Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
2002-04-15
2004-11-09
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
C360S098080
Reexamination Certificate
active
06816338
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to computer disk drives, and more particularly, to a disk clamp for a disk drive, and an apparatus and method for preloading the disk clamp in order for installation within the disk drive.
BACKGROUND OF THE INVENTION
Disk drive data storage systems typically include one or more data storage disks mounted to a spindle hub, and a spindle motor drives the spindle hub which rotates the disks at high RPMs. A disk clamp assembly secures the disks to the hub.
Data disks have a central bore or opening that receives the spindle hub. A common type of disk clamp assembly includes an annular or disk-shaped disk clamp, and a number of screws that secure the clamp to the hub. One or more disks positioned below the clamp are secured to the hub. In addition, spacers may be placed between each disk. For example, in a disk drive with a single data disk, the arrangement could include in series, a clamp, a spacer adjacent the clamp, a disk, a spacer on the opposite side of the disk, and then the hub. For some disk clamp assemblies, a top data disk may directly contact the disk clamp without the use of a spacer. The disks and spacers are often referred to as a disk pack.
Examples of references disclosing clamps utilizing securing screws include the U.S. Pat. Nos. 5,274,517, 5,333,080, 5,528,434, and 5,790,345.
Certain disadvantages arise by using screws to secure the clamp to the hub. One distinct disadvantage is that the screws transmit irregular radially and axially directed forces to the data disk, thus resulting in surface irregularities on the disk. Any distortion or surface irregularities of the disk read/write surface may result in poor head transducer flight characteristics. Another disadvantage is that use of screws contributes to disk contamination. Particle generation occurs when the screws are driven for attaching the clamp. More specifically, particle generation can be attributed to screw-to-hole and screw-to-driver misalignments, excessive force transferred through a single screw, excessive friction for the screw to overcome when being driven, and other reasons as well. In order to rectify these problems, efforts can be made to redesign screw-to-driver interface, improve tool alignment for driving the screw, and even lubricating the screw. Each of these solutions may involve significant redesign of not only the screws and the tools used to drive the screw, but may also require disk clamp redesign. Furthermore, lubrication of the screws can cause contamination by introduction of a substance into the disk drive which itself is a contaminant, or which attracts contaminants.
Another type of disk clamp exists which does not require the use of screws to secure the clamp to the hub. Presumably, these types of clamps help to reduce undesirable radial or axial loading and also help to reduce contamination. One example of a clamping device which does not require the use of screws to secure a clamp to the hub includes the device disclosed in the U.S. Pat. No. 5,270,999. The disk clamp disclosed in this references has a flat lower surface which directly contacts the data disk. The central opening of the clamp includes an inner conical surface. The upper end of the hub includes a groove having a complementary conical or angled surface. When the clamp is mounted over the hub, a uniform circumferential gap exists between the conical surfaces. A clip or retaining ring is placed in the gap between the conical surfaces. When the retaining ring is in place, the clamp resists axial force that may act to disengage the disk from the hub. In addition to the clip or retaining ring, an O-ring is also used to stabilize the disk with respect to the hub. The clamp disclosed in the U.S. Pat. No. 5,270,999 provides very little axial force to secure the disk or disks to the hub. Thus, the O-ring must be used to help prevent radial movement of the disk with respect to the hub. There is always some small gap between the inner edge of the disk defining the central opening and the outer surface of the hub. This gap can allow radial movement of the disk with respect to the hub if no force is provided to prevent such radial movement.
The current method used for installing a screwless clamp involves the use of a press device which deflects the clamp after the clamp has been placed over the hub of the disk drive. Additionally, this method also involves placing a load on the retainer ring as the retainer ring is placed in the gap between the hub and the disk clamp. Therefore, in addition to the force which is needed to deflect the clamp, additional force is required to overcome the friction between the retainer ring and the edge of the interior or central opening of the disk clamp such that the retainer ring can slide or move into the gap between the hub and the clamp. Also in this method, because the disk clamp is loaded and mounted for use over the hub, structure is required to stabilize the hub to prevent damage to the hub. The data disks themselves must be prevented from spinning, and the current solution for this is to create holes in the housing or baseplate of the disk drive, and then spanners are placed in contact with the lower edge of the disk pack to prevent it from spinning. Thus, the current method of installing a disk clamp still subjects the disk drive to contamination and potential damage. Therefore, even in the case of a screwless clamp, there are certain problems which arise in installing the disk clamp.
Therefore, there is a need to provide an apparatus and method which allows for easy and reliable installation of a disk clamp, yet minimizes potential damage to the disk drive, and also simplifies the tools/equipment which must be used to install the disk clamp. Accordingly, there also is a need for a screwless disk clamp of the type which accommodates the apparatus and method for installing the disk clamp.
SUMMARY OF THE INVENTION
In accordance with the present invention, a disk clamp and an apparatus and method for preloading the disk clamp are provided. The invention may also be regarded as a combination of the disk clamp, along with the apparatus for preloading the disk clamp. The invention herein is also intended to cover various subcombinations of this combination, including various elements used within the preloading apparatus. Additionally the invention herein is also intended to cover methods of installing the disk clamp in the disk drive incorporating the method of preloading the disk clamp.
In a preferred embodiment of the disk clamp, the disk clamp includes a lower flange or proturbance which contacts an underlying spacer or disk. When an external load is applied to set the clamp, the disk clamp itself acts as a spring in that it deflects downward in response to the applied load. After a retaining ring is placed in a gap between a groove on the hub and the clamp, the load is removed which enables the disk clamp to spring back to its undeflected state; however, the retaining ring prevents full return resulting in the retaining ring being wedged between the clamp and the hub. A continuous wire ring retaining ring may be used, a cutring, or multiple sections of wire arcs may be inserted between the clamp and the hub.
Other structural features of the disk clamp include an upper groove formed in the upper surface of the clamp for receiving a balance ring, and one or more lower concentric grooves. These lower concentric grooves help to distribute the load of the clamp on the underlying disk pack. Specifically, the ability to vary and control the load transmitted from the disk clamp to the disk pack minimizes deflection known as disk coning and waviness. Preferably, the contact surface of the lower flange is flat, which further reduces undesirable radial loading thus reducing disk coning and waviness. The larger contact area provided by the flat contact surface of the lower flange better compensates for locational misalignment between the clamp and a disk pack which naturally occurs due to tolerances in the manufacture of the clamp and of the disk
Maxtor Corporation
Renner Craig A.
Sheridan & Ross P.C.
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