【正文】 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。 36 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。 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(shù)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 ,激光動(dòng)態(tài)精度可達(dá) 177。, 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) ,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 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 37 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。 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。快速原型技術(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 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) ,制造精度可達(dá) 177。 ～177。 ）、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）。 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 38 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: r ag an employment tribunal clai Emloyment tribunals sort out disagreements between employers and employees. You may need to make a claim to an employment tribunal if: you don39。t agree with the disciplinary action your employer has taken against you your employer dismisses you and you think that you have been dismissed unfairly. For more informu, take advice from one of the anisations listed under Further help. Employment tribunals are less formal than some other courts, but it is still a legal process and you will need to give evidence under an oath or affirmation. Most people find making a claim to an employment tribunal challenging. If you are thinking about making a claim to an employment tribunal, you should get help straight away from one of the anisations listed under Further help. ation about dismissal and unfair dismissal, see Dismissal. You can make a claim to an employment tribunal, even if you haven39。t appealed against the disciplinary action your employer has taken against you. However, if you win your case, the tribunal may reduce any pensation awarded to you as a result of your failure to appeal. Remember that in most cases you must make an application to an employment tribunal within three months of the date when the event you are plaining about happened. If your application is received after this time limit, the tribunal will not usually accept i. If you are worried about how the time limits apply to you If you are being represented by a solicitor at the tribunal, they may ask you to sign an agreement where you pay their fee out of your pensation if you win the case. This is known as a damagesbased agreement. In England and Wales, your solicitor can39。t charge you more than 35% of your pensation if you win the case. you39。re clear about the terms of the agreement. It might be best to get advice from an experienced adviser, for example, at a Citizens Advice Bureau. To find your nearest CAB, including those that give advice by , click on nearest CAB. For more information about making a claim to an employment tribunal, see Employment tribunals. The (lack of) air up there Cay man Islandsbased Webb, Watch m the head of Fifa39。s antiracism taskforce, is in London for the Football Association39。s 150th anniversary celebrations and will attend City39。s Premier League match at Chelsea on Sunday. I am going to be at the match tomorrow and I have asked to meet Ya ya Toure, he told BBC Sport. For me it39。s about how he felt and I would like to speak to him first to find out what his experience was. 39 Uefa has opened disciplinary proceedings against CSKA for the racist behaviour of their fans during City39。s 21 win. Michel Platini, president of European football39。s governing body, has also ordered an immediate investigation into the referee39。s actions. CSKA said they were surprised and disappointed by Toure39。s plaint. In a statement the Russian side added: We found no racist insults from fans of CSKA. Age has reached the end of the beginning of a word. May be guilty in his seems to passing a lot of different life became the appearance of the same day。 May be back in the past, to oneself the paranoid weird belief disillusionment, these days, my mind has been very messy, in my mind constantly. Always feel oneself should go to do something, or write something. Twenty years of life trajectory deeply shallow, suddenly feel something, do it. 一字開(kāi)頭的年齡已經(jīng)到了尾聲。或許是愧疚于自己似乎把轉(zhuǎn)瞬即逝的很多個(gè)不同的日子過(guò)成了同一天的樣子；或許是追溯過(guò)去，對(duì)自己那些近乎偏執(zhí)的怪異信念的醒悟，這些天以來(lái)，思緒一直很凌亂，在腦海中不斷糾纏?？傆X(jué)得自己似乎應(yīng)該去做點(diǎn)什么，或者寫點(diǎn)什么。二十年的人生軌跡深深淺淺，突然就感覺(jué)到有些事情，非做不可了。 The end of our life, and can meet many things really do? 而