Linear actuator with wear-resistant ceramic bushing
View Patent ↗An actuator including a threaded shaft and a carriage having a shaft engaging portion coupled to the threaded shaft. The carriage is moveable in a direction parallel to an axis of the threaded shaft upon a relative rotation between the threaded shaft and the shaft engaging portion. A ceramic bushing is coupled to the shaft engaging portion of the carriage, the bushing surrounding the threaded shaft. The ceramic bushing is much harder than heretofore used materials and results in greatly reduced particulate formation. The carriage or portion thereof can be formed around the bushing, e.g., by injection molding.
1. An actuator, comprising:
a threaded shaft;
a carriage having a shaft engaging portion coupled to the threaded shaft, the carriage being moveable in a direction parallel to an axis of the threaded shaft upon a relative rotation between the threaded shaft and the shaft engaging portion; and
a ceramic bushing coupled to the shaft engaging portion of the carriage, the bushing surrounding the threaded shaft.
2. An actuator as recited in claim 1 , wherein the ceramic bushing contains about 5 to about 50% by weight of a zirconium-containing material.
3. An actuator as recited in claim 2 , wherein the zirconium-containing material is a zirconia.
4. An actuator as recited in claim 1 , wherein the ceramic bushing contains about 20 to about 30% by weight of a zirconium-containing material.
5. An actuator as recited in claim 1 , wherein the threaded shaft extends through the shaft engaging portion.
6. An actuator as recited in claim 5 , wherein the shaft engaging portion includes internal threads adapted to engage the threaded shaft.
7. An actuator as recited in claim 1 , wherein the shaft engaging portion has been formed around the ceramic bushing.
8. An actuator as recited in claim 7 , wherein the shaft engaging portion has been formed around the ceramic bushing by injection molding.
9. An actuator as recited in claim 1 , further comprising a tape head coupled to the carriage.
10. An actuator as recited in claim 1 , wherein the shaft engaging portion includes a rotatable drive wheel that engages the threaded shaft.
11. An actuator as recited in claim 1 , further comprising a motor coupled to the threaded shaft.
12. An actuator as recited in claim 1 , further comprising a gear coupled to the threaded shaft, the gear adapted for engaging an external drive gear.
13. An actuator, comprising:
a threaded shaft;
a ceramic bushing surrounding the threaded shaft; and
a carriage molded around the ceramic bushing, the carriage being moveable in a direction parallel to an axis of the threaded shaft upon a relative rotation between the threaded shaft and the carriage.
14. An actuator as recited in claim 13 , wherein the ceramic bushing contains about 5 to about 50% by weight of a zirconium-containing material.
15. An actuator as recited in claim 14 , wherein the zirconium-containing material is a zirconia.
16. An actuator as recited in claim 13 , wherein the ceramic bushing contains about 20 to about 30% by weight of a zirconium-containing material.
17. An actuator as recited in claim 13 , wherein the carriage includes internal threads adapted to engage the threaded shaft.
18. An actuator as recited in claim 13 , wherein the carriage has been formed around the ceramic bushing by injection molding.
19. An actuator as recited in claim 13 , further comprising a tape head coupled to the carriage.
20. An actuator as recited in claim 13 , wherein the carriage includes a rotatable drive wheel that engages the threaded shaft.
21. An actuator as recited in claim 13 , further comprising a motor coupled to the threaded shaft.
22. An actuator as recited in claim 13 , further comprising a gear coupled to the threaded shaft, the gear adapted for engaging an external drive gear.
23. A tape drive actuator, comprising:
a coarse positioner, comprising:
a threaded shaft;
a carriage coupled to the threaded shaft, the carriage being moveable in a direction parallel to an axis of the threaded shaft upon a relative rotation between the threaded shaft and the carriage; and
a ceramic bushing coupled to the carriage, the bushing surrounding the threaded shaft; and
a fine positioner coupled to the carriage.
24. A method for forming at least a portion of an actuator carriage around a bushing, comprising:
coupling a bushing to a holding mechanism;
closing a mold around the bushing, the mold having an inner surface having a general shape of at least a portion of an actuator carriage;
injecting plastic into the mold;
removing the bushing and the injection molded plastic from the mold;
removing the holding mechanism from the bushing.
25. A method as recited in claim 24 , wherein the bushing is a ceramic bushing.
26. A method as recited in claim 25 , wherein the ceramic bushing contains about 5 to about 50% by weight of a zirconium-containing material.
27. A method as recited in claim 24 , wherein the actuator carriage is adapted for insertion in a tape drive.