FEA and Experimentally Determination of Applied Elasticity Problem for Fabricating Aspheric Surfaces

Abstract

The elastic deformation machining method is suitable for fabricating aspheric surfaces that have excellent physical properties of elastic materials. The machining process is carried out with the deformation model without mold. When vacuum pressure is supplied to the workpiece, the top surfaces of workpiece are deformed into aspheric shape. After machining process, the bottom surface will be formed into the aspheric shape and the top surface returns to its original flat surface form due to internal force and bending moments of the material. However, the accuracy will decrease due to the reduced thickness while the vacuum pressure keeps unchanged during machining process. Therefore, it is necessary to carry out the finite element analysis (FEA) to determine the vacuum pressure with corresponding to the reduced thickness. In addition, the mold with its surface approximates and the desired surface form of the lens is also presented. When uniform vacuum pressure is supplied to the workpiece through small holes of the mold, the workpiece will be deformed into aspheric profile as similar to the mold surfaces. In order to improving the form accuracy, the FEA and the experiment are studied for modifying the mold profile to correspond with bending strength of workpiece material.

Significance of Diamond as a Cutting Tool in Ultra-Precision Machining Process

“…In addition, the aspheric surface is considered to be a portion, and the other portion is a diffraction grating inscribed in the lens. The sharp edges and the circular profile of the [7].…”

“…The performance of the NPCD tool is improved compared to the SCD, where the tool life is longer for the NPCD. This may be due to the hardness property and thermally stable characteristics of the NCPD tool [5,7].…”