JPH04251678A - Wrist driving device of multiaxial robot - Google Patents

Abstract

PURPOSE:To directly drive respectively freely rotatable wrist parts and actuating members, such as spot welding gun, by means of a motor mounted to the member, which exists on a driving side, among these members without the intervention of transmission members. CONSTITUTION:The functions of an S4 axis and an S5 axis, i.e., the rotation of a revolving rod 18 and the rotation of arms 19, 20 are executed by the motor 25 mounted to the rear end of an arm 17. A timing belt 26 is put on the pulleys mounted to the revolving alignment shafts of both arms 19, 20 in order to transmit the driving power of the motor 25 to the rotation of the arm 20. On the other hand, the function of the S6 axis, i.e., the function to rotate the wrist 21 in the arrow S6 axis direction is executed by the driving device built into the arm 20. Similarly, the functions of the S7 axis and S8 axis are attained by the driving device built into the wrist part 21. Then, the functions of the S6 to S8 axes are directly driven without transmitting the driving power from the driving source on the robot body side.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wrist drive device for a multi-axis robot that drives the wrist of a robot having multi-axis functions, for example, about eight axes.

0002

2. Description of the Related Art A car body assembly process usually includes a floor main process, a main body process, and a metal line process. The floor main process is a process in which a front floor panel, a rear floor panel, etc. are joined to form a floor main, and the main body process is a process in which body side panels, roof panels, etc. are joined to the floor main. In this process, welding work may be performed on various parts of the vehicle interior with the roof panel attached. The robot used for such work has a multi-axis function of about eight axes. When welding is to be performed on various parts within the vehicle interior, a spot welding gun is attached to the wrist attached to the tip of the robot's arm. In order to enable this welding gun to move in a complicated trajectory, the spot welding gun is provided with a function of a total of eight axes, for example, as described above.

0003

[Problems to be Solved by the Invention] Conventionally, in a robot having such a multi-axis function, a wrist drive device is attached to the rear end of the robot arm in order to drive a welding gun that is attached to the wrist at the tip of the robot arm. I try to place it in the department. FIG. 6 is a diagram showing an example of a conventionally used multi-axis robot. As shown in this diagram, a wrist motor 2 for driving a wrist part 1 is attached to the rear end of an arm 3. The power of the wrist motor 2 is transmitted to the wrist part 1 by a shaft built into the arm 3. In this way, the reason why the motor 2 is attached to the rear end of the arm 3 in order to drive the wrist part 1 located at the tip of the arm 3 is because the drive motor is built into the wrist part 1. This is because it is necessary to assemble the brake section and the speed reducer to this drive motor, which increases the size of the wrist section 1 itself. However, in this way arm 3
If the wrist motor 2 is attached to the rear end, if the arm is made up of two arms that can be bent together, the power will be transmitted to the wrist via the bendably joined shaft. There is a problem that the circumference of this shaft portion becomes very large.

The present invention has been made in view of the above-mentioned problems of the prior art, and has a compact drive device built into the wrist to drive the wrist, thereby achieving the desired performance without increasing the size of the wrist itself. The purpose is to enable operation.

[0005]

[Means for Solving the Problems] To achieve the above object, the present invention includes a wrist portion rotatably attached to the tip of a robot arm, and a wrist portion rotatably attached to the wrist portion. In the wrist drive device for a multi-axis robot, the arm, the wrist portion, and the actuating member, which is the driving side, are equipped with a motor. A speed reducer is formed by a driving-side rotating body attached to the main shaft of the motor, and a driven-side hollow rotating body fixed to the driven-side member of the arm, the wrist portion, and the actuating member. and a fan that prevents a temperature rise in the speed reducer is provided on the main shaft of the motor, and a bearing member that rotatably supports the driven hollow rotating body is located at a position axially offset from the driven hollow rotating body. This is a wrist drive device for a multi-axis robot.

[0006]

[Operation] The reducer has a hollow structure, consisting of a driving-side rotating body attached to the main shaft of the motor and a driven-side hollow rotating body fixed to a driven-side member. is rotatably supported on the motor side by a bearing member positioned axially shifted from this. This makes it possible to reduce the overall size of the drive device, including the support member of the hollow reducer, and the wrist part, which is rotatably attached to the robot arm, and the wrist part, which is rotatably attached to the robot arm. A rotatably mounted actuating member, such as a spot welding gun, can be directly driven by a motor attached to one of these members on the driving side, without using a transmission member. Even if the reducer is downsized, the heat generated therein is reliably cooled down by the cooling air generated by the fan provided on the main shaft of the motor.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on an embodiment of the present invention shown in the drawings. 1 and 2 are diagrams showing the entire robot incorporating the wrist drive device of the present invention, and FIG. 3 shows the robot being used to perform spot welding work on various parts in the interior of the vehicle body W. It is a perspective view showing a state.

As shown in the figure, this robot 10 has a swivel base 12 attached to a base 11 so as to be freely rotatable in the direction of a pivot axis S1. The swing arm 14 is attached, and the link 1
A swing arm 16 parallel to this swing arm 14 is connected to the shaft 13 via a shaft 5 . These swing arms 14 and 16 are designed to swing in the direction of the swing axis S2 indicated by the arrow.
An arm 17 is attached to the tip of the arm 6 and is movable up and down in the S3 axis direction by these arms.
A rotary rod 18 that is rotatable in the direction of the S4 axis is attached to the rotary rod 7 . Further, an arm 19 that is rotatable in the S5 axis direction is attached to the tip of the rotating rod 18, and an arm 20 that is rotatable in the S5' axis direction is attached to the tip of this arm 19. It is being A wrist portion 21 that is rotatable in the S6 axis direction is attached to the tip of this arm 20, and this wrist portion 21 is rotatable in the S7 axis direction that is perpendicular to the S6 axis direction. A spot welding gun 22 is attached to this wrist portion 21 so as to be rotatable in the S8 axis direction.

The functions of the S4 and S5 axes, that is, the rotation of the rotary rod 18 and the rotation of the arms 19 and 20, are controlled by the arm 17.
A timing belt 26 is attached to the pulleys attached to the rotation alignment shafts of both arms 19 and 20 in order to transmit the driving force of the motor 25 to the rotation of the arm 20. is being passed over. On the other hand, the function of the S6 axis, that is, the function of rotating the wrist portion 21 in the direction of the arrow S6 axis, is performed by a drive device built into the arm 20. Similarly, the functions of the S7 and S8 axes are achieved by a drive device built into the wrist portion 21. Therefore, the functions of the S6 to S8 axes are directly driven without transmitting power from a drive source built into the robot body.

FIG. 4 is a sectional view showing the internal structure of the arm portion 20 and wrist portion 21, and this figure shows a drive device for rotating the spot welding gun 22 attached to the wrist portion 21 in the S8 axis direction. . The details of this drive device are shown in FIG. 5. As shown in FIG. 5, the servo motor 31 is provided in a housing integrally with the brake part, and a mounting flange 32 is fixed to the housing. A driving side rotating body 34 is attached to the motor main shaft 33 protruding from the tip end side of the motor housing, and this rotating body 34 is located within a hollow driven side rotating body 35 attached to a driven member on the driven side. There is. A flexible cylindrical body 36 is interposed between these rotating bodies 34 and 35, and its rear end is fixed to the mounting flange 32. A hollow speed reducer 37 is constituted by these rotating bodies 34, 35 and the cylinder 36. This reducer 37
An air suction hole 38 is provided in the motor main shaft 33 to cool the
A fan member 3 is formed and provided on the motor main shaft 33.
9, the air sucked in from the air suction hole 38 passes through the motor housing and flows out from the heat radiation hole 40 provided therein. This suppresses a temperature rise within the reducer 37.

In order to rotatably support the hollow driven rotating body 35, a cylindrical member is provided between an inner annular body 41 integral with the hollow driven rotating body 35 and an outer annular body 42 integral with the mounting flange 32. A cross roller bearing 43 is installed outside the body 36. Thereby, the rotation of the motor main shaft 33 can be decelerated to a predetermined low speed and then transmitted to the driven member without increasing the outer diameter of the motor housing itself. In addition, the entire servo motor 31, reducer 37, etc. will be integrated into a unit as shown in FIG.
Maintenance is facilitated by replacing the entire unit. Furthermore, this unit has substantially the same structure for driving the S6, S7, and S8 axes, and the same unit can be attached to any part. In other words, to drive the S6 axis, the motor 31 is attached to the arm 20, which is the drive side member relative to the wrist portion 21.
This is accomplished by fixing the hollow rotating body 35 on the driven side to the wrist portion 21. Similarly, the spot welding gun 22 as an operating member is a driven member with respect to the wrist portion 21, and the motor 3 attached to the wrist portion 21, which is the driving side.
1, by driving a hollow rotating body 35 fixed to the spot welding gun 22. Furthermore, the function of the S7 axis can be obtained in a similar manner. As shown in Figure 4, S
The rotation center axis 45 in the seven-axis direction is out of phase by 90 degrees with respect to the rotation center of the outer rotating body 35, that is, the rotation center of the motor main shaft 33, and is also shifted without intersecting. Therefore, the structure of this part becomes simple and the drive device becomes compact.

0012

As described above, according to the present invention, a robot has a wrist portion which is rotatably attached to an arm, and an operating member such as a spot welding gun which is rotatably attached to this wrist portion. A small drive device consisting of a motor and a hollow speed reducer attached to the drive side of these members can directly rotate and drive these members without using a transmission member, so these members can be driven. The device for this purpose does not become large, and the same number of axes functions as the conventional robot can be obtained using a small robot.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a robot incorporating a multi-axis robot wrist drive device according to an embodiment of the present invention;

[Figure 2]
is a perspective view of FIG. 1,

FIG. 3 is a perspective view showing a state in which the robot shown in FIGS. 1 and 2 is performing welding work on a vehicle body;

[Figure 4]
is a cross-sectional view showing the internal structure of the robot's wrist,

[Figure 5]
is an enlarged view of the drive device shown in FIG.

FIG. 6 is a front view showing a conventional multi-axis robot.

[Explanation of symbols]

20... Robot arm, 21... Wrist part, 22... Spot welding gun, 31... Servo motor, 32... Mounting flange,
33... Motor main shaft, 34... Driving side rotating body, 35... Driven side rotating body, 37... Reducer, 38... Air suction hole, 39... Fan, 40... Heat radiation hole, 43... Bearing.

Claims (1)

[Claims] Claim 1: A robot arm having a wrist portion rotatably attached to the tip of the robot arm, and an actuation member rotatably attached to the wrist portion, the actuator having a plurality of actuation members. In the wrist drive device for a multi-axis robot having a function of the number of axes, a motor is attached to the drive-side member of the arm, the wrist portion, and the actuating member, and a drive-side rotating body is attached to the main shaft of the motor. and the arm;
A speed reducer is formed by the wrist portion and a driven-side hollow rotating body fixed to a driven-side member of the operating member, and a fan is provided on the main shaft of the motor to prevent a rise in temperature of the speed reducer; A wrist drive device for a multi-axis robot, wherein a bearing member that rotatably supports the driven hollow rotary body is installed at a position offset from the driven hollow rotary body in the axial direction.