JPS6124152B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an impact wrench used for tightening bolts, nuts, etc., which detects the number of blows occurring at the end of tightening and stops the operation of the impact wrench. This relates to a control device.

Traditionally, when tightening a large number of screws such as bolts and nuts in automobile factories, etc., a torsion bar is attached to a one-hammer type or two-hammer type impact wrench. There are individual differences in the tightening time depending on the worker, and even in the same task, unnecessary tightening or insufficient tightening may occur.
There were drawbacks such as variations in the tightening force of a large number of bolts and nuts, making it impossible to perform accurate tightening work.

The purpose of the present invention is to eliminate such drawbacks and always tighten screws with a predetermined tightening torque.
When rotating and screwing together a screw such as a nut, the rotation detector and sensor detect the impact rotation generated by the engagement and disengagement of the hammer piece at the end of the screwing, and the number of impacts reaches a preset value. The present invention provides a tightening force control device for an impact wrench, characterized in that it is configured to stop the operation of the impact wrench at certain times.

Embodiments of the present invention will be explained with reference to the drawings: 1
is an impact wrench, and the boss portion 4 of the cam disk 4 fitted to the front end of the rotor shaft 3 of the air motor 2
The rear wall 5b of the clutch frame 5 is fitted into the rear wall 5b, and uneven portions 6a, 6 are formed at predetermined intervals on the outer periphery of the rear wall 5b.
A gear-shaped rotation detecting body 6, which is formed by continuously providing b on the entire outer periphery, is fixed integrally and concentrically.

Note that this rotation detection body 6 may be integrally fixed to the rear end rotor shaft 3a of the air motor 2 as shown in FIGS. .

Reference numerals 7 and 8 denote a pair of sensors, such as a magnetic sensor and an electric sensor, which are fixed to the inner surface of the casing 1a of the impact wrench 1 in close proximity to the outer peripheral surface of the rotating body 6, and whose output waveforms have a phase difference of 90°. It is installed like this. These sensors 7 and 8 are connected to D-
The flip-flop 9 is electrically connected to the number of blows setting device 10 by wiring, and the output side of the number of blows setting device 10 is connected to an R-S flip-flop 11,
It is connected to a solenoid valve 13 via a relay circuit 12. Reference numeral 14 is a printer connected to the number of blows setting device 10, which automatically displays the number of bolts and nuts that have been tightened, and can check if the number of bolts or nuts that have been tightened matches the number of screws to be tightened. It is.

15 is a reset button connected to flip-flop 11.

The solenoid valve 13 is disposed in a pipe 17 that supplies compressed air from a compressed air supply source 16 to the impact wrench 1, and a stop valve 18 and an air pressure adjustment unit 19 are installed in the pipe between the solenoid valve 13 and the compressed air supply source 16.
is arranged. Note that the solenoid valve 13 may be built into the casing 1a of the impact wrench 1.

Various known structures can be adopted as the structure of an impact wrench that operates by supplying compressed air, but the example shown is one in which the inside of the casing 1a is operated by operating a control lever 20 and a switching valve (not shown). The air motor 2 is rotated at high speed in the left or right direction, and the outer periphery of the front and rear side walls 5a, 5b of the clutch frame 5 is rotated from a cam disk 4 that is integrally spline-fitted to the front end of the rotor shaft 3 of the air motor 2. By removably engaging the hammer piece 22 with the body 24 of the anvil 23 rotatably supported on the front end of the casing 1 via the hammer piece 22 which is supported between the parts so as to be able to swing from side to side. Rotation from the air motor 2 side is transmitted to the albil 23.

The hammer piece 22 is bent into a dogleg shape as shown in Figs. Engagement grooves 24a, 24
b, respectively, and an engagement piece 25 is integrally provided at the center of the rear part of the hammer piece 22, and both side surfaces 25a and 25b of the lower end of the engagement piece 25 are recessed in a part of the outer circumference of the cam disc 4. Opposite side 2 of the recess 26 provided
6a and 26b so as to be able to come into contact with each other.

To describe the operation of the embodiment configured as above, first, the impact wrench 1 is connected to the compression supply source 16.
The impact wrench 1 is connected to the piping 17 on the side, and the sensors 7 and 8 built in the impact wrench 1 are connected to the blow number setting device 10, and the solenoid valve 13 on the piping is electrically connected to the blow number setting device 10. Thereafter, the power to the number of blows setting device 10 is turned on, the counter of the number of blows setting device 10 is set to the desired number of blows, and the reset button 15 is pressed to set the starting state.

When the work preparation is completed in this way, the operation lever 2
Press 0 to rotate the air motor 2 clockwise, and the rotation is transmitted from the rotor shaft 3, cam disc 4, clutch frame 5, and hammer piece 22 to the anvil 23, which is fitted onto the corner shaft of the anvil 23. The bolt, nut, etc. fitted into the socket body are rotated and screwed by rotating the socket body (not shown).

In this way, the rotational torque of the air motor 2 is transmitted from the cam disk 4 to the anvil 23 via the hammer piece 22, causing the bolts and nuts to rotate and screw. At this time, the rotor shaft or clutch frame of the air motor 2 A rotation detector 6 fixed to a rotating part such as 5 also rotates integrally, causing the sensors 7 and 8 to generate pulses. These sensors 7,
The waveforms of the pulses generated by sensor 8 are generated with a certain phase difference as shown in Figure 4, A and B, respectively. In this figure, when the waveform of sensor 7 is upward, the waveform of sensor 8 is It is in a horizontal state.

Next, when the bolts and nuts are screwed and the resistance torque from the anvil side reaches the motor torque, the rotation of the anvil 23 approaches a stop, and therefore, the one inner end 22a of the hammer piece 22 and the anvil body 24
The locking force between the anvil body 24 and the anvil body 24 becomes weaker, and the hammer piece 22 detaches from the engagement groove 24a and runs free together with the air motor 2, causing slippage between the two, and the anvil body 24 is engaged again. The matching groove 24a and one inner end 22a of the hammer piece 22 are brought into engagement.

However, when there is a resistance torque greater than the rotational torque of the motor 2 on the anvil 23 side, the engagement groove 24a of the anvil body 24 and the hammer piece 22 are immediately disengaged, and as the resistance torque increases, The engagement between the two is impactful, and the cam disk 4 rotates while rebounding (rotating in the opposite direction) via the hammer piece 22, and by repeating this impact, the screw is tightened. It is completely tightened.

When this impact is performed, the rebound of the cam disc 4 causes the waveform of the pulse detected by the rotation detector 6 and the sensors 7 and 8, and the output of the waveform A' by the sensor 7 as shown in FIG. and the lower horizontal line of the waveform B' detected by the other sensor 8 are in a state of coincidence, and when the rotational drive of the cam disk 4 is started from this state, the waveforms A and B as described above are again formed.

Here, when the cam disk 4 rotates clockwise, 1;
If it is set to 0 during counterclockwise rotation for rebound, the line diagram shown in Figure 4 C will be obtained.
At the time of impact, the value changes from 1 to 0, and when the motor 2 overcomes the rebound and starts rotating normally, it changes from 0 to 1, which is transmitted to the number of hits setting unit 10 via the D-flip-flop 9, and the number of hits set by the number of hits setter 10 is The inversion of the output that occurs each time is continued. When the number of blows reaches the desired number of blows set in advance, a carry signal is output from the number of blows setting device 10, thereby actuating the R-S flip-flop 11 and closing the solenoid valve 13. This causes the impact wrench 1 to stop operating.

Next, when the impact wrench 1 is to be operated, the reset button 10 may be pressed to make it ready for operation. Note that automation is also possible if an auto-reset circuit is provided.

As described above, the present invention provides a pair of sensors that are arranged opposite to the rotation transmission part of an impact wrench and have a predetermined phase difference in the non-rotation part, and both sensors are connected to the reversal detection circuit of the rotation transmission part. The sensor is configured to detect the reversal of the rotation transmitting part that occurs when the impact wrench is struck by changes in pulse signals from these sensors, and is connected to the reversal detection impact setting device to determine the number of reversals of the rotation transmitting part. The impact setting device is configured to detect the impact, and is further connected to a circuit that stops the operation of the impact wrench based on an output signal when the number of impacts set by the impact setting device reaches a predetermined number. Since this is related to a tightening force control device for an impact wrench, the number of blows of an impact wrench is correlated with the tightening torque of screws, etc., so that the desired number of blows can be achieved by a preset number of blows. It is possible to obtain a tightening torque, and this device can make the tightening torque of a large number of screws almost the same, so there is no need to over-tighten or hit too many times due to unnecessary hits like with conventional impact wrenches. This completely eliminates the problem of insufficient tightening force due to insufficient tightening force, automatically tightens to the specified torque, and also tightens any screws that have been forgotten, allowing highly accurate tightening work. .

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a simplified side view thereof, FIG. 2 is a wiring circuit diagram, FIG. 3 is a piping circuit diagram, FIG. 4 is a pulse diagram, and FIG. Vertical side view of impact wrench, Figure 6 is Figure 5A
-A cross-sectional view taken along the A line; Figures 7 to 10 are longitudinal front views for explaining its function; and Figure 11 is a vertical side view of the main parts of the impact wrench when the detection part is fixed to the rotor shaft side. , Figure 12 is the 11th
It is a sectional view taken along line B-B in the figure. 1 is an impact wrench, 2 is an air motor, 4
1 is a cam disc, 6 is a rotation detector, 7 and 8 are sensors, 10 is a blow count setting device, 13 is a solenoid valve, 15 is a reset button, 16 is a compressed air supply source, 22 is a hammer piece, and 23 is an anvil.

Claims (1)

[Claims] 1. A pair of sensors are installed in the non-rotating part of the impact wrench facing the rotation transmitting part with a predetermined phase difference, and both sensors are connected to the reversal detection circuit of the rotation transmitting part to detect what happens when the impact wrench hits. The reversal of the rotation transmitting section is detected by changes in pulse signals from these sensors, and the reversal detection circuit is connected to a stroke number setting device, so that the number of reversals of the rotation transmission section is determined by the stroke setting device. An impact wrench, characterized in that the impact setting device is connected to a circuit that detects the impact and stops the operation of the impact wrench by an output signal when the number of impact settings of the impact setting device reaches a predetermined number. Tightening force control device.