JPH0966479A - Arm structure of scalar type robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the degree of freedom of a drive section layout in a second arm for reducing the moment of inertia of each arm in turning drive while compacting the arm. SOLUTION: A scalar type robot is composed of a horizontal articulation type arm 2 consisting of first and second arms 3, 4 and an operating shaft 13 attached to the arm 2. The operating shaft 13 is attached to the tip of the second arm 4 movably in the direction of the axis Z and rotatably. The second arm 4 is provided with a main arm part 4a, projecting part 4b and extending portion 4c. The projecting part 4b is provided with a second articulated shaft 7, so that the main arm part 4a and extending portion 4c are offset to the second articulated shaft 7. A second arm driving motor 9 is disposed in the projecting part 4b, the operating shaft 13 in the main arm part 4a, a Z axis motor 10 and R axis motor 11 for driving the operating shaft in the extending portion 4c respectively. A drive transmitting mechanism such as a belt is disposed in a range covering the main arm part 4a and extending portion 4c.

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 robot in which a movable member for attaching a working 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 the tip of the arm. For example, as shown in FIG.
A first arm 52 connected to 0 via a first joint shaft 51.
And a second arm 54 connected to the end of the first arm 52 via a second joint shaft 53, a horizontal joint type arm is formed, and an operating shaft as a movable member is formed at the end of the second arm 54. 55 is provided.

The operating shaft 55 has a Z-axis with respect to the second arm 54.
It can be moved and rotated in the axial direction (vertical direction), and is driven by a motor. A head portion including a working member such as a chuck member is attached to the operating shaft 55.

In this type of SCARA type robot, when a motor for actuating an arm or the like is concentrated on the main body, a transmission mechanism for actuating the second arm 54 and the actuating shaft 55 becomes complicated. As described above, the motor 57 for driving the second arm, the Z-axis motor 58 and the R-axis motor 59 for driving the operating axis are mounted on the second arm 54, and in many models, the second arm driving is performed. A motor 57 for driving is disposed substantially coaxially with the second joint shaft 53 at the base end portion of the second arm 54, and motors 58, 59 for driving the operating shaft are provided in a space between the motor 57 and the operating shaft 55. I try to place them side by side.

[0005]

However, as described above, the motor 5 as the drive source for the second arm 54 and the actuating shaft 55 is as described above.
In the structure in which 7, 58 and 59 are integrally mounted on the second arm 54, it is necessary to mount a relatively heavy accessory member such as a speed reducer together on the second arm 54, and thus it is inevitable that The weight of the second arm 54 increases, which causes a situation in which the moment of inertia about the first joint axis when the first arm is driven to rotate becomes so large that controllability and operating performance cannot be ignored. Also, the second arm 5
Also in No. 4, since the operating shaft driving motors 58 and 59 are arranged side by side between the second arm driving motor 57 and the operating shaft 55, the moment of inertia about the second joint axis tends to increase. .

Therefore, the motors 58 and 59 in the second arm 54 may be arranged on the base end side of the second arm so that the moment of inertia about the first and second joint axes during driving can be reduced. Desirably, the conventional second arm 54
In the above structure, since the base end side of the second arm is connected to the first arm via the second joint shaft and the motor 57 for driving the second arm is arranged in this portion, the moment of inertia is sufficiently small. It is structurally difficult to adopt such a layout of the motors 58 and 59, and if a motor arrangement that can reduce the moment of inertia is adopted, the mechanism portion for driving the operating shaft becomes complicated. Accompanying
Actual implementation is difficult.

Further, in the conventional structure of the second arm 54,
Since the motors 57, 58, and 59 are arranged side by side on the arm, it is difficult to shorten the entire length (length in the longitudinal direction) of the second arm to make the robot compact.

The present invention has been made to solve the above-mentioned problems, and increases the degree of freedom in the layout of the drive section in the second arm to reduce the moment of inertia of each arm during swivel drive, and the compact arm. It is an object of the present invention to provide an arm structure for a SCARA robot that can be realized.

[0009]

According to the arm structure of a SCARA type robot of the present invention, a first arm connected to a main body through a first joint shaft and a second joint shaft at the tip of the first arm. A horizontal arm including a movable member for attaching a working member to the second arm, and a motor for driving the second arm arranged on the second joint shaft. In the joint type SCARA robot, the second arm has an arm body and a protruding portion protruding from one side portion in the axial direction thereof, and the protruding portion is connected to the first arm via a second joint shaft. As a result, the arm body is configured to be offset with respect to the line segment connecting the center of the second joint axis and the center of the first joint axis in the arm extension state in which both arms face in the same direction, and With the movable member on the main body A driving source for driving the movable member, is made of a drive transmission mechanism.

According to this structure, since the movable member, the drive source for driving the movable member, and the drive transmission mechanism are mounted on the arm body offset from the second joint shaft, the layout of these members for driving the second arm is large. Motor does not get in the way. Therefore, with respect to the layout of the drive source for driving the movable member, it is possible to adopt a layout in which the moment of inertia can be made smaller without the adverse effect of complicating the drive transmission mechanism.

[0011]

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

1 to 3 schematically show the entire SCARA type robot to which the arm 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. The arm 2 is
It comprises a first arm 3 and a second arm 4, and the first arm 3
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 second arm 4 is connected to the tip end portion of the first arm 3 via a second joint shaft 7. It is movably connected.

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

More 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.

As shown in FIGS. 2 and 4, the ball screw shaft 18 has a pulley 22 attached to its lower end,
Via a pulley 23 mounted on the output shaft of the Z-axis motor 10 and a timing belt 24 wound around them, 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.

A pulley 25 is connected to the upper end of the outer cylinder portion 14, and the R-axis motor 11 and the speed reducer 11a are connected to the pulley 25.
A timing belt 27 is stretched over a pulley 26 and a pulley 25 which are connected to each other via a pulley 26, so that the operating shaft 13 is driven to rotate by the R-axis motor 11. That is, the pulleys 22, 23, 25, 26 and the timing belts 24, 27 constitute a drive transmission mechanism.

The operating shaft 13, the ball screw shaft 18, the Z-axis motor 10 and the R-axis motor 11 are arranged in a line in the second arm 4, and are in an arm extended state (first position) as shown in FIGS. 3 and 4. In a state where the arm 3 and the second arm 4 are oriented in the same direction), they are offset laterally (downward in FIG. 3) with respect to the line segment connecting the first joint shaft 6 and the second joint shaft 7, and The Z-axis motor 10 and the R-axis motor 11 of the drive unit are arranged so as to be closer to the first joint shaft 6 than 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 mechanisms such as the belts 24 and 27 are arranged in a range extending over c. That is, the arm body of the second arm 4 is constituted by the arm main portion 4a and the extending portion 4c.

In this way, by disposing the Z-axis motor 10 and the R-axis motor 11 closer to the first joint shaft 6 than the motor 9, the center of gravity of the second arm 4 is set to the first joint shaft 6. The motor 9 for driving the second arm is interposed between the ball spline 12 and the like and the Z-axis and R-axis motors 10 and 11 by setting the positions close to each other and offsetting the entire drive unit with respect to the motor 9. Then, it will not be an obstacle to the drive transmission mechanism.

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 second arm 4 is provided with the second joint shaft 7 on the projecting portion 4b protruding from one side of the arm body, so that the arm body becomes the second arm. Since the structure is offset with respect to the joint shaft 7, the interference between the motor 9 for driving the second arm provided on the second joint shaft 7, the motors 10 and 11 provided on the arm body, and the drive transmission mechanism. While avoiding this, the degree of freedom in layout of the motors 10 and 11 on the arm main body is increased, and a layout advantageous for reducing the moment of inertia can be obtained. In particular, Z-axis and R-axis motors 10 for operating the head assembly 5,
According to the scalar type robot of the above embodiment in which 11 is arranged closer to the first joint axis 6 than the second joint axis 7, the conventional scalar type robot of this type, that is, the Z-axis motor for operating the head assembly and The center of gravity of the second arm 4 is closer to the first joint axis 6 than in the SCARA robot in which the R-axis motor is arranged closer to the tip end side of the second arm than the second joint axis, and the swivel motion of the first arm 3 is correspondingly increased. The moment of inertia around the first joint axis becomes small.

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, the controllability and operation performance of the first arm 3 can be improved.

Also as described above, the arm main body of the second arm 4 is offset with respect to the second joint shaft 7 as described above, and the arm main portion 4a and the extending portion 4c have the Z axis,
Since the drive unit for operating the head assembly including the R-axis motors 10 and 11 is arranged, the head assembly 5
It can be easily achieved without any adverse effect such as complicating the structure of the driving unit.

That is, the structure in which the Z-axis and R-axis motors for operating the head assembly 5 are arranged at a position closer to the first joint axis than the second joint axis has a structure in which the first arm and the second arm are in an extended state. It is possible to achieve even in the conventional arm structure in which is linearly arranged. But,
In this case, since the motor for driving the second arm is interposed between the Z-axis and R-axis motors 10 and 11 and the operating shaft, for example, a mechanism for drive transmission that bypasses the motor is provided. It is required to be configured, the structure may be complicated, or the maintainability may be impaired due to this.

On the other hand, in the robot of the above-described embodiment, the drive unit for operating the head assembly including the R-axis motors 10 and 11 is offset with respect to the second joint shaft 7 as described above to drive the second arm. Since the motor 9 is not interposed between the operating shaft 13 and the Z-axis and R-axis motors 10 and 11, the layout of the drive unit can be freely set to obtain the above-mentioned operational effects, but the drive transmission There is no adverse effect such as complicating the mechanism for this.

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, the Z-axis and R-axis motors 10 and 1 are
It is desirable that the position 1 is such that the moment of inertia about the first joint axis can be sufficiently reduced within a range in which the moment of inertia about the second joint axis is not significantly increased.

As an example of the structure advantageous for reducing the moment of inertia about the second joint axis, the structure of the second arm 4 as shown in FIG. 5 can be considered.

In this structure, the extension portion 4 is formed on the second arm 4.
c is not provided, and the Z-axis and R-axis motors 10 and 11 are arranged at the base end portion of the arm main portion 4a, that is, on the side of the motor 9 for driving the second arm.

In such an arm structure, since the Z-axis and R-axis motors 10 and 11 are collectively arranged around the second joint shaft 7, the moment of inertia about the second joint shaft can be further reduced. In addition, as compared with the conventional arm structure in which the Z-axis motor and R-axis motor for operating the head assembly are arranged side by side on the second arm tip side with respect to the second joint shaft, the Z-axis and R-axis motors 10 and 11 are the first Since it is arranged close to the joint shaft 6, the moment of inertia about the first joint shaft can be sufficiently reduced as compared with the related art. Moreover, according to this arm structure, the Z is provided to the side of the motor 9 for driving the second arm.
Since the shaft and R-axis motors 10 and 11 are arranged side by side, there is also an advantage that the total length of the second arm can be shortened and a compact robot can be configured as compared with the conventional arm structure.

The scalar type robot of the above-described embodiment is an example of a scalar type robot to which an example of the arm structure of the present invention is applied, and its specific configuration is as follows.
Modifications can be made as appropriate without departing from the scope of the present invention.
For example, in the SCARA robot of the above embodiment, the operating shaft 13 is provided as a movable member, and the operating shaft 13 is operated by the Z-axis and R-axis motors 10 and 11 via the belt transmission mechanism. However, operating the operating shaft 13 via a shaft drive mechanism or a gear transmission mechanism,
Alternatively, the air cylinder may be configured to operate as a drive source.

[0036]

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 second arm connected to the tip of the arm via a second joint shaft, a movable member for attaching a working member to the second arm, and a second arm arranged on the second joint shaft. In a SCARA robot equipped with a drive motor,
A movable member, a drive source for driving the movable member, and a drive transmission mechanism are arranged on an arm body that is offset with respect to a line segment that connects the center of the second joint axis and the center of the first joint axis. Since the arm drive motor is kept out of the way, the layout of the drive source etc. for driving the movable member that can reduce the moment of inertia of the drive without complicating the structure of the drive transmission mechanism Can be adopted more freely.

[Brief description of drawings]

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

FIG. 2 is a schematic sectional view (side view) showing a SCARA type robot to which an example of the arm structure according to the present invention is applied.

FIG. 3 is a schematic plan view showing a SCARA type robot to which an example of the arm structure according to the present invention is applied.

FIG. 4 is a schematic plan view of a second arm showing a mechanism portion for transmitting a rotational force to an operating shaft.

FIG. 5 is a schematic plan view of a second arm showing another example of the arm structure according to the present invention.

FIG. 6 is a schematic plan view showing an example of a conventional SCARA robot.

[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 (1)

[Claims] 1. A first arm connected to a main body via a first joint shaft, and a second arm connected to a tip end of the first arm via a second joint shaft. In a horizontal joint type SCARA robot including a movable member for attaching a working member to an arm and a motor for driving a second arm arranged on the second joint axis, the second arm is an arm. It has a main body and a projecting portion projecting from one side portion in the axial direction thereof, and the projecting portion is the first through the second joint shaft.
By being connected to the arms, the arm main body is configured to offset with respect to a line segment connecting the center of the second joint axis and the center of the first joint axis in an arm extended state in which both arms face in the same direction. At the same time, the arm structure of the SCARA robot is characterized in that the arm body is provided with the movable member, a drive source for driving the movable member, and a drive transmission mechanism.