JPH09225856A - Fixed tool impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb a shock generated when a piston strikes a bumper so as to improve the durability of the bumper, and absorb the vibration of a impact tool as to suppress a impact noise. SOLUTION: The upper part of a bumper 18 is annularly projected toward the lower surface of a piston 7, and a first recessed part 29 forming a first air chamber 27 by tightly fitting the upper projected part of the bumper 18, is formed the bumper abutting surface of the piston 7. A second annular recessed part 34 which receives the lower part of the bumper 18 to be vertically moved under a tightly fitting condition so as to form a second air chamber 33, is formed in a part 30 to close the lower end side of a cylinder 5. An air passage 35 through which the first air chamber 27 and the second air chamber 33 are communicated with each other is passed through the bumper 18. The first air chamber side pressure receiving area of the bumper 18 is formed smaller than a second air chamber side pressure receiving area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastener hitting tool such as a nail driving machine, and more particularly, to absorb shocks caused by abrupt lowering of a piston, improve durability of a bumper, and suppress hitting sound and vibration. A fastener impact tool.

[0002]

2. Description of the Related Art A pressurized air is supplied to a housing, a cylinder is provided inside the housing, and a piston having a striking member attached therein is reciprocally arranged inside the cylinder to pressurize from the upper portion of the cylinder. When air is supplied, the piston rapidly descends and hits the fastener with the striking member at the nose to the object, and then when the air above the cylinder is exhausted to the atmosphere, pressurization of the return air chamber Air is applied to the lower surface of the piston so that the piston returns to the upper part of the cylinder, and a bumper that absorbs the shock caused by the sudden lowering of the piston is provided at the lower end of the cylinder. It is widely used at construction sites.

[0003]

When a soft bumper is used in the conventional fastener hitting tool, shock absorption is improved, but the durability of the bumper itself is weak, and conversely, when a hard bumper with high strength is used. Although the durability is increased, the shock absorption becomes low, the shock is transmitted to the entire tool, the shock is transmitted to the hand of the operator, a large impact sound is generated, and the damage to the parts of the tool is accelerated. Therefore, both have technical limits, and it is difficult to realize noise reduction and vibration absorption.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fastener impact tool which absorbs the impact generated when the piston impacts the bumper, improves the durability of the bumper, and suppresses the vibration and impact noise of the impact tool. Especially.

[0005]

In order to achieve the above object, according to the present invention, a piston is reciprocally disposed inside a cylinder, and when pressurized air is supplied from the upper part of the cylinder, the piston suddenly moves. A striking member that descends and is attached to the piston is configured to strike the fastener into the object,
A fastener striking tool in which an annular bumper that absorbs an impact due to the sudden lowering of the piston is provided on the lower end side of the cylinder, and the upper portion of the bumper projects annularly toward the lower surface of the piston. An annular first recess is formed on the bumper abutting surface of the bumper so that the upper protruding portion of the bumper is closely fitted to form a first air chamber,
The nose portion or the housing portion that closes the lower end side of the cylinder is formed with a second annular recess that receives the lower portion of the annular bumper in a tightly fit state so as to be vertically movable to form a second air chamber. An air passage communicating with the first air chamber and the second air chamber passes through the bumper, and the pressure receiving area of the bumper on the first air chamber side is the pressure receiving area on the second air chamber side. A fastener striking tool is provided which is characterized by being formed smaller.

[0006]

In the fastener striking tool having the above structure, when the piston is rapidly lowered and the striking member strikes the fastener, the bumper receives the first air chamber sealed in the first depression on the lower surface of the piston. The air pressure in the first air chamber is compressed by the downward movement of the piston, and the pressurized air flows into the second air chamber on the lower surface side of the bumper, which is also sealed, through the air passage of the bumper. After the bumper pressing force due to the air pressure in the second air chamber and the bumper pressing force due to the air pressure in the first air chamber on the upper surface side of the bumper are in equilibrium with each other, the pressure receiving area on the lower surface of the bumper is larger than the upper surface. Acts to move the bumper upward. The bumper moved upward comes into contact with the descending piston, absorbs impact energy associated with the abrupt lowering of the piston, and reduces the descending speed of the piston. Next, the piston whose speed has decreased further descends together with the bumper, but due to the buffering effect of the pressurized air in the second air chamber on the lower surface of the bumper and the bumper, the piston further loses impact energy, and Like the above, it comes into contact with the nose through the bumper without impact and stops.
Since the bumper has a great cushioning effect in this way, impact noise and vibration are sufficiently suppressed, and shocks to the bumper are also largely absorbed, and damage to the bumper and piston is minimized.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fastener striking tool according to the present invention will be described below with reference to the drawings. In FIG. 1, a fastener striking tool (typically, a nailing machine) 1 includes a handle 2 and a housing 3 integrally formed with the handle 2, and the handle 2 is supplied with pressurized air from an end portion thereof, Is formed in the cavity as a reservoir of pressurized air. A cylinder 5 is provided inside the housing 3, and a piston 7 to which a striking member 6 is attached is reciprocally arranged inside the cylinder 5. A main valve 9 is provided at the upper end of the cylinder 5, and the main valve seals the upper end of the cylinder 5 and does not supply the pressurized air in the reservoir 10 inside the handle 2 and the housing 3 to the cylinder 5 (the axial position). (A position on the left side of X) and a striking position (a position on the right side of the axis x) where pressurized air is supplied from the reservoir 10 by releasing the seal at the upper end of the cylinder 5. In the rest position, the piston 7 rests on top of the cylinder 5. At the striking position, pressurized air is supplied to the upper part of the piston 7 from the gap between the main valve 9 and the upper end of the cylinder 5, and the piston 7 is strongly and rapidly pushed downward.

By this pressing, the striking member 6 strikes the fixing tool on the nose 11 and strikes the object such as a plate. At the time of this driving, at the same time, pressurized air is stored in the return air chamber 13 formed between the lower portion of the cylinder 5 and the housing 3. While the piston 7 on the way down is in the upper part of the cylinder, the air below the piston 7 is stored in the return air chamber 13 through the intermediate hole 14 and the hole 15 on the lower end side of the cylinder 5, and the piston 7 passes through the intermediate hole 14. Then, the pressurized air in the cylinder chamber above the piston is also newly supplied through the intermediate hole 14. Since the intermediate hole 14 is provided with an O-ring 17 as a check valve, it does not flow backward from the intermediate hole 14 to the cylinder side, and a sufficient amount of pressurized air is stored in the return air chamber 13. Therefore, when the main valve 9 returns to the rest position (the position on the left side of the axis line x), the air in the upper part of the cylinder is exhausted to the atmosphere, and the pressurized air in the return air chamber 13 passes through the hole 15 on the lower end side to the cylinder below the piston. It flows into the chamber, acts on the lower surface of the piston 7, and the piston 7 returns to the upper part of the cylinder 5. A bumper 18 that absorbs the shock caused by the sudden lowering of the piston 7 is provided on the lower end side of the cylinder 5.

The main valve 9 is controlled by a trigger device 19 provided at the base of the handle 2. When the trigger valve pin 21 is in the rest position without being pushed, the pressurized air in the reservoir 10 of the handle 2 enters the main valve chamber 23 through the pipe 22 shown by the broken line, and the main valve 9 is pushed downwards, as shown in FIG. In a rest position to the left of axis X of. No pressurized air is supplied to the cylinder 5 and the piston 7
No pressurized air is sent to the upper surface of. Next, when the trigger valve pin 21 is pushed upward by pulling the trigger lever 25, the air in the main valve chamber 23 is exhausted to the atmosphere through the pipe 22 and the trigger device 19,
Since there is no force to push down the main valve 9, the main valve 9 is pushed up by the pressure of the pressurized air in the reservoir and is moved to the striking position on the right side of the axis X. Pressurized air in the reservoir 10 is supplied to the upper part of the piston 7, and the piston 7 is strongly pushed downward so that the striking member 6 drives the fastener in the nose 11 to the object. And the trigger lever 2
When 5 is released, the trigger valve pin 21 returns to the lower position, and the main valve 9 returns to the rest position on the left side of the axis X. Since the pressurized air is no longer supplied to the upper surface side of the piston 7 that has been pushed down and is exhausted to the atmosphere, the action of the pressurized air from the return chamber 13 causes the piston 7 to move to the bottom of the cylinder 5. It rapidly rises from the point and returns to the rest position shown.

Since the piston 7 rapidly descends to the lower end side of the cylinder 5 in order to drive the fastener to the object, the piston 7
The bumper 18 is indispensable in order to stop while absorbing the impact. When a soft bumper is used, the shock absorption is improved, but the durability of the bumper is lowered and the deformation is increased, and the bumper may be plastically deformed or may generate heat and may be damaged early. On the other hand, if a hard bumper with high strength is used, the durability will increase, but the impact absorption will be low, and the impact will be transmitted to the entire tool, and the impact sound will be transmitted to the worker's hand etc. and the impact sound will be generated. It may also accelerate the damage of the parts.

In the present invention, air chambers are formed on the upper surface and the lower surface of the bumper so that both air chambers and the bumper are organically associated with each other to obtain a large cushioning effect. First, the upper portion 26 of the bumper 18 is formed so as to project annularly toward the lower surface of the piston 7. Correspondingly, an annular first recess 29 is formed on the lower surface side of the piston 7 to form a first air chamber 27 in which the upper protruding portion 26 of the bumper 18 is tightly fitted and sealed. Are formed. Further, the lower portion 31 of the bumper 18 can be moved up and down in the upper portion 30 of the nose 11 that closes the lower end side of the cylinder 5 (or the housing portion when the lower portion of the housing 3 closes the lower end side of the cylinder 5). A second annular recess 34 is formed that defines a second air chamber 33 that is received and sealed in a tight fit. The bumper 18 is provided with an air passage 35 that penetrates the first air chamber 27 and the second air chamber 33 so as to communicate with each other.
Further, the bumper 18 is formed such that the pressure receiving area on the first air chamber 27 side is smaller than the pressure receiving area on the second air chamber 33 side. Therefore, when the air pressures of the second air chamber 33 and the first air chamber 27 become the same, the bumper 18 receives the force of the air pressure of the second air chamber 33, that is, the force for moving the bumper 18 upward due to the action of the air pressure of the second air chamber 33. Receive.
Since a high cushioning effect is obtained in the present invention, the bumper 18 can be formed of a hard rubber having high strength to some extent, which can enhance the durability of the bumper.

The operation of the apparatus having the above structure will be described with reference to FIGS. On the left side of the axis X in FIG. 1, when the piston 7 descends from the upper rest position shown by the solid line to the position shown by the imaginary line, the first lower surface of the piston 7
The annular upper protruding portion 26 of the bumper 18 is tightly received in the recess 29, and the air on the lower surface side of the piston 7 is confined in the first air chamber 27. The piston 7 continues to descend strongly and at high speed so as to compress the air in the first air chamber 27 as it is. In the bumper 18, the first air chamber 27 above the bumper and the second air chamber 33 below are located in the air passage 35.
The compressed air in the first air chamber 27 flows into the second air chamber 33 to increase the air pressure in the second air chamber 33.

Due to the inflow of pressurized air from the first air chamber 27, the air pressure in the second air chamber 33 gradually rises, and the bumper pressing force by the air pressure in the first air chamber 27 and the second air chamber 3 are increased.
The bumper pressing force due to the air pressure of 3 is balanced. Even after the equilibrium, the pressurized air flows from the first air chamber 27 to the second air chamber 33 so as to have the same pressure, but in the bumper 18, the pressure receiving area of the lower surface, that is, the second air chamber 33 is the upper surface, that is, Since it is larger than the one air chamber 27, the force for pushing up the bumper is larger than the force for pushing down the bumper 18, which causes the bumper 18 to move upward. This state is shown in FIG.
The solid line is shown on the right side of the axis line X, and the piston 7 is slightly lowered from the position shown by the imaginary line on the left side of the axis line X in FIG. 1, but the bumper 18 is moved slightly upward. The bumper 18 that has moved upward moves the piston 7 that is descending.
The impact energy associated with the sudden lowering of the piston 7 is absorbed, and the lowering speed of the piston 7 is reduced. The rate of decrease in the descending speed of the piston 7 is selected by selecting the number of air passages 35 in the bumper 18 and their diameters, and the pressure receiving area on the first air chamber side and the pressure receiving area on the second air chamber side. Can be changed.

Next, as shown on the left side of the axis X in FIG. 2, the piston 7 whose speed has decreased further descends together with the bumper 18, and the second air on the lower surface of the bumper 18 is descended as the piston 7 descends. The air in chamber 33 is further compressed. Piston 7
Receives a buffering effect by the pressurized air in the second air chamber 33 and the bumper 18 on the lower surface of the piston, and further loses the impact energy (ie, collision energy) by the pressurized air on the upper surface side of the piston. Due to this large cushioning effect, the piston 7 comes into contact with the nose 30 via the bumper 18 and stops without colliding with the nose 30 as in the conventional case. The stopped state is shown on the right side of the axis X in FIG.
In this way, since a large cushioning effect is obtained by the bumper 18 and the pressurized air in both air chambers, the impact sound and vibration are sufficiently suppressed, and the impact on the bumper 18 is also largely absorbed, and the bumper 18 and the piston are 7. Minimize damage. Also, since a high cushioning effect can be obtained, the bumper 18
Can be made of high-strength and hard rubber, which can also increase the durability of the bumper.

FIG. 3 shows an example in which the bumper 18 is positioned above the position shown in FIG. 1 in the stationary position to sufficiently secure the second air chamber 33 from the stationary state. Also in the embodiment shown in FIG. 3, a large buffering effect can be obtained as in the embodiment shown in FIGS. That is, on the left side of the axis X in FIG. 3, when the piston 7 descends from the upper stationary position shown by the solid line to the position shown by the imaginary line, the air on the lower surface side of the piston is confined in the first air chamber 27. Furthermore, the piston 7 descends and continues to compress the air in the first air chamber 27, but at this time, as shown on the right side of the axis X in FIG. The pressure in the second air chamber 33 also rises. Further, the compressed air in the first air chamber 27 that has been compressed flows into the second air chamber 33 through the air passage 35, so that the air pressure in the second air chamber 33 rises, and the first air chamber 27 and the second air chamber The bumper pressing force due to the air pressure of 33 is balanced. The following operation is shown in FIG.
And the same as the embodiment of FIG. That is, bumper 1
Since the pressure receiving area of the second air chamber 33 on the side of the second air chamber 33 is larger than that of the first air chamber 27, the bumper 18 is moved upward and brought into contact with the piston 7 that is descending. Is absorbed to reduce the descending speed of the piston 7. The piston 7 whose speed has decreased is the bumper 1
Although it descends together with 8, the impact energy is further lost due to the cushioning effect of the pressurized air in the second air chamber 33 and the bumper 18, and the nose 30 is hit without impacting as in the conventional case. Stop in contact.

[0016]

According to the impact tool of the present invention, the first air chamber is formed on the upper surface of the bumper and the second air chamber is formed on the lower surface of the bumper, and the first air chamber and the second air chamber are formed on the bumper. The air passage that communicates with the air chamber penetrates the
Since the pressure receiving area on the side of the air chamber is formed smaller than the pressure receiving area on the side of the second air chamber, when the air pressure of the second air chamber on the upper surface side of the bumper becomes about the same as the pressure of the first air chamber on the upper surface side of the bumper, A force that moves the bumper upward acts, the bumper moved upward contacts the piston that is descending, considerably absorbs the impact energy due to the sudden lowering of the piston, and lowers the descending speed of the piston . As a result, it is possible to reliably avoid the impact of the piston, which has been found in conventional impact tools, with the bumper. Next, the piston whose speed has decreased further descends together with the bumper, but due to the buffering effect of the pressurized air in the second air chamber on the lower surface of the bumper and the bumper, the piston further loses impact energy and goes to the nose. It abuts and stops without shocking collision. Therefore, a large cushioning effect is obtained by the bumper and the pressurized air in both air chambers, impact noise and vibration are sufficiently suppressed, and heat generation of the bumper is also suppressed. Also,
The impact on the bumper is also largely absorbed, minimizing damage to the bumper and piston. Further, the impact when the piston is hit can be sufficiently absorbed by the hard bumper, which improves the durability of the bumper.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional front view of a fastener striking tool according to an embodiment of the present invention with a part thereof omitted.

FIG. 2 is an operation explanatory view of a main part of the impact tool shown in FIG. 1 during impact.

FIG. 3 is a vertical cross-sectional front view of a main part of an impact tool according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Fixing Tool Hitting Tool 2 Handle 3 Housing 5 Cylinder 6 Hitting Member 7 Piston 9 Main Valve 10 Reservoir 11 Nose 13 Return Air Chamber 14 Intermediate Hole 15 Lower End Hole 18 Bumper 19 Trigger Device 21 Trigger Valve Pin 23 Main Valve Chamber 26 Bumper Upper protruding portion 27 First air chamber 29 First depression 30 Nose upper portion 31 Bumper lower portion 33 Second air chamber 34 Second depression 35 Air passage

Claims (1)

[Claims] 1. A piston is reciprocally disposed inside a cylinder, and when pressurized air is supplied from the top of the cylinder,
The piston suddenly descends and a striking member attached to the piston is configured to strike the fastener into an object, and an annular bumper that absorbs an impact due to the sudden lowering of the piston is provided on the lower end side of the cylinder. In the fastener striking tool, the upper portion of the bumper is annularly projected toward the lower surface of the piston, and the upper protruding portion of the bumper is tightly fitted to the bumper contact surface of the piston to form the first air chamber. An annular first recess to be formed is formed, and a nose portion or a housing portion that closes the lower end side of the cylinder receives a lower portion of the annular bumper in a tightly fit state so as to be vertically movable, and then receives a second air chamber. Forming a second annular recess, and an air passage communicating with the first air chamber and the second air chamber penetrates through the bumper, and the bumper further includes: The pressure tool impact tool on the side of the first air chamber is formed smaller than the pressure area on the side of the second air chamber.