High-precision roll bending of titanium alloy wire for glasses

Although the frames of glasses are generally made of titanium alloy, achieving a given designed shape can be difficult because titanium alloy has a large springback. Actually, the production of the rims of these frames depends on the experience and skills of workers. We conducted an experiment and carried out FEM analysis to investigate an improved method for producing rims via high-precision roll bending. First, to investigate real rim production, we searched for a relationship between roll no. 8 intermesh h and lens curvature κy, and a relationship between intermesh h and rim curvature κz using the titanium alloy wire used for actual rim production. Second, we created an analytical model to clarify actual rim production. Based on a detailed examination of the manufacturing process using experimental and FEM analyses, we found that the wire was tilted by a twisting moment generated by the roll no. 8 intermesh. We considered the cause of moving contact point between wires and bending rolls generated by getting lens curvatures processing defects. Third, the distance between roll nos. 7 and 8 was changed to reduce deviations from the standard wire. Finally, we achieved a better bending process for producing high-precision rims for glasses.