The Incremental Sheet Forming (ISF) process is a new die-less metal forming technology that provides the ability to manipulate single sheet metals into complex 3D shapes. Boeing as the industry partner of the University of Queensland's ISF research has identified humidity as a variable during forming that may adversely affect part quality. This thesis is focused on the construction of an enclosure and control system to regulate the temperature and humidity during testing so that the effect of these variables on part quality may be evaluated in the future.
Initially an enclosure was constructed to the best quality practically achievable with unavoidable leakage presenting only minor error in experimental results. Secondly, a simple control system was developed and tested, which was designed with Python programming language. The control system was able to provide acceptable temperature and humidity control. It was not capable of extremely precise control, i.e. the controlled variables always oscillated about the set points; however this would require further development of the dynamic interaction between humidity and temperature. Finally, the graphical user interface (GUI) was implemented with the Python program and proved to be very useful during testing as it gave a clear representation of real time conditions. Operation of the control system is user friendly and can be initiated to pre-set base conditions with one double-click from the desktop.
Experimentation showed that the range of achievable temperature and humidity combinations varied greatly during testing depending on outside conditions at the time. The ranges recorded during experimental testing were ±6 °C or ±15 %RH. Extended combinations of temperature and humidity may be achieved by taking advantage of outside conditions. For a high humidity test, the optimum time to operate is early in the morning, alternatively for a low humidity test, late in the afternoon.
The temperature of the enclosure can be controlled to ± 1 °C with a maximum error during extended testing of 0.19 °C (19%). Temperature fluctuations due to external sources throughout the tests were insignificant and disturbance resistance is high.The humidity of the enclosure can be controlled to ± 5 %RH for test durations with amaximum error of 2.2 %RH during high humidity tests. The complex relationship between relative humidity and temperature was explored and the simple solution presented worked effectively. The specific humidity of the enclosure was also maintained successfully during testing due to the uncoupled relationship with temperature variation.