JP2016043445A - Driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance an accuracy of an operation timing of an air motor in a screw driver which utilizes compressed-air as a power source.SOLUTION: Fig. 8 shows a state that since a main piston part 25 lowers and an O-ring 25b is located underside an air hole 31a, compressed-air on a slider chamber side flows into a third air passage 10d via the air hole 31a and rotation of an air motor 21 is started, that is, a state immediately after a driving operation is completed and a fastening operation is started. As said above, an operation of the air motor 21 is quickly performed at that time by directly supplying compressed-air in an accumulator 52 to the air motor 21 by use of a pilot valve 100.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a structure of a driving machine for driving a stopper member using compressed air (high pressure air).

  2. Description of the Related Art A driving machine for driving a stopper member (eg, a nail or a screw) that engages with a plate material such as wood, gypsum board, or steel plate using compressed air (high pressure gas) as a power source is known. In the nailing machine, the nail is driven in one direction with a strong driving force. In the screw driving machine, the screw is similarly driven by a distance shorter than the entire length of the screw, and then rotated and tightened. Operation is performed.

  As the compressed air, for example, one generated by a compressor or the like and stored in a tank can be used. For this reason, in such a driving machine, the air plug with which the air hose which supplies compressed air was mounted | worn is provided, and a driving machine is used in the state by which the hose was mounted | worn with the air plug. In a screwdriver, when a driver bit is attached to a piston that is moved by compressed air and a trigger or the like attached to the screwdriver is operated, the piston and driver bit descend, and the lower end of the screw causes the screw to reach a specified length. Just type in (striking action). Thereafter, the screw is rotated by rotating the driver bit, and the tightening operation is performed (tightening operation). The driver bit is rotated by an air motor that operates by supplying compressed air.

  In such a driving machine, the operation of the piston and the air motor is performed by the supplied compressed air, and the supplied compressed air is temporarily stored in a pressure accumulating chamber provided in the driving machine. , To perform the above operation. Here, a plurality of valves for controlling the flow of compressed air are used in order to control the operation of the piston and the air motor inside the driving machine. Since the power source (for example, a power source) other than compressed air is not used in the screwdriver of Patent Document 1, this compressed air is also used in the control of this valve.

  At this time, even if the hardness of the wood or the like to which the screw is fastened and the thickness of the screw are various, it is required to stably perform the driving operation and the tightening operation. In such a screwdriver, first, the compressed air pushes down the piston, and after the driver bit is lowered to a predetermined position by the driving operation, a part of the compressed air that pushed down the piston flows to the air motor side. Rotation operation (tightening operation) is performed. For this reason, the driver bit is configured to automatically rotate when the driver bit is lowered by a predetermined length. The compressed air that has driven the air motor is then exhausted. With such a configuration, a stable screwing operation can be performed.

JP 2005-103727 A

  In the screwing machine described above, the compressed air used for the operation is exhausted after flowing through each part inside the screwing machine from the pressure accumulating chamber, and is discharged to the outside. Here, since the compressed air for lowering the driver bit (piston) is located on the upstream side (the side closer to the pressure accumulating chamber) in this flow, the operation for lowering the driver bit was performed quickly after the operation of the trigger or the like. . However, as the compressed air for driving the air motor, a part of the compressed air for lowering the driver bit (piston) is used. For this reason, the response speed of the control of the air motor performed after the driver bit is lowered to a predetermined position becomes slow, and the pressure of the compressed air used for this control may drop. For this reason, it is difficult to fasten the screw sufficiently fast, and it is difficult to perform an efficient operation.

  Such a problem that the switching timing of the operation of the air motor is delayed exists not only at the start of the operation of the air motor but also at the end of the operation. When the operation end timing of the air motor is delayed, the driver bit continues to rotate more than necessary, and the screw may be tightened deeper than necessary. At this time, since the driver bit cannot be moved below a certain range, the engagement between the lower end of the driver bit and the cross groove at the head of the screw becomes shallow, and the screw cannot be rotated. The cam bit that the driver bit rotates in the state occurred. In this case, problems such as screw breakage, driver bit wear, and abnormal noise occurred. That is, there is a problem that work is not efficient because the operation timing of the air motor is not properly performed.

  That is, in a screwdriver using compressed air as a power source, it is desired to improve the accuracy of the operation timing of the air motor.

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
The driving machine according to the present invention performs a driving operation for driving a stopper member into a member to be fastened along a driving direction and a tightening operation for rotating and tightening the stopper member to compress compressed air stored in a pressure accumulating chamber. A driving machine that is used as a power source, and includes a rotation operation control air passage to which compressed air is supplied after the piston has moved to a predetermined position, an air motor that performs an operation of rotating the stopper member by compressed air, and the rotation A pilot valve connected to the operation control air passage, and performing an operation of supplying the compressed air in the pressure accumulating chamber to the air motor by the compressed air supplied into the rotation operation control air passage.
In the driving machine according to the present invention, the pilot valve slides inside the valve chamber in accordance with the pressure of air in the rotation operation control air passage, and the pilot valve in accordance with the position of the pilot valve in the valve chamber, The on / off control of the supply of compressed air in the pressure accumulating chamber to the air motor is controlled.
In the driving machine according to the present invention, the rotational movement control air passage is connected to the valve chamber via a valve chamber intake port provided on one end side of the valve chamber, and the valve chamber is connected to the other end side. The valve operation control chamber, which is a space between the end surface on the one end side of the pilot valve in the valve chamber and the end surface on the one end side of the valve chamber, communicates with the atmosphere through the provided valve chamber exhaust port. When compressed air is supplied from the rotational motion control air passage, compressed air in the pressure accumulating chamber is supplied to the air motor, and compressed air is not supplied from the rotational motion control air passage to the valve motion control chamber, The pilot valve is moved to the one end side so that compressed air in the pressure accumulating chamber is not supplied to the air motor.
The driving machine according to the present invention is characterized in that an air vent path for releasing a part of the compressed air supplied from the rotation operation control air passage to the atmosphere is provided on the pilot valve side.
The driving machine according to the present invention is characterized in that, in the tightening operation, when the fastener member is tightened by a predetermined depth, compressed air is not supplied to the rotation operation control air passage.
The driving machine according to the present invention is characterized in that the air vent path is connected to the rotational motion control air passage.
The driving machine according to the present invention is characterized in that an air vent path for releasing compressed air introduced into the valve operation control chamber to the atmosphere is connected to the valve operation control chamber.
The driving machine according to the present invention is characterized in that an air vent path for releasing compressed air introduced into the valve operation control chamber to the atmosphere is formed on an end face of the pilot valve on the one end side.
In the driving machine according to the present invention, a cross-sectional area of the air vent path is not more than 0.5 times a cross-sectional area of the valve chamber intake port.
In the driving machine according to the present invention, a cross-sectional area of the air vent path is 0.5 times or less of a cross-sectional area of the valve chamber exhaust port.
In the driving machine according to the present invention, a substantially cylindrical spindle that is rotated by the air motor around a central axis along the driving direction, the stopper member and one end side thereof are in contact with each other, and the stopper member is driven and rotated. A driver bit and the other end side of the driver bit are fixed, movable in the driving direction with respect to the spindle, and disabled to rotate with respect to the spindle around the central axis. And a piston that moves to one end side of the driver bit by introducing compressed air into the spindle, and the rotation operation control air passage has one end of the driver bit that is a predetermined length in the piston. Compressed air introduced into the spindle after moving to the side flows from the inside of the spindle.

  Since the present invention is configured as described above, it is possible to obtain a driving machine having compressed air as a power source and high accuracy of the operation timing of the air motor.

It is sectional drawing which shows the whole structure of the driving machine used as embodiment of this invention. It is sectional drawing which shows the structure inside the housing in the driving machine used as embodiment of this invention. It is sectional drawing which shows the state in which the pilot valve in the driving machine used as embodiment of this invention is closed. It is sectional drawing which shows the state in which the pilot valve in the driving machine used as embodiment of this invention is open. It is sectional drawing which shows the state (the 1) at the time of operation | movement in the driving machine used as embodiment of this invention. It is sectional drawing which shows the state (the 2) at the time of operation | movement in the driving machine used as embodiment of this invention. It is sectional drawing which shows the state (the 3) at the time of operation | movement in the driving machine used as embodiment of this invention. It is sectional drawing which shows the state (the 4) at the time of operation | movement in the driving machine used as embodiment of this invention. It is sectional drawing which shows the state (the 5) at the time of operation | movement in the driving machine used as embodiment of this invention. It is sectional drawing which shows the state (the 6) at the time of operation | movement in the driving machine used as embodiment of this invention. It is sectional drawing which shows the state (the 7) at the time of operation | movement in the driving machine used as embodiment of this invention. It is sectional drawing which shows the state (the 8) at the time of operation | movement in the driving machine used as embodiment of this invention. It is sectional drawing which shows the state with which the 1st modification of a pilot valve and a valve chamber is closed. FIG. 6 is a cross-sectional view showing a state in which a first modification of a pilot valve and a valve chamber is open. It is sectional drawing which shows the state with which the 2nd modification of a pilot valve and a valve chamber is closed. It is sectional drawing which shows the state with the 2nd modification of a pilot valve and a valve chamber open.

  A configuration of a screw driving machine (driving machine) according to an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing the configuration of the screwdriver 1. By this screw driving machine 1, a screw (fastening member) is driven into a plate material or the like (fastened member) placed on the lower side, and in FIG. 1, the screw is driven along the axial direction (drive-in direction). A cross-sectional view is shown. Here, the driving direction is the vertical direction.

  In this screw driving machine 1, a driving force is applied to a screw in a substantially cylindrical housing 10 with the driving direction as a central axis by applying a driving force downward to the screw, and then the screw is rotated. A mechanism for performing the tightening operation is provided. As a power source for this operation, compressed air supplied from the outside is used. Further, the compressed air is used as a source for generating the driving force and the torque for rotating the screw. The compressed air is also used in the operation of a valve or the like for controlling the compressed air.

  In FIG. 1, a handle 50 is fixed to the right side of the housing 10 so as to extend in a direction intersecting the housing 10 (right direction in the drawing: rearward) and gripped by an operator. An air plug 51 for mounting an air hose (not shown) for supplying compressed air from the outside is provided at the rear end (right end in FIG. 1) of the handle 50. The compressed air is stored in the pressure accumulating chamber 52 provided in the handle 50 from the air plug 51 and supplied to the housing 10 side. A pressure reducing valve 53 is provided in the air path between the air plug 51 and the pressure accumulating chamber 52, and when the pressure of the compressed air supplied from the air hose is higher than the pressure appropriate for the operation of the screwdriver 1, the pressure accumulating chamber. The pressure of the compressed air in 52 can be adjusted, and the pressure of the compressed air in the pressure accumulating chamber 52 is constantly adjusted to a range suitable for operation. Further, it is necessary to discharge the compressed air after being used for the operation in the housing 10 to the outside. The exhaust passage 54 serving as a passage for this purpose is also separated from the pressure accumulating chamber 52 in the handle 50 and on the upper side. Is provided. The compressed air that has passed through the exhaust passage 54 is discharged to the outside from an exhaust port 55 provided on the upper side of the air plug 51 at the end of the handle 50. At this time, drain (condensed water or liquid component such as oil) is mixed in the compressed air, but the compressed air (gas) is discharged by the drain separator 57 attached to the exhaust pipe 56 provided with the exhaust passage 54. And drain (liquid). The separated compressed air reaches the exhaust port 55 from the muffler 58 via the air passage 58A. The separated drain is stored in the drain tank 59 through the flow path 59A. At this time, the drain tank 59 is connected via the circulation path 59B to the throttle portion 54A, which is a portion whose diameter is locally reduced until the exhaust passage 54 reaches the drain separator 57. The pressure is lower than the outlet side of the drain separator 57. For this reason, the drain is easily accommodated in the drain tank 59.

  The operation of driving and rotating the screw downward is performed by a driver bit 11 provided so as to extend vertically on the central axis of the housing 10. The driver bit 11 moves up and down in FIG. 1 and rotates, so that one end (lower end) of the driver bit 11 is driven and rotated. FIG. 1 shows a state (initial state) immediately before this operation is performed. An injection part 12 extending in the vertical direction is mounted on the lower side of the housing 10, and the lower end of the driver bit 11 moves in the vertical direction inside the injection part 12. A push lever 13 slidable in the vertical direction along the injection portion 12 and biased downward is attached to the lowermost end of the injection portion 12. In addition, a magazine 60 that accommodates a plurality of screws is mounted on the right side (the same side as the handle 50) of the injection unit 12, and one screw is automatically injected by the screw feeding unit 61 for each operation. Load 12a. The loaded screw is driven downward by a driver bit 11 for a length less than its entire length, and then tightened by applying a rotational force.

  In addition, a trigger lever 14 is mounted below the connecting portion between the handle 50 and the housing 10, and an operation valve 15 connected to the trigger lever 14 is provided above the trigger lever 14. The above-described driving operation is performed by setting the operation valve 15 to the operated (for example, opened) state. However, the operation valve 15 is set to open when the trigger lever 14 is pulled upward and the push lever 13 is moved upward. As for the structure, a known trigger lever or push lever structure can be employed. The push lever 13 moves upward when the operator abuts the lower end of the injection unit 12 on a plate material or the like, and a driving operation is performed when both the trigger lever 14 and the push lever 13 are in operation. As a specific example, the operator makes contact with the lower end of the injection unit 12 at a position where the screw is to be driven, and pulls the trigger lever 14 in a state where the push lever is moved upward, whereby the screw driving operation is started.

  Next, a mechanism related to the operation of the driver bit 11 in the housing 10 and an operation in the housing 10 when the operation valve 15 is opened will be described.

  In the housing 10, a spindle 20 that is closed on the upper side and opened on the lower side to be rotatable is provided. A spindle 20 is provided in the upper part of the housing 10 and is connected to an air motor 21 that rotates by introducing compressed air through a planetary gear mechanism 22. Specifically, the sun shaft in the planetary gear mechanism 22 is fixed to the output shaft (rotary shaft) of the air motor 21, and the shaft portion of the revolving gear that meshes with the sun shaft is fixed to the spindle 20. For this reason, the spindle 20 rotates within the housing 10 with an appropriate reduction ratio as the air motor 21 rotates.

  Inside the spindle 20, a slider (piston) 23 is provided so as to be movable in the vertical direction with respect to the spindle 20. However, the outer periphery of the slider 23 and the inner surface of the spindle 20 are formed so as to engage with convex portions and concave portions, respectively, and when the spindle 20 rotates, the slider 23 also rotates. That is, the slider 23 is not rotatable with respect to the spindle 20 and is movable in the vertical direction. Although the slider 23 is described as being divided in the vertical direction in FIG. 1, these are actually integrated outside the range shown in the drawing. Further, the slider 23 is provided with an air blocking surface 23A for blocking the space in the vertical direction of the slider 23 when the slider 23 descends and comes into contact with a plate portion 31 described later.

  A sub piston part (piston) 24 is fixed to the slider 23. The sub-piston portion 24 is formed by integrating a cylindrical shaft 241 located on the upper side, a sub-piston 243 provided via a columnar sub-piston coupling portion 242 on the lower side, and a driver bit mounting portion 244 on the lower side. It is composed. The driver bit mounting portion 244 is formed with a flange portion 245 having a larger outer diameter. The upper end (the other end) of the driver bit 11 is mounted on the driver bit mounting portion 244. For this reason, the movement of the driver bit 11 reflects the movement of the slider 23 and the auxiliary piston part 24. The outer diameter of the auxiliary piston 243 is larger than that of the shaft 241.

  A cylinder 30 that is cylindrical and fixed to the housing 10 is fixed to the lower side of the spindle 20 with the rotation axis of the spindle 20 as a central axis. On the lower side of the spindle 20, a plate portion 31 that locks the air blocking surface 23 </ b> A of the slider 23 when the slider 23 descends is provided on the upper portion of the cylinder 30. The screw tightening depth is determined by the range in which the driver bit 11 can move downward, but the lower limit position is a position when the air blocking surface 23A and the plate portion 31 come into contact with each other.

  A main piston portion 25 is mounted inside the spindle 20 so as to surround the sub piston portion 24 below the slider 23. However, the main piston portion 25 is not fixed to the sub piston portion 24 and the slider 23, and is movable in the vertical direction with respect to these. The outer diameter of the main piston portion 25 is smaller than the inner diameter of the cylinder 30. In FIG. 1, the main piston portion 25 is described as being divided in the vertical direction, but actually, these are integrated outside the range shown in the drawing. A communication hole 25 a is formed in the main piston portion 25 so as to communicate the space provided between the sub piston portion 24 and the outer periphery of the main piston portion 25.

  The slider 23, the sub piston part 24, and the main piston part 25 function as a piston that causes the driver bit 11 to move up and down by compressed air when combined. At this time, the downward movement of the slider 23 is limited by the contact between the air blocking surface 23A and the plate portion 31, and the portion of the slider 23 above the air blocking surface 23A is lowered to the cylinder 30 side. There is no. On the other hand, the main piston part 25 and the auxiliary piston part 24 provided inside thereof can be lowered to the inside of the cylinder 30 side. On the lower end side of the cylinder 30, a bumper 32 made of an elastic body that abuts against the sub piston portion 24 and the like and absorbs an impact when the sub piston portion 24 descends is provided so as to surround the driver bit 11. When the sub piston part 24 is lowered, the flange part 245 contacts the bumper 32.

  In the housing 10, a first air passage 10 a connected to the operation valve 15 and a second air passage (air supply passage) that surrounds the spindle 20 outside the spindle 20 and is isolated from the spindle 20. 10b and a return air chamber 10c surrounding the cylinder 30 are formed. Further, a third air passage 10d (rotation operation control air passage: broken line) used for driving the air motor 21 and connected to the pilot valve 100 is also provided. The second air passage 10b always communicates with the pressure accumulating chamber 52 and stores compressed air therein, and the compressed air in the second air passage 10b is directly used for the driving operation.

  A slider chamber is formed between the upper side of the slider 23 and the upper surface of the spindle 20, and a cylinder chamber 30 a is formed in the cylinder 30. A check valve is provided near the lower side of the cylinder 30 and a compressed air outflow hole 30b connected to the return air chamber 10c is provided. By this check valve, the flow of air from the cylinder chamber 30a to the return air chamber 10c is allowed, and the flow of air from the return air chamber 10c side to the cylinder chamber 30a side is suppressed. A compressed air inflow hole 30c that allows air to flow from the return air chamber 10c side to the cylinder chamber 30a is formed further below the compressed air outflow hole 30b in the cylinder 30. Further, since the O-ring 32A is provided around the driver bit 11 in the bumper 32, it is possible to prevent the compressed air in the cylinder chamber 30a from leaking to the outside below the cylinder chamber 30a.

  In the above configuration, the driving operation is started by introducing the compressed air in the second air passage 10b into the slider chamber. In order to perform this operation, the above-described components are appropriately provided with a vent hole through which air passes and an O-ring. Hereinafter, this point will be described in accordance with the operations of the slider 23, the sub piston portion 24, the main piston portion 25, and the like. FIG. 2 is an enlarged view of the structure inside the housing 10 in FIG. 1 for this purpose.

  A cylinder intake port (intake hole) 20b is provided on the side surface of the spindle 20, and a cylinder exhaust port (exhaust hole) 20c is provided on the lower side thereof. The second air passage (air supply passage) 10b is connected to the cylinder intake port 20b. Controls on / off the introduction of compressed air. When the introduction of compressed air is turned on, the driving operation is started. By introducing the compressed air into the inside of the spindle 20 (slider chamber), the slider 23, the sub piston portion 24, and the main piston portion 25 are pushed down. A vent hole is formed in the shaft 241 of the sub piston portion 24 so that this operation is performed smoothly.

  An O-ring 25c is attached to the outer periphery of the lower portion of the main piston portion 25 in the vertical direction. For this reason, the air on the slider chamber side and the air on the cylinder chamber 30a side are separated at the place where the O-ring 25c is mounted. For this reason, the slider 23 and the like start the above-described downward movement by the compressed air above the O-ring 25c. Thereafter, when the O-ring 25b on the outer periphery near the center of the main piston portion 25 contacts the inner surface of the cylinder chamber 30a, the downward movement is continued by the compressed air above the O-ring 25b.

  On the other hand, the plate portion 31 is formed with a vent hole 31 a communicating with the third air passage 10 d connected to the air motor 21 side via the pilot valve 100. For this reason, when the main piston part 25 descends and the O-ring 25b is located below the vent hole 31a, a part of the compressed air on the slider chamber side passes through the vent hole 31a and the third air passage 10d. Flowing into. The opening and closing of the pilot valve 100 is controlled by this compressed air. As will be described later, when the pilot valve 100 is opened, compressed air is introduced into the air motor 21 and the air motor 21 rotates. As a result, the spindle 20 connected to the air motor 21 via the planetary gear mechanism 22 rotates, and the internal slider 23, sub piston portion 24, and driver bit 11 rotate.

  When the main piston part 25 further descends and the O-ring 25c mounted below the O-ring 25b on the outer periphery of the main piston part 25 reaches the position of the compressed air outflow hole 30b, a part of the air in the slider chamber Flows into the return air chamber 10c through a vent provided in the shaft 241, a communication hole 25a, and a compressed air outflow hole 30b. Thereafter, the main piston portion 25 is locked by the bumper 32, and only the sub piston portion 24 is lowered, and the driver bit 11 is lowered and rotated by the thrust of only the sub piston portion 24.

  Thereafter, when the screw is tightened to a predetermined depth (the driver bit 11 or the sub-piston portion 24 is lowered to a predetermined position), the air blocking surface 23A of the slider 23 comes into contact with the plate portion 31, so that the lowering stops. . As a result, the slider chamber is sealed, and the supply of compressed air in the slider chamber to the third air passage 10d via the vent hole 31a is also stopped, so that the rotation of the sub piston portion 24 (driver bit 11) is also stopped. This completes the tightening operation.

  After that, when the operation valve 15 is closed and the introduction of air from the second air passage 10b to the cylinder inlet 20b on the side surface of the spindle 20 is turned off, the compressed air in the slider chamber passes through the cylinder outlet 20c. Then, it flows into the exhaust passage 54 and is exhausted. After that, by introducing the compressed air in the return air chamber 10c into the cylinder chamber 30a through the compressed air inflow hole 30c, the main piston portion 25 and the like are pushed up to the initial state, contrary to the above.

  In the above operation, the driving operation is started by introducing the compressed air from the second air passage 10b to the cylinder intake port 20b. This operation will be described below. This operation is performed by moving the cylindrical sleeve valve 40 surrounding the spindle 20 upward.

  In this configuration, a cylindrical groove 70 in which the sleeve valve 40 can move in the vertical direction is formed in the housing 10 below the second air passage 10b. The sleeve valve 40 is biased upward by a spring 71 in the groove 70. The sleeve valve 40 is movable in the vertical direction within the groove 70. The sleeve valve 40 is opposed to the upper inner surface of the sleeve valve 40 on the upper side of the sleeve valve 40 and opposed to the inner surface of the groove 70 on the lower side of the sleeve valve 40. An O-ring seals between the inner inner surface and the outer inner surface of the groove 70 to be formed. The sleeve valve 40 is formed with a main valve vent hole 40a penetrating between the inside and the outside. The groove 70 communicates with the first air passage 10a on the lower side thereof, and a fourth air passage 10e formed in the housing 10 is formed outside the groove 70 so as to communicate with the exhaust passage 54. Yes.

  When the operation valve 15 is closed, the first air passage 10 a communicates with the pressure accumulation chamber 52. For this reason, the sleeve valve 40 is urged upward by the compressed air in the first air passage 10a and conversely downward by the compressed air in the second air passage. Furthermore, since the spring 71 is provided, the sleeve valve 40 is positioned on the upper end side in the groove 70 when the operation valve 15 is closed.

  When the sleeve valve 40 is positioned on the upper end side, the upper end of the sleeve valve 40 is locked by the upper surface of the groove 70, and the sleeve valve 40 closes the space between the second air passage 10b and the cylinder intake port 20b. For this reason, the compressed air in the second air passage 10b is not introduced into the inside of the spindle 20 (slider chamber) via the tube intake port 20b. On the other hand, in this state, the cylinder exhaust port 20c communicates with the main valve vent 40a and the fourth air passage 10e, and the compressed air in the slider chamber flows into the exhaust passage 54, so that the slider chamber is at atmospheric pressure.

  When the operation valve 15 is opened (when the trigger 14 is pulled), the first air passage 10a communicates with the atmosphere. For this reason, the sleeve valve 40 is urged downward by the compressed air in the second air passage 10b, and the load of the spring 71 is set so that this force is larger than the elastic force of the spring 71. The valve 40 is biased downward, and the sleeve valve 40 moves to the lower end side in the groove 70.

  When the sleeve valve 40 is positioned on the lower end side, the second air passage 10b and the cylinder intake port 20b communicate with each other, and compressed air is introduced into the slider chamber from the second air passage 10b. On the other hand, since the cylinder exhaust port 20c is closed by the sleeve valve 40, the compressed air in the slider chamber is not discharged. For this reason, the pressure of the air in the slider chamber increases. Thereby, the above driving operation is performed.

  The tightening operation (rotation of the air motor 21) starts when the main piston portion 25 descends and a part of the compressed air on the slider chamber side flows into the third air passage 10d through the vent hole 31a. In the screwdriver 1, the compressed air flows through the various paths as described above from the pressure accumulation chamber 52 to the exhaust passage 54. The compressed air that pushes down the slider 23 and the like is upstream in the flow. The compressed air that is located and flows through the third air passage 10d is located on the downstream side, and the compressed air flows through these complicated paths between them. For this reason, it is possible to directly drive the air motor 21 with the compressed air supplied into the third air passage 10d. However, there is a portion where the passage is long and the passage area is small, and the response speed is slow. For this reason, the timing for starting the operation of rotating the driver bit 11 is delayed, or a delay time occurs until sufficient torque is generated.

  In order to speed up this operation, the screw driver 1 is provided with a pilot valve 100. In addition to the third air passage 10d, the pilot valve 100 includes a fifth air passage 10f that communicates with the pressure accumulating chamber 52, a sixth air passage 10g that communicates with the compressed air supply port of the air motor 21, an exhaust passage 54, or other locations. A seventh air passage 10h communicating with the atmosphere is connected via FIG. 3 shows the configuration when the pilot valve 100 is closed, and FIG. 4 shows the configuration when the pilot valve 100 is open. In the open state (FIG. 4), the fifth air passage 10f and the sixth air passage 10g communicate with each other, so that the compressed air in the pressure accumulation chamber 52 flows directly to the sixth air passage 10g and is supplied to the air motor 21. . Thereby, the air motor 21 can be directly rotated by the compressed air in the pressure accumulating chamber 52. When the compressed air is introduced into the third air passage 10d, the air motor 21 can be immediately rotated with a large torque.

  Further, by using the pilot valve 100, the rotation of the driver bit 11 can be started quickly as described above, and the rotation can also be stopped quickly. Thereby, it is also suppressed that the screw is tightened more than necessary. Hereinafter, the structure including the pilot valve 100 will be described in detail.

  As shown in FIGS. 3 and 4, the pilot valve 100 slides in the vertical direction within the substantially cylindrical valve chamber 101. Further, the pilot valve 100 is formed with a lower seal portion 100A, a middle seal portion 100B, and an upper seal portion 100C having locally increased outer diameters at the lowermost portion, the central portion in the vertical direction, and the uppermost portion, respectively. A portion between the lower seal portion 100A and the middle seal portion 100B in the pilot valve 100 is formed into a substantially cylindrical shape having an outer diameter smaller than those of the lower seal portion 100A and the middle seal portion 100B, and the middle seal portion 100B and the upper seal in the pilot valve 100 are formed. A portion between the portions 100C is formed in a substantially cylindrical shape having an outer diameter smaller than that of the middle seal portion 100B and the upper seal portion 100C. O-rings 102A, 102B, and 102C are provided on the outer periphery of the lower seal portion 100A, the middle seal portion 100B, and the upper seal portion 100C, respectively, and the inner surfaces of the lower seal portion 100A, the middle seal portion 100B, the upper seal portion 100C, and the valve chamber 101 The pilot valve 100 slides up and down in the valve chamber 101 in a state where the gaps are sealed. Therefore, annular spaces are formed between the lower seal portion 100A and the middle seal portion 100B, and between the middle seal portion 100B and the upper seal portion 100C, respectively, between the inner surface of the valve chamber 101. Further, the outer diameter is increased in the order of the middle seal portion 100B, the lower seal portion 100A, and the upper seal portion 100C, and the inner shape (inner diameter) of the valve chamber 101 is set so that the pilot valve 100 can move in the vertical direction. ing. The pilot valve 100 restricts the movement to the lower side (one end side) when the lower surface (end surface on one end side) of the lower seal portion 100A contacts the lower surface of the valve chamber, and the upper surface (the other end side) of the upper seal portion 100C. ) Is in contact with the upper surface of the valve chamber 101 to restrict the upward movement (the other end side).

  Further, in the pilot valve 100, a spring accommodating hole 100D is formed from the upper surface (upper seal portion 100C) side to the lower side, and a spring 103 that can be expanded and contracted in the vertical direction is included in the pilot valve 100. The upper surface and the lower end of the valve chamber 101 are provided so as to be engaged with the bottom surface of the spring housing hole 100D. The bottom surface of the spring housing hole 100D is formed so as to be located inside the lower seal portion 100A. Therefore, in the valve chamber 101, the pilot valve 100 is urged downward by the spring 103.

  A valve chamber intake port 104 that is directly connected to the third air passage (rotational operation control air passage) 10d is provided on the lower surface (end surface on one end side) of the valve chamber 101. On the other hand, a valve chamber exhaust port 105 that is directly connected to the seventh air passage 10h and discharges compressed air in the valve chamber 101 to the outside is provided on the upper surface (the end surface on the other end side) of the valve chamber 101. The lower seal portion 100A is provided with a small communication hole (air vent path) 106 that communicates the lower surface side with the spring housing hole 100D. In this structure, compressed air is introduced from the third air passage 10 d into a space (valve operation control chamber) between the lower surface of the lower seal portion 100 </ b> A and the lower surface of the valve chamber 101, and pilots against the elastic force of the spring 103. The valve 100 can be pushed up. At this time, the space between the upper surface of the upper seal portion 100C and the upper surface of the valve chamber 101 is compressed, but the air inside this space is exhausted to the seventh air passage 10h via the valve chamber exhaust port 105. That is, the pilot valve 101 can be moved to the upper end side by increasing the pressure in the third air passage 10d (introducing compressed air into the third air passage 10d).

  As shown in FIG. 3, a state where the pressure in the third air passage 10d is low and the lower surface of the pilot valve 100 and the lower surface of the valve chamber 101 are in contact with each other is a state where the pilot valve 100 is closed. In this state, the valve chamber 101 connects the fifth air passage 10f communicating with the pressure accumulating chamber 52 to a location between the middle seal portion 100B and the upper seal portion 100C in the valve chamber 101. Further, the sixth air passage 10g communicating with the compressed air supply port of the air motor 21 is connected to the space between the lower seal portion 100A and the middle seal portion 100B. For this reason. The compressed air introduced from the fifth air passage 10f is introduced into the space between the middle seal portion 100B and the upper seal portion 100C. However, since this space is sealed by the middle seal portion 100B on the lower side and the upper seal portion 100C on the upper side, this compressed air is not located in other places, such as the space between the lower seal portion 100A and the middle seal portion 100B. It does not flow to the air motor 21 side.

  Here, in addition to the spring 103, the pilot valve 100 also receives a pressing force of compressed air in the fifth air passage 10f that is always present. The force that the pilot valve 100 receives in the vertical direction due to the pressing force is determined by the configuration of a horizontal plane (a plane perpendicular to the vertical direction) in contact with the compressed air in the pilot valve 100. In FIG. 3, this surface is an upper surface (upward surface) of the middle seal portion 100B and a lower surface (downward surface) of the upper seal portion 100C. The pilot valve 100 is formed by an upward surface. Pressurized downward and pressurized upward by the downward surface. Here, as described above, since the outer diameter of the middle seal portion 100B is set larger than the outer diameter of the upper seal portion 100C, the area of the upward surface is larger than the area of the downward surface. For this reason, in the state of FIG. 3, the pilot valve 100 is urged downward by the compressed air in the fifth air passage 10f. Further, since the spring 103 is also urged downward, when the pressure in the third air passage 10d is low, the state of FIG. 3 in which the pilot valve 100 is located on the lower end side of the valve chamber 101 is stabilized. Maintained.

  On the other hand, when the compressed air is introduced into the third air passage 10d, since the opening area of the communication hole 106 is set to be sufficiently small, the lower surface of the pilot valve 100 is pushed up by this compressed air, and the lower seal portion 100A. 4 in which the compressed air is introduced into the valve operation control chamber 101A formed as a space between the valve chamber 101 and the lower surface of the valve chamber 101. In this state, the fifth air passage 10f is connected to a space above and below the middle seal portion 100B in the valve chamber 101, particularly a space between the lower seal portion 100A and the middle seal portion 100B. Similarly to the case of FIG. 3, the sixth air passage 10g communicating with the compressed air supply port of the air motor 21 is connected to the space between the lower seal portion 100A and the middle seal portion 100B. For this reason, in the state of FIG. 4, compressed air is supplied to the air motor 21 from the fifth air passage 10 f (pressure accumulation chamber 52). Thereby, the air motor 21 can be operated.

  Here, in the configuration of FIG. 4, compared to the case of FIG. 3, the number of surfaces that receive a force in the vertical direction by the compressed air in the fifth air passage 10 f is large, and in the same way as described above, downward The direction of the force that the pilot valve 100 receives by the compressed air in the fifth air passage 10f is determined by the difference between the pressure receiving area and the upward pressure receiving area. In the configuration of FIG. 4, since the outer diameters of the lower seal portion 100A, the middle seal portion 100B, and the upper seal portion 100C are set as described above, the upward pressure receiving area is slightly increased, and the pilot valve 100 is The compressed air in the fifth air passage 10f is biased downward (valve chamber intake port 104 side). However, in this case, an upward force is also applied to the lower surface of the lower seal portion 100A by the compressed air in the valve operation control chamber 101A, and the area of the lower surface of the lower seal portion 100A is sufficiently larger than the difference in the pressure receiving area. When the opening area of the communication hole 106 is sufficiently small, as a result, the pilot valve 100 is urged upward (to the valve chamber exhaust port 105 side). For this reason, when compressed air is introduced into the third air passage 10d, the state in which the pilot valve 100 moves to the upper side of the valve chamber 101 is stably maintained as shown in FIG. Compressed air can be supplied.

  That is, by introducing compressed air into the third air passage 10d from the state of FIG. 3, the compressed air in the pressure accumulating chamber 52 can be directly supplied to the air motor 21 and the driver bit 11 can be rotated.

  Next, a case where the rotation of the driver bit 11 is stopped will be described. This corresponds to changing from the state of FIG. 4 to the state of FIG. This operation stops the supply of compressed air to the third air passage 10d via the vent hole 31a, lowers the pressure in the third air passage 10d (to atmospheric pressure), and supplies the compressed air to the air motor 21. Is done by stopping. However, for this purpose, it is necessary to extract the compressed air in the third air passage 10d from various paths, and a certain time is required to sufficiently reduce the pressure. For this reason, a certain time is required from the start of the pressure drop in the third air passage 10d until the supply of compressed air to the air motor 21 stops and the rotation stops. In this case, the rotation of the driver bit 11 cannot be stopped quickly, and the driver bit 11 may rotate more than necessary.

  In order to shorten this time, it is effective to discharge the compressed air in the valve operation control chamber 101A to the outside. For this purpose, in the configuration of FIGS. 3 and 4, a communication hole 106 is provided in the lower seal portion 100A. The compressed air in the valve operation control chamber 101 </ b> A is discharged to the outside through the spring accommodation hole 100 </ b> D and the pilot valve exhaust port 105 through the communication hole 106. At this time, when the pressure of the air in the third air passage 10d decreases and the pressure of the air in the valve operation control chamber 101A decreases, the pilot air is compressed by the compressed air in the spring 103 and the fifth air passage 10f as described above. The valve 100 is biased downward. For this reason, the air in the valve operation control chamber 101A is quickly discharged even when the pilot valve 100 is pressurized downward.

  As a result, the supply of compressed air to the air motor 21 is quickly stopped, and the rotation can be quickly stopped.

  If the opening area of the communication hole 106 is large, the compressed air in the valve operation control chamber 101A can be easily discharged as described above, so that the rotation can be stopped more quickly at the end of the screw tightening operation. It can be carried out. However, on the other hand, since the compressed air leaks from the communication hole 106 even when the pilot valve 100 is opened (the state shown in FIG. 4), the pressure rise to move the pilot valve 100 upward is delayed, and the air motor The operation start timing of 21 is delayed. Even in this case, since the compressed air in the pressure accumulating chamber 52 directly drives the air motor 21 without passing through the inside of the cylinder, the start-up of the rotation of the air motor 21 becomes faster, and the air motor 21 is compressed in the third air passage 10d. The driver bit 11 can be rotated faster than the case of driving with. However, the opening area of the communication hole 106, the spring constant of the spring 103, the external dimensions of each part of the pilot valve 100, and the like can be set in consideration of such characteristics of the start and stop of the rotation operation.

  Further, when the opening area (cross-sectional area perpendicular to the flow) of the communication hole (air vent path) 106 is equal to or larger than the opening area of the valve chamber intake port 104, the pilot is substantially caused by the compressed air in the third air passage 10d. The operation of pushing up the valve 100 may be slow. For this reason, in order to perform the above operation appropriately, the opening area of the communication hole 106 is preferably 0.5 times or less than the opening area of the valve chamber intake port 104. Further, in order to increase the operating speed of the pilot valve 100, the air between the upper surface of the upper seal portion 100C and the upper surface of the valve chamber 101 is quickly released to the seventh air passage 10h via the valve chamber exhaust port 105. There is a need. At this time, if the opening area of the communication hole 106 is equal to or larger than the opening area of the valve chamber exhaust port 105, the release of the air may be delayed. For this reason, the opening area of the communication hole 106 is preferably 0.5 times or less than the opening area of the valve chamber exhaust port 105.

  As described above, in the pilot valve 100 described above, when the pressure in the third air passage 10d increases, the compressed air in the pressure accumulating chamber 52 is directly supplied to the air motor 21 without passing through the cylinder. When the start timing of the rotary motion of the air motor 21 is advanced and the pressure in the third air passage 10d decreases, the compressed air in the valve operation control chamber 101A is discharged to the outside, so that the rotational motion of the air motor 21 is reduced. The stop timing can be advanced. Thereby, the operation of the screwdriver 1 can be performed efficiently.

  FIGS. 5-12 is a figure which shows the state for every process in operation | movement of said screwdriver 100 with the form similar to FIG. In these drawings, the movement of the slider 23 and the like and the flow of compressed air are indicated by arrows, and the screw X is driven into the surface S of the member to be fastened. In the screwing operation, the states from FIG. 5 to FIG. 12 are continuously changed. Here, FIG. 5 shows an initial state (a state in which the operation valve 15 is closed and the driver bit 11 is at the top), and FIG. 6 shows a state in which the operation valve 15 is opened from the initial state. In the state of FIG. 6, the first air passage 10 a communicates with the atmosphere, so the compressed air in the first air passage 10 a is exhausted to the outside.

  FIG. 7 shows that when the push lever 13 is pressed against a member to be tightened such as wood and the trigger lever 14 is pulled, the operation valve 15 moves upward in the drawing, so that the sleeve valve 40 is opened, and the main piston is compressed by compressed air. The state immediately after the start of the driving operation in which the part 25 starts to descend is shown. In FIG. 8, since the main piston portion 25 is lowered and the O-ring 25b is located below the vent hole 31a, the compressed air on the slider chamber side flows into the third air passage 10d via the vent hole 31a. 21 shows a state in which rotation starts, that is, a state immediately after the driving operation is finished and the tightening operation is started. As described above, by supplying the compressed air in the pressure accumulating chamber 52 directly to the air motor 21 using the pilot valve 100, the operation of the air motor 21 at this time is quickly performed. In this state, the driver bit 11 (sub-piston portion 24, etc.) has been lowered by the impact force of the compressed air, so that the lower end side of the screw X is driven into the surface S. FIG. 9 shows a state where the driver bit 11 (sub-piston portion 24) is lowered while rotating from this state. In this state, since the O-ring 25c is below the compressed air outflow hole 30b, part of the air in the slider chamber flows into the return air chamber 10c through the compressed air outflow hole 30b.

  FIG. 10 shows a state immediately after the tightening operation is finished. In this state, the flange portion 245 of the sub piston portion 24 contacts the bumper 32, and the air blocking surface 23 </ b> A of the slider 23 contacts the plate portion 31. Accordingly, the slider chamber is sealed from the space below the plate portion 31, and the compressed air on the slider chamber side is suppressed from flowing into the third air passage 10d through the vent hole 31a. As a result, the pressure of the air in the third air passage 10d is reduced, the pilot valve 100 is closed, and the air motor 21 is stopped. As described above, the air motor 21 is rapidly stopped at this time. The decrease in the pressure of the air in the third air passage 10d is caused by the slider 23 (sub piston portion 24, driver bit 11) descending to a predetermined position after the tightening operation is started, that is, the screw X is tightened to a predetermined depth. It is started by having entered. That is, the above operation when the pilot valve 100 is closed from the open is performed when the screw X is tightened to a predetermined depth. For this reason, it is suppressed that the screw X is tightened more than necessary.

  FIG. 11 shows a state where the operation valve 15 is closed by stopping pulling the trigger lever 14 and the first air passage 10 a communicates with the pressure accumulating chamber 52. As a result, the sleeve valve 40 is closed, and the supply of compressed air from the second air passage 10b to the cylinder intake port 20b is stopped. At the same time, the compression in the slider chamber is performed via the cylinder exhaust port 20c and the main valve vent hole 40a. Air is exhausted. Thereby, as shown in FIG. 12, the compressed air in the return air chamber 10c is introduced into the cylinder chamber 30a through the compressed air inflow hole 30c, and the slider 23, the sub piston portion 25, the driver bit 11, and the main piston portion 25 are introduced. Rises to the initial state (state shown in FIG. 5).

  As described above, in the screwing machine 1 described above, by using the pilot valve 100, the screwing work can be efficiently performed. However, other configurations having functions similar to those described above can be used. In particular, a configuration other than the configuration of the pilot valve and the valve chamber shown in FIGS. 3 and 4 can be used as the configuration for discharging the compressed air in the valve operation control chamber to the outside. FIGS. 13 and 14 are views showing an example of such a structure (first modified example). Here, FIG. 13 shows a state where the pilot valve 110 is closed (corresponding to FIG. 3), and FIG. 14 shows that the pilot valve 110 is opened. (Corresponding to FIG. 4). The pilot valve 110 is also provided with a lower seal portion 110A, a middle seal portion 110B, and an upper seal portion 110C similar to the pilot valve 100, similarly formed with a spring accommodating hole 110D, and using the spring 103 in the same manner. However, the pilot valve 110 (lower seal portion 110A) is not provided with a communication hole. The pilot valve 110 slides in a valve chamber 111 having a configuration different from that of the valve chamber 101 described above. In this configuration, since the communication hole is not provided in the pilot valve 110, the compressed air in the valve operation control chamber 111A cannot be extracted from the spring accommodating hole 110D side. However, in the valve chamber 111, the air vent path 112 is connected to the side of the valve operation control chamber 111A, and the compressed air in the valve operation control chamber 111A can be vented from the air vent path 112 in the same manner as described above. For this reason, even when the pilot valve 110 and the valve chamber 111 are combined as shown in FIGS. 13 and 14, the same effect as when the pilot valve 100 and the valve chamber 101 are combined as shown in FIGS.

  However, in the configuration of FIGS. 13 and 14, the air vent path 112 is directly connected to the valve operation control chamber 111A, so that the conductance of the flow of compressed air can be reduced as compared with the configuration of FIGS. . For this reason, the operation | movement which stops the air motor 21 can be performed still more rapidly than the structure of FIG.

  FIGS. 15 and 16 are diagrams similarly showing a modification (second modification) of the configuration of FIGS. In this structure, the air vent path 112 is connected not to the valve operation control chamber 111A but to the third air passage 10d. As a result, the compressed air in the valve operation control chamber 111A can be extracted as in the structure of FIGS. 13, 14, and FIGS. 15 and 16, the opening area of the air vent path 112 (cross-sectional area perpendicular to the air flow) can be made 0.5 times or less the opening area of the valve chamber intake port 104. The same is preferable.

  As described above, various configurations can be used for the pilot valve and the valve chamber. In the above example, a part of the air in the valve operation control chambers 101A and 111A always leaks to the outside, and this leakage amount is particularly large when the pressure of the air in the third air passage (rotational operation control air passage) 10d increases. In order to increase the speed, the operating speed of the pilot valves 100 and 110 when switching between opening and closing was increased. However, for example, the same effect can be obtained by using a mechanism that releases the air in the valve operation control chamber to the outside only when the pilot valve is switched from open to closed (when the pressure of the air in the third air passage 10d decreases). It is clear that Alternatively, when it is desired to advance only the operation start timing of the air motor, it is not necessary to evacuate the valve operation control chamber.

  Further, in the above example, since the compressed air used for the driving operation is caused to flow into the rotation operation control air passage when the driving operation is completed up to a predetermined position, the pilot valve is operated with the air pressure in the rotation operation control air passage. It was opened when it increased. However, this setting can be appropriately performed according to a mechanism that performs a driving operation using compressed air. That is, for example, the air pressure in the rotational motion control air passage is reduced at the end of the driving operation, and a pilot valve that is in a closed to open state when this pressure is reduced is used. You can also. It is also clear that such a pilot valve can be realized with a configuration similar to that shown in FIGS.

1 Screwing machine (driving machine)
10 Housing 10a First air passage 10b Second air passage (air supply passage)
10c Return air chamber 10d Third air passage (rotational motion control air passage)
10e Fourth air passage 10f Fifth air passage 10g Sixth air passage 10h Seventh air passage 11 Driver bit 12 Injection portion 12a Injection passage 13 Push lever 14 Trigger lever 15 Operation valve 20 Spindle 20b Cylinder intake port 20c Cylinder exhaust port 21 Air motor 22 Planetary gear mechanism 23 Slider (piston)
23A Air blocking surface 24 Sub piston part (piston)
25 Main piston part (piston)
25a Communication holes 25b, 25c, 32A, 102A, 102B, 102C O-ring 30 Cylinder 30a Cylinder chamber 30b Compressed air outflow hole 30c Compressed air inflow hole 31 Plate portion 31a Vent hole 32 Bumper 40 Sleeve valve 40a Main valve vent hole 50 Handle 51 Air plug 52 Accumulation chamber 53 Pressure reducing valve 54 Exhaust passage 54A Throttle portion 55 Exhaust port 56 Exhaust pipe 57 Drain separator 58 Muffler 59 Drain tank 59A Flow path 59B Circulation path 60 Magazine 61 Screw feed section 70 Groove 71, 103 Spring 100, 110 Pilot valve 100A, 110A Lower seal portion 100B, 110B Middle seal portion 100C, 110C Upper seal portion 100D, 110D Spring storage hole 101, 111 Valve chamber 101A, 111A Valve operation control chamber 104 Valve chamber intake port 05 valve chamber outlet 106 communicating hole (vent path)
112 Air vent path 241 Shaft 242 Sub-piston coupling part 243 Sub-piston 244 Driver bit mounting part 245 Hook X Screw S Surface of member to be fastened

Claims (11)

A driving machine that performs a driving operation for driving a stopper member into a member to be fastened along a driving direction and a tightening operation for rotating and tightening the stopper member using compressed air stored in a pressure accumulating chamber as a power source. There,
A rotational motion control air passage to which compressed air is supplied after the piston has moved to a predetermined position;
An air motor that performs an operation of rotating the stopper member with compressed air;
A pilot valve that is connected to the rotation operation control air passage and performs an operation of supplying compressed air in the pressure accumulating chamber to the air motor by compressed air supplied into the rotation operation control air passage;
A driving machine characterized by comprising:   The pilot valve slides inside the valve chamber according to the pressure of air in the rotation operation control air passage, and compresses the pressure accumulating chamber to the air motor according to the position of the pilot valve in the valve chamber. The driving machine according to claim 1, wherein on / off of air supply is controlled. The rotational movement control air passage is connected to the valve chamber via a valve chamber intake port provided on one end side of the valve chamber, and the valve chamber is connected to a valve chamber exhaust port provided on the other end side. Communicate with the atmosphere
When compressed air is supplied from the rotational operation control air passage to the valve operation control chamber which is a space between the end surface on the one end side of the pilot valve and the end surface on the one end side of the valve chamber in the valve chamber, Supplying compressed air in the pressure accumulating chamber to the air motor;
When compressed air is not supplied from the rotational operation control air passage to the valve operation control chamber, the pilot valve moves to the one end side so that compressed air in the pressure accumulation chamber is not supplied to the air motor. The driving machine according to claim 2.   4. The driving machine according to claim 2, further comprising an air vent path for releasing a part of the compressed air supplied from the rotation operation control air passage to the atmosphere on the pilot valve side.   5. The driving machine according to claim 4, wherein, in the tightening operation, when the stopper member is tightened to a predetermined depth, compressed air is not supplied to the rotation operation control air passage.   6. The driving machine according to claim 4, wherein the air vent path is connected to the rotation operation control air path.   4. The driving machine according to claim 3, wherein an air vent path for releasing compressed air introduced into the valve operation control chamber to the atmosphere is connected to the valve operation control chamber.   4. The driving machine according to claim 3, wherein an air vent path for releasing compressed air introduced into the valve operation control chamber to the atmosphere is formed on an end surface of the one end side of the pilot valve.   The driving machine according to any one of claims 6 to 8, wherein a cross-sectional area of the air vent path is 0.5 times or less of a cross-sectional area of the valve chamber intake port.   9. The driving machine according to claim 8, wherein a cross-sectional area of the air vent path is not more than 0.5 times a cross-sectional area of the valve chamber exhaust port. A substantially cylindrical spindle that is rotated by the air motor about a central axis along the driving direction;
A driver bit that contacts the stopper member and one end thereof, and drives and rotates the stopper member;
The other end side of the driver bit is fixed, is movable in the driving direction with respect to the spindle, and cannot be rotated with respect to the spindle around the central axis. The piston that moves to one end side of the driver bit by being introduced into a spindle, and
The compressed air introduced into the spindle after the piston has moved to one end side of the driver bit by a predetermined length flows into the rotation operation control air passage from the inside of the spindle. The driving machine according to any one of claims 1 to 10.

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