Energy saving in the Foundry Industry by Novel Single Shot Melting Process

该项目旨在比较传统铸造工艺和新型单次铸造技术CRIMSON所使用的能源，并开发一个包含每个阶段能源含量的工艺模型。然后，这个模型可以用来说服铸造设计师使用更节能的工艺，同时考虑铸造质量和设计灵活性。英国在铜、铝和新型轻金属合金方面拥有全球公认的铸造专业知识，支撑着许多具有竞争力的、以技术为基础的行业，这些行业对保持英国的航空航天和汽车基地在竞争中处于领先地位至关重要。这些行业借鉴了伯明翰备受瞩目的铸造研究小组开展的先进研发工作。伯明翰大学多年来一直处于铸造研发的前沿。今天，它是国际公认的领跑者，而CRIMSON技术-约束快速感应熔炼单发法-就是一种这样的技术，它正在帮助铸造行业在产品质量，制造响应能力和能源使用方面做出一步改变。一个典型的轻金属铸铸厂将倾向于以以下方式工作：从100公斤到几吨的金属在第一个炉中熔化，在第二炉中保持在700摄氏度左右，转移到钢包中，最后倒入铸造模具。通常需要一个班次（8小时）才能用完所有的熔体，任何剩余的未使用的熔体都要倒出来再次使用，或者成为废料。质量问题也出现了，这必须得到缓解：在熔体保持在一定温度的时间内，大气中的水被还原为氢和氧。在这个温度下，氢极易溶于金属，但当铸件冷却并凝固时，氢气会喷射成气泡。气泡在固体铸件中变成孔隙，对性能有不利影响，因此，必须尽可能多地从熔体中除去气体。氧气在熔体表面形成一层薄薄的氧化物，当液态金属在不同的熔炉之间转移和最终浇注时，它不可避免地被夹带在液态金属中。氧化层（或双膜）现在是一种夹杂物，再次对材料性能产生有害影响。金属保持液态的时间越长，吸收的氢就越多，表面的氧化物也就越厚。在过程的每个阶段都有由于氧化和炉效率低下而造成的能量损失，铸件产量和最终报废。因此，从最初的理论1.1 GJ/吨熔融铝的需求，可以估计每吨铝铸件的实际运输将消耗约182 GJ/吨。CRIMSON的方法没有经过这批处理，而是使用一个大功率的熔炉，在一个封闭的坩埚里，一次熔化足够的金属来填充一个模具。它将坩埚转移到一个上浇铸站进行高度计算机控制的模具填充，对抗重力，以获得最佳的填充和凝固状态。因此，CRIMSON方法只保持液态铝的最短时间，从而大大减少了由于保持金属在温度下的能量损失。随着快速融化时间的实现，大约几分钟，在温度下，氢被吸收或形成厚层氧化物的时间并不长。金属不允许在重力作用下下落，因此形成的任何氧化物都不会被夹带在液体中。因此，可以生产出更高质量的铸件，从而降低废品率，从而减少整体能源损失。该项目的第一个挑战是准确测量所调查的每个过程中每个阶段使用的能量，并计算氧化和废料造成的能量损失。第二个挑战是将这些信息整合到铸造设计师和铸造工程师可以使用的模型中。

This project aims to compare the energy used in traditional foundry processes and a novel single shot foundry technology, CRIMSON, and to develop a model of the processes that encapsulates the energy content at each stage. This model can then be used to persuade casting designers to use more energy-efficient processes which consider casting quality as well as design flexibility. The UK retains a globally recognised casting expertise, in copper, aluminium and new light-metal alloys that underpins many competitive, technology-based industries vital to keep the UK's aerospace and automotive base ahead of the competition. These industries draw on advanced R&D work carried out by Birmingham's high-profile Casting Research Group.The University of Birmingham has been at the leading edge of casting R&D for many years. Today, it is internationally acknowledged as a front runner, and the CRIMSON technique - Constrained Rapid Induction Melting Single Shot method - is one such technology which is helping the casting industry make a step-change in product quality, manufacturing responsiveness and energy use.A typical light-metal foundry will tend to work in the following way: from 100 kg to several tonnes of metal is melted in a first furnace, held at about 700 oC in a second, transferred into a ladle and finally poured into the casting mould. It can take a shift (8 hours) to use all the melt in a typical batch and any leftover unused melt is poured off to be used again, or becomes scrap. Quality issues also arise, which must be mitigated: during the time for which the melt is held at temperature, atmospheric water is reduced to hydrogen and oxygen. The hydrogen is highly soluble in the metal at this temperature, but as the casting cools and solidifies, the gas is ejected into bubbles. The bubbles become porosity in the solid casting and have a detrimental effect on performance, therefore, as much gas must be removed as possible from the melt. The oxygen forms a thin layer of oxide on the melt surface, which is then inevitably entrained in the liquid metal when it is transferred between the different furnaces and when the metal is finally poured. The oxide layer (or bi-film) is now an inclusion which, again, has a detrimental effect on the material properties. The longer the metal is held liquid, the more hydrogen is absorbed and the thicker the oxide becomes on the surface.At each stage of the process there are energy losses due to oxidation and furnace inefficiencies, casting yields and eventually scrap. So from an initial theoretical 1.1 GJ/tonne required tomelt aluminium it is possible to estimate that each tonne of aluminium castings shipped will actually use about 182 GJ/tonne.Instead of going through this batch process, the CRIMSON method uses a high-powered furnace to melt just enough metal to fill a single mould, in one go, in a closed crucible. It transfers the crucible into an up-casting station for highly computer-controlled filling of the mould, against gravity, for an optimum filling and solidification regime. The CRIMSON method therefore only holds the liquid aluminium for a minimum of time thus drastically reducing the energy losses attributed to hold the metal at temperature. With the rapid melting times achieved, of the order of minutes, there isn't a long time at temperature for hydrogen to be absorbed or for thick layers of oxide to form. The metal is never allowed to fall under gravity and therefore any oxide formed is not entrained within the liquid. Thus higher quality castings are produced, leading to a reduction in scrap rate and therefore reduced overall energy losses.The first challenge in the project is to measure accurately the energy used at each stage in each of the processes investigated and to calculate the energy losses from oxidation and scrap. The second challenge is to incorporate this information into a model that can be used by casting designers and foundry engineers.