Patent ID: 8795017

Claim:
A method for manufacturing electrodes for a spark plug comprising: a supply step of supplying a plurality of workpieces to a die for extrusion forming, wherein each workpiece is a material of an electrode and includes a core and a cladding that covers at least a portion of the surface of the core, said die having (i) an extrusion hole for forming the workpiece to have a predetermined cross sectional shape, and (ii) a supply hole located adjacent to the extrusion hole, said supply hole having a cross section greater than a cross section of the extrusion hole, wherein at one end of each workpiece along a direction parallel to a direction in which each workpiece is supplied to the supply hole, an end face of the core is exposed from an end face of the cladding; and a forming step of pushing each workpiece, supplied to the supply hole, through the extrusion hole so as to form each workpiece into a shape corresponding to the cross section of the extrusion hole, wherein the supply step includes supplying the plurality of workpieces to the supply hole such that the plurality of workpieces form a vertical line in the die.