponding limit holes 11 to limit the rotation of the rotating shaft 5. When the round ball on the spring top ball 10 abuts against one of the limit holes 11, the outer convex portion can correspondingly abut against one of the guide rods 4 and cause the guide rod 4 to squeeze the return spring.

[0033] In this specific embodiment, the ball head 2 is composed of two hemispheres, and the rotating cavity and the guide sliding hole are both formed by combining grooves recessed on the circular planes of the two hemispheres.

[0034] In this specific embodiment, the outer end of the guide rod 4 is a round end.

[0035] In this specific embodiment, reset bar holes extending in a direction parallel to the center line of the guide slide hole are respectively provided on both sides of the hole wall of the guide slide hole, and reset protrusions are respectively raised on both sides of the rod body of the constraint rod 3, which extend into the corresponding reset bar hole and can slide with it along the extension direction of the reset bar hole. The reset protrusions are respectively provided on one side of the two ends of the reset bar hole with the reset spring, and the two ends of the reset spring are respectively connected to the reset protrusion and the end of the reset bar hole.

[0036] In a specific implementation, there are four restraining rods, evenly spaced, so a coordinate system can be established based on the centerlines of the four restraining rods. Furthermore, the ball socket has four restraining slots, two of which are adjacent bar-shaped holes connected to the exterior of the ball socket, and the other two holes are circular holes connected to the exterior of the ball socket. One of the two bar-shaped holes extends vertically, and the other extends horizontally. The restraining rods can slide along the bar-shaped holes within the bars, while the restraining rods can rotate within the circular holes. When the ball head is in a specific position, the positions of the four restraining rods simultaneously correspond to the positions of the four restraining slots.

[0037] Movement pattern analysis

[0038] like Figure 3 As shown in FIG. 1 , the equivalent kinematic pair types corresponding to the five motion modes in this embodiment, and the constraint spirals corresponding to the five motion modes are:

[0039]

[0040] In addition to the above constraints, the constraint rods in the five motion modes are also uniformly subject to three inherent displacement constraints imposed by the ball sub-ball seat, as shown in Equation 2:

[0041]

[0042] Therefore, R m The mode can realize the freedom of rotation around the x-axis, U n The mode can realize the rotational freedom around the y-axis and z-axis, U m The mode can realize the rotational freedom around the x-axis and y-axis, R n The s mode can realize the rotational freedom around the y-axis, and the s mode can realize the rotational freedom around the x-axis, y-axis and z-axis. The switching process of the five motion modes is as follows Figure 4 shown.

[0043] In order to give the parallel mechanism the reconfigurable characteristics of the present application, this embodiment uses a constraint branch chain including the present application, and its deployment position is as follows Figure 5 As shown. The constraint helix of the parallel mechanism dynamic platform is related to the constraint helix of each branch. In order to better highlight the reconfigurable characteristics of this application, this embodiment sets all branches except the branch containing this application as unconstrained branches, and at the same time limits the number of kinematic pairs of the branch containing this application to three. Since this application is designed based on a ball pair, its rotation axis cannot be used as an input, so the input of the branch containing this application is fixed to a moving pair.

[0044] Based on the above limiting conditions, this embodiment designs five special constraint branches including the present application, such as Figure 6These branches are divided into two categories: one is the underactuated constraint branch, which, as the name implies, has no active pair but only a passive pair; the other is the driven constraint branch, which not only includes the present application but also has a mobile pair as an active pair. Both types of branches have the reconfigurable characteristics of the present application. Based on the deployment of these five branch motion pairs and combined with the various motion modes of the metamorphic ball pair, a variety of different branch types are derived, such as Figure 7 shown.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention that do not depart from the purpose and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A metamorphic ball pair structure, comprising a ball seat and a ball head, wherein the ball seat is concavely formed with a ball socket, and the ball head and ball pair are connected in the ball socket, characterized in that: At least two constraint holes are spaced apart on the wall of the ball socket, and a constraint rod is connected to the ball head which can be selectively inserted into at least one constraint hole. The constraint rod can be slid or rotated in the constraint hole. The freedom of the ball head in a specific direction is constrained by the sliding or rotation of the constraint rod in the constraint hole.

2. The metamorphic ball substructure according to claim 1, characterized in that: At least two guide sliding holes are recessed on the ball head at intervals, and the number of the guide sliding holes is less than or equal to the number of the constraint hole grooves. The guide sliding holes extend along the radial direction of the ball head, and each guide sliding hole is provided with the constraint rod coaxial with the guide sliding hole. The constraint rod is slidably connected to the corresponding guide sliding hole and can slide along the center line direction of the guide sliding hole, so that the outer end of the constraint rod can slide out of or into the guide sliding hole. When the ball head is in a specific position, the positions of at least two of the constraint rods correspond to the positions of the same number of constraint hole grooves.

3. The metamorphic ball substructure according to claim 2, characterized in that: The center of the ball head is provided with a rotating cavity, and the center lines of all the guide sliding holes are located in the same plane and are connected to the rotating cavity, and a return spring respectively connected thereto is provided between the constraint rod and the guide sliding hole. When the return spring is in a natural state, the outer end of the constraint rod is located in the guide sliding hole, and the inner end of the constraint rod is recessed with a guide socket along the center line direction of the constraint rod, and a guide plug rod that can slide with it along the center line direction of the guide socket is provided in the guide socket on the same center line, and a return spring respectively connected thereto is provided between the inner end of the guide plug rod and the bottom of the guide socket. When the return spring is in a natural state, the outer end of the guide plug rod extends out of the guide socket and extends into the rotating cavity, and a rotating axis is provided on the ball head along its radial direction. The centerline direction of the rotating shaft is perpendicular to the plane where the centerlines of all the guide sliding holes are located. The inner end of the rotating shaft passes through the ball head and extends into the rotating cavity, and the outer end of the rotating shaft extends out of the ball socket. The inner end of the rotating shaft is rotatably connected to the cavity wall of the rotating cavity, and the shaft body of the rotating shaft and the ball head are rotatably matched. An outer convex portion is provided on the shaft body of the rotating shaft located in the rotating cavity. When the rotating shaft rotates around its centerline direction, the outer convex portion can respectively abut against the inner end of the corresponding guide rod and push the guide rod to move inward to squeeze the return spring. When the position of the constraint rod corresponds to the position of the constraint hole groove, the outer convex portion can squeeze the return spring through the guide rod, so that the return spring can push the constraint rod to extend outward and insert into the constraint hole groove.

4. The metamorphic ball substructure according to claim 3, characterized in that: The outer protrusion is a cam sleeved on the rotating shaft, the cam and the rotating shaft are connected by a key, and a retaining spring is clamped on the shaft body of the rotating shaft to limit the movement of the cam along the center line direction of the rotating shaft.

5. The metamorphic ball substructure according to claim 3, characterized in that: The rotating shaft and the ball head are rotatably connected together via a bearing.

6. The metamorphic ball substructure according to claim 3, characterized in that: The rotating shaft is located above the outer convex portion and is located in the rotating cavity. A convex ring is circumferentially protruding around the rotating shaft. The rotating shaft is located above the convex ring and is located in the rotating cavity. A pressure ring and a preload spring are provided from bottom to top on the shaft. The two ends of the preload spring are respectively abutted against the pressure ring and the cavity wall of the rotating cavity. The preload spring can provide spring force for the pressure ring to press against the convex ring.

7. The metamorphic ball substructure according to claim 3, characterized in that: The rotating shaft is located outside the ball head and is sleeved with a limit sleeve which is coaxial with the rotating shaft. The limit sleeve is fixedly connected to the ball head towards one end of the ball head. A spring top ball is embedded in the shaft body of the rotating shaft corresponding to the position of the limit sleeve along the radial direction of the rotating shaft. A plurality of limit holes are provided on the sleeve body of the limit sleeve corresponding to the position of the spring top ball around the circumferential direction of the limit sleeve. The limit holes extend along the radial direction of the limit sleeve. The number of limit holes is consistent with the number of the constraint rods. Through the rotation of the rotating shaft, the round balls on the spring top ball can be respectively inserted into the corresponding limit holes to limit the rotation of the rotating shaft. When the round balls on the spring top ball abut against one of the limit holes, the outer protrusion can correspondingly abut against one of the guide rods and cause the guide rod to squeeze the return spring.

8. The metamorphic ball substructure according to claim 3, characterized in that: The ball head is composed of two hemispheres, and the rotating cavity and the guide sliding hole are both formed by closing grooves concavely arranged on the circular planes of the two hemispheres.

9. The metamorphic ball substructure according to claim 3, characterized in that: The outer end of the guide rod is a round head end.

10. The metamorphic ball substructure according to claim 3, characterized in that: Reset bar holes extending in a direction parallel to the center line of the guide slide hole are respectively provided on both sides of the hole wall of the guide slide hole, and reset protrusions extending into the corresponding reset bar holes and capable of slidingly cooperating with the reset bar holes along the extension direction of the reset bar holes are respectively raised on both sides of the reset protrusions corresponding to the two ends of the reset bar holes. The reset springs are respectively provided on one side of the reset protrusions corresponding to the two ends of the reset bar holes, and the two ends of the reset spring are respectively connected to the reset protrusions and the ends of the reset bar holes.

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