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Fixture for Measuring Flatness

IP.com Disclosure Number: IPCOM000079318D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Costa, MJ: AUTHOR

Abstract

Many manufacturing processes utilize one or more components which must be perfectly flat. One convenient method for checking flatness employs a series of mechanical gauge heads brought to zero against an optical flat. The optical flat provides the reference plane against which the gauge heads are initially zeroed. The optical flat may then be removed and replaced by the component to be checked. Deviations from zero of individual gauge heads measure component out of flatness.

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Fixture for Measuring Flatness

Many manufacturing processes utilize one or more components which must be perfectly flat. One convenient method for checking flatness employs a series of mechanical gauge heads brought to zero against an optical flat. The optical flat provides the reference plane against which the gauge heads are initially zeroed. The optical flat may then be removed and replaced by the component to be checked. Deviations from zero of individual gauge heads measure component out of flatness.

Fig. 1 is a plan view of a fixture for measuring flatness.

Posts 1, 2, 3, which provide a three-point support for the work, have studs which pass through the support plate 4 and thread into pads which, in turn, provide a three-point support for the entire fixture.

With the posts as load bearing members, the support plate carries only the weight of the mounted gauge heads, not shown, and thus does not deflect when a heavy work piece is placed on the columns. Also shown on the support plates are two limit posts 5, 6. These posts are made so that a gap of one or two mils exists between the zero plane and the tip of the limit post.

Fig. 2 is a top schematic view of the flatless fixture. Points of contact between the gauge heads and the work piece being tested are indicated by crosses. For a twelve-inch square-work piece, measured points are typically laid out along two mutually perpendicular axes as shown.

Gauge heads that are susceptible to large negative displacem...