Patent ID: 7364034

Claim:
An adjustable aperture apparatus that retains dust from material directed through the apparatus, the apparatus comprising: a tube having a cylindrical interior surface that surrounds an interior bore of the tube, the tube having a length that extends from a top edge of the tube that surrounds a top opening to the interior bore to a bottom edge of the tube that surrounds a bottom opening to the interior bore, the tube cylindrical interior surface having a center axis that extends through the tube interior bore and defines mutually perpendicular axial and radial directions relative to the tube; a plurality of plates in the tube interior bore, each plate having a radially outer edge positioned adjacent the tube interior surface, a radially inner edge opposite the radially outer edge and a pair of side edges between the radially outer edge and the radially inner edge with the pair of side edges converging as the pair of side edges extend from the radially outer edge toward the radially inner edge, and each plate having opposite top and bottom surfaces that face the respective top and bottom edges of the tube; a plurality of pivoting connections connecting the plurality of plates to the tube for pivoting movement of the plurality of plates between closed positions where the plurality of plates extend radially into the tube interior bore from the radially outer edges to the radially inner edges, and opened positions where the plurality of plates extend axially through the tube interior bore from the radially outer edges to the radially inner edges; and, a plurality of springs operatively connected between the plurality of plates and the tube with the plurality of springs urging the plurality of plates to the closed positions.