| 摘要 |
An extrusion control system and method controls the cross section and viscosity in the process of extruding even hard to control plastics like polyurethane. Cross section, A, is determined by measuring volumetric rate of delivery of melt through a gear pump V/t and the speed of the extrudate at a puller N/t. The cross-sectional area, <math-cwu id="MATH-US-00001"> <NUMBER>1</NUMBER> <MATH> <MROW> <MROW> <MI>A</MI> <MO>=</MO> <MFRAC> <MROW> <MI>V</MI> <MO>/</MO> <MI>t</MI> </MROW> <MROW> <MI>N</MI> <MO>/</MO> <MI>t</MI> </MROW> </MFRAC> </MROW> <MO>,</MO> </MROW> </MATH> <mathematica-file id="MATHEMATICA-00001" file="US20040032040A1-20040219-M00001.NB"/> <image id="EMI-M00001" wi="216.027" he="18.00225" file="US20040032040A1-20040219-M00001.TIF" imf="TIFF" ti="MF"/> </MATH-CWU> is controlled by controlling the puller speed. Pressure drop across the die, P, and the volume of melt delivered by the gear pump are measured and a term indicative of the viscosity of the melt is determined based on <math-cwu id="MATH-US-00002"> <NUMBER>2</NUMBER> <MATH> <MROW> <MROW> <MI>Vs</MI> <MO>=</MO> <MFRAC> <MI>KP</MI> <MI>V</MI> </MFRAC> </MROW> <MO>,</MO> </MROW> </MATH> <mathematica-file id="MATHEMATICA-00002" file="US20040032040A1-20040219-M00002.NB"/> <image id="EMI-M00002" wi="216.027" he="17.03835" file="US20040032040A1-20040219-M00002.TIF" imf="TIFF" ti="MF"/> </MATH-CWU> Vs being the viscosity and K being a constant dependent on the size and shape of the die orifice. Viscosity variations are compensated by varying heat applied to the melt.
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