Dieless forming continuous

Given the preceding findings, a version of die-less forming was needed which did not force any temporary nondevelopable shapes (regardless of how small) upon the component. Such a version was explored and demonstrated by Yencho [15]. To emphasize the absence of discontinuities, he termed it continuous die-less forming [16]. 

Yencho then constructed the initial version of the machine and explored the parameters necessary to successfully form flaw-free parts. A key finding concerned the effects of trapped moisture. Despite the generally hydrophobic nature of PEEK, it was found that small amounts of moisture absorbed by the Gr/PEEK laminates subsequent to their manufacture converted into steam during the forming operation and caused extensive delamination. This was in 

D Best of Each Laminate Worst of Each Laminate Representative of Laminate 

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Figure 14.14 Schematic of the continuous dieless forming machine showing the vertically moving crosshead cylinder, the fixed forming roller, and the dead weights used for workpiece back tensioning...

Figure 14.16 (a) Circular Dual-Dee induction coil used in early work on the continuous dieless forming process, (b) Addition of ferrite flux concentrator to Dual-Dee coil, (c) Temperature patterns generated in a Gr/PEEK laminate by the circular Dual-Dee coil with ferrite flux concentrator. The coil end was located at various distances from the laminate edge. No one position produced a uniform temperature profile... 

Figure 14.19 (a) Overall view of the continuous dieless forming machine, (b) Close-up view of the continuous dieless forming machine, from the side opposite to that shown in (a)... 

Continuous dieless forming was then used to form both uniform-curvature and non-uniform curvature components. Good shape accuracy (i.e., maximum deviation of 0.4 mm or 0.016 in.) was attained. A key ingredient proved to be manipulation of the temperature gradient across the forming roller. 

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