Microforming: Experimental investigation of the extrusion process for micropins and its numerical simulation using RKEM
Microforming: Experimental investigation of the extrusion process for micropins and its numerical simulation using RKEM
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DOI：
10.1115/1.1813468
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发表时间：
2004-11-01
影响因子：
4
通讯作者：
Swanson, A
中科院分区：
文献类型：
--
作者：
Cao, J;Krishnan, N;Swanson, A
使用小型机器（或所谓的台式机器）的微成形是使用全尺寸重型设备制造微型零件的替代新方法。微型零件通常定义为至少二维尺寸在亚毫米范围内的零件或结构，广泛用于电子和微机械产品中。然而，当将常规成形工艺按比例缩小到微米级时，需要考虑所谓的尺寸效应的影响。单个微观结构（晶粒的尺寸、形状和取向）和界面条件对工艺特性有显著影响。本文研究了挤压工艺，以确定其为一种可行的微成形工艺。一个成形组件的制造和使用结合加载子阶段挤出微针的最终直径为1毫米。晶粒尺寸的影响进行了研究，通过使用工件热处理，以产生不同的晶粒尺寸从32微米到211微米。采用两种不同粗糙度的挤压模具，研究了表面光洁度对挤压件成形的影响。虽然实验会带来有趣的问题和新的发现，但理论或数值解决方案是过程优化的必要工具。在这里，知道当前广泛使用的数值模拟工具的限制[即，有限元法（FEM）]，最近开发了一种新方法，即再生核元法（RKEM），以解决FEM的局限性（例如，重新网格化问题），同时保持FEM的优点，例如，多项式再生性和函数插值性。采用新的RKEM方法对微挤压问题进行了数值模拟。并将计算结果与有限元计算结果和实验结果进行了比较。结果令人满意。未来的实验和模拟工作的方向进行了讨论。
Microforming using a small machine (or so-called desktop machine) is an alternative new approach to those using full-size heavy equipment for manufacturing microparts. Microparts are commonly defined as parts or structures with at least two dimensions in the submillimeter range, which are used extensively in electronics and micromechanical products. However when scaling down a conventional forming process to microscale, the influence of the so-called size effect needs to be considered. The individual microstructure (size, shape, and orientation of grains) and the interfacial conditions show a significant effect on the process characteristics. In this paper the process of extrusion is investigated to establish it as a viable process for microforming. A forming assembly is fabricated and used in conjunction with a loading substage to extrude micropins with a final diameter of 1 mm. The effect of grain size is investigated by using workpieces heat treated to produce grain sizes varying from 32 mum up to 211 mum. Two extrusion dies with different roughness are used to study the effect of surface finish. While experiments lead to interesting questions and new discoveries, theoretical or numerical solutions are necessary tools for process optimization. Here, knowing the limits of the current widely used numerical simulation tools [i.e., the Finite Element Method (FEM)], a new method, the Reproducing Kernel Element Method (RKEM), has recently been developed to address the limitations of the FEM (for example, remeshing issue), while maintaining FEM's advantages, e.g., the polynomial reproducing property and function interpolation property. The new RKEM method is used to simulate the microextrusion problem. Its results are compared with that obtained from the FEM and the experiment result. Satisfactory results were obtained. Future directions on the experimental and simulation work are addressed.