Apparatus of preparing a molded article
View Patent ↗A sheet molding apparatus including at least one molding surface with a plurality of perforations, at least one sheet retainer with a plurality of vacuum perforations, and an accompanying vacuum mechanism for controllably drawing reduced pressure through the perforations. The sheet molding apparatus can be used for rapidly and accurately positioning thermoformable thermoplastic sheets to match the molding surfaces in producing molded articles.
1. A sheet molding apparatus comprising:
a. a first mold portion having an interior mold surface, and a perimeter edge, said interior mold surface having a contour and a plurality of perforations;
b. a first vacuum apparatus that is in fluid communication with said first mold portion, said first vacuum apparatus controllably drawing reduced pressure through said plurality of perforations of said interior mold surface of said first mold portion;
c. at least one sheet retainer having an upper surface, the upper surface of said sheet retainer having a plurality of perforations, said sheet retainer having a longitudinal axis that is oriented along at least a portion of said perimeter edge; and
d. a second vacuum apparatus that is in fluid communication with said sheet retainer, said second vacuum apparatus controllably drawing reduced pressure through said plurality of perforations of said upper surface of said sheet retainer,
wherein said sheet retainer is reversibly and controllably positionable along at least one of an x-axis, a y-axis and a z-axis relative to said perimeter edge, and said sheet retainer is rotatable around said longitudinal axis,
further wherein, said upper surface of said sheet retainer is dimensioned to retain a first portion of a second surface of a heated thermoplastic sheet on the upper surface of said sheet retainer, when said second surface of said first portion of said heated thermoplastic sheet is contacted with said upper surface of said sheet retainer and reduced pressure is drawn through said plurality of perforations of the upper surface of said sheet retainer, and
e. reversible positioning of said sheet retainer along at least one of said x-axis, said y-axis and said z-axis relative to said perimeter edge, and reversible rotation of said sheet retainer around said longitudinal axis, with said first portion of said second surface of a heated thermoplastic sheet being retained on the upper surface of said sheet retainer, assists a second portion of said second surface of said heated thermoplastic sheet being drawn to and matching the contour of said interior mold surface of said first mold portion when said second surface of said second portion of said heated thermoplastic sheet is contacted with said interior mold surface of said first mold portion and reduced pressure is drawn trough said plurality of perforations of said interior mold surface of said first mold portion.
2. The sheet molding apparatus of claim 1 further comprising:
a. an extruder having a terminal end; and
b. a sheet die, said sheet die being in fluid communication with said terminal end of said extruder;
wherein said first mold portion and said sheet retainer are together positioned and reversibly moveable in a plane beneath said sheet die, and said sheet die is substantially stationary.
3. The sheet molding apparatus of claim 2 wherein said first mold portion and said sheet retainer together reside on a platform, said platform being positioned and reversibly moveable in said plane beneath said sheet die.
4. The sheet molding apparatus of claim 1 wherein each sheet retainer independently has a plate shape, and is a plate sheet retainer having an interior edge and an exterior edge, said interior edge of said plate sheet retainer being closer to said perimeter edge of said first mold portion.
5. The sheet molding apparatus of claim 1 wherein the upper surface of each sheet retainer independently has a contour selected from the group consisting of flat contours, convex contours, concave contours and combinations thereof.
6. The sheet molding apparatus of claim 1 further comprising:
a. a second mold portion having an interior mold surface;
b. wherein said first mold portion and said second mold portion are reversibly positionable relative to each other such that the interior mold surface of said first mold portion and the interior mold surface of said second mold portion are in reversibly positionable facing opposition relative to each other.