A Toolpath Planning Method for Optical Freeform Surface Ultra-Precision Turning Based on NURBS Surface Curvature

Abstract

As the applications for freeform optical surfaces continue to grow, the need for high-precision machining methods is becoming more and more of a necessity. Different toolpath strategies for the ultra-high precision turning of freeform surfaces can have a significant impact on the quality of the machined surfaces. This paper presents a novel toolpath planning method for ultra-precision slow tool servo diamond turning based on the curvature of freeform surfaces. The method analyzes the differential geometric properties of freeform surfaces by reconstructing NURBS freeform surfaces. A mathematical model is constructed based on the parameters of different positions of the freeform surface, toolpath parameters, and tool residual height. Appropriate toolpath parameters can be calculated to generate the optical freeform ultra-precision slow tool servo diamond turning toolpath. Compared with the toolpaths generated by the traditional Archimedes spiral method, the ultra-precision slow tool servo diamond turning toolpath planning method proposed in this paper can generate more uniform toolpaths on the freeform surfaces and keep the residual tool height within a small range.

Determinant of Dynamics and Interfacial Forces in Ultraprecision Machining of Optical Freeform Surface through Simulation-Based Analysis

“…Diamond turning, a precision-engineered subset of ultraprecision machining, is increasingly recognized for its efficacy in producing optical freeform surfaces. The novel ultraprecision toolpath planning method for slow tool servo diamond turning optimises freeform optical surface machining by considering surface curvature and differential geometry for enhanced surface quality and uniformity [1]. This technique stands out for its integration of fast tool servo (FTS) and slow tool servo (STS) methodologies, which are key to achieving high accuracy in complex surface geometries.…”