JP2002066941A - Impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the workability and operability of an impact tool having an impact mechanism part for generating impact force by making use of oil pressure. SOLUTION: Balls 12 are disposed in a cam groove provided in an outer circumference of a shaft 4 for transmitting the power and an inner circumference of a coupling 8 turnable on the axis of the shaft 4, the coupling 8 is locked by the balls 12 by pressing the coupling 8 to the opposite side of a drive motor 2 by an elastic body 10, and a tip of the shaft 4 is pivotably supported by a joint 13 for transmitting the power from the coupling 8 to the impact mechanism part 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact tool for screw tightening provided with an impact mechanism for generating an impact force by utilizing the compression of oil.

[0002]

2. Description of the Related Art A conventional impact tool for tightening a screw includes a low-noise type impact mechanism that generates an impact force by using an air motor as a power source and compressing oil (see Japanese Patent Publication No. 8-5015). ),
There is an impact mechanism (see JP-A-2-224981) which uses an electric motor as a drive source and instantaneously generates an impact force. A torsion spring is disposed on the outer periphery of the latter impact mechanism. This reduces the recoil that occurs when an impact force is generated.

[0003]

In an impact tool using an impact mechanism that instantaneously generates an impact force by using compression of oil, the rotation of the impact mechanism instantaneously decelerates when an impact force is generated, and the speed reduction mechanism portion is used. Since the motor connected to the motor decelerates instantaneously, the inertia force of the motor is transmitted to the operator's hand as a reaction. In the case of an impact tool using an air motor as a drive source to reduce the reaction, a means for reducing the reaction by air supplied to the drive motor is incorporated. On the other hand, in the case of an impact tool using an electric motor as a drive source, the recoil is reduced by disposing the torsion spring on the outer periphery of the impact mechanism as described above. However, in the configuration in which the torsion spring is provided, the outer circumference of the impact mechanism becomes large,
As a result, the impact tool itself becomes large, so that it is impossible to reduce the size of the impact tool, and there is a problem that workability and operability in a narrow place are reduced.

[0004] In any of the above-described configurations, the recoil can be reduced. However, since the instantaneous impact force is generated only in the rotation direction and no force is generated in the axial direction, the cross screwdriver is used. When a screw with a cross-shaped hole is tightened using a bit, there is a problem that the bit is detached from the cross-shaped hole of the screw due to an instantaneously generated impact force, thereby impairing workability.

[0005] An object of the present invention is to solve the above-mentioned problems and to provide an impact tool excellent in operability and workability.

[0006]

An object of the present invention is to provide a drive motor, a speed reduction mechanism for transmitting rotational power of the drive motor,
An impact tool equipped with an impact mechanism that instantaneously generates an impact force by an output from the speed reduction mechanism,
A ball is arranged in a cam groove provided in an outer periphery of a shaft for transmitting power and an inner periphery of a coupling rotatable on an axis of the shaft, and the coupling is pressed by an elastic body toward a counter-drive motor side. This is achieved by supporting the tip of the shaft with a joint that transmits the power from the coupling to the impact mechanism.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The impact tool according to the present embodiment will be described below with reference to FIGS. 1 is the motor 2
An impact tool 4 having a built-in reduction mechanism 3 is mounted on a reduction gear 5 of the reduction mechanism 3, and is supported by a bearing 6 and has a cam groove 7 on the outer periphery at the distal end. Elastic body 10 which is rotatably mounted on the axis of the shaft 4 and is made of a coil spring, a disc spring, rubber, or the like.
Ball 12 having a convex portion 11 which is pressed forward by the shaft to transmit the power from the shaft 4 and which is embedded in the cam grooves 7, 9
The coupling 13 is stopped by a bearing 15 of a case 14 that covers the outer peripheral members, and the coupling 13 is
It has a hole 16 for receiving power from
No. 5015 discloses an impact mechanism 17 (not shown in detail) which has a square hole 18 for transmitting power, and is a joint for pivotally supporting the rear bridge of the impact mechanism 17 and the tip of the shaft 4. The output shaft 1 of the impact mechanism 17
9 is supported by a bearing 20 at the tip of the case 14, and 2
Reference numeral 1 denotes a cross-shaped screwdriver bit 21 for tightening a cross-recessed screw, which is attached to the output shaft 19.

In such a configuration, when a load is applied to the bit 21 attached to the output shaft 19 of the impact mechanism 17 by rotating the motor, the impact mechanism 17 instantaneously generates an impact force. The instantaneous reaction of the impact force is transmitted to the coupling 8 via the joint 13.
When the reaction is transmitted to the coupling 8, the cam groove 7 provided on the inner periphery is formed.
And the elastic body is pushed through the ball 12 along the cam groove 9 on the outer periphery of the shaft while being pushed to the speed reduction mechanism side, thereby causing a relative angle shift between the impact mechanism 17 and the speed reduction mechanism 3. Therefore, even if the rotation of the impact mechanism 17 is rapidly decelerated, the amount of deceleration of the motor is reduced, and the inertia generated when the coupling 8 is pushed out to the deceleration mechanism and moves at the same time as the reaction of the impact force is reduced. The reaction force of the force is transmitted to the bit 21 via the joint 13 and the impact mechanism 17.
The bit 21 is transmitted to the tip, so that the bit 21 does not easily come off from the cross hole of the screw. When the impact force of the impact mechanism section 17 decreases, the coupling 8 pushed out toward the speed reduction mechanism section becomes
Due to the compressive force stored in the elastic body 10, it is extruded while rotating in the rotation direction toward the impact mechanism along the cam groove 7 on the outer periphery of the shaft and the cam groove 9 provided on the inner periphery of the coupling, and the relative angle is shifted. The impact mechanism 17 again.
Can generate an impact force. 4 and 5
The configuration shown in FIGS. 6 and 7 may be different from the configuration shown in FIG.

With such a configuration, when an impact force is generated, the coupling 8 can be interlocked via the joint 13 to alleviate the recoil and press the bit 21 against the cross hole at the same time. Can be reduced. Therefore, a force in the axial direction is also generated while alleviating the instantaneous reaction of the impact force, thereby improving workability and operability.

[0010]

According to the present invention, a ball is arranged in a cam groove provided in an outer periphery of a shaft for transmitting power and an inner periphery of a coupling rotatable on the axis of the shaft, and the coupling is made of an elastic material. By pressing against the anti-drive motor side, the ball is locked, and furthermore, the tip of the shaft is axially supported by a joint that transmits the power from the coupling to the impact mechanism, so that the shaft in the axial direction when an impact force is generated By generating a force and reducing the recoil, an impact tool having excellent operability and workability can be provided.

[Brief description of the drawings]

FIG. 1 is a partially longitudinal side view showing an impact tool according to the present invention.

FIG. 2 is a partially longitudinal side view showing a state of an impact tool when an impact force is generated according to the present invention.

FIG. 3 is a partially omitted longitudinal side view showing a shaft having a hole and a coupling having a cam groove according to the present invention.

FIG. 4 is a longitudinal sectional view showing a cam groove on the inner periphery of the coupling according to the present invention.

FIG. 5 is a front view of FIG. 4;

FIG. 6 is a longitudinal sectional view showing a long groove on the inner circumference of the coupling according to the present invention.

FIG. 7 is a front view of FIG. 6;

FIG. 8 is a side view showing a state of a cam groove on an outer periphery of a shaft according to the present invention.

FIG. 9 is a side view when FIG. 8 is rotated 90 degrees.

FIG. 10 is a side view when FIG. 9 is rotated by 90 degrees.

[Explanation of symbols]

1 is an impact tool, 2 is a motor, 3 is a reduction mechanism, 4
Is a shaft, 8 is a coupling, 9 is a cam groove, 10 is an elastic body, 12 is a ball, 13 is a joint, 17 is an impact mechanism, and 22 is a long groove.

Claims (3)

[Claims] 1. An impact tool comprising a drive motor, a speed reduction mechanism to which rotational power of the drive motor is transmitted, and an impact mechanism that instantaneously generates an impact force by an output from the speed reduction mechanism. A ball is arranged in a cam groove provided in an outer periphery of a shaft for transmitting power and an inner periphery of a coupling rotatable on the axis of the shaft, and the coupling is pressed by an elastic body toward the anti-drive motor. An impact tool, wherein the tip of the shaft is pivotally supported by a joint for transmitting the power from the coupling to the impact mechanism unit. 2. A cam groove is provided on an outer periphery of the shaft, a long groove is provided on an inner periphery of the coupling rotatable on an axis of the shaft, and a ball is arranged between the long groove and the cam groove. The impact tool according to claim 1, wherein: 3. A hole for arranging the ball is provided on an outer periphery of the shaft, and a cam groove is provided on an inner periphery of the coupling rotatable on an axis of the shaft, and the cam groove and the hole are further provided. 2. The method according to claim 1, wherein the ball is disposed between the two.
Impact tool described.