Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
1999-11-22
2001-02-06
Letscher, George J. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
Reexamination Certificate
active
06185072
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to disk head assemblies for supporting read/write heads adjacent rotating disks in disk drives and more particularly, to a base plate for attaching a load beam assembly to a head actuator arm.
2. Description of the Prior Art
Disk drives typically include a stack of spaced apart, concentric magnetic storage disks mounted on a common shaft, and an actuator arm assembly encased within a housing. The actuator arm assembly, also called a head stack assembly (HSA), comprises a plurality of arms extending into spacing between the disks. Mounted on the distal end of each arm is a resilient suspension assembly to which is attached an air bearing slider, the combination of which is referred to as a head gimbal assembly (HGA). Included in the suspension assembly is a load beam, which is mounted at one end to the actuator arm by means of a base plate, and a flexure which is attached to the other end of the load beam and pivotally supports the slider on a gimbal that keeps the slider suspended in a horizontal plane on the disk surface regardless of any motion of the bad beam. The base plate has a flange and a hollow hub. The hub is passed through and extends beyond a hole in the load beam and the flange is welded to the load beam. The hub is then inserted into a boss hole in the actuator arm and the hub is swaged to provide a press fit within the actuator arm boss hole.
The load beam provides the resilient spring action that biases the slider toward the surface of a magnetic recording disk, while the flexure provides flexibility for the slider. A thin film or other magnetic transducer is deposited or otherwise attached at the rearward end of the slider to read or write on the magnetic disk.
A base plate is typically formed by flowing material into the hub region by extrusion from the flange region by a combination of forging and coining. With low hub, thin flange base plates there is often not enough material available in the flange material to flow during extrusion to fill the hub geometry, without decreasing the thickness of the hub.
An object of this invention is to provide a new method of manufacturing a base plate to connect a load beam to an actuator arm in a magnetic head assembly.
SUMMARY OF THE INVENTION
The invention is a base plate that has a flange and a hub that is formed with a fold portion extruded from the flange. In accordance with an aspect of the invention the fold portion may extend beyond an outer diameter of the hub to form a barb.
An advantage of this invention is that it allows the manufacture of base plates with extremely low profile hubs with relatively standard wall thickness by a metal stamping process.
A further advantage of this invention is that the presence of a fold reduces the hard material coupling between the flange and hub portions of the base plate, thereby reducing the gram load change through the swaging process.
A further advantage of this invention is that the presence of the fold increases the hub material's ability to achieve a high retention torque in the tension direction by acting as a lever during the swage operation, thrusting the material with greater force into the arm material, creating a greater press fit.
A further advantage of this invention is that if the fold is such that additional material extends outward to increase the outer diameter of the hub by forming a barb, this allow a press fit, thrusting the barb into the arm material, thereby eliminating the need to swage.
REFERENCES:
patent: 5390058 (1995-02-01), Yamaguchi
patent: 5528092 (1996-06-01), Ohta
patent: 5604649 (1997-02-01), Hernandez
Anderson Russell J.
Braunheim Steve
Hanrahan Kevin
Schmidt Ryan
Intri-Plex Technologies, Inc.
Lamb Owen L.
Letscher George J.
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