JP2001047324A - Fastening tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening tool capable of sensing a minute torque accurately and allowing easy mounting of a strain gauge accurately. SOLUTION: An epicyclic gearing mechanism 3 increases the torque of an air motor installed on the body. Together with a drive shaft, a fastening member is rotated by an increased rotational output of the gearing mechanism 3 so that an object concerned is fastened. The reaction force in the direction of arrow R acting on a casing 21 through an internal gear 25 when the mechanism 3 rotates the drive shaft is received by a plate-form member 5 through a transmitting member 26 extending outward in the radial direction. A strain gauge is attached to the plate-form member 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tightening tool used for tightening, for example, nuts and bolts.

[0002]

2. Description of the Related Art Conventionally, a fastening tool includes an air motor and a planetary gear mechanism which increases a rotational force generated by the air motor and transmits the torque to a drive shaft. FIG.
FIG. 3 is a schematic sectional view of a casing 31 in which an internal gear 30 of the planetary gear mechanism is fixed to an inner peripheral surface. The outer peripheral surface of the casing 31 has a 90 °
The strain gauges 33, 33,...

[0003] In the tightening tool having the above structure, when the object to be tightened is to be tightened by the drive shaft receiving the rotational force of the air motor through the planetary gear mechanism, the planetary gear is driven by the reaction force of the rotational torque for tightening the object to be tightened. Since the torsional deformation occurs in the casing 31 of the mechanism, the strain gauges 33 attached to the casing 31 are also deformed, and the resistance values of the strain gauges 33 change.
The rotational torque is detected based on the change in the resistance value of each of the strain gauges 33.

[0004]

However, in the above-mentioned tightening tool, if the rotational torque for tightening the object to be tightened is very small, for example, 5 kgf · cm, the casing 3
1 also reduces the amount of torsional deformation, and the casing 31
Are also small, it is difficult to detect the small deformation with high accuracy by the strain gauges 33, 33, and it is difficult to accurately detect the minute rotation torque. There is a problem that is.

[0005] Further, the casing 31 of the planetary gear mechanism.
There is a problem that it is difficult to attach the strain gauges 33, 33,...

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tightening tool capable of accurately detecting a minute rotation torque and mounting a strain gauge accurately and easily.

[0007]

In order to achieve the above object, a tightening tool according to the present invention is provided with a main body, a motor attached to the main body, and a motor mounted on the main body to generate the motor. An intensifying section that increases the rotational force, a drive shaft that rotates in response to a rotational output from the intensifying section and drives the object to be tightened, and a transmission member that is fixed to a casing of the intensifying section and extends radially outward And a plate-like member fixed to the main body, and a strain gauge attached to the plate-like member, while receiving a reaction force when the booster drives the drive shaft via the transmission member. It is characterized by that.

According to the first aspect of the present invention,
When the motor attached to the main body starts, the torque generated by the motor is increased by the booster, and the drive shaft receiving the rotation output from the booster rotates to tighten the object to be tightened. At this time, the reaction force when the booster drives the drive shaft is received from the plate-like member via the transmission member extending radially outward, and the plate-like member undergoes large bending deformation. Then, the magnitude of the reaction force is detected based on the change in the resistance value of the strain gauge attached to the plate member, and the rotational torque proportional to the reaction force is detected.

As described above, since the plate-like member receives the reaction force when the booster drives the drive shaft via the transmission member, a large bending deformation occurs in the plate-like member, and the minute reaction force is generated. But it can be detected. Therefore, even a small rotation torque of 10 kgf · cm or less can be accurately detected.

Further, since the above-mentioned strain gauge can be attached to the plate-like member, the attachment of the strain gauge can be easily performed.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a tightening tool according to the present invention.

FIG. 1 is a sectional view of a tightening tool according to an embodiment of the present invention. As shown in FIG. 1, the tightening tool includes a main body 1, an air motor 2 attached to the main body 1,
Planetary gear mechanism 3 as a booster mounted on main body 1
And a drive shaft 4 that rotates by receiving a rotation output from the planetary gear mechanism 3. Further, the planetary gear mechanism 3
A plate member 5 in the vicinity is fixed to the main body 1, and a strain gauge 6 is attached to a smooth surface of the plate member 5. The rotation output shaft 7 of the air motor 2 of the main body 1 is fitted to the transmission shaft 8, and the tip of the transmission shaft 8 is connected to the sun gear 22 (shown in FIG. 2) of the planetary gear mechanism 3. Further, a tightening member 9 that fits with the object to be tightened is attached to the tip of the drive shaft 4 that rotates with the rotation output from the planetary gear mechanism 3. Reference numerals 10, 11, 12, and 13 denote bearings that rotatably support the drive shaft 4.

FIG. 2 is a schematic sectional view of the casing of the planetary gear mechanism 3. As shown in FIG. 2, the planetary gear mechanism 3 is fitted on a transmission shaft 8 (shown in FIG. 1) and rotates with the transmission shaft 8, and a sun gear 22 meshed with the sun gear 22. The planetary gears 23 and 24 revolve while rotating around the gears, and the internal gear 25 meshes with the planetary gears 23 and 24. This internal gear 25 is fixed to the inner peripheral surface of the casing 21 of the planetary gear mechanism 3. A transmission member 26 extending radially outward is fixed to the outer peripheral surface of the casing 21. The transmission member 26 includes a base 27 protruding in the radial direction, a rod 28 fixed to the base 27, and a sphere 29 attached to the tip of the rod 28.
The rod 28 extends in a direction perpendicular to the direction in which the base 27 protrudes, and the ball 2 at the tip of the rod 28.
9 extends so as to face the smooth surface of the plate member 5.

When the air motor 2 shown in FIG. 1 is started in the above-described tightening tool, the rotational force of the air motor 2 is reduced.
The power is transmitted to the planetary gear mechanism 3 via the rotation output shaft 7 and the transmission shaft 8. Then, the rotational force of the air motor 2 is increased by the planetary gear mechanism 3. The drive shaft 4 receiving the increased rotation output rotates together with the tightening member 9 to tighten the tightened object fitted to the tightening member 9. At this time, the reaction force when the planetary gear mechanism 3 rotates the drive shaft 4 acts on the casing 21 via the internal gear 25 in the direction of arrow R as shown in FIG. The part 29 moves to the position indicated by the two-dot chain line and presses the plate-shaped member 5. A large bending deformation occurs in the plate member 5, and the magnitude of the reaction force is detected based on a change in the resistance value of the strain gauge 6 attached to the plate member 5, and the rotation is proportional to the reaction force. Detect torque.

As described above, the plate-like member 5 receives the reaction force when the planetary gear mechanism 3 rotates the drive shaft 4 via the transmission member 26 extending outward in the radial direction, so that even a minute reaction force can be detected. it can. Therefore, even a small rotation torque of 10 kgf · cm or less can be accurately detected.

The strain gauge 6 is connected to the plate-like member 5.
, The strain gauge 6 can be easily attached.

In the above embodiment, the air motor 2 is used for tightening the object to be tightened. However, an AC (alternating current) motor, a servo motor, or the like may be used instead of the air motor.

[0018]

As is apparent from the above description, the fastening tool according to the first aspect of the present invention receives a reaction force when the booster drives the drive shaft by the plate-like member via the transmission member.
Since a large bending deformation occurs in the plate-like member and even a small reaction force can be detected, a small rotational torque of 10 kgf · cm or less can be accurately detected.

Further, in the tightening tool according to the first aspect of the present invention, since the strain gauge is attached to the plate-like member, the strain gauge can be easily attached.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a fastening tool according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a casing of a planetary gear mechanism in the tightening tool.

FIG. 3 is a schematic sectional view of a casing of a planetary gear mechanism in a conventional fastening tool.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Air motor 3 Planetary gear mechanism 4 Drive shaft 5 Plate-shaped member 6 Strain gauge 26 Transmission member

Claims (1)

[Claims] 1. A main body, a motor attached to the main body, an intensifier mounted on the main body for increasing a rotational force generated by the motor, and a motor that receives rotation output from the intensifier and rotates. A drive shaft that drives the object to be tightened; a transmission member fixed to the casing of the booster and extending radially outward; and a reaction force when the booster drives the drive shaft through the transmission member. And a plate-shaped member fixed to the main body, and a strain gauge attached to the plate-shaped member.