| 摘要 |
<p>A method for producing a composite spark plug electrode is disclosed. The method comprises forming a right circular cylindrical billet of a corrosion-resistant metal into a cup having closed and open ends and a cavity having walls extending concentrically therein, and then inserting into the open end of the cup a close-fitting right circular cylindrical billet of a metal having a high thermal conductivity to fit tightly against the walls of the cavity thereof to form a composite billet having closed and filled ends. The method also includes the steps of inserting the closed end of the composite billet into a close-fitting bore of a die having within the bore an extrusion orifice of a diameter less than that of the bore, inserting a plunger into the bore of the die against the filled end of the composite billet, and applying pressure to the plunger to force all of the composite billet except a terminal portion adjacent to the filled end thereof through the extrusion orifice to form an electrode blank having the unextruded terminal portion as an upper headed portion and a rod of reduced diameter extending longitudinally therefrom as a lower portion of a diameter equal to that of the extrusion orifice and a length greater than that of the composite billet. The cylindrical billet of corrosion-resistant metal can be nickel or nickel alloy and can be formed into the cup by back-extrusion. The cylindrical billet of metal of high thermal conductivity can be copper, and, after being inserted into the cup, can be compressed therein to force a lower end and the cylindrical walls thereof into close-fitting relationship with the cavity of the cup.</p> |
