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On-line ultrasonic monitoring of die casting of an aluminum plate with steps of different thicknesses is studied using pulse-echo techniques. Clad buffer rods are inserted into the die wall for the monitoring. The flow front of molten aluminum inside the die has been probed by a two-channel acquisition system with a time resolution up to 1 ms. This information may be used to control the plunger movements. The gap development, due to the shrinkage of the part in the die, and the part solidification are also monitored for the understanding of the cooling process. As expected, it is observed that thicker sections take longer to solidify. The die wall temperature variation derived from the changes in ultrasonic travel time in the buffer rod is also observed. |
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