Patent Application
20080079232
Reference will now be made in detail to the alternative embodiment(s) of the present invention. While the invention will be described in conjunction with the alternative embodiment(s), it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.
Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.
The discussion will begin with an overview of an electrical lead suspension (ELS) in conjunction with its operation within a hard disk drive and components connected therewith. The discussion will then focus on embodiments of a method for utilizing a stainless steel framework to change the resonance frequency range of a flexure nose portion of a head gimbal assembly in particular.
In general, embodiments of the present invention provide a method and apparatus for sealing a pivot axle and bearing assembly during submersion cleaning. By providing a seal for the pivot axle and bearing, the cleaning time is significantly reduced while the overall cleaning is significantly increased.
With reference now to
In the exemplary
In the embodiment shown, each arm 125 has extending from it at least one cantilevered ELS 127. It should be understood that ELS 127 may be, in one embodiment, an integrated lead suspension (ILS) that is formed by a subtractive process. In another embodiment, ELS 127 may be formed by an additive process, such as a Circuit Integrated Suspension (CIS). In yet another embodiment, ELS 127 may be a Flex-On Suspension (FOS) attached to base metal or it may be a Flex Gimbal Suspension Assembly (FGSA) that is attached to a base metal layer. The ELS may be any form of lead suspension that can be used in a Data Access Storage Device, such as HDD 100. A magnetic read/write transducer 131 or head is mounted on a slider 129 and secured to a flexible structure called “flexure” that is part of ELS 127. The read/write heads magnetically read data from and/or magnetically write data to disk 115.
The level of integration called the head gimbal assembly, or head stack assembly (HSA) when more than one gimbal assembly is employed, is the head and the slider 129, which are mounted on suspension 127. The head gimbal assemblies of the HSA operate in a conventional manner and always move in unison with one another, unless HDD 100 uses multiple independent actuators (not shown) wherein the arms can move independently of one another.
The steady improvements in disk storage capacity have led to smaller magnetic head sizes and lower fly heights. This decrease in fly height has necessitated that the head stack assembly (HSA) be as clean as possible to reduce head collisions with asperities that may cause loss of read/write functionality or even catastrophic head crashes. Therefore, prior to final assembly in the HDD, the head stack assembly must be thoroughly cleaned. Prior art methods for cleaning a head stack assembly perform the cleaning process without the pivot axle and bearing assembly being installed, and then installing it after the cleaning process. However, improvements in pivot and bearing design have necessitated the use of more permanent installation methods, such as bonding. This more permanent installation has introduced a necessity for cleaning the HAS with the pivot axle and bearing assembly installed.
Referring now to
When a full wet wash with complete immersion of HSA 200 in a cleaning solution is used to clean HAS 200 with bonded pivot axle and bearing assembly installations, the pivot axle and bearing assembly is at risk for contamination by the cleaning process. This is due to the fact that the pivot axle and bearing assembly cannot be closed off completely. There must be a gap between the HSA 200 and the pivot axle to permit the rotation function. Thus, via the gap, contamination can enter into the bearing assembly and bearing grease can wash out of the bearing assembly.
There is a gap 305 at the top between the pivot axle 301 and the inner edge of outer bearing ring 302, partially covered by a thin ring 309, to reduce the size of the gap 305. There is a corresponding gap 306 at the bottom of the bearing assembly. This pair of gaps 305, 306 forms a path for ingress and egress of cleaning solution, allowing the wet wash process to introduce contaminants into the bearing assembly, and possibly remove bearing grease, thus reducing bearing life. Sealing these two gaps 305,306 from the wet wash cleaning fluid provides an effective method for preventing contaminant transfer to and from the bearing assembly.
In the present embodiment, the top sealing cap 402 has a penetration 405 to allow a screw-type retaining mechanism 516 to enter the open shaft (e.g., shaft 308 of
Referring still to
In one embodiment of
Referring now to
In this embodiment, the top cap 415 and the bottom cap 417 are identical. The top cap 415 is configured to fit over the pivot axle and bearing assembly 300 at the protruding outer ring of the bearing sleeve 615. The cap annular ring 419 is seated on the HSA 200 surface at 619. The bottom cap 417 is configured to fit against HSA surface 200 at 616. The pair of sealing caps 400B is configured to provide a water tight seal for prevention of contaminant transfer into the pivot axle and bearing assembly at gaps 605, 604 during submersion cleaning of HSA 200. Each of the pair of caps has an inside diameter across an inside face 411; and an outside diameter across an outside face 410. The cap may be further configured with a slot or groove 424 in the outside face 410 to receive and contain a retaining device such as a spring clip.
In one embodiment of the present invention, two sealing mechanisms are provided by the cap 400B design. In one embodiment, a first sealing mechanism is provided at the joint 619 between the cap annular ring 419 and the top of the HAS 200 arm/actuator. A similar first sealing joint is provided for the lower cap 417 as shown at 616. This joint achieves its sealing function in virtue of the clamping force from the retaining device 620. A second sealing mechanism is provided at the boundary between the inner wall 418 of the cap 400B and the outer ring of the bearing assembly, shown at 615. The diameter of the inside face 411 of the cap 400B is substantially the same as the diameter of the outer ring of the bearing assembly 302. When the diameter of inside face 411 is the same as the diameter of the outer ring, or slightly smaller, an interference-fit is obtained, which provides a water-tight seal. If the diameter is slightly larger, an adequate seal is obtained in virtue of the slight irregularities in the plastic surface and the length of the boundary joint between the outer ring protrusion and the inner wall 418 of the cap.
According to another embodiment of the present invention, the outside circumference of inside face 411 of top cap 415 and bottom cap 417 may provide a third sealing mechanism. In this embodiment, a circular recess 412 is formed in the inside face 411, the recess being configured to accept an o-ring sealing device. An o-ring 612 placed in recess 412 can provide the third sealing mechanism. The dimensions of the cap height and recess are configured to compress the O-ring slightly when the cap is seated with no gap between the top surface of HSA 200 as shown at 611 (slight gap shown for clarity of cap face boundary.) In the event the bottom of the pivot axle and bearing assembly also protrude from the bottom surface of HSA 200, a second O-ring 612 may also be used to provide a third sealing mechanism for the bottom gap 604 in the pivot axle and bearing assembly. This condition is shown in
According to one embodiment, the pair of caps 415, 417 are clamped to the top and bottom surfaces of HSA 200 via a spring clip 620. Clip 620 is configured with coupling interface 621 (top and bottom) to secure clip 620 in place on caps 415,417. In one embodiment, a groove or channel 424 may be provided in the outside face 410 of caps 415,417 at coupling interface 621 to assist in keeping clip 620 in place.
Referring now to
In the present embodiment, the retaining mechanism is comprised of four parts: an upper arm 710 with a gimbal coupling mechanism 714 for coupling to and providing a clamping force to the top cap 415, wherein the upper arm 710 comprises a horizontal portion and a vertical portion; a middle arm 716 is joined to the upper arm at its approximate midpoint at 715; a lower arm 717 joined with a pivot joint 712 to the middle arm 716 also comprising a gimbal coupling mechanism 713 for coupling to and providing a clamping force to the bottom cap 417; and a spring 711 for providing expansion pressure to the pair of arms 710, 717 to provide the clamping force. The spring 711 is located at the lower end of the vertical portion of the upper arm 710 and is coupled to the outer end of the lower arm 717. Pivot joint 712 provides for simple installation and removal of the retaining mechanism to and from the two caps 415,417.
At step 810 of method 800, according to one embodiment of the present invention, a pair of sealing caps and a respective retaining mechanism are selected. The first sealing cap is selected to seal the top of the pivot axle and bearing assembly and the second sealing cap is selected to seal the bottom of the pivot axle and bearing assembly. The retaining mechanism is selected to secure the pair of sealing caps to the pivot axle and bearing assembly.
Still referring to step 810 of method 800, the sealing caps to be selected are either sealing caps configured for a screw-type retaining mechanism as described with
At step 820 of method 800, the selected sealing caps are installed, one on the top and one on the bottom of the pivot axle and bearing assembly so as to cover the gaps into the assembly, according to one embodiment of the present invention. Once the pivot axle and bearing assembly has been installed in the head stack assembly using permanent bonding techniques, the caps are then installed by hand, and then the compression-based sealing systems are implemented using any of the three cited retaining mechanisms.
At step 830, in accordance with an embodiment of the present invention, the appropriate retaining mechanism is installed securely to the caps, utilizing compression to prevent the intrusion of cleaning liquid into the pivot axle and bearing assembly during the submersion cleaning process. When a screw is used as the retainer, then the caps must be provided with the hole in the top cap and a threaded hole in the bottom cap. When the retaining clips are used, then they are installed after the caps are installed on either end of the bearing assembly.
At step 840, according to one embodiment of the present invention, a wet wash submersion cleaning process is performed on the HSA. The wet wash submersion cleaning process generally involves submersing the HSA in a tank of water with soap or other cleaning solvent and utilizing ultrasonics.
At step 850, in accordance with an embodiment of the present invention, the head stack assembly is allowed to dry with the pair of sealing caps and retaining mechanism installed.
At step 860, the pair of sealing caps and retaining mechanism are removed prior to installation of the HSA in a hard disk drive.
According to one embodiment, sealing means 910 can be a pair of sealing caps, one for sealing the top of a pivot axle and bearing assembly and one for sealing a bottom of the pivot axle and bearing assembly. The pair of sealing caps of sealing means 910 may, in one embodiment, be configured for receiving a screw, as shown in
Retaining means 920 may be a screw or bolt, according to one embodiment of the present invention. Refer to
Thus, the present invention provides, in various embodiments, an apparatus and method for sealing a pivot axle and bearing assembly during submersion cleaning. The foregoing descriptions of specific embodiments have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.
