Design and experiment of generalized triple-cross-spring flexure pivots applied to the ultra-precision instruments

Owing to the excellent performance, the generalized cross-spring flexure pivots (GCSFP), formed by two symmetric crossing leaves at an arbitrary position along the radial direction, had been widely used in precision instruments. However, the accuracy of GCSFPs is lower than the required one for some ultra-precision instruments. Especially for the large angles, the axis drift of GCSFPs cannot be ignored. By adding a spring to a GCSFP, a novel flexure pivot, which called generalized triple-cross-spring flexure pivot (GTCSFP), can be obtained. Finite element analysis shows that GTCSFPs can achieve ultra-high precision. The axis drift is less than 0.3 μm for a ±10° motion range. Several prototypes of GTCSFP were designed and manufactured. Rotational stiffness, radial stiffness, axial stiffness, axis drift, temperature drift, and fatigue life were measured. The result shows that GTCSFPs have many advantages, such as high precision, long service life, large movement range, and high off-axis/axial stiffness ratio. Thus, GTCSFPs have potential applications in the field of precision instruments.