A. Masoumi et G. Craggs, DESIGN OF STRAIN-RATE-CONTROLLED DIES FOR THE DIE DRAWING OF POLYMER SHEET, Journal of materials processing technology, 72(3), 1997, pp. 407-412
The die-drawing process may be used to achieve orientation of the mole
cular structure of a polymer and thereby considerably enhance its stre
ngth and stiffness. The effect of controlling the strain rate within a
die by suitable design of the die profile has been investigated and s
train-rate control is seen as a means of reducing product fracture dur
ing processing. A method of designing a die profile is given in detail
and manufactured dies having profiles where the strain rate either in
creases, decreases or remains constant throughout the die have been te
sted experimentally. Conventional taper dies are found to produce prod
uct fractures at relatively low billet velocities, but the products ha
ve a high draw ratio. The draw ratios achieved in constant-strain-rate
dies are lower, with considerably higher billet speeds being achieved
, particularly when using dies having a draw ratio of six. (C) 1997 El
sevier Science S.A.