Cam lock type climbing aid

Abstract

The application discloses a cam locking type climbing device, which comprises a climbing platform, a supporting leg and a locking mechanism, the supporting leg is pivotally connected to the end of the climbing platform, the locking mechanism is arranged on the climbing platform, and the locking mechanism comprises a limiting rod which is arranged on the climbing platform and faces the supporting leg, the limiting rod is rotatably and slidably supported on the climbing platform, so that the limiting rod has two working states of extending locking and retreating unlocking, the limiting rod can automatically realize the unlocking and locking actions through the cooperation of a cam member and a radial protruding part, specifically, the limiting rod is rotated by external force, so that the limiting rod rotates with the radial protruding part, at this time, the radial protruding part slides along the cam acting surface, when the radial protruding part slides to a first arrival point, the limiting rod is driven to retreat and unlock, and when the radial protruding part slides to a second arrival point, the limiting rod is driven to extend and lock.

Description

Technical Field

[0001] This invention relates to the field of climbing equipment technology, and specifically to a cam-locking climbing equipment. Background Technology

[0002] Climbing equipment, such as workbenches, scaffolding, and ladders, are tools used in industry, construction, maintenance, and various daily activities to provide additional height. These devices are designed to safely elevate workers to the required height to perform specific tasks. Workbenches typically consist of a platform and four supporting legs, which can be fixed at different heights and are often equipped with guardrails and other safety features to protect the user.

[0003] Currently, most workbenches use locking pins to lock the tabletop and support legs. For example, patent document CN202410343471.6 discloses a multi-functional foldable workbench with a locking assembly on the front support leg. The locking pin engages with a locking seat on the tabletop body to lock the tabletop body, thus maintaining its unfolded state stably. When the folding leg assembly is folded, the front and rear support legs fit together, and the locking pin engages with a locking element to lock the folding leg assembly. Here, a single locking assembly can simultaneously lock both the tabletop body and the folding leg assembly, resulting in a simple and versatile structure. Furthermore, the folding leg assembly has a handle, making unfolding and folding easier.

[0004] The aforementioned patent documents disclose a technical solution for locking using a locking pin, but it still has limitations in practical use, as follows:

[0005] Because the locking pin is small and located below the tabletop, it engages with the locking hole on the tabletop to achieve locking and positioning.

[0006] Therefore, when locking, because the locking pin is small and located under the tabletop, the user needs to bend over or lean forward to operate it. The view is obstructed and the space for hand movement is limited, which can easily lead to inaccurate alignment between the locking pin and the locking hole. Especially when there is a slight misalignment between the support leg and the tabletop, the user needs to adjust repeatedly and press hard, which can easily lead to hand fatigue.

[0007] When unlocking, the locking pin is usually designed to be manually pulled out or rotated to unlock. However, due to its hidden location and the need for two-hand operation (such as one hand to hold the tabletop and the other hand to pull the locking pin), it is difficult to operate. It is difficult to respond quickly when it is necessary to store items to avoid them. Furthermore, once the locking pin is tilted in the locking hole, there is a lot of friction between the locking pin and the inner wall of the locking hole, which requires a lot of force to pull out, further increasing the difficulty of unlocking.

[0008] Therefore, how to overcome the shortcomings of the existing technology is the subject of this invention. Summary of the Invention

[0009] The present invention provides a cam-locking climbing device, which aims to solve the technical problems mentioned in the background art.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a cam-locking climbing device, comprising a climbing platform, a supporting leg, and a locking mechanism, wherein the supporting leg is pivotally connected to the end of the climbing platform; the locking mechanism is disposed on the climbing platform and includes a limiting rod, which extends from the climbing platform toward the supporting leg, and the limiting rod rotates and slides on the climbing platform, so that the limiting rod has two working states: extended locking and retracted unlocking; the supporting leg is provided with a locking hole corresponding to the end of the limiting rod, and the locking hole is configured to engage with the limiting rod when the supporting leg is in the supported state. The ends are aligned; the limiting rod has a radial protrusion, and a cam is fixedly mounted on the climbing platform corresponding to the radial protrusion. The cam has a cam action surface with a first arrival point and a second arrival point. The radial protrusion of the limiting rod is configured to abut against the cam action surface and slide along the cam action surface during the rotation of the limiting rod. When the limiting rod is rotated by external force, the limiting rod is driven to retract and unlock when the radial protrusion slides to the first arrival point, and the limiting rod is driven to extend and lock when the radial protrusion slides to the second arrival point.

[0011] The relevant content in the above plan is explained as follows:

[0012] In the above scheme, the limiting rod can be rotated or slid, allowing the user to unlock and lock the support leg simply by rotating the limiting rod.

[0013] In the above scheme, the locking hole aligns with the end of the limiting rod when the support leg is in the supported state. Simultaneously, a second locking hole Q is also provided on the support leg; when the support leg is in the retracted state, the second locking hole Q aligns with the end of the limiting rod.

[0014] In the above solution, when the support legs are stored, locking pins or other components can be installed on the side of the platform to fix the support legs.

[0015] In the above scheme, the cooperation principle between the cam component and the radial protrusion can be referred to the cylindrical cam mechanism.

[0016] In the above scheme, the limiting rod can automatically unlock and lock by the cooperation of the cam and the radial protrusion. Specifically, by rotating the limiting rod with external force, the limiting rod rotates with the radial protrusion. At this time, the radial protrusion slides along the working surface of the cam. When the radial protrusion slides to the first position, it drives the limiting rod to retract and unlock. When the radial protrusion slides to the second position, it drives the limiting rod to extend and lock.

[0017] In a further technical solution, the locking mechanism includes a first sleeve and a second sleeve arranged coaxially; both the first sleeve and the second sleeve are fixedly connected to the climbing platform and are respectively sleeved on both ends of the limiting rod, the limiting rod is configured to rotate around the axis of the first sleeve and the second sleeve, the axis being the rotation axis of the limiting rod; a cam element acts between the first sleeve and the second sleeve.

[0018] With the above design, the limiting rod can simultaneously perform rotation and sliding operations by being restricted by the first sleeve and the second sleeve (generally, only the first sleeve or the second sleeve can achieve this operation, but the stability is not enough).

[0019] In a further technical solution, the cam component includes a third sleeve coaxially arranged with the first sleeve and the second sleeve. The third sleeve is positioned and connected to the first sleeve, the second sleeve, or the platform. The longitudinal section of the third sleeve is approximately a right-angled trapezoidal structure. The inclined waist of the right-angled trapezoidal structure is the cam action surface, and the two ends of the inclined waist are the first arrival point and the second arrival point, respectively.

[0020] With the above design, the radial protrusion can slide along the cam's working surface, enabling rapid linear motion.

[0021] In a further technical solution, the limiting rod includes a rod body with a bent section formed by bending at a set angle; the bent section is disposed on the periphery of the rod body or at the end of the rod body; the bent section is a radial protrusion.

[0022] With the above design, the radial protrusion is integrated with the rod body, so there is no need to worry about damage to the radial protrusion.

[0023] A further technical solution is that both ends of the rod are bent at a set angle to form a first bent section and a second bent section; wherein, the end of the first bent section is integrally connected to the lock hole insertion end, and the end of the second bent section is integrally connected to a limiting section; of the lock hole insertion end and the limiting section, one is fitted inside the first sleeve, and the other is fitted inside the second sleeve.

[0024] With the above design, the positions of the lock hole insertion end and the limiting section are not fixed, that is, the fixed support leg is not fixed.

[0025] In a further technical solution, the locking mechanism further includes a reset member; the reset member is disposed in the first sleeve and / or the second sleeve, and the reset member is configured to act on the limiting rod so that the limiting rod has a tendency to slide in the direction of the locking hole.

[0026] The reset element is a spring, and with the above design, the limiting rod can automatically reset, so that the operator does not have to worry about forgetting to lock it.

[0027] In a further technical solution, the third sleeve is integrally formed with the first sleeve, and the cam action surface on the third sleeve is configured to correspond to the first bent section.

[0028] The above design allows for the use of no additional material for the third sleeve. Furthermore, the cam's working surface only needs to be located on the first sleeve.

[0029] A further technical solution is that the lower surface of the platform has a groove, and the locking mechanism is disposed within the groove;

[0030] The inner wall of the groove is provided with a receiving hole at the position corresponding to the insertion end of the lock hole, and the receiving hole is coaxially arranged with the first sleeve and the second sleeve.

[0031] The above design allows the locking mechanism to be concealed, while the receiving hole can also hold the insertion end of the lock hole in place, thus improving the stability of the limiting rod.

[0032] Working principle:

[0033] In the unlocked state, the second bent section is located at the first arrival point, while the lock hole extension end is outside the locking hole;

[0034] Subsequently, once it is necessary to lock the support leg, the support leg is first guided to rotate until the locking hole on it moves to align with the receiving hole. Then, the limiting rod automatically rotates around the rotation axis L. During this process, the second bending segment moves along the cam action surface from the first arrival point to the second arrival point and achieves positioning. During the rotation of the limiting rod, the limiting rod will also move the locking hole insertion end in a straight line toward the locking hole until the locking hole insertion end is translated into the locking hole.

[0035] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0036] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0037] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0038] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the case.

[0039] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0040] The working principle and advantages of this invention are as follows:

[0041] This invention enables the limiting rod to automatically unlock and lock through the cooperation of the cam component and the radial protrusion. Specifically, by rotating the limiting rod with external force, the limiting rod rotates along with the radial protrusion. At this time, the radial protrusion slides along the working surface of the cam. When the radial protrusion slides to the first endpoint, it drives the limiting rod to retract and unlock. When the radial protrusion slides to the second endpoint, it drives the limiting rod to extend and lock. Attached Figure Description

[0042] Appendix Figure 1 This is a schematic diagram of the support foot locking mechanism in an embodiment of the present invention;

[0043] Appendix Figure 2 for Figure 1 Enlarged view of section A in the image;

[0044] Appendix Figure 3 This is a front view schematic diagram of the support leg locking mechanism in an embodiment of the present invention when the support leg is locked;

[0045] Appendix Figure 4 This is a bottom view of the structure when the support leg locking mechanism locks the support leg in an embodiment of the present invention.

[0046] Appendix Figure 5 for Figure 4 Enlarged view of section B in the image;

[0047] Appendix Figure 6 This is a perspective view of the support foot locking mechanism in an embodiment of the present invention;

[0048] Appendix Figure 7 for Figure 6 Enlarged view of section C in the image;

[0049] Appendix Figure 8 This is a schematic diagram of the groove structure in an embodiment of the present invention;

[0050] Appendix Figure 9 for Figure 8 A magnified view of section D in the image.

[0051] In the attached diagrams: 1. Climbing platform; 2. Support leg; 3. Locking hole; 4. First sleeve; 5. Second sleeve; 6. Limiting rod; 7. Locking hole insertion end; 8. Cam component; 9. Radial protrusion; 10. Cam working surface; 11. First arrival point; 12. Second arrival point; 13. Third sleeve; 14. Rod body; 15. First bent section; 16. Second bent section; 17. Reset component; 18. Groove; 19. Accommodating hole;

[0052] L1, rotation axis; Q, second locking hole. Detailed Implementation

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0054] Example: The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the examples of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0055] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0056] See appendix Figures 1-9As shown, a cam-locking climbing device includes a climbing platform 1, a support leg 2, and a locking mechanism. The support leg 2 is pivotally connected to the end of the climbing platform 1. The locking mechanism is disposed on the climbing platform 1 and includes a limiting rod 6, which extends from the climbing platform 1 toward the support leg 2. The limiting rod 6 rotates and slides on the climbing platform 1, allowing it to have two working states: extended locking and retracted unlocking. The support leg 2 has a locking hole 3 corresponding to the end of the limiting rod 6. The locking hole 3 is configured to align with the end of the limiting rod 6 when the support leg 2 is in the supported state. A radial protrusion 9 is provided, and a cam member 8 is fixedly provided on the platform 1 corresponding to the radial protrusion 9. The cam member 8 is provided with a cam action surface 10, which has a first arrival point 11 and a second arrival point 12. The radial protrusion 9 of the limiting rod 6 is configured to abut against the cam action surface 10 and slide along the cam action surface 10 during the rotation of the limiting rod 6. When the limiting rod 6 is rotated by external force, when the radial protrusion 9 slides to the first arrival point 11, the limiting rod 6 is driven to retract and unlock, and when the radial protrusion 9 slides to the second arrival point 12, the limiting rod 6 is driven to extend and lock.

[0057] In this embodiment, the limiting rod 6 can be rotated or slid, so that the user can unlock and lock the support leg 2 simply by rotating the limiting rod 6.

[0058] In this embodiment, the locking hole 3 aligns with the end of the limiting rod 6 when the support leg 2 is in the supported state. A second locking hole Q can also be provided on the support leg 2. When the support leg 2 is in the retracted state, the second locking hole Q aligns with the end of the limiting rod 6. The second locking hole Q and the locking hole 3 are positioned around the rotation pivot of the support leg 2.

[0059] In this embodiment, when the support leg 2 is stored, the side of the platform 1 can be equipped with components such as locking pins to fix the support leg 2.

[0060] In this embodiment, the cooperation principle between the cam component 8 and the radial protrusion 9 can be referred to the cylindrical cam mechanism.

[0061] In this invention, the limiting rod 6 can automatically unlock and lock by the cooperation of the cam 8 and the radial protrusion 9. Specifically, by rotating the limiting rod 6 with external force, the limiting rod 6 rotates with the radial protrusion 9. At this time, the radial protrusion 9 will slide along the cam action surface 10. When the radial protrusion 9 slides to the first arrival point 11, it drives the limiting rod 6 to retract and unlock. When the radial protrusion 9 slides to the second arrival point 12, it drives the limiting rod 6 to extend and lock.

[0062] Preferably, the locking mechanism includes a first sleeve 4 and a second sleeve 5 arranged coaxially; the first sleeve 4 and the second sleeve 5 are both fixedly connected to the climbing platform 1 and respectively sleeved on both ends of the limiting rod 6. The limiting rod 6 is configured to rotate around the axis of the first sleeve 4 and the second sleeve 5, which is the rotation axis L1 of the limiting rod 6; the cam member 8 acts between the first sleeve 4 and the second sleeve 5.

[0063] With the above design, the limiting rod 6 can simultaneously perform rotation and sliding operations by being limited by the first sleeve 4 and the second sleeve 5 (generally, only the first sleeve 4 or the second sleeve 5 can achieve this operation, but the stability is not enough).

[0064] Preferably, the cam component 8 includes a third sleeve 13 coaxially arranged with the first sleeve 4 and the second sleeve 5. The third sleeve 13 is positioned and connected to the first sleeve 4, the second sleeve 5, or the platform 1. The longitudinal section of the third sleeve 13 is approximately a right-angled trapezoidal structure. The inclined waist of the right-angled trapezoidal structure is the cam action surface 10, and the two ends of the inclined waist are the first arrival point 11 and the second arrival point 12, respectively.

[0065] With the above design, the radial protrusion 9 can quickly achieve linear motion operation after sliding along the cam action surface 10.

[0066] Preferably, the limiting rod 6 includes a rod body 14, which has a bent section formed by bending at a set angle; the bent section is provided on the periphery of the rod body 14 or at the end of the rod body 14; the bent section is a radial protrusion 9.

[0067] With the above design, the radial protrusion 9 is integrally formed with the rod body 14, so there is no need to worry about damage to the radial protrusion 9.

[0068] Preferably, both ends of the rod 14 are bent at a set angle to form a first bent section 15 and a second bent section 16; wherein, the end of the first bent section 15 is integrally connected to the lock hole insertion end 7, and the end of the second bent section 16 is integrally connected to a limiting section; of the lock hole insertion end 7 and the limiting section, one is fitted inside the first sleeve 4, and the other is fitted inside the second sleeve 5.

[0069] With the above design, the positions of the lock hole insertion end 7 and the limiting section are not fixed, that is, the fixed support leg 2 is not fixed.

[0070] Preferably, the locking mechanism further includes a reset member 17; the reset member 17 is disposed within the first sleeve 4 and / or the second sleeve 5, and the reset member 17 is configured to act on the limiting rod 6 so that the limiting rod 6 has a tendency to slide in the direction of the locking hole 3.

[0071] The reset element 17 is a spring, and with the above design, the limiting rod 6 can automatically reset, so that the operator does not have to worry about forgetting to lock it.

[0072] Preferably, the third sleeve 13 is integrally formed with the first sleeve 4, and the cam action surface 10 on the third sleeve 13 is set corresponding to the first bent section 15.

[0073] With the above design, the third sleeve 13 does not require more material. Furthermore, the cam action surface 10 only needs to be set on the first sleeve 4.

[0074] Preferably, the lower surface of the climbing platform 1 has a groove 18, and the locking mechanism is disposed in the groove 18;

[0075] The inner wall of the groove 18 is provided with a receiving hole 19 at the position corresponding to the lock hole insertion end 7. The receiving hole 19 is coaxially arranged with the first sleeve 4 and the second sleeve 5.

[0076] The above design allows the locking mechanism to be hidden, while the receiving hole 19 can lock the insertion end 7 of the lock hole, thus improving the stability of the limiting rod 6.

[0077] Working principle:

[0078] For reference Figure 2 , Figure 5 and Figure 6 The reset component 17 will apply a force to the limiting rod 6, causing it to always tend to move in a straight line towards the supporting leg 2. The following is in conjunction with... Figure 5 Let's take an example to illustrate:

[0079] Rotate the support leg 2 to the supported state. At this time, the locking hole 3 on the support leg 2 is aligned with the receiving hole 19. Then, the locking hole insertion end 7 on the limiting rod 6 will extend into the locking hole 3, and the first bent section 15 will be located at the second arrival point 12. Figure 9The lowest point of the cam action surface 10 is reached. Then, once unlocking is required, the limiting rod 6 is manually driven to rotate around the rotation axis L1. Then, the first bent section 15 moves from the second reaching point 12 to the first reaching point 11 (i.e., from the lowest point of the cam action surface 10 to the highest point). At the same time, the locking hole insertion end 7 gradually slides out of the locking hole 3. Once it has fully slid out, the limiting rod 6 no longer needs to be rotated. At this time, the limiting rod 6 is in the retracted unlocked state. Then, the support leg 2 is rotated. When the axis of the locking hole 3 is not coaxial with the axis of the locking hole insertion end 7 (the axis of the locking hole insertion end 7 exceeds the edge of the locking hole 3. This is explained with the side surface of the support leg 2 closest to the platform 1 as the reference), the operator can release the limiting rod 6. At the same time, the support leg 2 is rotated to be flush with the platform 1 (i.e., the support leg 2 is folded up). Then, the locking hole insertion end 7 on the limiting rod 6 enters the second locking hole Q directly opposite under the action of the reset member 17, realizing automatic locking.

[0080] Subsequently, once the operator needs to rotate the support leg 2 to align the locking hole 3 with the receiving hole 19 (i.e., the support leg 2 is in the supported state again), the limiting rod 6 needs to be driven to the retracted unlocked state first, and then the support leg 2 is guided to the supported state. When the axis of the second locking hole Q is not coaxial with the axis of the locking hole insertion end 7 (the axis of the locking hole insertion end 7 exceeds the edge position of the second locking hole Q), the operator can release the limiting rod 6 so that the support leg 2 can rotate to align the locking hole 3 with the receiving hole 19. Then, the reset member 17 will push the locking hole insertion end 7 on the limiting rod 6 to automatically slide into the locking hole 3, and at the same time, the first bending section 15 reaches the second arrival point 12. At this time, the limiting rod 6 is in the extended locked state.

[0081] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A cam-locking climbing aid, characterized in that: It includes a platform (1), a support leg (2) and a locking mechanism, wherein the support leg (2) is pivotally connected to the end of the platform (1); The locking mechanism is installed on the platform (1). The locking mechanism includes a limiting rod (6), which is set from the platform (1) toward the support leg (2). The limiting rod (6) rotates and slides on the platform (1) so that the limiting rod (6) has two working states: extending for locking and retracting for unlocking. The support leg (2) is provided with a locking hole (3) corresponding to the end of the limiting rod (6). The locking hole (3) is configured to be aligned with the end of the limiting rod (6) when the support leg (2) is in the supported state. The limiting rod (6) is provided with a radial protrusion (9), and a cam (8) is fixedly provided on the platform (1) corresponding to the radial protrusion (9). The cam (8) is provided with a cam action surface (10), and the cam action surface (10) has a first arrival point (11) and a second arrival point (12). The radial protrusion (9) of the limiting rod (6) is configured to abut against the cam action surface (10) and slide along the cam action surface (10) during the rotation of the limiting rod (6); By rotating the limiting rod (6) by external force, when the radial protrusion (9) slides to the second stop point (12), the limiting rod (6) is driven to extend and lock, and when the radial protrusion (9) slides to the first stop point (11), the limiting rod (6) is driven to retract and unlock.

2. The cam lock climbing aid of claim 1, wherein: The locking mechanism includes a first sleeve (4) and a second sleeve (5) arranged coaxially. The first sleeve (4) and the second sleeve (5) are both fixedly connected to the climbing platform (1) and are respectively sleeved on both ends of the limiting rod (6). The limiting rod (6) is configured to rotate around the axis of the first sleeve (4) and the second sleeve (5), which is the rotation axis of the limiting rod (6). The cam (8) acts between the first sleeve (4) and the second sleeve (5).

3. The cam lock climbing aid of claim 2, wherein: The cam component (8) includes a third sleeve (13) coaxially arranged with the first sleeve (4) and the second sleeve (5). The third sleeve (13) is positioned and connected to the first sleeve (4) or the second sleeve (5) or the platform (1). The longitudinal section of the third sleeve (13) is approximately a right-angled trapezoidal structure. The inclined waist of the right-angled trapezoidal structure is the cam working surface (10), and the two ends of the inclined waist are the first arrival point (11) and the second arrival point (12), respectively.

4. The cam lock climbing aid of claim 3, wherein: The limiting rod (6) includes a rod body (14) with a bent section formed by bending at a set angle; The bent section is located on the periphery of the rod body (14) or at the end of the rod body (14); The bent section is a radial protrusion (9).

5. The cam lock climbing aid of claim 4, wherein: Both ends of the rod (14) are bent at a set angle to form a first bent section (15) and a second bent section (16). The end of the first bent section (15) is integrally connected to the lock hole insertion end (7) on the limiting rod (6), and the end of the second bent section (16) is integrally connected to the limiting section; of the lock hole insertion end (7) and the limiting section, one is fitted inside the first sleeve (4), and the other is fitted inside the second sleeve (5).

6. The cam lock climbing aid of claim 2, wherein: The locking mechanism also includes a reset component (17). The reset member (17) is disposed within the first sleeve (4) and / or the second sleeve (5), and the reset member (17) is configured to act on the limiting rod (6) so that the limiting rod (6) has a tendency to slide in the direction of the locking hole (3) at all times.

7. The cam lock climbing aid of claim 5, wherein: The third sleeve (13) is integrally formed with the first sleeve (4), and the cam action surface (10) on the third sleeve (13) is set corresponding to the first bent section (15).

8. The cam lock climbing aid of claim 5, wherein: The lower surface of the climbing platform (1) has a groove (18), and a locking mechanism is disposed in the groove (18); The inner wall of the groove (18) is provided with a receiving hole (19) at the position corresponding to the lock hole insertion end (7). The receiving hole (19) is coaxially arranged with the first sleeve (4) and the second sleeve (5).

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