Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
1999-01-04
2001-04-10
Heinz, A. J. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
C360S245200
Reexamination Certificate
active
06215625
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to hard disk drives and in particular to means of attaching a magnetic head suspension assembly to an E-block.
BACKGROUND OF THE INVENTION
Hard disk drives typically include multiple disks that have a magnetic memory storage surface for storing data. A magnetic head including a read/write transducer passes over the disk surface for reading and writing data. The transducer must be precisely positioned on particular disk tracks in a consistent way to quickly and reliably read and write the data. In the disk drive industry, there is a trend to fit more and more disk tracks per unit of disk surface to maximize the disk storage capacity. Accordingly, precise positioning of the transducer with respect to the disk surface is critical.
Prior art hard disk drives have an E-block that pivots on a pivot bearing. The E-block has multiple actuator arms. Suspensions attach to the actuator arms to suspend the magnetic heads above the disk surface. The suspensions are typically spring loaded, having a particular gram load, to enable the heads to maintain a desired flying height just above the spinning disk surface. Changes in this gram load affect the flying height of the head.
Changes in the gram load are influenced by many factors. These factors include misalignment and deformation of critical components. For example, the suspension and actuator arm may misalign during assembly. The pivot bearing of the E-block may misalign within the E-block. Bearing and actuator arm defects may cause misalignment. Pivot bearing inner race runout, bore inaccuracies in the E-block, or bearing installation errors are examples of common causes for bearing and E-block misalignment that can result in gram load variations. The actuator arm tips may end up varying from a desired height and orientation, causing attached suspensions to have varying gram loads.
Often, gram load changes are associated with the process of attaching the suspension to an actuator arm. Swaging is the most common method of attaching the suspension to the actuator arm and involves pressing swage balls through the hub of a suspension baseplate. The swage balls expand the hub against the actuator arm to hold the suspension and actuator arms together. Pressing swage balls though the hub may distort the baseplate, changing the suspension gram load.
There are known ways of adhesively bonding a suspension to an actuator arm to overcome the undesirable effects of swaging. For example, a doughnut-shaped adhesive washer has been interposed between the actuator arm and the suspension hub. When the suspension hub inserts into the actuator arm opening, heat is applied to melt the washer and thereby create a bond.
There are drawbacks to known adhesive attachment methods. Heating the doughnut-shaped washer melts the washer. As the washer melts, it deforms. This deformation can allow the suspension to misalign relative to the actuator arm, changing the suspension gram load. Another drawback of the adhesive washer is that the hub locates relative to the actuator arm tip to create a bond. When the actuator arm tips misalign, the suspension will also misalign. There is no provision for correcting for actuator arm tip variations that cause gram load variations. What is desired is a way of correcting fabrication misalignment and distortion errors to maintain a consistent gram load.
SUMMARY OF THE INVENTION
An actuator for pivoting a magnetic transducer of a hard disk drive includes an E-block having a pivot bearing, actuator arms formed as part of the E-block, and suspensions bonded to the actuator arms. Each actuator arm has an arm tip with a bonding surface. The suspensions have an integrated baseplate that adhesively attaches to the bonding surface of the actuator arm tip.
The E-block pivot bearing is used as an alignment reference when bonding the suspensions to the actuator arms. The baseplate and the actuator arm bonding surface define a gap therebetween. Adhesive bridges the gap between the suspension and the actuator arm and bonds the suspension to the actuator arm tip. Because the suspensions use the pivot bearing as a reference and the adhesive flows to bridge the gap, the adhesive cures into a shape that automatically compensates for component alignment errors including actuator arm tip variations, pivot bearing inner race run-out, E-block bore inaccuracies, and bearing installation error. Additionally, adhesive bonding avoids gram load changes associated with swaging. Improved gram load precision can be achieved with adhesive bonding.
The bonding surface of the actuator arm tip has numerous possible configurations. One configuration includes a recessed bonding surface that is planar. The bonding surface defines a channel extending between the top and the bottom of the actuator arm for adhesive to flow into, according to a variation of the invention. The channel holds adhesive to enable the suspension/actuator arm bond to resist shear forces. According to another aspect of the invention, the bonding surface has a raised portion. The raised portion may include posts, rails or texture to prevent shear.
A method of assembling a suspension to an actuator arm of a an E-block, in accordance with the present invention, eliminates distortion error caused by swaging, and compensates for other errors caused by pressing the pivot bearing into the E-block arm.
The method includes the step of first inserting a pivot bearing into the E-block, and then referencing the pivot bearing to align the suspension in a desired position. The suspension and the actuator arm define a gap in the desired position relative to the bearing. The next step is bonding the suspension to the actuator arm with an adhesive to fill the gap and to maintain the suspension in the desired position. Filling the gap with adhesive forms an adhesive bridge between the actuator arm and the suspension. This bridge enables orientation of the suspension to compensate for variations in the actuator arm tips, bearing bore or race run-out, and bearing installation error, for example.
In keeping with this invention, a pivot bearing defines an axis and a z-datum. In the novel method, the step of referencing includes referencing the axis and the z-datum to align the suspension with respect to the pivot bearing. According to another aspect of the invention, the step of referencing includes attaching an assembly fixture to the pivot bearing and holding the suspension with the assembly fixture. The step of attaching includes mechanically clamping the suspension, or applying a vacuum to the suspension to hold the suspension in the desired position with respect to the pivot bearing.
The step of bonding preferably includes the steps of maintaining the suspension in the desired position with respect to the bearing, interposing the adhesive between the actuator arm and the suspension, and curing the adhesive with ultraviolet light. Accordingly, the present invention eliminates gram load changes associated with the swaging process. Additionally, since the suspension does not require location with respect to the E-block, or actuator arm tip as in the prior art, variations in gram load and static attitude caused by arm tip height and angle variations during fabrication are eliminated. Furthermore, locating the suspension with respect to the actuator bearing eliminates bearing related variations such as inner race run-out, bore inaccuracies and bearing installation misalignment.
REFERENCES:
patent: 5759418 (1998-06-01), Frater
patent: 5808835 (1998-09-01), Fujiwara
patent: 5877919 (1999-03-01), Foisy
patent: 6021023 (2000-02-01), Hillman
Heinz A. J.
Kallman Nathan N.
Read-Rite Corporation
LandOfFree
Apparatus and method for adhesive bridge suspension attachment does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for adhesive bridge suspension attachment, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for adhesive bridge suspension attachment will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2498117