Corrosion behaviour of aluminium in fresh waters with special reference to pipelines

Abstract

This review is largely concerned with work carried out on the long-term behaviour of aluminium in fresh waters and the methods developed for predicting service behaviour. The corrosion behaviour of aluminium in waters is discussed and it is shown that aluminium corrodes by pitting. The effect of pitting on tensile properties, on the bursting strength of pipes, and on the hydraulic efficiency of pipes is described. It is shown that the most important consideration is that of preventing of perforation by pitting. The mechanism of pit initiation and pit growth and its practical Implications are described. The methods used by these Laboratories for determining the corrosivities of waters are given. The alloys in general use.in fresh waters are given together with their chemical compositions. The types of all aplicationS are briefly mentioned, and a specific application, that of water pipelines, is then dealt With in detail. Finally, the methods usedfor preventing perforation are summarised.     

基于参考模型的制造业MES需求建模

本文结合ERP等软件的企业参考模型与在航天企业MES项目实施的经验,提出一种面向航天企业的参考模型。介绍了基于参考模型的需求建模方法及实现过程,最后通过实例来验证该思路的正确性和有效性。实践证明,基于参考模型的需求建模方法进行需求分析能够大大节约时间成本,提高软件设计思想与车间需求的符合度。     

手柄落料、冲孔级进模设计及制造

分析了手柄冲压成形的工艺特点,设计了一副落料、冲孔级进模;介绍了该模具的结构特点、设计思路以及装配和制造中应注意的问题。     

COMMERCIAL METHODS OF STRIPPING (with special reference to Chromium,Nickel and Copper)

The rate of penetration of organic bright nickel deposits in the B.N.F. jet-test is shown to vary with the thickness of the deposit. Therefore, to determine thickness by this method it is necessary to use a calibration curve relating apparent and true thickness. Although minor variations in plating conditions have little effect, separate calibration curves are required for deposits from different proprietary solutions and there is some evidence that differences can arise between individual baths of nominally the same type. Unless the calibration can be checked on deposits from a given bath, it is therefore recommended that the jet test on organic bright nickel deposits be used primarily as an acceptance test of the “limit” type.     

可换镶件式隔圈模具设计与制造

针对超薄塑料材料的手机镜头隔圈类零件复合冲形模具的结构进行了设计。为了较大地缩短类似零件模具的制造周期，模具结构采用了可换镶件式结构形式。为了提高模具的产能，模具的模腔数量设计为一模三腔。介绍了该模具的结构特点、工作过程和制造工艺，模具试生产验证该结构合理，生产效率高，有很好的技术经济效益。     

Design and manufacturing of high-performance prostheses with additive manufacturing and fiber-reinforced polymers

This paper presents an approach combining additive manufacturing (AM) with carbon fiber reinforced polymers (CFRP) in an autoclave prepreg process for the development of complex-shaped hybrid AM-CFRP structures with the potential for individualization. The goal of this paper is to investigate the processing route in the context of low volume industrial applications and to assess the mechanical performance of hybrid AM-CFRP structures in ultimate strength and fatigue. The approach was applied to lower-limb prostheses using dissolvable in-autoclave tooling made of ST-130 by fused deposition modeling, two load introduction elements made of titanium by selective laser melting, and pre-impregnated carbon fiber reinforcements. The parts were cured in an autoclave at a pressure of 3 bar and a temperature of 110 °C. The inner toolings were dissolved in a basic solution after curing. The prostheses were subjected to ultimate strength and fatigue tests to assess the mechanical performance of the structures. Results show that the target load of 5474 N was exceeded by 40% and that no fatigue failure occurred for the given loading. Weight savings of 28% compared to a state-of-the-art aluminum reference part were achieved. Results demonstrate that the combination of technologies could be appropriate for high-performance lightweight components with complex geometries.     

托架悬挂立式安装复合冲模结构的设计和制造

托架为铝合金零件,其形状如"n"字形登陆艇。加工时需要切除在弯曲成形后的两侧面,呈"n"字船形部分多余的料边和2×φ4.1mm孔中的废料。采用铣削加工的方法,具有加工的工序多、效率低、废品率高和孔位不对称的特点。采用了冲裁托架的全部外形和孔,再进行弯曲成形的加工方法。加工出来的托架外形和孔位很难做到对称性,易发生错位的现象。经过多次试验,采用了托架悬挂立式安装,再分别单边进行复合冲切加工工艺的方法。结果表明,获得了符合零件图纸要求的托架,且冲裁加工出的托架外形和孔位具有高效与对称性。     

数控加工中心四轴专用平口钳的设计研究

针对数控加工中心四轴上多采用普通平口钳进行安装和调试,安装、调试繁琐,应用范围小的问题,设计了一种数控加工中心四轴专用平口钳,内部螺杆采用反向螺纹设计,具有自动对中功能;外观形状参照四轴设计,占用空间小,特别适用于电极、复杂零件及小型模具零件的加工。     

Modeling of manufacturing processes with ANNs for intelligent manufacturing

Modern manufacturing often caters to rapidly changing product specifications determined by the continuously increasing productivity, flexibility and quality demands. Metal forming and machining are two important manufacturing processes in present day manufacturing. Automatic selection of tools and accessories in these processes heavily relies on forming force/cutting force estimation. Complex relationships exist between process parameters and these forces. In the present work, the applicability and relative effectiveness of Artificial Neural Network based models has been investigated for rapid estimation of these, invoking the function approximation capabilities of the ANN models. The results obtained are found to correlate well with the finite element simulation data in cases of metal forming, and experimental data in cases of metal cutting. This work has considerable implications in selection of the tools and on-line monitoring of tool wear. The actual forming and cutting forces can be compared with predicted ones to signal the onset of tool wear, and thus prevent damage to the tool and work piece during the course of manufacturing.     

接地板级进模设计与制造

介绍了接地板多工位级进模的结构特点和设计要点,分析了模具设计中的技术问题,得出了排样设计和解决内凹弯曲件的卸料问题的方法,对同类零件的模具设计有一定的借鉴作用.     

Design for additive manufacturing: Framework and methodology

In recent decades additive manufacturing (AM) has evolved from a prototyping to a production technology. It is used to produce end-use-parts for medical, aerospace, automotive and other industrial applications from small series up to 100,000 of commercially successful products. Metal additive manufacturing processes are relatively slow, require complex preparation and post-processing treatment while using expensive machinery, resulting in high production costs per product. Design for Additive Manufacturing (DfAM) aims at optimizing the product design to deal with the complexity of the production processes, while also defining decisive benefits of the AM based product in the usage stages of its life cycle. Recent investigations have shown that the lack of knowledge on DfAM tools and techniques are seen as one of the barriers for the further implementation of AM. This paper presents a framework for DfAM methods and tools, subdivided into three distinct stages of product development: AM process selection, product redesign for functionality enhancement, and product optimization for the AM process chosen. It will illustrate the applicability of the design framework using examples from both research and industry.     

金属弹片级进模设计

根据金属弹片的结构特点和生产要求,分析了金属弹片的冲压成形工艺,制定了适合金属弹片生产的冲压工艺方案并设计了级进模,经实际生产验证,金属弹片成形工艺方案及级进模是有效而可靠的,对类似零件的生产具有一定的参考作用。     

弹性接触件弯曲模设计

分析了弹性接触件结构特点和工艺性,介绍此类零件弯曲成形时模具设计的最优结构。用一副复合模具完成工件定位、预弯、弯曲成形。提高了生产效率,降低了模具成本、便于制造,维修方便。     

单摆杆级进模的设计与制造

为解决弯曲尺寸精度控制困难的问题,在模具的不同工位,综合采用了弯曲区刻槽、弯曲区材料局部减薄使其塑性变形适当加大、按预先估算的回弹量补偿回弹、调整弯曲凸模高度等控制弯曲回弹的工艺措施.利用几处微调装置,能有效地控制弯曲角度.成形的工件表面光滑、形状精确,尺寸精度达到±0.2mm,角度精度达到±30′.在几个工位上采用多种可调的减少弯曲回弹的措施,能有效地控制弯曲精度.     

Design and management of manufacturing systems for production quality

Manufacturing companies are continuously facing the challenge of operating their manufacturing processes and systems in order to deliver the required production rates of high quality products, while minimizing the use of resources. Production quality is proposed in this paper as a new paradigm aiming at going beyond traditional six-sigma approaches. This new paradigm is extremely relevant in technology intensive and emerging strategic manufacturing sectors, such as aeronautics, automotive, energy, medical technology, micro-manufacturing, electronics and mechatronics. Traditional six-sigma techniques show strong limitations in highly changeable production contexts, characterized by small batch productions, customized, or even one-of-a-kind products, and in-line product inspections. Innovative and integrated quality, production logistics and maintenance design, management and control methods as well as advanced technological enablers have a key role to achieve the overall production quality goal. This paper revises problems, methods and tools to support this paradigm and highlights the main challenges and opportunities for manufacturing industries in this context.     

Microstructure and mechanical properties of friction stir welded aluminium alloys with special reference to AA 5083 and AA 6082

Abstract

Aluminium alloys AA 5083 and AA 6082 have been friction stir welded and the mechanical properties and microstructures of the welds have been evaluated. Alloy AA 5083 mainly fractured near the centre of the weld, while fracture in AA 6082 mainly occurred in the heat affected zone. The tensile strength of welded joints in AA 6082 was lower than the base material strength, but still met classification societies' requirements. Hardness was approximately constant across the welded zone in AA 5083, while a minimum in hardness was found in the AA 6082 welds. The location of the fracture closely matched the minimum hardness region. Very fine scale precipitation in AA 6082 was significantly affected by the weld thermal cycle. In the zone of lowest hardness, the hardening precipitate (β″-Mg₅Si₆) had transformed to the non-hardening β′-Mg_1.7Si. This is probably the main reason for the minimum in hardness, the fracture location, and the decreased tensile strength. Results are compared to a similar investigation of aluminium alloy AA 7075.     

异形条钢矫直机的设计

针对高层建筑用塔式起重机采用的焊接杆件弯曲变形问题,提出了采用多辊矫直方案,方案从材料截面计算入手,进行了矫直机能力设计计算,得出了辊系的轴径、辊径和机器的矫直力、矫直力矩、传动功率参数值.通过生产验证该计算过程可以作为同类机床设计计算的参考.     

基于PLC变频调速一体的车轮专用焊机的设计

介绍了一种由PLC和变频器组成的专用焊机自动控制系统，对系统的硬件和软件设计作了较为详细的阐述。     

弯销和特殊斜销抽芯压铸模设计

铸件带有深腔,开模时铸件容易包紧在定模型芯上,并最终留在定模,给取件带来困难,模具设计时采用了具有延时作用的特殊斜销,消除了铸件对定模型芯的包紧力,从而使铸件留在动模。模具使用情况良好,所生产的零件能满足精度和表面粗糙度的要求。     

Similarities in the corrosion behaviour of iron, cobalt and nickel in acid solutions. A review with special reference to the sulphide adsorption

Corrosion kinetics of the iron group metals are strongly influenced by adsorption phenomena. Literature data and experimental results show sulphide adsorption to be a predominant factor in determining the corrosion rates of these metals and some of their alloys. Stabilizing sulphide inclusions against acid attack and reductions in the free sulphide concentration at the metal/electrolyte interface through appropriate alloying suppresses both general and localized corrosion.