0.75型卷扬机设计【绞车】【载荷7.5KN; 速度30m min; 卷筒容绳量100m; 卷筒尺寸φ180mm】【说明书+CAD】
0.75型卷扬机设计【绞车】【载荷7.5KN; 速度30m min; 卷筒容绳量100m; 卷筒尺寸180mm】【说明书+CAD】,绞车,载荷7.5KN 速度30m min 卷筒容绳量100m 卷筒尺寸180mm,说明书+CAD,0.75型卷扬机设计【绞车】【载荷7.5KN,速度30m,min,卷筒容绳量100m,卷筒尺寸180mm】【说明书+CAD】,卷扬机
任务书工 学院 系 专业 级 班学 号 学生 指导教师 设计题目 0.75型卷扬机设计 设计工作内容与基本要求(目标、任务、途径、方法,应掌握的原始资料(数据)、参考资料(文献)以及设计技术要求、注意事项等)一、设计技术要求、原始资料(数据)、参考资料(文献)通过实习调研搜集资料,运用所学知识,借助CAXA或AutoCAD软件,进行总体结构设计及各主要零部件结构如:电机、减速器与制动器选择、钢丝绳选择、卷筒结构的设计与计算等。主要参数:额定载荷7.5 KN; 额定速度30 m/min; 卷筒容绳量100 m; 卷筒尺寸180mm。通过该毕业设计,使学生对大学四年里学到和未学到的知识进行综合强化训练,为其走向工作岗位奠定良好基础。二、设计目标与任务1.查阅文献资料12种以上,外文资料不少于两种。写出3000字以上文献综述,单独装订成册。2.翻译外文科技资料,不少于3000汉字,单独装订成册。3. 完成总体方案设计。4.选择并论证设计传动方案、整机结构草图,完成主要零部件的强度校核计算。5.绘制装配图、主要零部件图,折合零号图纸两张以上。6.编写摘要,英中文完全对照,中文不少于300字。7.编写设计说明书,不少于8000字符。三、时间安排1-9周 完成文献综述及英文资料翻译。完成实习。总体结构设计、计算用CAXA或AutoCAD等软件绘制总装图、部装图、典型零件图。10-12周 编写设计说明书,进一步修改完善毕业设计,准备并完成答辩稿答辩。设计时间: 2012 年 02 月 13 日至 2012 年 05 月 15 日计 划 时 间: 2012 年 05 月 19 日专业(教研室)审批意见:审批人签名:开题报告表课题名称0.75型卷扬机设计课题来源课题类型指导教师学生姓名专 业学 号一、调研资料的准备根据任务书的要求,在做本课题前,查阅了与课题相关的资料有:机电一体化技术与系统,液压与气压传动,CAD软件制图,机械设计手册等相关教材。二、设计的目的与要求 设计是大学教学中最后一个实践性教学环节,通过该设计过程,可以检验我们在大学期间所学的知识,同时培养我们处理工程中实际问题的能力,因此意义特别重大。通过对题目的理解,查阅各种资料,设计出专用的0.75型卷扬机,以满足实际的工作需求! 三、设计的思路与预期成果 1、设计思路1) 首先:根据本次设计相关要求查找资料,做好准备。2) 其次:依据要实现的功能要求计算并选择或设计合适的电机,画出装配图。3) 最后:根据装配图画出零件图!2、预期的成果(1)完成文献综述一篇,不少于3000字,与专业相关的英文翻译一篇,不少于3000字。 (2)完成内容与字数都不少于规定量的设计说明书一份。(3)绘制装配图,部分零件图。四、任务完成的阶段内容及时间安排 1周 4周 收集设计资料并完成开题报告,完成英文资料翻译并写出文献综述 5周 10周 进行总体设计和部分零部件的选择与设计 7周11周 绘制装配图和部分零件图、编写设计说明书,修改整理,准备答辩五、完成设计所具备的条件因素具备机械设计、气压与液压传动、能有效借助图书馆的相关文献资料,相关的网络等资源,查阅机械设计手册、组合机床设计手册设计指导手册并且具有良好的计算机绘图(CAD)操作能力。指导教师签名: 日期: 2012-2-22 课题来源:(1)教师拟订;(2)学生建议;(3)企业和社会征集;(4)科研单位提供课题类型:(1)A工程设计(艺术设计);B技术开发;C软件工程;D理论研究;E调研报告 (2)X真实课题;Y模拟课题;Z虚拟课题要求(1)、(2)均要填,如AY、BX等。 第 6 页 卷扬机的应用及发展摘要:本文简要介绍了卷扬机的应用领域,卷扬机结构组成及特点,卷扬机的作用以及使用时的注意事项。国内外卷扬机的发展状况。通过这些对卷扬机有一个大致的了解,为设计做准备。关键词:卷扬机,应用,国内外,发展前言卷扬机又叫绞车,是由人力或机械动力驱动卷筒、卷绕绳索来完成牵引工作的装置。可以垂直提升、水平或倾斜拽引重物。卷扬机分为手动卷扬机和电动卷扬机两种。现在以电动卷扬机为主。电动卷扬机由电动机、联轴节、制动器、减速器和卷筒组成,共同安装在机架上。对于起升高度和装卸量大工作频繁的情况,调速性能好,能令空钩快速下降。在很久以前的古代,就知道来用辘轳等来提升重物,以减轻体力劳动的强度和提高劳动生产率。1. 国内卷扬机的应用与发展在我国,解放前卷扬机只有在一些大型企业中才被使用,应用很少,而且所使用的卷扬机也均为国外生产,国内基本上没有生产卷扬机的厂家。我国卷扬机的生产是解放后才开始的。50年代为满足恢复经济的需要和第一个五年计划的得要,卷扬机的生产被提到了日程上。原沈阳国泰机器厂(阜新矿山机械厂前身)等成批仿制了两种卷扬机,一种为日本的JIS8001型动力卷扬机,它是一种原动机为电动机动型式是开式圆柱齿轮传动,双锥体摩擦离合器,操作为手扳脚踩的快速卷扬机,另一种是按苏联图纸制造的1011型和1012型普通蜗杆传动、电控慢速卷扬机。由于当时生产力不高,卷扬机的需求量亦不多,故这段时间国内卷扬机的生产主要是仿制。 随着生产力的发展,到了60年代,卷扬机的生产和使用越来越多。为了协调生产,卷扬机主要生产厂家(阜新矿山机械厂、天津卷扬机厂、山西机器广、宝鸡起重运输机厂等)组成了卷扬机行业组织,隶属于第一机械工业部矿山机械行业。为了发展卷扬机的生产,行业组织了有关厂家的人员对全国卷扬机的生产相应用情况进行了调查。在调查的基础上,开始自行设计和制造新的卷扬机,先后试制了0.5t、lt、3t电动卷扬机,但由于对当时各厂家的生产能力估计不足,无法推广。从70年代起,我国卷扬机的生产进入了技术提高、品种增多的新阶段。在各厂自行设计和生产的基础上,1973年,由卷扬机行业组织了有关厂家和院校联合进行了卷扬机基型设计,并充分考虑到了当时中小厂家的生产能力。快速卷扬机的基型采用半开半闭式齿轮传动,离合器采用单锥面石棉橡胶摩擦带结构,操纵用手板刹车带制动。慢速卷扬机的基型式为闭式传动(圆柱齿轮传动或蜗杆传动减速器)、电磁铁制动结构。这两种基型一直到现今还在生产。为适应生产发展的需要,当时第一机械工业部发布了JB92674卷扬机型式与基本参数和JBl80376卷扬机技术条件两个部标准,并把卷扬机行业划归常德机械研究所(长沙机械研究院前身)领导。随着部标准的颁布,使卷扬机有了大发展的基础。在此期间,由于石化工业的发展,大型设备很多,都需要吊装,如一些大型反应塔,塔的高度达七八十米,质量达五六百吨,就需要有大型吊装用的卷扬机,因而各厂家相继生产了20t和32t卷扬机,满足了经济发展的需要。80年代以后,各种竞争机制的引入,科技是第一生产力的概念逐渐被人们所认识,所接受。是我国卷扬机设计制造技术发展最快的时期。国家也制定了有关卷扬机的配套标准、规范。新产品种数近十个,其中最具有代表性的产品有福建省建筑机械厂的行星传动卷扬机、昆明建筑机械厂的少齿差传动卷扬机、长沙建筑机械研究所与福州市建筑机械厂联合开发的仿日本Seibu公司采用立式齿轮传动的电控卷扬机广州市一建公司机械厂的高速卷扬机适应高层建筑的多功能需要,而江苏海门第三机械厂引进专利技术开发的系列多排顶杆蠕动传动的卷扬机分为三大系列:即电控、手控和微机程控三大类,其练台性能优于代表国际先进承平的Seibu一字型卷扬机,使我国的建筑卷扬机技术跨人世界先进行列。1991年10月通过的省科委组织的专家鉴定意见:该产品整机组合合理、结构紧凑、重量轻、过载能力强、工作安全可靠,与同类产品相比,居国内先进水平,其中传动方式部分的设计构思独特、新颖,受力均匀、合理,属国内外首创。进入新世纪以来,各行各业都有飞速发展,近些年数控机床的广泛应用,信息技术和数控技术日趋成熟,使得机械制造的效率提高、成本降低,这些都将推动卷扬机工业的发展。2. 国外卷扬机的应用与发展在国外,卷扬机的品种繁多,应用也很广泛,在西方技术先进的国家,虽然工业水平先进,机械化程度不断提高,起重设备也不断更新,但仍不能淘汰掉这样的行之有效的简单机械设备,下面介绍一下几个主要国家生产卷扬机的状况。(一) 美国美国生产卷扬机的厂家有近百家,主要有贝波(BEEBE)国际有限公司,哲思(THERN)有限公司等。贝波国际有限公司是美国较大的生产起重设备的公司,主要产品有各种手动卷扬机,电动卷扬机,提升机械及起重机。手动卷扬机重要品种有蜗杆传动系列,直齿圆柱齿轮系列,齿轮蜗杆传动组合系列,直接驱动系列,链传动系列。其中直间驱动式电动卷扬机的传动是全封闭行星齿轮传动,传动系列全部全部安装在卷筒里面,机架和卷筒用高强度钢焊接而成 。(二) 日本日本从明治30年开始制造和使用卷扬机。据日本荷役机械研究所设计,19701975年间卷扬机的产量增加62.5%。据日本通产省机械核计月报载,接年单纯土卷扬机的产量就达12万台,生产值约100亿日元。日本卷扬机行业由机械技术部会,荷役机械技术委员会领导.主要生产厂家有北川铁工所,远藤钢机,南星,越野总业,松岗产业等80多个产业。(三) 法国法国生产卷扬机的厂家很多,其中包藤(POTAIN)公司就是生产卷扬机的主要商家之一。包藤公司主要生产KUSW系列卷扬机,LMD系列卷扬机,PC系列卷扬机和RCS系列卷扬机。(四)国外卷扬机的发展史1、大型化由于基础工业的发展,大型设备和建筑构件要求整体安装,促进了大型卷扬机的发展。目前,俄罗斯已生产了60t的卷扬机,日本生产了32t,50t,60t液压和气动卷扬机,美国生产了136t和270t卷扬机。 2、采用先进电子技术为了实现自动控制和遥控,国外采用了先进的电子技术。对大型卷扬机安装了电器连锁装置,以保证绝对的安全可靠。3、发展手提式卷扬机 为了提高机械化水平,减轻工人劳动强度,国外发展小型手提式卷扬机,如以汽车蓄电池为动力的直流电动小型卷扬机。4、大力发展不带电源装置的卷扬机欧美国家非常重视发展借助汽车和拖拉机动力的卷扬机。此种卷扬机结构简单,有一个卷筒和一个变速箱即可。提升重物是卷扬机的一种主要功能,所以各类卷扬机的设计都是根据这一要求为依据的。虽然目前塔吊、汽车吊等取代了卷扬机的部分工作,但由于塔吊成本高,一股在大型工程中使用,而且灵活性较差,故一般中小型工程仍然广泛应用卷扬机,汽车吊虽然灵活方便,但也因为成本太高,而不能在工程中广泛应用,故大多设备的安装仍然是由卷扬机承担的。卷扬机除在工程、设备安装等方面被广泛应用外,在冶金、矿山、建筑、化工、水电、农业、军事及交通运输等行业亦被广泛应用,还可作现代化电控自动作业线的配套设备。电机经减速机带动钢丝绳滚筒,收放钢丝绳,通过不同的滑轮改变方向。工艺要求主要是滚筒转速即钢丝绳运动速度和制动系统的安全可靠性。卷扬机属于较简单的提升或牵引机械。主要是用电动机作为原动机,由于电动机输出的转速远远大于卷扬机中滚筒的转速,故必须设计减速的传动装置。传动装置的设计有多种多样,如皮带减速器、链条减速器、齿轮减速器、涡轮蜗杆减速器、二级齿轮减速器等等。通过合理的设计传动装置,使得卷扬机能够在特定的工作环境下满足正常的工作要求。机械设计是为实现高等院校机械类专业培养高级应用型、技术型人才培养目标所必须的实践性教学环节。通过设计强化学生对基本知识和基本技能的理解和掌握,培养学生收集资料和调查研究的能力,一定的方案比较、论证的能力,一定的理论分析与设计运算能力,以及编写编制能力。同时掌握资料的收集和分析、相关规范的选择和运用;设计方案的选择、成果图的绘制以及设计文本的编制全过程。另外对培养学生独立思考问题和解决问题的能力,为今后工作做好技术储备,都具有十分重要意义。通过设计,学生可以巩固和提高学过的基础理论和专业知识;提高运用所学专业知识进行独立思考和综合分析、解决实际问题的能力;培养掌握正确的思维方法和利用计算机解决实际问题的基本技能;增强对信息管理工作的认识,掌握信息处理方法,进行编制技术文件等基本技能的训练,使之具有一定程度的实际工作能力;掌握文献检索、资料查询的基本方法以及获取新知识的能力;促使学习和获取新知识,掌握自我学习的能力。通过参与实际工作,学生可以更了解工作,具备一定的实际工作能力。就本次设计而言,本人可以熟悉卷扬机的工作原理,其各部分机构及零件的设计计算,对所学过的机械制图、工程力学、工程材料、机械设计基础和公差知识进行一次综合运用。这对以后的机械专业工作会有很大帮助。参考文献1齐国志 建筑卷扬机的设计 机械工业出版社 19962龚桂义 机械设计课程设计指导书 高等教育出版社 19823龚桂义 机械设计课程设计图册 哈尔滨工业大学出版社 19454机械设计手册 机械工业出版社 20035刘鸿文 材料力学 高等教育出版社 19926周明衡 离合器制动器选用手册 化工工业出版社 20037汪恺 机械设计标准应用手册 机械工业出版社 19978成大先 机械设计手册 化工工业出版社 19939胡家秀 简明机械零件设计选用手册 机械工业出版社 199910齿轮手册编委会 齿轮手册(第二版)北京:机械工业出版社,200411罗伯特 机械设计中的机械零件(第三版)北京:机械工业出版社,200412徐灏 疲劳强度设计 北京:机械工业出版社 198513陈裕成 建筑机械与设备 北京:北京理工大学出版社 200914孔庆华 母福生刘传绍 极限配合与测量技术基础 上海:同济大学出版社200815张顺心 工程图学基础 北京:机械工业出版社200716Manually operated windlass mechanism for portable elevators application filed apr.19.191317Automatic braking arrangement for a windlass Jan van Gennep,715 Laurel Ave, Menlo Park, Calif.94025 Mar.20,1975 设计文献综述 院(系)名称 专业名称 学生姓名 指导教师 2012年 03 月 10 日 第 27 页 原文说明原文说明的内容是:文章阐述了电机的工作原理、发展过程、以及伺服电机的工作控制原理。并且举例说明了伺服电机所适用的场合。题名:Servomotors Elements and Applications作者: NEWMARKERHow Does a Motor Work?An electric motor converts electricity into mechanical motion. Electric motors are used in household appliances, electric fans, remote-controlled toys, and in thousands of other applications. The electric motor grew out of one of the earliest discoveries in electric scienceAragos rotations. In 1824, Francois Arago discovered that a magnetic needle suspended over a copper disk would rotate when the disc was spun. The next year, computer pioneer Charles Babbage and astronomer John Herschel showed that the action could be reversed: spinning a more powerful magnet above the copper disk would spin the copper disc. Then, in 1831, Michael Faraday conducted experiments that helped explain why this took place. While this laid the groundwork for the electric motor, it was another half century before electric motors were doing useful work. Over the next few decades many inventors made improved devices for turning electricity into motion. One of these was Hippolyte Pixiis 1832 improvement called the commutator, which switched the flow of current between two or more sets of stationary electromagnets to keep a motor continuously rotating. Thomas Davenport was the first to build an electric motor large enough to be used in industry, and he was also the first to seek a patent on a motor. Soon electric motors were being used for such things as transportation. Moritz-Hermann De Jacobi used an electric motor on a boat on the Neva River, and Charles G. Page used one to build a small locomotive. After the appearance of commercial electric power systems in the 1880s, larger electric motors were possible. Edison encouraged the use of electric motors in industrial applications and designed several new electric motors for that purpose. An important change came in the later 1880s and 1890s, when electric power companies began considering the switch to alternating current. Alternating current was perfect for the distribution of electric power over long distances, and it worked well with the Edison electric lamp, but no practical AC motor existed until the works of Galileo Ferraris in Italy and Nikola Tesla in the United States. Teslas contributions are remembered today more than Ferraris in part because Tesla was subsequently hired by the Westinghouse corporation, which used his patents along with many others to become one of the major producers of electric equipment. With a suitable AC motor available, AC power took off. It is still in use today.ServomotorServomotors are available as AC or DC motors. Early servomotors were generally DC motors because the only type of control for large currents was through SCRs for many years. As transistors became capable of controlling larger currents and switching the large currents at higher frequencies, the AC servomotor became used more often. Early servomotors were specifically designed for servo amplifiers. Today a class of motors is designed for applications that may use a servo amplifier or a variable-frequency controller, which means that a motor may be used in a servo system in one application, and used in a variable-frequency drive in another application. Some companies also call any closed-loop system that does not use a stepper motor a servo system, so it is possible for a simple AC induction motor that is connected to a velocity controller to be called a servomotor.Some changes that must be made to any motor that is designed as a servomotor includes the ability to operate at a range of speeds without overheating, the ability to operate at zero speed and retain sufficient torque to hold a load in position, and the ability to operate at very low speeds for long periods of time without overheating. Older-type motors have cooling fans that are connected directly to the motor shaft. When the motor runs at slow speed, the fan does not move enough air to cool the motor. Newer motors have a separate fan mounted so it will provide optimum cooling air. This fan is powered by a constant voltage source so that it will turn at maximum RPM at all times regardless of the speed of the servomotor. One of the most usable types of motors in servo systems is the permanent magnet (PM) type motor. The voltage for the field winding of the permanent magnet type motor can be AC voltage or DC voltage. The permanent magnet-type motor is similar to other PM type motors presented previously. Figure-1 shows a cutaway picture of a PM motor and Fig.-2 shows a cutaway diagram of a PM motor. From the picture and diagram you can see the housing, rotor and stator all look very similar to the previous type PM motors. The major difference with this type of motor is that it may have gear reduction to be able to move larger loads quickly from a stand still position. This type of PM motor also has an encoder or resolver built into the motor housing. This ensures that the device will accurately indicate the position or velocity of the motor shaft.FIGURE 1-1 Typical PM servomotorsFIGURE 1-2 Cutaway picture of a permanent magnet servomotorBrushless ServomotorsThe brushless servomotor is designed to operate without brushes. This means that the commutation that the brushes provided must now be provided electronically. Electronic commutation is provided by switching transistors on and off at appropriate times. Figure 1-3 shows three examples of the voltage and current waveforms that are sent to the brushless servomotor. Figure 1-4 shows an example of the three windings of the brushless servomotor. The main point about the brushless servomotor is that it can be powered by either ac voltage or dc voltage. FIGURE 1-3 (a) Trapezoidal input voltage and square wave current waveforms. (b) Sinusoidal input voltage and sinusoidal voltage and square wave output voltage waveforms. (c) Sinusoidal input voltage and sinusoidal current waveforms. This has become the most popular type of brushless servomotor control.Figure 1-4 shows three sets of transistors that are similar to the transistors in the output stage of the variable-frequency drive. In Fig. l-4a the transistors are connected to the three windings of the motor in a similar manner as in the variable-frequency drive. In Fig. l-4b the diagram of the waveforms for the output of the transistors is shown as three separate sinusoidal waves. The waveforms for the control circuit for the base of each transistor are shown in Fig. l-4c. Figure l-4d shows the back EMF for the drive waveforms. FIGURE 11-86 (a) Transistors connected to the three windings of the brushless servomotor. (b) Waveforms of the three separate voltages that are used to power the three motor windings. (c) Waveforms of the signals used to control the transistor sequence that provides the waveforms for the previous diagram, (d) Waveform of the overall back EMFServomotor Controllers Servomotor controllers have become more than just amplifiers for a servomotor. Today servomotor controllers must be able to make a number of decisions and provide a means to receive signals from external sensors and controls in the system, and send signals to host controllers and PLCs that may interface with the servo system. Figure 1-5 shows a picture of several servomotors and their amplifiers. The components in this picture look similar to a variety of other types of motors and controllers. FIGURE 1-5 Example servomotors and amplifiersFigure 1-6 shows a diagram of the servomotor controller so that you can see some of the differences from other types of motor controllers. The controller in this diagram is for a DC servomotor. The controller has three ports that bring signals in or send signals out of the controller. The power supply, servomotor, and tachometer are connected to port P3 at the bottom of the controller. You can see that the supply voltage is 115-volt AC single phase. A main disconnect is connected in series with the LI wire. The LI and N lines supply power to an isolation step-down transformer. The secondary voltage of the trans-former can be any voltage between 20 and 85 volts. The controller is grounded at terminal 8. You should remember that the ground at this point is only used to provide protection against short circuits for all metal parts in the system. The servomotor is connected to the controller at terminals 4 and 5. Terminal 5 is + and terminal 4 is - . Terminal 3 provides a ground for the shield of the wires that connect the motor and the controller. The tachometer is connected to terminals 1 and 2. Terminal 2 is + and terminal 1 is - . The shield for this cable is grounded to the motor case. The wires connected to this port will be larger than wires connected to the other ports, since they must be capable of carrying the larger motor current. If the motor uses an external cooling fan, it will be connected through this port. In most cases the cooling fan will be powered by single-phase or three-phase AC voltage that remains at a constant level, such as 110 volts AC or 240 volts AC. FIGURE 1-6 Diagram of a servo controller. This diagram shows the digital (on-off) signals and the analog signals that are sent to the controller, and the signals the controller sends back to the host controller or PLC.The command signal is sent to the controller through port PI. The terminals for the command signal are 1 and 2. Terminal 1 is + and terminal 2 is - . This signal is a type signal, which means that it is not grounded or does not share a ground potential with any other part of the circuit. Several additional auxiliary signals are also connected through port 1. These signals include inhibit (INH), which is used to disable the drive from an external controller, and forward and reverse commands (FAC and RAC), which tell the controller to send the voltage to the motor so that it will rotate in the forward or reverse direction. In some applications, the forward maximum travel limit switch and reverse maximum travel limit switch are connected so that if the machine travel moves to the extreme position so that it touches the overtravel limit switch, it will automatically energize the drive to begin travel in the opposite direction. Port PI also provides several digital output signals that can be used to send fault signals or other information such as drive running back to a host controller or PLC. Port PI basically is the interface for all digital (on-off) signals. Port P2 is the interface for analog (0-max) signals. Typical signals on this bus include motor current and motor velocity signals that are sent from the servo controller back to the host or PLC where they can be used in verification logic to ensure the controller is sending the correct information to the motor. Input signals from the host or PLC can also be sent to the controller to set maximum current and velocity for the drive. In newer digital drives, these values are controlled by drive parameters that are programmed into the drive. PWM Servo Amplifier The PWM servo amplifier is used on small-size servo applications that use DC brush-type servomotors. Figure 1-7 shows a diagram for this type of amplifier. From the diagram you can see that single-phase AC power is provided to the amplifier as the supply at the lower left part of the diagram. The AC voltage is rectified and sent to the output section of the drive that is shown in the top right comer of the diagram. The output section of the drive uses four IGBTs to create the pulse-width modulation waveform. The IGBTs are connected so that they provide 30-120 volts DC and up to 30 A to the brush-type DC servo-motor. The polarity of the motor is indicated in the diagram. The remaining circuits show a variety of fault circuits in the middle of the diagram that originate from the fault logic board and provide an output signal at the bottom of the diagram. You should notice that the fault output signals include overvoltage, overtemperature, and overcurrent. A fourth signal is identified as SSO (system status output), which indicates the status of the system as faulted anytime a fault has occurred. A jumper is used to set the SSO signal as an open collector output with a logic level 1 indicating the drive is ready, or as a normally closed relay indicating the drive is ready. The input terminals at the bottom right part of the diagram are used to enable or inhibit the drive, and to select forward amplifier clamp (FAC) or reverse amplifier clamp (RAC). The inhibit signal is used as a control signal, since it inhibits the output stage of the amplifier if it is high. The FAC and RAC signals limit the current in the opposite direction to 5%. The input signals are shown in the diagram at the upper left side. The VCS (velocity command signal) requires a +VCS and a -VCS signal to provide the differential signal. FIGURE 1-7 Diagram of a pulse-width modulator (PWM) amplifier with a brush-type DC servomotorApplications for Servo Amplifiers and Motors You will get a better idea of how servomotors and amplifiers operate if you see some typical applications. Figure 1-8 shows an example of a servomotor used to control a press feed. In this application sheet material is fed into a press where it is cut off to length with a knife blade or sheer. The sheet material may have a logo or other advertisement that must line up registration marks with the cut-off point. In this application the speed and position of the sheet material must be synchronized with the correct cut-off point. The feed-back sensor could be an encoder or resolver that is coupled with a photoelectric sensor to determine the location of the registration mark. An operator panel is provided so that the operator can jog the system for maintenance to the blades, or when loading a new roll of material. The operator panel could also be used to call up parameters for the drive that correspond to each type of material that is used. The system could also be integrated with a programmable controller or other type of controller and the operator panel could be used to select the correct cutoff points for each type of material or product that is run. FIGURE 1-8 Application of a servomotor controlling the speed of material as it enters a press for cutting pieces to size.An Example of a Servo Controlled In-Line Bottle-Filling ApplicationA second application is shown in Fig. 1-9. In this application multiple filling heads line up with bottles as they move along a continuous line. Each of the filling heads must match up with a bottle and track the bottle while it is moving. Product is dispensed as the nozzles move with the bottles. In this application 10 nozzles are mounted on a carriage that is driven by a ball-screw mechanism. The ball-screw mechanism is also called a lead screw. When the motor turns the shaft of the ball screw, the carriage will move horizontally along the length of the ball-screw shaft. This movement will be smooth so that each of the nozzles can dispense product into the bottles with little spillage. The servo drive system utilizes a positioning drive controller with software that allows the position and velocity to be tracked as the conveyor line moves the bottles. A master encoder tracks the bottles as they move along the conveyor line. An auger feed system is also used just prior to the point where the bottles enter the filling station. The auger causes a specific amount of space to be set between each bottle as it enters the filling station. The bottles may be packed tightly as they approach the auger, but as they pass through the auger their space is set exactly so that the necks of the bottles will match the spacing of the filling nozzles. A detector is also in conjunction with the dispensing system to ensure that no product is dispensed from a nozzle if a bottle is missing or large spaces appear between bottles. FIGURE 1-9 Application of a beverage-filling station controlled by a servomotorThe servo drive system compares the position of the bottles from the master encoder to the feedback signal that indicates the position of the filling carriage that is mounted to the ball screw. The servo drive amplifier will increase or decrease the speed of the ball-screw mechanism so that the nozzles will match the speed of the bottles exactly. An Example of a Servo Controlled Precision Auger Filling System A third application for a servo system is provided in Fig. 1-10. In this application a large filling tank is used to fill containers as they pass along a conveyor line. The material that is dispensed into the containers can be a single material fill or it can be one of several materials added to a container that is dumped into a mixer for a blending operation. Since the amount of material that is dispensed into the container must be accurately weighed and metered into the box, an auger that is controlled by a servo system is used. The feedback sensor for this system can be a weighing system such as the load cell discussed in earlier chapters. The command signal can come from a programmable controller or the operator can enter it manually by selecting a recipe from the operators terminal. The amount of material can be different from recipe to recipe. FIGURE 1-10 Application of a precision auger filling station controlled by a servomotor.The speed of the auger can be adjusted so that it runs at high speed when the container is first being filled, and the speed can be slowed to a point where the final grams of material can be metered precisely as the container is filled to the proper point. As the price of material increases, precision filling equipment can provide savings as well as quality in the amount of product used in the recipe. An Example of a Label Application Using Servomotors The fourth application has a servomotor controlling the speed of a label-feed mechanism that pulls preprinted labels from a roll and applies them to packages as they move on a continuous conveyor system past the labeling mechanism. The feedback signals are provided by an encoder that indicates the location of the conveyor, tach generator that indicates the speed of the conveyor, and a sensor that indicates the registration mark on each label. The servo positioning system is controlled by a microprocessor that sets the error signal, and the servo amplifier that provides power signals to the servomotor. This application is shown in Fig. 1-11. FIGURE 1-11 Example of a labeling application controlled by a servomotorAn Example of a Random Timing Infeed System Controlled by a Servomotor The fifth application is presented in Fig. 1-12, and it shows a series of packaging equipment that operates as three separate machines. The timing cycle of each station of the packaging system is independent from the others. The packaging system consists of an infeed conveyor, a positioning conveyor, and a wrapping station. The infeed conveyor and the wrapping station are mechanically connected so that they run at the same speed. The position of the packages on the wrapping station must be strictly controlled so that the packages do not become too close to each other. A piece of metal called a flight is connected to the wrapping station conveyor at specific points to ensure each package stays in position. A sensor is mounted at the beginning of the positioning conveyor to determine the front edge of the package when it starts to move onto the positioning conveyor. A second sensor is positioned at the bottom of the packaging conveyor to detect the flights. Both of these signals from the sensors are sent to the servomotor to provide information so the servo can adjust the speed of the positioning conveyor so that each package aligns with one of the flights as it moves onto the packaging conveyor
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