JP2001219383A - Rotation striking tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve working efficiency by eliminating double contact of a click at the time of loosening work of a screw on a rotation striking tool. SOLUTION: A rotation striking tool to add a rotating strike by making (colliding) a click of a hammer 11 contact with a click of an anvil from a peripheral direction by making the hammer 11 to be fitted on an outer periphery of a spindle 8 carry out composite motion of relative revolution of a specified angle and axial direction movement (advance and retreat) is constituted of a V grove 14 forming a rotation striking mechanism 12 to make the hammer 11 carry out the composite motion on an outer periphery of the spindle 8, a ball 13 to be moved along the V groove 14 and an engagement recessed part 16 formed on an inner peripheral surface of the hammer 11 and having an inverse V shaped engagement recessed surface 15 to be engaged with the ball 13. Additionally, a lead angle α1 of an inclined groove 14c on the loosened side of the V groove 14 and a lead angle β1 of an inclined surface 15c on the loosened side of the engagement recessed surface 15 are respectively set smaller than lead angles α, β on the fastening side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary hitting tool called an impact wrench or an impact driver, and more particularly to a rotary hitting tool capable of applying a hit in a rotational direction to firmly tighten a screw.

[0002]

2. Description of the Related Art A conventional rotary impact tool, for example, an impact wrench, has a spindle which is rotated by an electric motor as a driving source via a power transmission mechanism comprising a planetary gear train. A hammer for applying a rotary impact to the anvil is fitted rotatably and movably in the axial direction. The anvil is rotatably arranged on the same axis as the spindle, and a socket, which is a tool for tightening bolts, can be attached to the tip of the anvil. A ball (steel ball) is interposed between the spindle and the hammer. The ball has a V-shaped V-shaped side view semi-circular cross section inclined to the rotation axis formed on the outer periphery of the spindle, and an inner periphery of the hammer. It is sandwiched between an engaging concave portion having an inverted concave V-shape in side view and a semicircular cross section formed on the surface. Thus, when the hammer rotates relative to the spindle, the hammer moves forward or backward in the axial direction with respect to the spindle. That is, the hammer is configured to perform a combined movement of the circumferential movement and the axial movement at a predetermined angle with respect to the spindle.

The hammer is pressed by a compression spring in the forward direction (anvil side). Therefore, the retreating operation of the hammer is performed against the pressing force of the compression spring. On the other hand, two claws are provided on the front end face of the hammer with a phase difference of 180 degrees in the circumferential direction. Correspondingly, a phase difference of 180 degrees is set on the axial end face of the anvil with the circumferential direction. And two claws are provided. Then, the hammer rotates and advances by the pressing force of the compression spring, and its claw abuts (collides) with the claw of the anvil from the circumferential direction, whereby the anvil is hit in the rotational direction. As a result, the bolt is rotationally hit from the anvil via the socket, and the screw is tightened. Then, the hammer after the impact retreats in the axial direction while being rotated in the direction opposite to the rotation direction of the spindle against the compression spring by the repulsive force at the time of the impact. After retreating, the screw spring is rotated again by the pressing force of the compression spring to move forward, and thereafter, the same tightening operation is repeated to complete the screw tightening. An impact wrench having such a structure is disclosed in, for example, Japanese Utility Model Publication No. 55-169368.

In the conventional impact wrench described above, the hammer that moves relative to the spindle to apply a rotary impact to the anvil is formed by a V-groove provided on the spindle and an engaging concave surface provided on the hammer. The movement will be regulated. FIG. 5A is an exploded view showing a V-shaped groove (two grooves are provided at a phase difference of 180 degrees in the circumferential direction) provided in the conventional spindle 51, and FIG. FIG. 4B is an exploded view of an engagement recess 55 (two recesses having a phase difference of 180 degrees in the circumferential direction) 55 having an engagement recess 54 provided on the hammer 53. The V-shaped groove 52 has one inclined groove 52a extending from the valley for tightening and the other inclined groove 52b for loosening, and the engaging concave surface 54 has one inclined surface 54a extending from the valley for tightening and the other inclined surface 54b. Is provided for loosening. As shown in the drawing, in the conventional V groove 52, the lead angles (inclination angles with respect to a straight line orthogonal to the rotation axis of the spindle 51) α of the inclined grooves 52a and 52b on the tightening side and the loosening side are set to be the same,
Further, the engagement concave surface 54 also has engagement concave surfaces 54a on the tightening side and the loosening side.
54b have the same lead angle β.

[0005]

When a rotary hammer is applied to the anvil by a hammer, the amount of rebound of the hammer differs between the time of tightening and the time of loosening. This is because the repulsive force at the time of tightening is large and the repulsive force at the time of loosening is small. FIG.
In (A), the relative position of the hammer 55 with respect to the spindle 51 is indicated by a two-dot chain line, the position C is a rotational hitting position (forward position), and the position D is a retreat position due to rebound during tightening. And the position E is a retracted position due to rebound when loosened. Hammer 53 repelled by rotary blow
The slopes 54a and 54b of the engagement concave surface 54 are
The ball 56 is moved by engaging with the inclined groove 5 of the V groove 52.
It moves along 2a and 52b. That is, the hammer 5
3 retreats in the axial direction while rotating in the opposite direction with respect to the spindle 51. At this time, there is a difference in the amount of retreat as shown in the figure due to the difference in the repulsive force between the time of tightening and the time of loosening. Occurs. Therefore, at the time of tightening in which the repulsive force acting on the hammer is large, the ball 56 retreats to the groove end of the inclined groove 52a on the tightening side, and then the operation proceeds to the next striking operation. The inclined groove 52b on the loose side of the ball 56
Cannot return to the end of the groove, and the operation shifts to the next striking operation from the middle of the inclined groove 52b. Note that the spring force of the compression spring is appropriately set in consideration of buffering of an impact when the ball comes into contact with the end of the groove at the time of tightening with a large repulsive force, and cannot be set smaller than necessary. . On the other hand, FIG. 6 schematically shows an operation mode in which the claw 57 of the hammer 53 retreated by repulsion shifts to the next striking operation during the bolt loosening operation. At the time of loosening, in which the amount of retreat is smaller than that at the time of tightening, the striking operation is started early, and the phase difference of 180 degrees has occurred since the claws 57 of the hammer 53 abut the claws 58a of the anvil 58 to which the previously struck. There is a possibility that a phenomenon of hitting the next claw 58b provided, that is, a so-called double hit of the claw may occur. That is, in the conventional impact wrench, when the operation of loosening the bolt is performed, the impact energy is not effectively transmitted to the anvil due to the double hit of the claw, and the operation efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a rotary hitting tool that eliminates the hit of a claw twice when loosening a screw, thereby improving working efficiency. Is to improve.

[0007]

In order to achieve the above object, a rotary impact tool according to the present invention has a configuration as described in each of the claims. Therefore, claim 1
According to the invention of the above, the ratio of the amount of axial movement to the amount of rotation of the hammer is configured to perform a composite movement that is smaller on the loosening side than on the tightening side. The amount of rotation of the moving hammer can be made as large as that at the time of tightening. For this reason, it is possible to increase the time required for the hammer to move forward in the axial direction to give a hit for the next hit, that is, to advance to the position where the claw of the hammer hits the claw of the anvil. As a result, while the hammer moves to the position at which it hits, the claw of the hammer passes over the upper surface of the anvil that has hit at the time of the previous hitting operation without touching the claw of the anvil and hits the next claw. be able to. Thus, the hit of the nail twice is eliminated. For this reason, the impact energy of the hammer is transmitted to the anvil in a concentrated manner at one time, and an efficient impact action is added.

According to the second aspect of the present invention, the loosening lead angle of one or both of the V groove and the engagement concave surface in the rotary impact mechanism is set smaller than the tightening side lead angle. As a result, as in the case of the first aspect, it is possible to eliminate the hit of the claw twice and to apply an efficient impact action to the anvil.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is applied to an impact wrench used for tightening or loosening bolts as an example of a rotary impact tool. 1 is a partially cutaway side view of the impact wrench, FIG. 2 is an enlarged sectional view of a main part,
FIG. 3 is an exploded view, in which (A) shows the V-groove of the spindle and (B) shows the engaging recess of the hammer. FIG. 4 is a schematic diagram for explaining an operation mode of the claw of the hammer at the time of loosening. As shown in FIG. 1, the impact wrench includes a reversible electric motor (not shown) as a drive source housed on the rear side (left side in the figure) of the housing 1, and an output shaft 2 of the electric motor. Is transmitted to the spindle 8 via the planetary gear train 3 as a power transmission mechanism.

As shown in FIG. 1, the planetary gear train 3 includes a pinion gear (sun gear) 5 provided on the output shaft 2,
It comprises a plurality of planetary gears 6 meshing with the pinion gear 5 and an internal gear 7 meshing with the planetary gears 6, and these are incorporated in a gear box 4 fixed to the housing 1. The internal gear 7 is fixed to the gear box 4, and each planetary gear 6 is rotatable via a support shaft 6 a on an overhanging carrier portion 9 integrally formed at the rear end (left side in the drawing) of the spindle 8. It is supported by.
The spindle 8 is arranged on the same axis as the output shaft 2, and an end on the output shaft 2 side is rotatably supported by the gear box 4 by a bearing 10.

A hammer 11 for applying a rotary impact force to the anvil 18 is fitted around the outer periphery of the distal end side (right side in the figure) of the spindle 8, and between the hammer 11 and the spindle 8, a hammer 11 is attached to the spindle 8. A rotary impact mechanism 12 for performing a combined movement of a circumferential movement (relative rotation) and an axial movement (forward / backward) at a predetermined angle with respect to 8 is provided. The rotary impact mechanism 12 has a V-shaped groove 14 formed on the outer periphery of the spindle 8 and inclined to the rotation axis and having a semicircular cross section in a side view, and an inverted V-shaped formed on an inner peripheral surface of the hammer 11 and An engagement recess 16 having an engagement recess 15 having a semicircular cross section and a ball 13 interposed between the V-groove 14 and the engagement recess 16 are provided. Therefore, when the hammer 11 is rotated relative to the spindle 8, the hammer 11 moves forward or backward in the axial direction with respect to the spindle 8. The rotary impact mechanism 12 having such a configuration is formed at a position symmetrical with respect to the rotation axis, that is, at a position having a phase difference of 180 degrees in the circumferential direction, so that the operation of the hammer 11 is smoothly performed. Is secured.

A compression spring 17 as an elastic member is interposed between the hammer 11 and the carrier portion 9 of the spindle 8, and the hammer 11 is opposed to the hammer 11 by the compression spring 17. It is pressurized toward the anvil 18 side (front) to be arranged. For this reason, the forward movement of the hammer 11 is controlled by the compression spring 1.
7, the reversing operation is performed against the pressing force of the compression spring 17. The forward movement is performed by the pressing force of the compression spring 17. Two claws (engaging protrusions) 11a are provided on the front end face of the hammer 11.
Is provided so as to protrude toward the anvil 18 side.
Corresponding to the above, two claws (engaging arms) 18a are provided on the shaft end surface (rear end) of the anvil 18 in a radial direction.

Accordingly, the hammer 11 is provided with the compression spring 1
At the position advanced by the pressing force of 7, the claw 11a of the hammer 11 abuts (collides) with the claw 18a of the anvil 18 from the circumferential direction, whereby the anvil 18 is hit in the rotational direction. On the other hand, when a load (screwing resistance) exceeding a certain value acts on the hammer 11 from the anvil 18 side, the hammer 11 is retracted as described above, and the claw 1 is moved.
The contact between 1a and 18a is released.

The anvil 18 is rotatably supported by an impact case 20 attached to the front end of the housing 1 via a bearing 19, and is provided with a shaft hole 18c provided in the center of the shaft on the shaft end face side. Shaft 8a
Is rotatably supported. Also, nail 1 of anvil 18
The lining 21 is interposed between the impact case 20 and the impact case 20. By this lining 21, the anvil 18 is rotationally supported without rattling in the axial direction. The distal end side of the anvil 18 is protruded from the impact case 20, and a socket mounting portion (square axis) for detachably mounting a bolt-tight socket (not shown) as a tip tool is provided at the distal end of the protruding portion. 18b is provided.

In the impact wrench having the above-described structure, as shown in FIG. 3A, a V-shaped groove 14 formed in the spindle 8 has one inclined groove 14b extending from the valley bottom 14a toward one groove end. And the other inclined groove 1 extending from the valley bottom 14a toward the other groove end.
4c is provided for loosening. The lead angle (inclination angle with respect to a straight line perpendicular to the axis of the spindle 8) α1 of the loosening-side inclined groove 14c is smaller than the tightening-side inclined groove 14c.
b is set smaller than the lead angle α. As shown in FIG. 3B, the engaging concave surface 15 formed on the hammer 11 has one inclined surface 15b extending from the central concave portion 15a for tightening, and extends from the concave portion 15a to the opposite side. The other slope 15c is provided for loosening.
And, as in the case of the V-groove 14, the loosening slope 15c
Is set so that its lead angle (inclination angle with respect to a straight line perpendicular to the axis of the hammer 11) β1 is smaller than the lead angle β of the inclined surface 15b on the tightening side. That is, the rotary impact mechanism 12 is configured to perform a composite motion in which the ratio of the axial movement amount to the circumferential movement amount of the hammer 11 is smaller on the loosening side than on the tightening side.

The impact wrench according to the present embodiment is configured as described above. Therefore, when a load (screw tightening resistance) of a certain value or more is applied to the anvil 18 via the socket during the bolt tightening operation or the loosening operation, the ball 13 fitted into the V groove 14 of the spindle 8 is tightened. The hammer 11 is moved along the inclined grooves 14b and 14c on the side or the loose side, and accordingly, the hammer 11 is moved in the axial direction by pressing the inclined surfaces 15b and 15c on the tightening or loose side. That is, the hammer 11 retreats while rotating relative to the spindle 8 in the opposite direction while compressing the compression spring 17. As a result, the claw 11a of the hammer 11 is disengaged from the claw 18a of the anvil 18, and the contact between the hammer 11 and the anvil 18 is released.

When the contact between the hammer 11 and the anvil 18 is released, the load is erased, and the hammer 11 is pressed by the compression spring 17 accordingly. For this reason, the hammer 11 has the inclined grooves 14 b and 14 of the V-shaped groove 14.
The ball 13 moving along c is moved while being pressed by the slopes 15b and 15c. That is, the hammer 11
Moves forward while rotating relative to the spindle 8 in the same direction. At this time, the claw 11a of the hammer 11 contacts the claw 18a of the anvil 18 from the circumferential direction. Thus, a striking force is applied to the anvil 18 in the rotational direction to tighten or loosen the bolt, and the above-described rotational striking operation is repeated.

Thus, when the hammer 11 strikes the anvil 18 during the above-described tightening or loosening, the hammer 11 presses and compresses the compression spring 17 as described above due to the repulsion by the impact. It retreats, but the repulsive force at that time is smaller when loosened than when tightened. In general, the spring force of the compression spring 17 is such that when the ball is tightened, the ball 13 repels the V-groove 1
The condition is set that the impact in the axial direction at the time of contact with the groove end of No. 4 can be effectively buffered. For this reason, if the lead angle of the inclined groove on the tightening side and the loosening side of the V-groove 14 is the same, as described in the related art, when the repulsive force is loosened, the ball is sufficiently extended to the groove end of the V-groove. A phenomenon in which the claw hits the next claw after hitting the previous claw during the next striking operation due to the fact that the crawler cannot fully retract, so-called claw 2
A hit occurs.

However, in the present embodiment, the inclined groove 14c on the loosening side of the V groove 14 formed in the spindle 8 is used.
Is set to be smaller than the lead angle α of the inclined groove 14b on the tightening side, and the lead angle β1 of the slanted side 15c of the engaging concave surface 15 formed on the hammer 11 is changed to the lead angle β1 on the tightened side 15b. Is set smaller than the lead angle β. For this reason, the amount of circumferential movement of the hammer 11 that retreats due to the repulsion at the time of hitting when loosening, that is, the amount of relative rotation with respect to the spindle 8 is compared with the case where the lead angle is the same as the tightening side (the time of tightening and To the same extent). However, the amount of retraction of the hammer 11 in the axial direction is determined by the size of the compression spring 17 and the repulsive force.
FIG. 3A shows the hammer 11 with respect to the spindle 8.
Are indicated by a two-dot chain line, the C position is a rotational hitting position (forward position), the D position is a retreat position by repulsion at the time of tightening, and the E position is a retreat position by repulsion when loosened. Position. As is clear from this figure, the amount of movement in the circumferential direction when the hammer 11 is loosened at the retracted position can be made substantially the same as that at the time of tightening. For this reason, FIG.
As shown in the schematic diagram of FIG.
It is possible to increase the time required to advance the roller 1 to a position where it can be advanced in the axial direction and give a hit, that is, a position where the claw 11a of the hammer 11 hits the claw 18a of the anvil 18. As a result, while the claw 11a of the hammer 11 advances to the position where it comes into contact with the claw 18a of the anvil 18, the claw 11a of the hammer 11 comes into contact with the claw 18a of the anvil 18 that was hit during the previous hitting operation. Instead, it can pass through the upper surface and contact the next claw 18a 'provided with a phase difference of 180 degrees.

As described above, according to the present embodiment, the nail 1
The two hits 1a and 18a are eliminated, and the impact energy of the hammer 11 is transmitted to the anvil 18 in a concentrated manner at one time, so that an efficient impact action can be added. Note that the actual angles of the lead angles α1 and β1 are determined when the compression spring 1
After taking into account the buffering effect and impact force of the spring force of 7,
It is appropriately determined within a range in which it is possible to avoid hitting twice.

It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the gist thereof. For example, in the embodiment, for both the V-groove 14 and the engagement concave surface 15, the lead angle α1 of the loose-side inclined groove 14c and the loose-side inclined surface 15c
Has been described as being smaller than the lead angle α of the inclined groove 14b on the tightening side and the lead angle β of the inclined surface 15b on the tightening side, respectively. It suffices if at least one of the above is applied. Also, an impact wrench has been described as an example of the rotary impact tool, but the present invention can be applied to an impact driver in which a driver bit can be attached to the tip on the anvil 18 side.

[0022]

As described in detail above, according to the present invention,
It is possible to provide a rotary impact tool capable of improving the working efficiency by eliminating the hit of the claws twice during the screw loosening operation.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view showing an impact wrench according to the present embodiment.

FIG. 2 is an enlarged sectional view showing a main part.

FIG. 3 is a development view of a spindle and a hammer;
(A) shows a V groove set on the spindle, and (B) shows an engagement recess set on the hammer.

FIG. 4 is a schematic diagram illustrating an operation mode of a claw when loosened.

FIG. 5 is a development view of a conventional spindle and hammer, where (A) shows a V groove set on the spindle,
(B) shows the engagement recess set in the hammer.

FIG. 6 is a schematic diagram illustrating an operation mode of a claw at the time of loosening according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Output shaft 3 ... Planetary gear train 8 ... Spindle 11 ... Hammer 12 ... Rotating impact mechanism 13 ... Ball 14 ... V groove 14b ... Clamping side inclined groove 14c ... Loose side inclined groove 15 ... Engagement concave surface 15b: Slope on tightening side 15c: Slope on loose side 16 ... Recessed recess 17 ... Compression spring 18 ... Anvil

Claims (2)

[Claims] 1. An electric motor, a spindle rotated by the electric motor, an anvil arranged coaxially with the spindle, a hammer fitted to an outer periphery of the spindle, and the hammer connected to the anvil. An elastic member that presses toward the side, and is interposed between the spindle and the hammer, and when the spindle is rotated in a tightening direction or a loosening direction of the screw, the hammer moves at a predetermined angle in the circumferential direction and the shaft is rotated. A rotary striking tool comprising: a rotary striking mechanism for engaging the claw of the hammer with the claw of the anvil to apply a rotary striking by performing a combined motion with the directional movement. The ratio of the amount of axial movement to the amount of movement of the hammer in the circumferential direction is configured to perform a composite movement on the loosening side smaller than on the tightening side. Rotary impact tool. 2. The rotary hitting tool according to claim 1, wherein the rotary hitting mechanism includes: a V-groove formed on an outer periphery of the spindle; and a ball moved along the V-groove.
An engagement concave portion formed on the inner peripheral surface of the hammer and having an inverted V-shaped engagement concave surface that engages with the ball. The V groove is used for fastening one inclined groove extending from a valley bottom. , The other concave groove is provided for loosening, the engaging concave surface is provided with one inclined surface extending from the valley bottom for tightening, and the other concave surface is provided for loosening, and one of the V groove or the engaging concave surface is provided. Alternatively, a rotary impact tool characterized in that the lead angles on both loosening sides are set smaller than the lead angle on the tightening side.