Diamond machining of freeform-patterned surfaces on precision rollers

Mingyu Liu,Xiaobing Feng,Chunjin Wang,Chi Fai Cheung

doi:10.1007/s00170-019-03628-y

Abstract

Rapid development of freeform surfaces faces the challenges of not only higher form accuracy and smoother surface finishing but also high machining efficiency and lower manufacturing cost. Combining diamond turning and roll-to-roll embossing technologies is a promising solution to fulfill these requirements. This paper presents a generic method to design and machine freeform surfaces on precision rollers. The freeform surface designed on the flat substrate is first transferred onto the cylindrical roller surface. The freeform-patterned roller surface is then diamond turned using the toolpath generated by a purposely developed toolpath generator. With the proposed method, the complex freeform surfaces designed on flat substrate can be transferred to and precisely machined on the cylindrical roller surfaces. A cutting experiment has been conducted to demonstrate the capability of the proposed method. In the experiment, a sinusoidal surface was designed and diamond turned on a precision roller. The results demonstrate that the proposed method is accurate and effective. The proposed method provides guidance for the design and precision manufacturing of freeform-patterned surfaces on precision rollers.

Highlights

Precision freeform surfaces [1] and structured surfaces [2] are widely used in various consumer products such as digital cameras [3] and 3D displays [4], and applications in advanced optics [5] and bio-medical parts [6]
While single point diamond turning is promising for the manufacture of freeform and micro-structured patterns on precision rollers, there are relatively few studies that focus on the development of a generic machining method for diamond turning of these kinds of freeform-patterned surfaces, i.e., given a designed surface with shape geometry of any degree of complexity, it can be transferred to the precision rollers, or the freeform patterns can be directly designed on the precision rollers, and be diamond machined as long as the tool geometry can meet the requirement
The method first transfers the conventional freeform surface designed on the flat substrate to the cylindrical roller surface

Summary

Introduction

Precision freeform surfaces [1] and structured surfaces [2] are widely used in various consumer products such as digital cameras [3] and 3D displays [4], and applications in advanced optics [5] and bio-medical parts [6]. Li et al [24] machined a V-shaped cylindrical grating on the roller surface, where the diamond tool cut in the z axis direction while the workpiece rotated incrementally This method is limited to 2D patterns and cannot be directly used to machine 3D-patterned surfaces. While single point diamond turning is promising for the manufacture of freeform and micro-structured patterns on precision rollers, there are relatively few studies that focus on the development of a generic machining method for diamond turning of these kinds of freeform-patterned surfaces, i.e., given a designed surface with shape geometry of any degree of complexity, it can be transferred to the precision rollers, or the freeform patterns can be directly designed on the precision rollers, and be diamond machined as long as the tool geometry can meet the requirement. When the flat substrate is designed to be transferred to the cylindrical substrate, special attention should be paid to avoid surface discontinuity in the wrap-around region, which may affect the dynamics of the machining process

Toolpath generation

Roller with sinusoidal patterns

Roller with a microlens array

Conclusion