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编号： 毕业设计任务书题 目： 3D打印机设计 学院： 机电工程学院 专 业： 机械设计制造及其自动化 学生姓名： 沈 源 学 号： 1200110419 指导教师单位： 机电工程学院 姓 名： 杨孟杰 职 称： 硕士/未评级 题目类型：理论研究 实验研究 工程设计 工程技术研究 软件开发 2015年12月28日一、毕业设计（论文）的内容本次设计是对3D打印机进行设计，具体内容如下：1、查阅相关资料，了解3D打印机工作原理；2、进行方案选择论证，优选出最佳方案；3、进行3D打印机主传动系统设计；设计3D打印机外形结构、送丝机构等关键零部件，并对关键零部件进行受力分析及校核。4、绘制装配图、零件图，编制设计计算说明书；5、了解相关的国家标准的应用。二、毕业设计（论文）的要求与数据要求：1、 成型半径200mm,成型高度300mm；2、 3D打印机结构形式：并联；3、 喷头直径：0.4mm。三、毕业设计（论文）应完成的工作指定整个毕业设计学生应该完成的所有工作包括：1、完成二万字左右的毕业设计说明书（论文）；在毕业设计说明书（论文）中必须包括详细的300-500个单词的英文摘要；2、独立完成与课题相关，不少于四万字符的指定英文资料翻译（附英文原文）；3、绘制3D打印机总装配图和主要零部件图，绘图工作量折合A0图纸3张以上，其中必须包含两张A3以上的计算机绘图图纸。四、应收集的资料及主要参考文献1 任仲贵. CAD/CAM原理M. 北京：清华大学出版社，1991.9.2 吴宗泽. 机械设计实用手册M. 北京：机械工业出版社，2002.3 朱学敏. 起重机械M. 北京：机械工业出版社，2003.4 丁克勤. 起重机械虚拟仿真计算与分析M. 北京：机械工业出版社，2010.5 王新荣, 陈永波.有限元法基础及ANSYS应用M. 北京：科学出版社，2008.6 吴宗泽. 机械零件设计手册M. 北京：机械工业出版社，2004.7 杨明忠. 机械设计M. 北京：机械工业出版社，2001.8 王明强. 计算机辅助设计技术M. 北京：科学出版社，2002.9 杨继全. 侯丽雅著三维打印设计与制造，科学出版社，2013-11-014.10 王运赣. 王宣著.三维打印技术,华中科技大学出版社,2013-08-011 Mischke,Charles R., Shigley,Joseph Edward. Mechanical engineering designM. Boston,Mass:McGraw Hill,2001.5、 试验、测试、试制加工所需主要仪器设备及条件计算机一台，CAD设计软件（CATIA）任务下达时间：2015年12月28日毕业设计开始与完成时间：2015年12月28日至 2016年05 月22日组织实施单位： 机械电子工程系教研室主任意见：签字： 2015年12月30日院领导小组意见：签字： 2015年12月31日编号： 毕业设计开题报告题 目： 3D打印机设计 院 （系）： 机电工程学院 专 业： 机械设计制造及其自动化学生姓名： 沈源 学 号： 1200110419 指导教师单位： 机电工程学院 姓 名： 杨孟杰 职 称： 硕士/未评级 题目类型：理论研究 实验研究 工程设计 工程技术研究 软件开发 2016年3月1日1毕业设计的主要内容、重点和难点等本次设计是对3D打印机进行设计，大致内容如下：1、了解3D打印机的基本工作原理；2、通过查阅资料了解其控制方法和工作原理，选取控制电机；3、查阅相关资料及标准，熟悉3D打印机结构及运动方式；4、进行3D打印机主传动系统设计；设计3D打印机外形结构、送丝机构等关键零部件，并对关键零部件进行受力分析及校核5、绘制装配图、零件图，编制设计计算说明书；6、了解相关的国家标准的应用。 重点和难点 本课题的重点、难点是选取控制电机；3D打印机结构及运动方式；3D打印机主传动系统设计；设计3D打印机外形结构、送丝机构等关键零部件，并对关键零部件进行受力分析及校核；绘制装配图、零件图。2准备情况（查阅过的文献资料及调研情况、现有设备、实验条件等） 调研情况 随着时代的进步，3D打印技术也得到了进一步发展跨入了一个全新的领域，新的信息和控制以及材料等技术不断被广泛应用到机械制造领域，3D打印技术也将会被推向各个领域。在以后3D打印技术将会向精密和智能以及通用便捷化等方向发展。如今，我们需要做的是研制更多类型的打印材料，提升它的打印速度、效率和精度。提高3D打印成品的表面质量、粗糙度和物理性能，以实现直接面向产品的制造。比如智能材料和功能梯度材料和纳米材料以及非均质材料及复合材料等。特别是新型材料直接成型技术有可能成为以后研究3D打印与应用的另一个热点。3D打印机的体积非常小和可以桌面化以及成本更低廉、操作更简便等等特点。更加适应分布化生产和设计与制造一体化的需求以及家庭日常应用的需求。现在的软件可以集成化使设计软件和生产控制软件能够无缝对接，拓展在生物医学和建筑工程以及车辆以及服饰等更多新型领域的应用。 查阅的文献资料1 任仲贵. CAD/CAM原理M. 北京：清华大学出版社，1991.9.2 液压传动，章宏甲主编. 北京：机械工业出版社，2002.3 朱学敏. 起重机械M. 北京：机械工业出版社，2003.4 丁克勤. 起重机械虚拟仿真计算与分析M. 北京：机械工业出版社，2010.5 吕宏 王慧主编机械设计.北京大学出版社2010.8.6 沈纫秋主编工程材料与制造工艺教程北京：航空工业出版社1991.5.7 杨明忠. 机械设计M. 北京：机械工业出版社，2001.8 王明强. 计算机辅助设计技术M. 北京：科学出版社，2002.9 朱理主编机械原理高等教育出版社.2010.4.10 Mischke,Charles R., Shigley,Joseph Edward. Mechanical engineering designM. Boston,Mass:McGraw Hill,2001. 试验、测试、试制加工所需主要仪器设备及条件 （1）计算机一台；（2）caxa电子图板,solidworks三维绘图软件。 3、实施方案、进度实施计划及预期提交的毕业设计资料 实施方案：1、 查阅以上参考文献积累知识，和老师沟通并分析整体流程，进行多种方案论证比较，确定最后的设计方案。 2、依次设计传动结构、搅拌机构，设计计算传动系统、执行系统并进行必要的校核计算。 3、绘制主要零部件图和总体装配图。 4、设计说明书的编写。毕 业设计(论文)工作内容及进度实施计划：1、开题报告 第 1周2、总体方案设计 第 2-4周3、常规设计 第5-8周4、工艺规程设计 第9-11周5、编写毕业设计说明书 第12-14周6、外文资料翻译 第15周7、准备答辩 第16周预期提交资料：1、完成二万字左右的毕业设计说明书（论文）；在毕业设计说明书（论文）中必须包括详细的300-500个单词的英文摘要；2、独立完成与课题相关，不少于四万字符的指定英文资料翻译（附英文原文）；3、3D打印机总装配图和主要零部件图，绘图工作量折合A0图纸3张以上，其中必须包含两张A3以上的计算机绘图图纸。指导教师意见指导教师（签字）： 2016年3月日开题小组意见开题小组组长（签字）：2016年3 月日 院（系、部）意见 主管院长（系、部主任）签字： 2016年3月日- 3 -编号： 毕业设计(论文)外文翻译（原文）学 院： 机电工程学院 专 业：机械设计制造及其自动化 学生姓名： 林 建 学 号： 1200110414 指导教师单位： 机电工程学院 姓 名： 杨孟杰 职 称： 硕士/未评级 2016年6月8日Fatigue life prediction of the metalwork of a travelling gantry craneV.A. KopnovAbstractIntrinsic fatigue curves are applied to a fatigue life prediction problem of the metalwork of a traveling gantry crane. A crane, used in the forest industry, was studied in working conditions at a log yard, an strain measurements were made. For the calculations of the number of loading cycles, the rain flow cycle counting technique is used. The operations of a sample of such cranes were observed for a year for the average number of operation cycles to be obtained. The fatigue failure analysis has shown that failures some elements are systematic in nature and cannot be explained by random causes.卯1999 Elsevier Science Ltd. All rights reserved.Key words: Cranes; Fatigue assessment; Strain gauging1. Introduction1.1 Characteristics and Developmental Tendency of Modern Cranes With rapid development of modern science and technology, magnification of industrial production scale and improvement of automation level, application of cranes is becoming widespread and its function is obvious. Meanwhile, requirements for cranes are more and more strict. Especially, the widespread use of electronic computer technology spurs lots of subject-crossing advanced design approaches and accelerates the improvement of modern manufacturing and detecting technology. Fierce competition in international market becomes more dependent on the competition of technology. All of these impel technological functions of cranes into a brand-new developmental stage. Cranes are facing a tremendous transformation. Our country is entering global international competitive market at an unprecedented rate and crane manufacture is confronted with a new situation where opportunities and challenges coexist. Thus, it is crucial for cranes to develop and innovate constantly. I want to make a brief explanation about characteristics and developmental tendency of modern cranes with examples, based on new theories, technology and trend of cranes at home and overseas.1)Make the key products large, high speed, endured and specializedBecause of continuous expansion of industrial production scale, increasingly improvement of production efficiency and rising proportion of money spending on loading and unloading and transporting materials in the process of production, required amount of large or high-speed cranes is increasing. Lifting quantities become larger, working speed becomes higher and requirements of energy-consuming and reliability become stricter. Cranes have already become a critical link in the process of automation production. Cranes should be easy to use, maintain and operate and have high security, less troubles and long average time between failures. The central issue in international market production competition is reliability, and many companies abroad have drawn up inter-controlled standard of reliability. The most important for us to catch up with and surpass world advanced level of cranes function is to improve reliability, to make cranes durable, less troubles, maintainable and economic to be used.At the moment, the biggest floating crane in the world weighs 6500t, chain crane 3000t and bridge crane 1200t. Diversity of industrial mode of production and customers need makes crane market expanding and products renewing constantly to satisfy special needs with specific functions and bring its best usefulness into play. Functions of various kinds of cranes are improving. DEMAG ERGOTECH has developed a crane special for aircraft maintenance, which has made its own way into international market. This crane is great in length and lifting height and has accurate halt. When a flexible maintenance platform fixed under lifting cart, it can reach every part of the aircraft. With the fast development of nuclear power stations in the world, cranes which are special for them achieve corresponding development. For example, annular bridge crane in reactors space, working under radiative circumstances, is used to lift dangerous load such as top cover of pressure container and components in reactors. It requires high reliability, high security, the ability to determine location accurately and automatically and transfer goods to a lower level, as well as various kinds of protection and particular security devices.2)Make series of production modularized, combined, standardized and practicalMost cranes are produced by series and batch, thus use of systematic multi-objections entire optimization to design series of cranes has already become the key point in development. Through rational matching of series main parameter, its functions can be improved, manufacturing cost can be reduced, and degree of general purpose can be raised. Use less specification spare parts to compose series production with multi-species and multi-specifications. And thus, the requirements of customers can be fully satisfied.By using modularized design instead of conservative entire design, we can make components with similar functions into standard modules which have various uses, similar connective key factors and are interchangeable. Through combination of different modules, we can make different kinds and specifications of cranes. There are only several modules involved when it comes to crane improvement. To design a new style of crane, all that you do is to choose different modules to recompose. Because of improvement in degree of general purpose, single products with small serial production can transform into module production of pretty great batches. As a result, we can achieve specialization production with high efficiency and cut manufacturing cost. It can satisfy marketing demands and increase competitive capacity by composing cranes of various series and specifications using less modularized forms.Bridge crane produced by DEMAG ERGOTECH considered carefully modularization and combination. It makes inter-parameter of series, entirety, mechanism and components matched with each other. The distribution of capacity obtains most economic and suitable effects. To make the main components of lifting mechanism reaches its largest general purpose, the method that the result of lifting weights multiplying lifting speed is a constant has been used. There are more specifications derived through changes of pulley multiplying power. Series of 5-125t bridge cranes only need four basic lifting carts even with various working ranks. Module series of standard wheel cases, which are produced by the company, have various groups of linking holes which can choose different drive unit to form platform carts. They can also combine with metal construction components to be used as running machine of various kinds of cranes; its wheels have several forms of surfaces to be chosen. Because of no basic distance limit and flexible combination, they are widely used. The companys series of end bridge standard modules have commercialized. It resorts to frictional cycle and high intensity bolt link which improves interchange and accuracy of sizes and reduces machining of connecting covers. It can connect to each main beam quickly and effectively. There are two kinds of end beam modules; one is suitable for single beam and the other is for double beams. According to length and weights, end beam style can be decided.3)Make productions for general purposes small, light, simple and diversifiedThere are quite a number of cranes used in general workshop and storehouse, and thus they have light work and the requirement is not very strict. How to improve application of these cranes and to cut manufacturing cost is critical to win in the marketing competition. Considering comprehensive benefit, the need to decrease the height of cranes as low as possible, to simplify the constructions and to reduce weights and wheel pressure can also decrease structures height, lighten structure composition and reduce cost of producing and maintenance. So there will be fast development of electric calabash bridge and light beam cranes, and bridge cranes for general purposes will be replaced by them.The needs of customers advance diversity of cranes. Series parameter scale of cranes expanding and functions enlarging, product of one machine for several uses will obtain further development to increase capacity of dealing with emergencies. The proportion of using wireless remote control under normal conditions will increase.DEMAG ERGOTECH has formed standard crane series of light combinations after long period explosion and innovation. The whole series compose of various productions such as combination “工” style single beam, hanging case single beam, horn cart case single beam and case double beams. There are altogether fifteen forms of connection between main beam and end beam. This is suitable for needs of different structure and lifting goods. Each specification of crane has three single speeds and three double speeds to be chosen. There are seven operating ways. In addition, different electric conduction pattern and different electric control pattern can match hundreds and thousands of cranes through different combinations to fully satisfy different needs of customers. Another advantage of the crane is that they are light. Compared to productions at home, its lifting weight is 32t and length 25.5m compared to 46.4t-weight of double beams cranes in our country, 28.3t- electric calabash bridge cranes. Weight of DEMAG electric calabash bridge crane is only 18.5, which is lighter than domestic productions by 60 percent and 35percent respectively.1.2 Type of CranesCranes can be classified into four kinds, namely, (a) overhead traveling crane; (b) jib crane; (c) bridge or gantry crane; and (d) cantilever crane. Overhead traveling crane. Consists of a girder and a trolley. The girder is supported at each end on trucks capable of traveling on elevated fixed tracks. The trolley is equipped with hoisting and other mechanism, capable of traversing from end to end of such girder. The girder and associated end carriages are known as the bridge. Such cranes vary in lifting capacity from about 2 tons to 400 tons, and in span from 20 ft to 150 ft,or more. Depending on the purpose for which it is to be used, the crane can be operated either from a cabin fixed to the bridge or the trolley, or from the ground. When two trolleys are furnished, these may run on a common tracks arranged side-by-side or one above the other so that each trolley can traverse the entire span. Jib crane: Consists of an inclined member, or jib, capable of suspending a load at its outer end. The jib is supported by a rope or other member attached to a vertical mast of frame. The out reach of the jib can be constant or variable, and the crane as a whole may be either fixed or movable.Included in this kind are: mobile and caterpillar cranes, builders tower cranes, wharf cranes, and movable cranes mounted on high pedestals, gantries, pontoons and barges. Lifting capacities vary from 1/2 ton to 300 tons or more, and outreaches from a few feet to 150 ft. Cranes required for handling heavy machinery and equipment in shipyards and at ports are frequently mounted on pontoons.Bridge or gantry crane: Consists of a bridge girder, connected at near both ends to upright members, which may be fixed or arranged to travel on a fixed track, and the load is suspended from a trolley or crane, capable or traversing from end to end of the bridge. Cranes of this kind have lifting capacities varying from end to end of the bridge. When used in general and bulk-storage yards, the tracks may be of broad or narrow gauge. The tipping moment of the loaded crane is kept within proper limits by a counterweight which is moved along an independent track on the bridge above the trolley. Cantilever crane: Consists of horizontal and vertical members the former, known as the cantilever, being fixed to or totating in a horizontal plane about the axis of the vertical member. On the cantilever is formed a track which supports a movable trolley from which the load is suspended.The mechanism for hoisting and traversing is usually mounted on a rear extension of the cantilever. Although such cranes may be fixed or movable, those of large capacity are usually fixed. Lifting capacities, height of lift and outreach vary between wide limits. When used for the fitting out of ships, light loads are handled by an auxiliary hoist which may be mounted on a jib crane arranged to travel on track. The main lifting mechanism usually consists of two winches which can be operated independently or in concert. A typical fitting-out crane may be of 250 tons capacity with a total outreach of 180 ft and a lifting height of 200 ft. Wharf Cranes: A wharf crane is any crane located on a wharf or pier, and particularly adapted to the transfer of cargo between the wharf or pier and the hold of the vessel alongside; it is also called a cargo crane, although the latter term is more general, as it comprises also parts of the cargo-handling gear of a vessel. Owing to the varying spacing of vessel hatchways, the wharf crane in most cases must be capable of movement along the wharf, and hence is generally mounted on a runway. Other requirements are sufficient horizontal reach to cover the hatchway,sufficient length of host to raise the load from the bottom of the hold to a point entirely clear of the vessel, and rapidity and economy on operation.Types much used as wharf cranes are single or double portal gantries or traveling bridges on the wharf shed roof, carrying rotating bridges on cantilever gantries with folding extensions over the hatchways; gantries with inclined cantilever jibs; also of the derrick type.In the handling of general cargo, as contrasted to bulk cargo, a broader view in analyzing the situation has to be taken. Diversity of shape, size and weight precludes the possibility of using elevators or conveyors to any great extent, while the necessity of sorting and piling in allotted places on the wharf makes the transporter, with its rather limited area of discharge, unsuitable.The traveling portal crane, having a boom capable of being luffed as well swung, is much used as a wharf crane. One of the chief disadvantages, however, which the ordinary luffing crane works under is that when the boom is luffed-in the load suspended from the top of the boom is simultaneously raised; conversely, as the boom is lowered, the load falls by a corresponding amount. This, obviously,is a loss of work and means an unnecessarily large motor to work the luffing gear.To overcome this objection a number of different designs of a type of crane known as the level-luffing crane have been developed, and these cranes are now extensively used as wharf cranes. In this type of cranes a compensating gear in some form or another is provided whereby the load is made to travel along a horizontal path irrespective of the rise and fall of the hoisting pulley caused by the luffing-in or out of the boom. In selecting the most economical crane for handling general cargo, the average and maximum weights of the individual pieces of cargo must be taken into consideration. The frequency with which 60-ton lifts are likely to be encountered is exceedingly low, also 20-ton lifts are quite uncommon, so that it would be out of reason to install on any single dock a number of cranes capable of handling such weights. This most popular general-cargo cranes in use at present are from 510 tonscapacity. Fatigue failures of elements of the metalwork of traveling gantry cranes LT62B are observed frequently in operation. Failures as fatigue cracks initiate and propagate in welded joints of the crane bridge and supports in three-four years. Such cranes are used in the forest industry at log yards for transferring full-length and sawn logs to road trains, having a load-fitting capacity of 32 tons. More than 1000 cranes of this type work at the enterprises of the Russian forest industry. The problem was stated to find the weakest elements limiting the cranes fives, predict their fatigue behavior, and give recommendations to the manufacturers for enhancing the fives of the cranes.2. Analysis of the crane operation For the analysis, a traveling gantry crane LT62B installed at log yard in the Yekaterinburg region was chosen. The crane serves two saw mills, creates a log store, and transfers logs to or out of road trains. A road passes along the log store. The saw mills are installed so that the reception sites are under the crane span. A schematic view of the crane is shown in Fig. 1.1350-6307/99/$一see front matter 1999 Elsevier Science Ltd. All rights reserved.PII: S 1 3 5 0一6307(98) 00041一7A series of assumptions may be made after examining the work of cranes:if the monthly removal of logs from the forest exceeds the processing rate, i.e. there is a creation of a log store, the crane expects work, being above the centre of a formed pile with the grab lowered on the pile stack;when processing exceeds the log removal from the forest, the crane expects work above an operational pile close to the saw mill with the grab lowered on the pile;the store of logs varies; the height of the piles is considered to be a maximum;the store variation takes place from the side opposite to the saw mill;the total volume of a processed load is on the average k=1.4 times more than the total volume of removal because of additional transfers.2.1. Removal intensityIt is known that the removal intensity for one year is irregular and cannot be considered as a stationary process. The study of the character of non-stationary flow of road trains at 23 enterprises Sverdlesprom for five years has shown that the monthly removal intensity even for one enterprise essentially varies from year to year. This is explained by the complex of various systematic and random effects which exert an influence on removal: weather conditions, conditions of roads and lorry fleet, etc. All wood brought to the log store should, however, be processed within one year.Therefore, the less possibility of removing wood in the season between spring and autumn, the more intensively the wood removal should be performed in winter. While in winter the removal intensity exceeds the processing considerably, in summer, in most cases, the more full-length logs are processed than are taken out.From the analysis of 118 realizations of removal values observed for one year, it is possible to evaluate the relative removal intensity g(t) as percentages of the annual load turnover. The removal data fisted in Table 1 is considered as expected values for any crane, which can be applied to the estimation of fatigue life, and, particularly, for an inspected crane with which strain measurement was carried out (see later). It would be possible for each crane to take advantage of its load turnover per one month, but to establish these data without special statistical investigation is difficult. Besides, to solve the problem of life prediction a knowledge of future loads is required, which we take as expected values on cranes with similar operation conditions.The distribution of removal value Q(t) per month performed by the relative intensity q(t) is written aswhere Q is the annual load turnover of a log store, A is the maximal designed store of logs in percent of Q. Substituting the value Q, which for the inspected crane equals 400,000 m3 per year, and A=10%, the volumes of loads transferred by the crane are obtained, which are listed in Table 2, with the total volume being 560,000 m3 for one year using K,.2.2. Number of loading blocksThe set of operations such as clamping, hoisting, transferring, lowering, and getting rid of a load can be considered as one operation cycle (loading block) of the crane. As a result to investigations, the operation time of a cycle can be modeled by the normal variable with mean equal to 11.5 min and standard deviation to 1.5 min. unfortunately, this characteristic cannot be simply used for the definition of the number of operation cycles for any work period as the local processing is extremely irregular. Using a total operation time of the crane and evaluations of cycle durations, it is easy to make large errors and increase the number of cycles compared with the real one. Therefore, it is preferred to act as follows.The volume of a unit load can be modeled by a random variable with a distribution function(t) having mean22 m3 and standard deviation 6;一3 m3, with the nominal volume of one pack being 25 m3. Then, knowing the total volume of a processed load for a month or year, it is possible to determine distribution parameters of the number of operation cycles for these periods to take advantage of the methods of renewal theory 1.According to these methods, a random renewal process as shown in Fig. 2 is considered, where the random volume of loads forms a flow of renewals: In renewal theory, realizations of random:，having a distribution function F(t), are understoodas moments of recovery of failed units or request receipts. The value of a processed load:，afterth operation is adopted here as the renewal moment. Let F(t)=Pt. The function F(t) is defined recurrently, Let v(t) be the number of operation cycles for a transferred volume t. In practice, the total volume of a transferred load t is essentially greater than a unit load, and it is useful therefore totake advantage of asymptotic properties of the renewal process. As follows from an appropriatelimit renewal theorem, the random number of cycles v required to transfer the large volume t hasthe normal distribution asymptotically with mean and variance.without dependence on the form of the distribution function月t) of a unit load (the restriction isimposed only on nonlattice of the distribution). Equation (4) using Table 2 for each averaged operation month,function of number of load cycles with parameters m,. and 6,., which normal distribution in Table 3. Figure 3 shows the average numbers of cycles with 95 % confidence intervals. The values of these parametersfor a year are accordingly 12,719 and 420 cycles.3. Strain measurementsIn order to reveal the most loaded elements of the metalwork and to determine a range of stresses, static strain measurements were carried out beforehand. Vertical loading was applied by hoisting measured loads, and skew loading was formed with a tractor winch equipped with a dynamometer. The allocation schemes of the bonded strain gauges are shown in Figs 4 and 5. As was expected, the largest tension stresses in the bridge take place in the bottom chord of the truss (gauge 11-45 MPa). The top chord of the truss is subjected to the largest compression stresses.The local bending stresses caused by the pressure of wheels of the crane trolleys are added to the stresses of the bridge and the load weights. These stresses result in the bottom chord of the I一beam being less compressed than the top one (gauge 17-75 and 10-20 MPa). The other elements of the bridge are less loaded with stresses not exceeding the absolute value 45 MPa. The elements connecting the support with the bridge of the crane are loaded also irregularly. The largest compression stresses take place in the carrying angles of the interior panel; the maximum stresses reach h0 MPa (gauges 8 and 9). The largest tension stresses in the diaphragms and angles of the exterior panel reach 45 MPa (causes 1 and hl.The elements of the crane bridge are subjected, in genera maximum stresses and respond weakly to skew loads. The suhand, are subjected mainly to skew loads.1, to vertical loads pports of the crane gmmg rise to on the other The loading of the metalwork of such a crane, transferring full-length logs, differs from that ofa crane used for general purposes. At first, it involves the load compliance of log packs because ofprogressive detachment from the base. Therefore, the loading increases rather slowly and smoothly.The second characteristic property is the low probability of hoisting with picking up. This is conditioned by the presence of the grab, which means that the fall of the rope from the spreader block is not permitted; the load should always be balanced. The possibility of slack being sufficient to accelerate an electric drive to nominal revolutions is therefore minimal. Thus, the forest traveling gantry cranes are subjected to smaller dynamic stresses than in analogous cranes for general purposes with the same hoisting speed. Usually, when acceleration is smooth, the detachment of a load from the base occurs in 3.5-4.5 s after switching on an electric drive. Significant oscillations of the metalwork are not observed in this case, and stresses smoothly reach maximum values. When a high acceleration with the greatest possible clearance in the joint between spreader andgrab takes place, the tension of the ropes happens 1 s after switching the electric drive on, theclearance in the joint taking up. The revolutions of the electric motors reach the nominal value inO.r0.7 s. The detachment of a load from the base, from the moment of switching electric motorson to the moment of full pull in the ropes takes 3-3.5 s, the tensions in ropes increasing smoothlyto maximum. The stresses in the metalwork of the bridge and supports grow up to maximumvalues in 1-2 s and oscillate about an average within 3.5%.When a rigid load is lifted, the accelerated velocity of loading in the rope hanger and metalworkis practically the same as in case of fast hoisting of a log pack. The metalwork oscillations are characterized by two harmonic processes with periods 0.6 and 2 s, which have been obtained from spectral analysis. The worst case of loading ensues from summation of loading amplitudes so that the maximum excess of dynamic loading above static can be 13-14%.Braking a load, when it is lowered, induces significant oscillation of stress in the metalwork, which can be r7% of static loading. Moving over rail joints of 3 mm height misalignment induces only insignificant stresses. In operation, there are possible cases when loads originating from various types of loading combine. The greatest load is the case when the maximum loads from braking of a load when lowering coincide with braking of the trolley with poorly adjusted brakes.4. Fatigue loading analysisStrain measurement at test points, disposed as shown in Figs 4 and 5, was carried out during the work of the crane and a representative number of stress oscillograms was obtained. Since a common operation cycle duration of the crane has a sufficient scatter with average value 11.5min, to reduce these oscillograms uniformly a filtration was implemented to these signals, and all repeated values, i.e. while the construction was not subjected to dynamic loading and only static loading occurred, were rejected. Three characteristic stress oscillograms (gauge 11) are shown inFig. 6 where the interior sequence of loading for an operation cycle is visible. At first, stresses increase to maximum values when a load is hoisted. After that a load is transferred to the necessary location and stresses oscillate due to the irregular crane movement on rails and over rail joints resulting mostly in skew loads. The lowering of the load causes the decrease of loading and forms half of a basic loading cycle.4.1. Analysis of loading process amplitudes Two terms now should be separated: loading cycle and loading block. The first denotes one distinct oscillation of stresses (closed loop), and the second is for the set of loading cycles during an operation cycle. The rain flow cycle counting method given in Ref. 2 was taken advantage of to carry out the fatigue hysteretic loop analysis for the three weakest elements: (1) angle of the bottom chord(gauge 11), (2) I-beam of the top chord (gauge 17), (3) angle of the support (gauge 8). Statistical evaluation of sample cycle amplitudes by means of the Waybill distribution for these elements has given estimated parameters fisted in Table 4. It should be noted that the histograms of cycle amplitude with nonzero averages were reduced afterwards to equivalent histograms with zero averages.4.2. Numbers of loading cycles During the rain flow cycle counting procedure, the calculation of number of loading cycles for the loading block was also carried out. While processing the oscillograms of one type, a sample number of loading cycles for one block is obtained consisting of integers with minimum and maximum observed values: 24 and 46. The random number of loading cycles vibe can be described by the Poisson distribution with parameter =34.Average numbers of loading blocks via months were obtained earlier, so it is possible to find the appropriate characteristics not only for loading blocks per month, but also for the total number of loading cycles per month or year if the central limit theorem is taken advantage of. Firstly, it is known from probability theory that the addition of k independent Poisson variables gives also a random variable with the Poisson distribution with parameter k,. On the other hand, the Poisson distribution can be well approximated by the normal distribution with average, and variation ,. Secondly, the central limit theorem, roughly speaking, states that the distribution of a large number of terms, independent of the initial distribution asymptotically tends to normal. If the initial distribution of each independent term has a normal distribution, then the average and standard deviation of the total number of loading cycles for one year are equal to 423,096 and 650 accordingly. The values of k are taken as constant averages from Table 3.5. Stress concentration factors and element enduranceThe elements of the crane are jointed by semi-automatic gas welding without preliminary edge preparation and consequent machining. For the inspected elements 1 and 3 having circumferential and edge welds of angles with gusset plates, the effective stress concentration factor for fatigue is given by calculation methods 3, kf=2.r2.9, coinciding with estimates given in the current Russian norm for fatigue of welded elements 4, kf=2.9.The elements of the crane metalwork are made of alloyed steel 09G2S having an endurance limit of 120 MPa and a yield strength of 350 MPa. Then the average values of the endurance limits of the inspected elements 1 and 3 are ES一l=41 MPa. The variation coefficient is taken as 0.1, and the corresponding standard deviation is 6S-、一4.1 MPa.The inspected element 2 is an I-beam pierced by holes for attaching rails to the top flange. The rather large local stresses caused by local bending also promote fatigue damage accumulation. According to tables from 4, the effective stress concentration factor is accepted as kf=1.8, which gives an average value of the endurance limit as ES一l=h7 Map. Using the same variation coiffing dent th e stand arid d emit ion is =6.7 MPa. An average S-N curve, recommended in 4, has the form:with the inflexion point No=5106 and the slope m=4.5 for elements 1 and 3 and m=5.5 for element 2. The possible values of the element endurance limits presented above overlap the ranges of load amplitude with nonzero probability, which means that these elements are subjected to fatigue damage accumulation. Then it is possible to conclude that fatigue calculations for the elements are necessary as well as fatigue fife prediction.6. Life predictionThe study has that some elements of the metalwork are subject to fatigue damage accumulation.To predict fives we shall take advantage of intrinsic fatigue curves, which are detailed in 5and 6. Following the theory of intrinsic fatigue curves, we get lognormal life distribution densities for the inspected elements. The fife averages and standard deviations are fisted in Table 5. The lognormal fife distribution densities are shown in Fig. 7. It is seen from this table that the least fife is for element 3. Recollecting that an average number of load blocks for a year is equal to 12,719, it is clear that the average service fife of the crane before fatigue cracks appear in the welded elements is sufficient: the fife is 8.5 years for element 1, 11.5 years for element 2, and h years for element 3. However, the probability of failure of these elements within three-four years is not small and is in the range 0.09-0.22. These probabilities cannot be neglected, and services of design and maintenance should make efforts to extend the fife of the metalwork without permitting crack initiation and propagation.7. Conclusions The analysis of the crane loading has shown that some elements of the metalwork are subjectedto large dynamic loads, which causes fatigue damage accumulation followed by fatigue failures.The procedure of fatigue hfe prediction proposed in this paper involves tour parts:(1) Analysis of the operation in practice and determination of the loading blocks for some period.(2) Rainflow cycle counting techniques for the calculation of loading cycles for a period of standard operation.(3) Selection of appropriate fatigue data for material.(4) Fatigue fife calculations using the intrinsic fatigue curves approach.The results of this investigation have been confirmed by the cases observed in practice, and the manufacturers have taken a decision about strengthening the fixed elements to extend their fatigue lives.References1 Feller W. An introduction to probabilistic theory and its applications, vol. 2. 3rd ed. Wiley, 1970.2 Rychlik I. International Journal of Fatigue 1987;9:119.3 Piskunov V(i. Finite elements analysis of cranes metalwork. Moscow: Mashinostroyenie, 1991 (in Russian).4 MU RD 50-694-90. Reliability engineering. Probabilistic methods of calculations for fatigue of welded metalworks. Moscow: (iosstandard, 1990 (in Russian).5 Kopnov VA. Fatigue and Fracture of Engineering Materials and Structures 1993;16:1041.6 Kopnov VA. Theoretical and Applied Fracture Mechanics 1997;26:169.编号： 毕业设计(论文)外文翻译（译文）学 院： 机电工程学院 专 业：机械设计制造及其自动化 学生姓名： 林 建 学 号： 1200110415 指导教师单位： 机电工程学院 姓 名： 杨孟杰 职 称： 硕士/未评级 2016年6月8日龙门式起重机金属材料的疲劳强度预测v.a.科普诺夫摘要内在的疲劳曲线应用到龙门式起重机金属材料的疲劳寿命预测问题。起重机，用于在森林工业中，在伐木林场对各种不同的工作条件进行研究，并且做出相应的应变测量。对载重的循环周期进行计算，下雨循环计数技术得到了使用。在一年内这些起重机运作的样本被观察为了得到运作周期的平均数。疲劳失效分析表明，一些元件的故障是自然的系统因素，并且不能被一些随意的原因所解释。1999年Elsevier公司科学有限公司。保留所有权利。关键词：起重机;疲劳评估;应变测量1. 绪论1.1现代起重机的特征和发展趋向随着现代科学技术的迅速发展，工业生产规模的扩大和自动化程度的提高，起重机在现代化生产过程中应用越来越广，作用愈来愈大，对起重机的要求也越来越高。尤其是电子计算机技术的广泛应用，促使了许多跨学科的先进设计方法出现，推动了现代制造技术和检测技术的提高。激烈的国际市场竞争也越来越依赖于技术的竞争。这些都促使起重机的技术性能进入崭新的发展阶段，起重机正经历着一场巨大的变革。 我国正以前所未有的速度进入全球化国际竞争市场，中国的起重机制造业面临着机遇与挑战并存的新形势。因此起重机的不断发展和创新是关键。现根据国内外起重机的新理论、新技术和新动向，结合实例，简要论述现代起重机的特征和发展趋向。1） 重点产品大型化、高速化、耐久化和专用化 由于工业生产规模不断扩大，生产效率日益提高，以及产品生产过程中物料装卸搬运费用所占比例逐渐增加，促使大型或高速起重机的需求量不断增长。起重量越来越大，工作速度越来越高，并对能耗和可靠性提出更高的要求。起重机已成为自动化生产流程中的重要环节。起重机不但要好用，容易维护，操作方便，而且安全性要好，故障要少，平均无故障工作时间要长。可靠性是国际市场产品竞争的焦点，国外许多大公司都制定了可靠性内控标准。我国起重机的性能要赶超世界先进水平，最关键的是要提高可靠性，使起重机具有优异的耐久性、无故障性、维修性和使用经济性。 目前世界上最大的浮游起重机起重量6500t，最大的履带起重机起重量3000t，最大的桥式起重机起重量1200t，自动化立体仓库堆垛起重机最大运行速度达240mmin。 工业生产方式和用户需求的多样性，使专用起重机的市场不断扩大，品种也不断更新，以特有的功能满足特殊的需要，发挥出最佳的效用。冶金专用起重机，防爆、防腐、绝缘起重机和铁路、船舶、车辆专用起重机的功能不断增加，性能不断提高，适应性比以往更强。德国德马格公司研制出一种飞机维修保养专用起重机，在国际市场上打开了销路。这种起重机跨度大，起升高度大，停准精度高。在起重小车下面安装有可伸缩回转的维修平台，可到达飞机任一部位。随着世界核电站的迅速发展，核电站专用起重机也得到相应发展，如反应堆室内的环形桥式起重机在放射性环境中工作，用于起吊压力容器顶盖及堆内构件等危险载荷，要求可靠性高，安全性好，能自动精确定位和缓慢下放物品等，并有多种保护装置和特殊安全装置。2）系列产品模块化、组合化、标准化和实用化许多起重机是成系列成批量的产品，采用系统多目标整体优化方法进行起重机系列设计已成为发展重点，通过全面考虑性能、成本、工 艺、生产管理、制造批量和使用维护等多种因素对系列主参数进行合理匹配，以达到改善整机性能降低制造成本，提高通用化程度，用较少规格数的零部件组成多品种、多规格的系列产品，充分满足用户需求。用模块化设计代替传统的整机设计方法，将起重机上功能基本相同的构件、部件和零件制成有多种用途，有相同联接要素和可互换的标准模块，通过不同模块的组合，形成不同类型和规格的起重机。对起重机进行改进，只需针对某几个模块。设计新型起重机，只需选用不同模块重新进行组合。由于提高了通用化程度，可使单件小批生产的产品改换成具有相当批量的模块生产，实现高效率的专业化生产，降低制造成本。能以较少的模块形式，组合成多品种多规格的起重机，满足市场需求，增加竞争能力。德国德马格公司生产的桥式起重机充分考虑了模块化和组合化，使系列、整机、机构、部件和零件互相之间的参数匹配，能力分布达到最为经济合理的搭配效果。利用起重量与起升速度的乘积为常数的方法使起升机构主要部件达到最大限度的通用。再通过滑轮倍率的变化派生出更多的规格。5125t桥式起重机系列，多种工作级别，只需4种基型的起重小车。该公司开发的标准车轮箱模块系列，上面有多组联接孔，可选装不同型号的驱动单元，可组装成台车，可与金属结构件组合后用作各种桥式、门式起重机，巷道堆垛起重机或其它轨行式起重运输机械的运行机械，其车轮有多种踏面形式可供选用。由于不受基距限制，组合灵活，用途广泛。该公司的端梁标准模块系列已经商品化，与主梁之间采用摩擦环和高强度螺栓的连接方式，提高了互换性和尺寸精度，减少了接合面的加工量。与任一主梁都可快速有效相接。有适用于单梁或双梁两种形式的端梁模块，根据起重量及跨度就可确定出适用的端梁型号。3）通用产品小型化、轻型化、简易化和多样化 有相当批量的起重机是在一般的车间仓库使用，要求并不很高，工作并不十分繁重。如何提高这些起重机的适用性，降低制造成本，是市场竞争能否获胜的关键。考虑综合效益，要求起重机尽量降低外形高度，简化结构，减小自重和轮压，也可使整个建筑物高度下降，建筑结构轻型化，降低造价和使用维护费用。因此电动葫芦桥式起重机和轻型梁式起重机会有更快的发展，并将大部分取代中小吨位一般用途桥式起重机。用户的需求性促进了起重机的多样性。起重机的系列参数范围进一步扩大，功能选择进一步增加，一机多用产品进一步得到发展，以增强应变能力。在一般使用场合采用无线遥控操作的比例也将逐步增多。德国德马格公司经过长期的开发和创新，已形成一个轻型组合式标准起重机系列。整个系列由组合式工字形单梁、悬挂箱形单梁、角形小车箱形单梁和箱形双梁多个品种组成。主梁与端梁相接共有15种形式，可适合不同建筑物和不同起吊物的要求。每种规格起重机都有三种单速及三种双速可供任意选择。操纵方式有地面手电门自行移动、手电门随小车移动、手电门固定、远红外或无线电遥控、司机室固定、司机室随小车移动、司机室自行移动等7种选择，外加不同的导电形式，不同的电控形式，通过不同的组合，可搭配成百上千种起重机，充分满足用户不同的需求。这种起重机的另一最大优点是轻型化，与国内产品相比较，起重量32t，跨度25.5m，国内双梁桥式起重机自重为46.4t，电动葫芦桥式起重机自重为28.3t，而德马格电动葫芦桥式起重机的自重只有18.5t，比国内产品分别轻60和35。1.2 起重机的类型起重机可分为四类：高架移动起重机、动臂起重机、桥式或门式起重机、悬臂吊车。高架移动起重机由横梁和空中吊运装置组成。横梁靠固定道轨支承，并且可以在轨上来回移动。空中吊运装置由提升装置和其他装置组成，可以从横梁的一端运动到另一端。横梁和与之相连的框架统称为桥。这些的起重机囊括了起重量从2吨到400吨，跨度从20英尺到150英尺的各种类型。根据目的不同,在机舱工作的起重机常在桥或空中吊运装置进行控制,其他情况控制装置常在地面。当两个空中吊运装置安装完毕，他们就能在同一道轨上并行或上下交错的并行，以确保每个空中吊运装置都能在整个横梁上移动。动臂起重机：动臂起重机有能在它的外侧提升重物的倾斜动臂。动臂通过绳索或其他方式连接到垂直的框架上。动臂可以是定长或者可伸缩的。起重机可以是固定式或移动式。这一类的起重机包括：移动和履带起重机,建筑商,码头起重机、塔式起重机和可移动的安装在高台子,井架,浮筒和驳船上的起重机。起重能力不同从1/2吨到300吨不等,动臂可伸展范围从几英尺到150英尺。需要在船厂、港口处理重型机械和设备的起重机经常安装在驳船。桥式起重机：桥式起重机的横梁通过道轨连接在垂直支架，可以在固定的道轨上移动。重物被空中吊运装置提升，并且能从桥的一端移动到另一端。这类起重机能提升桥覆盖范围的所有重物。当需要提升大吨位的货物时，轨道通常选用宽或窄的铁轨。在桥上安装有一平衡物，它可以在吊运装置上方的轨道上，独立运动。它用来平衡起重机的力矩。悬臂起重机：悬臂起重机由水平的横梁和垂直的支架组成。水平的横梁称为悬臂。悬臂可以是固定的，也可以是能够以支架作为轴线在水平面内转动的。提升装置通过滑轨与悬臂相连。提升和滑移的机构常安装在悬臂的后方。虽然这类的起重机可以是固定的，也可以是可移动的，但那些大型的都是固定的。提升重物大小，重量以及可延伸范围受到宽度的限制。当用于船舶起吊时，轻型的起重机常在动臂起重机滑轨上安装有辅助提升装置。主要的提升机构包括两个即可独立运动也可同步运动的绞盘。典型的舾装起重机是250吨，悬臂延展量180英尺，垂直提升高度200英尺。码头吊车：任何安置在码头上的起重机都可成为码头起重机，特别是指那些用于码头与船舶间货物移运的起重机，它也可以称为货物起重机，（货物起重机的含义广泛），因为它属于船舶货物起重机械的一部分。因为船舶舱口的位置不定，所以绝大多数的码头起重机必须能在码头上移动，通常它们被安装在铁轨上。码头起重机的其它要求包括悬臂足够水平，吊绳长度足够以便搬移货物到船上指定的位置，操作上的高效与经济。这类码头起重机通常是指有一个或者两个动力机构的桥式或悬臂式起重机。他们常被安在码头仓库屋顶位置。悬臂以支架为轴转动，从而达到吊运的目的。支架上连接有倾斜的起重臂或悬臂。在通常的货物吊运中，必须有开阔的视野以确定放置位置，但，在这点上，码头大吨位吊运却与之相反。货物形状，体积，重量的多变性排除使用提升机和传送机的可能性，同时，货物需要在分派的地点分堆有次序的码放，让在码头使用运输机成为不可能。悬臂起重机成为码头起重机的原因之一是它有一个与支架成90且可以在平面内转动的悬臂。然而，它有一个重大的缺点：当悬臂水平转动时，悬挂在悬臂上的货物会随之缓慢提升。只有，当吊杆位于较低位置时，货物提升相同的高度。显然，这意味着能量的损失和一个本不需要的用于驱动摆动装置的大功率马达。为了弥补这一缺陷，一类有着独特设计的起重机迅速发展，它被称为水平起重机，目前，它已经被广泛运用于码头起重。这类起重机有一个补偿齿轮组，它能使货物在同一水平面内运动，而无需考虑动臂摆动引起的提升。当选择用于常见货物吊运的经济性时，单一货物最大和平均起重量是必须考虑的因素。如果，60吨位的起吊频率极低，20吨位的起吊也非常少，那么就没有理由购置这一吨位的起重机。目前，最常用的起重机起重量为5到10吨。频繁观测龙门式起重机LT62B在运作时金属元件疲劳失效。引起疲劳裂纹的故障沿着起重机的桥梁焊接接头进行传播，并且能够支撑三到四年。这种起重机在森林工业的伐木林场被广泛使用，用来转移完整长度的原木和锯木到铁路的火车上，有一次装载30吨货物的能力。 这种类型的起重机大约1000台以上工作在俄罗斯森林工业的企业中。限制起重机寿命的问题即最弱的要素被正式找到之后，预测其疲劳强度，并给制造商建议，以提高起重机的寿命。2.起重机运行分析为了分析，在叶卡特琳堡地区的林场码头选中了一台被安装在叶卡特琳堡地区的林场码头的龙门式起重机LT62B， 这台起重机能够供应两个伐木厂建立存储仓库，并且能转运木头到铁路的火车上，这条铁路通过存储仓库。这些设备的安装就是为了这个转货地点在起重机的跨度范围之内。一个起重机示意图显示在图1中 。 1350-6307/99 /元，看到前面的问题。 1999年Elsevier公司科学有限公司保留所有权利。 PH:S1350-6307(98)00041-7V.A.Kopnov|机械故障分析6（1999）131-141图1起重机简图检查起重机的工作之后，一系列的假设可能会作出： 如果每月从森林移动的原木超过加工率，即是有一个原木存储的仓库，这个起重机期待的工作，也只是在原木加工的实际堆数在所供给原木数量的中心线以下；当处理超过原木从森林运出的速度时，起重机的工作需要在的大量的木材之上进行操作，相当于在大量的木材上这个锯木厂赚取的很少；原木不同的仓库;大量的木材的高度被认为是最高的; 仓库的变化，取替了一侧对面的锯轧机; 装载进程中总量是平均为K=1.4倍大于移动总量由于额外的转移。2.1 搬运强度据了解，每年的搬运强度是不规律的，不能被视为一个平稳过程。非平稳流动的道路列车的性质在23家企业中已经研究5年的时间，结果已经表明在年复一年中，对于每个企业来说，每个月的搬运强度都是不同的。这是解释复杂的各种系统和随机效应，对搬运施加的影响：天气条件，道路条件和货车车队等，所有木材被运送到存储仓库的木材，在一年内应该被处理。 因此，在春季和秋季搬运木头的可能性越来越小，冬天搬运的可能性越来越大，然而在冬天搬运强度强于预想的，在夏天的情况下，更多足够长的木材就地被处理的比运出去的要多的多。V.A.Kopnov|机械故障分析6（1999）131-141表1搬运强度（%）表2转移储存量通过一年的观察，从118各搬运值的观察所了解到的数据进行分析，并且有可能评价相关的搬运强度（吨）参考年度的装载量的百分比。该搬运的数据被记录在起重机预期值表1中，它可以被应用到估计疲劳寿命，尤其是为检查起重机应变测量（见稍后） 。将有可能为每个起重机，每一个月所负荷的载重量，建立这些数据，无需特别困难的统计调查。此外，为了解决这个问题的寿命预测的知识是未来的荷载要求， 在类似的操作条件下，我们采取起重机预期值。每月搬运价值的分布Q（t） ，被相对强度q（t）表示为 其中Q是每年的装载量的记录存储，是设计的最大存储原木值Q以百分比计算，其中为考察起重机等于40.0万立方米每年， 和容积载重搬运为10 的起重机，得到的数据列在表2 中，总量56000立方米每年，用K表示。2.2 .装载木块的数量这个运行装置，如夹紧，吊装，转移，降低，和释放负载可被视为起重机的一个运行周期（加载块）。参照这个调查结果，以操作时间为一个周期，作为范本，由正常变量与平均值11.5分相等等，标准差为1.5分钟。不幸的是，这个特点不能简单地用于定义运作周期的数目，任何工作期间的载重加工是非常不规则。使用运行时间的起重机和评价周期时间，与实际增加一个数量的周期比，很容易得出比较大
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