JPS6327152B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tool having a hammering mechanism, and particularly to a low-noise chipping hammer.

A chipping hammer is used to drive a tire cap into the front axle hub of a tire. As shown in FIG. 1, a conventional chipping hammer includes a handle 1, a case 2 integrally connected to the handle 1, a piston 3 slidably inserted into the case 2, and a piston 3 inside the case 2. an air chamber 4 formed on one side of the piston 3; an air passage 5 that guides compressed air to the air chamber 4; Piston pin 6 that receives the load and case 2
The actuating jig 7 is supported at the tip of the actuating jig 7. Then, compressed air is periodically applied to the air chamber 4 via the air passage 5, and the cyclic pressure load applied to the piston 3 is transmitted to the operating jig 7 via the piston pin 6, and the operating jig 7 receives this hammering load. The cap 8 is driven into the front axle hub 10 by applying the tip of the cap 8 to the collar 9 of the cap 8.

However, the conventional chipping hammer described above has the following sources of noise.

a Due to contact between piston 3 and piston pin 6.

b Due to contact between the piston pin 6 and the operating jig 7.

c Due to contact between the operating jig 7 and the collar 9 of the cap 8.

d Due to contact between the collar 9 of the cap 8 and the front axle hub 10.

e. Loud noise from front axle hub 10.

f Chipping hammer exhaust sound.

In this way, the noise accompanying the chipping hammer includes the noise of the chipping hammer tool itself as shown in a, b, c, and f, and the noise of the workpiece side as shown in d and e. Since noise accounts for a large proportion of the overall noise, it is effective to reduce the noise of the chipping hammer tool itself, and the present invention also aims to reduce the noise of the chipping hammer itself, especially the above-mentioned a, b, The purpose of this is to suppress the noise caused by the noise source c.

In order to achieve this object, in the noise-reducing chipping hammer of the present invention, a piston and a piston pin are integrated to form a piston with a shank, and a hard rubber pad is attached to the tip of the shank of the piston with a shank. installed. The case into which the piston is slidably inserted is made of a resin product such as acetal copolymer. By adopting such a configuration, the conventional contact portion between the piston and the piston pin is removed, eliminating the noise generation source described in a above, and a hard rubber pad is interposed in the contact portion between the piston pin and the operating jig. Therefore, the noise from the noise source b mentioned above is significantly reduced. Furthermore, by making the case itself a resin product, vibration transmission to the handle is attenuated and alleviated, noise is suppressed and operability is improved.

Preferred embodiments of the low-noise chipping hammer of the present invention will be described below with reference to the drawings.

FIG. 2 shows an embodiment of the low-noise chipping hammer of the present invention. In the figure, 11 is a handle of a chipping hammer tool, and a case 12 is attached to the handle 11.
are formed continuously and integrally. Case 1
2 is made of a hard synthetic resin, for example an acetal copolymer. The case 12 is a cylindrical body,
A piston 13 is slidably inserted inside. An air chamber 14 is formed on one side of the piston 13 in the case 12, and the air chamber 14 has a handle 11 and an air passage 15 formed in the case 12.
are communicating. Compressed air is periodically sent to the air chamber 14 through an air passage 15, and the piston 13
It is now possible to apply air pressure cyclically. The piston 13 has a shank portion 16 extending on the side opposite to the air chamber 14, and the piston 13 with the shank portion 16 has a shape in which the conventional piston 13 and the piston pin 6 shown in FIG. 1 are integrated. are doing. The shank part 16 is case 1
It is slidably supported by a pusher 18 fixed to 2. An operating jig 17 is supported at the tip of the case 12, and the operating jig 17 is connected to the cap 1.
It has a shape suitable for applying a load to the flange portion 21 of the cap 19 when driving the cap 9 into the front axle hub 20, that is, it is composed of a bottom plate 22 and a cylindrical portion 23 projecting from the bottom plate 22 in a cylindrical shape. As shown in FIG. 3, a pad 24 made of hard rubber is attached to the tip of the piston shank portion 16. The hard rubber pad 24 has a substantially truncated conical shape and is attached to the shank portion 16 with its large diameter end facing the operating jig 17 side. Hard rubber pad 24/
7 to the shank portion 16, a tapered hole 25 is provided in the hard rubber pad 24/7, the diameter of which becomes smaller toward the back, and the tip 26 of the shank portion 16 is formed into a tapered shape. shaped hole 25
This is done by wedged together and prevented from coming off with a pin 27 extending perpendicularly to the axis.

The detachment prevention structure using the pin 27 may be replaced by a cushion resilient connection as shown in FIG. In the structure shown in FIG. 4, a flange 28 is provided at the tip of the shank portion 16 and projects radially outward.
The attached tip is inserted into a hole 29 formed in the hard rubber pad 24 and having a relatively large diameter. A snap spring 30 is fitted to the outlet of the hole 29 of the hard rubber pad 24 to prevent it from coming off.
A push guide 31 is slidably inserted therein while being supported by the snap spring 30. The bush guide 31 faces the flange 28, and a compression coil spring 32 is interposed between the bush guide 31 and the flange 28.
In addition, in the method shown in FIG. 4, the pad 24 and the operating jig 17 may be integrated. At the time of this integration, the pad 24 and the operating jig 17 may be integrated by tapered press-fitting as shown in FIG. In the example shown in FIG. 5, the shank portion 1 of the operating jig 17
A tapered protrusion 33 is provided on the 6 side surface, and the protrusion 33 is press-fitted into a tapered hole 34 formed on the end surface of the pad 24 on the operating jig 17 side. This press-fitting method is advantageous in terms of maintenance compared to a one-piece method.

In the low-noise chipping hammer configured as described above, compressed air pressure is cyclically applied to the air chamber 14, and the hammering load applied to the piston 13 is transferred to the case 12 through the shank portion 16 formed integrally with the piston 13. It is applied elastically to the operating jig 17 at the tip.

Therefore, the contact area between the piston and piston pin, which was one of the sources of noise in the past, has been structurally eliminated by combining the two into a piston with a shank, and this area is a source of noise. It will never occur.

Further, since a hard rubber pad 24 is attached to the tip of the shank portion 16, the piston shank portion 16 makes contact with the operating jig 17 via the hard rubber pad 24, and metal-to-metal contact occurs between rubber and metal. The sound of the hit suddenly becomes smaller.

This noise reduction effect was tested in a factory where the background noise is approximately 65 dB when actually driving the cap 19 into the front axle hub 20, and it was found that the noise of the chipping hammer of the present invention was 81 to 83 dB compared to the 91 to 93 dB generated by the conventional chipping hammer. It was found that a noise reduction of approximately 10 dB can be achieved. The measurements are based on A scale level measurements using an ordinary sound level meter at a distance of 30 cm from the side of the air hammer.

In addition, since the case 12 is made of acetal copolymer, the hammering vibration transmitted from the operating jig 17 to the handle 11 via the case 12 is reduced compared to the case of a conventional metal case, which improves the working environment. is improved.

Further, when the hard rubber pad 24 and the operating jig 17 are integrated as shown in FIG. 5, the contact between the rubber pad 24 and the operating jig 17 is also eliminated, so that noise reduction is further promoted.

The above-mentioned chipping hammer is used as an example of a chipping hammer for driving a cap into a front axle hub of an automobile, but the field of application of the low-noise chipping hammer of the present invention is not limited to this, and the same or similar hammers may be used. It is also possible to apply the present invention to a pneumatic tool having a ring mechanism, and the present invention includes such a case.

As described above, the low-noise chipping hammer of the present invention is constructed by integrating the conventionally separate piston and piston pin into a piston with a shank, and a rubber pad is attached to the tip of the shank. In addition to being able to remove the contact area between the piston and the piston pin, which was a source of noise, it is also possible to reduce the noise at the contact area between the piston pin and the operating jig, resulting in a significant overall noise reduction. is obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional chipping hammer, FIG. 2 is a sectional view of a low-noise chipping hammer of the present invention, FIG. 3 is a partially enlarged sectional view of the device shown in FIG. 5 is a partial cross-sectional view of a low-noise chipping hammer according to another embodiment of the device shown in FIG. 2;
This figure is a partial sectional view of a low-noise chipping hammer according to another embodiment of the present invention from the apparatus shown in FIGS. 2 and 4. 11...handle, 12...case, 13...piston,
14...Air chamber, 15...Air passage, 16...Shank portion, 17...Operation jig, 19...Cap, 20...Front axle hub, 24...Hard rubber pad, 2
6...Tapered part.

Claims (1)

[Claims] 1. Compressed air is periodically actuated to a piston slidably inserted into a case, and the load applied to the piston is transmitted via a piston pin to an operating jig movably supported by the case. In a pneumatic tool having a hammering mechanism that obtains a striking force using compressed air, the piston and the piston pin are integrated to form a piston with a shank, and the piston with a shank has an elastic pad made of a hard rubber pad at the tip of the shank. 1. A low-noise chipping hammer characterized in that a striking force applied from a shank portion of a piston with a shank is transmitted to an operating jig via an elastic material made of a hard rubber pad. 2. The low-noise chipping hammer according to claim 1, wherein the resilient material made of the hard rubber pad is directly fixed to the tip of the shank portion of the piston with shank. 3. The low-noise chipping hammer according to claim 1, wherein the resilient material made of the hard rubber pad is pressed onto the tip of the shank portion of the piston with a shank by a compression coil spring. 4. The low-noise chipping hammer according to claim 3, wherein the resilient material made of the hard rubber pad and the operating jig are integrally connected. 5. The low-noise chipping hammer according to claim 1, wherein the case is made of a hard synthetic resin material.