JPS62251086A - Clamping controller for impact 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 (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 bolts, because it generates little reaction during tightening work.

By the way, when performing a tightening operation on an object to be fastened using this impact 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 impact wrench when a predetermined tightening torque is reached. 59-163467) is mentioned. This device detects the amount of reaction rotation of the output shaft of the air motor after impact using a reaction rotation amount detection mechanism, integrates and counts the detected amount of reaction rotation using a counter, and counts the detected amount of reaction rotation when it reaches a predetermined count value. This device sends a command signal to the air supply cutoff mechanism to close the air supply passage, and this device allows the tightening torque of objects to be fastened to be controlled automatically and accurately. It becomes possible.

(Problems to be Solved by the Invention) However, in the above control device, the following problems may occur. In other words, the predetermined count value, that is, the reference value input into the counter, needs to be set in advance according to the object to be fastened, but for example, when tightening several types of bolts with different diameters, the reference value of each bolt Since the value differs depending on the diameter, it is necessary to set the standard value for each type of bolt each time you tighten it, which causes problems such as time-consuming work and reduced work efficiency. There is. Furthermore, if the reference value is set every time the type of bolt is changed, there is a possibility that a setting error will occur, and therefore it is difficult to perform accurate torque management.

This invention was made in order to solve the above-mentioned conventional drawbacks, and its purpose is to provide an impact wrench that can tighten objects with high precision without requiring any trouble even when tightening different types of objects. An object of the present invention is to provide a tightening control device.

(Means for Solving the Problems) Therefore, in the impact wrench tightening control device of the present invention, in an impact wrench having an air motor and a tightening torque generation mechanism driven by the air motor, A detection means for detecting the torque characteristic value of the tightening torque by the 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 a command from the control means. an air supply cutoff mechanism that closes the air supply passage in response to a signal, and further includes a plurality of reference value setting means for setting the above reference values in advance according to various types of objects to be fastened, and one of the plurality of reference values. and set value switching means for selecting one of the reference values and inputting it to the control means.

(Function) In the impact wrench tightening control device described above,
The operator can immediately start tightening work simply by selecting the reference value corresponding to the object to be fastened using the set value switching means, and therefore the standard value can be changed every time a different type of object is tightened. There is no need to set the value again.

(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. 3 and 4, 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 shaft 9 of the air motor 6 by a spline, a hammer 12 that is rotationally driven by the cam 11, and supports this hammer 12 and rotates together with the hammer 12. an anvil 14 that receives a blow from the hammer 12; and a main shaft 15 that is fixed to the anvil 14 and is driven to rotate together with the anvil 14 by the blow of the hammer 12.
The tip of the main shaft 15 is led out beyond the front end of the front casing 4, and a tightening socket (not shown) can be removably attached thereto. . The air that operates the air motor 6 passes through an air supply passage 18 in the grip part 1 from an air supply pipe connection port 17 attached to the lower end of the grip part 1, and passes through an air supply valve mechanism 19 for forward/reverse switching and flow rate adjustment. The air is supplied to the air motor 6 via the valve mechanism 21, and the exhaust gas from the air motor 6 is discharged to the outside through an appropriate route. The air supply valve mechanism 19
The operation knob 22 is protruded in front of the grip part 1, and the valve element 2 is attached to the inner tip of the valve stem 23 that is directly connected to the operation knob 22.
4, and a sleeve-shaped valve body 25 fitted into the grip part 1.
The inner end hole edge of the valve seat 26 is used as the valve seat 26, and the operation knob 2
2, the valve element part 24 is pulled away from the valve seat 26, passes through the gap formed in this part and the inside of the valve element 25, passes through the through hole 27 bored in the valve element 25, and passes through the air motor 6 direction. It is possible to supply air to the room. Further, a magnet 28 is attached to the back side of the operation knob 22, and a reed switch 29 is attached to the front part of the grip part 1.
2 to start supplying air to the air motor 6, the reed switch 29 detects the proximity of the magnet 28 and can activate a tightening control device to be described later. Therefore, the wire connections 31, 31 of this reed switch 29 are led out via the connector 32. Note that 33 is a forward/reverse switching lever, and 34 is a flow rate adjustment knob.

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
A large number of slits 3B are bored along the circumferential direction of the air motor 6, and a bolt 42 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. Each photointerrupter 36, 37 includes a pair of light emitting diodes and a photointerrupter disposed opposite to each other via the rotating disk 35.
) transistor, and the number of slits 38 passing between them, that is, the rotating disk 35 and the output shaft 9.
The number of signals corresponding to the rotation angle of is generated. Since both the photo ink converters 36 and 37 are arranged out of phase, the signal from one photo ink converter 36 and the signal from the other photo ink converter 37 have a phase difference. The direction of rotation of the rotating disk 35 can be detected by determining the level of the other signal at the pulse edge of one signal. Therefore, by using the above rotary encoder, it is possible to detect 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 the collision after the hammer 12 collides with the anvil 14. .

A control device B that controls the tightening torque using the reaction rotation amount detection mechanism 8 will be explained based on FIGS. 1 and 2. In the figure, the rotating disk 35 and photointerrupters 36 and 37 are as described above, but the output from the photointerrupters 36 and 37 is first sent to a Schmitt circuit 51 and subjected to waveform shaping. The count pulse output from the Schmitt circuit 51 is then sent to the gate 52.
Furthermore, the direction pulse is sent to the gate 52 via the rotation direction changeover switch 53, which direction is the tightening rotation direction and which direction is the reaction rotation direction. This is the part where you decide. As mentioned above, the direction of rotation of the air motor 6 can be changed by operating the forward/reverse switching lever 33.
1, the rotation direction changeover switch 53 may be configured to interlock the changeover lever 33 or the forward/reverse changeover valve mechanism 21. As a result of the above, only the count pulse in the reaction rotation direction is output from the gate 52, but this output is passed through the multiplier circuit 54 to the addition/subtraction counter 5 in order to increase the resolution.
Sent to 5.

The addition/subtraction counter 55 integrates and counts these count pulses, and when this count reaches a preset count number set in the Samir switch 65, 66, 67, it issues a command signal and activates the relay 57. let me,
The air supply cutoff mechanism 58 such as a solenoid valve is operated to close the air supply passage, and the operation of the air motor 6 is stopped to complete the tightening work. In addition, in the above, Schmitt circuit 5
The circuit from 1 to relay 57 forms control circuit C of control device B, as shown in FIG.
These may be arranged separately from the impact wrench A main body, or may be built into the impact wrench A main body.

By the way, in the above control device, a Samir switch (digital switch) is used to set a predetermined count number.
A plurality of (three in the case of the figure) are provided, and any one of the preset count numbers set in these Samir switches 65, 66, and 67 is applied to the addition/subtraction counter 55.
has been entered. That is, the Samir switch 6
5,66,67, predetermined count numbers are set in advance according to various types of objects to be fastened, and among these, the set count number corresponding to the object to be fastened is selected via the set value changeover switch 68. It is selected by the operator and input into the addition/subtraction counter 55. Furthermore, 59
is a digital display device connected to the addition/subtraction counter 55 via the decoder 60, and visually displays the difference between the set count number of the Samir switch 65, 66 or 67 and the detected cumulative count number. It's been like getting. Further, 61 indicates a test switch, 62 a test reset switch, and 29 the above-mentioned lever interlock switch.

Next, a tightening test for setting the set count number for each Samir switch 65, 67, and 67 will be described. In this case, for example, the object to be fastened has a diameter of 8 m, 1 (hm,
In the case of 14 types of bolts, perform the following test work on each of the 65.
The set count number is set to 66.67. 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 counts up, and counts up when a count pulse is input. Therefore, when the tightening is finished, the digital display device 5
9, the cumulative count of count pulses in the reaction rotation direction from the start of tightening to the end of tightening is displayed.

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 using a torque wrench or the like. This loosening torque varies depending on the fastener, but in most cases it is about 80% of the tightening torque, so in practice 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, but if the tightening torque is too high or too low, 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, read the numerical value on the digital display device 59 when the tightening torque value is appropriate, and set this numerical value to any of the Samir switches 65, 66, or 67 by turning the setting dial. The test operation is completed and the test switch 61 is released. By performing the above test work on various bolts, the optimum value of the cumulative count in the direction of reaction rotation is set for each Samir switch 65, 66, 67 when the tightening torque reaches its optimum value. That will happen.

Next, a case will be described in which the impact wrench A as described above is used to tighten, for example, three types of bolts having different diameters. First, the operator operates the set value changeover switch 68 to select the corresponding set count number based on the diameter of the bolt to be tightened. As a result, the addition/subtraction counter 55 has the Samir switch 6
From 5.66 or 67, the optimal setting count number for the bolt will be input. Therefore, when the worker next operates the operation knob 22, the air motor 6 is activated.
Start tightening the bolt. At the same time, the control device is also activated by a signal from the 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 shows a Samir switch 65, 66 or 67 at the start of tightening.
The set count number is displayed, but after the start of tightening, this display number is subtracted according to the number of count pulses accumulated as described above.

When the accumulated number of count pulses reaches the set count number and the number displayed on the digital display device 59 becomes zero, a command signal is issued from the addition/subtraction counter 55, and an air supply cutoff mechanism 58 such as a solenoid valve is activated to shut off the air. cut off the
Stop the impact wrench and complete the tightening work. Then, when the tightening work is completed, the trigger is returned, and at the same time, the set count number is automatically set again, and preparation for the next tightening work similar to the above is completed. If the diameter of the bolt to be tightened next is different from the diameter of the bolt tightened first, the operator must
By operating the switch 8 and selecting the set count number corresponding to the bolt in question, it becomes possible to immediately start the bolt tightening work similar to that described above. In this way, according to the above-mentioned impact wrench A, it is possible to tighten different types of objects to be fastened with one impact wrench A without any trouble, and there is no need to set the reference value each time. , it is possible to prevent the occurrence of setting errors and to perform accurate torque management.

(Effects of the Invention) The impact wrench tightening control device of the present invention includes a plurality of reference value setting means for setting reference values in advance according to various types of objects to be fastened, and a plurality of reference value setting means for setting reference values in advance according to various types of objects to be fastened; Since it is equipped with a set value switching means for selecting the reference value and inputting it to the control means, even when tightening different types of objects, the operator can select the reference value corresponding to the object to be fastened. By selecting through the set value switching means, the tightening work can be started immediately.

Therefore, different types of objects to be fastened can be tightened with one impact wrench without any trouble, thereby making it possible to improve work efficiency. Moreover, since there is no need to set the reference value by changing the object to be fastened, setting errors do not occur, and as a result, it is possible to manage the tightening torque with high precision.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is an overall circuit diagram of the impact wrench tightening control device of the invention, Fig. 2 is a block diagram thereof, and Fig. 3 is a longitudinal sectional front view of the impact wrench.
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3. A... Impact wrench, B... Control device, 6...
・Air motor, 7... Tightening torque generation mechanism, 8...
・Reaction rotation amount detection mechanism, 55... addition/subtraction counter, 5
8... Air supply cutoff mechanism, 65.66.67... Samir switch, 68... Switch box for switching set value.

Claims (1)

[Claims] 1. In an impact wrench having an air motor and a tightening torque generating mechanism driven by the air motor, a detecting means for detecting a torque characteristic value of the tightening torque by the tightening torque generating mechanism; It has a control means that issues a command signal when the detected torque characteristic value reaches a reference value, and an air supply cutoff mechanism that closes the air supply passage in response to the command signal from the control means, and further includes a control means that issues a command signal when the detected torque characteristic value reaches a reference value. a plurality of reference value setting means for setting the reference values according to various types of objects to be fastened; and a set value switching means for selecting one of the plurality of reference values and inputting the selected reference value to the control means. A tightening control device for an impact wrench, comprising: