资源描述
长江大学工程技术学院毕业设计(论文) 外文翻译外文题目A technical note on the characterization of electroformed nickel shells for their application to injection molds 译文题目一个描述电铸镍壳在注塑模具的应用的技术研究系部机 械 系专业班级材控60901班学生姓名李小玲指导教师宋宏/高工辅导教师宋宏/高工完成时间2012年11月18日一个描述电铸镍壳在注塑模具的应用的技术研究 Universidad de Las Palmas de Gran Canaria, Departamento de Ingenieria Mecanica, Spain 摘要： 在过去几年中快速成型技术及快速模具已被广泛开发利用. 在本文中,使用电芯作为核心程序对塑料注射模具分析. 通过差分系统快速成型制造外壳模型. 主要目的是分析电铸镍壳力学特征、 研究相关金相组织,硬度,内部压力等不同方面，由这些特征参数以生产电铸设备的外壳. 最后一个核心是检验注塑模具. 关键词：电镀；电铸；微观结构；镍1. 引言 现代工业遇到很大的挑战，其中最重要的是怎么样提供更好的产品给消费者,更多种类和更新换代问题. 因此,现代工业必定产生更多的竞争性. 毫无疑问,结合时间变量和质量变量并不容易,因为他们经常彼此互为条件; 先进的生产系统将允许该组合以更加有效可行的方式进行，例如,如果是观测注塑系统的转变、 我们得出的结论是,事实上 一个新产品在市场上具有较好的质量它需要越来越少的时间 快速模具制造技术是在这一领域, 中可以改善设计和制造注入部分的技术进步. 快速模具制造技术基本上是一个中小型系列的收集程序，在很短的时间内在可接受的精度水平基础上让我们获得模具的塑料部件。其应用不仅在更加广阔而且生产也不断增多。 本文包括了很广泛的研究路线,在这些研究路线中我们可以尝试去学习，定义，分析，测试，提出在工业水平方面的可行性，从核心的注塑模具制造获取电铸镍壳，同时作为一个初始模型的原型在一个FDM设备上的快速成型。 不得不说的是,先进的电铸技术应用在无数的行业，但这一研究工作调查到什么程度,并根据这些参数,使用这种技术生产快速模具在技术上是可行的. 都产生一个准确的，系统化使用的方法以及建议的工作方法.2 制造过程的注塑模具薄镍外壳的核心是电铸,获得一个充满epoxic金属树脂的一体化的核心板块模具(图1)允许直接制造注射型多用标本，因为它们确定了新英格兰大学英文国际表卓华组织3167标准。这样做的目的是确定力学性能的材料收集代表行业。该阶段取得的核心4，根据这一方法研究了这项工作,有如下: a,用CAD系统设计的理想对象 b模型制造的快速成型设备(频分多路系统). 所用材料将是一个ABS塑料c一个制造的电铸镍壳，已事先涂有导电涂料(必须有导电).d无外壳模型 e核心的生产是背面外壳环氧树脂的抗高温与具有制冷的铜管管道.有两个腔的注塑模具、 其中一个是电核心和其他直接加工的移动版. 因此,在同一工艺条件下，同时注入两个标准技术制造，获得相同的工作。3 获得电壳:设备电镀是电解质时电流的化学变化,电解所形成的直流电有两个电极，阳极和阴极。当电流流经电路，在离子溶液中转化为原子。电镀液用于这项工作是由氨基磺酸镍400 毫升/升,氯化镍(10克/升)、硼酸(50克/升),allbrite SLA(30毫升/升),allbrite703(2毫升/升). 选择这种组合主要原因是我们考虑注塑模具程序是玻璃纤维. 氨基磺酸镍让我们获得可以接受的内部压力(测试不同工艺条件结果,而不是最佳工艺条件约2兆帕最高为50兆帕). 不过,这种内部压力是由touenesulfonamode衍生物和甲醛水溶液使用的ALLbrite添加剂的结果。这种添加剂也增加了壳的阻力. Allbrite703是一种可生物降解水溶液表使用剂 氯化镍,有利于解决金属统一分布在阴极，提高导电性的问题。硼酸作为PH值缓冲区。该设备用于制造壳的测试如下： 聚丙烯:600毫米400毫米500毫米的尺寸 三聚四氟乙烯电阻器,每一个有800W 具有机械搅拌系统的阴极循环和过滤系统用的泵和聚丙烯过滤器。 充电整流器. 最大强度在连续50个A和连续电流电压介于0至16伏 篮钛镍阳极(镍硫回合电解镍)纯度99%以上 气体注入系统一旦电流密度( 1-22A/dm）,温度(35至55)和pH值,已经确定，执行参数以及测试的进程部分不可改变。4 获得硬度电壳硬度的测试一直保持在相当高的很稳定的结果。如图2，可以看到：电流密度值2.5到22A/dm，硬度值介于540到580高压，PH值为4+-0.2和温度为45摄氏度，如果PH减少到3.5和温度为55摄氏度，硬度为520以上，高压低于560.这一测试使常规组成不同于其他氨基磺酸镍，允许其经营更加广泛，然而，这种operatyivity将是一定的取决于其他因素，如内部压力，因为他可能的变异。改变PH值，电流密度和温度等，另一方面，传统的硬度氨基磺酸镍承受的高压在200-250之间，远低于取得的一个实验结果的电压。对于一个注塑模具，硬度可以接受的起点300高压这是必须考虑的，注塑模具中最常见的材料，有改善钢（290高压），整体淬火（520-595高压），casehardened钢铁（760-8-高压）等，以这样一种方式，可以看到，注塑模具硬度水平的镍是壳内的高范围的材料。因为这是一个负责内部压力的塑料注射液，这种方式与环氧树脂灌浆将遵循它，相反对低韧性的壳补偿，这就是为什么它是必定尽可能的外壳厚度均匀，并没有重要的原因，如 腐蚀。5 金相组织为了分析金相结构、电流密度、温度主要变化. 在正面横向部分（垂直沉积）对样品进行了分析，为了方便地封装在树脂，抛光。铭刻，在不同阶段的混合乙酸和硝酸。该时刻间隔15,25,40,50之后再次抛光, 为了在金相显微镜下观察奥林巴斯PME3-ADL3.3X/10X 必须要说的是，这一条规定显示了图片之后的评论，用于制造该模型的壳在FDM快速成型机里融化的塑料材料（澳大利亚统计局）巩固和解决了该阶层。后来在每一个层，挤出的模具都留下一个大约0.15毫米直径横向和纵向的线程。因此，在表面可以看到细线表面头部的机器。这些西路将作为参考信息解决镍的重复性问题。重复性的模型将作为一个基本要素来评估注塑模具的表面纹理。表1测试系列：表1. 检验系列系列pH温度()电流密度A/mm214.20.2552.2223.90.2455.5634.00.24510.0044.00.24522.22图3说明该系列第一时刻表面的样本 它显示了流道起点的频率复用机，这就是说，又一个很好的重复性。它不能仍然要注意四舍五入结构。在图4 系列2，经过第二次，可以看到一条线的流道的方式与以前的相比不太清楚。在图5系列3虽然第二次时刻开始出现圆形晶结果是非常困难的。此外，最黑暗的部分表明时刻不足的进程和组成。这种现象表明，在低电流密度和高温条件下工作，得到更小的晶粒尺寸和壳重现性好，就是所需要的足够的应用程序。如果分析横向平面进行的沉积，可以在所有测试样品和条件增长的结构层（图6），牺牲一个低延展性取得令人满意的高机械阻力，最重要的是添加剂的使用情况，氨基磺酸镍液的添加剂通常创建一个纤维和非层状结果9.这个问题表明在任何情况下改变润湿剂，由于该层结构的决定因素是这种结构的应力减速器（ALLbriteSLA)。另一方面，她也是测试的层状结构不同厚度中的电流密度. 6 内部压力 壳的一个主要特点是应该有其应用，如插入时要有一个低水平的内部压力。测试不同的温度很电流密度，所采取的措施取决于阴极弯曲张力计法。A钢测试控制使用侧固定和其他自由度固定（160毫米长，12.7毫米宽，0.3毫米厚）。金属沉积只有在控制了机械拉伸力（拉深或压应力），才能计算内部压力。弹性的角度来看，斯托尼模型应用，假定镍基质厚度，对部分钢材产生足够小（3微米）的影响。在所有测试情况下，一个能够接受的应用程序在内部压力在50兆帕的极端条件下和2兆帕的最佳条件下产生。得出的结论是，内部压力在不同的工作条件和参数没有明显的变化条件下。7 校验注塑模具试验已进行了各种代表性热塑性材料如聚丙烯、高密度聚乙烯和PC、 并进行了注射部件性能的分析，如尺寸，重量，阻力，刚度和柔性。对壳的力学性能进行了拉伸破坏性测试和分析。大约500个注射液在其余的条件下，进行了更多的检验总体而言, 为分析一种材料，重要的是注意到行为标本中的核心和那些加工腔之间的差异。然而在分析光弹注入标本（图7）有人注意到不同的国家之间张力存在两种不同的类型的标本，是由于不同的模腔热传递和刚度。这种差异解释了柔性的变化更加突出的部分晶体材料，如聚乙烯和聚酰胺6. 有人注意到一个较低的柔性标本在的高密度聚乙烯分析测试管在镍核心的情况下，量化30%左右。如尼龙6这个值也接近50%。8 结论经过连续的测试，注塑模具在不同条件下检查的氨基磺酸镍液使用添加剂。这就是说塑性好，硬度好和摩擦力好的层状结构，已取得的力学性能是可以接受的。借鞋缺陷的镍壳将部分取代环氧树脂为核心的注塑模具，使注入的一系列中型塑料零部件达到可接受的质量的水平。外 文 出 处: http:/www.sciencedirect.com 参考资料1 A.E.W. Rennie, C.E. Bocking and G.R. Bennet, Electroforming of rapid prototyping mandrels for electro discharge machining electrodes, J. Mater. Process. Technol. 110 (2001), pp. 186196. 2 P.K.D.V. Yarlagadda, I.P. Ilyas and P. Chrstodoulou, Development of rapid tooling for sheet metal drawing using nickel electroforming and stereo lithography processes, J. Mater. Process. Technol. 111 (2001), pp. 286294. 3 J. Hart, A. Watson, Electroforming: A largely unrecognised but expanding vital industry, Interfinish 96, 14 World Congress, Birmingham, UK, 1996. 4 M. Monzn et al., Aplicacin del electroconformado en la fabricacin rpida de moldes de inyeccin, Revista de Plsticos Modernos. 84 (2002), p. 557. 5 L.F. Hamilton et al., Clculos de Qumica Analtica, McGraw Hill (1989). 6 E. Julve, Electrodeposicin de metales, 2000 (E.J.S.). 7 A. Watson, Nickel Sulphamate Solutions, Nickel Development Institute (1989). 8 A. Watson, Additions to Sulphamate Nickel Solutions, Nickel Development Institute (1989). 9 J. Dini, Electrodeposition Materials Science of Coating and Substrates, Noyes Publications (1993). 10 J.W. Judy, Magnetic microactuators with polysilicon flexures, Masters Report, Department of EECS, University of California, Berkeley, 1994. (cap. 3). A technical note on the characterization of electroformed nickel shells for their application to injection molds aUniversidad de Las Palmas de Gran Canaria, Departamento de Ingenieria Mecanica, Spain AbstractThe techniques of rapid prototyping and rapid tooling have been widely developed during the last years. In this article, electroforming as a procedure to make cores for plastics injection molds is analysed. Shells are obtained from models manufactured through rapid prototyping using the FDM system. The main objective is to analyze the mechanical features of electroformed nickel shells, studying different aspects related to their metallographic structure, hardness, internal stresses and possible failures, by relating these features to the parameters of production of the shells with an electroforming equipment. Finally a core was tested in an injection mold. Keywords: Electroplating; Electroforming; Microstructure; Nickel 1. IntroductionOne of the most important challenges with which modern industry comes across is to offer the consumer better products with outstanding variety and time variability (new designs). For this reason, modern industry must be more and more competitive and it has to produce with acceptable costs. There is no doubt that combining the time variable and the quality variable is not easy because they frequently condition one another; the technological advances in the productive systems are going to permit that combination to be more efficient and feasible in a way that, for example, if it is observed the evolution of the systems and techniques of plastics injection, we arrive at the conclusion that, in fact, it takes less and less time to put a new product on the market and with higher levels of quality. The manufacturing technology of rapid tooling is, in this field, one of those technological advances that makes possible the improvements in the processes of designing and manufacturing injected parts. Rapid tooling techniques are basically composed of a collection of procedures that are going to allow us to obtain a mold of plastic parts, in small or medium series, in a short period of time and with acceptable accuracy levels. Their application is not only included in the field of making plastic injected pieces 1, 2 and 3, however, it is true that it is where they have developed more and where they find the highest output. This paper is included within a wider research line where it attempts to study, define, analyze, test and propose, at an industrial level, the possibility of creating cores for injection molds starting from obtaining electroformed nickel shells, taking as an initial model a prototype made in a FDM rapid prototyping equipment. It also would have to say beforehand that the electroforming technique is not something new because its applications in the industry are countless 3, but this research work has tried to investigate to what extent and under which parameters the use of this technique in the production of rapid molds is technically feasible. All made in an accurate and systematized way of use and proposing a working method. 2. Manufacturing process of an injection moldThe core is formed by a thin nickel shell that is obtained through the electroforming process, and that is filled with an epoxic resin with metallic charge during the integration in the core plate 4 This mold (Fig. 1) permits the direct manufacturing by injection of a type a multiple use specimen, as they are defined by the UNE-EN ISO 3167 standard. The purpose of this specimen is to determine the mechanical properties of a collection of materials representative industry, injected in these tools and its coMParison with the properties obtained by conventional tools. Fig. 1.Manufactured injection mold with electroformed core.The stages to obtain a core 4, according to the methodology researched in this work, are the following: (a) Design in CAD system of the desired object.(b) Model manufacturing in a rapid prototyping equipment (FDM system). The material used will be an ABS plastic.(c) Manufacturing of a nickel electroformed shell starting from the previous model that has been coated with a conductive paint beforehand (it must have electrical conductivity).(d) Removal of the shell from the model.(e) Production of the core by filling the back of the shell with epoxy resin resistant to high temperatures and with the refrigerating ducts made with copper tubes.The injection mold had two cavities, one of them was the electroformed core and the other was directly machined in the moving platen. Thus, it was obtained, with the same tool and in the same process conditions, to inject simultaneously two specimens in cavities manufactured with different technologies. 3. Obtaining an electroformed shell: the equipmentElectrodeposition 5 and 6 is an electrochemical process in which a chemical change has its origin within an electrolyte when passing an electric current through it. The electrolytic bath is formed by metal salts with two submerged electrodes, an anode (nickel) and a cathode (model), through which it is made to pass an intensity coming from a DC current. When the current flows through the circuit, the metal ions present in the solution are transformed into atoms that are settled on the cathode creating a more or less uniform deposit layer. The plating bath used in this work is formed by nickel sulfamate 7 and 8 at a concentration of 400ml/l, nickel chloride (10g/l), boric acid (50g/l), Allbrite SLA (30cc/l) and Allbrite 703 (2cc/l). The selection of this composition is mainly due to the type of application we intend, that is to say, injection molds, even when the injection is made with fibreglass. Nickel sulfamate allows us to obtain an acceptable level of internal stresses in the shell (the tests gave results, for different process conditions, not superior to 50MPa and for optimum conditions around 2MPa). Nevertheless, such level of internal pressure is also a consequence of using as an additive Allbrite SLA, which is a stress reducer constituted by derivatives of toluenesulfonamide and by formaldehyde in aqueous solution. Such additive also favours the increase of the resistance of the shell when permitting a smaller grain. Allbrite 703 is an aqueous solution of biodegradable surface-acting agents that has been utilized to reduce the risk of pitting. Nickel chloride, in spite of being harmful for the internal stresses, is added to enhance the conductivity of the solution and to favour the uniformity in the metallic distribution in the cathode. The boric acid acts as a pH buffer. The equipment used to manufacture the nickel shells tested has been as follows: Polypropylene tank: 600mm400mm500mm in size. Three teflon resistors, each one with 800W. Mechanical stirring system of the cathode. System for recirculation and filtration of the bath formed by a pump and a polypropylene filter. Charging rectifier. Maximum intensity in continuous 50A and continuous current voltage between 0 and 16V. Titanium basket with nickel anodes (Inco S-Rounds Electrolytic Nickel) with a purity of 99%. Gases aspiration system.Once the bath has been defined, the operative parameters that have been altered for testing different conditions of the process have been the current density (between 1 and 22A/dm2), the temperature (between 35 and 55C) and the pH, partially modifying the bath composition. 4. Obtained hardnessOne of the most interesting conclusions obtained during the tests has been that the level of hardness of the different electroformed shells has remained at rather high and stable values. In Fig. 2, it can be observed the way in which for current density values between 2.5 and 22A/dm2, the hardness values range from 540 and 580HV, at pH 40.2 and with a temperature of 45C. If the pH of the bath is reduced at 3.5 and the temperature is 55C those values are above 520HV and below 560HV. This feature makes the tested bath different from other conventional ones composed by nickel sulfamate, allowing to operate with a wider range of values; nevertheless, such operativity will be limited depending on other factors, such as internal stress because its variability may condition the work at certain values of pH, current density or temperature. On the other hand, the hardness of a conventional sulfamate bath is between 200250HV, much lower than the one obtained in the tests. It is necessary to take into account that, for an injection mold, the hardness is acceptable starting from 300HV. Among the most usual materials for injection molds it is possible to find steel for improvement (290HV), steel for integral hardening (520595HV), casehardened steel (760800HV), etc., in such a way that it can be observed that the hardness levels of the nickel shells would be within the mediumhigh range of the materials for injection molds. The objection to the low ductility of the shell is compensated in such a way with the epoxy resin filling that would follow it because this is the one responsible for holding inwardly the pressure charges of the processes of plastics injection; this is the reason why it is necessary for the shell to have a thickness as homogeneous as possible (above a minimum value) and with absence of important failures such as pitting. Fig. 2.Hardness variation with current density. pH 40.2, T=45C.5. Metallographic structureIn order to analyze the metallographic structure, the values of current density and temperature were mainly modified. The samples were analyzed in frontal section and in transversal section (perpendicular to the deposition). For achieving a convenient preparation, they were conveniently encapsulated in resin, polished and etched in different stages with a mixture of acetic acid and nitric acid. The etches are carried out at intervals of 15, 25, 40 and 50s, after being polished again, in order to be observed afterwards in a metallographic microscope Olympus PME3-ADL 3.3/10. Before going on to comment the photographs shown in this article, it is necessary to say that the models used to manufacture the shells were made in a FDM rapid prototyping machine where the molten plastic material (ABS), that later solidifies, is settled layer by layer. In each layer, the extruder die leaves a thread approximately 0.15mm in diameter which is compacted horizontal and vertically with the thread settled inmediately after. Thus, in the surface it can be observed thin lines that indicate the roads followed by the head of the machine. These lines are going to act as a reference to indicate the reproducibility level of the nickel settled. The reproducibility of the model is going to be a fundamental element to evaluate a basic aspect of injection molds: the surface texture. The tested series are indicated in Table 1. Table 1. Tested series Series pH Temperature (C) Current density (A/dm2) 14.20.2552.2223.90.2455.5634.00.24510.0044.00.24522.22Fig. 3 illustrates the surface of a sample of the series after the first etch. It shows the roads originated by the FDM machine, that is to say that there is a good reproducibility. It cannot be still noticed the rounded grain structure. In Fig. 4, series 2, after a second etch, it can be observed a line of the road in a way less clear than in the previous case. In Fig. 5, series 3 and 2 etch it begins to appear the rounded grain structure although it is very difficult to check the roads at this time. Besides, the most darkened areas indicate the presence of pitting by inadequate conditions of process and bath composition. Fig. 3.Series 1 (150), etch 1.Fig. 4.Series 2 (300), etch 2.Fig. 5.Series 3 (300), etch 2.This behavior indicates that, working at a low current density and a high t matter demonstrated that the determinant for such structure was the stress reducer (Allbrite SLA). On the other hand, it was also tested that the laminar structure varies according to the thickness of the layer in terms of the current density. Fig. 6.Plane transversal of series 2 (600), etch 2.6. Internal stressesOne of the main characteristic that a shell should have for its application like an insert is to have a low level of internal stresses. Different tests at different bath temperatures and current densities were done and a measure system rested on cathode flexural tensiometer method was used. A steel testing control was used with a side fixed and the other free
展开阅读全文