Patent ID: 8435149
Filing Date: 2013-05-07
Classification: B25J,F16H

Abstract:
1. A reduction gear device to be attached to a robot arm of an industrial robot, the reduction gear device comprising: a first reduction mechanism that includes a first spur gear that rotates integrally with an input shaft, and a second spur gear that meshes with the first spur gear; and a second reduction mechanism that includes: (1) a crankshaft that rotates integrally with the second spur gear, and causes, along its rotation, an eccentric revolution of an eccentric cam, (2) an external gear that revolves eccentrically while being engaged with the eccentric cam, and (3) an internal gear that houses the external gear while meshing with the external gear and allows the eccentric revolution of the external gear, wherein the internal gear comprises a number of teeth N differing from a number of teeth of the external gear, wherein one of the internal gear and the external gear is fixed to a base part side member of the robot arm, and the other of the internal gear and the external gear is fixed to an anterior end side member of the robot arm, an inner diameter D of the internal gear is 140 mm≦D≦200 mm, a torque T transmitted to the anterior end side member is 650 Nm≦T≦1960 Nm, and a trend of increase in density of iron powder in a lubricant sealed within the reduction gear device is a first amount for a predetermined period from a time that operation of the reduction gear device begins, and the trend changes to a second amount less than the first amount after the predetermined period has passed, and the iron powder density in the lubricant is less than or equal to 600 ppm when the change in the trend of increase occurs.