“鏈片沖孔落料復(fù)合?!蓖拱寄A慵臋C(jī)械加工工藝過(guò)程及工藝裝備的設(shè)計(jì)
“鏈片沖孔落料復(fù)合模”凸凹模零件的機(jī)械加工工藝過(guò)程及工藝裝備的設(shè)計(jì),沖孔,復(fù)合,凸凹,零件,機(jī)械,加工,工藝,過(guò)程,進(jìn)程,裝備,設(shè)備,設(shè)計(jì)
附錄1 軸加工工藝
軸加工工藝
摘要:軸類零件是機(jī)器中的主要零件之一,它通常被用于支撐傳動(dòng)件的傳遞扭矩。軸是旋轉(zhuǎn)體零件,其長(zhǎng)度大于直徑。加工表面通常由內(nèi)外圓柱面、圓錐面、螺紋、花鍵、橫孔、溝槽等。
關(guān)鍵字:軸,精度,基準(zhǔn)
軸類零件的技術(shù)要求:
以圖所示的軸為例
(1)尺寸精度和形狀精度
軸屬于精度較高的零件,其軸頸的尺寸精度達(dá)IT5~I(xiàn)T6,支承軸頸的形狀精度會(huì)直接影響軸的旋轉(zhuǎn)精度,所以要求圓度0.005mm。其余表面的尺寸精度一般為IT6~I(xiàn)T9,形狀精度低于支承軸頸,或限制在尺寸公差范
圍內(nèi)。
(2)位置精度
保證配合軸頸相對(duì)支承軸頸的同軸度,是軸類零件位置精度的普遍要求。為便于檢驗(yàn),常采用圓跳動(dòng)公差,它既包含被測(cè)要素與基準(zhǔn)要素的位置誤差,也包含被測(cè)要素本身的形狀誤差。
(3)表面粗糙度
支承軸頸和重要工作表面的粗糙度要求最高,達(dá)Ra0.8~0.4μm,配合軸頸和其他重要表面一般為Ra1.6~0.8μm。
軸類零件的材料、毛坯及熱處理
(1)軸類零件的材料
一般軸類零件常用45鋼,并根據(jù)不同的工作條件采用不同的熱處理,以獲得一定的強(qiáng)度、韌性、和耐磨性。45鋼的缺點(diǎn)是淬透性較差,淬火后易形成較大的內(nèi)應(yīng)力。對(duì)于中等精度且轉(zhuǎn)速較高的軸,可選用40Cr等合金結(jié)構(gòu)鋼。這類鋼淬火時(shí)擁有冷卻,熱處理后的內(nèi)應(yīng)力小,并且有良好的韌性。精度較高的軸,可選用軸承鋼GCr15和彈簧鋼65Mn等,這類材料經(jīng)調(diào)制和表面處理后,具有較高的耐磨性和疲勞強(qiáng)度;缺點(diǎn)是韌性較差。
(2)軸類零件的毛坯
軸類零件最常用的毛坯是圓棒料和鍛件。采用圓棒料時(shí),毛坯的準(zhǔn)備工作簡(jiǎn)單,但只適用于截面差異不大及力學(xué)性能要求不高的軸。坯料在經(jīng)過(guò)鍛壓后,金屬的組織致密、均勻,并且形成沿表面呈流線型的內(nèi)部纖維組織,能有效提高零件的多向力學(xué)性能。對(duì)于中、小批量生產(chǎn)或結(jié)構(gòu)不太復(fù)雜的軸,一般都采用自由鍛造。大批量生產(chǎn)時(shí),采用模型鍛造機(jī)和提高生產(chǎn)率,又可大大減少加工余量,以節(jié)省材料和減少后續(xù)加工。但當(dāng)工件尺寸和質(zhì)量較大時(shí),由于模鍛設(shè)備的局限性而無(wú)法采用模鍛,所以大型且結(jié)構(gòu)復(fù)雜的軸,其毛坯制造存在一些難題。若采用鍛造,則強(qiáng)度和韌性不足。
(3)軸類零件的熱處理
軸類零件的熱處理取決于軸的材料、毛坯形式、性能和精度要求等。軸的鍛造毛坯在機(jī)械加工之前,均需進(jìn)行正火或退火(高碳鋼和高碳合金鋼)處理,以使鋼的晶粒細(xì)化(球化),消除鍛造后的內(nèi)應(yīng)力。降低毛坯的硬度,改善切削加工性能。
調(diào)制是軸類零件最常用的熱處理工藝,調(diào)質(zhì)即可獲得良好的綜合力學(xué)性能,又作為后續(xù)將近行的各種表面熱處理的預(yù)備熱處理。調(diào)質(zhì)處理一般安排在粗加工后、精加工之前。一方面為消除粗加工所產(chǎn)生的殘余內(nèi)應(yīng)力,產(chǎn)生的變形可由后續(xù)的半精加工、精加工切除;另一方面經(jīng)調(diào)質(zhì)后的工件硬度比較適合于半精加工。對(duì)于加工余量很小的軸,調(diào)質(zhì)也可安排在粗加工之前。
局部淬火、表面淬火、及滲碳淬火的熱處理一般安排在半精加工之后、精加工之前。淬硬后的工作便面不宜用刀具進(jìn)行切削,而要由磨削來(lái)達(dá)到最終要求的尺寸精度和表面粗糙度,并可糾正經(jīng)淬火后產(chǎn)生的少量變形。對(duì)于精度較高的軸,在局部淬火或粗磨后,為了保持加工后尺寸的穩(wěn)定,需進(jìn)行低溫時(shí)效處理,以消除磨削所產(chǎn)生的內(nèi)應(yīng)力、淬火內(nèi)應(yīng)力和繼續(xù)產(chǎn)生內(nèi)應(yīng)力的殘余奧氏體。
軸的加工工藝分析
1)主軸的加工工藝過(guò)程
序號(hào)
工序名稱
工序內(nèi)容(工序簡(jiǎn)圖或說(shuō)明)
設(shè)備
1
備料
2
鍛造
自由鍛
3
熱處理
退火
4
鋸頭
保持總長(zhǎng)386±1.5mm
5
銑鉆
同時(shí)銑兩端面、鉆兩端中心孔(外圓柱定位)
專用機(jī)床
6
粗車
車各外圓(中心孔定位)
臥式車床
7
熱處理
調(diào)質(zhì)
8
精車
車各外圓(中心孔定位)
數(shù)控車床
9
銑
銑鍵槽 外圓定位
立式銑床
10
磨外圓
磨各外圓柱面至尺寸(中心孔定位)
外圓磨床
11
檢驗(yàn)
2)工藝過(guò)程分析
(1)加工階段的劃分
從上表觀察軸的整個(gè)加工工藝過(guò)程,可分為四個(gè)階段:工序1~4為毛坯準(zhǔn)備階段;5~7為粗加工階段;8~9為半精加工階段;最后是精加工階段。
(2)定位基準(zhǔn)的選擇與轉(zhuǎn)換
軸類零件的定位基準(zhǔn),最常用的是兩中心孔。因?yàn)檩S類零件各外圓表面、錐孔、螺紋表面的同軸度,以及端面對(duì)回轉(zhuǎn)軸線的垂直度,均與主軸的軸線有關(guān),若以兩中心孔定位,就能符合基準(zhǔn)統(tǒng)一的原則,能夠最大限度地在一次裝夾中加工多出表面。因此,只要有可能,總是盡量采用中心孔作為定位基準(zhǔn)。
(3)加工順序的安排
在安排軸的加工工序時(shí),總體上,已外圓和錐孔作為主要表面,按各加工價(jià)段“先粗后精”,逐步達(dá)到零件所要求的精度。
①“基準(zhǔn)先行”原則。首道機(jī)械加工工序是加工中心孔,為粗車工序準(zhǔn)備好基準(zhǔn);在以后的工序中,一個(gè)工序的加工內(nèi)容與下一工序的基準(zhǔn)一環(huán)扣一環(huán),協(xié)調(diào)安排。
②先大端后小端。安排外圓各表面的加工工序時(shí),一般先加工大端外圓,再加工小端外圓,則會(huì)在加工一開(kāi)始就降低工件的剛度。
③次要表面加工安排。軸上的鍵槽、花鍵、螺紋、橫向小孔等雖然都屬于次要表面,但這些表面往往與軸外圓有一定的位置公差要求,需要較精確的精基準(zhǔn),所以一般都安排在外圓的精車或粗磨之后加工。這是因?yàn)槿绻诰嚽熬豌姵鲦I槽和鉆出橫孔,精車時(shí)因斷續(xù)切削而產(chǎn)生振動(dòng),既影響加工質(zhì)量,又容易損壞刀具。另一方面,鍵槽的深度也難以控制。但是這些加工也不宜放在主要表面精磨之后,以免破壞主要表面已獲得的深度。
附錄2
快速原型技術(shù)及在模具制造中的應(yīng)用
摘要:論述了快速原型技術(shù)的工藝原理、加工特點(diǎn)、形成與發(fā)展概況以及在模具制造中的應(yīng)用,指出該項(xiàng)技術(shù)可構(gòu)成一種應(yīng)用范圍十分廣泛、新穎的加工體系,市場(chǎng)前景廣闊。
關(guān)鍵詞:快速原型技術(shù) 模具制造 產(chǎn)品開(kāi)發(fā)
快速原型技術(shù)是一種涉及多學(xué)科的新型綜合制造技術(shù)。80年代后,隨著計(jì)算機(jī)輔助設(shè)計(jì)的應(yīng)用,產(chǎn)品造型和設(shè)計(jì)能力得到極大提高,然而在產(chǎn)品設(shè)計(jì)完成后,批量生產(chǎn)前,必須制出樣品以表達(dá)設(shè)計(jì)構(gòu)想,快速獲取產(chǎn)品設(shè)計(jì)的反饋信息,并對(duì)產(chǎn)品設(shè)計(jì)的可行性作出評(píng)估、論證。在市場(chǎng)競(jìng)爭(zhēng)日趨激烈的今天,時(shí)間就是效益。為了提高產(chǎn)品市場(chǎng)競(jìng)爭(zhēng)力,從產(chǎn)品開(kāi)發(fā)到批量投產(chǎn)的整個(gè)過(guò)程都迫切要求降低成本和提高速度??焖僭图夹g(shù)的出現(xiàn),為這一問(wèn)題的解決提供了有效途徑,倍受國(guó)內(nèi)外重視。
1 快速原型技術(shù)的基本原理
快速原型技術(shù)是用離散分層的原理制作產(chǎn)品原型的總稱,其原理為:產(chǎn)品三維CAD模型→分層離散→按離散后的平面幾何信息逐層加工堆積原材料→生成實(shí)體模型。
該技術(shù)集計(jì)算機(jī)技術(shù)、激光加工技術(shù)、新型材料技術(shù)于一體,依靠CAD軟件,在計(jì)算機(jī)中建立三維實(shí)體模型,并將其切分成一系列平面幾何信息,以此控制激光束的掃描方向和速度,采用粘結(jié)、熔結(jié)、聚合或化學(xué)反應(yīng)等手段逐層有選擇地加工原材料,從而快速堆積制作出產(chǎn)品實(shí)體模型。
2 快速原型技術(shù)的加工特點(diǎn)
快速原型技術(shù)突破了“毛坯→切削加工→成品”的傳統(tǒng)的零件加工模式,開(kāi)創(chuàng)了不用刀具制作零件的先河,是一種前所未有的薄層迭加的加工方法。與傳統(tǒng)的切削加工方法相比,快速原型加工具有以下優(yōu)點(diǎn):
(1)可迅速制造出自由曲面和更為復(fù)雜形態(tài)的零件,如零件中的凹槽、凸肩和空心部分等,大大降低了新產(chǎn)品的開(kāi)發(fā)成本和開(kāi)發(fā)周期。
(2)屬非接觸加工,不需要機(jī)床切削加工所必需的刀具和夾具,無(wú)刀具磨損和切削力影響。
(3)無(wú)振動(dòng)、噪聲和切削廢料。
(4)可實(shí)現(xiàn)夜間完全自動(dòng)化生產(chǎn)。
(5)加工效率高,能快速制作出產(chǎn)品實(shí)體模型及模具。
下表為快速原型技術(shù)與傳統(tǒng)切削方法的比較。
快速原型技術(shù)與傳統(tǒng)切削方法比較表
3 快速原型技術(shù)的發(fā)展
快速原型技術(shù)概念即RP(Rapid Prototyping Technology)概念的提出可追朔到1979年,日本東京大學(xué)生產(chǎn)技術(shù)研究所的中川威雄教授發(fā)明了疊層模型造型法,1980年小玉秀男又提出了光造型法,該設(shè)想提出后,由丸谷洋二于1984年繼續(xù)研究,并于1987年進(jìn)行產(chǎn)品試制。
1988年,美國(guó)3D Systems公司率先推出快速原型實(shí)用裝置—激光立體造型即SLA(Stereo Lightgraphy Apparatus),并以年銷售增長(zhǎng)率為30%~40%的增幅在世界市場(chǎng)出售。近年來(lái),隨著掃描振鏡性能的提高,以及材料科學(xué)和計(jì)算機(jī)技術(shù)的發(fā)展,快速原型技術(shù)已日趨成熟,并于1994年正式進(jìn)入推廣普及階段。 按照所用材料的形態(tài)與種類不同,快速原型技術(shù)目前有以下四種類型。
3.1 利用激光固化樹脂材料的光造型法
光造型裝置一直以美國(guó)3D Systems公司的SLA型產(chǎn)品獨(dú)占鰲頭,并形成壟斷市場(chǎng)。其工作原理如圖1所示。由激光器發(fā)出的紫外光,經(jīng)光學(xué)系統(tǒng)匯集成一支細(xì)光束,該光束在計(jì)算機(jī)控制下,有選擇的掃描液激光器掃描鏡升降裝置容器光敏樹脂體光敏樹脂表面,利用光敏樹脂遇紫外光凝固的機(jī)理,一層一層固化光敏樹脂,每固化一層后,工作臺(tái)下降一精確距離,并按新一層表面幾何信息使激光掃描器對(duì)液面進(jìn)行掃描,使新一層樹脂固化并緊緊粘在前一層已固化的樹脂上,如此反復(fù),直至制作生成一零件實(shí)體模型。激光立體造型制造精度目前可達(dá)±0.1mm,主要用作為產(chǎn)品提供樣品和實(shí)驗(yàn)?zāi)P?。此外,日本帝人制機(jī)開(kāi)發(fā)的SOLIFORM可直接制作注射成型模具和真空注塑模具
圖1 立體光造型技術(shù)原理圖
3.2 紙張疊層造型法
紙張疊層造型法目前以Helisys公司開(kāi)發(fā)的LOM裝置應(yīng)用最廣。該裝置采用專用滾筒紙,由加熱輥筒使紙張加熱聯(lián)接,然后用激光將紙切斷,待加熱輥筒自動(dòng)離開(kāi)后,再由激光將紙張裁切成層面要求形狀,如圖2所示。
圖2 紙張疊層造型原理圖
LOM可制作一些光造型法難以制作的大型零件和厚壁樣件,且制作成本低廉(約為光造型法的1/2)、速度高(約為木模制作時(shí)間的1/5以下),并可簡(jiǎn)便地分析設(shè)計(jì)構(gòu)思和功能。
3.3 熔融造型法
熔融造型法以美國(guó)Stratasys公司開(kāi)發(fā)的產(chǎn)品FDM(Fused Deposition Modelling)應(yīng)用最為廣泛。工作時(shí),直接由計(jì)算機(jī)控制噴頭擠出熱塑材料并按照層面幾何信息逐層由下而上制作出實(shí)體模型。FDM技術(shù)的最大特點(diǎn)是速度快(一般模型僅需幾小時(shí)即可成型)、無(wú)污染,在原型開(kāi)發(fā)和精鑄蠟?zāi)5确矫娴玫綇V泛應(yīng)用。
3.4 熱可塑造型法
熱可塑造型法以DTM公司開(kāi)發(fā)的選擇性激光燒結(jié)即SLS(Selective Laser Sintering)應(yīng)用較多。該方法是用CO2激光熔融燒結(jié)樹脂粉末的方式制作樣件。工作時(shí),由CO2激光器發(fā)出的光束在計(jì)算機(jī)控制下,根據(jù)幾何形體各層橫截面的幾何信息對(duì)材料粉末進(jìn)行掃描,激光掃描處粉末熔化并凝固在一起。然后,鋪上一層新粉末,再用激光掃描燒結(jié),如此反復(fù),直至制成所需樣件。如圖3所示。
圖3 選擇性激光燒結(jié)原理圖
SLS技術(shù)造型速度快(一般制品,僅需1天~2天即可完成)、造型精度高(每層粉末最小厚度約0.07mm,激光動(dòng)態(tài)精度可達(dá)±0.09mm,并具有自動(dòng)激光補(bǔ)償功能)、原型強(qiáng)度高(聚碳酸脂其彎曲強(qiáng)度可達(dá)34.5MPa,尼龍可達(dá)55MPa),因此,可用原型進(jìn)行功能試驗(yàn)和裝配模擬,以獲取最佳曲面和觀察配合狀況。
在快速原型技術(shù)的開(kāi)發(fā)應(yīng)用方面,美國(guó)和日本走在前列。近年來(lái),我國(guó)快速原型技術(shù)的發(fā)展已十分迅速。華中理工大學(xué)在1994年開(kāi)發(fā)研制成功兩種快速成型系統(tǒng)樣機(jī)HRP和RPS,目前已進(jìn)入商品市場(chǎng),廣泛應(yīng)用于汽車、玩具、航空航天、造船、軍工等行業(yè)。
4 快速原型技術(shù)在模具制造中的應(yīng)用
4.1 快速制模鑄造
將需鑄零件的CAD模型轉(zhuǎn)換為快速模殼制造,按模殼每層截面的幾何形狀生成陶瓷模殼然后按快速熔模鑄造方法即可快速制造金屬零件。此外,可將快速原型技術(shù)制作生成的樣件作為鑄造模具的原模,實(shí)現(xiàn)零件的快速鑄造,其過(guò)程為:零件CAD三維設(shè)計(jì)→計(jì)算流體動(dòng)力學(xué)分析(CFD)→LOM模型制造→熔模鑄造金屬零件。
4.2 快速模具制造
傳統(tǒng)的模具制造方法周期長(zhǎng)、成本高,一套簡(jiǎn)單的塑料注塑模具其價(jià)值也在10萬(wàn)元以上。設(shè)計(jì)上的任何失誤反映到模具上都會(huì)造成不可挽回的損失??焖僭图夹g(shù)可精確制作模具的型心和型腔,也可直接用于注射過(guò)程制作塑料樣件,以便發(fā)現(xiàn)和糾正出現(xiàn)的錯(cuò)誤。
美國(guó)愛(ài)達(dá)荷國(guó)家工程與環(huán)境試驗(yàn)中心采用快速凝固工藝即RSP技術(shù)實(shí)現(xiàn)了注塑模具的快速經(jīng)濟(jì)制造。該方法采用快速原型技術(shù)制作的樣件作為母體樣板,通過(guò)噴涂到母體樣板的金屬或合金熔滴的沉積制造模具。其工藝過(guò)程為:熔融的工具鋼或其它合金被壓入噴嘴,與高速流動(dòng)的隋性氣體相遇而形成直徑約0.05mm的霧狀熔滴,噴向并沉積到母體樣板上,復(fù)制出母樣的表面結(jié)構(gòu)形狀,借助脫模劑使沉積形成的鋼制模具與母樣分離,即可制出所需模具。
母樣使用的材料取決于噴涂其上的合金材料。對(duì)于噴涂工具鋼來(lái)說(shuō),可選用陶瓷材料,類似材料還有鋁氧粉和氧化鋯可供選擇。該方法制作精度高(噴涂工具鋼時(shí)最小表面涂層可達(dá)0.038mm,制造精度可達(dá)±0.025mm~±0.05mm)、時(shí)間短(普通模具一周之內(nèi)即可成型)、造價(jià)低(一般為傳統(tǒng)模具制造費(fèi)用的1/2~1/10)。
4.3 快速鑄造模具
以聚碳酸脂為材料,用SLS快速制出母型,并在母體表面制出陶瓷殼型,焙燒后用鋁或工具鋼在殼內(nèi)進(jìn)行鑄造,即得到模具的型心和型腔。該方法制作周期不超過(guò)4周,制造的模具可生產(chǎn)250000個(gè)塑料制品。
5 結(jié)論
綜上所述,RP是一種正在進(jìn)一步發(fā)展和完善且已獲得了廣泛應(yīng)用的高技術(shù)??梢灶A(yù)見(jiàn),隨著CAD的廣泛應(yīng)用、市場(chǎng)競(jìng)爭(zhēng)日趨激烈、快速造型技術(shù)本身和快速模具制造成套技術(shù)的完善,快速成形技術(shù)將發(fā)展為一種能被企業(yè)普遍采用的技術(shù)手段,并將給企業(yè)帶來(lái)巨大的經(jīng)濟(jì)效益,這應(yīng)引起各方面的高度重視。
附錄3
The Rapid Prototyping Manufacturing and its application in molding manufacturing
Abstract: By discussing the rapid prototyping technology the craft principle, characteristic of the processes, formation and the general situation of the develop of fast prototype and its application in molding, point out the technique can form a kind of a process system of extensive application and novel, and its foreground is vast.
Key Words: rapid prototyping technology; molding manufacturing; development of product
Rapid prototyping technology is a new type of multidisciplinary integrated manufacturing technology. After the 1980s, following the application of computer-aided design, product shape and design capabilities have greatly improved, however, product design has completed, production, a system must be designed to convey the concept of samples, rapid feedback to product design, product design and assess the feasibility, and feasibility studies. The increasingly fierce competition in the market today, the time is effective. To enhance the competitiveness of products, from product development to volume production of the whole process are urgently required to reduce costs and increase speed. Rapid prototype technology appearance provides an effective solution to this problem which much attention at home and abroad.
1. The basic principle of Rapid Prototyping Technology
The RP is the generic name of the principle creation product prototype that uses the long-lost layering, its principle is: Produce CAD modelà Stratified separated àaccording to the plan geometry information which is dispersed to pile up the original materialà generating entity models.
This technology integrates of computer technology, laser processing technology, new material technology, relying on CAD software in the creation of 3D computer models entities, and is divided into a series of plane geometry information to control the scanning laser beam direction and speed, using sinter, pooling or chemical reaction means exhaustive selective processing of raw materials, thus rapid accumulation manufacture products entities models.
2. The characteristics of Rapid Prototyping Technology
Rapid Prototyping Technology breaks the traditional way to produce spare parts of “roughcast àslice to pare to processàfinished”, Needless cutlery created the first production of spare parts, is an unprecedented lamina reducing processing methods. Comparing to tradition, the fast prototype processes the following advantage:
(1) Produce the spare parts of the curved face and more complicated appearance quickly, such as shoulder within spare parts and hollow and parts of etc.s, consumedly lowered the development cost of the new product and development period.
(2) Is a non-contact processing, machine tool cutting processing is necessary cutlery and jig without cutlery wear and cutting force.
(3) Without vibration, noise and slice to pare the waste.
(4) Can carry out the nighttime over full-automatic production.
(5) Process with high efficiency, produces the article entity model and molding tools quickly.
The form follows the comparison of the method for the Rapid Prototyping Technology and tradition.
Comparison the item
Processing technology
The tool machine slices to pare to process
RP(Light shape method)process
The method of process
Do away with the surplus material process
Fold the layer process
The object of process
Solid
Liquid, portrait, powder
Tool
The tool of slice to pare
Light beam
Minimum processing units
Dot’s diameter is about 1μms
Triangles of 200μms long
Production of spare parts
The least processes come together the body of the unit
The least processes come together the body of the unit
The RP and traditions slice to pare the method comparison sheet
3. The develop of RP
Rapid prototyping technology concept that the concept RP (Rapid Prototyping Technology) could be back to 1979. the profess of Zhong Chuan Weixiong in produce and technique institute of Japanese University of Tokyo invent the method of fold the layer model, the Xiao Yu Xiunan put forward the light shape method again in 1980, after the conceive put forward, it was continued to study in 1984 by Wan Gu Yanger, and carried on to produce manufacture on a trial basis in 1987.
1988, the United States rapidly prototype 3D Systems Corporation was the first to introduce practical devices-laser three-dimensional shapes that SLA (Stereo Lightgraphy Apparatus), and annual sales growth rate 30%~40% increase in the world market. In recent years, with increasing performance scanning-a mirror, and the development of materials science and computer technology, rapid prototyping technology matures, and in 1994 to promote universal access to the formal stage. In accordance with the patterns and materials used in the different types of rapid prototyping technology currently has the following four types.
3.1 Solidification resin materials using laser light shapes law
The light shape equipment is excellent with a product of the 3D Systems company of the United States, and the formation of a monopoly. Figure 1 shows the operating principles. Issued by the laser light, the optical system to compile into a small beam, the beam in the computer controlled, selective scanning resin surface, using an ultraviolet resin Frozen mechanisms, a layer of solidification resin, each layer of solidification, precision workstations in a distance with the new layer of surface geometric information to the laser scanner for scanning reading, solidification of the new layer of resin and firmly stick to the previous layer has solidification resin, so repeatedly until the production of spare parts entities generated a model. The laser stereoscopic shape manufacturing accuracy can reach the ±0.1 mms, mainly used to provide the sample and the experiment models for the product. In addition, the SOLIFORM of the Japanese system machine developed can manufacture to inject to model the molding tool and vacuum molding tools directly.
Figure 1 Stereoscopic light shape technique principle diagram
3.2The paper folds the layer shape method
The paper folds the LOM that the layer shape method develops with the Helisys company currently applicant most widely. The devices used for roller paper from the paper heating roller cylinders connectivity, and then using the laser to cut paper, the question heating roller cylinders automatically leave, the paper will be ready by laser level requirements into shape, as shown in figure 2.
Figure 2 Principle diagram of the paper folds the layer shape
The LOM can manufacture some large spare parts and the thick wall kind pieces of the hard creation with lights shape method and create cost is cheap (about for the light shape method of 1/2), the speed is high (about manufacture time for the wood mold of below 1/5), and can simply analytic the design conceive outline and function.
3.3 meltdown shape methods
The meltdown shape method is most extensive used with the product FDM which is developed in American Stratasys,(the Fused Deposition Modeling), when it is working, the plastics material with hot extrusion sprayed directly by sprinkler head controlled by computer combine to layer to create an entity model from bottom to top according to several information of level. The biggest characteristics in FDM technical is a quick(general the model need several hours and can immediately model) and free from pollution, to get the extensive application in prototype, develop and cast wax mole and so on.
3.4 hot and fictile shape methods
The hot and fictile shape method burns the knot with the selectivity laser of the DTM company development namely the SLS (the Selective Laser Sintering) application is the most. That method is a way manufacture kind piece that burns with the CO2 laser machine controls by the calculator, carry on scanning on the material powder according to several information for faces of several pieces with horizontal each layer of the body, the powder is scanning by laser and solidify together. Then, spread up a new powder of layer, then scan to burn the knot with the laser, thus again and again, keep to go to make the kind piece which needed. As figure 3 shows.
Figure 3 The principle chart of selectivity laser sintering
The SLS technique shape speed is fast(general ware, need one or two days to complete), the shape accuracy is high(the minimum thickness of each layer powder is about 0.07 mms, the laser dynamic state accuracy can reach the ±0.09 mms, and have the automatic laser repair function), the prototype strength is high(gather its bent strength of the carbonic acid fat and can amount to the 34.5MPa,the nylon can reach 55MPa), therefore, can carry on function’s experiment and assemble the emulation with the prototype, to obtain the best curved face to match with the observation the condition.
Develop and applied aspect technically in RP, the United States and Japans are the best. In Huazhong University develops two kinds of model system machine HRP and RPSs which is research to manufacture in 1994 successful quickly, have already entered the commodity market currently, be applied in the professions extensively, such as automobile, toy, aviation aerospace, shipbuilding and the soldier work etc.
4. The application of the RP in molding manufacture
4.1 Making the mold foundry fast
Put the spare part CAD model converse to fast method, produce metal spare parts quickly according to each layer shape of face to for ceramic mold and then accord to fast method. In addition, can carry out the original mold that the fast prototype technique manufactures a conduct and actions founder molding tool, spare parts of fast cast, its process is: Design the spare parts CAD 3D àthe calculation hydrodynamics analysis(CFD)àthe LOM model manufacturingàcast the metals spare parts.
4.2 fast molding tool manufacturing
The traditional molding tool manufacturing method period is long, the cost is high, a set of simple plastics molding tool is worth above 100,000 dollars. Any error of design reflects the molding tool make the loss that can’t be retrieved. Fast prototype technique can a heart and bodies of the accurate manufacture molding tool, also can used for injecting process to produce manufacture plastics piece directly, for the purpose of detection and the mistake that rectify to appear.
The center of national engineering in American Idaho and environments experiment adopt the fast concretion craft namely the technique of RSP carried out the fast and economy of the plastics molding manufacture. That method adopt fast prototype technique produce sample to be sample product sink to accumulate to make the mold. The craft process is steel or tool used for other alloys of the meltdown were pressed to go in to the mouth of spray meet high speed Sui air to form fog of liquid which diameter about 0.05mms, spay to maternal sample and sink to accumulate on it, make duplicate the surface structure shape of maternal sample, with the help of chemical to separate the steel mold which was sink to accumulated and maternal sample, then produce the mold needed.
The material of maternal sample decided by the alloy material which was spray on it. For the spray stool steel, can chose ceramic materials, still have similar material as Aluminum Oxygen powder and provided as choice. That method manufacture accuracy is high (when spray to draw the tool steel, the minimum layer and can amount to the 0.038mms, manufacture accuracy can reach the ±0.025mms~±0.05mms),time is short (common molding tool can be modeled in a week ) the price is low.(General is 1/2~1/10 of the traditional molding tool manufacture).
4.3 Fast cast molding
The carbonic as the material, use the SLS to make a female type quickly, and in the maternal surface produce the shape of ceramics hull, use the aluminum or the tool steels to carry on the foundry in the hull after baking to burn, then get the inner part and the shape of the molding tool. That method manufacture period not over 4 weeks, the molding tool of the manufacturing can produce 250000 plastics wares.
5 Conclusion
Based on the above, the RP is a further development and refinement technology which has been extensive and high-tech applications. It can be predicted that along with the wider using of CAD, the increasingly fierce market competition, rapid shaped mould manufacturing technology itself and the rapid improvement of technology packages, will be developed rapidly emerging technology enterprises to be a common technical means, and bring huge economic benefits to the enterprise, which should have aroused great attention.
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