Study On Temperature Distribution Mechanism And Structural Optimization In Micro-scale Warm Extrusion

With the growing demand for micro components, the microfabrication techniques such as LIGA, lithography, etching and other traditional ones could not satisfy the requirement of manufacturing complex three-dimensional products in mass. The plastic processing has the advantages including the low cost, high efficiency and precision. So the combination with micro-forming technology and conventional plastic processing, such as micro-extrusion and micro-stamping, has been widely developed. Most of the existing research on micro-extrusion is focused on micro-cold extrusion, which has difficulty in the high deformation resistance and uneven molding filling. Therefore, the micro-scale warm extrusion is proposed to decrease deformation resistance and increase the material fluidity. To solve the complexity and difficult control in the traditional heating system that influence the quality and cost of micro components, the laser-assisted heating method has been presented because of its high control ability, efficiency and ease of selective heating. The new method combining laser-heating with microforming can find its extensive applications in other microforming fields.In this paper, the basic theories including laser-heating and micro-scale warm extrusion are systematically studied. The laser-heating FE (Finite Element) modeling and temperature distribution are investigated. On the basis of the results, the forming simulation of micro-warm extrusion is made. The main work and results are as follows.1. The characteristics of micro-scale warm extrusion and the difference between micro and macro extrusion are discussed. The key problems in the simulation, such as meshing, thermal-mechanical coupling model and friction model, are investigated.2. Heat transfer theory is described. The temperature distribution of aluminum alloy using laser-heating method is studied through serial experiments. The FE modeling of laser-heating is set up based on ABAQUS. The influences of laser parameters including laser power, heating time and spot diameter, on temperature distribution are analyzed3. Double-sided laser-heating method is carried out and the uniform temperature distribution can be obtained by the optimization of laser parameter. The heating system of micro-scale warm extrusion which includes laser, optical path and detection device is designed and introduced.4. Forming process with double-sided laser heating method is simulated under different die structure parameters such as cone angle of femal die, die land length and cavity die radius. Finally, the die structure parameters are analyzed and optimized using orthogonal experiment method.