Research Initiation: Closed-loop Shape Control During Hot Isostatic Pressing Process

热等静压(HIP)工艺的一个重要问题是成形变形的发生，这极大地限制了HIP作为净或近净成形加工技术的潜力。研究的基本目的是探索使用反馈控制原理来减少由于模型不准确和过程扰动而导致的不可预测的形状变形。反馈补偿是根据现场涡流传感器提供的致密化信息实时调整髋部温度和压力来实现的。针对热等静压过程动态特性的多输入、多输出、非线性和不确定性，采用改进的模型预测控制方法设计计算机控制系统。将构造一个状态估计器来根据涡流传感器提供的阻抗值来估计致密化状态。本项目的研究成果不仅有助于提高热等静压质量和生产率的计算机闭环控制系统，而且可能对其他材料加工系统的实时反馈控制系统的开发也有一定的参考价值。如果成功，这项研究将允许以高度的一致性和形状精度从粉末金属生产零件，从而减少废品。

An important problem with the hot isostatic pressing (HIP) process is the occurrence of shape distortion, which greatly limits the potential of HIP as a net or near net shape processing technology. The basic objective of the research is to explore the use of feedback control principles for reducing the unpredictable shape distortion due to model inaccuracy and process disturbance. The feedback compensation is achieved by adjusting the HIP temperature and pressure in real time based on the densification information provided by the in-situ eddy current sensors. Due to the multi-input multi-output, nonlinear and uncertain nature of the HIP process dynamics, a modified version of the model predictive control method will be used to design the computer control system. A state estimator will be constructed to estimate the densification status from the impedance values provided by the eddy current sensors. The research results from this project will not only lead to closed-loop computer control systems for improving HIP quality and productivity, but may also be useful for the development of real-time feedback control systems for other material processing systems. If successful, the research will allow the production of part from powdered metal with a high degree of consistency and shape accuracy, reducing scrap.