JP2001047377A - Pneumatic nailing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the nailing performance by decreasing the loss of the drive energy in a pneumatic nailing machine. SOLUTION: By a pilot operation selector valve 20 of spring offset type, the back face side air chamber of a piston 18 in a pneumatic nailing machine 1 is connected alternatively with an air exhaust hole 25 in communication to the atmosphere or an air chamber 14, and the pilot port of the selector valve 20 is connected with the air chamber of a trigger valve 11. In standby or at starting of the piston, the selector valve is in the position having communication to the atmosphere, and the air on the back face of the piston is exhausted to the atmosphere at the time of nailing. When a trigger lever in On condition is released, the selector valve is turned to the air chamber connecting position by the pilot pressure, and the piston is returned to the standby position by the air pressure in the air chamber. Then the selector valve 20 is returned to the position having communication to the atmosphere through a throttle hole in a slide spool 22 by the action of a spring, and the standby condition for nailing is established.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic nailing machine, and more particularly, to a pneumatic nailing machine in which energy loss is reduced to improve nailing performance.

[0002]

2. Description of the Related Art In a conventional pneumatic nailer, a blowback chamber is formed around a pneumatic cylinder, and air on the lower surface side of the piston is generated when the piston descends in the pneumatic cylinder. When the trigger valve is turned off after nailing, the piston is raised to the standby position by the compressed air stored in the blowback chamber.

Therefore, there is a problem that the back pressure of the piston at the time of nailing is high and the energy of nailing is greatly lost. Also, the air supply amount to the blowback chamber changes according to the on-time of the trigger valve, and the blowback chamber is set so that the piston can return to the standby position even when the trigger lever is pulled back to the off position instantaneously. Since the capacity is relatively large, there is a problem that the air consumption per stroke is large.

[0004] Therefore, there is a technical problem to be solved in order to reduce the driving resistance of the piston to reduce the loss of nailing energy and to reduce the air consumption to improve the driving efficiency. An object of the present invention is to solve the above problems.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above object, and is a pneumatic nailing machine which controls the activation of a pneumatic cylinder by pilot-operating a head valve of a pneumatic cylinder with a trigger valve. , A spring-offset pilot-operated switching valve for selectively connecting a rear-side air chamber of a piston of a pneumatic cylinder to an exhaust port communicating with the atmosphere or an air chamber of a pneumatic nailing machine; The port is connected to the air chamber of the trigger valve, and the switching valve is formed so as to be switchable from the atmosphere communication position to the air chamber connection position by the pilot pressure supplied to the switching valve through the air chamber of the trigger valve. The air chambers before and after the body are communicated via the throttle, and the air supplied when the trigger valve is turned off is released. The switching valve is switched from the atmospheric communication position to the air chamber connection position by the lot pressure, and the piston of the pneumatic cylinder is returned to the standby position by the pressurized air in the air chamber. Is configured to return to the atmospheric communication position.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a pneumatic nailer 1,
A grip 3 extends at a right angle from a side surface of the cylinder housing 2, and a nose block 4 is coupled to a tip (lower in FIG. 1) of the cylinder housing 2. The nail magazine 5 connected to the back of the nose block 4 has its rear end connected to the end of the grip 3 and is supported by the grip 3.

The nose block 4 is equipped with a nail feed claw 6 which is driven backward and forward by a nail feed piston (not shown) arranged on the back surface in FIG. Nose block 4
To the driver guide hole 4a.

A contact arm 7 projecting beyond the tip of the nose block 4 extends in the direction of the trigger lever 8 through the back surface of the nose block 4 in FIG. Of the free arm 9.

The contact arm 7 has a compression coil spring 10
When the distal end of the contact arm 7 is pressed against the object to be driven and pushed toward the nose block 4, the distal end of the free arm 9 is pushed up in the direction of the trigger valve 11. When the trigger lever 8 is pulled in this state, the fulcrum of the free arm 9 moves to the trigger valve 11 side, the trigger valve stem 12 is pushed, and the pneumatic cylinder 13 is activated.
That is, there is a safety mechanism in which the pneumatic cylinder 13 is activated by two operations of pressing the tip of the contact arm 7 against the object to be driven and pulling the trigger lever 8, and the pneumatic cylinder 13 is not activated by only one of the operations. It is configured.

The pneumatic cylinder 13 is disposed at the center in the cylinder housing 2, and the space around the pneumatic cylinder 13 and the space in the grip 3 form an air chamber 14 for compressed air.
It has become. A head valve 15 is disposed above the pneumatic cylinder 13, and the head valve 15 is urged by a compression coil spring 16 to contact a valve seat 17 on the upper edge of the pneumatic cylinder 13, and the air chamber 14 and the piston 18 of the pneumatic cylinder 13 The upper air chamber is shut off.

The pneumatic cylinder 13 has a ventilation hole 13a formed in the vicinity of its lower end. The outer peripheral surface of the ventilation hole 13a is surrounded by an annular ventilation pipe 19 having a C-shaped cross section.
A switching valve 20 for switching between intake and exhaust is provided on the front surface of the cylinder housing 2, and the rear side of the piston 18 of the pneumatic cylinder 13 through ventilation holes 19 a and 2 a formed in the front part of the annular ventilation pipe 19 and the front part of the cylinder housing 2. (Lower)
The air chamber communicates with the switching valve 20.

The switching valve 20 has a slide spool 22 built in a spool housing 21. The slide spool 22 has a large-diameter land 22a at the front and rear middle part, a small-diameter land 22b at the rear end, and a center hole 22c penetrating back and forth. Is provided, and a small-diameter throttle hole 22d penetrating back and forth is formed in the large-diameter land 22a.

The front of the slide spool 22 is inserted into and supported by a front bearing hole of the spool housing 21, and the slide spool 22 is offset to the retracted position by a compression coil spring 23 inserted into the spool chamber.

A valve seat 24 is provided at the front end of the spool housing 21, and an exhaust port 25 is formed around the valve seat 24. Further, the spool housing portion 21 is provided with pilot ports 26 and 27 which are branched into two portions at a rear portion of the spool chamber and a front portion thereof, and pressurized air in the air chamber 14 is supplied to the trigger valve 11.
Are supplied to pilot ports 26 and 27 through a pilot line 28 shown by a chain line.

When the slide spool 22 is at the retracted position as shown in FIG. 2, the pilot ports 26 and 27 communicate between the large-diameter land 22a and the small-diameter land 22b of the slide spool 22, and the pneumatic cylinder 13 The lower air chamber is provided in the center hole 2 of the slide spool 22 of the switching valve 20.
It communicates with the exhaust port 25 through 2c.

When the slide spool 22 is in the forward position as shown in FIG. 3, the front end of the slide spool 22 contacts the valve seat 24 to close the center hole 22c, and the lower air chamber of the pneumatic cylinder 13 is closed. It communicates with the air chamber 14 through the rear pilot port 27.

Next, the operation of the pneumatic nailing machine 1 will be described. When one end of the air hose is connected to an air compressor and the other end is connected to an air plug (not shown) attached to the end of the grip 3 of the pneumatic nailer 1, the air chamber 14
Is filled with high-pressure air, and the trigger valve 11 shown in FIG.
Air is supplied from the air chamber to the upper surface of the head valve 15 of the pneumatic cylinder 13 through the pilot line 2b in the cylinder housing 2, and the head valve 15 presses against the valve seat 17 due to the difference in pressure receiving area between the upper and lower surfaces. The chamber 14 and the upper air chamber of the pneumatic cylinder 13 are shut off.

The air supplied from the air chamber of the trigger valve 11 to the pilot ports 26 and 27 of the switching valve 20 through the pilot line 28 is supplied to the slide spool 22.
And enters the groove between the large-diameter land 22a and the small-diameter land 22b, and is also supplied to the air chamber in front of the large-diameter land 22a through the throttle hole 22d of the large-diameter land 22a. 1 and 2 by a compression coil spring 23.
The air chamber on the rear side of the piston 18 of the pneumatic cylinder 12 communicates with the atmosphere through the switching valve 20.

When the tip of the contact arm 7 is pressed against the object to be driven and the trigger lever 8 is pulled, the stem 12 of the trigger valve 11 is pushed in, the compressed air on the lower surface of the trigger valve spool 12a is exhausted, and the trigger valve spool 12a is released. Descend. Thereby, the pressurized air acting on the upper surface of the head valve 15 of the pneumatic cylinder 13 is exhausted through the pilot pipe 2a and the trigger valve 11 in the cylinder housing 2, and the air chamber 1
Due to the air pressure of 4, the head valve 15 rises, high-pressure air flows from the air chamber 14 into the upper air chamber of the pneumatic cylinder 13, and the piston 18 and the driver 18a are activated. At the same time, the pressure air in the spool chamber of the switching valve 20 is also exhausted through the trigger valve 11, but the slide spool 22 is maintained at the retracted position by the compression coil spring 23.

When the piston 18 descends in the pneumatic cylinder 13, air on the back side of the piston 18 is supplied to the switching valve 20.
, The driving energy is lost very little due to the back pressure of the piston 18, and nailing is performed with high energy efficiency.

When the trigger operation is released after nailing, the trigger valve 11 returns to the initial state of FIG.
4, pressurized air is supplied to the upper surface of the head valve 15 through the trigger valve 11 and the pilot line 2a, and the head valve 15 descends. At the same time, pressurized air is supplied from the trigger valve 11 to the pilot ports 26 and 27 of the switching valve 20, and the air pressure acting on the back surface of the large-diameter land 22 a of the slide spool 22 overcomes the spring force of the compression coil spring 23 and As shown in FIG. 3, the cylinder 22 moves forward and presses against the front valve seat 24 to stop the exhaust from the lower air chamber of the pneumatic cylinder 13, and communicate the lower air chamber with the pilot port 27. Thereby, the pressurized air in the air chamber 14 is supplied to the lower air chamber of the pneumatic cylinder 13 through the switching valve 20, and the piston 18 rises and returns to the standby position.

During this time, in the switching valve 20, the compressed air flows through the throttle hole 22d of the large-diameter land 22a.
a, the difference in air pressure between the front and rear surfaces of the large-diameter land 22a decreases, and after a certain time, the slide spool 22 retreats due to the spring force of the compression coil spring 23, and the retreat position shown in FIG. Return to. The time required for the slide spool 22 once advanced by the release of the trigger operation to start retreating is determined by the diameter of the throttle hole 22d and the spring force of the compression coil spring 23, and is set to be equal to or longer than the return stroke time of the piston 18. Thereby, the piston 18
After returning to the standby position, the air pressure in the lower air chamber of the pneumatic cylinder 13 becomes the atmospheric pressure, and the nailing standby state is established.

The present invention is not limited to the above embodiment, and various modifications are possible within the technical scope of the present invention, and it is natural that the present invention extends to those modifications. is there.

[0024]

As described above, in the pneumatic nailing machine of the present invention, when the piston is driven by the switching valve, the air chamber behind the piston is communicated with the atmosphere, and after nailing, the air chamber is returned to the air chamber behind the piston. The piston is returned to the atmospheric position by supplying high-pressure air from the air, so unlike conventional pneumatic nailers that store air in the blowback chamber, energy loss due to the back pressure of the piston during nailing is small. In addition, the nailing performance is improved and the air consumption is reduced, and the driving efficiency is remarkably improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a pneumatic nailer according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a switching valve of the pneumatic nailer in FIG. 1 in a standby state.

FIG. 3 is a cross-sectional view showing a switching valve of the pneumatic nailing machine of FIG. 1 in a state where a trigger is released.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pneumatic nailing machine 11 Trigger valve 13 Pneumatic cylinder 13a Vent hole 14 Air chamber 18 Piston 19 Annular vent pipe 20 Switching valve 22 Slide spool 22c Center hole 22d Restriction hole 23 Compression coil spring 24 Valve seat 25 Exhaust port 26, 27 Pilot port 28 Pilot pipeline

Claims (1)

[Claims] 1. A pneumatic nailing machine in which the head valve of a pneumatic cylinder is pilot-operated by a trigger valve to control the activation of the pneumatic cylinder, wherein an exhaust port or pneumatic pressure which communicates the air chamber on the back side of the piston of the pneumatic cylinder with the atmosphere. A spring-offset pilot-operated switching valve for selectively connecting to an air chamber of the nailing machine; a pilot port of the switching valve connected to an air chamber of a trigger valve; and a supply to the switching valve through the air chamber of the trigger valve. The switching valve is formed so that it can be switched from the atmosphere communication position to the air chamber connection position by the pilot pressure, and the air chambers before and after the valve body of the switching valve are communicated via the throttle to release the trigger valve ON operation. The switching valve switches from the air communication position to the air chamber connection position due to the pilot pressure supplied when The piston of the pneumatic cylinder is returned to the standby position by the pressurized air in the air chamber, and the switching valve is returned to the atmospheric communication position after a certain period of time by the action of the throttle and the spring. Hammer.