JPS6055252B2 - Multi-axis bolt automatic tightening device - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention is directed to the maintenance and maintenance of a large number of bolts during periodic inspection of a control rod drive device installed at the bottom of a nuclear reactor (B, W, R), for example. This invention relates to an automatic multi-axis bolt tightening device used for tightening (tightening) or loosening (removal).

[Technical background of the invention and its problems]

This type of automatic bolt tightening device called a nut runner that has already been proposed includes a hydraulic or electric type shaft bolt tightening device.

However, for example, on a pier where a large number of control rod drive devices (C, R, D) installed at the bottom of a nuclear reactor are fixed with eight bolts each, regular inspections are required. Each control rod drive requires the installation and removal of multiple control rod drives.

Moreover, the bottom of the reactor is an atmosphere with particularly high radiation concentration in a nuclear reactor, and in the past, workers were exposed to radiation because they had to directly install or remove tightening bolts one by one. There is a strong desire to avoid this. That is, as shown in FIG. 1, the control rod drive device is provided with a control rod drive mechanism exchange chamber a at the bottom of the pressure vessel of the nuclear reactor, and this peripheral wall is formed into a cylindrical shape. An annular rail d is provided on a support stand c protruding from b,
A platform e is made rotatable like a turntable on this rail d via wheels e1, and a movable trolley f that can run is mounted on this platform e. The control rods installed at the bottom of the furnace can be moved freely to any position, and on the other hand,
The movable cart f is provided with a beam g that can be swung horizontally or vertically by a hydraulic cylinder device, for example, and the beam g
Sprockets H, i, and j are mounted on the upper and lower parts, a chain k is wound around them, and this chain k is operated by a reversible drive device e, and a control rod drive device is attached to the chain k. It is equipped with a mechanism m, a drainage device n for storing and draining reactor water that comes out when extracting a control rod etc. from the reactor bottom, and a support base p for supporting a bolt tightening device, etc.
Accordingly, during periodic inspection, each bolt on the hearth bottom is removed or installed one by one using the bolt tightening device.

In this way, the above-mentioned bolt tightening device has to install and remove each bolt one by one under harsh conditions of high temperature, high humidity, and radiation, which reduces work efficiency and reduces work safety. There were also difficulties from a gender perspective.

[Object of the Invention] In view of the above-mentioned points, the present invention has been developed to quickly and efficiently tighten and remove a plurality of bolts using a large number of box spanners in one process and with a constant torque. The purpose is to simplify bolt tightening work, etc. The present invention provides a multi-axis bolt automatic tightening device.

[Summary of the Invention] The present invention provides a pair of support discs constituting an output gear of a differential gear device housed in a gear box. An arm is rotatably mounted concentrically with an output shaft connected to the electric motor via a torque limiter and a speed reducer, and is provided around the axis of the output shaft so as to rotate in conjunction with the output shaft. A pin shaft is provided on the rod, and a differential pinion that commonly meshes with the first gear provided on the circumference (surrounding part) of each of the support disks is attached to the pin shaft, and A rotary shaft for driving a spanner, which is rotatably supported by the gear box, is interlocked with the second gear provided so that the tightening torque of each spanner is the same. There is also a second invention in which the three pairs of support discs constituting the output gear of the differential gear device housed in the gear hook are concentric with the output shaft connected to the electric motor via a torque limiter and a speed reducer. A pin shaft is provided on an arm rod protruding from the output shaft in a radial direction, and a pin shaft is provided on the pin shaft at a peripheral portion l of one of the three pairs of support discs. A differential pinion that meshes with each gear is installed,
Each rotating shaft of the pair of support disks arranged concentrically with the output shaft is provided with an arm rod that rotates in conjunction with the rotating shaft, and a pin shaft provided on each arm rod is provided with a pin shaft, A differential pinion that meshes commonly with each pair is attached to a first gear provided on the periphery of the other two pairs of support disks, and a differential pinion is provided on the outer peripheral surface of the other two pairs of support disks. A rotary shaft for driving a wrench, which is rotatably supported by the gear box, is interlocked and connected to the second gear with a wrench so that the tightening torque of each wrench is the same. be.

[Embodiments of the invention]

Hereinafter, the present invention will be described with reference to an illustrated embodiment.

In FIG. 2, reference numeral 1 denotes an electric motor capable of reversible rotation, and the output shaft 1a of this electric motor 1 is provided with a torque limiter 2 and a speed reducer 3 shown in FIG. A differential gear device 5 housed in a gear box 4 is attached to the output shaft 3a of the machine 3, and each rotating shaft 5a is supported by the gear box 4 and driven by the differential gear device 5. , 5b has a plurality of box-shaped spanners 6.
a and 6b are attached.

That is, the differential gear device housed in the gear box 4 is constructed as shown in FIGS. 2 to 5.

That is, the output shaft 3a is provided with a pair of support discs 9, 1, which constitute the output gear of the differential gear device, via the respective bearings 7, 8.
0 is mounted on a shaft, and internal gears (hereinafter referred to as internal gears) 9a, 10a constituting a first gear are provided around the support discs 9, 10, and a second gear is provided on the outer peripheral surface. External gears (hereinafter referred to as external gears) 9b, 10 forming the gears of
b are each integrally formed. Further, the base of an arm rod 11 that protrudes in the radial direction is firmly mounted on the output shaft 3a, and a pin shaft 1 is attached to the free end of this arm rod 11.
2 and 13 are firmly planted. Furthermore, each pin shaft 12
, 13 are loosely fitted with pinions 14 and 15 that are axially offset from each other. Both pinions 14 and 15 are partially meshed with each other, and one pinion 14 is connected to the internal gear. The other pinion 15 meshes with the internal gear 10a, and the two pinions 14 and 15 constitute one differential pinion. Furthermore, the external gears 9b, 10
In b, each gear 1 attached to each of the rotating shafts 5a, 5b is shown.
6 and 17 are in mesh with each other, and the teeth 16 and 17 can rotate together in the same direction. On the other hand, as shown in FIGS. 6 and 7, the torque limiter 2 is incorporated into a rotating cylinder 18 provided at one end of the output shaft 1a.

That is, a lid 19 is firmly attached to the opening of the rotary cylinder 18, and a driven shaft 2a is rotatably mounted on the lid 19 and each bearing 20a, 20b at the rear end of the rotary cylinder 18. It is mounted on the shaft. Further, a one-way clutch 21 of a trailing wave type is provided on the driven shaft 2a at a position close to the bearing 20a, and this one-way clutch 21 rotates the rotating cylinder 18 as shown in FIG. When the rollers 21a rotate in the direction opposite to the arrow direction, each roller 21a moves toward the narrower gap between the rotary cylinder 18 and the one-way clutch 21, becomes biting, and rotates the driven shaft 2a; , when the rotating cylinder 18 is rotated in the direction of the arrow, each roller 21 moves to the side with a wide gap between the rotating cylinder 18 and the one-way clutch 21, allowing it to escape, and the relationship between the driven shaft 2a and the rotating cylinder 18 is as follows. Can be rotated freely. Further, a spline groove 22 is provided on the inner circumferential surface of the rotating cylinder 18, and splines formed on the outer circumference of three friction ring plate-shaped clutch plates 23 are engaged with the spline groove 22. A friction plate 24 is interposed between each clutch plate 23 and engages with a spline 26 formed on the driven shaft 2a. Therefore, they are pressed together in the axial direction.

Therefore, when the rotary cylinder 18 integrated with the output shaft 1a is rotated counterclockwise (counter-arrow direction), this rotational force is transmitted to the driven shaft 2a via the one-way clutch 21, and a large torque is transmitted to the driven shaft 2a. added to.

On the other hand, when the rotating cylinder 18 is rotated clockwise, power is transmitted to the driven shaft 2a via each clutch plate 23 and each friction plate 24. However, when a certain load is applied to the driven shaft 2a, the clutch plate 23 and the friction plate 24 slide, and the driven shaft 2a stops rotating. That is, when the bolt tightening limit is reached, the driven shaft 2a remains stationary and the rotary cylinder 18 rotates with play. Therefore, in order to tighten the two bolts now, the spanners 6a and 6b are fitted to each bolt in advance.

Next, when the electric motor 1 is rotated, the output shaft 3a drives the differential gear device 5 via the torque limiter 2 and the speed reducer 3, as described above. That is, when the output shaft 3a rotates clockwise as shown by the arrow in FIG. 4, the arm rod 11 of the output shaft 3a also rotates, so the pinion 15 rotates counterclockwise around the pin shaft 13. The pinion 14 also tries to rotate counterclockwise about the pin shaft 12. However, since the pinions 14 and 15 are in mesh with each other, their rotation is restrained, and the internal gears 9a,
Both support disks 9, 10 rotate together clockwise via 10a. Therefore, the external gears 9b, 1 of both support discs 9, 10
Each rotating shaft 5 is connected via gears 16 and 17 meshing with
a, 5b are rotated, and each bolt is tightened by each swivel 6a, 6b. Here, each of the above subanas 6
Since each bolt tightened by bolts a and 6b has a slight difference in tightening stroke,
One of the bolts reaches the final stroke position of the bolt first.

7. Therefore, if the spanner 6a reaches its final stroke first, the gear 16 will stop rotating.

Following this, the internal gear 9a also stops. Therefore, the pinion 14 that meshes with this rotates on the inner circumference of the internal gear 9a,
Internal gear 1 that drives and meshes with another pinion 15
0a is rotated at increased speed, the spanner 6b is rotated via the gear 17 meshing with the external gear 10b, and the other bolts are tightened at high speed to the final stroke and then stopped. In this way, when the internal gear 10a stops, the arm rod 11 and the reducer 3 also stop, and the torque reaches a certain level or more, the torque limiter 2 slips and the rotational force of the electric motor 1 is reduced further by the spanners 6a, 6b. will not join. In this case, as a characteristic of the differential gear device 5, the same driving force is acting on both the internal gears 9a and 10a, so the slip starting torque of the torque limiter 2 becomes the appropriate torque for tightening the bolts with each spanner 6a and 6b. If the spanners 6a and 6b are adjusted so that the bolts are tightened evenly, the final tightening torque will be accurate, even if there are differences in the tightening stroke of each bolt with the tightening hand, and each bolt will be tightened uniformly. It can be tense.

Next, the embodiment shown in FIG. 8 is another embodiment of the present invention, in which four spanners 6a, 6b, 6c, 6
d, and a differential gear device 5 for driving this is incorporated.

That is, in this embodiment, another arm rod 1'' is provided on the output shaft 3a, and the pinion 1'' shown in FIG.
The arm rod 11 is fixed to the rotating shaft of a support disk 29 which has two pinions 27 and 28 similar to those shown in FIGS. Attach the pinions 14 and 15 to each wrench 6a.
, 6b, and rotate the other pin,
A support disk 30 having an internal gear 30a with which the on 27 meshes
An arm rod 11'' is fixed to the rotating shaft of the arm rod 11'', and a third
Pinions 14'' and 15'' having the same configuration as those shown are attached.

The pinions 14'', 15'' are supported by supporting discs 9'',
1 “In the internal gear of! mesh, and put a wrench 6c on the external gear.
Gears 16'' and 17'' attached to the rotating shaft 6d are meshed with each other. Therefore, the rotation of the support disk 29 operates the spanners 6a, 56b via the pinions 14, 15, etc., and the rotation of the support disk 30 operates the pinion 1.
The spanners 6c and 6d are operated through the screws ``, 15'', etc.

Therefore, when the differential gear device 5 is driven, each spanner 6
The bolts a, 6b, 6c, and 6d tighten each bolt in one step with uniform torque, and have substantially the same effect as the specific example described above. Next, the embodiment shown in FIGS. 9 and 10 is another embodiment of the present invention.
This was an attempt to tighten the bolts of a book in one operation without raising and lowering the device or replenishing the bolts.

That is, in the multi-axis bolt automatic tightening device that can simultaneously tighten four bolts shown in FIG.
A pair of gears 16a and 16b are meshed with each other, and the gears 16a and 16b are arranged so that the upper spanners 6a'' and 6b'' are at the required bolt tightening position. spanner 6
The gears 16a and 16b for rotation a″ or 6a″ are connected to the rotating shaft 3.
2, and this rotation shaft 32 is provided with a spline 31. An engaging portion 33a of the clutch 33 is attached to the spline 31 portion so as to be movable only in the axial direction, and the spline 33a of the rotating shaft 32
A fifth engaged portion 33b is supported above the portion via a bearing. Each shaft 33b'' is attached to the top of the engaged portion 33b.
is provided protrudingly, and a spanner 6a'' or 6a is attached to each shaft 33b''.
'' is supported so as to be movable up and down, and at the same time, the square shaft 33''b is configured to transmit rotational force even when it is moved up and down.Furthermore, the engaged portion 33b and the spanner 6a''(6a'') are A spring 56 is interposed between them. The above clutch device 3
The engaging portion 33a of No. 3 is a swinging lever 35 pivotally connected with a pin 55.
are connected by.

Although not shown in FIGS. 9 and 10, one of the clutch engaging portions 33a is coupled to the corresponding engaged portion 33b due to the action of the drive device that swings the swinging lever 35. , the driving force from the gear 16a or 16b is transmitted to one of the spanners 6a'' or 6a''. When using such a device, the eight bolts are held by the spanners 6a'' and 6a'', respectively, and brought close to the bolt tightening portion until they are crimped, and the swinging lever 35 is tilted, so that one of the clutches is not engaged. The mating portion 33a is engaged with the engaged portion 33b, and the bolt tightening device is activated.

When the mechanism shown in FIG. 9 is activated by driving the motor 1, four bolts are automatically tightened at once. At this time, the bolt being tightened rises, but the spring 56 also slides on each shaft 33b'' and pushes the sub-bana 6a'' or 6a'' upward, and the bolt tightening torque is transmitted. When the four bolts have been tightened by this operation, the swinging lever 35 is tilted in the opposite direction, and the wrench 6a'' or 6 on the side that has not yet been tightened is tilted in the opposite direction.
If a'' is driven in the same manner, eight bolts can be tightened in one step without the need to change the automatic bolt tightening device. As another embodiment of the device of the present invention, the device of FIGS.
By incorporating it into the device shown in the figure, it becomes possible to configure it as a device for tightening four bolts.

Next, another embodiment of the present invention shown in FIG.
Instead of the differential gear device 5 using spur gears shown in the figure, the design is changed to a differential gear device 5 using bevel gears, and the content is substantially the same as that of the embodiment shown in FIG. 2. There are things.

That is, bevel gears 9a'' and 10a'' constituting the first gear are provided concentrically on the mutually opposing surfaces of the support discs 9 and 10, and both gears 9a'' and 10a''
A pinion 14 made of a bevel gear constituting a differential pinion is interposed between them, and the pinion 14 is commonly meshed with both gears 9a'' and 10a''.

The pin on which this pinion 14 is mounted is the output shaft 3a.
It is integrally formed with the arm rod 11 fixed to. The other points are the same as the first embodiment shown in FIG. 2, and the same operation is performed. Next, an embodiment in which a bolt loosening device is incorporated into a multi-axis bolt automatic tightening device according to the present invention will be described.

12 and 13, reference numeral 3a is the output shaft of the reduction gear 3, and a drive disk 37 having a notch 37a is firmly mounted on the output shaft 3a''. The arm rod 1 is disposed on the output shaft 3a adjacent to the disc 37.
1 is loosely mounted.

Moreover, as mentioned above, this arm rod 11 has a pin shaft 12,
13 is implanted, and each pin shaft 12, 13 has a
Pinions 14 and 15 are mounted on shafts and are rotatably mounted at mutually shifted positions in the axial direction. Although the pinions 14 and 15 are axially offset, they mesh with each other at some parts, and moreover, the pinion 14 meshes with the internal gear 9a, and the pinion 15 meshes with the internal gear 10a. ing.

Since the pinions 14 and 15 are in mesh with each other in this way, when the output shaft 3a is driven, the pin shafts 12 and 13 move inside the internal gears 9a and 10a, thereby causing the internal gears 9a and 10a to move. are simultaneously driven with the same torque in the same direction as the rotational direction of the output shaft 3a.

This means that the pinions 14 and 15 have internal gears 9a and 10a.
A reaction force that drives the internal gears 9a and 9a acts on each other to rotate them in the same direction, but since the pinions 14 and 15 are meshed with each other and are not allowed to rotate in the same direction, the same torque drives the internal gears 9a and 9a. 10a. However, if one of the internal gears 9a and 10a is fixed, the force that rotates the output shaft 3a and the pinion 14
, 15, one of which rolls in a fixed internal gear, drives the other internal gear in the same direction as the rotational direction of the output shaft 3a, and the unfixed internal gear rotates at twice the speed. I will do it. Further, both ends of a support shaft 38 are loosely attached to the arm support rod 52 that is loosely fitted to the arm rod 11 and the output shaft 3a, and the support shaft 38 is provided with a support shaft 38, as shown in FIG. , a locking lever 39 and a pair of locking claws 40a, 4
0b is fixed. Furthermore, an extensible spring 41 is interposed between one end of the locking lever 39 and the arm lever 11, and the elasticity of this spring 41 causes each of the locking claws 4 to
0a and 40b are adapted to engage with the tooth bottoms of the respective internal gears 9 and 10. On the other hand, the other end 3 of the locking lever 39
9a extends into the notch 37a, and is connected to the arm rod 1.
1 is provided with a protrusion 42 on the rotation path of the other end 39a of the locking lever 39.

Therefore, when the driving disk 37 rotates clockwise as shown by the arrow in FIGS. 12 and 13 and pushes the protrusion 42, the entire arm rod 11 is moved around the rotating shaft 3a. rotate around.

Further, when the driving disk 37 rotates counterclockwise and pushes the other end 39a of the locking lever 39, the locking lever 3.
9 rotates to the right around the support shaft 38 against the elasticity of the spring 41 to separate the locking pawls 40a, 40b from the internal gears 9a, 10a to release the lock, and on the other hand, the other end Part 39a
is adapted to push the projection 42 to rotate the entire arm rod 11 in a counterclockwise direction around the output shaft 3a. Therefore, in order to loosen the two bolts, first fit the spanners 6a and 6b onto each bolt.

Next, when the electric motor 1 is rotated, the output shaft 3a drives the differential gear device 5 via the torque limiter 2 and the speed reducer 3, as described above. That is, when the output shaft 3a rotates in the clockwise direction, the drive disk 37 is moved to the arm rod 11 via the protrusion 42.
rotates around the output shaft 3a.

Then, since both locking pawls 40a and 40b bite into the bottoms of the respective internal gears 9a and 10a due to the elasticity of the spring 41, both internal gears 9a and 10a rotate clockwise in synchronization. That is, if the lock pawls 40a, 40b are not completely bitten together at first, the output shaft 3a is driven and the arm rod 11 is moved clockwise via the drive disc 37 and the protrusion 42. When rotated, the pinions 14 and 15 drive the internal gears 9a and 10a clockwise with the same torque.

However, at this time, if the bolt fitted to the spanner 6a is loosened and the other spanner 6b is tightened, the differential gear mechanism of each pinion 14, 15 causes the internal gear 1 to
0a is a stopped state), the pinion 15 rotates counterclockwise, the pinion 14 rotates clockwise, and the internal gear 9a rotates clockwise.

However, when the arm rod 11 rotates slightly clockwise, the locking pawl 40b strongly bites into the internal gear 10a, and a strong driving force acts on the internal gear 10a, causing each internal gear 9a, 10a rotate in synchronization, and while maintaining the same amount of rotation, each spanner 6a, 6b is rotated in the bolt loosening direction. Next, in the above embodiment, tightening of the two bolts is performed by the following operation.

That is, when the output shaft 3a is rotated counterclockwise in the direction opposite to the arrow in FIGS. 12 and 13, the driving disk 37 is rotated counterclockwise.

Then, the driving disk 37a pushes the locking lever 39, and the locking lever 39 is moved by the elasticity of the spring 41. supporting shaft 3 against
8, and thereby each locking pawl 40a
, 40b are spaced apart from each internal gear 9a, 10a. Then, the locking lever 39 comes into contact with the protrusion 42, and the arm lever 11 that pivotally supports each pinion 14, 15 rotates, thereby causing both internal gear wheels 9a, 10a to rotate counterclockwise, Each bolt is tightened at once. Finally, the embodiment shown in FIG. 14 is another embodiment in which a bolt loosening device is incorporated into the multi-axis bolt automatic tightening device according to the present invention, and this is the first embodiment.
This is a modification of the embodiment using the bevel gear differential gear device shown in FIG.

That is, in this embodiment, a drive disc 37 having a pair of notches 37a is firmly mounted on the output shaft 3a, and a pair of cam parts 37b are provided on the outer periphery of the drive disc 37.
Each protrusion 42 provided in the middle of 1 is connected to each notch 37
Furthermore, a radial guide groove 43 is formed in the arm rod 11 at a position close to each projection 42, and each lock pawl 40a, 40b is fitted in each guide groove 43. The internal gears 9a, 10a are slidably fitted so as to be able to engage with the tooth bottoms of the internal gears 9a, 10a by the elasticity of each spring 41, and each roller 44 is provided on each of the locking pawls 40a, 40b, Each of the rollers 44 is adapted to come into contact with each of the cam portions 37b.

Therefore, when the output shaft 3a rotates in the clockwise direction indicated by the arrow in FIG.
7b is connected to each lock via each roller 44, and each lock pawl 40a, 40b
from each internal gear 9a, 10a, each pinion 14,
Free rotation of 15.

On the other hand, when the output shaft 3a rotates counterclockwise, each cam portion 37b engages each locking pawl 40a, 40 via each roller 44.
b is locked to each internal gear 9a, 10a by the elasticity of the spring 41 and temporarily fixed.

Thus, the support disks 9 and 10 rotate together with the output shaft 3a, and the bolt can be loosened. [
[Effects of the Invention] As described above, according to the present invention, it is possible not only to tighten and remove a plurality of bolts and nuts at once with a plurality of spanners and with uniform torque in one process, but also to tighten and remove them with a uniform torque. By skillfully utilizing a dynamic gear system, each bolt can be tightened uniformly with accurate tightening torque even if there is a slight difference in the tightening stroke of each bolt.

Furthermore, the entire device can be constructed in a compact size and is easy to handle and operate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a control rod drive device for a nuclear reactor incorporating the automatic multi-axis bolt tightening device according to the present invention, FIG. 2 is a cross-sectional view of the automatic multi-axis bolt tightening device according to the present invention, and FIG. 4 is a front view of the same as above, FIG. 5 is a sectional view of the same as above, FIG. 6 is a sectional view of the torque limiter incorporated in the present invention, and FIG. 7 is a cross-sectional view of FIG. 6. 8 and 9 are diagrams showing other embodiments of the present invention, FIG. 10 is an enlarged sectional view of FIG. 9, and FIG. 11 is a diagram showing still another embodiment of the present invention. FIG. 12 is a front view of the bolt loosening device incorporated into the differential gear device of the multi-axis bolt automatic tightening device of the present invention.
FIG. 13 is a perspective view showing only the main parts of FIG. 12;
FIG. 14 is a diagram showing another embodiment incorporating the bolt loosening device described above. DESCRIPTION OF SYMBOLS 1... Electric motor, 2... Torque limiter, 3... Reducer, 5... Differential gear device, 6a, 6b... Wrench, 9, 10... Support disk, 9a, 10a. ... Internal gear, 9b, 10b... External gear, 11... Arm rod, 14,
15...pinion, 16,17...gear.

Claims (1)

[Claims] 1. A pair of support discs constituting an output gear of a differential gear device housed in a gear box are arranged concentrically and concentrically with an output shaft connected to an electric motor via a torque limiter and a speed reducer. A pin shaft is provided on an arm rod that is rotatably mounted and rotates around the axis of the output shaft in conjunction with the output shaft, and a pin shaft is attached to the pin shaft around the peripheral portion of each of the support disks. A differential pinion that meshes commonly with first gears provided on each of the support disks is mounted, and a second gear provided on the outer peripheral surface of each of the support disks is equipped with a rotation for driving a spanner that is pivotally supported on the gear box. A multi-axis bolt automatic tightening device characterized by interlocking the shafts via gears so that the tightening torque of each spanner is the same. 2. The three pairs of support discs that constitute the output gears of the differential gear device housed in the gear box are mounted concentrically and rotatably with the output shaft connected to the electric motor via the torque limiter and reducer. At the same time, a pin shaft is provided on an arm rod projecting in a radial direction from the output shaft, and the pin shaft is commonly meshed with each gear provided around one of the three pairs of support discs. A differential pinion is attached to each of the rotation shafts of the pair of support disks, which are arranged concentrically with the output shaft, and an arm rod that rotates in conjunction with the rotation shaft is provided. The first pin shaft provided on the periphery of the other two pairs of support disks is attached to the pin shaft.
A differential pinion that meshes commonly with each pair of gears is installed, and a second gear provided on the outer peripheral surface of the other two pairs of support disks is used to drive a spanner that is pivotally supported by the gear box. A multi-axis bolt automatic tightening device characterized by interlocking rotating shafts via gears so that the tightening torque of each wrench is the same.