A right and left thread locking fastener and installation tool

Abstract

The utility model provides a right and reverse thread locking fastener and installation tool, including bolt main part, primary nut and secondary nut, bolt main part outer periphery is equipped with adjacent and opposite rotation right outer thread section and reverse outer thread section, right outer thread section diameter is greater than reverse outer thread section diameter. Primary nut is equipped with and right inner thread of right outer thread section cooperation. Secondary nut is equipped with and reverse inner thread of reverse outer thread section cooperation. Secondary nut lower extreme outside is equipped with at least one first deformation lug, and primary nut upper extreme outside is equipped with and first locking groove of first deformation lug cooperation. Bolt main part end part is equipped with second locking groove, and secondary nut upper extreme outer periphery is equipped with at least one second deformation lug. The utility model sets up opposite rotation right and reverse thread section, and has built double mechanical locking mechanism, improves anti -loose performance, can adapt more for the more severe vibration working condition.

Description

Technical Field

[0001] This utility model belongs to the field of fastener technology, specifically relating to a positive and negative threaded locking fastener and its installation tool. Background Technology

[0002] In high-end equipment fields such as aerospace, rail transportation, and heavy machinery, the reliability and safety requirements for fastening connections are extremely high. Ordinary single-nut fasteners are prone to loosening under long-term vibration loads, which may lead to serious consequences.

[0003] Existing technologies widely employ fasteners with alternating positive and negative threads. Their anti-loosening principle is as follows: when two nuts with opposite threads are tightened, their adjacent end faces are pressed together, and they restrain each other through static friction. When an external load tends to cause the fastener system to loosen, the tendency of one nut to loosen is transmitted to the other nut through the static friction between the contact surfaces. Because the threads are opposite, the loosening direction of the first nut is precisely the tightening direction of the second nut, preventing overall loosening. However, this anti-loosening mechanism relies on the static friction between the nuts. Under severe vibration, the contact surfaces may experience slight relative slippage or "bouncing," causing a momentary decrease or loss of static friction, disrupting the force transmission and creating the possibility of loosening.

[0004] Therefore, the above problems urgently need to be solved. Utility Model Content

[0005] Purpose of the utility model: In order to overcome the above shortcomings, this utility model provides a fastener with positive and negative thread locking, which can achieve a controllable and low-damage mechanical locking, and establish a rigid interlock between the primary nut and the secondary nut. It also provides a special tool that can complete the final tightening of the fastener in one operation, solving the problem of excessive torque when locking multiple points at the same time, and ensuring installation quality and efficiency.

[0006] Technical Solution: To achieve the above objectives, this utility model provides a reversible threaded fastener, comprising a bolt body, a primary nut, and a secondary nut. The bolt body has adjacent, oppositely oriented external thread segments and reverse external thread segments on its outer periphery, with the diameter of the external thread segment being larger than the diameter of the reverse external thread segment. The primary nut has a positive internal thread that mates with the positive external thread segment. The secondary nut has a reverse internal thread that mates with the reverse external thread segment.

[0007] The lower end of the secondary nut is fitted onto the upper end of the primary nut.

[0008] The lower outer side of the secondary nut is provided with at least one first deformation lug, and the upper outer side of the primary nut is provided with a first locking groove that mates with the first deformation lug. When the first deformation lug is subjected to radial compression, the first deformation lug deforms and gets stuck in the first locking groove.

[0009] The bolt body has a second locking groove at its end, and the upper outer circumference of the secondary nut has at least one second deformation lug. When the second deformation lug is subjected to radial compression, it deforms and gets stuck in the second locking groove.

[0010] This invention creates a reverse-threaded structure by setting opposite-direction thread segments on the outside of the bolt body, which, together with a primary nut and a secondary nut, form a double mechanical rigid locking mechanism. Then, through the engagement of the first deformation lug with the first locking groove and the second deformation lug with the second locking groove, a double mechanical rigid locking mechanism is constructed.

[0011] When the first deformation lug of the secondary nut deforms under radial compressive force and gets stuck in the first locking groove of the primary nut, the primary nut and the secondary nut form an engagement, which can effectively prevent relative rotation between the two. Even if the contact surface friction fluctuates or is lost due to severe vibration, the locking state can be maintained, which significantly improves the reliability of anti-loosening.

[0012] The second locking groove at the end of the bolt body and the second deformation lug of the secondary nut further rigidly lock the secondary nut to the bolt body, preventing the secondary nut from loosening or rotating relative to the bolt body. This indirectly locks the position of the primary nut, forming a double mechanical lock. Compared with the traditional anti-loosening structure that relies solely on friction, the anti-loosening effect of this invention is more durable and stable, and can adapt to more severe vibration conditions.

[0013] Meanwhile, locking groove designs can compromise the integrity of the thread, thus affecting the load-bearing capacity of the fastener. This invention places the locking groove at the connection end between the bolt body and the secondary nut, as well as on the outer periphery of the primary nut. This does not disrupt the structural integrity of the forward external thread section. As the primary nut provides the main locking force, its threaded connection with the bolt body is unaffected by the locking groove, ensuring sufficient load-bearing capacity. Furthermore, to allow the deformation lug to deform during the locking process and embed into the locking groove, the nut needs a certain deformation capacity. This affects the choice of nut material, reducing its structural strength and consequently impacting load-bearing capacity. This invention places the deformation parts (first and second deformation lugs) on the secondary nut, while the primary nut, as the main load-bearing component, remains unaffected by the material selection, still allowing the use of materials with high structural strength. This ensures that the overall load-bearing strength of the fastener is not affected by the deformation design. The engagement between the secondary nut and the reverse external thread section primarily serves as an anti-loosening locking mechanism. This design ensures both the strength requirements of the connection and optimizes the functional allocation of the anti-loosening structure. If the first and second deformation lugs are respectively set on the primary and secondary nuts, the preload provided by the primary nut when locking depends on the deformation force of the first deformation lug. This can easily lead to insufficient preload, affecting the tightening effect. Deformation of the deformation lug will damage the nut's structure, which in turn will affect the overall structural strength of the nut and the tightening effect.

[0014] The internal structure of the secondary nut features a wrapping cavity, a travel cavity, and a engagement cavity extending along its axis, with gradually decreasing inner diameters. The wrapping cavity has a larger inner diameter, effectively wrapping the upper end of the primary nut. The travel cavity effectively avoids the larger diameter forward external thread section. It provides working space when the thickness of the connected parts changes, preventing jamming. The reverse internal thread on the inner wall of the engagement cavity mates with the reverse external thread section, achieving threaded connection with the bolt body.

[0015] Furthermore, in the aforementioned threaded locking fastener, the first locking groove is arranged around the first-stage nut, and the distance between adjacent first locking grooves is less than the width of the first locking groove. The second locking groove is arranged around the outer periphery of the bolt body, and the distance between adjacent second locking grooves is less than the width of the second locking groove. The above structure forms a continuous locking surface, ensuring that the deformation lug is embedded in the locking groove and can be directly locked under optimal preload. It ensures that the deformation lug is partially or completely embedded in the locking groove, providing multiple locking mechanisms, and always engaging within the slope or protection range of a certain locking groove, preventing engagement failure.

[0016] Furthermore, in the aforementioned threaded locking fasteners, multiple first and second deformation lugs are provided, and they are all evenly distributed along the circumference of the secondary nut. This structural arrangement allows each lug to be evenly stressed and deform synchronously, forming a locking force distributed along the circumference, thereby improving the locking stability and reliability of the overall structure.

[0017] Furthermore, in the aforementioned positive and negative threaded locking fasteners, the outer surface of the first deformable lug is designated as a guide surface. The width of the first deformable lug is such that it forms an interference fit with the groove wall when it deforms and engages with the first locking groove. The guide surface is either an arc-shaped surface or an inwardly inclined slope. The guide surface smoothly guides the lug deformation, efficiently converting radial compressive force into deformation and displacement, significantly reducing the torque required for locking operations, making installation easier and smoother. The interference fit completely eliminates the play between the lug and the locking groove, forming a rigid interlock without loosening.

[0018] Furthermore, in the aforementioned positive and negative threaded locking fasteners, the outer surface of the second deformable lug is designated as a guide surface, and the width of the second deformable lug is such that it forms an interference fit with the groove wall when it deforms and engages with the second locking groove. Similarly, the guide surface is designated as an arc-shaped surface or an inwardly inclined slope.

[0019] Furthermore, in the aforementioned threaded fasteners, the primary nut has a hexagonal cross-section at the end furthest from the secondary nut to facilitate wrench use. This structure allows the operator to independently tighten the primary nut using a standard wrench, precisely applying the specified preload torque to establish clamping force between the fastener and the connecting plate. When installing the secondary nut, fixing the hexagonal head effectively prevents the bolt body from rotating.

[0020] An installation tool for installing the aforementioned threaded fasteners includes a sleeve body and a force-applying tool that cooperates with the sleeve body. The sleeve body has a lower chamber and an upper chamber coaxially connected inside. The inner walls of the upper chamber and the lower chamber are respectively configured to cooperate with the upper and lower outer circumferences of the secondary nut to transmit torque.

[0021] The inner wall of the lower chamber is provided with multiple first force-applying parts, and the inner wall of the upper chamber is provided with multiple second force-applying parts.

[0022] When the sleeve body is fitted onto the secondary nut, the first force-applying part and the second force-applying part are respectively positioned opposite to the first deformation lug and the second deformation lug in the circumferential direction.

[0023] When the sleeve body rotates around the axis, the side wall of the first force-applying part presses against the first deformation lug, causing it to deform and lock into the first locking groove, and the side wall of the second force-applying part presses against the second deformation lug, causing it to deform and lock into the second locking groove.

[0024] Furthermore, in the aforementioned installation tool, the initial circumferential gap between the sidewall of the first force-applying part and the first deformable lug is smaller than the initial circumferential gap between the sidewall of the second force-applying part and the second deformable lug.

[0025] During the rotation of the sleeve body, the first force-applying part contacts the corresponding deformation lug before the second force-applying part and begins to compress, so that the first deformation lug and the second deformation lug are deformed and locked in stages.

[0026] In the initial stage of sleeve body rotation, the first force-applying part contacts and compresses the first deformation lug, causing it to undergo plastic deformation and engage in the first locking groove of the primary nut, completing the initial mechanical locking between the secondary nut and the primary nut. As the sleeve body continues to rotate, after overcoming the deformation resistance of the first deformation lug, the sidewall of the second force-applying part begins to contact the second deformation lug and gradually applies compressive force. Since the first stage of locking has fixed the secondary nut and the primary nut relatively, the compression of the second deformation lug now acts directly between the secondary nut and the bolt body, causing the second deformation lug to deform and engage in the second locking groove at the end of the bolt body, completing the final mechanical locking between the secondary nut and the bolt body. This staged locking mechanism decomposes the torque that originally needed to overcome the deformation resistance of two deformation lugs simultaneously into two independent torques acting sequentially, effectively reducing the maximum torque value required for a single operation and avoiding the problems of excessive load on the force-applying tool, difficult operation, or even damage to the fasteners caused by simultaneous locking at multiple points. The operator only needs to complete the double locking in sequence through one continuous rotation operation, simplifying the installation steps and improving installation efficiency.

[0027] Furthermore, in the aforementioned installation tool, the first force-applying part and the second force-applying part are respectively arc-shaped notches formed on the inner wall of the sleeve body.

[0028] The arc-shaped notch has a simple structure and is easy to process and form. Its arc-shaped sidewalls form a smooth contact with the outer surface of the deformable lug, which can evenly transmit the extrusion force during the extrusion process and avoid excessive damage or breakage to the deformable lug.

[0029] Furthermore, in the aforementioned installation tool, the inner wall cross-sectional profile of the upper chamber is triangular, with its corner regions forming the second force-applying portion. The inner wall cross-sectional profile of the lower chamber is circular, with its recessed areas forming the first force-applying portion.

[0030] As can be seen from the above technical solution, this utility model has the following beneficial effects: ① This utility model of a reverse threaded fastener provides anti-loosening protection without relying on friction by using the reverse thread direction of the primary nut and the secondary nut, combined with the mechanical interlocking formed by the deformation lug and the locking groove. It solves the problem of traditional fasteners loosening due to the decay of preload under severe vibration.

[0031] ② This utility model of a positive and negative threaded locking fastener ensures the integrity of the primary nut structure, which plays the main load-bearing function, and the integrity of the thread engaging with the primary nut. It concentrates the deformation locking function in the secondary nut, separates the main load-bearing function from the anti-loosening locking function, ensures connection strength, and achieves a balance between load-bearing capacity and anti-loosening performance.

[0032] ③ The installation tool, through different initial gap designs, can complete two-stage locking in an orderly manner in a single continuous rotation operation, reducing the peak installation torque and operational difficulty. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the positive and negative threaded fastener of this utility model; Figure 2 This is a front view of the bolt body; Figure 3 This is a schematic diagram of the structure of the primary nut; Figure 4 This is a schematic diagram of the structure of the secondary nut; Figure 5 This is a schematic diagram of the structure of the sleeve body; Figure 6 This is a bottom view of the sleeve body; Figure 7 This is a schematic diagram showing the engagement state of the first force-applying part and the first deformable lug; Figure 8 This is a schematic diagram showing the engagement state of the second force-applying part and the second deformed lug.

[0034] In the diagram: 1. Bolt body, 11. Forward external thread section, 12. Reverse external thread section, 13. Second locking groove, 2. Primary nut, 21. First locking groove, 3. Secondary nut, 31. First deformation lug, 32. Second deformation lug, 33. Enclosing cavity, 34. Clearance cavity, 35. Engagement cavity, 4. Sleeve body, 41. Lower chamber, 411. First force application part, 42. Upper chamber, 421. Second force application part. Detailed Implementation

[0035] Example 1 like Figure 1-4 The illustrated fastener with reverse threaded fastener includes a bolt body 1, a primary nut 2, and a secondary nut 3. The bolt body 1 has adjacent, oppositely oriented external threaded sections 11 and 12, with the diameter of the positive external threaded section 11 being larger than the diameter of the reverse external threaded section 12. The primary nut 2 has a positive internal thread that mates with the positive external threaded section 11. The secondary nut 3 has a reverse internal thread that mates with the reverse external threaded section 12.

[0036] The lower end of the secondary nut 3 is fitted onto the upper end of the primary nut 2.

[0037] The lower outer side of the secondary nut 3 is provided with at least one first deformation lug 31, and the upper outer side of the primary nut 2 is provided with a first locking groove 21 that mates with the first deformation lug 31. When the first deformation lug 31 is subjected to radial compression, the first deformation lug 31 deforms and gets stuck in the first locking groove 21.

[0038] The bolt body 1 has a second locking groove 13 at one end, and the secondary nut 3 has at least one second deformation lug 32 on the outer periphery of its upper end. When the second deformation lug 32 is subjected to radial compression, the second deformation lug 32 deforms and gets stuck in the second locking groove 13.

[0039] In this embodiment, the first locking groove 21 is arranged around the first-stage nut 2, and the distance between adjacent first locking grooves 21 is less than the width of the first locking groove 21. The second locking groove 13 is arranged around the outer periphery of the bolt body 1, and the distance between adjacent second locking grooves 13 is less than the width of the second locking groove 13.

[0040] In this embodiment, there are multiple first deformation lugs 31 and second deformation lugs 32, and they are all evenly arranged around the secondary nut 3.

[0041] In this embodiment, the outer surface of the first deformable lug 31 is configured as a guide surface. The width of the first deformable lug 31 is configured to form an interference fit with the groove wall when it deforms and engages with the first locking groove 21. The guide surface is configured as an arc-shaped surface or an inwardly inclined surface.

[0042] In this embodiment, the outer surface of the second deformable lug 32 is configured as a guide surface, and the width of the second deformable lug 32 is configured to form an interference fit with the groove wall when it deforms and engages with the second locking groove 13. Similarly, the guide surface is configured as an arc-shaped surface or an inwardly inclined surface.

[0043] In this embodiment, the cross-section of the primary nut 2 at the end furthest from the secondary nut 3 is hexagonal to facilitate use with a wrench. This structure allows the operator to independently tighten the primary nut 2 using a standard wrench, precisely applying the specified preload torque to establish the clamping force of the fastener on the connecting plate. When installing the secondary nut 3, fixing the hexagonal head effectively prevents the bolt body 1 from rotating.

[0044] like Figure 5-6 An installation tool is shown for installing the aforementioned positive and negative threaded fasteners. It includes a sleeve body 4 and a force-applying tool that cooperates with the sleeve body 4. The sleeve body 4 has a lower chamber 41 and an upper chamber 42 that are coaxially connected inside. The inner walls of the upper chamber 42 and the lower chamber 41 are respectively designed to cooperate with the upper and lower outer circumferences of the secondary nut 3 to transmit torque.

[0045] The inner wall of the lower chamber 41 is provided with a plurality of first force-applying parts 411, and the inner wall of the upper chamber 42 is provided with a plurality of second force-applying parts 421.

[0046] When the sleeve body 4 is fitted onto the secondary nut 3, the first force-applying part 411 and the second force-applying part 421 are respectively positioned opposite to the first deformation lug 31 and the second deformation lug 32 in the circumferential direction.

[0047] When the sleeve body 4 rotates around the axis, the side wall of the first force-applying part 411 presses the first deformation lug 31, causing it to deform and lock into the first locking groove 21, and the side wall of the second force-applying part 421 presses the second deformation lug 32, causing it to deform and lock into the second locking groove 13.

[0048] like Figure 7-8 The installation tool shown has an initial circumferential gap between the side wall of the first force-applying part 411 and the first deformable lug 31, which is smaller than the initial circumferential gap between the side wall of the second force-applying part 421 and the second deformable lug 32.

[0049] During the rotation of the sleeve body 4, the first force-applying part 411 contacts the corresponding deformation lug before the second force-applying part 421 and begins to compress, so that the first deformation lug 31 and the second deformation lug 32 are deformed and locked in stages.

[0050] In this embodiment, the first force-applying part and the second force-applying part are respectively arc-shaped notches formed on the inner wall of the sleeve body.

[0051] In this embodiment, the inner wall of the upper chamber 42 has a triangular cross-sectional profile, and its corner regions constitute the second force-applying part 421. The inner wall of the lower chamber 41 has a circular cross-sectional profile, and its recessed areas constitute the first force-applying part 411.

[0052] The workflow of this utility model includes the following steps: Pre-tightening primary nut 2: The operator uses a standard wrench to hold the hexagonal end of primary nut 2, screws it to the positive external thread section 11 and applies the specified pre-tightening torque, so that primary nut 2 presses against the connected parts and establishes the initial clamping force.

[0053] The second step is to install the secondary nut 3: screw the secondary nut 3 into the reverse external thread section 12 of the bolt body 1, and manually tighten the secondary nut 3 until it covers the upper end face of the primary nut 2. At this time, the secondary nut 3 is threadedly connected to the bolt body 1.

[0054] The third step is to implement double locking: put the sleeve body 4 of the installation tool on the outer circumference of the secondary nut 3 to ensure that the first force-applying part 411 of the lower chamber 41 corresponds circumferentially to the first deformation lug 31 at the lower end of the secondary nut 3, and the second force-applying part 421 of the upper chamber 42 corresponds circumferentially to the second deformation lug 32 at the upper end.

[0055] Using a force-applying tool (such as a wrench), the sleeve body 4 is driven to rotate around its axis. Due to the small initial circumferential gap between the first force-applying part 411 and the first deformable lug 31, the arc-shaped notch sidewall of the first force-applying part 411 will contact the guide surface of the first deformable lug 31 during the initial rotation of the sleeve body 4. The rotational torque is converted into radial compressive force through the guidance of the guide surface, causing the first deformable lug 31 to undergo plastic deformation inward. As the rotation continues, the first deformable lug 31 gradually embeds into the first locking groove 21 on the outer periphery of the primary nut 2, forming an engagement with the first locking groove 21, thus completing the mechanical interlock between the secondary nut 3 and the primary nut 2. As the sleeve body 4 continues to rotate, overcoming the deformation resistance of the first deformation lug 31, the second force-applying part 421, formed by the triangular corner of the inner wall of the upper chamber 42, contacts the second deformation lug 32. Since the secondary nut 3 is already fixed relative to the primary nut 2, the compression of the second force-applying part 421 on the second deformation lug 32 acts directly between the secondary nut 3 and the bolt body 1, causing the second deformation lug 32 to deform inward along the guide surface and lock into the second locking groove 13 at the end of the bolt body 1, thus achieving rigid locking between the secondary nut 3 and the bolt body 1. This completes the anti-loosening installation of the entire fastener.

[0056] The above embodiments are exemplary and are intended to illustrate the technical concept and features of this utility model, so that those skilled in the art can understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the scope of protection of this utility model.

Claims

1. A fastener with reverse threaded fasteners, characterized in that: The device includes a bolt body (1), a primary nut (2), and a secondary nut (3). The bolt body (1) has adjacent and oppositely oriented external thread sections (11) and reverse external thread sections (12) on its outer periphery. The diameter of the external thread section (11) is larger than the diameter of the reverse external thread section (12). The primary nut (2) has a positive internal thread that mates with the external thread section (11). The secondary nut (3) has a reverse internal thread that mates with the reverse external thread section (12). The lower end of the secondary nut (3) is fitted onto the upper end of the primary nut (2); The secondary nut (3) has at least one first deformation lug (31) on the outer side of its lower end, and the primary nut (2) has a first locking groove (21) on the outer side of its upper end that cooperates with the first deformation lug (31); when the first deformation lug (31) is subjected to radial compression, the first deformation lug (31) deforms and gets stuck in the first locking groove (21); The bolt body (1) has a second locking groove (13) at its end, and the upper outer periphery of the secondary nut (3) has at least one second deformation lug (32); when the second deformation lug (32) is subjected to radial compression, the second deformation lug (32) deforms and gets stuck in the second locking groove (13).

2. The fastener with reverse threaded fastener according to claim 1, characterized in that: The first locking groove (21) is set around the first-level nut (2) and the distance between adjacent first locking grooves (21) is less than the width of the first locking groove (21); the second locking groove (13) is set around the outer periphery of the bolt body (1) and the distance between adjacent second locking grooves (13) is less than the width of the second locking groove (13).

3. The fastener with reverse threaded fastener according to claim 1, characterized in that: The first deformation lug (31) and the second deformation lug (32) are both provided in multiples, and are evenly arranged along the circumference of the secondary nut (3).

4. The fastener with reverse threaded fastener according to claim 1, characterized in that: The outer surface of the first deformable lug (31) is set as a guide surface; the width of the first deformable lug (31) is set to form an interference fit with the groove wall when it deforms and is inserted into the first locking groove (21).

5. The fastener with reverse threaded fastener according to claim 1, characterized in that: The outer surface of the second deformation lug (32) is set as a guide surface, and the width of the second deformation lug (32) is set to form an interference fit with the groove wall when it is deformed and inserted into the second locking groove (13).

6. The fastener with reverse threaded fastener according to claim 1, characterized in that: The cross-section of the first-level nut (2) away from the second-level nut (3) is hexagonal so that it can be used with a wrench.

7. An installation tool for installing the reversible threaded fastener as described in any one of claims 1-6, characterized in that: Includes a sleeve body (4) and a force-applying tool that cooperates with the sleeve body (4). The sleeve body (4) is coaxially connected with a lower chamber (41) and an upper chamber (42). The inner walls of the upper chamber (42) and the lower chamber (41) are respectively designed to cooperate with the outer periphery of the upper and lower ends of the secondary nut (3) to transmit torque. The inner wall of the lower chamber (41) is provided with a plurality of first force-applying parts (411), and the inner wall of the upper chamber (42) is provided with a plurality of second force-applying parts (421). When the sleeve body (4) is sleeved on the secondary nut (3), the first force-applying part (411) and the second force-applying part (421) are respectively arranged opposite to the first deformation lug (31) and the second deformation lug (32) in the circumferential direction; When the sleeve body (4) rotates around the axis, the side wall of the first force-applying part (411) presses the first deformation lug (31) to deform and lock into the first locking groove (21), and the side wall of the second force-applying part (421) presses the second deformation lug (32) to deform and lock into the second locking groove (13).

8. The installation tool according to claim 7, characterized in that: The initial circumferential gap between the sidewall of the first force-applying part (411) and the first deformable lug (31) is smaller than the initial circumferential gap between the sidewall of the second force-applying part (421) and the second deformable lug (32). During the rotation of the sleeve body (4), the first force-applying part (411) contacts the corresponding deformation lug before the second force-applying part (421) and begins to squeeze, so that the first deformation lug (31) and the second deformation lug (32) are deformed and locked in stages.

9. The installation tool according to claim 7, characterized in that: The first force-applying part (411) and the second force-applying part (421) are respectively arc-shaped notches formed on the inner wall of the sleeve body (4).

10. The installation tool according to claim 7, characterized in that: The inner wall of the upper chamber (42) has a triangular cross-sectional profile, and its corner area constitutes the second force-applying part (421); the inner wall of the lower chamber (41) has a circular cross-sectional profile, and its concave area constitutes the first force-applying part (411).

Images