Patent ID: 7335848

Claim:
A process for producing a die usable for formation of a honeycomb structure, which comprises forming, at one of surfaces of a plate-like base material for die, slits having a hexagonal cell shape to be used for extrusion of a honeycomb structure having hexagonal honeycomb cells and, at the rest surface of the base material for die, backside holes each communicating with one of the slits, in which process holes for dielectric fluid each having an opening diameter smaller than the width of said slit are formed to a predetermined depth at said one of surfaces of the base material for die at the positions corresponding to at least one of the six vertexes of each hexagon constituting the hexagonal honeycomb shape of said honeycomb structure to be extruded; and said backside holes each communicating with said holes for dielectric fluid are formed at said other end of the base material for die, and a discharge electrode for electrical discharge machining is provided at a position apart by a predetermined distance from said one of surfaces of the base material for die in which the backside holes and the holes for dielectric fluid have been formed, so as to cover at least part of the openings of the holes for dielectric fluid; while a dielectric fluid for electrical discharge machining is being passed from said the other surface of the base material for die to said one of surfaces of the base material for die via the backside holes and the holes for dielectric fluid, electrical discharge machining is conducted at the one of surfaces of the base material for die until the machining proceeds to a position communicating with each backside hole; thereby, said slits having a hexagonal cell shape are formed at said one of surfaces of the base material for die.