Heated die lips for controlling extruded polymer film thicknesses
OwnerJ. Gregory Moriarityinventor
Life of this patent
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Abstract
Lip die structures include thrust developing elements spaced along one lip at first points for flexing those first points toward and away from the other lip and controlled by a thickness monitor spaced downstream along the web being produced from the lip die. First heating elements are carried by the one lip aligned with the thrust developing elements and are controlled by the thickness monitor to selectively heat the first heating elements responsive to monitored decreases in web thickness. Second heating elements are also carried by the first lip intermediate the first heating elements and are controlled by the thickness monitor to actuate, selectively, the second heating elements responsive to monitored decreases in thickness of said web.
Claims6
A lip die structure including a pair of elongated, laterally spaced lips defining an extrusion slot therebetween having an exit opening from which to extrude molten resin into a web, said die structure including a plurality of thrust elements spaced longitudinally along one of said lips operative to flex said one lip toward and away from the other lip at spaced locations, a measuring component continuously monitoring the thickness of said web and being operative to selectively actuate said thrust elements to flex said one lip toward and away from said other lip selectively at said spaced locations responsive to increases and decreases, respectively, of monitored thickness of said web at points spaced thereacross in alignment with said spaced locations, and a plurality of heating elements longitudinally spaced along said one lip adjacent said exit opening for selectively heating said one lip at selected points spaced therealong, said plurality of heating elements including first and second heating elements, said first heating elements being at selected points in alignment with the spaced locations for flexing said one lip by said thrust elements and said second heating elements being at points spaced between said first heating elements, said measuring component also being operative to selectively actuate and deactuate any of said heating elements responsive to decreases and increases, respectively, of monitored thickness of said web at points spaced thereacross in alignment with said selected points.
A lip die structure including a pair of laterally spaced lips defining an extrusion slot therebetween having an exit opening from which to extrude continuous molten resin, said die structure including a plurality of thrust elements spaced along one of said die lips to mechanically flex said one lip toward and away from the other said lip at selected first points along said one die lips a plurality of heating elements including first and second heating elements spaced along said one die lip adjacent said exit opening, said first heating elements being at selected points substantially in alignment with said first points and said second heating elements being at points spaced between said first heating elements, a measuring component continuously monitoring the thickness of said extruded resin at points downstream from said exit opening which are spaced to correspond to said first points, said measuring component being operative to selectively actuate and deactuate said heating elements responsive to decreases and increases, respectively, of monitored thickness of said extruded resin at said points downstream, said actuation of said selected heating elements causing lateral flow of said resin into areas adjacent said activated heaters.
Dependencies are inferred from the claim text.