Horizontal articulated robot

Abstract

A horizontal articulated robot includes a base, a first arm provided rotatably around a first rotation axis on the base, a second arm provided rotatably around a second rotation axis on the first arm, the second rotation axis being parallel to the first rotation axis, and a main shaft provided in the second arm to be extended in a direction parallel to the second rotation axis. A distance between the second rotation axis and the main shaft is shorter than a length of a straight line connecting the first and the second rotation axes. Additionally, the first arm has a recessed portion formed so as to include a position on a rotation path where a rotation radius around the second rotation axis is equivalent to the distance between the second rotation axis and the main shaft.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 12 / 547,533 filed on Aug. 26, 2009, which claims priority to Japanese Patent Application No. 2008-223868 filed on Sep. 1, 2008, both of which are hereby expressly incorporated by reference herein in their entireties.BACKGROUND[0002]1. Technical Field[0003]The present invention relates to an industrial robot, and more particularly to a horizontal articulated robot having a plurality of horizontally rotating arms.[0004]2. Related Art[0005]Among industrial robots, there is known a SCARA robot (a horizontal articulated robot) with a plurality of arms sequentially connected by means of a horizontal articulation. FIG. 12 shows an example of a planar structure of a common SCARA robot having two arms.[0006]As shown in FIG. 12, the SCARA robot includes a base 51, a first arm 52 having a base end portion horizontally rotatably connected to a base 51, and a second arm 53 having a ...

AI Technical Summary

Benefits of technology

[0012]The present invention has been accomplished under the aforementioned background. An advantage of the invention is to provide a horizontal articulated robot that achieves a large mobility range while maintaining a high responsiveness, and a high positioning precision.

[0013]A horizontal articulated robot according to an aspect of the invention includes a base, a first arm provided rotatably around a first rotation axis on the base, a second arm provided rotatably around a second rotation axis on the first arm, the second rotation axis being parallel to the first rotation axis, and a main shaft provided in the second arm to be extended in a direction parallel to the second rotation axis, a distance between the second rotation axis and the main shaft being shorter than a length of a straight line connecting the first and the second rotation axes, and the first arm having a recessed portion formed so as to include a position on a rotation path where a rotation radius around the second rotation axis is equivalent to the distance between the second rotation axis and the main shaft.

[0014]In the horizontal articulated robot, the main shaft has the rotation path where the rotation radius around the second rotation axis is equivalent to the length of the second arm. The main shaft is movable to be positioned in such a manner that the main shaft enters into an eccentrically recessed region of the first arm. In other words, the movable range of the main shaft is extended by an amount of reduction in a minimum rotation radius with respect to the first rotation axis of the main shaft.

[0015]In addition, when compared with the conventional horizontal articulated robot having the first arm without any recessed portion, there is no change in the lengths of the first and the second arms in the robot of the aspect. This can minimize an increase in the mass of the first arm, as well as the second arm as in the conventional robot can be used without change. As a result, even when using the eccentric first arm as described above in the horizontal articulated robot, responsiveness, positioning precision, and the like can be maintained as in the conventional robot. Thus, there is no unnecessary increase in robot size.

[0016]Preferably, in the horizontal articulated robot, the recessed portion is formed by curving the first arm.

[0017]In the structure, the main shaft is movable to be positioned in such a manner that the main shaft enters into a curved portion of the first arm. Thereby, the main shaft can be received more smoothly in the curved portion according to a curving shape of the first arm.

Problems solved by technology

Accordingly, miniaturization of the arm frame is restricted, and it is thus difficult to reduce the minimum radius Rmin.

This can deteriorate responsiveness upon movement and positioning precision.

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