Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1987-01-02
1989-01-31
Evans, F. L.
Optics: measuring and testing
By polarized light examination
With light attenuation
356243, 356385, 358101, 358106, G01B 1124
Patent
active
048012076
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of and apparatus for providing information as to the cross-sectional shape or the profile of a body (such as steel bars, railway wheels and ceramic, plastic or wooden objects) or for measuring the cross-sectional dimensions thereof. This invention relates to an improvement to the invention set forth in our earlier Australian application no. 87638/82; European application No. 82902344.9; Japanese application No. 502438/82; Canadian application No. 409,525 and U.S. application Ser. No. 476,869. The subject matter of those applications is hereby incorporated by this reference.
BACKGROUND ART
In our earlier applications it was explained that in the production of continuous or semi-continuous materials by either a rolling extruding or other forming processes, for example the manufacture of steel bar in a rolling mill, it is usually desired to obtain data on the cross-sectional shape and dimensions of that product at least at the finishing end of the process. The invention disclosed in our earlier application provides goods results. However, the purpose of this invention is to improve the accuracy of the obtained data.
DISCLOSURE OF INVENTION
Thus, the object of this invention is to provide a method and apparatus for providing information as to the cross-sectional shape or profile of the body which remove geometric distortions due to viewing geometry and thus enables a more accurate determination of the required information without the need for or reliance on rigid control of the geometry of the system. However, once a particular geometry is selected the geometry should be held rigid throughout calibration and measurement steps.
It should be understood that the reference in this specification to the provision of information as to the cross-sectional shape or profile of the body includes information relating to the dimensions of the body, shape and relative location of the body. It should also be understood that reference to light in the specification includes non-visible as well as visible parts or the electromagnetic radiation spectrum. It should also be understood that reference to steel bar or metal bar in the specification includes rolled or extruded sections such as channel, angle, rail or the like. It should be understood that reference to the measurement (or object) plane refers to the plane in which profile measurement is desired and which is highlighted by the illumination source.
The present invention may be said to reside in a method of providing information as to the cross-sectional shape or profile of at least a portion of a surface of a body, including the steps of providing a known datum, said known datum including at least four substantially planar surfaces substantially perpendicular to the measurement plane such that four lines formed by the intersection of these planes with the measurement plane define at least three non co-linear reference locations at the intersections of said lines, detecting said known datum, illuminating said body to produce reflected light from said body to provide preliminary information as to the cross-sectional shape or profile of the body, transforming said preliminary information in accordance with a variation of said detected datum from said known datum to provide a better indication of the true cross-sectional shape or profile of at least a portion of the surface of the body to thereby provide said information or allow the information to be obtained therefrom.
The present invention may also provide an apparatus to provide information as to the cross-sectional shape or profile of at least a portion of a surface of a body including illumination means to project light towards said body, sensing means for detecting light from a known datum means, said known datum means including at least four substantially planar surfaces substantially perpendicular to the measurement plane such that lines formed by the intersection of those planes with the measurement plane cause at least three non co-linear reference l
REFERENCES:
patent: 3854822 (1974-12-01), Altman et al.
patent: 4111557 (1978-09-01), Rottenkolber et al.
patent: 4188544 (1980-02-01), Chasson
patent: 4246606 (1981-01-01), Yoshida
patent: 4375921 (1983-03-01), Morander
patent: 4498778 (1985-02-01), White
patent: 4682894 (1987-07-01), Schmidt et al.
Evans F. L.
The Broken Hill Proprietary Company Limited
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