Seagate Technology Incorporated

Dustin Alan Cochran

Klaus Dieter Kloeppel

Mark Greg Steele

Gunter Karl Heine

Alexander Gredinberg

Mohammed Mizanur Rahman

An apparatus and method are provided for electrochemically etching grooves in a working surface. In an aspect, a frame holds a working surface about an axis and facing an electrode movable along the axis. The electrode, axially movable, has surface carrying a groove pattern to fix on the working surface. A source of electrolyte is pumped at a fixed static pressure rate between the surface of the movable electrode and the working surface. In an aspect, a support fixture supports the electrode for movement toward and away from the working surface with minimal frictional restriction. A force biases the electrode surface toward the working surface so that a gap through which the electrolyte flows between the surface of the movable electrode and the working surface is determined primarily by the static flow rate of the electrolyte and the force bias of the electrode toward the working surface.

Critical orifice gap setting for grooving fluid dynamic bearings

A fluid dynamic bearing is provided having a first surface having at least a first groove pattern formed therein; and the second surface having at least a second groove pattern formed therein; wherein one of the surfaces is configured to be rotated relative to the other surface. The groove patterns may be conventional patterns or patterns described herein. Further, the patterns discussed herein may be disposed wholly on each surface or may be divided between the two surfaces. The groove design is intended to be useable in either a journal, thrust or other fluid bearing design.

Grooves on both the moving and the stationary mating fluid dynamic bearing surfaces for performance enhancement

A system and method are described for radially positioning a workpiece for electrochemical machining. In one embodiment, a pressurized air chamber is configured to contain pressurized air. In addition, an expandable diaphragm is configured to position the workpiece radially relative to an electrode assembly in response to the pressurized air being released into the pressurized air chamber.

System and method for radially positioning a workpiece for electrochemical machining

A system and method are described for holding and releasing a workpiece for electrochemical machining. In one embodiment, a workpiece holder has a workpiece surface that couples to the workpiece when negative pressure is applied to provide a seal between the workpiece and the workpiece surface. A plenum located within the workpiece holder has a proximal end capable of being removably coupled to the workpiece. A piston is configured to move upward in the plenum and to lift the workpiece off of the workpiece surface in response to positive pressure being applied.

System and method for holding and releasing a workpiece for electrochemical machining

A method of forming a hydrodynamic bearing surface on a workpiece is provided. The method comprises electrochemically etching away all material in a region of the surface, except for portions of the region defined by a land pattern on an etching cathode. The step of removing forms a continuous recessed region comprising grooves formed between the portions of the region defined by the land pattern, and a relief cut region circumscribing the workpiece.

Method for electrochemically forming a hydrodynamic bearing surface

An apparatus, method and means is provided for electrochemical machining of hydrodynamic bearing assemblies in spindle motors. In an aspect, a cartridge is provided that receives and accurately positions an electrode in three dimensions in a near frictionless manner. The electrode reaches and maintains an equilibrium position in response to a first and second predetermined force, the equilibrium position being a predetermined three dimensional orientation relative to the work piece and defining a critical orifice with the work piece. In an aspect, a hydrostatic bearing is employed within the electrode for radially adjusting the electrode.

Method and apparatus for forming grooves within journals and on flat plates

A fluid dynamic bearing motor is provided comprising a base, a counter plate fixed to the base, a stationary sleeve fixed to the base and supported on the counter plate, a rotating shaft axially disposed through the sleeve, and a fluid dynamic bearing disposed between the shaft and the sleeve and between a free end of the shaft and a first surface of the counter plate, wherein at least one of the free end of the shaft and the first surface of the counter plate comprises a single spiral-shaped groove formed thereon.

Low velocity, high pressure thrust pump

To groove two regions simultaneously to different groove depths, a dual element/voltage electrode is disclosed. The electrode comprises an outer, cylindrical sheath element and an inner rod element separated by an insulator. Each element operates at a different voltage. The cylindrical element which grooves the conical bearing will, for example, operate at half the voltage of the rod element which grooves the pumping region, thereby achieving twice the groove depth.

Dual voltage conical ECM electrode

In one aspect of the invention, an apparatus for ECM grooving of a workpiece is provided. A portion of a conical workpiece is supported on a frame, with the cone opening facing a Z-axis. A slide electrode assembly is provided, including an electrode movable along the Z-axis and having, on a face aligned across a machining gap from the workpiece, a pattern of grooves to be defined on the workpiece; As an electrolyte is pumped into or through the machining gap at a constant static pressure, the electrode reacts to the pressure by moving toward or away from the workpiece to establish a certain gap width to create the necessary groove depth and definition. The force acting on the slide electrode assembly is the primary controlling factor for establishing the machining gap as the electrode and support move in response to the constant static pressure of pumped electrolyte.

Automated machine control gap for conical fluid dynamic bearing ECM grooving

A dual cone or single cone work piece is placed inside a pair of locating surfaces so that it is accurately held within a framework defined by these locating surfaces. A electrode is then inserted inside the cone, and is movable within the cone to accurately set the gap between the electrode which will find the groove pattern to be formed on the cone surface. An electrolyte is then pumped through the gap between the cone and the electrode.

Dual conical ECM grooving device

An apparatus and method are provided for electrochemically etching grooves in an inner surface of a hub to form at least one fluid dynamic bearing. The apparatus includes a cathode having an electrically conductive substrate with an outer surface that corresponds to the inner surface of the hub . The outer surface has raised lands corresponding to areas in which the grooves are to be formed in the inner surface of the hub . A layer of electrically insulating material covers the outer surface of the substrate between the raised lands to reduce etching of the inner surface of the hub in corresponding areas.

Apparatus and method for manufacturing fluid dynamic bearings

A workholder for an ECM process comprises a set of jaws which define an interior workpiece holding region are mounted on the surface of a diaphragm which is movable under air pressure from a flat to a more generally spheroid shape with the injection of pressurized air between the diaphragm and a backing plate. As the air is injected, and the diaphragm becomes more spheroid, the jaws are moved a substantially equal distance away from the center axis of the workholding region. The workpiece, which typically incorporates or is mounted on a circular shaft, is placed in the center of the workholding region, and the air pressure is removed, causing the diaphragm to return to its original flat shape and the jaws to snap back to their original positions resting against the shaft. With the workpiece now held firmly and repeatably in place about a consistent axis, an electrode can be moved up to a point across a small gap from the surface where grooves are to be formed; with the flow of electrolyte through this gap, and the application of electricity across the gap, the grooves can be formed on the surface.

Diaphragm workholding device for ECM

The present invention is directed to an apparatus,and method of etching grooves,in a shaft,In one embodiment, a cathode,is provided for electrochemically etching grooves,in an outer surface,of the shaft,to form a fluid dynamic journal bearing,The cathode,includes an electrically conductive cylindrical substrate,having an inner surface,that corresponds to the outer surface,of the shaft,the inner surface,having raised lands,corresponding to areas in which the grooves,are to be formed. A layer of electrically insulating material,covers the inner surface,of the substrate,between the lands,to preclude etching of the shaft,in areas between the lands. Preferably, the lands,are arranged so that the grooves,etched in the shaft,form one or more fluid dynamic bearings. In another aspect, the invention provides a process for electrochemically etching grooves,in the outer surface,of the shaft,to form a fluid dynamic bearing.

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Watsonville, CA, United States of America

Dustin Alan Cochran