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JX15-06

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【JX15-06】货物搬运升降机平台车设计（CAD+论文）,JX15-06

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第一章 绪论1.1课题研究的目的及意义1.1.1滚轮式液压升降平台车设计的目的1、 理论目的：综合运用机械设计课程、液压技术，材料力学及其他与相关课程的理论知识和生产实际，进行液压升降台设计实践，使理论知识和生产实践紧密结合起来，从而使已有知识学有所用，并得到进一步的巩固和提高。2、实践目的：在设计实践中学习和掌握通用液压元件，尤其是各类标准元件的选用原则和回路的组合方法，培养设计技能，提高分析和解决生产实际问题的能力，为今后的设计制造工作打好的基础。3、通过液压升降平台车设计，学生应在计算、绘图、运用程序软件和熟悉设计资料（包括设计手册、产品样本、标准和规范）以及进行评估方面得到实际训练，增强自主创新设计能力。1.1.2滚轮式液压升降平台车设计的意义 随着当代机械制造业与液压技术的不断发展，社会生产对生产率的要求也越来越高，因此，在人类社会工农业发展中，具有结构紧凑，操作方便，升降平稳等优点的液压升降机起着极其重要的作用。滚轮式 液压升降机是一种新型的液压升降机，主要由机械元件和液压系统等组成。滚轮式 液压升降机适合于车间、仓库、车站、码头等场所，且由于只需要简单动力，不会产生火花和电磁场，故特别适合搬运易燃、易爆物品，这种升降机对提高搬运效率、减轻劳动强度等都具有重要意义。此外，滚轮式 液压升降台根据使用要求，可配置其它附加装置，并可任意多项或组合，能达到更好的使用效果。因此我们有必要对它进行深入研究。本次毕业设计的题目来源于生产第一线，所设计的产品具有实用价值，已经有成熟产品生产。我们可以参考现有产品做出的改进设计，使产品机构更合理、更实用、更可靠。1.2国内外液压技术研究现状及发展趋势1.2.1研究现状 液压升降机的核心部件在于液压提升设备,因此国内外对液压提升设备主要进行动力分析和运动分析，确定液压缸的主要性能参数和主要尺寸。如液压缸的推力速度，作用时间，内径，液压升降机行程及活塞杆直径等。为避免液压缸体积大且沉重、不便拆装、用途单一、价格高、长时间暴露在外面易老化腐蚀，造成无谓的损害，久后会使连接处漏水等缺点。它通常采用35、34号或无缝钢管做成实心杆或空心杆，为了提高耐磨性的防锈蚀，目前国内传统工艺是表面镀硬铬（镀层厚度0.020.05mm）并抛光，其表面粗糙度Ra为1.60.4m。由于镀铬对人、环境污染严重，属国家环保线值项目，且镀层不均匀，液压提升设备的工作液压提升设备其实也就是个最简单的油缸了.通过手动增压秆(液压手动泵)使液压油经过一液压提升设备是液压缸的重要部件。1.2.2发展趋势 随着全球科学技术的迅猛发展，世界液压升降台工业相继发生了一系列重大的技术革命，极大地提高了劳动生产率和产品质量，扩大了生产规模，降低了产品热耗、能耗，有效控制了烟尘、粉尘、有害气体的排放，由此引发了世界液压技术工业快速发展，解决了全球对液压产品的巨大需求。在最近20年，世界液压工业新技术绝大部分是在上世纪几大创新技术的基础上开发或发展的，这些新技术包括降低热耗、提高自动化程度、扩大生产规模、利用废物、环境保护、产品深加工等方面。其中玻璃钢/复合材料的技术有着良好的发展前景，就是要大力开拓玻璃钢/复合材料的应用范围，不断提高先进性能。此外，随着人们生活水平的提高，建筑面积不段增加，像车间、仓库等面积小又急需节省人力资源，提高劳动效率高，减少噪音和污染的场所， 液压升降平台车应运而生。国内外研究人员正针对这些场所，根据人们的不同需要在不断的完善升降平台车的结构性能，改变体积的大小！研发出能够更加实现重物的平稳升降、节省人力、占用空间小、安全可靠并能迅速地对承载物重量的改变做出反应的 液压升降平台车。1.3本课题研究内容本设计课题主要研究内容包括滚轮式液压升降平台车的总体方案论证选择、液压系统回路的设计、相关标准件的计算选型、零部件设计、材料选择首先对液压升降技术参数进行分析研究，结合具体实例，对机构中两种液压缸布置方式分析比较，并根据要求对液压传动系统个部分进行设计计算最终确定液压执行元件-液压缸，通过对铰架的各项受力分析确定台板与铰架的载荷要求，设计出一种高效节能无污染，且运用广泛的滚轮式液压升降平台车。11第二章 滚轮式液压升降平台车的总机设计2.1总体方案的分析比较和确定查阅各种文献资料，结合实际生活经验，拟定滚轮式液压升降平台车的设计需达到以下要求：额定载重量500kg，升降台最大升高高度在950毫米到1050毫米之间，通过脚踩 液压泵提起货物，要求后轮固定，设置过载安全阀，确保操作者安全，刹车安全可靠。可在升程内任意位置停止升降。经过多方面考虑，对滚轮式 液压升降平台车的设计初拟定两种方案， 图2-1（方案一图） 图2-2（方案二图） 方案一分析：如图2-1所示，液压升降台采用的液压缸两端都可在一定空间内自由活动，这样一来对液压缸易受到径向剪切力和较大弯矩，从而对其压杆稳定性要求很高。从外形结构上来说，尺寸设计计算和力的计算都很复杂 ，而且要满足升降台升降时的最大最小高度，需要较大的液压缸行程。此外从安全方面考虑，与液压缸上端作用点相连接的肋板部分作用在连接铰架的轴上，则轴对该处铰架截面作用力将很大，则该截面可能成为危险截面。且当液压缸活塞到底部时，升降台还可能将有较大高度 ，不能满足升降台最低高度的设计要求。 方案二分析：如图2-2所示，该方案和方案一不同之处之一在于，液压缸一端通过轴固定在底座上，另一端通过肋板固定在铰架上，这样液压缸的一端绕另一端在某个较小角度内旋转，能保证液压缸具有较好的压杆稳定性，而且液压缸作用在铰架的实心截面处，使铰架受力分配较均匀。另外，在此方案中，液压缸的作用点较低，那么的液压缸的行程只需变化很小，便载物台就可以实现较大幅度的升降，易于满足设计要求，因此它能节省工作人员的体力，提高工作人员的工作效率。 通过以上的方案分析，本滚轮式液压升降平台车采用方案二设计。2.2液压升降平台车的结构及运动原理 滚轮式液压升降平台车主要由动力源和机架两部分组成，动力源部分主要由液压泵和单作用液压缸组成，机架部分由工作平台，内外剪式铰架板和底座导轨槽，支撑板等构件组成(如图2-3所示)。滚轮式液压升降平台车的运动原理如下所述：首先，升降平台的升降是通过液压缸的伸缩运动来实现地的。液压缸一端通过轴和两肋板与外铰架相连。另一端通过轴固定在底座导轨槽的中部位置；其次，内、外铰架与导轨槽连接的方式为：图示铰架右端通过安装了轴承的滚轮与上下导轨槽相连接，图示铰架左端通过铰支连接固定在上下导轨槽左部； 液压泵经过油管与液压缸相连，则当脚踩液压泵脚踏板时，油压将顶起液压缸使柱塞伸出，当卸荷时，重物的重力将使肋板压缩柱塞，使柱塞回缩进去。由前述的连接方式得，与外铰架5右侧，内铰架3右侧相连接的滚轮将左右滚动，从而工作平台将上升或下降，起到升降货物的作用。此外，万向脚轮10上安装有刹车，方便在搬运货物的时候升降台不会移动。图2-3 液压升降平台车结构 1单向脚轮，2液压缸，3内铰架，4平台导轨槽，5外铰架，6工作平台7手推扶杆，8液压泵，9底座支撑板，10万向脚轮，11底座导轨槽第三章 升降台尺寸初步分析计算3.1升降台高度的计算（1） 、设计升降台最大高度为950至1050mm之间，可取=1000mm左右，而升降台最小高度设计为=435mm； （2）、选用滚轮时，因滚轮为标准件，可选取其直径为150mm，则轮子底部至升降台底座支撑板底部的距离，即滚轮机构总体高度可选为t=200mm；（3)、试选上端导轨槽整体高度=50mm,底座导轨槽整体厚度=60mm,则未考虑平台厚度的情况下，上端导轨槽固定铰支中心与底座固定铰支中心的距离为：a升降台处于最大高度时，=-（t+）=1000-(200+)=745mmb升降台处于最小高度时，=-（t+）=435-(200+)=180mm3.2相关角度的计算 若设液压缸作用点中心与平台底部距离为=10mm,则底座固定铰支中心至液压缸作用点中心的垂直距离为：g=-=180-10-=145mm。 由升降平台尺寸为1010520mm,则可设升降台处于最低高度时，底座固定铰支中心与活动铰支中心两点距离为d=850mm。则tan=0.2117 =则2L=869mm从而sin=0.8575 =以上2L- 铰架长度； - 升降台最低高度时铰架中心线与底座导轨中心线夹角； - 升降台最大高度时铰架中心线与底座导轨中心线夹角；此时升降台处于最大高度时有，底座固定铰支中心与活动铰支中心两点距离为e=448mm=435mm。这说明当升降台处于最大高度时，所承受重物作用中心仍介于平台固定铰支中心与活动铰支中心之间，使得平台倾覆的可能性极小，满足稳定性要求。3.3液压缸作用结构图分析 如下两图3-1、3-2中:图3-1 升降台结构分析 图3-2 液压缸作用简化图若令=m ，=p ，则=n由确定； 设计当升降台达最大高度时，液压缸作用点中心与底座固定铰支中心连线ce处于垂直位置，即与水平成，则 当=时，sin（+）=g=145mm； 当=时，+= = 由上得p=213mm现将液压泵的支撑点作用于底座中心d点，则 M=425mm 现计算液压缸中心线（线ed）到c点的距离n的大小 对于ced，由面积关系可有： ，从而得： 将p=213mm，m=425mm，=代入上式得： 第四章 升降台受力及力矩分析4.1整体受力分析图 升降台在整体受力如图4-1，图4-1 整体受力分析图4.2外铰架受力分析图 外铰架L1受力分析如图4-2，图4-2 外铰架受力分析图图中： , ; , ;4.3内铰架受力分析图内铰架L2受力分析如图4-3，图4-3 内铰架受力分析图 图中; , ; ;以上了图中所示力的方向皆为事先假设力的方向，其中规定水平方向（x方向）向上为正，向下为负；竖直方向（y方向）向右为正，向左为负。4.4力和力矩的分析计算4.4.1铰架上端铰支受力先忽略平台自重，则由上图因为， 所以 而 （令，且有，为轴承滚轮与平台导轨槽间的摩擦系数） ，则至此能计算出 、 、 、4.4.2整体受力分析计算 对平台，重物及两铰架组成的整体进行受力分析：（4.1） =0 =0 . =0 . 4.4.3内、外铰架单独受力分析 对L1单独进行受力平衡分析： =0 =0 . =0 =0 .由、得 . 由、得 . 对L2单独进行受力平衡分析： =0 =0 . =0 =0 . 4.4.4力矩平衡分析 若规定逆时针为正，顺时针为负，则对L1的c点的转矩平衡得： =0 =0 （a） 对L2有： （1），d点的转矩平衡得： =0 =0 .（b） （2），o点的转矩平衡得： =0 =0 =0 .（c）又因为 .（d）轴承滚轮与底座导轨槽间的摩擦系数T= 206351.3 =26825.526826N大连交通大学2010届本科生毕业设计（论文）外文翻译附录附录1英文原文Definitions and Terminology of VibrationVibrationAll matter-solid, liquid and gaseous-is capable of vibration, e.g. vibration of gases occurs in tail ducts of jet engines causing troublesome noise and sometimes fatigue cracks in the metal. Vibration in liquids is almost always longitudinal and can cause large forces because of the low compressibility of liquids, e.g. popes conveying water can be subjected to high inertia forces (or “water hammer”) when a valve or tap is suddenly closed. Excitation forces caused, say by changes in flow of fluids or out-of-balance rotating or reciprocating parts, can often be reduced by attention to design and manufacturing details. Atypical machine has many moving parts, each of which is a potential source of vibration or shock-excitation. Designers face the problem of compromising between an acceptable amount of vibration and noise, and costs involved in reducing excitation.The mechanical vibrations dealt with are either excited by steady harmonic forces (i. e. obeying sine and cosine laws in cases of forced vibrations) or, after an initial disturbance, by no external force apart from gravitational force called weight ( i. e. in cases of natural or free vibrations). Harmonic vibrations are said to be “simple” if there is only one frequency as represented diagrammatically by a sine or cosine wave of displacement against time.Vibration of a body or material is periodic change in position or displacement from a static equilibrium position. Associated with vibration are the interrelated physical quantities of acceleration, velocity and displacement-e. g. an unbalanced force causes acceleration (a = F/m ) in a system which, by resisting, induces vibration as a response. We shall see that vibratory or oscillatory motion may be classified broadly as (a) transient; (b) continuing or steady-state; and (c) random.Transient Vibrations die away and are usually associated with irregular disturbances, e. g. shock or impact forces, rolling loads over bridges, cars driven over pot holes-i. e. forces which do not repeat at regular intervals. Although transients are temporary components of vibration motion, they can cause large amplitudes initially and consequent high stress but, in many cases, they are of short duration and can be ignored leaving only steady-state vibrations to be considered.Steady-State Vibrations are often associated with the continuous operation of machinery and, although periodic, are not necessarily harmonic or sinusoidal. Since vibrations require energy to produce them, they reduce the efficiency of machines and mechanisms because of dissipation of energy, e. g. by friction and consequent heat-transfer to surroundings, sound waves and noise, stress waves through frames and foundations, etc. Thus, steady-state vibrations always require a continuous energy input to maintain them.Random Vibration is the term used for vibration which is not periodic, i. e. has no made clear-several of which are probably known to science students already.Period, Cycle, Frequency and Amplitude A steady-state mechanical vibration is the motion of a system repeated after an interval of time known as the period. The motion completed in any one period of time is called a cycle. The number of cycles per unit of time is called the frequency. The maximum displacement of any part of the system from its static-equilibrium position is the amplitude of the vibration of that part-the total travel being twice the amplitude. Thus, “amplitude” is not synonymous with “displacement” but is the maximum value of the displacement from the static-equilibrium position.Natural and Forced Vibration A natural vibration occurs without any external force except gravity, and normally arises when an elastic system is displaced from a position of stable equilibrium and released, i. e. natural vibration occurs under the action of restoring forces inherent in an elastic system, and natural frequency is a property of he system.A forced vibration takes place under the excitation of an external force (or externally applied oscillatory disturbance) which is usually a function of time, e. g. in unbalanced rotating parts, imperfections in manufacture of gears and drives. The frequency of forced vibration is that of the exciting or impressed force, in the forcing frequency is an arbitrary quantity independent of the natural frequency of the system.Resonance Resonance describes the condition of maximum amplitude. It occurs when the frequency of an impressed force coincides with, or is near to a natural frequency of the system. In this critical condition, dangerously large amplitudes and stresses may occur in mechanical systems but, electrically, radio and television receivers are designed to respond to resonant frequencies. The calculation or estimation of natural frequencies is, therefore, of great importance in all types of vibrating and oscillating systems. When resonance occurs in rotating shafts and spindles, the speed of rotation is known as the critical speed. Hence, the prediction and correction or avoidance3 of a resonant condition in mechanisms is of vital importance since, in the absence of damping or other amplitude-limiting devices, resonance is the condition at which a system gives an infinite response to a finite excitation.Damping Damping is the dissipation of energy from a vibrating system, and thus prevents excessive response. It is observed that a natural vibration diminishes in amplitude with time and, hence, eventually ceases owing to some restraining or damping influence. Thus if a vibration is to be sustained, the energy dissipated by damping must be replaced from an external source.The dissipation is related in some way to the relative motion between the components or elements of the system, and is caused by frictional resistance of some sort, e.g. in structures, internal friction in material, and external friction caused by air or fluid resistance called “viscous” damping if the drag force is assumed proportional to the relative velocity between moving parts. One device assumed to give viscous damping is the “dashpot” which is a loosely fitting piston in a cylinder so that fluid can flow from one side of the piston to the other through the annular clearance space. A dashpot cannot store energy but can only dissipate it.Basic Machining Operations and Machine ToolsBasic Machining OperationsMachine tools have evolved from the early foot-powered lathes of the Egyptians and John Wilkinsons boring mill. They are designed to provide rigid support for both the work piece and the cutting tool and can precisely control their relative positions and the velocity of the tool with respect to the work piece. Basically, in metal cutting, a sharpened wedge-shaped tool removes a rather narrow strip of metal from the surface of a ductile work piece in the form of a severely deformed chip. The chip is a waste product that is considerably shorter than the work piece from which it came but worth a corresponding increase in thickness of the uncut chip. The geometrical shape of the machine surface depends on the shape of the tool and its path during the machining operation.Most machining operations produce parts of differing geometry. If a rough cylindrical work piece revolves about a central axis and the tool penetrates beneath its surface and travels parallel to the center of rotation, a surface of revolution is produced and the operation is called turning. If a hollow tube is machined on the inside in a similar manner, the operation is called boring. Producing an external conical surface of uniformly varying diameter is called taper turning. If the tool point travels in a path of varying radius, a contoured surface like that of a bowling pin a can be produced; or, if the piece is short enough and the support is sufficiently rigid, a contoured surface could be produced by feeding a shaped tool normal to the axis of rotation. Short tapered or cylindrical surfaces could also be contour formed.Flat or plane surfaces are frequently required. The can be generated by admiral turning or facing, in which the tool point moves normal to the axis of rotation. In other cases, it is more convenient to hold the work piece steady and reciprocate the tool across it in a series of straight-line cuts with a crosswise feed increment before each cutting stroke. This operation is called planning and is carried out on a shaper. For larger pieces it is easier to keep the tool stationary and draw the work piece under it as in planning. The tool is fed at each reciprocation. Contoured surfaces can be produced by using shaped tools.Multiple-edged tools can also be used. Drilling uses a twin-edged fluted tool for holes with depths up to 5 10times the drill diameter. Whether the drill turns or the work piece rotates, relative motion between the cutting edge and the work piece is the important factor. In milling operations a rotary cutter with a number of cutting edges engages the workspace which moves slowly with respect to the cutter. Plane or contoured surfaces may be produced, depending on the geometry of the cutter and the type of feed. Horizontal or vertical axes of rotation ma be used, and the feed of the work piece may be in any of the three coordinate directions.Basic Machine ToolsMachine tools are used to produce a part of a specified geometrical shape and precise size by removing metal from a ductile material in the form of chips. The latter are a waste product and vary from long continuous ribbons of a ductile material such as steel, which are undesirable from a disposal point of view, to easily handled well-broken chips resulting from cast iron. Machine tools perform five basic metal-removal processes: turning, planning, drilling, milling, and finding. All other metal-removal processes are modifications of these five basic processes. For example, boring is internal turning reaming, tapping, and counter boring modify drilled holes and are related to drilling; hobbling and gear cutting are fundamentally milling operations; hack sawing and broaching are a form of planning and honing; lapping, super finishing, polishing, and buffing are variants of grinding or abrasive removal operations. Therefore, there are only four types of basic machine tools, which use cutting tools of specific controllable geometry: 1.lathes, 2.planers, 3.drilling machines, and 4.milling machines. The grinding process forms chips, but the geometry of the abrasive grain is uncontrollable.The amount and rate of material removed by the various machining processes may be large, as in heavy turning operations, or extremely small, as in lapping or super finishing operations where only the high spots of a surface are removed.A machine tool performs three major functions: 1.it rigidly supports the work piece or its holder and the cutting tool; 2. it provides relative motion between the work piece and the cutting tools; 3. it provides a range of feeds and speeds usually ranging from 4 to 32 choices in each case.Speed and Feeds in MachiningSpeeds feeds, and depth of cut are the three major variables for economical machining. Other variables are the work and tool materials, coolant and geometry of the cutting tool. The rate of metal removal and power required for machining depend upon these variables.The depths of cut, feed, and cutting speed are machine settings that must be established in any metal-cutting operation. They all affect the forces, the power, and the rate of metal removal. They can be defined by comparing them to the needle and record of a phonograph. The cutting speed is represented by the velocity of the record surface relative to the needle in the tone arm at any instant. Feed is represented by the advance the needle radically inward per revolution, or is the difference in position between two adjacent grooves.Turning on Lathe CentersThe basic operations performed on an engine lathe are illustrated in Fig. Those operations performed on extremely surfaces with a single point cutting tool are called turning. Except for drilling, reaming, and tapping, the operations on internal surfaces are also performed by a single point cutting tool.All machining operations, including turning and boring, can be classified as roughing, finishing, or semi-finishing. The objective of a roughing operation is to remove the bulk of the material say rapidly and as efficiently as possible, while leaving a small amount of material on the work-piece for the finishing operation. Finishing operations are performed to brain the final size, shape, and surface finish on the work piece. Sometimes a semi-finishing operation will precede the finishing operation to leave a small predetermined and uniform amount of stood on the work-piece to be removed by the finishing operation.Generally, longer work pieces are turned while supported on one or two lathe centers. Cone shaped holes, called center holes, which fit the lathe centers are drilled in the ends of the work piece-usually along the axis of the cylindrical part. The end of the work piece adjacent to the tailstock is always supported by a tailstock center, while the end near the headstock may be supported by a headstock center or held in a chuck. The headstock end of the work piece may be held in a four-jar chuck, or in a cullet type chuck. This method holds the work piece firmly and transfers the power to the work piece smoothly; the additional support to the work piece provided by the chuck lessens the tendency for chatter to occur when cutting. Precise results can be obtained with this method if care is taken to hold the work piece accurately in the chuck.Very precise results can be obtained by supporting the work piece between two centers. A lathe dog is clamped to the work piece; together they are driven by a driver pate mounted on the spindle nose. One end of the work piece is machined; then the work piece can be turned around in the lathe to machine the other end. The center holes in the work piece serve as precise locating surfaces as well as bearing surfaces to carry the weight of the work piece and to resist the cutting forces. After the work piece has been removed from the lathe for any reason, the center holes will accurately align the work piece back in the lathe or in another lathe, or in a cylindrical grinding machine. The work piece must never be held at the headstock end by both a chuck and a lathe center. While at first thought this seems like a quick method of aligning the work piece in the chuck, this must not be done because it is not possible to press evenly with the jaws against the work piece while it is also supported by the center. The alignment provided by the center will not be maintained and the pressure of the jaws may damage the center hole, the lathe center, and perhaps even the lathe spindle. Compensating or floating jaw chucks used almost exclusively on high production work province an exception to the statements made above. These chucks are really work drivers and cannot be used for the same purpose as ordinary three or four=jaw chucks.While very large diameter work pieces are sometimes mounted on two centers, they are preferably held at the headstock end by faceplate jades to obtain the smooth power transmission; moreover, large lathe dogs that are adequate to transmit the power not generally available, although they can be made as a special. Faceplate jaws are like chuck jaws except that they are mounted on a faceplate, which has less overhang from the spindle bearings than a large chuck would have.BoringThe boring operation is generally performed in two steps; namely, rough boring and finish boring. The objective of the rough-boring operation is to remove the excess metal rapidly and efficiently, and the objective of the finish-boring operation is to obtain the desired size, surface finish, and location of the hole. The size of the hole is obtained by using the trial-cut procedure. The diameter of the hole can be measured with inside calipers and outside micrometer calipers. Basic Measuring Instruments, or inside micrometer calipers can be used to measure the diameter directly.Cored holes and drilled holes are sometimes eccentric with respect to the rotation of the lathe. When the boring tool enters the work, the boring bar will take a deeper cut on one side of the hole than on the other, and will deflect more when taking this deeper cut, with the result that the bored hole will not be concentric with the rotation of the work. This effect is corrected by taking several cuts through the hole using a shallow depth of cut. Each succeeding shallow cut causes the resulting hole to be more concentric than it was with the previous cut. Before the final, finish cut is taken; the hole should be concentric with the rotation of the work in order to make certain that the finished hole will be accurately located.Shoulders, grooves, contours, tapers, and threads are bored inside of holes. Internal grooves are cut using a tool that is similar to an external grooving tool. The procedure for boring internal shoulders is very similar to the procedure for turning shoulders. Large shoulders are faced with the boring tool positioned with the nose leading, and using the cross slide to feed the tool. Internal contours can be machined using a tracing attachment on a lathe. The tracing attachment is mounted on the cross slide and the stylus follows the outline of the master profile plate. This causes the cutting tool to move in a path corresponding to the profile of the master profile plate. Thus, the profile on the master profile plate is reproduced inside the bore. The master profile plate is accurately mounted on a special slide which can be precisely adjusted in two directions, in two directions, in order to align the cutting tool in the correct relationship to the work. This lathe has a cam-lick type of spindle nose which permits it to take a cut when rotating in either direction. Normal turning cuts are taken with the spindle rotating counterclockwise. The boring cut is taken with the spindle revolving in a clockwise direction, or “backwards”. This permits the boring cut to be taken on the “back side” of the bore which is easier to see from the operators position in front of the lathe. This should not be done on lathes having a threaded spindle nose because the cutting force will tend to unscrew the chuck. 中文翻译振动的定义和术语振动所有的物质-固体，液体和气体-都能够振动，例如，在喷气发动机尾部导管中产生的气体振动会发出令人讨厌的噪声，而且有时还会使金属产生疲劳裂缝。液体中的振动总是纵向的，而且由于液体的可压缩性低，这种振动还会产生很大的力。例如，当输水管道的阀门或水龙头突然关闭时，管道会遭受很大的惯省性力的作用（或称为水击）。诸如，由于液体流动状态改变或者转动，往复运动零件推动平衡所产生的激振力，一般可以通过对各零件的精心设计和制造来使用权其得到降低。一台常见的机器中有许多运动零件，每个零件都是潜在的振动源或冲击激振源。设计人员需要处理好振动与噪声的允许值与降低激振所需要的费用之间的关系。所讨论的振动或者由稳态的谐振力引起的振动（也就是服从正弦或余弦定律的强迫振动），或者是在初始扰动之后，除了被称为重量的重力之外，没有其他外力引起的振动（也就是自然或自由振动的情况）。如果仅用一个频率的正弦或余弦波图形就可表示位移与时间的关系，谐振就被认为是“简单的”。一个物体或一种材料在振动时，它相对于静平衡位置的位置变化或位移是周期性的。与振动有关的物理量是相互关联的加速度，速度和位移。例如，一个不平衡的力在系统中造成的加速度（a =F/m）会因为系统的抵抗而引起振动作为响应。可以看到，振动或者振荡大致可以分为三类：（1）瞬态的，（2）连续的或稳态的，（3）随机的。瞬态振动是逐渐衰减的，而且通常与不规则的扰动有关，例如，滚动载荷通过桥梁，汽车通过坑洞，也就是在确定的期间内不重复的力。尽管瞬态振动是振动的暂时性成分它们能够产生大初始振幅和引起高的应力。在大多数情况下，它们持续的时间很短，因而人们可以将其忽略不计而只考虑稳态振动。稳态振动通常和机器的连续运转在关，而且尽管这种振动是周期性的，但不一定是谐振或正弦振动。由于需要能量才能产生振动，因此，振动消耗了能量，降低了机器和机构的效率。能量的消耗有多种方式，磨擦和随后将所产生的热传到周围，声波和噪声，以及通过机架与基础的应力波等到。因此稳态振动总是需要连续的能量输入来维持其存在。随机振动是一个用来描述非周期性振动的术语。也就是说，这种振动不是周期性变化的，是不定期地进行重复的。在下面段落中，对一些与振动有关的术语和定义加以明确，其中一些可能是理科学生都已经清楚了的。周期，循环，频率和振幅。 稳态机械振动是系统在一定时间范围内的重复运动，该时间范围被称为周期。在任何一个周期内所完成的运动，被子称为一个循环。每个单位时间内的循环数目被称为频率。系统任何部分离开它的静平衡位置的最大位移就是该部分振动的振幅，总的行程是振幅的两倍。因此，“振幅”并不是“位移”的同义词，而是距离静平衡位置的位移最大值。自由振动和强迫振动。除了重力以外，在没有任何其他作用时产生的振动称为自由振动。通常一个弹性系统离开它的稳定平衡位置后且被松开时，这个系统就会产生振动。也就是说，自由振动是在弹性系统固有弹性恢复力的作用下产生的，而固有频率则是系统的一个特性。强迫振动是在外力的激励（或者外部的振荡性干扰）下产生的。这个激励或干扰通常是时间的函数。例如，在不平衡的转动部件中，或者是在有缺陷的齿轮和传动装置中就会产生这种振动。强迫振动的频率就是激振力或者外部施加的力的频率。也就是说，强迫振动的频率是一个与系统固有频率没有关系的任意量。共振。共振描述了最大振幅的状况。当外力的频率与系统的固有频率相同或相近时就会产生共振。在这种临界条件下，机械系统中出现具有危险性的在振幅和高应力。但是，电学上，收音机和电视机的接收器则被设计成在共振频率时工作。因此，在所有各种振动或振荡系统中，计算或者估计系统的固有频率是非常重要的。阻尼。阻尼是振动系统中能量被消耗的现象，它可以防止过量的响应。可以观察到，自由振动的振幅会随时间而衰减，因而，振动最终将由于某些限制或阻尼的影响而停止。因此，如果要使振动持续下去，一定要有外部的能源对由于阻尼而耗散的能量进行补充。能量耗散以某种方式与系统的部件或元件之间的相对运动有关，它是由于某种类型的磨擦引起的。例如，在结构中，材料内部的磨擦和由空气可液体阻力等造成的外部磨擦被称为“粘性”阻尼，在这里假定阻力与运动部件之间的速度成正比。一种能够提供黏性阻尼的装置被称为“阻尼器”。它是由一个缸体与一个活塞松驰配合形成的，液体能够从活塞的一端通过环形间隙流到另一端。阻尼器不能存储能量，仅能消耗能量。基本的加工工序和机床基本的加工工序机床是从早期的埃及人的脚踏动力车床和约翰威尔金森的镗床发展而来。它们用于为工件和刀具两者提供刚性支承并且可以精确控制它们的相对位置和相对速度。基本上讲，在金属切削中一个磨尖的楔形工具以紧凑螺纹形的切屑形式从有韧性工件表面去除一条很窄的金属。切屑是废弃的产品，与其工件相比相当短但是比未切屑的部分有相对的增加。机器表面的几何形状取决于刀具的形状以及加工操作过程中刀具的路径。大多数加工工序生产出不同几何形状的部件。如果一个粗糙的柱形工件绕中心轴旋转而且刀具穿破工件表面并沿与旋转中心平行的方向前进，就会产生一个旋转面，这道工序叫车削。如果以类似的方式加工一根空心管的内部，则这道工序就叫镗削。制造一个直径均匀变化的锥形外表面叫做锥体