USRE38340EExpiredUtility

Multi-point bending of bars during fabrication of magnetic recording heads

Assignee: SEAGATE TECHNOLOGY LLCPriority: Nov 4, 1996Filed: Dec 13, 1996Granted: Dec 2, 2003

Est. expiryNov 4, 2016(expired)· nominal 20-yr term from priority

G11B 21/24G11B 5/398G11B 5/3103G11B 5/1871B24B 37/048G11B 5/3967G11B 5/56G11B 5/3169G11B 5/3173G11B 5/3116G11B 5/4826G11B 5/3163G11B 5/54B24B 49/16B24B 37/005G11B 5/3106Y10T29/49004

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Claims

Abstract

A device for lapping a bar of the type which carries a plurality of sliders used in magnetic storage systems includes first, second and third actuators adapted to couple to the bar, and impart a first, second and third controllable force in response to a first, second and third control signal, respectively. An arm couples to the first, second and third actuators and applies a lapping force to the bar which presses the bar against a lapping surface thereby causing material to be removed from the bar. A controller provides the first, second and third control signals to the first, second and third actuators, respectively, to impart a plurality of forces onto the bar. The actuators are controlled to obtain a desired profile of the bar and to obtain a desired distribution of the lapping force across the profile of the bar.

Claims

exact text as granted — not AI-modified

What is claimed is:

1. A device for lapping a bar carrying a plurality of sliders, comprising:
a first actuator adapted to couple to the bar and impart a first controllable force in response to a first control signal;
a second actuator adapted to couple to the bar and impart a second controllable force in response to a second control signal;
a lapping surface;
an arm coupled to the first and second actuators which provides a lapping force to the bar against the lapping surface; and
a controller providing the first and second control signals to the first and second actuators, respectively, to impart a plurality of forces on the first and second controllable forces on the bar selected to obtain a desired profile of the bar and to obtain a desired distribution of the lapping force across the profile of the bar, wherein bending caused by the first actuator interferes with bending caused by the second actuator and the controller determines the first and second control signals for the first and second actuators based upon the desired profile of the control points bar and an interrelationship between the bending caused by the first and second control points actuators.

2. The device of claim 1 wherein the first actuator couples to a first control point and the second actuator couples to a second control point adjacent the first control point.

3. The device of claim 1 wherein the controller includes memory which contains a sensitivity matrix describing a relationship between the interrelationship between the bending caused by the first and second actuators and the first and second control signals is are selected as a further function of the sensitivity matrix.

4. The device of claim 1 including a carrier coupling the arm to the bar and including a first control point coupled to the first actuator and a second control point coupled to the second actuator.

5. The device of claim 4 including a balancing actuator coupled to the controller and wherein the carrier includes at least two fixed control points coupled to the balancing actuator to apply a balancing force to the bar.

6. The device of claim 5 wherein the carrier has first and second opposing ends and the two fixed control points are on the opposing ends of the carrier.

7. The device of claim 5 wherein the carrier includes a third control point coupled to a third actuator and a fourth control point coupled to a second fourth actuator and wherein the at least two fixed control points are separated by at least two of the first, second, third and fourth control points.

8. The device of clam 4 wherein the carrier includes a detent and the arm includes a clamp adapted to clamp onto the detent.

9. The device of claim 4 wherein the carrier includes a first control area for coupling to the first actuator and transferring the first controllable force to the first control point, the first control area defined by a region of reduced strength in the carrier.

10. The device of claim 9 wherein the region of reduced strength comprises a cutout in the carrier.

11. The device of claim 4 wherein the carrier includes a parallel spring mechanism adapted to reduce deformation of the bar due to movement of the lapping surface.

12. The device of claim 1 wherein the first and second actuators are pneumatic.

13. The device of claim 4 wherein the carrier includes a third control point and a spacing between any pair of adjacent control points is non-uniform.

14. A device for lapping a bar carrying a plurality of sliders comprising:
an arm;
a lapping surface;
a first actuator coupled to the arm;
a second actuator coupled to the arm;
a carrier comprising:
a work surface adapted to couple to the bar and press the bar against the lapping surface;
a first control point on the work surface coupled to the first actuator and positioned to apply a first force to the bar; and
a second control point on the work surface adjacent the first control point coupled to the second actuator and positioned to apply a second force to the bar;
wherein the first and second control points are positioned in relatively close proximity such that displacement of the first control point causes significant displacement of the second control point.

15. The device of claim 14 including a controller coupled to the first and second actuators providing control signals to the first and second actuators as a function of a sensitivity matrix which describes a relationship between movement of the first actuator and a resulting movement of the second control point.

16. The device of claim 14 wherein the carrier further comprises first and second fixed control points which control balancing of the bar relative to the lapping surface.

17. The device of claim 16 wherein the fixed control points are on opposing ends of the work surface.

18. The device of claim 16 wherein the carrier further includes third and fourth control points on the work surface and wherein the two fixed control points are separated by at least two of the first, second, third or fourth control points.

19. The device of claim 14 wherein the carrier includes a detent and the arm includes a clamp adapted for coupling to the detent.

20. The device of claim 14 wherein the carrier includes a first control area coupling to the first actuator and transferring movement to the first control point, the first control area defined by a region of reduced strength in the carrier.

21. The device of claim 20 wherein the region of reduced strength comprises a cutout region in the carrier.

22. The device of claim 14 wherein the carrier includes a parallel spring mechanism adapted to reduce deformation of the work surface due to movement of the lapping surface.

23. The device of claim 14 wherein the carrier includes a third control point and a spacing between any pair of adjacent control points is non-uniform.

24. A device for lapping a bar carrying a plurality of sliders, comprising:
an arm;
a lapping surface;
a carrier comprising:
a work surface adapted to couple to the bar and press the bar against the lapping surface; and
first, second, third and fourth adjacent control points coupled to the arm and to the work surface;
wherein the first control point is coupled to a first actuator, the second control point is coupled to a second actuator, the third control point is coupled to a third actuator and the fourth control point is coupled to a fourth actuator.

25. The device of claim 24 , the carrier further comprises a fourth control point and wherein the first and fourth control points are fixed control points and are separated by the second and third control points.

26. The device of claim 24 wherein the first carrier further includes a detent and the arm is adapted to clamp to the detent.

27. The device of claim 24 including a first control area adapted to transfer movement to the first control point, the first control area defined by a region of reduced strength in the carrier.

28. The device of claim 14 or 24 wherein the carrier includes 7 actuated control points and 2 fixed control points.

29. A device for lapping a bar carrying a plurality of sliders, comprising:

a first actuator adapted to couple to the bar and impart a first controllable force to the bar proximate to a first control point in response to a first control signal;

a second actuator adapted to couple to the bar and impart a second controllable force to the bar proximate to a second control point in response to a second control signal;

a lapping surface;

an arm adapted to support the bar relative to the lapping surface; and

a controller providing the first and second control signals to the first and second actuators, respectively, to impart the first and second controllable forces to bend the bar to obtain a desired profile of the bar and a desired distribution of lapping force across a profile of the bar, wherein the first actuator introduces a first bending profile to the bar and the second actuator introduces a second bending profile to the bar and the first and second control signals are selected as a function of an interrelationship of the first bending profile imparted by the first actuator and the second bending profile imparted by the second actuator at the first and second control points.

30. The device of claim 29 wherein the controller includes memory which contains a sensitivity matrix describing the interrelationship of the first and second bending profiles imparted by the first and second actuators and the first and second control signals are selected as a further function of the sensitivity matrix.

31. The device of claim 29 including a carrier coupling the bar to the arm to support the bar relative to the lapping surface and the first and second actuators are coupled to the carrier.

32. The device of claim 29 including a balancing actuator coupled to the controller and the arm.

33. The device of claim 29 including a third actuator and a fourth actuator adapted to couple to the bar and adapted to impart third and fourth controllable forces to the bar proximate to third and fourth control points in response to third and fourth control signals and the controller determines the third and fourth control signals based upon the desired profile of the bar and the desired distribution of lapping force across the profile of the bar and the interrelationship of third and fourth bending profiles imparted to the bar by the third and fourth actuators.

34. The device of claim 31 wherein the carrier includes a plurality of flexible control areas of reduced strength spaced along a length of the carrier.

35. The device of claim 34 wherein the flexible control areas comprise a cutout in the carrier.

36. The device of claim 31 wherein the carrier includes a third actuator coupled to the carrier and the first, second and third actuators are non- uniformly spaced along a length of the carrier.

37. A device for lapping a bar carrying a plurality of sliders comprising:

an arm;

a lapping surface;

a carrier coupled to the arm and adapted to support the bar relative to the lapping surface; and

a plurality of actuators coupled to the carrier proximate to control points 1 - n spaced along a length of the carrier and the plurality of actuators adapted to supply a plurality of controllable forces to the bar in response to a plurality of control signals supplied to the plurality of actuators to bend the bar, and the plurality of the control signals being determined to provide a desired profile of the bar and a desired distribution of lapping force along a length of the bar based upon [ K 11 K 1  n K n1 K nn ] · [ F 1 F n ] = [ U 1 U n ] 

where

[

K
11

1

n

K
n1

K
nn

]



is a sensitivity matrix for the controllable force vs. displacement for control points 1 - n where K 11 to K nn are not equal to zero; [ F 1 F n ] 
are the controllable forces proximate to the control points 1 - n; and [ U 1 U n ] 
is the displacement proximate to the control points 1 - n.

38. The device of claim 37 wherein the carrier includes a plurality of areas of reduced strength spaced along the length of the carrier.

39. The device of claim 37 wherein the sensitivity matrix is derived experimentally based upon application of known controllable forces.

40. The device of claim 37 wherein the device includes at least seven actuators coupled to the carrier.

41. The device of claim 37 wherein the sensitivity matrix includes at least three control points spaced along the length of the carrier and the controllable force F proximate to at least one of the three control points equals zero.

42. The device of claim 37 wherein the sensitivity matrix includes at least nine control points spaced along the length of the carrier and the controllable force F proximate to at least two of the nine control points equals zero.

43. The device of claim 37 wherein the sensitivity matrix includes at least two control points spaced along the length of the carrier where the controllable force F proximate to the at least two control points equals zero to define fulcrum points along the length of the carrier.

44. The device of claim 37 wherein the sensitivity matrix is derived using mathematical modeling techniques.

45. The device of claim 24 wherein the means for actuating the plurality of actuators based upon the cumulations of the bending profiles of each of the plurality of actuators includes a controller which determines an actuation force for each of the plurality of actuators based upon a sensitivity matrix describing an interrelationship between the bending profiles of each of the plurality of actuators.

46. The device of claim 24 wherein the means for actuating the plurality of actuators calculates an actuation force for each of the plurality of actuators based on: [ K 11 K 1  n K n1 K nn ] · [ F 1 F n ] = [ U 1 U n ] 

where

[

K
11

1

n

K
n1

K
nn

]



is a sensitivity matrix for the actuation force vs. displacement for control points 1 - n along a length of the carrier where K 11 to K nn are not equal to zero; [ F 1 F n ] 
are the actuation forces proximate to the control points 1 - n; and [ U 1 U n ] 
is the displacement proximate to the control points 1 - n.

47. A device for lapping a bar carrying a plurality of sliders, comprising:

an arm;

a lapping surface;

a carrier coupled to the arm and adapted to support the bar relative to the lapping surface;

a plurality of actuators coupled to the carrier and each of the plurality of actuators adapted to impart a bending profile to the carrier; and

means for actuating the plurality of actuators to impart a desired bending profile to a plurality of control points along the carrier based upon a cumulation of the bending profiles of each of the plurality of actuators.

48. The device of claim 47 wherein at least seven actuators are coupled to the carrier.

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