Appeal No. 1999-1778
Application No. 08/888,365
is designed to be mounted by the aforementioned expansion
process. In Booth, all of the internal ribs are the same, that
is, Booth does not provide any relatively large convex portion
(such as element (6) of Fujimoto) for taking up expansion
forces. Booth states that the expansion process causes problems
when mounting ribbed tubes of the type disclosure therein.
Specifically, Booth states that “with rifle tube [i.e., an
internally ribbed tube] the stress caused by the expansion
process is increased in the thin part of the tube wall, causing
the tube to split if there is even a minimal defect in the tube”
(column 2, lines 15-18). Booth contends however, that by
“increasing the amount of wall available (bottom wall to fin
wall ratio) to accommodate the required expansion, the[2]
likelihood of the tube splitting can be reduced” (column 2,
lines 19-22). Concerning this splitting phenomenon, Booth
states that “[it] is believed to be due to the necessity for
sections of the tube between the fins to accommodate the stretch
required by the expansion process, which necessarily caused
2Booth defines the terms “bottom wall distance” and “fin
wall distance” in the paragraph spanning columns 3 and 4.
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