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南 京 工 程 學(xué) 院
畢業(yè)設(shè)計(論文)選題、審題表
教研室
模具
指導(dǎo)教師
林偉
職稱
講師
申報課題名稱
基于UG的相機殼注塑模設(shè)計
課題性質(zhì)
A
課題來源
D
課
題
簡
介
相機殼塑料件結(jié)構(gòu)特點突出,具有側(cè)孔,需要做側(cè)向抽芯結(jié)構(gòu),采用斜導(dǎo)柱側(cè)向抽芯結(jié)構(gòu),該塑料件分型面為曲面分型面,所以該模具結(jié)構(gòu)復(fù)雜。使學(xué)生掌握較復(fù)雜的典型模具結(jié)構(gòu)和能利用UG進行分模面設(shè)計,掌握分模面在模具設(shè)計中的重要作用。通過MOLDFLOW—MPI模具分析技術(shù)從理論上對產(chǎn)品設(shè)計方案在注塑成型過程進行數(shù)值模擬,通過有關(guān)計算結(jié)果的分析,預(yù)測塑料件結(jié)構(gòu)可能出現(xiàn)的缺陷,利用MPI分析結(jié)果,合理設(shè)計模具澆注系統(tǒng)和冷卻系統(tǒng),消除缺陷。
所需經(jīng)費
上機時數(shù)
課題要求
(包括所具備的條件)
1、 對常用塑料具備一定的了解和掌握;
2、 熟悉AUTOCAD及UG繪圖;
3、 熟悉注射模具設(shè)計步驟及方法;
4、了解模具的制造加工過程。
課題工作量要求
1. 開題報告(含本課題任務(wù)分析、文獻(xiàn)綜述、本課題的主要研究方法及工作計劃等);
2. 模具工程圖(折合2~3張A0圖紙)、產(chǎn)品三維圖;
3. 畢業(yè)設(shè)計論文,須電子文檔;
4. 畢業(yè)設(shè)計內(nèi)容光盤一張。
教研室
審定意見
室主任簽字:
系領(lǐng)導(dǎo)小組審定意見
教學(xué)主任簽字:
說明:1、該表為畢業(yè)設(shè)計(論文)課題申報時專用,由選題教師填寫,經(jīng)教研室討論、室主任簽字,報學(xué)院領(lǐng)導(dǎo)小組審定,院長簽字后生效。
2、課題性質(zhì):A.工程設(shè)計;B.工程技術(shù)研究;C.軟件工程(如CAI課題);D.文獻(xiàn)型綜述;E.其它。
3、課題來源:A.自然科學(xué)基金與部、省、市級以上科研課題;B.企、事業(yè)單位委托課題;C.院級基金課題;D.自擬課題。
4、上機時數(shù)可填:xx時數(shù)/人或者該課題所需總時數(shù)。
5、選題結(jié)束后,該表要求統(tǒng)一存放在學(xué)院辦公室備查。
二、注塑模和壓縮模
盡管成型某些熱固性材料的方法取得了一定進步,但注塑模主要(還是)用來生產(chǎn)熱塑性塑件(這主要是因為)熱固性塑料熔體的過程中,也會出現(xiàn)這種情況,這個問題一直非常難解決。住宿成型要換里和鑄造十分相似。住宿成型的工藝過程包括:首先把料斗中的粉狀或粒狀的塑料混合物依次輸送到定量去和熔化區(qū),然后再注射到模具型腔中,經(jīng)過短時冷卻后,開模,推出成型塑件。注塑機分為手動,半自動及全自動操作。住宿模具有以下優(yōu)點:
(i) 較高的成型速度使大批量生產(chǎn)成為可能;
(ii) 為成形具有不同使用性能的熱塑性材料提供了較寬的選擇;
(iii) 可成型帶有螺紋的塑件、側(cè)向凹陷的塑件、帶有側(cè)孔的塑件和較大的薄壁件。
熔融塑料注入模具中通常有幾種方式。在大型注塑機上采用往復(fù)螺桿式的注入方式。螺桿同時具有注射和塑化的功能。樹脂原料進入旋轉(zhuǎn)的螺桿時,要經(jīng)過三個區(qū)域:喂入?yún)^(qū)、壓實區(qū)和塑化區(qū)經(jīng)過喂入?yún)^(qū)后,為壓實樹脂原料,螺桿螺旋部分的深度逐漸降低,同時傳遞樹脂原料間因剪切作用而產(chǎn)生的熱量,使原料呈現(xiàn)半流動狀態(tài)。在計量區(qū),螺缸表面的加熱裝置對熔體進一步加熱。當(dāng)熔體充滿螺桿前部區(qū)域時,螺桿在熔體壓力的作用下后退,觸動限位開關(guān)使液壓缸工作,在液壓力的作用下推動螺桿向前運動,將熔融塑料注射到閉合的模具型腔中。防倒流閥能夠阻止受壓熔體倒流進螺桿的螺旋區(qū)。
注塑機的鎖磨系統(tǒng)所提供的鎖模力由(塑件在分型面的投影)尺寸決定,鎖模力以噸為單位。通??拷?jīng)驗來決定塑件所需要的鎖模力總噸數(shù),一般在塑件投影面積上每平方英寸需要作用兩噸鎖模力。如果熔體流動困難或塑件較薄,鎖模力應(yīng)提高到三到四噸。
許多螺桿式注塑機能生產(chǎn)熱固性塑料。以前,熱固性塑料由擠出模具或傳遞模具生產(chǎn)。熱固性塑料熔體在模具內(nèi)固化或發(fā)生聚合反應(yīng),并在溫度為375℃~410℃范圍內(nèi)推出熱塑性塑料熔體必須在模具冷卻成型,以保證推出時不發(fā)生變形。這種熱硬化性循環(huán)速度很快。當(dāng)然,生產(chǎn)熱塑性塑件時,模具必須被加熱,而不是冷卻。
注塑模重要性有:
⑴、塑料具有密度小、質(zhì)量輕、比強度大、絕緣性好、介電損耗低、化學(xué)穩(wěn)定性強、成型生產(chǎn)率高和價格低廉等優(yōu)點,在國民經(jīng)濟和人民日常生活的各個領(lǐng)域得到了日益廣泛的應(yīng)用,早在二十世紀(jì)九十年代初,塑料的年產(chǎn)量按體積計算已經(jīng)超過鋼鐵和有色金屬年產(chǎn)量的總和。在機電(如所謂的黑色家電)、儀表、化工、汽車和航天航空等領(lǐng)域,塑料已成為金屬的良好代用材料,出現(xiàn)了金屬材料塑料⑵、以汽車工業(yè)為例,由于汽車輕量化、低能耗的發(fā)展要求,汽車零部件的材料構(gòu)成發(fā)生了明顯的以塑代鋼的變化,目前我國汽車塑料占汽車自重的5%至6%,而國外已達(dá)13%,根據(jù)專家預(yù)測,汽車塑料的單車用量還將會進一步增加。在現(xiàn)代車輛上,無論是外裝飾件、內(nèi)裝飾件,還是功能與結(jié)構(gòu)件,都可以采用塑料材料,外裝飾件有保險杠、擋泥板、車輪罩、導(dǎo)流板等;內(nèi)裝飾件有儀表板、車門內(nèi)板、副儀表板、雜物箱蓋、座椅、后護板等;功能與結(jié)構(gòu)件有油箱、散熱器水室、空濾器罩、風(fēng)扇葉片等。據(jù)統(tǒng)計,我國2000年汽車產(chǎn)量200多萬輛,車用塑料達(dá)138萬噸。從國內(nèi)外汽車塑料應(yīng)用的情況看,汽車塑料的用量現(xiàn)已成為衡量汽車生產(chǎn)技術(shù)水平的標(biāo)志之一。
⑶、作為塑料制件最有效的成型方法之一的注塑成型由于可以一次成型各種結(jié)構(gòu)復(fù)雜、尺寸精密和帶有金屬嵌件的制品,并且成型周期短,可以一模多腔,生產(chǎn)率高,大批生產(chǎn)時成本低廉,易于實現(xiàn)自動化生產(chǎn),因此在塑料加工行業(yè)中占有非常重要的地位。據(jù)統(tǒng)計,塑料模具約占所有模具(包括金屬模)的38.2%,塑料制品總重量的大約32%是用于注射成型的,80%以上的工程塑料制品都要采用注射成型方式生產(chǎn)。
⑷、根據(jù)海關(guān)統(tǒng)計,我國2000年共進口模具9.77億美元,其中塑膠模具共5.5億美元,占56.3%,2001年共進口模具11.12億美元,其中塑膠模具共6.16億美元,占55.4%。從品種上來說,進口量最大的是塑膠模具。
在壓縮成型過程中,塑料原料是以粉狀或錠料形式放置在加熱的金屬模具型腔中。因為分型面是水平面,上模就垂直下行。閉合模具后,預(yù)成型加壓加熱作用一段時間。在壓力為2~3t/in和溫度為華氏溫度350的作用下,是塑料呈半液態(tài),充滿模具型腔。雖然近年來開發(fā)的酚醛樹脂可在25S內(nèi)塑化,但塑料通常的塑化需要1~15min。最后開模取出塑件。如果零件中含有金屬嵌件,應(yīng)在注入塑料前,講嵌件放入型腔定位孔中。錠料在裝入模腔前預(yù)熱出去氣體,增強流動性,以便于充滿模具和縮短塑化時間。電介質(zhì)加熱時加熱錠料的便利方法。
因為塑料是直接加入模具型腔中的,所以壓縮模比其他模塑料工藝的模具簡單,不需要澆道和澆口,可以節(jié)省原料,因為清理澆道和澆口,對熱固性塑料來說是極大的浪費。用于壓縮模塑的壓力機通常是垂直液壓機。較大的壓力機要求操作者全神貫注地操作;然而,一個操作者可以同時操作幾臺小型壓力機,因此壓力機要合理放置以便操作者能夠方便你從一臺到另一臺進行操作,操作者要保證當(dāng)他再次繞道特定壓力機前時,模具恰好準(zhǔn)備開模。熱固性塑料在加熱和加壓作用下固化,這個特性決定其適合壓縮模和傳遞模。因為壓縮模要交替的加熱和冷卻,所以熱塑性塑料實際上不是用于壓縮成型。為了使熱塑性塑料之間硬化并從型腔中頂出,就需要將塑件冷卻。
壓縮模的類型。 用于壓縮的模具可分為四種基本類型,分別是:不溢式壓縮模、擋環(huán)不溢式壓縮模、溢式壓縮模和半溢式壓縮模。在不溢式壓縮模中,柱塞式凸模隨上模進入下模模腔成型,因為下模沒有擋環(huán)或限位裝置,柱塞式凸模繼續(xù)下行以全部壓力施加在塑料上,這樣就成產(chǎn)出具有良好電性能和物理性能的致密塑件。加入模腔的塑料劑量須精確計量,以為其影響零件的壁厚。擋環(huán)不溢式壓縮模與不溢式壓縮模類似,只是在預(yù)定點處增加了擋環(huán),使柱塞式凸模在預(yù)定點停止運動,在這種模具中擋環(huán)吸收了原應(yīng)作用在零件上的部分壓力。這種壓縮??删_控制零件的壁厚,但是塑件密度的變化是相當(dāng)大的。在溢式壓縮模中,溢料會增加上下模的尺寸。當(dāng)上模對塑料施壓時,多余的塑料會從分型面處溢出。對溢料進一步施壓,他就硬化最后在上模形成飛邊。生產(chǎn)致密塑件通常需要使用的計算量稍多的原料來增加壓力。這種類型的模具之所以在生產(chǎn)中廣泛采用,是因為它想對比較容易制造,并能夠控制塑件的厚度和致密度,使其更接近要求。半溢式壓縮模是溢式壓縮模和不溢式壓縮模的組合類型,除了飛邊外,采用的擋環(huán)可限制上模的移動。
南京工程學(xué)院
畢業(yè)設(shè)計任務(wù)書
江蘇財經(jīng) 學(xué)院 數(shù)控加工與模具設(shè)計 專業(yè)
設(shè) 計 題 目 基于UG的相機殼注塑模設(shè)計
學(xué) 生 姓 名 潘 濤
班 級 10模具(本)
起 止 日 期 2012.02.06-04.26
指 導(dǎo) 教 師 林 偉
教研室主任 赫英岐
發(fā)任務(wù)書日期 2012年2月6日
1.畢業(yè)設(shè)計的原始數(shù)據(jù):
(1)產(chǎn)品圖及其技術(shù)要求;
(2)生產(chǎn)批量:中批量。
2.畢業(yè)設(shè)計(論文)的內(nèi)容和要求(包括技術(shù)要求、圖表要求以及工作要求等):
(1)繪制產(chǎn)品零件圖;
(2)查閱資料并就自己承當(dāng)?shù)恼n題方向?qū)懗鲩_題報告(嚴(yán)格按統(tǒng)一格式);
(3)完成產(chǎn)品的工藝設(shè)計及模具設(shè)計并繪制模具及模具零件的工程圖;
(4)按規(guī)定格式和要求用Word打印設(shè)計說明書一份;
(5)用PowerPoint或其它軟件制作答辯提綱一份。
3.畢業(yè)設(shè)計應(yīng)完成的技術(shù)文件:
(1)產(chǎn)品零件圖;
(2)開題報告(格式見校園網(wǎng));
(3)模具裝配圖及各零件圖;
(4)設(shè)計計算說明書;
(5)上述所有文檔的刻錄光盤一張。
4.主要參考文獻(xiàn):
(1)李秦蕊主編 塑料模具設(shè)計 西安工業(yè)大學(xué)出版社 1997
(2)申開智主編 塑料成型模具 中國輕工業(yè)出版社 2009
(3)廖念釗主編 互換性與技術(shù)測量 中國計量出版社 1998
(4)王鵬駒主編 塑料模具設(shè)計手冊 機械工業(yè)出版社 2008
(5)吳宗澤主編 機械零件設(shè)計手冊 機械工業(yè)出版社 2006
(6)羅和生主編 塑料材料手冊 廣東出版社 2004
(7)張國強主編 塑料模設(shè)計與生產(chǎn)應(yīng)用 應(yīng)用出版社 2005
(10) 王永主編 注塑模具經(jīng)驗點評 機械工業(yè)出版社 2007
5.畢業(yè)設(shè)計(論文)進度計劃(以周為單位):
起 止 日 期
工 作 內(nèi) 容
備 注
第1-2周
(02.06-02.19)
1、熟悉課題,查閱并收集有關(guān)資料,為寫開題報告做準(zhǔn)備;
2、繪制產(chǎn)品零件圖;
3.完成工藝性分析,提出設(shè)計方案;
檢查零件圖
和方案
第3-4周
(02.20-03.04)
1、寫出開題報告初稿。
2、完成工藝計算;
3、完成模具零件結(jié)構(gòu)形式確定及設(shè)計,選擇設(shè)備。
檢查開題報告
第5-6周
(03.05-03.18)
1、第8周完成開題報告的最后定稿;
2、繪制模具草圖
檢查開題報告與模具結(jié)構(gòu)草圖
第7-9周
(03.18-04.08)
繪制模具裝配圖及各設(shè)計件零件圖
檢查圖(電子版)
第10-11周
(04.09-04.22)
編寫設(shè)計說明書
檢查設(shè)計說明書
第12周
(04.23-04.26)
打印畢業(yè)設(shè)計資料并準(zhǔn)備答辯
檢查答辯PPT
教研室審查意見:
室主任
2012年2月8 日
學(xué)院審查意見:
教學(xué)院長
2012年2月12 日
二、The injection and Compression Molding
Injection molding si principally used for the production of the thermoplastic parts, although some progress has been made in developing a method for injection molding some thermosetting materials. The problem of injecting a melted plastic into a mold cavity form a reservoir of melted material has been extremely difficult to solve for thermosetting plastics which cure and harden under such conditions within a few minutes. The principle of injection molding is quite similar to that of die-casting. The process consists of feeding a plastic compound in powdered or granular form from a hopper through metering and melting stages and then injecting it into a mold. After a brief coolling period, the mold is opened and the solidified part ejected. Injection-molding machines can be arranged for manual operation, automatic single-cucle operation, and full automatic operation. The advantage of injection molding are:
(i) a high molding speed adapted for mass production is possible;
(ii) there is a wide choice of thermoplastic materials providing a variety of usefull properties;
(iii) it is possible to mold threads, undercuts, side holes, and large thin sections.
Several methods are used to force or inject the melted plastic into the mold. The most commonly used system in the larger machines is the in-line reciprocating screw.The screw acts as a combination and plasticizing unit.As the plastic is fed to the rotating screw,it passes through three zones as shown: feed,compression, and metering. After the feed zone, the screw-flight depth is gradually reduced,forcing the plastic to compress. The work is converted to heat by shearing the plastic, making it a semifluid mass. In the metering zone, additional heat is applied by conduction from the barrel surface. As the chamber in front of the screw becomes filled, it forces the screw back, tripping a limit switch that activates a hydraulic cylinder that forces the screw forward and injects the fluid plastic into the closed mold.An antiflowback valve prevents plastic under pressure from escaping back into the screw flights.
The clamping force that a machine is capable of exerting is part of the size designation and is measured in tons. A rule-of-thumb can be used to determine the tonnage required for a particular job. It is based on two tons of clamp force per square inch of projected area. If the flow pattern is difficult and the parts are thin,this may have to go to three or four tons.
Many reciprocating - screw machines are capable of handing thermosetting plastic materials.Previously these materials were handled by compression or transfer molding.Thermosetting materials cure or polymerize in the mold and are ejected hot in the range of 375℃~410℃.Thermoplastic parts must be allowed to cool in the mold in order to remove them without distortion.Thus thermosetting cycles can be faster.Of course the mold must be heated rather than chilled,as with thermoplastics.
The importance of Injecting the mold are :
⑴、Plastics have the density small, the quality light, the specific tenacity big, the insulating property good, the dielectric loss low, the chemical stability strong, the formation productivity high and the price inexpensive and so on the merits, obtained day by day the widespread application in the national economy and people's daily life each domain, as early as in the beginning of 1990s, the plastic annual output already surpassed the steel and iron and the non-ferrous metal annual output sum total according to the volume computation.In mechanical and electrical (for example so-called black electrical appliances), domains and so on measuring appliance, chemical, the automobile and astronautics aviation, the plastic has become the metal the good substitution material, had the metal material plastic tendency.
⑵、Take the automobile industry as the example , as a result of the automobile lightweight, the low energy consumption development request, the automobile spare part material constitution occurred obviously has modelled the band steel the change, at present our country automobile plastic accounts for 5% which the automobile was self-possessed to 6%, but overseas has reached 13%, forecast according to the expert, the automobile plastic bicycle amount used will also be able further to increase.On modern vehicles, regardless of is outside installs the assorted items, the internal installation assorted items, the function and the structural element, all may use the plastic material, outside installs the assorted items to have the bumper, the fender, the wheel hub cap, the air deflector and so on; After the internal installation assorted items have in the display board, the vehicle door the board, the vice-display board, the sundry goods box lid, the chair, the guard shield and so on; The function and the structural element have the fuel tank, the radiator header, the spatial filter hood, the fan blade and so on.Statistics have indicated, our country in 2000 automobile output more than 200 ten thousand, the vehicle amounted to 1,380,000 tons with the plastic.Looked from the domestic and foreign automobile plastic application situation that, the automobile plastic amount used already became one of weight automobile production technical level symbols.
⑶、Injection of a molding formation as plastic workpiece most effective formation methods because may by one time take shape each kind of structure complex, the size precise and has the metal to inlay a product, and the formation cycle is short, may by mold multi-cavities, the productivity be high, when mass productions the cost isvery inexpensive, easy to realize the automated production, therefore holds the extremely important status in the plastic processing profession.Statistics have indicated, plastic mold composition all molds (including metal pattern) 38.2%, the plastic product gross weight about 32% is uses in injecting the formation, 80% above engineering plastics product all must use the injection formation way production. 4. counts according to the customs, our country in 2000 altogether imported mold 977,000,000 US dollars, in which plastic molding forms altogether 550,000,000 US dollars, occupied for 56.3%,2001 years altogether to import mold 1,112,000,000 US dollars, in which plastic molding forms altogether 616,000,000 US dollars, accounted for 55.4%.From the variety, the import volume biggest is the plastic molding forms.
⑷、Counts according to the customs, our country in 2000 altogether imported mold 977,000,000 US dollars, in which plastic molding forms altogether 550,000,000 US dollars, occupied for 56.3%, 2001 years altogether to import mold 1,112,000,000 US dollars, in which plastic molding forms altogether 616,000,000 US dollars, accounted for 55.4%.From the variety, the import volume biggest is the plastic molding forms.
In compression molding the palstic material as powder or preforms is placed into a heated steel mold cavity,Since the parting surface is in a horizontal plane ,the upper half of the mold descends vertically.It closes the mold cavity and pressures for a predetermined period.A pressure of from 2 to 3 tons square inch and a temperaure at approximately 350F converts the plastic to a semiliquid which flows to all parts of the mold cavity.Usually from 1 to 15 minutes is required for curing,altough a recently developed alkyd plastic will cure in less than 25 secends. The mold is then opended and the molded part removed.If metal insers are desired in the parts,they should be placed in the mold cavity on pins or in the holes before the plastic is loaded.Also, the preforms should be preheated before loading into the mold cavity to eliminate gases,inprove flow,and decrease curing time.Dieletric heating is a convenient method of heating the preforms.
Since the plastic material is placed directly into the mold cavity,the mold itself can be simpler than those used for other molding precesses.Gates and sprues are unnecessary.This also results in a saving in material,because trimmed-off gates and sprues would be a complete loss of the thermosetting plastic.The press require the full attention of one operator.However,several smaller presses can be operated by one operator. The presses are conveniently located so the operator can easilymove from one to the next.By the time he gets around to a particular press again,that mold will be ready to open.the thermosetting plastics which harden under heat and pressure are suitable for compression molding and transfer molding.It is not practical to moid shermoplastic materials by these methods,since the molds would have to be alternately heated and cooled.In order to harden and eject thermoplastic parts form the mold,cooling would be necessary.
Types of molds for compression molding.The molds used for compression molding are classified into four basic types, namely ,positive molds,landed positive mold,flash-type molds,and semipositive molds.In a positive mold the plunger on the upper mold enters the lower mold cavity.since there are no lands or stops on the lower die ,the plunger completely trap the plastic material and descends with full pressure on the charge.A dense part with good electrical and physical properties is produced.The amount of plastic placed in the die cavity must be accurately measured,since it determines the thickness of the part .A landed positive mold is similar to a positive mold except that lands are added to stop the travel of the plunger at predetermined point.In this case,the lands absorb some of the pressure that should be exerted on the parts.The thickness of the parts will be accurately controlled,but the density may vary cansideraby.In a flash-type mold,flash redges are added ti the top and bottom molds.As the upper mold exerts pressure on the plastic,excess material is forced out between the flash ridges where it forms flash.This flash is further compressed.becomes hardened,and finally stops the downard thavel of the upper mold.A slight excess of the plastic material is always chared to ensure sufficient pressurs to produce a dense molded part.This type of mold is widely used because it is comparatively easy to construct and it controls thickness and density within colse limits.The semipositive mold is a combination od the flash type and landed posive molds.In addition to the flash ridges,a land is employed to restrict the travel of the upper mold.
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