JPH0583344B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tightening control device for an impact wrench.

(Prior Art) An impact wrench is a tool that is relatively frequently used as a tool for tightening various objects to be fastened, such as bolts and nuts, because the impact wrench generates little reaction during tightening work. By the way, when performing tightening work on objects to be fastened using this impact wrench, it is necessary to stop the tightening work when the tightening torque acting on the objects to be fastened reaches a predetermined value. . In other words, if you stop tightening work while the tightening torque acting on the bolt or nut is small, sufficient tightening force will not be obtained, and if you continue tightening work until a high torque is reached, the bolt This is because it may be damaged. Therefore, various devices have been developed and put into practical use to stop the operation of the impact wrench when a predetermined tightening torque is reached.
As an example, the applicant's earlier application (Utility Model Application No. 59
An example of this is the impact wrench tightening control device described in No.-163467). This device is
The reaction rotation amount detection mechanism detects the reaction rotation amount of the output shaft of the air motor after impact, and the detected reaction rotation amount is integrated and counted by a counter. When this reaches a predetermined count value, A command signal is issued to the air supply cutoff mechanism to close the air supply passage, and this device makes it possible to accurately and automatically control the tightening torque of objects to be fastened.

(Problems to be Solved by the Invention) However, in the above control device, the following problems may occur. That is,
For example, if a bolt has been improperly tightened and needs to be loosened, it will not be possible to simply change the direction of rotation of the air motor from forward to reverse by operating the forward/reverse switching lever on the impact wrench. The reaction rotation amount detection mechanism detects the rotation amount of the output shaft as the reaction rotation amount during normal rotation, and as a result, the air supply passage is closed. For this reason, it is conceivable that the operator would be able to release the control by the control device and use the impact wrench in a free state by operating a switch for canceling the control function provided on the control device. Usually, the main body of the control device is located at a certain distance from the place where the work is performed, so the worker must go to the place where the main body of the control device is located each time. Therefore, canceling the control function requires a lot of effort. Therefore, it is possible to separate the switch for canceling the control function from the main body of the control device and place it near the impact wrench, or to attach it to the impact wrench itself, but in either case, it is possible to There is still the problem that two operations are required, one for operating the control function and the other for canceling the control function, and it is difficult to expect much improvement in work efficiency.

This invention was made in order to solve the above-mentioned conventional drawbacks, and it is possible to switch the rotation direction of the air motor of the impact wrench and cancel the control function with a single touch operation. An object of the present invention is to provide a tightening control device for an impact wrench that can improve efficiency.

(Means for Solving the Problems) Therefore, the impact wrench tightening control device of the present invention includes an air motor, a tightening torque generation mechanism driven by the air motor,
In the impact wrench, the impact wrench includes a switching valve mechanism installed in the air supply passage to switch the rotational direction of the air motor, and a detection means for detecting a torque characteristic value of the tightening torque generated by the tightening torque generating mechanism; a control means that issues a command signal when the torque characteristic value detected by the means reaches a reference value; an air supply cutoff mechanism that closes the air supply passage in response to a command signal from the control means; and a release means for stopping the output of the command signal, and the release means is constructed so as to be interlockable with the switching valve mechanism of the impact wrench.

(Function) In the impact wrench tightening control device described above, when the operator operates the changeover valve mechanism of the impact wrench, the rotational direction of the air motor is switched, and the release means is interlocked with the changeover valve mechanism. , the control function is canceled by stopping the output of the command signal from the control means. In other words, the rotation direction of the air motor can be switched and the control function can be canceled with a one-touch operation.

(Embodiments) Next, specific embodiments of the impact wrench tightening control device of the present invention will be described in detail with reference to the drawings.

First, as shown in FIGS. 1 to 3, this impact wrench A has a grip part 1 and a main body casing 2 that is connected to the grip part 1 and extends in the front-rear direction. The main casing 2 includes a central casing 3 that is integrally connected to the upper end of the grip part 1, a front casing 4 that extends further forward from the front end of the central casing 3, and a rear casing that covers the rear of the central casing 3. 5, an air motor 6 is housed in the central casing 3, a tightening torque generation mechanism 7 is housed in the front casing 4, and a reaction rotation amount detection mechanism 8 is housed in the rear casing 5. ing. The tightening torque generating mechanism 7 includes a cam 11 connected to the tip of the output end 9 of the air motor 6 by a spline, hammers 12, 12 that are rotationally driven by the cam 11, and hammers 12, 12. a hammer frame that supports and rotates together with the hammers 12, 12; an anvil (not shown) that receives blows from the hammers 12, 12; The tip of the main shaft 15 is guided outward beyond the front end of the casing 4, and a tightening socket (not shown) can be removably attached thereto. being done. The air that operates the air motor 6 passes through the air supply passage 18 in the grip part 1 from the air supply pipe connection port 17 attached to the lower end of the grip part 1.
The air is supplied to the air motor 6 via the air supply valve mechanism 19 and the forward/reverse switching valve mechanism 21. It is discharged to the outside through the passage 20. Note that an air supply cutoff mechanism such as a solenoid valve, which will be described later, is interposed in the air supply passage that supplies working air to the air motor 6. The air supply valve mechanism 19 has an operation knob 22 protruding in front of the grip part 1, and a valve element 24 formed at the inner tip of a valve rod 23 that is directly connected to the operation knob 22. The seal ring 16 is fitted into a concave groove provided on the outer peripheral surface of the valve stem 2.
A step part for the seal ring 16 to come into contact with is provided around the inner peripheral surface of the bottomed cylindrical valve member 25 fitted in the grip part 1 so as to surround the valve seat 2.
6, and a spring 10 is interposed between the end surface of the valve element 24 and the bottom surface of the valve member 25. Therefore, due to the action of the spring 10, the seal ring 16 is always urged toward the valve seat 26 via the valve element 24, and the operation knob 2
2, the seal ring 16 of the valve element portion 24 is separated from the valve seat 26. Air can then be supplied in the direction of the air motor 6 through the gap formed in this portion and the inside of the valve member 25, through a through hole 27 formed in the valve member 25. Further, a first magnet 28 is attached to the end surface of the valve part 24.
However, a first reed switch (lever interlocking switch) 29 consisting of a Hall IC arranged corresponding to the first magnet 28 is attached to the bottom surface of the valve member 25. When starting air supply to the air motor 6, the first reed switch 29 is activated in the vicinity of the first magnet 28,
A tightening control device, which will be described later, can be activated. Therefore, this first reed switch 29
A connection (not shown) passes through the exhaust passage 20 and is led out to the outside via a connector 32 provided at the lower end of the grip portion 1. The forward/reverse switching valve mechanism 21 provided in the air supply passage 18 projects a forward/reverse switching lever 33 in front of the grip portion 1, and connects the base of the lever 33 with a bottomed cylindrical casing 34. The lever 33 is rotatably supported on the gripping portion 1 side.
A valve portion 43 for changing the direction of air supply to the air motor 6 is formed at the base of the air motor 6. A second magnet 44 is buried at an eccentric position on the base end surface of the forward/reverse switching lever 33 with one end surface thereof facing the bottom surface of the casing 34, and the second magnet 44 is embedded in the bottom surface of the casing 34 at A second reed switch (changeover valve interlocking switch) 45 made of a Hall IC is attached at a position corresponding to the second magnet 44. In this case, the second reed switch 45 is
As shown in FIG. 5, the forward/reverse switching lever 33 is disposed at a position opposite to the second magnet 44 when the forward/reverse switching lever 33 points to the reverse (left rotation) position. That is, as shown in FIG. 4, when the forward/reverse switching lever 33 is pointing to the forward (clockwise) position, the second reed switch 45 is in the OFF state, and the forward/reverse switching lever 33 is in the fifth position. As shown in the figure, when the second magnet 44 is about to move to the reverse position, it detects the proximity of the second magnet 44, which turns it into an ON state and cancels the control function of the tightening control device, which will be described later. There is. The connection (not shown) of this second reed switch 45 is also led out to the outside via the connector 32 at the lower end of the gripping part 1.

Next, the reaction rotation amount detection mechanism 8 disposed inside the rear casing 5 will be explained. It is of a rotary encoder type and includes a pair of photo interrupters 36 and 37 arranged with a phase difference between them. The rotary disk 35 has a large number of slits bored along its circumferential direction, and bolts are inserted through washers 41 into the free end of a lead-out shaft 39 fixed to the rear end of the output shaft 9 of the air motor 6. 42. Each photo interrupter 36, 37 has a rotary disk 3
It consists of a pair of light emitting diodes and a phototransistor that are arranged in positions facing each other through the slits 5, and the number of slits passed between them corresponds to the rotation angle of the rotary disk 35 and the output shaft 9. Generates a number of signals. Since both photo interrupters 36 and 37 are arranged with a phase shift, the signal from one photo interrupter 36 and the signal from the other photo interrupter 37 have a phase difference, so that the pulse edge of one signal has a phase difference. By determining the level of the other signal, it is possible to detect the direction of rotation of the rotary disk 35. Therefore, by using the rotary encoder described above, the hammer 12
After colliding with the anvil, only the reaction rotation angle when the output shaft 9 of the air motor 6 returns in the opposite direction due to the reaction of this collision can be detected. As shown in FIGS. 1 and 6, the outputs of the photo interrupters 36 and 37 are led out from the connector 30 through the exhaust passage 20 and from the connector 32 to the control device.

In this way, the impact wrench A has various mechanisms such as the tightening torque generation mechanism 7, the reaction rotation amount detection mechanism 8, and the forward/reverse switching valve mechanism 21. A control device for controlling the tightening torque when tightening an object will be explained based on FIG. 7. In the figure, a rotating disk 35 and photo interrupters 36, 3
7 is as described above, but the outputs from the photo interrupters 36 and 37 are first sent to the Schmitt circuit 51 and subjected to waveform shaping. The count pulse output from the Schmitt circuit 51 is then sent to the gate 52. Next, from the gate 52,
A count pulse in the direction of reaction rotation will be output, and this output is sent to an addition/subtraction counter 55 through a multiplier circuit 54 in order to increase resolution. The addition/subtraction counter 55 integrates and counts these count pulses, and when this count reaches the preset count number set in the Samir switch 65, it issues a command signal to activate the relay 57, which activates the solenoid valve. The air shutoff mechanism 58 is operated to close the air supply passage, and the operation of the air motor 6 is stopped to complete the tightening work. In the above, the circuit from the Schmitt circuit 51 to the addition/subtraction counter 55 forms the control circuit B of the tightening control device, and the lever interlocking switch 29 and the switching valve interlocking switch 45 each serve as the addition/subtraction counter of this control circuit B. 55. Note that 59 is a digital display device connected to the addition/subtraction counter 55 via a decoder 60, and visually displays the difference between the set count number of the Samir switch 65 and the detected cumulative count number. It's been like getting. Further, 61 indicates a test switch, and 62 indicates a test reset switch.
Note that the lever interlocking switch 29, the switching valve interlocking switch 45, and the photo interrupter 3 in the above
6 and 37 are connected to the control circuit B from the connector 32 shown in FIG.

Next, a tightening test for setting the set count number in the Samir switch 65 will be explained. First, the test switch 61 is switched to the test position, and the object to be fastened is tightened based on the operating sound and response during tightening. In this case, by switching the test switch 61 to the test position, the addition/subtraction counter 55 becomes up-counting, and performs up-counting when a count pulse is input. Therefore, at the end of tightening, the digital display device 59 displays the cumulative count of count pulses in the reaction rotation direction from the start of tightening to the end of tightening. Next, the actual tightening torque of the fastened object tightened as described above is measured, and this is done by measuring the loosening torque of the fastened object with a torque wrench or the like. This loosening torque varies depending on the fastener, but in most cases it is around 80% of the tightening torque, so in practical terms it is possible to estimate the tightening torque from the measurement results of the loosening torque. . If the measured torque value is appropriate, the test ends. However, if the tightening torque is insufficient, operate the test reset switch 62 and perform the test again to ensure proper tightening. Repeat this test until torque is achieved. Then, as a result of the above test, when the tightening torque value is appropriate, the numerical value on the digital display device 59 is read, and this numerical value is set as the set count number by turning the setting dial of the Samir switch 65, and the test work is completed. do. Then, the test switch 61 is released. As a result, the Samir switch 65 is set to the optimum value of the cumulative count in the reaction rotation direction when the tightening torque reaches its optimum value.

Next, a case will be described in which a bolt tightening operation is performed using the impact wrench A as described above. First, by operating the operation knob 22, the air motor 6 is operated to start tightening, and the tightening control device is also activated by a signal from the first reed switch 29. The reaction rotation angle of the output shaft 9 of the air motor 6 during tightening is detected as a count pulse, and the detected count pulse is integrated in the addition/subtraction counter 55. The digital display device 59 displays the count number set in the Samir switch 65 at the start of tightening, but after the start of tightening, this display number changes according to the number of count pulses accumulated as described above. It is subtracted. When the number displayed on the digital display device 59 becomes zero, that is, when the cumulative number of count pulses reaches the set count number, a command signal is issued from the addition/subtraction counter 55,
The air supply cutoff mechanism 58 such as a solenoid valve is operated to cut off the air, and the impact wrench is stopped to complete the tightening work. Then, when the tightening work is completed, the operation knob 22 is returned to its original position, and at the same time, the set count number is automatically set again.
Preparation for the next tightening operation similar to the above is completed. In this way, according to the impact wrench A, the standard tightening torque value can be set according to the various conditions of the member to be tightened, bolts, screw holes, etc., so extremely accurate tightening can be achieved. It becomes possible to perform torque control.

On the other hand, when loosening a bolt due to improper tightening, rotate the forward/reverse switching lever 33 from the state shown in FIG. 4 to the state shown in FIG. 5 to change the direction of rotation of the air motor 6. Switch from forward direction to reverse direction. Then, along with the operation of the forward/reverse switching lever 33, the second reed switch 45
detects the proximity of the second magnet 44 and issues a command signal to the addition/subtraction counter 55 to stop counting. As a result, the addition/subtraction counter 55 no longer issues a command signal to the air supply cutoff mechanism 58, and the control function of the tightening control device is canceled. In other words, simply by operating the forward/reverse switching lever 33, the rotational direction of the air motor 6 can be switched and the control function of the tightening control device can be canceled at the same time. After loosening the bolt, move the forward/reverse switching lever 33 again to the fifth position.
When the air motor 6 is rotated from the state shown in the diagram to the state shown in FIG. the result,
The tightening control device will regain control function.

As described above, in the impact wrench tightening control device of the above embodiment, the rotational direction of the air motor 6 of the impact wrench A can be switched and the control function can be canceled or restored by a one-touch operation. Furthermore, since non-contact switches are used for the lever interlocking switch 29 and the changeover valve interlocking switch 45, the life of each switch 29, 45 can be maintained for a long time.

In the above embodiment, the second reed switch 45 is connected to the addition/subtraction counter 5 of the control circuit B.
Although the explanation has been given using the circuit connected to control circuit B as an example, in short, when the rotation direction of the air motor 6 is switched from the forward rotation direction to the reverse rotation direction, the control circuit B
Any circuit may be used as long as it can stop the output of the command signal from the controller. In addition to the configuration of the above embodiment, an NG display means may be provided to detect and warn insufficient tightening to the set value, and in this case, the second
If the reed switch 45 is used as an NG reset switch, there is no need to increase the number of operations.

(Effects of the Invention) The tightening control device for an impact wrench of the present invention includes a detection means for detecting a torque characteristic value of the tightening torque by the tightening torque generation mechanism, and a torque characteristic value detected by the detection means. a control means that issues a command signal when the control means reaches a reference value; an air supply cutoff mechanism that closes the air supply passage in response to a command signal from the control means; and a release means that stops outputting the command signal from the control means. Since the release means is interlockably incorporated into the switching valve mechanism of the impact wrench, the rotational direction of the air motor can be switched by simply operating the switching valve mechanism, that is, by a one-touch operation. It is possible to cancel the control function at the same time. Therefore, the work efficiency can be improved more than the conventional impact wrench tightening control device.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, in which Fig. 1 is a longitudinal cross-sectional view of an impact wrench, and Fig. 2 is a -
3 is a front view of the impact wrench shown in FIG. 1, FIGS. 4 and 5 are front views explaining the operation of the switching valve mechanism, FIG. 6 is a wiring diagram of the impact wrench, and FIG. The figure is a block diagram of the tightening control device. A...Impact wrench, B...Control circuit, 6...Air motor, 7...Tightening torque generation mechanism, 8...Reaction rotation amount detection mechanism, 21...Forward/reverse switching valve mechanism, 45...Second Reed switch, 5
8...Air supply cutoff mechanism.

Claims (1)

[Claims] 1. An impact wrench comprising an air motor, a tightening torque generating mechanism driven by the air motor, and a switching valve mechanism interposed in an air supply passage to switch the rotational direction of the air motor. a detection means for detecting a torque characteristic value of the tightening torque by the tightening torque generating mechanism; a control means for issuing a command signal when the torque characteristic value detected by the detection means reaches a reference value; and the control means. an air supply cutoff mechanism that closes the air supply passage in response to a command signal from the control means; and a release means that stops the output of the command signal from the control means, and the release means can be interlocked with a switching valve mechanism of the impact wrench. A tightening control device for an impact wrench, characterized in that it is incorporated in.