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1. WO1997023321 - METHOD AND APPARATUS FOR FORMING A CONTROL VALVE FOR HYDRAULIC CIRCUITS

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[ EN ]

1. A rotary control valve for use in a hydro-mechanical system comprising:
a housing;
a sleeve; and
a spool shaft having an end having an extended portion having a plurality of circumferential notches.

2. The rotary control valve of claim 1 , further comprising:
a pinion shaft having a near end having a recess adapted to freely receive said plurality of circumferential notches of said spool shaft, said extended portion engaging a portion of said near end of said pinion shaft when said spool shaft is rotated a predetermined distance with respect to said pinion shaft.

3. A method of forming in a machine tool a spool shaft for use in a rotary control valve comprising the steps of:
forming a spool shaft blank having a spool shaft extension on one end;
forming a plurality of notches in said spool shaft extension;
forming a complementary recess on a spool shaft holder for receiving said spool shaft extension;
mounting a first spool shaft holder in said machine tool;
mounting said plurality of notches in said end extension of said spool shaft within said complementary recess of said spool shaft holder;
machining said spool shaft; and
removing said spool shaft from said machine tool.

4. The method of forming said spool shaft of claim 3 wherein after said removing step further comprising the steps of:
hardening said spool shaft;
mounting a second spool shaft holder in a grinding machine;
re-mounting said plurality of notches in said spool shaft extension within said complementary recesses of said second spool shaft holder to index said spool shaft; and
grinding said spool shaft.

5. The method of forming said spool shaft of claim 4 wherein said grinding step further comprises:
grinding a predetermined geometrical shape on said spool shaft.

6. The method of forming said spool shaft of claim 4, wherein said machining step comprises performing sequential machining operations on said spool shaft.

7. The method of forming a spool shaft of claim 6 wherein after said grinding step further comprising the steps of:
mounting said spool shaft in a third work piece holder mounted in a "C-axis" grinding machine;
grinding a plurality of metering ramps on said spool shaft with said C-axis grinding machine.

8. A method of forming a pinion shaft for use in a rotary control valve in a machine tool used for performing a machining operation thereon comprising the steps of:
forming a pinion shaft blank;
forming a rosette having a plurality of arms that are complementary to a mating set of notches formed in a near end of said pinion shaft blank;
forming a complementary plurality of notches on a pinion shaft holder;
mounting said pinion shaft holder in a machine tool;
mounting said rosette in said end of said pinion shaft in said complementary plurality of notches of a pinion shaft holder; and
performing a machining operation on said pinion shaft.

9. The method of forming said pinion shaft of claim 8 after said performing step further comprising:
hardening said pinion shaft;
mounting the final one of said pinion shaft holders in a cylindrical grinding machine;
re-mounting said plurality of arms in said pinion shaft upon said complementary notches of said final one of said pinion shaft holders; and
grinding required cylindrical shapes upon said pinion shaft.

10. An apparatus for machining an indexing portion on a shaft, said apparams comprising:
a base;
a shaft holder mounted to said base, said holder rotating said shaft in a first direction at a first predetermined speed; and
a cutting assembly mounted to said base and having a cutting tool mounted to a rotating member, said cutting tool being offset a predetermined distance from a center of rotation of said rotating member.

11. The apparams of claim 10, wherein said rotating member rotates in a direction counter to said first direction at a predetermined speed of rotation three times the speed of rotation of said spool shaft holder.

12. The apparams of claim 10, wherein said rotating member rotates in said first direction at a predetermined speed of rotation three times the speed of rotation of said spool shaft holder.

13. The apparams of claim 10, comprising:
a motor turning a driveshaft, said driveshaft connected to rotate said spool shaft holder and said rotating member of said cutting assembly.

14. The apparams of claim 12, further comprising:
a lifting apparams for pivoting said cutting assembly to and away from said spool shaft.