The Research Of Coniferous Timber Superfine Wood Flour Cell Lysis Mechanism And Its Preparation Method

Wood flour is widely used in a number of areas such as building materials, agriculture, plastics, chemical, metallurgical and environmental. Wood flour processing raw materials are different species sawdust. They are easily obtained, cheap and abundant raw materials. If added the amount to ultrafine composite polymer materials, they will produce a new multifunctional materials.Used the microscope to observe the larch sawdust, the fracture shape is very irregular. After amplification observations, we observed significant cracks within some of the particles. After high magnification observation, observed micro cracks in some sawdust. These cracks appear related to two factors, one is the test materials is larch, is a radical change material, micro-cracks may occur in the growth process; another sawdust has been processed, in the process had been cause internal micro cracks by the external forces. According to the observation results, the dried sawdust can be assumed to be a brittle laminate. The fracture mode of the wood fibers is separation until fracture between the tracheid, can destroy the honeycomb structure transverse of the softwood transverse, and another is that the tracheids is fracture in the longitudinal direction, so that the tracheid shorter. Based on the microscopic structure of the larch to superfine processing must do cell wall broken. Knowledge of fracture mechanics, structural mechanics and finite element theory calculate the size of the force of the wood cell wall, provides a theoretical basis for the ultra-fine wood flour machining tool spindle design. Available cellular structure to simulate the softwood tracheid structure, application of J integral in the fracture mechanics theory, simulation of Xingan Larch earlywood tracheids tensile deformation of radial force until fracture process and calculate the force in the process of cell wall structure deformation and damage. Compared the theoretical calculation results with the domestic and foreign different species of cell wall fracture experimental study results, obtained the early wood fiber breaking strength range. And apply the structural mechanics and finite element related knowledge in Xingan Larch cell wall structure to model as linear elastic truss structure. According to the structure characteristics of truss with rod unit to compressive stress, calculate the micro mechanics model, and cpmpard the calculation results and the traditional cutting theory, drawed the cutting force of cell wall fracture, provided the theoretical reference for the superfine wood powder machine tool, spindle design.Superfine wood flour processing belongs fiber materials the superfine processing, it is the difficulty of ultrafine powder preparation technology. Fiber material toughness, impact alone, extrusion, grinding force is difficult to ultrafine. The composite force field applying strong shear force and strong grinding force combining for the fiber material needs to be possible to reach the micron or submicron size. Superfine wood flour machine design mechanical force to crush the force field, the prominent shear and the role and impact of grinding, mixing, friction force interaction crushed materials. Based on advanced manufacturing technology of powder in the domestic and foreign about Superfine wood flour. And according to the characteristics of wood flour processing, paid attention to the design of cooling equipment. Research and development of superfine wood powder machine can realize the high mesh wood powder and grade separation. Conclude the wood flour processing relationship among mesh, time, cutter and cutter spacing.Current separation, grading equipment comparative analysis and test characteristics of the preparation of ultra-fine wood flour, cyclone separation equipment, it mainly collected powder dry powder-based, low manufacturing costs, easy maintenance, inactivity member, pressure drop constant, the main disadvantage is the presence of the particle separation efficiency of the small particle size is low. Design in cyclone structure design based on the classic model of the cyclone, the theoretical calculations based on the equilibrium orbit model of cyclone separation performance, comparing the calculation results with the powder shape and size of the definition, the design a separating apparatus is able to achieve the desired performance. Empirical model and dissipation loss model and the calculation of the voltage drop across the cyclone separator and the use of computational fluid dynamics software to simulate the gas flow field in the cyclone separator and the state of motion of the particles of different size of wood flour. The high-speed jet stream so that the flow of the laminar flow in the spiral separator of the wood meal in the collection box, dry-type pneumatic classifier used in the wood flour grading jet pre-dispersed centrifugal fan reaches the classification of the wood powder.Test preparation different mesh wood flour powder physical properties of experimental study it, can be drawn with the gradual increase of wood flour mesh, wood flour color will gradually deepen. This is its corresponding processing time also gradually extended due to the higher the mesh number of the wood powder, wood flour in the process to heat the more carbonization more remarkable. Sawdust particles during processing as the processing time by laminar, sheet, rod, needle, until the results of the last observed filamentous. Different mesh wood flour test measured with the higher density of the mesh becomes large, the porosity of the powder particles becomes small, between the particles increased coordination number, powder compressibility becomes small. The main force under normal powder van der Waals force, its magnitude can calculate the size of the reunion of wood flour, wood flour mesh greater the higher the number of its reunion, but defined in superfine wood flour stable under normal conditions within the mesh wood flour reunion is not easy.