Metal working – Means to assemble or disassemble – Means to assemble electrical device
Reexamination Certificate
2000-03-09
2001-10-02
Hughes, S. Thomas (Department: 3726)
Metal working
Means to assemble or disassemble
Means to assemble electrical device
C029S281500, C029S596000, C269S266000, C269S043000
Reexamination Certificate
active
06295722
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method and apparatus for mass production of electric disc drive motors assembled with curable adhesives. In particular, the invention relates to an apparatus having a plurality of nests for aligning a plurality of motor components during assembly, and a removable frame for holding and tensioning the motor components during an adhesive curing process.
BACKGROUND OF THE INVENTION
A new system for mass producing disc drive motors is needed. The previous art utilized quick drying adhesives allowing motors to be assembled quickly and efficiently by hand. However, the advent of high performance disc drives, requiring submicron distances between the head and the disc face, created new challenges. The previously used quick drying adhesives had a tendency to outgas small quantities of organic constituents. These minute quantities of outgassed volatiles adhered to the surfaces of the disc drives, forming a submicron film which degraded performance and reliability, and also damaged the delicate submicron components of the disc drives.
These complications made the use of quick drying adhesives impractical. The inventors remedied this problem by switching to an adhesive which did not emit significant amounts of organic volitiles (hereinafter referred to as “non-outgassing adhesives”). However, non-outgassing adhesives created their own problems. The non-outgassing adhesives cure much more slowly than the prior quick dry adhesives. The prior adhesives cured almost immediately, allowing quick easy hand assembly of motor components. A longer cure time wastes many man-hours while the assemblers hold motors under the required tension during the adhesive cure process. In the face of this difficulty, hand assembly is impractical. However, the need for mass production of motor components and motors remains.
An object of the present invention is to provide a method for quick and efficient mass production of electric disc drive motors using non-outgassing epoxy adhesives. A further object of the invention encompasses the multi-position preload/cure fixtures used to accomplish the method of motor construction. There is no known prior art.
DISCLOSURE OF THE INVENTION
The present invention accomplishes the above objectives cheaply and efficiently. The invention embodies a method for the step-wise construction of disc drive motors using non-outgassing epoxies instead of the previously used quick drying adhesives. The method involves the progressive assembly of the motors from their component parts. The method begins by treating the separate unassembled components with non-outgassing adhesives. These components are then assembled before the adhesive cures. The components are then allowed to cure. After curing, the assembled components are treated with adhesive again and assembled with additional motor components and allowed to cure. This process is repeated, each step adding further components. As the motors near completion the components must be kept under tension during the curing process. The apparatuses of the present invention accomplish this by holding the assembled motor components together with spring tensioned guide shafts (these apparatuses are also known as multiposition preload/curing fixtures). This is accomplished by placing a plurality of assembled and adhesive treated motor components on motor nests located on the apparatus. Each apparatus features motor nests shaped to accommodate the specific motor components involved. Once the components are placed in the motor nests the spring loaded guide shafts are inserted into the motor components to hold them firmly in place to maintain the components under compressive tension. On occasion, the components do not fit together properly. To overcome this difficulty, the apparatus is designed to push the components together with overgramming (Note: “overgramming” is a brief excess compressive pressure applied to the motor components to overcome any intercomponent binding, properly seating the assembled components). Once the components are assembled and firmly secured within the apparatus, the adhesive is cured. Once the assembly of the motor is complete, the finished motors are tested for correct operation and life expectancy.
As stated above, the method also encompasses the apparatuses used to construct the motors. The apparatuses hold motor components under tension during the adhesive curing process and seats the components by overgramming when necessary. Additionally, the apparatuses are easily loaded and unloaded to facilitate rapid motor assembly. It is a further feature of the apparatuses that they are compact, allowing many fixtures to be stacked in an oven should the adhesive curing phase involve heat curing.
Each apparatus has two (2) subparts; the first subpart is a base piece featuring a plurality of component nests for cradling the motor components. The second subpart is a removable frame piece for securing and compressing motor components. The frame is mounted removably on the base piece. Once positioned, the frame is secured to the base piece by a clamping means. The frame features a plurality of guide shafts with coaxially mounted tensioning springs for compressing and securing the adhesive treated and assembled motor components. The frame is mounted on the base such that the guide shafts can function with the nests of the base to firmly secure and compress the assembled motor components. In operation, the frame guide shafts are retracted by a retracting means mounted on the base. The preferred embodiment utilizes a pneumatic piston, as is known in the art, to operate the retracting means. When the frame is in this “open” configuration, the adhesive treated and assembled motor components are inserted into the nests mounted on the base piece. The nests are designed to cradle the specific motor components involved, maintaining them in the correct orientation until the frame can be “closed”. Once a plurality of assembled motor components are loaded into the nests, the retracting means pushes the guide shafts back into place. If needed, a brief “overgramming” pressure is also applied to seat the adhesive treated components in their proper conformation. This is the “closed” position. The loaded frame is then released from the base piece and set aside allowing the adhesive to cure.
Motor assembly is completed in a step by step process with each component being treated with adhesive, fitted together with the appropriate adjoining component, then cured, and then progressively treated with adhesive and assembled with the next component. As the motor construction process nears completion, some motor component assemblies require compressive tension during curing. This is accomplished by loading assembled components into the previously mentioned fixtures, compressively tensioning, overgramming as necessary, then curing. Once the components are assembled into completed motors, operational and life testing are performed. The motor assembly is then complete.
The invention is more filly described and particularly pointed out in the accompanying drawings, the disclosure, and claims below. It shall be noted that the following drawings and disclosure illustrate but one embodiment of the various ways the invention may be practiced.
REFERENCES:
patent: 3799533 (1974-03-01), Malott
patent: 4048717 (1977-09-01), Piette
patent: 6000123 (1999-12-01), Munezane et al.
Gredinberg Alex
MacLeod Donald J.
Stevens Gregg P.
Hong John C.
Hughes S. Thomas
LaRiviere Grubman & Payne, LLP
Seagate Technology LLC
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