JPS61164786A - Rotary direct-acting mechanism of industrial robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an industrial robot, and more specifically, the present invention relates to an industrial robot, and more specifically, a movable body that supports a robot arm is rotated relative to a base, and a movable body that supports a robot arm is rotated in a straight line along the axis of rotation. This invention relates to a rotational and linear motion mechanism for a cylindrical coordinate robot for movement.

[Prior art and problems]

In general, a cylindrical coordinate robot includes a rotational translation device for rotating a movable body supporting a robot arm with respect to a base and linearly moving the movable body along a rotation center axis.

FIGS. 3 and 4 each schematically show the configuration of a conventional rotary-linear motion mechanism in a cylindrical coordinate robot. In the robot shown in FIG. 3, an intermediate support 2 is rotatably supported on a base 1, a movable base 3 is supported on the intermediate support 2 so as to be linearly movable along its rotation center axis, A rotary drive device 4 for rotationally driving the intermediate support 2 is supported by the fixed base 1, and a linear drive device 5 for linearly driving the movable base 3 is supported by the intermediate support 2. In the case of such a structure, since the weight of the linear drive device 5 is applied to the rotary drive device 4 as a load, there is a drawback that the load on the rotary drive device 4 increases.

In the robot shown in FIG. 4, an intermediate support 2 is provided so as to be linearly movable with respect to a base 1, and a movable body 3 is provided rotatably with respect to the intermediate support 2, and drives the intermediate support 2 linearly. A linear drive device 5 for rotationally driving the movable body 3 is supported on the base 1, and a rotational drive device 4 for rotationally driving the movable body 3.
is supported by the intermediate support 2. In the case of such a structure, since the weight of the rotary drive device 4 is added to the linear drive device 5 as a load, there is a drawback that the load on the linear drive device 5 increases.

Therefore, there is a need for a rotary and linear motion mechanism that can minimize the load applied to a rotary drive device or a linear drive device, and that can simplify the load support structure and make the entire device more compact.

[Means and operations for solving the problems] As a first means for solving the above problems, the present invention rotates a movable body that supports a robot arm with respect to a base, and In a rotary and linear motion mechanism for an industrial robot that moves linearly along an axis, a hollow rotary shaft is supported on the base so as to be rotatable around the axis, and a first motor for rotationally driving the movable body is mounted on the base. The ball screw shaft is attached to a base and its output shaft is connected to the hollow rotating shaft, a Bono P screw shaft is provided coaxially within the hollow rotating shaft, the ball screw shaft is rotatably supported on the base, and the movable body A second motor for linearly driving is attached to the base and its output shaft is connected to the ball screw shaft, and a hollow movable shaft fixed to the movable body is slidable within the hollow rotation shaft. There is provided a rotary and linear motion mechanism for an industrial robot, characterized in that a ball screw nut is fixedly inserted inside the movable shaft and screwed to the ball screw shaft, the ball screw nut being inserted so as not to be relatively rotatable.

According to the above means, since the first motor for rotationally driving the movable body and the second motor for linearly driving the movable body are each supported by the base, the weight of the rotational drive system is reduced by the weight of the linear drive motor. The weight of the linear drive system does not act as a load on the rotary drive motor. Therefore, the motor can be made smaller.

In addition, the ball screw shaft for linear feed is located at the center of rotation of the movable body and coaxial with the hollow rotating shaft for transmitting rotational power, which simplifies the load support structure and allows for rotational and linear motion mechanisms. This allows the whole to be made more compact.

In addition, as a second means to solve the above problems,
The present invention further provides a detector for detecting the amount of rotation of the hollow rotation shaft in addition to the above-mentioned means, and a straight line of the movable shaft as the hollow rotation shaft rotates based on the detected value of the detector. The present invention provides a rotary and linear motion mechanism for an industrial robot, comprising: a control unit that applies an output signal to the second motor to control the rotation angle of the second motor so as to correct the motion.

According to this second means, the linear motion of the movable shaft accompanying the rotation of the hollow rotary shaft is corrected by controlling the rotation angle of the second motor for linear drive. It becomes possible to prevent the body from moving in a straight line, or to move it in a straight line regardless of the rotation of the movable body.

These and other features and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate embodiments of the invention.

〔Example〕

1 and 2 show one embodiment of the present invention.

Referring to these figures, the rotary and linear motion mechanism of the industrial robot includes a base 11. The base 11 is usually fixed to the installation surface, but may be provided so as to be movable along the installation surface. A movable body 12 supporting a robot arm is rotatable relative to the base 11 and linearly movable along its rotation center axis.

A hollow rotating shaft 13 is supported on the base 11 via a bearing 14 so as to be rotatable around its axis. The first motor 15 for rotationally driving the movable body 12 is connected to the base 1.
It is attached to 1. The output shaft of the first motor 15 is directly connected to a reducer 16, and the output shaft of the reducer 16 is connected to the hollow rotating shaft 13 via a pair of gears 17 and 18.

A ball screw shaft 19 for linear feeding is provided coaxially within the hollow rotation shaft 13. The ball screw shaft 19 is rotatably supported by the base 11 via a bearing 20.

A second motor 21 for linearly driving the movable body 12 is attached to the base 11. Timing gears 23° 24 are fixed to the output shaft 22 of the second motor 21 and the ball screw shaft 19, respectively.
24 are connected by a timing belt 25. The hollow rotating shaft 13 is provided with an opening 26 through which the timing belt 25 passes.

A hollow movable shaft 27 is fixed to the movable body 12. As can be seen from FIG. 2, the movable shaft 27 is the hollow rotation shaft 13.
It is inserted into the interior via a pair of bearings 28 in a slidable but non-rotatable manner.

A ball screw nut 29 that is screwed onto the ball screw shaft 19 is fixed inside the movable shaft 27.

Each of the first motor 15 and the second motor 21 is equipped with a rotation angle detector 30,31.

Detection signals from the rotation angle detectors 30 and 31 are sent to the control section 32. The control unit 32 controls the first motor 15 and the second motor 21 according to a program based on the detected value of the rotation detector 30.31.

The rotation of the output shaft 22 of the second motor 21 is caused by the ball screw shaft 19.
transmitted to. When the ball screw shaft 19 rotates, the ball screw NAND 29 does not rotate (moves linearly together with the movable shaft 27, and as a result, the movable body 12 moves linearly).

On the other hand, the rotation of the output shaft of the first motor 15 is reduced by the reducer 16, and the rotation of the output shaft of the first motor 15 is reduced by the gear 17.18.
transmitted to. The rotation of the hollow rotation shaft 13 is directly transmitted to the movable shaft 27, thereby causing the movable body 12 to rotate. However, when the movable shaft 27 rotates, the ball screw nut 29 also rotates, so if the ball screw shaft 19 is fixed so that it cannot rotate, the ball screw nut 29 will rotate along the axis of the ball screw shaft 19. It will move in the direction. Therefore, the control unit 32 controls the second motor I5 to correct the linear movement of the movable shaft 19 due to the rotation of the hollow rotation shaft 13, based on the detected value of the rotation angle detector 30 provided in the first motor I5. The second motor 21 is configured to apply an output signal that controls the rotation angle of the motor 21 . As a method for correcting the amount of linear movement, the ball screw shaft 19 may be rotated in the same direction by an angle equal to the rotation angle of the hollow rotation shaft 13. Alternatively, the ball screw shaft 19 may be rotated in a direction that lowers the ball screw throat 29 by an amount corresponding to the amount by which the ball screw nut 29 is raised.

In the rotary and linear motion mechanism having the above configuration, the first motor 15 for rotationally driving the movable body 12 and the second motor 21 for linearly driving the movable body 12 are each supported by the base 11. The weight of the rotational drive system does not act as a load on the linear drive motor 21. Furthermore, the weight of the linear drive system does not act as a load on the rotary drive motor 15. Therefore, motor 15
゜21 can be made smaller.

In addition, the ball screw shaft 19 for linear feeding is connected to the movable body 12.
Since it is located at the center of rotation of the ball screw shaft 19 and is provided coaxially with the hollow rotating shaft 13 for transmitting rotational power, only the axial load acts on the ball screw shaft 19. Therefore, the load supporting structure is simplified, and the entire rotary and linear motion mechanism can be made compact.

Furthermore, in the rotary and linear motion mechanism configured as described above, the linear motion of the movable shaft 19 accompanying the rotation of the hollow rotary shaft 13 is corrected by controlling the rotation angle of the second motor 21 for linear drive. The movable body 12 can be prevented from moving linearly during the rotation of the movable body 12. Moreover, the movable body 12 can also be moved linearly regardless of its rotation.

Although one embodiment has been described above, the present invention is not limited to the embodiment described above, and various changes can be made to its constituent elements within the scope of the invention described in the claims. . For example, the gear 24 attached to the ball screw shaft 19 may be positioned below the gear 17.18 shown in FIG.

Moreover, various obvious means can be used for transmitting the rotation of the motor 15, 21 to the hollow rotating shaft 13 or the ball screw shaft 19.

〔Effect of the invention〕

As is clear from the above description, according to the first means of the present invention, the first motor for rotationally driving the movable body and the second motor for linearly driving the movable body are each supported by the base. Therefore, the weight of the rotational drive system does not act as a load on the linear drive motor, and the weight of the linear drive system does not act as a load on the rotational drive motor. Therefore, the motor can be made smaller. In addition, the ball screw shaft for linear feed is located at the center of rotation of the movable body and coaxial with the hollow rotating shaft for transmitting rotational power, which simplifies the load support structure and allows for rotational and linear motion mechanisms. This allows the whole to be made more compact.

Therefore, it is possible to provide a rotary and linear motion mechanism for an industrial robot that is small in size and has a simplified structure.

Furthermore, according to the second means of the present invention, the linear motion of the movable shaft accompanying the rotation of the hollow rotary shaft is corrected by controlling the rotation angle of the second motor for linear drive, so that the rotation of the movable body It becomes possible to prevent the movable body from moving in a straight line while moving the movable body, or to move the movable body in a straight line regardless of the rotation of the movable body.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of a rotary and linear motion mechanism of an industrial robot showing an embodiment of the present invention, and Fig. 2 is a longitudinal cross-sectional view of the rotary and linear motion mechanism shown in Fig. 1 taken along the line ■-■ in Fig. 1. The sectional view, FIG. 3, and FIG. 4 are schematic configuration diagrams showing a rotary and linear motion mechanism of a conventional industrial robot, respectively. 11...Base, 12...Movable body, 13...
hollow rotating shaft, 15... first motor, 19... ball screw shaft, 21... second motor, 27... movable shaft, 2
9...Ball screw nut, 30...Rotation angle detector,
32...control unit.

Claims (1)

[Scope of Claims] 1. In a rotary linear motion mechanism for an industrial robot that rotates a movable body supporting a robot arm relative to a base and moves linearly along the rotation center axis, the base includes a hollow rotation. A movable shaft is rotatably supported around its axis, a first motor for rotationally driving the movable body is attached to the base, and its output shaft is connected to the hollow rotary shaft, a ball screw shaft is provided coaxially therein, and the ball screw shaft is rotatably supported on the base;
A second motor for linearly driving the movable body is attached to the base and its output shaft is connected to the ball screw shaft, and a hollow movable shaft fixed to the movable body is slid into the hollow rotation shaft. 1. A rotary and linear motion mechanism for an industrial robot, characterized in that a ball screw nut is fixedly inserted into the movable shaft so as to be relatively unrotatable, and is screwed onto the ball screw shaft inside the movable shaft. 2. In a rotary and linear motion mechanism for an industrial robot in which a movable body supporting a robot arm is rotated with respect to a base and linearly moved along its rotation center axis, a hollow rotation shaft is attached to the base around the axis. A first motor for rotationally driving the movable body is attached to the base, an output shaft thereof is connected to the hollow rotation shaft, and a ball screw shaft is installed in the hollow rotation shaft. coaxially provided and rotatably supporting the ball screw shaft on the base;
A second motor for linearly driving the movable body is attached to the base and its output shaft is connected to the ball screw shaft, and a hollow movable shaft fixed to the movable body is slid into the hollow rotation shaft. a detector for detecting the amount of rotation of the hollow rotating shaft; and, based on the detected value of the detector, an output signal is sent to the second motor to control the rotation angle of the second motor so as to correct the linear motion of the movable shaft accompanying the rotation of the hollow rotation shaft. A rotary and linear motion mechanism for an industrial robot, characterized by comprising a control section for applying voltage.