Method of combining grinding and EDM operation for finishing fuel injector nozzle bodies

Claim 1

A method for concentrically forming a valve guide bore and a valve seat in respective fuel injector nozzle body blanks having a center-cut bore terminating in a blind hole defined in part by a pre-formed cone shaped surface to locate a needle valve component therein so as to reduce the fuel dribble capacity of the nozzle body, said method comprising the following steps: a. loading a first blank at one station on one of two work head means on an indexable turret; b. indexing the turret 90 degrees; c. non-contact machining a valve seat surface on the pre-formed cone shaped surface of the first blank to be concentric with the longitudinal axis of the nozzle body; d. moving a first cross slide bearing the non-contact machining means to align seat lapping means with the valve seal surface; e. lapping the valve seat surface; f. returning the cross slide to its preceding position; g. indexing the turret another 90 degrees; h. loading a second blank on the second work head means; i. indexing the turret a further 90 degrees; j. grinding the bore of the first blank to be concentric with the longitudinal axis of the nozzle body while concurrently and concentrically non-contact machining the valve seat surface of the second blank; k. concurrently moving said first cross slide and a second cross slide bearing the bore grinding means to align respective seat lapping and bore lapping means with said first and second blanks; l. lapping the respective value seat and bore so as to be concentric with one another; m. returning the first and second cross slides to their respective preceding positions; and n. unloading the first blank as a finished fuel injection nozzle body.

Claim 2

A method for concentrically forming a valve guide bore and a valve seat in respective fuel injector nozzle body blanks having a center-cut bore terminating in a blind hole defined in part by a pre-formed cone shaped surface to locate a needle valve component therein so as to reduce the fuel dribble capacity of the nozzle body, said method comprising the following steps: a. loading a first blank at one station on one of two work head means on an indexable turret; b. indexing the turret 90 degrees; c. non-contact machining a valve seat surface on the pre-formed cone shaped surface of the first blank to be concentric with the longitudinal axis of the nozzle body; d. moving a first cross slide bearing the non-contact machining means to align seat lapping means with the valve seal surface; e. lapping the valve seat surface; f. returning the cross slide to its preceding position; g. indexing the turret another 90 degrees; h. loading a second blank on the second work head means; i. indexing the turret a further 90 degrees; j. grinding the bore of the first blank to be concentric with the longitudinal axis of the nozzle body while concurrently and concentrically non-contact machining the valve seat surface of the second blank; k. concurrently moving said first cross slide and a second cross slide bearing the bore grinding means to align respective seat lapping and bore lapping means with said first and second blanks; l. lapping the respective value seat and bore so as to be concentric with one another; m. returning the first and second cross slides to their respective preceding positions; and n. unloading the first blank as a finished fuel injection nozzle body.

Claim 4

A method for concentrically forming a valve guide bore and a valve seat in respective fuel injector nozzle body blanks having a center cut bore terminating in a blind hole defined in part by a performed cone shaped surface to locate a needle valve component therein so as to reduce the fuel dribble capacity of the nozzle body, said method comprising the steps of: (a) performing the valve seat as a frustrum of a cone to have a small end diameter to large end diameter ratio on the order of 1-50; (b) grinding the center cut bore surfaces to the blind hole of one blank and concurrently non-contact machining a valve seat surface of a second blank by use of a consumable spark gap electrode including a conical surface closely spaced from the preformed valve seat and concentrically of the valve guide bore; and (c) rotating said ground and non-contact machined nozzle body blanks into alignment with respective bore and valve seat lapping means, and concurrently and concentrically lapping said ground bore and machined valve surfaces.

Claim 5

A method for concentrically forming a valve guide bore and a valve seat in respective fuel injector nozzle body blanks having a center cut bore terminating in a blind hole defined in part by a performed cone shaped surface to locate a needle valve component therein so as to reduce the fuel dribble capacity of the nozzle body, said method comprising the steps of: (a) performing the valve seat as a frustrum of a cone to have a small end diameter to large end diameter ratio on the order of 1-50; (b) grinding the center cut bore surfaces to the blind hole of one blank and concurrently non-contact machining a valve seat surface of a second blank by use of a consumable spark gap electrode including a conical surface closely spaced from the preformed valve seat and concentrically of the valve guide bore; and (c) rotating said ground and non-contact machined nozzle body blanks into alignment with respective bore and valve seat lapping means, and concurrently and concentrically lapping said ground bore and machined valve surfaces.