United States of America As Represented by the Secretary of the Air Force

I-tek, Inc.

Roger K Lee, Jr

William C Bradley

Allen H Greenleaf

A rotary lapping system for grinding a workpiece in an abrasive slurry liquid and producing a positive lift in the abrasive slurry liquid is disclosed. The positive lift is the result of the particular mounting of the grinding pads which causes the leading edge pads to possess a positive angle of attack during rotation in the abrasive slurry liquid. The advantages of a positive lift in the grinding pads includes preventing the grinding tools from digging into the surface of the workpiece during very high speed lap grinding. Trailing edge grinding pads are allowed to produce, in one embodiment, a negative angle of attack which results in a negative lift. The net lift of all grinding pads may be a neutral lift, which allows the entire lap substrate to be tilted and allow working of local areas while the leading edge guiding pads continue to hydroplane over the workpiece surface and avoid tendencies to dig into the surface.

Very high speed lap with positive lift effect

A rotary lapping system which contains a construction and mounting of grinding pads called tesserae which act to produce a negative lift or suction through hydrodynamic action with an abrasive slurry liquid is disclosed. The rotary lapping system uses a plurality of negative lift tools, each of which is composed of a square base of metal, a rubber sheet bonded to the base and four brass tessera bonded to the rubber sheet. Each tessera has a plurality of equally spaced, parallel grooves forming the grinding surface and the four tesserae are bonded to the rubber sheet to leave a relatively wide space, or slot, between each of the tessera. Four negative lift tools are attached around the outer edge of a metal ring, equally spaced, and the metal ring is bonded to a rubber ring which is bonded to the base of a power driven dish-like member for hodding a grinding slurry to be fed to the grinding surfaces. The tessera construction causes a negative lift, or suction, to produce very strong cutting pressure with more rapid material removal without distortion of, or harm to the workpiece. The negative lift is the result of the particular mounting of the tesserae, which cause the tesserae at the leading edge of the rubber sheet to present a negative angle of attack to the abrasive slurry liquid during rotation.

Very high speed lap with negative lift effect

A system for precisely determining the position of a beam of incident radiation. In one embodiment in the disclosure the system is utilized in an orbiting, Ritchey-Chretien telescope to determine the precise position of the image of a guide star in the focal plane of the telescope. In that embodiment a first reticle plate, having concentric ring reticle lines, is located at the edge of the tangential focal surface of the telescope and outside of the focal area being used for observation. A second reticle plate, having radial reticle lines, is located adjacent to the first reticle plate at the edge of the sagittal focal surface of the telescope and outside of the focal area being used for observation. A relay lens system and an image dissector tube are positioned behind the reticle plates so that light refracted by the reticle plates is passed by the relay lens system to the image dissector tube. A guide star is imaged on the first and second reticle plates. Light in the star image which is imaged onto either an apex or a groove in the reticle plates is split into separate beams in dependence upon the exact position of the image relative to the apex or groove. The position of the guide star image is precisely located first in a coarse position mode and secondly in a fine position mode. In the coarse position mode the image dissector tube aperture is scanned to find the overall locations of the separate beams, and the deflection signals of the image dissector tube at those locations determine the particular apex or groove in each reticle plate upon which the star is imaged. In the fine position mode the amount of light in each of the separate beams formed by the reticle plates is measured by the image dissector tube in a photon counting mode. This determines the exact position of the star image relative to the particular apex or groove in each reticle plate upon which the star image is incident.

Growing community of inventors

Watertown, MA, United States of America

Roger K Lee, Jr