JPH0335464Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention is an air nutter (functionally the same as an air riveter) used for, for example, fixing two panels together using a nut member. This invention relates to the improvement of air nutters, and in particular to improvements in the operability of air nutters, which are utilized in the field of manufacturing technology industry for this type of tools.

(Prior Art) A nut member having a female thread formed on the inner periphery of a sleeve having a flange is inserted into, for example, a mounting hole in two joined panels, and a screw mandrel of an air nut is inserted into the nut member. By screwing together the screw mandrel and moving the screw mandrel backward toward the inside of the main body of the air nutter while pressing the flange of the member against the side surface of the panel, the sleeve portion of the nut member is deformed to bulge outward. The overall structure of an electric nutter that clamps and fixes two panels between the deformed sleeve portion and the flange of the sleeve is well known (eg, Japanese Patent Publication No. 4674/1983).

(Problems to be solved by the invention) By the way, the screw mandrel for deforming the nut member described above is first rotated in the normal direction in order to screw the nut member onto the screw mandrel, and then the screw mandrel is rotated in the normal direction to screw the nut member onto the screw mandrel. In order to deform the nut, it is subjected to a tensile action in a non-rotating state, and then it is rotated in the opposite direction to separate it from the nut member fixed to the panel, etc., but each of these actions is the work of fixing the nut member to the panel, etc. It is necessary that these functions work together automatically and continuously, and therefore, the power transmission and switching operations for performing each of the above operations must be performed smoothly, and each operation must be performed by the nut member. It is extremely important to ensure that each step of the above-mentioned fixing work is carried out reliably.

The present invention aims to improve the operability and workability of an air nutter using compressed air as a driving source by smoothly and reliably carrying out each of the automatic and continuous actions of the air nutter as described above. There are some that aim to provide an air nut that can be used.

(Means for solving the problem) The air nutter (or air riveter) according to the present invention moves an air piston fitted in an air cylinder forward to pressurize oil stored in the machine body. By moving the oil piston backward and moving the screw mandrel attached to the tip of the oil piston backward toward the inside of the machine body, a deforming force is applied to the sleeve portion of the nut member screwed onto the screw mandrel. In the air nutter configured as above, an air motor rotated by compressed air is disposed inside the body of the air nutter, and an air motor for driving the rotation of the air motor is provided between the air motor and the compressed air supply port in the body of the machine. an air introduction passage is provided, and an air motor forward/reverse rotation direction switching operation mechanism for switching the rotation direction of the air motor is provided, and between the air motor and the screw mandrel,
Several planetary gears mesh with a transmission gear formed at the end of the rotating shaft of the air motor, a clutch member fitted with the gears, and a lever for rotating the clutch member in a predetermined circumferential direction. a turning spring, and a regulating plate of a clutch member, which is provided with a through hole that communicates with the through hole provided in the clutch member when necessary;
A square shaft, etc. for transmitting rotational force with a square cross section, which is fitted into a through hole formed in the axial center of the oil piston so that it can freely rotate in the circumferential direction, and whose front end is engaged with a screw mandrel. A power transmission mechanism configured to transmit both forward and reverse rotational driving force of the air motor to the screw mandrel is provided, and the compressed air supply port and the air cylinder which is the forward movement side of the air piston are connected to each other. An air introduction passage for forward movement of the air piston is formed between the air introduction hole, and a spool for opening/closing the air introduction passage is formed in the communication hole formed in communication with the air introduction passage for forward movement of the air piston. The spool in the hole is slidably fitted between the communication hole for fitting the spool and the compressed air supply port, and the spool in the hole is connected to the air introduction passage for forward movement of the air piston by compressed air. An air introduction part is formed for controlling the spool to be moved forward in the closing direction, and an air introduction part is provided between the air introduction part and a compressed air outlet formed in the machine body near the power transmission mechanism part. A passage for discharging the compressed air introduced into the exhaust passage is disposed, and a clutch member of the power transmission mechanism that also serves as an opening/closing member for the passage is disposed in the passage of the discharge passage. is arranged so that communication is opened when the clutch member is rotated to a predetermined rotation angle position by a predetermined rotational torque, and a forward/reverse rotation direction switching operation mechanism for the air motor is provided. consists of an air passage switching spool disposed inside the machine body, a returning spring disposed on the rear side of the spool, and a spool push member that moves with the oil piston shaft. The turning spring moves the spool forward to connect the air passage of the spool to the forward rotation passage of the air motor, and when the oil piston retreats, the push member moves the spool backward to connect the air passage of the spool to the forward rotation side passage of the air motor. It is characterized in that it is configured to communicate with a side passage.

(Function) Therefore, according to the configuration of the present invention, a series of operations such as forward rotation, rotation stop and backward movement, further reverse rotation and forward movement on the screw mandrel can be smoothly and continuously performed. You can do it by doing this.

Therefore, it is easy to screw the nut member onto the screw mandrel during forward rotation of the screw mandrel, and then, when the flange of the screwed nut member is pressed against the side surface of the mounting hole, the nut can be screwed onto the screw mandrel. The members are fixed and the screw mandrel moves forward relatively, and the flange and the machine body side are joined and fixed, and the rotation of the screw mandrel is stopped. By this rotation stop, the clutch member of the power transmission mechanism is rotated to a predetermined rotation angle position, and at this time, the communication hole formed in the clutch member and the air introduction passage for forward movement of the air piston are opened and closed. Since the air discharge passage consisting of the control air introduction part for the spool and the air discharge port of the machine body is opened for communication and the control for the spool is released, the spool opens the air introduction passage for forward movement of the air piston. Introduce compressed air into the air cylinder.

Compressed air introduced into the air cylinder moves the air piston forward to pressurize the oil inside the machine body, and this oil pressure causes the oil piston and the screw mandrel attached to it to move backward at the same time to tighten the nut. Performs a deforming action on the member. At this time, the push member of the air passage switching spool of the rotational direction switching mechanism of the air motor is moved by the oil piston to push and retreat the spool, and the rotational direction switching mechanism of the air motor is operated to switch the air motor. When reversely rotated, the clutch member returns to its original position and closes the air discharge passage. Therefore, the spool of the air introduction passage for forward movement of the air piston is moved back to its original position by the compressed air and closes the passage, so that the force for the forward movement of the air piston is released. Note that the air piston moves back as the oil piston moves forward due to the returning spring, but the air motor can be rotated in the opposite direction during a predetermined period of time, so the screw mandrel is fixed in the mounting hole. It can be removed from the nut member.

By releasing the trigger after each of these actions is completed, the passage is closed, and the switching spool in the rotational direction switching operation mechanism is moved back to its original position by the returning spring, so that the spool is connected to the air motor. The air introduction passage for rotational driving can be switched to a state in which the air motor is rotated in the forward direction.

(Example) Next, the present invention will be explained based on embodiment figures.

1 and 3 show the whole air nutter according to the present invention, and the air nutter consists of a machine body frame 2 containing oil 1, an air cylinder 3 disposed at the lower part of the frame 2, and an air nutter that contains oil 1. An air piston 4 for pressurizing the oil 1 fitted in the cylinder 3, an oil cylinder 5 formed in an upper position of the frame 2 in communication with the oil storage portion of the frame, and an oil cylinder 5 fitted in the oil cylinder 5. oil piston 6,
A returning spring _S1 for moving the oil piston 6 forward, a pivot member 8 for a screw mandrel, which will be described later, fixed to the front end of the oil piston 6, and a through hole 7 formed in the axial center of the oil piston 6. A square shaft 9 for transmitting rotational force having a square cross section is fitted so as to freely rotate in the circumferential direction, and the front end of the square shaft 9 is engaged to ensure integral rotation in the circumferential direction. Screw mandrel 10 and
Connector 1 attached to the front end of machine frame 2
1 and a nose piece 12 attached to the front end of the connector 11.

Further, an air motor 13 for rotationally driving the square shaft 9 is disposed at a rear position of the square shaft 9, and a supply air control unit formed in the air motor 13 and the machine body (air cylinder 3 in the example). Between the compressed air supply port 14 of the mechanism AC,
An air introduction passage 17 for driving the rotation of the air motor is provided via an air passage 15 provided with a valve seat and one air branch passage 16.

The air introduction passage 17 is connected to the supply port 14 (second
(see figure), a passage 17 ₂ , and _an air hose 17 ₃ . V has an on-off valve mechanism between the air passage 17 and the air motor 13, and a trigger 18 provided on the front side of the frame 2.
, a connecting rod 19 pivotally connected to the trigger, a base end pivotally connected to the connecting rod, and an air cylinder 3 having an intermediate portion.
a lever 20 pivotally mounted on the upper part of the lever; a pusher 21 slidably inserted into an insertion hole inside the supply air control mechanism AC with its upper end pressed against the lower surface of the tip of the lever by a spring _S2 ; It is composed of a ball valve 22 that is pressed against a valve seat portion in the air passage 15 by a spring S ₃ . Under normal conditions, the ball valve 22 is biased by the spring S ₃ to connect the compressed air supply port 14 and the air introduction passage 17 . However, when the trigger 18 is pulled forward, the pusher 21 is moved downward against the elasticity of the spring _S2 via the connecting rod 19 and the lever 20, and the ball valve 22 is closed at its lower end. is pushed down against the elasticity of the spring _S3 to connect the compressed air supply port 14 and the air introduction passage 17.

Further, an air introduction passage 24 for forward movement of the air piston is provided between the air supply port 14 and the air introduction hole 23 (see FIG. 4) of the air cylinder 3 on the forward movement side of the air piston 4. has been done. The air introduction passage 24 is connected to the supply port 14.
are communicated with each other via the passage 15 and the other air branch passage 25. Further, a spool 27 for opening and closing the air introduction passage 24 is slidably fitted into a communication hole 26 formed in communication with the air introduction passage 24,
6 and the supply port 14 is a control air introduction portion 28 of the spool 27 that moves the spool 27 forward in the direction of closing the air introduction passage 24 with air through an air circulation hole 29. It is formed. Air is introduced into the air introduction section 28 by passing the air supplied from the air supply hole 14 through an air circulation hole 29 formed in the spool 27, and the air introduced into the introduction section 28 is introduced into the air introduction section 28. The spool 27 is pushed toward the introduction hole 23 of the cylinder by the air pressure to close the passage 24.

Further, the spool 27 is configured to be pushed in the direction of unblocking the passage 24 by the spool 27 by using the pressure of the air supplied from the other air branch passage 25. . That is, since the pushing force corresponds to the area of the large-diameter upper surface 27 ₁ and large-diameter lower surface 27 ₂ of the spool 27, when air is introduced into the introduction section 28, the large-diameter The spool 27 does not act effectively because it receives a larger pushing force on the large-diameter upper surface 27 ₁ than on the end surface of the lower surface 27 ₂ , and therefore, the spool 27 is not pushed in the direction of closing the passage 24 . It will receive power.

In FIG. 3, reference numeral 30 denotes an air introduction section 28 disposed between the control air introduction section 28 of the opening/closing spool 27 described above and an air outlet formed in the machine body near the power transmission mechanism described later. a passage 30 ₁ which is an air discharge passage for discharging the air inside and communicates with the air introduction part 28;
It consists of an air hose 30 ₂ and an air hose 30 ₃ , and 31 ₁ and 31 ₂ indicate a discharge passage for the air inside the air cylinder 3 to the outside of the machine and a discharge hole.

Further, in the path of the air introduction passage 17 for driving the air motor rotation described above, an air flow path switching spool of a forward/reverse rotation switching operation mechanism 32 for switching the rotation direction of the air motor 13, which will be described later, is disposed. There is.

This mechanism 32 consists of an adapter nut 33 screwed onto the tip side of the oil piston 6, a guide plate 34 fitted into the oil piston 6 at the rear of the adapter nut so as to be movable back and forth, and a protruding portion of the guide plate screwed into the adapter nut 33. A push rod 36 is inserted into the machine body so as to be movable back and forth with the tip end of the adjustment screw 35 in contact with the tip end of the adjustment screw, and a push rod 36 is inserted into the machine body so as to be movable back and forth. A push member P consisting of a split push rod 36' inserted through the main body so as to be movable back and forth, and a spool 37 for switching the air flow path disposed in the path of the air introduction passage 17 described above.
The rear end surface of the divided push rod 36' is arranged so as to be able to come into contact with the distal end surface of the spool 37. In addition, this push member P is normally pushed to the position shown in FIG. 5 by a returning spring _S4 .

Therefore, the air flow path switching spool 37
is fitted into a bushing 38 communicating with the air introduction passage, as shown in FIGS. 6a and 6b,
In the normal state, the air motor 13 is rotated in the forward direction by being pushed by the returning spring _S4 , but the switching operation of the air flow path by the spool 37 is performed as follows.

That is, in the normal state, a in FIGS. 5 and 6
As shown in , the switching spool 37 is connected to the spring S ₅
In this state, the air supplied through the flow path 17 flows through the air introduction hole 39 formed in the bushing 38.
The air flows through an air outlet 40 formed in the accommodation space of the air motor 13 and communicates with an air outlet (not shown) on the forward rotation side of the air motor 13, and is ejected into the accommodation space. This becomes a driving force that rotates the air motor 13 in the forward direction. Furthermore, when the oil piston 6 retreats due to oil pressure, the adapter nut 33 of the push member P described above also retreats, causing the guide plate 34 to spring.
The adjusting screw 35, push rod 36 and split push rod 36' are moved back against the elasticity of _S5 , and the switching spool 37 is pushed rearward by the rear end face of the split push rod. At this time, the front end surface of the switching spool 37 connects to the air introduction hole 41 formed in the front part of the bushing 38.
When the bushing 38 is moved backward, air is introduced into the bushing 38 through the hole 41, and the switching spool 37 is reliably moved rearward by the air pressure. Furthermore, when the switching spool 37 is in the rearward movement state, the spool 37 communicates the air delivery hole 40 with the exhaust hole 43, and the air introduction hole 39 is formed in the air motor accommodation space. The supplied air is connected to an air outlet hole 42 that communicates with an air outlet hole (not shown) on the reverse rotation side, and therefore, at this time, the supplied air becomes a driving force for rotating the air motor 13 in the reverse direction.

Further, between the air motor 13 and the screw mandrel 10, the forward and reverse rotational driving force of the air motor 13 is applied to the screw mandrel 10.
A power transmission mechanism 44 for transmitting power to the side is provided.

This mechanism 44 includes several planetary gears 46 that mesh with a transmission gear 45 formed at the end of the rotating shaft of the air motor 13, and the gears 46 at both the front and rear positions of the gears.
6 rotatably supported via a fixing pin 47, a clutch member 50 fitted on the outer periphery of the gear 46, and a clutch member 50 that is rotated in a predetermined circumferential direction. The clutch member 50 is provided with a return spring S ₆ for rotating the clutch member, a storage chamber 51 for the spring, and an elongated hole 53 into which a knock pin 52 is inserted, and a through hole provided in the clutch member 50. 54 and a regulating plate 56 of the clutch member equipped with a through hole 55 that communicates with the clutch member when necessary.
The clutch member 50 is covered in the arrangement shown in FIGS. 7 and 8.

Both the above-mentioned pivot members 48, 49 are provided so as to be able to rotate simultaneously with the rotation of the gear 46, and the clutch member 50 is elastically hooked to the regulating plate ₅₆ via a spring S6. Therefore,
In a normal state, the planetary gear 46 rotates on its axis and rotates around the inner gear 57 formed on the inner circumferential surface of the clutch member 50.
They will be guided by and orbit at the same time. Also,
A square hole 58 that engages with the rear end of the square shaft 9 is formed in the axial center of the front pivot member 48 .

Therefore, the forward and reverse rotational force of the air motor 13 is
It is transmitted to the screw mandrel 10 in front via the transmission gear 45, planetary gear 46, pin 47, pivot member 48, and square shaft 9.

Further, the air hose 30 ₃ of the air discharge passage 30 is communicated with the through hole 55 of the regulating plate 56 of the clutch member through the air discharge hole 59, and the through hole 55 is connected to the through hole 55 when the clutch member 50 is switched. It is configured to communicate with a communication hole 54 provided in the clutch member, and therefore, during the switching operation, a passage 61 formed between a frame cap 60 provided inside the machine body and the inner wall of the machine body is connected. The air discharge port 62 provided in the machine body is configured to communicate with the air hose ₃₀₃ through the air outlet 62.

Next, a series of operations of the air nutter will be explained based on the above embodiment.

First, when the trigger 18 is pulled to open the ball valve 22 and the air motor 13 is rotated forward, the screw mandrel 10 will also rotate forward, so in this state, screw the nut member onto the screw mandrel 10, Next, in this state, although not shown, the nut member is inserted into the mounting hole formed in the two panels, and the flange of the nut member is pressed against the side surface of the mounting hole to rotate the nut member. When you stop the screw mandrel 10 (machine main side)
will make relative progress. When the flange of the nut member and the nose piece 12 are joined and fixed by this forward movement, the screw mandrel 10 becomes locked and stops rotating. However, since the air motor 13 continues to rotate in the normal direction, its transmission gear 45 causes the planetary gear 46 to rotate, and therefore the clutch member 50 resists the elasticity of the spring S ₆ to a predetermined rotation angle position. It will be rotated forward until. This predetermined rotation angle position is the 8th rotation angle position.
This refers to the position where the knock pin 52 shown in the figure restricts the rotation of the clutch member 50, and when the clutch member 50 is rotated to that position, the member 52
The communication hole 54 formed at 0 communicates with the communication hole 55, and allows the air hose ₃₀₃ of the air discharge passage 30 and the discharge port 62 to communicate with each other.

Communication between the air hose 30 ₃ and the discharge port 62 is as follows:
The air introduced into the air introduction section 28 through the air discharge passage 30 is discharged to the outside of the machine. Therefore, at this time, the air pressure in the introduction section 28 decreases and the control over the spool 27 is released, so that the spool 27 is adjusted in diameter by the air pressure supplied from the supply port 14 and the branch passage 25. The end surface of the large lower surface ₂₇₂ receives pressure and pushes the spool 27 upward to communicate the air branch passage 25 with the air introduction passage 24'. Therefore, air is supplied into the air cylinder 3 through the passage 24' and the air introduction hole 23 of the cylinder, so that the air piston 4 is moved forward and its piston rod fits into the oil storage part, causing the air to flow inside the oil storage part. Pressurize oil 1. This oil 1
When the oil piston 6 is pressurized, the oil piston 6 is moved back against the elasticity of the returning spring _S1 , but the pivot member 8 provided at the front end of the oil piston 6 moves the screw mandrel 10 back at the same time. Therefore, the nut member can be deformed by expanding the sleeve portion of the nut member outward and fixing the panel between the deformed sleeve portion and the flange. This deformation action of the nut member is performed while the oil piston 6 is moved to a predetermined rear position by oil pressure.

Further, as described above, when the oil piston 6 is retracted and the nut member is deformed, the air flow path switching spool 37 is retracted by the pusher member P to reversely rotate the air motor 13. When the clutch member 50 is reversely rotated, the clutch member 50 is rotated back to its original position due to the elasticity of the returning spring _S6 and the reverse rotation of the planetary gear 46, thereby closing the air discharge passage 30 again. Therefore, air is introduced into the air introducing portion 28 again and pushes the spool 27 downward,
Since the communication relationship between the air branch passage 25 and the passage 24' is cut off, the forward movement force on the air piston 4 is released, and the pressurizing action of the oil 1 by the piston rod is stopped. For this reason, the oil piston 6 is moved back forward by the elasticity of the returning spring _S1 , but the ball valve 22 is opened and the air formed in the front part of the bushing 38 of the forward/reverse rotation operation mechanism 32 of the air motor is While air is being supplied to the introduction hole 41, the spool 37 is held at its current position by air pressure, so the air motor 13 continues to rotate in the reverse direction. Therefore, the screw mandrel 10 is rotated in the opposite direction and retreats from the nut member fixed to the mounting hole of the panel or the like. Then, when the ball valve 22 is closed,
The switching spool 37 moves back to its original position in front due to the elasticity of the returning spring _S4 , and the push rod member P also moves back to its original position and becomes normal.

Note that the reference numeral 63 in the figure is a handle that is fitted into and fixed to the rear part of the push rod 36 of the push member P described above, and if the nut member is not properly screwed into the screw mandrel 10, By pulling the handle 63 and manually retracting the push member P, the air motor 1 can be
The nut member is removed by rotating 3 in the reverse direction, and 64 is a screw cap detachably attached to the rear end of the housing portion of the air motor 13.
If the air motor 13, square shaft 9, screw mandrel 10, etc. become unable to rotate or malfunction due to unforeseen causes, remove the screw cap 64,
It is useful for manually rotating the rotating shaft of the air motor 13 with a screwdriver or the like to return it to a normal state. Also, reference numeral 65 indicates an air discharge passage in the air cylinder, and reference numeral 66 indicates an air discharge passage of the air motor. Each figure shows a discharge pipe for discharging excess air fed into the casing.

(Effects of the invention) According to the invention, firstly, due to its overall configuration, a series of operations such as forward rotation, rotation stop and backward movement, and further reverse rotation and forward movement of the screw mandrel can be smoothly performed. Since this can be carried out continuously and continuously, the operability and workability of the air nutter using compressed air as a driving source can be significantly improved.

Furthermore, the forward/reverse rotation direction switching operation mechanism of the air motor consists of an air passage switching spool disposed inside the machine body, a returning spring disposed on the rear side of the spool, and a spool that moves with the oil piston shaft. Under normal conditions, the returning spring moves the spool forward to communicate the air passage of the spool with the normal rotation side passage of the air motor, and when the oil piston retreats, the push member moves the spool forward. The air passage of the spool is connected to the reverse passage of the air motor by retracting the spool, and the spool is pushed by a separate hydraulic push spool. Compared to the above, the space for housing the spool can be made smaller, the entire air nutter can be downsized, and there is an advantage that oil leakage does not occur.

Furthermore, if the nut member is not properly screwed into the screw mandrel,
By manually retracting the spool push member, there is operational convenience in that the air motor can be reversely rotated in an emergency to remove the nut member.

[Brief explanation of the drawing]

The figures show an embodiment of the air nutter of the present invention.
The figure is a cross-sectional end view taken along the A-A line in Figure 1, Figure 3 is a left side view of the entire body taken longitudinally along the A-B-C line in Figure 2, and Figure 4 is a cross-sectional view taken along the line A-A in Figure 2. - A partially omitted vertical cross-sectional view along line E-F, Figure 5 is G-H-I in Figure 3.
6 is an explanatory view showing the operating state of the switching spool of the air passage, FIG. 7 is a vertical sectional front view showing the main parts of the power transmission mechanism, and FIG. 8 is a sectional view along the line. 9 is a partially omitted enlarged sectional view taken along line K-L in FIG. 8, and FIGS. 10 a and b are a right side view and partially cutaway front view of the frame cap, respectively. It is a diagram. Explanation of symbols, 2...Machine body frame, 3...Air cylinder, 4...Air piston, 5...
Oil cylinder, 6...Oil piston, 9...
...Square shaft, 10...Screw mandrel, 13...
...Air motor, 14...Air supply port, 17...
...Air introduction passage, 23...Air introduction hole, 2
4, 24'...Air introduction passage, 26...Communication hole section, 27...Suburu, 28...Air introduction section,
30...Discharge passage, 31 ₂ ...Air discharge hole,
32... Forward/reverse rotation switching operation mechanism, 37... Spool, 39... Air introduction hole, 40... Air delivery hole, 41... Air introduction hole, 42... Air delivery hole, 44... Power transmission mechanism, 45...Transmission gear,
46... Planet gear, 50... Clutch member, 5
4, 55...Through hole, 56...Regulation plate, _S6 ...Returning spring, S...Spring, P...
Push parts.

Claims (1)

[Scope of utility model registration request] By moving the air piston fitted in the air cylinder forward and pressurizing the oil contained in the machine body, the oil piston is moved backward, and the screw mandrel attached to the tip of the oil piston is moved backward. In an air nutter configured to apply a deforming force to a sleeve portion of a nut member threaded onto the screw mandrel by moving backward toward the inside of the main body, air rotated by compressed air is provided inside the main body of the air nutter. an air motor main body which includes a motor, an air introduction passage for driving the rotation of the air motor between the air motor and a compressed air supply port in the airframe, and which switches the rotational direction of the air motor; A reverse rotation direction switching operation mechanism is provided, and between the air motor and the screw mandrel, there are several planetary gears meshed with a transmission gear formed at the end of the rotation shaft of the air motor, and the gears. A clutch member fitted with a clutch member, a returning spring for rotating the clutch member in a predetermined circumferential direction, and a through hole that communicates with the through hole provided in the clutch member when necessary. A rotation force transmitting plate with a rectangular cross section that is fitted into a through hole formed in the axial center of the oil piston so that it can rotate freely in the circumferential direction, and whose front end is engaged with a screw mandrel. A power transmission mechanism is provided, which transmits the forward and reverse rotational driving force of the air motor to the screw mandrel, and includes a square shaft, etc. An air introduction passage for forward movement of the air piston is formed between the air introduction hole of the air cylinder and the air introduction hole,
Further, a spool for opening and closing the air introduction passage is slidably fitted into the communication hole formed in communication with the air introduction passage for forward movement of the air piston, and the communication hole for fitting the spool and the above-mentioned An air introduction part for controlling the spool is formed between the compressed air supply port and the spool in the hole by compressed air in a direction in which the air introduction passage for forward movement of the air piston is closed. A passage for discharging the compressed air introduced into the air introduction portion is provided between the introduction portion and a compressed air discharge port formed in the machine body near the power transmission mechanism portion, and
A clutch member of the power transmission mechanism that also serves as an opening/closing member for the passage is disposed in the path of the discharge passage, and the clutch member is rotated through a predetermined rotation angle by a predetermined rotational torque. The forward/reverse rotation direction switching operation mechanism of the air motor is configured to be arranged and configured to be opened for communication when rotated to the position, and the air passage switching spool disposed within the machine body and the air passage switching spool disposed within the machine body. It is composed of a returning spring disposed on the rear side of the spool and a spool push member that moves with the oil piston shaft.In normal conditions, the spool is advanced by the returning spring and the air passage of the spool is connected to the air motor. The air nut is connected to the normal rotation side passage of the air motor, and when the oil piston is retracted, the spool is moved back by the push member to make the air passage of the spool communicate with the reverse rotation side passage of the air motor.