面团自动排放机的结构设计【10×10旋转溜管式生面团自动排放机】
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黄河科技学院毕业设计说明书 第 III 页1010旋转溜管式生面团自动排放机摘要:馒头是人们的主食之一,然而中国馒头生产的最大特点却是家庭作坊。馒头生产机械还是停留在手工操作的阶段。这已不再适应现今日趋加快的生活节奏。为解决馒头大规模工业生产的薄弱环节上的问题,采用嵌入式系统开发经验,设计了旋转溜管式馒头坯自动排放机,并进行了智能化改造。本文介绍了此设备的工作原理和主要技术参数。其原理是:将成型好的面团通过远红外传感器1落入旋转溜管,则传感器发信号给控制器,控制器发控制信号使步进电机旋转一定角度,向下一孔落料。面团通过旋转溜管并沿着分配上指定的导向溜管落入托盘,按直线排列成行。当排完第一行后,下一排的第一个面团通过传感器时,控制器附加发出一个控制信号使离合器吸合,而让送进机构带着托盘向前运行,当走一列距时,光电传感器2发信号使离合器段开,此时开始排放下一排。希望此次设计能提供一个食品机械自动化改造的成功实例。关键词:自动排放,自动控制,旋转溜管,面团,排放 Automatic Discharge of 10 10 Rotary Slip Tube Raw Dough Author:Cui Jia LeTutor:Mu Guo HuaAbstractThe bread is one of the staple food of the people, however, the most prominent feature of Chinese steamed bread production is the family workshops. Bread production machinery remain in the stage of manual operations. This is no longer adapted to todays increasingly accelerated pace of life。To solve the problem on the weak link of the large-scale industrial production of bread, embedded systems development experience, design a rotating slip tube bread blanks automatically discharge machine, and intelligent transformation. This article describes the working principle of this device and main technical parameters. The principle is: forming a good dough by far-infrared sensors fall into the rotary slide tube, the sensor signal to the controller, the controller control signals for the stepper motor to rotate a certain angle, down a hole blanking. Dough slide by rotating the tube along the orientation specified in the distribution of slip tube to fall into the tray, arranged in rows by a straight line.When drained, the first line of the next row of the first dough through the sensor, additional controller to send a control signal so that the clutch pull, and sent to institutions run forward with the tray, walk a distance, the photoelectric sensorsignal clutch segment open, then discharged the next row. Hope that this design can provide successful examples of a food machinery automation transformation.Keywords: auto emissions, automatic control, rotating slide tube, dough, emissions目录1、绪论11.1课题背景及目的11.3自动排放机工艺及设备的设计要求21.4自动排放机的设计要求31.5方案论证32、旋转溜管式生面团自动排放机设计52.1旋转溜管式生面团自动排放机基本形式52.2设计参数分析83、机械结构的设计与计算113.1旋转溜管的设计113.2送进机构的设计113.2.1链条的型号及尺寸113.2.2链条附件尺寸K1123.3送进机构链的计算133.3.1链轮转速的分析133.3.2计算功率选取电机133.3.3链轮齿形143.3.4离合器的选取154、传动机构的设计计算174.1链传动特点174.2传动机构计算174.3机架的设计205、轻型输送机的设计22结论23致谢24参考文献25 黄河科技学院毕业设计说明书 第 25 页1绪论1.1 课题背景及目的在中国,我们都是以米和面作为主食的,而馒头是面食中的主要食品。而在北方,更是人们日常离不开的一种面食。在人们的生活中,馒头一直以传统的方式手工加工制作,产量低、能耗多、劳动强度大,产品的质量、营养价值和卫生状况都难尽人意。但在工作节奏和生活节奏日益加快的今天,更多的人们都不自己在家做馒头,而是去超市购买。所以这种家庭手工的制作方式已满足不了人们的需求,机械化的各种面食加工设备如馒头机也就应运而生。在普通百姓眼中手工做馒头是件很简单的事情,但事实上要实现自动化操作,并且大量的生产是件很难的事,要考虑很多的方面。例如,面粉品质对馒头的影响、发酵菌种以及发酵工艺、馒头的柔软度的保持、何种工艺流程适合于工业化生产等问题,在馒头自动化生产中都必须考虑的。随着工业化和社会化的发展,家庭作坊必将也必须被淘汰。食品生产的机械化和工业化的推广以及食品工艺的自动化、智能化都是急需解决的重大问题。在中国,馒头的历史已经有数千年了,但馒头的生产一直停留在家庭生产或作坊式生产的水平,产量较低、劳动强度大、耗能多、产品卫生难以保证。在七十年代中后期,一些西方发达国家如,美国、加拿大等国家发现了我国馒头生产的这个巨大商机,并成立科研小组开始研究我国馒头的生产技术问题,并多次要求与中国进行技术和生意上的合作。八十年代初到九十年代中期,我国也开始重视馒头自动化生产的。在八十年代中期,国家经委、商业部下达“馒头连续化生产线工艺及设备的研究”研究课题。从此我们学校粮食学院就开始组织了有关技术研究人员开始进行馒头工业化的探索。先后试制出了馒头自动生产线和MTX-250型馒头自动生产线,在1986年和1991年通过了国家级的技术鉴定,其生产线自动化程度较高,是我国馒头工业化生产的最初思路。之后也有人提出了很多的方案,但所有类型的生产线都由于设备投资较大,自动控制性能存在缺陷,以及工艺技术的不配套,使自动生产线的推广受到了限制。在中国,馒头不同与西方国家的面包、汉堡、三明志等食品,馒头的利润很低。因此馒头生产的成本不能太高,否则就要亏本为此,科技工作者根据我国馒头市场的实际情况,研究出了组合式馒头工业化生产线,该生产线中,和面、成型由机械完成,醒发和汽蒸在蒸车上进行,采用不锈钢蒸柜为蒸制容器,由锅炉提供蒸汽。馒头从纯手工生产,发展到了半自动化的阶段。面粉是馒头的主要原料,随着我国面粉企业的迅速发展,对我国的粮食机械行业的发展提出了更高的要求,也给我国粮机行业的发展带来了新的机遇和挑战,粮食机械的发展一定要适应面粉企业的发展。这对于我们的馒头全自动生产线的研发更是一种挑战。1.2 本课题的主要研究内容本次毕业设计,我要改变传统的馒头手工加工制作方法,改变手工做法中的加工慢,效率低,等等。使馒头加工连续化、自动化和工业化,不断满足现代社会的需求,同时对于我也是一个重大的挑战,使我重新认识馒头的加工制作。随着社会现代化程度的不断提高,这种改变也是迫在眉睫。目前,馒头的生产工序,从和面、成型、醒发、汽蒸等都在逐步实现机械化。在自动化生产馒头时,通常是利用馒头成型机械制作出馒头胚,再将多个馒头胚摆放整齐然后放入蒸屉中蒸熟。但在实际生产中,由于馒头胚不易通过机器排放整齐,故常见的操作方式为手工排放后再放入蒸屉中。但是,手工排放方式既耗费人工,生产效率又低,且因工人直接用手接触馒头胚而带来了不卫生的隐患,有可能造成疾病的传播。但馒头胚成规模地排放所需的手工成分实在太多,耗时耗力,提高了成本,限制了馒头生产的产量和质量。因此,有必要提供一种专用于馒头的自动排放机。1.3 自动排放机工艺及设备的设计要求排放是馒头生产的关键设备,一是要解决劳动强度大的问题,二是确保产品卫生。三是自动排列准确。针对此次设计的自动排放机,为了能够更好的使馒头的加工更自动化,更便捷,同时更能方便人们的加工使用,所以设计的基本要求是:(1)设计10x10生面团排放机(生面团行距80mm,列距80mm)(2)采用轻型带式输送机。即采用轻型带式输送机将加工制作好的馒头送到排放口,通过排放设备,将馒头摆放成10排,10列,且每排每列的间距都是80mm。所要达到的工艺要求就是垂直落料,直线排出,这样便大大提高的馒头加工的时间,使馒头加工的自动化程度加强。1.4 自动排放机的设计要求 1、设计一台馒头自动排放机,解决以前由人工完成的排放操作,减缓工人的劳动强度,提高劳动生产率。2、自动排放机要求能和每分钟200个馒头以下的各种馒头成型机相配套使用,即排放速度和时间是可调的。3、因为每行只限排放10个馒头,每列限排放10个馒头,且馒头之间的间距均为80mm。4、要求馒头排放位置准确可靠,不存在累积误差。5、设计一个在馒头成型机和排放机之间完成馒头输送的轻型输送带,且能适应于不同的高度的馒头成型机和排放机的要求,即要求输送机的高度是可以无级调节的。6、由于食用和健康方面的要求,所以要求相应设备的卫生清洁,避免污染和生锈。1.5 方案论证对于馒头的排放设计,我经过上网查询,图书馆寻找资料等各种途径了解到各式各样的排放设计。目前馒头自动排放机大概有3种形式,第一种利用皮带传动和托盘运动实现馒头的排放;第二种是推板式生面团自动排放机;第三种是旋转溜管式生面团自动排放机。方案一 利用皮带传动和托盘运动实现馒头的排放该排放设备由皮带传动机构,托盘送给机构,控制系统和机架组成。工作原理:皮带传动机构的主运动是皮带传动,由调速电机驱动辅助运动是皮带末端部的滑块在电机的驱动下,实现皮带出口端作直线问歇运动,输送带在驱动装置作用下朝着一个方向匀速运动,出口端则由一个活动刀口支撑使皮带作伸缩动作,每个面坯在预定的位置落到盘中后,每一个位置上的光电开关都会给控制器发出信号当面坯落到托盘中时,皮带输送机构即完成了第一排10个面坯的摆放之后,托盘前进80 mm后停止,皮带传动机构又重复上面的摆放动作和过程,摆放第二排面坯,如此循环,进行间歇式摆放连续化作业。方案二 旋转推板式自动排放机 将成型后的生面团,由输送带按一定间距输送到排放机上。排放机上部设有一旋转的拨板。拨板的旋转方向与输送带运动方向相垂直,每当输送带上通过一定数量的馒头时,拨板运动一次,将定数量的馒头拨入输送带下设的定位器中,利用馒头的白然落差和出料口的布置,使定数量的馒头按一定间隙整齐地排列在托盘或主输送带上,进入下一道工序。拨板拨下的馒头数量是根据生产线上的产量来设定。为了使拨板动作与输送带速度完全同步,两者必须用一个传动系统来连接【8】。方案三 旋转溜管式自动排放机这种排放机的排放原理是利用馒头的自重,通过一个间歇旋转导向器,将生面坯导入固定的定位装置中,从而实现自动排列动作。该机主要由导向器、固定定位装置和主传动机构三部分构成。当馒头由成型机成型后,通过传送带提升送入导向器的落料口,导向器是会灵活旋转的滚道,一是控制馒头滚动下落,二是准确实现某个角度的转动,确保其出口与定位装置上平面圆周排布的孔相对接。固定的定位装置作用则必是将面坯实现位置转变,达到排放。排列后的面坯落入托盘或输送带上,向前运行进入后一工序【6】。2旋转溜管式生面团自动排放机设计21旋转溜管式生面团自动排放机基本形式本设计是将做好的生面团通过传送带输送到投料口,然后利用馒头本身的自重,通过旋转溜管和导向溜管,使其自动排放到事先放置好的托盘上。然后再通过主输送带将托盘送到下一环节。大体上如图2-1所示:图2-1.溜管式自动排放示意图排放机的设计原理这种排放机的排放原理是利用馒头的自重,通过一个间歇旋转导向器,将生面坯导入固定的定位装置中,从而实现自动排列动作。本次设计的旋转管溜式自动排放机的基本形式,它主要由旋转溜管,分配盘(上面装有10个导向溜管);送进机构(由链轮,链条,电磁离合器,电机,减速器等构成);步进电机,控制器,光电传感器等组成。如图2-2所示:图2-2 旋转溜管式生面团自动排放机的基本形式要实现生面团自动排放成所要求的摆放(1010),需利用旋转溜管和导向溜管,从而使生面团的排放达到预期的要求,这就需要利用步进电机带动旋转溜管的转动。根据需要的摆放(1010),在导向圆盘上设置10个导向溜管的空,使其均匀分布在导向圆盘上,通过步进电机的带动,使生面团通过落料口后按次序的落入的导向溜管内,从而使生面团自动排放到托盘上。因为这种排放设计是利用馒头的自重,所以对生面团经过落料口也必须精心设计,以免生面团都落入到同一导向溜管内,从而达不到设计的要求。所以在落料口处设计一个光电传感器1(如图2-1),每当一个生面团经过传感器1时,便将信号传送给步进电机,使其发生一次动作。同时这也是在导向圆盘这里为什么要选择步进电机的原因,步进电机和普通电动机不同之处是步进电机接受脉冲信号的控制,步进电机和普通电机的区别主要就在于其脉冲驱动的形式,正是这个特点,步进电机可以和现代的数字控制技术相结合。根据本设计的要求,所以采用步进电机和光电传感器配合,更能实现其的自动化控制,以达到设计要求。经过设计分析,该排放机主要可由导向器、固定定位装置和主传动机构三部分构成(如图2-2)。当馒头由成型机成型后,通过传送带提升送入导向器的落料口,导向器是会灵活旋转的滚道,一是控制馒头滚动下落,二是准确实现某个角度的转动,确保其出口与定位装置上平面圆周排布的孔相对接。固定的定位装置作用则必是将面坯实现位置转变,达到排放。排列后的面坯落入托盘或输送带上,向前运行进入后一工序。此外,对托盘上生面团的摆放也需要控制,按照排放要求(1010),生面团之间的行距80mm,列距80mm,这可以通过导向溜管控制。当每一列摆放完10时,这就要求托盘向前行进一个单位的距离,以便下一列的排放,这时就需要采用电磁离合器控制和另外一个光电传感器联合控制,以实现此要求【13】。电磁离合器与别的离合器的最大区别就是电磁离合器靠线圈的通断电来控制离合器的接合与分离。按照此次毕业设计的要求:生面团在托盘排列的行距80 m m、列距80mm。每排10个,即1010的设计。它的工作过程是:将做好的生面团经过提升机的输送带传送到投料口,当生面团经过远红外光电传感器1时,传感器向控制器发出一个脉冲信号,控制器以规定的频率向步进电机发送一组脉冲信号,从而使步进电机带动旋转溜管转36度,从而使生面团通过旋转溜管并沿着分配盘上指定的导向溜管落入托盘。由于导向溜管在出口处排列成直线,且间距为80 mm,那么生面团也将在托盘上排列成直线,以达到设计要求。当第11个生面团通过光电传感器1时,控制器将附加发出一个控制信号,使电磁离合器吸合,以使送进机构带动托盘向前运动,当电磁行走80mm时,光电传感器2发出信号,使电磁电磁离合器断电,松开,送进机构停止运行。此时提升机开始接着向投料口输送生面团,排放第2排生面团【9】。其系统控制简图见图2-3。图2-3 系统控制简图2.2 设计参数分析排放机主要有以下几个技术参数组成:1、旋转溜管;2、生面团下落时间;3、生面团行距。1、旋转溜管:旋转溜管是本机的关键部件,它由步进电机直接带动旋转,每分钟要求它启,停60次,甚至120次,每次要转动固定的角度,每次转动过程要在01 s内,甚至更短的时间完成。这就要求步进电机的技术性能满足这个工作状况。我们采用国产步进电机,型号是90BF33,其有关技术参数如下:步进电机型号:90BF33 空载起动频率: 1 500脉冲s额定负载起动频率: 1 20O脉冲s 步距角:q=15度脉冲控制器收到光电传感器1送来的信号后,即向步进电机发送加个脉冲信号,使旋转溜管转动36度,其所用时间t=0.02s所用时间几乎可以忽略不计,但是在初次试车时,发现旋转溜管在启动,停止时振动极大,甚至发生步进电机丢步。经分析,造成这些不正常情况的原因是启动,停止时加速度极大且旋转溜管质心偏离回转中心(增加了惯性矩)。我们采取了如下改进措施;a. 降低起动脉冲频率通过调谐控制器,使脉冲频率在保证每次转动时间为01 s时取最低值; b尽量减轻旋转溜管的重量,从而减少其转动惯量。通过以上改进后,旋转溜管运行的非常稳定。2、生面团下落时间:生面在离开提升输送带后,落人旋转溜管。再通过导向溜管、最后落入托盘。在这个工作过程中,我们不希望看到的是旋转溜管还没有转动到位的时候,下落的生面团已经到达旋转溜管的下部,这样可能造成生面团不能顺利进入导向溜管。甚至损坏旋转溜管。另一个可能的问题是:如两个生面团在提升输送带上挨的很近,甚至没有问隔,这样有可能使光电传感器2发出的信号间隔时间小于01 s,甚至信号时间间隔为零,这样有可能造成两个生面团落入托盘上同一个位置。调整提升皮带机出口与旋转溜管入口的垂直距离H(见图2.3),目的是当光电传感器1发出信号后,经过0.1 s。生面团才落入旋转溜管的入口,此刻,旋转溜管己转动到。H的最佳值可按自由落体公式计算: (2.1)其中g取,t取0.1s。经计算H=50mm。通过调整高度H(H 50mm),调整光电传感器1的安装位置,其最理想的位置是生面团刚脱离提升输送带开始下落的那一点。调整提升输送机的带速,目的是保证在任何情况下,光电传感器1发出信号的间隔大于0.1s。通过试车,时间间隔最好在0.2s以上,这样就能确保两个连续生面团不落入到托盘上同一位置。最终保证排放机适应性能大大提高【2】。3、生面团行距:设计生面团排放行距为80mm,当控制器接收传感器1发来的信号,通过计数,每隔10个信号就发出一个电脉冲,令电磁离合器吸合,将电动机的动力传给送进机构。当送进机构运行带动控制盘转动时,控制盘上均布着若干小孔),控制盘上的小孔将导通光电传感器2,将产生一个电信号,控制器收到这个信号后将发出指令,使电磁离合器断开,送进机构运行停止,从而完成行距的送进【5】。如图2-4所示。图2-4 进给机构旋转溜管式生面团自动捧放机是一种新型的机电一体化产品,它结构简单,工作可靠,但是要应用到生产线上还需做一些配套工作。我想用上旋转溜管式生面团自动排放机后,馒头生产的自动化将会有很大的一次飞跃,馒头生产工业化毕将代替手工制作。3机械结构的设计与计算3.1旋转溜管的设计旋转溜管是将从输送带送来的馒头实现有规律的圆周喂料,旋转溜管由步进电机控制。旋转溜管是实现自动排放的关键环节。溜管是由圆筒焊接而成,还可对馒头的下落起一定的缓冲作用,避免馒头的较大变形。由于旋转溜管结构简单,质量较轻,所以步进电机可以选号为:90BF3-3 。 其参数如下:空载启动频率:额定负载起动频率:步距角:由于旋转溜管是非标准件,设计时遵循的原则是:面团可以精确的落入溜管中,同时面团可以顺着溜管滑下,则溜管与垂直的夹角小于45度,面团直径大约30mm40mm。则导料管直径应大于40mm,同时需要面团精确落入导料管,则可选直径为90mm。具体尺寸一图纸为准。3.2 送进机构的设计3.2.1链条的型号及尺寸根据任务书可知,托盘尺寸为:800mm800mm,初定两链轮中心距为3500mm.由任务书可知,需要输送链来输送托盘,根据各种链条的特点及其适应场合可知,应选用双节距滚子链来输送。因为链条上要承重,所以宜于安装导轨承托,所以选磙子连较合适。再者,此重链条型号较齐全,宜于选用。又因可安装定位拨叉的附件链条。因为每个托盘宽800mm, 两排面团间行距较宜,又为了安装定位拨叉,所以还要配以K1型附件链板。链号M28,P型滚子链,链条节距选80mm,整链链节距数为110,K1型附件的输送链。如图3-1。所示标记为:M28-P-80110K1 其参数如下:链号:MP型滚子直径D1:30节距P:80 内链节内宽B1:17内链节外宽B2:25外链节内宽B3:25.2链板高度H2:21套筒内经D3:7.1套筒外径D4:10.0销轴直径D2:7销轴长度B4:40图3-1 链条安装了定位螺栓解决了托盘的纵向定位问题,但横向定位在工人操作起来也是很必要的,工人不可能每放上一个托盘就用眼去看托盘有没有放好。为此我们设计了横向定位轮,工人每次把托盘放上就可顺势一推靠着定位轮,这样托盘就可顺利的通过分配盘,而且也满足了面团落到预期位置的一个条件【7】。3.2.2链条附件尺寸K1查机械设计手册第二卷 P8-134可知附件尺寸如下:D:9.0H:20F:64B:1003.3送进机构链的计算3.3.1、链轮转速的分析依据托盘必须在1秒内前进80mm来确定,可知链速最小为80mm/s(即0.1m/s)。由于链输送在整个过程中传动比、链速和速度不均匀性,当节距P=80、齿数Z=12时,确定转速利用公式: (3.1)得到=5r/min因而排放机中输送装置转速须满足5r/min其实也可这样考虑,链条应该在1秒内走过80mm,即一个节距也就是说链轮要在1秒内转过一个齿(30),而为了机构能理想的完成动作要求,速度应该更快一些,况且还有离合器断开吸合时的速度损耗,也应使链轮转的再快一些,而输送链具体运行到位是又传感器精确控制的。从这一点考虑速度快一些是没有什么防碍的(但从惯性会使托盘上的面团移动这一点考虑速度也不宜过快)。所以根据分析选链轮的转速为78r/min。为了使机构结构紧凑,安装方便,简化设计过程,而选取减速机与电机一体装置-减速电机,在次选取上海旭普电机有限公司生产的SD(斜齿轮-锥齿轮减速机)系列的SD 83 Y802-4 NA7 B3 A 减速减速电机。 输出转速为7.0r/min 输出扭矩1020NM 使用系数=2.60。其选型参数,安装尺寸以及外观见附表。3.3.2计算功率选取电机计算结果由机械设计手册查得:水平输送及倾斜输送所需功率V=10cm/s顶托式输送机:q 链条及其附件的质量 q=3.08kg/m=0.2M=28S=3.5m得=选取电机功率为0.0707kw考虑到所设计机构为间歇运动,有惯性及功率损失等众多复杂的因素,根据经验选功率为0.75KW的电机F=5.83KNP=0.0707kw取电机功率为0.75KW3.3.3链轮齿形查机械设计手册第二卷P 8-135可知 节距P:配用链条参数,P=80 滚子外径D1:配用链条参数,=30 齿数:齿数范围为640,优先采用8、10、12、16和24.选Z=12 分度圆直径D:d=得:d=309.119mm齿顶圆直径:取:da=329.12mm齿根圆直径: 得:df=279.12mm齿轮凸缘直径: 得:dg262.26mm 取dg=80mm根据机械设计手册可查得其他参数:倒角宽度:g=2.72mm倒角半径:r=27.2mm齿宽:b=14mm3.3.4 离合器的选取根据设计的需要,本机构为间歇式运动机构,根据本机构是要由微控制器控制的机电一体化产品,所以选取电磁离合器,选天津机床电器有限公司生产的DLM2(小型)干式多片电磁离合器。如图3-1所示【11】。因为干式的动作快,价格低,控制容易,转矩大,工作性能好,适于迅速操作频繁,而且还带有链轮,可直接装在链轮轴上,这样大大简化了传动系统。图3-2 电磁离合器基本参数为:规格额定动转矩接通时间断开时间额定电压许用最高转速质量16160N.m0.28s0.06s24v2000r/min6.2Kg其主要尺寸如下:规格 D1 D2 D3 D4 D d b 16 148 85 88 134 45 e h L L1 L2 L3 L4 L5 电刷型号 1 79 58 13 8 16 7DS-0034传动机构的设计计算4.1链传动特点 链传动是在两个或多于两个链轮之间用链作为挠性电元件的一种啮合传动。链传动的形式如图4-1所示:图4-1 传动装置 和带传动相比,链传动的主要优点是:1) 没有滑动。2) 工况相同时,传动尺寸比较紧凑。3) 不需要很大的张紧力,作用在轴上的载荷较小。4) 传动效率高,约为98。5) 能够在温度高和湿度较大的环境中使用。4.2传动机构计算1、已知条件(1)链轮齿数:主动轴上链轮齿数为Z1=25,从动轴链轮齿数为Z2=28.传动比i= Z2/ Z1(2)转速:i=n1/n2=z2/z1主动轴链轮转速n1=7.84r/min, 从动链轮转速n2=7r/min(3)修正功率Pd:PdKaPKz/KpPd0.216kw由设计功率P0=0.07070.75kw和主动轮链轮转速n1=7.84r/min 查机械设计可知:Ka=1.0 Kz=1.11 Kp=1(4)链条节距P:根据修正功率和主动链轮转速查机械设计手册第二卷得节距P=12A,即 19.05mm。(5)初定中心距a: 暂取 a=20P(6)链节数Lp:得:Lp=66.5 取:Lp=66节(7)链实际中心距:a=取:a=375mm(8)润滑方式选定:根据滚子链节距P=19.05和链条的速度v=0.667m/s查机械设计图9-14可选用润滑方式为用油刷或油壶人工定期润滑。(9)链条标记:根据设计计算结果采用单排12A滚子链,节距为19.05mm,节数为66节,其标记:12A-166GB1243.1-83(10)链轮材料及热处理:材料为45钢,热处理渗碳、淬火、回火。齿面硬度为5060HRC。2、链轮几何尺寸计算(1)主动链轮孔径: dh=35mmdhmax=72mm(2)分度圆直径: d= 得:d=170.09mm(3)齿顶圆直径: 取:da=180mm(4)齿根圆直径: df=d-dr 得:df=158.18mm(5)齿轮凸缘直径: dg得: dg149.51mm 查表得: h=18.08 (查机械设计手册上册表11-1)取dg=120mm根据机械设计手册可求得其他参数:轮毂厚度h: h=21.2轮毂长度l: l=69.96轮毂直径dh:dh=dk=2h=102.048齿宽:bf=8.93mm3 从动链轮几何尺寸的计算(1)分度圆直径: d= 得:d=152.4mm(2)齿顶圆直径: 取:da=155mm(3)齿根圆直径: df=d-dr 得:df=140.49mm(4)齿轮凸缘直径: dg 得: dg131.236mm 查表得: h=18.08 取dg=120mm根据机械设计手册可求得其他参数:轮毂厚度h:h=21.024轮毂长度l:l=69.38轮毂直径dh:dh=dk=2h=102.048齿宽:bf=8.93mm4.3机架的设计对于旋转溜管的机架设计,一是对于排放盘的机架设计,即将排放装置和旋转溜管安装固定;二是对于托盘输送的机架设计。首先对于排放盘的机架设计,根据先前的参数分析,即馒头由于自重而从旋转溜管中下落,根据其下落时间,计算出下落高度,计算出机架实际的控制高度。其次对于安装机架,根据实际生产需要,应用以及对材料,成本的需要。当托盘上按照设计要求排放完1010的馒头,使工人们很方便的就能将托盘移走,考虑到操作方便,其底座的安装机架的设计高度范围大概为;0.70.8m。而对于安装机架的宽度设计,则根据排放的要求;1010,每个馒头之间的间隔为80mm。所以托盘的设计大小应为:800 mm800mm【10】。另外考虑到安装机架要安装链轮来传递托盘,所以根据其安装要求和实际需要,安装机架的设计宽度应为898mm。5轻型输送机的设计为了适应于馒头自动排放机的需要,适应于馒头生产线造化连续化生产的要求,在馒头成型机和排放机之间设置一输送机。根据机构工作的实际情况,此输送机一个显著特点就是轻小,因为此输送机,只需将1两的面团从400mm的高度输送到1450mm的高度即可。1、根据面团直径较小的情况,选带宽B=100mm;2、带速V=0.25m/s;3、由于此机构属于特轻型输送机,考虑到简约化的理念,驱动装置采用特轻型风冷式电动滚筒,在此选用的轻型风冷式电动滚筒系广东省汕头特轻输送设备厂的产品,又因此处所用滚筒较小,只能是电机外置式。代号为:SD10-0.25/0.25。滚筒采用轴承内置式这样安装方便也能使输送机更轻巧【8】。结论毕业设计是大学生毕业前最后一个重要的实践环节,是学习深化与升华的重要过程。题既是我们学习、研究与实践成果的全面总结,又是对学生素质与能力的一次全面检验,而且还是对学生的毕业资格及学位资格认证的重要依据。通过本次毕业设计使我对机械设计及其自动化有了更深刻的认识,特别是通过本次设计让我了解了面团自动排放机的基本结构及其工作原理,设计与计算的过程也是个不断学习、不断完善自我的过程,在这个过程中,熟练掌握了AutoCAD的作图技能,同时对专业知识有了进一步理解和体会,认识到了一个兼顾工艺与经济效益的设备。综上所述,在此次毕业设计的实践中,学到了很多专业知识,积累了不少宝贵的经验,令我受益匪浅。在今后的学习生活中,使我更有信心的面对各种困难。同时本次设计为我以后进一步学习打下基础。致谢本次毕业设计能够顺利完成,得益于黄河科技大学机械系所有教师的认真负责的帮助,使我有了完成毕业设计所要求的知识积累和能够很好的掌握和运用专业知识的能力。正是有了教师们的悉心帮助和支持,才使我的毕业设计工作顺利完成,在此向机械系的全体教师表示由衷的谢意,感谢他们四年来的辛勤栽培,在此更要感谢指导老师穆老师的指导,穆老师渊博的专业知识,严谨的治学态度,精益求精的工作作风,诲人不倦的高尚师德,严以律己、宽以待人的崇高风范,平易近人的人格魅力对我影响深远。穆老师对本毕业设计初稿进行逐字批阅,指正其中的错误,使我有了思考的方向,他得循循善诱的教学和不拘一格的思路给予我无尽的启迪,他得严谨细致、一丝不苟的作风,将一直是我工作。学习中得榜样。我还要感谢同组的各位同学,在此次毕业设计的这段时间,你们给了我很多启发和帮助,提出了很多宝贵的意见,对于你们的帮助和支持,我表示深深地感谢。同时在设计过程中,参考的相关书籍和论文,在这里一并向有关的作者表示感谢。在临近毕业之际,我还要再次借此机会向在这四年来给予我帮助和指导的所有老师表示由衷的谢意,感谢他们四年来的辛勤栽培。参考文献1周全申 朱庆方 朱克庆 旋转溜管式生面团自动排放机,郑州粮食学院学报。2周全申 旋转推板式生面团自动排放机构,郑州粮食学院学报, 1998(1)41433旋转推板式生面团自动排放机 郑州粮食学院学报CN41-1113/TS ,1998.4濮良贵 机械设计(第七版) M.北京:高等教育出版社,2003.5.5廖念钊 互换性与技术测量(第四版) M.北京:中国计量出版社,2003.8.6吴棕泽 机械设计师手册M.北京: 机械工业出版社,2002.7编辑委员会 运输机械设计选用手册M. 化学工业出版社 1999.8机械设计手册(第二卷) 机械工业出版社9机械设计手册(第三卷) 机械工业出版社10吴棕泽 机械课程设计手册 高等教育出版社11周名衡 离合器、制动器选用手册M. 化学工业出版社 1996.12周开勤 机械零件设计手册(第五版) M.北京:高等教育出版社, 2002.513成大先 机械设计手册(第五版) 化学工业出版社14周全申 食品推放机构的研究与设计.郑州粮食学院学报,1989(1):35 15 Richard P.Paul, Robot manipulators : Machematics, Programming and control, MIT Press,1981.Comparison of various modeling methods for analysis of powder compaction in roller press Roman T. Dec a , Antonios Zavaliangos b, * , John C. Cunningham b a K.R. Komarek Briquetting Research Inc., Anniston, AL 36207, USA b Department of Materials Engineering, Drexel University, Philadelphia, PA 19104-2875, USA Abstract Recently used models relating basic properties of the feed material, roller press design and its operating parameters are reviewed. In particular, we discuss the rolling theory for granular solids proposed by J.R. Johanson in the 1960s, later trials utilizing slab method and newly developed final element models. These methods are compared in terms of efficiency and accuracy of predicting the course of basic process variables like nip angle, pressure distribution in roll nip region, neutral angle, roll torque and roll force. The finite element method offers the most versatile approach because it incorporates adequate information about powder behavior, geometry and frictional conditions. This enables to perform realistic computer experiments minimizing costs, time and resources needed for process and equipment optimization. D 2002 Elsevier Science B.V. All rights reserved. Keywords: Roll compaction; Modeling methods; Finite element model 1. Introduction The conceptual simplicity and low operating cost make roll pressing a very popular pressure agglomeration method. It is used for a large number of materials in mining, mineral, metallurgical, chemical, food and pharmaceutical industries. There can be a number of reasons for particle size enlarge- ment, the most important are to improve material storage, handling, feeding, dosing or mixing characteristics. In ther- mal operations, it can also improve efficiency of melting, drying or burning. A roll compaction operation is successful when it produ- ces compacts with uniform, desired mechanical (or other) properties at a specified production rate and unit cost. It dependsonproper matchingofthepropertiesofpowdertobe processed with the design and operating parameters of the roller press. The main feed material properties to be considered are the stressstrain relationship and friction coefficient as a function of powder density (or stress state). Important design factors will be: feed system design, roll diameter and roll surface geometry. The main operating parameters to be set are: the roll speed, roll gap, roll torque, roll force, feeder and deaerating device conditions. Current industrial compacting and briquetting practice is largely based on trial-and-error techniques. While it is possible to achieve the optimum process performance using such an approach, it results in an increase of operating cost and time, especially with higher value materials and more demanding quality requirements. An alternative approach is to use mathematical modeling to provide necessary information for proper equipment and process design. In spite of its apparent simplicity, powder compaction in a roller press exhibits some behaviors and interactions that are poorly understood from an analytical view. Mathematical models that will allow realistic numer- ical simulation of powder compaction and appropriate visualization of these results can permit the process engineer to gain a better understanding through the process, leading to its better design and control. The purpose of this paper is to review the existing models and compare them in terms of efficiency and accuracy of predicting the course of basic process variables. Only three models developed through the last few decades and thought to be best suited for predicting mechanical behavior of granular materials during roll compaction are considered. 0032-5910/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved. PII: S0032-5910(02)00203-6 * Corresponding author. Tel.: +1-215-895-2078; fax: +1-215-895- 6760. E-mail address: azavaliacoe.drexel.edu (A. Zavaliangos). Powder Technology 130 (2003) 265271 2. Models of compaction process in the roller press 2.1. Model proposed by J.R. Johanson Developed in mid-1960s, it was the first complex model allowing to predict behavior of the material undergoing continuous shear deformation between the rolls. The mate- rial is assumed to be isotropic, frictional, cohesive and com- pressible and to obey the effective yield function (Jenike Shield 1). Pressure distribution above the nip region was determined based onthe continuousplane-straindeformation and assum- ingtheslipalongtherollsurface.Thefollowinginputdataare needed: effective angle of internal friction and angle of wall friction. Both can be determined using a Jenike shear tester. In the nip region, a very simplified material model was applied. It was assumed that there is no slip between the material and the roll surface and all material trapped between the rolls at the position of nip angle must be compressed into a strip with the width equal to the roll gap. As a result, pressure in the nip region is described by the pressuredensity relationship obtained from the experi- ment using punch-die system. Two equations are considered to determine the nip angle, as it is illustrated in Fig. 1. First one, represented by solid line, describes pressure gradient for the x direction, assum- ing that slip occurs along the roll surface. When slip does not take place between compacted material and the rolls, pressure gradient is given by the second equation shown by the dashed line in Fig. 1. Based on the examinations presented in Ref. 2, it is indicated that the intersection of the two curves gives the angle of nip, a. The actual pressure gradient above the a is given by solid line, and from a to the rolls center axis by the dashed line. This model can be very useful to determine the angle of nip for gravity fed roller presses. It gives a good agreement with experimental data when applied to the cases where smooth rollers with large diameter (over 500 mm) are used. Discrepancies are much higher when cavities are cut into the roller working surface and, as a result of simplifying assumption, roller diameter is reduced by the mean depth of those cavities. In the case of predicting the values of basic operating parameters like roll force and roll torque, the agreements are reasonably good for granular materials showing high coef- ficient of friction against the roller surface and mid and high values of compressibility constant, K. Discrepancies between computed and measured values are bigger (some- times over 50%) when higher compaction pressures (over 100 MPa) are applied and materials are very compressible (low K value). In spite of its limitations, it should be pointed out that it has been the first model allowing engineers to analyze the correlation between basic process variables and properties of the granular material. It also emphasizes that a lack of understanding compaction mechanism can result in a proc- ess and equipment design which will not produce a product with the required characteristics. Considering the simplifications made while modeling powder behavior in the nip region were responsible for discrepancies with the real system, a modeling technique known as a slab method was evaluated. 2.2. Analysis of nip region based on slab method This method of modeling was widely used to predict pressure distribution and roll separating force in metal rolling process. Similarly to the Johanson model, plane sections are assumed to remain plane as they pass through the rolls. It was first applied to analyze metal powder rolling by Katashinskii 3. However, yield criterion for fully dense metal was used in those initial studies. In the analysis presented below, the concept of yield criterion for metal powders proposed by Kuhn and Downey 4 was employed in order to develop the material model. Deformation zone under the rolls was divided into trapezoidal slabs as seen in Fig. 2 5. The force balance on the slab results in the equilibrium equation for the x direction and is expressed as: Bhr x Bx 2ptana x C0 s f 0 1 In Eq. (1) the frictional stress is expressed as: s f Yq : for lppzYq2 s f lpp : for lpp 95%) porous metal. The friction for the roll/material was assumed to follow the Coulomb friction law with a constant frictional coef- ficient. The effect of the feed system was represented by a constant feed stress applied to the mesh in the rolling di- rection at the inflow boundary. To address the severe mesh distortion observed in the initial implicit Lagrangian simulations, the arbitrary Lagran- Fig. 5. The roll pressure vs. rolling angle as function of feed stress for powder/roll friction coefficient of 0.50. Fig. 6. The roll pressure vs. rolling angle as function of feed stress and coefficient of friction. R.T. Dec et al. / Powder Technology 130 (2003) 265271 269 gianEulerian (ALE) analysis features with adaptive mesh- ing were employed with the explicit version of the ABA- QUS finite element code. The mass and densities of the roll and material mesh were optimized to minimize inertial effects for this quasi-static deformation problem and to minimize computational time. Eulerian inflow and outflow boundaries were used. The simulation was conducted until steady state conditions were reached based on the constant values of the roll force and roll torque. The simulations were conducted to evaluate the effect of the frictional coefficient at the roll/powder interface and the feed stress on basic process variables: roll force, roll torque, nip angle and neutral angle. The nip angle was defined as a value of the rolling angle in which the linear velocity of the roll surface is equal to the velocity of contacting material (no slip), the neutral angle as the angle in which the frictional shear stress at the roll surface reverses direction. These values along with the relative density of compact at the exit are presented in Table 1. The roll pressure profiles as a function of feed stress and coefficient of friction are shown in Figs. 5 and 6, respec- tively. The shear stress profiles as a function of feed stress and coefficient of friction are shown in Fig. 7. The results indicate reveals the anticipated two regions of slip in the feed zone and sticking in the nip region. The nip angle is approximately 8.5j and 12j for coefficients of friction of 0.35 and 0.50, respectively. The feed stress had a significant effect on the maximum roll pressure generated. Increasing the coefficient of friction for a given feed stress likewise increased the maximum roll pressure. In all con- ditions, the maximum roll pressure is observed 0.5j to 1.1j before the centerline between the rolls. The roll force and roll torque increased as expected with increasing feed stress and frictional coefficient. Likewise, the exit relative density also increases with the increase of frictional coefficient and the feed stress. The contour plot of velocity in the rolling direction for the simulation in which the feed stress is 0.21 MPa and the Fig. 7. The shear stress at the roll surface vs. rolling angle as function of feed stress and coefficient of friction. Fig. 8. Velocity in the rolling direction (v1) in mm/s for example simulation (feed stress=0.21 MPa and coefficient of friction at roll/powder=0.50). The roll is rotating with a linear velocity of C050 mm/s at the surface. Note the nonhomogeneous velocity especially in the feed zone. R.T. Dec et al. / Powder Technology 130 (2003) 265271270 coefficient of friction at the roll is 0.50, which is shown in Fig. 8, reveal a nonhomogeneous velocity field especially in the feed zone. Additional refinement of the finite element model is necessary before final experimental verification of the results. For example, material stress at the roll entry should be considered as a function of time and position to better represent influence of the feed screw system. Also, improve- ment in the material model and treatment of the friction phenomena should add to better agreement with the real physical system 13. 3. Summary and conclusions Presented work demonstrates the historical development of the models describing compaction process in the roller press. As it was shown, final element-based analysis has several advantages over the modeling methods used in the past. By utilizing the commercially available software, models can be adjusted, to generate improved solutions through a process of hypothesis, numerical testing and reformulation. Prediction of relative densities, material flow, deformation energy, shear stress (roll torque), pressure distribution (roll force), position of nip angle and neutral angle, failure of the compact during release, etc. can all be made with these models. All of these important consider- ations can be taken one step further by including model of the feeding process and forming tool geometry (cavities in the roll surface). It leads to realistic analysis of the com- paction process and with appropriate visualization of the results to a better design and control. This is particularly important with manufacturing of engineered agglomerated products with specific properties (pharmaceutical, chemical, ceramic or semi-conductor industries). The biggest challenges with the implementation of the FEM modeling are arising not from the computational problems, but from preparation of the adequate input data. There is a need for better, more accurate material models, which realistically represent the behavior of the powder through the wide range of densities during compaction. Using the appropriate friction model, describing phenom- ena on the material/forming tool interface is of great importance as well, because all the processing energy is transmitted throughout the roll-material contact. Another need is to move into three-dimensional modeling and to incorporate models of material behavior in the feeding devices. References 1 A.W. Jenike, R.T. Shield, On the plastic flow of coulomb solids beyond original failure, Journal of Applied Mechanics 26, Trans. ASME 81, Series E (1959) 599602. 2 J.R. Johanson, A rolling theory for granular solids, ASME, Journal of Applied Mechanics 32 (ser. E, No. 4) (1965) 842848. 3 V.P. Katashinskii, Analytical determination of specific pressure during the rollingof metalpowders(in Russian),Soviet PowderMetalCeram. 10 (6) (1986) 765772. 4 H.A. Kuhn, C.L. Downey, Deformation characteristics and plasticity theory of sintered powder materials, International Journal of Powder Metallurgy 7 (1) (1971) 1525. 5 R.T. Dec, Study of compaction process in roll press, Proceedings, Institute for Briquetting and Agglomeration 22 (1991) 207218. 6 R.T. Dec, R.K. Komarek, Roll press design for powder and bulk solids, Proc. 15th Powder and Bulk Solids Conference, June, 1990, pp. 125136. 7 V.P. Katashinskii, M.B. Stern, Stressstrain state of powder being rolled in the densification zone: I. Mathematical model of rolling in the densification zone, Poroshkovaya Metallurgiya 11 (251) (1983) 1721. 8 V.P. Katashinskii, M.B. Stern, Stressstrain state of powder being rolled in the densification zone: II. Distribution of density, longitudi- nal stain and contact stresses in the densification zone, Poroshkovaya Metallurgiya 12 (252) (1983) 913. 9 S. Shima, M. Yamada, Compaction of metal powder by rolling, Pow- der Metallurgy 27 (1) (1984) 3944. 10 PM Modet Modelling Group, Comparison of computer models rep- resenting powder compaction process, Powder Metallurgy 42 (4) (1999) 301311. 11 ABAQUS Version 5.8, Reference Manuals, Hibbitt, Karlsson and Sorensen, Pawtucket, R.I., 1999. 12 P.T. Wang, M.E. Karabin, Evolution of porosity during thin plate rolling of powder-based porous aluminum, Powder Technology 78 (1994) 6776. 13 J. Cunningham, PhD Thesis, Drexel University, Philadelphia, PA, USA (in press). R.T. Dec et al. / Powder Technology 130 (2003) 265271 271
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