JPS63245373A - Torque wrench - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) This invention relates to a torque wrench.

(Conventional technology) Torque wrenches have little recoil during tightening work, so
This tool is relatively frequently used as a tightening tool for various fastened objects such as bolts and nuts. By the way, when tightening objects to be fastened using this torque wrench,
It is necessary to stop the tightening operation when the tightening torque acting on the object to be fastened reaches a predetermined value. In other words, if you stop tightening while the tightening torque acting on the bolt or nut is small, sufficient tightening force will not be obtained, and if you continue tightening until a high torque is reached, the bolt will This is because it may be damaged.

Therefore, various devices have been developed and put into practical use that stop the operation of the torque wrench when a predetermined tightening torque is reached.
An example of this is the impact wrench tightening control device described in Japanese Patent Application No. 61-196541. this is,
The reaction rotation amount detection mechanism placed inside the impact wrench casing detects the reaction rotation amount of the air motor's output shaft after impact, and the detected reaction rotation amount is detected by a counter in a tightening control device separate from the impact wrench. addition,
When the count reaches a predetermined value, a command signal is sent to the air supply cutoff mechanism to close the air supply passage.This device allows you to tighten objects with an impact wrench. It becomes possible to control torque accurately and automatically.

(Problems to be Solved by the Invention) By the way, when using the above-mentioned tightening control device to tighten objects with an impact wrench, the worker always controls the tightening control device by himself or herself at the work site. The impact wrench must be placed next to the tool, so when moving to the next work site after completing fastening work at a particular work site, the impact wrench must be carried along with the tightening control device. There is a problem in that it is very inconvenient to carry them, which hinders the handling of impact wrenches.

This invention was made to eliminate the above-mentioned drawbacks, and its purpose is to accurately control the tightening torque of objects to be fastened.
To provide a torque wrench that can be automatically controlled and is convenient to handle at a work site.

(Means for Solving the Problems) Therefore, in the torque wrench tightening control device of the present invention, an air motor and a tightening torque generation mechanism driven by the air motor are disposed in a casing including a grip part. In the torque wrench, the casing further includes a control means for issuing a command signal when the torque characteristic value of the tightening torque by the tightening torque generating mechanism reaches a reference value, and a control means for issuing a command signal from the control means to control the air motor. An air supply cutoff mechanism is installed to cut off the air supply to.

(Function) In the torque wrench with the above configuration, when the tightening torque characteristic value by the tightening torque generating mechanism reaches the reference value, the control means issues a command signal, and the air supply cutoff mechanism starts the air motor according to the above command signal. Since the air supply is cut off, it is possible to accurately and automatically control the tightening torque of the object to be fastened. Moreover, since these detection means, control means, and air supply cutoff means are arranged within the casing of the torque wrench, handling of the torque wrench at a work site becomes very convenient.

(Example) Next, a specific example of the torque wrench of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a longitudinal cross-sectional view of a device in which the present invention is applied to an impact wrench. In the figure, 2 is a casing, and this casing 2 includes a grip part 1 and an upper end of this grip part 1. an integrally connected central casing 3;
It has a front casing 4 that extends further forward from the front end of the central casing 3, and a rear casing 5 that covers the rear of the central casing 3. A solenoid pulp 48 is interposed as a shutoff mechanism, an air motor 6 is provided in the central casing 3, a tightening torque generating mechanism 7 is provided in the front casing 4, and a reaction rotation amount detection mechanism is provided in the rear casing 5. 8 are stored in each. The tightening torque generating mechanism 7 supports a cam 11 connected to the tip of the output shaft 9 of the air motor 6 by a spline, a hammer 12.12 rotationally driven by the cam 11, and the hammer 12.12. Hammer 12. Hammer frame that rotates with 12 (
The main shaft 15 is fixed to the anvil and rotated together with the anvil by the impact of the hammer 12.12. The tip of the main shaft 15 is guided outward beyond the front end of the front casing 4,
A tightening socket (not shown) is adapted to be removably attachable. The air that operates the air motor 6 is
From the air supply pipe connection port 17 attached to the lower end of the grip part 1, the air passes through the air supply passage 18 in the grip part 1, passes through the air supply valve mechanism 19, and passes through the forward/reverse switching valve mechanism 21 to the air motor 6. The exhaust from the air motor 6 is discharged to the outside through an exhaust passage 20 provided adjacent to the air supply passage 18. The air supply valve mechanism 19 has an operating knob 22 protruding in front of the grip portion 1, and a valve rod 2 directly connected to the operating knob 22, as shown in FIG.
A valve element 24 is formed at the inner tip of the valve element 3, and a seal ring 16 is disposed in a concave groove provided on the outer peripheral surface of the valve element 24.
A stepped portion for the seal ring 16 to come into contact with is provided around the inner circumferential surface of the bottomed cylindrical valve member 25 which is fitted into the grip part so as to surround the valve stem 23. 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 each time the operation knob 22 is pushed in, the seal ring 16 of the valve element 24 is pressed. It is pulled away 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 provided on the end surface of the valve element 24, and a first magnet 28 is attached to the end surface of the valve element 24.
5 has a hole 1 arranged corresponding to the first magnet 28 on the bottom surface thereof. A first reed switch (lever action switch) 29 consisting of
2 to start supplying air to the air motor 6, the first reed switch 29 is turned on in the vicinity of the first magnet 28, and a tightening control section 47, which will be described later, can be activated. There is. As shown in FIG. 1, the forward/reverse switching valve mechanism 21 provided in the air supply passage 18 causes a forward/reverse switching lever 33 to protrude in front of the grip portion 1, and a base portion of the lever 33 with a bottom. It is rotatably supported on the grip part 1 side via a cylindrical casing 34, and a valve part 43 for changing the direction of air supply to the air motor 6 is formed at the base of the lever 33.

At an eccentric position on the base end surface of the forward/reverse switching lever 33, a second f61 stone 44 has one end surface connected to the bottomed cylindrical casing 3.
The second magnet 44 is buried in a state facing the bottom surface side, and the second magnet 44 is buried in the bottom surface of the bottomed cylindrical casing 34.
A second reed switch (changeover valve interlocking switch) 45 consisting of a hole 16C0 is attached at a position corresponding to .

In this case, as shown in FIG. 4, the 217th switch 45 is arranged 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. 3, 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 fourth position. As shown in the figure, when an attempt is made to point to the reverse position, the proximity of the second magnet 44 is detected, which turns it into an ON state and allows the control function of the tightening control section 47, which will be described later, to be canceled. ing.

Next, the reaction rotation amount detection mechanism 8 disposed inside the rear casing 5 will be explained. It is of a rotary encoder type consisting of a pair of photointerrupters 36 and 37 arranged with a phase difference from each other. Rotating disk 35
Numerous slits are bored along the circumferential direction, and a nut 4 is inserted through a washer 41 into the free end of the lead-out shaft 39 fixed to the rear end of the output shaft 9 of the air motor 6.
It is fixed by 2. Each photo ink printer 36
．． 37 is composed of a pair of light emitting diodes and a phototransistor that are arranged opposite to each other with the rotating disk 35 in between. Generates a number of signals corresponding to the rotation angle. Since both photo ink printers 36 and 37 are arranged with a phase shift,
The signal from one photointerrupter 36 and the signal from the other photointerrupter 37 have a phase difference, and the direction of rotation of the rotating disk 35 can be determined by determining the level of the other signal at the pulse edge of one signal. It becomes possible to detect. Therefore, by using the rotary encoder described above, after the hammer 12 collides with the anvil, the air motor 6 is
Only the reaction rotation angle when the output shaft 9 returns in the opposite direction can be detected. In addition, each of the photo ink printers 36 mentioned above
．． The output of 37 is sent to a tightening control section 47, which will be described later.

Next, the tightening control section 47 as a control means will be explained. As shown in FIG. 5, a storage recess 51 is formed in the upper part of the central casing 3. Support portions 54, 54, and 54 are formed on the bottom and one side of the storage recess 51, respectively. A circuit board 53 is supported on these supports 54, 54, 54. This circuit board 53 is for mounting and supporting the tightening control section 47, and is entirely covered and reinforced with a resin mold such as epoxy. This circuit board 53 is connected to the support portion 54.5.
4.54, the storage recess 51 is filled with an elastic material 55 such as silicone rubber. That is, this prevents the circuit board 53 disposed in the storage recess 51 from being damaged due to vibrations generated during the fastening work of objects to be fastened. The storage recess 51 filled with an elastic material is the lid member 5
6 is blocked from above. Note that 57 is the circuit board 5
Hexadecimal DTP as a tightening torque setting section provided on 3.
This is a rotary code switch (hereinafter referred to as a rotary code switch), and an opening 58 is formed in the lid member 56 at a position facing the rotary code switch 57. The operator can operate the rotary code switch 57 through this opening 58 to set a set count corresponding to the tightening torque in a tightening torque setting circuit to be described later. Further, 65 is a wiring connected to the circuit board 53. A part of this wiring is connected to a connector 32 provided at the lower end of the grip part 1, and an AC adapter 49 for supplying power from the outside is connected to this connector 32 (see Fig. 1). .

FIG. 6 shows a functional block diagram of the tightening control section 47. In the figure, the rotating disk 35 and the photo interrupter 36, 37 are as described above, but the The electrical signal is first sent to the recoil counting circuit 59. In this recoil counting circuit 59, pulses (hereinafter referred to as count pulses) corresponding to the recoil angle generated by the electric signal are integrated and counted.

When this count pulse number reaches a set count number preset in the tightening torque setting circuit 60 constituted by the rotary code switch 57, a command signal is issued from the solenoid shutoff circuit 61. In response to this command signal, the solenoid valve 4 is activated, the air supply passage 18 is closed, the air supply to the air motor 6 is cut off, and the fastening work is completed. Note that when the count pulse number in the reaction counting circuit 60 reaches the set count number set in the tightening torque setting circuit 60, another command signal is sent from the solenoid shutoff circuit 61 to the tightening completion detection circuit 62. Emitted. This command signal activates the tightening completion detection circuit 62, which lights up the light emitting diode 63 to notify the operator of the completion of the tightening work. In the above, the counter reaction circuit 59 and the tightening torque setting circuit 60
, the solenoid shutoff circuit 61 and the tightening completion detection circuit 62 are formed on the circuit board 53 (the part surrounded by the dashed line in FIG. 6) and constitute the tightening control section 47. The continuous action switch 29 is connected to the reaction counting circuit 59, the solenoid shutoff circuit 16, and the tightening completion detection circuit 62, and when turned ON, these become activated. Further, the above-mentioned changeover valve interlocking switch 45 is connected to the solenoid shutoff circuit 61, and when turned ON, the solenoid shaft off circuit 61 is maintained in an inoperative state. Note that a power source 64 for power supply is connected to the circuit board 53. FIG. 7 shows a wiring diagram of the interior of the impact wrench (the area surrounded by the one-dot chain line) having the above structure. The tightening control section 47 includes a connector 32 for connecting a fart adapter 49 that supplies power to the cough tightening control section 47, a photo ink valve 36, 37, a solenoid valve 48, a lever interlock switch 29, and a changeover valve. The interlocking switches 45 will be connected to each other.

Next, a tightening test for setting an appropriate set count number in the tightening torque setting circuit 60 will be explained. First, by operating the rotary code switch 57, an appropriate set count number is set in the tightening torque setting circuit 60. Then, the object to be fastened is tightened according to the set count number, and the tightening torque of the tightened object is measured. If there is a difference between this measured torque value and the torque value actually required for tightening, the set count number that is adjusted based on the set count number set in the tightening torque setting circuit 60 as described above is applied to the rotary motor. The code switch 57 is operated to reset the setting, and this test is repeated until the set count number corresponding to the appropriate tightening torque is determined. As a result, the optimum value of the set count number when the tightening torque reaches the optimum value is set in the tightening torque setting circuit 60.

Next, a case will be described in which bolt tightening work is performed using the impact wrench as described above.

First, by operating the operation knob 22, the air motor 6 is
is activated to start tightening, and the tightening control section 47 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 reaction angle counting circuit 59. When the cumulative number of count pulses reaches the set count number set in the tightening torque setting circuit 60, a command signal is issued from the solenoid shutoff circuit 61, and the solenoid valve 48 is operated to shut off the air.
The operation of the impact wrench is stopped to complete the tightening work, and the light emitting diode 63 is turned on. When the tightening operation is completed, the operation knob 22 is returned to its original position, and at the same time, the set count is automatically set again, and preparation for the next tightening operation similar to the above is completed.

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. 3 to the state shown in FIG. 4 to change the rotation direction of the air motor 6 to the correct direction. The rotation direction is switched from the rotation direction to the 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 solenoid shutoff circuit 61. As a result, the solenoid shutoff circuit 61 will no longer issue a command signal to the solenoid valve 48, and the tightening torque control function by the control section 47 will be canceled.

After the bolt has been loosened, the forward/reverse switching lever 33 is again rotated from the state shown in FIG. 4 to the state shown in FIG. The switch 45 is turned off when the second magnet 44 is removed, and as a result, the tightening control section 47 recovers its control function.

In this way, in the above embodiment, the tightening control section 47 that issues a command signal based on the detection signal from the reaction rotation amount detection mechanism 8 and the solenoid valve 48 as the air supply cutoff mechanism are used.
Since it is arranged in the casing 2 of the impact wrench, it is possible to accurately and automatically control the tightening torque of the object to be fastened, and the handling of the impact wrench at the work site is very convenient. Furthermore, since the set count number, that is, the tightening torque can be set at hand by the operator, the effort required for the setting work is reduced.

In the above embodiment, an example in which the present invention is applied to an impact wrench has been described, but the present invention can also be applied to a torque wrench that is rotationally driven by another air motor. For example, in a pulse wrench that is driven by pressure oil, if a rotary encoder similar to the above embodiment is directly connected to the output shaft of the air motor, this will show periodic changes corresponding to changes in the rotational speed of the air motor. A pulsed input signal train is obtained. Since each impact with the pulse wrench causes a decrease in the rotational speed of the air motor, the timing of each impact can be detected by detecting the periodic change in the input pulse train as described above, and the signal change corresponding to this impact can be counted. So, the count value,
In other words, by configuring the control means to issue a command signal when the number of blows reaches a reference value, the tightening torque of the object to be fastened can be controlled in a pulse wrench, etc., in the same manner as in the above embodiment for the impact wrench. can be controlled automatically and accurately. Furthermore, by incorporating the control means into the device, the device can be constructed as a device that is convenient to handle at a work site.

(Effects of the Invention) As described above, in the torque wrench of the present invention, a command signal is provided in the casing of the torque wrench when the torque characteristic value of the tightening torque by the tightening torque generation mechanism reaches a reference value. The configuration includes a control means that generates a command signal, and an air supply cutoff mechanism that cuts off the air supply to the air motor in response to the command signal.
Automatic control is possible, and handling of the torque wrench at the work site is extremely convenient.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an impact wrench to which the present invention is applied, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Figs. 3 and 4 are front views, respectively, for explaining the operation of the switching valve mechanism. 5 is an enlarged sectional view of the tightening control section shown in FIG. 1, FIG. 6 is a block diagram of the tightening control section, and FIG. 7 is a wiring diagram inside the impact wrench. DESCRIPTION OF SYMBOLS 1... Gripping part, 2... Casing, 6... Air motor, 7... Tightening torque generation mechanism, 9... Tightening control part, 48... Air supply cutoff mechanism. Figure 3 Figure 4 Figure 5':) 4 ') 1 'D') ') L3 54 Figure 7

Claims (1)

[Claims] 1. In a torque wrench in which an air motor and a tightening torque generation mechanism driven by the air motor are disposed in a casing including a grip, the casing further includes a tightening torque generated by the tightening torque generation mechanism. A control means for issuing a command signal when a characteristic value reaches a reference value, and an air supply cutoff mechanism for cutting off air supply to the air motor in response to a command signal from the control means. Torque Wrench.