JPH0152153B2 - - 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 race 2 and a piston 3. An air chamber 4 formed on one side, an air passage 5 that guides compressed air to the air chamber 4, and an air passage 5 that is slidably inserted into the case 2 and formed separately from the piston 3.
It consists of a piston pin 6 that receives more load, and an actuating jig 7 located at the tip of the case 2.
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 transferred via the piston pin 6 to the operating jig 7.
The cap 8 is driven into the front axle hub 10 by applying the tip of the operating jig 7 that receives this hammering load to the flange 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 Resonant sound of the 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, but the background noise of the chipping hammer tool itself is Since it accounts for a large proportion of the overall noise, an effective way to reduce noise is to reduce the noise of the chipping hammer itself.

In order to reduce noise, the applicant of this patent previously proposed that a piston and a piston pin are integrated to form a piston 11 with a shank, as shown in FIG. A low-noise chipping hammer has been proposed in which a hard rubber pad 13 is attached to the tip of the part 12. (Patent Application No. 57-157421 (Japanese Patent Application No. 59-47172)
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 area between the piston and the piston pin is removed, eliminating the noise generation source described in a above, and a hard rubber pad 13 is installed at the contact area between the piston pin and the operating jig.
, the noise from the noise source b mentioned above can be significantly alleviated. Furthermore, by making the case 14 itself a resin product, vibration transmission to the handle is attenuated and alleviated, noise is suppressed and operability is improved.

However, although the low-noise chipping hammer shown in FIG. 2 has significantly reduced noise compared to the chipping hammer shown in FIG.
Therefore, there is a problem that the length becomes long and the workability when holding the chipping hammer by hand is reduced, so it is desired to reduce the size and especially shorten the length.

In addition, the low-noise chipping hammer shown in Figure 2 is
Since the case 14 consists of an integrated case,
There is a problem in that the impact during hammering is directly transmitted from the cap holder 15 to the hands and arms via the case 14, and further reduction of vibration and noise transmitted to the hands and arms is desired.

Furthermore, in the low-noise chipping hammer shown in FIG. 2, the pad 13 and the cap holder 15 are pressed against the press-fit cap 17 and the workpiece 18 by constantly pressing the hammer by hand, thereby preventing the pad 13 and the cap holder 15 from bouncing due to the repulsive force of vibration during the chipping stroke. Since the control is performed manually, there is a problem in that the chipping hammer moves, making the work difficult. Therefore, it is desirable to prevent the swing between the workpiece and the chipping hammer.

The present invention satisfies this demand, that is, reduces the length, size, and weight of a low-noise chipping hammer, and reduces the noise caused by the impactful vibration of the press-fitting hammer and the vibration transmitted to the hands and arms. The purpose of the present invention is to further reduce the number of chips and to prevent the movement between the workpiece and the chipping hammer during press-fitting.

The low-noise chipping hammer of the present invention, which meets this purpose, has a piston with a shank that has a piston part slidably inserted into the cylinder, a shank part that projects from the cylinder, and a cap holder that is formed separately from the cylinder in the shank part. The cap holder is movably mounted, and a spring member is interposed between the piston bed provided at the tip of the shank portion and the cap holder to press the cap holder against the piston head. Here, a holder rubber made of an elastic body is interposed between the cap holder and the piston bed, and an O-ring is fitted between the outer periphery of the piston head and the inner periphery of the cap holder. A damper rubber consisting of a projectile is interposed between them.

The low-noise chipping hammer of the present invention constructed as described above is improved as follows compared to the low-noise chipping hammer shown in FIG.

First, as shown in Figure 2, a piston head and holder rubber are used instead of hard rubber pads, and the length of the shank is limited to the tipping stroke necessary for press-fitting the press-fit cap, thereby avoiding an increase in the overall length due to the addition of pads. , the length of the chipping hammer can be shortened, and the weight can also be reduced accordingly. Therefore, the work when supporting the chipping hammer with one hand and performing the hammering work is facilitated.

Next, regarding the transmission of vibrations to hands and arms, in the chipping hammer shown in FIG. The structure is such that impact vibrations are directly transmitted to the hands and arms via the case 14. However, in the chipping hammer of the present invention, the cap holder and cylinder are separated, so the impact of the cap holder is not directly transmitted to the cylinder.
Vibration to hands and arms is significantly reduced. In addition, when a damping rubber is interposed between the cap holder and the cylinder, or when the cap holder is made of hard synthetic resin, the interference noise between the cap holder and the cylinder is reduced, and shock mitigation is promoted.

Furthermore, regarding the prevention of the chipping hammer from swinging when press-fitting the press-fit cap into the workpiece,
A spring member interposed between the piston head and the cap holder softens the reaction force on the hand and arm of the axial pressing force of the press-fit cap against the workpiece, and prevents bouncing by performing a buffering action. There is.

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

FIG. 3 shows a low-noise chipping hammer according to an embodiment of the present invention. In the figure, reference numeral 21 denotes a handle for supporting the chipping hammer by hand.
A cylinder 22 is connected to 1. cylinder 2
A cylindrical hole 23 extending in the axial direction of the cylinder 22 is formed in the cylinder 22, and a piston portion 25 of a piston 24 with a shank is slidably inserted into the hole 23. There is a hole 2 on the handle 21 side of the piston 25.
A chamber 27 is formed in the handle 21, and compressed air pressure is cyclically applied to the chamber 27 through an air passage 28 formed in the handle 21.
A hammering load is applied to the piston 25.
A shank portion 26 of the shank-equipped piston 24 protrudes from the cylinder 22 toward the side opposite to the handle 21. A bushing 29 is fitted into a hole 23 at the outlet of the shank portion 26 from the cylinder 22, and the shank portion 26 is slidably inserted through this bushing 29.

A piston head 30 is attached to the protruding end of the shank portion 26 of the piston 24 with a shank. To attach the piston head 30 to the shank part 26, the tip of the shank part 26 is formed into a tapered taper 31, and the piston head 30 is formed with a taper hole 32 that tightly engages with the taper surface 31. 31 into the tapered hole 32, and then insert the pin 33 extending perpendicularly to the axial direction of the shank portion 26 into the piston head 30 and the shank portion 2.
This is done by inserting it through both of the parts 6 and fixing them to each other.

A cap holder 34 is attached to the shank portion 26 of the piston 24 with a shank so as to be slidable in the axial direction with respect to the shank portion 26. The cap holder 34 has a holder portion 36 for driving the press-fit cap 35 at one end, a cylindrical portion 37 extending from the holder portion 36 toward the cylinder 22 at the center, and a cylindrical portion 37 screwed to the cylindrical portion 37 at the other end. It has a bottom cap 38. The piston head 30 is slidably inserted into the cylindrical portion 37 of the cap holder 34.

A coil spring 39 as a spring member is interposed between the piston head 30 and the bottom cap 38, and urges the cap holder 34 toward the cylinder 22 with respect to the shank portion 26.
Due to this bias, the back surface of the holder portion 36 of the cap holder 34 is pressed against the piston head 30 at the tip of the shank portion 26. A holder rubber 40 serving as a buffer member is embedded in the surface of the holder portion 36 of the cap holder 34 that contacts the piston head 30.

The outer peripheral surface of the piston head 30 extends along the inner peripheral surface of the cylindrical portion 37 of the cap holder 34, and an O-ring 41 is fitted onto the outer peripheral surface of the piston head 30. The O-ring 41 and the inner peripheral surface of the cylindrical portion 37 are in a sliding relationship. Further, an O-ring 42 is fitted on the outer periphery of the shank portion 26 of the piston 24 with a shank, and also inside the bottom cap 38. A damping lever 44 made of a rubber member or the like is interposed between the bottom cap 38 screwed to the cap holder 34 and the bush 29 mounted on the cylinder 22. The bottom cap 38 is constructed from a hard synthetic resin, such as an acetal copolymer.

In addition, 35 in FIG. 3 is a press-fit cap 35, which is used as a workpiece for the front axle hub 43 of an automobile.
It is something that is driven into.

Next, the operation of the low-noise chipping hammer shown in FIG. 3 having the above structure will be explained.

First, regarding the operation of the hammering, see chamber 27.
Apply compressed air pressure cyclically to piston 2
The hammering load applied to the piston 25 is transmitted to the cap holder 34 via the shank portion 26 and the piston head 30 formed integrally with the piston 25, and the press-fit cap 3 held by the cap holder 34 is
5 into the workpiece, the axle hub 43.

Next, regarding the noise reduction effect,
Noise is reduced compared to the conventional chipping hammer shown in FIG. That is, by integrating the conventional piston and piston pin shown in FIG. 1 to form the piston 24 with a shank, there is no contact between the piston and the piston pin, and the cap holder
By embedding the holder rubber 40 in the cap holder 4, there is no metal contact between the piston head 0 and the cap holder 34, so noise generation is eliminated or reduced, and noise and vibration are significantly reduced.

Moreover, it is shorter and lighter than the chipping hammer shown in FIG. That is, in the chipping hammer shown in FIG. 3, the length of the shank portion 26 of the piston with shank 24 is limited to the chipping stroke necessary for press-fitting the press-fit cap 35, and by attaching the hard rubber pad 13 as shown in FIG. This prevents the period from being extended. In the chipping hammer of the present invention, the piston head 30 replaces the hard rubber pad 13 and the holder rubber 40 embedded in the cap holder 34 reduces the overall length while maintaining an excellent cushioning effect. Furthermore, since the connection between the piston head 30 and the shank portion 26 is a tapered connection, the connection portion will not be damaged in strength regardless of the connection over a short length, and the cap holder can be reliably removed from the piston with shank 24. The hammering load is transmitted to 34.

Furthermore, compared to the chipping hammer shown in FIG. 2, the transmission of impact from the chipping hammer body to the hand and arm when the chipping hammer is activated is reduced. In the chipping hammer shown in FIG. 3, the bottom cap 38 of the cap holder 34 and the cylinder 22 are separated. Therefore, the impact generated in the cap holder 34 when the press-fit cap 35 is driven is not directly transmitted from the cap holder 34 to the cylinder 22. A damper lever 4 is installed between the bottom cap 38 and the bush 29 attached to the cylinder 22 side.
4 is interposed, the bottom cap 38 does not directly hit the bush 29, and the transmission of the impact is blocked or buffered by the damper lever 44. Furthermore, since the bottom cap 38 is made of hard resin, the transmission of impact is further attenuated.

Further, the swinging of the chipping hammer when press-fitting the press-fit cap 35 is also alleviated. Cap holder 34
The piston head 3 is moved by the coil spring 39.
Since the holder rubber 40 is buried in the pressed part, the press-fit cap 35 is pressed by the hammering load of the piston 24 with a shank.
The reaction force when press-fitting into the workpiece 43 is the spring 3
9 and the holder rubber 40,
The transmission to the hands and arms is alleviated.

Since the O-ring 41 is fitted to the piston head 30, the axes of the cap holder 34 and the piston with shank 24 are aligned, and the grinding noise between the piston head 30 and the cap holder 34 is reduced.

As described above, the low-noise chipping hammer of the present invention uses a piston with a shank to eliminate contact between the piston part and the shank part,
By separating the case from the cylinder and cap holder, there is no direct vibration transmission path from the cap holder to the cylinder, and the cap holder is pressed by a spring against the piston head attached to the tip of the shank of the piston with a shank. The effects of reducing noise generation, alleviating the transmission of the impact of the hammer to the hands and arms, and preventing the chipping hammer from bouncing.

[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 previously proposed by the applicant of this patent, and FIG. 3 is a sectional view of a low-noise chipping hammer according to an embodiment of the present invention. Figure. 22... Cylinder, 24... Piston with shank, 25... Piston part, 26... Shank part,
27...chamber, 30...piston head, 31...
Tapered surface, 32... Tapered hole, 34... Cap holder, 35... Press-fit cap, 38... Bottom cap, 39... Spring, 40... Holder rubber, 41... O-ring, 42... O-ring,
44...Danpara rubber.

Claims (1)

[Scope of Claims] 1. A piston with a shank, in which a piston part and a shank part are integrated, is slidably inserted into a cylinder, and the tip of the shank part protrudes from the cylinder; A cap holder, which is formed separately from the cylinder and positioned in front of the cylinder, is attached to a portion protruding from the cylinder of the shank, and is movably attached to the shank, and the piston head and cap holder are fixed to the tip of the shank. A low-noise chipping hammer characterized in that a spring member for biasing the cap holder in the cylinder direction is inserted between the two to press the cap holder against the piston head. 2. The low-noise chipping hammer according to claim 1, wherein a holder rubber made of a bullet is interposed between the cap holder and the piston head. 3. The low-noise chipping hammer according to claim 1, wherein the cap holder is made of hard synthetic resin. 4. The low-noise chipping hammer according to claim 1, wherein a damping rubber made of an elastic body is interposed between the cap holder and the cylinder. 5. The low-noise chipping hammer according to claim 1, wherein an O-ring is fitted between the outer circumference of the piston head and the inner circumference of the cap holder.