JP3076834B2 - Automatic shut-off device for hydraulic pulse wrench - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic shut-off mechanism for controlling the torque of a spindle in a torque wrench.

[0002]

2. Description of the Related Art A torque wrench employing an air motor as a power source has a shut-off function of stopping rotation of a rotor when bolts, nuts and the like are seated with a predetermined torque. Conventionally, an auto-shutoff device for exerting this function conventionally detects stop or reversal of the rotor by an inertial body connected to the rotor, opens the air supply valve by the movement of the inertia body, and supplies air to the air timer, The air supply to the air motor is shut off for a certain period of time after sitting.

According to Japanese Utility Model Laid-Open Publication No. 3-40076, the rotational output of an air motor is intermittently transmitted to a main shaft.
In a torque wrench having a pulse generating mechanism for generating a hydraulic pulse each time a rotational force is applied to the main shaft, the hydraulic pressure on the high pressure generation side of the mechanism is applied to a relief valve, and the hydraulic pressure is set under the spring pressure of the relief valve. An automatic shut-off device is known in which a relief valve is opened when a set pressure value exceeds a set pressure, and an on-off valve is opened by the oil pressure at that time to stop the rotation of an air motor.

[0004]

In the above two prior arts, in the former, although a certain degree of torque accuracy can be obtained, actually, the generated torque is monitored and the automatic shut-off device is operated by the generated torque. Therefore, there is a problem that the torque accuracy is easily influenced by the performance and working conditions of the torque wrench itself.

[0005] The latter has a drawback that the hydraulic pressure on the high pressure side is often not sufficiently transmitted as the tightening force of the bolts and nuts because the hydraulic pressure pulse is generated only for a very short time. Also, if the oil pressure on the high pressure generation side becomes higher than the spring pressure of the relief valve, the air motor stops.Therefore, only the lower limit of the generated torque is managed. There was a problem of instability.

The present invention has been made in view of the above-mentioned drawbacks and problems, and detects a hydraulic pressure at the time of pulse generation, which is a source of torque generated by a torque wrench, and obtains a more accurate torque based on the data. An object of the present invention is to provide an automatic shutoff device for a hydraulic pulse wrench capable of performing management.

[0007]

An automatic shut-off device for a hydraulic pulse wrench according to claim 1 comprises: a fluid pressure motor;
A fluid pressure circuit for controlling the fluid pressure motor, a pulse generation mechanism for intermittently transmitting the rotation output of the fluid pressure motor to the main shaft with a generated hydraulic pulse and applying a rotational force to the main shaft, and a pulse generation mechanism in a hydraulic pulse reading means occurs, even the order for converting the result into an electric signal by comparing a hydraulic pulse setting pressure read by the reading means
It is possible to set the lower limit and upper limit of the set pressure.
The hydraulic pressure pulse has exceeded the lower limit of the set pressure by the set number of times.
Counting means for outputting a signal when
NG signal is output when the pressure pulse exceeds the set pressure upper limit.
Electrical control means for the force, is characterized in that it comprises a shut-off means for stopping the supply of fluid to the fluid pressure motor through an output from the upper Symbol electrical control means.

[0008]

[0009]

According to a second aspect of the present invention, in the automatic shut-off device for a hydraulic pulse wrench, the reading unit is a pressure sensor that detects a fluid pressure transmitted by a thrust of the hydraulic pulse.

According to a third aspect of the present invention, there is provided an automatic shut-off device for a hydraulic pulse wrench, wherein the reading unit is a load cell that generates a compressive strain by a fluid pressure transmitted by a thrust of a hydraulic pulse.

According to a fourth aspect of the present invention, there is provided an automatic shut-off device for a hydraulic pulse wrench, wherein a power source of the electric control means is a battery built in a housing.

[0013]

According to the automatic shut-off device of the hydraulic pulse wrench of the first aspect, the hydraulic pulse corresponding to the rotational force of the spindle read by the reading means is directly compared with the set pressure by the electric control means, and the hydraulic pulse is When the pressure exceeds the set pressure, the supply of the fluid to the hydraulic motor is stopped by the shut-off means according to the output signal of the electric control means, and the rotation of the hydraulic motor stops. At this time, the oil
According to the auto shut-off device of the pressure type pulse wrench,
Tightening force is sufficiently transmitted from the main shaft to bolts and nuts.
Thus, the hydraulic pressure exceeding the lower limit of the pressure set by the electric control means
The number of occurrences of the luce is monitored. In addition, bolts and nuts
Due to some situation other than the tightening force transmitted to the
The value of the hydraulic pulse has exceeded the upper limit of the set value and has increased.
In such cases, the effects of the situation can be eliminated.
Noh.

[0014]

[0015]

According to the automatic shut-off device of the hydraulic pulse wrench of the second aspect , the reading means can be configured at low cost.

According to the automatic shut-off device of the hydraulic pulse wrench of the third aspect , handling of the reading means is easy.

According to the automatic shut-off device of the hydraulic pulse wrench of the fourth aspect , since the battery is incorporated in the housing, it is not necessary to draw out the electric wiring for supplying electricity to the electric control circuit from the housing.

[0019]

FIG. 1 is a block diagram of an automatic shut-off device according to an embodiment of the present invention. FIGS. 2, 3 and 4 show different examples of the electric control circuit (electric control means) used in the automatic shut-off device.

In FIG. 1, reference numeral 1 denotes an air motor whose rotation direction is reversed depending on the direction of air flow. An air circuit 2 for controlling the air motor 1 includes an air source 21.
, An air supply valve 22, a rotation direction control valve 23, and air passages 24a to 24e connecting them. The air passages 24d, 24e are connected to the two air supply / discharge ports 11, 11 of the air motor 1. A muffler 25 is connected to the air passage 24f. Reference numeral 3 denotes a pulse generating mechanism. The pulse generating mechanism 3 itself is known from Japanese Utility Model Laid-Open Publication No. 3-40076 described above, and the detailed description thereof will be omitted. The pulse generating mechanism 3 intermittently transmits the rotational output of the air motor 1 to the main shaft 4 and generates a hydraulic pulse corresponding to the rotational force each time the rotational force is applied to the main shaft 4. And the hydraulic pulse transmission chamber 3
The piston 33 having a small diameter is provided at the axial center position of the upper lid 32 forming the hydraulic pressure pulse generating chamber 31.
Means the hydraulic cylinder 34 on the opposite side of the air motor 1
Pistons 35 are arranged, and both pistons 3
The transmission rods 3 and 35 are connected by a transmission rod 36 disposed through the rotation center of the air motor 1. In the hydraulic chamber 37 of the hydraulic cylinder 34, a pressure sensor 5, which is an example of a means for reading a hydraulic pulse generated in the high-pressure chamber, is provided. The hydraulic pulse read by the pressure sensor 5 is processed by the electric control circuit 6. As a power supply of the electric control circuit 6, a battery 61 built in the housing 10 is used. Reference numeral 7 denotes a switching valve, which is a two-position solenoid valve provided with a solenoid 71 operated by an output signal from the electric control circuit 6. Reference numeral 8 denotes a stop differential pressure valve, and reference numeral 9 denotes a stop switching valve. These three valves 7, 8, and 9 constitute shut-off means. That is, the stop switching valve 8 is interposed between the air passages 24c and 24d, and is configured such that the air pressure in the air passage 24c acts on both ends. Are connected via an air passage 81. 8
Reference numeral 2 denotes an exhaust port connected to the stop switching valve 9. One end of the stop switching valve 9 is connected to the air passage 2 through the switching valve 7.
4d or connected to the check valve 72. Further, the electric control circuit 6 and the battery 61 are connected via a pressure switch 62. The pressure switch 62 has a function of maintaining an energized state when the air passage 24d is at a high pressure and interrupting the energization when the air passage 24d is at a low pressure.

The above-described air supply valve 22, rotation direction control valve 23,
Each of the switching valve 7, the stop differential pressure valve 8, and the stop switching valve 9
It is constituted by a two-position switching valve. All of the components described above are housed in the housing 10 of the torque wrench except for the air source 21 and a part of the air passage 24a.

The electric control circuit 6 shown in FIG.
Set value (pressure value) set by 3 and pressure sensor 5
The comparator 65 compares the hydraulic pulse detected by the above with the value amplified by the amplifier 64, and sets the lower limit of the hydraulic pressure (set by the setting switch 63) to the set number of times (set by the setting switch 63). And a counting means 66 for outputting a signal for switching the communication state of the switching valve 7 when the number of times continuously exceeds the threshold value.

The electric control circuit 6 shown in FIG.
The data holding unit 67 and the A / D converter 6 of the value set in Step 3
8, a comparison operation unit 65 and the like.

The electric control circuit 6 of FIG. 4 is obtained by replacing the comparison operation section 65 of FIG.

Next, the operation of the automatic shut-off device provided with the electric control circuit 6 shown in FIG. 2 will be described.

When the air supply valve 22, the rotation direction control valve 23, the switching valve 7, the stop differential pressure valve 8, and the stop switching valve 9 are set at the positions shown in FIG. doing. Therefore, no torque is generated.

When the air supply valve 22 is switched from this state, air is supplied from the air source 21 to the air passage 24a, the air supply valve 22, the air passage 24b, the rotation direction control valve 23, the air passage 24c, the stop differential pressure valve 8 Is supplied to the air motor 1 through the air passage 24d in this order. The air that has flowed out of the air motor 1 is discharged through the air passage 24e, the rotation direction control valve 23, the air passage 24f, and the muffler 25 in this order. In such an operation state, for example, the air motor 1 rotates forward, and the rotation output of the air motor 1 is intermittently transmitted to the main shaft 4 by the pulse generation mechanism 3. The hydraulic pulse generated in the high pressure chamber of the pulse generation mechanism 3 pushes down the piston 33 in the hydraulic pulse transmission chamber 31. As a result, the piston 35 is pushed down via the transmission rod 36, so that the pressure of the hydraulic cylinder 34 at that time, that is, the above-mentioned hydraulic pulse is read by the pressure sensor 5, and the read signal is input to the electric control circuit 6.

In the electric control circuit 6, the setting switch 63 sets the lower limit and upper limit of the set value for pressure and the set value for the number of times.

Therefore, the comparator 65 compares the set value of the pressure with the oil pressure pulse read by the pressure sensor 5. The above-mentioned operation state is maintained while the hydraulic pressure pulse read by the pressure sensor 5 is smaller than the set lower limit value. If the oil pressure pulse value read by the pressure sensor 5 becomes larger than the set upper limit, the operation at that time is determined to be NG, the operation is immediately stopped, and a message to that effect is displayed. Then, when the number of consecutive hydraulic pulses read by the pressure sensor 5 that is larger than the set lower limit becomes larger than the set number, this is detected by the counting means 66 and output. Then, the solenoid 71 is excited to switch the switching valve 7, thereby switching the stop switching valve 9, so that one end of the stop differential pressure valve 8 communicates with the exhaust port 82. As a result, the stop differential pressure valve 8 is switched to stop the air supply to the air motor 1 (auto shut-off function). At the same time, the pressure in the air passage 24d becomes low, the pressure switch 62 is turned off, and the electricity from the battery 61 is turned off. The power supply to the control circuit 6 is cut off.

According to such an automatic shut-off function, even after the hydraulic pulse reaches a predetermined value, the hydraulic pulse of that value is applied to the bolt or the nut a predetermined number of times, so that the bolt or the nut can be securely tightened. Become like If a hydraulic pulse exceeding the set upper limit is generated, it is determined that an accurate operation is not being performed, and the operation is stopped and a message to that effect is displayed, so that the tightening reliability for bolts and nuts is improved. Further, since the battery 61 housed in the housing 10 is used as a power source of the electric control circuit 6, it is possible to prevent the electric wiring from hindering the workability and breaking the electric wiring.

In the above embodiment, the pressure sensor 5 for detecting the hydraulic pressure transmitted by the thrust of the hydraulic pulse is used as the reading means.
Instead, a load cell that generates a compression strain by the hydraulic pressure transmitted by the thrust of the hydraulic pulse may be used. The load cell is more advantageous in terms of mounting structure and handling, and the pressure sensor 5 is more advantageous in terms of price.

[0032]

According to the automatic shut-off device of the hydraulic pulse wrench of the first aspect, the hydraulic pressure at the time of pulse generation, which is the source of the torque generated by the hydraulic pulse wrench, is detected, and the data is used as the basis. Since torque control can be performed, more accurate torque management can be performed . Also, hydraulic pal
Over several times after the pressure reaches the specified pressure value
Can be applied to bolts and nuts
As a result, more secure tightening can be performed. In addition,
In any situation other than the tightening force transmitted to the
To prevent bolts and nuts from tightening.
It becomes possible to transmit the urging force.

[0033]

[0034]

Further, according to the automatic shut-off device of the hydraulic pulse wrench of the second aspect , the reading means can be configured at low cost, and according to the automatic shut-off device of the hydraulic pulse wrench of the third aspect , the reading is performed. Handling of the means is facilitated.

According to the automatic shut-off device for the hydraulic pulse wrench of the fourth aspect , there is an effect that it is possible to prevent a situation such as disconnection of electric wiring for supplying electricity to the electric control circuit.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an automatic shut-off device according to an embodiment of the present invention.

FIG. 2 is a block diagram of an electric control circuit used in the automatic shut-off device.

FIG. 3 is a block diagram of another electric control circuit used in the automatic shut-off device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air motor (fluid pressure motor) 2 Air circuit (fluid pressure circuit) 3 Pulse generation mechanism 4 Main shaft 5 Pressure sensor (hydraulic pulse reading means) 6 Electric control circuit (electric control means) 7 Switching valve 8 Stop differential pressure valve ( (Shutoff means) 9 Switching valve for stop (Shutoff means) 61 Battery 66 Counting means

Continuation of front page (56) References JP-A-1-246081 (JP, A) JP-A-3-251375 (JP, A) JP-A-59-53168 (JP, A) JP-A-62-259783 (JP, A) , A) Actual opening 58-1576 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B25B 23/145 B25B 21/02

Claims (4)

(57) [Claims] 1. A fluid pressure motor, a fluid pressure circuit for controlling the fluid pressure motor, and an intermittent transmission of a rotation output of the fluid pressure motor to a main shaft by a generated hydraulic pulse, thereby transmitting a rotational force to the main shaft. a pulse generating mechanism for applying a hydraulic pulse reading means generated by the pulse generating mechanism, der intended to be the hydraulic pressure pulse compared to the set pressure converts the result into an electrical signal read by the reading means
Therefore, the lower limit and upper limit of the set pressure can be set,
When the pressure pulse exceeds the lower limit of the set pressure by the set number of times
A counting means for outputting a signal, and
And <br/> electric control means for outputting an NG signal when the scan exceeds the upper limit of the set pressure, the shut-off by the output from the upper Symbol electrical control means stops the supply of fluid to the fluid pressure motor And an auto-shutoff device for a hydraulic pulse wrench. 2. The automatic shut-off device for a hydraulic pulse wrench according to claim 1, wherein said reading means is a pressure sensor for detecting a fluid pressure transmitted by a thrust of a hydraulic pulse. 3. An automatic shut-off device for a hydraulic pulse wrench according to claim 1, wherein said reading means is a load cell which generates a compressive strain by a fluid pressure transmitted by a thrust of a hydraulic pulse. 4. The automatic shut-off device for a hydraulic pulse wrench according to claim 1, wherein the power source of the electric control means is a battery built in the housing.