JPH0699362A - Tightening completion deciding device for electric motor-driven impact wrench - Google Patents

Abstract

PURPOSE:To tighten all the bolts by specified tightening force by providing a tightening completion deciding device for an electrion motor-driven impact wrench capable of surely deciding tightening completion of the bolt. CONSTITUTION:A mounting base 9 is rotatably externally fitted to a socket 2 of an electric motor-driven impact wrench main unit 1, to also stop the mounting base 9 to turn from a side of the electric motor-driven impact wrench main unit 1, and a rotary encoder 15 (rotation detector) is mounted on the mounting base 9. A toothed pulley 17 is rotatably supported to a detecting shaft 16 of the rotary encoder 15, and further a toothed pulley 18 is integrally externally fitted to the socket 2, to provide a toothed belt 19 linked between both the toothed pulleys 17, 18. A control unit 20 for calculating a rotational speed per second unit of the socket 2, based on a pulse signal 21 (detection signal) output from the rotary encoder 15, and further for deciding a bolt 3 to complete tightening, when reaching a specified rotational speed/second, is connected to the rotary encoder 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening completion determining device for an electric impact wrench.

[0002]

2. Description of the Related Art Conventionally, there has been known an electric impact wrench capable of quickly and surely fastening a bolt by applying rotation to the bolt by impact. In the present situation, when the bolt is tightened by operating the above, the completion of the bolt tightened by the electric impact wrench is judged based on the intuition of the worker.

Further, in recent years, it has been considered in various fields to automatically substitute the bolt fastening work using the electric impact wrench by a robot or the like. It is conceivable to investigate in advance how long the bolt will be tightened with the specified tightening force after starting and set the predetermined time determined based on the result in a timer etc. ing.

[0004]

However, when a worker performs a bolt fastening operation using an electric impact wrench, the fastening operation is usually performed with a large torque so as to increase the work efficiency. If the judgment is delayed, the bolt may be excessively tightened, and the screw hole may be damaged due to excessive tightening of the bolt, resulting in shortening the life of the fastening portion.

Further, when the fastening work is performed by a robot or the like, if the fastening completion is judged by the work time management using a timer or the like, the tightening resistance is caused by the quality of the bolts and nuts or foreign matters between the screws. Since it is often different, the fastening completion time was not constant, and it was difficult to fasten all the bolts with the prescribed fastening force.

The present invention has been made in view of the above circumstances, and provides a fastening completion determination device for an electric impact wrench that can reliably determine the completion of bolt fastening.
The purpose is to tighten all bolts with the specified tightening force.

[0007]

The present invention is based on a rotation detector capable of detecting the number of rotations of a socket provided at the tip of an electric impact wrench main body, and a detection signal output from the rotation detector. Completion of fastening of an electric impact wrench, comprising: a control device that calculates the number of revolutions of the socket per unit time and determines that the fastening of the bolt is completed when the number of revolutions reaches a prescribed value. It relates to a determination device.

[0008]

Therefore, according to the present invention, when the bolt is fitted into the socket of the electric impact wrench body and the socket is rotated to start the fastening operation of the bolt, the rotation speed of the socket is measured by the rotation detector, and the detection signal thereof is detected. Is input to the control device.

In the control device, the relationship between the socket rotation speed per unit time and the bolt fastening force at the time of completion of fastening is set in advance, so that the socket calculated based on the detection signal output from the rotation detector. When the number of revolutions per unit time reaches a specified value, it is determined that the fastening of the bolt is completed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of a fastening completion judging device for an electric impact wrench according to the present invention.
Is an electric impact wrench body, 2 is a socket provided at the tip of the electric impact wrench body 1, and the socket 2 has a fitting concave portion 4 at the tip end, which can be fitted into the head 3a of the bolt 3. The end portion has a mounting hole 6 into which the drive shaft 5 of the electric impact wrench body 1 can be inserted. The drive shaft 5 inserted into the mounting hole 6 is detachably connected by a pin 7, The O-ring 8 is fitted on the base end of the socket 2 so that the socket 7 is prevented from coming off.

Further, a mounting base 9 having a projecting portion 9a projecting laterally is fitted to the outer periphery of the socket 2 via a ball bearing 10 on the tip side of the O-ring 8 of the socket 2 so as to be freely rotatable. And a locking bracket 1 protruding from the mounting base 9 at a desired position on the outer periphery thereof.
In the locking hole 12 of No. 1, the tip of a rotation stop rod 14 attached to the electric impact wrench body 1 side via an L-shaped attachment 13 is fitted and the mounting base 9 is attached to the electric impact wrench body 1. It is designed to be stopped against.

That is, the mounting base 9 is held at a stationary position when viewed from the electric impact wrench body 1 side, and the socket 2 can rotate without being restricted by the mounting base 9.

Further, the protruding portion 9a of the mounting base 9 is
A rotary encoder 15 (rotation detector) is attached to the rotary encoder 15, and a toothed pulley 17 is axially supported on a detection shaft 16 of the rotary encoder 15. A toothed pulley 18 is integrally fitted to the socket 2 so as to correspond to the toothed pulley 17, and a toothed belt 19 is stretched between the toothed pulleys 17 and 18.

Further, the rotary encoder 15 is connected to a control device 20 arranged at a required place, and the control device 20 inputs a pulse signal 21 (detection signal) output from the rotary encoder 15. To calculate the number of revolutions of the socket 2 in seconds by converting the counted number of the pulse signal 21 into the number of revolutions of the socket and comparing it with time. 3 is determined to be completed, and the stop signal 22 for stopping the rotation of the socket 2 is output.

That is, when the bolt 3 is tightened by the socket 2 of the electric impact wrench body 1 and the head 3a of the bolt 3 reaches the fastened member side, as shown in FIG. Decreases as the bolt 3 is tightened and the tightening is completed, and finally the rotation cannot be measured. However, if the tightening of the bolt 3 is continued until the rotation of the socket 2 is no longer measured, the tightening force will be over the specified value due to overtightening. Therefore, the relationship between the socket rotational speed in seconds and the tightening force of the bolt 3 is previously determined. A master curve is prepared by measurement, and the socket rotation speed per second at which the fastening force of the bolt 3 becomes a prescribed value is set as the prescribed rotation number / second for determining the completion of the fastening of the bolt 3. .

When the head 3a of the bolt 3 is fitted into the fitting recess 4 of the socket 2 of the electric impact wrench body 1 and the socket 2 is rotated to start the fastening operation of the bolt 3, the socket 2 Toothed pulley 1
8, the detection shaft 16 of the rotary encoder 15 is rotated via the toothed belt 19 and the toothed pulley 17, and a pulse signal 21 is output from the rotary encoder 15 and input to the control device 20.

In the controller 20, the pulse signal 21 (detection signal) output from the rotary encoder 15 is used.
Is counted, and the count number of the pulse signal 21 is converted into the socket rotation speed and collated with time to calculate the rotation speed of the socket 2 in seconds, and when the specified rotation speed / second is reached. It is judged that the fastening of the bolt 3 is completed,
The rotation of the socket 2 is stopped by the stop signal 22.

The prescribed number of revolutions / second for judging completion of the fastening of the bolt 3 is a very small value, and the bolt 3
Even if the number of rotations / second of the socket 2 decreases during tightening due to the quality of screws and nuts (not shown) or the influence of impurities between screws, etc., the completion of fastening the bolt 3 is much smaller than this value. Since the determination is made in step 1, there is no erroneous determination that the fastening is completed while the bolt 3 is being tightened.

Therefore, according to the above-described embodiment, the number of revolutions of the socket 2 per second is measured, and the fastening of the bolt 3 is completed when the number of revolutions per second of the socket 2 reaches the specified number of revolutions / sec. Since it can be determined that this has been done, if the stop signal 22 is output and the rotation of the socket 2 is stopped when the determination is made, all the bolts 3 can be fastened with the prescribed fastening force.

The fastening completion determining device for an electric impact wrench according to the present invention is not limited to the above-described embodiment, and the rotation detector is not limited to a rotary encoder. It goes without saying that various changes can be made within the range not covered.

[0022]

According to the above-described fastening completion judging device for an electric impact wrench of the present invention, the rotation speed of the socket in seconds is measured, and when the rotation speed of the socket reaches a prescribed value. Since it can be determined that the fastening of the bolts is completed, if the rotation of the socket is stopped when the determination is made, it is possible to achieve the excellent effect that all the bolts can be fastened with a prescribed fastening force. .

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a plan view of the mounting base of FIG.

FIG. 4 is a view in the direction of arrows IV-IV in FIG.

FIG. 5 is a graph showing the relationship between the socket rotation speed in seconds and the bolt fastening force.

[Explanation of symbols]

 1 Electric Impact Wrench Main Body 2 Socket 3 Bolt 15 Rotary Encoder (Rotation Detector) 20 Control Device 21 Pulse Signal (Detection Signal)

Claims (1)

[Claims] 1. A rotation detector capable of detecting a rotation speed of a socket provided at a tip of an electric impact wrench body, and a rotation speed of the socket per unit time based on a detection signal output from the rotation detector. And a control device that determines that the fastening of the bolt is completed when the rotational speed reaches a prescribed value, and a fastening completion determining device for an electric impact wrench.