JPH10329046A - Tightening tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change setting of tightening torque with high ease of operation. SOLUTION: A tightening tool is provided with a tightening torque adjusting part which shuts down power transmission to an output shaft 9 through prescribed load torque so as to be capable of changing setting of the tightening torque of the tightening torque adjusting part by changing spring load. A decelerating member 4 is disposed between a setting changing operation part 3 and a spring load changing member 35. Presence of the decelerating member 4 can minimize the force to be applied to the setting changing operation part 3, which is needed for changing the spring load by moving the spring load changing member 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tightening tool such as an electric screwdriver or an electric wrench, and more particularly to a tightening tool provided with a tightening torque adjusting unit also called a torque limiter.

[0002]

2. Description of the Related Art In a tightening tool in which power transmission is cut off when a tightening torque reaches a set value so as not to cause over-tightening, a planetary mechanism which is a reduction gear is used as a torque adjusting unit. There are many things. That is, the ring gear in the planetary mechanism is made rotatable, and an engaging member is provided for engaging the ring gear by the bias of the clutch spring to stop the rotation of the ring gear. Although the deceleration output of the planetary mechanism is transmitted to the output shaft by the rotation inhibition, the tightening torque is increased and the load torque applied to the ring gear is determined by the engagement force between the engagement member and the ring gear given by the clutch spring. When the height is also increased, the ring gear pushes back the engagement member against the clutch spring to start idling, thereby interrupting power transmission.

[0003] Further, since the tightening torque in this device depends on the spring force of the clutch spring as described above, the setting of the tightening torque can be changed by changing the compression amount of the clutch spring. The compression amount of the clutch spring can be changed by the operation of the changing operation section, so that the setting of the tightening torque can be changed.

[0004]

When the setting of the tightening torque is increased, the amount of compression of the clutch spring is increased to increase the spring load. However, in the prior art, the male screw provided on the gear case is provided. The rotation of the load changing member, which is screwed into the portion and one end of the clutch spring is in contact with by rotating the setting changing operation portion, is performed, and the load changing member is rotated by one rotation of the setting changing operation portion. Because both were connected so that also makes one rotation,
As the spring load is increased, the force required for operating the setting change operation unit is also increased, and the force required at this time is considerably increased, making it difficult to change the setting of the tightening torque.

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and an object of the present invention is to provide a tightening tool capable of changing the setting of the tightening torque with good operability.

[0006]

According to the present invention, there is provided a tightening torque adjusting section for interrupting the power transmission to the output shaft by a predetermined load torque, and the tightening torque of the tightening torque adjusting section is changed by changing the spring load. The tightening tool capable of changing the setting is characterized in that a speed reducing member is arranged between the setting changing operation section and the spring load changing member. Due to the presence of the deceleration member, when the spring load changing member is moved to change the spring load, a small amount of force must be applied to the setting change operation member.

As the speed reducing member, a worm speed reducer or a speed reducer including a planetary gear mechanism can be suitably used.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described. The tightening tool shown in FIG. 1 has an electric screwdriver with various tool bits mounted on an output shaft 9 thereof through a chuck (not shown). A gear case 8 and a tightening torque setting member are accommodated between the output shaft 9 and the rotation shaft 20 of the motor 2 as a power source. Contains a speed reducer that reduces the output of the motor 2, a tightening torque adjusting clutch, and a lock mechanism 6 that locks the output shaft 9 with respect to the tool body 1 when performing a manual tightening operation.

The speed reducer is constituted by a three-stage planetary gear mechanism. A sun gear 21 provided on a rotating shaft 20 of the motor 2 and a ring gear 2 fixed to the inner surface of the gear case 8.
3 and a plurality of planetary gears 22 supported by a carrier 24
Are meshed with each other, and a plurality of planetary gears 26 are meshed with a sun gear 25 formed integrally with the carrier 24 and a ring gear 27 freely rotatable within the gear case 8. The carrier 28 supporting the planetary gear 26 integrally includes a sun gear 29 of a third-stage planetary mechanism, and the sun gear 29 and a ring gear that is freely rotatable in the gear case 8. The planetary gear 30 meshes with 31. The carrier 32 supporting the planetary gear 30 is connected to the output shaft 9 via the lock mechanism 6. The description of the lock mechanism 6 that performs an automatic lock for manual tightening is omitted.

The ring gear 27 of the second-stage planetary gear mechanism among the speed reducers having the three-stage planetary gear mechanism is not only arranged freely in the gear case 8 as described above, but also freely rotatable. When it moves to the motor 2 side (upper state in FIG. 1), it engages with the ring gear 23 to prevent its rotation and moves to the opposite side. In the state (lower side in FIG. 1), it engages with the carrier 28 and rotates together with the carrier 28. Since the reduction ratio changes between the former state and the latter state, the ring gear 27
The shift can be performed by the movement of the vehicle.

In the third stage planetary gear mechanism, the ring gear 31 is freely rotatable as described above.
This is because the tightening torque adjustment clutch is a ring gear 31
This is because it is based on. The tightening torque adjusting clutch and the tightening torque setting section for the clutch are provided so as to axially penetrate the ridge 33 formed on the axial end face of the ring gear 31 and the step portion of the gear case 8. Ball 34 disposed in the through hole, a load changing member 35 screwed into a male screw provided on the outer peripheral surface of the small-diameter portion at the tip of the gear case 8, and the outer periphery of the small-diameter portion at the tip of the gear case 8. Click plate 3 arranged
6, 37 and a clutch spring 3 composed of a compression coil spring disposed between the load changing member 35 and the click plate 36.
8, and a setting change operation unit 3 rotatably attached to the distal end of the main body 1. When the load changing member 35 is rotated, the load changing member 35 also moves in the axial direction due to the engagement with the male screw, and the compression amount of the clutch spring 38 changes.

The output of the motor 2 is controlled by the first and second stage planetary gear mechanisms and the ball spring 3 urged by the clutch spring 38.
The rotation is reduced by the third stage planetary mechanism having the ring gear 31 whose rotation is hindered by the locking of the gear 4, and is transmitted to the output shaft 9. When the load torque applied to the ring gear 31 becomes higher than the engagement force between the ball 34 provided by the clutch spring 38 and the ridge 33 of the ring gear 31, the ring gear 31 opposes the clutch spring 38. The ball 34 is pushed out to start idling. Since the torque adjusting clutch portion including the ring gear 31 and the ball 34 slips, the tightening torque is limited. If the load changing member 35 is moved to the left in the figure to increase the compression amount of the clutch spring 38 (the lower side in the figure shows this state), the ball 34 and the ring gear 31 Since the engaging force of the ring gear 31 increases, the load torque at which the ring gear 31 starts idling increases, that is, the tightening torque increases.

The movement of the load changing member 35 is performed by rotating the load changing member 35 screwed to the gear case 8 around an axis. This is performed by rotating the setting change operation unit 3 that is rotatably arranged. However, the setting change operation unit 3 and the load change member 3 are configured such that the rotation of the load change member 35 only slightly rotates when the setting change operation unit 3 is rotated once.
5, a speed reduction unit 4 is provided. The reduction unit in the example shown in FIG. 1 includes an internal gear 40 provided on an inner peripheral surface of the setting change operation unit 3 and a gear 41 provided on a distal outer peripheral surface of the gear case 8.
The shaft 43 protrudes from the tip end surface of the load changing member 35.
And a planetary gear mechanism consisting of a planetary gear 42 mounted on the motor.

The planetary gear 42 meshing with the gear 41 and the internal gear 40 rotates the load changing member 35 in accordance with the rotation of the setting change operation unit 3, and the rotation speed is the rotation speed of the setting change operation unit 3. Therefore, even if the amount of compression of the clutch spring 38 increases, the operating force required to turn the setting change operation unit 3 to move the load changing member 35 is small. It is a thing.

FIG. 2 and FIG. 3 show another example of the speed reduction unit 4. Here, a wheel bracket 52 is fixed to a sleeve 50 fixed to a tip end portion of the gear case 8 via a support plate 51, and a plurality of worm wheels 45 are arranged on the wheel bracket 52 at equal intervals. The worm wheel 45 is configured so that its axial direction is tangential to the annular worm wheel 45.

A worm gear 46 is formed on the inner surface of the setting change operation section 3, and a plurality of worm racks 47 are formed on the load changing member 35 arranged on the outer periphery of the sleeve 50 so as to be freely movable in the axial direction. The worm wheel 45 meshes with both the worm gear 46 and the worm rack 47. When the setting change operation unit 3 is rotated, the worm wheel 45 that meshes with the worm gear 46 provided on the setting change operation unit 3 rotates, and the rotation includes the worm rack 47 that meshes with the worm wheel 45. The changing member 35 moves in the axial direction. A speed reduction unit 4 composed of a worm speed reducer is arranged between the setting change operation unit 3 and the load change member 35 so that the load change member 35 can be moved lightly against the clutch spring 38. .

[0017]

As described above, in the present invention, since the deceleration member is disposed between the setting change operation portion and the spring load changing member, the spring load is changed by moving the spring load changing member. In doing so, the force that must be applied to the setting change operation member is small, and the setting change operation can be performed lightly.

When a speed reducer composed of a worm speed reducer or a planetary gear mechanism is used as the speed reducer, a speed reducer having a large reduction ratio is disposed in a narrow space between the setting change operating section and the spring load change member. It is possible to set the tightening torque without using a worm gearbox, and without using a lock mechanism in the setting change operation unit because it has a self-locking function. It does not change carelessly, and allows stepless adjustment of the torque setting, and when a speed reducer composed of a planetary gear mechanism is used, the speed reduction member can be constituted by a spur gear. The manufacturing cost can be reduced, and the torque setting can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of another example of the embodiment of the present invention.

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

[Explanation of symbols]

 3 operation part for setting change 4 reduction member 35 load change member 38 clutch spring

Claims (3)

[Claims] 1. A tightening tool comprising a tightening torque adjusting unit for interrupting power transmission to an output shaft with a predetermined load torque, and enabling a setting change of a tightening torque of the tightening torque adjusting unit by changing a spring load. A tightening tool comprising a speed reducing member disposed between a setting change operating portion and a spring load changing member. 2. The fastening tool according to claim 1, wherein the speed reducing member is a worm speed reducer. 3. The tightening tool according to claim 1, wherein the speed reducing member is a speed reducer including a planetary gear mechanism.