Research On Ultraprecision Cutting Of Microlens Array On Oxygen-free Copper

The diameter of microlens array element is usually in micron scale.It has the characteristics of small cell structure,small size,high integration and rich optical function.With the rapid development of optoelectronic technology,the demand for microlens array photoelectric components is increasing day by day.In order to realize large scale,high efficiency and high quality production of microlens array optoelectronic devices,a lot of researches have been carried out.At present,the method of machining microlens array are hot emboss,ultraprecision cutting,ultraprecision grinding,hot melt adhesive and Femtosecond laser acid etching,but these technologies are not mature,which have the problems of low processing accuracy,low processing efficiency,and can only machine large scale microlens array.Ultraprecision cutting is the main method to achieve high precision,small scale and large area microlens array machining.In this thesis,the ultraprecision slow tool servo(STS)machining and ultraprecision micro milling of microlens array were studied.The mechanism of tool path generation of two machining methods was studied,and the trajectory planning method was proposed.Through theoretical analysis,finite element simulation and experiment,the effects of cutting speed,cutting depth,tool rake angle and workpiece exit angle on the machining accuracy of microlens array were studied.The advantages and disadvantages of slow cutter servo cutting and micro milling were compared and analyzed.Aiming at the built-up edge(BUE)reduce the machined surface roughness,failure surface integrity problems,firstly the formation mechanism of BUE was studied.Through the finite element simulation and experiments of ultraprecision turning,the influence of cutting depth and cutting fluid on BUE formation was analyzed.It was found that when the cutting depth is large,the high pressure zone formed on the rake face,which hinders the discharge of chip and accelerates the formation of BUE.Therefore,the "step-by-step cutting method" was put forward to avoid the formation of a high pressure area,and restrain BUE generation;the tool chip interface membrane forming method for reducing tool-chip interface friction coefficient was put forward to restrain the formation of BUE.As for the formation of burr,through the design of single factor cutting experiments,the influence of cutting depth,feed speed and spindle speed on burr formation was studied.Third Wave AdvantEdge finite element simulation software was used to simulate the cutting process.The influence of tool rake angle and workpiece exit angle on burr formation mechanism was studied.The methods of reducing the rake angle of the cutter and reducing the depth diameter ratio of the micro lens were proposed to restrain the burr.Based on the above research,the method to control form accuracy and surface quality of microlens array was established.Through the optimization of machining parameters,the surface roughness of single micro lens can reach 5nm,and the form accuracy PV can reach 43 nm.The position error of each lens element in the microlens array is less than 10 nm Ra.