Method for determining the proper progress of a superplastic forming process by monitoring gas-mass outflow
AssigneeMcDonnell Douglas Corporation
InventorKen K. Yasui
Life of this patent
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Abstract
A method and apparatus for determining the progress of a superplastic formation process that uses cumulative gas-mass outflow from a forming part being formed from generally one or more sheets of superplastically formable material, a process that may include selective diffusion bonding of the sheets together. The method includes using the expected initial conditions of the process to determine the gas-mass cumulative exhaust at room temperature and pressure. The method is advantageous over inlet measuring methods where high pressure gas must be measured and any small hole in the system results in large errors.
Claims8
A method for monitoring a superplastic forming process in forming equipment that introduces forming gas to deform a sheet of superplastically formable material into a forming die including:
- determining the initial volume of the forming die into which the sheet is to be formed;
- determining the temperature of the gas within the forming die at which exhaust gas-mass flow measuring equipment is going to start measuring the exhaust gas flow from the forming die;
- determining the ambient pressure and temperature;
- calculating the cumulative gas-mass that should be exhausted from the forming die from the initial conditions of temperature of the gas within the forming die, the ambient temperature and ambient pressure using the formula v=mRT/p where m is the mass of gas at absolute temperature, T, p is pressure and R is a constant that depends on the units used;
- measuring the cumulative exhaust gas-mass that exhausts from the forming die, said measuring being at ambient temperature and pressure;
- and
- comparing the actual cumulative exhaust gas-mass of the process against the calculated cumulative exhaust gas-mass to determine when the sheet has formed into the forming die.
A method for monitoring a superplastic forming process in forming equipment that introduces .forming gas at a controlled gas-mass rate to deform a blank into one or more dies including:
- determining the initial volume of the one or more forming die into which the blank is to be formed;
- determining the temperature of the gas within the one or more forming dies at which exhaust gas-mass flow measuring equipment is going to start measuring the exhaust gas flow from the one or more forming dies;
- determining the ambient pressure and temperature;
- calculating the cumulative gas-mass that should be exhausted from the one or more forming dies from the initial conditions of temperature of the gas within the forming die, the ambient temperature and ambient pressure using the formula v=mRT/p where m is the mass of gas at absolute temperature, T, p is pressure and R is a constant that depends on the units used;
- measuring the cumulative exhaust gas-mass that exhausts from the one or more forming dies at ambient temperature and pressure;
- and
- comparing the actual cumulative exhaust gas-mass of the process against the calculated cumulative exhaust gas-mass to determine when the sheet has formed into the one or more forming dies.
An apparatus to control a superplastic forming process in a forming die including:
- a gas connection to the inlet side of the forming die;
- a gas connection to the exhaust side of the forming die;
- means to assure the exhaust gas is at ambient temperature connected to said gas connection to the exhaust side of the forming die;
- a pressure gage connected to said gas connection to the inlet side of the forming die;
- a gas-mass flowmeter connected to said means to assure the exhaust gas is at ambient temperature for measuring the exhaust gas at ambient temperature.
Dependencies are inferred from the claim text.