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I摘要本文主要设计了一种以 AT89S51 单片机为核心的产品自动装箱控制系统，能够对自动化生产流水线上的产品进行精确的计数和装箱。主体部分采用两条传送带，一条是包装箱传送带，另一条是产品传送带。对产品计数采用光电传感器，并与单片机 AT89S51接口，再通过单片机对交流电机的控制，实现产品的自动装箱。本设计的内容分为两部分：物品传动皮带机构设计，单片机控制电路设计。其中物品传动皮带机构与带式输送机的结构相似，该带式输送装置由输送带，托辊，驱动装置，拉紧装置等组成。而单片机控制部分主要分析了单片机与光电传感器协同工作和数据处理等方面。通过单片机对电动机等各机械部分的控制来实现系统要求，从而达到自动化生产的水平。关键词关键词 自动装箱；单片机；光电检测；输送装置IIAbstractThis paper has mainly designed an automatic packing control system for products. The core is monolithic computer of AT89S51. It carries on the precise counting and packing for the products on the automation process line. The main part uses two conveyor belts. One is package conveyor belt, and the other is product conveyor belt. The photoelectric sensor is used for the product counting and connects with the monolithic computer of AT89S51. The monolithic computer controls the motor. At last it realizes the automatic packing. This design divides into two parts. One is the design of goods transmission belt, and the other is the design of circuit control of monolithic computer. The goods transmission belt is similar to the belt conveyors structure, this conveyor belt is installed by the conveyor belt, the supporting roller, the drive, the tightening device and so on. The joint operation between monolithic computer and photoelectric sensor has been analyzed in the section of circuit control. The data processing also has been analyzed. We can achieve the requirements of system through the control on mechanical part, the motor and so on, thus reach the level of producing in automation.Keywords automatic packing monolithic computer electro-optic examination transportation equipment III目目 录录1 绪论.11.1 背景介绍.11.2 方案确定.11.3 设计方案综述.22 带式输送装置设计.32.1 带式输送装置的结构与应用.32.2 输送带的选择与计算.32.2.1 输送带的确定.42.2.2 输送带宽度的选择.42.2.3 输送带运行速度的选择.42.2.4 输送带接头的选择.52.3 托辊的选择.52.4 滚筒的选择.62.5 输送带牵引力计算.72.5.1 输送带的运动阻力和有效载荷.72.5.2 输送带的牵引力.112.6 带的强度校核.122.7 驱动装置的设计与计算.122.7.1 电动机的选择计算.132.7.2 减速器的选型.142.7.3 联轴器的选择.152.8 拉紧装置的选择.153 单片机控制电路设计.173.1 单片机控制系统的控制要求.173.2 光电检测装置的设计.173.2.1 光电传感器的基本原理.183.2.2 传感器的选择.193.2.3 传感器的位置确定.193.3 单片机控制系统的设计.203.3.1 单片机的概述.20学院毕业设计 (论文 )II3.3.2 单片机的应用.203.3.3 单片机的发展趋势.213.3.4 AT89S51 单片机的基本结构.213.3.5 AT89S51 单片机的主要引脚及功能.233.3.6 存储器和 I/O 接口电路.253.3.7 复位操作及复位电路.253.3.8 时钟电路.263.3.9 单片机控制的过程极其流程图.263.3.10 主程序的设计.284 辅助设备的设计.314.1 驱动头架的尺寸确定.314.2 拉紧尾架的尺寸确定.314.3 中间架的尺寸确定.314.4 传料板的尺寸确定.31结论.32致谢.33参考文献.34附录.35附录 1.35附录 2.46学院毕业设计 (论文 )III1 绪论1.1 背景介绍 在现代化的工业生产中，常常需要对产品进行计数、装箱。如果用人工不但麻烦，而且效率低、劳动强度大。随着微机控制的普及，特别是单片机的应用，给自动装箱系统的设计带来了极大的方便。近年来，包装生产线的自动化、电子监测和控制系统持续发展，使的包装企业以高速度、较少的停机时间和包装故障，以及产品损耗减少、工伤和老毛病降低等优点而获得出色的成绩。2002 年 11 月 3 至 7 日在芝加哥举行的国际PACK EXPO 上，我们可以看到多家自动化公司展示的最新的包装设备和新技术。这些经济实用的自动化技术将会成为未来的发展力量，可见自动装箱技术的应用前景十分广阔。在中国，自动化技术还未成熟，还需要长时间的发展，所以将会有很大的空间来发展此技术。这也是未来的发展方向和趋势。中国的经济高速度发展也需要这项技术来促进和加速，相信在自动化技术成熟以后，中国的经济也将有飞跃性的进步。当前中国的经济发展格局也是非常的需要高技术来支持。这样中才会有稳定的发展状态。向西部发展的经济战略思想必然需要有高技术随之转移，生产也将需要自动化技术的支持，这样发展高技术自动化也就是必然的趋势通过此题目的设计可以把大学四年所学的专业知识融会贯通于实际并能锻炼独立思考的能力,努力发展成未来的技术骨干，为中国的发展贡献一份力量，也使得我们能适应未来中国以及世界自动化技术的发展趋势。1.2 方案确定根据工况以及本设计的要求，确定以下方案：托辊：选用平行上下托辊。滚筒：本设计运送的产品较轻，载荷不大，所需的功率也不大，所以选用光面滚筒，钢板焊接。驱动装置：根据工况以及设计要求，考虑成本，本设计选择电机-减速器作为整个方案的驱动装置，由电机通过联轴器、减速器带动传动滚筒转动。拉紧装置：本设计输送装置长度较短，比较各种拉紧装置，选用螺旋拉紧装置。选取 500mm 的拉紧行程。 单片机：选用 AT89S51 单片机，是一种低功耗、具有在线编程 Flash 程序存储器的单片机。学院毕业设计 (论文 )21.3 设计方案综述此自动装箱系统利用传感器检测产品，并与单片机接口，输出的开关信号来驱动电动机，经过减速器减速，再带动传动滚筒，实现传送带的传送。两个检测装置分别检测包装箱是否到位和产品数量以控制相应电动机的启、停，从而带动相应传送带传送，最终实现精确计数，自动装箱。设计意义：此自动装箱系统从原料到包装实现了自动化，解决了手工装箱慢、容易计数出错等问题。该方法技术可靠，成本较低，可大大提高工效，减轻工人劳动强度以及减少产品损耗、工伤事故等。可应用于食盐、味精、洗衣粉、医药化工、农药、饲料等的自动装箱。学院毕业设计 (论文 )32 带式输送装置设计2.1带式输送装置的结构与应用带式输送装置是一种广泛应用的连续输送装置。工作原理是：由挠性输送带作为物料承载件和牵引件的连续输送设备，根据摩擦传动的原理，由传动滚筒带动输送带进行物料的传递与运输。它结构简单，工作可靠，造价低廉，适用性强。特别对工作节拍没有严格要求、比较干燥的生产场所，可用于柔性或半柔性的自动包装线，输送带、盒、箱等产品或散粒、块状产品。带式输送装置一般由传动滚筒，改向滚筒，输送带，托辊，拉紧装置等组成。如下图2-1所示为输送装置原理图。挠性输送带2绕在上、下托辊之上，由传动滚筒驱动，拉紧装置6用于调节输送带的拉紧力，以保持输送带的输送能力。传动滚筒驱动输送带的能力与输送带在传动滚筒上的包角大小有关，包角大时传动能力大，而改向滚筒就用于增大传动包角。带式输送装置的各辊轴轴承都采用滚动轴承，以减小运转中的摩擦阻力和功率消耗。图 2-1 输送装置原理图1-改向滚筒；2-输送带；3-上托辊；4-传动滚筒；5-下托辊；6-拉紧装置2.2 输送带的选择与计算输送带是带式输送机的牵引构件及承载构件，用于输送物料和传递动力， 是带式输送机的重要组成部分，约占带式输送机总成本的30%40%左右。它贯穿输送机的全长，在设备检修中占很大比重。同时，输送带在带式输送机中既是货物的承载机构，又是带式输送机的牵引机构，因此，不仅需要足够的强度，而且还应具有耐磨、耐腐蚀的要求。输送带选择的合理与否直接影响带式输送机的投资、运行成本，更为重要的是将直接影响输送机的可靠、安全运行。学院毕业设计 (论文 )42.2.1 输送带的确定输送带结构型式分为织物心输送带和钢丝绳心输送带，由上覆盖胶、心层、下覆盖胶组成，上、下覆盖胶的作用是保护心层不受损坏和不受周围工作环境的影响。心层材料有棉帆布、尼龙帆布、聚酯帆布和钢丝绳。织物心层输送带可根据拉力大小选取层数，棉帆布心输送带层数为3-8 层，尼龙帆布心输送带层数为2-6 层，聚酯帆布心输送带层数为3-6 层，当达到最大层数仍不能满足拉力要求时，采用钢丝绳心输送带。自动包装机所用带式输送装置多为轻型或特轻载荷类型，要求传送带结构紧凑、轻巧。根据输送机类型、结构以及工况，考虑经济成本，此设计的输送带心层材料选用4层的棉帆布带。2.2.2 输送带宽度的选择输送成件物品的输送带，按所输送的最大物件的对角线长度，再加约 100mm 余量约定所需要的输送带宽度，见图 2-2 所示，再根据标准带宽考虑到运输的包装箱不大，选取宽度为 500mm。此时要求包装箱的对角线长度 A 不宜大于 400mm。因为包装箱传送带所承受的重量大于产品传送带，所以下面选择计算包装箱传送带，产品传送带的各参数可与其相同。图 2-2 输送带宽2.2.3 输送带运行速度的选择输送带运行速度是输送机设计计算的重要参数，在输送量一定时，适当提高带速，可减少带宽。对水平安装的输送机，可选择较高的带速，输送倾角越大带速应偏低，向上输送时带速可适当高些，向下输送时带速应低些。输送成品件时的产品输送带速度 见式（2.1）v 式vnl（2.1） 式中 输送带速度，m/s，包装线上输送块状物件取值常小于 1.25m/s；v学院毕业设计 (论文 )5 每秒钟输送成件物品的件数，此处 n=5 件；n 输送带上成件物品节距，等于物品长度与两件之间的间距之和，此处l；0.2lmm 所以,产品输送带速度,包箱输送带可选用与此同样的速0.2 51/1.25/vm sm s度为 1m/s。2.2.4 输送带接头的选择 带式输送机输送带的接头有搭铆接，皮带扣连接，硫化胶粘接及化学胶粘接等方式。不同的连接方式接头效率不同。橡胶帆布带以优质硫化粘接最好，一般硫化粘接次之，皮带扣连接再次，搭接铆接最差。接头效率等于接头处最大破坏强度与输送带的极限强度的比值。为了此传送带有足够长的使用寿命，选用优质硫化粘接。2.3 托辊的选择 托辊是用于支承输送带及输送带上所承载的物品，保证输送带稳定运行的装置。它是整个输送装置中的重要部件, 使用数量多, 形式多样, 价格昂贵。托辊选择是否合理,影响带式输送机的使用、维修, 更会影响带式输送机使用寿命。托辊可分为：承载托辊、回程托辊。其中承载托辊分为：槽形托辊、缓冲托辊、调心托辊、平行上托辊等。回程托辊可分为：平行下托辊、螺旋托辊、V形托辊等。托辊辊子的直径与输送机带宽、带速和承载能力有关系, 与输送机长度和倾角无关。托辊直径与带宽的关系托辊辊径与长度应符合GB/T99021991带式输送机托辊基本参数与尺寸的规定, 见表2-1（单位mm）。表 2-1 托辊直径与带宽的关系托辊直径 500 650 800 1000 1200 1400 1600 1800 2000 2200 240063.5 76 89 108 133 159 194 219 在确定带速的情况下, 托辊辊子的转速不能太大。在同样寿命情况下, 转速大, 使用时间就短,转速小, 使用时间就长。但辊子的直径不能太大,辊子直径太大, 整个输送机不配套, 初期投资成本就高。一般规定: 辊子的转速不能超过600r/min。托辊直径与学院毕业设计 (论文 )6输送机带速的关系见表2-2。表2-2 托辊辊径与带速、转速的关系（r/min）辊径(mm) 0.8 1.0 1.25 1.6 2.0 2.5 3.15 4.0 5.0 6.589 172 215 268 344 429 537108 142 177 221 283 354 442 557133 144 180 230 287 359 453 575159 120 150 192 240 300 379 481 601194 123 158 197 246 310 394 492219 275 349 436 567已确定输送带宽度B=500mm，且带速v=1m/s，再综合以上情况, 根据表2-1和表2-2, 选用托辊直径89mm。因输送带承载的载荷并不大，所以分别选择平行上托辊和平行下托辊为承载托辊和回程托辊。2.4滚筒的选择滚筒分传动滚筒和改向滚筒。传动滚筒是传递动力的主要部件传动滚筒根据承载能力分轻型、中型和重型三种。轻型：轴承孔径 80-100mm。轴与轮毂为单键联接的单幅板焊接筒体结构。单向出轴。中型：轴承孔径 120-180mm。轴与轮毂为胀套联接。重型：轴承孔径 200-220mm。轴与轮毂为胀套联接，筒体为铸焊结构。有单向出轴和双向出轴两种。传动滚筒是将驱动装置的动力，通过摩擦力传递给输送带的部件。通常情况下，根据轴与轮毂之间的连接方式，传动滚筒有钢板焊接结构和铸焊结构两种形式。钢板焊接滚筒轴与轮毂之间采用键连接，能承受中小型载荷；铸焊滚筒轴与轮毂之间采用胀套连接，避免了由于键连接而削弱轴的强度，因此这种结构形式的滚筒可承受较大的负荷，且便于安装和拆卸。滚筒表面有光面和胶面两种形式，在功率不大，环境湿度小的情况下，可采用表面摩擦因数小的光面滚筒；在功率大，环境又潮湿，容易打滑的情况下采用表面摩擦因数大的胶面滚筒。胶面的作用是增大传动滚筒与输送带之间的摩擦力。胶面滚筒有铸胶和包胶两种工艺型式，铸胶滚筒胶面厚且耐磨，质量好，但工艺复杂，价格高；包胶滚筒工艺简单，成本低。胶面滚筒有光胶面、人字型沟槽和菱形沟槽三种型式。当采用人字型沟槽胶面滚筒时，应注意其方向性，人字型尖应朝向滚筒的转动方向，菱形胶面滚筒用于双向运输的输送机。用于重要场合的滚筒最好采用硫化橡胶覆面；当有阻燃、隔爆条件要求时，应采用相应措施。此处运送的产品较轻，所需的功率也不大，所以选用光面滚筒。改向滚筒的作用是改变输送带的运行方向或增加输送带与传动滚筒间的围包角。增学院毕业设计 (论文 )7加围包角的作用是增加输送带与滚筒间的接触面，使输送带与滚筒间不打滑。改向滚筒包括尾部滚筒、增加传动滚筒围包角、增加尾部滚筒围包角及拉紧装置处的滚筒。改向滚筒和传动滚筒一样有钢板焊接结构和铸焊结构两种形式。滚筒表面有光钢面和光胶面两种。除较重要的场合选用光胶面滚筒外，一般采用光钢面滚筒。按承载能力改向滚筒又可分轻型、中型和重型；轴承孔径分为50-100mm，120-180mm及200-260mm，结构与传动滚筒一致。改向滚筒覆面有裸露光钢面和平滑胶面两种。表 2-4 各种帆布带相对层数的最小传动滚筒直径型号345678CC-56、NN-10050050063080010001000NN-150、EP-100500500630800NN-120 NN-300EP-200 EP-3005006308001000因为选用的棉帆布带层数，所以由上表 2-4，可选用的滚筒最小滚筒直径为4Z 500mm。因为该向滚筒的直径一般比传动滚筒的直径小一级，结合下表 2-5，可选用带宽，长度，的滚筒为传动滚筒，带宽，长度500Bm600Lm1500Dmm500Bm，的滚筒为改向滚筒。600Lm2400Dmm表 2-5 带宽和滚筒直径、长度之间的关系带宽 B （mm）滚筒长度 L（mm）滚筒直径 D（mm）500600200,250,315,400,500650750200,250,315,400,500,630,800,1000800950200,250,315,400,500,630,800,1000,1250,1400所选的传动滚筒和改向滚筒的基本参数如下表 2-6：表 2-6 滚筒基本参数滚 筒带宽（mm）直径D（mm）轴承 型号许用合力(KN)转动惯量(Kgm2)质量(Kg)图 号传动滚筒5005006316495250DT01A4081改向滚筒5004006312403166DT01B30522.5输送带牵引力计算2.5.1 输送带的运动阻力和有效载荷输送带运动时的阻力包括直线区段、曲线区段以及一些附属装置所产生的局部阻力。学院毕业设计 (论文 )8（1）直线区段 输送带在托辊上运动时的阻力包括托辊轴承以及带与托辊之间的摩擦阻力等。通常由与托辊单位长度压力所引起的运动阻力来表示，特称为阻力系数。其值 与轴承类型及工作环境有关， 取长度为 L、倾角为 的一段输送带，分析其受力状况，如图 2-3 所示。设单位长度内物件、输送带和上、下托辊的当量线载荷、。即可求WqDq1Gq2Gq出作用在托辊轴承上的总压力 N。 式/WWqGl（2.2） 式111/GqGl（2.3） 式（2.4）222/GqGl式中 包箱重量，此处为 250N；WG 上托辊重量，由参考文献7查得，此处选为 116N；1G 下托辊重量，由参考文献7查得，此处为 104N；2G包装箱节距，此处为 1000mm（包装箱长略小于 400mm） ；l上托辊间距，输送散货时取 1.2m。输送件货时，如果单间重量超过1l200N，则托辊间距应小于件货输送方向长度的一半，此处取 0.18m；下托辊间距，一般取 23 米，此处取 3 米。 2l所以 ：，由参考文献5可查得250/WqN m11160/GqN m234.67/GqN m。57.09/DqN m 图 2-3 输送带受力分析学院毕业设计 (论文 )9考虑到 角较小， 几乎为零度，可近似地取 式() cosWDGNqqqL（2.5）这样输送带在托辊上运动时所受的摩擦阻力为 式() cosWDGNqqqL（2.6）令 Sa、Sb 分别代表所选区段内输送带主动边和从动边的拉力。由图（2-3）可列出受力平衡方程式 式() cos() sinWDGWDSaSbqqqLqqL（2.7）进而求出该区段的运动阻力为 式1() cos() sinZWDGWDFSaSbqqqLqqL（2.8）对于松边来说，因没有物件承载，QW=0，故主从动边的拉力差改变为 式2() cos() sinZDGWDFqqLqqL（2.10）由参考文献5可查得带与托辊的运动阻力系数，接合一般输送带长度选择，0.025这里带长取 12m。所以, 直线区段的运动阻力 1() cos() sinZWDGWDFqqqLqqL =0.02512(250+57.09+1370) =503.13N 2() cossinZDGDFqqLq L =0.025(57.09+34.67) 12 =27.53N学院毕业设计 (论文 )10（2） 曲线区段输送带饶过主、从动滚筒时也会遇到阻力，它主要由轴承摩擦阻力以及带本身的刚性阻力组成。轴承摩擦阻力是通过作用在滚筒上的外力再转换为对轴承的正压力而求出的，即 N 式FN（2.11）式中 轴承的摩擦系数，由参考文献5查得，此处为 0.015。如图 2-4 所示，作用在滚筒上的外力有，输送带饶入端和饶出锻端的拉力、，SS以及滚筒的自重；若忽略不计此自重，且近似取=，则作用在滚筒上轴承的合力SS 式2 sin(2)NS（2.12）式中 滚筒的包角，此处取为 180。图 2-4 滚筒受力分析若将轴承摩擦阻力折算到滚筒圆周上，则当量阻力为 式2sin(2)FN d DSdD（2.13）式中 D、d分别为滚筒及其轴颈的直径，此处传动滚筒分别取 500mm，80mm，改向滚筒分别取 400mm，60mm；输送带由于本身弯曲变形和内摩擦效应所产生的运动阻力 式FS学院毕业设计 (论文 )11（2.14）挠性系数可按下式近似计算 式1.21.23D（2.15）式中 带的厚度，此处为 4.5mm。因此，带在曲线区段运动的总阻力为 式2sin(2)QFFFdSDS（2.16）式中 S带绕过轮上两端拉力中取较大者。曲线区段 23 的挠性系数由式（2.15）近式算出：1.21.22321.231.23 0.45 400.0066D该区段的运动阻力由式（2.16）算出，其中 S 在计算时采用从动滚筒带绕出段端拉力。 2323222332sin(2)QFd SDS 332 0.015 60sin904000.0066SS30.0111S2.5.2 输送带的牵引力由式（2.7）看出，在直线区段内，输送带上 a 点的拉力 Sa 应等于另一点 Sb 的拉力与两点间的运动阻力之和。对带的拉力进行逐点计算的分段方法，如图 2-5 所示。图 2-5 输送带受力分析的分段以主动滚筒上输送带的绕出点 1 为起始点，以饶入点 4 为终点，沿带的工作运转方向将它分为若干直线和曲线区段。并设各点拉力：第 1 点为：1S第 2 点为：21ZSSF第 3 点为：3223QSSF学院毕业设计 (论文 )12第 4 点为：43123ZZQZSSFSFFF据此可求出运输带任一点的 n 的拉力 式1(1)nnnnSSF（2.17）进而可求出输送带在传动滚筒上绕出点的拉力与饶入点之间的函数关系。0SRS， ， ，令则式（2.17）改写为式（2.18） 。RnSS01nSS0(1)RnnFF 式00RRSSF（2.18）另一方面，在正常运转过程中，为保证带的作用力传递和不沿滚筒打滑，饶入点和饶出点的拉力还必须满足由欧拉公式所提出的条件，即 式（2.19）0RSS eK 式中 K安全系数，通常取 1.21.5。 至此，可求出输送带的牵引力 式0RORZQZPSSFFFF（2.20）由上述推导可列出如下：21ZSSF3223QSSF43123ZZQZSSFSFFF所以，4130.0111391.23SSS110.0111 (34.41) 0.98893921.23SS11.011391.62S考虑到滚筒为金属制件，其工作环境干燥，由参考文献5可查得，=0.25，再取安全系数 K=1.5，又得2.19e 式41112.191.51.46SS eKSS（2.21）对以上两表达示 S4=f（S1）联立，解出主从动滚筒绕入端和绕出端的拉力为 ： 41273.41SN1872.2SN学院毕业设计 (论文 )13所以，牵引力。41401.21FSSN2.6带的强度校核校核带输送带的强度，可用下式（2.22）： 式maxZBSn（2.22）式中 Z带的帆布层数，此处为 4；B带宽，此处为 500mm；一层 1cm 宽胶布带的保证强度，普通橡胶带（棉布带芯胶布）通常取560N/cm；n安全系数，查由参考文献5得，此处为 8。最大拉力，此处。maxSmax41401.21SSSN max4 50 560 1273.4187.958ZBS故说明强度可靠。2.7 驱动装置的设计与计算驱动装置是用来驱动输送带运动，实现物料运送的装置。其驱动原理是依靠传动滚筒与输送带之间的摩擦力来传递动力使带运动的。驱动装置由电动机、减速器、联轴器、传动滚筒等组成。如图 2-6 为驱动装置图。对于倾角较大的上运带式输送机还应设有停止器或制动器，以防止电动机断电后输送带在自重及物料重力作用下返回运动。而本设计的带式输送装置倾角较小，几乎为零，所以可不设置停止器或制动器。图 2-6 驱动装置图1-电动机；2、4-联轴器；3-减速器；5-传动滚筒学院毕业设计 (论文 )142.7.1电动机的选择计算（1）选择电动机的类型电动机是常用的原动机，并且是系列化和标准化产品。机械设计中需要根据工作机的工作情况和运动，动力参数，合理地选择电动机类型，结构形式，传递的功率和转速,确定电动机的型号。电动机有交流电动机和直流电动机之分.由于直流电动机需要直流电源，结构较复杂，价格较高，维护比较不方便，因此无特殊要求时不宜采用。工业上常采用交流电动机。交流电动机有异步电动机和同步电动机两类，异步电动机又分为笼型和绕线型两种，其中以普通笼型异步电动机应用最广泛。而在此自动装箱系统中，电动机须经常启动、制动，所以要求电动机的转动惯量小和过载能力大，应选用起重及冶金用三相笼型异步电动机，电压380V，YZ型。（1） 选择电动机的容量电动机所需工作功率为 式(1000)daPFv（2.23）式中 F输送带的牵引力，N；v输送带的速度，m/s；电动机至输送带的传动总功率；a传动总功率：421234a 式中 轴承的传动效率，此处为 0.98；1 蜗杆传动的传动效率，此处为 0.7；2连轴器的传动效率，此处为 0.99；3滚筒的传动效率，此处为 0.96。4所以， 420.980.7 0.990.96a0.6 401.21 1 (1000 0.6)0.67PdKW（2） 确定电动机的转速滚筒轴工作转速为 式60 1000()nvD（2.24）式中：D传动滚筒直径，此处为 500mm；v输送带带速，此处为 1m/s。可得。60 1000 1 (3.14 500)38.22 /minnr学院毕业设计 (论文 )15因为一级蜗杆减速器的传动比 i=1040，则电动机转速的可选范围为：(80 40) 38.22382 1529 /mindninr根据容量和转速等，由参考文献4查得，选用电动机型号为 YZ112M-6。选用的电动机的技术参数如表 2-7表 2-7 电动机的技术参数型号额定功率（KW）定子电流（A）转 速（r/min）最大转矩堵转转矩堵转电流效率（%）功率因数YZ112M-61.54.259202.02.04.4769.50.7652.7.2 减速器的选型根据带速，传动滚筒直径和电动机转速推知减速器的传动比为： 式（2.25）603.14 920 0.5 6024.07inDv由机械手册查得，蜗杆减速器的结构简单，尺寸紧凑，效率低，适用于载荷较小。间歇工作的场合。所以这里选用 CW 型圆弧圆柱蜗杆减速器，它适用于冶金，矿山，起重，运输，化工，建筑等机械设备的减速传动。 由下式（2.24） ，式（2.25）可初步计算减速器的功率 式（2.26）1112JBPP f f 式（2.27）1134RBPP f f式中 减速器计算输入机械功率，Km；1JP 减速器计算输入热功率；1RP 减速器实际输入功率；1BP工作载荷系数，由参考文献6查得，此处取为 1.25；1f 启动频率系数，由参考文献6查得，此处取为 1.1；2f 小时负荷系数，由参考文献6得，此处取为 0.7；3f环境温度系数，由参考文献6得，此处取为 1.14。4f所以 ，10.7 1.25 1.10.9625JPKW10.7 0.7 1.140.56RPKW由于大于，故按进行选择。1JP1RP10.9625JPKW选择的减速器的技术参数如下表 2-8表 2-8 减速器的技术参数型号高速轴输入转矩额定输入功率传动比中心距CW125-25-1000r/min5.6 KW25125mm学院毕业设计 (论文 )162.7.3 联轴器的选择 考虑到工作现场的空间和减少传动链的原则，该设计直接采用联轴器，通过联轴器直接把电动机和减速器联接，减速器与滚筒联接。动力传递过程中，电机转速相对较大，有一定的振动且频繁启动，因此电动机与减速器相连处选用弹性联轴器。减速器与滚筒联接处转速低，但有一定载荷，两轴也不在同一基础上，有相对偏差，因而选用滑块联轴器。弹性套柱销联轴器：具有挠性元件，依靠弹性套与半联轴器凸缘上圆孔间的间隙以及弹性套的变形,不但具有位移补偿能力，而且具有良好的缓冲吸振能力，因此适用于这里启动频繁、有冲击振动的场合。滑块联轴器：具有径向位移、角位移补偿能力，由于制造、安装及机器运转中轴、轴承、支承座等受载荷、温度的影响而变形，使得被联接两轴在实际中不可能完全对中，两轴出现径向位移、角位移等，这时使用的滑块联轴器允许两轴间有一定的相互位移。2.8 拉紧装置的选择拉紧装置给输送带一定的初始拉紧力，在运行中始终使输送带保持一定的拉紧程度，以免在驱动滚筒上打滑，并使输送带在拖辊间的挠度保证在规定的范围内。拉紧装置是带式输送机不可缺少的重要组成部分，它的性能好坏直接影响带式输送机整体的性能，拉紧装置的功能主要有以下几点：（1）保证带式输送机驱动滚筒分离点的足够张力和驱动装置依靠摩擦传动所必须传递的摩擦牵引力，以带动输送机的正常运转，防止输送带打滑； （2）保证承载分支最小张力点的必须张力，限制输送带在托辊之间的垂度，保证带式输送机正常运行； （3）补偿塑性变形与过渡工况时输送带伸长量的变化。由于负载变化会引起输送带发生长度变化，蠕变现象也会造成输送带伸长，张紧力有变小趋势，需要拉紧装置来吸收由蠕变产生的伸长，维持输送机正常运行所需的最小张紧力； （4）为输送带重新接头做必要的行程准备。每部带式输送机都有若干个接头，可能在某一时间接头会出现问题，必须截头重做，拉紧装置为带式输送机准备了负荷以外的输送带，这样接头故障就可以通过放松拉紧装置重新接头来解决。常见的拉紧装置有重力拉紧装置、螺旋拉紧装置、固定绞车拉紧装置、自动拉紧装置等。各种拉紧装置的特点如下：3 H D; Z, 9（1）重力拉紧装置。重力拉紧装置是结构最简单，应用最广泛的一种拉紧装置。它是利用重锤来自动拉紧，由于重锤靠自重拉紧，所以它能保证拉紧力在各种工况下保持恒定不变，能自动补偿胶带的伸长。重力拉紧装置的特点是拉紧力不变，拉紧位移可变，它学院毕业设计 (论文 )17适用于固定式长距离运输机，机长 500m 以上的中长距离输送机，需较大的拉紧行程，可将拉紧滚筒小车布置在输送机下部，通过布置在输送机一侧的重锤拉紧塔架实现重锤拉紧。（2）螺旋拉紧装置。螺旋拉紧装置结构简单，拉紧行程小，适用于短距离输送机，此拉紧装置所需的拉紧力一般通过丝杠手动调整，适用于长度 80m 以内的短距离输送机。对轻型物料和输送量特小的输送机，可适当延长。根据输送带张力，亦可采用液压缸作为动力。（3）固定绞车拉紧装置。固定绞车拉紧装置是利用小型绞车来拉紧，绞车一般用蜗轮蜗杆减速器带动卷筒来缠绕钢绳，从而拉紧胶带。这种拉紧装置的优点是体积小，拉力大，可用于 500m 以上中等长度以上的输送机。缺点是它只能根据所需要的拉紧力调定后产生固定的拉紧力，拉紧力不能自动调节，当绞车和控制系统出现问题时，对胶带机不能产生恒定的拉紧力或拉紧力失效，安全可靠性相对降低。（4）自动拉紧装置。自动拉紧装置不但能根据主动滚筒的牵引力来自动调整拉紧力，而且还能补偿胶带的伸长。包括自动式电动绞车或自动式液压拉紧装置，可根据输送机启动、运行、制动运行工况的不同要求，自动调整输送带拉紧力和响应张紧滚筒的位置变化要求，宜用于布置复杂的大型输送机。9 _. % 因为这里的输送装置长度为 12m，长度较小对照上述拉紧装置，所以选用螺旋拉紧装置比较合适。螺旋张紧行程有 500mm、800mm、1000mm 三种，此处选取 500mm 的张紧行程，最大拉紧力为 9KN。3 单片机控制电路设计在传感器中，很多传感器能接受输入信号以开关信号输出。由于单片机具有位处理功能，所以可以实现开关量的控制。本文设计了一种小型件的自动装置系统，利用传感器检测产品，并与单片机接口，输出的开关信号控制产品的自动装箱。学院毕业设计 (论文 )183.1 单片机控制系统的控制要求 该系统总共分成传动和传感两部分，其功能要求是能准确定位包装箱，准确检测是否装满产品，产品的传动和包装箱的转动能够自动的调节，并且可以检测箱子的个数。系统中有两条传送带和两个检测器（光电传感器）。传送1 是包装箱传送带，传送带2 是产品传送带。信号检测部分有两个光电传感器，光电传感器1 用来检测包装箱是否到位，光电传感器2 用来产品计数。传送带2 将产品从生产区传送到包装区，产品到传送带2 的末端时，就会掉入包装箱，同时被检测器2 （光电传感器）检测并计数。传送带1 把满箱运走，并用空箱代替。为使空箱对准产品，用检测器1 （光电传感器）检测是否到位。产品自动装箱系统的工作流程如图3-1所示。图 3-1 产品自动装箱系统的工作流程图3.2 光电检测装置的设计光电检测技术在包装机械中多用于计数、容器定位、料面控制和色质检测等方面。其特点是可以实现无接触检测, 可将机械动态检测变成光电静态检测,从而显著简化机械结构, 通常被称为自动控制的眼睛, 而且它所具有的某些功能, 是人眼所不能达到的。比如它具有很高的响应速度, 当被测物以较高速度运动时也逃脱不了该系统的观察。这里利用光电检测装置检测产品数量和包装箱是否到位。3.2.1光电传感器的基本原理传感器是一种能把物理量或化学量转变成便于利用的电信号的器件。而光电传感器(光电开关)是光电接近开关的简称，它是利用被检测物对光束的遮挡或反射，当被测量的信号达到某个特定的阈值时，传感器相应地输出一个设定的低电平或高电平信号，以达到检测的目的。其物体不限于金属，对所有能反射光线的物体均可被检测。光电开关学院毕业设计 (论文 )19是一种电量传感器，把电流或电压的变化以光电的方式传送出去。即进行电信号-光信号-电信号的转换。光电传感器在一般情况下，有三部分构成，它们分为：发射器(光源) 、接收器和检测电路。根据接收器所感知的信号判断被测对象的有无、形状、方位和颜色时, 按发射器和接收器的相对位置不同可分为反射型和透过型两种型式, 见图 3-2（a）、（b）。图 3-2（a）反射型、（b）透过型发射器对准目标发射光束，发射的光束一般来源于半导体光源，发光二极管(LED)、激光二极管及红外发射二极管。发射器发出的光采用不同形式接触被测物后照射在受光器上, 而接受器是在光照射下产生电流(或电导率发生变化) , 即所谓的具有光电效应的光敏元件, 常用的有光电二极管、光电三极管、光电池管。光电二极管的 PN 结在没有光照时和普通二极管一样具有单向导电性, 使用时处于反向偏置; 光线照射管芯, 会产生光生载流子, 在反向电压作用下,光生载流子导电产生光电流, 即随入射光强度的变化在负载电阻的两端就会产生随光强度变化的光电压,经检波、放大处理去推动控制系统。光敏三极管除了具有光敏二极管能将光信号转换成电信号的功能外，还有对电信号放大的功能。光敏三级管的外型与一般三极管相差不大，一般光敏三极管只引出两个极发射极和集电极，基极不引出，管壳同样开窗口，以便光线射入。为增大光照，基区面积做得很大，发射区较小，入射光主要被基区吸收。工作时集电结反偏，发射结正偏。在无光照时管子流过的电流为暗电流Iceo=（1+）Icbo（很小） ，比一般三极管的穿透电流还小；当有光照时，激发大量的电子-空穴对，使得基极产生的电流Ib增大，此刻流过管子的电流称为光电流，集电极电流Ic=（1+）Ib，可见光电三极管要比光电二极管具有更高的灵敏度。发送器对准目标发射光束，发射的光束一般来源于半导体光源，发光二极管(LED)、激光二极管及红外发射二极管。光束不间断地发射，或者改变脉冲宽度。接收器有光电二极管、光电三极管、光电池组成。在接收器的前面，装有光学元件如透镜和光圈等。在其后面是检测电路，它能滤出有效信号和应用该信号。学院毕业设计 (论文 )203.2.2 传感器的选择光电开关的分类和工作方式如下：（1）漫反射式光电开关：它是一种集发射器和接收器于一体的传感器，当有被检测物体经过时，物体将光电开关发射器发射的足够量的光线反射到接收器，于是光电开关就产生了开关信号。当被检测物体的表面光亮或其反光率极高时，漫反射式的光电开关是首选的检测模式。（2）镜反射式光电开关：它亦集发射器与接收器于一体，光电开关发射器发出的光线经过反射镜反射回接收器，当被检测物体经过且完全阻断光线时，光电开关就产生了检测开关信号。（3）对射式光电开关：它包含了在结构上相互分离且光轴相对放置的发射器和接收器，发射器发出的光线直接进入接收器，当被检测物体经过发射器和接收器之间且阻断光线时，光电开关就产生了开关信号。当检测物体为不透明时，对射式光电开关是最可靠的检测装置。（4）槽式光电开关：它通常采用标准的U字型结构，其发射器和接收器分别位于U型槽的两边，并形成一光轴，当被检测物体经过U型槽且阻断光轴时，光电开关就产生了开关量信号。槽式光电开关比较适合检测高速运动的物体，并且它能分辨透明与半透明物体,使用安全可靠。（5）光纤式光电开关：它采用塑料或玻璃光纤传感器来引导光线，可以对距离远的被检测物体进行检测。通常光纤传感器分为对射式和漫反射式。在传送带2上，包装箱为不透明物体，综合考虑上述分类，选用对射式光电开关。3.2.3 传感器的位置确定当光电传感器检测到包装箱到位或产品数量已达到要求时，单片机控制的电路使相应的电动机停止转动。但由于惯性等因数，包装箱并不会立即停止，还会继续往前运行一段距离S，导致包装箱不能准确到位，产品数量计错。而这段预留的距离S可由式（3.1）、式（3.2）近似推导可得。 式mgma（3.1） 式（3.22202taSVV）式中：为输送带摩擦因数，由参考文献5查得，为 0.6； 为带停止时的初速度，取值为 1m/s；tV为带停止的末速度取值为 0；0V学院毕业设计 (论文 )21 为输送带停止这段时间的加速度。a所以预留距离： 1 284Sgmm因此，传感器 1 在包装箱上的位置应位于产品传送带下方偏前 84mm；因为产品间距为 150mm，大于这段预留距离，所以传感器 2 的位置可设在产品传送带末（具体位置见CAD 总装配图） 。3.3 单片机控制系统的设计此自动装箱系统主体部分采用两条传送带，一条包装箱传送带，另一条是产品传送带。对产品计数采用光电传感器，并与单片机接口，再通过单片机对交流电机的控制，实现产品的自动装箱。3.3.1 单片机的概述单片机的全称叫做单片机微型计算机，是微型计算机家族中的一个分类，是将CPU、存储器、总线、I/O接口电路集成在一片超大规模集成电路芯片上，因此又称之为单片机。单片机具有体积小、功能全、价格低廉的突出优点，同时其软件也非常丰富，并可将这些软件嵌入到其他产品中，使其他产品具有丰富的智能。单片机所具有的这些优点使之问世后得到了迅速的发展，广泛应用在工业控制、仪器仪表、交通运输、通信设备、家用电器等众多领域，成为现代电子系统中最重要的智能化器件。3.3.2 单片机的应用为满足各种各样系统对控制功能的不同需求，以单片机为控制核心构成的控制系统在规模、结构、功能等方面将会有很大的不同，根据规模可概括、笼统地划分为基本应用系统和和扩展应用系统。单片机基本应用系统没有扩展的程序存储器ROM、数据存储器RAM、扩展的I/O接口等扩展部件，除单片机外仅配置了电源、时钟电路、输入/输出设备和复位电路，是最小的单片机应用系统，如图3-3所示。学院毕业设计 (论文 )22图3-3 最小的单片机应用系统3.3.3 单片机的发展趋势从第一代单片机到时至今日各大公司推出的各种型号电片机的功能及资源，可以看到电片机正朝着更高性能、更高容量、进一步微型化、多品种的方向发展，主要体现在如下几个方面：（1）CPU的运算速度、处理能力进一步的提高。（2）存储容量的增加和存储器本身技术水平的提高。16位单片机中的ROM和RAM的容量进一步增大，特别是Flash存储器的使用，可大大提高编程和擦除的速度，并能实现在线编程。（3）I/O口的改进 。单片机的I/O口将开始呈现多样化和多功能化的趋势，包括可编程并行口，可编程串行口、串行扩展口、多位的A/D转换器、增加I/O口的逻辑控制功能等多项软硬件技术都已开始应用。 （4）特殊的串行口功能。为适应控制系统网络化的需求，一些单片机提供了具有了网络功能的特殊串行口，为应用单片机构造控制网络系统提供了便利的条件。（5）系统的单片化。随着超大规模集成电路制造水平和工艺的不断发展和提高，一些外围电路的功能将会被并入或集成到单片机的芯片内部，包括多位的A/D转换器、D/A转换器、DMA控制器、中断控制器等将一个单片机控制系统集成在一块芯片上。（6）小型化。 对一些比较简单的设备或系统（例如简单的家电设备、小单元报警系统等）的控制，并不需要功能特别强的单片机来实现，只需要满足控制的需要即可，因此一些功能相对简单、体积更小、价格低廉的单片机有着广阔的市场。3.3.4 AT89S51单片机的基本结构AT89S51是美国ATMEL公司的低功耗，高性能CMOS8位单片机，片内含4KB的可编程的学院毕业设计 (论文 )23Flash只读程序存储器，器件采用ATMEL公司的高密度、非易失性存储技术生产，兼容标准8051指令系统及引脚。它集Flash程序存储器可在线编程（ISP）也可用传统方法进行编程及通用8位微处理器于单片芯片中。主要性能参数：MCS-51产品指令系统完全兼容 ；4K字节的快速擦除写Flash存储器；1000次擦写周期 ；4.0-5.5V的工作电压范围；全静态工作模式：0HZ-33MHZ；三级程序加密锁；128字节内部RAM；32个可编程I/O口线；2个16位定时/计数器；6个中断源；全双工串行UART通道；低功耗空闲和掉电模式；看门狗（WDT）及双数据指针；掉电标识和快速编程特性；单片机的原理结构图如下图3-4：学院毕业设计 (论文 )24图3-4 AT89S51单片机原理结构图3.3.5 AT89S51单片机主要引脚及功能VCC：电源电压GND：地P0口：P0口是一组8位漏极开路型双向I/O口，也即地址/数据总线复用口。作为输出口用时，每位能驱动8个TTL逻辑门电路，对端口写“1”可作为高阻抗输入端用。 在访问外部数据存储器或程序存储器时，这组口线分时转换地址（低8位）和数据总线复用，学院毕业设计 (论文 )25在访问期间激活内部上拉电阻。P1口：P1口是一个带内部上拉电阻的8位双向I/O口，P1的输出缓冲可驱动（吸收或输出电流）4个TTL逻辑门电路。对端口写“1” ，通过内部的上拉电阻把端口拉到高电平，此时可作输入口。作输入口使用时，因内部存在上拉电阻，某个引脚被外部信号拉低时会输出一个电流。P2口：P2是一个带内部上拉电阻的8位双向I/O口，P2的输出缓冲级可驱动（吸收或输出电流）4个TTL逻辑门电路。对端口写“1” ，通过内部的上拉电阻把端口拉到高电平，此时可作输入口使用，因为内部在上拉电阻，某个引脚被外部信号拉低时会输出一个电流。P3口：P3口是一组带内部上拉电阻的8位双向8位I/O口。P3口输出缓冲级可驱动（吸收或输出电流）4个TTL逻辑门电路。对P3口写入“1”时，它们被内部上拉电阻拉高可作为输入端口。做输出端时，被外部拉低P3口将用上拉电阻输出电流。RST：复位输入。 ：程序存储器允许（）输出是外部程序存储器的读选通信号，当 AT89S51PSENPSEN由外部程序存储器取指令（或数据）时，每个机器周两次有效，即输出两个脉冲。PSEN当访问外部数据存储器，没有两次有效的信号。PSENEV/VPP：外部访问允许。欲使 CPU 仅访问外部程序存储器（地址 0000H-FFFFH），EA端必须保持低电平（接地）。XTAL1：振荡器反向放大器及内部时钟发生器的输入端。XTAL2：振荡器反向放大器的输出端。PDIP封装AS89S51单片机的引脚排列如下图3-5所示 图3-5 PDIP封装AS89S51单片机的引脚排列学院毕业设计 (论文 )263.3.6 存储器和I/O接口电路AT89S51单片机芯片内配置有4KB的Flash程序存储器和128B的数据存储器RAM，根据需要可外扩最大64KB的程序存储器和64KB的数据存储器，因此AT89S51的存储器结构可分为4部分：片内程序存储器、片外程序存储器、片内数据存储器和片外数据存储器。CPU的数据处理速度要远高于外围设备，同时各外围设备的数据处理速度也不尽相同，因此在CPU与外围设备之间进行信息交换时要解决处理速度的匹配问题，以有效地提高CPU的工作效率；与此同时还要对外围设备进行驱动，I/O接口电路正是为了上述问题而设计的。CPU和外围设备进行信息交换都要通过接口电路来进行。AT89S51单片机内部集成4个可编程的并行I/O口（P0-P3），每个输出接口电路都具有锁存器和驱动器，输入接口电路具有三态门控制，这是接口电路的基本特征。3.3.7 复位操作及复位电路复位操作是使单片机的CPU以及各部件处于初始状态，并从这个状态开始运行。单片机在运行过程中可能会受到外界的干扰使程序陷入死循环或“跑飞”，发生这种情况时需要将单片机复位，以重新启动运行。（1）复位操作RST引脚是复位信号的输入端口，高电平有效。在时钟振荡器稳定工作情况下，该引脚若有低电平上升到高电平并持续2个机器周期，如图所示，系统实现一次复位 操作。单片机在RST高电瓶有效后的第二个机器周期开始执行内部复位操作，并在RST变为低电平前的每个机器周期重复执行内部复位操作。（1） 复位电路图3-6上电自动复位电路 图3-7为手动复位电路复位操作有手动复位和上电自动复位，上图3-6为上电自动复位电路，上图3-7为手动复位电路。在复位电路上电的瞬间，RC电路充电，RST引脚出现高电平。RST引脚出现的高电平学院毕业设计 (论文 )27将会随着对电容C的充电过程而逐渐回落，为了保证RST引叫出现的高电平持续两个机器周期以上的时间，须合理地选择其电阻和电容的参数值，而电阻和电容参数的取值随着时钟频率的不同而变化。这里采用手动复位，以便在出现故障或是任意需要的情况下进行复位，3.3.8 时钟电路时钟电路用于产生单片机工作所需要的时钟信号，控制着单片机的有序运行节奏，而时序规定了指令执行过程中各控制信号之间的相互关系。在时钟信号的控制作用下，单片机就如同一个复杂的同步时序电路，严格地按照规定的时序进行工作。 在AT89S51芯片内部，有一个振荡器电路和时钟发生器，引脚XTAL1和XTAL2之间介入晶体振荡器和电容后构成内部时钟方式。也可以使用外部振荡器产生的信号直接加载到振荡器的输入端，作为CPU的时钟源，称为外部时钟方式。大多数的单片机采用内部时钟方式，这里AT89S51单片机也采用内部时钟方式。图3-8、3-9为两种方式的电路连接。 图3-8 使用片内振荡器接法 图3-9 使用片外振荡器接法3.3.9 单片机控制的过程极其流程图单片机AT89S51用P1.6 控制传送带1，P1.7控制传送带2。P1.6，P1.7均通过一个反向驱动器与光电耦合器的发光二极管阴极相连，通过改变光敏电阻阻值改变GATE 的电位，从而控制三端双向晶闸管的通、断，以实现对电动机的启、停控制。具体的原理图如图3-10，产品自动装箱控制系统的流程图如图3-11学院毕业设计 (论文 )28图3-10 单片机控制的产品自动装箱系统原理图学院毕业设计 (论文 )29 图3-11 产品自动装箱控制系统的流程图3.3.10 主程序的设计ORG2000HSTART： ANL P1.，# 3 F H ；停止两个传送带ORL P1. ，#40H ；启动带1，停止带2LOOP1： JB P1.0，LOOP1 ；检测包装箱是否到位，等待P1.0 为低电平LOOP2： JNB P1.0，LOOP2 ；等待P1.0 为高电平，新的空箱到位ANL P1 ，#OBFH ；停止带1SETB P1.7 ；启动带2MOV R1 ，#00H ；计数器清零LOOP3： JNB P1.1，LOOP3 ；等待P1.1为高电平LOOP4： JB P1.1，LOOP4 ；等待P1.1 为低电平，检测产品是否到来学院毕业设计 (论文 )30LOOP5： JNB P1.1，LOOP5 ；INC R1 ；计数器加1MOV A，R1XRL A，#64H ；箱内装100个产品吗？JNZ LOOP3 ；未满，继续AJMP START ；已装箱，换箱END光电传感器与单片机协同工作，控制电动机启动、停止，从而实现自动计数装箱，其具体过程如下：（1）单片机执行程序：ANL P1.，#3FH。P1.6、P1.7 同时置 0，此时与 P1.6、P1.7 相连的反向驱动器使光电耦合器的发光二极管阴极变为高电平，发光二级管因为电流太小不能发光，光敏电阻接受不到光照阻值较大，GATE 点电位较小，达不到三端双向晶闸管的导通值，三端双向晶闸管断开，电动机 1、2 停止转动，则包装箱传送带 1、2 停止传送。 （2）单片机执行程序：ORL P1.，#40H 。P1.6 置 1，此时与 P1.6 相连的反向驱动器使光电耦合器的发光二极管阴极变为低电平，发光二级管发光，光敏电阻受到光照阻值变小，而 GATE 点电位上升，达到三端双向晶闸管的导通值，三端双向晶闸管接通，控制带1 的电动机转动，包装箱传送带 1 开始传送。 （3）单片机执行程序：JB P1.0，LOOP1 ；检测包装箱是否到位，等待P1.0 为低电平。此时包装箱传送带1已开始运行，当还未送到位时，光电检测器1的发光器因无遮避物直接照到受光器（光敏三级管）上，光敏三极管受光照饱和导通，输出低电平，与它相连的P1.0接口置0，单片机顺序向下执行程序。（4）单片机执行程序：JNB P1.0，LOOP2；等待P1.0为高电平。当包装箱继续运行，遮住光电检测器1的受光器时，此时光敏三级管因为受不到光照而截止，输出高电平，与它相连的P1.0接口置1，单片机顺序向下执行程序。（5）单片机执行程序：ANL P1 ，#OBFH。P1.6 置 0，同理电动机 1 停止转动，包装箱传送带因惯性等因数，运行 84mm 后准确到位。（6）单片机执行程序：SETB P1.7 。P1.7 置 1，同理传送带 2 启动。（7）同理单片机执行下述程序：MOV R1 ，#00H ；计数器清零LOOP3： JNB P1.1，LOOP3 ；等待P1.1为高电平LOOP4： JB P1.1，LOOP4 ；等待P1.1为低电平，检测产品是否到来LOOP5： JNB P1.1，LOOP5 ；学院毕业设计 (论文 )31INC R1 ；计数器加1MOV A，R1XRL A，#64H ；箱内装100个产品吗？JNZ LOOP3 ；未满，继续（8）当产品装满后，返回从START重复执行程序，再对下一个货物箱进行装箱。如此循环，实现包装生产流水线的自动计数装箱。 学院毕业设计 (论文 )324 辅助设备的设计4.1 驱动头架的尺寸确定驱动头架用于支撑滚筒，减速器，电动机。整个装置架选用性能良好的槽钢支撑，角钢加固，钢板等用于固定电机，减速器，传动滚筒的机座。槽钢，角钢，钢板的连接使用焊接，焊缝均为连续角焊，焊件搭接处焊三面。 根据中心线的高度，固定电动机与减速器的架高 213mm，传动滚筒的架高 380mm，具体尺寸结构已于 CAD 图标出。4.2 拉紧尾架的尺寸确定拉紧尾架用于支撑传动滚筒，安装螺旋拉紧装置。因选用的拉紧行程为 500mm，结合传动滚筒的两滚筒座间距为 350mm，确定整个拉紧尾架的长为 1300mm，宽为多少 380mm。具体尺寸结构已于 CAD 图中标出。4.3 中间架的尺寸确定中间架用于安装上下托辊，采用两个 80mm 宽的槽钢，固定部分都采用螺栓联接。共有 3 段中间架，均长 3400mm，各中间架之间也用螺栓连接，便于运输和安装。结合上下托辊的尺寸，确定中间架的总长为 10200mm，宽为 916mm，高为 480mm。具体尺寸结构已于 CAD 中间架图中标出。4.4 传料板的尺寸确定在将包装箱输送装置和产品输送装置成丁字型布置时，由于两输送带之间有一定的距离，产品不能顺利落入包装箱内，因此需加一传料板。此传料板可起到传接产品，使产品准确落入箱中的作用。因传料板所承受的力很小，材料可采用铝板，以 45 度倾斜，并用螺栓将板固定在产品输送装置的头部驱动架上。具体结构见 CAD 装配图。学院毕业设计 (论文 )33结论本文从自动装箱系统整体设计出发, 主要对物品传动皮带机构和单片机控制电路这两部分进行了设计。其中物品传动皮带机构与常见的带式输送机结构相似，本文对该输送装置各组成部分：输送带、托辊、拉紧装置、驱动装置等进行了分析。对单片机控制过程进行了详细说明。得出以下主要结论：（1）输送带运动时的阻力包括直线区段、曲线区段以及一些附属装置所产生的局部阻力。本文对这三部分产生的阻力进行了计算并对带进行了强度校核，以保证输送装置能可靠、安全的运行。（2）考虑到工作现场的空间和减少传动链原则，本设计的驱动装置直接采用联轴器将电动机和减速器相连，减速器与传动滚筒相连。（3）拉紧装置给输送带一定的初始拉紧力，使在运行中始终使输送带保持一定的拉紧程度，以免在驱动滚筒上打滑，它是带式输送机不可缺少的重要组成部分。因这里输送装置的长度较短，综合比较各种拉紧装置，本设计选用了螺旋拉紧装置，它结构简单，拉紧行程小，适用于短距离输送机。当输送带因长时间工作变松时，可通过丝杠手动调整。（4）控制部分主要分析了单片机与光电传感器协同工作和数据处理等方面。本设计采用了最简单的单片机应用系统，它包括电源、时钟电路、输入/输出设备和复位电路。通过单片机对电动机等各机械部分的控制来实现系统要求，达到自动计数和装箱。 学院毕业设计 (论文 )34致谢经过三个多月的忙碌，本次毕业设计已经接近尾声，在此，我要感谢每一个帮助过我的人。 首先,我要感谢的是我的指导老师。他平日里工作繁多，但在我做毕业设计的每个阶段，都给予我悉心的指导和帮助。可以说，没有导师的悉心指导和帮助，我是不可能顺利完成我的毕业设计的。另外，他的治学严谨和科学研究精神值得我永远地学习，并将积极影响我今后的学习和工作。其次我要感谢我的父母,在我毕业设计最艰苦的那段日子,是他们给了我最大的精神支持。父母为了我的成长，一直在背后默默的付出和辛勤的工作，他们的养育之恩，我将用自己的一生去回报。再次，我要感谢帮助过我的同学，在我毕业设计期间，他们给了我不少的关心和帮助。最后，感谢母校对我的培养并感谢各位专家和教授对本文的评阅和指导。 学院毕业设计 (论文 )35参考文献1 马淑华.单片机原理与接口理论M.北京:北京邮电大学出版社,2005:1-24.2 王锡法.长距离变坡下运带式输送机的设计研究D.西安理工大学,2005.3 吴占和.基于光电传感器和单片机控制的产品自动装箱系统J；中国科技信息,2007,(12).4 朱龙根.简明机械零件设计手册M.北京:机械工业出版社,1997.5 成大先.机械设计手册M.北京:化学工业出版社,1993.6 机械设计手册编委会.减速器和变速器M.北京：机械工业出版社，2007. 7 起重运输机械零部件、操作件和小五金M.北京：机械工业出版社，2007.8 单丽云.工程材料M.徐州:中国矿业大学出版社,2000.9 邹丽新.单片微型计算机M.苏州:苏州大学出版社,2001.10邱宣怀.机械设计M.北京:高等教育出版社,1997.11王鹰.起重输送机械图册M. 北京:机械工业出版社,1992.12龚湘义.机械设计课程指导书M.北京:高等教育出版社,1990:7-15.13曾正明.机械材料手册M. 北京:机械工业出版社,2003.14谢铁邦.互换性与技术测量M.武汉:华中科技大学出版社,1998.15范思冲.画法几何及机械制图M.北京:机械工业出版社,1999.学院毕业设计 (论文 )36附录附录1英文原文Basic Machining Operations and Cutting TechnologyBasic Machining Operations Machine 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 workpiece and the cutting tool and can precisely control their relative positions and the velocity of the tool with respect to the workpiece. Basically, in metal cutting, a sharpened wedge-shaped tool removes a rather narrow strip of metal from the surface of a ductile workpiece in the form of a severely deformed chip. The chip is a waste product that is considerably shorter than the workpiece from which it came but with a corresponding increase in thickness of the uncut chip. The geometrical shape of workpiece 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 workpiece 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 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 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. They can be generated by radial 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 workpiece 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 workpiece 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 to 10 times the drill diameter. Whether the 学院毕业设计 (论文 )37drill turns or the workpiece rotates, relative motion between the cutting edge and the workpiece is the important factor. In milling operations a rotary cutter with a number of cutting edges engages the workpiece. 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 may be used, and the feed of the workpiece may be in any of the three coordinate directions. Basic Machine Tools Machine tools are used to produce a part of a specified geometrical shape and precise I 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: I turning, planning, drilling, milling, and grinding. 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; bobbing 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: lathes, planers, drilling machines and 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 I 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: it rigidly supports the workpiece or its holder and the cutting tool; it provides relative motion between the workpiece and the cutting tool; it provides a range of feeds and speeds usually ranging from 4 to 32 choices in each case. Speed and Feeds in Machining Speeds, 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 depth 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 (V) 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 of the needle radially inward per 学院毕业设计 (论文 )38revolution, or is the difference in position between two adjacent grooves. The depth of cut is the penetration of the needle into the record or the depth of the grooves. Turning on Lathe Centers The basic operations performed on an engine lathe are illustrated. Those operations performed on external surfaces with a single point cutting tool are called turning. Except for drilling, reaming, and lapping, 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 as 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 obtain the final size, shape, and surface finish on the workpiece. Sometimes a semi-finishing operation will precede the finishing operation to leave a small predetermined and uniform amount of stock on the work-piece to be removed by the finishing operation. Generally, longer workpieces 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 workpiece-usually along the axis of the cylindrical part. The end of the workpiece 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 workpiece may be held in a four-jaw chuck, or in a type chuck. This method holds the workpiece firmly and transfers the power to the workpiece smoothly; the additional support to the workpiece 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 workpiece accurately in the chuck. Very precise results can be obtained by supporting the workpiece between two centers. A lathe dog is clamped to the workpiece; together they are driven by a driver plate mounted on the spindle nose. One end of the Workpiece is mecained;then the workpiece can be turned around in the lathe to machine the other end. The center holes in the workpiece serve as precise locating surfaces as well as bearing surfaces to carry the weight of the workpiece and to resist the cutting forces. After the workpiece has been removed from the lathe for any reason, the center holes will accurately align the workpiece back in the lathe or in another lathe, or in a cylindrical grinding machine. The workpiece 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 workpiece in the chuck, this must not be done because it is not possible to press evenly with the jaws against the workpiece 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 学院毕业设计 (论文 )39perhaps even the lathe spindle. Compensating or floating jaw chucks used almost exclusively on high production work provide 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 workpieces are sometimes mounted on two centers, they are preferably held at the headstock end by faceplate jaws 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. Introduction of Machining Machining as a shape-producing method is the most universally used and the most important of all manufacturing processes. Machining is a shape-producing process in which a power-driven device causes material to be removed in chip form. Most machining is done with equipment that supports both the work piece and cutting tool although in some cases portable equipment is used with unsupported workpiece. Low setup cost for small Quantities. Machining has two applications in manufacturing. For casting, forging, and press working, each specific shape to be produced, even one part, nearly always has a high tooling cost. The shapes that may he produced by welding depend to a large degree on the shapes of raw material that are available. By making use of generally high cost equipment but without special tooling, it is possible, by machining; to start with nearly any form of raw material, so tong as the exterior dimensions are great enough, and produce any desired shape from any material. Therefore .machining is usually the preferred method for producing one or a few parts, even when the design of the part would logically lead to casting, forging or press working if a high quantity were to be produced. Close accuracies, good finishes. The second application for machining is based on the high accuracies and surface finishes possible. Many of the parts machined in low quantities would be produced with lower but acceptable tolerances if produced in high quantities by some other process. On the other hand, many parts are given their general shapes by some high quantity deformation process and machined only on selected surfaces where high accuracies are needed. Internal threads, for example, are seldom produced by any means other than machining and small holes in press worked parts may be machined following the press working operations. Primary Cutting Parameters The basic tool-work relationship in cutting is adequately described by means of four factors: tool geometry, cutting speed, feed, and depth of cut. 学院毕业设计 (论文 )40The cutting tool must be made of an appropriate material; it must be strong, tough, hard, and wear resistant. The tool s geometry characterized by planes and angles, must be correct for each cutting operation. Cutting speed is the rate at which the work surface passes by the cutting edge. It may be expressed in feet per minute. For efficient machining the cutting speed must be of a magnitude appropriate to the particular work-tool combination. In general, the harder the work material, the slower the speed. Feed is the rate at which the cutting tool advances into the workpiece. Where the workpiece or the tool rotates, feed is measured in inches per revolution. When the tool or the work reciprocates, feed is measured in inches per stroke, Generally, feed varies inversely with cutting speed for otherwise similar conditions. The depth of cut, measured inches is the distance the tool is set into the work. It is the width of the chip in turning or the thickness of the chip in a rectilinear cut. In roughing operations, the depth of cut can be larger than for finishing operations. The Effect of Changes in Cutting Parameters on Cutting Temperatures In metal cutting operations heat is generated in the primary and secondary deformation zones and these results in a complex temperature distribution throughout the tool, workpiece and chip. A typical set of isotherms is shown in figure where it can be seen that, as could be expected, there is a very large temperature gradient throughout the width of the chip as the workpiece material is sheared in primary deformation and there is a further large temperature in the chip adjacent to the face as the chip is sheared in secondary deformation. This leads to a maximum cutting temperature a short distance up the face from the cutting edge and a small distance into the chip. Since virtually all the work done in metal cutting is converted into heat, it could be expected that factors which increase the power consumed per unit volume of metal removed will increase the cutting temperature. Thus an increase in the rake angle, all other parameters remaining constant, will reduce the power per unit volume of metal removed and the cutting temperatures will reduce. When considering increase in unreformed chip thickness and cutting speed the situation is more complex. An increase in undeformed chip thickness tends to be a scale effect where the amounts of heat which pass to the workpiece, the tool and chip remain in fixed proportions and the changes in cutting temperature tend to be small. Increase in cutting speed; however, reduce the amount of heat which passes into the workpiece and this increase the temperature rise of the chip m primary deformation. Further, the secondary deformation zone tends to be smaller and this has the effect of increasing the temperatures in this zone. Other changes in cutting parameters have virtually no effect on the power consumed per unit volume of metal removed and consequently have virtually no effect on the cutting temperatures. Since it 学院毕业设计 (论文 )41has been shown that even small changes in cutting temperature have a significant effect on tool wear rate it is appropriate to indicate how cutting temperatures can be assessed from cutting data. The most direct and accurate method for measuring temperatures in high -speed-steel cutting tools is that of Wright &. Trent which also yields detailed information on temperature distributions in high-speed-steel cutting tools. The technique is based on the metallographic examination of sectioned high-speed-steel tools which relates microstructure changes to thermal history. Trent has described measurements of cutting temperatures and temperature distributions for high-speed-steel tools when machining a wide range of workpiece materials. This technique has been further developed by using scanning electron microscopy to study fine-scale microstructure changes arising from over tempering of the tempered martens tic matrix of various high-speed-steels. This technique has also been used to study temperature distributions in both high-speed -steel single point turning tools and twist drills. Wears of Cutting Tool Discounting brittle fracture and edge chipping, which have already been dealt with, tool wear is basically of three types. Flank wear, crater wear, and notch wear. Flank wear occurs on both the major and the minor cutting edges. On the major cutting edge, which is responsible for bulk metal removal, these results in increased cutting forces and higher temperatures which if left unchecked can lead to vibration of the tool and workpiece and a condition where efficient cutting can no longer take place. On the minor cutting edge, which determines workpiece size and surface finish, flank wear can result in an oversized product which has poor surface finish. Under most practical cutting conditions, the tool will fail due to major flank wear before the minor flank wear is sufficiently large to result in the manufacture of an unacceptable component. Because of the stress distribution on the tool face, the frictional stress in the region of sliding contact between the chip and the face is at a maximum at the start of the sliding contact region and is zero at the end. Thus abrasive wear takes place in this region with more wear taking place adjacent to the seizure region than adjacent to the point at which the chip loses contact with the face. This result in localized pitting of the tool face some distance up the face which is usually referred to as catering and which normally has a section in the form of a circular arc. In many respects and for practical cutting conditions, crater wear is a less severe form of wear than flank wear and consequently flank wear is a more common tool failure criterion. However, since various authors have shown that the temperature on the face increases more rapidly with increasing cutting speed than the temperature on the flank, and since the rate of wear of any type is significantly affected by changes in temperature, crater wear usually occurs at high cutting speeds. 学院毕业设计 (论文 )42At the end of the major flank wear land where the tool is in contact with the uncut workpiece surface it is common for the flank wear to be more pronounced than along the rest of the wear land. This is because of localised effects such as a hardened layer on the uncut surface caused by work hardening introduced by a previous cut, an oxide scale, and localised high temperatures resulting from the edge effect. This localised wear is usually referred to as notch wear and occasionally is very severe. Although the presence of the notch will not significantly affect the cutting properties of the tool, the notch is often relatively deep and if cutting were to continue there would be a good chance that the tool would fracture. If any form of progressive wear allowed to continue, dramatically and the tool would fail catastrophically, i. e. the tool would be no longer capable of cutting and, at best, the workpiece would be scrapped whilst, at worst, damage could be caused to the machine tool. For carbide cutting tools and for all types of wear, the tool is said to have reached the end of its useful life long before the onset of catastrophic failure. For high-speed-steel cutting tools, however, where the wear tends to be non-uniform it has been found that the most meaningful and reproducible results can be obtained when the wear is allowed to continue to the onset of catastrophic failure even though, of course, in practice a cutting time far less than that to failure would be used. The onset of catastrophic failure is characterized by one of several phenomena, the most common being a sudden increase in cutting force, the presence of burnished rings on the workpiece, and a significant increase in the noise level. Mechanism of Surface Finish Production There are basically five mechanisms which contribute to the production of a surface which have been machined. These are:(1) The basic geometry of the cutting process. In, for example, single point turning the tool will advance a constant distance axially per revolution of the workpiecc and the resultant surface will have on it, when viewed perpendicularly to the direction of tool feed motion, a series of cusps which will have a basic form which replicates the shape of the tool in cut. (2) The efficiency of the cutting operation. It has already been mentioned that cutting with unstable built-up-edges will produce a surface which contains hard built-up-edge fragments which will result in a degradation of the surface finish. It can also be demonstrated that cutting under adverse conditions such as apply when using large feeds small rake angles and low cutting speeds, besides producing conditions which lead to unstable built-up-edge production, the cutting process itself can become unstable and instead of continuous shear occurring in the shear zone, tearing takes place, discontinuous chips of uneven thickness are produced, and the resultant surface is poor. This situation is particularly noticeable when machining very ductile materials such as copper and aluminum. 学院毕业设计 (论文 )43(3) The stability of the machine tool. Under some combinations of cutting conditions; workpiece size, method of clamping ,and cutting tool rigidity relative to the machine tool structure, instability can be set up in the tool which causes it to vibrate. Under some conditions this vibration will reach and maintain steady amplitude whilst under other conditions the vibration will built up and unless cutting is stopped considerable damage to both the cutting tool and workpiece may occur. This phenomenon is known as chatter and in axial turning is characterized by long pitch helical bands on the workpiece surface and short pitch undulations on the transient machined surface. (4) The effectiveness of removing swarf. In discontinuous chip production machining, such as milling or turning of brittle materials, it is expected that the chip (swarf) will leave the cutting zone either under gravity or with the assistance of a jet of cutting fluid and that they will not influence the cut surface in any way. However, when continuous chip production is evident, unless steps are taken to control the swarf it is likely that it will impinge on the cut surface and mark it. Inevitably, this marking besides looking. (5) The effective clearance angle on the cutting tool. For certain geometries of minor cutting edge relief and clearance angles it is possible to cut on the major cutting edge and burnish on the minor cutting edge. This can produce a good surface finish but, of course, it is strictly a combination of metal cutting and metal forming and is not to be recommended as a practical cutting method. However, due to cutting tool wear, these conditions occasionally arise and lead to a marked change in the surface characteristics. Limits and Tolerances Machine parts are manufactured so they are interchangeable. In other words, each part of a machine or mechanism is made to a certain size and shape so will fit into any other machine or mechanism of the same type. To make the part interchangeable, each individual part must be made to a size that will fit the mating part in the correct way. It is not only impossible, but also impractical to make many parts to an exact size. This is because machines are not perfect, and the tools become worn. A slight variation from the exact size is always allowed. The amount of this variation depends on the kind of part being manufactured. For examples part might be made 6 in. long with a variation allowed of 0.003 (three-thousandths) in. above and below this size. Therefore, the part could be 5.997 to 6.003 in. and still be the correct size. These are known as the limits. The difference between upper and lower limits is called the tolerance. A tolerance is the total permissible variation in the size of a part. The basic size is that size from which limits of size arc derived by the application of allowances and tolerances. Sometimes the limit is allowed in only one direction. This is known as unilateral tolerance.学院毕业设计 (论文 )44Unilateral tolerancing is a system of dimensioning where the tolerance (that is variation) is shown in only one direction from the nominal size. Unilateral tolerancing allow the changing of tolerance on a hole or shaft without seriously affecting the fit.When the tolerance is in both directions from the basic size it is known as a bilateral tolerance (plus and minus). Bilateral tolerancing is a system of dimensioning where the tolerance (that is variation) is split and is shown on either side of the nominal size. Limit dimensioning is a system of dimensioning where only the maximum and minimum dimensions arc shown. Thus, the tolerance is the difference between these two dimensions. Surface Finishing and Dimensional Control Products that have been completed to their proper shape and size frequently require some type of surface finishing to enable them to satisfactorily fulfill their function. In some cases, it is necessary to improve the physical properties of the surface material for resistance to penetration or abrasion. In many manufacturing processes, the product surface is left with dirt .chips, grease, or other harmful material upon it. Assemblies that are made of different materials, or from the same materials processed in different manners, may require some special surface treatment to provide uniformity of appearance. Surface finishing may sometimes become an intermediate step processing. For instance, cleaning and polishing are usually essential before any kind of plating process. Some of the cleaning procedures are also used for improving surface smoothness on mating parts and for removing burrs and sharp corners, which might be harmful in later use. Another important need for surface finishing is for corrosion protection in a variety of: environments. The type of protection procedure will depend largely upon the anticipated exposure, with due consideration to the material being protected and the economic factors involved. Satisfying the above objectives necessitates the use of main surface-finishing methods that involve chemical change of the surface mechanical work affecting surface properties, cleaning by a variety of methods, and the application of protective coatings, organic and metallic. In the early days of engineering, the mating of parts was achieved by machining one part as nearly as possible to the required size, machining the mating part nearly to size, and then completing its machining, continually offering the other part to it, until the desired relationship was obtained. If it was inconvenient to offer one part to the other part during machining, the final work was done at the bench by a fitter, who scraped the mating parts until the desired fit was obtained, the fitter therefore being a fitter in the literal sense. It is obvious that the two parts would have to remain together, and m the event of one having to be replaced, the fitting would have to be done all over again. In these days, we expect to be able to purchase a replacement for 学院毕业设计 (论文 )45a broken part, and for it to function correctly without the need for scraping and other fitting operations.When one part can be used off the shelf to replace another of the same dimension and material specification, the parts are said to be interchangeable. A system of interchangeability usually lowers the production costs as there is no need for an expensive, fiddling operation, and it benefits the customer in the event of the need to replace worn parts. Automatic Fixture Design Traditional synchronous grippers for assembly equipment move parts to the gripper centre-line, assuring that the parts will be in a known position after they arc picked from a conveyor or nest. However, in some applications, forcing the part to the centre-line may damage cither the part or equipment. When the part is delicate and a small collision can result in scrap, when its location is fixed by a machine spindle or mould, or when tolerances are tight, it is preferable to make a gripper comply with the position of the part, rather than the other way around. For these tasks, Zaytran Inc. Of Elyria, Ohio, has created the GPN series of non- synchronous, compliant grippers. Because the force and synchronizations systems of the grippers are independent, the synchronization system can be replaced by a precision slide system without affecting gripper force. Gripper sizes range from 51b gripping force and 0.2 in. stroke to 40Glb gripping force and 6in stroke. Grippers Production is characterized by batch-size becoming smaller and smaller and greater variety of products. Assembly, being the last production step, is particularly vulnerable to changes in schedules, batch-sizes, and product design. This situation is forcing many companies to put more effort into extensive rationalization and automation of assembly that was previouslyextensive rationalization and automation of assembly that was previously the case. Although the development of flexible fixtures fell quickly behind the development of flexible handling systems such as industrial robots, there are, nonetheless promising attempts to increase the flexibility of fixtures. The fact that fixtures are the essential product - specific investment of a production system intensifies the economic necessity to make the fixture system more flexible. Fixtures can be divided according to their flexibility into special fixtures, group fixtures, modular fixtures and highly flexible fixtures. Flexible fixtures are characterized by their high adaptability to different workpieces, and by low change-over time and expenditure. There are several steps required to generate a fixture, in which a workpiece is fixed for a production task. The first step is to define the necessary position of the workpiece in the fixture, based on the unmachined or base pan, and the working features. Following this, a combination of stability planes must be selected. These stability planes constitute the fixture configuration in which the workpiece is fixed in the defined position, all the forces or torques are compensated, 学院毕业设计 (论文 )46and the necessary access to the working features is ensured. Finally, the necessary positions of moveable or modular fixture elements must be calculated- adjusted, or assembled, so that the workpiece is firmly fixed in the fixture. Through such a procedure the planning and documentation of the configuration and assembly of fixture can be automated.The configuration task is to generate a combination of stability planes, such that fixture forces in these planes will result in workpiece and fixture stability. This task can be accomplished conventionally, interactively or in a nearly fully automated manner. The advantages of an interactive or automated configuration determination are a systematic fixture design process, a reduction of necessary designers, a shortening of lead time and better match to the working conditions. In short, a significant enhancement of fixture productivity and economy can be achieved.学院毕业设计 (论文 )47附录2中文翻译基本加工工序和切削技术 机床是从早期的埃及人的脚踏动力车和约翰威尔金森的镗床发展而来的。它们为工件和刀具提供刚性支撑并可以精确控制它们的相对位置和相对速度。基本上讲，金属切削是指一个磨尖的锲形工具从有韧性的工件表面上去除一条很窄的金属。切屑是被废弃的产品，与其它工件相比切屑较短，但对于未切削部分的厚度有一定的增加。工件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。大多数加工工序产生不同几何形状的零件。如果一个粗糙的工件在中心轴上转动并且刀具平行于旋转中心切入工件表面，一个旋转表面就产生了，这种操作称为车削。如果一个空心的管子以同样的方式在内表面加工，这种操作称为镗孔。当均匀地改变直径时便产生了一个圆锥形的外表面，这称为锥度车削。如果刀具接触点以改变半径的方式运动，那么一个外轮廓像球的工件便产生了；或者如果工件足够的短并且支撑是十分刚硬的，那么成型刀具相对于旋转轴正常进给的一个外表面便可产生，短锥形或圆柱形的表面也可形成。平坦的表面是经常需要的，它们可以由刀具接触点相对于旋转轴的径向车削产生。在刨削时对于较大的工件更容易将刀具固定并将工件置于刀具下面。刀具可以往复地进给。成形面可以通过成型刀具加工产生。 多刃刀具也能使用。使用双刃槽钻钻深度是钻孔直径5-10倍的孔。不管是钻头旋转还是工件旋转，切削刃与工件之间的相对运动是一个重要因数。在铣削时一个带有许多切削刃的旋转刀具与工件接触，工件相对刀具慢慢运动。平的或成形面根据刀具的几何形状和进给方式可能产生。可以产生横向或纵向轴旋转并且可以在任何三个坐标方向上进给。基本机床基本机床 机床通过从塑性材料上去除屑片来产生出具有特别几何形状和精确尺寸的零件。后者是废弃物，是由塑性材料如钢的长而不断的带状物变化而来，从处理的角度来看，那是没有用处的。很容易处理不好由铸铁产生的破裂的屑片。机床执行五种基本的去除金属的过程：车削，刨削，钻孔，铣削。所有其他的去除金属的过程都是由这五个基本程序修改而来的，举例来说，镗孔是内部车削；铰孔，攻丝和扩孔是进一步加工钻过的孔；齿轮加工是基于铣削操作的。抛光和打磨是磨削和去除磨料工序的变形。因此，只有四种基本类型的机床，使用特别可控制几何形状的切削工具。它们是：车床，钻床，铣床和磨床。磨削过程形成了屑片，但磨粒的几何形状是不可控制的。 通过各种加工工序去除材料的数量和速度是巨大的，正如在大型车削加工，或者是学院毕业设计 (论文 )48极小的如研磨和超精密加工中只有面的高点被除掉。一台机床履行三大职能：它支撑工件或夹具和刀具；它为工件和刀具提供相对运动
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