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

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.

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.

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.