JP2001179657A - Idle driving prevention device for impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the service life of a product in an idle driving prevention device for impact tool. SOLUTION: The end surface 4a of an intermediate element 4 hits a buffering member 7 and then hits the inner wall 6a of a front cover 6 while giving compressive deflection to the buffering member 7, therefore the advance speed of the intermediate element 4 is damped. As a result, the rebound speed of the intermediate element 4 can be damped, so that an impact element 3 will not retract nor cover an air vent hole 8, thus preventing idle driving.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing continuous striking motion (hereinafter referred to as idle striking) of a striker at no load, such as an electric hammer and a hammer drill.

[0002]

2. Description of the Related Art Conventionally, in order to prevent idle hitting, when the tip tool is separated from a work material, a striker moves to a non-strike position, and air between the striker and the piston is released into an air vent hole provided in a cylinder. It was possible to get in and out of the vehicle, and the structure that eliminated the suction force of the piston was adopted. However, when the striking force is increased, the bounce speed of the meson after the striker hits the meson is high. Close the vent hole. There was a problem that this was repeated and the blanking occurred.

[0003]

In the conventional structure as described above, the meson hits the inner wall of the front cover continuously due to the idling, and thus there is a problem that the life of the front cover and the main body is significantly reduced. Was. SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems of the prior art and improve the life of the front cover and the main body.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a buffer member on an inner wall of a front cover where an opening end of a hole for accommodating a tip tool shaft of a meson abuts to attenuate a forward speed of the meson, and a bounce speed of the meson. Is achieved by preventing the striker from retracting and preventing the striker from blocking the air vent hole.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional side view showing one embodiment of the impact tool according to the present invention, and FIG. 2 is a partial cross-sectional side view showing one embodiment when a meson of the impact tool according to the present invention is advanced. In FIG. 1, the rotational force of the electric motor is converted into a reciprocating motion of a piston 2 by a crankshaft (not shown) and a connecting rod 1. The striker 3 is moved by an air spring between the piston 2 and the striker 3, and the strike is transmitted to the tip tool 5 via the meson 4. A front cover 6 is located in front of the meson 4 (left side in the figure), and a circumferential groove 6b is provided in an end face of the front cover 6 on the meson 4 side at a portion located inside the outer periphery of the meson 4. The buffer member 7 is embedded in the groove 6b. In addition, inside the groove 6b where the buffer member 7 is provided,
An inner wall 6a with which the meson 4 comes into contact when the cushioning member 7 is compressed to some extent is provided. In such a configuration, when the tip tool 5 is separated from the work material, as shown in FIG. 2, the tip tool 5, the meson 4, and the striker 3 (to the left in the figure)
Advance. At this time, the end face 4a of the meson 4 collides with the cushioning member 7 embedded in the inner wall of the front cover 6, and the cushioning member 7
While giving compression deflection to the inner wall 6a of the front cover 6. By this buffer member 7, the collision energy of the meson 4 is absorbed to some extent, and the bounce speed of the meson 4 is reduced. The decelerated meson 4 does not have enough energy to retreat the striker 3, so that the striker 3 does not block the air vent hole 8, so that the blank strike can be prevented.
In the present embodiment, not all of the collision energy of the meson 4 is absorbed by the elastic force of the cushioning member 7, but after the meson 4 is absorbed to some extent, the inner wall 6a of the front cover 6
In the configuration. This is because if the buffer member 7 buried in the inner wall 6a of the front cover 6 is made to protrude larger than the inner wall 6a, all the collision energy of the meson 4 is absorbed by the elastic force of the buffer member 7. This is because the buffer member 7 is deteriorated early due to the repetitive stress applied to the buffer member 7, and the life of the buffer member 7 is shortened. To avoid this,
The amount of compression of the cushioning member 7 (that is, the inner wall 6 of the front cover 6)
(amount of protrusion of the buffer member 7 embedded in the inner wall 6a)
Is configured so that the rebound speed of the meson 4 is equal to or less than the energy for retreating the striker 3,
It is desirable to maintain the life of the device. That is, the amount of protrusion of the buffer member 7 with respect to the inner wall 6a is larger than the amount of protrusion required for at least the energy of the rebound of the meson 4 to be equal to or less than the energy for retreating the striker 3, and has a predetermined life (other than that). It is desirable that the protrusion is configured to be smaller than the protrusion amount that can maintain the life of the main body itself caused by the element. Further, in the present embodiment, inside the cushioning member 7,
Although the inner wall 6a in contact with the meson 4 is provided, the buffer member 7 may be inside and the inner wall 6a in contact with the meson 4 may be outside.

[0006]

According to the present invention, a buffer member is provided on the inner wall of the front cover where the opening end of the hole for accommodating the tip tool shaft of the meson abuts, so that the blanking can be prevented. The service life can be improved.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view showing an embodiment of a striking tool according to the present invention.

FIG. 2 is a partial cross-sectional side view showing one embodiment of the impact tool according to the present invention when a meson is advanced.

[Explanation of symbols]

1 is a connecting rod, 2 is a piston, 3 is a striker, 4 is a meson, 5 is a tip tool, 6 is a front cover, 7 is a cushioning member, and 8 is an air vent hole.

Claims (2)

[Claims] 1. A striking tool having a hammer reciprocated by a piston reciprocating in a cylinder, a meson hit by the reciprocating motion of the hammer, and a tip tool hit by the reciprocating motion of the meson. An inner wall of the front cover which abuts on the tip-tool-side end face of the meson, provided with a buffer member for attenuating the forward speed of the meson and reducing the bouncing speed of the meson, to prevent the hitting tool from hitting without hitting. apparatus. 2. The shock-absorbing member is configured to protrude from the inner wall of the front cover, and the amount of protrusion is necessary so that the energy due to the bounce of the meson becomes less than the energy for retreating the striker. 2. The hitting prevention device for an impact tool according to claim 1, wherein the projecting amount is larger than the projecting amount and smaller than the projecting amount of the buffer member itself capable of maintaining a predetermined life.