A Study to Enhance the Accuracy of Linear Motion Ball Guide System

―Theoretical Elucidation of the Influence of Misalignment to Waving Amplitude―

Abstract

In the previous reports, it was clarified that waving amplitudes in linear motion ball guide (LMBG) systems can be suppressed by optimization of the crowning shape on end of carriage's raceways. Moreover, the evaluation algorithm of waving amplitude considered table deformation and the design method of table parameters based on a desired waving amplitude were developed. Mounting surface errors for LMBG significantly affect the motion accuracy of LMBG, however, this phenomenon has not been clarified yet. In this study, therefore, this issue is clarified analytically. At first, the analytical model of LMBG system is constructed; the model can set on the initial five-way errors for carriage and rail of LMBG: horizontal direction, vertical direction, roll angle, pitch angle and yaw angle. Then, load distribution theory analyses with various misalignment are carried out. The analyes results show that the only horizontal error significantly affects the waving amplitude; other four-way errors affect little. These results also suggest that the proposed analysis can evaluate necessary mounting surface accuracy to achieve a desired waving amplitude. Furthermore, it is clarified that the LMBG's rating life is affected by the additional load due to misalignment.