JPH0796474A - Impact rotating tool - Google Patents

Abstract

PURPOSE:To easily and securely change the tightening force by providing an operating means to move the striking part in the radial direction of a hammer to change the striking position of an output shaft by the striking part in the radial direction. CONSTITUTION:When a cylinder 6 is in the retracted position, and a movable body 23 is located inside a larger inner diameter part 61 of the cylinder 6, the distance (radius) from the center of a hammer 2 to a striking part 24 is large. When the cylinder 6 is advanced, the movable body 23 is located inside a smaller inner diameter part 62, and pushed back against a spring 22 toward the center side of the hammer 2, and the radius from the center of the hammer 2 to the striking part 24 becomes small. Thus, the striking impact given to an output shaft 4 is smaller in the case where the radius of the striking part 24 is small than in the case where the radius of the striking part 24 is large, and the tightening force is also reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact rotary tool such as an impact wrench or an impact driver used for tightening and loosening bolts, nuts or screws.

[0002]

2. Description of the Related Art An impact rotary tool such as an impact wrench or an impact driver performs a tightening work by applying a hitting impact by a hammer driven to rotate to an output shaft. An example is shown in FIG. The rotation of the motor 1 is reduced in speed by a speed reducer 10 composed of a planetary speed reduction mechanism and transmitted to the drive shaft 11. A cylindrical hammer 2 is freely rotatably arranged on the outer periphery of the drive shaft 11.
1, a V-shaped cam groove 31 formed on the outer circumference, a cam groove 32 formed on the inner peripheral surface of the hammer 2, both cam grooves 31,
With the cam 3 consisting of the ball 33 engaging with 32,
The movement of the drive shaft 11 and the hammer 2 in the axial direction and the movement around the axis are restricted. The hammer 2 is urged toward the output shaft 4 by the spring 5, and the tip end surface of the hammer 2 is engaged with an anvil portion 40 projecting laterally from the rear end of the output shaft 4. A section 24 is provided.

When no load is applied to the output shaft 4 to which the driver bit or socket is mounted at the tip, the rotation of the drive shaft 11 is transmitted to the hammer 2 via the cam 3 and the striking portion 24 of the hammer 2 is also transmitted. Is transmitted to the output shaft 4 by the engagement of the anvil portion 40 with. When the load applied to the output shaft 4 increases, relative rotation occurs between the hammer 2 and the drive shaft 11 within the range allowed by the cam 3, and at this time, the hammer 2 is guided by the cam 3 and the hammer 2 moves. Spring 5
When the striking portion 24 disengages from the striking portion 24 and the anvil portion 40 and the striking portion 24 gets over the anvil portion 40,
The hammer 2 is guided by the cam 3 by the restoring force of the spring 5 and moves forward to shockly engage the striking portion 24 with the anvil portion 40, and to apply a rotational force to the output shaft 4.

[0004]

As described above, the impact rotary tool which gives the output shaft 4 the rotation due to the impact of impact is as follows.
Although a higher tightening force can be obtained than when the output shaft is directly rotated by the motor deceleration output, when tightening small diameter bolts and nuts, they are often overtightened and damaged. .

For this reason, there is provided a device in which the tightening force can be set low by changing the rotational speed of the hammer, that is, the rotational speed of the motor for rotational driving. However, if the number of rotations is reduced to reduce the tightening force, the work speed becomes slower, the efficiency becomes poor, and the hammering of the output shaft by the hammer becomes difficult to operate normally.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an impact wrench capable of easily and reliably changing the tightening force.

[0007]

SUMMARY OF THE INVENTION According to the present invention, however, in an impact rotary tool that applies a rotational force to the output shaft by impacting the output shaft with a hammer that is rotationally driven, the impact part of the output shaft of the hammer is arranged in the radial direction of the hammer. It is characterized in that it is provided with externally operable operation means for moving the striking part in the radial direction of the hammer to change the striking position of the output shaft by the striking part in the radial direction. There is.

[0008]

According to the present invention, the tightening force can be changed by changing the radial position of the striking portion of the hammer by operating the operating means without lowering the rotation of the motor.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the illustrated embodiments.
The hammer 2 here is exactly the same in operation as when a striking impact is applied to it. Without the movable body 23 which is slidable in the radial direction with respect to the hammer 2.
3 is provided with a striking portion 24.

That is, as shown in FIG. 3, the outer surface of the hammer 2 is provided with a plurality of recesses 20 which are open also on the front surface side at equal intervals in the circumferential direction, and on both sides of each recess 20. Guide grooves 21 and 21 are formed in the wall. A movable body 23 having a striking portion 24 on the front surface and guide projections 25 engaging with the guide groove 21 on both side surfaces is slidably arranged in the recess 20 in the radial direction of the hammer 2.

On the outer periphery of the hammer 2, a cylinder 6 is provided with a drive shaft 1
0 and the hammer 2 are arranged concentrically. A slide button 66 located on the outer surface of the housing 7 of the impact rotary tool is connected to a locking groove 64 on the outer peripheral surface of the cylinder 6 via a locking member 65, and the hammer 2 is moved by moving the slide button 66 back and forth. It slides axially forward and backward, and its inner peripheral surface has different inner diameters on the front end side and the rear end side in the axial direction, and the large inner diameter portion 61 on the front end side and the small inner diameter on the rear end side. The portion 62 and the portion 62 are connected by a tapered surface 63.

The movable body 23 provided on the hammer 2 is urged outward by a spring 22 arranged between the movable body 23 and the bottom surface of the recess 20 to move the spherical body 26 arranged on the outer surface into the cylinder 6. It is in contact with the peripheral surface. Reference numeral 27 in FIG. 3 denotes a hemispherical concave portion for holding the spherical body 26 formed on the outer surface of the movable body 23,
28 is a hole for receiving the spring 22 provided in the movable body 23.

Now, when the cylinder 6 is in the retracted position as shown in FIG. 1 and the movable body 23 is located inside the large inner diameter portion 61 of the cylinder 6, the striking portion 24 is located from the center of the hammer 2. The distance (radius) to is large. Moreover, when the cylinder 6 is moved forward,
As shown in FIG. 2, since the movable body 23 is located inside the small inner diameter portion 62 and is pushed into the center side of the hammer 2 against the spring 22, the radius from the center of the hammer 2 to the striking portion 24 is large. Becomes smaller.

Here, the energy that the hammer 2 can give to the output shaft 4 depends on the mass and angular velocity of the hammer 2 and the radius of the striking portion 24 from the center of the hammer 2, and as shown in FIG. As shown in FIG. 2, when the radius of the striking portion 24 is smaller than that when the striking portion 24 has a large radius, the striking impact applied to the output shaft 4 becomes smaller and the tightening force also decreases. Even when considered as torque, the smaller the radius of the striking portion 24, the smaller the transmission torque. Even if the angular velocity of the hammer 2 is not reduced by changing the rotation speed of the motor 1, the tightening force and the rotational torque transmitted to the output shaft 4 can be reduced.

The large inner diameter portion 61 and the small inner diameter portion 62 of the cylinder 6 both have an axial length longer than the axial movement stroke of the hammer 2 required to give a striking impact. In either case, the spherical body 26 does not interfere with the axial movement of the hammer 2.

[0016]

As described above, in the present invention, the tightening force can be changed by changing the radius of gyration of the striking part by operating the operating part, which may hinder the operation. It is possible to easily and accurately change the tightening force and to tighten a wide range of screws without lowering the rotation speed.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a cross-sectional view of the same when the tightening force is changed.

FIG. 3 is an exploded perspective view of the above.

FIG. 4 is a cutaway side view of a conventional example.

[Explanation of symbols]

 2 hammer 4 output shaft 23 movable body 24 striking part

Claims (2)

[Claims] 1. In an impact rotary tool for applying a rotational force to an output shaft by striking the output shaft with a hammer driven to rotate, the striking part of the output shaft of the hammer is movable in the radial direction of the hammer, and the striking part is also provided. An impact rotating tool comprising an operating means that can be operated externally to move the tool in the radial direction of the hammer to change the hitting position of the output shaft by the hitting portion in the radial direction. 2. The striking portion is provided on a movable body slidably disposed in a radial recess provided on the hammer, and has a large inner diameter portion and a small inner diameter portion on the outer circumference of the hammer. 2. The impact rotary tool according to claim 1, wherein a cylinder, in which the movable body is in contact with the inner surface of the lever by a spring bias, is arranged so as to be axially movable by the operating means.