JPS6156070B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a bolt tightening machine for tightening a special bolt equipped with a shearing tip at the tip, and when a rotational torque exceeding a certain level is applied to the shearing tip, the tip is sheared and a certain torque is applied. This invention relates to a bolt tightening machine that can tighten bolts.

Conventionally, by using a torque control bolt 9 shown in FIG. 6, the bolt is tightened to a predetermined torque, thereby eliminating variations in tightening force and loosening of the bolt.

The above-mentioned torque control bolt has a shearing chip 91 protruding from the tip of the screw shaft 94, and when tightened with a bolt tightening machine dedicated to the torque control bolt, if a rotational torque exceeding a certain level is applied to the bolt, the screw will tighten. Stress is concentrated at the groove bottom portion of the circumferential groove 95 between the shaft 94 and the tip 91, and the tip 91 is sheared from the circumferential groove 95 portion with the maximum shearing stress determined by the groove shape. Therefore, it can be determined at a glance whether or not the tip 91 has been sheared, that is, whether or not it has been completely tightened.

For example, a tightening machine exclusively for torque control bolts is disclosed in U.S. Pat.
As disclosed in Japanese Patent Application No. 29598, an inner socket 6 and an outer socket 7 are provided at the tip of the tightening machine, respectively connected to the drive device 1, and the inner socket 6 is connected to a shearing tip at the tip of the bolt shaft. 91
Then, the outer sockets 7 are fitted to the nuts screwed onto the bolts, respectively, and the drive device 1 is operated, and the tightening reaction force of the nuts is supported by the bolt tips via the inner sockets, and the bolt nuts are sheared by shearing the bolt tips. The tightening torque between the two is regulated. However, the above-mentioned tightening machine is not equipped with a device to prevent incomplete fitting between the inner socket 6 and the bolt tip 91, and is hidden in the outer socket 7 and may cause the inner socket and the bolt tip to be incompletely fitted. There is a risk that the connectors may enter a tightened state while they are in a properly fitted state.

If the tightening machine operates while the tip 91 is not fully inserted into the inner socket 6, that is, the pressure receiving area of the tip relative to the inner socket is small, the surface pressure of the tip will increase and the tip will not be able to withstand the rotational force. The corner of the tip is deformed into a rounded shape, causing idle rotation between the tip and the socket. In this case, the bolt itself becomes unusable due to the deformation of the tip, and the inner surface of the socket is damaged, and the unexpected tightening reaction force causes the tightening machine to There was a problem that it was dangerous for workers to join the workers through the work.

Therefore, the applicant proposed a device for preventing incomplete fitting between the inner socket 6 and the bolt tip 91 shown in FIG. 11 (Japanese Patent Publication No. 36640/1983).

This allows a protruding pin 5 biased by a spring in the protruding direction to protrude and retract into the inner socket 6, and is formed in the holder 3 for the inner socket through a hole 80 formed through the side wall of the inner socket 6. A spherical stopper 4 is arranged so as to be able to protrude and retract from the abutment surface 35, and at the forward position of the ejecting pin 5, the large diameter portion 50 of the pin 5 moves the stopper 4 to the abutment surface 35.
This feature is characterized in that the inner socket 6 is locked in the forward position.

When the bolt tip 91 is fitted into the engagement hole 60 of the inner socket 6 when tightening the bolt nut, the protruding pin 5 in the socket 6 is inserted into the tip 91.
When the bolt tip 91 is completely fitted into the engagement hole 60 and the ejector pin 5 is further moved back, the large diameter portion 50 on the pin 5 is moved from the stopper position. Comes off and stopper 4
is released, the stopper 4 sinks into the socket 6 and comes off the abutment surface 35, releasing the lock of the inner socket 6 and allowing the inner socket 6 to move backward.

Continue pushing the entire tightening machine onto the bolt,
As long as the inner socket 6 is fitted with the chip 91,
It moves backward in the holder 3 against the inner socket push-out spring 62 and enters the engagement hole 70 of the outer socket.
The nut 92 on the bolt 9 fits into the hole.

The tightening operation is as described above, and after tightening,
Inner socket 6 has sheared bolt tip 9
1 is running idly as soon as it is fitted, but when the tightener is pulled out from the nut 92, the inner socket extrusion spring 62 pushes the tip 63 of the inner socket 6 into the nut engagement hole 70 of the outer socket 7. let

Thereafter, when the ejector pin 5 is ejected by the ejector pin extrusion spring 52, the pin 5 knocks out the shearing chip 91 remaining in the inner socket 6.

At this time, the large diameter portion 50 on the pin 5 again corresponds to the hole 80 in the inner socket side wall, and the stopper 4
A part of the inner socket 6 is brought out of the socket 6 and pressed against the contact surface 35 of the holder 3, and the inner socket 6 is locked in the forward position in the same manner as described above.

As mentioned above, unless the bolt tip is completely fitted into the tip engaging hole 60 of the inner socket 6 and the protruding pin 5 is retracted, the lock at the forward position of the inner socket 6 will not be released, and therefore the inner socket 6 will not be locked in the forward position. The socket 6 is moved back and the nut 92 is prevented from fitting into the engagement hole 70 of the outer socket 7, and there is a risk that the tightening operation will start with the inner socket and bolt tip incompletely fitted, as in the conventional case. There isn't.

However, it has been found that the incomplete fitting prevention device described above has the following problems.

That is, in order to reliably knock out the chip from the inner socket 6, it is desirable that the tip of the protruding pin 5 reach the tip of the inner socket 6 as much as possible. However, if the tip of the protruding pin 5 is made too long, when the bolt tip 91 is fitted into the inner socket 6 during tightening, the protruding pin will be able to move backward without the bolt tip being fully fitted into the inner socket 6. The lock provided by the stopper is released, allowing the inner socket to retreat, and does not play a role in preventing incomplete fitting.

To deal with this problem, as shown in Figure 12,
It is conceivable to move the stopper backward and lengthen the large diameter portion 50 of the ejector pin 5, that is, the portion that holds the stopper in the locking position. In this case, the inner socket 6 is allowed to retreat after the chip 91 is fully inserted into the inner socket 6.However, when the chip is ejected, the tip of the ejector pin 5 reaches near the tip of the inner socket 6. It is possible to prevent chip ejection failure. However, as the length of the machine increases, the tightening machine inevitably becomes larger, making it difficult to handle.

Also, after shearing the chip, when the tightening machine is removed from the nut, the inner socket 6 containing the chip will be removed.
moves forward, and the stopper 4 reaches a position corresponding to the contact surface 35.

In this case, depending on the angular position of the stopper 4, it may or may not engage with the contact surface 35.

When the ejector pin 5 is protruded by the spring 52 in a state where the stopper 4 is not engaged with the contact surface 35, the large diameter portion 50 of the ejector pin 5 hits the stopper and interferes with it.
Sometimes the ejection force was weakened.

The present invention prevents damage to the socket and improves work safety by disposing a detection member that slides independently of the ejecting pin so that it can move in and out of the chip engagement hole of the inner socket. The purpose is to realize a collision prevention device and solve the problems of conventional bolt fasteners at once.

As shown in FIG. 1, the bolt tightening machine according to the present invention has an inner socket 6 and an outer socket 7 arranged concentrically with respect to a casing 11 containing a rotary drive device 1 so as to be orthogonal to the casing 11. ing.

The rotation drive device 1 rotates the drive motor 12 by 3 rotations.
The rotating shaft 13 of the motor 12 is connected to the bevel gear 1 through the planetary gear devices 15, 16, and 2 of the stage.
4, 14a to the first stage planetary gear unit 15
It is connected to the sun gear 15a. Support frame 15c of the planet gear 15b of the first stage planetary gear device 15
is the sun gear 16a of the second stage planetary gear device 16.
The support frame 16c of the planetary gear 16b of the planetary gear unit 16 is the final stage of the planetary gear unit 2.
It is integrally connected to the sun gear 20 of. Final stage planetary gear device (hereinafter simply referred to as planetary gear device) 2
The support frame 22 of the planetary gear 26 supports the internal gears 15d, 16 of the first stage and second stage planetary gear units 15, 16.
It is integrally connected to d.

An outer socket 7 is connected to an internal gear 21 of a planetary gear device 2.

The support frame 22 of the planetary gear device 2 has each planetary shaft 23
The distal end portion 24 of the support frame 22 is made to protrude to the outside of the support frame 22, and a short cylindrical portion 25 is provided protruding from the outer periphery of the frame 22.

The base end of the holder 3, into which the inner socket 6 is slidably fitted, is rotatably fitted into the cylindrical portion 25. At the base end of the holder 3 are provided shafts 2 corresponding to each planetary shaft 23 of the support frame 22, as shown in FIG.
A notch 33 is formed with a depth approximately equal to the length of the protrusion 3 and a width larger in the circumferential direction than the diameter of the planetary shaft 23, and the tip 24 of the planetary shaft 23 is loosely fitted into the notch 33.

Therefore, the holder 3 can freely rotate relative to the support frame 22 by the space 31 created between the notch 33 and the planetary shaft 23.

The outer circumference of the inner socket 6 and the holder 3
In order to fit the inner peripheries of the two, protrusions 61 and 34 are provided at equal intervals in the axial direction as shown in Fig. 5, and the mating protrusions can be slid into the grooves 37 and 161 formed between the protrusions. It's fitted. contact surfaces 69 of the protrusions 61 and grooves 161;
The inclination of 162 should be kept within 15 degrees with respect to the straight line passing through the axis.

As shown in FIG. 2, the inner socket 6 is urged in the forward direction by a spring 62, and the inner socket 6
The tip of the nut is exposed into the nut engagement hole 70 at the tip of the outer socket 7.

The front end of the protrusion 34 of the holder 3 is formed with a contact surface 35 that can engage with a spherical stopper 4, which will be described later.

When the drive device 1 operates the motor 12 in a state where an external force is applied to the inner socket 6 to prevent rotation of the inner socket 6, the planetary gear device 2 is activated.
The internal gear 21 and therefore the outer socket 7 rotate at a reduced speed, and if the motor 12 is operated while an external force is applied to the outer socket 7 to prevent the outer socket 7 from rotating, the planetary gear system 2 is supported by the planets. Frame 2
At 2, the inner socket 6 rotates in the opposite direction at a further reduced speed.

Further, when the motor 12 is stopped and the entire tightening machine is rotated while the inner socket 6 is fixed, the planetary gear support frame 22 rotates by the length of the space 31 relative to the holder 3 of the inner socket 6, Therefore, the outer socket 7 is rotated in the opposite direction.

There is a ball 64 on the inner surface of the tip of the inner socket 6.
It is pushed by a spring and protrudes so that it can appear and retract.

After the ball 64 breaks the bolt chip 91 in the inner socket 6, even if the tightening machine is removed from the bolt 9, the chip 91 remains in the inner socket 6, thereby preventing the chip from falling unexpectedly.

A bolt chip incomplete fitting prevention device 8 is provided between the inner socket 6 and the holder 3.

The device 8 is connected to a hole 8 in the side wall of the inner socket 6.
0, and a chip detection member 81 that is slidably disposed in the inner hole 66 of the inner socket 6 and detects the entry of a chip 91 and operates the stopper 4. .

A hole 80 into which the stopper 4 is fitted is opened through the side wall of the inner socket 6 facing the contact surface 35 of the holder 3 at the forward end of the inner socket, and the stopper 4 is inserted into the hole 80. It's stuck in the middle of the day.

A stop ring 67 is provided at the boundary between the inner hole 66 of the inner socket 6 and the tip engaging hole 60 for regulating the forward end of the tip detecting member 81.

The tip detection member 81 has a stop ring 6 at its tip.
A protruding part 83 is slidably penetrated through the tip engaging hole 60 and projects into the tip engaging hole 60, and a small diameter shaft 81a and a large diameter shaft 81b are coaxially integrated to the rear of the protruding part 83. is forming.

A conical surface 85 is formed at the boundary between the small diameter shaft 81a and the large diameter shaft 81b.

The tip detection member 81 is biased forward by a spring 87 and reaches the forward end, that is, the stop ring 67.
When the protruding portion 83 comes into contact with the tip engaging hole 60, the stopper 4 passes from the small diameter shaft 81a through the conical surface 85 to the large diameter shaft 81b, that is, the lower portion 86.
from the inner socket 6 to the high part 86a.
Extrudes from the outer peripheral surface of the holder 3 and contacts the contact surface 3 of the inner surface of the holder
5.

Note that the conical surface 85 exists to smoothly move the stopper 4 from the low portion 86 to the high portion 86a of the chip detection member 81, but if the difference in height between the low portion 86 and the high portion 86a is small, the conical surface 85
The same operation as above is possible even if is omitted.

A protruding pin 5 is provided in the chip detecting member 81 so as to be movable forward and backward, and is linked to the ejecting mechanism 51.

The ejecting mechanism 51 includes a spring 52 that urges the ejecting pin 5 forward, and is provided protruding from the rear end of the ejecting pin 5, and slides the sun gears 20, 16a, 15a of the planetary gear reduction devices 15, 16, 2. A push rod 53 that is able to pass through and form a locking groove 54 at the penetrating end, and a latch 56 that is connected to a trigger 55 attached to the handle 10 of the tightening machine and that penetrates into the transition path of the push rod 53. Consists of. When the ejecting pin 5 and therefore the thrust rod 53 are compressed and moved back, the latch 56 engages with the locking groove 54 on the rod 53, and when the trigger 55 is pulled, the latch 56 and the locking groove 54 are disengaged. The spring force moves the push rod 53 and therefore the ejector pin 5 forward.

Next, the bolt tightening tool of the present invention having the above configuration will be explained in three states: [before fitting], [normal fitting], and [misaligned fitting].

[Before mating]

As shown in FIG. 1, the inner socket 6 is connected to the spring 6.
2, the tip is exposed to the nut engagement hole 70 of the outer socket 7.

The chip detecting member 81 is biased by a spring 87 to cause the protruding portion 83 at the tip to emerge into the chip fitting hole 60 of the inner socket 6, and the protruding pin 5 is biased by the spring 52 to cause the tip to be exposed to the tip detecting member 81. It is made to appear from.

The large diameter shaft 81b on the outer periphery of the chip detection member 81, that is, the high portion 86a pushes the stopper 4 outward,
The stopper 4 is engaged with a contact surface 35 of the holder 3.

In this state, the inner socket 6 is prevented from retreating because the stopper 4 is locked to the holder 3.

[When mated normally]

When tightening bolts and nuts, a bolt tip 91 is inserted into the engagement hole 60 of the inner socket 6 as shown in FIG.

The protruding pin 5 in the socket 6 and the chip detecting member 81 release the springs 52 and 8 in response to the insertion of the chip 91.
Compress 7 and retreat. When the bolt tip 91 is completely fitted into the engagement hole 60 and the tip detection member 81 is retreated, the high portion 86a on the tip detection member 81 releases the stopper 4, so that the stopper 4 is completely inserted into the hole 80 of the inner socket 6. The inner socket 6 is retracted into the holder 3 into which the chip 91 is fitted, and the engagement hole 70 of the outer socket is fitted into the nut 92 on the bolt 9. .

[When mating with misalignment]

If the nut engaging hole 70 and the nut 92 are out of phase as shown by the chain line in FIG. 4, the nut 92 will not fit into the water socket 7. Even if the motor 12 is operated in this state, the outer socket 7
just spins around in vain.

When the tightening machine is held in hand and pivoted in either the forward or reverse direction, the inner socket 6 is engaged with the bolt 9 and is in a fixed state, so the planetary gear support frame 22 is , each notch 3 in the holder 3
The tip portion 24 of the planetary shaft 23 rotates by an amount of margin relative to the space 31 of 3.

At this time, the planetary gear 26 on the planetary shaft 23 reverses the engaged internal gear 21 and therefore the outer socket 7 by the amount of rotation of the tightening machine, so that the socket engagement can be performed without having to grasp and adjust the outer socket 7 by hand. The matching hole 70 and the nut 92 can be fitted by matching their phases.

When the inner socket 6 is fully fitted into the bolt tip 91 and the outer socket 7 is fully fitted into the nut 92, the locking groove 54 at the rear of the push rod 53 will lock into the latch 56.
engage with.

Next, the tightening operation of the bolt tightening machine will be explained.

[Screw tightening]

By operating the drive device 1, since the inner socket 6 into which the bolt tip 91 is fitted is temporarily stopped, the outer socket 7 rotates at a reduced speed to tighten the nut 92. Since the tightening reaction force is received by the bolt tip 91 via the inner socket 6, the nut 92 can be sufficiently tightened.

As the tightening of the nut progresses, the threaded shaft 94 of the bolt 9 comes out from the nut surface, and the movement of this threaded shaft 94 is absorbed by the inner socket 6 moving back inside the holder 3 against the spring 62. I can do it.

When the inner socket 6 and the holder 3 are engaged, the respective protrusions 61 and 34 fit into the mating grooves 37 and 161, and the grooves and the protrusions come into surface contact. This is because the inner socket 6 moves in the axial direction, compared to the case of the conventional example shown in FIG. Since the frictional resistance at the time is much smaller, the inner socket 6 can move back inside the holder 3 smoothly, and no large load is applied to the drive device 1. Therefore, the drive device 1 can be small.

Also, as in the conventional case, the corner 68 of the inner socket 6
Since no force is applied to press the inner surface of the holder 3 in the radial direction, the wall thickness of the holder 3 can be made thinner.

By reducing the size of the drive device 1 and reducing the thickness of the holder 3, the tightening machine can be made smaller and lighter.

It is desirable that the protrusion 61 of the inner socket 6 and the contact surface 69 of the holder 3 be on a straight line passing through the axis, but if the angle is within 15 degrees from the straight line, the inner socket 6 will slide smoothly. It was confirmed through experiments that this is the case.

[Chip shearing]

When the nut is completely tightened, the nut 92 does not rotate and therefore the outer socket 7 engaged with the nut 92 is in a fixed state. When the outer socket 7 is fixed, a reaction force is generated in the inner socket 6, which is a force that turns the tip 91 fitted in the engagement hole 60 of the inner socket 6 in the opposite direction to the screwing direction of the nut 92. acts.

At the limit of tightening, the circumferential groove 95 of the bolt tip 91
If the stress concentrated on the bolt exceeds the allowable range, the bolt tip 91 is sheared at the circumferential groove 95, and the bolt 9 and nut 92 are tightened to a specified torque.

After tightening, the sheared bolt tip 91 remains in the inner socket 6 and rotates idly, but when the tightener is removed from the nut, the force of the spring 62 pushes the tip of the inner socket 6 out of the way. It is made to protrude into the nut engagement hole 70 of the socket 7.

Since the chip detection member 81 of the inner socket 6 is urged forward by the spring 87, it moves forward following the movement of the inner socket 6.

[Chip discharge]

When the trigger 55 is pulled and the push rod 53 is moved forward by the force of the spring 52, the protruding pin 5 moves forward within the chip detecting member 81 and comes out into the engagement hole 60, striking and ejecting the previously sheared chip 91. At this time,
The chip detecting member 81 also advances further, and the large diameter shaft 81b, that is, the high portion 86a on the circumference of the chip detecting member 81, again corresponds to the hole 80 and causes a part of the stopper 4 to protrude outside the inner socket 6. It is engaged with the abutting surface 35 of the holder 3, and prevents the inner socket 6 from retreating in the same manner as described above.

9 and 10 show other embodiments of the present invention in which the holder 3 is made shorter and the abutment surface 35 for the stopper 4 is formed on the inner surface of the outer socket 7.

In the case of FIG. 9, two steel balls 41 and 42 are rotatably fitted into a hole 80 in the side wall of the inner socket 6, the outer steel ball 42 serves as a stopper 4, and the inner surface of the outer socket 7 is fitted with a corresponding one. A circumferential groove-like contact surface 35 is formed with which the stopper 4 can engage. Similarly to the above, when the chip detecting member 81 is biased by the spring 87 and waiting at the forward position, the inner steel ball 41 rides on the major longitudinal axis 81b, that is, the high part 86a of the chip detecting member 81, and the outer steel ball 42 engages with the contact surface 35 and prevents the inner socket 6 from retreating. When the chip detection member 81 is pushed by the bolt chip 91 and retreats against the spring 62, the inner steel ball 41 slides over the conical surface 85 of the chip detection member 81 and the small diameter shaft 81a.
That is, the outer steel ball 4 can be moved to the resistance part 86, and therefore the outer steel ball 4
2 escapes from the contact surface 35 and allows the inner socket 6 to retreat.

In the embodiment shown in FIG. 10, a stopper 4 having a total length slightly longer than the wall thickness of the side wall and rounded at both ends is slidably fitted into a hole 80 in the side wall of the inner socket 6, and is attached to the outer periphery of a chip detecting member 81. The outer socket 7 has a circumferential groove 88 on which the stopper 4 engages and disengages, and a contact surface 35 on the inner surface of the outer socket 7 where the stopper 4 engages and disengages.
form.

When the chip detecting member 81 is biased by the spring 87 and waiting at the forward position, the chip detecting member 81
The stopper 4 is located on the outside against the large diameter shaft 81b, that is, the high portion 86a of the outer socket 7.
The inner socket 6 is engaged with the abutting surface 35 to prevent the inner socket 6 from retreating.

When the chip detection member 81 is pushed by the bolt chip 91 and retreats against the spring 62, the chip detection member 8
The stopper 4 becomes able to engage in the circumferential groove 88, that is, the lower portion 86 of the inner socket 6, and accordingly, the stopper 4 moves inward to disengage from the contact surface 35 and allow the inner socket 6 to retreat.

The present invention is as described above, and the stopper 4 that restricts the protrusion and retraction of the inner socket 6 connects the bolt tip 9 to the tip engagement hole 60 of the inner socket 6.
1 is completely fitted and the tip detecting member 81 is moved back. Therefore, the engagement hole 70 of the outer socket 7 cannot be fitted into the nut 92, so the connection between the inner socket and the bolt tip cannot be made as in the conventional case. There is no risk of starting the tightening operation with incomplete mating.
Also, the tightening work can be completed completely.

Further, in the present invention, the inner socket 6 is unlocked by the chip detection member 81, and the protruding pin 5
Therefore, even if the protruding length of the ejecting pin 5 is extended to the full opening surface of the tip engaging hole 60 of the inner socket 6, the ejecting pin 5 will completely retreat from the engaging hole 60. It is possible to maintain the locking of the inner socket 6 until the end, and the length of the tightening machine can be designed to be short. Furthermore, the disadvantage of a type of tightening machine in which the ejecting pin also serves as a locking means for the inner socket, which was previously proposed by the present application, is that the ejecting pin hits the stopper during ejecting operation, weakening the ejecting force, etc., has been solved. , has many excellent effects.

It should be noted that the present invention is not limited to the above-mentioned configuration, and it goes without saying that various modifications can be made within the technical scope of the claims.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the tightening machine of the present invention, Fig. 2 is a sectional view of the main part of the tightening machine engaged with bolts and nuts,
Figure 3 is a sectional view taken along the line of Figure 2, Figure 4 is a sectional view taken along the line of Figure 1, Figure 5 is a sectional view taken along the line of Figure 2, and Figure 6 is a sectional view of the torque control bolt. A front view, FIG. 7 is a sectional view of main parts of a conventional tightening machine, FIG. 8 is a sectional view taken along the line of FIG. 7, and FIGS. 9 and 10 are sectional views of other embodiments of the present invention. Figure 11 is a sectional view of the main parts of a tightening machine previously proposed by the present applicant, and Figure 12 is a tightening machine designed to release the lock of the inner socket at the ideal timing. It is a sectional view of the main part. 3... Holder, 35... Contact surface, 4... Stopper, 5... Projection pin, 6... Inner socket, 7... Outer socket, 81... Chip detection member.

Claims (1)

[Scope of Claims] 1. The cylindrical holder 3 is fitted into the outer socket 7 having a nut engagement hole 70 at its tip so that it can rotate freely regardless of the rotation of the outer socket 7. Drive devices 1 that apply rotational forces in mutually opposite directions are connected, and the holder 3
An inner socket 6 is provided therein so as to be slidable in the axial direction and rotatable together with the holder 3, and a tip engaging hole is provided at the tip of the inner socket 6 to engage with a shearing tip 91 of the bolt. In the bolt tightening machine in which the protruding pin 5 is slidably disposed in the inner socket 6, the inner socket 6 has a protruding portion 86 and a protruding portion 86 arranged in the axial direction. A detecting member 81 that slides independently of the pin 5 is provided so as to be able to protrude and retract into the tip engaging hole 60, and the detecting member 81 is urged by a spring in the direction of protruding into the tip engaging hole 60. , the stopper 4 is movably disposed in the radial direction in a through hole 80 formed in the side wall of the inner socket 6 perpendicular to the transition path of the detection member 81, and when the detection member 81 is in the forward position, the stopper 4 moves toward the detection member. 81 high part 8
6a and engages with the contact surface 35 formed on the outside of the inner socket 6.
When the detection member 81 is in the retreat position, the stopper 4 is lowered to a lower part 86 of the detection member 81, and the stopper 4 can be retracted from the contact surface 35. 2. The bolt tightening machine according to claim 1, wherein the detection member 81 is a cylindrical body having a small diameter shaft 81a on the front side and a large diameter shaft 81b on the rear side. 3. The bolt tightening machine according to claim 1 or 2, wherein the detection member 81 is a cylindrical body with a groove 88 provided around the center of the large diameter shaft 81b. 4. The bolt tightening machine according to any one of claims 1 to 3, wherein the protruding pin 5 is slidably fitted into a hole 83 formed through the detection member 81. 5. According to any one of claims 1 to 4, the tip of the holder is located in front of the stopper at the forward end of the detection member 81, and the contact surface is formed on the inner surface of the holder. Bolt tightening machine as described. 6. Any one of claims 1 to 4, wherein the tip of the holder is located behind the stopper at the forward end of the detection member 81, and the contact surface is formed in the outer socket. Bolt tightening machine described in .