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一种新的单次浇注铸造技术Crimson所使用的能量，并开发一个封装每个阶段能量含量的工艺模型。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，考虑到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长，这些专长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。这些行业借鉴了伯明翰著名铸造研究小组进行的先进研发工作。伯明翰大学多年来一直处于铸造研发的领先地位。今天，它被国际公认为领跑者，而Crimson技术-受限的快速感应熔化单击法-是一种帮助铸造业在产品质量、制造响应和能源使用方面做出阶梯变化的技术。典型的轻金属铸造厂的工作方式如下：将100公斤到几吨的金属在第一炉中熔化，在第二炉中保持约700摄氏度，转移到钢包中，最后倒入铸造模具中。它可能需要一个班次(8小时)来使用典型批次中的所有熔体，任何剩余的未使用的熔体被倒出来再次使用，或者变成废料。还会出现质量问题，必须加以缓解：在熔体保持温度的时间内，大气中的水被还原为氢和氧。在这种温度下，氢在金属中高度溶解，但随着铸件冷却和凝固，气体被喷射到气泡中。气泡在固态铸件中变得疏松，对性能有不利影响，因此，必须尽可能多地从熔体中去除气体。氧气在熔体表面形成一层薄薄的氧化物，当它在不同的熔炉之间转移时，以及当金属最终被浇注时，它不可避免地被夹带到液态金属中。氧化层(或双层)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。在这个过程的每个阶段，由于氧化和炉子效率低下、铸件产量和最终的废料，都会造成能量损失。因此，从最初理论上所需的1.1GJ/吨铝，可以估计每吨铝铸件实际将使用约182GJ/吨铝铸件，而不是经历这个批量过程，而是使用一个高功率的熔炉，一次性熔化足够在封闭的熔炉中填充一个模具的金属。它将坩埚转移到上浇注工位，在重力的作用下，高度由计算机控制模具的填充，以实现最佳的填充和凝固制度。因此，深红方法只将液态铝保持在最短的时间内，从而大大减少了将金属保持在温度下所造成的能量损失。由于达到了几分钟的快速熔化时间，氢在温度下没有很长的时间被吸收，也没有很长时间形成厚厚的氧化层。金属永远不会在重力作用下掉落，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准确测量所研究的每个过程中每个阶段所使用的能量，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一个可供铸造设计师和铸造工程师使用的模型中。

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.