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中使用的能源，并开发一个包含每个阶段能量含量的工艺模型。该模型可用于说服铸造设计人员使用更节能的工艺，这些工艺考虑了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，这些专业知识支撑着许多具有竞争力的技术型行业，这些行业对于保持英国航空航天和汽车基地在竞争中的领先地位至关重要。这些行业都得益于伯明翰著名的铸造研究集团的先进研发工作。伯明翰大学多年来一直处于铸造研发的领先地位。如今，它已成为国际公认的领先技术，CRIMSON技术--约束快速感应熔炼单次喷射法--就是这样一种技术，它帮助铸造行业在产品质量、制造响应速度和能源使用方面实现了飞跃。一个典型的轻金属铸造厂往往会以以下方式工作：从100公斤到几吨的金属在第一个熔炉中熔化，第二个熔炉保持在约700摄氏度，转移到钢包中，最后倒入铸模中。在一个典型的批次中使用所有的熔体可能需要一个轮班（8小时），任何剩余的未使用的熔体都要倒出来再次使用，或者变成废料。质量问题也会出现，这必须得到缓解：在熔体保持温度的时间内，大气中的水被还原为氢气和氧气。在这个温度下，氢在金属中是高度可溶的，但是随着铸件冷却和凝固，气体被喷射成气泡。气泡在固体铸件中成为孔隙，并对性能产生不利影响，因此，必须从熔体中去除尽可能多的气体。氧气在熔体表面形成一层薄薄的氧化物，当液体金属在不同的熔炉之间转移时，以及当金属最终浇注时，氧化物不可避免地夹带在液体金属中。氧化物层（或双膜）现在是一种夹杂物，再次对材料性能产生不利影响。金属保持液态的时间越长，吸收的氢就越多，表面的氧化物就越厚。在工艺的每个阶段，由于氧化和熔炉效率低下，铸件产量和最终的废料都有能量损失。因此，从最初的理论1.1 GJ/吨需要熔化铝，可以估计，每运输一吨铝铸件实际上将使用约182 GJ/吨。CRIMSON方法使用高功率熔炉，而不是通过这种批量过程，熔化足够的金属，以填补一个单一的模具，在一次，在一个封闭的坩埚。它将坩埚转移到一个向上浇铸站，以高度计算机控制的方式克服重力填充模具，以实现最佳的填充和凝固状态。因此，CRIMSON方法仅将液态铝保持最短的时间，从而大大减少了由于将金属保持在温度下而造成的能量损失。随着快速熔化时间的实现，在几分钟的数量级，没有很长的时间在温度下吸收氢或形成厚层的氧化物。金属在重力作用下不会下落，因此形成的任何氧化物都不会夹带在液体中。因此，可以生产出更高质量的铸件，从而降低废品率，从而减少总的能量损失。该项目的第一个挑战是精确测量所研究的每个工艺中每个阶段的能量消耗，并计算氧化和废品造成的能量损失。第二个挑战是将这些信息整合到一个模型中，供铸造设计师和铸造工程师使用。

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.