JP2007168035A - Stoppage controlling mechanism of air motor in pneumatic pressure type screw driving machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stoppage control mechanism of an air motor on a pneumatic pressure type screw driving machine to stop the air motor at a predetermined screw fastening position after screwing a driving screw by the air motor by striking the driving screw, simple in structure and devised not to wastefully consume air. <P>SOLUTION: An upper end of a valve housing 12 is opened to an air chamber 5, a conducting port 14 of a side wall is opened to the air motor 6, a cylindrical auxiliary valve 16 is arranged in the valve housing 12 so as to move downward by compression air boosted when a striking piston 2 is driven, a stop valve 22 is arranged below the auxiliary valve 16 free to vertically move, a lower part of a valve stem 28 stored in the inside of the stop valve 22 is projected downward in the valve housing 12, the stop valve 22 is pushed down as the auxiliary valve 16 moves downward when the striking piston 2 is driven, and the stop valve 22 is moved to a closing position of the conducting port 14 as the auxiliary valve 16 and the valve stem 28 work together when the driving screw 7 is fastened into predetermined screwing depth and a lower end of the valve stem 28 is pushed up. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stop control mechanism for an air motor in a pneumatic screw driving machine that stops an air motor at a predetermined screw tightening position after hitting a driving screw and further tightening the screw with an air motor in a pneumatic screw driving machine.

  Generally, a pneumatic screw driving machine is designed to lightly drive a driving screw against a material to be driven and then tighten it tightly. A mechanism and a screw tightening mechanism for rotating the driving screw are provided. The striking mechanism is configured such that a driver bit is integrally coupled to a striking piston slidably accommodated in a striking cylinder, a main valve is actuated by a trigger operation, and an air chamber for storing compressed air is provided with respect to the striking cylinder. It opens and closes and supplies compressed air to the striking cylinder to drive the striking piston. In contrast, the screw tightening mechanism uses an air motor to rotate the driver bit.

  Also, in the screw driving machine, the contact arm is slidably held along the nose part where the driving screw is ejected, urged so as to protrude in the driving direction from the nose part, and the tip is driven A safety device is known in which, when pressed against a material, the other end abuts against a contact arm stopper and is locked so as not to move any more, and the trigger operation becomes effective. Further, using the contact arm, the contact arm stopper is unlocked almost simultaneously with the operation of the striking mechanism by operating the trigger, and the driving screw is tightened by the air motor. There has been known an automatic stop control mechanism that controls an air motor to automatically stop when it is screwed so that the screwing depth is constant.

This is mainly composed of a stop valve and an exhaust valve, with the supply of compressed air to the exhaust valve as the pressure of the timer chamber connected to the air chamber rises, and the external input of the valve stem of the stop valve by the contact arm, When the screw head is flush with the material to be driven, the air motor is controlled to stop.
JP 2002-264032 A

  However, in the above technique, compressed air is sent from the air chamber to the exhaust valve through the timer chamber, and the air drips into the atmosphere from the exhaust hole provided in the exhaust valve, and moves with tightening of the driving screw. The air from the timer chamber of the exhaust valve stem is released to the atmosphere until the contact arm pushes the stem of the stop valve by a certain amount to close the exhaust hole. For this reason, when the material to be driven is hard, such as when the contact arm moves slowly and it takes time to operate the stop valve stem, the compressed air stored in the timer chamber is continuously discharged to the atmosphere. There is a problem that air consumption is increased.

  In addition, since two valves, a stop valve and an exhaust valve, are required, the structure is complicated and the number of parts is large, resulting in an increase in weight and cost.

  The present invention provides a stop control mechanism for an air motor in a pneumatic screw driving machine that solves the above problems, has a simple structure, can reduce the number of parts, and does not waste air. Is the subject.

  In order to solve the above-mentioned problem, the invention according to claim 1 is an operation in which an air motor is supplied into a striking cylinder by compressed air stored in an air chamber, and a driver bit integrally coupled to a striking piston in the interior is driven downward. And a screw tightening mechanism for rotating the driver bit by an air motor, the driver bit hits the driving screw by the hitting mechanism, and further tightens the driving screw by the screw tightening mechanism, In an air motor stop control mechanism in a pneumatic screw driving machine that controls to stop the air motor, a valve housing is provided between the air chamber and the air motor, and an upper end of the valve housing is opened to the air chamber. A conduction port formed on the side wall of the valve housing is used for the air motor. A cylindrical auxiliary valve is arranged in the upper part inside the valve housing so as to be movable up and down, and the auxiliary valve is moved downward by compressed air whose pressure is increased when the striking piston is driven, A cylindrical stop valve capable of opening and closing the conduction port is disposed below the auxiliary valve so as to be movable up and down, and a valve stem is accommodated in the stop valve so as to be movable up and down. Projecting downward from the opening in the lower part of the valve housing, and when the impact piston is driven, the auxiliary valve moves downward to push down the stop valve and the drive screw is tightened to a predetermined screw-in depth. When the lower end of the valve stem is pushed up, the auxiliary valve and valve stem cooperate to raise the stop valve. Wherein the moving the closed position of the conduction port.

  According to the invention of claim 1, since it is a simple structure in which the auxiliary valve, the stop valve, and the valve stem are accommodated in one valve housing, the valve mechanism can be reduced in size and weight, Since the number of parts is reduced, the cost can be reduced.

  Further, the auxiliary valve moves downward by the compressed air whose pressure is increased when the striking piston is driven, and the compressed air is kept in a further moved state, so that it is not released to the atmosphere. Therefore, all the compressed air is consumed to rotate the air motor until the valve stem is pushed up and the stop valve is activated. Thus, since the compressed air is not consumed unnecessarily, its consumption efficiency is greatly improved.

  FIG. 1 is a longitudinal sectional view of a screw driving machine. This screw driving machine includes an impact mechanism and a screw tightening mechanism inside the tool body A. The striking mechanism includes a striking cylinder 1, a striking piston 2 slidably provided in the striking cylinder 1, and a driver bit 3 integrally coupled to the striking piston 2. The main valve 4 is operated to open, and compressed air is supplied into the striking cylinder 1 from an air chamber (connected to an air supply source) 5 for storing compressed air, and the driver bit 3 is driven to operate. The screw tightening mechanism (not shown) is for tightening the driver bit 3 by the power of the air motor 6. The main valve 4 is opened and operated almost simultaneously with the start of the operation of the impact mechanism. A part of the compressed air flowing in from is supplied to the air motor 6 to rotate the driver bit 3 around its axis, thereby tightening the driving screw driven by the driver bit 3. The hitting mechanism and the screw tightening mechanism described above are well-known mechanisms according to Japanese Patent Laid-Open No. 2001-353671.

  In the screw driving machine, a contact arm 10 is slidably disposed along a nose portion 8 for injecting the driving screw 7 as a safety device. The contact arm 10 is urged so that the tip protrudes in the driving direction, and a part 10a of the other end is located in the vicinity of the trigger 19, and the trigger 19 can be operated only when the tip is pressed against the driven material. It is configured to be effective. Further, the contact arm 10 is configured to be temporarily engaged with and locked to a contact stopper (not shown) at the time of pressing, and can project again in the driving direction by operating the impact mechanism and moving the contact stopper. ing.

  By the way, there is provided a stop control mechanism for controlling the air motor 6 to automatically stop after the driving screw 7 is tightened to a predetermined screwing depth by the screw tightening mechanism.

  The stop control mechanism of the air motor 6 is constituted by a valve mechanism provided between the air chamber 5 and the air motor 6, as shown in FIGS. That is, the valve housing 12 is provided in the middle of the air passage that leads from the air chamber 5 to the air motor 6. An opening 13 is formed at the upper end of the valve housing 12 so as to open to an air passage P1 communicating with the air chamber 5. In addition, a conduction port 14 that opens to an air passage P <b> 2 that communicates with the air motor 6 is formed in the side wall of the valve housing 12. A short cylindrical hole 15 that opens to the atmosphere is also formed in the lower portion of the valve housing 12.

  Inside the valve housing 12, a cylindrical auxiliary valve 16 is disposed on the upper part so as to be movable up and down. A communication hole is formed in the upper and lower portions of the side wall of the portion where the auxiliary valve 16 is disposed. The upper communication hole 17 communicates with a timer chamber 20 that is pressurized when the striking piston 2 is driven. The timer chamber 20 is normally called a blowback chamber for returning the striking piston 2 driven downward to return upward, and when the striking piston 2 is driven to the bottom dead center, a through-hole at the bottom of the striking cylinder 1 is used. 9 is a chamber that receives supply of compressed air from 9. There is no need for a special chamber as shown in the above-mentioned Patent Document 1 as a timer chamber.

  On the other hand, the lower communication hole 18 is electrically connected to the atmosphere. The auxiliary valve 16 is normally urged upward by the air pressure supplied from the air chamber 5 into the valve housing 12 and is in the raised position, and the upper communication with the compressed air that has been increased when the striking piston 2 is driven. When compressed air is supplied from the hole 17 to the valve upper chamber 21, it moves downward due to the pressure difference between the upper and lower surfaces, and when the air pressure from the air chamber 5 is reduced, the pressure difference is reversed again, so that it moves up.

  The lower communication hole 18 is merely for adjusting the air pressure that changes when the auxiliary valve 16 moves up and down. Therefore, the compressed air supplied from the timer chamber 20 to the valve upper chamber 21 remains in the valve upper chamber 21 and is not exhausted to the atmosphere.

  Next, a cylindrical stop valve 22 that can open and close the conduction port 14 is arranged below the auxiliary valve 16 on the same axis so as to be movable up and down. O-rings 23 and 24 are respectively attached to the upper and lower portions of the stop valve 22, and the upper O-ring 23 comes into contact with and separates from the inner surface of the throttle portion 25 of the stop valve 22 formed above the conduction port 14. The opening 14 is configured to open and close. A plurality of notches 26 are formed on the upper end surface of the stop valve 22 so that the compressed air passage is not blocked when the lower end of the auxiliary valve 16 abuts. Further, the stop valve 22 is biased so as to always move upward by the spring 27 and open the conduction port 14.

  A valve stem 28 is accommodated in the stop valve 22 so as to be movable up and down. The central portion of the valve stem 28 is larger than the upper and lower end portions, and O-rings 30 and 31 are also attached to the upper and lower portions of the large diameter portion. The lower portion 32 of the valve stem 28 can protrude downward from the cylindrical hole 15 at the lower portion of the valve housing 12 and is normally moved downward by a spring 33 provided between the stop valve 22 and the lower portion. Is urged so as to protrude below the valve housing 12.

  Next, a holding member 34 having an edged flange 34b is disposed on the cylindrical portion 34a at the lower portion of the valve housing 12, and a pushing member 36 is held on the cylindrical portion 34a of the holding member 34 so as to be movable up and down. 35 is always urged downward. The pushing member 36 is arranged to be able to engage with a part of the contact arm 10. The contact arm 10 is locked by the contact arm stopper when pressed against the material to be driven, but when the impact mechanism is activated, the lock is released, and the contact arm 10 moves integrally with the drive screw. The other part 10 b of the contact arm 10 is engaged with the pushing member 36 immediately before the driving screw 7 reaches a predetermined screwing depth, and the pushing member 36 pushes up the valve stem 28.

  In the above configuration, normally, as shown in FIG. 3, compressed air is supplied from the air chamber 5, and the auxiliary valve 16 is at the upper end position by the air pressure. Since a gap is formed between the stop valve 22 and the valve stem 28, the compressed air is supplied to the valve lower chamber 37 from this gap. Due to the air pressure and the spring force of the spring 33, the stop valve 22 is in the upper end position (position where it engages with the lower end of the auxiliary valve 16). The lower end of the valve stem 28 protrudes below the valve housing 12. Thereby, the stop valve 22 electrically connects the passage P1 that communicates with the air chamber 5 and the passage P2 that communicates with the air motor 6.

  Next, the operation mode of the stop control mechanism of the air motor 6 will be described. When the contact arm 10 is pressed against the material to be driven and the trigger 19 is pulled, the main valve 4 is opened and the striking mechanism is actuated to drive the striking piston 2, so that it is compressed by the striking piston 2 and supplied from the striking cylinder 1. The compressed air is stored in the timer chamber 20 and further supplied into the upper chamber 21 of the auxiliary valve 16 from the upper communication hole 17 of the valve housing 12 as shown in FIG. 4, and the auxiliary valve 16 moves downward. Press down the stop valve 22. When the stop valve 22 is pushed down, the valve stem 28 enters relatively deeper into the stop valve 22, so that the upper O-ring 30 comes into contact with the inner surface of the stop valve 22 and the valve lower chamber 37 is sealed.

  Next, the air motor 6 is operated almost simultaneously with the operation of the striking mechanism, and the driving screw 7 is tightened. When the driving screw 7 is tightened in the driven material, the contact arm 10 moves relatively upward and engages with the pressing member 36, so that the pressing member 36 is also pushed up, and the driving screw 7 is moved. When tightened to a predetermined screwing depth, the pushing member 36 pushes up the valve stem 28 of the stop valve 22 to the upper end as shown in FIG. As a result, the lower O-ring 31 of the valve stem 28 is disengaged from the upper edge of the cylindrical hole 15, so that the compressed air supplied to the valve lower chamber 37 is discharged to the outside from the gap between the cylindrical hole 15 and the valve stem 28. Is done. For this reason, since the valve lower chamber 37 is depressurized, the stop valve 22 moves downward against the spring 27 by the air pressure acting on the upper end surface thereof as shown in FIG. At the same time, the valve stem 28 also enters deeply into the stop valve 22, so that the upper O-ring 30 closes the inside of the stop valve 22. Then, the upper O-ring 23 of the stop valve 22 abuts against the inner surface of the throttle portion 25 of the valve housing 12 and closes. For this reason, since the conduction port 14 for the air motor 6 is closed, the air supply from the air passage P2 is stopped, and the air motor 6 is stopped.

  When the trigger 19 is released after the screw tightening operation is completed, the striking piston 2 returns to the original position, and the compressed air for the valve upper chamber 21 of the auxiliary valve 16 also returns to the timer chamber 20 and is further exhausted. The auxiliary valve 16 returns to the upper end position. At substantially the same time, the pressing operation of the contact arm 10 is also released, so that the valve stem 28 is also moved downward and its lower O-ring 31 seals the tube hole 15, so that the compressed air in the air chamber 5 is again supplied to the stop valve 22. 2 is supplied to the valve lower chamber 37, and the stop valve 22 moves upward to reach the initial state of FIG.

  As described above, the auxiliary valve 16 and the valve stem 28 cooperate to move the stop valve 22 to the closed position of the conduction port 14.

  In the above-described embodiment, the air motor 6 is stopped in the order in which the auxiliary valve 16 first moves downward and then the valve stem 28 is pushed. On the other hand, FIG. Thus, it is conceivable that the auxiliary valve 16 moves downward after the contact arm 10 and the pushing member 36 first move upward and the valve stem 28 is pushed upward. In this case, since the valve stem 28 does not seal the inside of the stop valve 22, the compressed air from the air chamber 5 is discharged from the cylinder hole 15 to the atmosphere through the inside of the stop valve 22 and the valve lower chamber 37. However, when the auxiliary valve 16 moves downward and pushes down the stop valve 22, the valve stem 28 seals the inside of the stop valve 22, so that the state shown in FIG. 6 is obtained, and the auxiliary valve 16, valve stem 28, Cooperate, the conduction port 14 is closed, and the air motor 6 stops.

  As described above, when the valve stem 28 is pushed ahead of the auxiliary valve 16, the compressed air in the air chamber 5 is directly released from the cylindrical hole 15. It is a phenomenon. Further, the valve stem 28 is pushed before the auxiliary valve 16 only when the contact arm 10 is suddenly pressed with a large force and is operated in an unusual manner. There is almost no need to worry about wasted consumption of compressed air.

  As described above, the stop control mechanism of the air motor 6 has a simple structure in which the auxiliary valve 16, the stop valve 22, and the valve stem 28 are accommodated in the valve housing 12. The mechanism can be reduced in size and weight, and the number of parts can be reduced, so that the cost can be reduced.

  Further, in the technique disclosed in the patent document, the compressed air from the timer chamber 20 is wasted to the atmosphere in the absence of input from the contact arm 10. The compressed air is used only to lower the auxiliary valve 16 and maintain the state thereof. After the screw tightening operation is finished, the contact arm 10 returns to the timer chamber 20 so that the contact arm 10 There is no release to the atmosphere until the valve stem 28 is pushed up. Therefore, even if it takes time for the stop valve 22 stem to operate, such as when the material to be driven is hard, the compressed air that operates the auxiliary valve 16 remains in the valve upper chamber 21 and the atmosphere. In the meantime, all the compressed air is expended to rotate the air motor 6. Thus, since the compressed air is not consumed unnecessarily, the consumption efficiency is greatly improved.

  In addition, although the valve housing 12 is arrange | positioned up and down, the structure arrange | positioned beside may be sufficient.

It is a longitudinal cross-sectional view of a screw driving machine. It is a longitudinal cross-sectional view of the stop control mechanism of an air motor. It is a longitudinal cross-sectional view of the said stop control mechanism in the state where the air motor is rotating. It is a longitudinal cross-sectional view of the said stop control mechanism when an auxiliary valve act | operates. It is a longitudinal cross-sectional view of the said stop control mechanism of the state by which the auxiliary valve act | operated and the valve stem was pushed up. It is a longitudinal cross-sectional view of the said stop control mechanism in the state which the stop valve closed the conduction | electrical_connection opening with respect to an air motor. It is a longitudinal cross-sectional view of the said stop control mechanism when a valve stem act | operates ahead of an auxiliary valve.

Explanation of symbols

2 Stroke piston 5 Air chamber 6 Air motor 12 Valve housing 14 Conducting port 16 Auxiliary valve 22 Stop valve 28 Valve stem

Claims (1)

A striking mechanism for supplying an air motor into the striking cylinder by compressed air stored in the air chamber and driving a driver bit integrally coupled to the striking piston inside the striking piston, and a screw for rotating the driver bit by the air motor. A pneumatic screw driving machine that controls the air motor to stop after the driver bit hits the driving screw by the driving mechanism and further tightens the driving screw by the screw tightening mechanism. In the air motor stop control mechanism in
A valve housing is provided between the air chamber and the air motor, an upper end of the valve housing is opened in the air chamber, a conduction port formed in a side wall of the valve housing is opened in the air motor,
A cylindrical auxiliary valve is arranged in the upper part inside the valve housing so as to be movable up and down, and the auxiliary valve is moved downward by compressed air whose pressure is increased when the impact piston is driven,
Under the auxiliary valve, a cylindrical stop valve that can open and close the conduction port is arranged to be movable up and down,
A valve stem is accommodated in the stop valve so as to be movable up and down, and a lower portion of the valve stem projects downward from an opening at a lower portion of the valve housing,
When the driving piston is driven, the auxiliary valve moves downward to push down the stop valve, and when the driving screw is tightened to a predetermined screwing depth and the lower end of the valve stem is pushed up, A stop control mechanism for an air motor in a pneumatic screw driving machine, wherein an auxiliary valve and a valve stem cooperate to move the stop valve to a closed position of the conduction port.

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