JPH0624714B2 - Impact wrench tightening control device - Google Patents

Description

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 tightening tool for various objects to be fastened, such as bolts and nuts, because there is little recoil during tightening work. By the way, in performing the tightening work of the fastened object with this impact wrench, it is necessary to stop the tightening work in a state where the fastening torque acting on the fastened object reaches a predetermined value. In other words, if the tightening work is stopped while the tightening torque acting on the bolts and nuts is small, sufficient tightening force cannot be obtained, and if the tightening work is performed until a high torque is reached, the bolts will not be tightened. This is because it may be damaged. Therefore, various devices for stopping the operation of the impact wrench when the predetermined tightening torque is reached have been developed and put into practical use. As an example of this, the applicant's earlier application (actual development 59 -163467) can be cited as a tightening control device for an impact wrench. This device detects the reaction rotation amount after the impact of the output shaft of the air motor by the reaction rotation amount detection mechanism, integrates and counts the detected reaction rotation amount by the counter, and when this reaches a predetermined count value. The air supply shutoff mechanism issues a command signal to close the air supply passage. According to this device, the tightening torque of the object to be fastened can be controlled accurately and automatically.

(Problems to be Solved by the Invention) However, the following problems may occur in the above control device. That is, the predetermined counter value, that is, the reference value, input to the counter needs to be set in advance according to the object to be fastened, but, for example, when tightening several bolts having different diameters, the reference value of each bolt is used. Since the value differs depending on the diameter, it is necessary to set a reference value according to the type each time the bolt of each type is tightened, which requires time and labor for the work, resulting in a decrease in work efficiency. There is. Further, if the reference value is set every time the type of bolt is changed, there is a possibility that a setting error may occur, and therefore it is difficult to perform accurate torque management. Therefore, a plurality of reference value setting means are provided, and reference values are set in advance for these various objects to be fastened, and when the tightening work of the objects to be fastened is handled, a switch or the like that requires switching is used. It is also possible to select the reference value to be used, but even in this case, it is necessary to perform the switching work of the above switches etc. each time when tightening different types of objects to be fastened, and it is necessary to replace the tightening socket. However, a significant improvement in work efficiency cannot be expected.

The present invention has been made in order to solve the above-mentioned conventional drawbacks, and an object thereof is to make it possible to accurately fasten objects to be fastened with different types without requiring any trouble. It is to provide a tightening control device for a wrench.

(Means for Solving Problems) Therefore, in the tightening control device for an impact wrench according to the present invention, an air motor and the air motor are provided for a plurality of impact wrenches arranged corresponding to various objects to be fastened. A tightening torque generating mechanism driven by a motor, a detecting means for detecting a torque characteristic value of the tightening torque by the tightening torque generating mechanism, and an air supply shutoff mechanism for closing the air supply passage by a command signal from the control means. While providing
In the control device to which the torque characteristic value detected by the detection means of each impact wrench is input, a plurality of reference value setting means for setting the reference value in advance for various fasteners, and the impact that has been operated. An operating wrench discriminating means for discriminating a wrench, a set value switching means for selecting a reference value corresponding to the operating impact wrench based on a signal from the operating wrench discriminating means, and the detected torque characteristic value is selected. When the reference value is reached, a control means for issuing the specified signal and a feed signal for inputting a command signal from the control means to the air supply cutoff mechanism corresponding to the operation impact wrench by the signal from the operation wrench determining means. It is characterized in that it is provided with an air shut-off mechanism selecting means, respectively.

(Operation) In the tightening control device for the impact wrench described above,
The worker can immediately start the tightening work by simply selecting the impact wrench corresponding to the object to be fastened, so that it is not necessary to set the reference value every time the object to be fastened with a different type is fastened. Also, the operation of switches and the like is unnecessary.

Further, since the above-mentioned control is performed by the centralized control device, the cost can be reduced by simplifying the device configuration, and the handling at the time of transportation or the like becomes easy.

(Example) Next, a specific example of the tightening control device for an impact wrench according to 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 portion 1 and a main body casing 2 that is continuous with the grip portion 1 and extends in the front-rear direction. The main body casing 2 includes a central casing 3 integrally connected to an upper end portion of the grip portion 1, a front casing 4 extending further forward from a front end portion of the central casing 3, and a rear casing covering a rear portion of the central casing 3. 5, an air motor 6 is housed in the central casing 3, a tightening torque generating mechanism 7 is housed in the front casing 4, and a reaction rotation amount detecting mechanism 8 is housed in the rear casing 5. ing.
The tightening torque generating mechanism 7 supports a cam 11 that is 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 the hammer 12, and rotates together with the hammer 12. Hammer frame 13, an ampule 14 that is hit by the hammer 12, and a main shaft 15 that is fixed to the ampil 14 and is driven to rotate together with the ampule 14 by being hit by the hammer 12.
The leading end of the main shaft 15 extends outward beyond the front end of the front casing 4 so that a tightening socket (not shown) can be detachably attached. . The air for operating the air motor 6 passes through the air supply pipe connection port 17 attached to the lower end of the grip portion 1 through the air supply passage 18 in the grip portion 1, passes through the air supply valve mechanism 19, and switches between forward and reverse and adjusts the flow rate. The air is supplied to the air motor 6 via the valve mechanism 21, and the exhaust air from the air motor 6 is discharged to the outside through an appropriate path. An air supply cutoff mechanism such as a solenoid valve described later is provided in the air supply passage for supplying the working air to the air motor 6. The air supply valve mechanism 19 projects the operation knob 22 in front of the grip portion 1, forms the valve element portion 24 on the inner tip of the valve rod 23 directly connected to the operation knob 22, and fits the grip portion 1. The inner end hole edge of the sleeve-shaped valve body 25 is a valve seat 26, and the valve portion 24 is formed by pushing the operation knob 22.
Is separated from the valve seat 26, and through the gap formed in this portion and the inside of the valve body 25, through the through hole 27 formed in the valve body 25, air can be supplied toward the air motor 6. . Further, a magnet 28 is attached to the back surface side of the operation knob 22 and a reed switch 29 is attached to the front portion of the grip portion 1, and when the operation knob 22 is pushed in and air supply to the air motor 6 is started. Further, the reed switch 29 can detect the proximity of the magnet 28 and activate the tightening control device described later. Therefore, the connections 31 and 31 of the reed switch 29 are led out to the outside via the connector 32. Reference numeral 33 is a forward / reverse switching lever, and 34 is a flow rate adjusting knob.

Next, the reaction rotation amount detecting mechanism 8 arranged in the rear casing 5 will be described. In this case, the mechanism 8 has a rotating disk 35 directly connected to the output shaft 9 of the air motor 6.
And a pair of photo interrupters 36 and 37 which are arranged in the rear casing 5 so as to have a phase difference with each other, and are of a rotary encoder type. Rotating disc 3
Reference numeral 5 designates a number of slits 38 formed along the circumferential direction thereof. The free end portion of the lead-out shaft 39 fixed to the rear end portion of the output shaft 9 of the air motor 6 is connected to the bolt 42 via the differential 41. Is stuck by. Each of the photo interrupters 36 and 37 is composed of a set of light emitting diodes and phototransistors which are arranged at positions opposite to each other with the rotary disc 35 interposed therebetween, and the number of slits 38 passing between them, that is, the rotary disc. 35 and output shaft 9
Generate a number of signals corresponding to the rotation angle of. Since both photo interrupters 36 and 37 are arranged so as to be out of phase with each other, the signal of one photo interrupter 36 and the signal of the other photo interrupter 37 have a phase difference, and the pulse edge of one signal It is possible to detect the rotation direction of the rotary disk 35 by determining the level of the other signal in the above. Therefore, by using the rotary encoder described above, 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 after the collision of the hammer 12 with the ampule 14 due to the reaction of the collision. .

As described above, the impact wrench A has each mechanism such as the tightening torque generating mechanism 7, the reaction rotation amount detecting mechanism 8 and the air supply cutoff mechanism. A control device B that controls the tightening torque when tightening a fastener will be described with reference to FIGS. 1 and 2. First, when the object to be fastened is, for example, three types of bolts having a diameter of 8 mm, 10 mm, and 14 mm, the impact wrench A is arranged in the same number as each type, that is, three sets, and the tip of the main shaft 15 of each impact wrench A1, A2, A3. A tightening socket for tightening the corresponding bolt shall be attached to the section. When the operator selects one of the impact wrenches A1, A2 or A3 and operates the operation knob 22 of the control device B, the reed switch 29 is operated.
Although it is activated by a signal from, if, for example, the operation knob 22 of the impact wrench A1 corresponding to a bolt having a diameter of 8 mm is operated, the output from the photo interrupters 36 and 37 of the reaction rotation amount detection mechanism 8 in the impact wrench A1. Is first sent to the Schmitt circuit 51 and subjected to waveform shaping. The count pulse output from the Schmitt circuit 51 is sent to the gate 52, and the direction pulse is sent to the gate 52 via the rotation direction changeover switch 53. The rotation direction changeover switch 53 is tightened in either direction. It is the direction of rotation, and is a part that defines which direction is the reaction rotation direction. As described above, the rotation direction of the air motor 6 is controlled by operating the forward / reverse switching lever 33.
Since it is determined by the forward / reverse changeover valve mechanism 21, the rotation direction changeover switch 53 includes the changeover lever 3
3 or the forward / reverse switching valve mechanism 21 may be interlocked. Then, as a result, only the count pulse in the reaction rotation direction is output from the gate 52, but this output is sent to the addition / subtraction counter 55 through the multiplication circuit 54 in order to improve the resolution. Addition / subtraction counter 5
5 counts by integrating this count pulse, and this count number is further counted by the Samir switches 65, 66, 6
When the preset count number set in advance to 7 is reached, a command signal is issued to the supply air cutoff mechanism selection circuit 71. Then, the supply air cutoff mechanism selection circuit 71 activates the relay 57,
The air supply shutoff mechanism 58 of the impact wrench A1 selected by the signal from the operation wrench determining circuit 70 described later 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 causes the first
As shown in the figure, the control circuit C of the control device B is formed.

By the way, in the above control device, a Samir switch (digital switch) for setting a predetermined count number.
Are provided in plurality (three in the case shown in the figure), and these Samir switches 65, 66, 67 are preset with predetermined count numbers according to the three types of bolts. The set count number corresponding to the bolt having a diameter of 8 mm is automatically input to the addition / subtraction counter 55 by operating the operation knob 22 of the impact wrench A1. That is, each impact wrench A1, A2, A3,
When the operation knob 22 is operated, the lever interlocking switch signal is input to the operation wrench determining circuit 70. Therefore, in this example, the lever-interlocking switch signal emitted from the impact wrench A1 is input to the operating wrench determining circuit 70, and the operating wrench determining circuit 70 uses the lever-interlocking switch signal to output the operating impact wrench A1. Then, the signal is output to the counter switching circuit 68 and the supply air cutoff mechanism selection circuit 71. This allows
The counter switching circuit 68 selects the set count number corresponding to the operation impact wrench A1 and selects the addition / subtraction counter 5
5, and the air supply cutoff mechanism selection circuit 7
1 is to input the command signal from the addition / subtraction counter 55 to the air supply cutoff mechanism 58 corresponding to the operation impact wrench A1, 59 is a digital display device, and addition / subtraction is performed via the decoder 60. It is connected to a counter 55 and has a Samir switch 65, 66 or 6
The difference between the set count number of 7 and the detected integrated count number can be visually displayed. 61
Is a test switch, 62 is a test reset switch, and 29 is the lever interlock switch described above.

Next, a tightening test for setting the set count number in each of the Samir switches 65, 67, 67 will be described. In this case, the object to be fastened has a diameter of 8 mm and 10 mm as described above.
For the 3 mm and 14 mm bolts, perform the following test work for each bolt and
The set count number is set to 5, 66, and 67. First, switch the test switch 61 to the test position,
Tighten the object to be fastened based on the operating sound and response when tightening. In this case, the addition / subtraction counter 55 counts up by switching the test switch 61 to the test position, and counts up when the count pulse is input. Therefore, at the end of tightening, the integrated count number of the count pulse in the reaction rotation direction from the start of tightening to the end of tightening is displayed on the digital display device 59. Next, the actual tightening torque of the fastened object tightened as described above is measured by measuring the loosening torque of the fastened object with a torque wrench or the like. Although this loosening torque varies depending on the fastener, it is about 80% of the tightening torque in most cases, so it is practically possible to estimate the tightening torque from the measurement result of the loosening torque. If the measured torque value is proper, the test ends with this, but if there is an excess or deficiency in the tightening torque, the test reset switch 6
Operate No. 2 and repeat the test, and repeat this test until the proper tightening torque is reached. Then, as a result of the above test, the numerical value of the digital display device 59 when the tightening torque value is appropriate is read, and the setting dial is turned to read this numerical value, and either Samir switch 65, 66, or 6 is read.
Setting to 7 completes the test work and releases the test switch 61. By performing the above-mentioned test work on various bolts, the optimum value of the integrated count number in the reaction rotation direction when the tightening torque becomes the optimum value is set in each of the Samir switches 65, 66, 67. Will be.

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 selects the corresponding impact wrench A1, A2 or A3 based on the diameter of the bolt to be tightened. When the operator operates the operation knob 22 of the selected impact wrench A1, A2 or A3, the air motor 6 is activated and the tightening of the bolt is started, but at the same time, the signal from the reed switch 29 is sent. The control device B is also activated,
The addition / subtraction counter 55 is automatically input with the set number ofacts corresponding to the operation impact wrench A1, A2 or A3. That is, when the lever interlocking switch of the operation impact wrench A1, A2 or A3 is input to the operation wrench determination circuit 70, and the operation impact wrench is determined by this determination circuit 70, the counter switching circuit 68 causes the determination circuit 70 to change from the determination circuit 70. Operated by the signal of Impact Wrench
The set count number corresponding to A1, A2 or A3 is selected and input to the addition / subtraction counter 55. Then, 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 by the addition / subtraction counter 55. At the start of tightening, the digital display device 59 displays the set count number of the Samir switches 65, 66, or 67. This display number is the count pulse accumulated as described above after the start of tightening. It is subtracted according to the number. When the total number of count pulses reaches the set count number and the display number on the digital display device 59 becomes zero, a command signal is issued from the addition / subtraction counter 55 and the solenoid valve or the like selected by the air supply cutoff mechanism selection circuit 71. The air supply shutoff mechanism 58 is operated to shut off the air, and the operation of the impact wrench is stopped to complete the tightening work. When the tightening work is completed, the trigger is returned, and at the same time, the set count number is automatically set again, and the preparation for the next tightening work similar to the above is completed. Then, if the diameter of the bolt to be tightened next is different from the diameter of the bolt tightened earlier, by selecting the impact wrench A1, A2 or A3 corresponding to the bolt by the operator,
It becomes possible to immediately start the bolt tightening work similar to the above without replacing the tightening socket. Thus, according to the tightening control device for the impact wrench A, one control device B and a plurality of impact wrench A are provided.
It is possible to tighten different types of objects to be fastened with 1, A2, A3 without any trouble, and since it is not necessary to set the reference value each time, it is possible to prevent the occurrence of setting mistakes,
It is possible to perform accurate torque management.

Further, since the above-mentioned control is performed by the centralized control device, the cost can be reduced by simplifying the device configuration, and the handling at the time of transportation or the like becomes easy.

(Effect of the Invention) In the impact wrench tightening control device of the present invention, a plurality of impact wrenches are provided corresponding to various objects to be fastened, and an operating wrench determining means for determining the operated impact wrench is provided. A set value switching means for selecting a reference value corresponding to the working impact wrench by the signal from the working wrench discriminating means and inputting it to the control means; Since the corresponding air supply cutoff mechanism is provided with the air supply cutoff mechanism selection means for inputting the command signal from the control means, even when tightening different types of objects to be fastened, the worker concerned By selecting the impact wrench corresponding to the object, the tightening work can be started immediately. Therefore, different types of objects to be fastened can be fastened without any trouble, and the working efficiency can be greatly improved. Moreover, setting work of the reference value by changing the object to be fastened is not necessary, so that setting error does not occur, and as a result, accurate tightening torque management can be performed.

Further, since the above-mentioned control is performed by the centralized control device, the cost can be reduced by simplifying the device configuration, and the handling at the time of transportation or the like becomes easy.

[Brief description of drawings]

1 shows an embodiment of the present invention, FIG. 1 is an overall circuit diagram of an impact wrench tightening control device of the present invention, FIG. 2 is the same block diagram, and FIG. 3 is a vertical sectional front view of the impact wrench.
FIG. 4 is a sectional view taken along the line IV-IV in FIG. A ... Impact wrench, B ... Control device, 6 ... Air motor, 7 ... Tightening torque generating mechanism, 8 ... Reaction rotation amount detection mechanism, 55 ... Addition / subtraction counter, 58 ... Air supply cutoff mechanism, 65, 66, 67 ... Samir switch, 68
...... Counter switching circuit, 70 …… Operating wrench discrimination circuit,
71 ... Means for selecting the air supply shutoff mechanism.

Claims (1)

[Claims] 1. An air motor, a tightening torque generating mechanism driven by the air motor, and a tightening torque generating mechanism for a plurality of impact wrenches arranged corresponding to various objects to be fastened. A detection means for detecting the torque characteristic value of the tightening torque and an air supply shutoff mechanism for closing the air supply passage in response to a command signal from the control means are provided, while inputting the torque characteristic value detected by the detection means of each impact wrench. In the control device, a plurality of reference value setting means for setting reference values in advance for various fasteners, an operating wrench determining means for determining an operated impact wrench, and the operating wrench determination A set value switching means for selecting a reference value corresponding to the operation impact wrench by a signal from the means, and the detected torque characteristic value The command signal from the control means is input to the control means for issuing the command signal when the selected reference value is reached and the air supply cutoff mechanism corresponding to the operation impact wrench by the signal from the operation wrench determining means. A tightening control device for an impact wrench, comprising: