Nine-degree-of-freedom spherical hinge linkage locking universal support

Abstract

The invention belongs to the technical field of hardware tools, and particularly discloses a nine-degree-of-freedom spherical hinge linkage locking universal support which comprises a first joint part, a middle ball head rod and a second joint part, and the first joint part and the second joint part are connected through the middle ball head rod; the linkage locking device is used for achieving linkage locking of the universal support through the nine-degree-of-freedom Compared with the prior art, nine-degree-of-freedom movement and locking of the universal support are achieved, the structure is simple, and adaptability is high.

Description

Technical Field

[0001] The invention relates to the technical field of hardware tools, and in particular to a nine-degree-of-freedom ball hinge linkage locking universal bracket. Background Art

[0002] Universal bracket is a common mechanical device, usually composed of multiple rods connected by swivel joints. It is flexible in design and can achieve a variety of different positions and directions by rotating each joint. Therefore, it is widely used in table lamps, cameras, measuring instruments, medical equipment and other items to achieve random positioning needs in a large space.

[0003] The universal bracket in the prior art usually directly forms a ball joint by connecting an integrated ball head and a ball socket. This type of universal bracket has a low degree of freedom, and when locking is required, force is applied to the ball head rod to increase the friction between the ball head and the ball socket for locking. This locking method has limited load-bearing capacity due to the length of the ball head rod, and has a short lifespan and is not convenient for maintenance and replacement. In addition, the adjustment and locking methods of the existing universal bracket are cumbersome and have poor stability, making it inconvenient to achieve the ideal effect through a single locking operation. Summary of the invention

[0004] To solve the above problems, the present invention provides a nine-degree-of-freedom ball hinge linkage locking universal bracket, which realizes 9-degree-of-freedom transmission of the universal bracket through a combined ball head rod and a connecting mechanism, and is easy to lock, easy to use and replace, and highly practical.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is a nine-degree-of-freedom ball hinge linkage locking universal rod bracket, characterized in that the universal rod bracket includes a first joint part, an intermediate ball head rod and a second joint part, and the first joint part and the second joint part are connected by the intermediate ball head rod; it is used to realize a nine-degree-of-freedom ball hinge linkage locking universal rod bracket.

[0006] Furthermore, the first joint part includes a first ball head rod and a first connecting structure, the first ball head rod is arranged on the upper side of the first connecting structure and is ball-jointed with the first connecting structure; the intermediate ball head rod is a single-ended spherical structure, one end of the intermediate ball head rod is connected to the bottom of the first connecting structure; the second joint part includes a second connecting structure and a second ball head rod; one end of the second connecting structure is ball-jointed with the other end of the intermediate ball head rod, and the other end is ball-jointed with the second ball head rod.

[0007] Furthermore, the first ball head rod includes a first ball head sleeve, a first ball crown push block and a first push rod. The first ball crown push block is movably mounted on the bottom of the first ball head sleeve. The arcuate surface of the first ball head sleeve and the arcuate surface of the first ball crown push block are located on the same spherical surface, constituting the ball head part of the first ball head rod. A through hole is provided in the middle of the first ball head sleeve. The first push rod is installed in the through hole in the middle of the first ball head sleeve and can move along the axis direction of the through hole, so as to bear external forces and lock the ball joint.

[0008] Furthermore, the first connection structure includes an upper cover plate of the first joint, a lower cover plate of the first joint and a semi-slider; the semi-slider is movably installed inside the lower cover plate of the first joint, and the inner arc surface of the semi-slider is in ball contact with the first ball head rod; the upper cover plate of the first joint and the lower cover plate of the first joint are fixedly connected.

[0009] Furthermore, the second connection structure includes a joint tube, an upper end cover plate of the second joint part, a lower end cover plate of the second joint part and a slider; a slider is movably arranged in the joint tube, and the two end surfaces of the slider are in contact with the intermediate ball head rod and the ball head part of the second ball head rod respectively, and the upper end surface and the lower end surface of the joint tube are respectively provided with a second joint upper end cover plate and a second joint lower end cover plate; the second joint upper end cover plate and the second joint lower end cover plate are fixedly connected to the joint tube; the inner surface of the second joint upper end cover plate and the upper end surface of the slider together constitute a semi-enclosed space adapted to the ball head part of the intermediate ball head rod, for accommodating the ball head part of the intermediate ball head rod, thereby forming a ball joint; the inner surface of the second joint lower end cover plate and the lower end surface of the slider together constitute a semi-enclosed space adapted to the ball head part of the second ball head rod, for accommodating the ball head part of the second ball head rod, thereby forming a ball joint.

[0010] Furthermore, the intermediate ball head rod includes an intermediate ball head sleeve, a second ball crown push block and a second push rod. The upper end of the intermediate ball head sleeve is fixedly connected to the lower end cover of the upper joint, and the ball head end of the intermediate ball head sleeve is movably installed with the second ball crown push block. The arc surface of the intermediate ball head sleeve and the second ball crown push block are located on the same spherical surface as the arc surface of the second ball crown push block, forming the ball head part of the intermediate ball head rod; the second push rod is installed in the intermediate ball head sleeve, and the two ends of the second push rod are respectively attached to the bottom end of the semi-slider and the top end of the second ball crown push block; and the two ends of the second push rod are higher than the end faces of the through hole in the middle of the intermediate ball head sleeve and the lower end cover of the upper joint.

[0011] Furthermore, the structure of the second putter or the first putter is a "putter structure" or a "putter + small ball combination structure of equal diameter".

[0012] Furthermore, the slider is laterally funnel-shaped, rectangular-shaped, or circular-shaped.

[0013] As another technical solution, the first joint portion includes a first ball head rod and a second connection structure, the first ball head rod is arranged on the upper side of the second connection structure and is ball-jointed with one end of the second connection structure; the intermediate ball head rod is a double-ended spherical structure, and the other end of the second connection structure is ball-jointed with one end of the intermediate ball head rod;

[0014] The second joint part comprises a first connection structure and a solid rod; the other end of the intermediate ball head rod is ball-jointed with the first connection structure, and the bottom of the first connection structure is connected with the solid rod.

[0015] Furthermore, the intermediate ball head rod is a double-ended spherical structure, specifically including a second intermediate ball head sleeve, a third ball crown push block, a fourth ball crown push block and a third push rod. One end of the second intermediate ball head sleeve is movably mounted on the third ball crown push block, and the arc surface of one end of the second intermediate ball head sleeve and the arc surface of the third ball crown push block are located on the same spherical surface, forming an upper ball head portion of the intermediate ball head rod; the other end of the second intermediate ball head sleeve is movably mounted on the fourth ball crown push block, and the end arc surface of the other end of the second intermediate ball head sleeve and the arc surface of the fourth ball crown push block are located on the same spherical surface, forming a lower ball head portion of the intermediate ball head rod; the third push rod is installed in the second intermediate ball head sleeve, one end of the third push rod is in contact with the plane of the third ball crown push block, and the other end is in contact with the top plane of the fourth ball crown push block.

[0016] The technical solution of the present invention has the following beneficial effects:

[0017] 1. The joint system of the present invention is connected by a ball hinge, through the first joint part, the middle ball head rod and the second joint part, and the swing angle amplitude is increased through double joint connection, which increases the degree of freedom and is more flexible to use in space.

[0018] 2. The present invention sets an axial through hole in the first ball head rod and the middle ball head rod, sets a push rod in the through hole, and makes the end face of the push rod contact with the ball crown push block, so that when locking is required, it is only necessary to apply a locking pressure at the upper push rod, and the locking pressure can be transmitted to the next joint part through the push rod and the ball crown push block, thereby realizing the linkage locking of the joint, so that the end of the universal bracket can be reliably positioned through one operation, which is highly applicable to occasions where random, rapid, frequent and large-scale changes of target points are required during work.

[0019] In the present invention, the first ball head rod comprises a first ball head sleeve, a first ball crown push block and a first push rod, and the intermediate ball head rod comprises an intermediate ball head sleeve, a second ball crown push block and a second push rod; when performing linkage locking, force is transmitted through the first ball crown push block and the second ball crown push block, thereby avoiding damage to the first ball head sleeve and the second ball head sleeve in long-term use, and further improving the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings.

[0021] Figure 1 It is the overall structure front view of the present invention.

[0022] Figure 2 It is a schematic diagram of the shape change of the slider.

[0023] Figure 3 It is a schematic diagram of the push rod structure changes. Figure 4 It is a schematic structural diagram of another embodiment of the present invention.

[0024] Among them, 1-upper ball head rod, 2-upper ball head sleeve, 3-upper end cover plate of upper joint, 4-first ball crown push block, 5-lower end cover plate of upper joint, 6-middle ball head rod, 7-middle ball head sleeve, 8-upper end cover plate of lower joint, 9-second ball crown push block, 10-slider, 11-joint tube, 12-lower end cover plate of lower joint, 13-solid ball head rod, 14-second connecting structure, 15-first connecting structure, 16-first push rod, 17-second push rod, 20-semi-slider. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0026] like Figure 1 As shown, this embodiment provides a nine-degree-of-freedom ball hinge linkage locking universal bracket, including an upper joint part, an intermediate ball head rod 6 and a lower joint part, and the upper joint part and the lower joint part are connected by the intermediate ball head rod 6; the upper joint part has 3 degrees of freedom, and the lower joint part has 6 degrees of freedom, realizing a 9-degree-of-freedom ball hinge linkage locking universal bracket.

[0027] The upper joint part includes an upper ball head rod 1 and a first connecting structure 15. The upper ball head rod 1 is arranged on the upper side of the first connecting structure 15 and is ball-jointed with the first connecting structure 15.

[0028] The upper ball head rod 1 includes an upper ball head sleeve 2, a first ball crown push block 4 and a first push rod 16. The first ball crown push block 4 is movably installed at the bottom of the upper ball head sleeve 2. The upper ball head sleeve 2 and the first ball crown push block 4 can slide relative to each other along the axis direction of the ball head sleeve 2. The arc surfaces of the upper ball head sleeve 2 and the first ball crown push block 4 are located on the same spherical surface, forming the ball head of the upper ball head rod 1. A through hole is provided in the middle of the upper ball head sleeve 2, and the first push rod 16 is installed in the through hole in the middle of the upper ball head sleeve 2.

[0029] The first connection structure 15 includes an upper joint upper end cover plate 3, an upper joint lower end cover plate 5 and a semi-slider 20; the upper joint upper end cover plate 3 and the upper joint lower end cover plate 5 are fixedly connected to connect the upper ball head rod 1, and the semi-slider 20 is arranged inside the upper joint lower end cover plate 5 and can move relatively along the height direction of the upper joint lower end cover plate 5; the inner arc surface of the semi-slider 20 is in direct ball contact with the arc surface of the upper ball head sleeve 2 in the upper ball head rod 1 and the arc surface of the first ball crown push block 4, so as to realize the ball joint rotation of the upper ball head rod 1. The bottom end of the semi-slider 20 is in contact with one end of the second push rod 17 in the middle ball head rod 6.

[0030] The intermediate ball head rod 6 is arranged at the lower side of the first connection structure 15; specifically, it includes an intermediate ball head sleeve 7, a second ball crown push block 9 and a second push rod 17. The upper end of the intermediate ball head sleeve 7 is fixedly connected to the lower end cover plate 5 of the upper joint part, and the ball head end of the intermediate ball head sleeve 7 is movably installed with the second ball crown push block 9. The arc surface of the intermediate ball head sleeve 7 and the second ball crown push block 9 are located on the same spherical surface, forming the ball head of the intermediate ball head rod 6. The second push rod 17 is installed in the intermediate ball head sleeve 7, one end of the second push rod 17 is in contact with the bottom end plane of the semi-slider 20, and the other end is in contact with the top end plane of the second ball crown push block 9; and both ends of the second push rod 17 are slightly higher than the plane end surface of the intermediate ball head sleeve 7 and the through hole in the middle of the lower end cover plate 5 of the upper joint.

[0031] The lower joint part includes: a second connection structure 14 and a solid ball head rod 13;

[0032] The second connection structure 14 includes a joint tube 11, a lower joint upper end cover plate 8, a lower joint lower end cover plate 12 and a slider 10;

[0033] A slider 10 is provided in the joint tube 11, and the two end surfaces of the slider 10 are in contact with the ball head parts of the intermediate ball head rod 6 and the solid ball head rod 13, respectively, and the slider 10 can slide axially in the joint tube 11. The upper end surface and the lower end surface of the joint tube 11 are respectively provided with a lower joint upper end cover plate 8 and a lower joint lower end cover plate 12; the lower joint upper end cover plate 8 and the lower joint lower end cover plate 12 are fixedly connected to the joint tube 11 through threads. The inner surface of the lower joint upper end cover plate 8 and the upper end surface of the slider 10 together form a semi-enclosed ball socket adapted to the ball head part of the intermediate ball head rod 6, which is used to accommodate the ball head part of the intermediate ball head rod 6, thereby forming a ball hinge. The inner surface of the lower joint lower end cover plate 12 and the lower end surface of the slider 10 together form a semi-enclosed ball socket adapted to the ball head part of the solid ball head rod 13, which is used to accommodate the ball head part of the solid ball head rod 13, thereby forming a ball hinge.

[0034] The working principle of the nine-degree-of-freedom ball hinge linkage locking universal bracket is as follows: when in use, the arc surface portion of the upper ball head sleeve 2 is in contact with the cross section of the upper end cover plate 3 of the upper joint part (i.e., the inner arc surface of the upper end cover plate 3 of the upper joint part). When the upper ball head sleeve 2 swings, the cross section of the upper end cover plate 3 of the upper joint part moves relative to the arc surface portion of the upper ball head sleeve 2. When it slides to the junction of the arc surface portion and the plane portion of the upper ball head sleeve 2, the maximum swing amplitude of the upper ball head sleeve 2 is reached, forming a restriction on the alignment freedom. Similarly, the intermediate ball head sleeve 7 also has its own range of degrees of freedom. Combining the upper ball head sleeve 2 and the intermediate ball head sleeve 7 can greatly improve the degree of freedom of the entire sub-joint system. Therefore, the degree of freedom of the ball hinge linkage locking universal bracket can be improved by connecting the upper ball head system and the lower ball head system through the intermediate ball head sleeve 7.

[0035] When the universal bracket needs to be locked, an external force acts on the first push rod 16, and the first push rod 16 pushes the first ball crown push block 4 to move downward, thereby increasing the friction between the first ball crown push block 4 and the semi-slider 20 in the first connecting structure 15, so that the first ball crown push block 4 is locked, thereby achieving the locking of the upper ball head rod 1.

[0036] At the same time, the first ball crown push block 4 pushes the semi-slider 20 to move downward, and then the semi-slider 20 pushes the second push rod 17 to move downward, generating a downward force on the second ball crown push block 9. After the second ball crown push block 9 is squeezed, the pressure is transmitted to the solid ball head rod 13 in the lower joint part through the slider 10, and the friction between the solid ball head rod 13 and the lower end cover plate of the lower joint part is increased, thereby achieving the locking of the entire universal bracket.

[0037] During the process of pressure transmission, since both ends of the second push rod 17 are slightly higher than the end faces of the through holes in the middle of the upper ball head sleeve 2 and the intermediate ball head sleeve 7, and are respectively in contact with the flat ends of the first ball crown push block 4 and the second ball crown push block 9, the pressure exerted on the second ball crown push block 9 will not be borne by the platform on the upper side of the intermediate ball head sleeve 7, so that the locking pressure can be transmitted at one time through the second push rod 17, thereby locking the entire universal bracket.

[0038] As an implementation method, Figure 1 As shown, when the universal bracket is locked and used to connect with actuators such as medical equipment and cameras, the upper ball head rod 1 or the middle ball head rod 6 can be replaced by a solid ball head rod 13 to reduce the processing difficulty and cost.

[0039] like Figure 2 As shown, the shape of the slider 10 is not fixed. It can be a transverse funnel shape, forming arc surfaces at the upper and lower ends that fit with the ball head part of the upper ball head rod 1; it can also be a rectangular or circular shape, with the upper and lower ends only abutting against the ball head part of the upper ball head rod 1.

[0040] As an implementation method, Figure 3 As shown, the second push rod 17 and the first push rod 16 can be composed of a combination of a push rod and a small ball of equal diameter, wherein the small ball is placed between the first push rod 16 and the first ball crown push block 4 or between the second push rod 17 and the second ball crown push block 9, so as to transform the horizontal contact surface into an arc-shaped contact surface, so that the small ball can adjust the force direction by its own deformation when under pressure, so as to better transmit the locking pressure.

[0041] As an implementation method, Figure 4 As shown, a nine-degree-of-freedom ball hinge linkage locking universal bracket, the upper joint portion of which includes an upper ball head rod 1 and a second connecting structure 14, the upper ball head rod 1 is arranged on the upper side of the second connecting structure 14, and is ball-jointed with one end of the second connecting structure 14; the middle ball head rod is a double-ended spherical structure, and the other end of the second connecting structure 14 is ball-jointed with one end of the middle ball head rod 1;

[0042] The lower joint part includes a first connection structure 15 and a solid rod; the other end of the intermediate ball head rod is ball-jointed with the first connection structure 15; the solid rod has no ball head, and the bottom of the first connection structure 15 is fixedly connected to the solid rod.

[0043] The intermediate ball head rod is a double-ended spherical structure, specifically including a second intermediate ball head sleeve, a third ball crown push block, a fourth ball crown push block and a third push rod. One end of the second intermediate ball head sleeve and the third ball crown push block are movably installed. The arc surface at one end of the second intermediate ball head sleeve and the arc surface of the third ball crown push block are located on the same spherical surface, forming the ball head portion on the intermediate ball head rod.

[0044] The other end of the second intermediate ball head sleeve is movably installed with the fourth ball crown push block. The end arc surface of the other end of the second intermediate ball head sleeve and the arc surface of the fourth ball crown push block are located on the same spherical surface to form the lower ball head of the intermediate ball head rod.

[0045] The third push rod is installed in the second intermediate ball head sleeve, one end of the third push rod is in contact with the plane of the third ball crown push block, and the other end is in contact with the top plane of the fourth ball crown push block.

[0046] The present invention forms a nine-degree-of-freedom ball hinge linkage by connecting an upper ball head rod, an intermediate ball head rod, a solid ball head rod and a connecting structure. The upper ball head system realizes three degrees of freedom due to the fixed connection between the lower end cover plate and the intermediate ball head rod. Combined with the swing angle range of the intermediate ball head rod and the solid ball head rod, the swing angle of the lower ball head system is greatly improved, so that the activity range of six degrees of freedom can be achieved through the lower ball head. Compared with the existing technology that realizes the activity range of three degrees of freedom through the ball head rod and the ball head, the present invention greatly improves the degree of freedom of the entire ball hinge linkage locking universal bracket. It makes it possible to obtain a larger degree of freedom when using fewer joint systems, realize the large-range operation function of the universal bracket without reducing the reliability and positioning accuracy of the universal bracket, and greatly improve the practicality of the ball hinge linkage locking universal bracket.

[0047] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A nine-degree-of-freedom ball hinge linkage locking universal rod bracket, characterized in that: The universal rod bracket comprises a first joint part, an intermediate ball head rod and a second joint part, and the first joint part and the second joint part are connected through the intermediate ball head rod; and is used to realize a nine-degree-of-freedom ball hinge linkage locking universal bracket.

2. The nine-degree-of-freedom ball hinge linkage locking universal rod bracket according to claim 1, characterized in that: The first joint part comprises a first ball head rod and a first connecting structure, wherein the first ball head rod is arranged on the upper side of the first connecting structure and is spherically hinged with the first connecting structure; The middle ball head rod is a single-ended spherical structure, and one end of the middle ball head rod is connected to the bottom of the first connecting structure; The second joint portion includes: a second connection structure and a second ball head rod; One end of the second connection structure is ball-jointed to the middle ball head rod, and the other end is ball-jointed to the second ball head rod.

3. The nine-degree-of-freedom ball hinge linkage locking universal rod bracket according to claim 2, characterized in that: The first ball head rod includes a first ball head sleeve, a first ball crown push block and a first push rod. The first ball crown push block is movably mounted on the bottom of the first ball head sleeve. The arcuate surface of the first ball head sleeve and the arcuate surface of the first ball crown push block are located on the same spherical surface, forming the ball head part of the first ball head rod. A through hole is provided in the middle of the first ball head sleeve. The first push rod is installed in the through hole in the middle of the first ball head sleeve and can move along the axis direction of the through hole, so as to bear external force and lock the ball joint.

4. The nine-degree-of-freedom ball hinge linkage locking universal rod bracket according to claim 3, characterized in that: The first connection structure includes an upper cover plate of the first joint, a lower cover plate of the first joint and a semi-slider; the semi-slider is movably installed inside the lower cover plate of the first joint, and the inner arc surface of the semi-slider is in ball contact with the first ball head rod; the upper cover plate of the first joint and the lower cover plate of the first joint are fixedly connected.

5. The nine-degree-of-freedom ball hinge linkage locking universal rod bracket according to claim 3, characterized in that: The second connection structure includes a joint tube, an upper end cover plate of the second joint part, a lower end cover plate of the second joint part and a slider; a slider is movably arranged in the joint tube, and the two end surfaces of the slider are respectively in contact with the middle ball head rod and the ball head part of the second ball head rod, and the upper end surface and the lower end surface of the joint tube are respectively provided with a second joint upper end cover plate and a second joint lower end cover plate; the second joint upper end cover plate and the second joint lower end cover plate are fixedly connected to the joint tube; the inner surface of the second joint upper end cover plate and the upper end surface of the slider together constitute a semi-enclosed space adapted to the ball head part of the middle ball head rod, for accommodating the ball head part of the middle ball head rod, thereby forming a ball hinge; the inner surface of the second joint lower end cover plate and the lower end surface of the slider together constitute a semi-enclosed space adapted to the ball head part of the second ball head rod, for accommodating the ball head part of the second ball head rod, thereby forming a ball hinge.

6. The nine-degree-of-freedom ball hinge linkage locking universal rod bracket according to claim 5, characterized in that: The intermediate ball head rod includes an intermediate ball head sleeve, a second ball crown push block and a second push rod. The upper end of the intermediate ball head sleeve is fixedly connected to the lower end cover of the upper joint, and the ball head end of the intermediate ball head sleeve is movably installed with the second ball crown push block. The arc surface of the intermediate ball head sleeve and the second ball crown push block are located on the same spherical surface as the arc surface of the second ball crown push block, forming the ball head part of the intermediate ball head rod; the second push rod is installed in the intermediate ball head sleeve, and the two ends of the second push rod are respectively attached to the bottom end of the semi-slider and the top end of the second ball crown push block; and the two ends of the second push rod are higher than the end faces of the through hole in the middle of the intermediate ball head sleeve and the lower end cover of the upper joint.

7. The nine-degree-of-freedom ball hinge linkage locking universal rod bracket according to claim 6, characterized in that: The structure of the second putter is a "putter structure" or a "putter + small ball combination structure of equal diameter".

8. The nine-degree-of-freedom ball hinge linkage locking universal rod bracket according to claim 5, characterized in that: The slider is transversely funnel-shaped, rectangular or circular.

9. The nine-degree-of-freedom ball hinge linkage locking universal rod bracket according to claim 1, characterized in that: The first joint part includes a first ball head rod and a second connection structure, wherein the first ball head rod is arranged on the upper side of the second connection structure and is spherically hinged with one end of the second connection structure; the intermediate ball head rod is a double-ended spherical structure, and the other end of the second connection structure is spherically hinged with one end of the intermediate ball head rod; The second joint part comprises a first connection structure and a solid rod; the other end of the intermediate ball head rod is ball-jointed with the first connection structure, and the bottom of the first connection structure is fixedly connected with the solid rod.

10. The nine-degree-of-freedom ball hinge linkage locking universal rod bracket according to claim 9, characterized in that: The intermediate ball head rod is a double-ended spherical structure, specifically including a second intermediate ball head sleeve, a third ball crown push block, a fourth ball crown push block and a third push rod. One end of the second intermediate ball head sleeve is movably mounted on the third ball crown push block, and the arc surface of one end of the second intermediate ball head sleeve and the arc surface of the third ball crown push block are located on the same spherical surface, forming an upper ball head portion of the intermediate ball head rod; the other end of the second intermediate ball head sleeve is movably mounted on the fourth ball crown push block, and the end arc surface of the other end of the second intermediate ball head sleeve and the arc surface of the fourth ball crown push block are located on the same spherical surface, forming a lower ball head portion of the intermediate ball head rod; the third push rod is installed in the second intermediate ball head sleeve, one end of the third push rod is in contact with the plane of the third ball crown push block, and the other end is in contact with the top plane of the fourth ball crown push block.

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