Appeal No. 97-4183
Application 08/424,128
1, lines 26-36).
It would have been obvious to one of
ordinary skill in the art at the time the
invention was made to open the initially
closed nozzle(s) in the drill bit of Miller
et al ’346 . . . for reasons other than
erosion, plugging or lost circulation
control in view of the teaching of Kistler,
Jr. ’413. [Answer, pages 4 and 5.]
The appellants, on the other hand, argue that:
Miller et al ’346 teaches a bit having
two nozzle systems, and when the first
nozzles become eroded from flow they are
closed and a second set of nozzles is
opened while the bit is at the bottom of a
well. The invention is related to the
problem of nozzle erosion. . . . Kistler
’413 discloses a shear relief valve to be
placed in a bit and expelled if the bit
flow passages become plugged and ?... is
controllably expellable in other
circumstances? (Kistler ’413 at col. 1,
lines 56, 57). Kistler ’413 in the
Background section of the patent, also
discusses various conditions under which
replaceable nozzles in a bit would
desirably be changed. It is perfectly
clear that the teachings of Kistler ’413
apply to changing the nozzles on the
surface of the earth, while drilling has
been interrupted. [Brief, pages 3 and 4.]
We are unpersuaded by the appellants’ arguments.
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