Flap wheel assembly

A flap wheel assembly comprising:

• a hub, said hub having an axis, a central cross section perpendicular to said axis having a circular periphery of a first diameter around said axis, opposite circular end cross section perpendicular to said axis, axially spaced on opposite sides of said central cross section and having circular peripheries around said axis of second diameters substantially larger than the diameter of said central cross section, a peripheral surface comprising a multiplicity of straight elongate surface segments extending between the peripheries of said end cross sections across and contacting the periphery of said central cross section each crossing at a different radius of said central cross section from said axis and being disposed at the same angle with respect to said axis measured about the radius crossed by the surface segment;
• a plurality of rectangular flap members each having a generally uniform width and a straight edge portion of a length about equal to the length of said segments;
• and
• means along and generally parallel to said segments for holding the straight edge portions of said flap members in spaced relationship around the peripheral surface of said hub with the width of said flap members projecting outwardly of said hub to afford, upon rotation of said hub, engaging distal portions of said flap members with a generally cylindrically convex surface generally uniformly along the lengths of said flap members.

A hub for a flap wheel assembly, said hub comprising at least a part of a hyperboloid of revolution of one sheet having an axis, a central cross section perpendicular to said axis having a generally circular periphery of a first diameter around said axis, opposite circular end cross sections perpendicular to said axis, axially spaced on opposite sides of said central cross section and having circular peripheries around said axis of second diameters substantially larger than the diameter of said central cross section, a peripheral surface comprising a multiplicity of generally straight elongate surface segments extending between the peripheries of said end cross sections across and contacting the periphery of said circular central each crossing said central cross section at a different radius of said central cross section from said axis and being disposed at the same angle with respect to said axis measured about the radius crossed by the surface segment, said part having end surfaces generally at right angles to said axis and including essentially all of the hyperboloid of revolution between said end surfaces;

• said hub having a plurality of straight elongate slots spaced around said periphery, each slot opening through and extending parallel to and along one of said segments between said end surfaces and being larger in cross sectional area at a location spaced from said peripheral surface than adjacent said peripheral surface.

A hub for a flap wheel assembly, said hub comprising at least a part of a hyperboloid of revolution of one sheet having an axis, a central cross section perpendicular to said axis having a generally circular periphery of a first diameter around said axis, opposite circular end cross sections perpendicular to said axis, axially spaced on opposite sides of said central cross section and having circular peripheries around said axis of second diameters substantially larger than the diameter of said central cross section, a peripheral surface comprising a multiplicity of generally straight elongate surface segments extending between the peripheries of said end cross sections across and contacting the periphery of said circular central each crossing said central cross section at a different radius of said central cross section from said axis and being disposed at the same angle with respect to said axis measured about the radius crossed by the surface segment, said part having end surfaces at generally right angles to said axis and including essentially all of the hyperboloid of revolution between said end surfaces;

• said hub having a plurality of means along and generally parallel to said segments each adapted for holding a straight edge portion of a generally rectangular flap member with the width of said flap member projecting outwardly of said hub to afford, upon rotation of said hub about said axis, engaging distal portions of said flap member with an arcuate convex surface generally uniformly along the length of said flap member.