Nondestructively determining the dimensional changes of an object as a function of temperature

• US 5,414,648 A
• Filed: 05/31/1990
• Issued: 05/09/1995
• Est. Priority Date: 05/31/1990
• Status: Expired due to Fees

• Current Assignee: Integrated Diagnostic Measurement Corporation
• Original Assignee: Integrated Diagnostic Measurement Corporation
• Inventors: Rice, Robert H., Morgan, Ira L., Bolger, Joseph E., Schindler, Donald G.
• Primary Examiner(s): Cosimano, Edward R.
• Application Number:
  US07/531,322
• Time in Patent Office: 1,804 Days
• Field of Search: 364/550, 364/575, 364/559, 364/560, 364/563, 364/506, 364/507, 378/4, 378/9, 378/54, 378/55, 378/58, 378/59, 72/8, 72/9, 72/12, 72/16, 250/359.1
• US Class Current: 702/155
• CPC Class Codes: G01B 15/06 for measuring the deformation in a solid
• CPC Class Codes: G01N 25/16 by investigating thermal coefficient of expansion

Abstract

An apparatus and method for determining the shape specific contraction and expansion of cylindrical or otherwise geometrically regular-shaped products as a function of time and temperature through high precision, continuous, nondestructive dimensional analysis of a cross-section of the object as the object is heated and/or cooled. The apparatus includes multiple penetrating radiation sources and detectors. In performing the analysis on an object as its temperature changes over a certain temperature range, the apparatus generates curves or formulas representing the changes in a dimension of the object as a function of temperature and/or time.

Claims

1. A method for nondestructively determining the dimensional changes in an object as a function of temperature over a desired temperature range, comprising:

a) scanning a single cross-section of said object with penetrating radiation along a plurality of paths;

b) sensing the temperature of the object as the object is being scanned and generating temperature signals representative of the temperature of the cross-section of the object;

c) generating electrical signals representative of the radiation attenuation along each of the plurality of paths through the cross-section of the object;

d) converting the electrical signals representative of the attenuated penetrating radiation signals into signals representative of the density-length of the object along each of the plurality of paths;

e) processing the density-length signals to determine, by use of a computer model of the object to be examined, dimensional measurements of a cross-section of the object;

f) processing the temperature signals to generate a temperature which corresponds with each determined dimensional measurement;

g) allowing the object to increase and/or decrease in temperature; and

h) periodically repeating steps a) through g) at different temperatures whereby a series of correlated dimensional and temperature measurements are taken of the same cross-section over the desired temperature range.

2. The method of claim 1, which further comprises:

generating a graphical representation of temperature versus dimensional data for each dimension of the object.

3. The method of claim 1, which further comprises:

generating a model of the dimensional data as a function of temperature for each dimension of the object.

4. The method of claim 1, wherein:

the object is geometrically regular-shaped.

5. The method of claim 4, which further comprises:

generating a graphical representation of temperature versus dimensional data for each dimension of the temperature.

6. The method of claim 4, which further comprises:

generating a model of the dimensional data as a function of temperature for each dimension of the object.

7. The method of claim 4, wherein:

a) the geometrically regular-shaped object is cylindrical; and

b) the dimensions determined using the computer model include outside diameter and ovality.

8. The method of claim 7, which further comprises:

generating a graphical representation of temperature versus dimensional data for each dimension of the object.

9. The method of claim 7, which further comprises:

generating a model of the dimensional data as a function of temperature for each dimension of the object.

10. The method of claim 7, wherein:

a) the geometrically shaped object is tubular; and

b) the dimensions determined using the computer model also include inside diameter, wall thickness and eccentricity.

11. The method of claim 10, which further comprises:

generating a graphical representation of temperature versus dimensional data for each dimension of the object.

12. The method of claim 10, which further comprises:

generating a model of the dimensional data as a function of temperature for each dimension of the object.

13. An apparatus for nondestructively determining the dimensional changes in an object as a function of temperature, comprising:

a) means for periodically scanning a single cross-section of the object with penetrating radiation along a plurality of paths;

b) means for periodically measuring the temperature of the same cross-section of the object when the object is scanned with penetrating radiation;

c) means for generating electrical signals representative of the radiation attenuation along each of the plurality of paths;

d) means for converting the electrical signals representative of the attenuated penetrating radiation signals into signals representative of the density-length of the object along each of the plurality of paths;

e) a computer model of the object to be examined and processing means to determine dimensional measurements of a cross-section of the object from the density-length signals produced by the converting means; and

f) means for generating a dimension/temperature profile from the determined dimensional measurements and temperature measurements.

14. The apparatus of claim 13, which further comprises:

means for generating a graphical representation of temperature versus dimensional data for each dimension of the object.

15. The apparatus of claim 13, which further comprises:

processing means for generating a model of the dimensional data as a function of temperature for each dimension of the object.

16. A method for calibrating a process control system which bases its process control calculations on measurements made at elevated or depressed temperatures of the object produced from a specific batch of raw material:

a) preparing a sample object from the batch of material;

b) fixing the sample in place in order to periodically scan a single cross-section of the object with penetrating radiation along a plurality of paths;

c) sensing the temperature of the cross-section of the object and generating temperature signals representative of the temperature of the cross-section of the object;

d) generating electrical signals representative of the radiation attenuation along each of the plurality of paths;

e) converting the electrical signals representative attenuated penetrating radiation signals into signals representative of the density-length of the object along each of the plurality of paths;

f) processing the density-length signals to determine, by use of a computer model of the object to be examined, dimensional measurements of a cross-section of the object;

g) processing the temperature signals to generate a temperature which corresponds with each dimensional measurement;

h) allowing the object to continuously increase or decrease in temperature to the desired temperature;

i) periodically repeating steps b) through h) so as to take dimensional and temperature measurements, using the same cross-section, over the desired temperature range;

j) generating a model of the dimensional data as a function of temperature for each determined dimension of the object; and

k) transferring the generated model of the dimensional data as a function of temperature to the process control system.

17. A method of developing a model of the changes in the dimensions of an object as a function of temperature over a desired temperature range, comprising:

a) scanning a cross-section of the object with penetrating radiation;

b) sensing the temperature of the object as the object is scanned;

c) generating temperature signals representative of the sensed temperature of the cross-section of the scanned object;

d) generating signals representative of the radiation attenuation through the cross-section;

e) processing the attenuation signals by use of a computer model of the object examined to determine the dimensional measurements of the cross-section;

f) correlating the temperature signals generated during a scan with the dimensional measurements generated from the attenuation signals associated with the scan;

g) allowing the object'"'"'s temperature to change;

h) repeating steps a) through f) as the temperature of the object changes in order to generate dimensional measurements and associated temperature signals for the safe cross-section of the object at a plurality of temperatures; and

i) storing the object'"'"'s dimensions as a function of temperature over the desired temperature range.