What is claimed is:
1. An apparatus for writing position data onto a first data storage disc comprising:
a spindle assembly configured to support first and second discs rotatably in a stack;
an actuator configured to support a servowriter head between the discs to write several servo marks onto a data surface of the first disc;
a support element configured to allow sliding contact with the actuator to unload the servowriter head from the data surface; and
means for retracting the actuator and the support element from between the first and second discs.
2. An apparatus according to claim 1 in which the discs have a nominal radius R and in which the support element is constructed and arranged to extend between the first and second discs by a distance greater than R6.
3. An apparatus according to claim 1 in which the support element is a rotary cam structure, and in which the retracting means is an engagement surface configured to support the actuator while the cam structure rotates out from between the first and second discs.
4. An apparatus according to claim 3 in which the discs have a nominal radius R and in which the support element is constructed and arranged to extend between the first and second discs by a distance greater than R6.
5. An apparatus according to claim 1 in which the actuator is rigidly but rotatably supported by a first rigid body, in which the spindle assembly is rigidly but rotatably supported by a second rigid body, and further comprising automated means for coupling the first and second rigid bodies temporarily during a servowriting operation.
6. An apparatus according to claim 5 in which the support element is a rotary cam structure, and in which the retracting means is an engagement surface configured to support the actuator while the cam structure rotates out from between the first and second discs.
7. An apparatus according to claim 5 in which the discs have a nominal radius R and in which the support element is constructed and arranged to extend between the first and second discs by a distance greater than R6.
8. An apparatus according to claim 1 in which the stack has a substantially horizontal axis of rotation.
9. An apparatus according to claim 8 in which the support element has a substantially horizontal axis of rotation.
10. An apparatus according to claim 8 in which the actuator is rigidly but rotatably supported by a first rigid body, in which the spindle assembly is rigidly but rotatably supported by a second rigid body, and further comprising automated means for coupling the first and second rigid bodies temporarily during a servowriting operation.
11. An apparatus according to claim 8 in which the support element is a rotary cam structure, and in which the retracting means is an engagement surface configured to support the actuator while the cam structure rotates out from between the first and second discs.
12. An apparatus according to claim 8 in which the discs have a nominal radius R and in which the support element is constructed and arranged to extend between the first and second discs by a distance greater than R6.
13. A method for writing position data comprising steps of:
(a) assembling first and second discs coaxially in a stack, the first disc having a first data surface facing the second disc;
(b) writing several servo marks onto the data surface with a servowriter head supported by an actuator;
(c) moving the actuator out from between the first and second discs by sliding the actuator onto an engagement surface of a support element that extends between the first and second discs;
(d) moving the support element out from between the first and second discs as the actuator slides on the engagement surface; and
(e) removing the first and second discs from the stack.
14. A method according to claim 13 in which the writing step (b) includes a step (b1) of sliding the actuator along a portion of the engagement surface that approaches the first disc at an approach angle of less than about 25 degrees relative to the disc surface until the actuator disengages from the support element.
15. A method according to claim 14 in which the servowriter head is constructed and arranged to fly at a median distance of less than one microinch from the data surface while writing the servo marks.
16. A method according to claim 13 in which the writing step (b) includes a step (b1) of sliding the actuator along a portion of the engagement surface that approaches the first disc at an approach angle of 4 to 10 degrees relative to the disc surface until the actuator disengages from the support element.
17. A method according to claim 13 in which the writing step (b) includes steps of:
(b1) loading the servowriter head adjacent the first data surface while the disc stack rotates at an initial speed; and
(b2) rotating the disc stack at least 5% slower than at the initial speed while the head writes the several servo marks onto the data surface.
18. A method according to claim 17 in which the writing step (b) further includes a step (b3) of sliding the actuator along a portion of the engagement surface that approaches the first disc at an approach angle of 4 to 10 degrees relative to the disc surface until the actuator disengages from the support element.
19. A method according to claim 13 in which the actuator movement step (c) is performed by rotating the actuator within a fixed angular range having two extreme positions.
20. A method according to claim 19 in which the support element movement step (d) is performed while holding the actuator at one of the extreme positions.
21. A method according to claim 19 in which the writing step (b) includes a step (b1) of sliding the actuator along a portion of the engagement surface that approaches the first disc at an approach angle of less than about 25 degrees relative to the disc surface until the actuator disengages from the support element.
22. A method according to claim 13 in which the support element movement step (d) is performed by rotating the support element about an axis of rotation.
23. A method according to claim 13 in which the support element movement step (d) is begun after the actuator is moved out from between the first and second discs.
24. A method according to claim 13 in which the actuator movement step (c) and the support element movement step (d) overlap.
25. A method according to claim 13 in which the discs have a nominal radius R, and in which the actuator and the support element continuously remain with a distance of R6 of the discs throughout performing the steps (b) through (d).
26. A method according to claim 13 in which the removing step (e) begins by moving the discs axially.
27. A method according to claim 13 further comprising steps of:
(f) installing the first disc into a disc drive; and
(g) after the installing step (f), using the servo marks to position a transducer while the transducer writes additional position data onto the data surface.
28. A method according to claim 27 in which the writing step (b) includes a step (b1) of sliding the actuator along a portion of the engagement surface that approaches the first disc at an approach angle of less than about 25 degrees relative to the disc surface until the actuator disengages from the support element.
29. A method according to claim 27 in which the support element movement step (d) is begun after the actuator is moved out from between the first and second discs.
30. A method according to claim 27 in which the removing step (e) begins by moving the discs axially.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A system for forming an annular isolator between tubing and a borehole having a minimum expected diameter and a maximum expected diameter comprising:
a section of expandable tubing having a first unexpanded outer diameter and a second expanded outer diameter, and
an annular ring of elastomeric material carried on the outer surface of said tubing, said ring having radial and axial dimensions selected so that upon expansion of said tubing in a borehole having said maximum expected diameter, said annular ring will contact said borehole and be compressed with a preselected minimum stress, and upon expansion of said tubing in a borehole of minimum expected diameter, said annular ring will contact said borehole and be compressed with a preselected maximum stress.
2. The system according to claim 1 wherein said annular ring has a inner surface in contact with said expandable tubing and an outer surface for contacting a borehole and has a first axial dimension at its inner surface and a second axial dimension at its outer surface, said first axial dimension being greater than said second axial dimension.
3. The system according to claim 1, further comprising a pair of said annular rings spaced axially apart on said expandable tubing by a sufficient distance so that upon expansion of said tubing in a borehole of minimum expected diameter said rings may expand axially without contacting each other.
4. The system according to claim 1, further comprising:
a pair of said annular rings spaced axially apart on said expandable tubing, and
an elastomeric sleeve carried on said tubing between said pair of annular rings, said sleeve having a radial dimension substantially smaller than the radial dimension of said annular rings.
5. The system according to claim 4, wherein the elastomeric sleeve comprises a material which swells upon contact with fluid in a borehole.
6. The system according to claim 5, wherein the material comprises low acrylic-nitrile.
7. The system according to claim 5, wherein the material comprises an EPDM compound.
8. The system according to claim 1, further comprising a pair of said annular rings spaced axially apart on said expandable tubing by a sufficient distance so forces required to expand said tubing in a borehole of minimum expected diameter do not exceed the limits of the expansion tool or damage the tubing or borehole.
9. The system according to claim 1, further comprising:
a pair of said annular rings spaced axially apart on said expandable tubing, and
a band of chemically reactive materials carried on said tubing between said pair of annular rings, said materials encased in a protective covering preventing chemical reactions from occurring when said tubing is unexpanded and allowing chemical reactions to occur when said tubing is expanded.
10. The system according to claim 1, further comprising:
a pair of said annular rings spaced axially apart on said expandable tubing,
a compartment carried with said tubing,
an annular isolator forming material carried in said compartment, and
a flow path from said compartment to the space between said pair of rings, whereby upon expansion of said tubing said material flows into the space between said pair of rings and forms an annular isolator.
11. The system according to claim 1, wherein said tubing includes a section of reduced diameter relative to said first unexpanded diameter and said annular ring is carried on said section of reduced diameter.
12. The system according to claim 1, wherein the annular ring comprises a material which swells upon contact with fluid in a borehole.
13. The system according to claim 12, wherein the material comprises low acrylic-nitrile.
14. The system according to claim 12, wherein the material comprises an EPDM compound.
15. A method for forming an annular isolator between expandable tubing and a borehole comprising:
attaching an elastomeric sleeve to a section of expandable tubing,
installing the tubing in a borehole,
expanding the tubing with a first expansion tool having a fixed expansion diameter, and
further expanding the tubing in the location of said sleeve.
16. The method according to claim 15, further comprising using a variable expansion cone to further expand the tubing in the location of said sleeve.
17. The method according to claim 15, further comprising applying pressure inside the tubing in the location of said sleeve to further expand said tubing.
18. The method according to claim 17, further comprising applying axial compression to said tubing in the location of said sleeve.
19. The method according to claim 15, further comprising using an expandable bladder at the location of said sleeve to further expand said tubing.
20. The method according to claim 15, further comprising swelling the elastomeric sleeve in the borehole.
21. The method according to claim 20, further comprising swelling the elastomeric sleeve by exposing the elastomeric sleeve to fluid in the borehole.