Experimental Investigation On WEDM Process And Molding Of Optical Microstructure Array Mold

In recent years,due to its high image quality,large field of view,high uniformity and lightweight,the microlens array has become the most compelling core device in camera lens,optical communication,infrared detection,intelligent guidance and other systems.At present,optical glass molding technology is the most effective method to obtain high-precision,high-volume and low-cost microlens array.However,in the process of optical molding,the quality of microlens array mold plays a key role in the performance and cost of microlens array products.The work aims to obtain highprecision micro-pyramid array mold on the new precision glass molding die material,C71500 copper-nickel alloy,by using Low Speed Wire cut Electrical Discharge Machining(LS-WEDM)technology.Then,molding experiments were carried out using a self-developed micro-pyramid array mold to verify the processing quality and forming properties of the mold.The main contents include the following aspects:(1)The influence of WEDM process parameters on workpiece machining accuracy and surface quality was analyzed.The surface roughness and arc radius of the micropyramid array mold were determined as the technological indexes,and the pulse width,pulse interval,wire speed and peak current were selected as the influencing factors of the technological indexes.Single-factor method,corner-processing technology and multi-cutting forming method were carried out as test methods.The influence of precision WEDM parameters on surface roughness and arc radius of micro-pyramid arrays was studied.(2)Several parameters affecting the surface roughness and arc radius of micropyramid arrays were analyzed.Besides,the heterogeneity of cusp radius of the micropyramid array mold was studied,and the optimal process parameters could be obtained by comprehensive optimization of the experimental results.It was found that the surface roughness of the cusp decreased when it came to the decline of the pulse width or the increment of the wire speed,and decreased at first and then increased with the increment of the pulse gap.The arc radius of the cusp decreased with the decrease of the pulse width,and decreased with the increment of the pulse gap and the wire speed.The comprehensive optimization result showed that micro-pyramid array mold cusp could achieve the optimal surface roughness(Ra9nm)and the minimum cusp radius(5.41?m),when the pulse width was 6?s,the pulse interval time was 14?s and the wire speed was 6m/s.Compared with the experimental results before optimization,the surface roughness was reduced by 60.9%,and the cusp radius was reduced by 53.0%.(3)The molding experiment was carried out by using the self-developed micropyramid array mold to study the influence of molding speed,molding temperature and pressing amount on the forming depth of the micro-pyramid array lens.Based on the experimental results,the die pressing process parameters were optimized to improve the forming accuracy of micro pyramid array lens.At the same time,the precision micro-pyramid array lens was molded to verify the performance of the self-developed micro-pyramid array mold.