This paper proposes a novel technique, called Variable Powder Flow Rate Control (VPFRC), for the regulation of powder flow rate in laser metal deposition processes. The idea of VPFRC is to adjust the powder flow rate to maintain a uniform powder deposition per unit length even when disturbances occur (e.g., the motion system accelerates and decelerates). Dynamic models of the powder delivery system motor and the powder transport system (i.e., five-meter pipe, powder dispenser, and cladding head) are first constructed. A general tracking controller is then designed to track variable powder flow rate references. Since the powder flow rate at the nozzle exit cannot be directly measured, it is estimated using the powder transport system model. The input to this model is the DC motor rotation speed, which is estimated on-line using a Kalman filter. Experiments are conducted to examine the performance of the proposed control methodology. The experimental results demonstrate that VPFRC is successful in maintaining a uniform track morphology, even when the motion control system accelerates and decelerates.
L. Tang et al., "Variable Powder Flow Rate Control in Laser Metal Deposition Processes," Proceedings of the 18th Annual Solid Freeform Fabrication Symposium (2007, Austin, TX), pp. 22-48, University of Texas at Austin, Aug 2007.
18th Annual Solid Freeform Fabrication Symposium (2007: Aug. 6-8, Austin, TX)
Mechanical and Aerospace Engineering
Intelligent Systems Center
Article - Conference proceedings
08 Aug 2007