Abstract: A groove forming process for forming at least one groove pattern on the outer diameter of a shaft for use in a hydrodynamic bearing of a spindle motor. First, the shaft is inserted between a pair of dies, at least one of which has a groove pattern thereon. Next, the shaft is positioned so that it is perpendicular to the groove pattern and at one end of the groove pattern. By lowering the upper die, the shaft is clasped between the dies. The shaft is then rolled in a first direction over the groove pattern by simultaneously applying pressure in a vertical direction and applying pressure in a first horizontal direction to one of the pair of dies so that the shaft rolls in the first direction. The shaft is then rolled in a second direction over the groove pattern by simultaneously applying pressure in a vertical direction and applying pressure in a second horizontal direction to one of the pair of dies so that the shaft rolls in the second direction.

Abstract: A hydrodynamic spindle motor of the present invention may include a shaft having a thrust bearing plate, an insert surrounding the shaft above the thrust bearing plate, and a sleeve surrounding the shaft below the thrust bearing plate. In one embodiment the thrust bearing plate is substantially centrally positioned along the longitudinal axis of the shaft. Preferably either the shaft has annular skewed herringbone shaft grooves or, alternatively, the insert has annular skewed herringbone insert grooves and the sleeve has annular skewed herringbone sleeve grooves. A set of circulation channels above the thrust bearing plate and a set of circulation channels below the thrust bearing plate preferably cross a shaft bore to allow for flow of lubricating fluid. A face seal may be formed between the lower radial cap surface of an end cap and an upper radial insert surface of the insert.

Abstract: A compact electric motor construction employing fluid bearings for use in a disk drive apparatus includes a spindle having a shaft and a thrust plate and a hub assembly including a hub having an outer disk support portion with an inner thrust bearing surface located axially above the upper thrust bearing surface of the thrust plate. The hub also includes an inner sleeve which substantially surrounds the shaft and provides an air gap between its inner diameter and the outer diameter of the thrust plate. The air gap is vented to the interior of the motor cavity by vent passages. Transition grooves are provided on bearing surfaces adjacent all fluid seal zones for controlling the migration of bearing fluid in a radial direction and for providing a low fluid pressure region adjacent capillary seals at the ends of the shaft to contain the seal and prevent leakage.

Abstract: A spindle motor having hydrodynamic bearings formed between a hardcoated shaft with a radial thrust bearing plate substantially perpendicular to the axis of the shaft, a hard coated sleeve, and a hardcoated thrust ring. An axial bearing cavity is formed between the sleeve and the shaft. A first radial bearing cavity is formed between a radial surface of the sleeve and a lower radial plate surface. A second radial bearing cavity is formed between a lower surface of the thrust ring and an upper radial plate surface. Lubricant at least partially fills the cavities to form hydrodynamic bearings therein. The surface hard coats are preferably ceramic-like coatings such as titanium nitride, boron carbide, or Laser Cut 964. A method for fabricating a motor having hydrodynamic bearings includes the steps of machining motor components from a metal such as steel or bronze, coating the components with a surface hard coat, and assembling the motor.

Abstract: A conical bearing system includes a first conical bearing having an integral shaft and a second conical bearing defining a bore having a shaft mating bore section and a threaded bore section. The system is assembled by applying adhesive to the shaft and inserting the shaft into the shaft mating bore section. A threaded screw is then screwed into the threaded bore section until the screw abuts the shaft. Then torque is applied to the screw to push against the shaft thereby causing the second conical bearing to move axially. Once the adhesive has cured, the screw may optionally be removed.

Abstract: A construction for an electric spindle motor includes a stationary central shaft with a horizontal thrust bearing plate and a rotating hub assembly. A flanged thrust bearing ring having an upper capillary surface is affixed to the hub assembly. An annular end cap having a lower capillary surface is nested within the flanged bearing ring. The upper and lower capillary surfaces are radially outwardly diverging horizontal surfaces relative to each other which define a capillary cavity. Lubricating fluid partially fills the capillary cavity to form a horizontal capillary seal which prevents the fluid from escaping the motor. The capillary seal may be formed by tapering either the upper or lower capillary surfaces to provide an enlargement of the bearing cavity in an axial direction radially outwardly from the central shaft. Alternatively, the capillary seal may be formed by substantially coating the upper and lower capillary surfaces with a barrier coating to increase surface tension.

Abstract: A ferrofluid seal for a bearing application with a stationary shaft about which a hub rotates. The seal consists of a permanent magnet and one or more annular pole pieces which form a magnetic circuit with the bearing shaft. The magnetic circuit includes an annular gap between the shaft and the pole pieces in which the magnetic flux traps a magnetic fluid which bridges the gap to form a seal. The shaft is tapered in the gap area to form a wedge-shaped gap which accommodates changes in the magnetic fluid volume due to temperature variations while holding the fluid within the magnetic field to maintain the seal. The pole piece which forms the gap has a straight annular face located at a constant radial distance from the shaft axis. At high operating temperatures expansion of the magnetic fluid causes the fluid to fill the taper of the shaft, but, since the shaft is stationary, fluid spash is eliminated. The straight surface of the pole piece controls fluid splash caused by centrifugal force.