JPH05228849A - Impact rotating tool - Google Patents

Abstract

PURPOSE:To limit the retreat of a hammer at the time of tight fitting of a spring to prevent the fall of a steel ball from a groove and the like of the hammer by arranging a receiver seat of a spring for energizing a hammer at a position closer to the deflection side of the spring than the steel ball built-in position. CONSTITUTION:A cam groove 4a is formed in a driving shaft 4 and a groove 2a is formed in a hammer 2 to convert the rotation of the hammer 2 to the retreat in the axial direction through a steel ball 1. When the fastening torque reaches a certain value, the hammer 2 is retracted to remove the engagement of claw parts 5a, 2b of an anvil 5 and the hammer 2, and the rotational energy stored in the spring 6 as the restoring force hits the anvil 5 with the retreat of the hammer 2. As a result, a fastening tool is disconnected. In this case, a receiver seat 7 of the spring 6 is arranged at a position closer to the deflection side of the spring 6 than the steel ball 1 built-in position. The retreat of the hammer 2 at the time of tight fitting of the spring 6 is limited to prevent the fall of the steel ball 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary impact tool, and more particularly, with a simple improvement, it is intended to prevent escape of a cam groove formed in a drive shaft and a hammer and a steel ball incorporated in the groove. It is related to technology.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS.
In an impact driver as an impact rotary tool, a hammer 2 moves forward and backward through a drive shaft 4 and a groove 2a formed by cutting the hammer 2 itself and a steel ball 1 inserted in a cam groove 4a. .. According to the prior art, the maximum retreat amount of the hammer 2 is required to be equal to or greater than the position where the hammer 2, the groove 2a of the drive shaft 4, and the end of the cam groove 4a are reached in order to insert the steel ball 1. That is, hammer 2
The spring 6 that elastically biases the steel balls 1 is largely elastically deformed to incorporate the steel balls 1 with a margin.

Therefore, the hammer 2 repels at the end positions of the groove 2a and the cam groove 4a, so that the steel ball 1 momentarily receives no force from the spring 6. Since the hammer 2 does not follow the groove 2a and the cam groove 4a and tries to move forward only by the urging force of the compression spring 6, the groove 2
a, the steel ball 1 which is interposed in the cam groove 4a in a free state
Had a problem that it jumped out from the end surface of the groove 2a of the hammer 2. Further, there is a problem that when the hammer 2 reaches the tip of the groove 2a or more when the screw is tightened in the lateral and downward directions, the steel ball 1 falls from the cam groove 4a of the drive shaft 4 due to its own weight. In this way, the steel ball 1 is caught between the hammer 2 and the hammer case or the housing, which causes failure such as damage of the hammer case, damage of the anvil 5 and the claw portions 5a and 2b of the hammer 2.

In order to improve such a problem, Japanese Patent Publication No. 61-54547 has been proposed.

[0005]

By the way, Japanese Patent Publication No. 61
No. 54547 discloses a structure in which a cam groove is formed on an end surface of a hammer, a spring seat regulates a backward movement amount of the hammer, and a steel ball can be inserted only into the cam groove of the hammer. Only the probability of the ball jumping out is low, and there is a possibility of jumping out. Further, the number of constituent parts is large and the number of assembling steps is also high.

The present invention has been made in view of the above problems, and an object thereof is to prevent a steel ball from falling off, at low cost, with excellent assembling property, and to surely prevent the coming off. There is an attempt to provide an impact rotary tool that can

[0007]

According to the present invention, a cam groove 4a for converting a rotational movement of a hammer 2 into an axial backward movement through a steel ball 1 is formed on a drive shaft 4 and a groove 2a is formed on a hammer 2. When a certain tightening torque is reached, the hammer 2 retracts, the anvil 5 and the claws 5a and 2b of the hammer 2 disengage, and the rotational energy stored as the hammer 2 retracts strikes the anvil 5 by the restoring force of the spring 6. However, in an impact rotary tool for tightening or loosening screws, bolts, etc., the steel ball 1 incorporated in the cam groove 3a formed in the drive shaft 4 and the hammer 2 and the groove 2a.
When the hammer 2 retreats beyond a certain level, the groove 2a and the cam groove 4
The position of the seat 7 of the spring 6 that elastically biases the hammer 2 so as to prevent the spring 6 from escaping from the position a is changed to the bending side of the spring 6 rather than the installed position of the steel ball 1, and the spring 6 based on the retreat of the hammer 2 is moved. In the close contact state, the hammer 2 is prevented from further retracting to prevent the steel ball 1 from coming out of the cam grooves 3a and 4a.

[0008]

The cam groove 4a formed on the drive shaft 4 in this way
And the spring 6 that elastically biases the hammer 2 to prevent the steel ball 1 incorporated in the groove 2a formed in the hammer 2 from coming out of the groove 2a and the cam groove 4a when the hammer 2 retracts more than a certain amount. The position of the seat 7 is changed to the bending side of the spring 6 rather than the assembling position of the steel ball 1, and the hammer 2
By preventing the hammer 2 from further retracting when the spring 6 is in close contact with the cam groove 4a and the groove 2a, the steel ball 1 is prevented from coming out from the cam groove 4a and the groove 2a.
That is, in order to incorporate the steel ball 1 into the groove 2a between the hammer 2 and the drive shaft 4 and the cam groove 4a, the spring 6 is sufficiently compressed to move the steel ball 1 into the groove 2a between the hammer 2 and the drive shaft 4 and the cam groove. After the steel ball 1 has been assembled, the position of the seat 7 of the spring 6 is changed in the direction in which the spring 6 compresses the hammer 2 and the spring 2 is retracted when the hammer 2 is retracted. Stick 6 together,
Even if the hammer 2 retreats to the maximum, it is prevented from retreating beyond the insertion position of the steel ball 1 in the state where the spring 6 is in close contact, and with a simple improvement that the seat 7 of the spring 6 is changed, This is to ensure that the intended purpose is achieved and that the structure is simplified.

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 2, the impact rotary tool A is an impact driver in which a driver bit is attached to the bit holder 9, and a battery pack 11 is attached to the lower end of the handle portion of the main body 10 and is attached to the front side of the handle portion. Is a switch handle grip 12 and a rotation direction switching lever 13
And are provided.

As shown in FIG. 1, a motor 15 is arranged in the main body 10 via a motor mount 14, and a pinion 41 is press-fitted and fixed to the output shaft of the motor 15, and the pinion 41 is fixed to the pinion 41. The drive shaft 4 is meshed with a plurality of planet gears 18 attached to a carrier portion 17 at the rear end. The drive shaft 4 has a rear end supported by a bearing 19 and a front end supported by an anvil 5,
The planetary gear 18 also meshes with an internal gear 20 formed integrally with the motor mounting base 14, and
When it rotates, it is decelerated and rotated by being decelerated by the planetary mechanism including the pinion 41, the planetary gear 18, the internal gear 20, and the carrier unit 17.

An annular hammer 2 is provided on the outer periphery of the drive shaft 4.
Are arranged so as to be movable in the axial direction and the rotation direction. This hammer 2 is provided with a claw portion 2b on the front surface thereof which meshes with a claw portion 5a on the rear end surface of the anvil 5, and has an axial groove 2a formed on the inner peripheral portion thereof, which is formed on the outer periphery of the drive shaft 4. The hammer 2 rotates integrally with the drive shaft 4 through the steel ball 1 that engages with the substantially V-shaped cam groove 4a. The cam groove 4a is formed in a substantially V shape in order to perform tightening operation of screws and bolts and loosening operation of reverse rotation.

One end of a coil-shaped spring 6 is in contact with the back surface of the hammer 2 via a thrust plate 21. The other end of the spring 6 is a seat 7 for the spring 6.
Via the thrust plate 22 that becomes the gear shaft 2 of the planetary gear 18.
The hammer 2 is supported by the spring 3, and the hammer 6 is biased forward by the spring 6. The anvil 5 is rotatably supported by a bearing 24. The bit holder 9 is provided at the tip of the anvil 5, and a claw portion 5a with which the claw portion 2b of the hammer 2 is meshed is formed at the rear end surface.

In the impact driver, however, the drive shaft 4 which is rotationally driven by the motor 15 transmits its rotational force to the hammer 2 via the steel ball 1, and the hammer 2 is urged by the spring 6 to cause the anvil. The rotation of the hammer 2 is transmitted to the driver bit through the anvil 5 because the hammer 2 is engaged with the driver bit. In such a case, if the load becomes large during screw tightening work with a driver bit,
At the meshing part between the hammer 2 and the anvil 5, the hammer 2
In order to generate a component force for retreating, the hammer 2 is retracted while rotating with respect to the drive shaft 4 because of the substantially V-shaped cam groove 4a provided on the drive shaft 4. When the hammer 2 and the anvil 5 are disengaged from each other, the hammer 2 strikes the anvil 5 by the rotational energy from the motor 15 and the reaction force of the spring 6. Added to. The impact in the axial direction is received by the thrust ring 25 provided on the bearing 24.

In the above construction, the hammer 2 having reached a certain tightening torque is engaged with the anvil 5 by the claw portions 5a and 2b.
The amount of retreat when retreating while releasing the engagement in is the close contact state of the spring 6 that is in contact with the thrust plate 22 extruded by the gear shaft 23 that is press-fitted from the end of the drive shaft 4 after the steel ball 1 is installed. This prevents the hammer 2 from further retracting, and the hammer 2 largely retracts to prevent the steel ball 1 from escaping from the groove 2a of the hammer 2. The configuration will be described in detail below.

As shown in FIGS. 4A and 4B, the drive shaft 4
Is erected on the jig 26, and the thrust plate 22,
Spring 6, thrust plate 21, steel ball 27, hammer 2
Are placed in sequence and assembled. Then, the lower end surface of the drive shaft 4 is received by the jig 26, and the upper end surface of the hammer 2 is pressed by the press 28.
Push down with etc. The steel ball 1 is inserted through the gap a generated at this time. Next, as shown in FIG. 4 (c), with the upper end of the drive shaft 4 held down, a push-up pin 29 is press-fitted and fixed into the through hole from the lower end face to push up the thrust plate 22 to compress the spring 6, Shorten the installation length of the spring 6,
In such a state, the gear shaft 23 is incorporated, and the position of the seat 7 of the spring 6 is changed to the compression direction of the spring 6. Therefore, when the hammer 2 is retracted, the spring 6 is compressed and brought into close contact with the hammer 2. Further, the hammer 2 is prevented from retreating, and thus the hammer 2 is further retracted from the insertion position of the steel ball 1 to prevent the steel ball 1 from coming off. That is, a spring that elastically biases the hammer 2 to prevent the steel ball 1 assembled in the cam groove 4a of the drive shaft 4 and the groove 2a of the hammer 2 from coming out of the groove 2a when the hammer 2 retracts beyond a certain level. The position of the seat 7 (thrust plate 22 in the embodiment) of 6 is changed to the bending side of the spring 6 rather than the installed position of the steel ball 1, and when the spring 6 is in close contact due to the retreat of the hammer 2, the hammer 2 is further moved. To prevent the escape from the groove 2a and the cam groove 3a.

In this way, the steel ball 1 incorporated in the cam groove 4a of the drive shaft 4 and the groove 2a of the hammer 2 is prevented from coming out of the groove 2a and the cam groove 4a when the hammer 2 retracts beyond a certain level. Therefore, the position of the seat 7 of the spring 6 that elastically biases the hammer 2 is changed to the bending side of the spring 6 rather than the position where the steel ball 1 is installed, and when the spring 6 is in close contact due to the retreat of the hammer 2, that of the hammer 2 is changed. By preventing the above-described retreat operation and preventing the steel ball 1 from coming out of the groove 2a and the cam groove 4a, the steel ball 1 can be incorporated into the groove 2a between the hammer 2 and the drive shaft 4 and the cam groove 4a. Compress the spring 6 enough to move the steel ball 1 into the hammer 2 and the drive shaft 4.
After the steel balls 1 have been assembled, the positions of the seats 7 of the springs 6 are changed in the direction in which the springs 6 compress the hammers 2 while easily assembling the grooves 2a and the cam grooves 4a. If the hammer 2 moves back to the maximum, the steel balls 1
Of the spring 6 is prevented from retreating beyond the insertion position of the spring 6 in the close contact state, and the intended purpose can be reliably achieved by a simple modification by changing the seat 7 of the spring 6. Is intended to be simplified. In such cases,
The gear shaft 23 of the planet gear 18 is also loosely fitted in the through hole of the drive shaft 4.

More specifically, as shown in FIG. 4B, the mounting position of the hammer 2 on the drive shaft 4 is the steel ball 1 in which the hammer 2 is mounted.
And is at a position of length L with respect to the flange surface of the drive shaft 4. When the anvil 5 is loaded with a certain amount or more, the hammer 2 retracts to a position where the spring 6 is compressed until the spring 6 is brought into close contact with it, as shown in FIG. In such a case, the steel ball 1 is likely to come out, as shown in FIG.
As shown in (c), the push-up pin 29 is press-fitted into the drive shaft 4 to compress the spring 6 via the thrust plate 22. Then, as shown in FIG. 5 (a), when the hammer 2 is retracted, the spring 6 quickly comes into close contact, and the length h pushed up by the push-up pin 29 is increased.
Only the amount of retreat of the hammer 2 is reduced, and the steel ball 1 is prevented from slipping out by that amount.

FIG. 6 shows a second embodiment, which utilizes the through hole of the gear shaft 23 of the planetary gear 18, that is, the jig 26.
The push-up pin 29 attached to is inserted into the through hole to push up the thrust plate 22 to compress the spring 6, and the spacer 30 having a height corresponding to the compressed height h is inserted. As shown in FIG. 6C, the spacer 30 has
The spacer 3 has a substantially C-shaped ring shape.
0 is opened and mounted between the thrust plate 22 and the drive shaft 4 as shown in FIG. Also in this embodiment, the hammer 2 is located at a position closer to the anvil 5 side by the height h than the position where the steel ball 1 is installed.
Is brought into a close contact state, the amount of retreat of the hammer 2 is reduced, and the incorporated steel ball 1 is prevented from coming off.

FIG. 7 shows a third embodiment of the jig 26.
The push-up pin 29 attached to is inserted into the through hole to push up the thrust plate 22 to compress the spring 6, and the cylindrical spacer 30a having a height corresponding to the compressed height h is set at the position of the gear shaft 23. The gear shaft 23 is inserted through a cylindrical spacer 30a. Also in this embodiment, the hammer 2 is located at a position closer to the anvil 5 side by the height h than the position where the steel ball 1 is installed.
Is brought into a close contact state, the amount of retreat of the hammer 2 is reduced, and the incorporated steel ball 1 is prevented from coming off.

8 and 9 show a fourth embodiment,
This is to easily remove the assembled steel ball 1. The drive shaft 4 is formed with a prism 32, the thrust plate 22 is formed with a square hole 33, and the square plate 32 is inserted into the square hole 33 to prevent the thrust plate 22 from rotating. Thus, the relative position is determined. The thrust plate 22 in the bent state is formed with the descending hole 34 for inserting the push-up pin 29 with a 90 ° phase shift. Then, in order to remove the steel ball 1 in which the slip-out prevention is performed as described above, the gear shaft 23 fitted with a clearance is removed, and the jig 2 is left in this trace.
6 is inserted through a preliminarily formed long removal pin hole 35 to push up the thrust plate 22 as shown in FIG. 9 (a) to release the positioning of the thrust plate 22 and the drive shaft 4 in the rotational direction. Then, rotate the thrust plate 22 by approximately 90 °,
The removal pin 35 is pulled out to lower the thrust plate 22, the push-up pin 29 press-fitted into the drive shaft 4 is inserted into the lowering hole 34 of the thrust plate 22, and the thrust plate 22 is lowered. Then, the steel balls 1 are pulled out and disassembled in the same manner as when the steel balls 1 are inserted. After replacing the defective part, assemble in reverse order.

[0021]

As described above, according to the present invention, the steel balls incorporated in the cam groove formed in the drive shaft and the groove formed in the hammer escape from the cam groove and the groove when the hammer retreats more than a certain amount. The position of the spring seat that elastically biases the hammer to prevent it is changed to the bending side of the spring rather than the built-in position of the steel ball, and the hammer further retracts when the spring is in close contact due to the hammer retracting. Since it prevents the steel ball from coming out of the cam groove and groove, the spring is sufficiently compressed to hammer the steel ball into the groove of the hammer and the drive shaft and the cam groove. After the steel balls have been installed, the spring seats are repositioned in the direction in which the spring compresses the hammer, and the hammer can be easily installed in the groove between the drive shaft and the drive shaft and the cam groove. When retracting, close the spring and prevent the hammer from retracting beyond the insertion position of the steel ball even when the hammer retreats to the maximum in the tight contact state of the spring, thus making it easier to change the spring seat With such improvements, there is an advantage that the intended purpose can be achieved reliably and the configuration can be simplified.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of the present invention.

FIG. 2 is a partially cutaway side view of the same as above.

FIG. 3 is an exploded perspective view of a main part of the above.

4 (a), (b) and (c) are explanatory sectional views showing an assembling action of the steel ball of the same, and FIG. 4 (d) is a side view showing a cam groove of a drive shaft.

FIG. 5 is a sectional view showing (a) a bottom view of the steel ball retaining function of the same.

FIG. 6 shows a second embodiment of the above, (a) is a cross-sectional view before mounting the spacer, (b) is a cross-sectional view in a state in which the hammer is prevented from retracting, (c) is a plan view of the spacer, d)
Is a plan view showing a state in which the spacer is opened, (e) is a side view of the spacer, and (f) is a bottom view of (b).

FIG. 7 shows a third embodiment of the above, (a) is a cross-sectional view before mounting a spacer, (b) is a cross-sectional view showing a state in which the hammer is prevented from retracting, (c) is a plan view of the space,
(D) is a side view.

8A and 8B show a fourth embodiment of the above, in which FIG. 8A is a sectional view with a steel ball attached, FIG. 8B is a sectional view with a thrust plate raised, and FIG. (D) is a plan view of the thrust plate, (e) is a plan view of the drive shaft, (f) is an X of (a).
FIG. 3 is a sectional view taken along line X-ray.

FIG. 9 is a sectional view showing the action of removing the steel ball of the above, and (a) is a state in which the thrust plate is removed and lifted by a pin;
(B) is a sectional view of the thrust plate in a lowered state, (c)
Is a cross-sectional view of the steel ball removed, (d) is a bottom view, (e) is a plan view in which the phase of the thrust plate is changed, (f) is a plan view of the drive shaft, (g) is X in (b). FIG. 3 is a sectional view taken along line X-ray.

[Explanation of symbols]

 1 Steel Ball 2 Hammer 2a Groove 4 Drive Shaft 4a Cam Groove 5 Anvil 6 Spring 7 Seat

Claims (1)

[Claims] 1. A cam groove for converting a rotational movement of a hammer into a backward movement in an axial direction through a steel ball is formed in the hammer on a drive shaft, and when a certain tightening torque is reached, the hammer retracts to move to an anvil. The cams formed on the drive shaft and hammer in the impact rotary tool in which the engagement of the hammer's claws disengages and the rotational energy stored as the hammer retracts strikes the anvil by the spring's restoring force and tightens or loosens screws, bolts, etc. The position of the spring seat that elastically biases the groove to prevent the groove and the steel ball incorporated in the groove from coming out of the groove and the cam groove when the hammer retracts more than a certain amount is greater than the position where the steel ball is incorporated. It is changed to the flexible side of the spring to prevent further backward movement of the hammer when the spring is in close contact due to the backward movement of the hammer. An impact rotary tool characterized by being stopped to prevent a steel ball from coming out of the cam groove and the groove.