JPS5917586Y2 - Bumper destruction prevention device for impact tools - Google Patents

Description

[Detailed Description of the Invention] The present invention has a nail driving section in which a driver, which is an integrally connected nail driving member, is slidably and tightly fitted into an impact cylinder built into the impact tool main body, and protrudes from the main body. This invention relates to a destruction prevention device for a bumper, which is disposed to stop a striking piston, which is operated forcefully within a driver guide hole formed in the axial direction of the nose of the engine, at the bottom dead center position within the striking cylinder. It is something.

As an example of this type of impact tool, fluid pressure such as compressed air pressure is applied to the impact piston, so that the impact piston is suddenly lowered within the impact cylinder, and the tip of a driver is integrally connected in the axial direction of the impact piston. A pneumatic nail configured to easily perform nail driving work by hitting the head of a nail preloaded in the driver guide hole of the nose with a screwdriver and driving out the nails one by one from the tip of the nose. His hitting machine is known.

In other words, when driving a single nail, fluid pressure is supplied to the upper chamber of the piston of the striking cylinder, and residual air in the lower chamber of the piston is released to the atmosphere to move the striking piston away from the top dead center. It moves rapidly toward the bottom dead center, and after nailing is completed, a return fluid pressure (spring pressure, etc. may be used in some cases) is applied to the lower chamber of the striking piston, and the upper chamber of the striking piston is opened to the atmosphere. The striking piston is then moved back from the bottom dead center position toward the top dead center.

The lower end of the striking cylinder is made of hard rubber or the like to stop the striking piston at the bottom dead center position during nail driving and to prevent the impact of the piston from being transmitted to the main body as unnecessary vibrations. A bumper is installed.

Therefore, when the striking piston is stopped, the bumper is elastically deformed by the collision of the striking piston.

If the above-mentioned elastic deformation occurs frequently by stopping the multiple receiving, the surface of the bumper will partially crack (cracks are particularly likely to form on the top surface of the bumper).

), which eventually caused the cracks to spread, causing them to break and scatter.

In particular, if the driver does not drive a nail and the bumper is not driven in, a strong impact is applied to the bumper and the above-mentioned damage becomes even more severe.

In addition, in large nailing machines that require large driving energy,
The temperature of the bumper is 130C to 150° when driving nails repeatedly.
It reaches temperatures as high as C.

Therefore, if you choose a rubber material that can maintain the strength of the bumper even at high temperatures, the low temperature range will be sacrificed due to the characteristics of rubber.
In environments around -10°C, bumpers often crack and break.

Therefore, the present invention has been proposed in order to eliminate the above-mentioned conventional drawbacks, and its purpose is to reliably prevent the bumper from being destroyed during impact.

Hereinafter, one embodiment of the present invention will be explained in detail based on FIGS. 1 and 2.

Figures 1 and 2 show a pneumatic nailer 1 to which the present invention is applied.
FIG. 1 is a diagram showing a state in which the striking piston 6 is moving forward toward the bottom dead center, and FIG. 2 is a diagram showing a state in which the striking piston 6 is projected into the bumper 30. It is.

Reference numeral 2 denotes a nailing machine main body, in which a striking cylinder 3 is built and a nose 4 is disposed at a lower end 2a.

That is, the diameter of the vicinity of the lower end 2a of the main body 2 is reduced, and the lower end 3a of the impact cylinder 3 is tightly fitted and held therein, and the lower end 2a is further provided with a connection provided at the base end of the nose 4 (upper end side in the figure). The portions 41 are integrally connected.

As a result, the nose 4 has a driver guide hole 43 formed through the nose 4 in the axial direction thereof and protrudes coaxially with the lower ends of the main body 2 and the impact cylinder 3.

The inner wall of the connecting part 41 of the nose 4 has a flat part 41b inside an annular inclined surface 41a on the outer peripheral side, and a stepped part 42 is formed inside the flat part 41b. Section 42
A driver guide 5 having a driver insertion hole 51 in the center is loosely fitted therein.

A flange portion 52 is formed on this driver guide 5.

Further, 6 is a striking piston, which is tightly fitted into the striking cylinder 3 via an O-ring 61 so as to be movable in the vertical direction in the figure.

A driver 7 is integrally connected to and protrudes below the piston 6.

The impact piston 6 is driven by pressurized air in a main air chamber (not shown) supplied into the piston upper chamber 3A of the impact cylinder 3 via a head valve (not shown) disposed in an upper portion of the main body 2. Blow cylinder 3
It moves forward toward the inner bottom dead center position.

Further, a return air chamber 70 is formed in the lower outer peripheral portion of the striking cylinder 3, in which air for returning the striking piston 6 to the top dead center is stored.

When the striking piston 6 moves forward, the pressurized air that has been supplied to the piston upper chamber 3A of the striking cylinder 3 is introduced into the return air chamber 70 from the return air supply hole 71.

In addition, on the inner circumferential wall of the lower end 3a of the impact cylinder 3,
A large diameter portion 3d constituting a bumper holding portion is formed that has a slightly larger diameter than the cylinder main diameter portion 3b with the step portion 3C as a boundary.

A bumper 30 is incorporated into the lower end portion 3a of the striking cylinder 3 to receive and stop the striking piston 6 at the bottom dead center.

This bumper 30 has an outer ring block 31 which is an outer bumper part.
It is constructed by integrally assembling two independent annular blocks: and an inner ring block 32 which is an inner bumper part.

The outer circumferential wall of the outer annular block 31 has an outermost bulge 82 at its midpoint in the height direction, and the diameter gradually decreases from the bulge 82 toward the upper and lower end edges 31 a and 31 b.

The vicinity of the outermost bulging portion 82 is fitted into the large diameter portion 3d of the impact cylinder 3, and is locked by the stepped portion 3C.

Further, in the axial direction of the central part of the outer ring block 31, an insertion hole 8 into which a cylindrical body part 32A of the inner ring block 32, which will be described later, is inserted.
3 have been established.

The inner ring block 32 has a cylindrical body part 32A whose outer diameter gradually decreases in the axial direction toward the distal end, that is, the side where the impact piston 6 contacts, and a cylindrical body part 32A in which the outer diameter gradually decreases in the axial direction from the base end of the cylindrical body 32A. A driver insertion hole 84 is provided in the axial direction of the central portion of the cylindrical body portion 32A.

The upper end surface 85 of the flange portion 32B serves as a flat engaging mounting portion on which the outer ring block 31 is placed.

An outer circumferential wall 88 of the cylindrical body portion 32A of the inner ring block 31 and an inner circumferential wall 89 of the insertion hole 83 of the outer ring block 31.
The inner ring block 32 and outer ring block 31 are provided between the inner ring block 32 and the outer ring block 31.
A gap 90 is maintained to allow radial deflection of the.

In the above configuration, in the bumper 30, the outermost bulging portion 82 of the outer ring block 31 engages with the stepped portion 3C of the striking cylinder 3;
Further, the flange portion 32B of the inner ring block 32 engages with the annular inclined surface 41a of the nose connecting portion 41, preventing the blowing cylinder from falling upward in the figure, that is, to the side where the striking piston 6 is disposed. A stable installation state can be obtained at the lower end portion 3a of No. 3.

This means that a stable installation condition can be obtained even when the nailer 1 is used for ceiling driving, that is, when the nose 4 is directed upward and a nail is driven from below onto a surface (not shown) to be nailed. It turns out.

On the other hand, an annular groove 20 is formed on the lower surface 6b of the striking piston 6 and serves as a bumper fitting portion.

This annular groove 20 includes a first annular groove 21 that fits and holds the outer ring block 31 and a cylindrical body portion 3 of the inner ring block 32.
2A, and the first annular groove 21 and the second annular groove 22 form three annular protrusions 23, 24, 2A on the lower surface 6b of the striking piston 6.
25 is formed.

Then, the striking piston 6 moves forward in the direction of the arrow in FIG. 1 by the pressurized air supplied into the piston upper chamber 3A of the striking cylinder 3, and reaches the bottom dead center as shown in FIG. When struck, the outer ring block 31 is fitted into the first annular groove 21, and the cylindrical body portion 32A of the inner ring block 32 is fitted into the second annular groove 22.

Therefore, the impact force when the striking piston 6 hits can be reliably distributed and received by the outer ring block 31 and the inner ring block 32, so the durability is superior compared to a bumper made of a single block. ing.

The elastic deformation of the upper end portion of the outer ring block 31 in the radial direction is prevented by the annular projections 23 and 24, and
Elastic deformation in the radial direction of the upper end portion of the cylindrical body portion 32A in the drawing can be prevented by the annular protrusion 24.25.

Therefore, by stopping the impact piston 6 from receiving the impact many times, tissue destruction that occurs when the bumper 30 is frequently elastically deformed can be avoided, especially in the outer ring block 31 and the inner ring block 32.
It is possible to reliably prevent tissue destruction near the upper surface of the cylindrical body portion 32A.

In addition, when the impact piston 6 hits the center portion of the cylindrical body portion 32A of the outer ring block 31 and the inner ring block 32,
Since the bumper 30 can be bent in the radial direction, the characteristics of the bumper 30 are not lost.

Further, even if the rubber material of the bumper 30 is set for high temperature or cold weather, the durability of the bumper 30 is sufficiently ensured.

As described above, according to the present invention, even if the striking piston strongly hits the bumper during impact, it is possible to sufficiently prevent damage to the bumper.

[Brief explanation of drawings]

1 and 2 are longitudinal sectional views of essential parts of a pneumatic nailing machine showing an embodiment of the present invention, and FIG. 1 shows a state in which the striking piston is moving forward toward the bottom dead center. FIG. 2 is a diagram showing a state in which the striking piston hits the bumper. 1...Pneumatic nailer, 3...Blow cylinder, 6...Blow piston, 6b...
・Blowing piston surface, 7...Driver, 20...
...Annular groove (bumper fitting part), 21...
First annular recess, 22...Second annular groove, 30.
... Bumper, 31 ... Outer ring block, 3
2...Inner ring block, 34...Driver insertion hole.

Claims (1)

[Scope of utility model registration request] A striking piston to which a driver is integrally connected, a striking cylinder in which the striking piston is slidably and tightly fitted, and a receiver disposed at the lower end of the striking cylinder to stop the striking piston at a bottom dead center position within the striking cylinder. The bumper comprises an outer ring block and an inner ring block arranged concentrically with the block with a gap between the outer ring block and the inner ring block, the inner ring block having a driver insertion hole formed therethrough. In the tool, a first annular bumper fitting portion is fitted to the lower surface of the striking piston over the inner and outer peripheries of the upper end portion of the inner ring block, and a first annular bumper fitting portion is fitted over the inner and outer peripheries of the upper end portion of the outer ring block. A second annular bumper fitting part is provided to fit together with the bumper, and when the striking piston hits the bumper, each of the blocks is held by the fitting part, and the upper end portion of each block is elastically deformed in the radial direction. A device for preventing damage to a bumper in an impact tool, characterized in that the device is capable of preventing destruction of a bumper.