Importance

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Abstract

Steel rod stock is shaped into a fuel injector tip having a central axis and including a shank extending between a mating end and a nozzle end. An inner surface of the fuel injector tip includes a conical needle valve seat and defines a nozzle chamber and a sac on opposite sides of the needle valve seat. The mating end includes a injector stack surface and an injector body contact surface. After shaping the fuel injector tip, it is a case hardened to a hardness in excess of HRC 55. Next, the nozzle end is shaped, after the case hardening step, to include a plurality of nozzle surfaces that each define one of a plurality of nozzle outlets extending between the sac and the outer surface. The inner surface and the nozzle surfaces are then autofrettaged to induce compressive residual stress at the case hardened needle valve seat, the case hardened sac and at least a portion of the nozzle surfaces closest to the sac.

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First Claim