Tool path generation and optimization for freeform surface diamond turning based on an independently controlled fast tool servo

Abstract

Diamond turning based on a fast tool servo (FTS) is widely used in freeform optics fabrication due to its high accuracy and machining efficiency. As a new trend, recently developed high-frequency and long-stroke FTS units are independently driven by a separate control system from the machine tool controller. However, the tool path generation strategy for the independently controlled FTS is far from complete. This study aims to establish methods for optimizing tool path for the independent control FTS to reduce form errors in a single step of machining. Different from the conventional integrated FTS control system, where control points are distributed in a spiral pattern, in this study, the tool path for the independent FTS controller is generated by a ring method and a mesh method, respectively. The machined surface profile is predicted by simulation and the parameters for the control point generation are optimized by minimizing the deviation between the predicted and the designed surfaces. To demonstrate the feasibility of the proposed tool path generation strategies, cutting tests of a two-dimensional sinewave and a micro-lens array were conducted and the results were compared. As a result, after tool path optimization, the peak-to-valley (P-V) form error of the machined surface was reduced from 429 nm to 56 nm for the two-dimensional sinewave by using the ring method, and from 191 nm to 103 nm for the micro-lens array by using the mesh method, respectively.

Friction behaviors in the metal cutting process: state of the art and future perspectives

“…Advanced manufacturing technology is developing in the direction of ultra-high speed, high flexibility, ultra-precision, and green processing. The diverse cutting processes mainly include ultra-high speed machining, heavy-duty cutting, laser-assisted machining, precision, and ultra-precision cutting [53,54]. As shown in figure 10, the cutting mechanism of ultra-high speed machining also undergoes substantial alterations concerning traditional cutting when the cutting speed exceeds 1000 m min −1 .…”

Generation of Micro Lenslet Arrays using High Efficiency Synchronized Diamond Milling

“…(5) (6) Where L is the length of the lenslet and F is the reciprocating feed of the tool, where the positive notion is used when moving against the rotation of the tool.…”

“…and Nanotechnology (ASPEN 2022) 15-18 November 2022, Singapore. Edited by Nai Mui Ling Sharon and A. Senthil Kumar functional surfaces like micro lenslet arrays [6]. Nevertheless, the processing speed is limited to the positioning ability of the FTS, along with the frequency of the features at the extremities of the component.…”

Numerical simulation of materials-oriented ultra-precision diamond cutting: review and outlook

“…Among wide ranges of advanced manufacturing techniques, ultra-precision single point diamond turning (SPDT) utilizing synthetical or natural single-crystal diamond (SCD) tools with nanoscale cutting edge radius has become a popular one, due to its achievable accurate form accuracy, moderate machining efficiency, high machined surface finish, high degree of machining freedom and low subsurface damage, etc [8][9][10][11][12]. For instance, ultra-smooth surface with nanoscale or even sub-nanoscale surface flatness can be readily prepared by ultra-precision diamond cutting, for its achievable nanometer machining accuracy [13,14].…”