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編號(hào)
無(wú)錫太湖學(xué)院
畢業(yè)設(shè)計(jì)(論文)
相關(guān)資料
題目:基于Pro/E的接水盒注塑模具設(shè)計(jì)
信機(jī) 系 機(jī)械工程及自動(dòng)化專(zhuān)業(yè)
學(xué) 號(hào): 0923247
學(xué)生姓名: 袁蘊(yùn)芳
指導(dǎo)教師: 曹亞玲 (職稱(chēng):講 師 )
(職稱(chēng): )
2012年5月25日
目 錄
一、畢業(yè)設(shè)計(jì)(論文)開(kāi)題報(bào)告
二、畢業(yè)設(shè)計(jì)(論文)外文資料翻譯及原文
三、學(xué)生“畢業(yè)論文(論文)計(jì)劃、進(jìn)度、檢查及落實(shí)表”
四、實(shí)習(xí)鑒定表
無(wú)錫太湖學(xué)院
畢業(yè)設(shè)計(jì)(論文)
開(kāi)題報(bào)告
題目: 基于Pro/E的接水盒注塑模具設(shè)計(jì)
信機(jī) 系 機(jī)械工程及自動(dòng)化 專(zhuān)業(yè)
學(xué) 號(hào): 0923247
學(xué)生姓名: 袁蘊(yùn)芳
指導(dǎo)教師: 曹亞玲 (職稱(chēng):講師 )
(職稱(chēng): )
2011年11月14日
課題來(lái)源
本課題來(lái)源于實(shí)際生活。
科學(xué)依據(jù)(包括課題的科學(xué)意義;國(guó)內(nèi)外研究概況、水平和發(fā)展趨勢(shì);應(yīng)用前景等)
(1)課題的科學(xué)意義
本課題研究的意義在于:隨著科學(xué)技術(shù)的發(fā)展需要,模具已成為現(xiàn)代化不可缺少的工藝裝備,它被稱(chēng)為工業(yè)產(chǎn)品之母,所有工業(yè)產(chǎn)品莫不依賴(lài)模具才得以規(guī)模生產(chǎn)、快速擴(kuò)張,被歐美等發(fā)達(dá)國(guó)家譽(yù)為“磁力工業(yè)”。模具設(shè)計(jì)是機(jī)械專(zhuān)業(yè)一個(gè)最重要的教學(xué)環(huán)節(jié),是一門(mén)實(shí)踐性很強(qiáng)的學(xué)科,是對(duì)我們所學(xué)知識(shí)的綜合運(yùn)用,通過(guò)對(duì)模具設(shè)計(jì)和制造過(guò)程有個(gè)基本了解,為以后的工作及學(xué)習(xí)深造打下了堅(jiān)實(shí)的基礎(chǔ)。接水盒是日常生活中常用的基本品,對(duì)它的注塑模具進(jìn)行設(shè)計(jì)和分析,有一定的現(xiàn)實(shí)意義和經(jīng)濟(jì)價(jià)值,是順應(yīng)當(dāng)前模具制造行業(yè)發(fā)展需要的,具有重大意義。
(2)國(guó)內(nèi)外研究狀況、水平和發(fā)展趨勢(shì)
我國(guó)模具工業(yè)的產(chǎn)值在國(guó)際上排名位居第三,僅次于日本和美國(guó)。國(guó)內(nèi)的模具生產(chǎn)廠已超過(guò)17000家,從業(yè)人員達(dá)50萬(wàn)。近年來(lái),我國(guó)的模具工業(yè)一直以每年13%左右的增長(zhǎng)速度快速發(fā)展,我國(guó)模具行業(yè)在“十五”期間的增長(zhǎng)速度達(dá)到13%-15%。如今,CAD/CAM/CAE技術(shù)的應(yīng)用水平又上了一個(gè)新臺(tái)階,以生產(chǎn)家用電器的企業(yè)為代表,陸續(xù)引進(jìn)了相當(dāng)數(shù)量的CAD/CAM系統(tǒng),如美國(guó)EDS的UGⅡ、美國(guó)Parametric Technology公司的Pro/Engineer等等。這些系統(tǒng)和軟件的引進(jìn),雖花費(fèi)了大量資金,但在我國(guó)模具行業(yè)中,實(shí)現(xiàn)了CAD/CAM的集成,并能支持CAE技術(shù)對(duì)成型過(guò)程,如充模和冷卻等進(jìn)行計(jì)算機(jī)模擬,取得了一定的技術(shù)經(jīng)濟(jì)效益,促進(jìn)和推動(dòng)了我國(guó)模具CAD/CAM技術(shù)的發(fā)展。
研究?jī)?nèi)容
(1)塑件工藝性分析;
(2)注射成型機(jī)的選用;
(3)注射模的結(jié)構(gòu)組成;
(4)型腔分布與分型面的設(shè)計(jì);
(5)澆注系統(tǒng)設(shè)計(jì);
(6)導(dǎo)向及脫模機(jī)構(gòu)設(shè)計(jì) ;
(7)側(cè)抽芯機(jī)構(gòu)設(shè)計(jì)與溫度調(diào)節(jié)系統(tǒng)的設(shè)計(jì)。
擬采取的研究方法、技術(shù)路線、實(shí)驗(yàn)方案及可行性分析
(1)研究方法
借閱相關(guān)書(shū)籍雜志,充分利用圖書(shū)館及網(wǎng)絡(luò)資源。
(2)技術(shù)路線
收集資料,確定方案,設(shè)計(jì)尺寸,三維建模。
(3)實(shí)驗(yàn)方案
首先對(duì)塑件進(jìn)行工藝性分析,選擇接水盒所用材料,并分析其材料性能、成型特性及條件、結(jié)構(gòu)工藝性。根據(jù)塑件的生產(chǎn)批量及尺寸精度要求確定型腔數(shù)目,確定型腔排布及澆注系統(tǒng),選用模架。進(jìn)行校核注射機(jī),設(shè)計(jì)推出機(jī)構(gòu)及冷卻系統(tǒng)、排氣系統(tǒng)。然后進(jìn)行主要零部件強(qiáng)、剛度校核。最后按要求繪制模具零件圖、模具裝配圖。
(4)可行性分析
查閱相關(guān)設(shè)計(jì)資料,了解設(shè)計(jì)過(guò)程。熟悉零件各種配合方式和參數(shù)的計(jì)算,熟練運(yùn)用AutoCAD軟件和Pro/E軟件,做出機(jī)械零件和裝配圖以及三維建模。最后整理資料,完成畢業(yè)設(shè)計(jì)論文。
研究計(jì)劃及預(yù)期成果
研究計(jì)劃:
2012年11月12日-2012年12月2日:收集資料,撰寫(xiě)開(kāi)題報(bào)告、文獻(xiàn)綜述;
2013年12月3日-2013年3月1日:完成零件三維造型,制定設(shè)計(jì)方案;
2013年3月4日-2013年3月8日:完成模型結(jié)構(gòu)的設(shè)計(jì);
2013年3月11日-2013年3月22日:完成設(shè)計(jì)的相應(yīng)計(jì)算及相關(guān)設(shè)計(jì)結(jié)構(gòu)的和計(jì)算的檢查;
2013年3月25日-2013年4月26日:繪制模型圖、模具圖、模架圖;
2013年4月29日-2013年5月3日:繪制裝配圖;
2013年5月6日-2013年5月10日:編寫(xiě)設(shè)計(jì)說(shuō)明書(shū);
2013年5月13日-2013年5月25日: 遞交畢業(yè)設(shè)計(jì)資料,準(zhǔn)備答辯材料,并進(jìn)行答辯。
預(yù)期成果:
設(shè)計(jì)中各個(gè)部件的選擇需要具體分析和理論計(jì)算,方案擬定正確;設(shè)計(jì)計(jì)算根據(jù)來(lái)源可靠,計(jì)算數(shù)據(jù)準(zhǔn)確無(wú)誤,定位夾緊元件選用正確規(guī)范;機(jī)械結(jié)構(gòu)圖紙繪制要求視圖完整、符合最新國(guó)家標(biāo)準(zhǔn),圖面整潔、質(zhì)量高(圖紙繪制要求采用計(jì)算機(jī)繪圖);用Pro/E完成模具的三維裝配,用CAD完成零件圖和裝配圖。
特色或創(chuàng)新之處
(1)塑料注塑模能夠一次成型形狀復(fù)雜、尺寸精確或帶嵌件的塑料制件;
(2)采用組合式凹凸模,節(jié)省了成本,便于模具的維修。
已具備的條件和尚需解決的問(wèn)題
(1)已學(xué)過(guò)的塑料成型加工工藝、注塑模具的設(shè)計(jì)等,并具備有Pro/E和Auto CAD制圖能力;
(2)對(duì)Pro/E的使用有待加強(qiáng);
(3)對(duì)整體結(jié)構(gòu)的優(yōu)化設(shè)計(jì)也有待加強(qiáng)。
指導(dǎo)教師意見(jiàn)
指導(dǎo)教師簽名:
年 月 日
教研室(學(xué)科組、研究所)意見(jiàn)
教研室主任簽名:
年 月 日
系意見(jiàn)
主管領(lǐng)導(dǎo)簽名:
年 月 日
英文原文
The Injection Molding
1. The injection molding
Injection molding is 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 injection a method plastic into a mold cavity from a reservoir injection molding is quite similar to that of die-casting.The process consists of feeding a plastic compound in powered or granular form from a hopper through metering and melting stages and then injection it into a mold.After a brief cooling period ,the mold is opened and the solidified part ejected.Injection-molding machine operation.The advantage of injection molding are:(i)a high molding speed adapter for mass production is possible;(ii)there is a wide choice of thermoplastic materials providing a variety of useful properties;(iii)it is possible to mold threads,undercuts,side holes,and large thin section.
2. The injection-molding machine
Several methods are used to force or injection the melted plastic into the mold.The most commonly used system in the in-line reciprocating screw ,as shown in Figure 2-1.The screw acts as a combination injection and plasticizing unit.As the plastic is fed to rotating screw,it passes through three zones as shown:feed,compression,and metering.After the feed zone,the screw-flight depth is gradually reduced.force the plastic to compress .The work is converted to heat 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 vavle presents plastic under pressure from escaping back into the screw flight.
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 compressiong or transfer molding.Thermosetting materials cure or polymerize in the mold and are ejected hot in the range of 375℃~410℃.Thermosetting parts must be allowed to cool in the mold in order or remove them without distortion.Thus thermosetting cycles can be faster.Of course the mold must be heated rather than chilled,as with thermoplastics.
3. Basic Underfeed Mould
The description of the design and the opening sequence follows.The mould consists of three basic parts,namely:the moving half,the floating cavity plate and the feed plate respectively.
The moving half consists of The moving mould plate assembly,support block,backing plate,ejector assembly and the pin ejectiong system.Thus the moving half in this design is identical with the moving half of basic moulds.
The floating cavity plate,which may be the integer or insert-bolster design,is located on substantial guide pillars(not shown)fitted in the feed plate.These guide pillars must be of sufficient length to support the floating cavity plate over its full movement and still project to perform the function of alignment between the cavity and core when the mould is being closed.Guide bushes are fitted into the moving mould plate and the floating cavity plate respectively.
The maximum movement of the floating cavity plate is controlled by stop or similar device.The moving mould plate is suitably bored to provide sufficient a clearance for the stop bolt assembly.The stop bolts must be long enough to provide sufficient space between the feed plate and the floating cavity plate for easy removal of the feed system.The minimum space provide for should be 65mm just sufficient for an operator to remove the feed system by hand if necessary.
The desire operating sequence is for the first daylight to occur between th e floating cavity plate.This ensures the sprue is pulled from the sprue bush immediately the mould is opened.To achieve this sequence,springs may be incorporated between the feed plate and the floating cavity plate.The springs should be enough to give an initial impetus to the floating cavity plate to ensure it moves away with themoving half.It is normal practice to mount the springs on the guide pillars and accommodate them in suitable pocket in the cavity plate.
The major part of the feed system(runner and sprue)is accmmodated in the feed plate to facilitate automatic operation,the runner should be of a trapezoidal form so that once it is pulled from the feed plate is can easily be extracted.Note that if a round runner is used,half the runner is formed in the floating cavity plate,where it would remain,and be prevented from falling or being wiped clear when the mould is opened.
Now that we have considered the mould assembly in the some detail,we look at the cycle of operation for this type of mould.
The impressions are filled via the feed system and after a suitable dwell period,the machine platens commence to open.A force is immediately exerted by the compression springs,which cause the floating cavity plate to move away with the moving half as previously discussed.The sprue is pulled from the sprue bush by the sprue puller.After the floating cavity plate has moved a predetermined distance,it is arrested by the stop bolts.The moving half continued to move back and the moldings,having shrunk on to the cores,are withdrawn from the cavitities.The pin gate breaks at its junction with the runner.
The sprue puller,being attached to the moving half,is pulled through the floating cavity plate and thereby release the feed system which then free to fall between the floating cavity plate and the moldings are ejected.When the mould is closed,the respective plates are returned to their molding position and the cycle is repeated.
4. Feed System
It is necessary to provide a flow-way in the injection mould to connect the nozzle(of the injection machine) to each impression. This flow-way is termed the feed system.Normally the feed system comprises a sprue,runner and gate.These terms apply equally to the flow-way itself,and to the molded material which is remove from the flow-way itself in the process of extracted molding.
A typical feed system for a four-impression,two plate-type mould .It is seen that the material passes through the sprue,main runner,branch runner and gate before entering the impression. As the temperature of molten plastic is lowered which going through the sprue and runner,the viscosity will rise;however,the viscosity is lowered by shear generated when going through the gate to fill the cavity .Ti is desirable to keep the distance that the material has to travel down to a minimum to reduce pressure and heat losses.It is for the reason that careful consideration must be given to the impression layout gate’s design.
4.1 Sprue
A sprue is a channel through which to transfer molten plastic injected from the nozzle of the injector into the mold.It is a part of sprue bush,which is a separate part from the mold.
4.2 Runner
Arunner is a channel that guides molten plastic into the cavity of a mold.
4.3 Gate
A gate is an entrance through which molten plastic enters the cavity.The gate has the following function:restricts the flow and the direction of molten plastic;simplifies cutting of a runner and moldings to simplify finishing of parts;quickly cools and solidifies to avoid backflow after molten plastic has filled up in the cavity.
4.4 Cold slug well
The purpose of the cold slug well,shown opposite the sprue,is theoretically to receive the material that has chilled at the front of nozzle during the cooling and ejection phase.Perhaps of greater importance is the fact that it provides position means whereby the sprue bush for ejection purposes.
The sprue,the runner and the gate will be discarded after a part is complete.However,the runner and the gate are important items that affect the quality or the cost of parts.
5. Ejection
A molding is formed in mould by injecting a plastic melt , under pressure , into an impression via a feed system . It must therefore be removed manually . Furthermore , all thermoplastic materials contract as they solidify , which means that the molding will shrink on to the core which forms it . This shrinkage makes the molding difficult to remove.
Facilities are provided on the injection machine for automatic actuation of an ejector system , and this is situated behind the moving platen . Because of this . The mould’s ejector system will be most effectively operated if placed in the morning half of the mould ,i.e. The half attached to the moving platen . We have stated previously that we need to eject the,molding,from the score and it therefore follows that the core ,too , will most satisfactorily be located in the moving half .
The ejector system in a mould will be discussed under three headings , namely :(i) the ejector gird;(ii) the ejector plate assembly;and (iii) the method of ejection.
5.1 Ejector gird
The ejector gird is that part of the mould which supports the mould plate and provides a space into which the ejector plate assembly can be fitted and operated . The gird normally consists of a back plate on to which is mounted a number of conveniently shaped “support blocks ”.
The ejector plate assembly is that part of the mould to which the ejector element is attached .The assembly consists of an ejector plate , a retaining plate and an ejector rod .One end of this letter member is threaded and it is screwed into the ejector plate . In this particular design the ejector rod function not only as an actuaing member but also as a method guiding the assembly .Note that the parallel portion of the ejector rod passes through an ejector rod bush fitted in the back plate of the mould.
5.2 Ejection techniques
When a molding cools , it contacts by an amount depending on the material being processed . For a molding which has no internal form , for example , a solid rectangular block , the molding will shrink away from the cavity walls , thereby permitting a simple ejection technique to be adopted .However , when the molding has internal form , the molding , as it cools ,will shrink onto the core and some positive type of ejection and some positive type of ejection is necessary.
The designer has several ejection techniques form which to choose , but in general , the choice will be restricted depending upon the shape of the molding . The basic ejection techniques are as follows:(i)pin ejection (ii)sleeve ejection (iii)stripper plate ejection and (IV)air ejection.
中文譯文
注塑模
1. 注塑模
盡管成型某些熱固性材料的方法取得了一定的進(jìn)步,但注塑模主要用來(lái)生產(chǎn)熱塑性塑件。熱固性塑料熔體在很短的時(shí)間內(nèi)就固化和硬化,在從料斗箱模具型腔注入熱固性塑料熔體的過(guò)程中,也會(huì)出現(xiàn)這種情況,這個(gè)問(wèn)題一直非常難解決,注塑成型原理和鑄造十分相似。注塑成型的工藝包括:首先把料斗中的粉狀、粒狀的塑料混合物依次輸送發(fā)哦計(jì)量區(qū)和融化區(qū),然后再注射到模具的型腔中,經(jīng)過(guò)一段時(shí)間的冷卻后,開(kāi)模,退出成型塑件,注塑件分為手動(dòng),半自動(dòng)及全自動(dòng)操作。注塑模具有以下優(yōu)點(diǎn):(1)較高的成型速度使大批量生產(chǎn)成為可能;(2)為成型具有不同使用性能的熱塑性材料提供了較寬的選擇;(3)可以成型帶有螺紋的塑件、側(cè)向凹陷的塑件、帶有側(cè)孔的塑件以及較大的薄壁件。
2. 注塑機(jī)
熔融塑料進(jìn)入模具中通常有幾種方式。在大型注塑機(jī)上常帶采用螺桿式的注入方式。螺桿同時(shí)具有注射和塑化的功能。樹(shù)脂原料進(jìn)入旋轉(zhuǎn)的螺桿時(shí),要經(jīng)過(guò)圖示的三個(gè)區(qū)域:喂入?yún)^(qū),壓實(shí)區(qū)和計(jì)量區(qū)。經(jīng)過(guò)喂入?yún)^(qū)后,為壓實(shí)樹(shù)脂原料,螺桿螺旋部分的深度逐漸降低,同時(shí)傳遞樹(shù)脂原料間因剪切作用而產(chǎn)生的熱量,使原料呈半流動(dòng)狀態(tài)。在計(jì)量區(qū),螺缸表面的加熱裝置對(duì)熔體進(jìn)一步加熱。當(dāng)熔體充滿螺桿前部區(qū)域時(shí),螺桿在熔體壓力的作用下后退,觸動(dòng)限位開(kāi)關(guān)使液壓缸工作,在液壓力的作用下推動(dòng)螺桿向前運(yùn)動(dòng),將熔融塑料注射到閉合的模具型腔中。防倒流閥能夠組阻止受壓熔體倒流進(jìn)螺桿的螺旋區(qū)。
注塑機(jī)的鎖模系統(tǒng)做提供的鎖模力由尺寸決定,鎖模力以噸為單位。通??拷?jīng)驗(yàn)來(lái)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(dòng)困難或塑件較薄,鎖模力應(yīng)提高到三到四噸。
許多往復(fù)螺桿式注塑機(jī)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357℃~410℃范圍內(nèi)推出。熱塑性塑料熔體必須在模具內(nèi)冷卻成型,以保證推出時(shí)不發(fā)生變形,這種熱固性循環(huán)速度很快。當(dāng)然,生產(chǎn)熱塑性塑料時(shí),模具必須被加熱,而不是冷卻。
3. 模具基本結(jié)構(gòu)
這種簡(jiǎn)單的模具結(jié)構(gòu),模具設(shè)計(jì)和開(kāi)模順序?qū)⒃谝韵碌钠姓撌?。模具由三個(gè)基本部分組成,分別是動(dòng)模部分,浮動(dòng)型腔板和定模板。
動(dòng)模部分包括模板組件、支撐塊、支撐板,推出機(jī)構(gòu)和頂桿推出系統(tǒng)。這樣設(shè)計(jì)的動(dòng)模部分與最基本的模具結(jié)構(gòu)中的動(dòng)模部分相同。
浮動(dòng)型腔板通過(guò)導(dǎo)柱固定在定模板上,設(shè)計(jì)形式可以是整體式,也可以是鑲拼式。導(dǎo)柱必須有足夠的長(zhǎng)度,支撐浮動(dòng)型腔板完成開(kāi)合動(dòng)作,并在模具合模時(shí)完成對(duì)型腔和型芯的找正作用。導(dǎo)套分別安裝在動(dòng)模板和浮動(dòng)型腔板上。
浮動(dòng)型腔板的最大運(yùn)動(dòng)距離由限位釘或類(lèi)似裝置控制。在動(dòng)模板的適當(dāng)位置鉆孔,以便安裝限位釘。限位釘必須有足夠的長(zhǎng)度為定模板和浮動(dòng)型腔板之間提供足夠的空間,從而使?jié)沧⑾到y(tǒng)的凝料順利脫落。如果必須使用手動(dòng)方式取出凝料,開(kāi)模時(shí)取出凝料所需的最小距離應(yīng)為65mm。
模具的開(kāi)模順序是:浮動(dòng)型腔板和定模板先分開(kāi)。確保模具打開(kāi)時(shí)澆注系統(tǒng)凝料立即從澆口套脫出。為實(shí)現(xiàn)這樣的順序,定模板和浮動(dòng)型腔板之間裝有彈簧。彈簧的彈力必須足夠大,確保在初始推力的作用下浮動(dòng)型腔板跟隨動(dòng)模部分一起運(yùn)動(dòng)。彈簧套在導(dǎo)柱上,一同裝在浮動(dòng)型腔板上相應(yīng)的彈簧座處,這種形式在彈簧裝配中十分常見(jiàn)。
澆注系統(tǒng)的主要部分開(kāi)設(shè)在定模板上,為便于自動(dòng)操作,分流道應(yīng)采用梯形截面,以便于脫出澆注系統(tǒng)凝料。注意,如果采用圓形分流道,分流道的一半開(kāi)設(shè)在浮動(dòng)型腔板上,開(kāi)模時(shí),分流道可能留在浮動(dòng)型腔板,將阻礙凝料的脫落或去除。
我們已經(jīng)詳細(xì)討論模具裝配,再看這類(lèi)模具的生產(chǎn)循環(huán)過(guò)程。
熔體經(jīng)過(guò)澆注系統(tǒng)充滿型腔后,經(jīng)過(guò)適當(dāng)?shù)谋哼^(guò)程,注塑機(jī)帶動(dòng)模具開(kāi)模。壓縮彈簧的彈力立即釋放出來(lái),推動(dòng)浮動(dòng)型腔板和動(dòng)模部分一起移動(dòng),如同前面論述的一樣。主流道凝料被拉料桿從澆口套中拉出。浮動(dòng)型腔板移動(dòng)預(yù)定距離后,被限位釘限位。動(dòng)模部分繼續(xù)后移,塑件由于收縮作用包緊在型芯上從型腔中脫出。點(diǎn)澆口在結(jié)合處拉斷,與分流道脫離。
安裝在動(dòng)模部分的拉料桿脫離浮動(dòng)型腔板,澆注系統(tǒng)凝料由此脫下,然后在浮動(dòng)型腔板和定模板之間自由落下。動(dòng)模部分繼續(xù)后退,直到推出機(jī)構(gòu)開(kāi)始運(yùn)動(dòng),推出塑件。和模時(shí),模具的各模板回到成型位置,重復(fù)下一個(gè)注塑循環(huán)。
4. 澆注系統(tǒng)
在注塑模中,連接噴嘴和各個(gè)型腔的流動(dòng)通道是十分必要的,這種進(jìn)料通道稱(chēng)為澆注系統(tǒng)。通常,澆注系統(tǒng)由主流道、分流道和澆口組成。這些術(shù)語(yǔ)應(yīng)用在相應(yīng)的進(jìn)料通道本身,以及取出塑料時(shí)從進(jìn)料通道中一同取出的澆注系統(tǒng)凝料。
典型的兩版式四腔澆注系統(tǒng)。可以看出原料通過(guò)主流道、第一分流道、第二分流道和澆口注入道型腔中。熔融塑料通過(guò)主流道和分流道時(shí)溫度降低而使熔體粘度降低。澆注系統(tǒng)要保持適當(dāng)?shù)拈L(zhǎng)度,使熔體的壓力減少和熱量損失降到最低。因此,設(shè)計(jì)時(shí)必須充分考慮型腔布局和澆口形式。
4.1 主流道
主流道是將熔融塑料從注塑機(jī)噴嘴傳遞到模具型腔的通道。主流道是澆口套的一部分,澆口套是獨(dú)立于模具的單獨(dú)零件。
4.2 分流道
分流道是引導(dǎo)熔體塑料進(jìn)入模具型腔的通道。
4.3 澆口
澆口是熔融塑料進(jìn)入型腔的入口。澆口有以下作用:約束熔融塑料流動(dòng),應(yīng)道熔融塑料的流動(dòng)方向;使分流道和塑件末端易于分離;快速冷卻固化,防止熔融塑料充滿型腔后倒流。
4.4 冷料井
冷料井正對(duì)著主流道。理論上,冷料井的作用是用來(lái)儲(chǔ)存在(塑件)冷卻和推出過(guò)程中注塑機(jī)噴嘴處形成的熔體前鋒冷料。也許冷料井更重要的作用是幫助澆道凝料推出澆口套。
塑料成型后,主流道、分流道和澆口部分凝料將被廢棄。但是,分流道和澆口對(duì)塑件質(zhì)量和成本有重要影響。
5. 推出機(jī)構(gòu)
塑料熔體在壓力作用下經(jīng)過(guò)澆注系統(tǒng)進(jìn)入模具形成塑件,因此(塑件成型后)必須手動(dòng)取出。此外,所有熱塑性熔體凝固時(shí)都會(huì)收縮,這意味著塑料將包緊在型芯上。收縮作用使塑料脫膜(存在)困難。
注塑機(jī)為推出系統(tǒng)提高了自動(dòng)推出力,其推出動(dòng)力裝置安裝在注塑機(jī)移動(dòng)板的后面。因此,模具的推出系統(tǒng)安裝在動(dòng)模部分將獲得最大效率,例如,這部分(可以)安裝在移動(dòng)板上。我們?cè)谇懊嬲撌隽耍ㄩ_(kāi)模時(shí))需要從型芯上推下塑件,因此,塑料必須跟隨型芯(一同移動(dòng)),推出系統(tǒng)裝在動(dòng)模部分最為合適。
模具的推出系統(tǒng)將在以下三個(gè)標(biāo)題中論述,即:(1)推出支架;(2)推板裝配機(jī)構(gòu);(3)推出方式。
5.1 推出支架
推出支架是模具的一部分,用來(lái)支撐模板,為推板的裝配和運(yùn)動(dòng)提供空間。推出支架通常由定模座板和幾塊支撐塊組成,支撐塊安裝在動(dòng)模座板上,且便于加工成型。
推板裝配機(jī)構(gòu)也是模具的一部分,用來(lái)安裝推出零件。推板裝配機(jī)構(gòu)安裝在推板支撐架內(nèi),直接裝在模板后面。裝配機(jī)構(gòu)由推板、推板固定板和注塑機(jī)頂出桿組成。注塑機(jī)頂出桿一端帶有螺紋,通過(guò)螺紋緊固在推板上。在這種結(jié)構(gòu)中,頂出桿的作用不僅是推出零件,而且為推板裝配機(jī)構(gòu)起導(dǎo)向作用。注意,頂出桿直接相等的部分通過(guò)頂出桿套筒,套筒安裝在模具座板上。
5.2 推出方式
塑件冷卻后,其收縮狀態(tài)決定于塑料熔體的成型過(guò)程。對(duì)于內(nèi)部不帶有其他形狀的塑件,例如,實(shí)芯矩形件,塑件的收縮作用使其脫離型腔壁,因此,可以采用簡(jiǎn)單的脫模方式(推出塑件)。然而,若塑件具有內(nèi)部形狀,冷卻收縮時(shí)塑件將包緊在型芯上,因此,有必要采用一些適當(dāng)?shù)姆椒ㄍ瞥鏊芗?
設(shè)計(jì)推出機(jī)構(gòu)時(shí)有幾種方式可供選擇,但是,總的來(lái)說(shuō),選擇哪種推出方式取決于塑件的形狀?;镜耐瞥龇绞接幸韵聨追N:(1)推桿脫模;(2)推管脫模;(3)推件板脫模;(4)氣動(dòng)脫模。