Patent ID: 8822873

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: a liquid groove forming step for forming linear processing liquid grooves having a width that is smaller than a width of a slit-forming plate-shaped protrusion electrode, in positions for forming slits which form the partition walls of the honeycomb structure by subjecting the kneaded clay to extrusion in one side end face as a kneaded clay forming face of a plate-shaped die substrate having the one side end face and another side end face, an introduction hole forming step for forming a plurality of introduction holes for introducing the kneaded clay, the introduction holes communicating with the processing liquid grooves, in the another side end face to function as a kneaded clay introduction face of the die substrate before or after the liquid groove forming step, and a slit forming step for forming slits communicating with the introduction holes by performing comb-like electro-discharge machining by a comb-like electrode where a plurality of plate-shaped protrusion electrodes, each corresponding to the width of the slit, are disposed in positions including the processing liquid grooves on the one side end face as the kneaded clay forming face of the die substrate, wherein during the slit forming step the slits are formed by inserting the comb-like electrode in positions deviated from central axes of the processing liquid grooves.