A double-end stud mounting tool adapted for an automated device

Abstract

A double-end stud mounting tool suitable for an automation equipment, comprising a connection module, a monitoring module, a quick-lock module and a clamping module; the connection module comprises a straight rod type four-square wrench and a straight cylinder type adapter sleeve; the straight rod type four-square wrench is provided with a plug-in structure at the root and is coaxially and fixedly connected with the main shaft of the automation equipment through the plug-in structure; the straight cylinder type adapter sleeve is coaxially sleeved outside the straight rod type four-square wrench, a gap is left between the two, the top end of the straight cylinder type adapter sleeve is provided with a flange structure and is fixedly connected with the sleeve shell of the main shaft of the automation equipment through the flange structure; the monitoring module is located at the bottom end of the straight cylinder type adapter sleeve; the clamping module is located at the square head of the four-square wrench; and the quick-lock module is located between the four-square wrench and the clamping module. The application adopts a modular design idea, can be assembled with the main shaft of the automation equipment, each module can be replaced according to the model of the double-end stud, and the distance of the double-end stud when being screwed into the threaded hole of the workpiece can be monitored in real time, so that the installation precision and efficiency of the double-end stud are improved.

Description

Technical Field

[0001] This invention belongs to the field of tooling technology, and in particular relates to a double-ended stud installation tool adapted to automated equipment. Background Technology

[0002] Double-ended studs are widely used in mechanical assembly as connecting components. The end of the double-ended stud used to screw into the threaded hole of the workpiece is usually called the screw-in end, while the other end of the double-ended stud needs to be connected to a tightening tool during installation and is therefore usually called the fastening end.

[0003] Currently, the tools used in the installation of double-ended studs mainly consist of a threaded sleeve and a setter. The setter is located inside the threaded sleeve. First, the fastening end of the double-ended stud needs to be screwed into the threaded sleeve so that the fastening end of the double-ended stud contacts the setter inside the threaded sleeve, thereby generating a biting force. Under the biting force, the fastening end of the double-ended stud is fastened to the threaded sleeve. Then, the screw-in end of the double-ended stud is aligned with the threaded hole of the workpiece, and by tightening the threaded sleeve, the screw-in end of the double-ended stud can be screwed into the threaded hole of the workpiece to complete the installation of the double-ended stud.

[0004] However, when installing studs using traditional tools, the insert and its internal setter rotate synchronously. When removing the insert from the fastening end of the stud, it's necessary to reverse the rotation. However, the engagement force between the fastening end and the setter doesn't disappear. Under this force, the static friction between the insert and the stud may still be greater than the static friction between the stud and the workpiece's threaded hole. This can cause the stud to unscrew itself from the workpiece's threaded hole when the insert is reversed, resulting in installation failure. In severe cases, the fastening end of the stud may become completely stuck inside the insert, severely hindering subsequent installations.

[0005] Furthermore, traditional tools can only be used for manual installation of double-ended studs, and cannot be adapted to a wide range of automated equipment such as machine tools and robotic arms, which severely limits the efficiency of double-ended stud installation using traditional tools.

[0006] To address this, Chinese patent application number 202210414423.2 discloses a tool kit for installing and removing double-ended studs. Although this patent solves many problems of traditional tools in installing double-ended studs to some extent, it is still a manual tool and cannot be adapted to a wide range of automated equipment such as machine tools and robotic arms. Therefore, it also suffers from the problem of low efficiency in installing double-ended studs. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a double-ended stud installation tool adapted to automated equipment. It can be assembled with the spindle of the automated equipment and adopts a modular design concept. Each module can be replaced according to the actual model of the double-ended stud. During installation, the distance of the double-ended stud into the threaded hole of the workpiece can be monitored in real time, which effectively improves the installation accuracy of the double-ended stud. Relying on the powerful performance of the automated equipment, the installation efficiency of the double-ended stud is greatly improved.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a double-ended stud installation tool adapted to automated equipment, comprising a connecting module, a monitoring module, a quick-lock module, and an engagement module; the connecting module includes a straight-barrel square wrench and a straight-tube adapter sleeve; the straight-barrel square wrench has a plug-in structure at its root, and the straight-barrel square wrench is coaxially and fixedly connected to the main shaft of the automated equipment through the plug-in structure at its root; the straight-tube adapter sleeve is coaxially fitted onto the outside of the straight-barrel square wrench, with a gap between the straight-tube adapter sleeve and the square wrench, and the top end of the straight-tube adapter sleeve has a flange structure, and the straight-tube adapter sleeve is fixedly connected to the outer shell of the main shaft of the automated equipment through the flange structure at its top end; the monitoring module is located at the bottom end of the straight-tube adapter sleeve; the engagement module is located at the square head of the square wrench; and the quick-lock module is located between the square wrench and the engagement module.

[0009] The monitoring module includes a laser displacement sensor, a floating sleeve, and a top support frame. The floating sleeve has a double-wall structure, with its inner wall slidably inserted into a straight-tube adapter sleeve. Two guide grooves are symmetrically formed on the body of the straight-tube adapter sleeve, parallel to its central axis. A limiting pin is fixedly installed on the inner wall of the floating sleeve, located within the guide groove. An external thread is provided on the outer wall of the floating sleeve. The top support frame has an annular structure at its upper end, with an internal thread on the annular portion, and is screwed onto the floating sleeve. The bottom of the top support frame has a frame structure. The laser displacement sensor is fixedly installed on the outer surface of the straight-tube adapter sleeve, with its laser beam parallel to the central axis of the straight-tube adapter sleeve and directed towards the floating sleeve.

[0010] The quick-lock module includes a positioning sleeve, a positioning ring, and a locking frame. The positioning sleeve is coaxially fixed to the top of the square head of the square wrench, and the positioning sleeve and the square wrench are fixed together by screws. Two notched grooves are symmetrically provided at the top opening of the positioning sleeve. The positioning ring is coaxially fixed to the top opening of the positioning sleeve by screws. The upper end of the locking frame is a ring-shaped structure, and two limiting protrusions are symmetrically provided on the inner side of the ring-shaped structure of the locking frame. The limiting protrusions are located in the notched grooves. The locking frame has only rotational freedom relative to the positioning sleeve and the positioning ring, and the rotation angle range is 0 to 90°. The lower end of the locking frame is a rod-shaped structure, and a rod-shaped body is provided below each limiting protrusion. A limiting block is provided at the bottom of each rod-shaped body.

[0011] The engagement module includes an outer shell, an inner shell, an inter-shell limiting body, a thrust bearing, and a pushing body. The outer shell adopts a variable-diameter cylindrical structure. At the opening of the cylinder on the large-diameter end of the outer shell, locking inner protrusions are evenly distributed circumferentially. An internal thread is provided on the inner surface of the small-diameter end of the outer shell, and the small-diameter end of the outer shell is screwed into the fastening end of a double-ended stud via the internal thread. The inner shell adopts a variable-diameter cylindrical structure. At the opening of the cylinder on the outer surface of the large-diameter end of the inner shell, locking outer protrusions are evenly distributed circumferentially. The number of locking outer protrusions and locking inner protrusions are equal, and their positions correspond one-to-one. The inner surface of the small-diameter end of the inner shell is provided with a square slot. Two locking edges are symmetrically provided at the opening of the square slot. The square slot engages with the square head of a square wrench. The locking edges are connected to the limiting body on the locking frame. The locking blocks engage in a locking and limiting engagement; the outer shell is coaxially fitted onto the outer side of the inner shell, the inner protrusion of the locking position is located directly above the outer protrusion of the locking position, and forms several inter-block slots along the circumferential direction; the upper end of the inter-shell limiting body is a ring-shaped structure, the lower end of the inter-shell limiting body is an arc-shaped structure, and the arc-shaped structure part of the inter-shell limiting body is located within the inter-block slots; the thrust bearing and the pusher body are located inside the outer shell and the inner shell, and are coaxially distributed with the outer shell and the inner shell, and have axial movement freedom inside the outer shell and the inner shell; the outer ring of the thrust bearing is clearance-fitted with the inner surface of the large-diameter end of the inner shell, the inner ring of the thrust bearing is fixedly connected to one end of the pusher body, and the other end of the pusher body is in contact with the fastening end of the double-ended stud.

[0012] The beneficial effects of this invention are:

[0013] The present invention relates to a double-ended stud installation tool adapted for automated equipment. It can be assembled with the spindle of the automated equipment and adopts a modular design concept. Each module can be replaced according to the actual model of the double-ended stud. During installation, the distance of the double-ended stud into the threaded hole of the workpiece can be monitored in real time, which effectively improves the installation accuracy of the double-ended stud. Relying on the powerful performance of the automated equipment, the installation efficiency of the double-ended stud is greatly improved. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a double-headed stud installation tool adapted to automated equipment according to the present invention;

[0015] Figure 2 This is a structural schematic diagram (sectional view) of a double-headed stud installation tool adapted to automated equipment according to the present invention;

[0016] Figure 3 This is a schematic diagram of the combined structure of the connection module and the monitoring module of the present invention;

[0017] Figure 4 This is a schematic diagram (cross-sectional view) of the combined structure of the connection module and the monitoring module of the present invention;

[0018] Figure 5 This is a schematic diagram of the quick-lock module of the present invention;

[0019] Figure 6 This is a structural schematic diagram (sectional view) of the quick-lock module of the present invention;

[0020] Figure 7 This is a schematic diagram of the positioning sleeve structure in the quick-lock module of the present invention;

[0021] Figure 8 This is a schematic diagram of the locking frame structure in the quick-lock module of the present invention;

[0022] Figure 9 This is a schematic diagram of the bite module of the present invention;

[0023] Figure 10 This is a structural schematic diagram (sectional view 1) of the bite module of the present invention;

[0024] Figure 11 This is a structural schematic diagram (sectional view 2) of the bite module of the present invention;

[0025] Figure 12 This is a schematic diagram of the outer shell structure in the bite module of the present invention;

[0026] Figure 13 This is a schematic diagram of the inner shell structure in the biting module of the present invention;

[0027] Figure 14 This is a schematic diagram of the intershell limiting body structure in the biting module of the present invention;

[0028] In the diagram, 1—straight rod square wrench, 2—straight cylindrical adapter sleeve, 3—laser displacement sensor, 4—floating sleeve, 5—top support frame, 6—guide groove, 7—limiting pin, 8—positioning sleeve, 9—positioning ring, 10—locking frame, 11—notched groove, 12—limiting protrusion, 13—limiting block, 14—outer shell, 15—inner shell, 16—inter-shell limiting body, 17—thrust bearing, 18—top pusher, 19—inner locking protrusion, 20—outer locking protrusion, 21—square slot, 22—locking edge. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] like Figures 1-14 As shown, a double-ended stud installation tool adapted for automated equipment includes a connection module, a monitoring module, a quick-lock module, and an engagement module. The connection module includes a straight-barrel square wrench 1 and a straight-tube adapter sleeve 2. The straight-barrel square wrench 1 has a plug-in structure at its root, and the straight-barrel square wrench 1 is coaxially fixed to the main shaft of the automated equipment through the plug-in structure at its root. The straight-tube adapter sleeve 2 is coaxially fitted onto the outside of the straight-barrel square wrench 1, with a gap between the straight-tube adapter sleeve 2 and the square wrench 1. The top end of the straight-tube adapter sleeve 2 has a flange structure, and the straight-tube adapter sleeve 2 is fixedly connected to the outer shell of the main shaft of the automated equipment through the flange structure at its top end. The monitoring module is located at the bottom end of the straight-tube adapter sleeve 2. The engagement module is located at the square head of the square wrench 1. The quick-lock module is located between the square wrench 1 and the engagement module.

[0031] The monitoring module includes a laser displacement sensor 3, a floating sleeve 4, and a top support frame 5. The floating sleeve 4 has a double-wall structure, with its inner wall slidably inserted into the straight-tube adapter sleeve 2. Two guide grooves 6 are symmetrically provided on the tube body of the straight-tube adapter sleeve 2, and the guide grooves 6 are parallel to the central axis of the straight-tube adapter sleeve 2. A limiting pin 7 is fixedly installed on the inner wall of the floating sleeve 4, and the limiting pin 7 is located within the guide groove 6. An external thread is provided on the outer wall of the floating sleeve 4. The upper end of the top support frame 5 has an annular structure, and an internal thread is provided on the annular part of the top support frame 5. The top support frame 5 and the floating sleeve 4 are screwed together by the thread. The lower end of the top support frame 5 has a frame structure. The laser displacement sensor 3 is fixedly installed on the outer surface of the straight-tube adapter sleeve 2, and the laser beam of the laser displacement sensor 3 is parallel to the central axis of the straight-tube adapter sleeve 2, with the laser beam of the laser displacement sensor 3 pointing towards the floating sleeve 4.

[0032] The quick-lock module includes a positioning sleeve 8, a positioning ring 9, and a locking frame 10. The positioning sleeve 8 is coaxially fixedly fitted above the square head of the square wrench 1, and the positioning sleeve 8 and the square wrench 1 are fixed together by screws. Two notched grooves 11 are symmetrically provided at the top opening of the positioning sleeve 8. The positioning ring 9 is coaxially fixed at the top opening of the positioning sleeve 8 by screws. The upper end of the locking frame 10 is a ring-shaped structure, and two limiting protrusions 12 are symmetrically provided on the inner side of the ring-shaped structure of the locking frame 10. The limiting protrusions 12 are located in the notched grooves 11. The locking frame 10 has only rotational freedom relative to the positioning sleeve 8 and the positioning ring 9, and the rotation angle range is 0 to 90°. The lower end of the locking frame 10 is a rod-shaped structure, and a rod-shaped body is provided below each limiting protrusion 12. A limiting block 13 is provided at the bottom end of each rod-shaped body.

[0033] The engagement module includes an outer shell 14, an inner shell 15, an inter-shell limiting body 16, a thrust bearing 17, and a pushing body 18. The outer shell 14 adopts a variable-diameter cylindrical structure. Engaging protrusions 19 are evenly distributed circumferentially at the opening of the large-diameter end of the outer shell 14, and internal threads are provided on the inner surface of the small-diameter end of the outer shell 14. The small-diameter end of the outer shell 14 is screwed into the fastening end of a double-ended stud via the internal threads. The inner shell 15 adopts a variable-diameter cylindrical structure. The structure includes external locking protrusions 20 evenly distributed circumferentially at the opening of the cylinder on the outer surface of the large-diameter end of the inner shell 15. The number of external locking protrusions 20 and the positions of the internal locking protrusions 19 are equal and correspond one-to-one. The inner surface of the small-diameter end of the inner shell 15 is provided with a square slot 21. Two locking edges 22 are symmetrically provided at the opening of the square slot 21. The square slot 21 is inserted into the square head of the square wrench 1. The locking edges 22 are connected to the limiting blocks 1 on the locking frame 10. 3. A locking and limiting mechanism is used; the outer shell 14 is coaxially fitted onto the outer side of the inner shell 15, the inner locking protrusion 19 is located directly above the outer locking protrusion 20, and forms several inter-block slots along the circumferential direction; the upper end of the inter-shell limiting body 16 is a ring-shaped structure, the lower end of the inter-shell limiting body 16 is an arc-shaped structure, and the arc-shaped structure part of the inter-shell limiting body 16 is located within the inter-block slots; the thrust bearing 17 and the pusher body 18 are located inside the outer shell 14 and the inner shell 15, and are coaxially distributed with the outer shell 14 and the inner shell 15, having axial freedom of movement inside the outer shell 14 and the inner shell 15; the outer ring of the thrust bearing 17 is clearance-fitted with the inner surface of the large-diameter end of the inner shell 15, the inner ring of the thrust bearing 17 is fixedly connected to one end of the pusher body 18, and the other end of the pusher body 18 is in contact with the fastening end of the double-ended stud.

[0034] The following describes a single use of the present invention with reference to the accompanying drawings:

[0035] In this embodiment, the automated equipment is a CNC machining center. First, the root insertion structure of the straight-barrel square wrench 1 is coaxially fixed to the spindle of the CNC machining center; then, the straight-tube adapter sleeve 2 is fitted onto the outside of the straight-barrel square wrench 1, so that the top flange structure of the straight-tube adapter sleeve 2 is coaxially connected to the outer casing of the spindle of the CNC machining center, and the connection is tightened with bolts.

[0036] After the straight-bar square wrench 1 and the straight-tube adapter sleeve 2 are installed, the quick-lock module is then installed onto the spindle of the CNC machining center. First, the pre-assembled quick-lock module is inserted upwards onto the square head of the straight-bar square wrench 1. Then, the quick-lock module is moved upwards until the screw hole on the positioning sleeve 8 is aligned with the screw hole on the straight-bar square wrench 1. Then, screws are screwed into the aligned screw holes until the positioning sleeve 8 is completely fixed onto the straight-bar square wrench 1.

[0037] After the quick-lock module is installed, continue with the installation of the monitoring module. First, insert the inner wall of the floating sleeve 4 upwards into the straight-tube adapter sleeve 2 until the threaded hole on the inner wall of the floating sleeve 4 aligns with the guide groove 6 on the straight-tube adapter sleeve 2. Then, pass the limiting pin 7 through the guide groove 6 and screw it into the threaded hole on the inner wall of the floating sleeve 4 until the limiting pin 7 is confined within the guide groove 6. Next, screw the annular structure of the top support 5 upwards onto the floating sleeve 4 until the installation and fixation of the top support 5 is complete. Finally, install the laser displacement sensor 3 at the designated position on the outer surface of the straight-tube adapter sleeve 2.

[0038] After the monitoring module is installed, the engagement module is installed last. First, move the pre-assembled engagement module directly below the square head of the straight-bar square wrench 1. Then, continue to lift the engagement module upwards so that the square head of the straight-bar square wrench 1 is accurately inserted into the square slot 21 at the top of the engagement module's inner housing 15. Next, horizontally rotate the locking bracket 10 on the quick-lock module, making it rotate 90° from its initial position. At this time, the limiting protrusion 12 on the locking bracket 10 will slide from one end of the notch groove 11 to the other end, and simultaneously, the limiting block 13 on the locking bracket 10 will move directly below the locking edge 22 of the engagement module. At this point, the axial degree of freedom of the engagement module is locked, and the engagement module installation is complete.

[0039] After the engagement module is installed, select a double-ended stud to be installed. First, screw the fastening end of the double-ended stud into the small-diameter end of the outer shell 14 of the engagement module until the fastening end of the double-ended stud is pressed against the pusher body 18. At this time, a temporary fixed connection is achieved between the double-ended stud and the engagement module. Then, the position of the spindle is adjusted by the CNC machining center until the screw-in end of the double-ended stud is aligned with the threaded hole on the workpiece. After that, the axial position of the double-ended stud is finely adjusted so that the screw-in end of the double-ended stud is aligned with the threaded hole on the workpiece. At this time, the bottom end of the top support 5 of the monitoring module has made contact with the workpiece surface around the threaded hole, and the laser displacement sensor 3 in the monitoring module is activated.

[0040] After the above preparations are completed, the spindle of the CNC machining center is started. The spindle's rotary feed motion is transmitted sequentially to the double-ended stud through the straight-bar wrench 1, the quick-lock module, and the engagement module, causing the tightening end of the double-ended stud to continuously screw into the threaded hole of the workpiece. During the process of the tightening end of the double-ended stud screwing into the threaded hole of the workpiece, the straight-tube adapter sleeve 2 and its laser displacement sensor 3 will generate relative displacement with respect to the workpiece surface, while the top support 5 of the monitoring module and the floating sleeve 4 are stationary with respect to the workpiece surface. That is to say, the relative displacement between the laser displacement sensor 3 and the floating sleeve 4 is exactly equal to the screwing distance of the tightening end of the double-ended stud. Therefore, the screwing distance of the tightening end of the double-ended stud can be known in real time through the displacement data monitored by the laser displacement sensor 3.

[0041] When the screw-in distance of the double-ended stud reaches the set value, the spindle of the CNC machining center first stops the rotational feed motion, and then performs the reverse rotational feed motion. Due to the presence of the thrust bearing 17, the static friction between the fastening end of the double-ended stud and the pusher body 18 can be eliminated immediately. At the same time, the dynamic friction resistance between the fastening end of the double-ended stud and the small-diameter end of the engagement module housing 14 is much lower than the static friction between the double-ended stud and the threaded hole of the workpiece. With the reverse rotational feed, the small-diameter end of the engagement module housing 14 can be quickly removed from the fastening end of the double-ended stud.

[0042] Similarly, by following the above working method, batch and efficient installation of double-ended studs can be achieved. When the model of the double-ended stud changes, if the automated equipment is not adjusted, only the appropriate engagement module needs to be replaced. The replacement is also very convenient. First, the locking bracket 10 on the quick-lock module is rotated horizontally in the reverse direction, causing it to rotate 90° back to its initial position. The limiting protrusion 12 on the locking bracket 10 slides from one end of the notch groove 11 to the other end. At the same time, the limiting block 13 on the locking bracket 10 is completely misaligned with the locking edge 22 of the engagement module, and the engagement module regains its axial freedom. Then, the engagement module is moved downwards, so that the square head of the straight-bar square wrench 1 is completely pulled out of the square slot 21 at the top of the inner shell 15 of the engagement module, thereby separating the engagement module from the straight-bar square wrench 1. At this point, the original engagement module can be removed, and the installation process of the new engagement module is exactly the same as that of the original engagement module.

[0043] The solutions described in the embodiments are not intended to limit the scope of patent protection of this invention. All equivalent implementations or modifications that do not depart from the scope of this invention are included in the patent scope of this case.

Claims

1. A double-ended stud installation tool adapted for automated equipment, characterized in that: The system includes a connection module, a monitoring module, a quick-lock module, and a locking module. The connection module comprises a straight-barrel square wrench and a straight-tube adapter sleeve. The straight-barrel square wrench has a plug-in structure at its base, allowing it to be coaxially and fixedly connected to the main shaft of the automation equipment. The straight-tube adapter sleeve is coaxially fitted onto the outside of the straight-barrel square wrench, with a gap between them. The top end of the straight-tube adapter sleeve has a flange structure, allowing it to be fixedly connected to the outer casing of the main shaft of the automation equipment. The monitoring module is located at the bottom of the straight-tube adapter sleeve. The locking module is located at the square head of the square wrench. The quick-lock module is located between the square wrench and the locking module. The monitoring module includes a laser displacement sensor and a floating sleeve. The floating sleeve and top support frame are as follows: The floating sleeve adopts a double-wall structure, and the inner wall of the floating sleeve is slidably inserted into the straight cylindrical adapter sleeve; Two guide grooves are symmetrically opened on the tube body of the straight cylindrical adapter sleeve, and the guide grooves are parallel to the central axis of the straight cylindrical adapter sleeve; A limiting pin is fixedly installed on the inner wall of the floating sleeve, and the limiting pin is located in the guide groove; An external thread is provided on the outer wall of the floating sleeve; The upper end of the top support frame is a ring structure, and an internal thread is provided on the ring structure part of the top support frame, and the top support frame and the floating sleeve are screwed together by the thread; The lower end of the top support frame is a frame structure; The laser displacement sensor is fixedly installed on the outer surface of the straight cylindrical adapter sleeve, and the laser beam of the laser displacement sensor is parallel to the central axis of the straight cylindrical adapter sleeve, and the laser beam of the laser displacement sensor is directed towards the floating sleeve.

2. The double-ended stud installation tool adapted to automated equipment according to claim 1, characterized in that: The quick-lock module includes a positioning sleeve, a positioning ring, and a locking frame. The positioning sleeve is coaxially fixed to the top of the square head of the square wrench, and the positioning sleeve and the square wrench are fixed together by screws. Two notched grooves are symmetrically provided at the top opening of the positioning sleeve. The positioning ring is coaxially fixed to the top opening of the positioning sleeve by screws. The upper end of the locking frame is a ring-shaped structure, and two limiting protrusions are symmetrically provided on the inner side of the ring-shaped structure of the locking frame. The limiting protrusions are located in the notched grooves. The locking frame has only rotational freedom relative to the positioning sleeve and the positioning ring, and the rotation angle range is 0 to 90°. The lower end of the locking frame is a rod-shaped structure, and a rod-shaped body is provided below each limiting protrusion. A limiting block is provided at the bottom of each rod-shaped body.

3. The double-ended stud installation tool adapted to automated equipment according to claim 2, characterized in that: The engagement module includes an outer shell, an inner shell, an inter-shell limiting body, a thrust bearing, and a pushing body. The outer shell adopts a variable-diameter cylindrical structure. At the opening of the cylinder on the large-diameter end of the outer shell, locking inner protrusions are evenly distributed circumferentially. An internal thread is provided on the inner surface of the small-diameter end of the outer shell, and the small-diameter end of the outer shell is screwed into the fastening end of a double-ended stud via the internal thread. The inner shell adopts a variable-diameter cylindrical structure. At the opening of the cylinder on the outer surface of the large-diameter end of the inner shell, locking outer protrusions are evenly distributed circumferentially. The number of locking outer protrusions is equal to the number of locking inner protrusions, and their positions correspond one-to-one. The inner surface of the small-diameter end of the inner shell is provided with a square slot. Two locking edges are symmetrically provided at the opening of the square slot. The square slot engages with the square head of a square wrench. The locking edges are connected to the limiting body on the locking frame. The locking blocks engage in a locking and limiting engagement; the outer shell is coaxially fitted onto the outer side of the inner shell, the inner protrusion of the locking position is located directly above the outer protrusion of the locking position, and forms several inter-block slots along the circumferential direction; the upper end of the inter-shell limiting body is a ring-shaped structure, the lower end of the inter-shell limiting body is an arc-shaped structure, and the arc-shaped structure part of the inter-shell limiting body is located within the inter-block slots; the thrust bearing and the pusher body are located inside the outer shell and the inner shell, and are coaxially distributed with the outer shell and the inner shell, and have axial movement freedom inside the outer shell and the inner shell; the outer ring of the thrust bearing is clearance-fitted with the inner surface of the large-diameter end of the inner shell, the inner ring of the thrust bearing is fixedly connected to one end of the pusher body, and the other end of the pusher body is in contact with the fastening end of the double-ended stud.

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