(under subclass 57) Subject matter comprising a step of, or means for, the forcible engagement of pressurized fluent material with the interior surface of work, at least a portion of which has a closed periphery cross-section so that upon deformation of the work the interior area of said cross-section is enlarged.
(1) Note. In many instances, the actuated tool engages an end of a tubular workpiece to upset to work while simultaneously trapping and imparting pressure to fluid within the work. See Fig. B in appended diagram.
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54, for constricting or collapsing hollow work by fluid pressure on the exterior thereof.
