JPH05285748A - Automatic screw fastening device - Google Patents

Abstract

PURPOSE:To judge the fastening condition of a screw when the screw is fastened by an automatic screw fastening device. CONSTITUTION:The upper end of a screw guide holder 6 is held via a spring 5 by a slide housing 4 which is vertically moved as a driver is moved. A bit 9 is inserted into the screw guide holder 6 to fasten a screw 7 held by the screw guide holder 6 to a work 8 with the bid 9. Objects to be detected 12 and 12 by a sensor are provided for the screw guide holder 6 at the equal elevation, and approaching sensors LS1 and LS2 are provided for the driver 3 via a bracket 11 wherein both the sensors correspond to the objects to be detected 12 and 12, but are different in sensitivity. A torque sensor 13 is provided for the bit 9, the torque sensor 13 and the approaching sensors LS1 and LS2 are connected to a judging means 14, and a display means 15 is connected to the judging means 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an automatic screw tightening device,
In particular, the present invention relates to an automatic screw tightening device that can determine the tightened state of a screw.

[0002]

2. Description of the Related Art An automatic screw tightening device has a screw guide holder for holding a screw and a bit for tightening the screw housed therein so that it can be moved back and forth. It is designed to be taken into the control unit.

[0003]

However, in the above-mentioned conventional automatic screw tightening device, it is OK or N that the sensor for judging screw tightening can be incorporated in the sequencer or the like.
Since only G is input, there is a problem that it is not possible to determine various screw tightening states. Also, OK,
If only NG can be determined, if workers are assigned to the next process, the details cannot be transmitted, and even if the next process is an automatic machine, it will not be possible to perform various operations. There is a problem.

Therefore, the present invention provides an automatic screw tightening device which can judge various screw tightening states.

[0005]

Means for Solving the Problems A screw guide holder that holds a screw and is positioned at a predetermined position with respect to a work, a bit that is housed in the screw guide holder so as to be able to move forward and backward, and that tightens the screw, and this bit. Sensor for detecting the tightening torque of the screw guide holder, a first position sensor for detecting whether or not the axial deviation of the bit with respect to the screw guide holder from the initial position is within a first predetermined distance, and for the screw guide holder A second position sensor that detects whether or not the axial displacement of the bit from the initial position is within a second predetermined distance, and tightening the screw based on the detection signals of the first and second position sensors and the torque sensor. And a determination unit that classifies the attached state into a plurality of modes.

[0006]

The screw tightening height is determined based on the detection signals from the first position sensor and the second position sensor, and the screw tightening condition is determined based on the detection signal from the torque sensor. The tightened state is classified into a plurality of modes.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, reference numeral 1 denotes an automatic screw tightening device, and a driver 3 is supported on a fixed portion 2 so as to be vertically movable. A slide housing 4 is provided below the driver 3, and the slide housing 4 supports an upper end of a cylindrical screw guide holder 6 urged by a spring 5 as shown in FIG.

As shown in FIG. 1, the screw guide holder 6 sucks and holds the screw 7 and performs the screw tightening work in a state where the tip of the screw 7 is in contact with the work 8. A bit 9 for tightening the screw 7 is housed in the rack so as to move back and forth.

Further, as shown in FIG. 3, a chuck unit 10 is provided at the tip of the screw guide holder 6 for holding the supplied screw 7, passing the screw 7 to the screw guide holder 6, and then escaping to the left and right. ing.

As shown in FIGS. 1 and 2, the driver 3 includes a proximity sensor LS1 as a first position sensor and a proximity sensor LS as a second position sensor via a bracket 11.
2 and 2 are mounted at the same height. In addition, the proximity sensor LS1, above the screw guide holder 6,
Sensor detection objects 12 and 12 corresponding to LS2 are attached. Here, the heights of the proximity sensors LS1 and LS2 are different when the tip of the bit 9 is brought into contact with the work 8 at the position where the tip of the screw guide holder 6 is brought into contact with the work 8 (initial position of the bit 9). Sensor detection object 12, 12
It is set to be the same height as.

In the proximity sensor LS1, the axial displacement X of the bit 9 at the initial position with respect to the screw guide holder 6 is determined by the height P of the head 7A of the screw 7 (strictly speaking, the head 7).
It remains ON until it becomes equal to the height of A minus the insertion depth of the bit 9 into the screw 7), and the proximity sensor LS2 has at least the displacement X of the screw 9 above the height of the screw 7. If it becomes smaller than P, it will turn ON and screw 7
It is turned off when the height is higher than P.

Therefore, the first predetermined distance in the proximity sensor LS1 is the height P of the screw 7, and the second predetermined distance in the proximity sensor LS2 is an arbitrary value Q (P> Q) smaller than the height P of the screw 7. ).

Then, as shown in FIG. 1, the bit 9 detects the tightening torque of the screw 7 and turns on when the tightening torque exceeds a certain value, and turns off when the tightening torque is less than a certain value.
A torque sensor 13 that outputs a torque-up signal is provided, and the torque sensor 13 and the proximity sensor LS are provided.
1, LS2 are connected to the determination means 14.

As shown in Table 1 below, the judging means 14 judges "OK" (completion of tightening), "screw floating", "missing item", "cling", "screw" and displays as shown in FIG. It is output to the device 15.

[0016]

[Table 1]

According to the automatic screw tightening device of the above embodiment,
When the screwdriver 3 descends during the screw tightening operation and the tip of the screw guide holder 6 abuts on the work 8, the bit 9, the bracket 11, the proximity sensors LS1 and LS2, and the slide housing 4 descend together with the driver 3 and the work 8 continues.
Tighten the screws. At this time, the screw guide holder 6 and the sensor detection objects 12, 12 supported by the slide housing 4 by the spring 5 escape upward by the spring 5.

Sensor detection objects 12, 12 which have escaped to the upper side
Is detected by the proximity sensors LS1 and LS2 to determine the tightened state of the screw 7.

FIG. 4 shows the proximity sensor LS for convenience of illustration.
1 and LS2 are arranged vertically to facilitate understanding.

In FIG. 1A, the displacement X of the bit 9 with respect to the screw guide holder 6 from the initial position is P.
Therefore, the proximity sensor LS1 is ON, the proximity sensor LS
2 is OFF. At this time, the torque-up signal is ON. Therefore, since the screw 7 is completely inserted into the work 8 and tightened, the judging means 14 judges that the screw 7 is properly tightened on the work 8, and the display device 15 displays “OK”. Is displayed as.
Here, when the torque-up signal is OFF, the screw 7 is properly inserted into the work 8 but is idling, which means that as shown in FIG.
It is determined and displayed as "screwhead".

On the other hand, in FIG. 4B, since the deviation X of the bit 9 with respect to the screw guide holder 6 from the initial position is larger than P, both the proximity sensors LS1 and LS2 are OFF and the torque-up signal is ON. Therefore, it is determined that the screw 7 is tightened without being completely inserted into the work 8 and the screw is lifted. Here, when the torque-up signal is OFF, it is determined and displayed as "clinging" as shown in FIG. 4 (d).

Further, in FIG. 4C, since the deviation X of the bit 9 from the initial position with respect to the screw guide holder 6 does not occur, both the proximity sensors LS1 and LS2 are ON, and the torque of the torque sensor 13 is large. Since the up signal turns off, the screw 7 is screwed into the screw guide holder 6
It is determined and displayed as "out of stock" which is not supplied inside.

In this way, by discriminating and displaying the tightening state of the screw 7 in plural, for example, when the screw 7 is not supplied and is out of stock, the screw 7 is supplied again or the screw 7 is supplied. When it is in a bite state, it is possible to take measures such as re-tightening without supplying screws.

Therefore, when the screw 7 is in a biting state, the screw 7 is supplied again to cause screw clogging,
It is possible to prevent the bit 9 from being damaged.

[0025]

As described above, according to the present invention, various insertion states of a screw into a work are detected using the first position sensor and the second position sensor, and the tightening torque of the screw is detected by the torque sensor. The tightening state of the screws can be detected and subdivided by the determination means based on these detection signals.

Therefore, when a worker is arranged in the next process, the contents thereof can be transmitted in detail, and when the next process is an automatic machine, the automatic machine can perform various operations.

[Brief description of drawings]

FIG. 1 is an enlarged side sectional view of a portion A of FIG. 3 according to an embodiment of the present invention.

FIG. 2 is an explanatory view of the same plane.

FIG. 3 is an overall perspective view of the same.

FIG. 4 is an explanatory view showing a tightened state of the screw.

[Explanation of symbols]

 6 ... Screw guide holder 7 ... Screw 8 ... Work piece 9 ... Bit 13 ... Torque sensor 14 ... Judgment means X ... Deviation P ... First predetermined distance Q ... Second predetermined distance LS1 ... Proximity sensor (first position sensor) LS2 ... Proximity sensor (second position sensor)

Claims (1)

[Claims] 1. A screw guide holder that holds a screw and is positioned at a predetermined position with respect to a workpiece, a bit that is housed in the screw guide holder so as to be able to move forward and backward, and that tightens the screw, and a tightening torque of the bit. , A first position sensor that detects whether or not the axial deviation from the initial position of the bit with respect to the screw guide holder is within a first predetermined distance, and an initial position of the bit with respect to the screw guide holder. Position sensor that detects whether or not the axial deviation from the position is within a second predetermined distance, and a plurality of screw tightening states based on the detection signals of the first and second position sensors and the torque sensor. An automatic screw tightening device comprising: