Modeling And Experimental Study On Fly-Cutting PMMA Bragg Grating Substrate

The micron precision Bragg grating(typically 10μm or less) on the distributed feedback(DFB) dye lasers substrate is the key point to the laser wavelength tuning and quality of output laser. Bragg grating is a micron linear three-dimensional periodic array of channels, commonly machined by MEMS and Energy assistant technology. However, the low machining precision, processing materials restricted, high processing costs, long production time and other issues, limit the improvement of the efficiency and quality of the output of the laser. Combined with the actual needs and working conditions, this project proposes the use of a diamond tool fly-cutting technology in processing the Bragg grating on PMMA substrate. With the combining methods of numerical simulation, basic experiments analogy, finite element simulation and machining experimental verification to s tudy the mechanical properties and processing performance of PMMA substrate. Analyze the impact of chip flow process on processing quality, forecast the influence law of each machining process parameters on the fly cutting chip liquidity, stress and strain. With the acoustic emission technology ensuring the accuracy of tool adjusting, by single-factor test to verify the theoretical prediction and simulation, optimize the machining parameters, has important theoretical and practical value for reference to ge t the highquality Bragg grating on PMMA substrate.Considering the nature differences of PMMA material and the requirement of many material physical parameters before the simulation, this paper measured the hardness and indentation microstructure morphology by micro-indentation, combined nano-indentation test to get basic mechanical performance parameters of PMMA, and simulated of the stress- strain curve. Study the elastic-plastic performance in micron removal. Analogy the experiment process and results between micro-planing and flycutting, has a deep understanding of the advantages and disadvantages of fly-cutting Bragg grating. Get the cutting principle factors affecting the cutting quality theoretically. At last get a conclusion: the chip flow mobilit y in non-free chip zone before the diamond tool plays an important role in processing quality.With Finite element simulation method, based on the actual process, establish tool and workpiece three-dimensional cutting model, use grooving pattern to simplif y the simulation of cutting process in non-free chip zone during. Combined with the indentation test, select the constitutive model and complete a set of parameters. Study the influence of cutting depth, cutting speed and cutting edge angle on chip liquidi ty, stress, strain in the cutting process, and is a theoretical guidance for the actual cutting experiment. Before single-factor experiments, using acoustic emission technique to ensure the accuracy of tool adjusting in the sub-micron level, and analyze fly cutting process from the peak variation of acoustic emission signal; through the comparison of single factor test results, study the factors on the processing quality, optimize process parameters. These work and conclusions provide an important theoretic al basis and practical experience for the improvement of fly-cutting Bragg grating on PMMA substrate.