| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程研究所 === 83 === In this study, a numerical simulation model for forward hot
extrusion process of tube has been developed. This numerical
si- mulation model combines the upper bound method with the
finite difference method, and it is proposed to predict the
deformation behaviors and forming load during the extrusion
process. Besi- des, in order to investigate the influence of
process variables to extrusion process, mechanical property
tests of the extruded tube are performed. The Kinematically
admissible velocity field of tube is de- rived , the energy
consumption can be calculated, and metal fl- ow pattern can be
obtained.Then, the finite difference method is applied to
predict the temperature distribution in the billet ,and in the
interface of billet and die during the extrusion process. For
the purpose of examining the availability of this numerical
simulation model, A6061 tubes are extruded at various
temperatures. The metal flow is observed on macro etched
section of the discard remained in the container, and the
charge welding seams in the cross-section of the extruded tubes
are observed by macro etching. The strength of welded portions
of extruded tube is evalua- ted by the expanding and
flattening tests. The expanding ratios of extruded tubes are
compared with those of seamless tubes pro- duced by machining
the same materials. It is found that the st- rength of the
extruded tubes is comparable to the tear streng- th of
billets. From the experimental and analytical results, the
optimal tube extrusion conditions can be found.
|
|---|
