As bicycle design continues to develop, consumers are not satisfied with just the
convenience and power-saving features of bicycles, but they also demand a fancy
appearance. To achieve dramatic deforming of bike frames, an extreme
high-profile difference is required. Thus, this study used rotary swaging, which
is the best forging method among shrink forming processes, as the preforming
process. The tube diameter reduction rates of 0.28 and 0.31 were set as the main
parameters, and the effects of feeding speed, feeding method, and friction
factor on the formed tube were analyzed. The results indicated that a higher
feeding speed results in a lower rate of tube thickness increase and a lower
friction factor results in a lower rate of tube thickness increase. Regarding
the effects of feeding methods, the automatic feeding method yielded better
surface roughness than the manual method. However, the tube may interfere with
the swaging dies, causing serious damage to the tube surface. In summary, the
tube rotary swaging process can be conducted at tube diameter reduction rates of
0.28 and 0.31. However, owing to the roughly twofold increase in tube thickness
to more than 4 mm in some areas, the tube cannot fully fit the die face at these
reduction rates under the hydroforming process. The tube can only be completely
fitted to the die face at tube diameter reduction rates below 0.24.
