Ceramic honeycomb structure and honeycomb-molding die
A ceramic honeycomb structure comprising large numbers of flow paths longitudinally formed by cell walls arranged in a lattice pattern in cross section, and an outer peripheral wall formed around the flow paths; in a cross section perpendicular to the longitudinal direction, fan-shaped bulges projecting in a fan shape toward the flow paths from cell wall intersections at which the cell walls are crossing; the circumscribed circles of circular portions of the fan-shaped bulges at all cell wall intersections having a constant radius; and when the distance between the center point of the circumscribed circle and the center point of the cell wall intersection is defined as a center point distance S, a center point distance So in the outer peripheral portion of the ceramic honeycomb structure and a center point distance Sc in the center portion meeting Sc<So.
1 . A honeycomb-molding die comprising supply holes for supplying a moldable material, and lattice-shaped slits for molding said moldable material to a honeycomb shape, which are formed on the opposite surface side to a surface side on which said supply holes are formed, with communication with said supply holes;
four corners of a die member at a slit intersection at which said lattice-shaped slits are crossing having circular recesses when viewed in the extrusion direction, said four circular recesses extending over the entire length of said lattice-shaped slits in the extrusion direction;
the inscribed circles of said four circular recesses at all slit intersections having a constant radius; and
when the distance between the center point of said inscribed circle and the center point of said slit intersection is defined as a die center point distance Sd, a die center point distance Sdc in a center portion of said honeycomb-molding die and a center point distance Sdo in an outer peripheral portion of said honeycomb-molding die meeting Sdc<Sdo.
2 . The honeycomb-molding die according to claim 1 , wherein in the outer peripheral portion of said die, the center point of said inscribed circle is positioned on the outer periphery side of said honeycomb-molding die with respect to the center point of said slit intersection.
3 . The honeycomb-molding die according to claim 1 , wherein a die center point distance Sdh at a slit intersection in an intermediate portion between the center and outer peripheral portions of said die meets Sdc<Sdh<Sdo.