注塑模具电铸镍壳毕业论文中英文对照资料外文翻译文献

外文资料翻译

系部：机械工程系

专业: 材料成型及控制工程

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/mm2

1 4.

2 ± 0.2 55 2.22

2 3.9 ± 0.2 45 5.56

3 4.0 ± 0.2 45 10.00

4 4.0 ± 0.2 4

5 22.22

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。

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. 186–196. [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. 286–294.

[3] J. Hart, A. Watson, Electroforming: A largely unrecognised but expanding vital industry, Interfinish 96, 14 World Congress, Birmingham, UK, 1996.

[4] M. Monzón et al., Aplicación del electroconformado en la fabricación rápida de moldes de inyección, Revista de Plásticos Modernos.84(2002), p. 557.

[5] L.F. Hamilton et al., Cálculos de Química Analítica, McGraw Hill (1989).

[6] E. Julve, Electrodeposición 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

——a Universidad de Las Palmas de Gran Canaria, Departamento de Ingenieria Mecanica, Spain

Abstract

The 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. Introduction

One 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 mold

The 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 equipment

Electrodeposition [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 400 ml/l, nickel chloride (10 g/l), boric acid (50 g/l), Allbrite SLA (30 cc/l) and Allbrite 703 (2 cc/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 50 MPa and for optimum conditions around 2 MPa). 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: 600 mm × 400 mm × 500 mm in size.

? Three teflon resistors, each one with 800 W.

? Mechanical stirring system of the cathode.

? System for recirculation and filtration of t he bath formed by a pump and a polypropylene filter.

? Charging rectifier. Maximum intensity in continuous 50 A and continuous current voltage between 0 and 16 V.

? 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 22 A/dm2), the temperature (between 35 and 55 °C) and the pH, partially modifying the bath composition.

4. Obtained hardness

One 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 22 A/dm2, the hardness values range from 540 and 580 HV, at pH 4 ± 0.2 and with a temperature of 45 °C. If the pH of the bath is reduced at 3.5 and the temperature is 55 °C those values are above 520 HV and below 560 HV. 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 200–250 HV, 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 300 HV. Among the most usual materials for injection molds it is possible to find steel for improvement (290 HV), steel for integral hardening (520–595 HV), casehardened steel

(760–800 HV), etc., in such a way that it can be observed that the hardness levels of the nickel shells would be within the medium–high 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 4 ± 0.2, T = 45 °C.

5. Metallographic structure

In 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 50 s, 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 0.15 mm 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)

1 4.

2 ± 0.255 2.22

2 3.9 ± 0.245 5.56

3 4.0 ± 0.24510.00

4 4.0 ± 0.24522.22

Fig. 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 temperature, shells with a good reproducibility of the model and with a small grain size are obtained, that is, adequate for the required application.

If the analysis is carried out in a plane transversal to the deposition, it can be tested in all the samples and for all the conditions that the growth structure of the deposit is laminar (Fig. 6), what is very satisfactory to obtain a high mechanical resistance although at the

expense of a low ductibility. This quality is due, above all, to the presence of the additives used because a nickel sulfamate bath without additives normally creates a fibrous and non-laminar structure [9]. The modification until a nearly null value of the wetting agent gave as a result that the laminar structure was maintained in any case, that 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 stresses

One 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 (160 mm length, 12.7 mm width and thickness 0.3 mm). Because the metallic deposition is only in one side the testing control has a mechanical strain (tensile or compressive stress) that allows to calculate the internal stresses. Stoney model [10] was applied and was supposed that nickel substratum thickness is enough small (3 μm) to influence, in an elastic point of view, to the strained steel part. In all the tested cases the most value of internal stress was under 50 MPa for extreme conditions and 2 MPa for optimal conditions, an acceptable value for the required application. The conclusion is that the electrolitic bath allows to work at different conditions and parameters without a significant variation of internal stresses.

7. Test of the injection mold

Tests have been carried out with various representative thermoplastic materials such as PP, PA, HDPE and PC, and it has been analysed the properties of the injected parts such as dimensions, weight, resistance, rigidity and ductility. Mechanical properties were tested by tensile destructive tests and analysis by photoelasticity. About 500 injections were carried out on this core, remaining under conditions of withstanding many more.

In general terms, important differences were not noticed between the behavior of the specimens obtained in the core and the ones from the machined cavity, for the set of the analysed materials. However in the analysis by photoelasticiy (Fig. 7) it was noticed a different tensional state between both types of specimens, basically due to differences in the heat transference and rigidity of the respective mold cavities. This difference explains the ductility variations more outstanding in the partially crystalline materials such as HDPE and PA 6.

Fig. 7. Analysis by photoelasticity of injected specimens.

For the case of HDPE in all the analysed tested tubes it was noticed a lower ductility in the specimens obtained in the nickel core, quantified about 30%. In the case of PA 6 this value was around 50%.

8. Conclusions

After consecutive tests and in different conditions it has been checked that the nickel sulfamate bath, with the utilized additives has allowed to obtain nickel shells with some mechanical properties acceptable for the required application, injection molds, that is to say, good reproducibility, high level of hardness and good mechanical resistance in terms of the resultant laminar structure. The mechanical deficiencies of the nickel shell will be partially replaced by the epoxy resin that finishes shaping the core for the injection mold, allowing to inject medium series of plastic parts with acceptable quality levels.

References

[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. 186–196. [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. 286–294.

[3] J. Hart, A. Watson, Electroforming: A largely unrecognised but expanding vital industry, Interfinish 96, 14 World Congress, Birmingham, UK, 1996.

[4] M. Monzón et al., Aplicación del electroconformado en la fabricación rápida de moldes de inyección, Revista de P lásticos Modernos.84(2002), p. 557.

[5] L.F. Hamilton et al., Cálculos de Química Analítica, McGraw Hill (1989).

[6] E. Julve, Electrodeposición 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).

模具毕业设计外文翻译(英文+译文)

Injection Molding The basic concept of injection molding revolves around the ability of a thermoplastic material to be softened by heat and to harden when cooled .In most operations ,granular material (the plastic resin) is fed into one end of the cylinder (usually through a feeding device known as a hopper ),heated, and softened(plasticized or plasticized),forced out the other end of the cylinder, while it is still in the form of a melt, through a nozzle into a relatively cool mold held closed under pressure.Here,the melt cools and hardens until fully set-up. The mold is then opened, the piece ejected, and the sequence repeated. Thus, the significant elements of an injection molding machine become: 1) the way in which the melt is plasticized (softened) and forced into the mold (called the injection unit); 2) the system for opening the mold and closing it under pressure (called the clamping unit);3) the type of mold used;4) the machine controls. The part of an injection-molding machine, which converts a plastic material from a sold phase to homogeneous seni-liguid phase by raising its temperature .This unit maintains the material at a present temperature and force it through the injection unit nozzle into a mold .The plunger is a combination of the injection and plasticizing device in which a heating chamber is mounted between the plunger and mold. This chamber heats the plastic material by conduction .The plunger, on each stroke; pushes unbelted plastic material into the chamber, which in turn forces plastic melt at the front of the chamber out through the nozzle The part of an injection molding machine in which the mold is mounted, and which provides the motion and force to open and close the mold and to hold the mold close with force during injection .This unit can also provide other features necessary for the effective functioning of the molding operation .Moving

毕业论文中参考文献的格式规范

毕业论文中参考文献的格式规范 一 .参考文献（即引文出处）的类型以单字母方式标识： 参考文献类型文献类型标示 专著Ｍ 论文集Ｃ 报纸文章Ｎ 期刊文章Ｊ 学位论文Ｄ 汇报Ｒ 规范Ｓ 专利Ｐ 电子参考文献类型标识 数据库ＤＢ 计算机程序ＣＰ 电子公告ＥＢ 二.① 主要责任者(专著作者、论文集主编、学位申报人、专利申请人、汇报撰写人、期刊文章作者、析出文章作者)。多个责任者之间以“，”分隔，注意在本项数据中不得出现缩写点“.”（英文作者请将作者名写全）。主要责任者只列姓名，其后不加“著”、“ 编”、“主编”、“合编”等责任说明。②. 文献习题名及版本1 / 3

(初版省略)。③ 文献类型 及载体类型标识。④ 出版项(出版地、出版者、出版年)。⑤ 文 献出处或电子文献的可 获得地址。⑥ 文献起止页码。⑦ 文献规范编号(规范号、专利号……)。 三.电子文献的载体类型及其标识 对于非纸张型载体的电子文献，当被引用为参考文献时需在参考 文献类型标识中同时标 明其载体类型。本标准建议采用双字母表示电子文献载体类型：磁带(magnetic tape)— —ＭＴ，磁盘(disk)——ＤＫ，光盘(ＣＤ-ＲＯＭ)——ＣＤ， 联机网络(online)——ＯＬ，并以下列 格式表示包括了文献载体类型的参考文献类型标识： ［文献类型标识/载体类型标识］ 如：［ＤＢ/ＯＬ］——联机网上数据库(database online) ［ＤＢ/ＭＴ］——磁带数据库(database on magnetic tape) ［Ｍ/ＣＤ］——光盘图书(monograph on ＣＤ-ＲＯＭ) ［ＣＰ/ＤＫ］——磁盘软件(computer program on disk) ［Ｊ/ＯＬ］——网上期刊(serial online) ［ＥＢ/ＯＬ］——网上电子公告(electronic bulletin board online) 2 / 3

概率论毕业论文外文翻译

Statistical hypothesis testing Adriana Albu，Loredana Ungureanu Politehnica University Timisoara,adrianaa@aut.utt.ro Politehnica University Timisoara,loredanau@aut.utt.ro Abstract In this article,we present a Bayesian statistical hypothesis testing inspection, testing theory and the process Mentioned hypothesis testing in the real world and the importance of, and successful test of the Notes. Key words Bayesian hypothesis testing; Bayesian inference;Test of significance Introduction A statistical hypothesis test is a method of making decisions using data, whether from a controlled experiment or an observational study (not controlled). In statistics, a result is called statistically significant if it is unlikely to have occurred by chance alone, according to a pre-determined threshold probability, the significance level. The phrase "test of significance" was coined by Ronald Fisher: "Critical tests of this kind may be called tests of significance, and when such tests are available we may discover whether a second sample is or is not significantly different from the first."[1] Hypothesis testing is sometimes called confirmatory data analysis, in contrast to exploratory data analysis. In frequency probability,these decisions are almost always made using null-hypothesis tests. These are tests that answer the question Assuming that the null hypothesis is true, what is the probability of observing a value for the test statistic that is at [] least as extreme as the value that was actually observed?) 2 More formally, they represent answers to the question, posed before undertaking an experiment,of what outcomes of the experiment would lead to rejection of the null hypothesis for a pre-specified probability of an incorrect rejection. One use of hypothesis testing is deciding whether experimental results contain enough information to cast doubt on conventional wisdom. Statistical hypothesis testing is a key technique of frequentist statistical inference. The Bayesian approach to hypothesis testing is to base rejection of the hypothesis on the posterior probability.[3][4]Other approaches to reaching a decision based on data are available via decision theory and optimal decisions. The critical region of a hypothesis test is the set of all outcomes which cause the null hypothesis to be rejected in favor of the alternative hypothesis. The critical region is usually denoted by the letter C. One-sample tests are appropriate when a sample is being compared to the population from a hypothesis. The population characteristics are known from theory or are calculated from the population.

毕业论文之参考文献

毕业论文之参考文献 参考文献 [2] [美]罗伯特"吉尔平：《国际关系政治经济学》，杨宇光等译，经济科学出版社，版。 [5] [美]罗伯特"吉尔平：《全球政治经济学》（杨宇光等译），上海人民出版社，2021年版。 [6] [美]约瑟夫"奈：《硬权力与软权力》，门洪华译，北京大学出版社，2021年 10月第1版，第177、183、190页。 [7] [美]托克维尔：《论美国的民主》，商务印书馆，董果良译，2002年版，第 210页。 [8] [美]肯尼斯"沃尔兹：《国际政治理论》，信强译，上海世纪出版集团，2021年11月第1版，第37、45、54页。 [20] 丁松泉：《中国崛起与中美关系》，中国社会科学出版社，2021年5月第1版。 [22] W.Arthur Lenis,The Evolution of the International Economic Order ,Princeton: Princeton University Press,1978. [23] Henry Kissinger,America at the Apex. The national interest, Summer ,2001, p15. [26] Raymond Vernon, Sovereignty at Bay: The Multinational Spread of U.S. Enterprises, New York & London: Basic Books, Inc Publishers,1971. [27] Robert Gilpin, U.S. Power and the Multinational Corporation: The Political Economy of Foreign Direct Investment, New York: Basic Books,Inc.,Publishers,1975. 感谢您的阅读，祝您生活愉快。

毕业论文外文翻译模版

吉林化工学院理学院 毕业论文外文翻译English Title（Times New Roman ，三号） 学生学号：08810219 学生姓名：袁庚文 专业班级：信息与计算科学0802 指导教师：赵瑛 职称副教授 起止日期：2012.2.27～2012.3.14 吉林化工学院 Jilin Institute of Chemical Technology

1 外文翻译的基本内容 应选择与本课题密切相关的外文文献（学术期刊网上的），译成中文，与原文装订在一起并独立成册。在毕业答辩前，同论文一起上交。译文字数不应少于3000个汉字。 2 书写规范 2.1 外文翻译的正文格式 正文版心设置为：上边距：3.5厘米，下边距：2.5厘米，左边距：3.5厘米，右边距：2厘米，页眉：2.5厘米，页脚：2厘米。 中文部分正文选用模板中的样式所定义的“正文”，每段落首行缩进2字；或者手动设置成每段落首行缩进2字，字体：宋体，字号：小四，行距：多倍行距1.3，间距：前段、后段均为0行。 这部分工作模板中已经自动设置为缺省值。 2.2标题格式 特别注意：各级标题的具体形式可参照外文原文确定。 1．第一级标题（如：第1章绪论）选用模板中的样式所定义的“标题1”，居左；或者手动设置成字体：黑体，居左，字号：三号，1.5倍行距，段后11磅，段前为11磅。 2．第二级标题（如：1.2 摘要与关键词）选用模板中的样式所定义的“标题2”，居左；或者手动设置成字体：黑体，居左，字号：四号，1.5倍行距，段后为0，段前0.5行。 3．第三级标题（如：1.2.1 摘要）选用模板中的样式所定义的“标题3”，居左；或者手动设置成字体：黑体，居左，字号：小四，1.5倍行距，段后为0，段前0.5行。 标题和后面文字之间空一格（半角）。 3 图表及公式等的格式说明 图表、公式、参考文献等的格式详见《吉林化工学院本科学生毕业设计说明书（论文）撰写规范及标准模版》中相关的说明。

塑料注塑模具中英文对照外文翻译文献

外文翻译及原文 (文档含英文原文和中文翻译) 【原文一】 CONCURRENT DESIGN OF PLASTICS INJECTION MOULDS Abstract The plastic product manufacturing industry has been growing rapidly in recent years. One of the most popular processes for making plastic parts is injection moulding. The design of injection mould is critically important to product quality and efficient product processing. Mould-making companies, who wish to maintain the competitive edge, desire to shorten both design and manufacturing leading times of the by applying a systematic mould design process. The mould industry is an important support industry during the product development process, serving as an important link between the product designer and manufacturer. Product development has changed from the traditional serial process of design, followed by manufacture, to a more organized concurrent process where design and manufacture are considered at a very early stage of design. The concept of concurrent engineering (CE) is no longer new and yet it is still applicable and relevant in today’s manuf acturing environment. Team working spirit, management involvement, total design process and integration of IT tools are still the essence of CE. The application of The CE process to the design of an injection process involves the simultaneous consideration of plastic part design, mould design and injection moulding machine selection, production scheduling and cost as early as possible in the design stage.

模具毕业设计外文翻译7081204

(此文档为word格式，下载后您可任意编辑修改！) 冷冲模具使用寿命的影响及对策 冲压模具概述 冲压模具--在冷冲压加工中，将材料(金属或非金属)加工成零件(或半成品)的一种特殊工艺装备，称为冷冲压模具(俗称冷冲模)。冲压--是在室温下，利用安装在压力机上的模具对材料施加压力，使其产生分离或塑性变形，从而获得所需零件的一种压力加工方法。 冲压模具的形式很多，一般可按以下几个主要特征分类： 1?根据工艺性质分类 (1)冲裁模沿封闭或敞开的轮廓线使材料产生分离的模具。如落料模、冲孔模、切断模、切口模、切边模、剖切模等。 (2)弯曲模使板料毛坯或其他坯料沿着直线(弯曲线)产生弯曲变形，从而获得一定角度和形状的工件的模具。 (3)拉深模是把板料毛坯制成开口空心件，或使空心件进一步改变形状和尺寸的模具。 (4)成形模是将毛坯或半成品工件按图凸、凹模的形状直接复制成形，而材料本身仅产生局部塑性变形的模具。如胀形模、缩口模、扩口模、起伏成形模、翻边模、整形模等。2?根据工序组合程度分类 (1)单工序模在压力机的一次行程中，只完成一道冲压工序的模具。 (2)复合模只有一个工位，在压力机的一次行程中，在同一工位上同时完成两道或两道以上冲压工序的模具。 (3)级进模(也称连续模) 在毛坯的送进方向上，具有两个或更多的工位，在压力机的一次行程中，在不同的工位上逐次完成两道或两道以上冲压工序的模具。 冲冷冲模全称为冷冲压模具。 冷冲压模具是一种应用于模具行业冷冲压模具及其配件所需高性能结构陶瓷材料的制备方法，高性能陶瓷模具及其配件材料由氧化锆、氧化钇粉中加铝、错元素构成，制备工艺是将氧化锆溶液、氧化钇溶液、氧化错溶液、氧化铝溶液按一定比例混合配成母液，滴入碳酸氢铵，采用共沉淀方法合成模具及其配件陶瓷材料所需的原材料，反应生成的沉淀经滤水、干燥，煅烧得到高性能陶瓷模具及其配件材料超微粉，再经过成型、烧结、精加工，便得到高性能陶瓷模具及其配件材料。本发明的优点是本发明制成的冷冲压模具及其配件使用寿命长，在冲压过程中未出现模具及其配件与冲压件产生粘结现象，冲压件表面光滑、无毛刺，完全可以替代传统高速钢、钨钢材料。 冷冲模具主要零件冷冲模具是冲压加工的主要工艺装备，冲压制件就是靠上、下模具的相对运动来完成的。 加工时由于上、下模具之间不断地分合，如果操作工人的手指不断进入或停留在模具闭合区，便会对其人身安全带来严重威胁。 1

毕业论文参考文献自动生成

今天刚知道原来参考文献可以自动生成……真丢脸！分享给为论文奋斗的同学来源： 周亮的日志 毕业论文不同于一般的小论文，特别是硕士毕业论文或者博士毕业论文。一般的小论文就四五页，而硕士论文动辄五六十页，有的甚至七八十页。所以有些东西如果要人工的去修改，将是一件非常痛苦的事情。痛苦的事情至少有两个：目录自动生成和编号、参考文献引用的上标。本文将从这两个方面说说小技巧，自动生成，非常方便。 先说两种痛苦情况。 设定好文章的目录结构后，突然发现中间要添加或者删除一个章节，添加删除容易，可是其后遗症就是后面的编号都要跟着变动。比如要删除第二章，那么原理的第三章就要改为第二章，后面的要跟着动，添加也一样，很麻烦。 第二个情况就是参考文献的上标问题。硕士论文参考文献都有好几十个，一般论文会要求按照论文的引用顺序列出参考文献。如果需要添加新的参考文献，那么这些参考文献的上标号又会跟着变动。 目录自动生成简单说下，将文档切换到大纲视图，然后设置你要设定成目录的文字的大纲级别。如果将大纲级别设定为1级，那么就是1级目录，一般我们会设置到3级，这样会生成1、2、3级目录。设定好后，在要插入目录的地方，点击“插入”-->“引用”-->“索引和目录”就可以了。格式在另外设置下就行了。 现在来说说这两个的简单解决办法。 首先都要设置成段落编号。将你要设定的一级目录设定成一级编号，二级目录设定成二级编号等等。参考文献一样，设置成段落编号。设定成段落编号有一个非常大的好处，就是插入或者删除其中的某个项目时，其后面的变好会跟着变动，所以这就解决了因添加删除中间的项目，而要同时修改后面的编号问题了。 目录的更新，只需要在“大纲视图”下点击更新目录，或者在页面视图的目录上，点击右键，选择“更新域”即可。

大学毕业论文---软件专业外文文献中英文翻译

软件专业毕业论文外文文献中英文翻译 Object landscapes and lifetimes Tech nically, OOP is just about abstract data typing, in herita nee, and polymorphism, but other issues can be at least as importa nt. The rema in der of this sect ion will cover these issues. One of the most importa nt factors is the way objects are created and destroyed. Where is the data for an object and how is the lifetime of the object con trolled? There are differe nt philosophies at work here. C++ takes the approach that con trol of efficie ncy is the most importa nt issue, so it gives the programmer a choice. For maximum run-time speed, the storage and lifetime can be determined while the program is being written, by placing the objects on the stack (these are sometimes called automatic or scoped variables) or in the static storage area. This places a priority on the speed of storage allocatio n and release, and con trol of these can be very valuable in some situati ons. However, you sacrifice flexibility because you must know the exact qua ntity, lifetime, and type of objects while you're writing the program. If you are trying to solve a more general problem such as computer-aided desig n, warehouse man ageme nt, or air-traffic con trol, this is too restrictive. The sec ond approach is to create objects dyn amically in a pool of memory called the heap. In this approach, you don't know un til run-time how many objects you n eed, what their lifetime is, or what their exact type is. Those are determined at the spur of the moment while the program is runnin g. If you n eed a new object, you simply make it on the heap at the point that you n eed it. Because the storage is man aged dyn amically, at run-time, the amount of time required to allocate storage on the heap is sig ni fica ntly Ion ger tha n the time to create storage on the stack. (Creat ing storage on the stack is ofte n a si ngle assembly in structio n to move the stack poin ter dow n, and ano ther to move it back up.) The dyn amic approach makes the gen erally logical assumpti on that objects tend to be complicated, so the extra overhead of finding storage and releas ing that storage will not have an importa nt impact on the creati on of an object .In additi on, the greater flexibility is esse ntial to solve the gen eral program ming problem. Java uses the sec ond approach, exclusive". Every time you want to create an object, you use the new keyword to build a dyn amic in sta nee of that object. There's ano ther issue, however, and that's the lifetime of an object. With Ian guages that allow objects to be created on the stack, the compiler determines how long the object lasts and can automatically destroy it. However, if you create it on the heap the compiler has no kno wledge of its lifetime. In a Ianguage like C++, you must determine programmatically when to destroy the

注塑模外文翻译

注塑成型智能模具设计工具 摘要 注塑成型是一个生产热塑性塑料制品最流行的制造工艺，而模具设计是这个过程的一个重要方面。模具设计需要专业的知识、技能，最重要的是拥有该领域的经验。三者缺一不可。生产塑料组件需要选择恰当的模具，如果缺乏其中之一，这种选择就得在反复试验的基础上进行。这会增加生产成本，并造成设计上的不一致。本文介绍了智能模具设计工具的发展。该工具捕获模具设计过程的知识，并且以符合逻辑的方式将这些知识反映出来。所获得的知识将是确定性的，但模具设计过程中的信息是非确定的。一旦开发了模具设计工具，它将指导使用者根据不同客户的要求，为其塑料零件选择合适的模具。 导言 注塑成型工艺过程需要专业的知识、技能，最重要的是需要它成功的实践经验。通常是工艺参数控制过程的效率。在制造过程中，有效地控制和优化这些参数能实现一致性，这种一致性会在零件质量和零件成本上表现出来的问题。 1 智能化工程模块注塑成型工艺（IKEM） 基于知识的智能化工程模块的注塑成型工艺（IKEM）是一种软件技术，它领先于并行工程和 CAD / CAM 系统。它集成工程的设计和制造工艺的最新知识，给用户各种设计方面的指示，通过减少在产品开发设计阶段的工程变更，有助于减少一些工时。该系统将用于注塑设计，设计迭代和流程整合。目前的过程由许多手工计算、CAD 图形结构和从以前项目取得的经验三部分组成。一旦工程师完成设计，这将是性能评估。该 IKEM 项目已分为三大模块。 1 费用估算模块 2 模具设计模块 3 生产模块 IKEM 系统有两种形式输入。在一个 CAD 模型的形式（Pro/E 文件）下输入，和在给出的用户界面形式下输入。制造商的经验水平将决定如何有效地控制工艺参数。有时这就导致人为错误引起的不一致性。还有经验不足，时间、资源短缺和创新的空间不大的情况。通过创造所谓的“智能模型”的问题，工程学知识提供了一个可行的方案去解决所有这样用户输入形式模架设计制造用户输出形式语法分析程 CAD 模型成本估计 2 智能模具设计工具 在它的基本形式中模具设计工具是一个从文本文件中提取输入的 Visual Basic 应用程序，这种文本文件包含关于零件和用户输入程序。该文本文件包含来自 Pro/E 的一个信息文件的零件的几何解析。输入是用来估测模具得尺寸和其它各种特性。 2.1 文献回顾 模具设计的是另一种注塑成型过程的阶段，有经验的工程师在很大程度上有助于自动化进程，提高其效率。这个问题需要注意的是深入研究设计模具的时间。通常情况下，当设计工程师设计模具时，他们会参阅表格和标准手册，这会消耗大量的时间。另外，在标准的CAD 软件中需要大量的时间去考虑模具的建模组件。不同的研究人员已经解决了缩短用不同的方式来设计模具所花费的时间的问题。凯尔奇和詹姆斯采用成组技术来减少模具设计时间。聚合一类注塑成型件的独特的编码系统和在注射模具中所需的工具已开发，它可以适用于其它产品生产线。实施编码系统的软件系统也已经被开发。通过获取在这方面领域的工程师的经验和知识，尝试直接使模具设计过程的自动化。并行模具设计系统的研究开发就是这样的一个过程，在并行工程环境中试图制定一个系统的注塑模具设计流程。他们的研究目标是研制一个有利于并行工程实践的模具开发的进程，和研制开发一个以知识为基础的为注塑模具设计提供工艺问题和产品要求的辅助设计。通过各种方式获取关于模具设计过程的确定信息和

模具专业外文文献最新

济南大学泉城学院 毕业设计外文资料翻译 题目现代快速经济制造模具技术 专业机械制造及其自动化 班级专升本1302班 学生刘计良 学号2013040156 指导教师刘彦 二〇一五年三月十六日

Int J Adv Manuf Technol ,(2011) 53:1–10DOI 10.1007/s00170-010-2796-y Modular design applied to beverage-container injection molds Ming-Shyan Huang & Ming-Kai Hsu Received: 16 March 2010 / Accepted: 15 June 2010 / Published online: 25 June 2010 # Springer-Verlag London Limited 2010 Modular design applied to beverage-container injection molds The Abstract: This work applies modular design concepts to designating beverage-container injection molds. This study aims to develop a method of controlling costs and time in relation to mold development, and also to improve product design. This investigation comprises two parts: functional-ity coding, and establishing a standard operation procedure, specifically designed for beverage-container injection mold design and manufacturing. First, the injection mold is divided into several modules, each with a specific function. Each module is further divided into several structural units possessing sub-function or sub-sub-function. Next, dimen-sions and specifications of each unit are standardized and a compatible interface is constructed linking relevant units. This work employs a cup-shaped beverage container to experimentally assess the performance of the modular design approach. The experimental results indicate that the modular design approach to manufacturing injection molds shortens development time by 36% and reduces costs by 19 23% compared with the conventional ap-proach. Meanwhile, the information on

毕业论文参考文献格式规范

毕业论文参考文献格式规范 一、参考文献的类型 参考文献（即引文出处）的类型以单字母方式标识，具体如下： [M]——专著,著作 [C]——论文集(一般指会议发表的论文续集，及一些专题论文集，如《***大学研究生学术论文集》。 [N]——报纸文章 [J]——期刊文章：发表在期刊上的论文，尽管有时我们看到的是从网上下载的（如知网），但它也是发表在期刊上的，你看到的电子期刊仅是其电子版。 [D]——学位论文：不区分硕士还是博士论文 [R]——报告：一般在标题中会有“关于****的报告”字样。 [S]——标准 [P]——专利 [A]——文章：很少用，主要是不属于以上类型的文章。 [Z]——对于不属于上述的文献类型，可用字母“Z”标识，但这种情况非常少见。 常用的电子文献及载体类型标识： [DB/OL] ——联机网上数据(database online) [DB/MT] ——磁带数据库(database on magnetic tape) [M/CD] ——光盘图书(monograph on CD ROM) [CP/DK] ——磁盘软件(computer program on disk) [J/OL] ——网上期刊(serial online) [EB/OL] ——网上电子公告(electronic bulletin board online) 很显然，标识的就是该资源的英文缩写，/前面表示类型，/后面表示资源的载体，如OL表示在线资源。 二、参考文献的格式及举例 1．期刊类 【格式】[序号]作者（两个以上用等）.篇名[J].刊名,出版年份,卷号(期号)起止页码. 【举例】 [1] 周融，任志国，等.对新形势下毕业设计管理工作的思考与实践[J].电气电

毕业论文 外文翻译#(精选.)

毕业论文（设计）外文翻译 题目：中国上市公司偏好股权融资：非制度性因素 系部名称：经济管理系专业班级:会计082班 学生姓名：任民学号： 200880444228 指导教师：冯银波教师职称:讲师 年月日

译文： 中国上市公司偏好股权融资：非制度性因素 国际商业管理杂志 2009.10 摘要：本文把重点集中于中国上市公司的融资活动，运用西方融资理论，从非制度性因素方面，如融资成本、企业资产类型和质量、盈利能力、行业因素、股权结构因素、财务管理水平和社会文化，分析了中国上市公司倾向于股权融资的原因，并得出结论，股权融资偏好是上市公司根据中国融资环境的一种合理的选择。最后，针对公司的股权融资偏好提出了一些简明的建议。 关键词：股权融资，非制度性因素，融资成本 一、前言 中国上市公司偏好于股权融资，根据中国证券报的数据显示，1997年上市公司在资本市场的融资金额为95.87亿美元，其中股票融资的比例是72.5％，，在1998年和1999年比例分别为72.6％和72.3％，另一方面，债券融资的比例分别是17.8％，24.9％和25.1％。在这三年，股票融资的比例，在比中国发达的资本市场中却在下跌。以美国为例，当美国企业需要的资金在资本市场上，于股权融资相比他们宁愿选择债券融资。统计数据显示，从1970年到1985年，美日企业债券融资占了境外融资的91.7％，比股权融资高很多。阎达五等发现，大约中国3/4的上市公司偏好于股权融资。许多研究的学者认为，上市公司按以下顺序进行外部融资：第一个是股票基金，第二个是可转换债券，三是短期债务，最后一个是长期负债。许多研究人员通常分析我国上市公司偏好股权是由于我们国家的经济改革所带来的制度性因素。他们认为，上市公司的融资活动违背了西方古典融资理论只是因为那些制度性原因。例如，优序融资理论认为，当企业需要资金时，他们首先应该转向内部资金（折旧和留存收益），然后再进行债权融资，最后的选择是股票融资。在这篇文章中，笔者认为，这是因为具体的金融环境激活了企业的这种偏好，并结合了非制度性因素和西方金融理论，尝试解释股权融资偏好的原因。

论文文献综述与参考文献--模版

1文献综述（一级标题，黑体三号加粗，居中） 1.1热油管道材料简介（二级标题，黑体四号） 自第一套轧机由美国轧机公司在Bulter成功建成后，美丽的故事们应该多样化的生 活………… 表23 辽宁石油化工--（表标题，宋体小四，加粗，居中，三线表）学生种类1998年1999年2000年 本科生100 150 300 硕士研究生20 60 100 博士研究生—— 5 12 点。表格可按全文统一编序，表格序号必须连续。表格允许下页接写，表题可省略，表头应重复写，并在右上方写"续表××"。表中各栏应注明量和相应的单位。表内数字须上下对齐。相邻栏内的数字或者内容相同，不能用“同上”、“同左”和其它类似用词，应一一重新标注。表格应写在离正文首次出现处的近处，不应过分超前或拖后。） 1.1.1热油管道钢质成分（三级标题，黑体小四） 23X1+32X2+45X3=380 （2.1）（公式书写说明：公式应另起一行，居中书写，公式的编号用圆括号括起放在公式右边行末（右对齐），公式和编号之间不加虚线。公式按全文统一编序号，公式序号必须连续。）

1.1.2 热油管道钢质性能 1.2 支持辊辊形技术 图23 北京科技大学校徽 （图像书写说明：毕业设计的插图必须精心制作，线条要匀称，图面要整洁美观。插图应与正文呼应，不得与正文脱节。每幅插图应有图序（图23）和图题（北京科技大学校徽），图序和图题应放在图位下方居中处。图应在描图纸或在洁白纸上用墨线绘成，也可以用计算机绘图。） 1.3 工作辊辊形的特点 E /V (S C E ) lg[i/(A ?cm -2 )] 图2 2024铝合金在不同浓度氯化镧海水中的动电位极化曲线