Study on the establishment method of multi-dimensional chain model and precision assembly for robot precision reducers

The motion accuracy and service life of robot precision reducers are directly affected by the assembly accuracy and stability, and the correct establishment of the assembly dimension chain is a crucial factor in ensuring the precise assembly of reducers. Therefore, a mathematical model of the multi-dimensional chain (MDC) is proposed based on distance over balls and pre-loading, which can effectively enhance the assembly accuracy of the reducers and ensure the consistency of product quality. The MDC model is built by applying a series of methods. The first-dimensional chain is established based on the distance over balls of the cycloidal gear and the pin housing, which ensures the lost motion and transmission error of the reducers. The second-dimensional chain is established according to the structure of the crank bearing. The influence of shape and position errors on operating torque fluctuation is compensated by controlling the clearance of the crank bearing. The third-dimensional and fourth-dimensional chains are established, respectively, through the axial pre-loading of the main bearing and tapered bearing, so the appropriate operating torque fluctuation of the reducers is guaranteed. Meanwhile, the relationship of the dimension chain and backlash is described through analyzing the error accumulation of the MDC. Finally, the comparative experiments are conducted, respectively, based on the MDC and manual random assembly methods. The results show that the assembly accuracy and efficiency of reducers can be improved effectively by applying the MDC, which can ensure the consistency of the accuracy and provide the theoretical guidance and technical support for the effective control of the motion accuracy of the reducers.