自动化立体仓库链式输送机设计【7张CAD图纸和文档所见所得】【SJ系列】
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毕业设计(论文)外文文献翻译题目对输送机用于食品输送系统的调查设计和制造专 业 名 称 机械设计制造及其自动化班 级 学 号 078105301学 生 姓 名 吕途指 导 教 师 于斐填 表 日 期 2011 年 04 月 09 日对输送机用于食品输送系统的调查设计和制造S.H. Masood B. Abbas E. Shayan A. Kara收稿日期:2003年3月29日/接受日期:2003年6月21日/线上发表于:2004年6月23日施普林格出版社伦敦有限公司2004摘要:本文介绍食品饮料行业的研究调查结果和进行开发的方法技术,在设计制造和使用的系统装配机械输送中缩短时间和成本。该输送机部件在设计和生产材料的基础上改进技术来最小化零部件和成本,利用装配设计和制造的设计规则。最终获得一个测试验证了改良技术的传送系统。相比传统的方法整体材料成本下降了19,整体组装成本降低20。关键词:装配 降低成本 设计 DFA DFM 机械输送机1引言 食品和饮料业中使用的输送系统是高度自动化定制结构部件组成的,并进行线路设计的产品,如食品箱,饮料瓶,罐快速组装生产。大部分饮料食品的加工包装涉及到组装业务持续经营情况,瓶或罐需移动或控制的速度。它们的移动需要高效率和可靠的机械输送机,从哪个范围的类型到地板镶嵌链子、路辗或者皮带传动的输送机系统的类型。 近年来,巨大的机械压力输送系统向客户提供低成本而高效率的输送机,制造商倾向审查其目前的设计和装配方法,看看另一种制造手段,可靠的输送机为他们的客户提供更经济的生产。目前,大多数材料处理设备,包括硬件和软件,成本高,安装和维护不灵活1。输送机是固定的地点和传送带有条件地根据自身的同步速度,使得任何输送系统非常困难和昂贵。在今天彻底变化的工业市场,有需要实施新的制造策略,新系统业务概念和新的系统控制软件和硬件开发的概念,即可以应用于材料设计的,灵活的新一代开放处理系统2。侯和峦琪两人提出了一种新的模块化和可重构的二维和三维输送系统,该系统包括一个开放的可重构软件体系结构的基础上的CIM - OSA的(开放系统)模型。据指出,在饮料行业研究领域的改善输送系统中使用的是非常有限的。大多数已发表的研究是针对提高系统的运行输送机一体化系统和高度复杂的软件和硬件。 本文提出的研究调查是旨在改善目前的技术和实践中使用的设计,制造和装配式链式输送机驱动机械,以降低制造所需的时间和输送成本等。部分应用并行工程的概念和几个重要的输送机制造的设计原则和设计组装4,5,为它们的功能进行了研究。材料的适用性,强度准则,成本和装配用于在整个运输系统。关键部件进行了修改和重新设计新的形状和几何形状,材料和一些新的。改进后的设计方法和部分新功能进行了核实。输送机上测试新的考验输送系统设计,制造和组装使用新的改进的部分。2 制造和装配的设计(DFMA) 近年来,研究关于在图纸面积上和设计制造,已成为非常有用的方法,为了产业,必须考虑改善其设施和制造业。然而,没有足够的相关工作做了特别的研究,输送配件的设计在方法问题上越来越多的传统的数据处理和重新绘制的工程设计输送机的基础。大量的论文已发表有相关的问题进行调查DFMA和应用各种方法,以实现经济的结果,证明,有效率和有效的公司根据成本调查的。DFMA知识的主要分类,可确定为:(1)一般准则,(2)公司特定的最佳实践(3)具体过程和或资源的困难。其中设计人员应该知道,一般准则是指普遍适用的规则的,涉及到制造业领域。下面已经编制准则对于DFM的清单 6.l 设计最低数量的零件l 开发一个模块化设计l 尽量减少部件的变化l 设计部件是多功能l 为多用途设计零件l 为简化设计,零件制造l 避免单独紧固件l 最大化遵守:为简化设计,装配l 尽量减少处理:处理演示设计l 评估装配方法l 消除调整l 避免弹性元件:他们是难以操作l 已知部分功能的使用l 允许零件的最大的不容忍现象l 使用已知的和经过验证的厂商和供应商l 在强制降级的值使用部分无边际过度紧张l 尽量减少部件l 着中标准化l 使用最简单的操作l 已知使用行动能力l 尽量减少设置和干预l 分批承接的工程变更这些设计准则应被看作是最优的“建议”。他们通常会导致高品质,低成本的设计和制造。有时必须作出妥协,当然。在这种情况下,如果一个准则替代违背了市场营销或性能要求,下一个最好应选择7。公司具体的最佳实践是指在内部设计规则。公司的开发,通常在一个较长时期,而设计者将坚持自己的信念。这些设计规则,确定由该公司为促进特定工艺和设计决定,以全面提高质量和效益之间的关系通过承认。公司使用的培训等指导方针的一部分给予设计师或维修产品的手工装配需要相当数量的。注意这些方法大部分是定量善于要么被快速方便地启动或更加正式和。例如,准则由Boothroyd和杜赫斯特8 DFA的就被视为是定量化,系统化。鉴于DFM指导方针,这仅仅是从经验丰富的专业经验法则推导,更不正式的定性和9。 Fig. 1. Layout of conveyor systemfor labelling plasic bottles3 传统的输送系统的设计系统的设计和制造输送机是一个非常复杂和耗时的过程。由于每种输送系统是一种特制的产品,每个项目都有各个不同的项目规模,产品和布局。该产品系统的设计是根据客户的要求和明确说明.此外,系统布局应适应公司提供的空间。在修订过程中的输送系统的设计布局,可以采取包括从几天到几个月,或在某些情况下的几年。一个适宜的最低成本和最大限度满足客户的要求是最有可能得到批准。图1显示了一条生产线,示意图中是一个典型的输送系统中安装使用的塑料瓶的标签。输送系统的不同部分被确定具体的技术名称,它通常用在类似的工业应用。该“singlizer”一节使产品形成一个小巷里从多个。在“减速表”降低产品的速度,一旦退出从填料,贴标机等的“流量”部分用于处理与保持高速,例如,填料,贴标机等的“转移表”转移的方向,产品流通。各节的目的,因此,这些不同的输送机控制加工机产品流经不同。 一个典型的机械输送系统应用用于食品和饮料包含超过200机械及零件根据系统的大小。体系中的一些共同输送的重要组成部分,但可以统一的,积累到家庭侧架,间隔棒,端板,盖板,弯板内,外弯板,弯轨和轴(驱动器,尾部和奴隶)。零件的大小和数量,这些根据所输送机的长度和数量节轨道相应的宽度和链类型的需要。存在的问题和缺点在目前的设计,制造和装配输送机械是多方面的,但包括:l 对一些部件的设计l 一些部件成本高l 在装配的/维修时间长l 使用非标件4 区改善 为了确定该地区的主要输送机零件。进行成本分析,降低材料的成本和一切劳动,以估计这种百分比在相对于总成本的所有各部分的成本。分析这样做的目的是找出关键部件,主要负责零部件的成本增加了输送机等调查手段,从而为降低成本。表1显示了输送系统的成本分析50节。分析结果显示,12件在15个构成79的成本降低总材料成本的,在输送系统进一步改进设计是可能的。在这些,确定了7个部分,如表1星号的关键部分一(表现出)构成的最大数量的元件数量和成本,包括材料71以上的整体。其中,三个组成部分(腿组,侧架和支持渠道)被发现50的费用占了总输送材料。其中一名12件详细分析每进行审议大会的各项原则并行设计工程,设计和制造,以及一个新的改进设计,开发的每一个案件10。组件的主要设计改进的细节部分选定如下。5 重新设计一套装配小腿 在输送系统中,安装在腿的侧架,是以保持整个输送系统离地。现有输送工作设计的腿费用昂贵。他们有关于稳定方面的问题,并导致交货延误研究。该延迟时间通常是由一些对供应商的零部件来自海外尚未到位。在输送中双腿所需最关键的规格是:l 输送带负荷强度足够l 稳固l 易于组装l 好的灵活性(调整高度) 图2表示输送站所有设计的零件现有的。这表明数字是一部分腿数字表2中描述,这也显示了一套完整的分类,以组建一个完整的成本分析与所需时间的劳动。现行体制包括塑料腿腿从海外订购括号,不锈钢管腿,这是图切割成指定大小,腿管塑料调整,这是在管腿夹到底部,如图所示。 2。片,这是大小切成正方形,钻孔和焊接管的腿交叉角螺栓支撑板,以支持和后盾腿支架螺栓。 2表中反映出的零件数目的每个部件和组件的数量是设计消费的腿在每一部分。对于许多客户通过几年常见的投诉举报公司已经改进使用了这种设计,但其中一个是腿部的不稳定。从初步调查后,很明显,该图连接之间的不锈钢管和塑料脚支架(第一部分和第三部分。二)未严格不够。这些部件的连接的只是一个6毫米的螺栓。有时,当输送系统进行完整的产品负载,有人指出,在输送的腿,造成不稳定的机械振动。一个主要的原因,这是由于在3月底单螺栓连接各表耳部分和第7部分。该输送机被认为是稳定的关键问题,并要求立即整改,以满足客户的期望。考虑到设计问题,对现有客户喜好的输送腿,开发一输送腿的新设计。一般来说,稳定和腿部力量的被视为点通车的主要标准,在新设计的改进建议,但其他的考虑是最小化的设计简洁,集会在海外部分缓解。图3显示了,腿装配新设计的输送的,而附表三则显示的说明和各部分的成本。 Fig. 2. Existing leg design assembly with part names shown in Table 1Fig. 3. New design for leg assembly with partnames in Table 3图3显示,新设计腿只包含5至8个输送机的主要部件。在旧的设计,塑料腿支架,腿管塑料管的调整和腿是最昂贵的项目向大会占72的腿部的成本。在新的设计方案,这些地方已经取代不锈钢的角度和新的塑料腿调整减少了近50,装配成本的腿。因此,在小腿部分的总数已经减少19至15日,每站的总安装成本降低了55美元的新设计。新的输送站的设计,测试时,发现更安全和稳定的设计,比旧的。 1消除零件编号和5岁的输送机设计,使新的设计更稳定和僵化。此外,设计宽度交叉支撑,也增加了两个螺栓安装,而不是老一英寸这提供了整个输送站安装额外的力量。6 重新设计的侧架 侧架是输送系统的主要部件,提供输送机和几乎所有的安装部分。侧架也将有一个刚性的力量,提供支持所有的负载进行输送。它也容纳输送配件为大会所有关联的。侧架设计的关键考虑因素是:l 侧架(深度尺寸)l 强度的材料l 易于装配l 易于制造图4显示了侧架尺寸和参数。侧架设计用于现有似乎是合理的深度的大小(尺寸图的H。4)。从最初的调查,发现该图之间的间隔距离,并返回轴杆洞(尺寸的G和F。四)可以减少,因为有一些不必要的两个组成部分之间的差距。重要的一点,检查前重新设计参数,以确保将那些经过两个紧密,返回连锁店将赶不上间隔栏,而输送机运行。设计模型是新的侧架民航处开出,以确保所有的规格是健全和部分放置在适合的位置,以检查和许可。使用框架的设计原理设计制造了新的一面对称,使其适用于所有类型的侧架。这一变化预计将减少边尺寸链框架的各种规模的显着。Fig. 4. Side frame dimensions表4显示了一个比较旧的设计尺寸和新设计的侧架为同一链条的类型。据指出,总体规模(深度输送机)的生产已经减少),从而使储蓄42毫米不锈钢侧面由199二百四十一毫米每到毫米(尺寸H牌照的时间表。因此,从不锈钢板1500 3000毫米,旧设计参数只允许6个3米长的侧架,但与新的设计参数现在有可能产生同样的纸张尺寸7侧架的3米长的。该材料使用量的帧侧也进行了审查作进一步调查。据估计,约有55的输送系统的总费用是花在材料。目前框架材料用于一边是2.5毫米厚的不锈钢食品级304。目前,有一个选择,因为其他材料认为可以在市场上与其他被厚度可能。为此,一挠度进行了分析估计,如果有任何其他类型的合适的材料,以取代现有的材料,以便它不会失败的强度准则。6.1 侧架挠度分析 图5显示确定偏转新框架方面的条件不同载荷下的X和Y方向的实验装置通过。使用新的设计参数的框架集制造,被调查方侧架的偏转上1.6毫米厚的不锈钢。阿方条架螺栓与垫片是酒吧和回报轴实验测试与组装的。为偏转的结果,得到了运用液压机上的可变负载侧架条通过。如图所示。 5,挠度测量仪是垂直放置(Y)和水平(X)轴来衡量任何阅读观察到侧框。上应用的负载侧架通过向下方向液压机英寸的侧架是站在支持由同一位置的腿架安装在一边。三个实验组进行的是四,六,八节轨道输送机,观察大负荷下的任何异常。在加载应用在实验输送部分超过估计,并在实际应用更高的系统比实际输送负荷条件。该输送机通常设计行业负荷下进行,每1吨米饮料工业应用在食品和。应用负载的目的是要估计的大框架下高负荷点挠度侧。图6和图7显示,分别是6首曲目结果4轨迹和实验用于传送路段。 Fig. 5. Experimental set up to investigate deflection on new side frame design Fig. 6. Deflection results for 4-track 1.6 mm stainless steel side frame Fig. 7. Deflection results for 6-track 1.6 mm stainless steel side frame从取得的成果,它是根据观察到的2载荷千牛,挠度值在2毫米的几乎所有类型的路段。在给定的情况下,1.6毫米不锈钢侧架的设计可以是一个可能替代现有的输送机侧架设计。据预计,随着更广泛的输送机部分,侧架的变形将保持在允许的范围内,即 5毫米。主要的原因是进行这项实验,以确保不扣侧架在高负荷。因此,没有任何证据节输送屈曲发生的任何类型的使用。还预计,基于工程师的经验和调查研究在当前,组装完成后作出的,怀孕的传送带将额外的力量,这将进一步减少帧的可能性偏转侧面。偏转,例如,测量每向外一套实验。随着腿架安装在一边,将采取行动的力量在相反方向,将推动侧架向内。在这个假设完全观察时,可以断定是一个完整的测试输送机制造和测试基于新的设计参数。与所有的实验获得的结果,这一结果表明,1.6毫米不锈钢侧架304级,可用于工业生产的饮料和食品输送机下加载指定的指导方针。节省的费用在这方面预计将系统重要,因为80用在输送材料是钢由不锈钢。该材料审查和挠度的分析表明,现有的2.5毫米的不锈钢板输送机的应用是一个对设计的侧架的饮料食品和。分析还表明,1.6毫米厚的不锈钢板可以得到圆满作为其功能的替代材料的侧架,其中表演节目。表5显示了比较旧的成本和37(新设计的侧架,这表明储蓄是每侧架新设计预计将达即节省了50.1)。除了这个节省成本,减少了尺寸侧架的241毫米至一百九十九毫米还将允许侧架生产出来的一个额外的3000 1500毫米不锈钢薄板。新的设计也进行了改进,在其他一些关键部件和组装等支持渠道,返回辊轴,间隔棒,支持穿带及支持方穿带,这导致进一步的节省成本和劳动力,也容易制造。例如,装带新设计的支持渠道大会的支持(包括穿带及侧)需要减少进程数,减少成本的渠道和提供使用不同类型的链节给予穿厚度带钢新的M 1,使用节省33.7这一改进设计。新设计的辊轴的回报提供了44.5,节约成本和劳动时间减少50。新设计的间隔栏所提供的估计有25的成本节约从旧设计。 7 设计实施测试输送系统 该部分的执行部件和设计改进的关键是进行个别设计出的,制造和系统组装一个正式的测试输送。这种新的和改进的输送机进行了测试检验和)验证瓶(塑料的性能与实际产品。还有一个成本分析的基础上进行比较旧的设计一致的整体输送成本与所涉及的成本节约与输送机在这个测试中7。新的测试传送带是一个singleiser类型(图8),包括长度为5米,总三个不同章节C1是第6条轨道输送第C2的加入,这是一个6通道90弯曲输送机。这是第C3连接到输送,这是两种不同类型的连锁8轨与组合输送部分,制表和STR。测试输送机共载有26个主要部分。图9显示了用于测试输送流量测试产品在合作公司。部件的性能和效率的新的测试新的输送机及其关键的顺利进行了测试,静音表现观察输送带产品流于空饮料瓶塑料。所有的部件和输送系统,发现显示的全功能令人满意的表现。一个完整的测试传送带上进行成本分析,以衡量亦有差异新旧设计和评估开支减轻装配劳动和减少英寸部件数量,使用的材料和制造成本分别计算出各部分储蓄率和各部分和整体系统进行了测定。Fig. 8. A singliser test conveyorFig. 9. Test conveyor assembly: product flow test8 结果和讨论 该地区输送系统最重要的考虑是,以检查是否设置了新的支持渠道和滴水托盘加入进行了以较少的劳动消耗。还注意确保劳动者一直有效履行职责的。输送系统组装的时代用于预计的因素取决于工人的情绪及其他外部。但已作出努力,以达到最接近可能的时间来制造输送机。 一个成本分析研究揭示了以下事实:l 对八个部分进行设计的共12个改善,取得了更多地节约40的制造成本。其他1的三个部分取得了节省26至34成本。l 在昂贵费用的部分,最大范围内实现一方节余,返回辊轴,腿穿带设置和支持。l 该输送机的总成本减少了19。l 该输送机整体劳动成本在大大减少了20。 据观察所得,储蓄的主要目的是取得在传动机零件中没有被专业设计的零件。系统的传送带上的一个重大变化是会影响侧架的设计参数,这也影响到其他部分的变化。其次,开发新渠道的M带沿剖面的支持与标准磨损增加新的重大成就输送机设计。设计完成的新的降低了劳动成本,也取得了重大的影响和改进设计制造装配线上的。与会者还注意到,通过分类数设计了不同的间隔条轨道改进了选拔程序。新的传送系统变得更经济,成本效益以及需要使用额外的强度材料被淘汰。9 结论 在设计和制造机械输送系统中,相当缺乏输送机优化设计的一个研究工作,特别是缺乏一个将现代化的技术应用到这种系统的设计改进研究中。为了提高测试的成本和交货时间,对输送机输送系统进行完整的故障分析和评估,在输送机制造业中举办评估高消费区域。分析应用系统支持的功能和运作原则,在不牺牲系统的功能和操作上改进面向装配的设计。一种在新的输送机设计基础上提出了所有建议使用的修改。和公司通过合作对这些建议进行了验证测试。结果证明是成功的达到了整体成本的19和节省降低20总劳动成本。研究结果证实,通过应用DFMA的规则,一个复杂系统的设计和装配输送食品机械的成本可大大减少。参考文献1. Anderasen MM, Ahm T (1986) Flexible assembly system. Springer,Berlin Heidelberg New York2. Ho JKL, Ranky PG (1994) The design and operation control of a reconfigurable flexible material handling. Proceedings of 1994 Japan-USA Symposium of Flexible Automation, vol. 2, Kobe, Japan, pp 8258283. Ho JKL, Ranky PG (1997) Object oriented modelling and design of reconfigurable conveyors in flexible assembly systems. Int J Comput Integr Manuf 10(5):3603794. Kusiak A (1990) Intelligent manufacturing systems. Prentice Hall, New York5. Corbett J, Dooner M, Meleka J, Pym C (1991) Design for manufacturing: strategies principles and techniques. Addison-Wesley, UK6. Mize JH, Glenn P (1989) Some fundamentals of integrated manufacturing. International Industrial Engineering Conference Proceedings, Washington, DC, pp 5465517. Mize JH (1987) CIMa perspective for the future of IEs. IIE Integrated Systems Conference Proceedings, Nashville, TN, pp 358. Boothroyd G, Dewhurst P (1988) Product design for manufacturing and assembly. Manuf Eng April:42469. Bedworth DD, Henderson MR, Wolfe PM (1991) Computer integrated design and manufacturing. McGraw-Hill, Singapore10. Abbas B (2001) An investigation into design and manufacturing of mechanical systems for food processing and beverage industry. Dissertation, Swinburne University of Technology, Hawthorn, Australia16Int J Adv Manuf Technol (2005) 25: 551559DOI 10.1007/s00170-003-1843-3ORIGINAL ARTICLES.H. Masood B. Abbas E. Shayan A. KaraAn investigation into design and manufacturing of mechanical conveyors systemsfor food processingReceived: 29 March 2003 / Accepted: 21 June 2003 / Published online: 23 June 2004 Springer-Verlag London Limited 2004Abstract This paper presents the results of a research investi-gation undertaken to develop methodologies and techniques thatwill reduce the cost and time of the design, manufacturing andassembly of mechanical conveyor systems used in the food andbeverage industry. The improved methodology for design andproduction of conveyor components is based on the minimisa-tion of materials, parts and costs, using the rules of design formanufacture and design for assembly. Results obtained on a testconveyor system verify the benets of using the improved tech-niques. The overall material cost was reduced by 19% and theoverall assembly cost was reduced by 20% compared to conven-tional methods.Keywords Assembly Cost reduction Design DFA DFM Mechanical conveyor1 IntroductionConveyor systems used in the food and beverage industry arehighly automated custom made structures consisting of a largenumber of parts and designed to carry products such as foodcartons, drink bottles and cans in fast production and assemblylines. Most of the processing and packaging of food and drink in-volve continuous operations where cartons, bottles or cans are re-quired to move at a controlled speed for lling or assembly oper-ations. Their operations require highly efcient and reliable me-chanical conveyors, which range from overhead types to oor-mounted types of chain, roller or belt driven conveyor systems.In recent years, immense pressure from clients for low costbut efcient mechanical conveyor systems has pushed con-veyor manufacturers to review their current design and assemblymethods and look at an alternative means to manufacture moreeconomical and reliable conveyors for their clients. At present,S.H. Masood (u) B. Abbas E. Shayan A. KaraIndustrial Research Institute Swinburne,Swinburne University of Technology,Hawthorn, Melbourne 3122, AustraliaE-mail: smasoodswin.edu.aumost material handling devices, both hardware and software, arehighly specialised, inexible and costly to congure, install andmaintain 1. Conveyors are xed in terms of their locations andthe conveyor belts according to their synchronised speeds, mak-ing any changeover of the conveyor system very difcult and ex-pensive. In todays radically changing industrial markets, there isa need to implement a new manufacturing strategy, a new systemoperational concept and a new system control software and hard-ware development concept, that can be applied to the design ofa new generation of open, exible material handling systems 2.Ho and Ranky 3 proposed a new modular and recongurable2D and 3D conveyor system, which encompasses an open re-congurable software architecture based on the CIM-OSA (opensystem architecture) model. It is noted that the research in thearea of improvement of conveyor systems used in beverage in-dustry is very limited. Most of the published research is directedtowards improving the operations of conveyor systems and inte-gration of system to highly sophisticated software and hardware.This paper presents a research investigation aimed at im-proving the current techniques and practices used in the de-sign, manufacturing and assembly of oor mounted type chaindriven mechanical conveyors in order to reduce the manufactur-ing lead time and cost for such conveyors. Applying the con-cept of concurrent engineering and the principles of design formanufacturing and design for assembly 4, 5, several criticalconveyor parts were investigated for their functionality, materialsuitability, strength criterion, cost and ease of assembly in theoverall conveyor system. The critical parts were modied andredesigned with new shape and geometry, and some with newmaterials. The improved design methods and the functionality ofnew conveyor parts were veried and tested on a new test con-veyor system designed, manufactured and assembled using thenew improved parts.2 Design for manufacturing and assembly (DFMA)In recent years, research in the area of design for manufacturingand assembly has become very useful for industries that are con-552sidering improving their facilities and manufacturing methodol-ogy. However, there has not been enough work done in the areaof design for conveyor components, especially related to the is-sue of increasing numbers of drawing data and re-engineeringof the process of conveyor design based on traditional methods.Emphasise standardisationUse the simplest possible operationsUse operations of known capabilityMinimise setups and interventionsUndertake engineering changes in batchesA vast amount of papers have been published that have investi-gated issues related to DFMA and applied to various methodolo-gies to achieve results that proved economical, efcient and costeffective for the companies under investigation.The main classications of DFMA knowledge can be iden-tied as (1) General guidelines, (2) Company-specic best prac-tice or (3) Process and or resource-specic constraints. Generalguidelines refer to generally applicable rules-of-thumb, relat-ing to a manufacturing domain of which the designer shouldbe aware. The following list has been compiled for DFMguidelines 6.These design guidelines should be thought of as “optimalsuggestions”. They typically will result in a high-quality, low-cost, and manufacturable design. Occasionally compromisesmust be made, of course. In these cases, if a guideline goesagainst a marketing or performance requirement, the next bestalternative should be selected 7.Company-specic best practice refers to the in-house designrules a company develops, usually over a long period of time, andwhich the designer is expected to adhere to. These design rulesare identied by the company as contributing to improved qualityand efciency by recognising the overall relationships betweenDesign for a minimum number of partsDevelop a modular designMinimise part variationsDesign parts to be multifunctionalDesign parts for multiuseDesign parts for ease of fabricationAvoid separate fastenersMaximise compliance: design for ease of assemblyMinimise handling: design for handling presentationEvaluate assembly methodsEliminate adjustmentsAvoid exible components: they are difcult to handleUse parts of known capabilityAllow for maximum intolerance of partsUse known and proven vendors and suppliersUse parts at derated values with no marginal overstressMinimise subassembliesparticular processes and design decisions. Companies use suchguidelines as part of the training given to designers of productsrequiring signicant amounts of manual assembly or mainte-nance. Note that most of the methodologies are good at eitherbeing quick and easy to start or being more formal and quanti-tative. For example, guidelines by Boothroyd and Dewhurst 8on DFA are considered as being quantitative and systematic.Whereas the DFM guidelines, which are merely rules of thumbderived from experienced professionals, are more qualitative andless formal 9.3 Conventional conveyor system designDesign and manufacturing of conveyor systems is a very com-plex and time-consuming process. As every conveyor system isa custom-made product, each project varies from every otherproject in terms of size, product and layout. The system designFig. 1. Layout of conveyor sys-tem for labelling plasic bottles553is based on client requirements and product specications. More-over, the system layout has to t in the space provided by thecompany. The process of designing a layout for a conveyor sys-tem involve revisions and could take from days to months or insome instances years. One with the minimum cost and maximumclient suitability is most likely to get approval.Figure 1 shows a schematic layout of a typical conveyorsystem installed in a production line used for labelling ofplastic bottles. Different sections of the conveyor system areidentied by specic technical names, which are commonlyused in similar industrial application. The “singlizer” sec-tion enables the product to form into one lane from multiplelanes. The “slowdown table” reduces the speed of productonce it exits from ller, labeller, etc. The “mass ow” sec-tion is used to keep up with high-speed process, e.g., ller,labeller, etc. The “transfer table” transfers the direction of prod-uct ow. The purpose of these different conveyor sections isthus to control the product ow through different processingmachines.A typical mechanical conveyor system used in food and bev-erage applications consists of over two hundred mechanical andelectrical parts depending on the size of the system. Some ofthe common but essential components that could be standard-ised and accumulated into families of the conveyor system areside frames, spacer bars, end plates, cover plates, inside bendplates, outside bend plates, bend tracks and shafts (drive, tail andslave). The size and quantity of these parts vary according to thelength of conveyor sections and number of tracks correspond-ing to the width and types of chains required. The problems andshortcomings in the current design, manufacturing and assemblyof mechanical conveyors are varied, but include:4 Areas of improvementIn order to identify the areas of cost reduction in material andlabour, a cost analysis of all main conveyor parts was conductedto estimate the percentage of cost of each part in relation to thetotal cost of all such parts. The purpose of this analysis was toidentify the critical parts, which are mainly responsible for in-creasing the cost of the conveyor and thereby investigate meansfor reducing the cost of such parts.Table 1 shows the cost analysis of a 50-section conveyor sys-tem. The analysis reveals that 12 out of 15 parts constitute 79%of the total material cost of the conveyor system, where furtherimprovements in design to reduce the cost is possible. Out ofthese, seven parts were identied as critical parts (shown by anasterisk in Table 1) constituting maximum number of compo-nents in quantity and comprising over 71% of overall materialcost. Among these, three components (leg set, side frame andsupport channel) were found to account for 50% of the totalconveyor material cost. A detailed analysis of each of these 12parts was carried out considering the principles of concurrent en-gineering, design for manufacture and design for assembly, anda new improved design was developed for each case 10. De-tails of design improvement of some selected major componentare presented below.5 Redesign of leg set assemblyIn a conveyor system, the legs are mounted on the side frame tokeep the entire conveyor system off the oor. The existing designof conveyor legs work, but they are costly to manufacture, theyOver design of some partsHigh cost of some componentsLong hours involved in assembly/maintenanceUse of non-standard partshave stability problems, and cause delays in deliveries. The delayis usually caused by some of the parts not arriving from over-seas suppliers on time. The most critical specications requiredfor the conveyor legs are:Table 1. Conveyor critical parts based on parts cost analysisProduct descriptionLeg setSide frameSupport channelBend tracksRt. roller shaftTail shaftSpacer barSupport wear stripSupport side wear stripEnd plateCover plateBend platesTorque arm bracketSlot coverInside bend plateQty68804008139391354001323939818978Material usedPlastic leg + SS tube2.5 mm SSC channel SSPlastic20 dia. SS shaft35 dia. Stainless steel50X50X6 SS40 10 mm plasticPlastic2.5 mm/SS1.6 mm S/S2.5 mm/SS6 mm S/S plateStainless steel2.5 mm/SSCost (%)20.2216.0715.0014.366.706.275.435.363.011.881.571.291.210.970.66Improvement possible (Yes/No)YesYesYesNoYesNoYesYesYesYesNoYesYesYesYesTotalCriticalparts100.00554Strength to carry conveyor loadStabilityEase of assemblyEase of exibility (for adjusting height)1 and part 3 in Fig. 2) was not rigid enough. The connectionsfor these parts are only a single 6 mm bolt. At times, when theconveyor system was carrying full product loads, it was observedthat the conveyor legs were unstable and caused mechanical vi-bration. One of the main reasons for this was due to a single boltFigure 2 indicates all the parts for the existing design ofthe conveyor leg. The indicated numbers are the part numbersdescribed in Table 2, which also shows a breakdown of cost an-alysis complete with the labour time required to assemble a com-plete set of legs. The existing leg setup consists of plastic legbrackets ordered from overseas, stainless steel leg tubes, whichare cut into specied sizes, leg tube plastic adjustments, whichare clipped onto the leg tube at the bottom as shown in Fig. 2.Lugs, which are cut in square sizes, drilled and welded to the legtube to bolt the angle cross bracing and backing plate to supportleg brackets bolts. The # of parts in Table 2 signies the numberof components in each part number and the quantity is the con-sumption of each part in the leg design. Companies have usedthis design for many years but one of the common complaintsreported by the clients was of the instability of legs.From an initial investigation, it became clear that the connec-tion between the stainless steel tube and plastic legs bracket (partFig. 2. Existing leg design assembly with partnames shown in Table 1Table 2. Cost analysis for old leg design assemblyconnection at each end of the lugs in part 3 and part 7. The sta-bility of the conveyor is considered critical matter and requiresrectication immediately to satisfy customer expectations.Considering the problems of the existing conveyor leg de-sign and the clients preferences, a new design for the conveyorleg was developed. Generally the stability and the strength ofthe legs were considered as the primary criteria for improve-ment in the new design proposal but other considerations werethe simplicity of design, minimisation of overseas parts and easeof assembly at the point of commissioning. Figure 3 shows, thenew design of the conveyors leg assembly, and Table 3 gives adescription and the cost of each part.Figure 3 shows that the new design consists of only ve mainparts for the conveyors leg compared to eight main parts in theold design. In the old design, the plastic leg bracket, the legtube plastic adjustment and the leg tube were the most expensiveitems accounting for 72% of the cost of leg assembly. In the newPart no.15, 647238Part descriptionPlastic leg bracketLeg tube plastic adjustmentLugAngle cross bracingBacking plateLeg tubeBolts# of parts2421226Qty2221226Cost$ 30.00$ 28.00$ 4.00$ 5.00$ 4.00$ 25.00$ 3.00SourceOverseasOverseasIn-houseIn-houseIn-houseIn-houseIn-houseTotal assembly cost (welding)$ 15.00In-houseTotal1917$ 114.00555Fig. 3. New design for leg assembly with partnames in Table 3Table 3. Cost analysis for new design leg assemblyPart no.13452Part descriptionStainless steel angle (50 50 3 mm)Leg plastic adjustmentCross brassingBoltsBacking plate# of parts22182Qty22142Cost$ 24.00$ 10.00$ 7.00$ 4.00$ 4.00SourceIn-houseOverseasIn-houseIn-houseIn-houseTotal assembly cost$ 10.00In-houseTotaldesign, those parts have been replaced by a stainless steel angleand a new plastic leg adjustment reducing the cost of leg assem-bly by almost 50%. Thus the total numbers of parts in the leghave been reduced from 19 to 15 and the total cost per leg setup1511Size of side frame (depth)Strength of the materialEase for assemblyEase for manufacturing$ 59.00has been reduced by $ 55 in the new design.The new conveyor leg design, when tested, was found to bemore secure and stable than the old design. The elimination ofpart number 1 and 5 from old conveyor design has made the newdesign more stable and rigid. In addition, the width of the crossbracing has also been increased with two bolts mount instead ofone in old design. This has provided the entire conveyor leg setupan additional strength.6 Redesign of the side framesThe side frame is the primary support of a conveyor systemthat provides physical strength to conveyors and almost all theparts are mounted on it. The side frame is also expected to havea rigid strength to provide support to all the loads carried onthe conveyor. It also accommodates all the associated conveyorcomponents for the assembly. The critical considerations of sideframe design are:Figure 4 shows the side frame dimension and parameters.The side frame used in existing design appears to be of rea-sonable depth in size (dimension H in Fig. 4). From the initialinvestigation, it was found that the distance between spacer barholes and return shaft (dimensions G and F in Fig. 4) could bereduced, as there was some unnecessary gap between those twocomponents. The important point to check before redening thedesign parameters was to make sure that after bringing those twocloser, the return chains would not catch the spacer bar while theconveyor is running. The model of the new side frame design wasdrawn on CAD to ensure all the specications are sound and theparts are placed in the position to check the clearances and thets. Using the principle of design for manufacturing the new sideframe design was made symmetrical so that it applies to all typesof side frames. This change is expected to reduce the size of sideframe signicantly for all sizes of chains.Table 4 shows a comparison of dimensions in the old designand the new design of side frames for the same chain type. It556Fig. 4. Side frame dimensionsTable 4. New and old side frame dimension parametersOld designChain type3.25 LF/SSSTR/LBP/MAGA31B92C71D196E65F105G211H241I136J58K85L196TAB2283621875696202232127New designChain type3.25 LF/SSSTR/LBP/MAG/TABA31B100C73D173E67F107G167H199I92J58K85L152is noted that the overall size (depth) of the conveyor has beenreduced from 241 mm to 199 mm (dimension H), which givesa saving of 42 mm of stainless steel on every side frame manu-factured. Thus, from a stainless steel sheet 1500 3000 mm, theold design parameter
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