1. Field of the Invention:
The present invention relates to an industrial robot of the type wherein a wrist section thereof has a freedom of movements along three axes.
2. Description of the Prior Art:
In a known industrial robot having a freedom of movements along six axes, a twist body is rotatably carried at one end of an arm body, a bend body is carried at one end of the twist body for rotation about an axis which is slanted with respect to the rotational axis of the twist body, and a swivel body is carried on the bend body for rotation about an axis which is slanted with respect to the rotational axis of the bend body. The known robot is accompanied by a problem that the working range of the bend body is diminished to avoid the interference between the twist body and the bend body.
In order to enlarge the working range of the bend body, it is effective to provide the front end of the twist body with an eccentric cylindrical portion whose axis is eccentric a predetermined amount from the rotational axis of the twist body and to coaxially and rotatably carry two rotational shafts which transmit rotational power respectively to the bend body and the swivel body. If this configuration is used, however, it may become practically difficult to assemble these long rotational shafts into the twist body, with the rotational shafts being held in coaxial relation. Particularly, it may not be easy and may result in taking a long time to assemble the rotational shafts directly into the eccentric cylindrical portion of the twist body.
Further, if the long rotational shafts for the bend and swivel bodies were disposed at a position which is eccentric from the rotational axis of the twist body, there may be raised a problem that the moment of inertia required to rotate the twist body has to be increased.