Method for manufacturing cylindrical honeycomb fired body

A method for manufacturing a cylindrical honeycomb fired body, the cylindrical honeycomb fired body comprising an outer peripheral side surface, and partition walls disposed on an inner peripheral side of the outer peripheral side surface and partitioning a plurality of cells forming flow paths from a first end surface to a second end surface, the method comprising:

• a step A of preparing a cylindrical honeycomb formed body by extrusion molding a green body comprising a ceramic raw material, a pore-forming material, a binder and a dispersion medium through a die defining an opening shape of the plurality of cells and an annular mask located downstream of the die and having an inner peripheral contour for defining an outer peripheral contour of the first end surface and the second end surface, such that a direction in which the cells extend is horizontal and a front side in a traveling direction of the extrusion molding is the first end surface, and a rear side is the second end surface, and then by cutting to a predetermined length;
• a step B of obtaining a cylindrical honeycomb dried body by drying the cylindrical honeycomb formed body;
• a step C of calculating:
• (D1MAX+D4MAX+D6MAX)−(D2MAX+D5MAX+D8MAX)=EMAX1,
• (D3MAX+D6MAX+D8MAX)−(D2MAX+D4MAX+D7MAX)=EMAX2,
• (D2MAX+D5MAX+D8MAX)−(D1MAX+D4MAX+D6MAX)=EMAX3, and
• (D2MAX+D4MAX+D7MAX)−(D3MAX+D6MAX+D8MAX)=EMAX4,
• in which, assuming that a cross-section perpendicular to the direction in which the cells of the cylindrical honeycomb dried body extend is observed from the front side in the traveling direction of the extrusion molding of the step A, and a location on the outer peripheral side surface located at a vertex during the extrusion molding in the step A is 0 rad, with a clockwise direction as a + direction, D1MAX is defined as a maximum value of distance between a center of gravity position O and an outer peripheral contour of the cross-section in a central angle (rad) from −⅛π to +⅛π, D2MAX is defined as a maximum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +⅛π to +⅜π, D3MAX is defined as a maximum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +⅜π to +⅝π, D4MAX is defined as a maximum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +⅝π to +⅞π, D5MAX is defined as a maximum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +⅞π to +9/8π, D6MAX is defined as a maximum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +9/8π to +11/8π, D7MAX is defined as a maximum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +11/8π to +13/8π, and D8MAX is defined as a maximum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +13/8π to +15/8π;
• a step D of specifying a minimum value among EMAX1, EMAX2, EMAX3, and EMAX4 calculated in the step C;
• a step E of obtaining the cylindrical honeycomb fired body by placing the cylindrical honeycomb dried body on a shelf plate and firing the cylindrical honeycomb dried body while passing it through a continuous firing furnace, such that the direction in which the cells of the cylindrical honeycomb dried body extend is parallel to a vertical direction and:
• when the minimum value is EMAX1, a location on the outer peripheral side surface corresponding to 0 rad is positioned at the front side in the traveling direction of the extrusion molding,
• when the minimum value is EMAX2, a location on the outer peripheral side surface corresponding to 4/8 π rad is positioned at the front side in the traveling direction of the extrusion molding,
• when the minimum value is EMAX3, a location on the outer peripheral side surface corresponding to 8/8 π rad is positioned at the front side in the traveling direction of the extrusion molding, and
• when the minimum value is EMAX4, a location on the outer peripheral side surface corresponding to 12/8 π rad is positioned at the front side in the traveling direction of the extrusion molding.

A method for manufacturing a cylindrical honeycomb fired body, the cylindrical honeycomb fired body comprising an outer peripheral side surface, and partition walls disposed on an inner peripheral side of the outer peripheral side surface and partitioning a plurality of cells forming flow paths from a first end surface to a second end surface, the method comprising:

• a step A of preparing a cylindrical honeycomb formed body by extrusion molding a green body comprising a ceramic raw material, a pore-forming material, a binder and a dispersion medium through a die defining an opening shape of the plurality of cells and an annular mask located downstream of the die and having an inner peripheral contour for defining an outer peripheral contour of the first end surface and the second end surface, such that a direction in which the cells extend is horizontal and a front side in a traveling direction of the extrusion molding is the first end surface, and a rear side is the second end surface, and then by cutting to a predetermined length;
• a step B of obtaining a cylindrical honeycomb dried body by drying the cylindrical honeycomb formed body;
• a step C of calculating:
• (D1MIN+D4MIN+D6MIN)−(D2MIN+D5MIN+D8MIN)=EMIN1,
• (D3MIN+D6MIN+D8MIN)−(D2MIN+D4MIN+D7MIN)=EMIN2,
• (D2MIN+D5MIN+D8MIN)−(D1MIN+D4MIN+D6MIN)=EMIN3, and
• (D2MIN+D4MIN+D7MIN)−(D3MIN+D6MIN+D8MIN)=EMIN4,
• in which, assuming that a cross-section perpendicular to the direction in which the cells of the cylindrical honeycomb dried body extend is observed from the front side in the traveling direction of the extrusion molding of the step A, and a location on the outer peripheral side surface located at a vertex during the extrusion molding in the step A is 0 rad, with a clockwise direction as a + direction, D1MIN is defined as a minimum value of distance between a center of gravity position O and an outer peripheral contour of the cross-section in a central angle (rad) from −⅛π to +⅛π, D2MIN is defined as a minimum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +⅛π to +⅜π, D3MIN is defined as a minimum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +⅜π to +⅝π, D4MIN is defined as a minimum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +⅝π to +⅞π, D5MIN is defined as a minimum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +⅞π to +9/8π, D6MIN is defined as a minimum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +9/8π to +11/8π, D7MIN is defined as a minimum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +11/8π to +13/8π, and D8MIN is defined as a minimum value of distance between the center of gravity position O and the outer peripheral contour of the cross-section in a central angle (rad) from +13/8π to +15/8π;
• a step D of specifying a minimum value among EMIN1, EMIN2, EMIN3, and EMIN4 calculated in the step C;
• a step E of obtaining the cylindrical honeycomb fired body by placing the cylindrical honeycomb dried body on a shelf plate and firing the cylindrical honeycomb dried body while passing it through a continuous firing furnace, such that the direction in which the cells of the cylindrical honeycomb dried body extend is parallel to a vertical direction and:
• when the minimum value is EMIN1, a location on the outer peripheral side surface corresponding to 0 rad is positioned at the front side in the traveling direction of the extrusion molding,
• when the minimum value is EMIN2, a location on the outer peripheral side surface corresponding to 4/8 π rad is positioned at the front side in the traveling direction of the extrusion molding,
• when the minimum value is EMIN3, a location on the outer peripheral side surface corresponding to 8/8 π rad is positioned at the front side in the traveling direction of the extrusion molding, and
• when the minimum value is EMIN4, a location on the outer peripheral side surface corresponding to 12/8 π rad is positioned at the front side in the traveling direction of the extrusion molding.