国内汽车发动机缸体铸件铸造技术发展趋势 下载本文

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Pushing ahead, East, North, West development, facilitating shanty, complete xincheng West Road, stability and reconstruction of the street, Star Ding garden built century Garden District, subject public housing construction, heating the gas expansion accelerated implementation, Jing Rui River and bridge style line solid shaft, further expanded the town development. Beautiful country adhere to the advance and typical for a group to lead. According to \d, and industry increased income, and live upgrade civilization, and culture rich connotation\ht, caught built beautiful village, and whole village advance, and easily relocation, and \d three built\depth into ecological, and industry, and culture, and tourism, elements, high standards caught party original city Liu, and jade are Xia AO, model village, in province City set has benchmark. Four is equal benefits to promote sharing, coordinated development of various social undertakings. In the case of rigid spending slowing revenue growth, increase, financial 75% to the people's livelihood, the masses have more access in the sharing. Cuoban something good and benefit. Adhere to the affordable, best, carefully cuoban village oil, water and heat, cultural, city and County columns practical, developments benefit families, bring more welfare to the masses. Development of social convenience. Acceptance of balanced development of compulsory education through the national assessment, the County vocational education center was named \onal education in China\batch of national reform and development model through provincial ... Five is to deepen reform and innovation to break bottlenecks and endogenous development of effective fire. As an engine of dynamism, adding reform key to adopting reform measures stress energy and break bottlenecks and promoting development. Pay close attention to the key areas of reform. Conscientiously implement the provincial deployment and cancel, adjustment, to undertake the administrative approval items according to Regulation 347 to further improve administrative efficiency continuing deepening reform for poverty alleviation, speeding up rural land right registration certification pilot project, encouraging the orderly transfer of land management, utilize the land resources, in order to promote scale management laid the Foundation. Actively cultivate the market. Firmly establish a market-oriented, nurturing family farms, industrial users, professional cooperation organization new market management main body 456, effectively improve the industry, intensive and marketization of encouraging support social capital into the small micro-credit, urban development, culture and tourism, public services and other areas, easing development shortfall. To promote mass innovation. To support the rural sector to use new thinking and new ideas, creative work incentives such as actively promoting financial intermediation, bring added 159 in non public enterprises, individually-1540, created a国内汽车发动机缸体铸件铸造技术发展趋势 吴殿杰

(机械工业第九设计研究院有限公司)

提要:介绍了国内发动机缸体铸造工艺和生产设备情况,同时指出了缸体铸件的熔炼、造型、清理等铸造技术的发展方向,特别介绍了代表未来先进水平的铝镁合金压铸技术、计算机模拟技术和快速成形技术的研究应用情况。

关键词:汽车发动机;缸体;铸造技术;发展趋势;铸件 1国内车用发动机市场需求

我国汽车产业近年来发展迅速,主要汽车企业(集团)2011年年底形成整车产能1 841万辆,相应发动机产能已达到年产1 671万台。随着社会经济快速发展和人民生活水平不断提高,我国汽车国产化进程不断加快,汽车消费需求旺盛,汽车保有量保持快速增长趋势。2006年至2010年,汽车保有量年均增加951万辆;据分析,目前中国的汽车保有量为7 000多万辆,到2020年将达到2亿辆,也就是每年将净增1 300万辆,考虑到汽车报废等因素,每年净增量将在2 000万辆左右。巨大的汽车市场保有量,必将促进汽车发动机缸体市场的大发展,表1为2007~2020年国内汽车发动机缸体铸件生产及预测情况。 2国内发动机缸体铸件铸造工艺及生产设备 2.1熔化工艺和设备

缸体铸造所用的熔炼设备大多为冲天炉—中频感应炉双联熔炼,也有采用中频感应炉—中频感应炉双联熔炼,而使用变频感应炉作为保温炉的企业亦在不断增加。为了节能和环保,部分企业的冲天炉采用水冷热风除尘方式,用具有高发热值的铸造焦取代冶金焦,以提高铁液温度,保证铁液质量,增强熔化效率。一汽铸造公司的冲天炉熔化过程控制采用微机等集散式控制系统,冲天炉熔炼铁液的检测采用测温仪、碳当量检测仪和化学成分直读光谱仪等。 从掌握的汽车行业铸造厂资料来看,哈尔滨东安机械厂、上汽通用和安徽奇瑞等许多车间的熔化设备多数以中频炉为主。当然,熔化设备的选择主要考虑当地的能源供应状况;但从熔炼质量看,这些熔炼设备都能满足供货需求,与世界先进水平基本接近。随着工业废钢的生产量增加,国内已经采用以废钢增碳的熔化工艺来生产缸体等薄壁高强度合金铸铁件,这为提高铸件质量和稳定生产提供了可靠的保证。一汽铸造公司使用国产10 t中频熔化炉,采用废钢增碳熔化技术生产高强度灰铸铁,铸件各项指标均达到国际同类水平,抗拉强度达230-320 MPa,硬度达180-220 HB,内腔清洁度要求小于3 000 mg。

总之,国内熔化设备的水平不断提高,不论是冲天炉还是电炉,均已接近世界先进水平。关键的电器控制元件引进后,电炉产品的总体水平已满足生产要求,熔化效率都有提高,但在运行过程中仍会出现小问题,有待设备生产厂家进一步降低设备故障率。

目前,大批量流水线生产的汽车铸造行业采用大吨位中(变)频炉熔化也是一种趋势。如安徽芜湖奇瑞60万台发动机缸体铸造及原一汽大宇发动机有限公司铸铁厂(现为上海通用烟台动力)熔炼炉和保温炉全部采用美国应达8 t容量的中频炉和20 t容量的保温炉。近10年来,随着静态变频装置的发展,其效率和安全性能不断提高而投资呈逐年下降的趋势,使得铸造厂采用中频感应电炉来代替工频感应电炉熔炼铁合金和非铁合金变得越来越普遍。 目前,国内几乎停止制造工频坩埚式感应电炉。另外,采用高功率密度的中频感应电炉的熔化时间较工频炉大大缩短,常见配置见表2。 表2中(变)频电源与电炉的配置方式 2.2造型工艺和设备

缸体是发动机上最关键、最复杂的铸件,其壁厚最薄处往往不到3 mm,缸体铸件生产应用最广的仍然是湿型粘土砂,具有成型性能好、能耗低、噪音小、污染少、效率高、运行可靠

Pushing ahead, East, North, West development, facilitating shanty, complete xincheng West Road, stability and reconstruction of the street, Star Ding garden built century Garden District, subject public housing construction, heating the gas expansion ccelerated implementation, Jing Rui River and bridge style line solid shaft, further expanded the town development. Beautiful country adhere to the advance and typical for a group to lead. According to \d, and industry increased income, and live upgrade civilization, and culture rich connotation\ht, caught built beautiful village, and whole village advance, and easily relocation, and \d three built\depth into ecological, and industry, and culture, and tourism, elements, high standards caught party original city Liu, and jade are Xia AO, model village, in province City set has benchmark. Four is equal benefits to promote sharing, coordinated development of various social undertakings. In the case of rigid spending slowing revenue growth, increase, financial 75% to the people's livelihood, the masses have more access in the sharing. Cuoban something good and benefit. Adhere to the affordable, best, carefully cuoban village oil, water and heat, cultural, city and County columns practical, developments benefit families, bring more welfare to the masses. Development of social convenience. Acceptance of balanced development of compulsory education through the national assessment, the County vocational education center was named \onal education in China\batch of national reform and development model through provincial ... Five is to deepen reform and innovation to break bottlenecks and endogenous development of effective fire. As an engine of dynamism, adding reform key to adopting reform measures stress energy and break bottlenecks and promoting development. Pay close attention to the key areas of reform. Conscientiously implement the provincial deployment and cancel, adjustment, to undertake the administrative approval items according to Regulation 347 to further improve administrative efficiency continuing deepening reform for poverty alleviation, speeding up rural land right registration certification pilot project, encouraging the orderly transfer of land management, utilize the land resources, in order to promote scale management laid the Foundation. Actively cultivate the market. Firmly establish a market-oriented, nurturing family farms, industrial users, professional cooperation organization new market management main body 456, effectively improve the industry, intensive and marketization of encouraging support social capital into the small micro-credit, urban development, culture and tourism, public services and other areas, easing development shortfall. To promote mass innovation. To support the rural sector to use new thinking and new ideas, creative work incentives such as actively promoting financial intermediation, bring added 159 in non public enterprises, individually-1540, created a等优点的静压造型线及气冲造型线使用较为广泛。近年来,国内外造型线制造厂家对造型机的不断改进,先后已出现气冲加压实、气流增益气冲加压实、静压加压实、主动多触头压实、成型挤压等加砂方式,砂型硬度更加均匀化,成为缸体铸件生产首选的造型设备。另外,对于发动机缸体铸件年产量万台左右的厂家,如潍柴四川柴油机厂和康明斯四川五粮液等大中型柴油机缸体铸造企业,均采用pepset自硬砂工艺和三乙胺冷芯盒工艺,这也是节能低碳的最佳选择。 国内清华大学、济南铸锻所等早已研制静压造型线,苏州铸造机械厂和保定维尔的静压造型线以及无锡华佩线已有数条投入使用,但他们在整线性能和铸型质量一致性方面还显得不足。因此,国内汽车铸件生产所用造型线多以进口为主,济南铸造锻压机械研究所捷迈铸造工程公司为扬动股份有限公司提供了一条砂箱尺寸为1 000 mm×750 mm×320 mm的静压造型线,该线主机选用德国HWS公司的静压造型机,辅机由国内提供,是国内单主机布线生产率最高的造型线,代表了当今世界的最高造型技术水平。 气冲造型问世几十年,其技术发展也在不断提高和进步,与其它现代化湿型砂造型方法一样,都是追求提高砂型紧实的均匀性,从而保证砂型表面光洁,尺寸精确,内部致密。为保证这一点,国外近几年又有了新发展,见表3。 表3国外造型线发展趋势 2.3制芯工艺和设备

目前,国内汽车铸造厂缸体生产所用砂芯如水套砂芯、曲轴箱砂芯、缸筒与顶端砂芯、前后端面砂芯等依各厂条件不同,分别采用冷芯盒制芯、热芯盒制芯或覆膜壳芯制芯。冷芯盒工艺因其芯砂流动性、溃散性、生产率、节能和砂芯精度优于其它制芯工艺,在国内汽车发动机缸体铸造行业得到广泛应用。从今后趋势看,其应用范围将不断扩大。

另外,采用锁芯工艺,利用砂芯上开设的工艺孔,二次填砂固化,使多个砂芯组合为一个整体组合砂芯,然后整体涂料、烘干,这样铸件尺寸精度可大大提高,总体尺寸误差不超过0.3 mm。多数厂家采用计算机控制的“制芯中心”使全部制芯过程实现自动化。

制芯等设备主要有德国兰佩冷芯制芯机、西班牙洛拉门迪制芯中心、日本浪速等,国产热芯设备有单工位、两工位、四工位等,壳芯设备有K763/874壳芯机等,可满足复杂、薄壁、高精度铸件对砂芯质量的要求。 2.4砂处理工艺和设备 2.4.1粘土湿型砂处理

砂处理工艺对铸件产量和质量至关重要。在大批量流水线生产条件下,型砂周期循环使用,国内汽车行业都非常重视反复使用过程中型砂性能的变化规律,力求选择好的砂处理工艺流程,并采用逐级多点检测和自动控制。随着高压、气冲及静压造型工艺对型砂要求严格性的不断提高,相当多厂家进口了大容量高速混砂设备,如一汽二铸厂采用2套200t/h砂处理单元,分别都配有美国国家工程公司辛普森22G高效混砂机和连续双盘冷却器,整个系统配有各种检测仪器,通过中央控制室模拟控制;哈尔滨东安发动机公司和天津内燃机厂等引进日本新东公司SSD型砂处理系统,回砂采用测温加水(MIA)和测湿加水(MIC)装置以及型砂成型性控制仪,配以先进的检测系统,通过自动化监控向静压造型线提供合格的型砂;上海通用、烟台动力、安徽奇瑞等公司采用塔式结构的砂处理单元,使用国外公司的高效混砂机,旧砂冷却系统以及计算机控制系统,并将旧砂破碎、磁选、筛分、增湿冷却、辅料定量、混砂等工艺布置在24 m×24 m×25 m左右的空间内,这也是目前国外较先进的布置形式。

常州法迪尔克公司开发的MXC 30~120 t/h系列变频式冷却混砂机实现了混砂机创新性的突破,在沈阳华晨、常柴股份等20余家发动机铸造厂得到推广。其砂处理系统布置简单,减少了设备、厂房的基础投入;采用调速变频,降低能耗,型砂混制更均匀;充分发挥膨润土

Pushing ahead, East, North, West development, facilitating shanty, complete xincheng West Road, stability and reconstruction of the street, Star Ding garden built century Garden District, subject public housing construction, heating the gas expansion accelerated implementation, Jing Rui River and bridge style line solid shaft, further expanded the town development. Beautiful country adhere to the advance and typical for a group to lead. According to \d, and industry increased income, and live upgrade civilization, and culture rich connotation\ht, caught built beautiful village, and whole village advance, and easily relocation, and \d three built\depth into ecological, and industry, and culture, and tourism, elements, high standards caught party original city Liu, and jade are Xia AO, model village, in province City set has benchmark. Four is equal benefits to promote sharing, coordinated development of various social undertakings. In the case of rigid spending slowing revenue growth, increase, financial 75% to the people's livelihood, the masses have more access in the sharing. Cuoban something good and benefit. Adhere to the affordable, best, carefully cuoban village oil, water and heat, cultural, city and County columns practical, developments benefit families, bring more welfare to the masses. Development of social convenience. Acceptance of balanced development of compulsory education through the national assessment, the County vocational education center was named \onal education in China\batch of national reform and development model through provincial ... Five is to deepen reform and innovation to break bottlenecks and endogenous development of effective fire. As an engine of dynamism, adding reform key to adopting reform measures stress energy and break bottlenecks and promoting development. Pay close attention to the key areas of reform. Conscientiously implement the provincial deployment and cancel, adjustment, to undertake the administrative approval items according to Regulation 347 to further improve administrative efficiency continuing deepening reform for poverty alleviation, speeding up rural land right registration certification pilot project, encouraging the orderly transfer of land management, utilize the land resources, in order to promote scale management laid the Foundation. Actively cultivate the market. Firmly establish a market-oriented, nurturing family farms, industrial users, professional cooperation organization new market management main body 456, effectively improve the industry, intensive and marketization of encouraging support social capital into the small micro-credit, urban development, culture and tourism, public services and other areas, easing development shortfall. To promote mass innovation. To support the rural sector to use new thinking and new ideas, creative work incentives such as actively promoting financial intermediation, bring added 159 in non public enterprises, individually-1540, created a的效率,降低加入量,有效控制型砂温度。表4为部分铸造公司选用的砂处理设备参数。 表4部分铸造公司选用的砂处理设备参数

2.4.2粘土湿型砂旧砂(混合型旧砂)热法再生处理线 国内一些汽车发动机铸造厂由于使用砂芯数量较多,落砂时有大量溃散砂芯(这些砂芯几乎都是树脂砂芯)流入到旧砂中,使旧砂量远远超过砂系统的容纳量,迫使必须抛弃大量的旧砂以保持砂处理系统平衡,在所抛弃的旧砂中,不仅有芯头、清理的废砂以及除尘细粉,还有许多落砂时不易破碎的型砂块,形成混合型旧砂。如果把这种混合型旧砂作为废砂(废弃物)抛弃,不仅造成了资源浪费,而且废弃旧砂堆放既占场地,又污染环境,还需大量的运输费用。为减少这类混合型旧砂的产生,有的发动机缸体铸造厂采用热法再生:如哈尔滨东安汽车发动机公司引进意大利的热法再生设备已在生产中应用;一汽铸造公司引进日本热法再生和机械再生结合技术,处理芯砂和型、芯砂混合砂已在生产中得到应用。粘土湿型旧砂再生技术的应用近年来有了突破,实践证明湿型粘土旧砂经热法再生后的LOI值、热膨胀率、发气量、角形系数及灰分含量等指标都优于新砂。但就目前国内铸造行业现状而言,粘土湿型砂热法再生技术的推广仍不如预期的那么广泛,仅有宜宾五粮液康明斯发动机缸体铸造厂以及东风、一拖等大型铸造厂、长三角地区的吴江、昆山等地建有热法焙烧炉用于旧砂再生。 最近国外流行一种集铸造与热处理于一体,即落砂、再生和热处理三合一的工艺,国内已陆续有一些采用自硬砂工艺生产铝缸体的铸造厂在落砂清理工序中推广这种工艺。在焙烧炉中,砂型和砂芯的树脂粘结剂所含有的许多能量在与炉中高温及富氧气氛接触燃烧后会被释放,而伴随着粘结剂的燃烧,砂型和砂芯中的型砂就会散落下来。炉顶安装的轴流风扇产生的高速气流向下吹向缸体铸件,将散落的型砂带向炉底。高速气流流过不规则形状的缸体铸件会产生压差,这种压差引起铸件内部和外部的气流扰动,从而将松动的型砂带走。与此同时,高速风扇也使炉内气流分布达到最佳状态,从而使炉内温差保持在很小的范围内。铸件从清洁铸造三合一系统出来后,在完成了固溶热处理的同时,型砂和芯砂都已去除干净。型(芯)砂在漏斗形炉底上被收集在一起。炉底装有流态床,用于对型(芯)砂进行最后清理。粘结剂残留的微粒被分离并被排放。型(芯)砂在炉内被完全再生,经过气力输送到造型、制芯工部。炉内废气集中排放,通过旋风分离器、灼烧器、换热器,最后经过袋式过滤除尘器,清洁后的气体才被排放到大气。

总之,新建铸造工厂必须考虑旧砂再生处理;对已建成投产的铸造工厂,可增加旧砂再生,或将旧砂集中到就近专业处理工厂再生后使用。这已经是一种发展趋势,是国家节能减排、可持续发展的需要。 2.5清理工艺和设备

目前,缸体铸件经去除浇冒口后,在清理线上打磨外表面,然后进入鼠笼式抛丸室清理,已是一种常规工艺。生产多品种缸体时,部分厂家采用夹持式高效抛丸清理机进行抛丸。普遍采用各种自动化和机械化专用清理线和高效缸体鼠笼抛丸机以及机械手对缸体进行整体清理,然后用手工对缸体逐个精整及吹净水套内腔残留物。经尺寸检查,气密性试验,铣加工定位点及终检后,进行涂漆或其它防锈处理,成为合格缸体铸件。 以钢丸代替铁丸进行抛丸清理,采用机器人分拣缸体铸件,采用浇冒口去除机去除浇冒口以及采用X射线和超声波探伤仪检验内部缺陷等方法已为越来越多的厂家采用。 天津丰田等铸造厂都对金属炉料进行抛丸、破碎、净化和称量,以提高熔化效率和铁液质量。表5为国内现有抛丸清理设备的主要技术参数。 2.6检测技术和装备

国内大批量生产发动机铸件的厂家都拥有先进的检测仪器和严格的质量保证体系。一般都采用先进的直读光谱仪和红外碳硫仪进行成分检测与控制,利用先进的电子金相显微镜进行精确的金相组织分析,先进的电子拉力试验机可以进行各种金属材料的拉伸、压缩、弯曲等试