JPS58160029A - Screw fastening device - Google Patents

Abstract

PURPOSE:To improve the precision of the stopping position of a screw fastening device by a method wherein in the case of the screw fastening device operated by a robot, the rotational velocity of a screw fastener is made to correspond with the pitch of a screw and a mechanism for moving arms in the vertical direction is lowered at the time of fastening the screw. CONSTITUTION:When a first arm 10 and a second arm 11 are turned horizontally by a first drive motor 9 and a second drive motor and the screw held by a screw holding section 15a of a spindle 15 of the screw fastener comes to a position right above a work, a drive motor 3 of the mechanism 2 for moving the arms up and down is so controlled that the number of revolutions of the motor 3 corresponds to the rotational velocity of the screw fastener 12 and the pitch of the screw and then the screw is fastened by lowering the screw fastener. In this case, the arm moving mechanism 2 is lowered by interrupting electricity supplied to the drive motor 3. Thus, in the above arrangement, no air cylinder or the like is provided so that the load applied on the top end of each the arms is reduced and the precision of determination of the stop position of the screw fastener is improved since the moment of inertia of the arm is small.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screw tightening device for tightening screws by a robot.

First, a screw tightening device t proposed prior to the present invention will be explained with reference to FIGS. 1 and 2.

In FIGS. 1 and 2, reference numeral 1 indicates a robot main body, which is a torso, and reference numeral 2 indicates an arm vertical movement mechanism provided on the main body 1. In FIG. This vertical movement mechanism 2 has a screw shaft 4 rotated by a drive motor 3.
and an elevating body 6 having a nut 5 screwed into the screw shaft 4.
and a guide 7 provided on the elevating body 6, and the guide 7 is engaged with a guide rail 8 fixed within the main body 1 to guide the elevating body 5 in the vertical direction. 9 is a first arm drive motor provided on the elevating body 5; lO is a first arm supported by the elevating body 5 and horizontally reciprocated by the first arm drive motor 9; 11 is the tip of the first arm 10; A second arm 12 is supported by a second arm 10 and horizontally reciprocated by a second arm drive motor (not shown) built into the arm 10. A freely supported screw tightening machine, 14 is a support frame 1
This is an air cylinder mechanism that is fixed to 3 and moves the screw tightening machine 12 up and down. The screw tightening machine 12 is a conventional screw tightening machine in which a main shaft 15 rotated by a motor is supported perpendicularly to a body 16, and a screw holding part 15a is provided at the lower end of the main shaft 15.

In the screw tightening device configured as described above, the screw shaft 4 is rotated by the drive of the drive motor 3, the elevating body 6 moves up and down via the nut 5, and the first arm 10 supported by the elevating body 6 is rotated. The screw tightening machine 12 also moves up and down together with the second arm 11, and the first arm sliding motor 9 degrees and the second arm driving motor move the first arm 9 degrees. Second
Arms 10° and 11 each rotate horizontally to tighten screw tightening machine 1.
2 moves horizontally, and a screw such as a nut or bolt held by the screw holding portion 15 & of the main shaft 15 is located directly above the workpiece. At this position, the elevating body 6, the first arm and the second arm]
(+, ll' are stopped, the air cylinder mechanism 14 is fully operated, the screw tightening machine 12 is lowered and operated, and the screw holding part 15 is inserted into the bolt or screw hole of the workpiece.
The nuts or bolts held by & are automatically tightened, and after the tightening is completed, the holding of the nuts or bolts by the screw holding part 15m is released, and the screw tightening machine 12 is raised and returned by the operation of the air cylinder mechanism 14.

In the screw tightening device described above, an air cylinder mechanism and a support frame for moving the screw tightening machine up and down are attached to the tip of the arm of the robot. For this reason, the load on the tip of the arm becomes heavy, and it is necessary to increase the strength and rigidity of the arm. There is a problem in that this becomes a factor in deteriorating stop positioning accuracy.

This invention solves the above-mentioned problem by fixing only the screw tightening machine to the tip of the arm, and lowering the screw tightening machine by controlling the lowering of the arm vertical movement mechanism when tightening the screw. It is an object of the present invention to provide a screw tightening device that can reduce the load on the tip, require a small driving force, and improve the accuracy of stopping positioning of the tip of the arm.

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. Among these figures, Fig. 1.1. The same reference numerals as in FIG. 2 indicate the same or corresponding parts, and 11 is the second arm;
At the tip of this arm 11, there is a screw tightening lock 120 and a fuselage 16.
It does not have a support frame or an air cylinder mechanism like those described above.

In the screw tightening device of this embodiment, when tightening a screw, the number of rotations in the downward direction of the drive motor 3 of the arm vertical movement mechanism 2 is adjusted to the rotation speed of the screw tightener 120 and the pitch of the screw such as a nut or bolt to be tightened. The first step is performed by controlling to the corresponding required value. While lowering the second arms 10 and 11 and the screw tightening machine 12, the screws held on the main shaft 15 are automatically tightened. After the tightening is completed, the screw tightening machine 12 is raised by the rotation of the drive motor 3 in the upward direction. This is done via the second arms 10 and 11.

Note that the configuration and operation of this embodiment other than those described above are the same as those in the first
Since it is the same as the screw tightening device shown in FIGS. 2 and 2, the explanation will be omitted.

In the above embodiment, the number of rotations of the drive motor in the downward direction is controlled when tightening the screws, but in this invention, the drive motor of the arm vertical movement mechanism is disconnected from the power supply when tightening the screws, and the arm and screws are tightened by its own weight. The machine may also be controlled to descend. In this case, a brake that brakes the descent of the arm is combined with the arm vertical movement mechanism, and the arm vertical movement that moves the elevating body up and down by the engagement of the pinion and rack. A mechanism may also be used. Furthermore, in the above embodiment, the first. Although a second arm is provided, the invention may also be of one arm.

As explained above, the present invention supports a robot main body that supports an arm that rotates horizontally so as to be movable in the vertical direction, and uses a mechanism provided in the robot main body to move the arm in the vertical direction.

A screw tightening machine that is directly fixed to this via an arm is lowered to tighten the screws, and when tightening the screws,
Since the above mechanism is controlled to descend by cutting off power to the drive motor of the mechanism that moves the arm in the vertical direction, it does not have an air cylinder mechanism to move the support frame or screw tightening machine up and down. In addition, the load on the tip of the arm can be reduced, and the screw tightening machine can be moved through the arm with a small driving force.Moreover, the moment of inertia at this time is small, and the load on the tip of the arm, The effect of improving the stop positioning accuracy of the screw tightening rock can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a screw tightening device proposed prior to this invention, FIG. 2 is a side view of the same, FIG. 3 is a plan view showing a screw tightening device according to an embodiment of this invention, and FIG. 4 is the same side view. 1...Robot body, 2...Arm vertical movement mechanism,
3... Drive motor, 6... Elevating body, 10... First arm, 11... Second arm, 12... Screw tightening machine, 15... Main shaft, 15 a... Screw retainer. In addition, the same reference numerals in the drawings indicate the same or corresponding parts. Agent Makoto Tameno - Shigeru 1 Figure f3 Figure Chief Office of the License Agency
12.5 Tome's name Screw-fastened main phone, 3. Person making the amendment Relationship to the case Permit 1 #rj representative Hitoshi Katayama 4, agent 5, subject of amendment (1) Statement of the specification Claims column 6, Contents of amendment (11 Amend the claims in the specification by attaching a separate sheet. 7. Attached documents Document stating the entire text of the amended claims 2, Claims (11) The robot body supports an arm that rotates horizontally so that it can move freely in the vertical direction, and the robot body is equipped with a mechanism that moves the arm in the vertical direction. A screw tightening device characterized in that the mechanism for moving the arm in the vertical direction is controlled to descend at a speed corresponding to the rotational speed of the screw tightening machine and the screw pitch when tightening the screw. 2) The screw tightening device according to claim 1, wherein during screw tightening, power is cut off to a drive motor of a mechanism for moving the arm in the vertical direction, so that the arm and the screw tightening machine are lowered by their own weight.

Claims (1)

[Claims] (11) A horizontally rotating arm is supported on the robot body so as to be movable in the vertical direction, a mechanism for moving the arm in the vertical direction is provided on the robot body, and only a screw tightening machine is installed at the tip of the arm. , the screw tightening direction is fixed in the downward direction, and when the screw is tightened, the rotational speed of the screw tightening machine is adjusted to a speed corresponding to the screw pitch, and the mechanism for moving the arm in the vertical direction is controlled downward. (2) When tightening a screw, electricity is cut off to a drive motor of a mechanism that moves the arm in the vertical direction, so that the arm and the screw tightening machine are lowered by their own weight. The screw tightening device described,