Research On Machining Method Of Polygon Fresnel Structure On Roller Mold

Fresnel lenses are optical elements that,due to their light weight,small size and excellent optical properties,have broad applications such as optoelectronics,photonic devices,advanced lighting systems,and concentrated solar systems that have evolved into single element arrays with better performance and higher functionality.These arrays can also be implemented using individual elements with polygonal shapes such as rectangles,hexagons,to achieve high filling rates.With the development of science and technology,the market demand for such microstructural optical diaphragm is huge.Roll-to-Roll(R2R)imprinting is a low-cost,high-productivity manufacturing process capable of replicating microstructures from roller molds to flexible membranes with high resolution and precision,and meeting the requirements of mass,automated production tasks.However,discontinuous nonrotating symmetric microstructures are difficult to fabricate on cylindrical surfaces.Therefore,an alternative approach has been adopted in the industry to copy the Fresnel lens structure from the flat plate to the flexible electroplated metal sheet and then wrap it around the outer cylindrical surface to form a structured roller mold.However,this plating and packaging process will introduce additional replication and assembly errors and reduce profile accuracy and surface roughness.This paper takes the processing of polygonal Fresnel structure on cylindrical surface as the research object,redesigns the structure of roller machine tool according to polygonal Fresnel structure processing,considers the geometry of polygonal Fresnel lens structure,diamond tool and the parameters of roller mold,studies the feasibility of polygonal Fresnel structure processing on roller,completes the experiment of polygonal Fresnel structure processing on roller,and carries on the measurement and error analysis to the polygonal Fresnel structure on roller.The thesis focuses on the following four parts:1.The modification of the existing roller machine tool,the rotary a shaft with positioning function is added;the base of the shaft is designed and processed,and the main function of the shaft is to maintain the relative position relationship between the tool and the workpiece and to assist the tool rotation.2.An algorithm for production of planar polygon Fresnel structure on roller surface is studied.A new processing method,diamond micro-scrape(DMS),was developed to provide a possible solution for the fabrication of a polygon Fresnel lens structure on a roller mold.In the proposed DMS machining method,the tool path is calculated according to geometry,which considers the structural design of the roller machine tool,the designed polygon Fresnel lens structure,the geometry of the diamond tool,and the parameters of the roller die.The machining scheme of ultra-precision roller machine tool is designed,and the machining method of polygon Fresnel structure on roller mold is optimized.3.According to the design outline of polygon Fresnel,the geometric parameters of diamond tool are determined,and the arc radius compensation of diamond tip is carried out according to the machining path.The error sources which affect the machining precision of polygon Fresnel structure on roller die are simulated and predicted.The relationship between the error source and machining precision is analyzed qualitatively and the corresponding compensation scheme is put forward to improve machining efficiency as far as possible under the premise of ensuring machining quality.By analyzing the influence of measuring error of roller diameter,deviation of cutter tip from a axis rotation center and non-vertical rotation axis of cutter tip and roller on machining precision of polygon Fresnel contour,the corresponding compensation and correction are carried out on the basis of mastering its influence law.4.Using the Taylor profilometer(Taylor-Hobson form Taly-surf)to measure the average surface roughness of the polygon Fresnel lens structure on the roller mold is ra6.7nm、 the contour accuracy is better than that of the PV 1,and a contour GT-X 3D optical profilometer is used to measure the 3 d contour of the polygon Fresnel structure.The multi-shaped Fresnel structure with a maximum side length of 1.7 mm,characteristic depth of 10 is processed on the roller die with a diameter of 60.316 mm,which verifies the feasibility of the diamond micro-scrape method to process the multi-shaped Fresnel structure on the roller,and analyzes and summarizes the factors affecting the machining error according to the processing results.