JP2002046078A - Impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration and sound insulating mechanism for an impact tool which uses a cam and steel balls to move a hammer back and forth. SOLUTION: The impact tool is so formed that when the hammer is moved back by a maximum amount, the end face 5a of the hammer is brought into contact with an elastic body 13a before the steel balls 7 engaging the hammer 5 with a spindle 3 collide against a cam end 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration and sound-proof mechanism for an impact tool in which a hammer moves forward and backward using a steel ball, a spindle cam and a hammer cam.

[0002]

2. Description of the Related Art A conventional impact tool will be described with reference to FIGS. FIG. 3 shows a striking mechanism of an impact wrench used when tightening and loosening bolts and the like using electric or air as a driving source. It is configured to transmit the power to the spindle 3 via the reduction unit 2. In addition, spindle 3
A hammer 5 is formed with a spindle cam 4 and a hammer 5 with a hammer cam 6. The hammer 5 is urged in a direction A by a spring 8 via a steel ball 7 to rotate and reciprocate. Further, the hammer 5 is provided with a hammer claw 9, which is engaged with an anvil claw 11 provided on an anvil 10.

Next, the operation of the striking mechanism at the time of bolt tightening will be described with reference to FIG. When the tightening of the bolts is started, the spindle 3, the hammer 5, and the anvil 10 start rotating integrally (pattern A). When the bolt tightening torque increases, the rotation of the anvil 10 stops, and the spindle 3 and the hammer 5 are displaced in the rotation direction. The hammer 5 moves along the lead of the spindle cam 4 with the spindle shaft 3 as a sliding portion. The spring 8 is retracted while compressing, and the hammer 5 and the anvil 10 are disengaged from each other (pattern B). Then, after the hammer 5 retreats to the maximum, the hammer 5 moves forward while rotating along the lead of the spindle cam 4 by the urging force of the spring 8, and applies a striking force to the anvil 10 (pattern C).
~ D ~ E).

[0004] In the striking mechanism operating as described above,
An elastic body 13b shown in FIG. 4 is provided between the hammer 5 and the spindle 3, thereby regulating the maximum retreat amount (Lb) of the hammer 5 and preventing the steel ball 7 from dropping. I have.

[0005]

In the above-mentioned conventional construction, when the hammer is retracted to the maximum when the bolt is tightened (when the hammer moves maximum in the direction B), the steel ball has a dimensional relationship in which the steel ball collides with the cam end. Because of this, the noise caused by the impact force when the steel ball hit the cam end,
There is a problem that vibration occurs.

An object of the present invention is to provide an impact tool which is excellent in usability by solving the above problems and reducing vibration and noise.

[0007]

The above object is achieved by a driving unit,
A spindle rotated by a drive unit, a hammer movable in the axial direction of the spindle, a hammer cam formed on the hammer, a spindle cam formed on the spindle, a steel ball engaged with the spindle cam and the hammer cam,
A spring that constantly biases the hammer toward the opposite side of the drive unit, and an elastic body that is disposed on the end surface of the spindle and that comes into contact with the end surface of the hammer when the hammer is fully retracted. Is achieved by bringing the end face of the hammer into contact with the elastic body before hitting the cam end.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An impact tool according to the present embodiment will be described with reference to FIGS. Figure 1 shows electricity,
FIG. 3 shows a striking mechanism of an impact wrench used when tightening and loosening bolts and the like using air as a driving source, and rotational force from a driving unit incorporated in a housing 1 is reduced via a speed reduction unit 2. To the spindle 3. A spindle cam 4 is formed on the spindle 3 and a hammer cam 6 is formed on the hammer 5. The hammer 5 is urged in the direction A by a spring 8 via a steel ball 7 to rotate and reciprocate. Further, the hammer 5 is provided with a hammer claw 9, which is engaged with an anvil claw 11 provided on an anvil 10.

Next, the operation of the striking mechanism at the time of bolt tightening will be described with reference to FIG. When the tightening of the bolts is started, the spindle 3, the hammer 5, and the anvil 10 start rotating integrally (pattern A). When the bolt tightening torque increases, the rotation of the anvil 10 stops, and the spindle 3 and the hammer 5 are displaced in the rotation direction. The hammer 5 moves along the lead of the spindle cam 4 with the spindle shaft 3 as a sliding portion. The spring 8 is retracted while compressing, and the hammer 5 and the anvil 10 are disengaged from each other (pattern B). Then, after the hammer 5 retreats to the maximum, the hammer 5 moves forward while rotating along the lead of the spindle cam 4 by the urging force of the spring 8, and applies a striking force to the anvil 10 (pattern C).
~ D ~ E).

In the striking mechanism operating as described above,
An elastic body 13 a shown in FIG. 2 is disposed between the hammer 5 and the spindle 3. Before the steel ball 7 collides with the cam end 15, the hammer end face 5 a and the elastic body 13 a
By contacting (contacting), the collision force is reduced.
The shape of the contact surface of the elastic body 13a is the same as that of the hammer end surface 5a, and the outer diameter of the contact surface is not restricted by the washer 14. ) Can be deformed in the radial direction on the contact surface of the elastic body 13a, and can be dispersed and alleviated.
Vibration can be reduced and the life of the elastic body 13a can be extended.

[0011]

According to the present invention, the hammer end face is brought into contact with the elastic body before the steel ball engaging the spindle with the hammer at the maximum retreat of the hammer before colliding with the cam end, whereby vibration and noise are reduced. Can be suppressed. Also, by making the shape of the contact surface of the elastic body in contact with the hammer end face the same, and deforming the contact surface of the elastic body in the radial direction,
Since the collision force at the time of the maximum retraction of the hammer can be reduced, the life of the elastic body can be improved.

[Brief description of the drawings]

FIG. 1 is a partially omitted longitudinal side view showing a striking mechanism of an impact wrench according to the present invention.

2A and 2B show an elastic body according to the present invention, wherein FIG. 2A is a cross-sectional view and FIG. 2B is a plan view.

FIG. 3 is a partially omitted longitudinal side view showing a hitting mechanism of a conventional impact wrench.

4A and 4B show a conventional elastic body, wherein FIG. 4A is a cross-sectional view and FIG. 4B is a plan view.

FIG. 5 is a state diagram showing an operation of a striking mechanism during bolt tightening.

[Explanation of symbols]

1 is a housing, 2 is a reduction gear, 3 is a spindle, 4 is a spindle cam, 5 is a hammer, 5a is a hammer end face, 6 is a hammer cam, 7 is a steel ball, 8 is a spring, 9 is a hammer claw, 10 is an anvil, 11 Is an anvil claw, 12 is a hammer case, 13a is an elastic body, 13b is an elastic body, 1
4 is a washer and 15 is a cam end.

Claims (2)

[Claims] A driving unit; a spindle rotated by the driving unit; a hammer movable in an axial direction of the spindle; a hammer cam formed on the hammer; a spindle cam formed on the spindle; A steel ball that engages the cam and the hammer cam, and a spring that constantly urges the hammer toward the anti-drive unit side,
An impact tool further comprising an elastic body disposed on an end face of the spindle and contacting the end face of the hammer when the hammer retreats to a maximum, before the steel ball collides with a cam end, the end face of the hammer is elastically deformed. An impact tool characterized by being configured to be in contact with a body. 2. The impact tool according to claim 1, wherein the shape of the contact surface of the elastic body is the same as the shape of the end face of the hammer, and the contact surface of the elastic body is deformed in a radial direction.