JP2005305578A - Impact tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impact tool capable of realizing the sure operation of a hammer to hit an anvil only once when a spindle is rotated one turn to the anvil. <P>SOLUTION: The impact tool 1 has a hammer claw part 13B projectingly attached to one end of the hammer 13 and an anvil claw part 14A which is projectingly attached to one end of the anvil 14 so as to engage with the hammer claw part 13B. The hammer claw part 13B is composed of a first hammer claw 13c and a second hammer claw 13d which is projectingly provided inward in the radial direction to the first hammer claw 13c. The anvil claw part 14A is composed of a first anvil claw 14c projectingly attached to a position capable of engaging with the first hammer claw 13c and a second anvil claw 14d projectingly attached to a position capable of engaging with the second hammer claw 13d. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for improving the tightening force of an impact tool.

  In general, an electric impact tool employs a method of hitting an anvil twice for each rotation of a spindle. This is because the hammer and the anvil are provided with two claws symmetrically so that an unbalanced load is not applied to the hammer and the anvil at the time of impact.

  The method of hitting twice in one rotation of the spindle is suitable for an efficient work when the number of hits per unit time is large, such as a work of tightening screws on wood. However, in many cases, it is better to increase the hitting energy per hit rather than increase the number of hits, such as loosening the tightened bolt or tightening the high tension bolt. As a method for increasing the energy per one hit, a countermeasure has been taken such as increasing the hammer minor speed or increasing the spindle rotation speed to increase the rotation speed of the hammer. However, these methods have a problem in that the current flowing through the motor increases and the load on the motor increases. For this reason, when the motor is changed to a specification having a larger physique by one rank, problems such as an increase in weight and an increase in price occur. In particular, a tool for powering a storage battery has a problem that the working time is shortened due to an increase in current.

  Patent Document 1 has the following description. That is, by setting the maximum axial fitting length of the hammer claw and anvil claw to 35% or less of the maximum axial stroke of the cam mechanism composed of the spindle cam and the steel ball, one rotation per one rotation of the spindle or once It is possible to set the hit mode equal to or less than the hit, and the energy per hit can be increased without increasing the load on the motor.

Japanese Utility Model Publication No. 6-669

  In the configuration described in Patent Document 1, since the fitting length in the axial direction changes depending on the settings of the spring load, the weight of the hammer, the inertia, and the like, it is not always possible to hit one anvil per one rotation of the spindle.

  An object of the present invention is to solve the above-mentioned problems and to provide an impact tool that ensures the operation of the hammer hitting the anvil only once when the spindle makes one rotation with respect to the anvil.

  A motor that is a drive source, a speed reduction mechanism that decelerates and transmits the rotational force of the motor, and a substantially cylindrical spindle that rotates when the rotational force of the speed reduction mechanism is transmitted to the outer periphery of the spindle. The axial direction is a spindle having a first cam groove recessed at a predetermined angle, and a substantially cylindrical hammer inserted into the spindle so as to be rotatable and movable in the axial direction. A hammer having a second cam groove recessed at a predetermined angle with respect to the axial direction at a position corresponding to the first cam groove, and a hammer claw projecting at one end of the hammer, A substantially cylindrical anvil provided in front of the spindle so as to be rotatable approximately coaxially, an anvil claw portion projecting from one end of the anvil so as to be engageable with the hammer claw portion, and the other end of the anvil A tip tool holding portion provided in the And an anvil that is provided in the first and second cam grooves and is engaged between the first and second cam grooves, and between the spindle and the hammer. The hammer claw portion has a first hammer claw and a second hammer claw projecting radially inward with respect to the first hammer claw. The anvil claw portion is provided with a first anvil claw protruding at a position engageable with the first hammer claw and a second protruding at a position engageable with the second hammer claw. And an anvil claw.

  In this way, the first hammer claw can be engaged only with the first anvil claw, and the second hammer claw can be engaged only with the second anvil claw. Therefore, regardless of the timing of hitting, the hammer hits the anvil only once when the spindle makes one rotation with respect to the anvil.

  According to the first aspect of the present invention, the hammer strikes the anvil only once when the spindle makes one rotation with respect to the anvil regardless of the timing of the impact which changes depending on the spring load, the weight of the hammer and the inertia. it can. Therefore, it is possible to provide an impact tool in which the operation of the hammer hitting the anvil only once when the spindle makes one rotation with respect to the anvil can be provided.

  Hereinafter, the right side of FIG. 1 will be described as the front of the tool, and the left side of FIG. 1 will be described as the rear of the tool.

  The overall configuration of the impact tool 1 will be described with reference to FIG.

  The configuration of the impact tool 1 is roughly composed of an outer frame portion 2, a motor 3 as a drive source, a switch 4 for controlling power supply from a power source (not shown) to the motor 3, and a deceleration for reducing the rotational force of the motor 3. The mechanism part 5 and the impact mechanism part 11 which converts the rotational force of the speed reduction mechanism part 5 into impact torque generated intermittently.

  The deceleration mechanism 5 will be described with reference to FIG.

  The speed reduction mechanism unit 5 includes a pinion gear 6 fixed to the motor 3, an idle gear 7 that meshes with the pinion gear 6, an idle gear 7 that is rotatably supported by a spindle 12 described later via a needle roller 10, A substantially ring-shaped internal gear 8 that circumscribes and meshes with the gear 7, and is configured to be non-rotatably supported by an inner cover 9, which will be described later, and to be unrotatable and non-movable in the axial direction by the outer frame portion 2. The inner cover 9 is supported, and the substantially cylindrical spindle 12 is rotatably provided on the inner cover 9 via a bearing (not shown).

  Although the rotational force of the motor 3 is transmitted from the pinion gear 6 to the idle gear 7 and the internal gear 8, the internal gear 8 is supported by the outer frame portion 2 through the inner cover 9 so as not to rotate. 7 revolves while spinning. When the idle gear 7 revolves, the spindle 12 rotates through the needle roller 10. In this way, the transmission of rotational force from the pinion gear 6 to the spindle 12 is decelerated according to the ratio between the number of teeth of the pinion gear 6 and the number of teeth of the internal gear 8.

  The impact mechanism unit 11 will be described with reference to FIGS.

  The impact mechanism unit 11 is provided with the above-described substantially cylindrical spindle 12, a substantially cylindrical hammer 13 that is inserted into the spindle 12 so as to be rotatable and movable in the axial direction, and is rotatably provided substantially coaxially in front of the spindle 12. A substantially cylindrical anvil 14, a ball 15 interposed between the spindle 12 and the hammer 13, and a spring 16 provided between the spindle 12 and the hammer 13 to press the hammer 13 forward.

  The spindle 12 has a first cam groove 12a that is recessed on the outer periphery of the spindle 12 at a predetermined angle with respect to the axial direction. The hammer 13 extends in the axial direction at one end of the hammer 13 and a second cam groove 13a that is recessed at a predetermined angle with respect to the axial direction at a position corresponding to the first cam groove 12a on the inner periphery of the hammer 13. And a hammer claw portion 13 </ b> B projecting from the head. The cross sections of the first cam groove 12a and the second cam groove 13a have a semicircular shape slightly larger in curvature than the outer diameter of the ball 15, and extend in a V shape with a predetermined angle with respect to the axial direction of the spindle 14. . The ball 15 is provided in the first cam groove 12aa and the second cam groove 13a, and engages with the first cam groove 12a and the second cam groove 13a. The anvil 14 includes an anvil claw portion 14 </ b> A that protrudes at one end of the anvil 14 so as to be able to engage with the hammer claw portion 13 </ b> B and a tip tool holding portion 14 b provided at the other end of the anvil 14. Have.

  With this configuration, the hammer 13 is always pressed forward against the spindle 12, but the hammer 13 moves forward by the engagement of the first cam groove 12 a and the second cam groove 13 a with the ball 15. Is restricted, and the first cam groove 12a and the second cam groove 13a are stably stopped at a position where the V-shaped vertices coincide with each other. When torque is applied so that the hammer 13 and the spindle 12 are relatively rotated, the hammer 13 and the spindle 12 are not relatively rotated until the torque overcomes the pressing force of the spring 16, and the torque is When the pressing force of 16 is overcome, the hammer 13 moves backward while rotating with respect to the spindle 12. If the application of torque is stopped, the hammer 13 immediately returns to the original position by the pressing force of the spring 16.

  The hammer claw portion 13B includes a first hammer claw 13c and a second hammer claw 13d that protrudes radially inward with respect to the first anvil claw. The heights of the first hammer claw 13c and the second hammer claw 13d are high enough to engage with the anvil claw portion 14A when the hammer 13 is located at the foremost position. The first hammer claw 13c and the second hammer claw 13d are substantially fan-shaped when viewed from the axial direction, and can restrict a first anvil claw 14c and a second anvil claw 14d, which will be described later, to be rotatable by a predetermined angle. Thus, the size occupied in the circumferential direction of the first hammer claw 13c and the size occupied in the circumferential direction of the second hammer claw 13d are substantially the same. The distance from the center of the rotating shaft to the outer peripheral side of the second hammer claw 13d is larger than the distance from the center of the rotating shaft to the first hammer claw 13c.

  The anvil claw portion 14A protrudes at a position where it can be engaged with the first anvil claw 14c and the second hammer claw 13d. Anvil claw 14d. The heights of the first anvil claw 14c and the second anvil claw 14d are high enough to engage with the hammer claw portion 13B when the hammer 13 is located in the foremost position. The first anvil claw 14c and the second anvil claw 14d are substantially rectangular and have substantially the same width. The distance from the center of the rotating shaft to the outer peripheral side of the second anvil claw 14d is set to be larger than the distance from the center of the rotating shaft to the inner peripheral side of the first anvil claw 14c.

  With this configuration, when the hammer claw portion 13B and the anvil claw portion 14A are relatively rotated, the first hammer claw 13c and the second anvil claw 14d are not engaged with each other. The second hammer claw 13d and the first anvil claw 14c are not engaged. Therefore, when the hammer 13 and the anvil 14 relatively rotate one time, the hammer claw portion 13B and the anvil claw portion 14A can be engaged only once.

  The operation of the impact tool 1 will be described with reference to FIGS.

  First, a not-shown tip tool attached to the tip tool holding portion 14b is engaged with a material to be tightened (not shown). Next, when the switch 4 is operated, the motor 3 starts rotating, and the rotational force is decelerated by the decelerating mechanism unit 5 and transmitted to the impact mechanism unit 11.

  The hammer 13 and the spindle 12 rotate with little resistance until the hammer claw portion 13B and the anvil claw portion 14A are engaged. When the hammer claw portion 13B and the anvil claw portion 14A are engaged, when the tightening torque is small, the hammer 13, the spindle 12 and the anvil 14 rotate together to perform a tightening operation.

  When the tightening torque is large, the hammer 13 retreats while rotating with respect to the spindle 12 along the trajectory of the first cam groove 12a and the second cam groove 13a against the pressing force of the spring 16. . When the hammer 13 is retracted from a predetermined position, the engagement between the hammer claw portion 13B and the anvil claw portion 14A is released, and the hammer 13 immediately returns to the original position by the pressing force of the spring 16. And hammer claw part 13B hits anvil claw part 14A in the direction of rotation. When the tightening torque continues to be large, the striking operation is repeated, and intermittent impact torque is repeatedly transmitted to the anvil 14 to perform the tightening operation.

  As described above, when the hammer 13 and the anvil 14 rotate relatively once, the hammer claw portion 13B and the anvil claw portion 14A can be engaged only once, so the locus of the hammer 13 is shown in FIG. As shown. FIG. 6 is a diagram showing the relationship between the claws during the striking operation. The left side in the figure is the forward rotation direction, and the upper side in the figure is the rear of the tool.

  As shown in the state of A in FIG. 6 or as shown in FIGS. 2 and 3, the first hammer claw 13c (or the second hammer claw 13d) is replaced by the first anvil claw 14c (or the second anvil claw 14d). Blow. Next, the hammer 13 retreats while being reversely rotated by the repulsive force from the anvil 14, and then advances again by the pressing force of the spring 16 and is accelerated in the forward rotation direction. As shown in the state B in FIG. 6 or as shown in FIGS. 4 and 5, the first hammer claw 13c (or the second hammer claw 13d) and the second anvil claw 14d (or the first anvil claw 14c) are halfway through. ) Are overlapped in the axial direction, but they pass through without colliding because they are provided at positions that do not overlap in the radial direction. Again, as shown in the state A in FIG. 6 or as shown in FIGS. 2 and 3, the first hammer claw 13c (or the second hammer claw 13d) is replaced by the first anvil claw 14c (or the second anvil claw). Strike 14d).

  Depending on the setting of the load of the spring 13, the weight and inertia of the hammer 13, and the rotational speed of the spindle 12, the timing of impact may be slightly shifted, but at least as compared with the conventional configuration in which impact is performed twice per one rotation of the spindle. Energy per hit can be increased. This is suitable for work requiring a large tightening torque.

The partial structure sectional view showing the impact tool by the present invention. Cross-sectional view of the main part structure showing a state during impact of the impact tool according to the present invention AA sectional view of FIG. Cross-sectional view of the main part structure showing the state of the impact tool according to the present invention when the hammer advances BB sectional view of FIG. The figure which shows the locus | trajectory of the hammer of the impact tool by this invention

Explanation of symbols

1 Impact tool
2 Outer frame
3 Motor
4 switch
5 Deceleration mechanism
6 Pinion gear
7 Idle gear
8 Internal gear
9 Inner hippo
10 Needle roller
11 Impact mechanism
12 Spindle 12a First cam groove
13 Hammer 13a Second Cam Groove 13B Hammer Claw
13c first hammer claw 13d second hammer claw
14 anvil 14A anvil claw part 14b tip tool holding part
14c first anvil claw 14d second anvil claw
15 balls
16 Spring

Claims (1)

A motor as a drive source;
A speed reduction mechanism that decelerates and transmits the rotational force of the motor;
A spindle having a substantially cylindrical shape that rotates by transmitting the rotational force of the speed reduction mechanism, and has a first cam groove recessed at a predetermined angle with respect to the axial direction on the outer periphery of the spindle;
A substantially cylindrical hammer that is inserted into the spindle so as to be rotatable and axially movable, and is recessed at a predetermined angle with respect to the axial direction at a position corresponding to the first cam groove on the inner periphery of the hammer. A hammer having a second cam groove and a hammer claw projectingly provided at one end of the hammer;
A substantially cylindrical anvil provided in front of the spindle so as to be substantially coaxially rotatable, wherein the anvil claw is provided at one end of the anvil so as to be engageable with the hammer claw, and the other end of the anvil. An anvil having a tip tool holding portion provided in
A ball provided in the first and second cam grooves and engaged with the first and second cam grooves;
A spring provided between the spindle and the hammer and pressing the hammer forward;
In impact tools having
The hammer claw portion includes a first hammer claw and a second hammer claw protruding radially inward from the first hammer claw,
The anvil claw portion includes a first anvil claw protruding at a position engageable with the first hammer claw and a second anvil protruding at a position engageable with the second hammer claw. Nails,
An impact tool characterized by comprising: