JPH0532183B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a bolt tightening method used when attaching a door to a vehicle body during automobile assembly, and in particular,
The present invention relates to a bolt tightening method that prevents seizure during bolt tightening. [Prior Art] Conventionally, a door is assembled to a vehicle body on an automobile body assembly line in the following manner.
That is, as shown in FIG. 4, when the vehicle body 1 is transported and positioned to the door assembly station A provided on the vehicle body assembly line, in conjunction with this operation, a hanging transport device (not shown) A door 2 as shown in FIG. 5 to be assembled to a vehicle body 1 is transported to above a door assembly station A, and the door 2 is suspended and supported at this position. Next, the multi-jointed door handling robot 10 grounded at the door assembly station A is activated, and the door 2 supported by the hanging conveyance device is moved by the door gripping device 11 provided at the end of the arm of the door handling robot 10. and transport the door 2 from the hanging support device to the door mounting opening 1a of the vehicle body 1 positioned on the door assembly station A, and position and hold the door 2 within this opening 1a. do. Next, in this state, the door 2 is bolted to the vehicle body 1 using the bolt tightening robot 15 having the hinges 3 and 4 and a nut runner, which are pre-installed at two locations on the top and bottom of the front edge of the door 2. It is attached to the opening 1a. Door 2 as above
The vehicle body 1 that has been installed is transported to the next station, and when the next vehicle body 1 is transported to the door assembly station A, the above operations are performed again, and thereafter the above operations are performed continuously. repeated. The bolt tightening robot 15 used for bolting the door 2 to the vehicle body 1 has a mounting plate 1 attached to the tip of the arm of the multi-articulated robot, as shown in FIG.
The nut runners 17 and 18 are arranged in parallel with each other at a predetermined interval through the nut runners 6, and
Socket portion 17 at the tip of nut runners 17 and 18
As shown in FIG. 7, bolts 20 are attached to a and 18a.
A holding mechanism for suctioning and holding the head 20a is incorporated. When the bolt tightening robot 15 bolts the door 2 to the vehicle body 1, first, the heads 20a of the bolts 20 are conveyed to the vicinity of the bolt tightening robot 15 in an aligned state by a bolt feeder (not shown). The nut runners 17 and 18 are attached to the bolt tightening robot 15.
The socket portions 17a and 18a of the holder are held by suction. Next, the nut runners 17, 18 holding the bolts 20, 20 by suction are moved toward the door 2 side which is positioned and held in the vehicle body opening 1a, and the upper mounting holes 3a, 4a of the upper and lower door hinges 3, 4 of the door 2 are moved.
Insert the bolts 20, 20 through. After that, the bolts 20,
20 and tighten. In this way, when the bolts 20, 20 are inserted into the upper mounting holes 3a, 4a of the upper and lower door hinges 3, 4 and tightened, the nut runners 17, 18 are once separated from the vehicle body 1, and then the same process as described above is performed. Then, insert the bolts 20, 20 into the respective lower mounting holes 3b, 4b of the upper and lower door hinges 3, 4, and screw and tighten them into nuts fixed to the vehicle body 1 side, thereby attaching the bolts of the door hinges 3, 4 to the vehicle body 1. End the stop. [Problems to be Solved by the Invention] As described above, when the door 2 is bolted to the vehicle body 1 by the bolt tightening robot 15 having the nut runners 17 and 18, the bolt tightening by each nut runner 17 and 18 is Detection of completion of attachment is normally performed by torque detection. That is,
After bolt tightening is started by the nut runners 17 and 18, when the tightening torque by the nut runners 17 and 18 reaches a preset value, for example, 250 kgcm, the bolt tightening is completed and the bolt tightening is terminated. However, when the completion of bolt tightening is detected by the above method, even if the bolt 20 seizes during tightening and the bolt 20 does not move at that point,
If the tightening torque applied to this stuck bolt 20 exceeds the set value, the nut runner 1
7 or 18 indicates that the bolt 20 has been tightened, and the bolt 20 has been tightened.
There was a problem that there was a risk that a product with a defective assembly would be passed on to the next process. [Means for solving the problem] When automatically tightening bolts using a nut runner, the bolts are temporarily tightened with a tightening torque lower than the tightening torque required for bolt tightening, and then,
The temporarily tightened bolt is then reversely rotated by a predetermined angle, and then the bolt after this reverse rotation is rotated in the normal direction again with the tightening torque required for bolt tightening to fully tighten the bolt. When the bolt does not rotate within a predetermined rotational torque during reverse rotation, seizure occurs. [Function] As mentioned above, during the bolt tightening process, the bolt is reversed once and bolt seizure is detected, thereby ensuring that the product with bolt seizure is passed on to the next process as is. This is to prevent [Example] Figures 1 to 3 illustrate a specific example of bolt tightening by controlling the movement of the bolt tightening robot 15 described above using the bolt tightening method according to the present invention. It is for the purpose of First, the outline of the work order when tightening bolts according to the present invention will be explained. First, the bolts 20, 2 are conveyed in an aligned state to the door assembly station A by a bolt feeder (not shown).
0 to the socket part 17 of the nut runners 17 and 18.
a, 18a, and take it out from the bolt feeder. Next, after detecting whether or not the bolts 20, 20 are accurately attracted to the socket parts 17a, 18a using a bolt dropout inspection machine 25, which will be described later, the bolts 20, 20 are inserted into the upper and lower door hinges 3,
4 into the upper mounting holes 3a, 4a, and tighten the bolts 2
0 and 20 into the nut on the vehicle body side, and in this state, temporarily tighten with a tightening torque lower than that required for tightening the bolt. Next, the bolts 20, 20 that have been temporarily tightened are reversely rotated by a predetermined angle, and the presence or absence of bolt seizure is detected by this reversal. That is, after temporarily tightening the bolts 20,
If seizure occurs on bolt 20, bolt 20, 2
At this stage, bolt 2 cannot be rotated forward or reverse unless a strong rotational torque is applied.
If you apply reverse rotation to 0 and 20 with a predetermined rotational torque,
It is possible to easily detect whether seizure has occurred in the bolts 20, 20. And bolts 20, 20
When it is detected that no seizure has occurred, the bolts 20, 20 are rotated in the normal direction again, and the bolts are tightened with the necessary tightening torque, and the bolts are inserted into the upper mounting holes 3a, 4a of the upper and lower door hinges 3, 4. Finish bolt tightening. In this way, after tightening the bolts to the upper mounting holes 3a and 4a of the upper and lower door hinges 3 and 4, the upper mounting holes 3a and 4a are tightened in the same way as above.
b and 4b, and the bolting of the door hinges 3 and 4 to the vehicle body 1 is completed. At the initial stage of the series of bolt tightening processes mentioned above,
socket portions 17a of both nut runners 17, 18;
The bolt dropout detector 25 that determines whether or not the bolts 20, 20 are held by suction on the bolt 18a is a second
It has a structure as shown in the figure. That is, the base plate 26
First and second inspection parts 29 and 30 are provided at two locations above and below a mounting plate 28 supported by an upright column 27, and a floodlight 31 is arranged approximately at the center of the mounting plate 28.
and an optical fiber 3 extending from the light receiver 32, respectively.
The end surfaces of 3 and 34 are inspected by the first and second inspection parts 29 and 3.
0, they are arranged opposite to each other with brackets 35 and 36 interposed therebetween. And Natsutranna 1
By attracting the bolts 20, 20 with the socket parts 17a, 18a of 7, 18, the bolts 20, 20,
20 from the bolt feeder, the socket portions 17 of the nut runners 17 and 18 are removed.
a, 18a are once positioned immediately before the first and second inspection sections 29, 30 of the bolt dropout inspection device 25, and the bolts 2 held by suction in the socket sections 17a, 18a.
0 and 20 are located in the first and second inspection sections 29 and 30. Then, at this time, the socket portion 17a,
If the bolts 20, 20 are accurately attracted and held by the bolts 18a, the light from the projector 31 will be reflected by the bolts 20, 20.
0, the light does not enter the light receiver 32, and the bolts 20,
If there is no bolt 20, the light from the projector 31 will directly enter the light receiver 32, so the presence or absence of the bolts 20, 20 is detected based on the presence or absence of the light incident on the light receiver 32. In this way, when the presence or absence of bolts 20, 20 is detected, if there are bolts 20, 20 in both socket parts 17a, 18a, the process proceeds to the next step, and If the bolts 20, 20 are not present, the process returns to the beginning and the bolts 20, 20 are held by suction again. Moreover, the socket parts 17a, 18a
If there is a bolt 20 on only one of them, it is difficult to re-adsorb and hold the bolt 20 in this state, so after removing the bolt 20 that is suction-held from the socket part 17a or 18a,
Perform re-adsorption and retention. A chuck device 40 having a pair of gripping claws 41, 41 is used as a dropping means for removing the bolt 20 from the socket portion 17a or 18a.
are arranged on a support plate 42 extending horizontally from below the support column 27, as shown in FIG. Then, the bolt 20, which is held by suction on only one of the socket parts 17a, 18a, is positioned between the pair of gripping claws 41, 41 of the chuck device 40, and the bolt 20 is gripped by the gripping claws 41, 41. After that, by separating the nut runners 17 and 18 from the chuck device 40, the socket portion 17a
Alternatively, the bolt 20 is made to fall off from the bolt 18a. Further, the bolt 20 gripped by the gripping claws 41, 41 falls under its own weight into a receiving box 43 disposed below the gripping claws 41, 41, and is housed therein. Bolt feeder 4 configured as described above
5, bolt dropout inspection machine 25, nut runner 17,
Bolt tightening robot 15 and vehicle body 1 having 18
Door handling robot 1 that supplies door 2 to
0 is connected to one control unit 46 as shown in FIG.
5. The control unit 46 and the bolt tightening robot 15 are controlled as outlined above based on the signals from the bolt dropout inspection machine 25 and the door handling robot 10, and the door 2 is bolted to the vehicle body 1. In addition, bolt feeder 45, bolt dropout inspection machine 2
5 and the door handling robot 10 to the controller 46, the following signals are output. That is, from the bolt feeder 45, the bolt 20
Nut runner 1 of the bolt 20 indicates a bolt presence signal indicating a supply possible state to the nut runners 17 and 18 of the bolt 20
A bolt removal completion signal indicating the completion of the bolt removal by the nut runners 17 and 18, a bolt removal failure signal indicating the bolt removal failure by the nut runners 17 and 18, etc. are output. In addition, the bolt 20 is detected by the bolt dropout inspection machine 25.
is the socket part 17 of both nut runners 17 and 18.
The bolt presence signal indicates that the bolt 20 is accurately attracted and held in the socket part 17a and 18a.
A bolt no signal indicating that there is no bolt in sockets 17a or 18a, a bolt grasping completion signal indicating that the chuck device 40 has grasped the bolt 20 that is sucked and held only in either one of the socket portions 17a or 18a, etc. are output. In addition, from door handling robot 10,
A door carry-in completion signal indicating that the door 2 has been carried into the vehicle body opening 1a; a door position correction completion signal indicating that accurate positioning within the opening 1a of the door 2 carried into the vehicle body opening 1a has been completed; etc. will be output. Furthermore, the nut runners 17 and 18 of the bolt tightening robot 15 output to the controller 46 a temporary tightening completion signal, a final tightening completion signal, an abnormality signal indicating that bolt seizure has been detected due to inability to reverse rotation, and the like. In the above configuration, the specific work order when bolting work performed when attaching the door 2 to the vehicle body 1 using the bolt tightening method according to the present invention will be explained according to the flowchart shown in FIG. Then, it is as follows. First, in step 50, bolt tightening robot 1
The nut runners 17 and 18 of No. 5 are moved toward the bolt feeder 45 side, and the bolts 20 and 20, which are conveyed in an aligned state to the assembly station A by the bolt feeder 45, are moved to the nut runners 17 and 18.
18 socket parts 17a and 18a, and taken out from the bolt feeder 45. next,
In step 51, it is determined whether or not the two bolts 20, 20 have been accurately removed from the bolt feeder 45. If both bolts 20, 20 have been removed, the process moves to step 52. When a bolt removal failure is detected, the process first moves to step 52, where it is determined whether or not the number of occurrences of the bolt removal failure during the current extraction operation has reached the third time. Then, the process returns to step 50 and the bolts 20, 20 are taken out from the bolt feeder 45 again. Furthermore, if the bolts 20, 20 fail to be taken out twice in a row, and if the bolts also fail to be taken out for the third time, the process moves to step 52, and the nut runners 17, 18, which failed to take out the bolts, are directed towards the bolt dropout inspection machine 25. Move, Natsutranna 17,1
After positioning the socket parts 17a, 18a of 8 in front of the first and second inspection parts 29, 30, step
After passing through step 54, the process proceeds to step 55. Then, both socket portions 17a, 18 of the nut runners 17, 18
If there is no bolt 20 in a, the process moves to step 56, where it is determined whether or not the number of occurrences of bolt 0 in the current extraction operation is the second time, and if it is the first time, the process returns to the start and repeats the above operation. Repeat. Also bolt 0
When this occurs for the second time, it is considered that there is an abnormality in the bolt feeder, so an abnormality signal is output and the device is stopped. Moreover, both socket parts 17a, 18a
If there is a bolt 20 on only one side of the
57, the bolt 20 that is attracted to the socket portion 17a or 18a is inspected by a bolt dropout inspection machine 25.
After removal by the chuck device 40 provided below, the process returns to the start. Further, when the process moves from step 51 to step 52 as described above, the nut runners 17 and 18 are moved toward the bolt dropout inspection machine 25 after bolt removal is completed, and the nut runners 17 and 18 are moved toward the bolt dropout inspection machine 25.
After the socket portions 17a, 18a of No. 7, 18 are positioned immediately in front of the first and second inspection portions 29, 30, the process proceeds to step 54. Then, in step 54,
Bolts 20, 20 are attached to both socket parts 17a, 18a.
It is determined whether or not it is accurately held by suction. If it is not held by suction, the process moves to step 55, and then the same operation as described above is performed. Further, when it is confirmed that the bolts 20, 20 are accurately attracted and held, the process moves to step 58, in which the door handling robot 10 closes the vehicle body opening 1a.
Check to see if Door 2 has been brought in.
Once confirmed, move on to step 59 and tighten bolt 2.
Nut runners 17 and 18 that adsorbed and held 0 and 20
are moved toward the door 2 side, and the bolts 20, 20 are inserted into the respective upper mounting holes 3a, 4a of the upper and lower door hinges 3, 4 of the door 2. Next, proceed to step 61, screw the bolts 20, 20 into the nuts on the vehicle body side, and in this state temporarily tighten with a tightening torque lower than the tightening torque required for bolt tightening.
The process proceeds to step 60, in which the nut runners 17, 18 are reversed in order to reverse the temporarily tightened bolts 20, 20 by a predetermined angle, and then the process proceeds to step 62. Furthermore, following the reversal of Natsutranna 17 and 18,
The rotational torque set in the nut runners 17 and 18 is set to the tightening torque required for bolt tightening or a value higher than that, and in this step 62, the nut runners 17 and 18 that sent the reverse rotation signal are set. By determining whether or not the rotation torque is lower than the specified rotation torque, it is determined whether or not seizure has occurred in the bolts 20, 20. At this point, if at least one of the nut runners 17 and 18 does not reverse rotation below the set rotational torque, it is determined that the bolts 20 and 20 have seized, and the current automatic bolt tightening work is started here. finished,
The vehicle body 1 in which this seizure has occurred will be reworked in the next process. If the nut runners 17 and 18 are reversed, the process moves to step 63, where it is determined whether the reversal angle has reached a preset value (for example, -540°), and if the set angle has not been reached, the process proceeds to step 63. Returning to step 61, the nut runners 17 and 18 continue to be reversed. When the reversal angle reaches the set angle, the process moves to step 64, and the nut runner 17,
After stopping the reversal of the door 18, the process moves to step 65, where the door handling robot 10 corrects the position of the door 2 with respect to the opening 1a of the vehicle body, thereby accurately positioning the door 2. In this way, the vehicle body opening 1 of the door 2
When accurate positioning with respect to a is completed, the process moves to step 66, and the nut runners 17 and 18 are rotated in the normal direction to rotate the bolts 20 and 20 in the normal direction again.This time, the bolts 20 and 20 are tightened with the tightening torque necessary for tightening the bolts. Tighten the upper and lower door hinges 3 and 4.
Finish tightening the bolts to the upper mounting holes 3a and 4a. In this way, when bolt tightening to the upper mounting holes 3a, 4a of the upper and lower door hinges 3, 4 is completed, the process moves to step 67, and the nut runners 17, 18 of the bolt tightening robot 15 are moved toward the bolt feeder 45 again. Then, the bolts 20, 20 are again sucked and held by the socket portions 17a, 18a of the nut runners 17, 18. Afterwards, perform the same operations as those performed from step 51 to step 66 above from step 68 to step 81, and
Tighten the bolts to the lower mounting holes 3b and 4b of the upper and lower door hinges 3 and 4, and
Finish bolting work to. Furthermore, step 67
When the bolts are tightened in step 81, the position correction work of the door 2 relative to the door opening 1a performed in step 65 is not performed. By the tightening method described above, the nut runner 17,
When tightening the bolts 20, 20 using the nut runners 18, the operating time or angle, rotation speed, and tightening torque of the nut runners 17, 18 during temporary tightening, reverse rotation, and final tightening are as shown in the table below, for example. Just leave it there.

〔Effect of the invention〕

As described above, in the present invention, the bolts are temporarily tightened, and then the bolts are once reversed to detect whether seizure has occurred in the bolts, and then the bolts are finally tightened. Therefore, if seizure occurs during automatic tightening of bolts, this seizure can be reliably detected, and it is possible to reliably prevent products with bolt seizure from being passed on to the next process. become.

[Brief explanation of the drawing]

Fig. 1 is a flowchart for explaining the bolt tightening method according to the present invention, Fig. 2 is a perspective view showing a bolt dropout inspection machine, Fig. 3 is a block diagram showing the configuration of the present invention, and Fig. 4 is a A perspective view showing an example of a door assembly station in an automobile manufacturing line,
FIG. 5 is a side view showing the shape of the door, FIG. 6 is a perspective view showing a nut runner installed at the tip of the bolt tightening robot, and FIG. 7 is a sectional view showing an example of a socket at the tip of the nut runner. 1...Vehicle body, 1a...Opening, 2...Door,
3, 4... Door hinge, 3a, 4a... Upper mounting hole, 3b, 4b... Lower mounting hole, 15... Bolt tightening robot, 17, 18... Nut runner, 1
7a, 18a...socket part, 20...bolt.

Claims (1)

[Claims] 1. When automatically tightening bolts using the NatsuTrunner, the bolts are temporarily tightened with a tightening torque lower than the tightening torque required for bolt tightening, and then,
The bolt that has been temporarily tightened is reversely rotated by a predetermined angle, and then the bolt after this reverse rotation is rotated in the normal direction again with the tightening torque necessary for bolt tightening to fully tighten the bolt. A bolt tightening method characterized in that seizing occurs when the bolt does not reverse within a predetermined rotational torque when reversing.