Using exhaust gas mass flow rate to control superplastic forming

An apparatus for superplastically forming a blank into an object comprising:

• a forming die containing the blank;
• means for controlling the superplastic forming of the blank;
• an exhaust gas being exhausted from the forming die at a mass flow rate;
• means for measuring the mass flow rate of the exhaust gas;
• said control means being responsive to the mass flow rate of the exhaust gas;
• the forming die being surrounded by an ambient atmosphere;
• and
• means for fluidly communicating the exhaust gas with the ambient atmosphere.

An apparatus for superplastically forming a blank comprising:

• a forming die containing the blank;
• an exhaust gas being exhausted at a mass flow rate from the forming die during superplastic forming;
• means for controlling the superplastic forming of the blank;
• and
• means for measuring the instantaneous mass flow rate of the exhaust gas;
• wherein
• said control means is responsive to the instantaneous mass flow rate of the exhaust gas.

A method for superplastically forming a blank during a forming cycle period, comprising:

• continuously measuring a mass flow rate for an exhaust gas being exhausted from a forming die while the blank is being superplastically formed in the forming die;
• determining an average mass flow rate for the exhaust gas for the forming cycle period, before the forming cycle period begins;
• continuously comparing the measured mass flow rate with the average mass flow rate;
• and
• controlling the superplastic forming of the blank responsive to the comparison of the measured mass flow rate with the average mass flow rate of the exhaust gas.