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高空作业升降机的动态特征和分析
论文提出
学院由
艾琳·埃尔南德斯
乔治·伍德鲁夫机械工程学院
佐治亚理工学院2012年12月
概要
空中升降机用于将人和物料提升到高度。有不同类型的航空电梯,具有极大不同的动力学特征。因此,对空中升降机进行新的分类,并通过运动学来组织。使用空中升降机时会发生许多事故。对这些危险的空中电梯和当前解决方案进行了评估,以了解事故的原因。一些重大事故是由于启动Z划升降机的弹性动力学和灵活性,例如振荡和翻转。测试了全尺寸电梯的振荡,以确定不同配置中的等效性。仿真并分析了非中心和超中心配置的机器运动引起的关节运动诱发振荡。使用形状来实现机械诱导振荡的减少。提示超稳定裕度用于模拟和分析非超中心和超中心配置的稳定性。平台增加对提升稳定性的影响也进行了分析。本论文的结果是对航空升降机的分类,包括其危害和减少这些危害的方法,对全尺寸aeria“升降机的动态响应的实验验证”,“双臂”的全动态翻转预测模型通过在关节和现实的速度分布中应用灵活性来阐明空中举升,以及详细研究双臂铰接升降机的动力学。
有很多方法可以将人送到很高的高度上去工作,例如建筑物,树木,飞机或其他高层建筑。在许多情况下,高空升降机被用来提供所需的高度和工作环境。高空作业升降机,像图1中所示的,提供了许多好处给那些需要升高工作平台的用户。
图1
从这些事实统计可以推断有两个主要问题。第一个问题是如何减少当使用升降机高空作业时发生的死亡事故。因此,有必要确定高空升降机最常见的危害以及这些危害发生的原因。第二个问题是了解不同的高空作业升降机,其各自的危害和减少这些危害的方法。在确定如何减少事故的发生时,一定要了解不同的高空作业车的性能好坏,考虑解决高空作业车的开发应用也是非常重要的。
高空作业升降机有着广泛应用,然而,所有这些应用,都是用来将人定位在高空中的。不同的机制执行不同的升降运动,区分不同类型的高空作业升降机是运用到它的运动学结构。区别架空缆车首要因素是其运动的方向性:是有垂直和垂直、水平之分的,如图2所示,垂直升降机使用:垂直桅杆和滑轮系统、垂直运动。水平运动:伸缩式,关节和伸缩关节。区分空中缆车的主要方式是通过自己的能力升高和带动地面而升高。
图2
高空作业的基础依赖于提高流动性,驾驶室驱动电源驱动升降机驱动。图3(a)是驾驶室升降机基座的一个例子。如果电梯有一个骨骼结构为基础或车载,那么高空作业无法驱动而升高,一种不动的高空升降用骨架基的例子示于图3(b)。
图3(a) 图3(b)
使用架空缆车并不取决于其运动的方向性。这取决于预期的工作环境, 两种不同的工作环境时使用空中缆车分别为室内和室外环境。室内环境限制电源,如电动,手动,电池。有时,使用天然气或柴油户外电力或电池室内的混合体。室外环境并不像室内; 因此,所有电源都可以使用。适用于所有高空作业升降机或其他选项。
垂直升降机分为三部分:剪刀式升降机,桅杆垂直升降机,滑轮式升降机。剪刀式升降机有其独特的结构,也就是多个剪刀缩回来降低高度和增加高度,如图4所示。
图4
垂直桅杆升降机有多个部分,互相搭配使用,或向上滑动相互对抗,以增加相等的高度。垂直桅杆升降机的一个例子示于图5。即剪刀式升降机和垂直桅杆升降机具有移动性选择而升高。
图5
滑轮升降机使用通用滑轮系统来提升工作平台,目前,唯一已知滑轮升降机可具有骨架结构的基体位置。滑轮电梯不能移动而升高,因为它有一个骨架结构的基础上,如示于图6。
图6
所有的垂直升降机,可在户外使用。由于小体和垂直升降机的脚印,它们也都可以在室内使用,只要它们不是天然气或柴油动力。
纵向和横向缆车就包括:阐明升降机,伸缩式升降机,以及伸缩关节升降机。所有的垂直和水平运动的空中缆车通过转动,表示为红色虚线在图2实现提升(B)。一个垂直和水平的高空升降的起重臂通常被称为高空升降臂。此外,垂直和水平运动架空升降机旋转在基部以提供在所有方向上的运动。图7(a)示出了在周围架空升降机通常称为摆运动的垂直轴的底座的旋转。图7(b)示出了周围的架空升降机通常被称为俯仰运动,这是枢转的吊臂结果的水平轴的旋转。
图7(a) 图7(b)
(注:图中Base:基体,Boom:激增)
阐明高空作业车有两个或两个以上铰链臂节是利用转动的铰链,以提升工作平台[1]。图8展示出了安装在卡车上铰接高空升降与多个起重臂段的铰链。
图8
架空缆车只有一个铰链臂节可伸缩。伸缩升降机能变幅,其悬臂长度可以增加。驾驶室安装伸缩式电梯,如图9伸出悬臂的顶端部分,可以增加悬臂长度较小的部分。
图9
伸缩机构阐明了,空中缆车升降机及伸缩升降机的多个铰链臂节可变幅,他们的长度也可以增加。图10示出架空升降机具有多个臂和其上部悬臂的长度可以伸长。
图10
纵向和横向升降机的可移动性或取决于高空升降的底座不动。纵向和横向的空中缆车有三个基本选项:骨骼,驾驶室安装,或车载。骨骼肌基架空升降机不能因为驱动而升高。然而,它们可以在室内或室外环境中使用,如示于图11。
图11
车载式高空作业升降机不能移动但可以提高。此外,车载式高空作业升降机限制进入室内的一个原因是因为内燃机产生废气。所以车载式高空作业升降机通常用于户外应用。一辆卡车式高空作业车,它有两个关节可伸缩,如图12 。最初主要用于果园樱桃的采摘,因为他们可以很容易地提升和旋转工作人员卡车的侧面,允许快速访问农产品。类似的情况在生产果园里,高空作业车可以升高到查电气线路和电线杆的高度。因此,除了樱桃采摘,还有常用的就是电器企业进行日常检查,维护和修理电源线,特别是经过风暴发生以后,需要的维修都可以用此高空作业车。美国汽车式高空作业升降机的品牌有:Altec, Terex, Elliot's Hi-Reach, and Versalift.
图12
对于许多建筑和公用设施的工作,高空作业车被用来达到非常高的位置。在较高的位置,不存在对运营商很多风险,在不同空中缆车就有不同程度的风险。首先,危险可以通过其严重程度被定义为:灾难性的,关键性的,边缘性的,意味着危险很可能会导致死亡,或者身体大面积严重受伤,当身体小部分受伤时,可以用绷带和包裹紧急处理处理就可以忽略不计此伤害,因为几乎没有任何身体伤害发生。二,危险可以通过危害发生的概率来定义:频繁的,可能的,偶然的,或不可能。经常意味着危险已经发生的概率最大,可能是出现的第二个概率最高;偶尔是发生的第二小的概率,而不可能是有发生的可能性最小的一个意外。这种风险评估是一个一阶段进行一般评估,仔细评估使用空中作业车的细节方面,以降低这些风险,以进一步描述可能的风险。
常见高空作业的危害可分为十一种不同的事件:触电翻倒,汽车碰撞,破碎,电源故障,平台,掉落的工具或用品,振动,碰撞障碍物,和恐高症。最严重和普遍发生的危险是高空升降平台操作人员的触电。超过三分之一的触电等意外都是因为接触到高空电力线路,因为接触高电流的电源线而死亡。电击,是由于接触到较低的电流,不会导致死亡。现在许多电力公司都保证了空中缆车所使用的较高位置的电气线路,如图13,当然也有触电发生的一个偶然概率。垂直和水平架空升降机运行最容易触电,因为它们能容易地朝着电力线旋转。
图13
偶尔出现的另一个灾难性的事件是站在高空升降机的栏杆最边或者俯身时,而导致坠落。大多数的跌倒发生在纵向和横向的空中缆车,因为他们的平台是小于垂直升降机的范围。在高空升降机中最有可能发生灾难性的一个危害是自动的碰撞。汽车碰撞时,其他车辆撞击作业车,通常导致从平台中飞出。汽车碰撞可以发生在任何的空中缆车,只要作业车处于接近附近其他车辆时。架空缆车接近其他车辆时,在建筑工地,特别是当他们在车行道。车载式高空作业升降机一般在道路上工作,因此,他们更可能发生汽车碰撞。
结论和未来的工作
对空中缆车以及它们的动态进行了研究。所使用的许多空中缆车都能达到很高的高度。空中缆车用于建筑工地,窗洗涤,从风暴中清理废墟,修理电气线路,甚至在电影制作中也会得到应用。有许多不同类型的高空缆车,它们有六种基本类型,可以有效地描述他们的运动。振荡和高空升降机翻倒有效的控制了危害。
创建一个高空作业的动力学模型来研究高空升降的动态。振荡模拟表明偏心和减少残余幅度。剩余振幅为回转动作迅速效应出现了一个扩展回转动作。从研究回转的残留振荡并结合回转和俯仰移动时,振荡频率和阻尼比为阐明高空升降模型进行了计算,形成一个输入整形器。输入整形减少剩余振幅为回转运动以及回转和变幅肘动作。
在本文的实验中,调查研究了某些高空升降机,对未来的空中缆车领域的工作有了一个方向性的好建议,以帮助消除或减少其中的一些较大危害的风险。模拟它们行为的并调查不同的输入整形器的模型来阐明高空作业车的性能,并比较它们的稳定时间和不定形的稳定时间。此外,最大残余振幅为每个整形对比,可以阐明空中作业试验对振荡的结果进行比较以确定更适合的控制器。此外,该模型架空升降机可给予成形的输入进行比较,以得到成形的仿真结果。最后,阐明空中缆车有两个关节诱导振荡。对于今后的工作,可以研究并分别了解选择最适合的控制器,用于阐明高空升降机的性能。
DYNAMIC CHARACTERJZATION AND ANALYSIS OF AERJAL LIFTS
A Thesis Presented to
The Academic Faculty by
Eileen C. Hernandez
In Partial Ful丑llment
of the Rβquirements for the Degree Master of Science in the
George W. Woodruff School of Mechanical Engineering
Georgia Institute of Technology December 2012
SUMMARY
Aerial lifts 町e used to elevate people and material to high heights. There 町e 皿皿y different types of aerial lifts which have vastly different dyn缸nics characteristics. Thus, a new categorization for aerial lifts w出created and organizes them by their kinematics. Many accidents occur while using aerial lifts. Haz町ds of aerial lifts and current solutions to those hazards were reviewed to understand the causes of the accidents. Some major accidents are due to the compl缸 dynamics and flexibility of a启Z划 lifts, such as oscillations and tip-overs. Oscillations of full-size a町ial lifts were experimenta』ly tested to determine 仕equencies in different configurations. Machine-motion induced oscillations of an articulati卫g aerial lift were simulated and analyzed for both non-overcenter and overcenter configurations. fuput shaping was used to achieve reduction in machine-皿otion induced oscillations. Tip-over stability margin was used to simulate and analyze the stability of both non-overcenter and overcenter configurations. The effect of increased platform m回s on tip-over stability m町gin W出also analyzed. The results in this thesis are a categorization of aerial lifts including their hazards and methods of reducing those hazards, an experimental verification of the dyna皿ic response of full-size aeria』 lifts, a fully dynamic tip-over prediction model of double-boom articulating aerial lift by applying flexibility in the joints and realistic velocity profiles, and a detailed study of the dynamics of a double-boom articulating aerial lift.
Xl
CHAPTER I
INTRODUCTION
There are many ways people reach high heights to work on buildings, trees, airplanes, and other tall structures. In many cases, aerial lifts 缸e used to provide the desired height and work environment. Aerial work lifts, like the one shown in Figure 1, provide many necess町y benefits to users that need an elevated work platform. However, with those benefits come significant hazards.
“According to the U.S. Bureau of Labor Statistics about 26 construction workers die each ye町 from using aerial lifts. Approximately 70% involve boom supported lifts, such as bucket trucks and cherry pickers; 25% of the other
deaths involve scissor lifts” [ 1].
//
Figure 1: An Altec truck-mounted articulated aerial lift working on electrical lines.
1
From 也ese statistica.1. facts two ma.in challeng四can be infeITed. The 位就 challenge is deter回国ng how to reduce fatalities that occur when using aerial lifts. Tb创甘:ore, there is a n四d to identi岛r 也e most co皿mon hazards of 树总al lifts and how they occur. The second
challenge is widersta.nding the 祖erent aerial work lifts (i息 bucket trucks, cbeny pick,棚,
SC凶sor lifts, etc.), their respective b相ards, and m创hods to reduce those h拙ards. Before detennilling how to redu,创 制iden馅,it is 国1portant to understand 也e different 槌rial 且她 well enough to develop po协ntial solutions that could be applied to the 嗣ria.l work lifts under consideration.
1.1 Desc时俐 ” and Categoriza锐on of Ae付 t L梆s
Aerie.I work lifts have e. wide range of a.ppearan臼s; however, all of them, a.re 四ed to position people high 凶the air [1]. Different m础.anisms m四创 始 阳form this 凶ing motion.
The kinematic structur程 ie what 部,para也·ee difl趾·ent typ剧 f aerie.I work lifts. The 缸'St
distinguishing factor 础 ng 棉对al lifts is 必rectionality of 白白motion: i) only vertical or, 总) Vi ical and horizontal,掘础 wn in Figure 2. A S部ond catego归ation is 也.e method used to elev在te the work platform. 四ere are thr锦 different m础 ds of elevation within each
位ectional ca.te静思 Ve民ic创凶s use:斗 部i筋 z,总.) ve约iβal mast,础d i均 pulley Sy侃锢s.
’
Lifts performing v的ical and horizontal motion use: i) tel制叩ic, ii) a.rticul就问,and 诅) te1锦oopic articulating. The final major way to dilferentia:悔 aerial 1出s is by their a.b山在y or 国功迫ity to drive on the ground while elevated.
3
Jf
,,
,
,
,
,,
,
····-
4
一
,
‘ ’川 ,
,
1也·u·····a
(碍 nly vertical motion
(均 Vertical and ho归ontal motion
Figure 2: Two Categori郁 f Aerial Li成 Motion.
Mobility while elevat.ed depends on the b副e ofthe aeriAl lift. L也a 份1at are able 协 缸ive while i总 部eration have a cab base to hold the power supply 仰d削略 Figure 3(a) 凶础 example of a cab-base lift. Ifa lift b锦a skeletal struct山珍 for the base or is 也ruck-mounted, then the aeria.I lift is unable to drive while elevat创.A1l 姐ample of 8ll immobile aerial lift with a skeletal b毗凶shown in R脚跟 3{b).
(a) Genie Z-80 mobile cab base (b) Genie TZ-34/到回mobile telescopic tele阂 ,pie 恼ticulating lift articulating lift with an skeletal base
Figure 3: Examples of mobile 1and immobile 辅rill』 lifts a.
Overall, moat aeri剑 work 凶S 锦n be 以aced 恒 ne of 出.e following 胆 d翩翩:
1. Sci”。r L出a
2. Verti恼J Mast L出8
3. Pulley Lifts
a τelesc。p沁 Lifts
、
5. Articula.ting Lifts
6. τ lesco以c Articulating Lifts
Scissor 崎S, V础ica.I m崎t 溢缸,and pulley li岛sperform only v础ica.I motion. τ副阁copic lifu:I 馆也ic叫.a.t坠g lifu:I, and teleacopic articulating lifts perform verti凶J and horizontal mo tion. Each cate伊叩h础varia悦 ns that c础 r c础not drive while elevated. By including 辅ria.I lifts’ mobility or i.mm抽出ty while el剧时时,th.e complete categorizat沁n of a衍凶险加 is giv, in Table 1.
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τ'he power supply used by aerial lifts do四not depend on the directionality of itsmotion. It depends on the intended work environment. Two different work environments for aerial l出s are: i) indoor 皿d ii) outdoor environments. Indoor environments re的rict the power supplies to those that do not emit 但:ha.ust such as electric, manual, battery, and sometim四 a hybrid that uses E翩 r diesel outdoors and electricity or b也.ttery indoors. Outdoor en- vironments 町e not 田restrictive as indoors; thus, all power suppli田can be used. Other options that apply to all aerial lifts 町e insulation for electrical work and/or reinforced heavy duty for industrial work.
Some companies that 町e well lmown for aerial work lifts include:τer眩 Ni缸yli丘 Alt钮,
JLG, Haulotte, R刷.chm嗣ter, Skyjack, Snorkel, E血的,Versalift, MLE Man Li晶 Manuf胁 tur国g Co., and Hi-Rea.ch. MLE Man Li丘 Manufacturing Co. sp臼ializ由国皿a.king custom aerial lifts such 回clean room lifts and pedestal mount man-lifts. Bridge Across Specialties,
Wes也 Co届t Under Bridge Platforms, and Pal.finger specialize in truck-mounted aerial work l监s capable of accessing beneath bridges for rep膛,皿aintena.nce, and 且spection,剧由佣n in Figure 4.
Figure 4: Palfinger’s vehicle-mounted bridge 皿spection l出performing 皿aintenance under a bridge. 14
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9
1.1.1 Verti恤l Lifts
V目世cal 凶s are 11Plit into thr喃wbl蜘ti()Illj: IICis盹r lift8, vertical 国剧t lifts 阻d pulley 蹄,Sci阂 r lift.a a.re 陆ntilied by th席四que structure that r酬mbles mul句,le scis阳m retra.c出sto redu曲M梆础d 8X阴.nd问to m翩翩e heigl拢 幽幽翩 in Figure 5.
Figure 5: Genie GS”1530 刷刷 r lift with 铀b b割e.15
W此icsl. m翩 翩e ha晦 田1且]ti 阳ti 但a a篇 either fit in.side 惆e 础 由er or equal 鹏也io惚也at slide up agAilJBt one a:na也er to 总翩翩lheight. A且但.11111ple of a verti锦l m础 lift Iss』own InFi .ire 6. Both 能lssor lifts and var舶d mast lifts have 也e option of mob心lty while ell!V就ed. If the lift h剧 a cab bl!i酶,lib the 咽ne i且 F地归嗡 5,他刷出e lift c皿 dri喃
W祖ile d回事协d.
Pulley lifts 1幽也e comm仙”ill!’\ ”脚,m t.oelev&te 他e locatlon 。.fthe响出且g plat阳m.
Cun回街 th晴 哑ly known pulley H岛倒乱ilable has & sb,let侃 而ucture 如‘b剧院 A pulley 溢ft 创地not be mobile W汹le ele喃,ted b帽刷晶e it b嗣a d岱坊ta! struct植re for a b制峙 楠ab.own in Fi .Ire 7.
All var悦阳I lifts 曲n be us创帆1tdoore. Due to t』.e small bodi帽 and fo的prints of vertical
溢疵,they c陆al阳all be uaed indoors 棉long 础 they a.re not 伊a or di回el p阳惚ed.
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Figure 6: Haulotte immobile vertical mast lift.6
Figure 7: JLG’s Liftpod that uses a pulley system.7
1.1.2 Vertical and Horizontal Lifts
Vertical and horizontal lifts are comprised of: articulating lifts, telescopic lifts, and telescopic articulating lifts. All vertical and horizontal motion aerial lifts achieve lifting by pivoting their boom(s), represented 回 a dashed red line in Figure 2(b). The booms of a vertical and horizontal aβrial lift are commonly referred to as the arm of the aerial lift. In addition, vertical and horizontal motion aerial lifts rotate at the base to provide access in all directions.
Figure 8(a) shows a rotation at the base around the vertical axis of an aerial lift commonly referred to as a slew movement. Figure 8(b) shows a rotation around a horizontal 缸is of an aerial lift commonly referred to as a luffing moveme时,which is the result from pivoting their booms.
Base
+
1
TW
」
TL
(a) Slewing motion (overhead view) (b) Luffing motion (side view) Figure 8: Movements of vertical and horizontal motion aerial lifts.
An articulating aerial lift has two or more hinged boom sections that pivot at the hinges to elevate the working platform [1]. Figure 9 shows a truck-mounted articulating aerial lift with multiple boom sections.
Figure 9: Altec articulating aerial lift.
Aerial lifts with only one hinged boom section may be telescopic lifts or just a one boom aerial lift. Telescopic lifts can slew, luff, and their boom length can increase due to the
Figure 10: Genie S-60’sτ'ra.x cab base t.elesc呻ic aerial lift. 16
multiple s出tions wi也in e. boom. The c配,b-mount.ed telescopic li丘 in Figure 10 b幅a.sm刻ler
”ction extendi.Dg out of the top pa.rt of 出怠 boom to i.Dcrease the boom length.
白lesc ,pie 缸锐cul.at凶恶 aer圳 ]出s are 馆ti,.ua创ng lifts and t.el,邻copie 坦fts comb丽时- Teleacopic 彼ticulating lifts have multiple hinged boom 锦ctior邸 佣a slew, luff 础d 也heir
booms c阳were回e in length. F泡出e 11sho· 植 树rial 时b with multiple booms and its
upper boom can 部pa.nd iD Ieng协 due to the tel倒copic sectio出.
Fig11. 1re 11: Ge皿e Z-60β4 c也b b嗣e telescopic a.r秘culat凶g lift. 10
V创tical. and horizontal. lifts ca.n. be mobile or immobile w.垣le elevated dependi吨 upon the base of the aerial lift. Vi仪tical a.nd ho巾,ntal aerial lifts have three base optioDS:
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