An improved robust identification method for position independent geometric errors of the swing axis of the gear grinding machine

Although the double ball bar (DBB) has been widely used in geometric error identification, it shows unstable identification results of the position independent geometric errors (PIGEs) of the rotary axes with complex structures. To solve this problem, this paper proposes an improved robust method of the PIGEs identification with circular trajectory in multiple planes. Based on the definition of axis average line defined in the ISO 230-7, more circular trajectory tests were carried out along the axis line instead of only two circular trajectories in ISO 230-7 and other references, then the axis average line together with PIGEs was finally obtained. As a specific application case, the proposed method was adopted in the PIGEs identification of the swing axis of the gear grinding machine with a relatively complex structure. Eight circular tests were performed, and 4 PIGEs were finally identified. In particular, the relationship between the measurement patterns and the identification accuracy is investigated, further demonstrating the limitations of the existing methods with only 2 circular trajectories used. The experimental results show that the proposed method is a simple but effective improvement to existing PIGEs identification methods using DBB.