【正文】 however, the number of parts to be made on the too1 and the part configuration are often the overriding factors in the selection process. It would not make good economic sense to build an inexpensive proto type tool that would only last for several parts when the application calls for a long production run, 本科畢業(yè)論文32or vice versa. Part configuration or plexity will also drive the tooling decision process. For example, while welded steel tools are often used for large wing skins, it would not be cost effective to use steel for a highly contoured fuselage section due to the high fabrication cost and plexity.One of the first choices that must be made is which side of the part should be tooled, . ,the inside or outside surface as shown in a skin to provides the opportunity to produce a part with an extremely smooth outside surface finish. However, if the part is going to be assembled to substructure, for example, with mechanical fasteners, tooling to the inside or inner mold line (IML) surface will provide better at with fewer gaps and less shimming required. An example is the wing skin shown in , which was tooled to the IML surface to ensure the best possible fit to the substructure during assembly. Acaul plate is used on the bag side during cure to provide an acceptable OML aerodynamic surface finish. As shown in , this part contains severe thickness transitions on the IML surface.If the part were of constant thickness or contained little thickness variation, it might have then made more sense to tool it to the OML surface. Ease of part fabrication is another in ,it would certainly be easier to collate or layup the plies on the male tool shown than down inside the cavity of a female tool. Selection of the material used to make the tool is another important consideration. Several of the key properties of various tooling materials are given in Table ,reinforced polymers can be used for low to intermediate temperatures, metals for low to high temperatures, and monolithic graphite or ceramics for very high generally been made of either steel or aluminum. Electroformed nickel became popular in the early 1980s followed by the introduction of carbon/epoxy and carbon/bismaleimide posite tools in the ,in the early 1990s,a series of low expansion ironnickel alloys was introducted under the trade names Invar and Nilo.Steel has the attributes of being a fairly cheap material with exceptional durability. It is teadily castable and has been known to withstand over 1300autoclave CUIE cycles and still be capable of making good partsHowever, steed is heavy, has a higher coefficient of thermal expansion (CTE)than the carbonjepoxy parts usually built on it, and for large massive tooling it can experience slow heatup rates in an autoclave. When a steel tool fails inservice, it usually be due to a cracked weldment.Aluminum, on the other hand, is much .lighter and has a much higher coefficient of thermal conductivity. It is do much easier to machine than steel but is more difficult Part Outside Surface本科畢業(yè)論文33to produce pressuretight castings and weldment. The two biggest drawbacks of aluminum are: being a soft material, it is rather susceptible to scratches, nicks and dents, and it has a very high coefficient of thermal expansion. Aluminum tools are quite frequently hard anodized to improve the durability. Hard anodize coatings do tend to spall and flakeoff as the aluminum temper ages during multiple thermal cycles. Due to its lightweight and ease of mach inability, aluminum is often used for what are called form block tool. As shown in ,a number of aluminum form block tools can be placed on a large flat aluminum project plate, then the plate with all the parts is covered with a single vacuum bag for cure, a considerable cost savings pared to bagging each individual part. Another application for aluminum tools is matcheddie tooling, where all surface are tooled, as shown for the spar in .Electroformed nickel keel has the advantages that it can be made into plex contours and does not require a thick faceplate. When backed with an open tubulartype substructure, this type of tool experiences excellent heatup rate in an autoclave. However, to make an electroformed nickel tool requires that a mandrel be fabricated to the exact contour of the final tool.Carbon/epoxy or glass/epoxy tools ()also require a master or mandrel for layup, during tool fabrication. A distinct advantage of carbon/ epoxy tools is that their CTE can be tailored to match that of the carbon/ epoxy parts they build. In addition, posite tools are rela。還有就是在寫畢業(yè)設(shè)計過程中幫我解決一系列的問題的同學(xué)們，非常謝謝你們，確實團隊的力量是強大的，謝謝你們。如今，伴隨著這篇畢業(yè)論文的最終成稿，復(fù)雜的心情煙消云散，自己甚至還有一點成就感。記得從論文選題到搜集資料，從開題報告、寫初稿后被你說的樣子到反復(fù)修改，期間經(jīng)歷了喜悅、聒噪、痛苦和彷徨，在寫作論文的過程中心情是如此復(fù)雜。提高了我們的思考、解決問題創(chuàng)新設(shè)計的能力，為以后的工作打下了較好的基礎(chǔ)。通過組員彼此間的交流，讓我們不僅解決了自身問題，還可以提早了解后續(xù)相關(guān)工作中的問題，這樣可以提前做好預(yù)防及提前了解相關(guān)解決此類問題的知識與方案，這樣大大節(jié)省了時間，提高了工作效率，并且還增加了我們對知識的了解。在設(shè)計過程中，我們綜合運用了系統(tǒng)的設(shè)計方法，且應(yīng)用熟悉相關(guān)資料（包括手冊、標(biāo)準(zhǔn)和規(guī)范等）以及進行經(jīng)驗估算等方面有了一定程度的提高，深刻的感受到計算機和工具及手冊在設(shè)計中帶來的便利和幫助。下面是工藝過程，見表 32本科畢業(yè)論文27工序號 工序內(nèi)容 工序名稱1 劃三孔及 R88cm 扇形缺圓孔線 劃線 詳見附錄 B 表 12 粗銑 A 面及對面留 余量 粗銑 詳見附錄 B 表 23 以 A 面定位，按線校正，粗銑安裝面 B,留余量 粗銑 詳見附錄 B 表 34上角鐵夾具，以 A 面(3)、B 面（2）為定位基準(zhǔn)，按線校正粗鏜三孔及 R88mm 扇形缺孔圓孔粗鏜 詳見附錄 B 表 45 精銑 A 面及另一端 精銑 詳見附錄 B 表 56 精銑安裝面 B，留刮研余量 精銑 詳見附錄 B 表 67 鉆殼體端蓋螺釘孔，鉆 B面安裝孔 鉆 詳見附錄 B 表 78 半精鏜孔 鏜 詳見附錄 B 表 89 精鏜孔 鏜 詳見附錄 B 表 9表 32 零件工序圖本科畢業(yè)論文28結(jié) 論經(jīng)過三個月的時間，在老師的指導(dǎo)和自己的努力下，我的畢業(yè)計設(shè)最終的完成。為了加強科學(xué)管理和便于交流，原電子工業(yè)部制定了指導(dǎo)性技術(shù)文件《工藝規(guī)程格式》。 填寫工藝文件 零件的機械加工工藝規(guī)程制定好以后，必須將上述各項內(nèi)容填寫在工藝卡片上，以便遵照執(zhí)行。查《切削手冊》f=～。2) 切削用量a銑削深度因為切削量較小，故可以選擇a p=。,主偏角Kr=70176。刀具：硬質(zhì)合金車刀。 加工要求：上鏜模裝夾，精鏜三孔達圖樣要求。查《切削手冊》表8，壽命T=180minc計算切削速度和主軸轉(zhuǎn)速按《切削手冊》表14，查得Vf＝150m/min，n=750r/min，詳見附錄B表8。查《切削手冊》f=~。3) 切削用量a銑削深度因為切削量較小，故可以選擇a p=。,主偏角 Kr=70176。 選擇刀具前角 γo＝18176。刀具：硬質(zhì)合金車刀。加工要求：上鏜模半精鏜三對孔及 R88mm 扇形缺圓孔。擴鉸和精鉸的切削用量如下:擴鉆：選高速鋼擴孔鉆 n=200r/min f=～????nfltm