Nut installation and removal tool for pre-tightening bolts

Abstract

The present invention discloses a nut assembly and disassembly tool for pre-tightening bolts, comprising a hydraulic bolt tensioner, a clamping wheel driving device, a clamping wheel lifting device and a clamping wheel transverse movement device. The clamping wheel driving device is located outside one side of the hydraulic bolt tensioner, and comprises a driving motor and a gearbox. The gearbox comprises a housing, an active double gear, a driven double gear, a clamping wheel, an active double gear shaft, a driven double gear shaft and a fork mechanism. The outer circumference of the clamping wheel is provided with a mesh pattern. The clamping wheel lifting device and the clamping wheel transverse movement device are respectively located between the hydraulic bolt tensioner and the clamping wheel driving device. The present invention has a compact structure, is convenient and quick to use, significantly reduces the labor intensity of tightening or removing nuts from pre-tightening bolts, improves work efficiency, and ensures the safety of tightening or removing nuts from pre-tightening bolts.

Description

Technical Field

[0001] The invention relates to an assembly and disassembly tool, in particular to an assembly and disassembly tool for tightening or removing a nut on a bolt after the bolt is stretched to produce elastic deformation, and belongs to the technical field of mechanical tools. Background Art

[0002] The pre-tightening connection of bolts and nuts is a common way of connecting parts of mechanical equipment. By stretching the bolts to make them elastically deformed and then tightening the nuts, the reliability of the bolt and nut connection can be effectively improved, the anti-loosening performance can be improved, the safety of the fixed connection of products and parts can be guaranteed, and the equipment can be prevented from being damaged due to loose nuts during use. At present, during the assembly process, a hydraulic bolt tensioner is generally used to stretch the high-strength bolts, so that the high-strength bolts are elastically deformed, so that a gap is generated between the bottom surface of the nut screwed on the high-strength bolt and the mounting base surface, and then a lever is manually inserted into the small circular hole corresponding to the circumferential surface of the nut for multiple times to tighten the nut again. After the hydraulic bolt tensioner is unloaded, the elastic deformation of the high-strength bolt disappears and the original length is restored, thereby completing the pre-tightening connection of the high-strength bolt and the nut. When it is necessary to remove the nut on the pre-tightened high-strength bolt, the hydraulic bolt tensioner is used again to stretch the bolt again, so that a gap is generated again between the bottom surface of the nut screwed on the high-strength bolt and the mounting base surface, and then the lever is used again to slowly loosen the nut. The method of tightening or loosening the nut is very inefficient, and each person's arm strength is different, and there are differences in disassembly and assembly habits. Especially when removing the nut, plastic deformation has occurred between some of the engaged screw threads, making it difficult to loosen the nut with a lever. The only way is to hit it with a hammer, which will cause knock marks on the nut and pose certain safety hazards. Summary of the invention

[0003] The purpose of the invention is to provide a nut assembly and disassembly tool for pre-tightening bolts which has a compact structure and is easy to use.

[0004] The present invention is achieved through the following technical solutions:

[0005] A nut assembly and disassembly tool for pre-tightening bolts, comprising a hydraulic bolt tensioner, a clamping wheel driving device, a clamping wheel lifting device and a clamping wheel lateral movement device, wherein the clamping wheel driving device is located outside one side of the hydraulic bolt tensioner, and comprises a driving motor and a gearbox, wherein the gearbox comprises a housing, an active double gear, a driven double gear, a clamping wheel, an active double gear shaft, a driven double gear shaft and a shift fork mechanism, wherein the driving motor is vertically fixed to the upper side of the housing, the bottom of the housing is supported on one side of the bottom of the hydraulic bolt tensioner by a skeleton spring, one side of the housing adjacent to the window of the hydraulic bolt tensioner cylinder is open, and the shaft of the driving motor is protected by a torsional overload protection The clutch is fixedly connected to the upper end of the active double gear shaft vertically supported in the housing; the active double gear upper gear, one end of the shift fork mechanism and the active double gear lower gear are sequentially inserted and positioned on the middle part of the active double gear shaft from top to bottom; the driven double gear upper gear, the pressure wheel and the driven double gear lower gear are sequentially inserted and positioned on the middle part of the driven double gear shaft from top to bottom, and the two ends of the driven double gear shaft and the lower end of the active double gear shaft are respectively supported in the housing by corresponding bearings; the outer peripheral surface of the pressure wheel is provided with a mesh pattern; the pressure wheel lifting device and the pressure wheel lateral movement device are respectively located between the hydraulic bolt tensioner and the pressure wheel driving device.

[0006] The purpose of the present invention can be further achieved by the following technical measures.

[0007] Furthermore, the number of teeth on the upper gear of the active double gear is greater than the number of teeth on the upper gear of the driven double gear, and the number of teeth on the lower gear of the active double gear is less than the number of teeth on the lower gear of the driven double gear; when the active double gear moves up to the position, the lower gear of the active double gear meshes with the lower gear of the driven double gear, and the pressure wheel rotates slowly; when the active double gear moves down to the position, the upper gear of the active double gear meshes with the upper gear of the driven double gear, and the pressure wheel rotates rapidly.

[0008] Furthermore, the middle cross-section of the active double gear shaft and the middle cross-section of the driven double gear shaft are both square, the square center hole of the active double gear and the middle clearance of the active double gear shaft match, the square center hole of the driven double gear and the square center hole of the pressure wheel respectively match the middle clearance of the driven double gear shaft.

[0009] Furthermore, the clamping wheel lifting device includes a dovetail block and a dovetail groove, the dovetail groove is vertically fixed on the top of the box body and is located between the drive motor and one side of the hydraulic bolt tensioner, and the dovetail block is embedded in the dovetail groove; the clamping wheel transverse movement device is located between one side of the hydraulic bolt tensioner cylinder body and the dovetail block. The clamping wheel transverse movement device includes a transverse movement cylinder and a guide mechanism respectively located between the four corners of the dovetail block and the hydraulic bolt tensioner cylinder body, the cylinder body of the transverse movement cylinder is a countersunk hole in the middle of one side of the hydraulic bolt tensioner cylinder body, the piston at one end of the piston rod extends into the countersunk hole, and the screw plug as the cylinder cover closes the outer end of the countersunk hole, and the other end of the piston rod passes through the screw plug and is fixed to the center of the lower part of the outer side of the dovetail block.

[0010] Furthermore, the guide mechanism includes a sleeve, a sliding shaft, a spring and a limit screw, one end of the sleeve is respectively fixed on the cylinder body and one side of the hydraulic bolt tensioner, one end of the sliding shaft is respectively fixed on the dovetail block, the other end of the sliding shaft extends into the other end of the sleeve, two ends of the spring respectively rest on the bottom of the sleeve and the other end of the sliding shaft, and the limit screw passes through the axial groove at the other end of the sleeve and is vertically screwed into the middle of the sliding shaft.

[0011] Furthermore, the fork mechanism includes a stepped sleeve, a fork body and a vertical shaft. The center of the stepped sleeve is provided with a square center hole of the stepped sleeve that is gap-matched with the middle of the active double gear shaft. The two ends of the stepped sleeve are respectively fixedly connected to the upper gear of the active double gear and the lower gear of the active double gear; the fork mouth at one end of the fork body is embedded in the neck of the stepped sleeve, and the other end of the fork body is sleeved on the middle of the vertical shaft. The two ends of the vertical shaft are respectively supported on the upper and lower sides of the box body, and one end of the handle is hinged to the other end of the fork body, and the other end of the handle passes through the lifting groove on one side of the box body. The top of the lifting groove is provided with a locking transverse groove; when the fork body drives the active double gear to move up to the position, the other end of the handle is embedded in the locking transverse groove to lock the active double gear. A driving motor program switch is installed on one side of the middle of the lifting groove.

[0012] The present invention is arranged on one side of the hydraulic bolt tensioner, and adopts a clamping wheel to move horizontally against the circumferential surface of the nut to be tightened or loosened, and adopts a friction transmission method to drive the nut to be tightened on the high-strength bolt stretched by the hydraulic bolt tensioner, or to remove the nut from the stretched high-strength bolt. At the same time, a gearbox is used for two-speed shifting, and the reversing of the drive motor is used to tighten the nut with a fast forward rotation and a small torque, and to loosen the nut with a slow reverse rotation and a large torque. The clamping wheel lifting device with a dovetail block and a dovetail groove structure is used to make the clamping wheel lift and lower with the gearbox and the drive motor as the nut moves up and down. The structure is compact, easy and quick to use, and the labor intensity of tightening or removing the nut from the pre-tightening bolt is significantly reduced, the work efficiency is improved, and the safety of tightening or removing the nut from the pre-tightening bolt is ensured.

[0013] Advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments thereof, which are given by way of example only with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of tightening a nut according to the present invention;

[0015] Figure 2 It is a structural schematic diagram of loosening a nut according to the present invention;

[0016] Figure 3 yes Figure 1 A top view of

[0017] Figure 4 yes Figure 1 Right view of;

[0018] Figure 5 Figure 1 AA section enlarged view;

[0019] Figure 6 It is a schematic diagram of the present invention for installing and removing hexagonal nuts. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments of the present invention.

[0021] In the description of the present invention, terms indicating orientation or positional relationship such as “center”, “up”, “down”, “left”, “right”, “inside” and “outside” are based on the orientation or positional relationship shown in the drawings, and do not indicate or imply that the device referred to must have a specific orientation.

[0022] like Figure 1 to Figure 4As shown, this embodiment includes a hydraulic bolt tensioner 1, a clamping wheel driving device 2, a clamping wheel lifting device 3 and a clamping wheel transverse movement device 4. The clamping wheel driving device 2 is located outside the right side of the hydraulic bolt tensioner 1, and includes a driving motor 21 and a gearbox 22. The gearbox 22 includes a box 23, an active double gear 24, a driven double gear 25, a clamping wheel 26, an active double gear shaft 27, a driven double gear shaft 28 and a fork mechanism 29. The driving motor 21 is vertically fixed on the upper side of the box 23, and the bottom of the box 23 is supported on the right side of the bottom of the hydraulic bolt tensioner 1 by a skeleton spring 231, so as to facilitate the up and down movement and reset of the clamping wheel 26. The right side of the box 23 adjacent to the cylinder window 11 of the hydraulic bolt tensioner is open, and the driving motor shaft 211 is fixedly connected to the upper end of the active double gear shaft 27 vertically supported in the box 23 through a torque overload protection clutch 212 to prevent the driving motor 21 from being burned out due to excessive resistance torque during the process of installing and removing the nut 20. The upper gear 241 of the active double gear, the left end of the fork mechanism 29 and the lower gear 242 of the active double gear are inserted and positioned in the middle of the active double gear shaft 27 from top to bottom. The upper gear 251 of the driven double gear, the clamping wheel 26 and the lower gear 252 of the driven double gear are inserted and positioned in the middle of the driven double gear shaft 28 from top to bottom. The two ends of the driven double gear shaft 28 and the lower end of the active double gear shaft 27 are supported in the box body 23 through corresponding bearings 271. The outer peripheral surface of the clamping wheel 26 is provided with a mesh pattern 261, which increases the friction transmission force between the clamping wheel 26 and the nut 20.

[0023] The number of teeth of the upper gear 241 of the active double gear is greater than the number of teeth of the upper gear 251 of the driven double gear, and the number of teeth of the lower gear 242 of the active double gear is less than the number of teeth of the lower gear 252 of the driven double gear. When the active double gear 24 moves up to the position, the lower gear 242 of the active double gear meshes with the lower gear 52 of the driven double gear, at this time the transmission ratio i=1.5~2.0, the clamping wheel 26 rotates slowly to loosen the nut 10; when the active double gear 24 moves down to the position, the upper gear 241 of the active double gear meshes with the upper gear 251 of the driven double gear, at this time the transmission ratio i=0.5~1.0, the clamping wheel 26 rotates quickly to tighten the nut 10.

[0024] like Figure 5 As shown, the middle cross-section of the driving double gear shaft 27 and the middle of the driven double gear shaft 28 are both square, the square center hole 2411 of the driving double gear is matched with the middle clearance of the driving double gear shaft 27, the square center hole 2511 of the driven double gear and the square center hole 2611 of the pressure wheel are respectively matched with the middle clearance of the driven double gear shaft 28, such a structure facilitates the up and down movement of the driving double gear 24 when shifting gears.

[0025] The clamping wheel lifting device 3 and the clamping wheel lateral movement device 4 are respectively located between the hydraulic bolt tensioner 1 and the clamping wheel driving device 2. The clamping wheel lifting device 3 includes a dovetail block 31 and a dovetail groove 32. The dovetail groove 32 is vertically fixed on the top of the box body 23 and is located between the drive motor 21 and the right side of the hydraulic bolt tensioner 1. The dovetail block 31 is embedded in the dovetail groove 32.

[0026] The clamping wheel transverse shifting device 4 is located between the right side of the hydraulic bolt tensioner cylinder body 11 and the dovetail block 31, and includes a transverse shifting cylinder 41 and a guide mechanism 42 respectively located between the four corners of the dovetail block 31 and the hydraulic bolt tensioner cylinder body 11. The cylinder body of the transverse shifting cylinder 41 is a countersunk hole 411 in the middle of the right side of the hydraulic bolt tensioner cylinder body 11, and the piston 413 at the left end of the piston rod 412 extends into the countersunk hole 411. The screw plug 43 serving as a cylinder cover closes the outer end of the countersunk hole 411, and the right end of the piston rod 412 passes through the screw plug 43 and is fixed to the center of the lower outer side of the dovetail block 31.

[0027] The guide mechanism 42 includes a sleeve 421, a sliding shaft 422, a spring 423 and a limit screw 424. The left end of the sleeve 421 is fixed to the right side of the hydraulic bolt tensioner cylinder 11, and the right end of the sliding shaft 422 is fixed to the dovetail block 31. The left end of the sliding shaft 422 extends into the right end of the sleeve 421. The two ends of the spring 423 are respectively against the bottom of the sleeve 421 and the end of the left end of the sliding shaft 422. The limit screw 424 passes through the axial groove 4211 at the right end of the sleeve 421 and is vertically screwed into the middle of the sliding shaft 422. The guide mechanism 42 at the four corners of the dovetail block 31 plays a precise guiding role in the lateral movement of the drive motor 21 and the gearbox 22, so that the clamping wheel 26 pressed on the nut 10 will not move in the vertical direction, ensuring that the clamping wheel 26 tightens or loosens the nut 10 through friction transmission.

[0028] like Figure 1 , Figure 2 , Figure 4 and Figure 5As shown, the fork mechanism 29 includes a stepped sleeve 291, a fork body 292 and a vertical shaft 293. The center of the stepped sleeve 291 is provided with a stepped sleeve square center hole 2911 which is clearance matched with the middle part of the active double gear shaft 27. The two ends of the stepped sleeve 291 are fixedly connected to the active double gear upper gear 241 and the active double gear lower gear 242. The fork mouth at the left end of the fork body 292 is embedded in the neck of the stepped sleeve 291, and the right end of the fork body 292 is sleeved on the middle part of the vertical shaft 293, and the two are clearance matched. The two ends of the vertical shaft 293 are supported on the upper and lower sides of the box 23 respectively, and the left end of the handle 294 is hinged to the right end of the fork body 292, and the left end of the handle 294 passes through the lifting slot 232 on one side of the box 23. The top of the lifting slot 231 is provided with a locking transverse slot 233. When the shift fork body 292 drives the active double gear 24 to move up to the right position, the right end of the handle 294 is embedded in the locking transverse groove 233 to lock the meshing of the active double gear 24 and the driven double gear 25.

[0029] A drive motor program switch 5 is installed on one side of the middle of the lifting slot 232. The drive motor program switch 5 is triggered by the upward or downward movement of the handle 294. When the handle 294 moves upward to trigger the drive motor program switch 5, the lower gear signal of the gearbox 2 is transmitted, indicating that it is in the slow gear for loosening the nut 10. At this time, after pressing the drive motor start switch, the clamping wheel 26 can only drive the nut 19 to rotate counterclockwise to tighten the nut 10. When the handle 294 moves downward to trigger the drive motor program switch 5, the upper gear signal of the gearbox 2 is transmitted. The upper gear signal indicates that it is in the fast gear for tightening the nut 10. After pressing the drive motor start switch, the clamping wheel 26 can only drive the nut 19 to rotate clockwise to tighten the nut 10, ensuring the safety of the use of the present invention.

[0030] Figure 6 As shown, when the nut 10 is a hexagonal nut, the nut 10 can be tightened or loosened using the present invention only after a sleeve 101 having a hexagonal inner hole 102 matching the outer circumference of the hexagonal nut is put on.

[0031] The use process of the present invention is as follows:

[0032] A nut 10 is tightened on the elongated high-strength bolt 20

[0033] A1) First tighten the nut 10 onto the high-strength bolt 20 until the bottom surface of the nut 10 abuts against the mounting base 30, then install the hydraulic bolt tensioner 1 onto the end of the high-strength bolt 20, start the hydraulic bolt tensioner 1, and under the action of the 1700Mpa~1500Mpa ultra-high pressure hydraulic oil of the hydraulic bolt tensioner, the high-strength bolt 20 is stretched until a gap L1 appears between the bottom surface of the nut and the mounting base 30, at which time the external oil pump stops pressurizing and maintains the pressure.

[0034] A2) Start the clamping wheel transverse shift device 4, press the forward button of the transverse shift cylinder 41, and the corresponding solenoid valve is switched to inject high-pressure oil into the transverse shift cylinder 41, pushing the piston rod 412 to move left, driving the clamping wheel driving device 2, the clamping wheel lifting device 3 and the clamping wheel transverse shift device 4 to move left, so that the clamping wheel 26 is pressed against the outside of the nut 10.

[0035] A3) Determine the fast gear position of the gearbox 22, move the handle 294 downward, the upper gear 241 of the active double gear meshes with the upper gear 251 of the driven double gear, and the clamping wheel 26 rotates rapidly to drive the nut 10 to rotate clockwise until the gap L1 is eliminated to complete the pre-tightening of the nut 10. At the same time, the clamping wheel 26, the clamping wheel driving device 2, the clamping wheel and the clamping wheel lateral movement device 4 descend along the dovetail groove 32 of the clamping wheel lifting device 3.

[0036] A4) Press the backward button of the transverse shift cylinder 41, and the corresponding solenoid valve is switched to inject high-pressure oil into the transverse shift cylinder 41, pushing the piston rod 412 to move right, driving the clamping wheel driving device 2, the clamping wheel lifting device 3 and the clamping wheel transverse shift device 4 to move right, so that the clamping wheel 26 is disengaged from the nut 10.

[0037] B Remove the nut 10 tightened on the stretched high-strength bolt 20

[0038] B1) Install the hydraulic bolt tensioner 1 onto the end of the high-strength bolt 20, start the hydraulic bolt tensioner 1, and under the action of the 1700Mpa~1500Mpa ultra-high pressure hydraulic oil of the hydraulic bolt tensioner, the high-strength bolt 20 is stretched until a gap L1 appears between the bottom surface of the nut and the installation base surface 30. At this time, the external oil pump stops pressurizing and maintains the pressure.

[0039] B2) Repeat the action of step A2) to press the clamping wheel 26 against the outside of the nut 10.

[0040] B3) Determine the slow gear position of the gearbox 22, move the handle 294 upward, and lock the handle 294 in the locking transverse groove 233. The lower gear 242 of the active double gear meshes with the lower gear 252 of the driven double gear, and the clamping wheel 26 rotates slowly to drive the nut 10 to rotate counterclockwise, and the nut 10 moves upward. At the same time, the clamping wheel 26, the clamping wheel driving device 2, and the clamping wheel transverse moving device 4 move upward along the dovetail groove 32 of the clamping wheel lifting device 3, and the nut 10 is loosened.

[0041] B4) Repeat the action in A4) and the clamping wheel 26 will be separated from the nut 10.

[0042] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A nut assembly and disassembly tool for pre-tightening bolts, comprising a hydraulic bolt tensioner, It is characterized in that It also includes a clamping wheel driving device, a clamping wheel lifting device and a clamping wheel lateral movement device. The clamping wheel driving device is located outside one side of the hydraulic bolt tensioner, and includes a driving motor and a gearbox. The gearbox includes a box body, an active double gear, a driven double gear, a clamping wheel, an active double gear shaft, a driven double gear shaft and a fork mechanism. The driving motor is vertically fixed on the upper side of the box body, and the bottom of the box body is supported on one side of the bottom of the hydraulic bolt tensioner by a skeleton spring. One side of the box body adjacent to the window of the hydraulic bolt tensioner cylinder is open, and the driving motor shaft is connected to the hydraulic bolt tensioner through a torque overload protection clutch. The upper end of the active double gear shaft vertically supported in the box is fixedly connected, the upper gear of the active double gear, one end of the fork mechanism and the lower gear of the active double gear are sequentially inserted and positioned on the middle part of the active double gear shaft from top to bottom; the upper gear of the driven double gear, the pressure wheel and the lower gear of the driven double gear are sequentially inserted and positioned on the middle part of the driven double gear shaft from top to bottom, and the two ends of the driven double gear shaft and the lower end of the active double gear shaft are respectively supported in the box through corresponding bearings; the pressure wheel lifting device and the pressure wheel lateral movement device are respectively located between the hydraulic bolt tensioner and the pressure wheel driving device; The number of teeth on the upper gear of the active double gear is greater than the number of teeth on the upper gear of the driven double gear, and the number of teeth on the lower gear of the active double gear is less than the number of teeth on the lower gear of the driven double gear; when the active double gear moves up to the position, the lower gear of the active double gear meshes with the lower gear of the driven double gear, and the pressure wheel rotates slowly; when the active double gear moves down to the position, the upper gear of the active double gear meshes with the upper gear of the driven double gear, and the pressure wheel rotates quickly; The shift fork mechanism includes a stepped shaft sleeve, a shift fork body and a vertical shaft. A square center hole of the stepped shaft sleeve is provided in the center of the stepped shaft sleeve, which is clearance-matched with the middle part of the active double gear shaft. The two ends of the stepped shaft sleeve are fixedly connected to the upper gear of the active double gear and the lower gear of the active double gear respectively. The fork opening at one end of the shift fork body is embedded in the neck of the stepped shaft sleeve, and the other end of the shift fork body is sleeved on the middle part of the vertical shaft. The two ends of the vertical shaft are respectively supported on the upper and lower sides of the box body, and one end of the handle is hinged to the other end of the shift fork body, and the other end of the handle passes through the lifting slot on one side of the box body.

2. The nut assembly and disassembly tool for pre-tightening bolts according to claim 1, It is characterized in that The middle cross-section of the active double gear shaft and the middle cross-section of the driven double gear shaft are both square, the square center hole of the active double gear and the middle clearance of the active double gear shaft match, the square center hole of the driven double gear and the square center hole of the pressure wheel respectively match the middle clearance of the driven double gear shaft.

3. The nut assembly and disassembly tool for pre-tightening bolts according to claim 1, It is characterized in that The clamping wheel lifting device includes a dovetail block and a dovetail groove. The dovetail groove is vertically fixed on the top of the box body and is located between the driving motor and one side of the hydraulic bolt tensioner. The dovetail block is embedded in the dovetail groove. The clamping wheel transverse movement device is located between one side of the hydraulic bolt tensioner cylinder body and the dovetail block.

4. The nut assembly and disassembly tool for pre-tightening bolts according to claim 3, It is characterized in that The clamping wheel transverse movement device includes a transverse movement cylinder and a guide mechanism respectively located between the four corners of the dovetail block and the cylinder body of the hydraulic bolt tensioner. The cylinder body of the transverse movement cylinder is a countersunk hole in the middle of one side of the cylinder body of the hydraulic bolt tensioner. The piston at one end of the piston rod extends into the countersunk hole, and the screw plug serving as the cylinder cover closes the outer end of the countersunk hole. The other end of the piston rod passes through the screw plug and is fixed on the lower center of the outer side of the dovetail block.

5. The nut assembly and disassembly tool for pre-tightening bolts according to claim 4, It is characterized in that The guiding mechanism comprises a sleeve, a sliding shaft, a spring and a limit screw. One end of the sleeve is fixed on one side of the cylinder body of the hydraulic bolt tensioner, one end of the sliding shaft is fixed on the dovetail block, the other end of the sliding shaft extends into the other end of the sleeve, two ends of the spring are respectively against the bottom of the sleeve and the other end of the sliding shaft, and the limit screw passes through the axial groove at the other end of the sleeve and is vertically screwed into the middle part of the sliding shaft.

6. The nut assembly and disassembly tool for pre-tightening bolts according to claim 1, It is characterized in that The top of the lifting slot is provided with a locking transverse slot; when the shift fork body drives the active double gear to move up to the right position, the other end of the handle is embedded in the locking transverse slot to lock the active double gear.

7. The nut assembly and disassembly tool for pre-tightening bolts according to claim 1, It is characterized in that A driving motor program switch is arranged on one side of the middle part of the lifting slot.

8. The nut assembly and disassembly tool for pre-tightening bolts according to claim 1, It is characterized in that The outer peripheral surface of the pressing wheel is provided with mesh patterns.

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