自修复电磁极工具电化学放电加工新方法研究

Aluminum matrix composites (AMCs) are of great attraction for applications in many industries. However, their poor machinability has to a great extent, hindered the widespread use of these high performance materials. Recently, the Project Leader has employed the Electrochemical Discharge Machining (ECDM) method to shape AMCs, the results obtained so far are very promising. Notwithstanding the achievements of high material removal rates, the problem of electrode tool wear remains to be solved. Recognizing this, a novel ECDM method with a self-restorable electrode is proposed to overcome the tool wear problem as well as to enhance the performance of the traditional ECDM method. In the new method, the electrode tool is made of a magnetic material and is covered with a thin layer of magnetically bound metal powder. With such a purposely designed tool surface configuration, the magnetic tool is protected from damage caused by discharge sparks. Although the metal powder layer would deteriorate, fresh powders are continuously supplied to the magnetic tool with a powder restorable device using the principle of a printing technique. Moreover，taking the advantage of utilizing a electromagnetic electrode, the Lorenz force of the charged particles can improve machining efficiency and stability. The research, including theoretical studies of the machining mechanism of the new method based on electromagnetic and electrochemical discharge theories, particle dynamic and finite element method, with experimental verification. Special attention will be paid to the analysis of the formation of the discharge bubble and its discharge mechanism under the influence of a magnetic field and the metal powders, the analysis of dynamic characters of the electromagnetic electrode，and the analysis of the material removal mechanism. It is believed that the proposed new method can overcome the deficiencies of the traditional ECDM method, and thus provides a high efficient machining method with low tool wear for shaping difficult-to-machine AMC materials.

铝基复合材料是极具应用前景的工程材料，加工困难是限制其工业应用的瓶颈问题。申请者在前期研究中采用电化学放电法加工该类材料，获得了较高的加工效率，然而工具的持续损耗问题限制了该方法在实际加工中的应用。为此本项目提出一种自修复电磁极工具电化学放电复合加工的新方法，新方法不仅可利用工具表面不断建立的动态金属磁粉层来延缓工具本体的放电损耗，还可利用磁场对带电粒子的洛仑兹力来进一步促进材料的去除并提高加工过程的稳定性。本课题拟应用电磁学理论、电化学放电理论、颗粒动力学法和有限元法，通过理论、试验和模拟仿真相结合的方式对新方法的加工机理和规律进行深入研究，重点包括：在磁场及其吸附的磁粉影响下的气泡特征及相应的电化学放电规律；电磁极工具的动态特征及工作规律；复合加工过程中的材料去除机理。本项目的研究成功，将建立一种高效率、微损耗的加工新方法，从而有望解决铝基复合材料的加工难题，具有重要的理论和现实意义。

铝基复合材料是极具应用前景的工程材料，加工困难是限制其工业应用的瓶颈问题。为解决电化学放电法加工该类材料中工具持续损耗的问题本项目提出一种自修复电磁极工具电化学放电复合加工的新方法，新方法不仅可利用工具表面不断建立的动态金属磁粉层来延缓工具本体的放电损耗，还可利用磁场对带电粒子的洛仑兹力来进一步促进材料的去除并提高加工过程的稳定性。本课题应用了电磁学理论、电化学放电理论、和有限元法等方法通过理论、试验和模拟仿真相结合的方式对新方法的加工机理和规律进行深入研究，探索了在磁场及其吸附的磁粉影响下的电化学放电规律；研究了电磁极工具的动态特征及磁粉对工具的保护机理；探索了复合加工过程中的材料去除机理。本项目的研，初步建立一种高效率、微损耗的加工新方法，为解决铝基复合材料的加工难题奠定了基础。本研究还探索了掩膜辅助磁粉电化学放电法进行表面微织构制造以及采用了磁粉电火花沉积法制造功能涂层,均取得了一定的进展。

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