Patent ID: 8779332

Claim:
A method for manufacturing a honeycomb structure forming die for subjecting kneaded clay as a raw material to extrusion forming in order to manufacture a honeycomb structure provided with porous partition walls separating and forming a plurality of cells functioning as fluid passages and having first cells having a predetermined opening area and second cells having a different opening area from that of the first cells disposed alternately, wherein the method comprises: an introduction hole forming step for forming, in a plate-shaped die substrate having one side end face and another side end face, a plurality of introduction holes for introducing kneaded clay on the another side end face to function as a kneaded clay introduction face, and a slit forming step for forming slits in the one side end face of the die substrate to communicate with the introduction holes in order to form the partition walls of the honeycomb structure by extruding the kneaded clay, by performing comb-like electro-discharge machining with a comb-like electrode having a support plate and a plurality of plate-shaped protrusion electrodes extending from the support plate and corresponding to a width of the slits, wherein during the slit forming step the protrusion electrodes of a first comb-like electrode are used to form portions of a first geometric slit pattern in the one side end face of the die substrate, and the protrusion electrodes of a second, different comb-like electrode are used to form portions of a second geometric slit pattern in the one side end face of the die substrate, and wherein the first geometric slit pattern formed by the first comb-like electrode is in a different position on the one end face of the die substrate from the second geometric slit pattern formed by the second comb-like electrode, and the second geometric slit pattern formed by the second comb-like electrode connects parts of the first geometric slit pattern formed by the first comb-like electrode.