A ceiling-mounted SCARA robot includes: a base, a first arm that is connected to the lower side of the base via a first coupling part centering around a first articulated shaft and that can pivotally move around the first articulated shaft within a horizontal plane, a second arm that is connected to the lower side of the first arm via a second coupling part centering around a second articulated shaft and that can pivotally move around the second articulated shaft within a horizontal plane, a working shaft that is mounted on the second arm, a second articulated shaft motor and a second articulated shaft reducer for driving the second arm, and a working-shaft rotation motor that rotates the working shaft. The second articulated shaft reducer is provided on the second coupling part, and the working-shaft rotation motor is arranged directly below the second articulated shaft reducer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2010/065141 filed Sep. 3, 2010, the contents of all of which are incorporated herein by reference in their entirety.

FIELD

The present invention relates to a ceiling-mounted SCARA robot.

BACKGROUND

As one type of horizontal articulated industrial robots referred to as SCARA robots, a ceiling-mounted SCARA robot that is installed by being hung from a ceiling surface is known (see, for example, Patent Literatures 1 and 2).

CITATION LIST

Patent Literatures

SUMMARY

Technical Problem

Each of arms and working shafts of a SCARA robot is driven by a motor and a reduction gear (hereinafter just “reducer” for convenience) provided on each of the arms and working shafts. As the motor and the reducer, which are heavy parts, are arranged to be closer to a tip end of the arm, the load on the motor and the reducer that drive the arm increases. Such a load becomes more noticeable as the SCARA robot is required to operate faster and more frequently.

The present invention has been achieved in view of the above problem, and an object of the present invention is to provide a ceiling-mounted SCARA robot that can reduce a load caused by driving of an arm.

Solution to Problem

In order to solve the aforementioned problems, a ceiling-mounted SCARA robot according to one aspect of the present invention is constructed in such a manner that it includes: a base; a first arm that is connected to the lower side of the base via a first coupling part centering around a first articulated shaft and that can pivotally move around the first articulated shaft as a center of pivotal movement within a horizontal plane; a second arm that is connected to the lower side of the first arm via a second coupling part centering around a second articulated shaft and that can pivotally move around the second articulated shaft as a center of pivotal movement within a horizontal plane; a working shaft that is mounted on the second arm; a second articulated shaft motor and a second articulated shaft reducer for driving the second arm; and a working-shaft rotation motor that rotates the working shaft, wherein the second articulated shaft reducer is provided on the second coupling part, and the working-shaft rotation motor is arranged directly below the second articulated shaft reducer. The second articulated shaft motor is arranged in a position that is between the second coupling part and the working shaft and directly below a first articulated shaft reducer at the lower side of the first arm. The arm length of the first arm and the arm length of the second arm are the same (shaft distances thereof are the same).

Advantageous Effects of Invention

The ceiling-mounted SCARA robot according to the present invention can reduce a load caused by driving of an arm.

DESCRIPTION OF EMBODIMENTS

Exemplary embodiments of a ceiling-mounted SCARA robot according to the present invention will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments.

Embodiment

FIG. 1is a front view of a ceiling-mounted SCARA robot according to an embodiment of the present invention. A ceiling-mounted SCARA robot1includes a base10, a first arm11, a second arm12, and a working shaft13. The ceiling-mounted SCARA robot1is installed in such a manner that the base10is attached to a ceiling surface so as to be hung from the ceiling surface.

The first arm11is connected to the base10via a first coupling part14centering around a first articulated shaft. The first arm11is configured to be capable of pivotally moving around the first articulated shaft as a center of pivotal movement within a horizontal plane that is parallel to the ceiling surface. The second arm12is connected to the first arm11via a second coupling part15centering around a second articulated shaft. The second arm12is configured to be capable of pivotally moving around the second articulated shaft as a center of pivotal movement within a horizontal plane. The working shaft13is arranged at a tip portion of the second arm12to be able to move in a vertical and rotatable manner. A tool for conveying and machining workpieces is mounted on the working shaft13.

The first arm11has arranged therein an accommodating space16that projects to the lower side thereof. The accommodating space16is arranged to be in parallel to the second coupling part15in a horizontal direction. The second arm12has arranged therein an accommodating space17that projects to the upper side thereof. The accommodating space17is arranged to be in parallel to the second coupling part15in a horizontal direction.

The arm length of the first arm11and the arm length of the second arm12are set to be equal. The arm length of the first arm11is set to be a distance between the first articulated shaft and the second articulated shaft. The arm length of the second arm12is set to be a distance between the second articulated shaft and a center of the working shaft13. The first arm11and the second arm12are configured to pass by without interfering with each other because their pivoting surfaces are vertically shifted from each other.

FIG. 2is a schematic configuration diagram showing inside of the ceiling-mounted SCARA robot. Among the components arranged inside of the ceiling-mounted SCARA robot1, those which are not necessary to be mentioned for the following explanations are not shown inFIG. 2. The ceiling-mounted SCARA robot1shown inFIG. 2represents a state where the second arm12has been pivotally moved180degrees from the state shown inFIG. 1and the second arm12is accommodated under the first arm11(hereinafter, this state is referred to as “accommodated state” as appropriate).

A first articulated shaft motor21and a first articulated shaft reducer25drive the first arm11. The first articulated shaft motor21is arranged in the base10. The first articulated shaft reducer25is arranged in the first coupling part14. A second articulated shaft motor22and a second articulated shaft reducer26drive the second arm12. The second articulated shaft motor22is arranged in the accommodating space16in the first arm11with a rotor thereof projecting upward. The second articulated shaft motor22is arranged in a position that is between the second coupling part15and the working shaft13and directly below the first articulated shaft reducer25at the lower side of the first arm11. The second articulated shaft reducer26is arranged in a position that is closer to the first arm11in the second coupling part15.

A working-shaft vertical-movement motor23moves the working shaft13vertically. The working-shaft vertical-movement motor23is arranged in a position at a side near the second coupling part15in the accommodating space17. The working shaft13is also arranged in the accommodating space17of the second arm12. A working-shaft rotation motor24rotates the working shaft13. The working-shaft rotation motor24is arranged to bridge across the second coupling part15and the second arm12. A part of the working-shaft rotation motor24is arranged inside of the second coupling part15. Furthermore, the working-shaft rotation motor24is arranged directly below the second articulated shaft reducer26. In the present embodiment, “directly below” here means that a component, in a state in which the ceiling-mounted SCARA robot1has been installed, is arranged in a position at a vertically lower side.

In the accommodating space17in the second arm12, there is provided a step portion that corresponds to the size of the accommodating space16of the first arm11. When the ceiling-mounted SCARA robot1is in an accommodated state, the accommodating space16of the first arm11is put into a position where three sides thereof are surrounded by the step portion and the second coupling part15. When the ceiling-mounted SCARA robot1is in an accommodated state, the working-shaft vertical-movement motor23is positioned directly below the second articulated shaft motor22.

As the working-shaft rotation motor24is arranged directly below the second articulated shaft reducer26while at least a part thereof is inside of the second coupling part15, the working-shaft rotation motor24is arranged to be as close as possible to a second articulated shaft J2. As the working-shaft vertical-movement motor23is arranged in a position at a side near the second coupling part15within the accommodating space17of the second arm12, the working-shaft vertical-movement motor23is arranged to be as close as possible to the second articulated shaft J2.

As the working-shaft rotation motor24and the working-shaft vertical-movement motor23, which are heavy parts, are arranged in a position close to the second articulated shaft J2, it becomes possible to reduce an inertia force on the second arm12. Due to this, it is possible to reduce a load on the second articulated shaft motor22and the second articulated shaft reducer26for driving the second arm12.

As the second articulated shaft motor22is arranged in the accommodating space16that is positioned at the lower side of the first arm11with the rotor thereof projecting upward, the second articulated shaft motor22is positioned to be closer to a first articulated shaft J1as compared to a case where the second articulated shaft motor22is positioned at an upper side of the first arm11with the rotor thereof projecting downward. By arranging the second articulated shaft motor22below the first articulated shaft reducer25, it is arranged to be as close as possible to the first articulated shaft J1. By arranging the second articulated shaft motor22, which is a heavy part, in a position close to the first articulated shaft J1, it is possible to reduce an inertia force on the first arm11. Due to this, it becomes possible to reduce a load on the first articulated shaft motor21and the first articulated shaft reducer25for driving the first arm11.

Furthermore, when the ceiling-mounted SCARA robot1is in an accommodated state, the working-shaft vertical-movement motor23is positioned directly below the second articulated shaft motor22, and therefore the second articulated shaft motor22, the working-shaft vertical-movement motor23, and the working-shaft rotation motor24are gathered in a position as close as possible to the first articulated shaft J1. Accordingly, when the first arm11is driven while the ceiling-mounted SCARA robot1is in an accommodated state, it is possible to reduce a load on the first articulated shaft motor21and the first articulated shaft reducer25. Accordingly, the ceiling-mounted SCARA robot1can reduce a load caused by driving of arms. According to the present embodiment, it is possible to obtain a light-weight and highly rigid arm that can perform high-speed operations.

INDUSTRIAL APPLICABILITY

As described above, the ceiling-mounted SCARA robot according to the present invention can reduce a load caused by driving of an arm, and therefore the ceiling-mounted SCARA robot is particularly suitable for works that require faster and frequent operations.

REFERENCE SIGNS LIST