JP2002264032A - Device for automatically stopping screw driving machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop an air motor only after finishing a predetermined screwing. SOLUTION: In an air passage 41 formed in a pneumatic cylinder, a valve chamber 47 for operating an exhaust valve 35 to open/close a pilot air chamber 23a to atmosphere is formed and in the valve chamber 47, an exhaust port for exhausting compressed air inside the air passage 41 to atmosphere is formed. The exhaust port is opened/closed operatively associated with a vertical move of a contact arm 18 and a timer chamber 50 is formed on an upstream side of the valve chamber 47. When a piston reaches the vicinity of bottom dead center and the compressed air flows in the valve chamber 47 from the air passage 41 via the timer chamber 50 and additionally the exhaust port 46 is closed operatively associated with operation of the contact arm 18, the exhaust valve 35 is operated by pressure increase inside the valve chamber 47 to exhaust the compressed air in the pilot air chamber 23a of a stop valve 22 and thereby to close the stop valve 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a driving screw in a floating state with respect to a target member by a screw driving machine and then rotating and tightening the screw until a predetermined screwing depth is reached. The present invention relates to an automatic stop device for a screw driving machine that is not stopped.

[0002]

2. Description of the Related Art Generally, in a screw driving machine, a screw driving machine is pressed against a member to be screwed in, and the driving screw is lifted from the surface of the target member by a driver bit integrally connected to an actuated piston by pulling a trigger lever. A mechanism in which the driver bit is driven by an air motor and the screw is lifted by pressing the screw driving machine further toward the target member when the stopper holding the screw driving machine comes off, and then the screw is lifted. Has been adopted. A stop valve that operates to shut off the supply of compressed air to the air motor when the screw driving machine is pressed to the stroke end, and an exhaust valve that operates when the piston reaches the bottom dead center. The structure is such that the rotation of the air motor is automatically stopped by cooperation to control the tightening depth stably.

[0003] Such an automatic stop device is known from Japanese Patent Application Laid-Open No. 2000-326248.
This is because, as shown in FIGS. 3 to 8 of the publication, when the piston 10 reaches the stroke end, the screwing of the contact arm 18 is completed, and the exhaust hole 46 for exhausting the compressed air acting on the back surface of the piston 10 is formed. Sub-open / close valve (exhaust valve) with compressed air when closed
35 is operated to exhaust the compressed air in the pilot air chamber 23a of the open / close valve (stop valve) 22, thereby closing the open / close valve 22 and thereby stopping the rotation of the air motor.

[0004]

However, in an actual use mode, before the screwing is completed (in a state where the screw is floating), as shown in FIG. 10 (a diagram schematically showing the screw driving machine). Press down the nose part strongly to remove the target member 5
It may be pushed to 1. In this case, since the piston 10 is pushed into the cylinder 8 together with the driver bit 11, the piston 1 once reaches the bottom dead center.
0 rises again. In addition, since the lower end of the contact arm 18 also contacts the target member 51, the upper end thereof rises relatively to the screw driving machine main body and closes the exhaust hole 46.
Even if the piston 10 rises again, the compressed air has already flowed into the air chamber 47 from the air passage.
Is increasing pressure. In this state, the contact arm 18
When the air hole 46 is closed, the compressed air in the pilot air chamber 23a is exhausted, so that the open / close valve 22 is operated, the supply of the compressed air to the air motor is stopped, and the air motor stops. In other words, the rotation of the air motor stops while the piston 10 is floating above the bottom dead center, so that the driving screw 32 also floats from the surface of the target member 51, resulting in a screw floating state.

[0005] The present invention solves the above-mentioned problems and prevents the air motor from stopping even if the piston is pushed into the screw driving machine body by strongly pressing the screw driving machine against the object before screwing is completed. It is an object of the present invention to provide an automatic stopping device for a screw driving machine that can effectively prevent the air motor from stopping after a predetermined screw tightening is completed.

[0006]

In order to solve the above-mentioned problems, an automatic stop device for a screw driving machine according to the present invention comprises a driver bit having a bit engaged with the head of a driving screw at a tip end of a pneumatic cylinder. A screw that is rotatably coupled to a piston, operatively connects the driver bit to an air motor, drives a piston of a pneumatic cylinder, drives a driving screw by a driver bit, and drives a driver bit to rotate by an air motor to screw the driving screw. A driving machine, a pilot-operated stop valve is provided in the compressed air supply path to the air motor, and a contact arm slidable along the nose of the screw driving machine is arranged so as to protrude from the tip of the nose,
In the automatic stop device of the screw driving machine configured to stop the air motor by closing the stop valve by the upward movement of the contact arm pushed into the screw driving machine main body with the progress of screwing, the stop valve includes: A pilot air chamber is provided for closing the stop valve by the pushing operation by the upward movement of the contact arm and the communication with the atmosphere, and the pneumatic cylinder acts on the rear surface of the piston when the piston reaches near the bottom dead center. An air passage for discharging compressed air is provided.In this air passage, a valve chamber for operating an exhaust valve for opening and closing the pilot air chamber with respect to the atmosphere is formed. An exhaust hole for discharging compressed air to the atmosphere is formed, and this exhaust hole is opened and closed in conjunction with the vertical movement of the contact arm. It causes the movement, on the upstream side of the valve chamber of the air passage forms a timer chamber,
When the piston reaches the vicinity of the bottom dead center and compressed air flows from the air passage through the timer chamber into the valve chamber, and the exhaust hole is closed in conjunction with the operation of the contact arm, the valve chamber is closed. The exhaust valve is actuated by the pressure increase, and the stop valve is closed and actuated by exhausting the compressed air in the pilot air chamber of the stop valve.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIG. FIG. 1 shows a screw driving machine 1 in which a pneumatic cylinder 3 and an air motor 4 are accommodated in a housing 2, and a trigger valve 7 in a grip 5 is operated by a trigger lever 6 arranged in front of a grip portion 5 of the housing 2. Open and close. The inside of the grip 5 is an air chamber 8. An air hose is connected to an air hose connector 9 attached to the bottom of the grip 5 to supply compressed air from the air compressor to the air chamber 8.

The outer peripheral surface of the driver pit 11 connected to the piston 10 of the pneumatic cylinder 3 is formed with a spline groove, and a driver is inserted into a spline groove hole at the center of the gear 12 mounted in the front part of the housing 2. Bit 11 is inserted, piston 10 and driver bit 1
1 is slidable with respect to the guide member 12. The power of the air motor 4 that rotationally drives the driver bit 11 is transmitted to the final gear 12 via a plurality of reduction gears 13 arranged at the front of the housing 2.

The screw feeder 15 provided on the side surface of the nose portion 14 is constituted by a pneumatic cylinder and a ratchet type feed claw which are not shown in the drawing, similarly to a general pneumatic nailer.
The connection type screws stored in the screw magazine 16 are sequentially supplied into the nose portion 14.

A swingable free arm 17 is attached to the trigger lever 6. A contact arm 18 facing the front of the free arm 17 passes through the back of the pneumatic cylinder 3 in FIG. And protrudes from the nose portion 14 in the screw injection direction. A screw guide 19 at the front end of a contact arm 18 that can slide back and forth.
A pivotable chuck 20 is pivotally mounted on the
Is closed by a spring (not shown).

When the screw arm 19 is pressed against a target member such as a building material and the contact arm 18 is pushed in, the contact arm 18 comes into contact with the distal end of the free arm 17. The stem of the trigger valve 7 is pushed via the arm 17 to switch the trigger valve 7, and a known accidental fire prevention mechanism is configured in which the pneumatic cylinder 3 and the air motor 4 are not activated by operating only the trigger lever 6.

An automatic stop device 21 composed of two stop valves for opening and closing an air supply path to the air motor 4 is provided on a side surface portion of the housing 2 shown in FIG. 2 (the back surface of the pneumatic cylinder 3 in FIG. 1). Built-in.

Next, referring to FIG. 3 to FIG.
1 will be described. Note that, in the same figure, the right from the center line is a vertical cross section of the screw pit as in FIG. 1, and the left from the center line is a horizontal cross section.

FIG. 3 shows the automatic stop device 21 in a standby state. The stop valve 22 of the automatic stop device 21 has a cylindrical main stem 24 inserted into a valve sleeve portion 23.
And a small-diameter pilot stem 25 inserted below the main stem 24. An O-ring 26 is mounted around the main stem 24.

The main stem 24 is in the raised position by the bias of the compression spring 27, and as shown in FIG.
The upper port 3 has an inlet port 28 and an outlet port 29 which are always in communication. The pilot stem 25 is the main stem 2
The lower pent port 31 of the valve sleeve portion 23 is closed by being urged downward by the compression spring 30 inserted into the inside 4. A valve body 33 having a shutter 45 is attached to a lower end portion of the pilot subtle 25 and faces an upper end of the effect 18. The compressed air in the air chamber 8 is supplied to the pilot air chamber 23a on the lower surface of the main stem 24 through the inside of the main stem 24.

The inlet port 2 above the stop valve 22
8 is connected to the air chamber 8, and the outlet port 29 is connected to the air motor 4.

The exhaust valve 3 is arranged in parallel with the stop valve 22.
5 are arranged. The exhaust valve 35 is provided with a valve stem 37 that is slidable in a valve sleeve portion 36, and the valve stem 37 is urged downward by a compression spring 38 to constantly shut off the vent ports 31 and 40 of the stop valve 22. I have.

The pneumatic cylinder 3 has an air passage 41 for discharging compressed air acting on the back surface of the piston 10 when the piston 10 reaches the vicinity of the bottom dead center. One end of the air passage 41 faces the opening port 3b,
At the other end, a valve chamber 47 for operating an exhaust valve 35 for opening and closing the pilot air chamber 23a to the atmosphere is formed, and an exhaust hole 46 is formed in the valve chamber 47.

The exhaust hole 46 is configured to open and close in conjunction with the vertical movement of the contact arm 18.
That is, the L-shaped shutter 45 is formed so as to open and close the exhaust hole 46 in conjunction with the vertical movement of the contact arm 18.

The vent port 31 of the stop valve 22 is connected to the exhaust valve 35. When the exhaust valve 35 is opened, the pilot air chamber 23a on the lower surface of the main stem 24 of the stop valve 22 vents through the vent port 31. The port 40 communicates with the atmosphere.

A timer chamber 50 is formed upstream of the valve chamber 47 in the air passage 41. The timer chamber 50 stores the compressed air flowing into the air passage 41 from the opening port 3b into the air passage 41 for a short time when the piston 10 reaches the vicinity of the bottom dead center, and flows into the valve chamber 47 until the pressure increases. Is to delay the time. Therefore, the operation of the exhaust valve 35 is also delayed.

Next, the operation of the screw driving machine will be described.
The tip of the screw guide 19 shown in FIG.
1 until the contact arm 18 comes into contact with a contact arm stopper (not shown) and the trigger lever 6 is actuated.
Opens, and the head valve 4 of the pneumatic cylinder 3 shown in FIG.
2, the compressed air flows into the pneumatic cylinder 3 from the air chamber 8 on the outer periphery of the pneumatic cylinder 3, and the piston 10 and the driver pit 11 descend as shown in FIG. 32, the air motor 4 drives the driver bit 11 to rotate, and the piston 10 moves to near the bottom dead center.

When the driving screw 32 is driven into the object 51 to be driven, the lock of the contact arm 18 by the contact arm stopper 43 is released as shown in FIG. 5, and the driving screw 32 is further driven by the air motor 4. As the screw 32 is screwed in, the piston 10 moves toward the bottom dead center, and the screwing machine approaches the screwing target 51 so that the contact arm 18 is moved.
Is further pushed into the screw driving machine body.

The piston 10 is connected to the pneumatic cylinder 3
, The compressed air in the pneumatic cylinder 3 flows into the air passage 41. Then, it flows into the valve chamber 47 via the timer chamber 50. But,
This compressed air is discharged to the atmosphere from the exhaust hole 46 as shown in FIG.

At the end of the screwing, the contact arm 18 pushes up the valve body 33 to slide the pilot stem 25 of the stop valve 22 upward as shown in FIG. When the pilot stem 25 moves upward, the pilot air chamber 23a on the lower surface of the main stem 24 and the vent port 31 are opened. Then, when the screw driving machine is pushed to the stroke end, the contact arm 18 pushes up the pilot stem 25 of the stop valve 22, and at the same time, the L-shaped valve element 45 closes the exhaust hole 46 of the exhaust valve 35. As a result, the compressed air in which the atmosphere is also dripped is filled in the valve chamber 47 and the pressure increases, pushing up the stem 37 of the exhaust valve 35 as shown in FIG. Is communicated from the vent port 31 to the atmosphere via the vent port 40. Therefore, the main stem 2
Pilot pressure acting on the lower surface of the vent port 3
1 to the atmosphere through the vent port 40 through the exhaust valve 35. As a result, the pressure acting on the upper and lower surfaces of the main stem 24 causes a difference, and the main stem 24 descends, and the inlet port 28 and the outlet port 29 are shut off by the O-ring 26 at the uppermost portion. Is cut off and the air motor 4 stops.

When the screwing machine 1 is lifted from the screwing target 51 after the air motor 4 stops, the contact arm 18 descends and separates from the pilot stem 25.
As shown in FIG. 4, the L-shaped valve body 45 opens the exhaust hole 46, and the compressed air in the valve chamber 47 is discharged again. Therefore, the stem 37 of the exhaust valve 35 returns to the initial position, and Is drained to the atmosphere, and the vent ports 31 and 40 are shut off. When the pilot stem 25 descends, the pilot air chamber 23a and the vent port 31 are shut off, and at the same time, the air chamber 8 communicates with the pilot air chamber 23a to supply compressed air from the inlet port 28 to the pilot air chamber 23a. Then, the main stem 24 floats and returns to the initial position.

When the operation of the trigger lever 6 is released, the trigger valve 7 is closed and the head valve 42 is lowered to return to the initial position shown in FIG. The pressure rises and returns to the initial position due to the pressure of the formed blowback chamber 44. Then, when the piston 10 rises from the bottom dead center and passes through the opening port 3b in the pneumatic cylinder 3, the pressure supply from the inside of the pneumatic cylinder 3 to the air passage 41 of the exhaust valve 35 is cut off.

Next, immediately after the piston 10 reaches the bottom dead center, when the head of the driving screw 32 is still slightly floating from the object 51, the screw driving machine is applied to the object 51 with a large force. In the case of a sudden press, as shown in FIG.
4 and the piston 10 rises again. Further, the upper end of the contact arm 18 also rises relatively to the screw driving machine main body, and the valve body 45 closes the exhaust hole 46.

By the way, even if the piston 10 rises again, the compressed air has already flowed into the air passage 41. But,
Even if the compressed air flows into the air passage 41, the pressure in the valve chamber 47 does not immediately increase. The compressed air is temporarily stored in the timer chamber 50 and then supplied to the valve chamber 47. Therefore, the pressure rise in the valve chamber 47 is delayed, so that even if the exhaust hole 46 is closed,
The exhaust valve 35 does not operate, and the stop valve 22 does not operate. During that time, the air motor 4 continues to rotate without stopping, so that the driving screw 32 in the floating state is sufficiently screwed into the object 51. When the driving screw 32 is sufficiently tightened, as shown in FIG. 8, the pressure in the valve chamber 47 is increased by the compressed air sent from the timer chamber 50, and the exhaust valve 35 is operated. O
The ring 48 closes the exhaust hole 46 and exhausts the compressed air in the pilot air chamber 23a of the stop valve, thereby closing and operating the stop valve 23.
As a result, the pilot air chamber 23a is exhausted, the main stem 24 of the stop valve 22 moves down, and the stop valve 22 also operates, so that the air motor 4 stops.

As described above, even if the piston 10 is pushed into the body of the screw driving machine by strongly pressing the screw driving machine against the object 51 at the time of screwing,
The stop of the air motor 4 can be delayed by the time chamber, and the air motor can be stopped only when predetermined screw tightening is completed during that time.

As shown in FIG. 3, a passage 52 is formed in the timer chamber 50 in addition to the passage 41. The passage 52 communicates with a piston return chamber via a check valve 53, and is connected to the timer chamber 50.
The compressed air stored in the cylinder is used for returning the piston. This makes it possible to reduce the size of the tool as compared with a case where the return chamber and the timer chamber are separately formed. In other words, by using a part of the chamber for returning the piston as a timer chamber, it is not necessary to separately form a timer chamber. When the timer chamber 50 is used as a timer, the check valve 53 compresses the return chamber. Prevents air from entering.

[Brief description of the drawings]

FIG. 1 is a sectional view of a screw driving machine.

FIG. 2 is a side view of the screw driving machine.

FIG. 3 is a partial cross-sectional view showing an automatic stop device by simplifying the screw driving machine.

4 is a partial cross-sectional view of the screw driving machine showing a state in which an exhaust valve shown in FIG. 3 is opened.

FIG. 5 is a partial cross-sectional view when driving a screw;

FIG. 6 is an enlarged view of a part of FIG.

FIG. 7 is a partial cross-sectional view of the screw driving machine showing a state where the stop valve and the exhaust valve shown in FIG. 3 are open.

FIG. 8 is a partial cross-sectional view of the screw driving machine in a state where the air motor stops after the screw tightening is completed.

FIG. 9 is a partial cross-sectional view of the screw driving machine in a state where the air motor stops immediately before screw tightening is completed.

FIG. 10 is a partial cross-sectional view showing a state where the screw driving machine is pressed by an excessive pressing force.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw driving machine 3 Pneumatic cylinder 4 Air motor 10 Piston 18 Contact arm 22 Stop valve 35 Exhaust valve 41 Air passage 46 Exhaust hole 47 Valve chamber 50 Timer chamber

Claims (1)

[Claims] A driver bit having a bit engaged with the head of a driving screw at the tip is rotatably coupled to a piston of a pneumatic cylinder, and the driver bit is operatively connected to an air motor to connect the piston of the pneumatic cylinder. A screw driving machine that drives and drives a driving screw with a driver bit, and rotationally drives the driver bit with an air motor to screw the driving screw. A pilot operated stop valve is provided in a compressed air supply path for the air motor, and the screw is driven. A contact arm that is slidable along the nose of the machine is arranged so as to protrude from the tip of the nose, and the stop valve is closed by upward movement of the contact arm that is pushed into the body of the screw driving machine as the screwing proceeds To stop the air motor. In the automatic stop device of a driving machine, the stop valve is provided with a pilot air chamber that closes the stop valve by a pushing operation by upward movement of the contact arm and a communication with the atmosphere, and a piston is provided in the pneumatic cylinder. An air passage for discharging compressed air acting on the back surface of the piston when the piston reaches the vicinity of the bottom dead center is provided. An exhaust hole for discharging the compressed air in the air passage to the atmosphere is formed in the valve chamber, and the exhaust hole is opened and closed in conjunction with the vertical movement of the contact arm, and the air passage of the air passage is formed. A timer chamber is formed upstream of the valve chamber, and the piston reaches the vicinity of the bottom dead center, and compressed air flows from the air passage through the timer. When the exhaust gas flows into the valve chamber through the chamber and the exhaust hole is closed in conjunction with the operation of the contact arm, the exhaust valve operates due to a pressure increase in the valve chamber, and the pilot air chamber of the stop valve is compressed. An automatic stop device for a screw driving machine, wherein the stop valve is closed and operated by exhausting air.