Appeal No. 2002-1447
Application 09/167,776
solidified shell (final rejection mailed June 28, 2000, paper
no. 9, pages 3-4).
As for the appellant’s claim requirement that the casting
powder is supplied such that the height of the slag layer
proximate the upper surface of the mold is greater than or equal
to a height of a portion of a strand shell which penetrates the
slag layer during oscillation of the mold, the examiner argues
(answer, page 5):
Since Stahl discloses the slag layer as acknowledged by
appellants [sic], it is apparent that a powder
dispensing means must had [sic] been provided in order
to dispense the powder and form a slag layer on top of
the molten metal surface. Further, since [sic] the
purpose of providing a slag layer is (1) to lubricate
the interface between the mold and the solidified shell
in the continuous casting process and thereby to obtain
a cast strand with better surface quality; and (2) to
cover the molten metal surface within the continuous
casting mold such that to prevent the molten metal from
oxidizing. Therefore, it would have been obvious to
those of ordinary skill the casting art that the height
of the slag layer must be maintained higher than that
of strand shell such that to prevent the same from
oxidizing.
The examiner has not provided evidence that the purposes of
Stahl’s slag layer are those alleged by the examiner.
Regardless, even if the examiner is correct in this regard, the
examiner has not provided evidence that, in prior art thin slab
casting, the strand shell was known to protrude through the slag
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