He Weidong

Dynamical Model of RV Reducer and Key Influence of Stiffness to the Nature Character

For the RV reducer used in Robots, based on different characteristics of involutes gear and cycloid gear, taken into account the influence of support bearings stiffness and the angle periodic variation between the crankshaft and the cycloid gear, applying Newtons second law and the generalized coordinates method, the 25-DOF dynamical model by lumped-parameter method has been established. Results show that the nature frequency of the RV reducer changes at a tiny range with the rotation of the cycloid gear, the support bearings stiffness of planet carrier and the bending stiffness of crankshaft has obvious effect on the nature frequency. Furthermore, sensitivity analysis of bearing stiffness to the nature character has been analyzed, and the results show that the nature frequency will be larger than 750 Hz when the support and arm bearings have higher stiffness. But the stiffness will decrease quickly when the bearings have tiny clearance caused by assembling or by fatigue. These can produce multi-stage lower nature frequency less than 380Hz, and result in the vibration or flutter of the system. In order to avoid resonance and keep the precision of RV reducer, the support and arm bearings should be designed and assembled as high stiffness.

Study on the Efficiency of the New-Style Reducer with the Green Lubricant

In this paper, we confect the green lubricant for a novel reducer. The basic oils are the pentaerythritol oil and the mixed oil of the rapeseed oil and the pentaerythritol oil. The additive is UT343 which is a kind of composite additive. In the new-style reducer (double rank four ring-plates cycloid drive) rig, we study the transmitting efficiency and the temperature of its running. And the lubricants are the pentaeruthritol with 2%UT343 and the mixed oil with 2%UT343. These two lubricants accord with the rule of greed lubricant. The results show that, compared with the mineral-based oil, the efficiency is enhanced and the oil temperature is reduced apparently. This proves that the lubricant can replace the mineral oil in the reducer. The transmitting power can be raised clearly. And then, with the SEM and the SEDS photos, the principle of increased efficiency is discussed. The element phosphorus acts as lubricating role in the lubricating condition and formed a strong lubricant film. The wearing loss is lower. And this increment was changed to effective power. So the efficiency is enhanced.