Undulated-wall honeycomb structure and manufacturing method thereof

An undulated-wall honeycomb structure having a plurality of cell passages defining a cell passage direction, which are mutually parallel in the cell passage direction;

• wherein
• (1) intersection portions between walls defining said cell passages have a predetermined pitch in cross-sections perpendicular to said cell passages and are located in a pattern,
• (2) each of said cell passages has an adjacent pair of undulating wall face portions of said walls excluding said intersection portions, each undulating wall face portion having an undulated shape including recessions and protrusions in both the cell passage direction and a cross-sectional direction perpendicular to said cell passage direction, and
• (3) for each cell passage, the undulating wall face portions of the adjacent pair are positioned such that (i) corresponding protrusions of each of the adjacent undulating wall face portions face one another and corresponding recessions of each of the adjacent undulating wall face portions face one another or (ii) corresponding protrusions of one of the adjacent undulating wall face portions face recessions of the other,
• (4) an adjacent pair of flat wall face portions is located opposite the adjacent pair of undulating wall face portions, and
• (5) said undulated-wall honeycomb structure comprises at least 56 of said cell passages.