分功率壳体卧式双面钻孔专用机床设计说明书
分功率壳体卧式双面钻孔专用机床设计说明书,功率,壳体,卧式,双面,钻孔,专用,机床,设计,说明书,仿单
分功率壳体卧式双面钻孔专用机床设计目 录引言4第一章 通用部件简介 61.通用部件的分类 62.动力部件63.支承部件74.控制部件85.辅助部件8第二章 组合机床的总体设计的步骤81组合机床工艺方案的制定82确定切削用量及选择刀具93组合机床总体设计三图一卡10第三章组合机床多轴箱设计121概述122设计原则14第四章夹具的设计1定位基准的选择152 夹紧力的计算15第五章液压原理图161液压传动图16第六章PLC梯形图161 工作原理及电气控制要求162 电气控制系统硬件设计163.电气控制系统软件设计17结论17致谢18参考文献18附录A 综述 附录B 调研报告附录C 外文翻译附录D 原文引言组合机床是一种自动化或半自动化的机床.无论是机械电气或液压电气控制的都能实现自动循环.半自动化的组合机床,工人只要将工件装夹好,按一下按钮,机床即可自动进行加工,加工一个循环停止.自动化的组合机床,工人只要将工件放到料斗或上料架上,机床即可连续不断的进行工作.我国传统的组合机床及组合机床自动线主要采用机、电、气、液压控制,它的加工对象主要是生产批量比较大的大中型箱体类和轴类零件(近年研制的组合机床加工连杆、板件等也占一定份额) ,完成钻孔、扩孔、铰孔,加工各种螺纹、镗孔、车端面和凸台,在孔内镗各种形状槽,以及铣削平面和成形面等。组合机床的分类繁多,有大型组合机床和小型组合机床,有单面、双面、三面、卧式、立式、倾斜式、复合式,还有多工位回转台式组合机床等;随着技术的不断进步,一种新型的组合机床柔性组合机床越来越受到人们的青睐,它应用多位主轴箱、可换主轴箱、编码随行夹具和刀具的自动更换,配以可编程序控制器( PLC) 、数字控制(NC) 等,能任意改变工作循环控制和驱动系统,并能灵活适应多品种加工的可调可变的组合机床。另外,近年来组合机床加工中心、数控组合机床、机床辅机(清洗机、装配机、综合测量机、试验机、输送线) 等在组合机床行业中所占份额也越来越大。由于组合机床及其自动线是一种技术综合性很高的高技术专用产品,是根据用户特殊要求而设计的,它涉及到加工工艺、刀具、测量、控制、诊断监控、清洗、装配和试漏等技术。我国组合机床组合机床自动线总体技术水平比发达国家要相对落后,国内所需的一些高水平组合机床及自动线几乎都从国外进口。工艺装备的大量进口势必导致投资规模的扩大,并使产品生产成本提高。因此,市场要求我们不断开发新技术、新工艺,研制新产品,由过去的“刚性”机床结构,向“柔性”化方向发展,满足用户需求,真正成为刚柔兼备的自动化装备。随着市场竞争的加剧和对产品需求的提高,高精度、高生产率、柔性化、多品种、短周期、数控组合机床及其自动线正在冲击着传统的组合机床行业企业,因此组合机床装备的发展思路必须是以提高组合机床加工精度、组合机床柔性、组合机床工作可靠性和组合机床技术的成套性为主攻方向。一方面,加强数控技术的应用,提高组合机床产品数控化率;另一方面,进一步发展新型部件,尤其是多坐标部件,使其模块化、柔性化,适应可调可变、多品种加工的市场需求。从2002 年年底第21 届日本国际机床博览会上获悉,在来自世界10 多个国家和地区的500 多家机床制造商和团体展示的最先进机床设备中,超高速和超高精度加工技术装备与复合、多功能、多轴化控制设备等深受欢迎。据专家分析,机床装备的高速和超高速加工技术的关键是提高机床的主轴转速和进给速度。该届博览会上展出的加工中心,主轴转速10 00020 000 r/ min ,最高进给速度可达2060 m/ min ;复合、多功能、多轴化控制装备的前景亦被看好。在零部件一体化程度不断提高、数量减少的同时,加工的形状却日益复杂。多轴化控制的机床装备适合加工形状复杂的工件。另外,产品周期的缩短也要求加工机床能够随时调整和适应新的变化,满足各种各样产品的加工需求。然而更关键的是现代通信技术在机床装备中的应用,信息通信技术的引进使得现代机床的自动化程度进一步提高,操作者可以通过网络或手机对机床的程序进行远程修改,对运转状况进行监控并积累有关数据;通过网络对远程的设备进行维修和检查、提供售后服务等。在这些方面我国组合机床装备还有相当大的差距,因此我国组合机床技术装备高速度、高精度、柔性化、模块化、可调可变、任意加工性以及通信技术的应用将是今后的发展方向。第一章 通用部件简介1.通用部件的分类 1.1. 通用部件已列为国家标准,并等效为国际标准,设计时应贯彻执行国家标准。我国有些企业有内部标准,但其主要技术参数及部件和联系尺寸必须统一执行国家标准,以实现部件通用化标准。2.动力部件2.1动力滑台是由滑座、滑鞍和驱动装置等组成,是实现组合机床直线进给运动的动力部件。 动力滑台的用途:根据被加工工件的工艺要求,可以在滑台上安装动力箱、钻削头、铣削头和镗孔车端面头等各种部件,以完成对工件的钻孔、扩孔、铰孔、螳孔、倒角、削端面、车端面、铣削及攻丝等工序,有时也作为输送部件使用,配置多工位组合机床。2.2TD系列动力箱的用途 动力箱是将电动机的动力传递给多轴箱的动力部件。动力箱安装在滑台或其它进给部件的结合面上,动力箱前端结合面上安装多轴箱,动力箱的输出轴驱动动力箱的每个主轴及传动轴,使多轴箱完成各种工艺切削运动。1DT系列动力箱分两种:第一种根据用于配置小型组合机床,其型号为1DT121DT25,本规格的动力箱输出轴有两种传动形式,I型用输出轴安装的平键,齿轮输出转矩;II型用输出轴端面键输出转矩。第二种动力箱用于配置大型组合机床,其规格为1DT321DT80,其输出轴只有平键,齿轮一种输出转矩的形式。液压滑台:1HY系列液压滑台;1HYA系列长台面型液压滑台;1HYS系列液压十字滑台。机械滑台:1HJ系列机械滑台;1HJC系列机械滑台;NC-1HJ系列交流伺服数机械滑台。3.支承部件 组合机床支承部件包括中间底座,侧底座,立柱,立柱底座,支架及垫块等。支承部件主要用来安装动力部件及其它工作部件是组合机床的基础部件。支承部件应用于足够的刚度,以保证各部件之间相对位置精度长期正确,从而保证组合机床的加工精度。组合机床的支承部件采用组合式,例如:卧式组合机床的床身,由中间底座与侧底座装配而成,而立式组合机床的床身由立柱及立柱底座装配而成。此种装配结构优点是加工和装配工艺性好,调整和运输比较方便。但是,组合式结构减弱了床身的整体刚性,这一缺点通常用加强部件之间的连接刚度来补偿。3.1.1CC系列滑台侧底座1CC系列滑台侧底座用于安装1HY系列液压滑台及各种机械滑台侧底座长度按滑台行程长度分型并与其配套。滑座安装在侧底座上,侧底座与中间底座用螺钉及销(或键)连接成一体,滑台与侧底座之间装有5mm厚的调整垫。采用调整垫铁对机床的制造和维修都方便。因为当滑座导轨磨损后,或重新组装机床时,只须取下滑台将导轨面重新修刮或修磨,再重新更换调整垫厚度,可使机床达到应有精度。 侧底座的顶面具有与滑座结合的平面外在其周围有收集冷却液或润滑油用的沟槽,用管道将油液引回存储槽中,侧底座的另一侧面有电气壁盒,以供安装电器元件用。一般电器壁盒与冷却液存储箱不应靠近,以防电气元件潮湿。为了便于支承部件及整台机床运输,侧底座应用走丝吊孔或吊环螺钉孔及放入撬杠用的底面凹槽。4.控制部件 控制部件用来控制组合机床行动循环。5.辅助部件 除上述部件外的部件称辅助部件,主要指用于润滑、冷却和排屑等部件。第二章 组合机床的总体设计的步骤1组合机床工艺方案的制定 双面钻孔组合机床是在工件两相对表面上钻孔的一种高效率自动化专用加工设备。机床的两个液压动力滑台对面布置,左、右刀具电动机分别固定在两边的滑台上,中间底座上装有工件定位夹紧装置。组合机床的总体设计通常是根据与用户签定的和同和协议书,针对具体加工零件,拟订工艺和结构方案,并进行方案图样和有关技术文件的设计。根据工艺方案确定机床的型式和总体布局。在选择机床配置型式时,既考虑到实现工艺方案,保证加工精度、技术要求及生产率,又考虑到机床操作、维护、修理和排屑的方便性。在选择组合钻床结构方案时,必须保证稳定的加工精度。固定式夹具组合钻床能达到的钻孔位置精度最高,采用固定导套一般能达 0.20mm。考虑到操作的方便性,需要合理确定装料高度为使钻床在温度过高时工作性能稳定,而且由于被加工件不需多次进给,故选用机械通用部件配置钻床。根据被加工零件的特点,为实现加工精度要求,同时考虑到经济效益和生产率,经过反复论证、分析和计算,我们采用了卧式双面多轴钻、组合机床的总体设计方案。本机床采用多工位卧式组合机床,变速箱体装在工作台的夹具上,这样便于上、下料。机床机械部分主要有:底座、侧底座、多轴箱、刀具、夹具、冷却系统;控制部分为PLC 控制系统及液压传动系统。机床的工作循环为:人工装上一工件,定位销插销定位夹紧油缸夹紧I 滑台开始工作循环:快进(冷却供、主轴转) 工进(死档铁停留) 快退至原位(主轴停) 滑台开始工作循环:快进(冷却供、主轴转) 工进(死档铁停留) 快退至原位(主轴停、冷却停) ,定位销拔出,夹紧油缸松开,防护门自动打开,油缸推出工件,工件到位后油缸退回 ,死档铁停留,工作循环结束2确定切削用量及选择刀具切削用量选择是否合理,对组合机床的加工精度、生产率、刀具的耐用度、机床的布局及正常工作均有很大的影响。 组合机床切削用量的选择特点:2.1.在大多数情况下,组合机床为多轴,多刀,多面同时加工,因此切削用量,根据经验应比一般万能机床单刀加工低30%左右。2.2.组合机床多轴箱下,所有刀具共用一个进给系统,通常为标准动力滑台,工作时,要求所以的刀具的每分钟进给量相同,且等于动力滑台的分钟进给量。由于工件材料:HT200 壁厚:2.510 HBS:157236 =220查工艺师手册钻孔切削速度查得:铸铁:v=1624m/min.取v=20m/min,f=0.15/0.12mm/r3.三图一卡设计3.1.加工示意图加工示意图的作用和内容 零件的加工工艺方案要通过加工示意图反映出来,加工示意图表示被加工零件在机床尚的加工过程,刀具辅具的布置状况以及工件,夹具,刀具等机床各部件间的相对位置关系,机床的工作行程及工作循环等。因此,加工示意图是组合机床设计的主要图纸之一。在总体设计中占据重要地位。它是刀具,辅具,夹具,多轴箱,液压电气装置设计及通用部件选择的主要原始资料;也是整台组合机床布局和性能的原始要求,同时还是调整机床刀具及成车的依据,其内容为:(1)应反映机床的加工方法,加工条件及加工过程。(2)根据加工部位特点及加工要求,决定刀具类型,数量,结构,尺寸(直径和长度),包括镗削加工是膛杆直径和长度。(3)决定主轴的结构类型,规格尺寸及外伸长度。(4)选择标准或设计专用的接杆,浮动卡头,导向装置,攻丝靠模装置,刀杆托架等,并决定它们的结构参数及尺寸。(5)标明主轴,接杆,夹具(导向)与工件之间的联系尺寸,配合及精度。(6)根据机床要求的生产率及刀具,材料特点等,合理正确定并标注各主轴的切削用量。3.2被加工零件工序图被加工零件为分功率器壳体,材料为H200,工序为箱体两端面钻孔,左端面为12个10加工孔和8个6,右端面为6个10和8个6加工孔。采用一面两孔定位,一面为箱体底面,两孔为底面上的长边上的两孔。采用箱体顶面夹紧。3.3加工示意图加工10的孔:锥柄长麻花钻 硬质合金 d=10mm L=168mm L1=87mm依据公式 M= , 选刚性主轴,直径为30/20mm 外伸长度为115 mm 切削用量 v=20 m/min f=0.15 mm/r 加工6的孔:锥柄麻花钻 硬质合金 d=6mm L=138 mm L1=57mm依据公式 M= 选刚性主轴,直径为22/14mm 外伸长度为115 mm 切削用量 v=30m/min f=0.15 mm/r 箱体左端面工进长度35 mm 快进85mm 快退120 mm箱体右端面工进长度35 mm 快进 85mm 快退120 mm3.4机床联系尺寸图左端面:20根主轴 右端面:14根主轴 多轴箱轮廓尺寸 H=336+100+100=536 mm B=400+2100=600 mm 厚度取325 mm长宽取630630 mm 最低孔位置44mm 最低主轴高度100 mm轴向力=1371.2N转矩 =7282.4Nmm功率 =0.274kw18=4.932kw18=19745.28N根据以上计算所得 选取液压动力滑台1HY40 动力箱1TD40-IIA (7.5kw)电机 Y132M-4 侧底座 1CC4013.5机床生产率计算卡 机床负荷率等。根据选定得机床工作循环所需要的工作行程长度,切削用量,动力部件的速度及工进速度等;就可以计算机床的生产率并编制生产率计算卡;用以反映机床的加工过程;完成每一动作所需的时间,切削用量,机床生产率等(1)机床生产效率计算卡1. 理想生产率 =23 件/h2. 实际生产率 =31件/h3. 机床负荷率 =0.75第三章组合机床多轴箱设计1.概述组合机床多轴箱的设计计算是组合机床设计工程中的重要环节,是主轴箱零部件设计的理论基础,计算稍有不慎,便会导致后期的设计制造前功尽弃。依据总体设计图, 对主轴箱进行结构创新设计。由于在本机床上需同时加工12个孔,不仅孔多、间距小,而且孔的排列分散,采用通常方案排箱无法实现12孔的工序集中。因此,本钻床的主轴箱传动系统在对被加工零件进行了深入、细致分析计算的基础上,通过采用滚针轴承,将常规状况下不能完成的排箱得以实现,而且所设计的主轴箱结构紧凑。(该设计只设计左面多轴箱的结构,右面多轴箱类似)依据组合钻床总体设计绘制主轴箱设计原始依据图其内容为主轴箱设计的原始要求和已知条件:1. 主轴箱轮廓尺寸630mm630mm;2. 工件轮廓尺寸及各孔位置尺寸主轴及通用传动轴结构型式的选择方案主轴结构型式由零件的加工工艺决定,并考虑主轴的工作条件和受力情况,采用长主轴。由于采用钻削加工主轴,需承受较大的单向轴向力,所以优选向心球轴承和推力球轴承组合的支承结构,且推力球轴承配置在主轴前端。传动轴的转速较低,但载荷较大,因此用圆锥滚子轴承。按上述方案配置的主轴和传动轴,按所选的轴承类型绘制轴承孔检查图,发现有些部位采用此配置因孔间距较小,箱体上的轴承座孔太大,导致箱体强度不够。因此,这些部位都将原方案改为推力球轴承与滚针轴承组合的支承结构,以减小径向尺寸,满足强度要求,实现合理排箱。 按以上原则设计的传动系统,保证了主轴箱的质量,提高了主轴箱的通用化程度,使得设计和制造工作量及成本都大大降低。为实现本机床“体积小、质量轻、结构简单、使用方便、效率高、质量好”的设计目标奠定了基础。2.设计原则1) 从面对主轴的方位看去,所有主轴均采用逆时针方向旋转。2) 在保证转速和转向的前提下,力求用最少的传动轴和齿轮(数量和规格),以减少各类零件的品种。具体措施:采用一根传动轴同时带动多根主轴,并将齿轮布置在同一排位置上,当齿轮啮合中心距不符合标准时,采用了变位齿轮。3) 放弃了用主轴带主轴的方案,这样避免了增加主轴负荷,不会影响加工质量。4) 为使主轴箱结构紧凑,主轴箱内齿轮传动副的传动比都在1.01.5之间。5) 为了使主轴上的齿轮不太大,有的在最后一级采用升速传动。6) 因钻削加工切削力大,为了减少主轴的扭曲变形,主轴上的齿轮尽量靠近前支承。对传动系统的一般要求1) 尽量用一根中间轴带动很多根主轴,当齿轮齿合中心距不符合标准时,可用变位齿轮或略变传动比的方法解决.2) 一般情况下,尽量不采用主轴带动主轴的方案,因为会增加主动轴的负荷,如遇到主轴分布密集而切削负荷又不大时,为了减少中心轴,也可用一根主轴带1-2根或更多根主轴的传动方案.3) 为使结构紧凑多轴箱体的齿轮传动副的最佳传动比为1-1.5,在多轴箱后盖内的第IV排(或第V排)齿轮,根据需要,其传动比可以取大些,但一般不超过33.5。4) 根据转速与转距成反比的道理,一般情况下如驱动轴转速较高时,可采用逐步降速传动,如驱动轴转速较低时可先使速度升高一点再降速,这样可使传动链前面几根轴齿轮上的齿轮应尽量安排靠近前支承,以减少主轴的扭转变形。5)粗加工切削力大,主轴上的齿轮应尽量安排靠近前支承,以减少主轴的扭转变形。6)齿轮安排数可按下面方法安排:不同轴上齿轮不相碰,可放在箱体内同一排上。不同轴上齿轮与轴或轴套不相碰,可放在箱体内不同排上。齿轮与轴相碰,可放在后盖内。四专用夹具结构设计机床夹具是在机床上所使用的一种辅助装置,用它来准确迅速地确定工件与机床刀具间地相对位置,即将工件定位及夹紧,以完成加工所需地相对运动。使用夹具地最终目的是保证产品质量,改善工人劳动条件,提高生产效率,降低产品成本。1定位基准的选择由零件图可知,采用双面加工的方法,同时为了缩短辅助时间采用液压夹紧。2 夹紧力的计算查机床夹具设计手册表1211 工件以平面定位,夹紧力与切削力方向垂直。 其中为基本安全系数1,2 为加工性质系数1,2 为刀具钝化系数1 为断续切削系数10.16 0.7 2.5则2750N 现选用地脚式的液压缸,查机床夹具设计手册: 故本夹具可安全工作。第五章液压原理图第六章PLC控制设计1 工作原理及电气控制要求双面钻孔组合机床是在工件两相对表面上进行钻孔的一种高效自动化专用加工设备 。2 个动力滑台对面布置并安装在标准侧底座上,刀具电动机M2 ,M3 分别固定在左、右动力滑台上,中间底座上装有工件定位夹紧装置。该机床采用电动机和液压系统(未画出) 相结合的驱动方式,其中电动机M2 ,M3 分别带动左、右主轴箱的刀具主轴提供切削主运动,而左、右动力滑台和工件定位夹紧装置则由液压系统驱动,M1 为液压泵的驱动电动机,M4 为冷却泵电动机。机床的电气控制要求为M1 先启动,只有系统正常供油后,其它控制电路才能通电工作; M2 ,M3在滑台进给循环开始时启动,滑台退回原位后停机;M4 可手动控制启停,也可在滑台工作进给时自动提供油液。其控制过程是典型的顺序控制,当把工件装入夹具后,按下启动按钮SB3 ,机床便开始自动循环的工作过程.2 电气控制系统硬件设计双面钻孔组合机床的电气控制属单机控制, 输入输出均为开关量。根据实际控制要求,并考虑系统改造成本,在准确计算I/ O 总点数的基础上,采用抗干扰强、稳定性和可靠性较高的三菱公司生产的FX1N260MR 可编程控制器。该控制系统中所有输入触发信号采用常开触点接法,所需的24 V 直流电源由PLC 内部提供;输出负载中的所有直流电磁换向阀同样采用由PLC 内部提供的24 V 直流电源,输出负载中的4 个交流接触器线圈则需外接220 V 交流电源.由于双面钻孔组合机床中转换开关、按钮及行开关较多,为了减少输入点数,降低费用,对输入信号作了适当处理,如4 台电动机的过载保护不作为输入信号,而直接接入输出线圈回路中。另外,电磁阀为感性负载并且通断频繁,为了保护PLC 的输出触点,在每个电磁阀两端各并上1 个续流二极管,来吸收反向过电压。3.电气控制系统软件设计由双面钻孔组合机床的控制要求可知,该控制系统需要实现3 个控制功能: 动力滑台的点动、复位控制; 动力滑台的单机自动循环控制; 整机全自动工作循环控制。本程序经模拟调试,完全符合双面钻孔组合机床的电气控制要求,使用效果良好。在使用过程中,还可根据不同的控制要求,在不改动接线或改动很少的情况下,通过改变程序来实现不同要求,大大节省了安装调试时间,提高了效率。结论本系统经过PLC 融入后,运行良好,故障率低。而且组合机床控制系统具有很好的柔性,能适应产品的变化,当工艺程序变更时,只需修改程序,就可满足新的加工要求。可见传统的机械设备融入PLC技术 后,既能使之成为机电一体化的新产品,适用生产过程的自动控制,又能发挥原组合机床的效能,而且投资较小,可见,灵活应用PLC 是实现组合机床电气自动化的有效途径。本组合机床较好地解决了大批量钻变速箱两端面孔的问题。不但保正加工质量,而且大为提高了工效,具有良好的经济效益和应用价值。致谢这次设计是在范真导师的精心指导下完成的。范老师进场抽出大量宝贵时间来关心我们,并且经常指导我的毕业设计。每当我们在设计上遇到什么问题或是有什么想不通的,她都会细心的讲解,直到我们懂为止,在此,献上诚挚的谢意。还要谢谢在设计中帮助我的同学,以及帮我答辩的各位老师!参考资料1、组合机床设计沈阳工业大学、吉林工业大学、大连铁道学院主编上海出版社出版1985年9月2、组合机床设计大连组合机研究所编机械工业出版社1975年6月3、金属切削加工工艺人员手册上海科学技术出版社4、金属切削机床设计参考图册机械工业出版社5、金属切削机床设计大连工学院戴曙主编机械工业出版1985年12月6、组合机床液压滑台图册机械工业出版社7、机械设计手册辽宁科学技术出版社8、机床设计手册机械工业出版社1978年12月9、组合机床设计参考图册大连组合机床研究所编机械工业出版社19 The Development and Application of a Planar Encoder MeasuringSystem for Performance Tests of CNC Machine ToolsW. JyweDepartment of Automation Engineering, National Huwei Institute of Technology, Huwei, Yunlin, TaiwanIn this paper, a measuring device with a planar encoder is developed to test the performance of a CNC machine tool. With the assistance of a PC, this system can be employed for both 2D contouring tests and 3D positioning tests for a CNC machine tool. The structure and the principle of the system, the applications for the general 2D contouring test, the drift test, and the specified geometric part path tests. An actual case study on improving the accuracy of machining a cam aredescribed. Finally, a new 3D positioning method using the optic encoder is demonstrated.Keywords: Ball bar system; CNC machine tool; Geometric part path; Planar encoder; Thermal drift test; Three-dimensional positioning; Two-dimensional contouring1. IntroductionMachine tool performance and consistency is the main determinant of the quality of parts machined by it. It is of importance to check the performance of the machine tool systematicallyfor direct quality control purposes or to compensate for this uncertainty. Schlesinger, in 1932 1, first provided a systematic testing method for machine tools. This method was developed as the basis of the ISO standard. Tlusty, in 1959 2, employed an electric level and sensor to test the spindle accuracy. Tlusty and Koenigsberger 3 and Burdekin 4 indicated new testing rules for machine tools. Burdekin 5 checked the relation between the motion accuracy of machine tools and the machined part. Tlusty 6 proposed a non-cutting testing method. The tests for machine tool performance were then classified into a direct cutting test and an indirect cutting test. Ericson 7 first described the work zone of machine tools. Bryan and Pearson 8 explained the definition and the way to measure the pitch, roll and yaw motion and straightness error. After the commercial laser interferometer 9 was available, the analysis of volumetric errors 1013 was described. Voutsudopoulos and Burdekin 14 indicated a calibrating model for a coordinate measuring machine. Fan 15 used a laser interferometer and a related device with the assistance of a PC to calibrate different types of NC machine tools. Zhang and Hockey 16 obtained the 21 error components by measuring the position errors. Zhang and Zang 17 designed a 1-D ball array to find the 21 error components, then Zhang 18 described a rapid method to obtain the straightness error. In 2000, Jywe 19 described a method of employing a ball bar system for the verification of the volumetric error of CNC machine tools. Circular tests were developed to check both geometric errors and contouring errors. Burdekin 20 described cutting tests using circular paths for accuracy assessment. Bryan 21 developed the first ball bar system for the contouring test. However, in this system, the uncertainty is high due to the friction between the master balls and the magnetic sockets and no accurate contouring radius was given. Knapps system 22,23 used a circular comparison standard disc mounted on the test table of the machine tool and a 2D-probe. The problems for this system are the existence of friction between the 2D probe and the disc, its small bandwidth, which causes the system to be unusable for high-speed contouring tests, and the high cost of the 2D probe. Kakinov 2427 provided a series of methods using a ball bar system to calibrate a coordinate measuring machine and CNC machine tools. Knapp 28,29 described a rule to reduce the errors due to stickslip etc. Burdekin and Park 30 modified the original ball bar system by employing a four-rod linkage. Burdekin and Jywe 31 provided a method to diagnose the contouring error and to adjust the parameters of the CNC controller to optimise the performance of the tested CNC machine tool. Ziegert and Mize 32 described a laser ball bar system. All these ball bar systems, including the lateral Renishaw system 33 provide only the radius error during the contouring test. This limits the analysis of contouring error since no individual error in each axis is available. Jywe 34 used two position silicon detectors (PSD) for a contouring test to obtain the contouring error in each axis. One laser source emits a laser beam and the laser beam is split into two vertical lines and projected onto two positioning silicon detectors, which are set vertically to each other on the test machine table. The Heidenhein 35 grid encoder also provides a 2D contouring test, but at very high cost. A planar encoder system was developed 36 for applications such as semiconductor and electronics manufacturing equipment. The system, which has a good dynamic response, can provide up to a 0.1 m resolution in positioning, and it is of importance that it is of low cost. However, the original planar encoder was designed for manual operation. It is not suitable for the contouring test of CNC machine tools due to the following considerations:1. The original system only included an encoder and a reading head. No related interface and driver are available.2. Thus there were no related contouring software and testing methods. Thus, in this paper a new computer-aided planar encoder system has been employed and integrated, with the related software, for checking the both the dynamic performance and the geometric error of a CNC machine tool. It is of importance that 90% of the cost of the contouring testing device can be reduced compared to the equivalent Heidenhein grid encoder system. From the previous research, it has been found that the device for the circular test is not always suitable for a 3D geometric error test. Furthermore, these devices are not suitable for a free-form 2D contouring test. In this paper a simple measuring device is designed and developed to check contouring performance with a single axis output. The application for a 3D positioning test is also developed.2. The 2D Planar Encoder Contouring Measuring System for CNC Machine Tools2.1 Principle of the Planar EncoderA planar encoder system, such as the Renishaw RGX grid plate, has been developed for applications such as semiconductor and electronics manufacturing equipment. The system uses a reading head with two orthogonal sensors that read a checkered grid in both the X and Y directions simultaneously. The system has a good dynamic response and can provide up to 0.1 mresolution in positioning. The software in V-Basic is edited to carry out the measuring procedure.Figure 1 shows the arrangement of the contouring test using the simple planar encoder. This planar encoder provides positioning information in each axis for 2D contouring. During the test, the planar encoder is set on the CNC machine tool, and the reading head is fixed in the spindle. The computer software can read the sampling data via a counter card.3. Uncertainty of the Measuring System3.1 Uncertainty Due to Sampling ProcedureThe developed software incorporated the following factors:1. Sampling must be uniform around the profile and reasonablyindependent of the type and speed of the computer. A Planar Encoder Measuring System for CNC Machine Tools 212. Sufficient sampling data is required to display and analyse the error at high resolution.3. Sampling data should be independent of contouring speed, computer speed and contouring radius.3.2 Uncertainty Due to Thermal EffectConsidering the thermal effect of the system for the tests, if the temperature in the planar encoder is different from that of the machine tool table, the radius error will be affected. If the temperature of the planar encoder itself is not uniform, the out of roundness error will be affected. Although the thermal expansion coefficient of the planar encoder is rather small, to minimise the effects, the encoder should be put on the test machine table for some time to reduce the difference in the temperatures and to let the temperatures of the encoder stabilise.4. Test Results of a Circular Contouring PathA simple contouring test is carried out on the XY-plane of a vertical CNC machine tool with a 0M Fanuc controller. The contouring result is shown in Fig. 2. The anticlockwise and clockwise contouring tests at 20 mm radius can meet ISO 230-1 and 230-2 requirements. From the results, the absolute radius error can be found easily. For general contouring systems, only the out of roundness is given. Furthermore, the error for each axis can also be found individually if necessary. This is useful for analytical purposes.5. Thermal DriftThis contouring system provides a non-contacting contouring test. For general contouring systems such as a ball bar system, only a limited number of runs are executed, due to the problem of winding of the signal cable. In this application, the test run is unlimited. Thus, a thermal drift test can be carried out easily without additional fixtures. For eight-hour continuous clockwise contouring runs, contouring results are shown in Fig. 3 for each two-hour period. The contouring centre for each 30 minutes, is plotted in Fig. 4. The contouring centre drift is significant in the 8 hours. It is important that not only the contouring centre drift is given but also the contouring error form in each run can be obtained. From this test, the performance of continuous runscan be monitored easily by this system.Fig. 1. The optical measuring system for contouring performance test on a CNC machine tool.Fig. 2. The clockwise and anticlockwise contouring test results withFig. 3. The thermo drift test results during 8 hours continuous the planar encoder measuring system. Fig4.The thermal drift test results presented by the drift of the contouring centres.Fig. 5. The squareness test result on a CNC machine tool with theplanar encoder measuring system.6. Squareness Error Test by Planar EncoderThe squareness error can be tested easily with the planar encoder. Let the encoder be set on the tested plane. The reading head goes along the square of the encoder. A CNC machine tool was tested and the result is shown in Fig. 5. contouring test.7. Laser Diode and Quadrant Sensor Contouring System 37*Using a laser diode and a quadrant sensor contouring system, the planar encoder contouring system can be verified. Using a 2 mm clockwise contouring radius, Fig. 6 shows the contouringresult using the quadrant sensor, while Fig. 7 gives similar results.Fig. 6. The contouring test results for square path with the laser diode and quadrant sensor contouring system 37.*Fig. 7. The contouring results for a square path with the planar encoder.Fig. 8. The test result for a combination of various geometric shapes provided by the planar encoder measuring system.Fig. 9. The geometric shape of a specified 2D cam.Fig. 10. The test results of the path of the CNC machine tool with/without cutter radius compensation.Fig. 11. The test results with self-calculated cutter radius compensation under different feed rates.Fig. 12. The structure of a 3D positioning measuring device.without sensors, is connected to the spindle of the tested CNC machine tool and to the reading head by two individual balls and magnetic sockets. The centre of the ball on the ball bar on the side of the spindle is the 3D measuring target to be analysed. When the target is reached, the first sample from the planar encoder is then taken at its first position. Without moving the target, the planar encoder is moved to a neighbouring point and a second sample is taken. Finally, the otherneighbouring point is sampled as the third sample. Each of the three samples includes 2D coordinates, the 3D coordinates of the target which can be analysed. Thus each 3D movementwill be obtained by this 1-point and 3-step (1P3S) method. This method can be described as follows. To obtain the 3D positioning coordinates X, Y and Z, a simple model is developed in Fig. 13,where:Fig. 13. The model for analysing coordinates of x, y, z.x, y, z are the coordinates to be analysed.x1, y1, z1, x2, y2, z2, x3, y3, z3 are the coordinates provided bythe 2D optical scale in the first, second and third step samples.L1, L2, L3 are the lengths provided by the ball bar. Then,Solving the equation,whereHere, two possible solutions can be found. One is on the top of the planar encoder, while the other is below it. Thus, in this application only the coordinates on the top of the ball plate are used. After the coordinate z is found, x and y can also be found. In this application, the ball bar length is fixed, thus L1 L2 L3. To extend the working range a standard or laser ball bar system with a long working range displacement sensor can be employed. In that case, L1, L2, L3 can be obtained by that sensor. To minimise the cost, in this application only one set of planar encoders and a simple ball bar are considered. Thus, A Planar Encoder Measuring System for CNC Machine Tools 27 the coordinates x1, y1, z1, x2, y2, z2, x3, y3, z3 have to be obtained by the planar encoder in three individual samples.The sampling procedure (1P3S) is:1. Let the machine tool move to the tested position (one point).2. Take the sample by the planar encoder (step 1).3. Move the reading head to a neighbouring position related to the planar encoder; the tested machine is not moved. Take the sample by the planar encoder (step 2).4. Move the reading head to the next neighbouring position, the tested machine is not moved. Take the sample by the planar encoder (step 3). z1, z2, z3 are affected by the flatness (Zij) of the linearXY stage. The flatness of the linear XY stage Zij is equal to the ith gridon the X-axis and the jth grid on the Y-axis.11. Discussion and ConclusionsIn this paper, a planar encoder system was employed for a contouring test of a CNC machine tool. It was proved that this system could be employed successfully for the contouring test. The advantages of this application can be summarisedas follows:1. During the contouring test, the contouring error for each individual axis can be obtained. This is not possible using a general ball bar system. This function provides more useful information for analysing the contouring error. 2. The system can be employed for a long-period thermal drift test, but the traditional ball bar systems cannot, because in this there is no cable which can be wound up.2. For contouring a combination of complicated curves such as a cam, the system can be employed while a general ball bar system cannot. Table 1. The verification result of the planar encoder for 3D positioningWith this 2D optical measuring system, the 3D positioning error test can also be performed successfully. Thus this optical encoder can be employed for both dynamic performance and geometric error tests on CNC machine tools. Acknowledgements The work was supported by National Science Council, Taiwan, Republic of China, Grant Number NSC-88-2212-E-150-006.References1. G. Schlesinger, Inspection Test on Machine Tools, MachineryPublishing Co. Ltd, London, 1932.2. J. Tlusty, System and methods for testing machine tools,Microtechnic, 13, p.162, 1959.3. J. Tlusty and F. Koenigsberger, Specifications and Tests of MetalCutting Machine Tools, UMIST, Manchester, 1970.4. G. Schlesinger, F. Koenigsberger and M. Burdekin, TestingMachine Tools, 8th edn, Machinery Publishing Co. Ltd,London, 1978.5. 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