刀具磨损
为了避免金属切削刀具失效，第三章讲述了它的最低性能要求，即机械性能和耐热性。刀具失效是指过量的磨损会导致刀具失去切削材料的能力。在本章中，文章主要讲述了降低刀具磨损的累积使用特点和机制，它们是最终导致刀具被替代的因素。在现实生产实践中，有一中表示严重磨损程度的连续谱，在这里没有什么要考虑的和可能在实践中北描述为立即失效的两者之间没有明显的边界.在本章和上一章节中有重复的内容。
第二章和第三种的内容表明，金属切削刀具比普通机床轴承表面承受更大的摩擦力、正应力、高温。在大部分情况下，没有办法避免刀具磨损，但是可以研究如何避免加速刀具磨损的方法。刀具磨损的主要因素刀具表面应力和温度（主要取决于金属切削模式——车削、铣削、转削）、刀具和工件材料、切削速度、进给量、切削深度和切削液的类型等。在第二章中，主要讲述了影响刀具磨损的因素的微小变化都会导致磨损的变化。机械加工中，刀具磨损方式和磨损率对金属切削操作和切削条件的变化同样敏感。虽然刀具磨损无法避免，但是通常情况下可以控制磨损方式来减少刀具磨损。4.1节中介绍了刀具磨损的主要方式。
主要介绍了机械加工的经济型。为了尽量减少制造成本，不仅需要寻找最合适的刀具和工件材料，而且还要考虑切削刀具寿命。在刀具寿命结束时，刀具必须能够替换或者维修以保证加工工件的精度、表面粗造度或者完整性。4.2节主要介绍了刀具寿命的标准和估算。
4.1刀具磨损及其分类
4.1.1 刀具磨损的形式
根据刀具磨损的程度和磨损进程，刀具磨损可分为两类，即磨损和断裂。磨损（如第二章讨论）是一种粗糙材质表面损失或者微接触，或者磨粒较小，最小至分子或者原子的去除机理。它通常会持续进行直到断裂。另一方面，断裂是比磨损更严重的损害，它的发生具有突然性。正如上面所说，从微磨损到严重断裂是一种连续的损害。
图4.1显示了一个典型的磨损模式，在这种情况下的磨损—一把硬质合金刀具切割处于高速旋转下的金属工件。月牙洼前刀面磨损，前刀面侧翼侧边磨损和在切削深度末端的凹口磨损，它们是磨损的典型方式。磨损量可以用在4.2节中介绍的VB、KT表示。
然而磨损量随着切削材料、切削方式和切削条件的变化而变化，如图4.2。如
图4.2(a)显示月牙洼和后刀面磨损存在可疑忽略的沟槽磨损，在开机后用硬质合
金刀具切削高速旋转的45钢的条件下。如果改为铣削，一个有裂缝的大幅度月牙洼磨损将成为磨损的显著特点（图4.2（b））。当陶瓷刀具车削镍基超级合金时（图4.2（c）项）在美国商务部线沟槽磨损是主要的磨损模式，而月牙洼和后刀面磨损几乎可以忽略不计。图4.2（d）给出了一个氮化硅陶瓷车削工具切削碳钢的结果。月牙洼和后刀面磨损会在很短的时间内磨损更大。在切削工件材料变为b相态的情况下，大量的切削材料粘附于钛铝合金的K级硬质合金刀具的侧边部分，这样导致刀具磨损断裂或者破碎。
图4.1典型的硬质合金刀具磨损形式
（a）车削45碳钢（b）端面铣削45碳钢
（c）车削铬镍铁718 （d）车削45碳钢
（e）车削钛合金
典型的工具损伤观察–磨损和断裂： (a)刀具：烧结碳化物P10， v = 150 m min–1,d = 1.0 mm,f = 0.19 mm rev–1，t = 5分钟; (b)刀具：烧结碳化物P10， v = 400 m min–1， d = 1.0 mm， f = 0.19mm tooth–1，t = 5min; (c)刀具： Al2O3/TiC陶瓷刀具，v = 100 m min–1，d = 0.5 mm，f = 0.19 mm rev–1，t = 0.5分钟;(d)刀具：Si3N4陶瓷刀具，v = 300 m min –1，d = 1.0 mm，f = 0.19 mm rev–1，t = 1分钟; (e)刀具：烧结碳化物P10，v = 150 m min –1 d = 0.5 mm，f = 0.1 mm rev–1，t = 2 min。
4.1.2 刀具磨损的原因
第2.4章概述了导致磨料，胶粘剂和化学磨损机理的一般条件。在刀具的磨损，这些机理的重要性和发生的条件，可以按切削温度来划分，如图4.3所示。再图上有三个刀具磨损的因素被确定，分别为机械磨损、热磨损和化学磨损。机械磨损包括腐蚀、剥落、早期断裂和疲劳，它基本上与温度无关。热磨损包括塑性变形、热扩散和作为其典型形式的化学反应，它随着温度的急剧增加。（应当指出，热扩散和化学反应是不是损害的直接原因。相反，它们会导致刀具表面被削弱，使磨损，
抗机械冲击或粘连可以更容易造成材料去除。）基于粘附的磨损被观察到有一个在一定温度范围内的局部最大值。
图4.3刀具磨损和切削温度的关系
图4.4机械磨损的分类
(1)机械磨损
根据刀具磨损的程度和磨损进程，刀具磨损可分为两类，即磨损和断裂。磨损（如第二章讨论）是一种粗糙材质表面损失或者微接触，或者磨粒较小，最小至分子或者原子的去除机理。它通常会持续进行直到断裂。另一方面，断裂是比磨损更严重的损害，它的发生具有突然性。正如上面所说，从微磨损到严重断裂是一种连续的损害。
无论机械磨损被列为磨损或断裂，它都视磨粒的大小而定。如图4.4所示的几种不同的磨粒大小模式，它们从小于0.1微米达到约100微米（远大于100微米被视为失效）。
磨料磨损（如图2.29示意图）通常是由滑动对刀具硬质颗粒的磨损造成的。硬
质颗粒无论是来自工作材料的微观结构，还是从切削边缘破碎的颗粒。磨料磨损减少了刀具相对于粒子和一般取决于距离的切削困难（参见4.2.2节）。
摩擦磨损发生在磨料颗粒比磨料磨损比较大的情况下。在刀具与工件之间相互滑动运动，并且刀具材料的颗粒或者晶粒被磨损破坏前，刀具材料的颗粒或者晶粒的机械性能被微细裂缝消弱。接下来主要依据破碎片的大小（有时候它由于它的大小限制被称为细微碎片）。这是由机械冲击载荷的规模导致切削力波动大，而不是固有的波动，导致局部应力磨损。
最后断裂颗粒比破碎颗粒大，并分为三类：早期阶段、难以预测阶段和最后阶段。削减如果刀具形状或切割的条件是不适当的，或者如果刀具内部存在一些缺陷，或在其边缘有缺陷，这样刀具磨损会立即发生在开始切削工件后。不可预知的断裂可以发生在任何时间段，如果在切削过程中刀具或者工件尖端的压力突然发生变化，例如抖动或不规则的工件表面硬度不均匀所引起。最后阶段断裂可经常被观察到，特别是在铣削过程中并且刀具寿命末端的时候；这些主要是有机械疲劳或者热应力发生在工作部件凸出部分引起的磨损。
(2)热磨损—塑性变形
当刀具处于高温切削状态下时，刀具尖端部分不能承受气条件下正应力，此时热磨损的塑性变形将被观察到，如图4.3所示。因此，发生于刀具处于高温状态下的硬度将作为塑性变形的显著特点。所以例如一般情况下，高速钢刀具及钴含量高的硬质合金刀具或金属陶瓷刀具用于切削条件苛刻的条件下，特别是在高进给速度的情况下。因此，边缘变形将导致生成一个不正确的形状尺寸的工件和快速去除工件材料的情况。
(3)热磨损——扩散磨损
热扩散磨损的结果发生在高温切削条件下，如果刀具和工件材料的元素会扩散到彼此对方的结构中。这是众所周知的硬质合金刀具，并已被研究了多年。例如Dawihl（1941）、特伦特（1952）、Trigger和Chao（1956年）、武山和村田（1963年）、格雷戈里（1965），库克（1973）、上原（1976）、Narutaki和山根（1976年）、Usui et al（1978）和其他科学家。
由扩散控制的速率与绝对温度以指数幂的形式成正比。在磨损的情况下，不同的研究者提出了不同的指前因子的因素：库克研究提出了扩散深度h与相应的时间t之间的关系（公式4.1（a））；更早以前，竹山和村田（1963）也研究提出了这些观点，并且更进一步提出滑动距离可能是一个更基本的变量（方程4.1（b））；随后Usui et al. (1978)根据接触力学和被2.4节提及的磨损提出了磨损会随着正接触应力的增加而加剧（公式4.1（c））。在以上所有例子中可知，磨损率的对数与1/
θ将绘制出一条直线，直线的斜率就是C2。
图示4.5火山口与侧面磨损率深度碳素钢转由P20硬质合金,来自Kitagawa(1988)的研究
图4.5显示了月牙洼和两个侧翼的深度为0.25％碳含量处的磨损率和0.46％碳含量钢，用P20的硬质合金刀具惊醒切削的结果，此实验为了验证方程的方式（4.1c）。图4.5中出现两个线性区域，并且当1/θ≈8.5×10^(-4) K^(-1)(或θ≈1175K)时是一个临界点。在较高温度斜率（>1175 K）是钢材和水泥之间的碳化物（库克，1973年）扩散过程的典型。在较低温度下斜率是一个随温度变化的机械磨损过程的典型，例如摩擦磨损。
扩散可直接显示在静态条件下的高温。如图4.6显示了一个典型静态的扩散试验结果，其中一个P-级硬质合金刀具在1200摄氏度温度下对一个0.15％碳钢持续加载30分钟之间通过硬质合金刀具和钢界面在4％Nital（一磺酸的合成酒精）蚀
刻下，金相部分显示钢珠光体已经从原来的水平增加。这意味着，硬质合金中的碳已扩散到刚里面。
此外，电子探针显微分析仪（EPMA）表明，钴和钨已从工具材料也扩散到钢铁中，并且是铁铁扩散到钢刀具材料。许多研究者都认为相互扩散是硬质合金刀具扩
（b）到界面的距离（um）
图示4.6 典型的静态扩散试验结果,因为P10耦合至0.15% C钢(Narutaki和Yamane,1976年)（a）通过Nital蚀刻的接口部分;（b）通过电子探针分析元素的扩散
散磨损的原因，但是没有详细的说明，关于这种现象将导致工件材料的去除效果。
Naerheim和遄达（1977）提出，对双方碳化钨钴（金级）和WC的磨损率，（钛，钽，钨）的C -钴（P级）硬质合金是由扩散速率控制钨（和Ti和Ta）和碳原子组合成的工作的材料，如图4.7所示。这种观点是基于透射电子显微镜（TEM）对月牙洼磨损的观察，显示在该工具的碳化物颗粒内无一0.01的工具芯片接口毫米的距
离的结构变化。对与于P级比K级材料磨损较慢，这是缓慢扩散，它解释了前者比后者的情况。Naerheim和遄达指出，在他们的切削试验中，被拉伸碳化物颗粒并没有在粘附物的底部被观察到。这不是上原的（1976年）的经验。用K级或者P级含碳量为百分之47的刀具进行切削，他收集切屑，并将它溶解在酸性溶液中提取粘结的碳化物，最后让它通过一个0.1 mm过滤嘴，通过这种方案进行分类碳化物尺寸。用K -级刀具，他只观察碳化物小于0.1毫米的大小，这与Trent研究结果相一致。然而，用P-级刀具，他观察到碳化物大于0.1毫米大小。这表明K和P型材料不同的磨损机理。
扩散磨损的另一个例子是金刚石切割刀具、硅氮化硅陶瓷刀具和SiC晶须增韧氧化铝陶瓷刀具在加工钢时的严重磨损。碳、硅和氮在高温下它们都极容易扩散到铁中，并且氮化硅和碳化硅很容易溶解于铁水。
如果一个层作为扩散屏障沉积在刀具上，这样就可以减少硬质合金刀具的扩散磨损热。在实际生产中有两种这样类型沉积层：一个是由涂层刀具提供;另一种是保护性氧化层沉积在切割过程中的磨损表面，用于还原特殊钢（如钙脱氧钢），即通常有'belag之称的层。
注：文章来源Metal_Machining。
T ool damage
Chapter 3 considered cutting tool minimum property requirements (both mechanical and thermal) to avoid immediate failure. By failure is meant damage so large that the tool has no useful ability to remove work material. Attention is turned, in this chapter, to the mech- anisms and characteristics of lesser damages that accumulate with use, and which eventu- ally cause a tool to be replaced. In reality, there is a continuous spectrum of damage severities, such that there is no sharp boundary between what is to be considered here and what might in practice be described as immediate failure. There is some overlap between this chapter and the previous one.
Chapters 2 and 3 have demonstrated that cutting tools must withstand much higher fric- tion and normal stresses –and usually higher temperatures too –than normal machine tool bearing surfaces. There is, in most cases, no question of avoiding tool damage, but only of asking how rapidly it occurs. The damages of a cutting tool are influenced by the stress and temperature at the tool surface, which in turn depend on the cutting mode – for exam- ple turning, milling or drilling; and the cutting conditions of tool and work material, cutting speed, feed rate, depth of cut and the presence or not of cutting fluid and its type. In Chapter 2, it was described in general that wear is very sensitive to small changes in sliding conditions. In machining, the tool damage mode and the rate of damage are simi- larly very sensitive to changes in the cutting operation and the cutting conditions. While tool damage cannot be avoided, it can often be reduced if its mode and what controls it is understood. Section 4.1 describes the main modes of tool damage.
The economics of machining were introduced in Chapter 1. To minimize machining cost, it is necessary not only to find the most suitable tool and work materials for an oper- ation, but also to have a prediction of tool life. At the end of a tool’s life, the tool must be replaced or reground, to maintain workpiece accuracy, surface roughness or integrity. Section 4.2 considers tool life criteria and life prediction.
4.1T ool damage and its classification
4.1.1T ypes of tool damage
Tool damage can be classified into two groups, wear and fracture, by means of its scale and how it progresses. Wear (as discussed in Chapter 2) is loss of material on an asperity or micro-contact, or smaller scale, down to molecular or atomic removal mechanisms. It usually progresses continuously. Fracture, on the other hand, is damage at
a larger scale than wear; and it occurs suddenly. As written above, there is a continuous spectrum of damage scales from micro-wear to gross fracture.
Figure 4.1 shows a typical damage pattern –in this case wear – of a carbide tool, cutting steel at a relatively high speed. Crater wear on the rake face, flank wear on the flank faces and notch wear at the depth of cut (DOC) extremities are the typical wear modes. Wear measures, such as VB, KT are returned to in Section 4.2.
Damage changes, however, with change of materials, cutting mode and cutting condi- tions, as shown in Figure 4.2. Figure 4.2(a) shows crater and flank wear, with negligible notch wear, after turning a medium carbon steel with a carbide tool at high cutting speed. If the process is changed to milling, a large crater wear with a number of cracks becomes the distinctive feature of damage (Figure 4.2(b)). When turning Ni-based super alloys with ceramic tools (Figure 4.2(c)) notch wear at the DOC line is the
dominant damage mode while crater and flank wear are almost negligible. Figure 4.2(d) shows the result of turning a carbon steel with a silicon nitride ceramic tool (not to be recommended!). Large crater and flank wear develop in a very short time. In the case of -phase Ti-alloys with a K-grade carbide tool, large amounts of work material are observed adhered to the tool, and part of the cutting edge is damaged by fracture or chipping (Figure 4.2(e)).
4.1.2Causes of tool damage
Chapter 2.4 outlined the general conditions leading to abrasive, adhesive and chemical wear mechanisms. In the context of cutting tool damage, the importance and occurrence of these mechanisms can be classified by cutting temperature, as shown in Figure 4.3. Three causes of damage are qualitatively identified in the figure: mechanical, thermal and adhesive. Mechanical damage, which includes abrasion, chipping, early fracture and fatigue, is basi- cally independent of temperature. Thermal damage, with plastic deformation, thermal diffu- sion and chemical reaction as its typical forms, increases drastically with increasing temperature. (It should be noted that thermal diffusion and chemical reaction are not the direct cause of damage. Rather, they cause the tool surface to be weakened so that abrasion, mechanical shock or adhesion can then more easily cause material removal.) Damage based on adhesion is observed to have a local maximum in a certain temperature range.
Mechanical damage
Whether mechanical damage is classified as wear or fracture depends on its scale.
m becomes failure).
Abrasive wear (illustrated schematically in Figure 2.29) is typically caused by sliding hard particles against the cutting tool. The hard particles come from either the work mater- ial’s microstructure, or are broken away from the cutti ng edge. Abrasive wear reduces the harder is the tool relative to the particles and generally depends on the distance cut (see Section 4.2.2).
Attrition wear occurs on a scale larger than abrasion. Particles or grains of the tool material are mechanically weakened by micro-fracture as a result of sliding interaction with the work, before being removed by wear.
Next in size comes chipping (sometimes called micro-chipping at its small-scale limit). This is caused by mechanical shock loading on a scale that leads to large fluctuations in cutting force, as opposed to the inherent local stress fluctuations that cause attrition.
Finally, fracture is larger than chipping, and is classified into three types: early stage, unpredictable and final stage. The early stage occurs immediately after beginning a cut if the tool shape or cutting condition is improper; or if there is some kind of defect in the cutting tool or in its edge preparation. Unpredictable fracture can occur at any time if the
stress on the cutting edge changes suddenly, for example caused by chattering or an irreg- ularity in the workpiece hardness. Final stage fracture can be observed frequently at the end of a tool’s life in milling: then fatigue due to mechanical or thermal stresses on the cutting edge is the main cause of damage.
Thermal damage – plastic deformation
The plastic deformation type of thermal damage referred to in Figure 4.3 is observed when a cutting tool at high cutting temperature cannot withstand the compressive stress on its cutting edge. It therefore occurs with tools having a high temperature sensitivity of their hardness as their weakest characteristic. Examples are high speed steel tools in general; and high cobalt content cemented carbide tools, or cermet tools, used in severe conditions, particularly at a high feed rate. Deformation of the edge leads to generation of an improper shape and rapid material removal.
Thermal damage – diffusion
Wear as a result of thermal diffusion occurs at high cutting temperatures if cutting
tool and work material elements diffuse mutually into each other’s structure. This is well known with cemented carbide tools and has been studied over many years, by Dawihl (1941), Trent (1952), Trigger and Chao (1956), Takeyama and Murata (1963), Gregory (1965), Cook (1973), Uehara (1976), Narutaki and Yamane (1976), Usui et al. (1978) and others. The rates of processes controlled by diffusion are exponentially proportional to the
searchers have proposed different pre-exponential factors: Cook (1973) suggested depth wear h should increase with time t (equation 4.1(a)); earlier, Takeyama and Murata (1963) also suggested this and the further possibility of sliding distance s being a more fundamental variable (equation 4.1(b)); later Usui et al. (1978), following the ideas of contact mechanics and wear considered in Chapter 2.4, proposed wear should also increase with normal contact stress
against
straight line, the slope of which is –C2
0.25%C and a 0.46%C steel turned by a P20 grade carbide tool, plotted after the manner
typi- cal of diffusion processes between steels and cemented carbides (Cook, 1973). The
smaller slope at lower temperatures is typical of a temperature dependent
mechanical wear process, for example abrasion.
Diffusion can be directly demonstrated at high temperatures in static conditions.
Figure 4.6 shows a typical result of a static diffusion test in which a P-grade cemented
carbide tool was loaded against a 0.15% carbon steel for 30 min at 1200?C. A
metallographic section through the interface between the carbide tool and the steel, etched
in 4% Nital (nitric acid and alcohol) shows that the pearlite in the steel has increased from
its original level. This means that carbon from the cemented carbide has diffused into the
steel. Furthermore, elec- tron probe micro-analysis (EPMA) shows that Co and W from
the tool material also diffuse into the steel; and iron from the steel diffuses into the tool
material. Many researchers agree that mutual diffusion is the cause of carbide tool
diffusion wear, but there is not agreement in detail as to the mechanism that then results in material removal.
Naerheim and Trent (1977) have proposed that the wear rates of both WC-Co (K-grade) and WC-(Ti,Ta,W)C-Co (P-grade) cemented carbides are controlled by the rate of diffusion of tungsten (and Ti and Ta) and carbon atoms together into the work material, as indicated in Figure 4.7. This view is based on transmission electron microscope (TEM) observations on crater wear that show no structural changes in the tool’s carbide grains within a distance of 0.01 –chip interface. The slower wear of P-grade than K-grade materials is explained by slower diffusion in the former than the latter case. Naerheim and Trent state that, in their cutting tests, pulled-out carbide grains were not observed adher ing to the underside of chips. This was not Uehara’s (1976) experience. He collected chips after turn- ing a 0.47% C steel with a K-grade or a P-grade tool, dissolved the chips in acid to extract adhered carbides and finally passed the solution through a 0.1m filter, to classify the carbide sizes. With K-grade tools, he only observed carbides less than 0.1 -grade tools he observed
- and P-type materials.
Other examples of diffusion wear are the severe wear of diamond cutting tools,
silicon nitride ceramic tools and SiC whisker reinforced alumina ceramic tools when machining steel. Carbon, silicon and nitrogen all diffuse easily in iron at elevated temperatures; and silicon nitride and silicon carbide dissolve readily in hot iron.
Thermal diffusion wear of carbide tools can be decreased if a layer acting as a barrier to diffusion is deposited on the tool. There are two types of layer in practice: one is as provided by coated tools; the other is a protective oxide layer deposited on the wear surfaces during cutting special deoxidized steels (for example Ca-deoxidized steels), commonly known as a ‘belag’ layer.
理工学院 毕业设计外文资料翻译 专业：计算机科学与技术 姓名：马艳丽 学号： 12L0752218 外文出处：The Design and Implementation of 3D Electronic Map of Campus Based on WEBGIS 附件： 1.外文资料翻译译文；2.外文原文。
附件1：外文资料翻译译文 基于WebGIS的校园三维电子地图的设计与实现 一．导言 如今，数字化和信息化是当今时代的主题。随着信息革命和计算机科学的发展，计算机技术已经渗透到科学的各个领域，并引起了许多革命性的变化，在这些科目，古代制图学也不例外。随着技术和文化的不断进步，地图变化的形式和内容也随之更新。在计算机图形学中，地理信息系统（GIS）不断应用到Web，制作和演示的传统方式经历了巨大的变化，由于先进的信息技术的发展，地图的应用已经大大延长。在这些情况下，绘图将面临广阔的发展前景。电子地图是随之应运而生的产品之一。随着计算机技术，计算机图形学理论，遥感技术，航空摄影测量技术和其他相关技术的飞速发展。用户需要的三维可视化，动态的交互性和展示自己的各种地理相关的数据处理和分析，如此多的关注应支付的研究三维地图。东北石油大学及其周边地区的基础上本文设计并建立三维电子地图。 二．系统设计 基于WebGIS的校园三维电子地图系统的具有普通地图的一般特性。通过按键盘上的箭头键（上，下，左，右），可以使地图向相应的方向移动。通过拖动鼠标，可以查看感兴趣的任何一个地方。使用鼠标滚轮，可以控制地图的大小，根据用户的需求来查看不同缩放级别的地图。在地图的左下角会显示当前鼠标的坐标。在一个div层，我们描绘了一个新建筑物的热点，这层可以根据不同的地图图层的显示，它也可以自动调整。通过点击热点，它可以显示热点的具体信息。也可以输入到查询的信息，根据自己的需要，并得到一些相关的信息。此外，通过点击鼠标，人们可以选择检查的三维地图和卫星地图。 主要功能包括： ?用户信息管理：检查用户名和密码，根据权限设置级别的认证，允许不同权限的用户通过互联网登录系统。 ?位置信息查询：系统可以为用户提供模糊查询和快速定位。
附录 科技译文： Numerical Control Numerical Control(NC) is a method of controlling the movements of machineComponents by directly inserting coded instructions in the form of numerical data(numbers and data ) into the system.The system automatically interprets these data and converts to output signals. These signals ,in turn control various machine components ,such as turning spindles on and off ,changing tools,moving the work piece or the tools along specific paths,and turning cutting fluits on and off. In order to appreciate the importer of numerical control of machines ,let’s briefly review how a process such as machining has been carried out traditionally .After studying the working drawing of a part, the operator sets up the appropriate process parameters(such as cutting speed ,feed,depth of cut,cutting fluid ,and so on),determines the sequence of operations to be performed,clamps the work piece in a workholding device such as chuck or collet ,and proceeds to make the part .Depending on part shape and the dimensional accuracy specified ,this approach usually requires skilled
农村社会养老保险的现状、问题与对策研究社会保障对国家安定和经济发展具有重要作用，“城乡二元经济”现象日益凸现，农村社会保障问题客观上成为社会保障体系中极为重要的部分。建立和完善农村社会保障制度关系到农村乃至整个社会的经济发展，并且对我国和谐社会的构建至关重要。我国农村社会保障制度尚不完善，因此有必要加强对农村独立社会保障制度的构建，尤其对农村养老制度的改革，建立健全我国社会保障体系。从户籍制度上看，我国居民养老问题可分为城市居民养老和农村居民养老两部分。对于城市居民我国政府已有比较充足的政策与资金投人，使他们在物质和精神方面都能得到较好地照顾，基本实现了社会化养老。而农村居民的养老问题却日益突出，成为摆在我国政府面前的一个紧迫而又棘手的问题。 一、我国农村社会养老保险的现状 关于农村养老，许多地区还没有建立农村社会养老体系，已建立的地区也存在很多缺陷，运行中出现了很多问题，所以完善农村社会养老保险体系的必要性与紧迫性日益体现出来。 （一）人口老龄化加快 随着城市化步伐的加快和农村劳动力的输出，越来越多的农村青壮年人口进入城市，年龄结构出现“两头大，中间小”的局面。中国农村进入老龄社会的步伐日渐加快。第五次人口普查显示：中国65岁以上的人中农村为5938万，占老龄总人口的67.4%.在这种严峻的现实面前，农村社会养老保险的徘徊显得极其不协调。 （二）农村社会养老保险覆盖面太小 中国拥有世界上数量最多的老年人口，且大多在农村。据统计，未纳入社会保障的农村人口还很多，截止2000年底，全国7400多万农村居民参加了保险，占全部农村居民的11.18%，占成年农村居民的11.59%.另外，据国家统计局统计，我国进城务工者已从改革开放之初的不到200万人增加到2003年的1.14亿人。而基本方案中没有体现出对留在农村的农民和进城务工的农民给予区别对待。进城务工的农民既没被纳入到农村养老保险体系中，也没被纳入到城市养老保险体系中，处于法律保护的空白地带。所以很有必要考虑这个特殊群体的养老保险问题。
Unit1 1、What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table. Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans. 合金与纯金属的区别是什么？纯金属是在元素周期表中占据特定位置的元素。例如电线中的铜和制造烹饪箔及饮料罐的铝。 Alloys contain more than one metallic element. Their properties can be changed by changing the elements present in the alloy. Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium; and gold jewelry which usually contains an alloy of gold and nickel. 合金包含不止一种金属元素。合金的性质能通过改变其中存在的元素而改变。金属合金的例子有：不锈钢是一种铁、镍、铬的合金，以及金饰品通常含有金镍合金。 2、 Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio. 为什么要使用金属和合金？许多金属和合金具有高密度，因此被用在需要较高质量体积比的场合。 Some metal alloys,such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy. Many alloys also have high fracture toughness, which means they can withstand impact and are durable. 某些金属合金，例如铝基合金，其密度低，可用于航空航天以节约燃料。许多合金还具有高断裂韧性，这意味着它们能经得起冲击并且是耐用的。 3、The atomic bonding of metals also affects their properties. In m etals, the outer valence electrons are shared among all atoms, and ar e free to travel everywhere. Since electrons conduct heat and electri city, metals make good cooking pans and electrical wires. 金属的原子连结对它们的特性也有影响。在金属内部，原子的外层阶电子由所有原子共享并能到处自由移动。由于电子能导热和导电，所以用金属可以制造好的烹饪锅和电线。 It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal. No photons pass through. 因为这些阶电子吸收到达金属的光子，所以透过金属不可能看得见。没有光子能通过金属. 4、Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance. 陶瓷和玻璃的特性高熔点、低密度、高强度、高刚度、高硬度、高耐磨性和
外文翻译 专业机械设计制造及其自动化学生姓名刘链柱 班级机制111 学号1110101102 指导教师葛友华
外文资料名称： Design and performance evaluation of vacuum cleaners using cyclone technology 外文资料出处：Korean J. Chem. Eng., 23(6), (用外文写) 925-930 (2006) 附件： 1.外文资料翻译译文 2.外文原文
应用旋风技术真空吸尘器的设计和性能介绍 吉尔泰金，洪城铱昌，宰瑾李， 刘链柱译 摘要：旋风型分离器技术用于真空吸尘器 - 轴向进流旋风和切向进气道流旋风有效地收集粉尘和降低压力降已被实验研究。优化设计等因素作为集尘效率，压降，并切成尺寸被粒度对应于分级收集的50％的效率进行了研究。颗粒切成大小降低入口面积，体直径，减小涡取景器直径的旋风。切向入口的双流量气旋具有良好的性能考虑的350毫米汞柱的低压降和为1.5μm的质量中位直径在1米3的流量的截止尺寸。一使用切向入口的双流量旋风吸尘器示出了势是一种有效的方法，用于收集在家庭中产生的粉尘。 摘要及关键词：吸尘器; 粉尘; 旋风分离器 引言 我们这个时代的很大一部分都花在了房子，工作场所，或其他建筑，因此，室内空间应该是既舒适情绪和卫生。但室内空气中含有超过室外空气因气密性的二次污染物，毒物，食品气味。这是通过使用产生在建筑中的新材料和设备。真空吸尘器为代表的家电去除有害物质从地板到地毯所用的商用真空吸尘器房子由纸过滤，预过滤器和排气过滤器通过洁净的空气排放到大气中。虽然真空吸尘器是方便在使用中，吸入压力下降说唱空转成比例地清洗的时间，以及纸过滤器也应定期更换，由于压力下降，气味和细菌通过纸过滤器内的残留粉尘。 图1示出了大气气溶胶的粒度分布通常是双峰形，在粗颗粒（>2.0微米）模式为主要的外部来源，如风吹尘，海盐喷雾，火山，从工厂直接排放和车辆废气排放，以及那些在细颗粒模式包括燃烧或光化学反应。表1显示模式，典型的大气航空的直径和质量浓度溶胶被许多研究者测量。精细模式在0.18?0.36 在5.7到25微米尺寸范围微米尺寸范围。质量浓度为2?205微克，可直接在大气气溶胶和 3.85至36.3μg/m3柴油气溶胶。
附录 INTEGRATION OF MACHINERY （From ELECTRICAL AND MACHINERY INDUSTRY）ABSTRACT Machinery was the modern science and technology development inevitable result, this article has summarized the integration of machinery technology basic outline and the development background .Summarized the domestic and foreign integration of machinery technology present situation, has analyzed the integration of machinery technology trend of development. Key word：integration of machinery ，technology，present situation ，product t，echnique of manufacture ，trend of development 0. Introduction modern science and technology unceasing development, impelled different discipline intersecting enormously with the seepage, has caused the project domain technological revolution and the transformation .In mechanical engineering domain, because the microelectronic technology and the computer technology rapid development and forms to the mechanical industry seepage the integration of machinery, caused the mechanical industry the technical structure, the product organization, the function and the constitution, the production method and the management system has had the huge change, caused the industrial production to enter into “the integration of machinery” by “the machinery electrification” for the characteristic development phase. 1. Integration of machinery outline integration of machinery is refers in the organization new owner function, the power function, in the information processing function and the control function introduces the electronic technology, unifies the system the mechanism and the computerization design and the software which constitutes always to call. The integration of machinery development also has become one to have until now own system new discipline, not only develops along with the science and technology, but also entrusts with the new content .But its basic characteristic may summarize is: The integration of machinery is embarks from the system viewpoint, synthesis community technologies and so on utilization mechanical technology, microelectronic technology, automatic control technology,
英文翻译说明 1. 英文翻译文章输成word，5号新罗马（New Times Roman）字体，1.5倍行间距，将来方便打印和一起装订；英文中的图表要重新画，禁止截图。 2. 整篇论文1.5倍行间距，打印时，用B5纸，版面上空2.5cm，下空2cm，左空2.5cm，右空2cm（左装订）。 3. 论文翻译后的摘要用五号宋体，正文小四号宋体、英文和数字用新罗马（New Times Roman）12、参考文献的内容用五号字体。图和表头用五号字体加粗并居中，图和表中的内容用五号字体。论文翻译的作者用五号字体加粗。 论文大标题………小三号黑体、加黑、居中 第二层次的题序和标题………小四号黑体、加黑、居中 第三层次的题序和标题………小四号宋体、加黑、居中 正文……………………………小四号宋体、英文用新罗马12 页码……………………………小五号居中，页码两边不加修饰符 4. 论文中参考文献严格按照下述排版。 专著格式：序号.编著者.书名[M].出版地: 出版社, 年代, 起止页码 期刊论文格式：序号.作者.论文名称[J]. 期刊名称, 年度, 卷(期): 起止页码 学位论文格式：序号.作者.学位论文名称[D]. 发表地: 学位授予单位, 年度 例子: (1).胡千庭, 邹银辉, 文光才等. 瓦斯含量法预测突出危险新技术[J]. 煤炭学报, 2007.32(3): 276-280. (2). 胡千庭. 煤与瓦斯突出的力学作用机理及应用研究[D]. 北京: 中国矿业大学(北京), 2007. (3). 程伟. 煤与瓦斯突出危险性预测及防治技术[M]. 徐州: 中国矿业大学出版社, 2003.
1.我们可以把钢再次加热到临界温度以下的某一温度，然后在慢慢让其冷却。We can heat the steel again to a temperature below the critical temperature, then cool it slowly. 2.无论任何简单的机床，都是由单一元件即通称为机械零件或部件组成的。However simple, any machine is a combination of individual components generally referred to as machine elements or parts. 3.这些金属不都是好的导体。 All these metals are not good conductors. 4. 在做带电实验的时候，再怎么小心都不为过。 You can't be too careful in performing an experiment. 5.利用发电机可以把机械能转变成电能。 The mechanical energy can be changed back into electrical energy by means of a generator or dynamo. 6.假定电源输入的电压保持不变。 Assume that the voltage input of the power supply remains the same. 7.化石燃料是发电过程中最为频繁使用的能源。 Fossil fuels are most frequently used source daring the power generation process. 8单个机械零件的可靠性成为评估整台机器使用寿命的基本因素。 The individual reliability of machine elements becomes the basis for estimating the overall life 9.说我们生活在一个电子时代，这一点都不夸张。 It's no exaggeration to say that we live in an electronic age. 10.发动机的转速不应超过最大允许值。 Engine revolution should not exceed the maximum permissible. 11.如能从大型核电站获得成本极低的电力，电解氢的竞争能力就会增强。（Electrolytic hydrogen）。 If extremely low-cost power were ever to become available from large nuclear power plants, electrolytic hydrogen would become competitive. 12.电子技术提供了一种新的显示时间的方法。 A new way of displaying time has been given by electronics. 13.远距离输电需要高压，安全用电需要低压。 High voltage is necessary for long transmission line while low voltage for safe use. 14.铝的电阻大约是同等尺寸的铜的1.5倍。 The resistance of aluminum is approximately half again as great as that of copper for the same dimensions = size 15.In fact,it is impossible for no force to be exerted on a body,since in this world everything is subject to the for ce of gravity. 事实上，物体不受外力作用是不可能的，因为在这个世界上任何物体都要受到重力的作用。 16.In a thermal power plant,all the chemical energy is not
使用高级分析法的钢框架创新设计 1．导言 在美国，钢结构设计方法包括允许应力设计法(ASD)，塑性设计法(PD)和荷载阻力系数设计法(LRFD)。在允许应力设计中，应力计算基于一阶弹性分析，而几何非线性影响则隐含在细部设计方程中。在塑性设计中，结构分析中使用的是一阶塑性铰分析。塑性设计使整个结构体系的弹性力重新分配。尽管几何非线性和逐步高产效应并不在塑性设计之中，但它们近似细部设计方程。在荷载和阻力系数设计中，含放大系数的一阶弹性分析或单纯的二阶弹性分析被用于几何非线性分析，而梁柱的极限强度隐藏在互动设计方程。所有三个设计方法需要独立进行检查，包括系数K计算。在下面，对荷载抗力系数设计法的特点进行了简要介绍。 结构系统内的内力及稳定性和它的构件是相关的，但目前美国钢结构协会（AISC）的荷载抗力系数规范把这种分开来处理的。在目前的实际应用中，结构体系和它构件的相互影响反映在有效长度这一因素上。这一点在社会科学研究技术备忘录第五录摘录中有描述。 尽管结构最大内力和构件最大内力是相互依存的（但不一定共存），应当承认，严格考虑这种相互依存关系，很多结构是不实际的。与此同时，众所周知当遇到复杂框架设计中试图在柱设计时自动弥补整个结构的不稳定（例如通过调整柱的有效长度）是很困难的。因此，社会科学研究委员会建议在实际设计中，这两方面应单独考虑单独构件的稳定性和结构的基础及结构整体稳定性。图28.1就是这种方法的间接分析和设计方法。
在目前的美国钢结构协会荷载抗力系数规范中，分析结构体系的方法是一阶弹性分析或二阶弹性分析。在使用一阶弹性分析时，考虑到二阶效果，一阶力矩都是由B1,B2系数放大。在规范中，所有细部都是从结构体系中独立出来，他们通过细部内力曲线和规范给出的那些隐含二阶效应，非弹性，残余应力和挠度的相互作用设计的。理论解答和实验性数据的拟合曲线得到了柱曲线和梁曲线，同时Kanchanalai发现的所谓“精确”塑性区解决方案的拟合曲线确定了梁柱相互作用方程。 为了证明单个细部内力对整个结构体系的影响，使用了有效长度系数，如图28.2所示。有效长度方法为框架结构提供了一个良好的设计。然而，有效长度方法的
72页 Machine Tools Objectived. Machine tools are the main engines of the manufacturing industry. This chapter covers a few of the details that are common to all classes of machine tools discussed in this book. After completing the chapter, the reader will be able to >understand the classification of the various machine tools used in manufacturing industries. >identify the differences between generating and forming of surfaces. > identify various methods used to generate different types of surfaces. >distinguish between the different accuracies and surface finishes that are achievable with different machine tools. >understand the different components of the machine tools and their functions. >learn about the different support structures used in the machine tools. >understand the various actuation systems that are useful to generate the required surfaces. >Learn the different types of guideways used in the machine tools. >understand the work holding requirements. 3.1 INTRODUCTION The earliest known machine tools are the Egyptian foot-operated lathes.
本科毕业论文(设计) 外文翻译 学院：机电工程学院 专业：机械工程及自动化 姓名：高峰 指导教师：李延胜 2011年05 月10日 教育部办公厅 Failure Analysis，Dimensional Determination And
Analysis，Applications Of Cams INTRODUCTION It is absolutely essential that a design engineer know how and why parts fail so that reliable machines that require minimum maintenance can be designed．Sometimes a failure can be serious，such as when a tire blows out on an automobile traveling at high speed．On the other hand，a failure may be no more than a nuisance．An example is the loosening of the radiator hose in an automobile cooling system．The consequence of this latter failure is usually the loss of some radiator coolant，a condition that is readily detected and corrected．The type of load a part absorbs is just as significant as the magnitude．Generally speaking，dynamic loads with direction reversals cause greater difficulty than static loads，and therefore，fatigue strength must be considered．Another concern is whether the material is ductile or brittle．For example，brittle materials are considered to be unacceptable where fatigue is involved． Many people mistakingly interpret the word failure to mean the actual breakage of a part．However，a design engineer must consider a broader understanding of what appreciable deformation occurs．A ductile material，however will deform a large amount prior to rupture．Excessive deformation，without fracture，may cause a machine to fail because the deformed part interferes with a moving second part．Therefore，a part fails(even if it has not physically broken)whenever it no longer fulfills its required function．Sometimes failure may be due to abnormal friction or vibration between two mating parts．Failure also may be due to a phenomenon called creep，which is the plastic flow of a material under load at elevated temperatures．In addition，the actual shape of a part may be responsible for failure．For example，stress concentrations due to sudden changes in contour must be taken into account．Evaluation of stress considerations is especially important when there are dynamic loads with direction reversals and the material is not very ductile． In general，the design engineer must consider all possible modes of failure，which include the following． ——Stress ——Deformation ——Wear ——Corrosion ——Vibration ——Environmental damage ——Loosening of fastening devices
2、应力和应变 在任何工程结构中独立的部件或构件将承受来自于部件的使用状况或工作的外部环境的外力作用。如果组件就处于平衡状态,由此而来的各种外力将会为零,但尽管如此,它们共同作用部件的载荷易于使部件变形同时在材料里面产生相应的内力。 有很多不同负载可以应用于构件的方式。负荷根据相应时间的不同可分为: (a)静态负荷是一种在相对较短的时间内逐步达到平衡的应用载荷。 (b)持续负载是一种在很长一段时间为一个常数的载荷, 例如结构的重量。这种类型的载荷以相同的方式作为一个静态负荷; 然而,对一些材料与温度和压力的条件下,短时间的载荷和长时间的载荷抵抗失效的能力可能是不同的。 (c)冲击载荷是一种快速载荷(一种能量载荷)。振动通常导致一个冲击载荷, 一般平衡是不能建立的直到通过自然的阻尼力的作用使振动停止的时候。 (d)重复载荷是一种被应用和去除千万次的载荷。 (e)疲劳载荷或交变载荷是一种大小和设计随时间不断变化的载荷。 上面已经提到，作用于物体的外力与在材料里面产生的相应内力平衡。因此,如果一个杆受到一个均匀的拉伸和压缩，也就是说, 一个力,均匀分布于一截面,那么产生的内力也均匀分布并且可以说杆是受到一个均匀的正常应力,应力被定义为 应力==负载 P /压力 A, 因此根据载荷的性质应力是可以压缩或拉伸的,并被度量为牛顿每平方米或它的倍数。 如果一个杆受到轴向载荷，即是应力，那么杆的长度会改变。如果杆的初始长度L和改变量△L已知，产生的应力定义如下: 应力==改变长△L /初始长 L 因此应力是一个测量材料变形和无量纲的物理量 ,即它没有单位;它只是两个相同单位的物理量的比值。 一般来说,在实践中,在荷载作用下材料的延伸是非常小的, 测量的应力以*10-6的形式是方便的, 即微应变, 使用的符号也相应成为ue。 从某种意义上说，拉伸应力与应变被认为是正的。压缩应力与应变被认为是负的。因此负应力使长度减小。 当负载移除时，如果材料回复到初始的，无负载时的尺寸时，我们就说它是具有弹性的。一特定形式的适用于大范围的工程材料至少工程材料受载荷的大部分的弹性, 产生正比于负载的变形。由于载荷正比于载荷所产生的压力并且变形正比于应变, 这也说明,当材料是弹性的时候, 应力与应变成正比。因此胡克定律陈述, 应力正比于应变。 这定律服从于大部分铁合金在特定的范围内, 甚至以其合理的准确性可以假定适用于其他工程材料比如混凝土，木材，非铁合金。 当一个材料是弹性的时候，当载荷消除之后，任何负载所产生的变形可以完全恢复,没有永久的变形。
英文翻译 题目: 通过分析变压器中溶解气体而进行故障诊断的专家系统 姓名: 宋日成 学院: 工学院 专业: 自动化 班级: 自动化112 班学号: 32211218 指导教师: 陆静职称: 讲师 2015年3月14日 南京农业大学教务处制
An Expert System for Transformer Fault Diagnosis Using Dissolved Gas Analysis W. S. Chan ·Y. L. Xu ·X. L. Ding ·W. J. Dai Received: 9 November 2005 / Accepted: 11 August 2006 / Published online: 7 September 2006? Springer-Verlag 2006 Abstract In order to automate the transformer fault diagnosis, improve the accuracy of judgment, the introduction of artificial intelligence expert system fault diagnosis. The system is based on fuzzy reasoning confidence by observing the information, the use of knowledge to reach a conclusion. Test proved this method reduces the randomness of judgment, improved diagnosis. Keywords:Expert System Transformer Troubleshooting 1 Introduction The power transformer is a major apparatus in a power system, and its correct functioning is vital to system operations. In order to minimize system outages,many devices have evolved to monitor the serviceability of power transformers. These devices, such as, Buchholz relays or differential relays, respond only to a severe power failure requiring immediate removal of the transformer from service, in which case, outages are inevitable. Thus, preventive techniques for early detection faults to avoid outages would be valuable. In this way, analysis of the mixture of the faulty gases dissolved in insulation oil of power transformer has received worldwide recognition as an effective method for the detection of incipient faults. Many researchers and electrical utilities have reported on their experience and developed interpretative criteria on the basis of DGA. However, criteria tend to vary from utility to utility. Each approach has limitations and none of them has a firm mathematical description. Therefore, transformer diagnosis is still in the heuristic stage. For this reason, knowledge-based programming is a suitable approach to implement in such a diagnostic problem. Based on the interpretation of DGA, a prototype of an expert system for diagnosis of suspected transformer faults and their maintenance procedures is proposed. The significant source in this knowledge base is the gas ratio method. Some limitations of this approach are overcome by incorporating the diagnostic procedure and the synthetic expertise method. Furthermore, data bases adopted from TPCS gas records of transformers are incorporated into the expert system to increase the practical performance. Uncertainty of diagnosis is managed by using fuzzy set concepts. This expert system is constructed with rule based knowledge representation, since it can be expressed by experts. The expert system building tool, Knowledge Engineering System (KES), is used in the development of the knowledge system