Metal deforming – By use of tool acting during relative rotation between tool... – Spherical tool
Reexamination Certificate
1999-09-24
2001-04-10
Tolan, Ed (Department: 3725)
Metal deforming
By use of tool acting during relative rotation between tool...
Spherical tool
C029S090010
Reexamination Certificate
active
06212927
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of disc drive data storage devices, and more particularly, but not by way of limitation, to a method of forming an actuator within a disc drive.
BACKGROUND OF THE INVENTION
Modern hard disc drives comprise one or more rigid discs that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is stored on the discs in a plurality of concentric circular tracks by an array of transducers (“heads”) mounted to a radial actuator for movement of the heads relative to the discs.
Typically, such radial actuators employ a voice coil motor to position the heads with respect to the disc surfaces. The heads are mounted via flexures at the ends of a plurality of arms which project radially outward from an actuator body. The actuator body pivots about a shaft mounted to the disc drive housing at a position closely adjacent the outer extreme of the discs. The pivot shaft is parallel with the axis of rotation of the spindle motor and the discs, so that the heads move in a plane parallel with the surfaces of the discs.
The actuator voice coil motor includes a coil mounted on the side of the actuator body opposite the head arms so as to be immersed in the magnetic field of a magnetic circuit comprising one or more permanent magnets and magnetically permeable pole pieces. When controlled DC current is passed through the coil, an electromagnetic field is set up which interacts with the magnetic field of the magnetic circuit to cause the coil to move in accordance with the well-known Lorentz relationship. As the coil moves, the actuator body pivots about the pivot shaft and the heads move across the disc surfaces.
Control of the position of the heads is typically achieved with a closed loop servo system such as disclosed in U.S. Pat. No. 5,262,907 entitled HARD DISC DRIVE WITH IMPROVED SERVO SYSTEM issued Nov. 16, 1993 to Duffy et al. (Duffy '907), and assigned to the assignee of the present invention. A typical servo system utilizes servo information (written to the discs during the disc drive manufacturing process) to detect and control the position of the heads through the generation of a position error signal (PES) which is indicative of the position of the head with respect to a selected track. The PES is generated by the servo system by comparing the relative signal strengths of burst signals generated from precisely located magnetized servo fields in the servo information on the disc surface.
During track following in which a selected head is caused to follow a selected track, a servo processor compares the value of the PES to a desired value indicative of the desired position of the head to the selected track and issues a digital correction signal to the power amplifier, which in turn provides an analog current to the actuator coil to adjust the position of the head with respect to the track. During a seek operation in which a selected head is moved from an initial track to a destination track, relatively large currents are applied to the coil to initially accelerate and then decelerate the head towards the destination track. The velocity of the head is repeatedly measured and the current applied to the coil is adjusted in accordance with the difference between the actual velocity of the head and a velocity profile.
As will be recognized, a continuing trend in the industry is to provide disc drives at an ever decreasing cost. To this end, efforts are continually being undertaken to improve not only disc drive storage and transfer rates, but also the manufacturing of the disc drives. In an effort to increase stiffness within the actuator, tolerance rings are often disposed between the cartridge bearing and the E-block. However, the tolerance rings often create problems with debris collection on the surface of the E-block when the corrugations from the tolerance rings scrape the surface of the E-block and thereby let off flakes of material.
With continued demand for reduction in cost, there remains a continued need for improvements in actuator assembly to reduce the amount of debris collection therein. It is to such improvements that the present invention is directed.
SUMMARY OF THE INVENTION
The present invention is directed to a method of hardening an E-block to reduce debris collection therein.
As exemplified by preferred embodiments, the method involves first providing a manufactured E-block for tooling. The E-block has a central bore with an inner diameter and a bore surface. A hardening member is then provided with an outer diameter that is larger than the inner diameter of the bore surface. The hardening member is pressed through the central bore so that the hardening member compresses and deforms the bore surface. As the hardening member deforms the bore surface, the bore surface becomes substantially smooth and hard. The aluminum bore surface therefore provides a substantially smooth, hard medium upon which a tolerance ring pressingly engages after assembly. The tolerance ring will be less likely to flake off such a substantially smooth and hard contacting bore surface thereby reducing the collection of debris within the bore.
The objects, advantages and features of the present invention will be apparent from the following detailed description when read in conjunction with the drawings and appended claims.
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Eddings Dana P.
Heaton Daniel M.
Jones Inman L.
Misso Nigel F.
Crowe & Dunlevy
Seagate Technology LLC
Tolan Ed
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