Fundamental study of the electrical and acoustic characterization of different types of single discharges in wire electrical discharge machining (WEDM)

在线材电火花加工中，对发生的不同类型放电的相互作用所产生的单个能量贡献缺乏基本的了解。此外，这些放电类型对材料去除和边缘区形成的影响在很大程度上是无法解释的。澄清这些相互关系将为有力地记录这一进程创造必要条件，以便获得所需的证明知识。研究假设如下：采用线材电火花加工中单次放电的方式，可以特异性地产生不同类型的放电，并对其进行能量表征，描述其特定的去除过程。该研究方法的核心是实现工业线材电火花加工机器的单放电功能，以及由此产生的追踪连续过程的能力，以追溯到其单个贡献。这样可以分别研究不同的放电类型，并精确表征其对材料局部改性的影响。与连续过程相反，连续过程不允许这种特定的相关性，只允许对转换能量和去除率进行一般分析，单个放电可以用来建立对过程的基本理解，然后可以将其转移回连续过程。为此，必须在商用线材电火花加工机上实现产生单次放电的合适机制。在此基础上，可以首先研究标准排放的具体情况及其影响变量。通过改变放电能量、材料和导线材料，原则上可以表征先前不确定的导线侵蚀现象。随后，进一步开发技术解决方案，不仅产生标准放电，而且产生异常放电和短路。通过这种方式，连续过程中普遍存在的条件被单独再现，并根据引入材料的能量量和由此产生的单个材料去除来描述。为此，建立了一种电声复合过程信号的测量和评价方法，并对材料中的能量耗散进行了相对热分析。

In wire EDM, there is a lack of basic understanding of the individual energetic contributions made by the interaction of the different types of discharge that occur. In addition, the influence of these discharge types on material removal and rim zone formation is largely unexplained. The clarification of these correlations would create a necessary condition for the energetic documentation of the process in order to obtain the needed knowledge for certification. The research hypothesis is the following:With the means of single discharges in wire EDM, different types of discharges can be specifically generated, energetically characterized and their specific removal processes can be described.The implementation of the single discharge functionality for industrial wire EDM machines and the resulting ability to trace the continuous process back to its individual contributions is the core of the research approach. In this way, different discharge types can be investigated separately and their effects on the local material modification can be precisely characterized. In contrast to the continuous process, which does not allow this specific correlation and only enables a general analysis of converted energy and removal rate, individual discharges can be used to build up a basic understanding of the process, which can then be transferred back to the continuous process. For this purpose, a suitable mechanism for generating single discharges on a commercial wire EDM machine must be implemented. On this basis, the specifics of and the influencing variables on standard discharges can first be investigated. By varying the discharge energy, the material and the wire material, the previously uncertain wire erosion-specific phenomena can be characterized in principle. Subsequently, further technical solutions are developed to generate not only standard discharges but also abnormal discharges and short circuits. In this way, the conditions prevailing in the continuous process are reproduced separately and described in terms of the amount of energy introduced into the material and the resulting individual material removal. For this purpose, a measurement and evaluation methodology of combined electrical and acoustic process signals is established, and a relative thermal analysis of the energy dissipation into the material is carried out.