JP2000334679A - Driving machine - Google Patents

Abstract

(57) [Problem] To provide a driving machine that prevents a member other than the piston bumper from being damaged by continuing the driving operation even though the life of the piston bumper has expired. That is. SOLUTION: When a piston bumper 7 becomes lower than a prescribed height, a seal surface of a seal member 9 provided on a piston 4a is located below an upper end of a second air passage 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving machine for driving a fastener such as a nail.

[0002]

2. Description of the Related Art An example of a conventional driving machine is shown in FIG.

As shown in FIG. 1, a driving machine 1 includes a cylinder 3
Piston 4a held vertically movable therein, drive bit 4b provided integrally with piston 4a, and piston 4a and drive bit provided below cylinder 3 and generated when a not-shown stop is driven in. A piston bumper 7 made of a flexible material such as rubber for absorbing the excess energy of the piston 4b and a return air chamber 12 for storing compressed air for returning the piston 4a at the bottom dead center to the top dead center are provided. ing. Further, as shown in the figure, the cylinder 3 is provided with a first air passage 14 having a check valve 13 communicating with the return air chamber 12 and a second air passage 8.
The piston 4a is provided with a seal member including an O-ring 20 and a piston ring 19 for sealing the piston 4a and the cylinder 3.

[0004] The driving machine configured as described above is driven by operating a drive switch (not shown).
Compressed air flows into the upper surface of the piston 4a located at the upper portion of the cylinder 3, and the piston 4a and the drive bit 4b rapidly descend inside the cylinder 3, and the lower end of the drive bit 4b strikes a not-shown tool such as a nail. When the piston 4a descends, the air below the piston 4a returns through the second air passage 8 into the air chamber 12, and the first O-ring 20 provided on the cylinder 3 as a seal member provided on the piston 4a. When passing through the air passage 14, the compressed air above the piston 4 a in the cylinder 3 also flows into the return air chamber 12 via the first air passage 14. Excess energy of the piston 4a and the drive bit 4b generated at the time of driving is converted into heat and sound and absorbed by the piston 4a colliding with the piston bumper 7 and deforming the piston bumper 7. When the compressed air above the piston 4a in the cylinder 3 is exhausted, the compressed air accumulated in the return air chamber 12 flows into the cylinder 3 via the second air passage 8, and the lower side of the piston 4a in the cylinder 3 When pressed, the piston 4a and the drive bit 4b return to the top dead center.

The driving tool shown in FIG. 5 is in a state immediately after the drive bit 4b drives a stopper (not shown) or after the driving is completed, and the piston 4a which has descended rapidly in the cylinder 3 collides. The deformed piston bumper 7 is thereafter in a state of elastic recovery.

[0006]

As described above, the piston bumper 7 absorbs the excess energy of the piston 4a and the drive bit 4b generated at the time of driving by colliding with the piston 4a descending rapidly in the cylinder 3 and deforming. However, it is a consumable member having a short life because it is likely to be damaged or permanently deformed because it is deformed by repeated impacts.

In the conventional driving machine having the above-described configuration, if the driving operation is repeated without noticing that the piston bumper 7 has reached the end of its life due to damage or permanent deformation of the piston bumper 7, the piston generated at the time of driving 4a and the drive bit 4b cannot absorb the excess energy, so that not only the piston bumper 7 but also the piston 4
a, the drive bit 4b, the tail cover 15 and the like may be damaged.

This example will be described with reference to FIGS. 6 and 7. FIG. 6 is an enlarged sectional view of a main part showing a state in which a damaged portion 18 has occurred in a part of the piston bumper 7, and FIG. 7 is an enlarged sectional view of a main part showing a state in which the piston 4a collides with the piston bumper 7 shown in FIG. FIG.

When a damaged portion 18 is formed in a part of the piston bumper 7 as shown in FIG. 6, when the piston 4a which has rapidly descended in the cylinder 3 collides with the piston bumper 7 as shown in FIG. As a result, the amount of deformation of the piston bumper 7 is increased, and the upper part of the tail cover 15 and the upper part of the drive bit 4b collide as shown in the figure. Thereby, the upper part of the tail cover 15 and the drive bit 4b
However, there is a disadvantage that the life of the driving machine is shortened due to breakage of the tool.

As an example, an example in which a damaged portion 18 is formed in a part of the piston bumper 7 has been described.
Is permanently deformed as described above, in addition to the possibility that the upper part of the tail cover 15 and the drive bit 4b may be damaged as described above, and the excess energy of the piston 4a and the drive bit 4b generated at the time of driving is transferred to the piston bumper 7
Cannot be absorbed, and the piston 4a and the tail cover 15 may be damaged.

An object of the present invention is to solve the above-mentioned disadvantages and to provide a long-life driving machine.

[0012]

SUMMARY OF THE INVENTION The object of the present invention is to ensure that when the piston bumper is lower than a specified height, the seal member of the piston is located below the upper end of the air passage for returning the piston and the drive bit to the top dead center. This is achieved by configuring.

[0013]

FIG. 1 shows an embodiment of the driving machine according to the present invention.
This will be described with reference to FIG.

FIG. 1 shows a piston 4a and a drive bit 4
FIG. 2 shows a state in which the piston 4a and the drive bit 4b suddenly descend inside the cylinder 3 and the piston 4a collides with the piston bumper 7, and FIG. 4 shows a state in which the piston bumper 7 has elastically returned, and FIG.
8 shows the state after the completion of the driving when 8 occurs.

Compressed air from a compressor (not shown) is stored in a pressure accumulating chamber 2 in the driving machine body 1 via an air hose or the like. A cylindrical cylinder 3 is provided in the driving machine main body 1, and a piston 4 a and a drive bit 4 b slidable up and down and formed of the same member are provided in the cylinder 3, and a drive bit 4 b A stopper 5 such as a nail is driven by the lower end. A piston bumper 7 made of a flexible material such as rubber that absorbs excess energy generated in the piston 4a and the drive bit 4b when the lower surface 4e of the piston 4a collides when the stopper 5 is driven is provided below the cylinder 3.

An O-ring 9, which is a seal member for sealing the piston 4a and the cylinder 3, is attached to the piston 4a. When the piston 4a suddenly descends in the cylinder 3 and collides with the piston bumper 7, the piston 4a In order to prevent the deformed portion of the bumper 7 from entering into the second air passage 8 provided in the cylinder 3, the outer periphery of the lower surface 4e of the piston 4a
A partition wall 4h is provided between the upper part of the piston bumper 7 and the second air passage 8 when the lower surface 4e of the cylinder a collides.

A sleeve valve 10 is provided on the outer periphery of the upper side of the cylinder 3. The lower end of the sleeve valve 10 opens the upper end of the cylinder 3 and closes the exhaust valve 11, so that the pressure accumulating chamber 2 and the upper side of the piston 4a in the cylinder 3 communicate with each other. As the sleeve valve 10 rises, the upper end of the cylinder 3 closes and the exhaust valve 11
Is opened, and the upper side of the piston 4a in the cylinder 3 is the exhaust port 21.
It is designed to communicate with the atmosphere via the. Cylinder 3
A return air chamber 12 for storing compressed air for returning the piston 4a at the bottom dead center and the drive bit 4b to the top dead center is provided on the outer circumference, and the piston 4a
A first air passage 14 provided with a check valve 13 made of a flexible material such as rubber which is returned from the cylinder 3 and communicates only in the direction of the air chamber 12 is provided in the middle of the vertical movement of the cylinder 3.
A second air passage 8 that always communicates the cylinder 3 with the return air chamber 12 is provided on the outer periphery of the lower end.

FIG. 2 shows that the piston 4a and the drive bit 4b suddenly descend inside the cylinder 3 and
e shows a state at the time of collision with the piston bumper 7, and the piston bumper 7 is flexed and deformed. For simplicity of description, this state is hereinafter referred to as the piston 4a being at the dynamic dead bottom dead center. FIG. 3 shows a state in which the piston bumper 7 that has been bent and deformed as shown in FIG. 2 has elastically returned. Hereinafter, this state is referred to as the piston 4a being at the bottom dead center of the static pressure.

FIG. 4 shows a state in which the piston 4a is at a statically pressed bottom dead center when a damaged portion 18 occurs in the piston bumper 7.

The piston 4a, the O-ring 9, the piston bumper 7 and the second air passage 8 are
When the piston bumper 7 is lower than the specified height due to breakage or permanent deformation of the piston 4a, the sealing surface of the O-ring 9 provided on the piston 4a when the piston 4a is at the bottom dead center of the static pressure is shown in FIG. As shown, it is configured to be located below the upper end of the second air passage 8.

Next, a driving operation by the driving machine 1 having the above-described configuration will be described.

FIG. 1 shows a state before the driving operation, in which the sleeve valve 10 is in the raised position, the communication between the pressure accumulating chamber 2 and the cylinder 3 is cut off, and the exhaust valve 11 is in the open state. The upper side of the piston 4a is the exhaust port 2.
1, and the piston 4a and the drive bit 4b are located at the top dead center. The lower side of the piston 4a in the cylinder 3 and the return air chamber 12 are at atmospheric pressure.

When the sleeve valve 10 is lowered,
And the upper side of the piston 4a of the cylinder 3 is communicated, and the exhaust valve 11 is closed to shut off the communication between the upper side of the piston 4a of the cylinder 3 and the atmosphere. 4a and the drive bit 4b are rapidly moved to the bottom dead center in the cylinder 3.

When the lower end of the drive bit 4b descends while hitting the stopper 5, and the O-ring 9 provided on the piston 4a passes through the first air passage 14, the piston in the cylinder 3 is passed through the first air passage 14. 4a above and return air chamber 12
The compressed air flows into the return air chamber 12. Further, the air below the piston 4 a in the cylinder 3 flows into the return air chamber 12 via the second air passage 8 while being compressed.

When the piston 4a and the drive bit 4b move to the bottom dead center, the lower surface 4e of the piston 4a collides with the piston bumper 7, and the piston bumper 7 as shown in FIG. In addition, the excess energy of the drive bit 4b is absorbed by bending and deforming the drive bit 4b in the moving direction.

As described above, when the height of the piston bumper 7 is lower than the specified height, the sealing surface of the O-ring 9 of the piston 4a is moved to the second position when the piston 4a is at the statically dead bottom dead center.
The piston 4a, the O-ring 9, and the piston bumper 7 are configured to be located below the upper end of the air passage 8. Therefore, even when the piston bumper 7 is higher than the specified height, the lower surface 4e of the piston 4a is When the piston bumper 7 is at the dynamic dead bottom dead center where the piston bumper 7 deflects and deflects, the sealing surface of the O-ring 9 provided on the piston 4a is higher than the upper end of the second air passage 8 as shown in FIG. Although it may be located below, the piston bumper 7 immediately returns elastically, and the sealing surface of the O-ring 9 is again located above the second air passage 8 as shown in FIG.

Next, when the sleeve valve 10 is lowered,
The compressed air on the upper side of the piston 4a in the cylinder 3 is exhausted to the atmosphere, and the lower side of the piston 4a is pressed by the compressed air in the return air chamber 12 flowing into the cylinder 3 through the second air passage 8, so that the piston 4a and The drive bit 4b returns to the top dead center and returns to the state of FIG.

The above driving operation is performed by the piston bumper 7.
Is higher than the specified height in the normal state. Next, the operation when the damaged portion 18 occurs in the piston bumper 7 will be described.

When a broken portion 18 is formed in the piston bumper 7, the piston bumper 7 becomes lower than a specified height, and as shown in FIG. That is, the surface on the cylinder 3 side is located below the upper end of the second air passage 8.

The specified height here is determined by the piston bumper 7.
Is set to the height of the piston bumper 7 before the piston bumper 7 becomes in a state where the excess energy of the piston 4a and the drive bit 4b generated at the time of driving cannot be absorbed by the piston bumper 7. I have.

When the piston bumper 7 is lower than the specified height, and the piston 4a is at the static pressing bottom dead center, the sealing surface of the O-ring 9 provided on the piston 4a is lower than the upper end of the second air passage 8. When it comes to the position, even if the sleeve valve 10 is raised after the end of driving the stopper,
Since the sealing surface of the O-ring 9 is located below the upper end of the second air passage 8, the compressed air in the return air chamber 12 flowing into the cylinder 3 via the second air passage 8 is compressed by the piston 4 a. The exhaust valve 1 cannot work to press the lower surface 4e upward and passes through the cylinder 3 above the piston 4a.
1. Exhausted to the atmosphere through the exhaust port 21, the piston 4a
And the drive bit 4b maintains the state located at the bottom dead center.

After that, even if the sleeve valve 10 is lowered again to allow the inside of the cylinder 3 to communicate with the pressure accumulating chamber 2,
Since the piston 4a and the drive bit 4b maintain the state of being located at the bottom dead center, the driving operation cannot be performed.

With this configuration, when the piston bumper 7 is damaged or permanently deformed and the piston bumper 7 becomes lower than the specified height, the driving operation cannot be performed. It is possible to prevent the piston 4a, the drive bit 4b, the tail cover 15, and the like from being damaged due to the inability of the piston bumper 7 to absorb the surplus energy of the piston 4a and the drive bit 4b generated at that time.

That is, by disabling the driving operation, it is detected that the piston bumper 7 is in the replacement time, and the members other than the piston bumper 7 are damaged and the life of the driving machine is shortened. Can be prevented.

In the above embodiment, the seal member provided on the piston 4a is the O-ring 9, but may be a seal member composed of the piston ring 19 and the O-ring 20, as shown in FIGS.

Also, the case where the piston bumper 7 has the broken portion 18 has been described. However, the spring constant does not change, and the piston bumper 7 is permanently deformed in the axial direction of the drive bit 4b, so that the height is reduced. Similarly, when the height is lower than the height, the next driving operation cannot be performed, and the piston bumper 7 cannot be operated.
Replacement time can be detected.

[0037]

According to the present invention, when the piston bumper is lower than the specified height, the sealing member is located below the upper end of the air passage, so that the piston bumper cannot be driven at the replacement timing. As a result, a long-life driving machine can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of the driving machine of the present invention.

FIG. 2 is a sectional view of a main part showing a state where the piston collides with a piston bumper in the driving machine shown in FIG. 1;

FIG. 3 is a sectional view of a main part showing a state in which the piston bumper has elastically returned from the state shown in FIG.

FIG. 4 is an enlarged sectional view of a main part showing a state after a driving operation when a piston bumper is damaged in the embodiment of the driving machine of the present invention.

FIG. 5 is an enlarged sectional view of an essential part showing an example of a conventional driving machine.

FIG. 6 is an enlarged sectional view of a main part showing a state in which a piston bumper has been damaged in the driving machine shown in FIG. 5;

7 is an enlarged sectional view of a main part showing a state where a piston collides with the piston bumper shown in FIG. 6;

[Description of References] 1 is a driving machine main body, 4a is a piston, 4b is a drive bit, 4e is a piston lower surface, 7 is a piston bumper, 8 is a second air passage, 9 is an O-ring, and 18 is a broken part.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C054 CB01 CD02 CE12 CF02 CF11 3C068 AA01 BB01 CC02 DD11 DD13 JJ20

Claims (1)

[Claims] A pressure accumulating chamber for accumulating compressed air, a piston reciprocating in a cylinder by a pressing force of the compressed air,
A drive bit that is integrally connected to the piston and strikes the stopper, a seal member that cooperates with the piston to seal the piston and the cylinder, and a piston bumper that absorbs excess energy of the piston and the drive bit at the bottom dead center of the piston. A driving machine having a return air chamber for accumulating compressed air for returning the drive bit from bottom dead center to top dead center, and an air passage returning to the cylinder and communicating the air chamber with the inside of the cylinder, A driving machine wherein the sealing member is located below the upper end of the air passage when the piston bumper is lower than a prescribed height.