| Summary: | 碩士 === 國立成功大學 === 機械工程研究所 === 84 === Owing to the effect of friction is very important for the
surface of a workpiece during the metal forming. However, the
most of previous researchers give a constant friction factor or
use the curve of ring compression accompanying with experiment
to decide the friction factor to analyze the process of the
metal forming, but we can not know whether the constant
friction is right or not. In addition, the major shortcoming of
this method is that too many experiments must be carried out
under the different operational condition. Therefore, an
efficiency and new method is proposed in this paper to predict
the constant friction factor between the workpiece and die. For
a preliminary study the feasibility of the present method the
upsetting is used to access the effect of the operational
conditions on the friction factor. In direc analysis , the
rigid-viscoplastic material and incompressible condition. In
inverse analysis, the friction factor is predicted by using the
golden section method accompanying with experiment, in which
the relationship between load and displacement are obtained.
The influence of the operational conditions and different
materials of the workpieces on the friction factor can be
verified and accessed. From the obtained results of this study,
this inverse method is reliable and provide a fast way to
predict the friction coefficient. Furthermore, the friction
factor is smaller when the velocity of die is increased or the
material of the workpiece is harder.
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