ASSESSING CONTROLLABILITY OF LOW PRESSURE DIE CASTING USING PROCESS SIMULATION
The low pressure die casting process is a common technique used to produce aluminum alloy wheels. Controlling and eliminating defects, such as micro- and macro- porosity, in low pressure die cast wheels is an on-going challenge that manufacturers must continually address. Current strategies for eliminating these defects focus on altering casting practice through changes to static operating parameters such as cooling time, or in extreme cases changing die structure. Although reduced defect rates may be achieved through these types of improvements, a complementary and potentially more flexible solution exists in the form of advanced process control. Since defects can be traced to die temperatures at critical location, controlling die temperature should reduce the number of defective castings. The current investigation will assess how advanced control methodologies can be used to improve process performance. To perform this assessment, a casting process model has been developed in ABAQUS, a commercial finite element program. The ABAQUS model has been transformed into a virtual casting process through the use of a wrapper script which runs the process continuously. This approach allows industrial process communication to be emulated and the performance of different control methodologies within this environment to be assessed. An identification experiment was performed on this virtual process by sending a pseudo-random binary sequence to vary a process parameter, active cooling duration, while recording temperatures at different locations. A linear state space model was constructed from the identification data and subsequently used to assess the controllability of the system. The results demonstrate a methodology for developing and evaluating control configurations with the potential to reduce defects. The performance of the state space model was compared with the virtual casting process.
low pressure die casting macro-porosity process control mathematical model
Xinmei SHI Daan M. MAIJER Guy DUMONT1
Dept. of Electrical and Computer Engineering, University of British Columbia, V6T 1Z4, Canada Dept. of Materials Engineering, University of British Columbia, V6T 1Z4, Canada
国际会议
大连
英文
635-642
2007-08-19（万方平台首次上网日期，不代表论文的发表时间）