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定位圈
型芯上鑲件
鹽城工學院本科生畢業(yè)設(shè)計說明書 2008
1前言
隨著塑料行業(yè)的不斷發(fā)展，對塑料模具提出越來越高的要求，因此，精密、大型、復雜、長壽命塑料模具的發(fā)展將高于總量發(fā)展速度。同時，由于近年來進口模具中，精密、大型、復雜、長壽命模具占多數(shù)，所以，從減少進口、提高國產(chǎn)化率角度出發(fā)，這類高檔模具在市場上的份額也將逐步增大。采用模具生產(chǎn)制件具有生產(chǎn)效率高，質(zhì)量好，切削少，節(jié)約能源和原材料，成本低等一系列優(yōu)點，模具成型已經(jīng)成為當代工業(yè)生產(chǎn)的重要手段，成為多種成型工藝中最具有潛力的發(fā)展方向。模具是機械、電子等工業(yè)的基礎(chǔ)工業(yè)，它對國民經(jīng)濟和社會發(fā)展起著越來越大的作用。
模具行業(yè)是制造業(yè)的重要組成部分，具有廣闊的市場前景。注塑模具分為熱塑性塑料注塑成型模具和熱固性塑料注塑成型模具兩大類。注塑模具的結(jié)構(gòu)是由塑件結(jié)構(gòu)和注塑機的形式?jīng)Q定的。凡注塑模具，均可分為動模和定模兩大部分。要真確地、高水平地使用注塑模具計算機輔助設(shè)計的各種軟件，也必須對模具設(shè)計的原則和方法有透徹的了解。
注射成型是塑料制品的主要成型方法,約半數(shù)以上的塑料制品是通過注射成型的。因此，塑料注射模的數(shù)量為其它各類塑料模具之首，約占整個塑料模具總產(chǎn)量的50%以上。同時塑料注射模具的設(shè)計制造和加工精度，均比其它各類塑料模具難度要大一些。一般來說，若能掌握塑料注射模具的制造技術(shù)，則對掌握其它各類塑料模具的制造技術(shù)，顯然會容易多了。
注塑模設(shè)計的主要內(nèi)容歸納起來大致有以下幾個方面：
A、根據(jù)塑料熔體的流變行為和流道、型腔內(nèi)各處的流動主力通過分析得出充模順序，同時考慮塑料熔體在模具型腔內(nèi)被分流及重新熔合的問題和模腔內(nèi)原有空氣導出的問題，分析熔接痕的位置、決定澆口的數(shù)量和方位。
B、根據(jù)塑料熔體的熱學性能數(shù)據(jù)、型腔形狀和冷卻水道的布置，分析得出保壓和冷卻過程中塑件溫度場的變化情況，解決塑件收縮及補縮問題，盡量減少由于溫度和壓力不均、結(jié)晶和取向不一致而造成的殘余內(nèi)應力和翹曲變形。
C、塑件脫模和橫向分型抽芯的問題可通過經(jīng)驗和理論分析來解決這方面的問題，目前還正在大力研究建立在經(jīng)驗和理論計算基礎(chǔ)上的計算機專家系統(tǒng)軟件，以期這方面的工作能更快、更準確無誤的在計算機上實現(xiàn)。
D、決定塑件的分型面，決定型腔的鑲拼組合。模具的總體結(jié)構(gòu)和零件形狀不單要滿足充模和冷卻等工藝方面的要求，同時成型零件還要具有適當?shù)木?、粗糙度、強度和剛度、易于裝配和制造，制造成本低。
以上這些問題，并非孤立存在，而是相互影響的，應綜合加以考慮。
本課題是對塑料提桶進行測繪、模具設(shè)計、模具型腔仿真加工。課題來源于鹽城市羽佳塑料制品廠。基于生產(chǎn)實踐之上的對塑料提桶的模具設(shè)計以及仿真加工。在設(shè)計過程中要解決塑料提桶制品測繪、模具設(shè)計、在模具設(shè)計時對分型面的選擇、澆口形式與位置的確定、型腔的安排、型腔和型芯冷卻水道的設(shè)置、工藝分析及加工仿真等問題。塑料提桶制品的幾何尺寸進行測量后要進行合理的后處理。模具分型面處在同一平面時不需要一定的角度，所以選擇底面為分型面。本模具設(shè)計采用直接澆口。為使流道平衡,應使各型腔距主流道距離均等。由于所成型的制品形狀簡單且?guī)缀纬叽巛^大,因此可采用冷卻水道圍繞型腔、定模鑲件、型芯主體的冷卻方式。模具方案設(shè)計完成后對型腔進行仿真加工。據(jù)此方案可以達到設(shè)計的預期效果。并且大大提高了注塑模的質(zhì)量和效率。
2總體方案論證
本課題的設(shè)計目的是對塑料提桶三維造型及優(yōu)化、塑料注射模具設(shè)計和模具加工仿真。其中：1、 制品的厚度方向小于2.0； 2、制品材料為ABS；3、制品表面粗糙度不低于實物表面；4、制品生產(chǎn)批量為5萬件；5、制品的其他要求要符合設(shè)計規(guī)范。在進行零件的三維造型之前，首先要對塑件進行測繪，繪制塑件二維工程圖，然后根據(jù)工程圖進行塑件的三維造型，再進行型腔的設(shè)計，主要是分型面的設(shè)計，接著就是把分型后的型腔裝配組件調(diào)入Pro/E Wildfire4.0進行整個模架的設(shè)計，然后進行仿真加工。
首先是對塑件進行測繪。由于該塑件大都為曲面實際測量有一定困難所以采用多次取斷面進行測量的方法。測繪好后使用Pro/E Wildfire4.0進行三維造型。主要采用拉伸、除料、旋轉(zhuǎn)等步驟造型。根據(jù)工廠現(xiàn)有設(shè)備的注射量、鎖模力等方面進行考慮，還有塑件的精度等級確定采用一模一腔。同時確保塑件及澆注系統(tǒng)所需的注射量不超過注射機最大容量的80％。
接著確定模具總體模具結(jié)構(gòu)形式。根據(jù)所選用的模具結(jié)構(gòu)形式，確定其定模、動模結(jié)構(gòu)。此制品外形簡單，尺寸較大，應考慮既節(jié)省材料，減輕模具重量，又使模具結(jié)實，故作如下分析：
A、模具呈圓形，動、定模直接由導柱連接，用錐面配合保證同軸度。此模具在三個角上為導柱空出位置，結(jié)構(gòu)合理。
B、該模具采用多段水冷卻，型腔四周雖在冷卻水孔處應力集中，但孔徑小。再者，動模受力均勻，不易應注射壓力而變形，模具結(jié)構(gòu)合理。
C.對各個系統(tǒng)進行設(shè)計，首先是澆注系統(tǒng)。根據(jù)所選用定模及動模模塊及定模板尺寸、模具的類型、型腔的類型、型腔的數(shù)目、布置、成型零件型腔尺寸、形狀及塑料型號等因素，確定澆注系統(tǒng)形式。
模具設(shè)計完成后，進行型腔的加工工藝分析，在確定加工工藝步驟后，在Cimatron中進行刀具路徑設(shè)定完成仿真加工，而后輸出數(shù)控程序。
3具體設(shè)計說明
3.1 塑件的測繪
塑件為塑料提桶，材料為ABS，用游標卡尺對零件進行測繪。我們最終所需要加工得到的是制造此零件的模具型腔，由于制造的原因，塑件在出模后不可避免的會產(chǎn)生一定的變形，因此對該零件的測量數(shù)值需要進行分析處理。如對塑件較大尺寸誤差的進行修正，對相同形狀處所測不同尺寸的取均值進行圓整，然后繪出零件的草圖。由于條件限制所以采用多次取斷面進行測量的辦法。
用游標卡尺（0～300、0.02），曲線測量儀等測量。測繪過程中必須把被測物體放在工作平面上，采用多次測量求平均值，正確地讀取數(shù)據(jù)。
測量的主要尺寸如下圖：
圖3-1 塑件制品圖
3.2 塑件的造型
零件測繪草圖出來以后，應該根據(jù)零件的測繪圖，對零件的進行三維造型。三維造型可以選用Pro／E軟件，三維造型的所有參數(shù)與測繪的數(shù)據(jù)一致。首先打開三維軟件Pro／E，進入零件設(shè)計界面，點擊草繪拉伸命令，然后在豎直面內(nèi)畫塑料提桶的中間截面的斷面圖，點擊旋轉(zhuǎn)命令繪制三維圖形，由于該塑件大都是曲面都是圓滑過渡所以在三維造型中要使用倒圓角命令。該塑件大都是曲面所以三維造型有一定的困難。要正確的繪制出該塑件的造型圖必須熟練掌握Pro／E的繪圖命令。
由Pro／E軟件的計算功能得塑件尺寸為：
該塑件口徑為270mm，高度為240mm，壁厚為2mm.
根據(jù)上述的方法繪制的制品的三維造型如圖3-1所示：
圖3-2 塑件三維造型
3.3塑件材料性能分析
塑料模具結(jié)構(gòu)比較復雜，組成一套模具的零件數(shù)目較多，而且由于各零件在工作中所處的地位、作用不同，對材料的性能要求也不同?？偟恼f來，用于制作塑料模具的材料，在質(zhì)量上首先要求具有一定的硬度和耐磨性，其次是有一定的強度和韌性，再次是易于加工。因此，應根據(jù)模具的結(jié)構(gòu)、性能要求和使用條件、模具的制造方法，合理地選用模具材料。根據(jù)文獻[5]中的P546，模具中各個零件的材料選擇如下：
A．導向零件的材料選擇 包括導套和導柱，由于在開、合模時有相對運動，成型過程中要承受一定的壓力，或偏載負荷，如導柱、導套與斜導柱等部件, 根據(jù)一軟一硬的原則, 保證硬度。因此要求表面耐磨性好，心部具有一定的韌性，本設(shè)計中的導向零件選用T8A，經(jīng)過滲碳淬火后表面硬度應達到50-55HRC；
B．澆注系統(tǒng)零件的材料選擇 本設(shè)計中的澆注系統(tǒng)零件選用T8A，經(jīng)過滲碳淬火后表面硬度應達到50-55HRC；塑件材料ABS，密度取1.01g/ cm3，脫模斜度取1°，ABS收縮率（0.3～0.8）%，取0.5% 。
C．模體零件的材料選擇 包括各種動、定模板、型腔、型芯等，這些零件要求具有足夠的機械強度，在本設(shè)計中選用45鋼，經(jīng)淬火處理后表面硬度達到40-45HRC，可滿足上述要求；
D．定位零件的材料選擇 包括定位圈和螺釘，要求其具有足夠的機械強度，耐磨性好，考慮上述要求，定位圈選用T8A，并表面淬火使硬度達到50-55HRC；螺釘選用45鋼。
3.4塑件的結(jié)構(gòu)分析
該塑件口徑為270mm，高度為240mm，壁厚為2mm。對于這種大型薄壁塑件模具，設(shè)計之前對塑件圖紙進行分析，認為在生產(chǎn)過程中可能會產(chǎn)生下列問題:
A．由于腔深、型芯長,可能會因型腔、型芯不同心而造成塑件壁厚薄不均,從而造成成型困難,廢品率高。這一點對于薄壁桶體尤為重要。
B．該模具僅型腔、型芯裝配后尺寸約為560X413mm,屬于大型模具，因此必須有良好的冷卻系統(tǒng)，以保證塑件不變形，提高生產(chǎn)率。
C．型芯表面積2092cm2,根據(jù)公式計算，初始包緊力約為18.3噸，頂出時很可能使塑件產(chǎn)生裂紋或變形。
D．脫模時型芯外可能形成真空，增大脫模力。
由于模具尺寸較大,設(shè)計時動、定模以導柱定位,以確保型芯、型腔的同軸度。
3.5型腔數(shù)的確定
型腔的數(shù)量是由給定的注塑機型號XS—ZY—500來確定的 ，并且從塑件的尺寸精度考慮，由于該制品精度等級6所以型腔數(shù)控制在一腔，并且零件是塑料提桶，體積大，大批量生產(chǎn)，從注塑經(jīng)濟效益出發(fā)來確定。
熱塑性塑料注射機型號：XS—ZY—500
具體參數(shù)如下表：
表3-1 注塑機參數(shù)
型號
XS—ZY—500
螺桿（柱塞）直徑／mm
65
注射容量/ cm3
665
注射壓力/( 105Pa)
104
鎖模力/(kN)
3500
最大注射面積/ cm2
1000
模具厚度
最大/mm
450
最小/mm
450
模板行程/mm
300
噴嘴
孔直徑/mm
6
球半徑/mm
18
定位孔直徑/mm
100
注射時間s
1.6
動，定模固定板尺寸mm
630
以機床的注塑能力為基礎(chǔ)，每次注射量不超過注射機最大注射量的80%。該塑件外形簡單，尺寸較大，故采用一模一腔的形式。
3.6 澆口位置選擇
模具設(shè)計時，澆口的位置及尺寸要求比較嚴格，初步試模后還需進一步修改澆口尺寸，無論采用何種澆口，其開設(shè)位置對塑件成型性能及質(zhì)量影響很大，因此合理選擇澆口的開設(shè)位置是提高質(zhì)量的重要環(huán)節(jié)，同時澆口位置的不同還影響模具結(jié)構(gòu)?？傊顾芗哂辛己玫男阅芘c外表，一定要認真考慮澆口位置的選擇，通常要考慮以下幾項原則：
A．避免制件上產(chǎn)生噴射等缺陷 澆口應開設(shè)在塑件截面最厚處，當塑件壁厚相差較大時，在避免噴射的前提下，澆口開設(shè)在塑件截面的最厚處，以利于熔體流動、排氣和補料，避免產(chǎn)生縮孔或表面凹陷。
B．有利于型腔排氣 在澆口位置確定以后，應在型腔最后充填處或遠離澆口的部位，開設(shè)排氣槽；或利用分型面、推桿間隙等模內(nèi)的活動部分排氣。
C．考慮塑件使用時的載荷狀況 通常澆口位置不能設(shè)置在塑件承受彎曲載荷或受沖擊力的部位，原因在于塑件澆口附近殘余應力大，強度差，一般能承受拉應力，不能承受彎曲應力和沖擊力。
D．考慮澆口位置和數(shù)目對塑件成型尺寸的影響 平板形塑件翹曲變形的原因在于垂直和平行于流動方向上的收縮率不同而致。
E．防止將型芯或嵌件擠歪變形 對于有細長型芯的圓筒形塑件，或有嵌件的塑件，應避免偏心進料，以防止型芯或嵌件被擠壓移位或變形，導致塑件壁厚薄不均，或塑件脫模損壞。
根據(jù)本塑件的特征，綜合考慮以上幾項原則，確定澆口位置選在塑件的底部。
3.7澆口結(jié)構(gòu)形式的選擇
澆口結(jié)構(gòu)形式很多，常用的主要有直接澆口、點澆口、側(cè)澆口三種。
A. 直接澆口 直接澆口是主流道澆口套直接成形的澆口，它不經(jīng)過分流道、支流道，因此流程短，注射壓力損失少，任何材料都能容易成型，易用于一模單腔的大而深得制品。
B.側(cè)澆口 側(cè)澆口的澆口可隨意選擇進料位置，澆口的寬度及深度在試模后可加深、加寬便于修正，但流程長，易產(chǎn)生氣泡，影響塑件質(zhì)量。
C.點澆口 點澆口一般設(shè)在型腔底部，排氣通暢，成型良好，塑件無不良痕跡。
該塑件結(jié)構(gòu)簡單、一模單腔、口徑大高度深，確定澆口采用直接澆口。
3.8澆口尺寸的確定
澆口的截面積一般為分流道截面積的3%～9%，截面形狀多為矩形（寬度與厚度的比為3：1）或圓形。在設(shè)計澆口時，應取較小值，以便在試模時加以逐步修正。根據(jù)本塑件的特征，綜合考慮以上幾項原則，確定采用直接澆口。
表3-2 直澆口主流道參考尺寸
制品大小
小制品
一般制品
大制品
主流道直徑
d
D
d
D
d
D
ABS
2.5
5
3
6
4
8
3.9澆注系統(tǒng)的平衡
對于中小型塑件的注射模具己廣泛使用一模多腔的形式，設(shè)計應盡量保證所有的型腔同時得到均勻的充填和成型。一般在塑件形狀及模具結(jié)構(gòu)允許的情況下，應將從主流道到各個型腔的分流道設(shè)計成長度相等、形狀及截面尺寸相同（型腔布局為平衡式）的形式，否則就需要通過調(diào)節(jié)澆口尺寸使各澆口的流量及成型工藝條件達到一致，這就是澆注系統(tǒng)的平衡。顯然，我們設(shè)計的模具是平衡式的，即從主流道到各個型腔的分流道的長度相等，形狀及截面尺寸都相同。
3.10分型面的設(shè)計
分型面的選擇應使塑件在開模后留在有脫模機構(gòu)的部分，一般應留在動模部位，以便于脫模。設(shè)計分型面時，盡量要避開斜面及曲面以便于加工，并盡量避免側(cè)向抽芯和側(cè)向分型。如塑件有側(cè)凹及側(cè)孔必須采用側(cè)向及側(cè)向抽芯時，應使側(cè)抽芯盡可能安放在動模上，而避免在定模抽芯。對于有同軸度要求的塑件在設(shè)計時盡可能將型腔設(shè)計在同一型面上。以保證制品精度。
該塑件的分型面如圖所示:
圖3-3 分型面位置
初步確定了分型面后，用Pro／E軟件建立分型面。主要有以下幾個步驟：
a．首先打開Pro／E，調(diào)入模具參考模型，在菜單欄中選取【新建】——【制造】——【模具型腔】——【裝配】，裝配已畫的零件圖。
b．設(shè)置收縮率，在菜單管理器中選取【收縮】——【按尺寸】——【設(shè)置/復位】——【所有尺寸】輸入ABS的平均收縮率0.005，單擊完成。
c．設(shè)計毛坯工件，在菜單管理器中選取【模具模型】——【創(chuàng)建】——【工件】——【手動】單擊確定。選擇【創(chuàng)建特征】，在菜單管理器中選取【實體】——【加材料】——【拉伸】——【實體】——【完成】進入草繪部分進行繪制。
d．設(shè)計分型面，利用菜單管理器中【分型面】的子選項進行分型面的創(chuàng)建和修改。
3.11 主流道的設(shè)計
主流道為從注射機噴嘴開始到分流為止的熔融塑料的流動通道。它與注射機噴嘴在同一直線上。主流道的基本尺寸通常取決于兩個方面：第一個方面是所使用的塑料種類，所成型的制品質(zhì)量和壁厚大小。關(guān)于主流道的基本尺寸的選定參考下表：
表3-3主流道直徑參考表
制品質(zhì)量/g
D/mm
R/mm
0～20
3
0.5
20～40
4
1
40～150
5
1
150～300
6
2
300～500
8
2
500～1500
10
2
為防止注射機噴嘴與澆口兩部分相接觸處由于有間隙而產(chǎn)生的溢料，澆口套的球半徑應比噴嘴的球半徑大2mm～5mm，主流道的小端尺寸應比噴嘴孔尺寸稍大，這樣可以使噴嘴與澆口對位容易。本模具設(shè)計采用的注射機是XS－ZY－500，其噴嘴球徑為6mm，取澆口套的球半徑為18mm。另外，為使?jié)部谔字械乃芰先菀酌撾x主流道，應設(shè)有脫模斜度，這個斜度一般最小不小于1°，最大不超過4°。主流道的脫模斜度不能過大，否則在注塑時會產(chǎn)生渦流和流速過慢等現(xiàn)象。主流道應保持光滑的表面，避免留有影響塑料流動和脫模的尖角毛刺等。
圖3-4 主流道的幾何關(guān)系
3.12冷卻系統(tǒng)設(shè)計
模具設(shè)計冷卻裝置的目的，一是防止塑件脫模變形；二是縮短成型周期；三是使結(jié)晶性塑料冷凝形成較低的結(jié)晶度，以得到柔軟性、擾曲性、伸長率較好的塑件。冷卻形式一般在型腔、型芯等部位合理地設(shè)置通水冷卻水路，并通過調(diào)節(jié)冷卻水流量及流速來控制模溫。冷卻水一般為室溫冷水，必要時也有采用強迫通水或低溫水來加強冷卻效率。冷卻系統(tǒng)的設(shè)計對塑料質(zhì)量及成型效率直接有關(guān)，尤其在高速、自動成型時更應注意。
A. 設(shè)計冷卻管道考慮因素：
a. 模具結(jié)構(gòu)形式，如普通模具、細長型芯的模具及脫模機構(gòu)障礙多的或鑲塊多的模具，對冷卻系統(tǒng)設(shè)計直接有關(guān)；
b. 模具的大小和冷卻面積；
c. 塑件熔接痕位置；
B. 冷卻水孔的開設(shè)原則：
a. 邊離型腔的距離一般保持在15～25mm，距離太近則冷卻不宜均勻，太遠則效率低。水孔直徑一般在8mm以上，根據(jù)模具大?。ㄋ芗亓浚Q定；
b. 孔通過鑲塊時，應該考慮鑲套管等密封問題；
c. 孔管路應暢通無阻；
e. 管接頭（冷卻水嘴）的位置盡可能放置在不影響操作的一側(cè)；
f. 冷卻水孔管路最好不開設(shè)在型腔塑料熔接的地方，以免影響塑件強度；
本模具采用一模一腔結(jié)構(gòu)，為使各個塑件都能均勻冷卻。采用多段冷卻及多處獨立冷卻系統(tǒng)。如圖所示：
圖3-5模具主視圖
圖3-5模具左視圖
型腔、型芯的冷卻設(shè)計：
A．型腔：由于型腔體積達560X304mm,設(shè)計時在桶身部分高度上采用了六排獨立冷卻系統(tǒng)。在用以成型的定模鑲件上，采用環(huán)型水道冷卻，水流的進出口設(shè)計在定模固定板上，鑲件與定模固定板之間由橡膠密封圈密封。
B．型芯：型芯冷卻采用中間有一主水道進水，然后沿周圍均布分成6個分水道出水，從而使型芯各處得到充分冷卻，整個模具的溫度場比較均勻。
3.13導向裝置
導向裝置的作用是：當動模與定模合模時，導向裝置先進行導向，型腔與型芯再合模，這樣可避免型芯與型腔發(fā)生碰撞而損壞。同時，保證了型芯及型腔的相對位置，兼起定位作用及承受一定的側(cè)壓力作用。導向裝置包括兩個部件，即導柱和導套，導柱一般安裝在動模上，導套安裝在定模上。有時，也可將導柱安裝定模上，導套安裝在動模上，或在動模上設(shè)計導套孔，用導柱直接導向。在本設(shè)計中，導套安裝在定模上，導柱安裝在動模上，在合模時進行導向定位。導柱和導套的孔徑設(shè)計時最好一致，這樣容易在裝配時，保證尺寸及同軸度尺寸精度。
3.14頂出系統(tǒng)設(shè)計
塑件在模具中冷卻定型時，由于熱收縮其體積和尺寸逐漸縮小，在塑料的uyu哦溫度以前熱收縮并不造成對型芯包緊力，但制品固化后繼續(xù)降溫則會對型芯產(chǎn)生包緊力，包緊力帶來的正壓力，垂直于型芯表面，脫模溫度越低正壓力越大，脫模時必須克服該包緊力所產(chǎn)生的摩擦力。
注射模具的頂出系統(tǒng)是制品的脫模裝置。在設(shè)置頂出系統(tǒng)時，首先需要確定當模具開啟后，制品的留模形式，頂出系統(tǒng)必須是建立在制品所滯留的模具部分中。
A．由于本模具若采用常規(guī)的機械頂出機構(gòu)，將會大大增加模具高度，無法與機床的裝模高度，最大行程匹配，因此設(shè)計了氣動頂出裝置。開模時由氣道進壓縮空氣，推動氣動閥，使塑件頂出一定的距離，然后由機械手取下塑件。同時，由于采用氣動頂出，可以破壞型芯外的真空，使其易于脫模。
B．由于冷卻系統(tǒng)及氣動頂出的需要，型芯設(shè)計成上下兩段。氣動頂出閥裝設(shè)計在型芯鑲件上，進氣道設(shè)計在動模固定板上。
C．在定模鑲件上也設(shè)計了兩個氣動頂出閥，以免塑件留在型腔內(nèi)。進氣道設(shè)計在定模固定板上。
D．為克服包緊力過大造成的頂出困難，在型芯鑲件與型芯主體的結(jié)合面上，設(shè)計了環(huán)型氣槽，并在端面沿周圍均勻開設(shè)了寬12mm、深0.8mm的氣隙,進氣道設(shè)在型芯主體上,與氣動頂出同時給氣。如圖3-6所示。
3.15 側(cè)抽芯的設(shè)計
側(cè)向抽芯用于有側(cè)孔的塑件，根據(jù)側(cè)孔的數(shù)量和方位設(shè)置一至多個側(cè)抽芯，用側(cè)向抽芯機構(gòu)抽出側(cè)型芯。
側(cè)向分型與抽芯方式一般分為：手動、機動、液壓或氣動分型抽芯。本模具設(shè)計中選用機械側(cè)向分型抽芯機構(gòu)中的氣動抽芯機構(gòu)。側(cè)芯在動模一邊，開模后，首先由氣缸抽出側(cè)芯，然后再頂出塑件，頂出系統(tǒng)復位后，側(cè)芯再復位。如圖3-7所示。
圖3-6型芯上鑲件
圖3-7側(cè)抽芯機構(gòu)
3.16確定各模板尺寸
模板各部分結(jié)構(gòu)尺寸如表3-4所示：
表3-4 模板各部分主要結(jié)構(gòu)尺寸
1
定模固定板
長 ×寬×厚
630mm ×40mm
2
定模鑲件
長 ×寬×厚
246mm ×65mm
3
型芯上鑲件
長 ×寬×厚
210mm ×68mm
4
型芯主體
長 ×寬×厚
410mm ×560mm
5
型腔
長 ×寬×厚
410mm×560mm
6
動模固定板
長 ×寬×厚
630mm ×40mm
根據(jù)上述的設(shè)計，最后設(shè)計出的模具的總裝圖如下：
圖3-8模具三維總裝圖
圖3-9模具三維爆炸圖
3.17凸、凹模結(jié)構(gòu)形式
對于極為簡單的形狀可以采用整體式的凸?；虬寄Ｍ?，往往采用拼鑲方法組合成凸?；虬寄?。
圖3-10模具凸模
圖3-11模具凹模
3.18加工零件工藝審查
A. 零件結(jié)構(gòu)特點：
該零件是注塑模的型腔，矩形外表面和動模板配合，型腔結(jié)構(gòu)以曲面為主加工比較復雜。由于型芯在注塑時需要承受一定的壓力和溫度，故該零件需要有足夠的強度、剛度、耐磨性和韌性。
B. 主要技術(shù)要求：
零件圖上的主要技術(shù)要求有：a. 熱處理：HB230～270；b. 銳角去毛刺倒鈍；c. 未注圓角R=0.25mm；d. 孔與基準C的垂直度公差等級為7級。
加工表面及其要求:矩形配合面的表面粗糙度Ra=1.6μm、與基準A的垂直度公差為0.01mm；分模面的平面度公差為0.01mm，與基準A的平行度公差為0.015mm；內(nèi)輪廓表面的粗糙度為Ra=0.8μm。
C. 零件材料：
由于大批量生產(chǎn)及型腔結(jié)構(gòu)簡單，成型零件的材料選用模具鋼45。
D．毛坯的選擇：
考慮到零件所需的性能，選用鑄件作毛坯；確定毛坯的形狀、尺寸：選用模具鋼45鑄件650×520（mm）；
3.19基準選擇
加工中心的一次裝夾希望能夠進行在該基準下的全部加工，這樣可以降低由于基準不重合而導致的基準不重合度誤差。根據(jù)對工件的加工的初步分析在毛坯的初次裝夾后可以完成加工，故選用毛坯的初始輪廓面為裝夾基準。
4．Cimatron仿真加工
Cimatron工作環(huán)境是專門針對模具行業(yè)設(shè)計開發(fā)的，可以說是一個高級的模具設(shè)計制造軟件。它支持實體，曲面和線框混合造型，使模具設(shè)計者輕松導入數(shù)據(jù)和創(chuàng)建零件的概念設(shè)計。
4.1設(shè)計步驟
1.打開CAD文件
打開cimatron E7.0后，在主菜單上選擇“文件”-“打開文檔”，在cimatron E7.0瀏覽器中選擇凹模，打開文件后，在CAD方式下檢驗模型的完整性。
2.進入CAM編程模塊
（1）輸出到CAM主菜單上選擇“文件”-“輸出”-“到加工”。將當前文件作為加工模型輸出到CAM方式。
（2）確認模型放置位置。進入加工模塊后，模型的放置位置和旋轉(zhuǎn)角度按默認方式，即直接放置到坐標系的原點，同時不做旋轉(zhuǎn)。在特征向?qū)谥袉螕簟按_定”按鈕完成模型放置。
3.放置刀具
單擊屏幕左側(cè)的編程向?qū)l中的“刀具”按鈕，進入新建刀具功能，屏幕上會出現(xiàn)“刀具和卡頭”對話框，在對話框中單擊“新建刀具”按鈕，如圖所示
圖4-1刀具的選擇
4.新建刀具軌跡
單擊屏幕左側(cè)的編程向?qū)l中的“新建刀具軌跡”按鈕進入刀具新建軌跡功能，屏幕上會彈出“創(chuàng)建刀具軌跡對話框” 窗口內(nèi)定義新建的刀路軌跡的名稱與坐標系及安全平面高度。
圖4-2 刀具軌跡的選擇
5.開始創(chuàng)建程序
單擊在屏幕左側(cè)的編程向?qū)l中的“創(chuàng)建程序”按鈕，開始創(chuàng)建程序，此時屏幕上的向?qū)l改變成程序向?qū)l。如圖所示
圖4-3 程序的創(chuàng)建
6.選擇工藝
在上圖對話框中，主選項選擇2.5軸加工，子選項中選擇素材環(huán)切
7.選擇加工對象
刀具確定后，會切換到加工對象功能下。單擊“工件輪廓”數(shù)量按鈕進行曲面選擇，在彈出的對話中設(shè)置參數(shù)
8.設(shè)置刀路參數(shù)
圖4-4 刀具參數(shù)的設(shè)置
圖4-5刀具參數(shù)的設(shè)置
圖4-6 刀具參數(shù)的設(shè)置
圖4-7 刀具參數(shù)的設(shè)置
圖4-8 刀具參數(shù)的設(shè)置
圖4-9 刀具參數(shù)的設(shè)置
9.設(shè)置機床參數(shù)
圖4-10 刀具參數(shù)的設(shè)置
10.單擊保存并計算
圖4-11 毛坯
圖4-12 凹模
5 結(jié)論
這次為期三個多月的畢業(yè)設(shè)計已接近尾聲，在這段時間里我結(jié)合設(shè)計課題和設(shè)計任務書的要求，首先進行畢業(yè)實習，在工廠中對模具結(jié)構(gòu)有了理性的認識，對模具設(shè)計奠定了基礎(chǔ)，同時對塑料模具設(shè)計和制造進行文獻檢索，了解模具的現(xiàn)狀和發(fā)展趨勢，并制定了設(shè)計方案和計劃。
按照畢業(yè)進度安排，我先對塑件進行測繪，確定尺寸精度和加工要求，并對其進行加工工藝分析，確定了各個零件之間的關(guān)系，對模具整體按照設(shè)計手冊進行設(shè)計計算，取得各個零件的設(shè)計參數(shù)，繪制了模具裝配圖。最后實現(xiàn)型腔的仿真加工。
通過這次畢業(yè)設(shè)計我對模具結(jié)構(gòu)有了清楚的認識，了解了注塑模具的工作方式，對型腔、型芯等主要零件的設(shè)計及要求有了初步知識。能夠?qū)δ＞咴O(shè)計中出現(xiàn)的問題予以解決，正確選取了型腔數(shù)、模具結(jié)構(gòu)尺寸。在模具設(shè)計中，精度要求的確定是至關(guān)重要的一步，要綜合考慮尺寸精度及配合要求，特別是各模板及型腔、型芯等配合精度要求高的部件，其精度確定的合理與否將影響到塑件的質(zhì)量，從而對產(chǎn)品的使用性能及企業(yè)的經(jīng)濟效益產(chǎn)生很大的影響。
在設(shè)計中由于使用最新的模具設(shè)計軟件是工作效率大大提高，并且提高了模具結(jié)構(gòu)的合理性。但由于實踐工程經(jīng)驗的欠缺，在設(shè)計中對零件的加工精度和成型零件的加工工藝的確定由很多不足之處，在以后的工作學習中還有待改進。
參 考 資 料
[1]王衛(wèi)兵.Cimatron E 模具設(shè)計與數(shù)控編程實例教程.北京：清華大學出版社，2003-7.
[2] 陸錦明，黃仕勇，陳江虎. Cimatron E7.1軟件在模具數(shù)控加工中的應用[J] .模具制造，2007，（7）：61-63.
[3]曹德權(quán)，唐定勇.Pro/ENGINEER Wildfire 4.0 中文曲面與逆向工程設(shè)計.北京：電子工業(yè)出版社，2004-10.
[4]王樹勛，蘇樹珊.模具實用技術(shù)設(shè)計綜合手冊.廣州：華南理工大學出版社，2003-6
[5]陳靜媛. 模具行業(yè)設(shè)計制造現(xiàn)狀與趨勢[J].機械設(shè)計與制造，2007（02）：174-175.
[5]洪慎章. 現(xiàn)代模具技術(shù)的現(xiàn)狀及發(fā)展趨勢[J] . 航空制造技術(shù)，2006，（6）：1-3.
[6]何博.Pro/ENGINEER Wildfire 實用速成教程.北京：中國電力出版社，2004-4.
[7]黃毅宏.模具制造工藝[Ｍ].北京：機械工業(yè)出版社,1995．
[8]宜凱得科技，張祥杰，黃圣杰.Pro/ENGINEER Wildfire 模具設(shè)計.北京：中國鐵道出版社，2004-6.
[9]許越樾.實用模具設(shè)計與制造手冊.北京：機械工業(yè)出版社，2005-10.
[10]陳孝康，陳炎嗣，周興隆.實用模具技術(shù)手冊.北京：中國輕工業(yè)出版社，2001-1.
[11]林清安.Pro/ENGINNER Wildfire4.0 模具設(shè)計.北京：電子工業(yè)出版社，2005-4.
[12]申開智.塑料成型模具.北京：中國輕工業(yè)出版社，2002-9.
[13]李云程.模具制造工藝學.北京：機械工業(yè)出版社，2000-10.
致 謝
本人在這次畢業(yè)設(shè)計中，充分利用這四年所學習的專業(yè)知識和平時自學的軟件應用，特別是在工程領(lǐng)域分析問題，解決問題的方法。通過這次畢業(yè)設(shè)計使我對Pro/E、Cimatron E有了進一步的掌握，對于使用Pro/E三維造型和使用Cimatron制作模架感到很是方便，對其中“塑料顧問”模塊有的新的認識，通過這個模塊在先前就可以了解到制品注射成型后的質(zhì)量是否達到設(shè)計要求，對于使用Cimatron進行仿真加工和數(shù)控編程中的實際加工問題進行了分析，對于AUTO CAD有的使用進一步的練習。在使用過程中對這些應用軟件的優(yōu)缺點有了很深的印象，充分利用它們的優(yōu)點對我的設(shè)計幫助很大，不僅效率高了而且對工作質(zhì)量有很大的益處。
在本次塑料提桶模具設(shè)計中承蒙劉道標老師的悉心指導和幫助，在畢業(yè)設(shè)計過程中提供了很多寶貴的資料、設(shè)計和方向、設(shè)計思路，以及模具結(jié)構(gòu)原理方面的知識，在此向他表示衷心的感謝。因本人工程實踐經(jīng)驗與理論水平有限，時間較短促，設(shè)計過程中難免存在錯誤，請老師批評指正。
附 錄
序號 名稱 圖幅 數(shù)量
1 模具裝配圖 A0 1
2 導套 A4 1
3 導柱 A4 1
4 定模固定板 A3 1
5 定模鑲件 A3 1
6 定位圈 A4 1
7 動模固定板 A3 1
8 型腔 A3 1
9 型芯上鑲件 A3 1
10 型芯主體 A3 1
11 彈簧 A3 1
12 堵塞 A3 1
13 三維圖冊 1 冊
14 數(shù)控代碼 1 冊
15 加工工藝過程卡 1 冊
16 加工工序卡 1 冊
27
International Journal of CAD/CAM Vol. 2, No. 1, pp. 6975 (2002) An Intelligent Cavity Layout Design System for Injection Moulds Weigang Hu and Syed Masood* Industrial Research Institute Swinburne (IRIS), Swinburne University of Technology, Hawthorn, Melbourne, Australia 3122 Abstract This paper presents the development of an Intelligent Cavity Layout Design System (ICLDS) for multiple cavity injection moulds. The system is intended to assist mould designers in cavity layout design at concept design stage. The complexities and principles of cavity layout design as well as various dependencies in injection mould design are introduced. The knowledge in cavity layout design is summarized and classified. The functionality, the overall structure and general process of ICLDS are explained. The paper also discusses such issues as knowledge representation and case-based reasoning used in the development of the system. The functionality of the system is illustrated with an example of cavity layout design problem. Keywords: Intelligent design, cavity layout design, injection mould design, case-based reasoning, design support system 1. Introduction In manufacturing, the injection moulding is one of the most widely used production processes for producing plastic parts with high production rate and little or no finishing required on plastic products. The process consists of injecting molten plastic material from a hot chamber into a closed mould, allowing the plastic to cool and solidify and ejecting the finished product from the mould. For each new plastic product, the injection moulding machine requires a new injection mould. Design and manufacture of injection mould is a time consuming and expensive process and traditionally requires highly skilled tool and mould makers. An injection mould consists of several components, which include mould base, cavities, guide pins, a sprue, runners, gates, cooling water channels, support plates, slides and ejector mechanism 1. Design of mould is also affected by several other factors such as part geometry, mould material, parting line and number of cavities per mould. With the advances in computer technology and artificial intelligence, efforts have been directed to reduce the cost and lead time in the design and manufacture of an injection mould. Injection mould design has been the main area of research since it is a complex process involving several sub-designs related to various com- ponents of the mould, each requiring expert knowledge and experience. Mould design also affects the productivity, mould maintenance cost, manufacturability of mould, and the quality of the moulded part. Most of the work expert systems, knowledge based systems and artificial intelligence to eliminate or supplement the vast amount of human expertise required in traditional design process. Kruth and Willems 2 developed an intelligent support system for the design of injection moulds integrating commercial CAD/CAM, a relational database and an expert system. Lee et. al. 3 proposed a systematic methodology and knowledge base for injection mould design in a concurrent engineering environment. Ra- viwongse and Allada 4 developed a neural network- based design support tool to compute the mould complexity index to help mould designers to assess their proposed mould design on mould manufacturability. Kwong and Smith 5 developed a computational system for the process design of injection moulding based on the blackboard-based expert system and the case-based reasoning approach, which includes mould design, production scheduling, cost estimation and determination of injection moulding parameters. Britton et. al. 6 discussed the injection mould design from a functional perspective using functional design knowledge and a number of knowledge libraries. Mok et. al. 7 developed an interactive knowledge-based CAD system for injection mould design incorporating computational, knowledge and graphic modules. Several studies have also been made on improving the design of specific components of an injection mould. Ong et. al. 8 developed a knowledge-based and object- oriented approach for the design of the feed system for injection moulds, which can efficiently design the type, in mould design has been directed to the application of location and size of a gating system in the mould. Irani et. al. 9 also developed a software system for automatic design of gating and runner systems for injection moulds and provide evaluation of gating design based on specified performance parameters. Nee et. al. 10 proposed a methodology for determination of optimal *Corresponding author: Tel : +61-3-9214-8260 Fax : +61-3-9214-5050 E-mail : Smasoodswin.edu.au G01G02 International Journal of CAD/CAM Vol. 2, No. 1, pp. 6975 parting directions in injection mould design based on automatic recognition and extraction of undercut features. Chen and Chou 11 developed algorithms for selecting a parting line in mould design by computing the undercut volumes and minimising the number of undercuts. Park and Kwon 12 worked on the design of cooling systems in injection moulds and proposed an optimal design based on thermal analysis and design sensitivity analysis of the cooling stage of the injection moulding process. Lin 13 worked on the use of gate size and gate position as the major parameters for simulated injection mould performance prediction. One area in injection mould design, which has received little attention, is the design of cavity layout in a multiple cavity injection mould. Cavity layout design affects the whole process of injection moulding directly, since it is one of the most important phases in mould design process. Consideration of cavity layout design in injection mould at concept design stage will improve the quality of injection moulded products because it is associated with the determination of many key factors affecting the design and quality of mould. Such factors include number of cavities; parting line; type of mould; type and position of gate; runner system; cooling system and ejection system. Some of these factors are difficult to build as true mathematical models for analysis and design. This paper presents the development of a design support system, called Intelligent Cavity Layout Design System (ICLDS), for multiple-cavity injection moulds based on knowledge based and object oriented approaches. It uses the case-based and ruled-based reasoning in arriving at the layout solution 14. It is based on the commercial software system named “RETE+”, which is an integrated development platform for customers to develop their own knowledge-based systems 15. The objective is to make full use of available techniques in artificial intelligence in assisting mould designers at concept design stage. 2. Cavity Layout Design in Injection Moulds Current practice for injection mould design, especially cavity layout design, depends largely on designers ex- periences and knowledge. It would therefore be desirable to use knowledge engineering, artificial intelligence and intelligent design techniques in generating an acceptable cavity layout design in injection mould accurately and efficiently. In mould design, most of patterns of cavity layout and rules and principles of cavity layout design can also be easily represented in the form of knowledge, which can be used in most of knowledge-based design systems. For example, for the layout patterns shown in Fig. 1, the criteria to select the suitable layout pattern for design are mainly dependent on working environments, conditions and requirements of customer and are mainly based on designers skill and experience. To make a choice of contradictory factors will rely obviously on designers knowledge and experiences. It is rather suitable for intelligent design techniques to be used in systems designed for such situations, especially for routine or innovation design. Design of injection mould mainly involves consideration of design of the following elements or sub-systems: (1) mould type (2) number of cavities Fig. 1. Some patterns of cavity layout with multiple cavities. Weigang Hu and Syed Masood An Intelligent Cavity Layout Design System for Injection Moulds G01G03 (3) cavity layout (4) runner system (5) ejector system (6) cooling system (7) venting (8) mounting mechanism Most of the elements are inter-dependent such that it is virtually impossible to produce a meaningful flow chart covering the whole mould design process. Some of the design activities form a complicated design network as shown in Fig. 2. Obviously, in injection mould design, it is difficult for designer to monitor all design parameters. Cavity design and layout directly affects most of other activities. The application of advanced knowledge based techniques to assist designer in cavity layout design at concept design stage will greatly assist in the development of a It is noted from Fig. 1 that a number of different layout patterns are possible with multiple cavities inside a mould. Higher the number of cavities of mould, higher the productivity of the injection mould. But this may lead to difficulties with issues such as balancing the runners or products with the complicated cavity shapes, which in turn may lead to problems of mould manufacturability. It is also possible that the number of cavities and the pattern of cavity layout will influence the determination of parting line, type of gate, position of gate, runner system and cooling system. Most of the main activities of mould design are therefore linked to cavity layout design. Fig. 3 shows the relations between cavity layout design and other design activities. The cavity layout design problem therefore depends upon a number of functionalities of the overall mould design system, which includes: Fig. 2. Design network of injection mould. comprehensive computer-aided injection mould design and manufacturing system. (1) definition of design specifications including analysis and description of characteristics of G01G04 International Journal of CAD/CAM Vol. 2, No. 1, pp. 6975 design problem (2) determination of mould type (3) determination of number of cavities (4) determination of orientation of product (5) determination of runner type and runner configuration (6) determination of type and position of gate (7) cavity layout conceptual design (8) evaluation of ejection ability, manufacturing ability and economic performances (9) determination of cooling system (10) graphic results display and output 3. Structure of ICLDS and the Design Process The structure of the Intelligent Cavity Layout Design System (ICLDS) is based on case-based reasoning and ruled-based reasoning designed around the RETE+ Fig. 3. Relationship diagram between cavity layout design and other modules of mould. Fig. 4. Overall structure of ICLDS. Fig. 5. The general design process of ICLDS. Weigang Hu and Syed Masood An Intelligent Cavity Layout Design System for Injection Moulds G01G05 software system. Fig. 4 shows the overall structure of ICLDS schematically. Fig. 5 shows the general design process of ICLDS. The design process starts with the definition of design specifications. The ICLDS system retrieves similar cases from case base by computing the similarity between the cases and the new case. If the solution is satisfactory, then results are displayed graphically. If the solution is not satisfactory, then ICLDS will use rule-based reasoning with forward or backward chaining or a mixture of both to arrive at a solution. If the solution is still unsatisfactory, then the user has to modify some of the initial design specifications. The use of case-based technology in the design process in ICLDS allows the user to obtain the solution(s) of design problem more quickly and flexibly. The structure of knowledge base and database used in the development of ICLDS is based on the underlying knowledge base and database structure from the RETE+ software system, which is a commercially available software development platform. 4. Development of ICLDS 4.1. Classifications of Knowledge For various logic and steps involved in layout design, there are different kinds of knowledge that needs to be described and represented in cavity layout design. The types of knowledge can be classified into five kinds based on object oriented (OO) concept as described below: (1) Design instance/case: previous design cases and current design instances (2) Relation: superclass-class-subclass relation, class- instance relation (3) Attribute: design variables, features, attributes of design problem (4) Rule: general design rules, design experiences (5) Procedure and/or model: numeric calculation, mathematical modeling, analysis, evaluation and procedures. 4.2. Knowledge Representations To describe each of these types of knowledge, the internal data structures of the ECLIPSE language, included in RETE+ inherently, can be used to make the object orientated representation of the design process as explained earlier. Some other considerations in knowledge representation are as follows: (1) For “design instance/case”, we combine “fact definition” and “relation definition” plus database and case base to represent it (2) The “attribute” are represented as instances of “template definition” and/or “relation definition” (3) For “relation”, we use “relation definition” to describe it (5) The “procedure/model” are defined by external routines using C+ language Furthermore, “goal definition” and “goal generation” techniques are used to fulfil backward chaining reasoning, and “case-based reasoning” is used to carry out case- based design. 4.3. Case-based Reasoning Case-Based Reasoning (CBR) is dependent firstly on case retrieved. Case-based retrieval is based on “Similarity Metric”. Therefore, how to calculate the similarity is obviously the key technique in CBR, and it is described in detail as below. Similarity metric is a weighted distance function in a multi-dimensional space where each dimension corresponds to a field whose value is specified in the query (new case) and which has a non-missing value in the case being ranked. The distance between the case and the query (which corresponds to a point in this multi-dimensional space) is computed differently for ordinal and nominal fields. An ordinal field is a field whose values are ordered or sorted. A nominal field is one whose values represent qualitative information for which sorting makes no sense. In general, ordinal fields include dates, integers, and real numbers while nominal fields include Boolean, Symbols, and Text. 4.3.1. Ordinal Distance For ordinal fields the distance, d ij , between the i-th cases value, v ij , and the querys value, V j , for the j-th field, is computed as: (1) where the maximum and minimum values for each field are determined during index construction. Since d ij represents the distance along the j-th axis of an n-dimensional similarity space, the similarity space distance D i is given by: (2) which, since d ij must range between 0 and 1, must also range between 0 and 1. When weights are used, the above equation becomes: (3) which, since W j and d ij must range between 0 and 1, must also range between 0 and 1. d ij v ij V j V j max V j min -= D i j 1= N d ij 2 N -= D i j 1= N W j d ij () 2 j 1= N W j -= (4) For “rule”, we combine “rule definition” and “rule set definition” to represent it 4.3.2. Nominal Distance for Text To determine the distance between the value of a G01G06 International Journal of CAD/CAM Vol. 2, No. 1, pp. 6975 TEXT field in a case and that specified in a query, we determine a weight for each term by which a text field is indexed and a weight for each term in the query. These weights are computed according to the following formula, where: (4) N is the number of cases. n k is the number of different cases in which term k occurs. F ik is the number of occurrences of term k in case i divided by the total number of terms in case i. W ik is the weight of the k-th term in case i. Let W k be the weight of the k-th term in the query, computed as in the above formula. Let T be the number of terms in the query. Given these weights, the similarity (expressed as a normalized distance) between two text fields is computed as : (5) 4.3.3. Nominal Distance for Symbols Symbols are merely a special case of text with only one term. The weights for symbol fields are computed as in the above equations for text fields with F ik always being one. Given these weights, the similarity is computed exactly as for text fields. 4.4. Validation of Case Validation of case is to check up whether each acceptable case is suitable for current problem and to find out the most suitable one, so each case should be associated with testing methods and tested results on it. Only the case, under the given conditions, for which all tested results on it match those of the current design problem, can be considered as the solution prototype for further refining. 4.5. Criteria for Validity of Cost Reduction With the application of ICLDS for cavity layout, two kinds of cost reduction can be expected. One is the overall theoretical cost reduction achieved in using the system to carry out the conceptual design of injection moulds. The other is the practical cost reduction value recorded in the case base which may be used to do the case-base reasoning if the case has the “cost reduction” attribute. For the theoretical one, there is no need of any criteria for validity of cost reduction because the cost savings will obviously come out through lead time the criterion of comparison can be used. For example, we can compare the “cost reduction” attributes for two cases and determine which one provides better fit for the customers requirements. One can use the percentage cost reduction formula to do the comparison. The percentage cost reduction can be calculated by the formula: Cost Reduction=(previous cost-current cost)/previous cost It is better first to work out the percentage for the cost reduction attributes and then do the validation of case between the cases. 5. Example of Application An application example, “determination of cavity layout pattern” of the “conceptual design for cavity layout” provided by Intelligent Cavity Layout Design System (ICLDS) is given below: If the initial design conditions are: (1) What type of mould is used? Two plate (2) What type of runner is used? Cold runner (3) How many cavities are there in mould? 6 (4) How long is it required for product to clear the moulding area? Small (5) What shape of product does moulding make? Rectangle Then the result is given by: (this is shown in Fig. 6) Pattern of cavity layout design is: Y-Rectangular-Layout The knowledge base is developed using features of ECLIPSE language, such as defrelation, deftemplate, defruleset, and goal generation. Part of the program, which describes the overall format of knowledge base development, is listed below: . . . . . . (defrelation dimension (?item ?size) (defrelation layout (?item ?type) . . . . . . (defruleset Runner_system 10 (agenda body) . . . . . . (defruleset cavity_layout 8 (agenda body 2) . . . . . . W ik F ik Log n k N() j 1= N F ij Log n j N()() 2 -= S i k 1= T W ik W k k 1= T W ik () 2 k 1= T W k () 2 -= saving, improvement in design quality and quick response to customers. For the validity of practical cost reduction, Fig. 6. Graphic result of pattern of 6-cavity layout- “Y-style runners”. Weigang Hu and Syed Masood An Intelligent Cavity Layout Design System for Injection Moulds G01G07 (defruleset cavity_layout (agenda body) (defrule goal_cavity_layout (initial-fact) (goal (selection layout_designed ?yesno) (unknown (selection layout_designed ?yesno) (not (layout cavity ?type) = (printout t . Waiting! Waiting! Waiting! . t) . . . . . (defrule cavity_layout2_2_01 (goal (layout cavity ?type) (unknown (layout cavity ?type) (known (quantity number_of_plate 2) (known (quality type_of_runner cold_runner) (k