JPH08336767A - Head valve freezing preventive mechanism for pneumatic nailing machine - Google Patents

Abstract

PURPOSE: To prevent the freezing of moisture so as to operate a head valve always satisfactorily. CONSTITUTION: An annular protruding edge part 18 is circumferentially provided on the upper part outside of a cylindrical impact cylinder 3a. A head valve 6 of short cylinder shape is disposed at the upper part of the protruding edge part 18, coaxially with the impact cylinder 3a in such a way as to be vertically slidable, and an air chamber 2 stored with compressed air is formed on the outside of the head valve 6. When the lower end of the head valve 6 is separated from the protruding edge part 18, the air chamber 2 is opened to the impact cylinder 3a, and when the lower end of the head valve 6 comes in contact with the protruding edge part 18, the air chamber 2 is closed to the impact cylinder 3a to seal. In a nailing machine of such constitution, the protruding edge part 18 of the impact cylinder 3a and the external wall surface of the upper part are covered with an integral rubber cover 19.

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 which prevents malfunction due to freezing of water in compressed air generated near a head valve when compressed air is supplied to and discharged from a striking cylinder. Regarding the mechanism.

[0002]

2. Description of the Related Art In a pneumatic nailing machine in which a short cylinder-shaped head valve is provided on the outer side of an upper part of a cylindrical striking cylinder so as to be opened and closed, an air chamber 31 is opened when the head valve 30 is opened and operated as shown in FIG. The compressed air inside is rapidly supplied as shown by the arrow from the upper end opening of the striking cylinder 32 through the gap between the head valve 30 and the striking cylinder 32,
This pneumatic pressure drives the driver 34 together with the impact piston 33 in the impact cylinder to impact the nail.

However, in this way, the head valve 3
0 opens and the high-pressure compressed air in the air chamber 31 expands rapidly when passing through the gap between the head valve 30 and the striking cylinder 32, so that the temperature drop due to this adiabatic expansion strikes the moisture contained in the compressed air. The upper outer peripheral surface a of the cylinder 31 is frozen, so that the head valve for controlling the supply and discharge of the compressed air may malfunction due to a sealing failure or air leakage, resulting in problems such as insufficient driving force and idle driving. .

[0004]

An object of the present invention is to solve the above-mentioned drawbacks, and particularly to prevent the freeze of water contained in compressed air and to always operate the head valve favorably. The purpose is to provide.

[0005]

In order to achieve the above object, the antifreezing mechanism of the head valve of the pneumatic nailing machine according to the present invention has a cylindrical striking structure in which a striking piston for nail driving is slidably accommodated. An annular projecting edge is provided outside the upper part of the cylinder, and a short cylindrical head valve is arranged on the upper part of the projecting edge so as to be vertically slidable coaxially with the striking cylinder. An air chamber for storing compressed air is formed, and when the lower end of the head valve separates from the projecting edge portion, the air chamber is opened to the striking cylinder, and the lower end of the head valve contacts the projecting edge portion. In a nailing machine that closes and seals the air chamber with a striking cylinder, a projecting edge portion of the striking cylinder and an outer wall surface of an upper portion thereof are covered with an integral rubber cover.

[0006]

According to the present invention, the head valve is arranged so as to surround the upper outer side of the striking cylinder, and slides in the vertical direction during the opening / closing operation. When the head valve opens and the lower end of the head valve separates from the projecting edge of the striking cylinder to open the passage between the striking cylinder and the head valve, high-pressure compressed air is supplied into the striking cylinder.
Nail driving is performed.

As described above, when the head valve is opened and the high-pressure compressed air is supplied into the striking cylinder, the compressed air expands rapidly. Due to this adiabatic expansion, the projecting edge of the striking cylinder and the outer upper portion of the striking cylinder. The temperature near the wall decreases. However, since this part is covered with a rubber cover, even if the compressed air freezes to form ice, it does not easily adhere to rubber, which has high heat insulation and elasticity, and peels off even if it adheres. Easy to be blown off by compressed air. Therefore, frosting of the passage portion of the compressed air is favorably prevented, and therefore, the head valve can always be favorably operated without causing seal failure or air leakage in the head valve.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2 and 3 show a nailing machine according to the present invention. This nailing machine uses a high-pressure power supply (not shown) introduced into a body 1 from a compressed air supply source. An air chamber 2 for storing compressed air and a cylindrical striking cylinder / piston mechanism 3 are arranged, and compressed air is compressed into a cylindrical striking cylinder 3a by actuation of a start valve 5 and a head valve 6 which are interlocked by operating a trigger lever 4. The striking piston 3b housed in the striking cylinder 3a is reciprocated, the driver 7 integrally coupled to the striking piston 3b is driven into the nose portion 9 at the tip of the body 1, and is inserted into the injection port of the nose portion 9. The nail 8 supplied is driven to drive the nail 8 into the material to be driven.

The starting valve 5 is a valve housing 1
A cylindrical pilot valve 11 and a valve stem 12 are slidably arranged in the pilot valve 11 and the compressed air from the air chamber 2 and the pilot valve 11 and the lower bottom portion of the valve housing 10, respectively. Is supplied to urge the pilot valve 11 to move upward, and the pilot valve 11 moved upward opens the air passage 14 leading to the upper chamber 13 of the head valve 6 to the air chamber 2 and the valve housing 10 It is closed to the exhaust port 15 at the upper end of the. Then, as shown in FIG. 4, by operating the trigger lever 4 to push the valve stem 12 against the spring, the supplied compressed air is discharged from the stem guide hole 17 at the lower end of the valve housing 10, whereby the compressed air is discharged. The pilot valve 11 is moved downward to close the air passage 14 with respect to the air chamber 2 and open with respect to the exhaust port 15 at the upper end of the valve housing 10.

An annular projecting edge portion 18 is provided around the upper portion of the striking cylinder 3a, and a short cylindrical head valve 6 is vertically slid on the projecting edge portion 18 coaxially with the striking cylinder 3a. It is arranged to be movable. The projecting edge portion 18 of the striking cylinder 3a and the outer wall surface of the upper portion thereof are covered with an integral rubber cover 19.

In the initial state (states shown in FIGS. 2 and 3), the lower end of the head valve 6 is in contact with the projecting edge portion 18 and receives the compressed air in the air chamber 2. An upper chamber 13 is formed above the head valve 6, and the upper chamber 13 communicates with the start valve 5 via the air passage 14. When compressed air is being supplied to the upper chamber 13, the head valve 6 is at the lower position, and the lower end of the head valve 6 abuts on the projecting edge portion 18 to strike the air chamber 2 against the striking cylinder 3.
It is closed and sealed against a. When compressed air is discharged from the upper chamber 13 (see FIG. 4), the head valve 6
Slides upward and its lower end separates from the projecting edge portion 18 to open the passage between the striking cylinder 3a and the head valve 6, and the air chamber 2 and the striking cylinder 3a are connected.

An inner cap 21 having an exhaust hole 20 is provided above the striking cylinder 3a, and a cylinder cap 22 is arranged around the inner cap 21.
As shown in FIGS. 2 and 3, the cylinder cap 2
2 and the inner cap 21 between the exhaust chamber 23
Are formed. A throttle hole 24 is formed in the lower portion of the exhaust chamber 23, and the exhaust port 2 is provided below the throttle hole 24.
An exhaust cover 26 having a number 5 is provided. In this way, the exhaust air exhausted from the exhaust holes 20 of the inner cap 21 is configured to be exhausted to the outside via the exhaust chamber 23 formed along the inner surface of the body 1.

The exhaust hole 20 of the inner cap 21 is opened when the head valve 6 is closed, and the exhaust hole 20 is closed when the head valve 6 is opened and operated.

With the above construction, when the nail is driven, the trigger lever 4 is pulled to push in the valve stem 12 of the starting valve 5 as shown in FIG. 4, whereby the pilot valve 11 is moved downward and the air passage 14 is exhausted to the exhaust port 15. Open, the compressed air in the upper chamber 13 is discharged from the exhaust port 15 to open and operate the head valve 6, and the compressed air in the air chamber 2 is passed through the passage between the striking cylinder 3 a and the head valve 6 to strike the striking cylinder 3 a. Suddenly supplied to the striking piston 3b
To strike.

When the trigger lever 4 is returned after nailing, as shown in FIG. 2, the valve stem 12 of the starting valve 5 is moved downward by a spring, and at the same time, the pilot valve 11 is moved upward to move upward from the air passage 14 again. Compressed air is supplied to the chamber 13 to close and operate the head valve 6, and the exhaust hole 20 of the inner cap 21 is opened to supply compressed air supplied into the striking cylinder 3a to the exhaust chamber 23.
Is exhausted through the exhaust port 15. At the same time, when the nail is driven, the impact piston 3b is compressed by the operation of the impact piston 3b and stored in the blowback chamber 27 around the impact cylinder 3a, so that the impact piston 3b moves upward and returns to the initial top dead center position. The next nail drive is prepared.

Next, the head valve 6 operates as described above to open the passage between the striking cylinder 3a and the head valve 6 (see FIG. 4), and the striking cylinder 3 is depressurized by exhaust gas.
When high-pressure compressed air is supplied into a, the compressed air expands rapidly, and this adiabatic expansion causes the striking cylinder 3a.
The temperature in the vicinity of the projecting edge portion 18 and the outer wall surface of the upper part decreases. However, since this part is covered with the rubber cover 19,
Even if the moisture in the compressed air freezes to generate ice, it is difficult to adhere to rubber having high heat insulation and elasticity, and even if it adheres, it is easily peeled off, so that it is easily blown off by the compressed air. Therefore, freezing of the compressed air passage portion when the head valve 6 is opened is favorably prevented, so that the head valve 6 is always operated favorably without causing a sealing failure or air leakage. be able to.

The head valve 6 is also made of a synthetic resin having a high heat insulating property, so that the icing can be further prevented.

The head valve is not limited to the above example. For example, the structure shown in FIG. 5 may be used.

[Brief description of drawings]

FIG. 1 is a side view of a nailing machine according to the present invention.

FIG. 2 is a vertical sectional view of the above-mentioned nail driver.

3 is a vertical cross-sectional view of the main part of the body of the nail driver shown in a cross section orthogonal to FIG.

FIG. 4 is a vertical cross-sectional view of a main part when driving to drive a nail.

FIG. 5 is a sectional view showing the vicinity of a head valve of a conventional nail driver.

[Explanation of symbols]

 2 air chamber 3a striking cylinder 3b striking piston 6 head valve 18 projecting edge 19 rubber cover

Claims (1)

[Claims] 1. A cylindrical impact cylinder slidably accommodating a nail impact impact piston is provided with an annular projecting edge portion on the outer side of an upper portion, and the projecting edge portion is coaxial with the impact cylinder above the projecting edge portion. A short cylindrical head valve is arranged so as to be slidable in the vertical direction, an air chamber for storing compressed air is formed outside the head valve, and when the lower end of the head valve separates from the projecting edge portion, In a nailing machine that opens an air chamber to a striking cylinder, and a lower end of a head valve abuts on the projecting edge portion to close and seal the air chamber to the striking cylinder, a projecting edge portion of the striking cylinder and an outer wall surface above the projecting edge portion. An anti-icing mechanism for the head valve of a pneumatic nailer, which is characterized by covering the inside with an integrated rubber cover.