关键词: 纳秒激光, 微米木纤维, 扫描电镜(SEM), 绝对温升

Abstract: [Objective] In this paper, based on the qualitative analysis of the formation process of micro fiber, the cutting theory of micron wood fiber processed by nanosecond laser processing was presented in the light of the principle of energy saving and consumption reduction. Through the experimental study of cell wall cracking on the surface of micro fiber, the power consumed by the cell wall was obtained.[Method] Scanning electron microscopy (SEM)method was used to study the deformation of burning. Based on laser heating and cutting, along the cell texture heating the wood tissue fluid, the tissue fluid within cells was gasificated and the cell expanded rapidly, internal pressure soared, leading to cell wall burst, then obtained the burr shaped fiber. At last,the micro/nano filaments were cut along the wood grain direction by laser cutting head. Through the analysis of power consumption of fiber processing, a series of modern analysis methods consisting of cytology, ultra precision machining theory, fiber and so on were applied to wood fibers formed in the process, and puts forward the calculation method of micron wood fiber laser cutting and the concept of cell lysis ability.[Result] The formula of equivalent cutting force and cutting power was obtained from the micro angle of the cell wall by means of the laser to the cutting of the micron wood fiber. With increasing frequency, degree of the burning in turn enhanced, the resulting cracks and grooves more intensive and deepened. The absolute temperature rise was large, and the surface of the specimen was produced by the slip. Absolute temperature rise was calcutaled by ΔT=∫₀^εf(βσ)/(ρC_m)dε.[Conclusion] Using laser to the micron meter wooden fiber energy equation to of micron wood fiber equivalent cutting force and cutting power formula derivation, and clarify the loading force of fiber in the micron wood fiber burning process and the corresponding parameters. Therefore,this study focused on the microstructure of cell lysis ability during laser cutting of micron wood fiber, through the analysis of fiber production and equivalent cutting force change, and put forward the way that along the wood surface using longitudinal laser heating burst the cell wall could save the energy consumption. The surface cracking mechanism of micro nano wood fiber cell wall were analyzed by the physical and mathematical formula derivation based on the Drescher fine close theory, the mechanics model of micro nano wood fiber was built and the cell wall cutting power calculation formula were derived. Using Fraxinus mandshurica as example to carry out wood cell wall surface burst experiment, for the micron wood fiber processing, the cutting power of cell wall was calculated and the high quality of micron size filament wood fiber was produced. This study provided the important theory basis for the application and promotion of China's micro nano wood fiber.

Key words: nanosecond laser, micron wood fiber, scanning electron microscope (SEM), absolute temperature rise