| 摘要 |
<p>An industrial robot is provided with a body (3), a rotary shaft (20) supported rotatably on the body, a driving motor (17) for rotating the rotary shaft, and a robot arm (13) connected at its base end to the rotary shaft and adapted to be turned at its free end in accordance with the rotation of the rotary shaft so that the arm is displaced upward and downward. An arm gravity balancer (21) is adapted to apply to the rotary shaft the moment (-M1) resistant to the moment (M1) which occurs around the axis of the rotary shaft due to the gravity applied to the robot arm. The balancer is provided with a tension spring (22) connected at its one end to the body. The other ends of the tension spring are connected to such two portions of the rotary shaft that are spaced from each other in the rotational direction of the shaft. These two portions of the rotary shaft, to which the tension spring is connected, are equally away from and symmetric with respect to, in the rotational direction of the rotary shaft, a straight line (X) which connects the first-mentioned single end of the tension spring and the axis of the rotary shaft, when the robot arm is in a vertical position.</p> |
