| The principle of the precision ball transmission mechanism is utilizing the cycloid groove face meshing pair to realize deceleration and utilizing annular groove end face engagement to realize constant output. The major advantages of this mechanism are large transmission ratio, the structure of small size, high transmission efficiency and strong load-carrying capacity. Beyond these, the agency’s biggest feather is no return difference, and this structural characteristic ensures to meet special requirements in the field of precision mechanical transmission. So this mechanism is widely used in the field of high precision industrial robot drive.Driving accuracy as an important performance index in mechanical drive mechanism is increasingly in the spotlight, so it is necessary for us to analyze this standard. Through the study, we can clarify the influence rule of each error factor to realize the further improvement in the performance of this transmission. At the same time, this transmission will have broad prospects in the future.The paper analyzes the structure, principles and movement characteristics of the precision ball drive mechanism. After that, the formula of angular relationship in the formation of the tooth profile curve is deduced. Based on the institutional precision theory, this paper studies the sources of the transmission error. According to the different error factors, the analyses of different methods are carried out.Under the action of resistance moment in the output tray, the ball meshing pairs in the deceleration part and the constant output part will generate contact deformations, and these small deformations lead to minute angles relative to the theoretical positions in these spare parts. Based on Hertz point contact theory, the paper analyses the contact deformations in these engagement pairs, and deduces the stiffness formula of meshing pair. Then the article structures moment equilibrium equations between the space meshing foeces and resistance moment. By solving these equations, the changing rule curves of minute angles are obtained.Because of so many parts in the precision ball transmission, there are different machining errors and installation errors, and all of these errors wear an impact on the output tray’s rotation error. Using a method of mass-spring equivalent model,the article build a mathematical model taken all the errors mentioned above into account. The application programme compiled by using MATLAB can proceed simulated analysis of the rotation error, and get fine error curve. At last, the paper analyses every error factor’s influence regularity on the rotation error independently. By comparison, the article finds out the main factors that influence the transmission accuracy and their effect laws. It can make preparation for the further research and provides reference for the actual processing and manufacturing of the precision ball transmission. According to the conclusion, when this drive is manufactured, the precision is distributed reasonably. The machine will meet the accuracy requirement, and be affordable. |
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