JPH0957669A - Driving part structure of scalar type robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve controllability and operational performance in a scalar type robot. SOLUTION: A scalar type robot is composed of a main body 1, a horizontal articulated arm 2 composed of first and second arms 3 and 4 and a head assembly 5 installed in a tip part of the arm 2, and the head assembly 5 is installed in a lower end part of an actuating shaft 13 which is installed on the tip of the second arm 4 and can move and rotate in the Z axis direction. A Z axis motor 10 to drive this actuating shaft 13, an R axis motor 11 and a second arm driving motor 9 are mounted on the second arm 4, and the motor 9 is arranged above a second articulated shaft 7, and in an arm extending condition where the first arm 3 and the second arm 4 turn in the same direction, the Z axis motor 10 and the R axis motor 11 are arranged in a position becoming closer to a first articulated shaft 6 than the second articulated shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal joint type of a first arm connected to a main body via an articulation shaft and a second arm connected to a tip of the first arm via an articulation shaft. In a SCARA robot with arms,
The present invention relates to a drive unit structure of a SCARA type robot in which a movable member for attaching a work member and a drive source thereof are integrally provided in a second arm.

[0002]

2. Description of the Related Art Conventionally, a scalar robot in which an arm has a horizontal joint type mechanism is generally known. This SCARA type robot is provided with an arm composed of a plurality of parts connected via a vertical joint shaft and an operation shaft connected to a tip end portion thereof, and is connected to, for example, a main body via a first joint shaft. A first arm and a second arm connected to the tip of the first arm via a second joint shaft constitute a horizontal joint type arm, and the tip of the second arm operates as a movable member. A shaft is provided.

The actuating shaft can move and rotate in the Z-axis direction (vertical direction) with respect to the arm, and is driven by a motor. A head portion including a working member such as a chuck is attached to the operating shaft.

In this type of SCARA robot, if a motor as a drive source for operating each arm is concentrated in the main body, the transmission mechanism for operating the second arm and the operating shaft becomes complicated. A motor for driving two arms and a motor for driving an operating axis are mounted on the second arm, and in many models, the motor for driving the second arm is substantially coaxial with the second joint shaft. The motors for driving the operating shaft are arranged side by side in the space between the motor and the operating shaft.

[0005]

However, in the structure in which the second arm and the motor as the drive source of the actuating shaft are integrally mounted on the second arm as described above, an accessory member having a comparatively heavy weight such as a reduction gear is attached. Since it is required to be mounted on the second arm together, the weight of the second arm inevitably increases, which causes the moment of inertia about the first joint axis when the first arm rotates to control the robot. In addition, the work accuracy is so large that it cannot be ignored.

Therefore, in a robot in which a motor for driving the second arm and the operating shaft is integrally mounted on the second arm, the moment of inertia about the first joint axis is increased when the first arm is driven to rotate. A structure that can be suppressed as much as possible is desired.

The present invention has been made to solve the above problems, and it is possible to suppress the increase of the moment of inertia about the first joint axis of the first arm to improve the controllability and operation performance of the robot. It is an object of the present invention to provide a drive unit structure for a SCARA robot that can be used.

[0008]

According to a first aspect of the present invention, there is provided a drive unit structure for a SCARA type robot, wherein the SCARA type robot is provided with a movable member for attaching a working member to a distal end portion of a horizontal joint type arm. The arm includes a first arm connected to the main body via a first joint shaft and a second arm connected to the tip of the first arm via a second joint shaft. The movable member, the drive source for driving the movable member, and the drive transmission means are mounted, and in the arm extended state in which the first and second arms face in the same direction, the first joint shaft rather than the second joint shaft. The drive source is arranged at a position close to the.

According to this structure, as compared with the conventional SCARA robot of this type in which the driving source for driving the movable member is arranged side by side between the first joint shaft and the movable member, the position of the center of gravity of the second arm is the second. The position is close to one joint axis. Therefore, it is possible to effectively reduce the moment of inertia about the first joint axis when the first arm turns while mounting the drive source for driving the movable member integrally on the second arm.

According to a second aspect of the present invention, there is provided a drive unit structure for a SCARA type robot according to the first aspect of the present invention.
A drive source for driving the arm is mounted on the second arm, and the drive source is arranged substantially coaxially with the second joint shaft, and the movable member and the drive source are in the second state when the arm is extended. It is offset with respect to a line segment connecting the center of the joint axis and the center of the first joint axis.

According to this structure, since the drive source for driving the second arm does not exist between the movable member and the drive source, the drive transmission mechanism is not complicated.

[0012]

Embodiments of the present invention will be described with reference to the drawings.

1 and 2 schematically show the entire SCARA robot to which the drive unit structure of the present invention is applied. The SCARA type robot shown in this figure includes a main body 1, a horizontal joint type arm 2, and a head assembly 5 attached to the tip of the arm 2. Arm 2 above
Is composed of a first arm 3 and a second arm 4, the base end portion of the first arm 3 is rotatably connected to the main body 1 via a vertical first joint shaft 6, and the first arm 3 A second arm 4 is rotatably connected to the tip of the third arm 3 via a second joint shaft 7 (see FIG. 2).

A motor 8 for driving the first arm is provided inside the main body 1, and an output shaft of the motor 8 is connected to the first joint shaft 6 via a speed reducer.

The second arm 4 is equipped with a motor 9 for driving the second arm. The motor 9 is arranged coaxially with the second joint shaft 7, and its output shaft is connected via a speed reducer. And is connected to the second joint shaft 7.

Further, the second arm 4 is provided with a drive portion for operating the head assembly 5. The drive unit includes an operating shaft 13 (movable member) provided at the tip of the second arm 4, a mechanism for moving and rotating the operating shaft 13 in the Z-axis direction (vertical direction), and a Z as a drive source. It has an axial motor 10 and an R-axis motor 11, and the head assembly 5 is mounted on the tip (lower end) of the operating shaft 13.

Specifically, the operating shaft 13 constituted by the spline shaft of the ball spline 12 is arranged at the tip of the second arm 4 in the Z-axis direction, and the outer cylinder portion 14 of the ball spline 12 is the second arm. 4 is supported via a bearing 15 so that the working shaft 13 is movable in the Z-axis direction and rotatable with respect to the second arm 4, and the tip of the working shaft 13 is It projects below the second arm 4.

A ball screw shaft 18 disposed in the Z-axis direction and rotatably supported by the second arm 4 on the side of the operating shaft 13 and a nut member screwed to the ball screw shaft 18. A ball screw mechanism 17 composed of 19 is provided, an operating shaft holder 20 is connected to the nut member 19, and the operating shaft 13 is rotatably held by the operating shaft holder 20 via a bearing 20.

The ball screw shaft 18 has a pulley 22 attached to the lower end thereof, a pulley 23 attached to the output shaft of the Z-axis motor 10 and a timing belt 24 wound around the pulleys 23, Z The shaft motor 10 is driven to rotate. When the ball screw shaft 18 is rotated by being driven by the Z-axis motor 10, the nut member 19 moves up and down, and the operating shaft 13 moves up and down accordingly. Further, a pulley 25 is coupled to the upper end of the outer cylinder portion 14, and the pulley 25 and the R
The actuating shaft 13 is rotationally driven by the R-axis motor 11 by the timing belt 27 being stretched around the pulley 26 connected to the shaft motor 11 via the speed reducer 11a. That is, these pulleys 22, 23, 2
5, 26 and the timing belts 24, 27 constitute drive transmission means.

As shown in FIGS. 2 and 3, the drive section for operating the head assembly 5 includes an operating shaft 13, a ball screw shaft 18, a Z-axis motor 10 and an R-axis motor 11 as a second arm 4. Are arranged in a row at, and
In the illustrated arm extension state (the state in which the first arm 3 and the second arm 4 are oriented in the same direction), the Z-axis motor 10 and the R-axis motor 11 of the drive section have the first joint shaft 6 rather than the second joint shaft 7. It is placed so that it is close to Further, in the example shown in the figure, the first joint shaft 6 is
Is arranged laterally (downward in FIG. 2) with respect to the line segment connecting the second joint shaft 7.

That is, the second arm 4 is provided with a laterally projecting portion 4b on the base end side of the arm main portion 4a and extends from the base end side of the arm main portion 4a in the direction opposite to the distal end side. The protruding portion 4b is provided with the extending portion 4c.
A second joint shaft 7 is provided at the arm main portion 4a and the extending portion 4c are offset from the second joint shaft 7. Then, the Z-axis motor 10 and the R are provided on the extending portion 4c.
The shaft motor 11 is installed, and the arm main portion 4a and the extension portion 4 are provided.
The drive transmission means such as the belts 24 and 27 are arranged in a range extending over c. In this way, the Z-axis motor 1
By arranging the 0 and R axis motors 11 at positions closer to the first joint shaft 6 than the motor 9, the center of gravity of the second arm 4 is set to a position closer to the first joint shaft 6, while the entire drive section is set. By offsetting with respect to the motor 9, there is a second gap between the ball spline 12 and the like and the Z axis and R axis motors 10 and 11.
The arm driving motor 9 does not interfere with the drive transmission mechanism.

A substantially triangular portion 4d is formed on the second arm 4 between the projecting portion 4b and the extending portion 4c, and the turning angle of the second arm 4 is detected at this portion. A turning angle sensor is installed.

Although the head assembly 5 is not shown in detail, for example, an air-operated chuck is provided at the tip, and the head assembly 5 is configured to grip a work by this chuck.

In the SCARA type robot constructed as described above, the first and second arms 3 and 4 are operated by driving the motors 8 and 9 for driving the first arm and the second arm. For example, the tip portion of the second arm 4 is reciprocated between the work loading unit and the work loading unit. The head assembly 5 is actuated by the drive of the Z-axis and R-axis motors 10 and 11 in the work loading part and the unloading part, and the chuck is operated in response to the suction and discharge of the air pressure, so that the loading part is loaded. The work carried in is picked up and transferred to the carry-out section.

In the operation of such a SCARA type robot, the Z-axis and R-axis motors 10 and 11 for operating the head assembly 5 are arranged closer to the first joint axis than the second joint axis 7. According to the scalar type robot of the above embodiment, the conventional scalar type robot of this type,
That is, the Z-axis motor and R for operating the head assembly
The center of gravity of the second arm 4 is closer to the first joint shaft 6 as compared with the SCARA type robot in which the shaft motor is arranged closer to the tip end side of the second arm than the second joint shaft, and the turning operation of the first arm 3 is correspondingly performed. The moment of inertia about the first joint axis is reduced.

Therefore, the reaction at the time of operation switching such as the turning start, the turning stop, or the turning direction switching of the first arm 3 is good. Therefore, according to the scalar type robot of the above-described embodiment, compared with the conventional scalar type robot of this type,
The controllability and operation performance of the arm 3 can be improved.

When the Z-axis and R-axis motors 10 and 11 are arranged closer to the first joint shaft than the second joint shaft 7 as described above, the Z-axis and R-axis motors 10 and 11 are the first. The moment of inertia around the first joint axis is reduced as it approaches the joint axis 6, which is advantageous, but as the distance from the second joint axis 7 increases (the extending portion 4c extends), the second joint axis during the second arm turning drive. The moment of inertia around 7 will increase. Therefore, it is desirable that the positions of the Z-axis and R-axis motors 10 and 11 are set so that the moment of inertia about the first joint axis can be sufficiently reduced within a range that does not significantly increase the moment of inertia about the second joint axis. .

The above-described SCARA robot of the above embodiment is an example of a SCARA robot to which an example of the drive unit structure of the present invention is applied, and its concrete configuration is as follows.
Modifications can be made as appropriate without departing from the scope of the present invention.

For example, in the above-described embodiment, the arrangement of the drive unit for operating the head assembly 5 is offset with respect to the motor 9 for driving the second arm, but it is not always necessary to adopt such a layout. Alternatively, as shown in FIG. 4, the drive unit may be provided without being offset with respect to the motor 9.

In this case, the ball splines 12 and Z
Although the motor 9 for driving the second arm is interposed between the shaft and the R-axis motors 10 and 11, there is a vertical space in the connecting portion between the output shaft of the motor 9 and the second joint shaft 7, etc. In such a case, the timing belts 24, 27 for transmitting the rotational force are utilized by utilizing the space as shown in FIG.
Should be passed over. If there is no such space, the diameters of the pulleys 22, 23, 25 and 26 may be set large and the motor 9 may be arranged on the inner peripheral portion of the timing belt 24. However, as described above, the ball spline 12 and the like and the Z-axis and R-axis motors 10 and 11 are
In the layout in which the motor 9 is interposed between and, the timing belts 24 and 27 are difficult to be replaced, and the maintainability is not good. Therefore, it is preferable to drive the head assembly 5 as in the above embodiment. Is preferably offset with respect to the motor 9 for driving the second arm.

In the above embodiment, the motor 9 for driving the second arm is mounted on the second arm 4, but the motor 9 may be mounted on the first arm 3, for example. That is, the motor 9 may be mounted on the lower surface of the tip of the first arm 3. According to this configuration, Z axis, R
Even if the shaft motors 10 and 11 are arranged closer to the first joint shaft 6 than the second joint shaft 7, the motor 9 does not exist in the second arm 4, so that a drive unit for operating the head assembly 5 is provided as a second drive unit. It is not necessary to offset the motor 9 for driving the arm.

[0032]

As described above, according to the present invention, the first arm connected to the main body through the first joint shaft and the first arm.
A SCARA type robot having a horizontal joint type arm comprising a second arm which is connected via a second joint shaft at the tip of the arm, and a movable member for attaching a working member to the second arm, and a movable member. While the drive source for driving and the drive transmission means are mounted, the drive source for driving the movable member is arranged at a position closer to the first joint shaft than the second joint shaft in the arm extended state. The center of gravity position of the second arm is set to
Since it is arranged close to the joint axis, it is possible to effectively reduce the moment of inertia about the first joint axis when the first arm is driven to rotate. Therefore, as compared with the conventional SCARA robot of this type in which the drive source for driving the movable member is arranged side by side between the second joint shaft and the movable member, the reaction at the time of switching the operation of the first arm is better, and the SCARA robot. The controllability and operating performance of can be improved.

In particular, when the motor for driving the second arm is mounted on the second arm and is arranged substantially coaxially with the second joint shaft, the movable member and its driving source are arranged as follows.
By offsetting the line segment connecting the center of the second joint axis and the center of the first joint axis in the arm extended state, the motor for driving the second arm is interposed between the movable member and its drive source. Therefore, the drive transmission mechanism is not complicated.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a SCARA type robot to which an example of a drive unit structure according to the present invention is applied.

FIG. 2 is a schematic plan view showing a SCARA type robot to which an example of a driving unit structure according to the present invention is applied.

FIG. 3 is a schematic plan view of a second arm showing a mechanism portion for transmitting a rotational force to an operating shaft.

FIG. 4 is a schematic plan view of a second arm showing another example of the drive unit structure according to the present invention.

[Explanation of symbols]

 1 Main Body 2 Arm 3 First Arm 4 Second Arm 5 Head Assembly 6 First Joint Axis 7 Second Joint Axis 8, 9 Motor 10 Z Axis Motor 11 R Axis Motor 12 Ball Spline 13 Working Axis 17 Ball Screw Mechanism

Claims (2)

[Claims] 1. A SCARA robot in which a movable member for attaching a working member is provided at the tip of a horizontal joint type arm, wherein the arm is connected to a main body via a first joint shaft. The arm includes an arm and a second arm connected to the tip of the first arm via a second joint shaft. The second arm has the movable member, a drive source for driving the movable member, and drive transmission means. Is installed and the first
And a drive unit structure for a SCARA robot, wherein the drive source is arranged at a position closer to the first joint axis than the second joint axis in the arm extended state in which the second arm is oriented in the same direction. 2. A drive source for driving the second arm is mounted on a second arm, and the drive source is arranged substantially coaxially with a second joint shaft, wherein the movable member and the drive source. 2. The drive unit structure for a SCARA robot according to claim 1, wherein the arm is offset with respect to a line segment connecting the center of the second joint axis and the center of the first joint axis in the arm extended state.