Appeal 2007-0136
Application 90/006,222
its discussion of the prior-art Findeisen patent.13 According to BHI,14
Findeisen—
discloses a method of manufacturing cast carbide pellets that
are generally spherical in shape and have improved mechanical
and metallurgical properties over prior-art carbide pellets.
These cast pellets are not truly spherical, but are sufficiently
symmetrical that residual stresses in the pellets are minimized.
Also, the generally spherical shape of these pellets eliminates
corners, sharp edges, and angular projections, which are present
in conventional crushed particles, that increase residual stresses
in the particles and tend to melt as the hardfacing composition
is applied to the surface.
In view of BHI's disclosure, one skilled in the art would have understood
"generally spherical" to be functionally driven to mean substantially free of
corners, sharp edges, and angular projections that might promote melting.
In claim 19, a portion of the matrix metal is used to form a tube that is
"filled" with the carbide pellets. Since only "a portion" of the metal forms
the tube, the claim is open to the remaining metal being used as additional
filler for the tube or as external excess (i.e., the composition is tubes plus
excess metal). Similarly, the claim requires the tube to be filled with the
pellets, but does not require the capacity of the tube to exactly match the
volume of pellets. Consequently, the pellets could be part or all of the fill,
and also form an external excess (i.e., tubes plus excess carbide).
OBVIOUSNESS
In analyzing obviousness, the scope and content of the prior art must
be determined, the differences between the prior art and the claims
13 E. Findeisen et al., "Process of manufacturing cast tungsten carbide
spheres", U.S. Patent 5,089,182 (granted 18 February 1992).
14 Spec. 2:1-12.
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