JPS5916911B2 - pneumatic impact tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic impact tool that uses air pressure as a driving source to drive a fastener such as a nail into a workpiece.

Conventionally, as an example of a pneumatic impact tool, there has been provided a impact piston integrally connected with a driver, a impact cylinder into which the impact piston is slidably and tightly fitted, a main air chamber connected to an air pressure source, and the impact piston. a return air chamber capable of applying return air pressure to the lower chamber side of the striking piston after reaching the bottom dead center, a first position communicating with the upper chamber of the striking piston of the striking cylinder and the main air chamber, and the atmosphere; The pneumatic nailing machine comprises a head valve that can select a second position communicating with the opening of the head valve, and a trigger valve for actuating the head valve.

To explain one impact cycle of the above-mentioned nail gun, first, when the valve stem of the trigger valve is pushed upward, the passage connecting the trigger valve chamber of the trigger valve and the main air chamber is opened by this valve stem. The pressurized air in the head valve piston upper chamber is discharged into the atmosphere through the trigger valve chamber.

Then, an opening signal is sent to the head valve, and the head valve piston of the head valve is pushed up from the second position to the first position by the pressurized air in the main air chamber, and the upper part of the percussion piston of the percussion cylinder is moved upward. is supplied with pressurized air.

As a result, the striking piston descends rapidly within the cylinder to drive the nail.

After the striking piston reaches the bottom dead center, the pressurized air supplied into the upper chamber of the striking piston is supplied into the return air chamber through a small hole formed in the striking cylinder.

When the push-up operation of the trigger valve stem is released, the valve stem returns to its original state, that is, the state before the push-up operation, and a close signal is sent to the head valve, which closes the connection between the upper chamber of the striking piston and the main air chamber. The upper chamber of the striking piston communicates with the atmosphere through the exhaust hole, and at the same time, the air in the return air chamber is supplied into the lower chamber of the striking piston through the hole, and the striking piston reaches the top dead center. The return process is completed.

Therefore, the operator must confirm that nail driving has been completed (the striking piston has reached the bottom dead center) and then release the push-up operation of the trigger valve stem.

Therefore, an operator who is accustomed to operating the above-mentioned nailing machine confirms the completion of the above-mentioned nail driving based on his experience and intuition gained from many years of work.
Currently, the push-up operation of the trigger valve stem is released.

Therefore, if the operator repeatedly pushes up and releases the trigger valve stem based on the above-mentioned intuition in order to quickly drive nails, the operation timing of the trigger valve stem, that is, the opening/closing signal to the - If the timings match exactly during one striking cycle, the nails will be driven in succession, but if the timing of the operations is out of order (for example, if the striking piston reaches the bottom dead center, the valve stem is (When the push-up operation is released and a close signal is sent to the head valve) Odor.

In this case, sufficient pressurized air is not stored in the return air chamber to return the striking piston to the top dead center, and the striking piston ends up stopping in the middle of the striking cylinder.

Then, the driver, which is integrally connected to the striking piston, stops within the nose into which the nails are successively fed, and the needle supply hole within the nose is closed.

In this state, when the trigger valve stem is pushed up, that is, an opening signal is sent to the head valve and the striking piston is lowered, the driver does not drive the nail and the striking piston is placed at the lower end of the striking cylinder. The bumper member is hit hard, resulting in premature wear of the bumper member.

Therefore, the present invention has been proposed to eliminate the above-mentioned conventional drawbacks, and provides a new pneumatic impact tool that can send appropriate opening/closing signals from a trigger valve to a head valve during one impact cycle. The purpose is to

Hereinafter, one embodiment of the present invention will be specifically described based on the drawings.

FIG. 1 is a partially omitted vertical cross-sectional view showing the inside of the main body of a pneumatic nailing machine showing an embodiment of the present invention, and shows a state in which the striking piston is located at the top dead center (from the trigger valve to the head valve). FIG. 4 is a diagram showing a state in which a close signal is being sent.

This nailing machine 1 includes a striking cylinder 3 disposed in a nailing machine main body 2, a striking piston 4 slidably and tightly fitted into the striking cylinder 3, and a main body connected to an air pressure source. an air chamber 5; a return air chamber 6 capable of applying return air pressure to the lower chamber 3b side of the striking piston 4 after the striking piston 4 reaches the bottom dead center; and an upper chamber 3a of the striking piston of the striking cylinder 3. A head that can select a first position (top dead center of the head valve piston 8a) communicating with the main air chamber 5 and a second position (bottom dead center of the head valve piston 8a) communicating with the opening to the atmosphere. A valve 8, a trigger valve 9 for operating the head valve 8, and a driver guide hole 11 for guiding a driver 10 integrally connected to the striking piston 4 in the direction coaxial with the striking cylinder 3 are formed inside. It is composed of a nose 12 and the like.

A second return air passage 16 is provided in the side wall of the impact cylinder 3 near the return air chamber 6 at a position below the first return air passage 15 .

On the other hand, an exhaust hole 18 is formed in the cylinder cap part 1T, which also serves as a noise-reducing work part, which is disposed in the upper part of the nailer main body 20 in the figure.
It communicates with the upper chamber 3a of the striking piston through.

Therefore, the trigger valve 9 that sends an opening/closing signal to the head valve 8 will be explained with reference to FIG. 2.

Note that in the state shown in FIG. 2, the trigger valve 9 is in the third position.
The head valve 8 is located at the second position.

A valve stem 21 is slidably built into the valve cylinder 20 of the trigger valve 9.

The valve stem 21 includes, from the top in the figure, a first large-diameter piston part 21a, a second large-diameter piston part 21b, a first medium-diameter piston part 21c, a second medium-diameter piston part 21d, a flange part 21e, and a triangular cross-section. operating rod 21f
It is structured in the following order.

The first large diameter piston part 21a and the second large diameter piston part 2
1b, a 101J ring 22 is fitted between the first medium diameter piston part 21c and the second medium diameter piston part 21d.
A second ring 23 is fitted between the two.

On the other hand, the main air chamber 5 in which pressurized air is stored and the trigger valve middle chamber 24 formed around the first medium-diameter piston portion 21c are always located halfway on the right side of the valve cylinder 200 in the figure. A first communication passage 25 has been opened.

The trigger valve middle chamber 24 communicates with the trigger valve lower chamber 27 through a gap 26 formed between the first middle diameter piston portion 21c and the valve cylinder 20.

Therefore, the pressurized air in the main air chamber 5 flows into the head valve piston upper chamber γ of the head valve 8 through the second passage 28 which is opened at the lower left portion of the valve cylinder 20 in the figure. There is.

On the other hand, a passage 31 is opened from a trigger valve upper chamber 29 located in the upper part of the trigger valve cylinder 200 in the drawing, and is connected to a switching valve 30 disposed inside the nailer main body 2, which will be described later. The upper chamber 29 communicates with the return air chamber 6 via a horizontal passage 40 opened on the left side of the switching valve 30 in the figure.

A constricted portion 31a is formed in the middle of the passage 31, and the flow rate of fluid (air) flowing through the passage 31 is controlled by the diameter of the constricted portion 31a.

The switching valve 30 is formed of a rubber member, and includes a first valve body portion 30a that opens and closes a passage 31 that communicates with the trigger valve upper chamber 29, and an exhaust side passage that communicates the trigger valve upper chamber 29 with the atmosphere. 32, and a third valve body 30c, which opens and closes a vertical passage 33 connected to a feed mechanism that operates a nail feeding claw (not shown).

In the state shown in FIG. 2, the switching valve 30 is moving in the direction of arrow A in the figure within the valve chamber 34, and the first valve body portion 30a and the third valve body portion 30c are located on the inner wall of the valve chamber 34. 35, and furthermore, the second valve body portion 30b closes the entrance 32a of the exhaust horizontal passage 32.

Next, the pneumatic nailing machine 1 having the above configuration according to FIG.
One cycle of impact will be explained below.

Note that in the state shown in FIG. 3, the trigger valve 9 is in the fourth position.
The head valve 8 is located at the first position.

First, the operating rod 21f of the valve stem 21 of the trigger valve 9 is pushed up in the direction of arrow B in the figure to position the trigger valve 9 in the fourth position.

Then, the inside of the valve upper chamber 29 is the first large diameter piston portion 2.
The compressed air in the valve upper chamber 29 is compressed by the operation of the valve 1a and is supplied to the switching valve 30 through the passage 31.

Then, the switching valve 30 is driven in the direction of arrow C in the figure by the pressure of the compressed air, and moves to the position shown by the dashed line.

That is, the second valve body portion 30b is connected to the exhaust side passage 320 inlet 3.
2a is opened, and the compressed air is discharged into the atmosphere through the exhaust passage 32.

The above-described movement of the switching valve 30 in the direction of arrow C occurs when the impact piston 4, which will be described later, moves toward the bottom dead center.
The compressed air returns it to its original state (the position shown by the solid line).

The pressurized air in the valve lower chamber 27 is then
It is released into the atmosphere from the gap 36 formed between 1f and the valve cylinder 20, and the head valve piston upper chamber 7, which communicates with the lower valve chamber 27, also communicates with the atmosphere through the second passage 28. .

At this time, the gap 26 formed between the valve lower chamber 27 and the valve middle chamber 24 is sealed by the second ring 23, and the pressurized air in the valve middle chamber 24 flows into the valve lower chamber 27. No inflow.

By communicating the head valve piston upper chamber 7 with the atmosphere, the head valve 8 is in a state where an open signal is sent from the trigger valve 9, and the helide valve piston 8
A is driven in the direction of the arrow in FIG. 1 and located at the first position.

Then, the pressurized air in the main air chamber 5 flows into the striking piston upper chamber 3a.

That is, the striking piston 4 rapidly descends within the striking cylinder 3 toward the bottom dead center.

In this state, the valve middle chamber 2 of the trigger valve 9
The pressure balance between the inside of the valve middle chamber 24 and the inside of the valve lower chamber 27 is disrupted, and the pressure inside the valve middle chamber 24 becomes greater than the pressure inside the valve lower chamber 27.

Therefore, the pressure of the pressurized air in the lower valve chamber 27 causes the valve stem 20 to move to the fourth position (that is, the upper surface 37 of the first large-diameter piston portion 21a touches the upper inner wall 29a of the upper valve chamber 29). It becomes a state where it is self-maintained (in a state of contact).

As the striking piston 4 rapidly descends within the striking cylinder 3 toward the bottom dead center, the pressurized air in the striking piston lower chamber 3b is stored in the return air chamber 6 shown in FIG. .

The pressurized air in 3a is then stored.

A portion of the air stored in the return air chamber 6 flows into the valve chamber 34 of the switching valve 30 through the passage 40.

Then, the switching valve 30 is moved in the direction of arrow A in FIG. 1 by the pressure of the air, and the second valve body portion 30
b closes the entrance 32a of the exhaust horizontal passage 320.

In addition, the pressure of the air causes the inner wall 35 of the valve chamber 34 to
The first valve body part 30a and the third valve body part 30C that were in contact with
is driven toward the second valve body portion 30b, and the passage 31 communicating with the valve upper chamber 29 of the trigger valve 9 and the valve chamber 3 are
4 is opened, and air in the valve chamber 34 flows into the passage 31.

Then, when the striking piston 4 reaches the bottom dead center in the striking cylinder 3, the air flowing into the passage 31 is supplied into the trigger valve upper chamber 29 while being throttled by the throttle part 31a.

Then, a signal to return the trigger valve 9 from the fourth position to the third position is obtained, and the valve stem 20 is driven in the direction of arrow E in the figure, so that the trigger valve 9 is in the state shown in FIG. 2, that is, It is returned to the third position.

Then, a closing signal is sent from the trigger valve 9 to the head valve 8, and the head valve 8 returns from the second position to the first position.

After the above-described operation is performed, the air stored in the return air chamber 6 is supplied into the lower chamber 3b of the striking piston, and the striking piston 4 discharges the air in the upper chamber 3a of the striking piston to the atmosphere through the exhaust hole 18. While ejecting the ball into the air, it returns to the top dead center again, completing one cycle of impact.

Further, by changing the diameter of the constriction part 31a provided in the passage 31 between the inside of the valve upper chamber 29 and the switching valve 30, the holding time of the valve stem 20 at the rising point can be freely adjusted. I can do it.

As is clear from the above embodiment, 1-') By pushing up the valve stem of the gas valve, the trigger valve is positioned at the fourth position, and an open signal is sent to the head valve to position the head valve at the first position. If the trigger valve is activated, the trigger valve will be self-retained until the signal that the striking piston reaches the bottom dead center is received, so it is possible to store enough air in the return air chamber to return the striking piston to the top dead center. can.

Therefore, poor return of the striking piston is prevented,
In addition, blank firing caused by poor return is also prevented.

As described above, according to the present invention, an appropriate opening/closing signal can be sent from the trigger valve to the head valve, and the intended purpose can be fully achieved.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing the inside of a nailing machine body showing an embodiment of the present invention, and FIG. 2 is an enlarged vertical cross-sectional view showing the relationship between the trigger valve and one-way valve in FIG. The valve is in the third position and the head valve is in the second position. FIG. 3 is an enlarged vertical sectional view showing the state in which the valve stem of the trigger valve shown in FIG. 1 is pushed up, and the trigger valve is in the fourth position and the head valve is in the first position. It is a figure showing a state. 1...Pneumatic nailer, 2...Pneumatic nailer body, 3...Blow cylinder, 3a...
...Blow piston upper chamber, 3b...Blow piston lower chamber, 4...Blow piston, 5...
・Main air chamber, 6...Stern air chamber, 7...Head/club piston upper chamber, 8...Head valve, 9...Torika valve , 10... Driver, 30...
・Switching valve.

Claims (1)

[Claims] 1. A striking piston integrally connected with a driver, a striking cylinder in which the striking piston is slidably and tightly fitted, a main air chamber connected to a pressurized air source, and a striking piston that is connected to the striking piston after the striking piston reaches the bottom dead center. a return air chamber capable of applying return pressurized air to the royal side of the striking cylinder; and a first position communicating with the striking piston upper chamber of the striking cylinder and the main air chamber, or an opening between the striking piston upper chamber and the atmosphere. a head valve selectively switched to a second position in communication with the head valve, a third position operating the head valve to the second position, and a fourth position switching the head valve to the first position; and a trigger valve, the striking piston is moved forward when the trigger valve is switched to a fourth position, and the striking piston is moved backward when the trigger valve is switched to a third position. In the trigger valve, the trigger valve includes a valve cylinder and a valve stem slidably and tightly fitted into the cylinder, and the valve stem has a piston portion having a difference in effective area, and the trigger valve includes a piston portion having a difference in effective area. The cylinder has a first chamber facing the small area portion of the piston portion and always communicating with the main air chamber, and a second chamber facing the large area portion of the piston portion, and the cylinder has a first chamber facing the small area portion of the piston portion and constantly communicating with the main air chamber, and a second chamber facing the large area portion of the piston portion. An air passage is provided between the return air chamber and the air passage selectively communicates between the second chamber and the return air chamber or between the second chamber and the exhaust hole. A switching valve is provided, and when the trigger valve is switched to a fourth position by pushing up the valve stem, the second chamber is compressed, so that the switching valve is brought into communication with the second chamber and the exhaust hole. At the same time, the valve stem is self-maintained in a pushed up state by the pressurized air in the first chamber, and when the striking piston reaches the bottom dead center, the pressurized air supplied into the return air chamber causes the above-mentioned Switching valve 2nd above
At the same time, the pressure supplied to the second chamber releases the self-holding state of the valve stem, and the trigger valve is switched to the third chamber.
A pneumatic impact tool characterized in that the tool can be switched to the position shown in FIG.