Anti-interference servo motor butt joint structure and alignment platform with same

Abstract

The invention discloses an anti-interference servo motor butt joint structure and an alignment platform with the anti-interference servo motor butt joint structure, and relates to the technical field of mechanical connection.The anti-interference servo motor butt joint structure comprises a butt joint, a guide groove formed in the side face of the butt joint is used for containing a ball, and the ball is ejected out through an ejection block contained in an inner cavity of the butt joint. Through the collaborative design of mechanical triggering and hydraulic driving, when a butt joint is inserted into a butt joint groove, a pressure head is pressed to retract inwards to open a hydraulic channel in a linkage mode, a blocking pipe moves along with the pressure head to relieve sealing of a liquid passing groove, and hydraulic oil pushes a plunger through a channel formed by a pressure relief hole and the liquid passing groove; and hydraulic force is transmitted after an initial gap between the pushing block and the plunger is eliminated, so that the pushing block accurately ejects the ball out to be embedded into a ring groove of the butt joint groove, the uniqueness of an action time sequence is forcibly guaranteed, and collision damage caused by mistaken ejection of the ball during misalignment is avoided. And the plunger is allowed to slightly displace during hydraulic fluctuation or external impact so as to stabilize the pushing block, so that the pressure is effectively isolated, and the interference to the locking state of the ball is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical connection, and in particular to an anti-interference servo motor docking structure and an alignment platform with the structure. Background Art

[0002] In the field of mechanical connection, the common connection method between the servo motor and the clamping wind tooth mechanism is to connect the joint head with the joint groove. There is an axially slidable ejector block in the joint head, and its conical surface contacts the side ball. During normal operation, the power drives the ejector block to move, converting the axial force into radial force, so that the ball is embedded in the ring groove in the joint groove to achieve a stable connection.

[0003] However, the existing technology has defects. If the power system is accidentally intervened (such as control circuit failure, power source failure, mechanical shock, misoperation), the ball will extend prematurely when the docking joint is not correctly inserted. If the ball collides with the docking groove, the ball surface will easily deform due to local pressure, destroying the geometric accuracy, resulting in deviations in subsequent docking and affecting stability. Summary of the invention

[0004] One of the purposes of the present invention is to improve the problem in the prior art that during the docking process between the docking head and the docking groove, the ball bearing may be extended prematurely due to the accidental intervention of the power system, and may collide with the docking groove.

[0005] A second object of the present invention is to provide an alignment platform.

[0006] To achieve one of the above purposes, the present invention adopts the following technical solution: an anti-interference servo motor docking structure, in which a guide groove arranged on the side of the docking joint accommodates a ball, and the ball is ejected by a push block received in the inner cavity of the docking joint, and the push block is sleeved on a plunger sealed and received in the inner cavity of the docking joint, and a gap is provided between the two to allow axial movement, and a spring is provided at the rear end of the plunger.

[0007] The hydraulic pipeline equipped with the joint seals through the plunger. The front end of the hydraulic pipeline is a closed structure, and the circumferential surface of the front end is provided with a liquid groove communicating with the hydraulic pipeline.

[0008] The pressure head telescopically connected to the front end of the joint has a blocking tube abutting the plunger, and the rear end of the blocking tube is telescopically connected to the front end of the hydraulic pipeline to seal and block the liquid groove. The pressure relief hole set at the front end of the blocking tube is misaligned with the liquid groove when the pressure head is not retracted, and is aligned with the liquid groove to form a hydraulic passage after the pressure head is retracted to guide the hydraulic pressure to push the push block, thereby ejecting the ball.

[0009] In the above technical solution, the implementation method of the embodiment of the present invention is as follows: Initial state: the pressure head is not retracted, the blocking tube blocks the liquid groove, the hydraulic passage is not formed, and the spring restricts the plunger and does not drive the push block to apply force to the ball.

[0010] The pressure head shrinks under force: the butt joint is inserted into the butt groove, the pressure head shrinks under pressure, the blocking tube pushes the plunger to move, the gap between the push block and the plunger is eliminated, and the pressure relief hole is aligned with the liquid groove to form a hydraulic passage.

[0011] Transmission of hydraulic pressure after the hydraulic passage is formed: the hydraulic oil enters the relevant space through the passage, and the hydraulic pressure acts on the push block through the plunger, overcoming the spring force and causing the push block to move backward.

[0012] Ball ejection: The ejection block moves backward to push the ball out of the guide groove and fits into the ring groove of the docking groove to achieve docking locking. The distance of the ball ejected by the hydraulic pressure is adapted to the depth of the ring groove.

[0013] Reset after pressure is removed: the hydraulic oil is discharged, the joint is pulled out, the pressure is removed, the spring pushes the plunger and the pressure head to reset, the pressure relief hole is misaligned with the liquid channel, and the hydraulic passage is cut off; the push block is reset under the ball reset force; the ball is squeezed and reset when it leaves the ring groove, hidden in the guide groove, and the structure returns to the initial state. In addition, the ball can be stabilized in the guide groove through the air pressure in the joint cavity or other mechanical limit structures.

[0014] The beneficial effects of the present invention are: First, through the coordinated design of mechanical triggering and hydraulic drive, when the butt joint is inserted into the butt joint groove, the pressure head is compressed and retracted to open the hydraulic passage. The blocking tube moves with the pressure head to release the seal of the liquid groove. The hydraulic oil pushes the plunger through the passage formed by the pressure relief hole and the liquid groove, and the initial gap between the push block and the plunger is eliminated. After that, the liquid pressure is transmitted, so that the push block accurately pushes the ball into the annular groove of the butt joint groove, forcibly ensuring the uniqueness of the action sequence and avoiding collision damage caused by the ball being accidentally ejected when misaligned.

[0015] Secondly, the axial clearance design between the push block and the plunger is combined with a spring reset mechanism, which allows the plunger to move slightly to stabilize the push block when the hydraulic pressure fluctuates or external impacts occur, effectively isolating the pressure and reducing interference with the ball locking state. At the same time, the hydraulic passage is automatically cut off as the pressure head is reset to achieve on-demand energy supply and self-locking, which significantly improves the anti-interference ability and long-term stability of the docking process.

[0016] Furthermore, in an embodiment of the present invention, a clearance of not less than 10 mm is provided between the push block and the plunger to allow axial movement.

[0017] Furthermore, in an embodiment of the present invention, the compression stroke of the pressure head triggers the axis of the liquid passage groove to coincide with the axis of the pressure relief hole, and the threshold pressure of the hydraulic passage conduction formed is 2-5 MPa.

[0018] Furthermore, in an embodiment of the present invention, the depth of the guide groove is 1 / 3-1 / 2 of the diameter of the ball, and the groove opening of the guide groove is rounded.

[0019] Furthermore, in an embodiment of the present invention, a guide key is provided on the inner wall of the blocking tube, and the guide key cooperates with a guide limit groove provided on the outer wall of the hydraulic pipeline to limit the rotation and outward movement of the pressure head.

[0020] Furthermore, in the embodiment of the present invention, the blocking tube and the hydraulic pipeline, the plunger and the inner cavity of the docking joint, and the pressure head and the inner cavity of the docking joint are all sealed by sealing rings.

[0021] Furthermore, in an embodiment of the present invention, the surface of the push block in contact with the ball is a conical surface with a taper of 45°-60°.

[0022] Furthermore, in an embodiment of the present invention, the surface of the ball is coated with a titanium nitride wear-resistant layer with a thickness of 10-20 μm.

[0023] Furthermore, in an embodiment of the present invention, the ball is stabilized in the guide groove by the air pressure in the inner cavity of the docking joint, or the ball is stabilized in the guide groove by providing a retaining ring or a retaining spring in the guide groove.

[0024] In order to achieve the second of the above-mentioned purposes, the present invention adopts the following technical solutions: an alignment platform, which has the anti-interference servo motor docking structure described in one of the above-mentioned invention purposes, and the alignment platform also has a hydraulic seat, a clamping wind tooth mechanism and a servo motor body, the telescopic end of the servo motor body is fixed to the back end of the hydraulic seat, the docking head of the anti-interference servo motor docking structure is fixed to the front end of the hydraulic seat, the side end of the hydraulic seat is provided with a hydraulic oil hole for guiding the hydraulic oil, the hydraulic oil hole is connected with the hydraulic pipeline in the docking head, the back end of the clamping wind tooth mechanism is provided with a docking groove matching with the docking head, and the inner wall surface of the docking groove is provided with an annular groove matching with the ball in the docking head. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a three-dimensional schematic diagram of an alignment platform according to an embodiment of the present invention.

[0026] Figure 2 It is a three-dimensional schematic diagram of a servo motor and a wind tooth clamping mechanism according to an embodiment of the present invention.

[0027] Figure 3 It is a schematic diagram of the anti-interference servo motor docking structure according to an embodiment of the present invention.

[0028] Figure 4It is a partial schematic diagram of the anti-interference servo motor docking structure according to an embodiment of the present invention.

[0029] 10. Butt joint, 11. Ball, 12. Hydraulic pipeline, 12.1. Liquid channel, 12.2. Guide limit groove, 13. Pressure head, 13.1. Blocking pipe; 20. plunger, 21. push block, 22. spring; 30. Hydraulic seat, 31. Hydraulic oil hole; 100. Wind tooth clamping mechanism. 200. Servo motor body. DETAILED DESCRIPTION

[0030] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "one", "first", "second", "third", "fourth", "fifth", "sixth" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] For the purpose of simplicity and explanation, the principles of the embodiments are mainly described by reference to examples. In the following description, many specific details are presented to provide a thorough understanding of the embodiments. However, it is obvious that for ordinary technicians in this field, these embodiments may not be limited to these specific details in practice. In some instances, the well-known mechanical sealing methods and structures applied between the submarine center shaft and the body are not described in detail to avoid making these embodiments unnecessarily difficult to understand. In addition, all embodiments can be used in combination with each other. Example 1

[0034] It should be noted that the drawings in the specification are the contents of the specification. The structural shapes, connection relationships, matching relationships, and positional relationships that can be obtained without any doubt in the drawings in the specification should be understood as the contents of the specification.

[0035] An anti-interference servo motor docking structure, such as Figure 3 , Figure 4 As shown, the guide groove arranged on the side of the butt joint 10 accommodates the ball 11, and the ball 11 is ejected by the push block 21 received in the inner cavity of the butt joint 10. The push block 21 is mounted on the plunger 20 which is sealed and received in the inner cavity of the butt joint 10, and there is a gap between the two to allow axial movement. The existence of this gap provides a certain activity space for subsequent actions. In addition, the rear end of the plunger 20 is equipped with a spring 22, which plays a reset role in the entire structure and provides the necessary conditions for the cyclic action of the structure.

[0036] like Figure 4 As shown, the hydraulic pipeline 12 provided to the joint 10 penetrates the plunger 20 in a sealed manner. This penetration method ensures the flow of hydraulic oil in the pipeline and also forms a relatively stable connection relationship between the hydraulic pipeline 12 and the plunger 20.

[0037] The front end of the hydraulic pipeline 12 is a closed structure, and the circumferential surface of the front end is provided with a liquid-passing groove 12.1 which is in communication with the hydraulic pipeline 12. The function of the liquid-passing groove 12.1 is to allow the hydraulic oil to flow out under certain conditions, thereby driving other components to move.

[0038] The pressure head 13 telescopically connected to the front end of the joint 10 has a blocking tube 13.1 abutting against the plunger 20. The rear end of the blocking tube 13.1 is telescopically connected to the front end of the hydraulic pipeline 12 to seal and block the liquid groove 12.1. The pressure relief hole set at the front end of the blocking tube 13.1 is misaligned with the liquid groove 12.1 when the pressure head 13 is not retracted. After the pressure head 13 is retracted, it is aligned with the liquid groove 12.1 to form a hydraulic passage to guide the hydraulic pressure to push the ejection block 21, thereby ejecting the ball 11.

[0039] The implementation method of the anti-interference servo motor docking structure is as follows: Initial state: The pressure head 13 is not retracted, and the blocking tube 13.1 seals and blocks the liquid groove 12.1. The pressure relief hole set at the front end of the blocking tube 13.1 is misaligned with the liquid groove 12.1. The hydraulic oil in the hydraulic pipeline 12 cannot flow out through the liquid groove 12.1, and the hydraulic passage is not formed.

[0040] The spring 22 disposed between the plunger 20 and the inner cavity of the docking head 10 is in a natural state (or has a certain preload force). The plunger 20 , under the force restriction of the spring 22 , does not drive the ejection block 21 to exert ejection pressure on the ball 11 .

[0041] The pressure head 13 shrinks under the force: When the docking joint 10 is inserted into the docking groove and the bottom wall of the docking groove compresses the pressure head 13 to shrink toward the inner cavity of the docking joint 10, the plunger 20 pushed by the blocking tube 13.1 also moves accordingly, eliminating the gap between the push block 21 and the plunger 20 that allows axial movement. At the same time, the pressure relief hole set at the front end of the blocking tube 13.1 is gradually aligned with the liquid groove 12.1 to form a hydraulic passage.

[0042] Hydraulic pressure transmission after the hydraulic passage is formed: Since the hydraulic pipeline 12 is provided with a hydraulic pipeline 12 that seals and penetrates the plunger 20, and the front end of the hydraulic pipeline 12 is a closed structure, when the pressure relief hole is aligned with the liquid passage groove 12.1 to form a hydraulic passage, the hydraulic oil enters the space between the pressure head 13 and the plunger 20 from the hydraulic pipeline 12 through the liquid passage groove 12.1 and the pressure relief hole, and the hydraulic pressure acts on the push block 21 through the plunger 20 to overcome the force of the spring 22 (and other possible resistances), so that the push block 21 moves backward.

[0043] Ball 11 ejection: During the backward movement of the push block 21, the ball 11 originally contained in the guide groove is pushed out, and the ball 11 is inserted into the annular groove of the docking groove to achieve docking and locking with the docking groove. The distance of the ball 11 pushed out by the hydraulic pressure is adapted to the depth of the annular groove.

[0044] Reset after pressure removal: After the hydraulic oil is discharged from the space between the pressure head 13 and the plunger 20, the docking head 10 is pulled out. At this time, the pressure exerted on the pressure head 13 by the bottom wall of the docking groove is cancelled. Since the spring 22 arranged between the plunger 20 and the inner cavity of the docking head 10 is elastic, the spring 22 will push the plunger 20 and the pressure head 13 forward and reset, and the pressure relief hole and the liquid passage groove 12.1 are misaligned again, and the hydraulic passage is cut off.

[0045] The push block 21 sleeved thereon is reset accordingly by the restoring force of the ball 11 , and a gap allowing axial movement appears between the push block 21 and the plunger 20 .

[0046] When the ball 11 is separated from the annular groove of the docking groove, the arc surface of the slide groove squeezes the ball 11, so that the ball 11 is reset and pushes the push block 21 to reset, and the push block 21 hides itself in the guide groove again, and the entire docking structure returns to the initial state, waiting for the next working cycle.

[0047] The ball 11 is stabilized in the guide groove by the air pressure in the inner cavity of the joint 10, or by other existing mechanical limiting structures, which is not limited in the present invention.

[0048] One of the purposes of the present invention is to, through the coordinated design of mechanical triggering and hydraulic drive, when the docking joint 10 is inserted into the docking groove, the pressure head 13 is compressed and retracted to open the hydraulic passage, and the blocking tube 13.1 moves with the pressure head 13 to release the seal of the liquid groove 12.1, and the hydraulic oil pushes the plunger 20 through the passage formed by the pressure relief hole and the liquid groove 12.1, and the hydraulic pressure is transmitted after the initial gap between the push block 21 and the plunger 20 is eliminated, so that the push block 21 accurately pushes the ball 11 out and embeds it into the annular groove of the docking groove, thereby forcing the uniqueness of the action sequence to avoid collision damage caused by the ball 11 being accidentally ejected when misaligned.

[0049] The second purpose of the present invention is to combine the axial clearance design between the push block 21 and the plunger 20 with the reset mechanism of the spring 22, so as to allow the plunger 20 to be slightly displaced to stabilize the push block 21 when the hydraulic pressure fluctuates or external impacts occur, thereby effectively isolating the pressure and reducing the interference with the locking state of the ball 11. At the same time, the hydraulic passage is automatically cut off as the pressure head 13 is reset to realize on-demand energy supply and self-locking, which significantly improves the anti-interference ability and long-term stability of the docking process.

[0050] Specifically, Figure 4 As shown, a clearance of not less than 10 mm is provided between the push block 21 and the plunger 20 to allow axial movement. The plunger 20 is allowed to move forward slightly under hydraulic fluctuations or instantaneous impacts (such as oil pressure pulsation), avoiding frequent vibration of the push block 21 and ensuring the position stability of the ball 11 after being ejected.

[0051] Specifically, the compression stroke of the pressure head 13 triggers the axis of the liquid groove 12.1 to coincide with the axis of the pressure relief hole, and the threshold pressure of the hydraulic passage formed is 2-5Mpa, ensuring that the hydraulic passage is opened only after the joint 10 is fully inserted, to prevent the ball 11 from being ejected when it is not aligned.

[0052] Specifically, Figure 3 As shown, the depth of the guide groove is 1 / 3-1 / 2 of the diameter of the ball 11, and the groove of the guide groove is rounded.

[0053] Specifically, Figure 4As shown, the inner wall of the blocking tube 13.1 is provided with a guide key (not shown), which cooperates with the guide limit groove 12.2 provided on the outer wall of the hydraulic pipeline 12 to limit the rotation and outward movement of the pressure head 13. It not only prevents the pressure head 13 from rotating to cause the pressure relief hole and the liquid passage groove 12.1 to be misaligned, ensures the precise alignment of the hydraulic passage, but also limits the outward movement of the pressure head 13 to avoid excessive stretching of the sealing ring or separation from the inner cavity of the docking head 10.

[0054] Specifically, Figure 4 As shown, sealing rings are used to seal the blocking tube 13.1 and the hydraulic pipeline 12, the plunger 20 and the inner cavity of the docking joint 10, and the pressure head 13 and the inner cavity of the docking joint 10 to prevent the hydraulic oil from leaking to the non-working area and maintain the system pressure stability.

[0055] Specifically, the surface of the push block 21 in contact with the ball 11 is a conical surface with a taper of 45°-60°. The conical surface converts the axial hydraulic driving force of the plunger 20 into the radial ejection force of the ball 11, and the cone angle range balances the transmission efficiency and the stability of the movement trajectory of the ball 11.

[0056] Specifically, the surface of the ball 11 is coated with a titanium nitride wear-resistant layer with a thickness of 10-20 μm.

[0057] Specifically, the ball 11 is stabilized in the guide groove by the air pressure in the inner cavity of the joint 10, or the ball 11 is stabilized in the guide groove by arranging a retaining ring or a retaining spring in the guide groove. Example 2

[0058] A aligning platform, such as Figure 1 , Figure 2 As shown, the alignment platform has the anti-interference servo motor docking structure in the above-mentioned embodiment 1, and the alignment platform also has a hydraulic seat 30, a clamping wind tooth mechanism 100 and a servo motor body 200. The telescopic end of the servo motor body 200 is fixed to the back end of the hydraulic seat 30, and the docking head 10 of the anti-interference servo motor docking structure is fixed to the front end of the hydraulic seat 30. The side end of the hydraulic seat 30 is provided with a hydraulic oil hole 31 for guiding the hydraulic oil, and the hydraulic oil hole 31 is connected with the hydraulic pipeline 12 in the docking head 10. The back end of the clamping wind tooth mechanism 100 is provided with a docking groove matching with the docking head 10, and the inner wall surface of the docking groove is provided with an annular groove matching with the ball 11 in the docking head 10.

[0059] Although the above describes the illustrative specific embodiments of the present invention so that those skilled in the art can understand the present invention, the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, all inventions and creations using the concepts of the present invention are protected.

Claims

1. An anti-interference servo motor docking structure, wherein a guide groove arranged on the side of the docking joint accommodates a ball, and the ball is ejected by a push block received in the inner cavity of the docking joint, characterized in that: The push block is sleeved on the plunger which is sealed and accommodated in the inner cavity of the butt joint, and a gap is provided between the two to allow axial movement, and a spring is provided at the rear end of the plunger; The hydraulic pipeline provided with the joint sealably penetrates the plunger, the front end of the hydraulic pipeline is a closed structure, and the circumferential surface of the front end is provided with a liquid passage groove communicated with the hydraulic pipeline; The pressure head telescopically connected to the front end of the joint has a blocking tube abutting the plunger, and the rear end of the blocking tube is telescopically connected to the front end of the hydraulic pipeline to seal and block the liquid groove. The pressure relief hole set at the front end of the blocking tube is misaligned with the liquid groove when the pressure head is not retracted, and is aligned with the liquid groove to form a hydraulic passage after the pressure head is retracted to guide the hydraulic pressure to push the push block, thereby ejecting the ball.

2. The anti-interference servo motor docking structure according to claim 1, characterized in that: A clearance of not less than 10 mm is provided between the push block and the plunger to allow axial movement.

3. The anti-interference servo motor docking structure according to claim 1, characterized in that: The compression stroke of the pressure head triggers the axis of the liquid passage groove to coincide with the axis of the pressure relief hole, and the threshold pressure of the hydraulic passage formed is 2-5 MPa.

4. The anti-interference servo motor docking structure according to claim 1, characterized in that: The depth of the guide groove is 1 / 3-1 / 2 of the diameter of the ball, and the groove opening of the guide groove is rounded.

5. The anti-interference servo motor docking structure according to claim 1, characterized in that: The inner wall of the blocking tube is provided with a guide key, and the guide key cooperates with the guide limit groove provided on the outer wall of the hydraulic pipeline to limit the rotation and outward movement of the pressure head.

6. The anti-interference servo motor docking structure according to claim 1, characterized in that: The blocking tube and the hydraulic pipeline, the plunger and the inner cavity of the docking joint, and the pressure head and the inner cavity of the docking joint are sealed by sealing rings.

7. The anti-interference servo motor docking structure according to claim 1, characterized in that: The surface where the push block contacts the ball is a conical surface with a taper of 45°-60°.

8. The anti-interference servo motor docking structure according to claim 1, characterized in that: The surface of the ball is coated with a titanium nitride wear-resistant layer with a thickness of 10-20 μm.

9. The anti-interference servo motor docking structure according to claim 1, characterized in that: The ball is stabilized in the guide groove by the air pressure in the inner cavity of the butt joint, or the ball is stabilized in the guide groove by arranging a retaining ring or a retaining spring in the guide groove.

10. An alignment platform, characterized in that: The alignment platform has the anti-interference servo motor docking structure described in any one of claims 1 to 9 above, and the alignment platform also has a hydraulic seat, a clamping wind tooth mechanism and a servo motor body. The telescopic end of the servo motor body is fixed to the back end of the hydraulic seat, and the docking head of the anti-interference servo motor docking structure is fixed to the front end of the hydraulic seat. The side end of the hydraulic seat is provided with a hydraulic oil hole for guiding the hydraulic oil, and the hydraulic oil hole is connected to the hydraulic pipeline in the docking head. The back end of the clamping wind tooth mechanism is provided with a docking groove that matches the docking head, and the inner wall surface of the docking groove is provided with an annular groove that matches the ball in the docking head.

Images