JPH0818260B2 - Impact wrench tightening force control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tightening force control device for an impact wrench used for tightening work such as bolts and nuts.

(Prior Art) Conventionally, in a production line or the like, an impact wrench is used when tightening bolts, nuts or the like in order to improve productivity. As an example of a device for controlling the tightening force of the impact wrench, there is a tightening force control device for the impact wrench disclosed in JP-A-57-201177. In this device, as shown in FIG. 4, an impact wrench 1 has an air motor 2 built-in, and a cam disk 4 is fitted to the front end of a rotor shaft 3 thereof. A rear side wall of the clutch frame 6 is fitted to the boss portion 5 of the cam disk 4 to form a rotation detecting body 7. As shown in FIG. 5, gear-shaped concavo-convex portions 8 ... Are formed on the outer periphery of the rotation detecting body 7 at predetermined intervals. A pair of detectors 10a fixed to the inner surface of the casing 9 of the impact wrench 1 in close proximity to the uneven portions 8 ...
10b is located. Each of the detectors 10a and 10b is attached by magnetic or electric so as to output a signal corresponding to the concavo-convex portion 8 ... And further so that the output waveforms of each of the detectors 10a and 10b have a phase difference of 90 °. ing. These detectors 10a, 10
As shown in FIG. 6, b is electrically connected to a hitting number setting device 12 via a rotation direction detector 11, and further, a hitting number setting device.
The output side of 12 is a flip-flop 13 and a relay circuit 14
Is connected to the solenoid valve 15 via.

The solenoid valve 15 is connected to a pipe for supplying compressed air from the compressed air supply source to the impact wrench 1, and the air motor 2 in the casing 9 is rotated in the left and right rotation directions. The cam frame 4 spline-fitted to the rotor shaft 3 of the air motor 2 is further fitted to the clutch frame 6
A hammer piece 17 supported by a shaft 16 is disposed between the front side wall and the rear side wall (rotation detecting body 7). This hammer piece 17 has an anvil fuselage as shown in FIG.
18 are releasably engaged with each other to transmit a rotational force to the anvil 19. With such a structure, when the resistance torque on the anvil 19 side reaches the air motor 2 when tightening the bolts or nuts, the rotation of the anvil 19 approaches the stop, and the hammer piece 17 and the anvil body 18 are stopped. If the locking force becomes weak, slippage occurs between them and they come off. At this time, as the resistance torque increases, the hammer piece 17 and the anvil body 18 are engaged with each other by shock, and the clutch frame 6 rotates in the opposite direction via the hammer piece 17 after the collision. . Tightening is performed by repeating this striking state. Then, when the number of hits reaches the preset desired number of hits, a carry signal is output from the hit number setting device 12, whereby the flip-flop 13 is actuated to close the solenoid valve 15, and the impact wrench 1 is actuated. It is supposed to stop.

(Problems to be Solved by the Invention) In the above configuration, the tightening condition of the bolts and nuts is not managed, and for example, the bolts are screwed diagonally or the screw thread is damaged and screwed halfway to stop. Or
Impact of the impact wrench, such as when foreign matter is caught in the screw threads, the head of the screw fits into the spatter and does not separate, or when the tightening force decreases due to abrasion of the impact wrench itself. Quality control by tightening is not enough with just the number.

Therefore, the present invention measures the counter rotation amount of the rotation detecting body with respect to the number of impacts of the impact wrench by a detector, and compares the counter rotation amount with the counter rotation amount with respect to the number of impacts which is a predetermined reference. It is therefore an object of the present invention to provide a tightening force control device for an impact wrench that can control the tightening condition of bolts, nuts, etc., and reliably manage tightening.

(Means for Solving Problems) A feature of the present invention for achieving the above-mentioned object is that a rotation detecting body is integrally fixed to a rotating portion of an impact wrench, and a pair of rotation detecting bodies are provided along a rotation direction of the rotation detecting body. A detector is provided, and the amount of anti-rotation of the rotation detection body with respect to the number of impacts of the impact wrench is measured based on a signal emitted from the detector due to counter-rotation of the rotation detection body caused by the rotational impact force of the impact wrench, This measured anti-rotation amount,
Normality determining means for making a determination by comparing with a normal pattern of the counter rotation amount with respect to the number of hits as a predetermined reference, and abnormality for making a determination with comparison with an abnormal pattern of the counter rotation amount with respect to the number of hits as a predetermined reference The determination means is provided.

(Operation) In the above configuration, the counter rotation amount of the rotation detector with respect to the number of impacts of the impact wrench is measured, and the measured counter rotation amount is used as the normal pattern of the counter rotation amount with respect to the number of impacts and the counter rotation with respect to the number of impacts. An abnormal pattern of the quantity is compared at the same time, and a control signal suitable for the applicable pattern is issued.

(Example) Below, the Example of this invention is described based on drawing. The impact wrench itself is the same as the one already described in the section of the prior art with reference to FIGS. 4 to 7, and therefore the preceding section will be referred to. Therefore, Fig. 1 ~
Only the embodiment according to the present invention will be described as shown in FIG.

First, in FIG. 1, as shown in FIGS. 4 and 5, a pair of detectors 10a and 10b are provided on the rotation detecting body 7 which is integrated with the clutch frame 6 along the uneven surface of the outer periphery thereof. It is arranged. The comparison / determination means 20 is connected from each of the detectors 10a and 10b. To describe the configuration of the comparison / determination means 20, the amplifiers 22a and 22b are connected from the respective detectors 10a and 10b by a lead wire 21, and further, the rotation direction detector 23 is connected from the amplifiers 22a and 22b. It is connected. When the rotation detecting body 7 rotates in the opposite direction to the anvil 19, each of the detectors 10a and 10b is
They are attached so that they have a phase difference of 90 ° from each other.
For example, when the rotation detecting body 7 rotates in the same direction as the anvil 19, the signal of 10a advances 90 ° more than the 10b signal, and when the rotation detecting body 7 rotates in the opposite direction of the anvil 19, , 10a is output 90 ° later than the signal of 10b. The rotation direction detector 23 detects the rotation direction based on the phase difference between 10a and 10b. Hammer piece as described above
When the engagement between 17 and the anvil body 18 is shocked, the clutch frame 6 (rotation detecting body 7) rotates in the direction opposite to the rotation direction of the anvil 19, so that the rotation amount in this reverse direction is changed. It is designed to be measured as the number of uneven gears. The rotation direction detector 23 is branched and connected to two reversal angle measuring devices 24a and 24b, respectively, and further, from the respective reversal angle measuring devices 24a and 24b, a normal comparator 25
And the abnormality comparator 26 are connected. Further, the solenoid valve 15 is connected from the normal comparator 25 and the abnormal comparator 26 so as to operate according to the respective output signals. The solenoid valve 15 has the same function as the solenoid valve 15 shown in FIG. As described above, the configuration of the reversal angle measuring devices 24a, 24b and the normal comparator 25 and the abnormal comparator 26, which are paired, is such that one is the normal judging device 27 and the other is the abnormal judging device.
28. It should be noted that the normality determiner 27 and the abnormality determiner
28 each have a memory function, for example, the second
The normal tightening pattern as shown in the figure is stored in the normality comparator 25 of the normality determiner 27, and the abnormal tightening pattern as shown in FIG. 3 is stored in the abnormality comparator 26 of the abnormality determiner 28. There is. Then, the signal from the rotation direction detector 23 is adapted to be input to both the normal determiner 27 and the abnormal determiner 28, and from the normal determiner 27, the input signal corresponds to the normal tightening pattern. If so, an output signal is generated to close the solenoid valve 15 and stop the impact wrench 1. If the input signal corresponds to the abnormal tightening pattern, the abnormality determiner 28 outputs an output signal to inform the operator of the abnormality by a display device or alarm device (not shown). The valve 15 is closed.

The operation of the tightening force control device for the impact wrench having the above-described structure is as follows. First, the rotational torque of the air motor 2 is transmitted from the cam disk 4 to the anvil 19 via the hammer piece 17, and the bolt attached to the tip of the anvil 19. Or rotate the nut and screw it into the other side. At this time, since the rotation detecting body 7 also rotates, detection signals are generated from the detectors 10a and 10b.

However, when the screw tightening progresses as described in the section of the related art, the resistance torque on the anvil 19 side increases, and the engagement between the hammer piece 17 and the anvil body 18 is shocked, the rotation detection is performed. The body 7 rotates in the direction opposite to the anvil 19. At this time, the number of teeth of the unevenly rotated parts 8 ...
Detected by 10a and 10b, the respective signals are amplified with a phase difference of 90 ° and transmitted to the normal judging device 27 and the abnormal judging device 28.

When the first signal is input to the normality determiner 27, the rotation detector 7 is rotated in the opposite direction by the reversal angle measuring device 24a.
The number of teeth is measured. This number of teeth is measured as a counter-rotation amount of the first signal as shown in FIG. 2 as a normal tightening pattern. In the case of the first signal, since the bolt or nut is tightened at a large angle with respect to the hit by the anvil 19, the amount of counter-rotation, that is, the recoil is small. Next, this input signal is compared with the reference signal of the anti-rotation amount which is stored in the normal comparator 25 and serves as a reference for the first impact. If the input signal compared with this reference signal is within a predetermined threshold range, the first input signal is determined to be normal.

The anti-rotation amount of the signal input for each number of hits is successively measured in the same manner as the first input signal, and then the anti-rotation amount for each number of hits stored in the normal comparator 25 as shown in FIG. Of the reference signal. As shown in FIG. 2, since the number of hits has reached 20 to 25 and sufficient screw tightening has been performed, the counter-rotation amount of the rotation detection body 7 is large, and even when the rotation detection body 7 becomes almost constant, the detector 10a If the anti-rotation amount of the signals input from 10 and 10b is within the threshold range, the normal comparator 25 outputs an output signal and the solenoid valve 15 is demagnetized so that the rotation of the air motor 2 is prevented. It is stopped and the screw tightening has been normally performed.

From the signals input to the abnormality determiner 28 at the same time, the rotation detector 7 is detected by the reversal angle measuring device 24b in the same manner as described above.
The anti-rotation amount is measured and then compared with the abnormal tightening pattern stored in the abnormality comparator 26 as shown in FIG. If the anti-rotation amount of each of the compared signals is within a predetermined threshold range set in the abnormal tightening pattern, an output signal is issued from the abnormal comparator 26, and an alarm device (not shown) is activated. The solenoid valve 15 is demagnetized at the same time as ringing and turning on the lamp. In this case, since the screw tightening is insufficient even when the number of hits reaches a predetermined value, the air motor 2 is forcibly stopped and the screw tightening is not performed any more.

The input signals from the detectors 10a, 10b are
It is input to both 7 and the abnormality determiner 28, but if the abnormality comparator 28 and the normal comparator 27 simultaneously count up in one step of screw tightening, the abnormality comparator 28 has priority.

As described above, the tightening force control device for an impact wrench of the present invention can detect abnormal tightening of bolts, nuts, etc. without the operator having to be aware of it. It is possible to eliminate the need for additional tightening with a wrench.

Further, when the screw is tightened by a robot, the tightening tool of the present invention is lightweight and small in size, so that it is more economical than the conventional nut runner system. Further, by using the micro computer, it is possible to record data for quality control, and central control can be performed.

(Effects of the Invention) From the above, according to the tightening force control device for an impact wrench of the present invention, the anti-rotation amount of the rotation detecting body with respect to the number of impacts of the impact wrench is measured, and the measured anti-rotation amount is measured. Is compared with a pre-stored abnormal pattern stored in advance as well as a normal pattern of anti-rotation amount for each number of impacts from the start to the end of screw fastening. Even if an abnormal tightening state occurs at a stage and the tightening torque becomes insufficient, and after that, galling of the screw, seizure, etc. occur and an apparent tightening torque rises,
There is no risk of deciding that the screw has been normally tightened. Therefore, it is possible to accurately determine whether or not the screw has been normally tightened at the initial stage, so that the quality control of the tightening is surely executed and a reliable screw tightening device can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a tightening force control device for an impact wrench according to the present invention, FIG. 2 is a graph showing a normal tightening pattern, and FIG. 3 is a graph showing an abnormal tightening pattern. FIG. 4 is a vertical sectional view showing a conventional impact wrench, FIG. 5 is a sectional view shown by an arrow AA in FIG. 4, and FIG. 6 is a configuration diagram showing a conventional tightening control device. FIG. 7 is a sectional view shown in FIG. 4 by an arrow BB. 1 ... Impact wrench, 7 ... Rotation detector 10a, 10b ... Detector, 20 ... Comparison judgment means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Kobayashi 3-6-15 Nonogami, Habikino City, Osaka Prefecture Soraken Co., Ltd. (56) References JP-A-59-53168 (JP, A) JP-A-SHO 55-58988 (JP, A) JP 59-118380 (JP, A) JP 61-37505 (JP, Y2)

Claims (1)

[Claims] 1. A rotation detecting body integrally fixed to a rotating portion of an impact wrench, a pair of detectors being provided along a rotation direction of the rotation detecting body, wherein the rotation detecting body is generated by a rotation impact force of the impact wrench. The anti-rotation amount of the rotation detection body with respect to the number of impacts of the impact wrench is measured based on the signal emitted from the detector by the anti-rotation of the impact wrench, and the measured amount of anti-rotation is the number of impacts as a predetermined reference. Is provided with normality determining means for making a determination by comparing with a normal pattern of anti-rotation amount with respect to, and abnormality determining means for making a determination by comparing with an abnormal pattern of anti-rotation amount with respect to the number of hits as a predetermined reference. Tightening force control device for impact wrench.