Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1996-08-16
1998-02-03
Pham, Hoa Q.
Optics: measuring and testing
By polarized light examination
With light attenuation
356375, 25055929, G01B 1114
Patent
active
057150621
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method of measuring sizes of a mold and mold-associated components by a laser measuring instrument, and, in particular, to a method of measuring a distance between a laser measuring instrument and the surface of each of a molding flask, mold, and mold-associated components by a laser measuring instrument wherein the instrument is disposed above the flask etc. such that it can move alongside the surface of the flask etc., and wherein it emits a laser beam to the surface and observes the laser spot on it to measure the distance between the surface and the instrument.
BACKGROUND ART
Recently, determining the quality of the cavity of a mold by measuring the dimensions of the cavity has been proposed to enhance the quality by eliminating staggers and casting fins of castings. Further, a method to measure the distance by emitting a laser beam and observing the laser spot was conceived as a method to measure the dimensions of the cavity.
However, when the dimensions of the cavity of a mold are measured by a laser measuring instrument, the levelness of the place on which a mold flask etc. is put is sometimes bad in comparison with the preciseness of measurements by the instrument. For example, the levelness of a conveying route may be bad due to an old flask or conveyor, or an unnecessary substance that enters the space between the flask and conveyor. This is disadvantageous as it causes a large error between the actual distance and the measured distance.
The present invention is made to eliminate this disadvantage. It aims to provide a method for precisely and accurately measuring the distance between a surface of a molding flask etc. and a laser measuring instrument.
DISCLOSURE OF INVENTION
To this end, the present invention is a method for measuring by a laser measuring instrument a distance between the laser measuring instrument and a surface of a flask, mold, or mold-associated component wherein the laser measuring instrument that emits a laser beam onto a surface of the flask etc. and that observes the laser spot on the surface is disposed above the flask etc. such that the instrument moves alongside the surface of the flask etc. The method includes a first step of emitting laser beams onto four points on the surface by the laser measuring instrument and measuring the distance between the instrument and each point, a second step of expressing points on the surface as x-y coordinates and expressing distances between the surface and the laser measuring instrument as a z coordinate, and obtaining an equation .DELTA.z=a x+b y+c to represent compensation values that compensate for the measurements of the distances between the surface and the laser measuring instrument based on the four measurements at the four points and one of the maximum and minimum values of the four measurements, a third step of measuring distances between target points on the surface of the mold or the mold-associated component and the laser measuring instrument, a fourth step of calculating compensation values for the target points from the equation .DELTA.z=a x+b y+c and the values of the x-y coordinates on the target points, and a fifth step of adding the compensation values to the measurements of the distances between the target points and the laser measuring instrument.
Herein a mold means one that has a groove etc. formed in the cavity or mold for showing its position, and a mold-associated component means a molding flask, a bushing of a flask for indexing it (centering of a bushing), etc.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic front view of the embodiment of a device that carries out the method of the present invention.
FIG. 2 is an enlarged plan view of a main part (molding flask) of the device in FIG. 1.
FIG. 3 is an enlarged front view of a main part (laser measuring instrument) of the device in FIG. 1.
BEST MODE FOR CARRYING OUT THE INVENTION
The embodiment of the present invention will now be explained in detail by reference to FIGS. 1, 2, and 3. As in FIG. 1,
REFERENCES:
patent: 4660970 (1987-04-01), Ferrano
patent: 4911550 (1990-03-01), Hisakuni
patent: 5416590 (1995-05-01), Stover et al.
patent: 5532499 (1996-07-01), Cheng
Pham Hoa Q.
Sintokogio Ltd.
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