Metal working – Means to assemble or disassemble – Means to assemble electrical device
Reexamination Certificate
1999-02-03
2001-10-02
Hall, Carl E. (Department: 3729)
Metal working
Means to assemble or disassemble
Means to assemble electrical device
C029S603060, C029S761000
Reexamination Certificate
active
06295723
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to head stack assemblies for disk drives, and, more particularly, to an apparatus for the building of head stack assemblies from an array of head stack subassemblies that comprises an arm of an actuator having a plurality of arms, a load beam and a mounting plate, all apertured and in aperture registration for staking together with a staking tool. The invention provides apparatus that compensates for imperfectly stacked subassemblies to apply a uniform clamping pressure on the subassemblies despite one or more of the subassemblies being angled relative to the clamping nosepiece. The invention further relates to improvements in the support of mounting plates against distortion during the staking process, using spacers having substantially identical size apertures to the mounting plate apertures, rather than substantially larger as heretofore, so that the mounting plate aperture edge margins are supported by spacer aperture edge margins, and less distortion is suffered during staking, for a better head stack product. The invention further relates to methods of head stack building and to methods of aligning and supporting head stack subassemblies for staking with maximum precision and minimum mounting plate distortion.
2. Related Art
Head stacks are known, as are methods of building them from an array of head stack subassemblies. The typical head stack forming apparatus clamps an array of head stack subassemblies between a nosepiece and a baseplate. Force on the array is applied by tie nosepiece moving toward the baseplate. Spacers are provided between successive subassemblies. One function of the spacers is to support the mounting plate from becoming distorted by passage of the staking tool therethrough.
SUMMARY OF THE INVENTION
A lack of realized precision in the registration of the spacer apertures with the mounting plate apertures requires that the spacer apertures be relatively larger than required to simply pass the staking tool. The oversized spacer aperture will have edge margins which are back from and which do not register with or cover the corresponding edge margins of the mounting plate aperture. This lack of perfect edge margin registration leaves a penumbra of unbuttressed mounting plate aperture edge margin. Under such conditions the mounting plate flange surrounding the base of the tubular boss may flex and buckle under the axial force exerted by the staking tool. It is an object of the invention to better support the mounting plate during staking. It is a further object to improve the registration of the spacer aperture edge margin with the mounting plate aperture edge margin. A further object is to separately, and externally of the head stack, align the spacers and their apertures with precision, permitting reduction in the difference in size between the spacer apertures and the mounting plate apertures and providing an increased support of the mounting plate by the spacer.
When one or more of the subassemblies is less than perfectly aligned on the common axis through the registered apertures that define the staking tool path, the first subassembly, the one immediately opposite the nosepiece, is presented at an angle to the engagement face of the nosepiece. The nosepiece then contacts the higher portion of the subassembly first and exerts a greater force thereon as the clamping pressure is applied. One or more of the subassemblies or portions thereof, may become misaligned. The staking tool, typically one or more staking balls driven through the apertures defining the staking tool path, then will have to traverse less than a straight path with possible adverse consequences in the staking operation. It is a further object of the invention to improve the staking operation, particularly in those cases where the stack of subassemblies is less than perfectly aligned in the clamping apparatus. When the subassemblies are angled relative to the apparatus nosepiece, the application of clamping force can be nonuniform, the alignment of clamped subassemblies not straight, and the staking tool path nonaxial, resulting in yield losses. It is an object of the invention to adapt to a less than perfectly aligned set of subassemblies which present themselves at an angle to the nosepiece by angularly self-adjusting the nosepiece engagement head to be flush with the engaged subassembly, so that the clamping force is uniformly applied despite the angled relations.
These and other objects of the invention to become apparent hereinafter are realized in an apparatus for building head stack assemblies from an array of head stack subassemblies disposed generally perpendicular to a common axis, each head stack subassembly comprising an arm of a common actuator having a plurality of arms, a load beam and a mounting plate to be staked together through a series of apertures therein with a staking tool, the apparatus comprising a baseplate, a nosepiece having an engagement head shiftable toward the baseplate in clamping relation against the subassemblies, and a series of clamp/spacers between successive subassemblies in the array, the engagement head being pivotable on the engagement head for flush engagement with the subassembly array at different angles of the array to the nosepiece for uniform application of clamping force to the array regardless of the different angles of the array.
In this and like embodiments of the invention, typically: the common axis is a first common axis, and there is also included an alignment beam for the spacers disposed on a second common axis spaced from and parallel to the first common axis, the alignment beam maintaining the spacer apertures in registration with the subassembly apertures independently of the clamping apparatus; the nosepiece and engagement head define a guide for the staking tool; the nosepiece and engagement head are coaxially apertured to define the staking tool guide; the nosepiece comprises a first body adapted for axial shifting relative to the baseplate in subassembly clamping relation, and a second body defining the engagement head, the second body being pivotally mounted to the first body, the first body is generally cylindrical, the second body is generally cylindrical and is supported by the first body in interfitting relation, the first and second bodies being coupled for relative pivoting movement permitting the second body to engage the subassembly array flush at the angle of presentation of the subassembly array to the engagement head within an angle range of 0 to +/−3 degrees, the second cylindrical body is interiorly open and terminates adjacent the subassembly array in a transverse wall having interiorly a dished shape, the first body having a cylindrical wall sized to fit within the second body cylindrical wall, the first body terminating adjacent the subassembly array in a dished wall congruent with and complementary to the second body wall dished shape for pivoting engagement therewith, and a fastener limiting separation of the first and second bodies during relative pivoting movement, the fastener comprising at least one rod and groove combination in which a rod is fixed in one of the first and second bodies and a rod-receiving groove is defined in the other of the first and second bodies, the rod being undersized relative to the groove to permit pivoting movement of the second body relative to the first body without axial separation of the first and second bodies, the second body cylindrical wall has a circularly distributed series of chordally located bores parallel to said second body transverse wall, each of the bores fixing a rod, the first body defining a circularly distributed series of rod-receiving chordally disposed grooves arranged to receive laterally an opposing rod fixed in the second body bore in first and second body coupling relation, the rods and bores being relatively sized to permit pivoting movement of the second body on the first body centered on their respective dished walls, and/or, the relative size of the r
Bachand Louis J.
Hall Carl E.
Magnecomp Corp.
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