JPH042377B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a screw tightening robot in which a nut runner is removably attached to the wrist of the robot.

<Prior art> In robots with a large degree of freedom that allow rotational movements such as twisting, bending, and turning to the wrist, the torque of the motor that drives the wrist to rotate is small, so the wrist is equipped with screws for tightening. When a nut runner is installed, the wrist will rotate if a moment that rotates the wrist is applied due to the reaction force when tightening the screw, so it cannot be used for items that require a large screw tightening torque. The reality is that it can only be used for tightening small items such as screws.

<Object of the Invention> An object of the present invention is to provide a screw tightening robot that can increase screw tightening torque by preventing the generation of a moment that rotates the wrist due to reaction force during screw tightening. That's true.

<Structure of the Invention> In order to achieve the above object, the present invention provides a connection in which a mounting tube is fixed to the wrist of a robot, and a dovetail groove is formed at the tip of the mounting tube in a direction perpendicular to the axis of rotation of the wrist. A block is attached, a mounting base with a coupling part that slidably engages with the dovetail groove is removably attached to the connecting block, and the nut runner is mounted on this mounting base parallel to the rotational axis of the wrist and by a predetermined amount. A dowel pin, which is provided at an offset position and separably connects the connecting block and the connecting part, is inserted into the mounting tube so that it can move forward and backward in a direction parallel to the axis of rotation of the wrist part, and the reaction force when tightening the screw with the nut runner is stiffened. It is designed so that it can be received by a robot arm with a high height.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. Fig. 1 shows a screw tightening robot in which a nut runner 11 is attached to an articulated robot 10 having six degrees of freedom. a supported shoulder portion 14; a first arm portion 15 supported by the shoulder portion 14 so as to be pivotable about a horizontal axis;
A second arm 16 is rotatably supported around an axis parallel to the pivot axis of the arm 15, and a second arm 16 is supported at the tip of the second arm 16 to rotate around an axis perpendicular to the pivot axis of the second arm 16. Rotatably supported wrist portion 17
A second wrist part 18 is supported on the wrist part 17 so as to be pivotable about an axis perpendicular to the pivot axis of the wrist part 17; The third wrist portion 19 is rotatably supported by the third wrist portion 19.

2 and 3, a mounting tube 21 is fixed concentrically to the mounting flange 20 of the third wrist section 19, and the wrist section 19 is attached to the lower part of the mounting tube 21.
A connecting block 23 having a dovetail groove 22 formed in a direction perpendicular to the axis of rotation is attached. Mounting tube 2
A knock pin 24 is fitted into the inside of the wrist portion 19 so as to be slidable in the direction of the rotational axis of the wrist portion 19.
is normally held in a position protruding into the dovetail groove 22 by the action of the spring 25, but can be moved back against the spring 25 by the action of air pressure.

The nut runner 11 is fixed on a mounting base 27, and this mounting base 27 is attached to the nut runner 1.
A coupling part 30 extends perpendicularly to the axis of rotation of the nut runner, and has a coupling part 30 at its tip consisting of an engagement guide part 28 that slidably engages with the dovetail groove 22 and a notch hole 29 that fits into the dovetail pin 24. 11
It is offset by a predetermined amount. The mounting base 27 is normally attached to the fixed frame 3 by a pair of positioning pins 32 protruding from the fixed frame 31.
The wrist part 19 is moved along the engagement guide part 28 of the mounting base 27 in a state parallel to the nut runner 11 under the movement control of the robot 10. The dovetail groove 22 on the wrist portion 19 side is engaged with the guide portion 28, and the notch hole 2 is closed by the action of the spring 25.
The mounting base 27 is integrally connected to the wrist portion 19 by fitting the dowel pin 24 into the wrist portion 9 .

The nut runner 11 is attached to the attachment base 27 at a position parallel to the axis of rotation of the wrist portion 19 to which the attachment base 27 is coupled and offset by a predetermined amount from the axis of rotation. This nut runner 11 includes a support tube 34 fixed to a mounting base 27, and a movable tube 3 connected to the support tube 34 through a flexible member so as to be able to rotate slightly relative to the support tube 34.
5, a drive shaft 37 which is rotatably and axially movably supported by the movable cylinder 35 and has a socket 36 (FIG. 1) attached to its tip that engages with a corner of a bolt or the like;
The screw tightening torque is managed by using a sensor to detect the deflection of the flexible member due to the reaction force of screw tightening. There is.

In the above configuration, for example, the plurality of mounting bases 27 to which several types of nut runners 11 with different screw tightening torque ranges are attached are usually stored at predetermined positions on the fixed frame 31, and depending on the content of the screw tightening work. The specified nut runner 1
1 is attached to the mounting base 27, which is attached to the robot 10.

To attach the mounting base 27 to the robot 10, the wrist portion 19 is held parallel to the axis of the nut runner 11, and the wrist portion 19 is attached to the engagement guide portion 2.
8, and the dovetail groove 22 is moved along the engagement guide portion 2.
At the same time, the notch pin 24 is engaged with the notch hole 29 by the action of the spring 25, whereby the mounting base 27 on which the nut runner 11 is mounted is integrally connected to the wrist portion 19. Thereafter, as the wrist portion 19 rises, the mounting base 27 is separated from the positioning pin 32 of the fixed frame 31 and transferred to the screw tightening position.

At this screw tightening position, the nut runner 11
Screws such as bolts are tightened, and the reaction force at the time of tightening the screws is applied to the wrist portion 19 via the mounting base 27.
However, since the axis of rotation of the nut runner 11 (center of the socket) is parallel to the axis of rotation of the wrist portion 19 and offset by a predetermined amount,
As shown in Fig. 4, the reaction force when tightening a screw is that only a rotational moment F with a radius equal to the offset amount OS acts on the wrist portion 19, and this rotational moment is transmitted from the wrist portion 19 through the wrist portions 18 and 17 to the rigidity. high second
Since it is received on the arm portion 16 side, no force that would cause the wrist portion 19 to rotate is generated. Therefore, it can withstand high torque screw tightening.

In the above embodiment, an example was described in which the nut runner is removably attached to the wrist at the tip of an articulated robot having six degrees of freedom. It is also effective when applied to robots with

<Effects of the Invention> As described above, the present invention provides a connecting block in which a mounting cylinder is fixed to the wrist at the distal end of the robot, and a dovetail groove is formed at the distal end of the mounting cylinder in a direction perpendicular to the axis of rotation of the wrist. A mounting base is removably attached to this connecting block, and the nut runner is mounted parallel to the rotational axis of the wrist part and offset by a predetermined amount to this mounting base. The nut runner is installed at a position where the nut runner is attached to the wrist of the robot, and the nut runner is inserted into the mounting tube so that it can move forward and backward in a direction parallel to the axis of rotation of the wrist. Even in cases where the robot arm is removably attached, the reaction force generated when tightening the screws by the nut runner does not generate a moment that would cause the wrist to rotate, and the reaction force is absorbed by the highly rigid robot arm. Therefore, it is possible to obtain a screw tightening robot that can sufficiently withstand large screw tightening torques.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 shows the entire screw tightening robot, and FIG. 2 shows the entire screw tightening robot.
FIG. 3 is a view taken from the direction of FIG. 2, and FIG. 4 is a view showing the screw tightening reaction force acting on the wrist. 10... Robot, 11... Natsutranna, 1
3... fixed base, 14... shoulder, 15... first
Arm part, 16... Second arm part, 17, 18, 19...
Wrist part, 27... Mounting base, 30... Connecting part.

Claims (1)

[Claims] 1. A robot having at least four degrees of freedom with a rotatable wrist at the tip, a mounting tube fixed to the wrist of the robot, and an angled member attached to the tip of the mounting tube in a direction perpendicular to the axis of rotation of the wrist. A connecting block with a groove formed thereon is attached, a mounting base having a coupling portion that slidably engages with the dovetail groove is removably attached to the connecting block, and a nut runner is attached to the mounting base along the axis of rotation of the wrist portion. A dowel pin is provided at a position parallel to the wrist part and offset by a predetermined amount, and a knock pin for releasably coupling the connecting block and the coupling part is fitted into the mounting tube so as to be movable in a direction parallel to the rotational axis of the wrist part. A screw tightening robot.