Design of a Cross-spring Flexure Hinge with Variable Thickness Based on Bezier Curve

A cross-spring flexure hinge is a widely used kinematic flexible mount. Compared with other flexure hinges, it has a longer rotation stroke, but at the same time, the large center drift of this hinge restricts its support and motion accuracy performance. In this study, a cross-spring flexure hinge with spring leaves of variable thicknesses was designed based on the Bezier curve (B-type hinge). By adjusting the stiffness of the spring leaves at different positions, the deformation of the flexure hinge was mainly concentrated near the intersection of the leaves, thereby improving the support and motion accuracy capabilities of the hinge. The end deflection, axial displacement, and relation between the end rotation angle and end load of the B-type hinge were established based on the Euler-Bernoulli beam theory. The accuracy of the B-type hinge mechanical model was verified using finite element simulation analysis. Then, a B-type hinge was integrated using slow-moving wire cutting, and it was subjected to a bending moment load test; the results were confirmed via simulation analysis. The analysis results showed that, compared with the traditional cross-spring flexure hinges, using the B-type hinge could effectively reduce the parasitic axis drift of regular flexure hinges and improve the support performance and motion accuracy capabilities.