Appeal No. 99-0158
Application 08/616,787
with an external diameter greater than the internal
diameter of the tube to be plugged; heating the plug
to the prescribed temperature for imparting its
“memory” configuration; thereafter cooling the same
to a temperature below the minimum limit of the
transition range of temperatures for the plug
material where the plug is imparted with its
“intermediate” configuration. Thereafter the plug
is applied to the tube to be plugged and heated to a
temperature above the upper limit of its transition
range whereby the tube is caused to attempt to
assume its memory configuration and in so doing is
expanded into tight plugging engagement within the
tube interior [column 2, lines 18 through 33].
According to the examiner,
even though Greacen fails to expressly state that
the plug has a higher coefficient of thermal
expansion than
that of the tube, Greacen is considered to stand for
such a proposition because it recognizes that the
thermal properties of two members can be utilized to
expand one member relative to the other.
Because one having ordinary skill in the art
recognizes that the most efficient use of the
Fields’ apparatus could be realized if the
pressurizing fluid was not allowed to escape from
the ends of the tube, one would have found it
obvious to employ the tube plugging method of
Greacen in the process of Fields in order to ensure
that no pressurizing fluid is allowed to escape
[from] the ends of the tube while the tube is being
deformed thereby. When the tube plugging method of
Greacen is incorporated into the process of Fields,
the end caps will press the tube ends against the
internal die surface.
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Last modified: November 3, 2007