外文翻译--钢铁连续铸造中模具温度场的实验研究与数值模拟-精品

钢铁连续铸造中模具温度场的实验研究与
数值模拟
（1）铸造工程研究中心,大连理工大学,中国大连116024
（2）材料科学与工程学院, 鞍山科技大学,中国鞍山114044
原稿收于2005年11月9日,校订于2006年2月16日
模具是连续铸造机械中的核心, 水冷模中的热传输与凝固在钢铁连续铸造中是最重要的因素，为了研究模具壁的温度分布，设计了一个模具模拟设备，并且用其做了一些实验，实验结果表明模具壁温度接近了冷却水的温度，在这个实验结论的基础上，提出并推论了一个等效热传导系数。

这个系数可用来解决熔融水和冷却水之间的热传输，还可用来描述模具的热传输体积。

通过这个等效热传导系数，可以非常容易和方便的对连续铸造的凝固过程进行数值模拟。

并且计算结果和实验结果是一致的，铸造速度和水流量对模具温度场的影响也进行了讨论。

关键词：连续铸造模温度场数值模拟
1．引言
钢铁工业是国家经济的支柱行业，连续铸造技术的水平也一直是现代化的象征。

在中国钢铁连续铸造的比例接近了90%，而世界其余地区在2003年底就超过了这个水平。

中国钢铁产业的规模大但不强。

创造高附加值产品是中国钢铁产业在未来的发展方向。

钢铁连续铸造的示意图如图1。

浇铸钢水连续通过模具冷却1区，喷水2区，辐射冷却3区。

从方坯的表面到中心发生凝固，然后完成整个方坯的铸造。

作为一个主要的热提取装置，要求模子能够把钢水中的热量转移到冷却水中，并能够凝固一个有足够厚度的壳以能够承受钢水的压力。

方坯的大部分缺陷形成于模子中，并在喷水区中扩展，所以，研究模子的温度分布是非常重要的。

它不仅能够优化模具获得更热应力，从而改善钢坯质量，而且还可以延长模具寿命提高生产效率和经济效益。

许多研究人员已经花了很多时间在这个领域上，其中包括在模具中凝固的研究和模具粉末的热传递。

在钢铁的连续铸造中，模具壁受1500摄氏度的高温钢和20摄氏度大流程率的冷却水的影响。

如果在古典的理论基础上根据热的导电率处理边界热传递的情况，模具壁温度超过铜的熔点。

实际上，在模子边界有热抵抗成分存在, 比如模子粉末和空气缝隙。

热抵抗减少了能够使得模子温度发生软化处理行为的边界热流，所以减少了模子扭曲的可能性。

它确保了铸造能够连续正常的进行。

通过实验研究，论文得出了模具壁的热传递规律并推论出了等效热传导系数，这使得在连续铸造过程中能够对包括模子在内的方坯钢的凝固过程进行数值模拟。

模拟结果和实验结果是一致的，除此之外，论文中计算并且讨论了铸造速度和水流率对模具温度场的影响。

2．实验
模具的实验装置和模具壁的热流如示意图2所示，锡铅合金已经用于该实验，因为它的密度和热传导与钢铁接近。

加热合金到大约到260度，放进保温装置中，用装甲热点偶测量温度，并用DUT3000温度采集模块收集数据。

把冷却水通过模子，水的入口与流量表相连接。

水的初温为20摄氏度。

制造一个高5mm和8mm的铜模子，根据图2，a=8h,b=2h。

热电偶T1插入到接近模子底面的铁水中，测量的结果是钢坯的表面温度。

热电偶T2、T3和T4分别测量模具壁和冷却水的温度。

图3和图4显示了水流率和模具壁厚度对模具壁界面上温度分布的影响，可以看出来，当水流率沿着模具壁的热传递方向增加时，熔融金属和模具壁界面之间的热梯度随着冷却水流率的增加而增加。

总的来说，模具壁的温度接近冷却水的温度而不是熔融金属的温度。

图3和图4表明，测量的结果指示出熔融金属和模具壁之间的模子界面存在热抵抗，阻碍了热传递。

然而，模具壁和冷却水之间的模具界面的热抵抗却很小。

3．边界等效热传导系数建模
在连续铸造中，从模具界面到冷却水之间熔融铁热量的热传递是一个复杂的过程，模具壁边界和熔融铁同时发生热传递有几种方法，如图5所示。

空气缝隙和模子粉是阻碍熔融铁和模子界面之间热传递的空气缝隙和模子粉是热抵抗，如图3和图4所示。

这篇论文提出了一个等效热传导系数，在经典理论的基础上以热系数的形式，处理熔融钢铁和模具之间、模具和冷却水之间的边界热传递。

在稳定的生产条件下，被冷却水从熔融金属中放出的热量在模子可以估计为
3.1模子和水之间的边界等效热传导系数
在图3和图4中模具壁和冷却水之间的模具界面的热抵抗很小，基于这个原因，边界等效热传导系数用来处理基于古典理论的热传导，其复杂关系为：
其中下标m和w分别指模具和水
3．2熔融铁和模具之间的边界等效热传导系数
在稳定的生产条件下，由冷却水吸取的热率为：
其中，W指水流率，单位；指比热容，单位，kJ／(t·℃)；Pw指密度，单位,
和分别指冷却水的流入温度和流出温度，单位℃
在稳定的生产条件下，从熔融金属的进入到熔融金属的出来，模子中的总热传递量可以被估计出来，以致模子能有一个足够厚度的凝固壳。

当铸造速度是V，模子高度是l时，模子中熔融金属的热流率则为：
实际上，在连续铸造的情况下，热量的损失则更小，在模子中可以忽略不计，根据热量平衡原理有：
测量结果表明，在熔融金属和模具壁之间的模子界面存在热抵抗，所以，边界等效热传导系数为：
其中下标mo和m分别指熔融金属和模子。

根据傅立叶法，熔融金属和模具壁之间的边界热传递关系为：
其中qmo指热流量
当模子壁的边界面积是A时，就有：
结合式(4)，(2)，(5)一(7)，可给出边界热抵抗的公式为：
3．3冷却水流率W的设计：
在模子中稳定的生产情况下，从进口熔融金属到出口熔融金属就会有一个足够厚度的凝固壳，总传递的热量可以估计出来。

目前，提高连续铸造的速度是提升钢铁产量的一个重要因素，因此，确定冷却水的流率W是一个重要的任务。

结合式(4)，(2)和（3)，模子中冷却水流率W和连续铸造速度V之间的关系就可以得出以下公式：
分析结果表明，等效热传导系数取决于连续铸造速度和冷却水，它使得在连续铸造过程中能够对包括模子在内的方坯钢的凝固过程进行数值模拟变得可能。

4．对连续铸造模的温度场数值模拟仿真
4．1温度场的数值模拟仿真
热平稳衡方程式：
连续铸造的温度场是空间中的一个稳态场，它有以下假定：
（1）热物理参数不变
（2）模子的锥度和振动可以忽略不计
（3）用温度补偿方法计算潜伏热
在热平衡理论的基础上，公式（10）转变成交变的有限差分方程，对方坯连续铸造的温度场的数值模拟仿真也可以进行。

模具尺寸是l02mmx 102mm,高度是700mm，壁厚是26mm，冷却水沟道的尺寸是12mmxl5mmx680mm，过程参数列在表1中。

在表1的情形中，钢坯loomm xloomm连续铸造的温度场是由连续铸造模的温度场的数字模型模拟而来的。

所得数字结果能够满足天然新产品的要求，模具部分的温度如图6所示，可以看出来模子壁的最高温度分布在模子中金属高度5到10mm的热壁上。

在离模子热壁
2-3mm的地方，温度在模子垂直的部分有最高的级别。

这个部分最可能会被扭曲和破裂，在靠近模子角落地方的温度比较低，因为二维热传递的缘故，计算结果和9式结果相当吻合。

4．2处理模子壁温度参数的效果
4．2．1冷却水流率
对模子的初步冷却是成功获得连续铸造产品的一个重要因素，如图7所示，随着冷却水流率的减少，模子的温度明显上升。

4．2．2铸造速度
如图8所示，如果铸造速度增加到0.1m/min,那么模子壁温度就会增加4度，高温区就会消耗。

当铸造速度超过到3m/min时，模子热壁的温度就会达到或才超过模子的熔融温度。

所以铸造速度必须要伴随水流率的增加而增加。

5．结语
（1）本文设计了一个模子模拟装置以能演示出模具壁的温度分布实验。

结果表明模子壁的温度总接近冷却水的温度。

引入了等效热传导系数来考虑熔融金属和冷却水之间的热传递。

它使得在连续铸造过程中能够对包括模子在内的方坯钢的凝固过程进行数值模拟变得可能。

（2）完成连续柱铸造的实验以及相应的模拟，实验结果和计算结果的一致使得连续铸造的温度场计算计划有效。

（3）连续铸造过程中对模子的温度场进行数字模拟仿真的VC计划正在进行，论文还计算和讨论了铸造速度和水流率对模子壁温度的影响。

后记——这篇作品得到了中国自然科学基金会的支持(No．599995442)
参考文献：
Green Package mechanical design of the key technologies Abstract:Green product design from the content and characteristics of full life cycle, concurrent engineering, removable and modular design method to study the mechanical design of green packaging of the key technologies required to explain the packaging machinery to carry out the need for green design and urgency of unforced.
20 since the early 70 century, industrial pollution caused by global environmental degradation, to an unprecedented degree, the increasingly serious ecological crisis calls for all countries in the world to strengthen environmental protection, in order to save human life on Earth, to ensure that the quality of human life and economic sustainable development. Entered since the 90's, especially the June 1992 World Conference on Environment and Development adopted "Agenda 21" In the future, national environmental protection strategy has experienced a new change, the global industrial restructuring takes on a new strategy for the green trend, which resource utilization is to rationalize the production of a small amount of waste on the environment pollution-free, less pollution direction. In such a "green wave" Under the impetus of green design emerged, corresponding to green product design technology has also become a hot topic at home and abroad Packaging machinery are modern packaging products packaging industry production the most important technical equipment, with the high-tech packaging machinery industry to the growing penetration, on the one hand, people are constantly developing new products, to stimulate consumption and phase out old products, on the other hand, consumption of resources mass production at the same time, increasing waste, the environmental cause great harm. Therefore, it is necessary to change traditional packaging machinery design and development model, at the design stage is necessary to take into account the packaging machinery at its entire life cycle (design, processing, manufacturing, assembly, use, repair until after the deal with the disposal of scrap process) on the environment without impact or minimal impact, and low consumption of resources, ease of recycling, green features, that is green design.
1） green product design and characteristics of the connotation
1.1The connotation of green product design
Green Products are referring to in its full life cycle process, to meet specific environmental protection requirements, the ecological environment or endanger the minimal sound, the highest utilization rate of resources, the lowest energy consumption products. Green product design is based on the protection of environmental resources as the core of the product design process. Products at the entire life
cycle, giving priority to product environmental attributes (use of natural resources, environmental and human impact, disassembly, recyclability, reusability, etc.), and as design objectives, in meeting the the requirements of environmental objectives simultaneously, in parallel to ensure that products should be considered and the basic functions of life, economy and quality. 1．2Green Product Design and Product Design of the traditional distinction
In traditional product design, design only to the product life cycle, market analysis, product design, process design, manufacturing (CAD / CAPP / CAM), sales and after-sales service, such as some stage, but many are also designed from the enterprises themselves development and economic interests, just consider how to meet user requirements, to meet the product's basic attributes (such as basic function, quality, longevity, cost, etc.), without considering or property with little regard for the environment, and its guiding principles of design as long as the products are easy to manufacturing, and has the required functionality, performance can be.
And green product design is different, which includes conceptual design, functional design, production design, the use of abandoned until after the recovery, reuse and treatment, etc., that is, the entire product life cycle design, are from the "cradle-to-reproduce" process. It requires designers to design at the application of concurrent engineering idea, put the rationalization of resource utilization, reduce energy, easy to demolition so that renewable sources of use and protection of ecological environment, and to ensure that product features, quality, service life and cost out the various requirements Designed for the same goals, and ensure the production of J can be smoothly carried out. Green product design will enable resources to maximize the utilization of energy to reduce or eliminate the waste products on the environment caused by pollution, are a concrete manifestation of sustainable development.
1．3 Green product design characteristics
1）Product design closed-loop design process. Traditional products are of the full life cycle from design, manufacture until abandoned at all stages, and after the Product in all aspects of waste is not being considered is an open-loop process. Green Design of the product life cycle in addition to traditional product life cycle, but also after the demolition of abandoned Products Recycling, treatment and disposal, is a closed-loop process.
2）Saving resources and energy. Green product design to optimize the overall product performance, so that the composition of products, components and materials are fully effective use, reducing the material resources and energy demand, resource consumption slowed to a
reasonable and sustained use of .
3）Reduce environmental pollution from the source on green product design to reduce the waste generated, reduce waste caused by a large number of daunting problems,
4）Protect the environment is conducive to the maintenance of ecosystem balance and achieve sustainable development of green products are the core of the design. Green product design can take precautionary measures to prevent the products and processes of environmental negative effects.
2．1 The structural design of packaging machinery
At present, the trend of packaging products have been refined and diversified, in which major environmental changes, the diverse, flexible and has a wide range of switching functions of packaging machinery in order to adapt to market demand. Is based on this, green structural design of packaging machinery in addition to industrial and commercial products should meet the basic requirements for packaging function, the main considerations improve the utilization rate of resources, structure, easy to deal with the demolition and recycling. Lower consumption of resources, good performance and Recycling demolition performance packaging machinery for the main elements of green design. Its specific principles are: to simplify the structural design of packaging machinery to minimize non-essential parts; use of multi-function parts, so that fewer parts to reduce consumption of resources; for spare parts, support, load optimized layout design, so that the entire Machine Products, as far as possible "small" and improve material utilization.
2．2 Materials for the Packaging Machinery Design Technology Materials-oriented design technology is based on materials targeted at the entire product life cycle (design, manufacture, use, disposal) of each stage to the environmental impact of materials and effective use as a control objective, in the realization of product functionality At the same time the requirements to minimize environmental pollution and resource consumption for at least the green product design technology.
Based on this, in green packaging machinery design, the materials used for the selection and management should be followed: 1) the use of easy processing of materials, packaging machine parts to reduce the difficulty of processing and the reject rate, and an earnest job of machines, Electricity, gas and other basic items matching the processing quality, try to reduce energy consumption; 2) minimize the types of materials used, in particular, are based on cost considerations, should be minimal use of expensive raw materials, rare;
3) the priority to use recyclable and easy to decompose, can be recycled, low-pollution materials; 4) packaging machines used in a variety of
materials are often anisotropic, so the green in packaging machinery design, should be considered by the orientation of the role of materials, making it the largest performance to exert . 5) to consider the needs of new packaging materials, packaging materials Packaging Machinery Change will lead to changes in packaging machinery for green design, special for the 20th century, since the 70's, industrial pollution caused by global environmental degradation, reached an unprecedented level increasingly serious ecological crisis calls for all countries in the world to strengthen environmental protection, in order to save human life on Earth, to ensure that the human quality of life and sustainable economic development. Entered since the 90's, especially the June 1992 World Conference on Environment and Development adopted "Agenda 21" In the future, national environmental protection strategy has experienced a new change, the global industrial restructuring takes on a new strategy for the green trend, which resource utilization is to rationalize the production of a small amount of waste on the environment pollution-free, less pollution direction. In such a "green wave" Under the impetus of green design emerged, corresponding to green product design technology has also become a hot topic at home and abroad.
Packaging machinery are modern packaging products packaging industry production the most important technical equipment, with the high-tech packaging machinery industry to the growing penetration, on the one hand, people are constantly developing new products, to stimulate consumption and phase out old products, on the other hand, consumption of resources mass production at the same time, increasing waste, the environmental cause great harm. Therefore, it is necessary to change traditional packaging machinery design and development model, at the design stage is necessary to take into account the packaging machinery at its entire life cycle (design, processing, manufacturing, assembly, use, repair until after the deal with the disposal of scrap process) on the environment without impact or minimal impact, and low consumption of resources, ease of recycling, green features, that is green design.
2．3 Packaging Machinery Manufacturing Process Design
Packaging machinery manufacturing process of green design include the following: 1) adopt reasonable new processing methods, packaging machinery Optimize Process Design program, to determine the optimum process parameters and reduce raw material consumption, so that the production process of waste minimization; 2) to use the appropriate packaging machinery production processes, reduce waste defective products improve the passing rate, improve energy efficiency and reducing consumption; 3) in the packaging machinery of the production
process should be to minimize the impact on the environment or the operator or hazardous substances.
2．4 Modular design
Modular design of packaging machinery are carried out the structural design of an effective method, but also a green product design program to determine its structure, one of the common means. Modules are designed in a certain range, at different functions, or the same function under different performance, different specifications of the products on the basis of functional analysis, and design into a series of functional modules, through the selection and combination of modules may constitute different products to meet the diverse needs of the market. Packaging machinery, especially some of the complex structure of packaging machinery products, all S are from a number of
sub-components must function in the composition. Design, as far as possible the various sub-components will be designed as a relatively independent functional modules, such as machine equipment, packaging machinery used modules, for use of one or several units can adapt to changes in product packaging. This green product design idea with modular design methods, you can at the same time the functions of packaging machinery to meet the property and the environment property, so it can shorten the development cycle of packaging machinery to increase the product range, improve its quality so as to quickly respond to market Change; On the other hand can also reduce or eliminate negative impacts on the environment to facilitate the reuse, upgrade, repair and packaging machinery after the demolition waste, recycling treatment.
2．5 Designed removable
Good is removable to facilitate maintenance of packaging machinery, parts and materials used recyclable, renewable an important guarantee that only good can be achieved Disassembly complete Materials Recycling and possible reuse of parts and components to achieve cost savings, reduced pollution and protecting the environment. Based on this, first importance should be removable on the concept of design. Packaging Machinery R & D staff should be always with the user, product maintenance and resources to contact the Recycling Department to obtain the structure of packaging machinery at the demolition of the existing deficiencies and to design the development of removable prepare the relevant data. Secondly, in order to facilitate the demolition, packaging machinery for whole system planning, it is necessary to consider the demolition of the structure on the ease, the corresponding design objectives, the structure of the program.
2．6 Life expectancy balanced design
Product implementation of various components of a balanced life is a green product design, a basic principle, so in the green packaging
machinery design, one must also consider the design of packaging machinery parts should have a balanced life. Obviously, the packaging machinery, in order to achieve them each with the same or similar parts of life is impossible. Is based on this, in the design and development, consideration should be given to make packaging machinery whole equipment comprising a number of important module has a longer life expectancy, at the same time easy to damaged equipment should be easy to replace modules, for some of the key modules involved in the design of safety should be taken into account designed to repair, then Detect structure.
2．7 Ergonomic design
Ergonomic design objective is to reduce the use of packaging machinery human error, mechanical and exert their own characteristics in order to improve the overall reliability of packaging machinery. Optimize the use of ergonomics principles of man-machine packaging machinery systems, such as, in the green packaging machinery design, control, control systems are reliable, not only requires packaging machinery itself has a satisfactory accuracy, but also suitable for the use of people accustomed to , make it easier to identify the operation, not easy to make mistakes, involving security issues, more people should be on anti-misoperation design; Furthermore Designed try suitable operating environment in the work of people required to minimize fatigue, interfere with the operation of factors, such as temperature, humidity, pressure, light, color, noise, vibration, dust, space, and thereby facilitate the packaging machinery to achieve the best efficiency of man-machine system in order to enhance labor productivity and the quality of their work.
2．8 Usability design
Packaging machinery are the backbone of modern packaging industry, it is the collection of machines, electricity, gas, optical, biological and magnetic integrated machinery and electronics equipment. Based on availability considerations, packaging machinery in the green design should focus on improving the packaging machinery reliability and stability, efforts to improve the automation of packaging machinery, packaging machinery will be the R & D and computer closely integrated with the implementation of Mechatronic Control will be automated operating procedures, data collection systems, automatic inspection system, automatic diagnosis system status detection, computer-aided design, rapid prototyping technology, process technology used in packaging machinery more of).
3 Conclusion
Green product design as a new design method has been widely at home and abroad, the recognition and attention, and has been applied in the enterprise have achieved considerable ecological and economic
benefits. At present, China's large-scale production line of packaging machinery has been introduced mainly in the packaging machinery from abroad equipment developed on the basis of. Especially after China's accession to the WTO, packaging machinery industry in an increasingly competitive, market competition will become increasingly fierce, while the green trade barriers abroad, also the packaging machinery industry in our country has put forward higher requirements. Therefore, based on green product design technology, packaging machinery to increase "green features", improve the reliability of packaging machinery and stability of our country in order to enhance packaging machinery enterprise core competitiveness of China's packaging machinery industry with international practice as soon as possible to create a good conditions and opportunities.。