In Jet Interferometry for Ultra Precise Electrolyte Jet Machining

超精密加工技术允许制造最高价值的部件。部件的复杂性不断发展，研究人员面临着以更精确的方式去除更小体积的材料，同时保持工件完整性的挑战。微加工、微放电/电化学加工和高速激光加工现在通常用于微电子、生物医学和航空航天工业的微部件制造。电解质喷射加工（EJM）是一种较新的工艺，尚未被这些行业以有意义的方式接受。该工艺本身具有几个吸引人的能力，例如能够处理难以加工的材料，而不会导致零件的热负荷和没有诱导的残余应力。该技术的一个特别令人感兴趣的方面是，通过简单的修改，该过程也可以作为增材制造技术反向运行，以精确地沉积存款材料。这里将要进行的工作将使用诺丁汉大学的定制MkI原型EJM工具，该工具最近由研究者完成。以及能够执行材料表面加工，这具有独特的能力，并代表了一个显着的进步，在国家的最先进的。研究人员已经证明了一个新的功能，在计算机控制的信号生成，这是能够创建所谓的“拨号表面”或表面制造对表面纹理/形态的规范，而不是表面粗糙度单独。众所周知，加工过程中的表面纹理控制很难实现，因为表面状况通常决定性能，因此高价值部件的价格很高。通常，微观表面纹理是工程以外的几个研究小组感兴趣的。这些包括研究细胞/表面相互作用的生物医学研究人员和希望提高与流体流动相互作用的表面性能的空气动力学家。为了释放EJM的全部潜力，必须创建新的机器仪器。这种仪器必须允许快速、准确、高精度的过程数据被收集，以支持实时自适应过程控制。它还应该允许进行机器表面计量，这越来越成为成功工业过程的基本要求。对于EJM要成功地利用在研究环境中，关键是作为一种可行的生产技术，这套新的过程仪表必须进行调查，然后开发，以允许准确和及时的计量进行的机器，而过程正在进行中。这里要研究的仪器将分为两个关键领域。首先，一种新形式的喷射激光干涉仪将被设计和优化用于EJM。该传感器将提供高速、高精度的过程控制测量数据。这将允许测量工艺的材料去除速率和直接与射流一致的材料去除区域的形式。此外，还将包括光纤装置，以允许光束传输。由于EJM内的间距很短，因此可以使用高亮度光源（激光）向工件提供光斑。除了喷墨激光器外，还将在机头上部署两个额外的传感器，位于射流外部。这些将是定制设计的单线相干扫描干涉仪设备，配置用于单线检测（以提高采集速率）。这些技术将允许实时收集不同的数据集，这些数据集将通过控制算法进行操作，以执行在线处理和自适应加工。这代表了该工艺用于生产复杂和高价值零件的可行性的一个步骤变化。

Ultra-precision machining techniques permit the manufacture of the most high value components. Component complexity continues to develop and researchers are challenged to remove smaller volumes of material in a more precise manner while maintaining work piece integrity. Micro-machining, micro electrical discharge/electrochemical machining and high speed laser processes are now commonly used for micro component manufacture for the microelectronics, biomedical and aerospace industries. Electrolyte Jet Machining (EJM) is a newer process which is yet to be embraced in a meaningful way by these industries. The process itself has several attractive capabilities, such as the ability to process difficult to machine materials with no resulting thermal loading of parts and no induced residual stress. A particularly interesting aspect of the technology is that, with simple modifications, the process may also run in reverse as an additive manufacturing technique to precisely deposit materials. The work to be undertaken here will make use of a custom built MkI prototype EJM tool at the University of Nottingham which was recently completed by the Investigators. As well as being able to perform material surface machining, this has unique capabilities and represents a significant advancement in terms of the state-of-the-art. The investigators have demonstrated a new functionality in terms of computer controlled signal generation which is capable of creating so called 'dial-up-surfaces' or surface manufacture against a specification for surface texture/morphology as opposed to surface roughness alone. Surface texture control within a machining process is notoriously difficult to achieve, commanding a premium price for high value components since surface condition often dictates performance. Typically, micro surface textures are of interest to several groups of researchers outside of engineering. These include biomedical researchers who study cell/surface interaction and aerodynamicists who look to enhance the performance of surfaces interacting with fluid flow. To unlock the full potential of EJM, novel on machine instrumentation must be created. This instrumentation must allow fast, accurate, high precision process data to be collected to support real-time adaptive process control. It should also allow for on-machine surface metrology to be undertaken which is increasingly an essential requirement for successful industrial processes. For EJM to be successfully exploited in both a research environment, and critically as a viable production technology this novel set of process instrumentation must be investigated and then developed to allow accurate and timely metrology to be undertaken on the machine while the process is under way. The instrumentation to be investigated here will be split into two key areas. Firstly, a novel form of in-jet laser interferometer will be designed and optimised for use with EJM. The sensor will provide high speed, high precision process control measurement data. This will allow the material removal rate of the process and the form of the material removal area directly in line with the jet to be measured. In addition a fibre optic arrangement will be included to allow beam delivery. Since stand-off distances are short within EJM this will be possible with a high brightness source (laser) to deliver a spot to the work piece. In addition to the in-jet laser two additional sensors will be deployed to the machine head, external to the jet. These will be custom designed single line coherence scanning interferometer devices, configured for single line based detection (to allow increased acquisition rates).These techniques will allow the collection of disparate data sets in real-time which will be manipulated through control algorithms to perform online processing and adaptive machining. This represents a step change in the viability of this process for the production of complex and high value parts.