滚筒式抛丸清理机的总体和结构设计
滚筒式抛丸清理机的总体和结构设计,滚筒,抛丸,清理,清算,总体,整体,以及,结构设计
外文翻译译文用抛丸清理机对板材轧辊进行抛丸处理V. I. Meleshko, A. P. Kachailov, V. G. Boikov,V. L. Mazur, T. P, Kobka, 和 I. I. Krivolapov目前,轧制品的质量受到许多关注,特别是板料。这从相当大的程度上取决于轧辊表面处理。许多公司着手提高轧辊表面处理的质量,为辗压作准备。这篇文章的作者来自Zaporozhstal公司,Magnetogorsk冶金联合企业的人员,有色冶金研究所, Dnepropetrovsk和Magnetogorsk采矿和冶金学院,来研究这个现实的问题。微表面质量,或粗糙施工的冷轧板,对金属的机械性能和生产性能,也对来自于这块板料部分的最终质量有影响。薄钢板最终微表面的形成是通过对已用金属球粗加工过的表面进行工作辗压得到的。通常情况下,对不合标准表面的工作辗压粗加工是由气动力学和电动抛丸清理机完成。在使用中的经验表明国家钢铁厂使用的气动机不能满足辊板表面抛丸处理的高质量要求。 1969年,Dnepropetrovsk冶金研究所在Zaprozhstal厂1号冷的混乱的磨房研究了SM-2型抛丸清理机,发现了一些它结构上的缺点。为了提供符合伏尔加汽车厂表面粗糙度要求的板料(粗糙度为0.8-1.6u),用于抛丸机设计的基本要求是确定的。机器必须满足:1. 在操作时一个持续的喷丸尺寸,换句话说,有效去除已磨损弹丸的既定尺寸;2. 平稳操作时,控制抛丸机收集的空气气压的可能性;3. 在机器没有特别的设备时,对不同直径(400-500mm)的工作辊的处理;4. 控制简单,维修方便。 图一SM-2抛丸机(如图1)是由一个装有轮子的固定的封闭室1,一个可移动喷管2(2在压缩空气的行动下,对轧辊表面发射弹丸),一个蠕虫输送机3,有分隔的传送机4,抛丸装置5,和排气系统6组成。该设备安装在一个低于地面水平1905毫米的特殊地基上。有小车的机器的长度是15,200拉姆 ,高度是4070毫米,宽度4600毫米。操作的辊的尺寸是直径400-500毫米,长度2000-4000毫米。整台设备的总重量是15吨。 研究表现了操作中一个工作中混合磨料磨损的动力和弹丸变化的原始情况。在抛丸时,弹丸在一个更大的尺寸范围内变化,磨损,形成许多微粒。在这种情况下,零件的抛丸取决于所用弹丸的尺寸。特定大小的微粒污染会破坏抛丸过程,使辊表面以及最后板料上的表面粗糙度降低。为了解决这些问题,有必要既定期地检查弹丸构成,在抛丸过程中做适当调整(在实际中很难做到),又要在机器运行过程中筛选弹丸以提供特定大小的微粒。 抛丸过程中的稳定性也是由送入喷管的弹丸的数量所决定的。实验表明,在气压2.5 -4.0atm下,提供0.3-0.4kg/sec的弹丸到运行的两个喷管中可以使操作稳定。给机器装配一个筛选装置是一个保持弹丸尺寸的有效方法。理论上的数据和Zaporozhstal公司在SM-1 和TsKb_P-1抛丸清理机的实际操作经验都证实了这一点。弹丸通过抛丸装置传送到辊表面,机器的封闭室被分为两个隔膜间,每间分为三格,并配备一个电子气动控制装置。工作混合物从上格式下降到较低的,然后收集。在操作机器时,排气口被关闭(打开)。弹丸要么在电子气动控制装置关闭阀门后送入,要么在操作者关闭抛丸机以后送入。当机器关闭时,出气孔下降,并且在它和膜片之间形成了一个圆空5毫米宽的圆孔。排气口是一个大约有30度的锥体,弹丸慢慢通过这一缺口,但不完全,然后弹丸直径减少到10毫米。装载喷口由控制装置轮流打开。首次维修SM-2抛丸机时,发现由于零件的腐蚀,控制系统经常不运行。正常磨料(根据铭牌三百七十五千克),在交替通过每个喷管后必须停止抛丸,因为之后另一个通过弹丸的低射舱室是不够的。在抛丸时由于控制装置不运转,它不能从较高的舱室下降到较低的。仅仅在操作者将抛丸设备从空气系统中分离后,下一部分的弹丸才能被送过来。在这种情况下,两个掌管的通风口都必须被打开,磨料要被送到较低的舱室。机器的连续工作使磨料通过没有控制装置的三至四个喷管,在磨料增加到标准要求650kg后,上述弹丸的运输才变为可能。然而,解决这个问题的基本方案还是控制装置的稳定运行。可用的弹丸是由工作室的收集舱收集的,然后落入蠕虫传送机的接受槽。平行于蠕虫传送机的板材处在一个更大的角度,而那些垂线正处于一个角度,倾向于收集朝它们射来的弹丸。因此,在对一个辊板进行抛丸后有必要关闭机器将累积的弹丸推到螺旋传送器上。为了消除这个缺点,将螺旋传送器加长到工作室长度的一半是可行的。此外,更小的板料已经完全消除,平行板被拉长以符合蠕虫输送机的长度。提供给抛丸设备收集室的压缩空气被油水分离装置烘干。然而,这种干燥方法是不够的。水蒸气凝结在主线和抛丸设备内,结果弹丸在低舱室内都粘到一起,形成了坚实的一堆。这一堆弹丸阻塞在垂直管内,阻碍了磨料沿着垂直管到达收集室的过程,也打乱了抛丸过程中弹丸抛向空中的最佳比例。这对抛丸过程及轧辊表面质量有不良影响。空气中存在的水分导致机器的腐蚀,也导致机器气动设备的操作性能更差。因此,在设计抛丸清理机时,有必要指定干燥空气的设备。例如,外国企业使用特殊的干燥设备利用吸水物质,如硅胶和活性氧化铝干燥压缩空气。图二移动喷管的机制存在一些缺陷。磨料射到轧辊表面是通过一个安装在肘形枪管(图2)上的喷管完成的。枪管的一个缺点是对压缩空气的混合物和弹丸的节流作用,节流处横向和纵向的管道也在。交汇处是一个直角,这导致了肘形枪的快速磨损,管道和喷管的交界区域增加。然而,随着喷管直径从10毫米增加到12毫米(允许的最大值),空气的消耗从13增加到19立方米每小时,改变了弹丸射向空中的比例。然而,这个比例必须保持稳定。因为在抛丸过程中很难纠正这个问题,因此有必要改善设计,增加零件的抗磨损度。为了这个目的设计了一款新型喷枪,它的管道直径增大了(图2b),从管道过渡到管道和喷嘴的形状也改变了。提出并经过测试,新的喷嘴设计更为有效。五个月的操作后,改良后肘枪和喷管没有发现显著的磨损迹象,而旧的肘枪一个月后就损坏了。喷枪通过传送带沿着辊移动。在台车重量和它沿着导轨运动导致的振荡的作用下,传送带离开对准线。从辊表面落下的弹丸在导轨上积累。结果,弹丸流对其表面的作用不是一个直角,而是扫过,导致表面质量更差。安置小条在肘枪之下解决了这个问题,而且使辊表面质量变得更令人满意。运行初期,SM-2抛丸机的压缩空气是从主要线路间得到的,其间有6atm的压力。根据在抛丸单位的收集室前安置的测压器读数,其间的气压不超过4.0atm 。在这个气压下,即使用尺寸最合适的弹丸,辊的粗糙度也在上限(粗糙度为2.7u)。因此,有必要降低空气的工作压力。空气阀是用来控制压力的,但它对空气压力的变化非常敏感,而且抛丸机的操作也不稳定。因此,减压阀被放置在油水分离器和抛丸设备间。这使我们能在精确度0.1atm下把在收集室的气压从4.0控制到2.0atm 。空气阀的运用使抛丸装置能够稳定的运行。为了把辊加工到不同直径,有必要每次都改变抛丸枪的位置,而SM-2抛丸机的设计没有提供这个功能。例如,现在要把直径为400毫米的辊加工到500毫米,必须关闭抛丸机做调整。在设计新抛丸机时,应该考虑改变枪的高度的可能。为了观察抛丸过程,灯火通明的工作舱长壁上开了一个特别的观察窗。然而,观察辊表面的抛丸过程是很困难的。因此,三个额外的500瓦灯泡在百叶窗的保护下,安装在工作舱的天花板上。图三机器(图3)的控制是通过控制面板2,在空中路线的阀5,用来控制辊的转速和喷管移动的变阻器,可以起动排气风扇机、在机器后的起动按钮来完成的。SM-2抛丸装置这样的布置控制起来不方便,控制速度的变阻器没有精确的范围,这使决定正确的速度变的困难。事实上,为确定每个控制手柄的新位置,有必要决定速度。这些缺点在设计新机器的时候必须消除。排气线的水平部分累积的金属垃圾的清除也有必要改善。排气线难以达到地面水平4米以上的位置。为了给抛丸机的独立单元提供更多方便和简化它的维护,钢铁冶金研究所开发并交给Zaporozhstal厂的建议已部分投入在现有的机器使用,而且将研究设计类似的新机型。SM-2气动抛丸机的改进使得控制和维持指定顺序抛丸冷轧工作辊和表面通过板料站更加可能。因此,Zaporozhstal厂正大量生产被冷轧的建设板料,这些板料以符合有色冶金技术规格1-683-69 和 1-686-69的表面粗糙度生产。6毕业设计(论文)任务书I、毕业设计(论文)题目:滚筒式抛丸清理机的总体和结构设计II、毕 业设计(论文)使用的原始资料(数据)及设计技术要求:1原始资料:滚筒式抛丸清理机的设计规格1000800mm;滚筒式抛丸清理机的其它主要技术参数:滚筒转速3r/min;最大有效容积0.1m3 ;最大载重量300kg ;工件长度400mm;工件单重15kg ;抛丸量100kg/min ;叶轮直径420mm ; 叶轮转速2300r/min ;抛射速度60m/s 2设计技术要求:根据主要技术参数设计滚筒式抛丸清理机的的结构。要求英文资料翻译忠实原文。要求完成的设计能满足实际要求,图面及文字说明表达简洁、清晰、易读懂,图纸设计规范,符合制图标准。能用于指导实际的生产、装配。要求毕业论文叙述条理清楚,设计计算正确,论文格式规范。III、毕 业设计(论文)工作内容及完成时间:1收集有关资料,写出开题报告; (2周)3月1日-3月14日2外文翻译(6000字符以上); (1周)3月15日-3月22日3分析与研究:了解现有类似设备的工作原理,制订设备工作原理图。(1.5周)3月23日-4月2日4滚筒式抛丸清理机的主要结构设计及计算。 (3.5周)4月3日-4月27日5滚筒式抛丸清理机的各主要配件图和总装图的绘制。(以上合计A0图2张,A3图6张)。(3周)4月28日-5月19日6撰写毕业论文一份 (2周)5月20日-6月4日7毕业设计审查、毕业答辩 (4周)6月5日-7月2日 、主 要参考资料:1. 王大康,卢颂峰.机械设计课程设计. 北京:北京工业大学出版社,2002.2。2. 汪恺.机械工业基础标准应用手册.北京:机械工业出版社,2001.6。3. 机械设计手册(新版).第一卷、第二卷、第四卷、第五卷.北京: 机械工业出版社,2004.8。4. 吴宗泽.机械零件设计手册.北京:机械工业出版社, 2003.11。5. 时钧.化学工程手册.北京:化学工业出版社,1996.1。6. 日本化学技术.化工机械设计和保养.上海:上海科学技术文献出版社,1985。7. Calculation of the Dimensions Blades for Drum Dryers. V.F.Pershin, A.A. Koryagin,V.L.Negrov, and A.G.Sidelnikov. Khimicheskoe i Neftyanoe Mashinostroenie, No. 11, pp. 21-22, November。 毕业设计(论文)开题报告题目 滚筒式抛丸清理机的总体和结构设计一、选题的依据及意义:本人的课题选自学校老师。抛丸清理机利用高速回转的叶轮,将弹丸抛向滚筒内不断翻转的铸件或锻件来清除其表面的残余型砂或氧化铁皮。清理均匀,生产率高,适宜于中小型铸锻车间清理15kg以下的小件使用。 本机设计时带有单独的集尘装置,故安装地点不受车间通风管路的限制,且卫生条件好。本机设有自动停车装置,故操作简便 。该产品适用于清理各种不怕碰撞、划伤的铸、锻件。是小型铸、锻、热处理车间清理工件表面残砂、氧化皮的理想设备。主要由滚筒、分离器、抛丸器、提升机、减速电机等组成。利用高速旋转的叶轮将弹丸抛向滚筒内部不断翻转的工件,使工件表面的附着物迅速脱落,从而获得一定粗糙度的光洁表面,达到清理的目的。二、国内外研究概况及发展趋势(含文献综述):抛丸机是机械产业中的通用基础设备,广泛应用于船舶、汽车工程、机械制造等行业的除锈、抛光、清砂等金属表面处理,国内外市场需求巨大。 国产抛丸清理机的市场前景广阔。日、韩这样的高度发达与中等发达国家,国内基本建设市场已经饱和,其国内的工程机械市场已停滞或萎缩,抛丸机清理机等工程建设机械很多依靠出口。而我国整个社会工业化进程尚未完成,大量的铁路、公路、水利基本建设正在和将要进行。大、中、小城市的交通、房屋建设方兴未艾,给抛丸机清理机等工程机械提供了大量的市场机会。 进入21世纪以来,马鞍山惊天公司、湖南山河公司已推出自己商标的抛丸机清理机。目前,较具规模的国内生产厂家有:惊天公司、山河公司和长治液压件厂。但国内产品的市场占有率仍很低,大部分市场被韩、日本、德国的产品所占有。商机不可失,国内的企业家应抓住这一产品市场大发展的机会,精心制造,不断创新,扩大销售,夺回国内市场,甚至出口到国外。三、研究内容及实验方案 :1研究内容主要研究滚筒式抛丸清理机的总体和结构的设计。滚筒式抛丸清理机的抛丸器为主要实行机构,其性能的好坏直接影响抛丸机的效率,还有传动系统和集尘装置也是抛丸机的主要机构。 2实验方案方案一 抛丸器传动:由电动机经皮带轮传动叶轮主轴使叶轮高速旋转。滚筒传动:由电动机经链轮传动带动托轮,再以摩擦传动滚筒。集尘器选用旋风除尘器。 方案二 抛丸器传动:由电动机经齿轮传动叶轮主轴使叶轮高速旋转。滚筒传动:由电动机经由皮带轮传动带动托轮,再以齿轮传动滚筒。集尘器选用电除尘器。 方案三 抛丸器传动:由电动机经链轮传动叶轮主轴使叶轮高速旋转。滚筒传动:由电动机经由齿轮传动带动托轮,再以齿轮传动滚筒。集尘器选用旋风除尘器。 方案一结构紧凑,布局合理,传动简单,可靠性高,使用寿命可以得到保障,制造成本低,加工简单。方案二、三效率比较低,加工成本高。经过三个方案的比较,选用方案一。四、目标、主要特色及工作进度:1目标为了清除铸件或锻件表面的残余型砂或氧化铁皮利用高速回转的叶轮将弹丸抛向滚筒内不断翻转的零件,要求达到如下目的:(1)综合运用机械和电器知识;(2)滚筒传动机构的设计;(3)轴的设计与校核;(4)滚筒传动机构所有零件的设计。该系列产品适用于清理各种不怕碰撞、划伤的铸、锻件。是小型铸、锻、热处理车间清理工件表面残砂、氧化皮的理想设备。主要由滚筒、分离器、抛丸器、提升机、减速电机等组成。利用高速旋转的叶轮将弹丸抛向滚筒内部不断翻转的工件,使工件表面的附着物迅速脱落,从而获得一定粗糙度的光洁表面,达到清理的目的。2 主要特色本机利用高速回转的叶轮将弹丸抛向滚筒内不断翻转的铸、锻件,来清除其表面的残余型砂或氧化铁皮。清理均匀,适宜中、小铸,锻件的清理。本机带有集尘装置,分离效果好,自动控制停车。操作、维修简便。3工作进度1收集有关资料,写出开题报告; (2周)3月1日-3月14日2外文翻译(6000字符以上); (1周)3月15日-3月22日3分析与研究:了解现有类似设备的工作原理,制订设备工作原理图。(15周)3月23日-4月2日4滚筒式抛丸清理机的主要结构设计及计算。 (3.5周)4月3日-4月27日5滚筒式抛丸清理机的各主要配件图和总装图的绘制。(以上合计A0、A3图共26张)。 (3周)4月28日-5月19日6撰写毕业论文一份 (2周)5月20日-6月4日7毕业设计审查、毕业答辩 (4周)6月5日-7月2日五、参考文献1.王大康,卢颂峰.机械设计课程设计. 北京:北京工业大学出版社,2002.2。2.汪恺. 机械工业基础标准应用手册. 北京:机械工业出版社,2001.6。3. 机械设计手册(新版).第一卷、第二卷、第四卷、第五卷.北京机械工业出版社,2004.8。4. 吴宗泽.机械零件设计手册.北京:机械工业出版社, 2003.11。5. 时钧.化学工程手册.北京:化学工业出版社,1996.1。6. 日本化学技术.化工机械设计和保养.上海:上海科学技术文献出版社,1985。7. Calculation of the Dimensions Blades for Drum Dryers. V.F.Pershin, A.A. Koryagin,V.L.Negrov, and A.G.Sidelnikov. Khimicheskoe i Neftyanoe Mashinostroenie, No. 11, pp. 21-22, November。5滚筒式抛丸清理机的总体和结构设计摘要: 本滚筒式抛丸清理机的工作原理是利用高速回转的叶轮将弹丸抛向滚筒内不断翻转的锥铸件或者锻件,来清除其表面的残余型砂或者氧化铁皮、清理均匀、生产效率高,适宜于中、小型铸锻车间清理小件使用,解决了小批量零件的清理工作。设计过程中,利用一级链传动减速带动滚筒和提升斗的回转和实验弹丸的循环使用。为了清除铸件或锻件表面的残余型砂或氧化铁皮利用高速回转的叶轮将弹丸抛向滚筒内不断翻转的零件。要求达到如下目的:a综合运用机械和电器知识;b弹丸循环及分离装置设计;c除尘器设计;d弹丸循环及分离装置、集尘器零件的设计。采用一级齿轮传动带动的抛丸器滚筒的抛丸工作,同时,运用干式旋风型除尘装置进行尘土分离工作。弹丸循环装置由滚筒护板于壳体之间的螺旋带提升斗及分离筛组成。由叶轮抛出的弹丸射击工件之后,从滚筒护板上的格子孔进入护板与筒壳体之间得空隙内,借助螺旋作用流到旋转的提升斗内。提升到上部,经过分离筛去毛刺、钉子、芯骨、砂、粒等。完整的弹丸经导入管再送入抛丸器内。设计针对小批量零件的清理工作,是有较好的实用价值和经济效益。设计对象为总装、弹丸循环及分离装置、除尘器设计、提升斗。本机利用带有独特的集尘装置安装地点不受车间同风管路的限制卫生条件好,本机设有自动停车装置,操作简便。关键词:型砂 氧化铁皮 毛刺 螺旋 Shot Blasting Machine Drum and structural design of the overallAbstract: The drum-type shot blasting machine works by using high-speed rotation of the impeller within the projectile thrown constantly turning roller cone castings or forgings, to remove residual sand or the surface oxide skin, clean uniform, high efficiency, suitable for in small and medium casting and forging shop clean up small pieces to use to solve a small part of the clearance volume. The design process, using a slow drive roller chain drive and enhance the struggle of the rotation cycle of the experimental use of the projectile. In order to remove residual casting or forging the surface of sand or iron oxide with a high-speed rotation of the impeller Pillay will continue to turn within the projectile thrown to the drum parts. Required to achieve the following purposes: a comprehensive use of mechanical and electrical knowledge; b projectile design cycle and the separation device; c filter design; d shot cycle and separation equipment, dust collector parts of the design. Using a gear-driven shot blast wheel drum work, while the use of dry-type dedusting cyclone dust separation device work. Projectile loop device of roller retaining plate in between the spiral shell with a separate screen to upgrade the Big Dipper and composition. Firing projectiles thrown by the impeller workpiece, the roller retaining plate from the grid plate and the cylinder bore into the shell protecting the gap between the have, the use of screw rotation to enhance the role of flow within the bucket. Elevated to the top, through the separation screen deburring, nails, core bone, sand, grain and so on. Complete projectile shot by the import into the canal inside. Designed for small batch parts cleaning work, there is a good practical value and economic benefits. Design object for the assembly, projectile circulation and separation devices, filter design, promotion fight. This machine is used with a unique location from workshop dust collection equipment installed wind pipe with good sanitary conditions restrictions, this machine is equipped with automatic stop device, easy to operate.Keyword: moulding sand millscale burr helix Signature of Supervisor:目 录 1 前言 .1 2 总体方案论证 .2 2.1 方案一 摩擦传动 .3 2.2 方案二 带传动 .3 2.3 方案三 齿轮传动 .3 2.4 方案四、蜗杆传动 .4 3 提升斗的设计分析 .6 3.1 旋风除尘器的特点 .6 3.2 粉尘的概念 .7 3.3 粉尘的计算 .8 3.4 粉尘的粘着性 .8 4 离心除尘技术 .10 4.1 离心式除尘工作原理 .10 4.2 转圈理论(沉降分离理论) .11 4.3 平街轨道理论 (假象圆筒学说) .11 4.4 边界层分离理论 .11 4.5 计算比传速 .11 4.6 计算最大弯曲应力 .13 4.7 旋风除尘器构造对性能的影响 .14 4.7.1 除尘器的直径及高度 .14 4.7.2 进口和出口形式 .14 4.8 卸灰装置 .15 4.9 灰斗 .16 5 旋风除尘器的计算 .18 5.1 流体阻力计算 .18 5.2 除尘效率计算 .18 5.3 运行各数对性能的影响 .19 6 旋风除尘器的注意事项 .21 7 旋风除尘器的防磨损措施 .22 8 总结 .23 致 谢 .24 参考文献 .25 附 录 .26 7外文翻译原文SHOT BLASTING MACHINES FOR THE BLASTING OF SHEET MILL ROLLSV. I. Meleshko, A. P. Kachailov, V. G. Boikov,V. L. Mazur, T. P, Kobka and I. I. KrivolapovAt the present time much attention is being devoted to increasing the quality of rolled products, partieularly sheet. To a significant degree this depends upon the preparation of the roll surface. Many plants are engaged in improving the quality of working the roll surface in preparing them for rolling.This article was written by personnel from Zaporozhstal Plant, Magnetogorsk Metallurgical Combine, the Institute for Ferrous Metallurgy, Dnepropetrovsk, and Magnetogorsk Mining and Metallurgical Institute on this very real problem.The surface microrelief, or roughness, of cold rolled constructional sheet has an influence on the mechanical and production properties of metal, and also on the finish quality of parts made from this sheet. The final surface microrelief of thin sheet steel is formed in a skin pass on work roils which have been given a rough finish with metal shot.Normally the rough surface finish on the work rolls of skin pass stands is produced in pneumatic and rotor shot blasting machines. Experience in their use has shownthat the pneumatic machines used in the countrys steel plants do not fill the need for high quality blasting of roll surfaces.In 1969 the Institute for Ferrous Metallurgy, Dnepropetrovsk, did work on the SM-2 shot blasting machine in No. 1 Cold Roiling Mill of Zaprozhstal Plant, which revealed a number of shortcomings in its construction.To provide sheet with the surface roughness required by the specifications of Volga Automobile Plant (R a =0.8-1.6 g),the basic requirements for the design of shot blasting machines were determined, The machine must provide:1. a constant shot size during operation, in other words, effective removal of shot of the specified size fromworn shot;2. the possibility of controlling air pressure in the collector of the shot blast machine during stable operations;3. the handling of work rolls of different diameters (400-500 mm) without special equipment on the machine;4. simplicity in control and convenience in maintenance.Fig.1The SM-2 machine (Fig. 1) consists of a stationary closed chamber ! with a trolley on wheels aad movab!enozzles 2 which under the action of compressed air discharge shot on to the roll surface, a worm conveyor 8, an elevator with a separator 4, the shot blast equipment 5, and an exhaust system 6. The equipment is mounted on a special foundation 1905 mm below the floor level The length of the machine withthe trolley out is 15fl00 ram, the height 4070 ram, and the width 4600 mr The dimensions of the rolls handled are 400-500 mm in diameter and 2000-4000 mm in length. The total weight of the equipment is 15 tons.As research has shown, the dynamics of the wear of a working mixture of abrasive and the original condition of the shot changes during operation. During blasting, the shot takes on a wider size range and is worn down, forming many fine particles. The conditions under which the parts are blasted depend upon the size of the shot used. The contamination of the specified size by fine particles disrupts the process, producing a poor quality surface on the rolls and consequently on the sheet. To eliminate these problems it is necessary to either regularly measure the composition of the shot and make appropriate changes in the blasting sequence, which is difficult to do in practice, or to screen the shot during operation of the machine to provide the specified particle size.Stability in the blasting process is also determined by the quantity of shot delivered to the nozzles. It was experimentally established that supplying 0.3-0.4 kg/sec of shot to the two nozzles in operating with an air pressure of 2.5-4.0 atm provided stable operation. Equipping the machine with screening devices is an effective method for maintaining a constant shot size mix. This is confirmed both by data in the literature and by experience in the operation of SM-1 and TsKb_P-1 shot blast machines at Zaporozhstal Plant.The shot is delivered to the surface of the roll by the shot blast equipment, the chamber of which is divided by two diaphragms with charging vents into three compartments and is equipped with an electropneumatic control device. The working mixture from the upper compartment of the chamber drops to the lower and then to the collector. During operation of the machine,the vents are closed (turned on). The shot is poured in either after turning off the valves by the electropneumatic control device, or after shutting down the machine by the operator. When it is turned off, the vent descends, and between it and the diaphragm a circular gap 5 mm wide is formed. The vent is a cone with a slope of about 30% The shot drops slowly through this gap but not completely, and therefore it increases to t0 ram. The loading vents are alternately turned on by the control device. The first time the SM-2 machine was repaired, it was discovered that the control device frequently did not operate because of corrosion of the parts. With normal charging of abrasive (375 kg according to the nameplate), blasting must be stopped after each alternate pass of the nozzles, since after another pass the shot in the lower compartment is insufficient, and during blasting, With nonoperation of the control device, it does not drop from the upper compartment to the lower. Delivery of the nextportion of shot must be done only after the operator disconnects the shot blast equipment from the air system. In this case both charging vents are opened, and the abrasive is fed to the lower compartment. Continuous operation of the machine for three or four passes of the nozzles with nonoperation of the control device and the delivery of shot described above became possible after increasing the standard charge to 650 kg. However, the basic solution of this problem is stable operation of the control device.The used shot is collected by the collecting bunker of the working chamber and drops into the receiving chute of the worm conveyor. The plates parallel to the worm conveyor are at a greater angle, and those perpendicular are at less of an angle, which tends to collect shot on them. Therefore, after blasting one roll it is necessary to shut the machine down to push the accumulated shot on to the screw conveyor. To eliminate this shortcoming, it is possible to lengthen the screw conveyor, which is half the length of the working chamber. In addition, the smaller plate is removed completely,and the parallel plates are elongated to correspond with the length of the worm conveyor.The compressed air supplied to the collector of the shot blast equipment is dried by an oil moisture separator. However, this method of drying is inadequate. Water vapor condenses in the main line and in the shot blast equipment, and as a result shot sticks together in the lower compartment and forms a solid mass. The solid mass clogs the vertical channels along which the abrasive is transported to the collector and disrupts the optimum ratio of shot to air in the blast. This has a detrimental effect on the blasting process and the quality of the roll surface. The presence of moisture in the air causes corrosion of the equipment and causes operation of the pneumatic equipment of the machine to be poorer. Therefore, in designing shot blast equipment,it is necessary to specify equipment for drying the air. Foreign firms, for example, use special drying equipment utilizing water absorbing substances such as silica gel and activated alumina for drying compressed air.The mechanism for moving the nozzle has a number of shortcomings. Application of the jet of abrasive material on to the roll is through a nozzle mounted in an elbow shaped gun (Fig. 2). A shortcoming of the gun is the throttling of the mixture of compressed air and shot where the vertical and horizontal channels join. The junction is a right angle, which causes quick wearing away of the elbow. The cross sections of the channels and nozzle was increased. However, with an increase in the nozzle diameter from 10 to 12 mm (the allowable maximum) the consumptionof air increased from 13 to 19 mS/h, which changed the ratio of shot to air in the blast. However, thisratio must be kept constant. Since during blasting it is difficult to make corrections, it was necessary o improve the design and increase the wear resistance of the parts.Fig.2For this purpose a new design of blast guns, in which the diameter of the channels was increased (Fig. 2 b) and the shape of the transition from the channel to the channel and nozzle was changed, was proposed and tested, The new nozzle design is much more effective. After five months of operation,noticeable signs of wear in the elbowand nozzle have not been found, while the old design elbows wore out in a month.The blast guns are moved along the roll by a conveyor belt. Under the action of the weight of the troJ.ley and oscillations caused by its movement along the guides on which shot falling from the surface of the rolls accumulates, the belt gets out of alignment. As a result, the impact of the stream of shot on the surface is not at a right angle, but glancing, which produces a poorer surface quality. Placing a strip under the gun eliminated this problem, and the roll surface quality became satisfactory.In the first period of operation the compressed air tn the SM-2 machine was obtained from the shop main i,ine, which has a pressure of 6 atm. According to readings on a manometer placed before the collector of the shot btaat unit, the air pressure in it did not exceed 4.0 aim. With this pressure, even with the use of the finest shot (DChK-0.8), the roughness of the rolls is at the upper limit (R a = 2.7 #).Therefore, it was necessary to reduce the working pressure of the air. An air valve was used to control the pressure, but it was very sensitive to changes in air pressure, and operation of the shot blast machine was unstaSle. As a result, a reducing valve was placed between the oil moisture separator and the shot blast equipment. This made it possible to control the air pressure in the collector from 4.0 to 2.0 atm with an accuracy of 0.1 atrr. The use of this valve provides stable operation of the shot blast equipment.To blast rolls of different diameters it is necessary each time to change the position of the blast gun, which is not provided for in the design of the SM-2 machine. For example, at the present time to blast a 400 mm diameter roll after a 500 mm roll the machine must be shut down for adjustment. In designing new shot blast machines the possibility of changing the height of the gun must be specified.To observe the blasting process, special observation windows were cut in the long wal! of the lighted working chamber. Nonetheless, observation of the surface of the roll being blasted was difficult. Therefore, three additional 500 W lights, protected by louvers, were placed on the ceiling of the working chamber.Fig .3Control of the machine (Fig. 3) is from the control panel 2, the valve 5 at the air line, the rheostats for con. trolling the speed of rotation of the roll and the movement of the nozzles, and the push buon for starting up the exhaust fan motor, which is behind the machine.Such an arrangement of the SM-2 shot blast machine equipment is not convenient for control The rheostats for controlling the speeds do not have graduated scales, which makes choice of the correct speed difficuR. Actual: 15 for each new position of the control handle it is necessary to determine the speed. These disadvantages must be eliminated in the design of new machines, It is also necessary to improve removal of accumulated metal dust from the horizontal portion of the exhaust line, which is in a difficult to reach location about 4 m above the floor tevel.To provide more convenient placement of the individual units of the shot blast machine and simplify imaintenance, the Institute of Ferrous Metallurgy has developed and turned over to Zaporozhstal Plant recommendations which have been partially put into use on the existing machine and will be studied in designing similar new machines.The improvement in the SM-2 pneumatic shot blasting machine has made it easily possible to controt and maintain the specified sequence for blasting work rolls for cold rolling and skin pass sheet stands. As a result, Zaporozhstal Plant is mass producing cold roiled constructional sheet with a surface roughness meeting Ferrous Metallurgy Technical Specifications 1-683-69 and 1-686-69.7
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