现代双梁桥式起重机的设计

毕业设计（论文）- 1 -第1章 前言起重机械是用来升降物品或人员的，有的还能使这些物品或人员在其工作范围内作水平或空间移动的机械。取物装置悬挂在可沿桥架运行的起重小车或运行式葫芦上的起重机，称为“桥架型起重机” 。桥架两端通过运行机构直接支承在高架轨道上的桥架型起重机，称之为“桥式起重机” 。桥式起重机一般有大车运行机构的桥架、装有起升机构和小车运行机构的起重小车、电气设备、司机室等几大部分组成。外形像一个两端支承在平行的两条架空轨道上平移运行的单跨平板桥。起升机构用来垂直升降物品，起重小车用来带着载荷作横向移动，以达到在跨度内和规定高度内组成的三维空间里做搬运和装卸货物用。桥式起重机是使用最广泛、拥有量最大的一种轨道运行式起重机，其额定起重量从几吨到几百吨。最基本的形式是通用吊钩桥式起重机，其他形式的桥式起重机都是在通用吊钩桥式起重机的基础上派生发展出来的。起重机的产品型号表示为：类、组、型代号 特征代号 主参数代号 更新代号例如：QD20/5桥式起重机表示为，吊钩桥式起重机，主钩 20t，副钩5t 。在设计过程中，结合起重机的实际工作条件，注意了以下几方面的要求：整台起重机与厂方建筑物的配合，以及小车与桥架的配合要恰当。小车与桥架的相互配合，主要在于：小车轨距（车轮中心线间的水平距离）和桥架上的小车轨距应相同，其次，在于小车的缓冲器与桥架上的挡铁位置要配合好，小车的撞尺和桥架上的行程限位装置要配合好。小车的平面布置愈紧凑小车愈能跑到靠近桥架的两端，起重机工作范围也就愈大。小车的高度小，相应的可使起重机的高度减小，从而降低了厂房建筑物的高度。小车上机构的布置及同一机构中各零件间的配合要求适当。起升机构和小车平面的布置要合理，二者之间的距离不应太小，否则维修不便，或造成小车架难以设计。但也不应太大，否则小车就不紧凑。小车车轮的轮压分布要求均匀。如能满足这个要求，则可以获得最小的车轮，轮轴及轴承箱的尺寸，并且使起重机桥架主梁上受到均匀的载荷。一般最毕业设计（论文）- 2 -大轮压不应该超过平均轮压得20%。小车架上的机构与小车架配合要适当。为使小车上的起升、运行机构与小车架配合得好，要求二者之间的配合尺寸相符；连接零件选择适当和安装方便。在设计原则上，要以机构为主，尽量用小车架去配合机构；同时机构的布置也要尽量使钢结构的设计制造和运行机构的要求设计，但在不影响机构的工作的条件下，机构的布置也应配合小车架的设计，使其构造简单，合理和便于制造。尽量选用标准零部件，以提高设计与制造的工作效率，降低生产成本。小车各部分的设计应考虑制造，安装和维护检修的方便，尽量保证各部件拆下修理时而不需要移动邻近的部件。总之，要兼顾各个方面的相互关系，做到个部分之间的配合良好。毕业设计（论文）- 3 -第2章 起升机构设计2.1 确定起升机构的传动方案，选择滑轮组和吊钩组2.1.1 主起升机构 起 升 机 构 计 算 简 图毕业设计（论文）- 4 -根据设计要求的参数，起重量Q=300t，属大起重量桥式起重机，鉴于目前我国的生产经验及以生产出的机型，决定采用开式传动。 该设计的基本参数如下表：起重量Q起升高度H起升速度V 运行速度V 跨度L300/50t31/33m1.1/7.0m/min 27.5/8.0m/min22m根据设计所给的参数我们可以有如下方案，如图a所示。显然，a方案结构简单，安装及维修都比较方便，但是由于轴 两端的变形较大使得小齿轮沿齿宽方向受力不均匀，易产生磨损。针对这一缺点b方案都对其进行了完善，使小齿轮的受力均匀，而且从结构上看，该方案不但可以使小齿轮受力均匀，而且结构紧凑简单，又考虑我国现有的生产经验故采用最终采用此方案。由设计参数知，起升高度H为31m，根据这一参数，我们选择双联滑轮组单层卷绕。这种绕绳方法构造简单，制造及安装方便，由于该起重机的起重量较大，钢丝绳对卷筒的压力较大，故此采用单层绕。综上所述，采用开式、双联滑轮组单层绕结构。 按Q=300t，查 1表4-1 取滑轮组的倍率I h=10，则可知钢丝绳的分支数为Z=4*I h=40。查2表15-15，知Q=300t 的桥式起重机选用叠片式双钩，叠板式双钩是由钢板冲剪成的钢片，用铆钉连接 开式传动而成。为了使负荷均等分布到所有钢片上，在叠板钩开口处，装镶可拆环的钢板。同时，在钩 颈环形孔中装有轴套。钩片材料用A3钢。这种结构有很毕业设计（论文）- 5 -电 动 机变速箱 开式齿轮 卷 筒轴承 轴承联轴器图a 第一种传动方案电 动 机变速箱 开式齿轮 卷 筒轴承 轴承联轴器 联轴器图b第二种传动方案毕业设计（论文）- 6 -多优点：（1）制造比较简单，特别是尺寸较大的吊钩（2） ih=12工作可靠，因为破坏开始时，首先在某一片钢片上产生， Z=24这样就可以进行维修，从而避免了破坏的进一步发展。该 叠片式吊钩的自重为：G 0=14t，两动滑轮间距A=250mm.。 双钩2.1.2 副起升机构 副起升机构参照主起升机构的原理采用，闭式传动、双连滑轮组、单层绕结构。根据其要求的起重量为50t，查 1表4-1 可知，取滑轮组倍率I h=4，则承重绳的分支为：Z=2 I h=8。 ih=4查2表15-10选用单钩（梯形截面）A型，其自重为 Z=8Gg=326kgf，查2表15-15选用5个滑轮，直径采用D=600mm 单钩，其自重为G g=80kgf，两动滑轮间距为A=120mm，估算吊钩组自重为G g=1t。 （参阅2 表13-2） 。 2.2 选择钢丝绳 2.2.1 主起升机构 主起升卷筒的钢丝绳的卷绕在双联滑轮组中，可以采用平衡滑轮结构，但也可以采用平衡杠杆来满足使用及装配的要求。采用平衡杠杆的优点是能用两根长度相等的短绳来代替平衡滑轮中所用的一根长绳，这样可以更加方便的进行更换及安装，特别是在大起重量的起重毕业设计（论文）- 7 -机当中，绳索的分支数比较多，采用这种结构的又有点就更加明显。其具体结构如上图所示。因为在起升过程中，钢丝绳的安全性至关重要，所以要保证钢丝绳的使用寿命，为此，我们可以采取以下措施：（1） 高安全系数，也就是降低钢丝绳的应力。（2）选用较大的滑轮与卷筒直径。（3）滑轮槽的尺寸与材料对于钢丝绳的寿命有很大的关系，其太大会使钢丝绳与滑轮槽接触面积减小，太小会使钢丝绳与槽壁间的摩擦剧烈，甚至会卡死。（4）尽量减少钢丝绳的弯曲次数。滑轮组采用滚动轴承，当i h=12时，查3 表2-1，知滑轮组的效率是： h=0.915。钢丝绳受到的最大的拉力为：kgfiGQsh1429895.0*12)43(30max 查3表2-4知在中级工作类型时，安全系数K=5.5 ，钢丝绳选用线接触6w（19）型钢丝绳，查2表12-3可知，其破断拉力换算系数=0.85，则钢丝绳的计算钢丝绳破断拉力总和为： kgfskb925164148*5.0max查2表12-10知，钢丝绳6w （19） ，公称抗拉强度185kgf Smax=14298kgf 直径d=35mm ，其钢丝破断拉力总和为：S b=92750kgf， d=35mm标记如下：钢丝绳6w（19）-35-185-I-光-右交（1102-74）2.2.2 副起升机构毕业设计（论文）- 8 -副卷筒的钢丝卷绕根据其倍率为I h=4，如上主起升机构的计算，查3表2-1知滑轮组效率为 h=0.975，钢丝绳所受的最大拉力： 5.638)91.0*42(5)(0maxhiGQs查3表2-4知在中级工作类型时，安全系数K=5.5 ，钢丝绳采用线接触6w（19）型钢丝绳，查2表12-3可知，其破断拉力换算系数=0.85，则钢丝绳的计算钢丝绳破断拉力总和为： 423085.638*5.0.maxsksb查2表12-10知，钢丝绳6w （19） ，公称抗拉强度200kgf， Smax=6538.5kgf直径d=22.5mm ，其钢丝破断拉力总和为：S b=42350kgf， d=22.5mm其标记如下：钢丝绳6w（19）-22.5-200-I-光-右交（1102-74）毕业设计（论文）- 9 -2.3 确定滑轮组的主要尺寸 滑轮许用最小直径：Dd(e-1)，查3表2-4查知，其中轮绳直径比e=25。2.3.1 主起升机构有：D35*(25-1)=840mm，参考2表13-2，初步选用滑轮D=1000mm，由 1中附表2知取平衡滑轮直径D p=0.6D D=1000mm =0.6*1000=600mm，取D p=600mm，其具体尺寸参照2表13-2 。 Dp=600mm 2.3.2 副起升机构有：D22.5*(25-1)=540mm，参考2表13-2，初步选用滑轮D=600mm ，由1中附表2知取平衡滑轮直径D p=0.6D=0.6*600=360mm，取D p=400mm， D=600mm 其具体尺寸参照2表13-2 。 Dp=400mm2.4 确定卷筒尺寸并验算其强度卷筒直径：Dd(e-1)2.4.1 主起升机构 卷筒直径：Dd(e-1)=35*24=840mm为了适当的减少卷筒的长度，故此选用较大直径的卷筒，选用卷筒直径D=2100mm ，参照 2表14-3，选用标准槽卷筒，其绳槽螺距。卷筒长度： 100)4(*2 LtZDHiLh 即 4581m16038*42138)*(.43*2 则卷筒的长度为：L=4600mm毕业设计（论文）- 10 -如上公式，其中Z 0为附加安全圈数，取Z 0=2。L 1 为卷筒中央无槽的光面部分，取其L 1=A=160mm，D 0为卷筒计算直径D 0=D+d=2138mm。 卷筒的壁厚：mm5248)106(210*.0取 =50mm。卷筒壁压力验算：kgf/cm275)38*50(1429maxaxtsy卷筒设计采用20Mn钢焊接而成，查4表4-9知，其抗 D=2100mm压强度极限 =4500 kgf/cm2,抗拉强度极限 b=2750 kgf/cm2, L=4600mm by故其许 用压应力 y=by/4.25=4500/4.25=1059 kgf/cm2, t=38mm， 因此可以看出强度足够可以满足使用要求。 =50mm由于卷筒长度L20000kgfm，即：有 MmaxN 故减速器满足要求。3.10 验算起动不打滑条件因该机型用于电站厂房内的检修，故坡度及风阻力矩均不计，故在无载启动时，主动车轮上与轨道接触处的圆周切向力：查2 表18-10，取YDWZ-200/25型制动器，额定制动力矩Mez=20kgfm。由于所取制动时间t z=3sec，且已经验算了启动不打滑条件，故略去制动不打滑验算。3.11 选择连轴器（1） 机构高速轴上全齿连轴器的计算扭矩 kgfmnMeljs7.14 4.1*930/57*21其中，=2，等效系数，查1表2-7可知，n1=1.4,安全系数，查 1表 2-21可知，Mel相应于机构JC%值得电动机额定力矩折算到高速毕业设计（论文）- 29 -轴上的力矩，查2图33-1可知，电动机JZR2-21-6 的参数为：d=40mm,l=110mm,d=40mm,l=110mm. clz3型联轴器查2表17-6选用clz3型连轴器，最大允许扭矩为：M=315kgfm,飞轮矩（GD 2） z=0.345kgfm2,重量为：Gz=21.7kgfm.(2)低速轴的计算扭矩 kgfmiMjsjs 7.159.0*7265.14*0 查2表21-11知，ZQ-850+250型减速器的低速轴为：d=140mm,l=200mm，查 2表19-7可知，QU800型车轮伸出轴端：d=150mm,l=180mm.查2表17-6选用连轴器clz8型，最大允许扭矩为：Mmax=23660kgfm.3.12 演算低速浮动轴强度疲劳演算低速浮动轴的等效扭矩： kgfmiMel 5.879.0*1265/4.3*10其中， =1.4，查1表2-7 知，因浮动轴d=130mm,则有：kgfmWIn20)3./(8721则其许用扭转应力为： 21/1.374./*5230ckgnmk其中，材料用45钢，取 s=6000kgf/cm2,s=3000kgf/cm2, -1 =0.22s =0.22*6000=1320kgf/cm2,s =0.6s =0.6*3000=1800kgf/cm2毕业设计（论文）- 30 -k=kxkm考虑零件的几何形状及表面状况的应力集中系数，取k=2.5,I=1.4，安全系数查1 表2-21可知，有 n16.5m） ，一般采用高速集中传动方案，而对小跨度（13.5m ）可以采用低速集中传动方案。在大车运行机构具体布置的主要问题是：(1) 联轴器的选择(2) 轴承位置的安排(3) 轴长度的确定这三者是相互联系的，在设计过程中要考虑到其中各个部分的配合，做到相互兼顾，充分发挥各个零件的作用。在布置大车运行机构时，要注意以下几个方面：(1) 要安装在起重机桥架上，桥架的运行速度很高，而且受载之后会发生挠曲现象，机构零部件在桥架上的安装不可能十分准确毕业设计（论文）- 43 -所以单单从保持机构的运动性能和补偿安装的不准确性着眼，在靠近电动机、减速器和车轮的轴，最好采用浮动轴。(2) 为了减少主梁的扭转载荷，应使机构零部件尽量靠近主梁而远离走台栏杆，尽量靠近端梁，使端梁能直接支撑一部分零部件的重量。(3) 对于集中传动的大车运行机构，轴承应安装在桥架走台的撑杆上方，而不要为安装轴承而增加杆件，以致增加桥架梁重量并使制造麻烦。对于分别传动的大车运行机构应参考有关的资料进行设计。在保证浮动轴有足够长度的情况下，要尽量减小机构的尺寸。(4) 制动器要靠近电动机，使浮动轴可以在运行机构制动时能发挥吸收冲击动能的作用。参照以上所述，由于所设计的参数级别较大，跨度中等，故 分别驱动采用分别驱动的方案。大车运行机构的设计计算与小车运行机构的计算过程及步骤类似，也要首先计算车轮运行阻力及车轮及轨道所能承受的强度，然后，选择电动机，联轴器，变速箱，浮动轴，车轮及轨道并对其进行强度，制动性的校核。毕业设计（论文）- 44 -结论通过此次毕业设计，让我了解到了很多方面东西。首先，此次毕业设计把大学四年来的理论知识复习、总结并应用于实践当中，让我们对工程机械特别是起重机械有了更深入的了解。从整体结构到各个部件都有了一个全面的认识。此次设计不但是对我们以前学习的一种深入，更是我们今后工作的一种理论基础。致谢毕业设计是我们大学生活中很重要的一个课题，现在我完成毕业设计即将完成学业、步入社会，首先要感谢孙振军老师在毕业设计过程中的指导和帮助，感谢各位老师四年来的关心和教导。我一定谨记老师们的教诲，今后努力工作不辜负老师们的期望和教导。毕业设计（论文）- 45 -参考资料1 起重机课程设计 陈道南、盛汉中 冶金工业出版社 1982.62 起重机设计手册 机械工业出版社 3 起重运输机械 陈道南、过玉清、周培德、盛汉中 高等学校试用教材 20004 机械零件手册 周开勤 高等教育出版社 2000.125 起重机计算实例 陈国璋、孙桂林、金永懿、孙学伟、徐秉业 中国铁道出版社 19856 机械设计 濮良贵、纪名刚 高等教育出版社 2000.127 互换性与技术测量 廖念钊等 中国计量出版社 2000.1毕业设计（论文）- 46 -Design of machine and machine elementsMachine designMachine design is the art of planning or devising new or improved machines to accomplish specific purposes. In general, a machine will consist of a combination of several different mechanical elements properly designed and arranged to work together, as a whole. During the initial planning of a machine, fundamental decisions must be made concerning loading, type of kinematic elements to be used, and correct utilization of the properties of engineering materials. Economic considerations are usually of prime importance when the design of new machinery is undertaken. In general, the lowest over-all costs are designed. Consideration should be given not only to the cost of design, manufacture the necessary safety features and be of pleasing external appearance. The objective is to produce a machine which is not only sufficiently rugged to function properly for a reasonable life, but is at the same time cheap enough to be economically feasible.The engineer in charge of the design of a machine should not only have adequate technical training, but must be a man of sound judgment and wide experience, qualities which are usually acquired only after considerable time has been spent in actual professional work.Design of machine elementsThe principles of design are, of course, universal. The same theory or equations may be applied to a very small part, as in an instrument, or, to a larger but similar part used in a piece of heavy equipment. In no ease, however, should mathematical calculations be looked upon as absolute and final. They are all subject to the accuracy of the various assumptions, which must necessarily be made in engineering work. Sometimes only a portion of the total number of parts in a machine are designed on the basis of analytic calculations. The form and size of the remaining parts are designed on the basis of analytic calculations. On the other hand, if the machine is very expensive, or if weight is a factor, as in airplanes, design 毕业设计（论文）- 47 -computations may then be made for almost all the parts.The purpose of the design calculations is, of course, to attempt to predict the stress or deformation in the part in order that it may sagely carry the loads, which will be imposed on it, and that it may last for the expected life of the machine. All calculations are, of course, dependent on the physical properties of the construction materials as determined by laboratory tests. A rational method of design attempts to take the results of relatively simple and fundamental tests such as tension, compression, torsion, and fatigue and apply them to all the complicated and involved situations encountered in present-day machinery. In addition, it has been amply proved that such details as surface condition, fillets, notches, manufacturing tolerances, and heat treatment have a market effect on the strength and useful life of a machine part. The design and drafting departments must specify completely all such particulars, must specify completely all such particulars, and thus exercise the necessary close control over the finished product.As mentioned above, machine design is a vast field of engineering technology. As such, it begins with the conception of an idea and follows through the various phases of design analysis, manufacturing, marketing and consumerism. The following is a list of the major areas of consideration in the general field of machine design: Initial design conception; Strength analysis; Materials selection; Appearance; Manufacturing; Safety; Environment effects; Reliability and life;毕业设计（论文）- 48 -Strength is a measure of the ability to resist, without fails, forces which cause stresses and strains. The forces may be; Gradually applied; Suddenly applied; Applied under impact; Applied with continuous direction reversals; Applied at low or elevated temperatures.If a critical part of a machine fails, the whole machine must be shut down until a repair is made. Thus, when designing a new machine, it is extremely important that critical parts be made strong enough to prevent failure. The designer should determine as precisely as possible the nature, magnitude, direction and point of application of all forces. Machine design is mot, however, an exact science and it is, therefore, rarely possible to determine exactly all the applied forces. In addition, different samples of a specified material will exhibit somewhat different abilities to resist loads, temperatures and other environment conditions. In spite of this, design calculations based on appropriate assumptions are invaluable in the proper design of machine.Moreover, it is absolutely essential that a design engineer knows how and why parts fail so that reliable machines which 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 speeds. On the other hand, a failure may be no more than a nuisance. An example is the loosening of the radiator hose in the automobile cooling system. The consequence of this latter failure is usually the loss of some radiator coolant, a condition which 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 difficulties 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 毕业设计（论文）- 49 -considered to be unacceptable where fatigue is involved.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.The part sizes and shapes selected must also take into account many dimensional factors which produce external load effects such as geometric discontinuities, residual stresses due to forming of desired contours, and the application of interference fit joint.Selected from” design of machine elements”, 6th edition, m. f. sports, prentice-hall, inc., 1985 and “machine design”, Anthony Esposito, charles e., Merrill publishing company, 1975.Mechanical properties of materialsThe material properties can be classified into three major headings: (1) physical, (2) chemical, (3) mechanicalPhysical properties Density or specific gravity, moisture content, etc., can be classified under this category. Chemical propertiesMany chemical properties come under this category. These include acidity or alkalinity, react6ivity and corrosion. The most important of these is corrosion which can be explained in laymans terms as the resistance of the material to decay while 毕业设计（论文）- 50 -in continuous use in a particular atmosphere. Mechanical properties Mechanical properties include in the strength properties like tensile, compression, shear, torsion, impact, fatigue and creep. The tensile strength of a material is obtained by dividing the maximum load, which the specimen bears by the area of cross-section of the specimen.This is a curve plotted between the stress along the This is a curve plotted between the stress along the Y-axis(ordinate) and the strain along the X-axis (abscissa) in a tensile test. A material tends to change or changes its dimensions when it is loaded, depending upon the magnitude of the load. When the load is removed it can be seen that the deformation disappears. For many materials this occurs op to a certain value of the stress called the elastic limit Ap. This is depicted by the straight line relationship and a small deviation thereafter, in the stress-strain curve (fig.3.1). Within the elastic range, the limiting value of the stress up to which the stress and strain are proportional, is called the limit of proportionality Ap. In this region, the metal obeys hookess law, which states that the stress is proportional to strain in the elastic range of loading, (the material completely regains its original dimensions after the load is removed). In the actual plotting of the curve, the proportionality limit is obtained at a slightly lower value of the load than the 毕业设计（论文）- 51 -elastic limit. This may be attributed to the time-lagin the regaining of the original dimensions of the material. This effect is very frequently noticed in some non-ferrous metals.Which iron and nickel exhibit clear ranges of elasticity, copper, zinc, tin, are found to be imperfectly elastic even at relatively low values low values of stresses. Actually the elastic limit is distinguishable from the proportionality limit more clearly depending upon the sensitivity of the measuring instrument.When the load is increased beyond the elastic limit, plastic deformation starts. Simultaneously the specimen gets work-hardened. A point is reached when the deformation starts to occur more rapidly than the increasing load. This point is called they yield point Q. the metal which was resisting the load till then, starts to deform somewhat rapidly, i. e., yield. The yield stress is called yield limit Ay.The elongation of the specimen continues from Q to S and then to T. The stress-strain relation in this plastic flow period is indicated by the portion QRST of the curve. At the specimen breaks, and this load is called the breaking load. The value of the maximum load S divided by the original cross-sectional area of the specimen is referred to as the ultimate tensile strength of the metal or simply the tensile strength Au.Logically speaking, once the elastic limit is exceeded, the metal should start 毕业设计（论文）- 52 -to yield, and finally break, without any increase in the value of stress. But the curve records an increased stress even after the elastic limit is exceeded. Two reasons can be given for this behavior:The strain hardening of the material;The diminishing cross-sectional area of the specimen, suffered on account of the plastic deformation.The more plastic deformation the metal undergoes, the harder it becomes, due to work-hardening. The more the metal gets elongated the more its diameter (and hence, cross-sectional area) is decreased. This continues until the point S is reached.After S, the rate at which the reduction in area takes place, exceeds the rate at which the stress increases. Strain becomes so high that the reduction in area begins to produce a localized effect at some point. This is called necking.Reduction in cross-sectional area takes place very rapidly; so rapidly that the load value actually drops. This is indicated by ST. failure occurs at this point T.Then percentage elongation A and reduction in reduction in area W indicate the ductility or plasticity of the material:A=(L-L0)/L0*100%W=(A0-A)/A0*100%Where L0 and L are the original and the final length of the specimen; A0 and A are the original and the final cross