外文翻譯--起重機(jī)介紹

1 附 錄 外文文獻(xiàn)原文： The Introduction of cranes A crane is defined as a mechanism for lifting and lowering loads with a hoisting mechanism Shapiro, 1991. Cranes are the most useful and versatile piece of equipment on a vast majority of construction projects. They vary widely in configuration, capacity, mode of operation, intensity of utilization and cost. On a large project, a contractor may have an assortment of cranes for different purposes. Small mobile hydraulic cranes may be used for unloading materials from trucks and for small concrete placement operations, while larger crawler and tower cranes may be used for the erection and removal of forms, the installation of steel reinforcement, the placement of concrete, and the erection of structural steel and precast concrete beams. On many construction sites a crane is needed to lift loads such as concrete skips, reinforcement, and formwork. As the lifting needs of the construction industry have increased and diversified, a large number of general and special purpose cranes have been designed and manufactured. These cranes fall into two categories, those employed in industry and those employed in construction. The most common types of cranes used in construction are mobile, tower, and derrick cranes. 1. Mobile cranes A mobile crane is a crane capable of moving under its own power without being restricted to predetermined travel. Mobility is provided by mounting or integrating the crane with trucks or all terrain carriers or rough terrain carriers or by providing crawlers. Truck-mounted cranes have the advantage of being able to move under their own power to the construction site. Additionally, mobile cranes can move about the site, and are often able to do the work of several stationary units. Mobile cranes are used for loading, mounting, carrying large loads and for work performed in the presence of obstacles of various kinds such as power lines and similar technological installations. The essential difficulty is here the swinging of the payload which occurs during working motion and also after the work is completed. This applies particularly to the slewing motion of the crane chassis, for which relatively large angular accelerations and negative accelerations of the chassis are characteristic. Inertia forces together with the centrifugal force and the Carioles force cause the payload to swing as a spherical pendulum. Proper control of the slewing motion of the crane serving to transport a payload to the defined point with simultaneous minimization of the swings when the working motion is finished plays an important role in the model. 2 Modern mobile cranes include the drive and the control systems. Control systems send the feedback signals from the mechanical structure to the drive systems. In general, they are closed chain mechanisms with flexible members 1. Rotation, load and boom hoisting are fundamental motions the mobile crane. During transfer of the load as well as at the end of the motion process, the motor drive forces, the structure inertia forces, the wind forces and the load inertia forces can result in substantial, undesired oscillations in crane. The structure inertia forces and the load inertia forces can be evaluated with numerical methods, such as the finite element method. However, the drive forces are difficult to describe. During start-up and breaking the output forces of the drive system significantly fluctuate. To reduce the speed variations during start-up and braking the controlled motor must produce torque other than constant 2,3, which in turn affects the performance of the crane. Modern mobile cranes that have been built till today have oft a maximal lifting capacity of 3000 tons and incorporate long booms. Crane structure and drive system must be safe, functionary and as light as possible. For economic and time reasons it is impossible to build prototypes for great cranes. Therefore, it is desirable to determinate the crane dynamic responses with the theoretical calculation. Several published articles on the dynamic responses of mobile crane are available in the open literature. In the mid-seventies Peeken et al. 4 have studied the dynamic forces of a mobile crane during rotation of the boom, using very few degrees of freedom for the dynamic equations and very simply spring-mass system for the crane structure. Later Maczynski et al. 5 studied the load swing of a mobile crane with a four mass-model for the crane structure. Posiadala et al. 6 have researched the lifted load motion with consideration for the change of rotating, booming and load hoisting. However, only the kinematics were studied. Later the influence of the flexibility of the support system on the load motion was investigated by the same author 7. Recently, Kilicaslan et al. 1 have studied the characteristics of a mobile crane using a flexible multibody dynamics approach. Towarek 16 has concentrated the influence of flexible soil foundation on the dynamic stability of the boom crane. The drive forces, however, in all of those studies were presented by using so called the method of kinematics forcing 6 with assumed velocities or accelerations. In practice this assumption could not comply with the motion during start-up and braking. A detailed and accurate model of a mobile crane can be achieved with the finite element method. Using non-linear finite element theory Gunthner and Kleeberger 9 studied the dynamic responses of lattice mobile cranes. About 2754 beam elements and 80 truss elements were used for modeling of the lattice-boom structure. On this basis a efficient software for mobile crane calculationNODYA has been developed. However, the influences of the drive systems must be determined by measuring on hoisting of the load 10, or rotating of the crane 11. This is neither efficient nor convenient for computer 3 simulation of arbitrary crane motions. Studies on the problem of control for the dynamic response of rotary crane are also available. Sato et al. 14, derived a control law so that the transfer a load to a desired position will take place that at the end of the transfer of the swing of the load decays as soon as possible. Gustafsson 15 described a feedback control system for a rotary crane to move a cargo without oscillations and correctly align the cargo at the final position. However, only rigid bodies and elastic joint between the boom and the jib in those studies were considered. The dynamic response of the crane, for this reason, will be global. To improve this situation, a new method for dynamic calculation of mobile cranes will be presented in this paper. In this method, the flexible multibody model of the steel structure will be coupled with the model of the drive systems. In that way the elastic deformation, the rigid body motion of the structure and the dynamic behavior of the drive system can be determined with one integrated model. In this paper this method will be called complete dynamic calculation for driven “mechanism”. On the basis of flexible multibody theory and the Lagrangian equations, the system equations for complete dynamic calculation will be established. The drive- and control system will be described as differential equations. The complete system leads to a non-linear system of differential equations. The calculation method has been realized for a hydraulic mobile crane. In addition to the structural elements, the mathematical modeling of hydraulic drive- and control systems is decried. The simulations of crane rotations for arbitrary working conditions will be carried out. As result, a more exact representation of dynamic behavior not only for the crane structure, but also for the drive system will be achieved. Based on the results of these simulations the influences of the accelerations, velocities during start-up and braking of crane motions will be discussed. 2. Tower cranes The tower crane is a crane with a fixed vertical mast that is topped by a rotating boom and equipped with a winch for hoisting and lowering loads (Dickie, 990). Tower cranes are designed for situations which require operation in congested areas. Congestion may arise from the nature of the site or from the nature of the construction project. There is no limitation to the height of a high-rise building that can be constructed with a tower crane. The very high line speeds, up to 304.8 mrmin, available with some models yield good production rates at any height. They provide a considerable horizontal working radius, yet require a small work space on the ground (Chalabi, 1989). Some machines can also operate in winds of up to 72.4 km/h, which is far above mobile crane wind limits. The tower cranes are more economical only for longer term construction operations and higher lifting frequencies. This is because of the fairly extensive planning needed for installation, together with the transportation, erection and dismantling costs. 3. Derrick cranes 4 A derrick is a device for raising, lowering, and/or moving loads laterally. The simplest form of the derrick is called a Chicago boom and is usually installed by being mounted to building columns or frames during or after construction (Shapiro and Shapiro, 1991).This derrick arrangement. (i.e., Chicago boom) becomes a guy derrick when it is mounted to a mast and a stiff leg derrick when it is fixed to a frame. The selection of cranes is a central element of the life cycle of the project. Cranes must be selected to satisfy the requirements of the job. An appropriately selected crane contributes to the efficiency, timeliness, and profitability of the project. If the correct crane selection and configuration is not made, cost and safety implications might be created (Hanna, 1994). Decision to select a particular crane depends on many input parameters such as site conditions, cost, safety, and their variability. Many of these parameters are qualitative, and subjective judgments implicit in these terms cannot be directly incorporated into the classical decision making process. One way of selecting crane is achieved using fuzzy logic approach. Cranes are not merely the largest, the most conspicuous, and the most representative equipment of construction sites but also, at various stages of the project, a real “bottleneck” that slows the pace of the construction process. Although the crane can be found standing idle in many instances, yet once it is involved in a particular task ,it becomes an indispensable link in the activity chain, forcing at least two crews(in the loading and the unloading zones) to wait for the service. As analyzed in previous publications 6-8 it is feasible to automate (or, rather, semi-automate) crane navigation in order to achieve higher productivity, better economy, and safe operation. It is necessary to focus on the technical aspects of the conversion of existing crane into large semi-automatic manipulators. By mainly external devices mounted on the crane, it becomes capable of learning, memorizing, and autonomously navigation to reprogrammed targets or through prt aught paths. The following sections describe various facets of crane automation: First, the necessary components and their technical characteristics are reviewed, along with some selection criteria. These are followed by installation and integration of the new components into an existing crane. Next, the Man Machine Interface (MMI) is presented with the different modes of operation it provides. Finally, the highlights of a set of controlled tests are reported followed by conclusions and recommendations. Manual versus automatic operation: The three major degrees of freedom of common tower cranes are illustrated in the picture. In some cases , the crane is mounted on tracks , which provide a fourth degree of freedom , while in other cases the tower is “telescope” or extendable , and /or the “jib” can be raised to a diagonal position. Since these additional degrees of freedom are not used routinely during normal operation but rather are fixed in a certain position for long periods (days or weeks), they are not included in the routine automatic mode of operation, although their position must be “known” to the control system. 5 外文文獻(xiàn)中文翻譯： 起重機(jī)介紹 起重機(jī)是用來舉升機(jī)構(gòu)、抬起或放下貨 物的器械。在大多數(shù)的建設(shè)工程中，起重機(jī)是最有用、功能最多的器械。它們因結(jié)構(gòu)、容量、操作模式、使用強(qiáng)度和費(fèi)用的不同而不同。在一個(gè)大的工程項(xiàng)目上，一個(gè)承包商可以因?yàn)椴煌睦媚康亩褂枚喾N起重機(jī)。小的液壓移動(dòng)式起重機(jī)可以用來從卡車上卸下材料，處理小而具體的物體的安置，然而較大的爬式或塔式起重機(jī)可以用來豎立并移動(dòng)框架，安置加強(qiáng)的鋼鐵，放置混凝土，豎起鋼筋結(jié)構(gòu)和預(yù)制混凝土橫梁。 在一些建設(shè)地點(diǎn)，一臺(tái)起重機(jī)是用來提升重物的，例如：混凝土的裝料車、加強(qiáng)部分和模殼。隨著建筑行業(yè)的提升要求不斷增加并且變化多樣，大量的具有綜 合的和特殊性能的起重機(jī)被設(shè)計(jì)和制造出來。這些起重機(jī)被分成兩類：工業(yè)用起重機(jī)和建筑用起重機(jī)。用于建筑業(yè)的最普通型式的起重機(jī)是移動(dòng)式、塔式和架式起重機(jī)。 1. 移動(dòng)式起重機(jī) 一臺(tái)移動(dòng)式起重機(jī)是一個(gè)不被局限于預(yù)先確定的軌道，在自身動(dòng)力的驅(qū)動(dòng)下具有運(yùn)動(dòng)能力的起重機(jī)。將起重機(jī)與卡車，甚至所有地帶的運(yùn)輸工具甚至粗糙地帶的運(yùn)輸工具，更甚至借助于所提供的爬行工具，起重機(jī)的就有運(yùn)動(dòng)的可能。車載起重機(jī)具有在它們自己的動(dòng)力驅(qū)動(dòng)下能夠移動(dòng)至建筑地點(diǎn)中的任何地方的優(yōu)勢。此外，移動(dòng)式起重機(jī)可以在場所內(nèi)移動(dòng)，經(jīng)常能夠處理與提升一些靜止部 件的工作。 移動(dòng)式起重機(jī)用來裝載、安裝、搬運(yùn)大負(fù)荷，也常用于在各種各樣的障礙中，例如：力量線和相似的科技安裝。在這兒必不可少的困難是當(dāng)工作過程中和工作完成之后有效載荷的擺動(dòng)，相關(guān)的大的角速度和底座的負(fù)的速度是其特有的。慣性力，伴著離心力和科里奧利力引起載物像一個(gè)球形鐘擺一樣旋轉(zhuǎn)。當(dāng)工作行為結(jié)束時(shí)，對(duì)同時(shí)用于將貨物輸送到限定地點(diǎn)的起重機(jī)的旋轉(zhuǎn)動(dòng)作進(jìn)行適當(dāng)?shù)南拗?，在模型中起著很重要的作用?現(xiàn)代的移動(dòng)式起重機(jī)包括驅(qū)動(dòng)和控制系統(tǒng)。控制系統(tǒng)把來自機(jī)械結(jié)構(gòu)的反饋信號(hào)傳送到驅(qū)動(dòng)系統(tǒng)，大體上，它們是由柔性元件組成的閉鏈機(jī) 械系。 旋轉(zhuǎn)、負(fù)荷和提升是移動(dòng)式起重機(jī)的基礎(chǔ)動(dòng)作，在傳送重物的過程中與運(yùn)作過程一樣，馬達(dá)的驅(qū)動(dòng)力、結(jié)構(gòu)內(nèi)應(yīng)力、風(fēng)力和貨物的內(nèi)力可以導(dǎo)致起重機(jī)產(chǎn)生一定的不希望得到的搖晃。結(jié)構(gòu)內(nèi)應(yīng)力和貨物內(nèi)應(yīng)力可以用數(shù)學(xué)方法進(jìn)行估價(jià)，例如有限元的方法。無論怎樣，驅(qū)動(dòng)力是很難描述的。在起動(dòng)和制動(dòng)的過程中，驅(qū)動(dòng)系統(tǒng)的外力起 6 伏變化很大。為了減小起動(dòng)和制動(dòng)中速度的變化，可控制的馬達(dá)必須產(chǎn)生可變化的力矩，來影響起重機(jī)的運(yùn)作。 現(xiàn)代的移動(dòng)式起重機(jī)直到今天還在鑄造，常常有 3000 噸的舉重能力，而且經(jīng)久不衰。起重機(jī)的結(jié)構(gòu)和傳動(dòng)系統(tǒng)必須是安全、 有效和盡量輕巧的。因?yàn)榻?jīng)濟(jì)和時(shí)間的原因，對(duì)于大的起重機(jī)不可能建造出其原型，所以，人們希望利用理論上的計(jì)算來確定起重機(jī)的電動(dòng)反應(yīng)。 在開放的文化中，一些反映移動(dòng)式起重機(jī)動(dòng)態(tài)影響的已發(fā)表文章是可以找到的。其中 70 歲的 Peeken 通過在動(dòng)態(tài)方程中利用很少的自由度，并在起重機(jī)結(jié)構(gòu)中利用非常簡單的彈簧阻尼系統(tǒng)，研究了在懸臂旋轉(zhuǎn)中一臺(tái)移動(dòng)式起重機(jī)的動(dòng)態(tài)力學(xué)。之后，Maczynski 研究了起重結(jié)構(gòu)上有四塊模型的移動(dòng)式起重機(jī)的載荷搖擺問題。 Posiadala考慮到旋轉(zhuǎn)、裝載和載荷提升的變化而研究了被提升的載荷的運(yùn)動(dòng)。無論怎 樣，只有運(yùn)動(dòng)學(xué)被研究了。稍后，相同的作家調(diào)查了在載荷運(yùn)行中的支持系統(tǒng)的彈性影響。最近， Kilicaslan 利用柔性綜合動(dòng)態(tài)方法研究了移動(dòng)式起重機(jī)的特性。 Towarek 把研究彈性基壤的影響集中在懸臂式起重機(jī)的動(dòng)態(tài)穩(wěn)定性上。在這些研究中，通過利用所謂帶有假定速度和加速度的運(yùn)動(dòng)力學(xué)的方法，驅(qū)動(dòng)力無論怎樣都有所出現(xiàn)。在實(shí)踐中，這種假想無法和運(yùn)行中的起動(dòng)和制動(dòng)相符合。 利用有限元的方法，一個(gè)詳細(xì)且正確的移動(dòng)式起重機(jī)的模型是可以實(shí)現(xiàn)的。利用非線性有限元理論， Gunthner 和 Kleeberger 研究了移動(dòng)式起重機(jī)的 動(dòng)態(tài)影響，在網(wǎng)格結(jié)構(gòu)中，大約 2754 個(gè)光線元素和 80 個(gè)構(gòu)架元素被用到。在此基礎(chǔ)上，一個(gè)有效的關(guān)于移動(dòng)式起重機(jī)計(jì)算的有效軟件 NODYA 被發(fā)明出來。無論如何，通過衡量載荷的提升量或起重機(jī)的旋轉(zhuǎn)，驅(qū)動(dòng)系統(tǒng)的影響必須要考慮到。這對(duì)于起重機(jī)多種運(yùn)動(dòng)的計(jì)算機(jī)模擬來說，既不很有效也不方便。 對(duì)于旋轉(zhuǎn)起重機(jī)動(dòng)態(tài)影響的控制的問題研究是有效的。 Sato 讓那個(gè)在載荷搖擺轉(zhuǎn)換末尾可將重物傳遞到所渴望的位置的控制理論盡快的衰退。 Gustafsson 為了移動(dòng)貨物時(shí)沒有振動(dòng)并且正確地在最后位置排列貨物，描述了一個(gè)旋轉(zhuǎn)起重機(jī)的反饋控制系統(tǒng) 。然而，在研究中，只有在懸臂和絞點(diǎn)中的堅(jiān)硬的固體和彈性節(jié)點(diǎn)被考慮到了。因?yàn)檫@個(gè)原因，所以起重機(jī)的動(dòng)態(tài)影響是廣泛存在的。 為了改變這種狀況，關(guān)于移動(dòng)式起重機(jī)的動(dòng)態(tài)計(jì)算的一種新的方法將會(huì)出現(xiàn)。在這種方法中，鋼鐵結(jié)構(gòu)的彈性綜合模型將會(huì)同驅(qū)動(dòng)系統(tǒng)的模型一起出現(xiàn)。在那種方法下，用一個(gè)獨(dú)立