US 4,725,963 AGranted

Method and apparatus for dimensional analysis and flaw detection of continuously produced tubular objects

AssigneeScientific Measurement Systems I, Ltd.

InventorsMorris Taylor, Ira L. Morgan, Hunter D. Ellinger, Forrest F. Hopkins, Thomas Stephens

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Abstract

An apparatus and method of non-contacting, non-destructive, on-line dimensional analysis and flaw detection of tubular products are disclosed. The apparatus includes penetrating radiation sources and detectors arranged about the product to be examined and a high-speed data processing system which employs novel computed tomography techniques to provide high precision dimensional estimates and flaw detection. The apparatus is capable of continuously determining the outside diameter, inside diameter, wall thickness, ovality, eccentricity, and weight-per-foot over a wide range of temperatures for essentially tubular products produced on a unit or continuous basis. The apparatus can also detect process-induced flaws in the products.

Claims17

Dependent claims

Apparatus for determining measurements on and detecting flaws in tubular or cylindrical objects of known density having an outer circumference and an inner circumference, comprising:

(a) a plurality of transmitting means angularly disposed about the object to be measured for transmitting a fan beam of known intensity containing a plurality of photons of penetrating radiation along a plurality of paths toward a cross section of the object to be measured;
(b) a plurality of detecting means angularly disposed about the object for detecting photons wherein each of said detecting means is disposed opposite one of said transmitting means for detecting the plurality of photons passing through a cross section of the object from said transmitting means along each path for generating signals representative of the number of photons detected along each of the plurality of paths;
(c) mounting means on which said plurality of transmitting means and detecting means are mounted stationary relative to the other;
and,
(d) processing means for processing the signals from said detecting means to generate measurements of thickness, interior and exterior dimensions, eccentricity, and weight-per-unit-length for the object;
wherein said processing means includes computing means which:
(i) determines the length of the portion of each path which passes through any solid portion of the object from the known density of the object and the density signals associated with each path;
(ii) classifies each length signal as an air region signal, outside region signal and inner region signal;
(iii) corrects each outside region signal for aperture effects;
(iv) determines the coordinates of the center and the diameter of the outer circumference of the object from the outer region signals;
(v) calculates length signals for a hypothetical solid object having the same center coordinates and diameter as the outer circumference of the object;
(vi) subtracts inner region signals from the length signals of the hypothetical solid object to form inside circle length signals;
(vii) determines the coordinates of the center and the diameter of the inner circumference of the object from the inside circle length signals;
and
(viii) computes other measurements, such as eccentricity and thickness, from the coordinates of the centers and diameters of the inner circumference and outer circumference of the object.

12 more elements

A method for determining measurements on and deflecting flaws in tubular or cylindrical objects of known density having an outer circumference and an inner circumference, comprising:

(a) transmitting a plurality of fan beams of penetrating radiation of known intensity toward the object to be measured from different angles, wherein each fan beam contains a plurality of photons which pass through the object along a plurality of paths;
(b) detecting the plurality of photons in each fan beam which pass through the object along each of the paths;
(c) generating signals representative of the number of photons detected along each of the plurality of paths;
(d) determining the average density of the plurality of photons along each of the plurality of paths and generating density signals for each path;
and
(e) processing the density signals to determine measurements of thickness, interior and exterior dimensions, eccentricity and weight per unit length, wherein the step of processing comprises:
(i) determining the length of the portion of each path which passes through the solid portion of the object from the known density of the object and the density signal associated with each path;
(ii) classifying each length signal as an air region signal, outside region signal and inside region signal;
(iii) correcting each outside region signal for aperture effects;
(iv) determining the coordinates of the center and the diameter of the outer circumference of the object from the outer region length signals;
(v) calculating length signals for a hypothetical solid object having the same center coordinates and diameter as the outer circumference of the object;
(vi) subtracting real inner region signals from corresponding length signals of the hypothetical solid object to form inside circle length signals;
(vii) determining the coordinates of the center and the diameter of the inner circumference of the object from the inside circle length signals;
and
(viii) computing other measurements, such as eccentricity and thickness, from the coordinates of the centers and diameters of the inner circumference and outer circumference of the object.

12 more elements

A method for determining measurements on and deflecting flaws in tubular or cylindrical objects of known density having an outer circumference and an inner circumference, comprising:

(a) transmitting a plurality of fan beams of penetrating radiation of known intensity toward the object to be measured from different angles, wherein each fan beam contains a plurality of photons which pass through the object along a plurality of paths;
(b) detecting the intensity of the transmitted radiation which passes through the object along each of the plurality of paths;
(c) generating signals representative of the intensity of the radiation detected along each of the plurality of paths;
(d) determining the average density of the object along each of the plurality of paths and generating density signals representative of the average density of the object along each path;
and
(e) processing the density signals to determine measurements of thickness, interior and exterior dimensions, eccentricity and weight per unit, wherein said step of processing comprises:
(i) determining the length of the portion of each path which passes through the solid portion of the object from the known density of the object, and the attenuation signals associated with each path;
(ii) classifying each length signal as an air region signal, outside region signal and inside region signal;
(iii) correcting each outside region signal for aperture effects;
(iv) determining the coordinates of the center and the diameter of the outer curcumference of the object from the outer region length signals;
(v) calculating length signals for a hypothetical solid object having the same center coordinates and diameter as the outer circumference of the object;
(vi) subtracting real inner region signals from corresponding length signals of the hypothetical solid object to form inside circle length signals;
(vii) determining the coordinates of the center and the diameter of the inner circumference of the object from the inside circle length signals;
and
(viii) computing other measurements, such as eccentricity and thickness, from the coordinates of the centers and diameters of the inner circumference and outer circumference of the object.

12 more elements

Dependencies are inferred from the claim text.