Micro Laser Ablation Technique Of Line Gear

Gear is one of the most important basic mechanical parts which have potential applications in miniature transmission field for its compact structure and accurate transmission.For example,micro robot,micro power devices,medical devicesand small satellites.The contradiction between adaptation of micromanufacturing technologies and complexity of three-dimensional structure of micro gears blocks its promotion and application.Most of the existing manufacturing methods only adapt to involute cylindrical gear,and problems such as poor efficiency,low precision,and size limitation remain unsolved.This paper entitled “Laser Ablation Micromachining Method and Technology of Line Gear”,focuses on miniature gears adapted to space transmission in small scale and reduces the manufacturing difficulties of miniature gears from the origin of gear meshing principle.Based on laser ablation material removal characteristics,this paper presents miniature bevel line gear configurations and its laser milling process.The micro line gear design theory combining with laser micro processing technology is innovative and has a certain application prospect.The research in this paper is of greater academic value for promoting the development of research on micromechanical system.This paper reviews the research status and progress from three aspects: manufacturing technology of miniature gear,design theory and processing technology of line gear,laser milling technology.The main contents include:(1)Based on the characteristics of micro-machining,the line gear configuration with the Archimedes sparal as the driving contact designed,the mathematical equations of the contact curve and center curve of are derived,the 3D modeling of the linea gear pairs are bulit,and the accuracy of transmission is verified by kinematics experiments.The simplified design theory of pure rolling line gear pair with intersecting axis is studied.The mathematical form of driving and driven contact curves varie with the transmission ratio and transmission angle are studied.(2)Based on normal evaporation and phase explosion mechanisms,the surface morphology evolution model of nanosecond pulsed laser ablation of metal material is established,and the accuracy of the proposed model in the prediction of average morphology of ablative craters was verified by processing experiments.This paper studies the ablation geometry prediction method based on linear superposition of material removal.Taking straight ablation groove and square groove as examples,the precision and application range of the superposition removal model are analyzed,which lays a foundation for subsequent laser milling technology.(3)The shape precision of the micro cone is improved by using various analysis and optimization methods.The specific work includes: referring to the cone precision standard and measurement method,the data acquisition and analysis method of shape for micro cone and optical measurement is proposed.The symmetry coefficient of the scanning strategy is defined,and its influence on the symmetry error,cone Angle and diameter error of the micro cone is analyzed experimentally.The effects of laser power,repetition frequency,scanning speed,scanning path spacing and other laser milling parameters on the processing effect of the microcircular table were analyzed experimentally.The processing model of the micro-circular table with nanosecond laser pulse milling was established by artificial neural network.After adopting the above optimization methods,the shape accuracy of the micro cone table reaches level 11.(4)Combining the design theory of line gear and laser milling,miniature bevel line gear is designed along with its the two-step processing method: The removal target of the first step is the micro cone;and the removal target of the second step is the Archimedes column.The machining of the bevel line gear is completed in two steps.The experiment proveded that the proposed method can manufacture bevel line gear workpiece in the size range of 0.5mm-2mm,the cone Angle range of 60-180° and precision level of 11.The minimum thickness of the tooth is 20μm.