Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1997-08-04
1998-06-23
Font, Frank G.
Optics: measuring and testing
By polarized light examination
With light attenuation
356376, G01B 1122, G01B 1124
Patent
active
057711003
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method of measuring a dimension of a mold or mold-associated component by a laser measuring instrument, and particularly to a method of measuring an inner dimension of a mold or a distance between the laser measuring instrument and a mold or mold-associated component, wherein the laser measuring instrument is disposed above and moved alongside a surface of the mold or mold-associated component to emit a laser beam on surfaces of the mold and/or mold-associated component and the laser spots produced on the surfaces are observed.
BACKGROUND ART
Recently, to enhance the quality of castings so that no staggers or casting fins are produced on the surfaces of the castings, the dimensions of the molding cavities of molds have had to be accurate. Thus it is suggested to measure the dimensions of a molding cavity and thereby to determine if they are allowable or not. As one method of measuring dimensions of the cavity of a mold, a laser measuring instrument is used that emits a laser beam in a predetermined direction.
However, when a dimension of a molding cavity is measured by using such a laser measuring instrument which emits a laser beam in a predetermined direction, the laser beam spot produced on a surface of a mold is selected to be in such a large size that the spot itself is not located between heat-resistant particles of the mold. Thus, when a spot is produced on an angle or edge portion of a mold, the spot bridges the two surfaces that define the angle portion. This makes it impossible to see the precise location of the spot. Further, if a distance between opposing angle portions of a molding cavity is short in comparison with the size of the laser measuring instrument, the instrument cannot be moved to the required positions that correspond to the angle portions of the cavity. Accordingly, no method of accurately measuring a dimension of a molding cavity by a laser measuring instrument has been invented.
This invention is conceived in view of that problem. It aims to provide a method to measure an inner dimension of a mold or a distance between a mold and a mold-associated component.
DISCLOSURE OF INVENTION
To achieve the above purpose of this invention, the method of the present invention of measuring an inner dimension of a mold or a distance between a mold and a mold-associated component by a laser measuring instrument disposed above a surface of at least the mold such that the instrument is movable alongside the surface of the mold to emit a laser beam or the like on surfaces of at least the mold, includes first, second, and third steps, wherein the first step includes disposing a laser emitting portion of the laser emitting instrument such that it inclines toward an inner surface of a first angle portion of opposing angle portions of a mold or mold-associated component to be measured, moving the instrument and the mold or mold-associated component relative to each other in a direction parallel to the surface of the mold to thereby successively measure points near the first angle portion on first and second surfaces which define the first angle portion, expressing the measurements on two arbitrary points on the first surface in x-y coordinates and obtaining an equation relating to the x-y coordinates for the two points as a regression line by the method of least squares, similarly obtaining an equation relating to x-y coordinates for two arbitrary points on the second surface, and calculating the intersection of the two regression lines as a position of the first angle portion, wherein the second step includes disposing the laser emitting portion of the laser emitting instrument such that it inclines toward an inner surface of a second angle portion of the opposing angle portions of the mold or mold-associated component, moving the instrument relative to the mold or mold-associated component in a direction parallel to the surface of the mold to thereby successively measure points on first and second surfaces near the second angle portion, which firs
REFERENCES:
patent: 5146779 (1992-09-01), Sugimoto et al.
Kawai Etsuzo
Yamamoto Shigeaki
Font Frank G.
Merlino Amanda
Sintokogio Ltd.
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