毕业论文设计设计--十吨位桥式起重机大车运行机构设计.doc

毕业设计（论文）相关资料题目：十吨位桥式起重机大车运行机构设计 目 录一、毕业设计（论文）开题报告二、毕业设计（论文）外文资料翻译及原文三、学生“毕业论文（论文）计划、进度、检查及落实表”四、实习鉴定表无锡太湖学院毕业设计（论文）开题报告题目：十吨位桥式起重机大车运行机构设计 信机 系 机械工程及自动 专业学 号： 0923087 学生姓名： 叶宏城 指导教师： 陈炎冬 （职称：讲师 ） （职称： ）2012年11月25日 课题来源生产实践需求科学依据（包括课题的科学意义；国内外研究概况、水平和发展趋势；应用前景等）1 课题的科学意义桥式起重机广泛地应用在室内外仓库、厂房、码头和露天贮料场等处。二十世纪以来，由于钢铁、机械制造业和铁路、港口及交通运输业的的发展，促进了起重运输机械的发展。对起重运输机械的性能也提出了更高的要求。现代起重运输机械担当着繁重的物料搬运任务，是工厂、铁路、港口及其他部门实现物料搬运机械化的关键。2 国内外研究概况、水平和发展趋势 起重机作为一种古老的机械，时至今日，在其承载结构、驱动机构、取物装置、控制系统及安全装置等各方面都有了很大的发展，其设计理论、制造工艺、检测手段等都逐渐趋于完善和规范化，并已经成为一种较完善的机械。但由于生产发展提出新的使用要求，起重机的种类、形式也需要相应地发展和创新，性能也需要不断变化与究善。由于现代化设计方法的建立和计算机辅助设计等现代设计手段的应用，使起重机设计思维观念和方法有了进一步的更新，其它技术领域和相邻工业部门不断取得的新科技成果在起重机上的渗透、推广应用等，更使起重机的各方面不断地丰富更新。因此，起重机面向现代化、智慧化、更安全可靠方便的方向发展。3 应用现状及其前景加入世贸组织后，虽然国内市场(特别是配套件)将受到较大冲击，但同时也给我们带来新技术的应用，使国内主机和配套件企业更清晰认识到差距，更多地了解国产产品存在的致命问题，必将引导主机和配套件企业的技术创新和技术进步。随着工程机械产品近十年来随着技术的引进、消化、吸收，有了长足的进步，产品性能、可靠性、外观都有较大幅度的提高，但同国外工程机械比较来看，还存在较大差距，就工程起重机而言，今后的发展主要表现在如下几个方面：（1）整机性能，由于先进技术和新材料的应用,同种型号的产品，整机重量要轻20%左右。随着结构分析应用和先进设备的使用,结构形式更加合理（2）高性能、高可靠性的配套件,选择余地大、适应性好,性能得到充分发挥（3）电液比例控制系统和智能控制显示系统的推广应用（4）操作更方便、舒适、安全、保护装置更加完善（5）向吊重量大、起升高度、幅度更大的大吨位方向发展。研究内容十吨位桥式起重机大车运行机构设计 确定机构传动方案 选择电动机，并验算电动机的发热功率条件 选择减速器，制动器，联轴器 端梁的设计 运用CAD绘制装配图零件图撰写毕业设计论文 拟采取的研究方法、技术路线、实验方案及可行性分析 去实习工厂实地研究学习，查阅桥式起重机的相关资料，分析总结。按照机械设计的相关要求按步骤进行设计和验算。明确设计要求，调查研究，收集设计资料，绘出零件图，装配图。按照步骤，实验方案可行。 研究计划及预期成果研究计划：2012年11月12日-2012年12月2日：教师下达毕业设计任务，学生初步阅读资料，完成毕业设计开题报告。2013年1月21日-2013年3月1日：指导毕业实习。2013年3月4日-2013年3月15日：确定总设计方案。2013年3月18日-2013年3月22日：总体设计（包括参数计算及结构分析计算）。2013年3月25日-2013年4月5日：总体设计（完成参数计算及结构分析计算后绘制草图；装配图）。2013年4月8日-2013年4月26日：零件设计。2013年4月29日-2013年5月25日：毕业论文说明书撰写和修改工作。预期成果：认识了解桥式起重机的相关知识了解和工作方式。设计出10吨位桥式起重机的大车部分。完成毕业设计论文和CAD制图。特色或创新之处对桥式起重机进行全面的了解，分析设计桥式起重机的大车机构已具备的条件和尚需解决的问题我已学习机械数控专业三年之久，掌握了一些这专业的部分知识，老师也给了一些参照资料，可以进行这方面的研究。尚需解决的问题：（1）车轮的计算及车轮的设计对各部件之间连接方法和传动方式的选择。（2）进给部件的强度刚度校核需要对进给部件的强度和刚度有保证，满足工作时的受力要求，需要进行校核计算。指导教师意见 指导教师签名：年 月 日教研室（学科组、研究所）意见 教研室主任签名： 年 月 日系意见 主管领导签名： 年 月 日外文资料翻译及原文英文原文：Fatigue life prediction of the metalwork of a travelling gantrycraneAbstractIntrinsic 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. Introduction 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beambeing 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)