Precision abrasive finishing apparatus

Abstract

A precision abrasive finishing apparatus comprising a base, preferably of granite and being ground to true flat; an abrasive lap capable of being vacuum-clamped against said base and having an abrasive material disposed on it upper, lapping surface; and vacuum clamping means. The abrasive material may be any conventional abrasive grit, such as aluminum oxide, silicon carbide, cubic boron nitride, or other material of suitable hardness, sharpness, friability, durability, inertness, and cost, but preferably is diamond.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a precision abrasive finishing apparatus, specifically, to a lap surface capable of being retrofitted to a conventional lapping table or to a curved mold. BACKGROUND OF THE INVENTION [0002] Lapping is a time-honored way of refining the geometry and finish of work pieces. Typically, the work piece is rubbed over a flat abrasive base surface that is larger than the work piece. The flat base surface may be made of an abrasive material that is either quarried or man-made, or the flat base may not itself be abrasive, but rather be coated with an abrasive material. Randomized motion is provided either by hand over a stationary abrasive base or by machine movement of either or both of work piece and base. The base should be flat-surfaced and a base having any deviation from true flat will degrade the resulting flatness and finish of the work piece. [0003] The abrasive material may be grain-locked in a rigid three-dimensional ma...

AI Technical Summary

Benefits of technology

[0022] Either magnetic materials or application of at least a partial vacuum may be employed to force ferrous shim or ground stock against a precision lapping surface. However, magnetic chucks are costly and magnetic forces transmitted through to the abrasive side of the shim or ground stock would impede swarf clearance. More desirably, vacuum techniques are generally lower in cost and work irrespective of the material composition of the shim or ground stock used.

Problems solved by technology

One major drawback to using abrasive slurries is that they abrade the flat base surface as well as the work piece and periodic re-truing of the base is necessary.

Abrasive slurries also require periodic replacement due to undesired grain breakdown and to loading with swarf.

Bonded abrasive papers and films held to base flat surfaces by mechanical tension, water “stiction”, or adhesives also require replacement due to grain breakdown and displacement.

Although bonded abrasives do allow flushing with water or other fluid to remove swarf, they are still subject to the problem of the grains themselves being abraded from the carrier medium.

Each of these factors may result in a working surface that is not true-flat.

However, such laps do require periodic recharging.

Granite is the universal standard of flat reference materials in metrology, but is limited in lapping applications to the support of abrasive papers and films because any direct rubbing would wear the granite out of true flat at an unacceptable rate.

However, abrasive papers and films have a shorter useful life than other lapping abrasives and require more intensive labor to achieve the same lapping effect.

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