New measurement method for process control of inductive heating operations of metals into the semi-solid state

用于金属半固态感应加热过程控制的新测量方法

• 批准号: 271002868
• 负责人: Professor Dr.-Ing. Alexander Verl
• 金额: --
• 依托单位: Institut für Steuerungstechnik der Werkzeugmaschinen und Fertigungseinrichtungen (ISW)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/271002868?language=en
• 关键词: New; measurement; method; process; control

In thixoforming, heated workpieces in a semi-solid phase are formed. Semi-solid materials have special properties which are positive for forming. Workpieces for thixoforming are often heated inductively, as this type of heating enables high outputs and efficiencies as well as precise control of the inducted power. Challenges in inductive heating arise due to the uneven heat input due to the skin effect. This makes it difficult to obtain a homogeneous liquid phase fraction in the workpiece, especially at high heating rates.For the measurement of the liquid phase fraction, a current measurement based on the recorded currents at the inductor was developed, which is based on the already known time constant measurement. Due to the skin effect, the currents responsible for heating are concentrated in the edge area of the workpiece. This carries the risk of melting off the edge areas, while the center of the workpiece has not yet reached the liquid phase fraction required for the forming process. Although the melting of the edge areas can be prevented by measured value acquisition and monitoring, but it is not known when the inside of the workpiece has adjusted due to heat conduction effects.On the basis of the values for the liquid phase fraction that can be measured in the edge area of the workpiece, the liquid phase fraction inside the workpiece is to be determined on the basis of a heating model. The model is supported by the measured values of the developed measuring in order to make as accurate a statement as possible about the propagation of the heat energy in the workpiece and the associated melting processes. This heating model will be investigated and implemented in this research project.The heating model will first be tested together with the developed current-based measurement by offline evaluation. Subsequently, the measured quantity acquisition and the heating model will be implemented on the control hardware.

在触变成型中，形成半固态的加热工件。半固态材料具有有利于成型的特殊性能。用于触变成型的工件通常采用感应加热，因为这种类型的加热可实现高输出和效率以及感应功率的精确控制。由于集肤效应导致热量输入不均匀，感应加热面临挑战。这使得很难在工件中获得均匀的液相分数，特别是在高加热速率下。为了测量液相分数，开发了一种基于感应器记录电流的电流测量方法，该方法基于已经已知时间常数测量。由于集肤效应，负责加热的电流集中在工件的边缘区域。这存在边缘区域熔化的风险，而工件中心尚未达到成形过程所需的液相分数。虽然可以通过测量值采集和监控来防止边缘区域熔化，但由于热传导效应，无法知道工件内部何时发生调整。根据可以计算出的液相分数值，在工件的边缘区域测量，根据加热模型确定工件内部的液相分数。该模型由所开发测量的测量值支持，以便尽可能准确地描述工件中热能的传播以及相关的熔化过程。该加热模型将在本研究项目中进行研究和实施。加热模型将首先通过离线评估与开发的基于电流的测量一起进行测试。随后，测量量采集和加热模型将在控制硬件上实现。