Appeal No. 97-0576
Application No. 08/308,876
The subject matter on appeal is directed to an
apparatus for preheating thermoplastic material. Claim 9 is
exemplary of the invention and reads as follows:
9. An apparatus for preheating thermoplastic material
prior to entry of the material into an extruder barrel,
comprising:
an elongated housing having a central bore, an inlet
adjacent a first end of the housing, and an outlet between the
inlet and a second end opposite the first end of the housing,
both the inlet and the outlet intersecting the central bore;
a material flow path beginning at the inlet, continuing
through the central bore, and passing from the central bore
through the outlet;
a pair of adjacent, parallel feed screws received
within the central bore of the housing for blending the
thermoplastic material and advancing it along the material flow
path, each feed screw having
a main body section having a helical flight configured
to form a screw channel that is generally U-shaped in cross-
section and to advance the material from the inlet toward the
outlet when the feed screw is rotated,
an open section having a constant diameter, and
a terminal section having a helical flight configured
to form a screw channel that is generally U-shaped in cross-
section and with a lead opposite that of the main body section,
such that the main body section extends from the inlet
to the open section which is adjacent the outlet, and the
terminal section extends from the open section to the second end
of the housing;
drive means for rotating the feed screws in the same
direction within the central bore; and
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