Thermal monitoring instrumentation for metal additive manufacturing - PYRAM

用于金属增材制造的热监测仪器 - PYRAM

• 批准号: EP/W025035/1
• 负责人: Ralph Tatam
• 金额: $ 122.56万
• 依托单位: CRANFIELD UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FW025035%2F1
• 关键词: Thermal; monitoring; instrumentation; metal; additive

The aim of this proposal is to develop a temperature measurement instrument for use in a wire based additive manufacturing (AM) processes. The instrument will use a lensed fibre-optic cable fed to a camera-based design, allowing it to operate in different deposition environments and will be compatible with a variety of metals. The system will provide real-time temperature images of the AM melt pool that will improve the effectiveness of the additive manufacturing processes. In turn, this will result in high-quality AM parts and improved productivity via quality control enhancement. Metal AM of large components will have a major impact on the production of specialist components due to its inherent cost and material savings as well as offering a route to easily changing the design and allowing component customisation. Metal components are formed by feeding a wire into a welding arc, or laser, which is then moved to deposit molten metal in predetermined positions and a structure is built by doing this in repeating layers. Structures built using this technique can have excellent material properties, but due to variations in the temperature of the melt pool, the internal metal structure can sometimes be irregular, which causes variations in the final mechanical properties of the component. Temperature measurement of the melt pool surface addresses these variations by ensuring the production of; a constant material internal structure, repeatable layer dimensions and component temperature heating/ cooling cycles, thereby ensuring good component quality control. If the metal surface temperature can be specified, measured and controlled, then this guarantees the mechanical properties of the component are within the required specifications.Thermal camera measurements of melt pools is challenging as the temperatures can be in excess of 2400 deg. C. Also, the intense light from the arc can blind the camera or degrade measurement accuracy. Commercial thermal cameras used for AM processes tend to have large, fixed lenses which makes installation of the lensed camera difficult in the limited space around typical AM torches as they need to be line-of-sight with the melt pool, to view it clearly. To overcome these challenges, a novel optical fibre two-wavelength camera instrument, tailored for the wire-based AM process operating over the range 800-2400 deg. C, will be developed, which is not blinded by the intense arc light and has compact and flexible imaging optics. This allows the camera head to be used in restricted spaces but the camera instrumentation itself can be located some metres away from the AM processing tool, on the robot arm. This instrument could also be usefully used with other AM welding processes with some adaption, and applications where physical access is very restricted e.g. gas turbine engines. The two-wavelength design uses an optical-fibre bundle and a camera together with special filters to block the unwanted light but transmit two image "colours". These two colours are then imaged on the same camera sensor separately. The temperature of the images is determined by the ratio of the two light signals. This ensures a wide operating temperature range, without requiring special knowledge of the thermal properties of the melt pool itself. The instrument design overcomes the challenges presented by the intense light and restricted access. Custom software will produce a real-time temperature map of the melt-pool, and allow the instrument to be then used with the process software controlling the AM machine. This will allow power feedback control of the welding arc and hence limit significant variations in the melt pool temperatures. The research will develop a state-of-the-art instrument addressing one of the major challenges facing metal AM processes and provides a route to fabricating reproducible and specification compliant components.

该提案的目的是开发一种用于线材添加剂制造(AM)工艺的温度测量仪器。该仪器将使用透镜光纤电缆馈入基于相机的设计，使其能够在不同的沉积环境中操作，并将与各种金属兼容。该系统将提供AM熔池的实时温度图像，这将提高添加剂制造工艺的有效性。反过来，这将导致高质量的AM部件，并通过质量控制增强提高生产率。大型部件的金属AM将对专业部件的生产产生重大影响，因为其固有的成本和材料节约，以及提供了一条轻松更改设计和允许部件定制的途径。金属部件是通过将焊丝送入焊接电弧或激光中形成的，然后将焊接电弧或激光移动以将熔化的金属沉积在预定位置，并通过在重复的层中这样做来建立结构。使用这种技术建造的结构可以具有出色的材料性能，但由于熔池温度的变化，内部金属结构有时可能是不规则的，这会导致组件的最终机械性能发生变化。熔池表面的温度测量通过确保生产恒定的材料内部结构、可重复的层尺寸和组件温度加热/冷却循环来解决这些变化，从而确保良好的组件质量控制。如果可以指定、测量和控制金属表面温度，则可以保证部件的机械性能符合要求的规格。熔池的热像仪测量具有挑战性，因为温度可能超过2400℃。另外，来自弧光的强光可能会使相机失明或降低测量精度。用于AM工艺的商用热像仪往往具有大而固定的透镜，这使得在典型AM手电筒周围的有限空间中安装透镜摄像机变得困难，因为它们需要与熔池对准视线，才能清楚地观察到它。为了克服这些挑战，一种新型的光纤双波长摄像仪器，专为工作在800-2400℃范围内的有线AM工艺量身定做。C，它不会被强烈的弧光遮挡，具有紧凑灵活的成像光学系统。这使得摄像头可以在有限的空间中使用，但摄像头本身可以安装在距离AM处理工具几米远的机械臂上。该仪器还可用于其他AM焊接工艺和物理访问非常受限的应用，如燃气轮机发动机。双波长设计使用光纤束和摄像头以及特殊的滤光片来阻挡不需要的光，但同时传输两种图像的“颜色”。然后，这两种颜色分别在同一相机传感器上成像。图像的温度由两个光信号的比率确定。这确保了较宽的工作温度范围，而不需要对熔池本身的热性能有专门的了解。仪器设计克服了强光和限制进入带来的挑战。定制软件将生成熔池的实时温度图，然后允许仪器与控制AM机器的过程软件一起使用。这将允许对焊接电弧进行功率反馈控制，从而限制熔池温度的显著变化。这项研究将开发一种最先进的仪器，以解决金属AM工艺面临的主要挑战之一，并提供一条制造可复制和符合规范的元件的途径。