化妝品噴頭塑料注塑模具設(shè)計(jì)【一模十六腔】【側(cè)抽芯】【說明書+CAD】
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畢業(yè)設(shè)計(jì)說明書題目名稱: 化妝品噴頭塑料模具設(shè)計(jì) 院系名稱: 班 級(jí): 學(xué) 號(hào): 學(xué)生姓名: 指導(dǎo)教師: 2011年05月 論文編號(hào):化妝品噴頭塑料模具設(shè)計(jì)The design of cosmetics shower nozzle plastic mold院系名稱: 班 級(jí): 學(xué) 號(hào): 學(xué)生姓名: 指導(dǎo)教師: 2011年 05月摘要 本課題主要是針對(duì)噴頭的模具設(shè)計(jì),通過對(duì)所設(shè)計(jì)的塑件進(jìn)行工藝的分析和方案比較,最終設(shè)計(jì)出一副注塑模具。該課題從產(chǎn)品結(jié)構(gòu)工藝性,具體模具結(jié)構(gòu)出發(fā),對(duì)模具的型腔數(shù)、澆注系統(tǒng)、模具成型部分的結(jié)構(gòu)、頂出系統(tǒng)、冷卻系統(tǒng)、注塑機(jī)的選擇及有關(guān)參數(shù)的校核、都有詳細(xì)的設(shè)計(jì)。針對(duì)噴頭的具體結(jié)構(gòu)分析比較,該模具是點(diǎn)澆口的單分型面注射模具,由于噴頭體積較小,所以應(yīng)采取一模多腔結(jié)構(gòu),以實(shí)現(xiàn)高效率生產(chǎn),本注塑模對(duì)型腔采用雙排平衡式排列,以便采用平衡式澆注系統(tǒng),其優(yōu)點(diǎn)在于簡(jiǎn)化機(jī)構(gòu),使模具外形對(duì)稱,從而可以得到尺寸正確,外表美觀,物理性能良好的塑件制品。由于塑件具有側(cè)向噴嘴,所以必須設(shè)置斜導(dǎo)柱,采用側(cè)向抽芯的結(jié)構(gòu)形式。關(guān)鍵詞 塑料模具,化妝品噴頭,側(cè)向抽芯Abstract This topic mainly aimed at the mold design of shower nozzle. Through the analysis and comparison of the plastic product which comes from your design , the plastic mold was designed. This topic came from the technology capability of product, the structure of the mold embarks,the Type cavity number. the pours system, the injection molding system and the related parameter examination have detailed design . Concrete structure specifically for the shower nozzle, be a moulds turn to be that mark of type injects a mould face to face count the running gate Shan, since shower nozzle volume is less therefore should adopt one multiple-cavity model structure, to realize high efficiency giving birth to a child, produce plastic articles by injection moulding the model adopt pair of rows to balance style arranging to type cavity , that whose merit is lain in makes mould external form symmetrical to adopt balance style to pour system, can get correct, have a fine exterior, Physical fine dimension function .Since moulding have a spray nozzle , therefore must interpose tilted guide pin, strengthen the structure form adopt side direction to take a core out. Key words: Plastic mold,Cosmetics shower nozzle,Side direction to take a core out目 錄1 引言12 產(chǎn)品技術(shù)要求和工藝分析2 2.1 產(chǎn)品技術(shù)要求22.1.1 產(chǎn)品設(shè)計(jì)圖22.1.2 產(chǎn)品技術(shù)要求2 2.2 塑件的工藝分析3 2.2.1 塑件結(jié)構(gòu)工藝性32.2.2 塑件工藝性分析3 2.3 塑件材質(zhì)工藝性3 2.4 成型工藝性32.4.1 ABS塑料主要的性能指標(biāo)32.4.2 塑件的體積重量42.4.3 ABS的注射成型工藝參數(shù)53 擬定成型方案6 3.1 分型面位置的確定6 3.2 成型方案的列出73.2.1 分型面的選擇73.2.2 型腔數(shù)的確定83.2.3 確定型腔的排列93.2.4 澆注系統(tǒng)的設(shè)計(jì)9 3.2.4.1 主流道的設(shè)計(jì)93.2.4.2 冷料井的設(shè)計(jì)103.2.4.3 分流道的設(shè)計(jì)113.2.4.4 澆口的設(shè)計(jì)133.2.5 排氣、溫度調(diào)節(jié)系統(tǒng)的設(shè)計(jì)與計(jì)算14 3.2.5.1 排氣系統(tǒng)的設(shè)計(jì)與計(jì)算14 3.2.5.2 冷卻系統(tǒng)的設(shè)計(jì)與計(jì)算14 3.2.5.3 模具加熱系統(tǒng)的設(shè)計(jì)153.3 模架的選定154 模具工作零件的設(shè)計(jì)與計(jì)算174.1 凹模的結(jié)構(gòu)17 4.2 凹模厚度的計(jì)算185 脫模結(jié)構(gòu)的設(shè)計(jì)與計(jì)算19 5.1 脫模力的計(jì)算19 5.2 推桿直徑的計(jì)算19 5.3 側(cè)抽芯與側(cè)向分型機(jī)構(gòu)205.3.1 斜導(dǎo)柱直徑的確定215.3.2 斜導(dǎo)柱長(zhǎng)度計(jì)算和最小開模行程計(jì)算226 注射機(jī)與模具各參數(shù)的校核24 6.1 工藝參數(shù)的校核246.1.1 注射量的校核24 6.1.2 鎖模力的校核246.1.3 最大注射壓和的校核24 6.2 安裝參數(shù)校核257 模具的裝配26 7.1 模具裝配順序26 7.2 開模過程分析278 總結(jié)28致謝29參考文獻(xiàn)30中原工學(xué)院2011屆畢業(yè)設(shè)計(jì)說明書 1 引言 隨著中國(guó)當(dāng)前的經(jīng)濟(jì)形勢(shì)的日趨好轉(zhuǎn),在“實(shí)現(xiàn)中華民族的偉大復(fù)興”口號(hào)的倡引下,中國(guó)的制造業(yè)也日趨蓬勃發(fā)展;而模具技術(shù)已成為衡量一個(gè)國(guó)家制造業(yè)水平的重要標(biāo)志之一,模具工業(yè)能促進(jìn)工業(yè)產(chǎn)品生產(chǎn)的發(fā)展和質(zhì)量提高,并能獲得極大的經(jīng)濟(jì)效益,因而引起了各國(guó)的高度重視和贊賞。在日本,模具被譽(yù)為“進(jìn)入富裕的原動(dòng)力”,德國(guó)則冠之為“金屬加工業(yè)的帝王”,在羅馬尼亞則更為直接:“模具就是黃金”??梢娔>吖I(yè)在國(guó)民經(jīng)濟(jì)中重要地位。我國(guó)對(duì)模具工業(yè)的發(fā)展也十分重視,早在1989年3月頒布的關(guān)于當(dāng)前國(guó)家產(chǎn)業(yè)政策要點(diǎn)的決定中,就把模具技術(shù)的發(fā)展作為機(jī)械行業(yè)的首要任務(wù)。 模具是利用其特定形狀去成型具有一定的形狀和尺寸制品的工具。在各種材料加工工業(yè)中廣泛的使用著各種模具。例如金屬鑄造成型使用的砂型或壓鑄模具、金屬壓力加工使用的鍛壓模具、冷壓模具等各種模具。對(duì)模具的全面要求是:能生產(chǎn)出在尺寸精度、外觀、物理性能等各方面都滿足使用要求的公有制制品。以模具使用的角度,要求高效率、自動(dòng)化操作簡(jiǎn)便;從模具制造的角度,要求結(jié)構(gòu)合理、制造容易、成本低廉模具影響著制品的質(zhì)量。首先,模具型腔的形狀、尺寸、表面光潔度、分型面、進(jìn)澆口和排氣槽位置以及脫模方式等對(duì)制件的尺寸精度和形狀精度以及制件的物理性能、機(jī)械性能、電性能、內(nèi)應(yīng)力大小、各向同性性、外觀質(zhì)量、表面光潔度、氣泡、凹痕、燒焦、銀紋等都有十分重要的影響。其次,在加工過程中,模具結(jié)構(gòu)對(duì)操作難以程度影響很大。在大批量生產(chǎn)塑料制品時(shí),應(yīng)盡量減少開模,以實(shí)現(xiàn)高效率生產(chǎn)。近年來,塑料模具的產(chǎn)量和水平發(fā)展十分迅速,高效率、自動(dòng)化、大型、長(zhǎng)壽命、精密模具在模具產(chǎn)量中所戰(zhàn)比例越來越大。注塑成型模具就是將塑料先加在注塑機(jī)的加熱料筒內(nèi),塑料受熱熔化后,在注塑機(jī)的螺桿或活塞的推動(dòng)下,經(jīng)過噴嘴和模具的澆注系統(tǒng)進(jìn)入模具型腔內(nèi),塑料在其中固化成型。 本次畢業(yè)設(shè)計(jì)的主要任務(wù)是化妝品噴頭模具設(shè)計(jì)。也就是設(shè)計(jì)一副注塑模具來生產(chǎn)化噴頭塑件產(chǎn)品。針對(duì)化妝品的具體結(jié)構(gòu),通過此次設(shè)計(jì),使我對(duì)點(diǎn)澆口單分型面?zhèn)认虺樾灸>叩脑O(shè)計(jì)有了較深的認(rèn)識(shí)。同時(shí)在設(shè)計(jì)過程中,通過查閱大量資料、手冊(cè)、標(biāo)準(zhǔn)、期刊等,結(jié)合教材上的知識(shí)也對(duì)注塑模具的組成結(jié)構(gòu)(成型零部件、型腔布局,澆注系統(tǒng)、側(cè)向抽芯機(jī)構(gòu)、導(dǎo)向部分、推出機(jī)構(gòu)、排氣系統(tǒng)、模溫調(diào)節(jié)系統(tǒng))有了系統(tǒng)的認(rèn)識(shí),拓寬了視野,豐富了知識(shí)。通過畢業(yè)設(shè)計(jì)能夠?qū)σ陨细鞣矫娴囊箪`活運(yùn)用,為將來獨(dú)立完成模具設(shè)計(jì)積累了一定的經(jīng)驗(yàn)。2 產(chǎn)品技術(shù)要求和工藝分析2.1產(chǎn)品技術(shù)要求2.1.1產(chǎn)品設(shè)計(jì)圖 產(chǎn)品設(shè)計(jì)圖見圖2-1、圖2-2和圖2-3。 圖 2-1 產(chǎn)品3D圖俯視圖 圖 2-2 產(chǎn)品3D圖仰視圖 圖 2-3 產(chǎn)品2D圖2.1.2 產(chǎn)品技術(shù)要求 塑料零件的材料為丙烯腈-丁二烯-苯乙烯共聚物ABS,其表面要求無凹痕。 此塑件上有多個(gè)尺寸有精度要求:零件上有多個(gè)尺寸有精度要求,該零件的重要尺寸40.09mm的尺寸精度為3級(jí) ,次重要尺寸12 0.07mm,9.10.07mm的尺寸精度為4級(jí), 15 0.52mm為MT7級(jí)塑料精度,屬于中等精度等級(jí),在模具設(shè)計(jì)和制造過程中要嚴(yán)格保證這些尺寸的精度要求。 其余尺寸均無精度要求為自由尺寸,可按MT8級(jí)精度查取公差值。2.2 塑件的工藝分析2.2.1 塑件結(jié)構(gòu)工藝性 噴頭尺寸見圖三整體尺寸18mm15.3mm外部由圓柱形體并到角形成,內(nèi)部由一圓柱形腔但有三個(gè)寬度為1mm高5mm寬的長(zhǎng)方形加強(qiáng)筋,化妝品噴頭屬于內(nèi)部配件,表面精度要求較高,尺寸精度要求也較高。2.2.2 塑件工藝性分析 (1) 該塑件尺寸較小且要求塑件表面精度等級(jí)較高,無凹痕。采用點(diǎn)澆口流道的單分型面型腔注射??梢员WC其表面精度。 (2) 該塑件為中小批量生產(chǎn) ,且塑件的形狀較復(fù)雜。為了加工和熱處理,降低成本,該塑件采用一模多腔的結(jié)構(gòu),并且采用平衡式排列,以便于采用平衡式澆注系統(tǒng),從而得到尺寸正確,外表美觀,物理性能良好的塑件制品。從而也可以提高生產(chǎn)效率。2.3 塑件材質(zhì)工藝性 此化妝品噴頭是采用 ABS注塑成的。查相關(guān)手冊(cè)可知。 丙烯腈-丁二烯-苯乙烯共聚物ABS樹脂微黃色或白色不透明,是丙烯腈-丁二烯-苯乙烯共聚物。丙烯腈使聚合物耐油,耐熱,耐化學(xué)腐蝕,丁二烯使聚合物具有優(yōu)越的柔性,韌性;苯乙烯賦予聚合物良好的剛性和加工流動(dòng)性。因此ABS樹脂具有突出的力學(xué)性能、沖擊強(qiáng)度高、尺寸穩(wěn)定、易成型、耐腐蝕、耐熱、耐寒等良好的綜合性能。同時(shí)具有吸濕性強(qiáng),但原料要干燥,它的塑件尺寸穩(wěn)定性好。2.4成型工藝性2.4.1 ABS塑料主要的性能指標(biāo):密度 (Kg.dm-3) 1.131.14收縮率 % 0.30.8熔 點(diǎn) 130160熱變形溫度 45N/cm 6598彎曲強(qiáng)度 Mpa 80拉伸強(qiáng)度 MPa 3549拉伸彈性模量 GPa 1.8彎曲彈性模量 Gpa 1.4壓縮強(qiáng)度 Mpa 1839缺口沖擊強(qiáng)度 kJ/ 1120硬 度 HR R6286體積電阻系數(shù) cm 1013 擊穿電壓 Kv.mm-1 15介電常數(shù) 60Hz3.7比熱容 J/kg.k 1470摩擦系數(shù) 0.152.4.2 塑件的體積重量 計(jì)算塑件的重量是為了選用注射機(jī)及確定模具型腔數(shù)。 計(jì)算得塑件的體積:使用PRO/E軟件畫出三維實(shí)體圖,軟件能自動(dòng)計(jì)算出所畫圖形塑件的體積。V1460mm3計(jì)算塑件的質(zhì)量:公式為WV (2-1) 根據(jù)實(shí)用模具技術(shù)手冊(cè)P235表12-3查得丙烯腈-丁二烯-苯乙烯共聚物ABS的密度為1.13-1.14kg/dm3,此處取1.135 kg/dm3故塑件的重量為:WV14601.13510-31.657g根據(jù)注射所需的壓力和塑件的重量以及其它情況,可初步選用的注射機(jī)為SZ60/40型注塑成型機(jī),經(jīng)查實(shí)用注塑模設(shè)計(jì)手冊(cè)P7表2-1,該注塑機(jī)的各參數(shù)如表2-1所示: 表2-1 SZ60/40型注塑成型機(jī)個(gè)參數(shù)理論注射量/cm360移模行程/mm180螺桿直徑/mm30最大模具厚度/mm280注射壓力/Mp150最小模具厚度/mm160鎖模力/KN400噴嘴球半徑/mm15拉桿內(nèi)間距/mm295185噴嘴口孔徑/mm3.52.4.3 ABS的注射成型工藝參數(shù): 注塑機(jī)類型:螺桿式 噴嘴形式: 通用式 料筒一區(qū) 150170 料筒二區(qū) 180190 料筒三區(qū) 200210 噴嘴溫度 180190 模具溫度 5070 注塑壓 60100 Mpa保壓 4060 Mpa注塑時(shí)間 25 s保壓時(shí)間 510 s冷卻時(shí)間 515 s周期 1530 s后處理 紅外線烘箱 溫度(70) 時(shí)間(0.31)3 擬定成型方案3.1 分型面位置的確定 如何確定分型面,需要考慮的因素比較復(fù)雜。由于分型面受到塑件在模具中的成型位置、澆注系統(tǒng)設(shè)計(jì)、塑件的結(jié)構(gòu)工藝性及精度、嵌件位置形狀以及推出方法、模具的制造、排氣、操作工藝等多種因素的影響,因此在選擇分型面時(shí)應(yīng)綜合分析比較,從幾種方案中優(yōu)選出較為合理的方案。選擇分型面時(shí)一般應(yīng)遵循以下幾項(xiàng)原則:a)保證塑料制品能夠脫模 這是一個(gè)首要原則,因?yàn)槲覀冊(cè)O(shè)置分型面的目的,就是為了能夠順利從型腔中脫出制品。根據(jù)這個(gè)原則,分型面應(yīng)首選在塑料制品最大的輪廓線上,最好在一個(gè)平面上,而且此平面與開模方向垂直。分型的整個(gè)廓形應(yīng)呈縮小趨勢(shì),不應(yīng)有影響脫模的凹凸形狀,以免影響脫模。 b)使型腔深度最淺 模具型腔深度的大小對(duì)模具結(jié)構(gòu)與制造有如下三方面的影響: 1)目前模具型腔的加工多采用電火花成型加工,型腔越深加工時(shí)間越長(zhǎng),影響模具生產(chǎn)周期,同時(shí)增加生產(chǎn)成本。 2)模具型腔深度影響著模具的厚度。型腔越深,動(dòng)、定模越厚。一方面加工比較困難;另一方面各種注射機(jī)對(duì)模具的最大厚度都有一定的限制,故型腔深度不宜過大。 3)型腔深度越深,在相同起模斜度時(shí),同一尺寸上下兩端實(shí)際尺寸差值越大,如圖2。若要控制規(guī)定的尺寸公差,就要減小脫模斜度,而導(dǎo)致塑件脫模困難。因此在選擇分型面時(shí)應(yīng)盡可能使型腔深度最淺。c)使塑件外形美觀,容易清理 盡管塑料模具配合非常精密,但塑件脫模后,在分型面的位置都會(huì)留有一圈毛邊,我們稱之為飛邊。即使這些毛邊脫模后立即割除,但仍會(huì)在塑件上留下痕跡,影響塑件外觀,故分型面應(yīng)避免設(shè)在塑件光滑表面上,如圖3的分型面a位置,塑件割除毛邊后,在塑件光滑表面留下痕跡;圖3的分型面b處于截面變化的位置上,雖然割除毛邊后仍有痕跡,但看起來不明顯,故應(yīng)選擇后者.d)盡量避免側(cè)向抽芯 塑料注射模具,應(yīng)盡可能避免采用側(cè)向抽芯,因?yàn)閭?cè)向抽芯模具結(jié)構(gòu)復(fù)雜,并且直接影響塑件尺寸、配合的精度,且耗時(shí)耗財(cái),制造成本顯著增加,故在萬不得己的情況下才能使用.e)使分型面容易加工 分型面精度是整個(gè)模具精度的重要部分,力求平面度和動(dòng)、定模配合面的平行度在公差范圍內(nèi)。因此,分型面應(yīng)是平面且與脫模方向垂直,從而使加工精度得到保證。如選擇分型面是斜面或曲面,加工的難度增大,并且精度得不到保證,易造成溢料飛邊現(xiàn)象。g)使側(cè)向抽芯盡量短 抽芯越短,斜抽移動(dòng)的距離越短,一方面能減少動(dòng)、定模的厚度,減少塑件尺寸誤差;另一方面有利于脫模,保證塑件制品精度 。h)有利于排氣 對(duì)中、小型塑件因型腔較小,空氣量不多,可借助分型面的縫隙排氣。因此,選擇分型面時(shí)應(yīng)有利于排氣。按此原則,分型面應(yīng)設(shè)在注射時(shí)熔融塑料最后到達(dá)的位置,而且不把型腔封閉 綜上所述,選擇注射模分型面影響的因素很多,總的要求是順利脫模,保證塑件技術(shù)要求,模具結(jié)構(gòu)簡(jiǎn)單制造容易。當(dāng)選定一個(gè)分型面方案后,可能會(huì)存在某些缺點(diǎn),再針對(duì)存在的問題采取其它措施彌補(bǔ),以選擇接近理想的分型面。3.2 成型方案的列出3.2.1 分型面的選擇方案一(1)分 型 面:A-A為分型面;動(dòng)模型芯和側(cè)向型芯形成內(nèi)部形狀,定模型心和動(dòng)模型芯形成外部形狀;分型面位置見圖3-1;(2)澆注系統(tǒng):從側(cè)面進(jìn)澆;(3)排 氣:分型面排氣;(4)模溫調(diào)節(jié):冷卻管道;(5)抽芯機(jī)構(gòu):由動(dòng)模型芯和側(cè)向型芯組成型芯,型芯自動(dòng)脫出,活動(dòng)鑲件由人工取出方案二(1)分 型 面:如圖3-2,A-A為分型面;(2)澆注系統(tǒng):從中心澆注; (3)排 氣:分型面排氣;(4)模溫調(diào)節(jié):冷卻管道;(5)抽芯機(jī)構(gòu):側(cè)向抽芯機(jī)構(gòu)圖3-1 方案一 圖3-2 方案二對(duì)比兩個(gè)成型方案,最終選定方案一。這是因?yàn)椋簩?duì)于有同軸要求的塑件,選擇分型面時(shí),應(yīng)把有同軸度要求的部位放在模具同側(cè)。塑件有多組抽芯時(shí),應(yīng)把抽芯距較短的一端作為抽芯。因?yàn)閭?cè)向合模的鎖緊力較小,所以應(yīng)把投影面積較小的一邊作為側(cè)抽芯把投影面積較大的一邊方在動(dòng)、定模合模的主分型面上。而這些特點(diǎn)都是方案一能夠滿足,而方案二不能滿足的。方案二因?yàn)榛瘖y品噴頭屬于薄壁零件,從中心直接進(jìn)澆容易保證盒蓋表面光滑,但由于注射壓力直接作用在塑件上,容易在進(jìn)料處產(chǎn)生較大的殘余應(yīng)力而導(dǎo)致塑件翹起變形,且會(huì)在人手所按壓的部位留下熔解痕,在使用時(shí)會(huì)有一種不舒服的感覺。另外,因?yàn)閲婎^為圓柱薄壁形結(jié)構(gòu),從外側(cè)中心直接進(jìn)澆容易保證盒蓋表面光滑,但由于注射壓力直接作用在塑件上,容易在進(jìn)料處產(chǎn)生較大的殘余應(yīng)力而導(dǎo)致塑件翹起變形,而且方案二的定出機(jī)構(gòu)不好設(shè)置。方案一可以用圓柱形推桿自動(dòng)推出塑件,再由人工取出塑件和凝料,使塑件順利脫模。綜上所述,最終確定的成型方案為方案一。3.2.2 型腔數(shù)的確定型腔數(shù)的確定有多種方法,本題采用注射機(jī)的注射量來確定它的數(shù)目。其公式如下:n2=(G-C)/V (3-1)式中:G注射機(jī)的公稱注射量/cm3 V單個(gè)制品的體積/cm3C澆道和澆口的總體積/cm3生產(chǎn)中每次實(shí)際注射量應(yīng)不大于公稱注射量G的0.8倍,現(xiàn)取0.6G進(jìn)行計(jì)算。每件制品所需澆注系統(tǒng)的體積為制品體積的(0.21)倍,現(xiàn)取C0.6V進(jìn)行計(jì)算。n2=0.7G/1.7V=0.412G/V=(0.41260)/1460=16.92由以上的計(jì)算可知,可采用一模十六腔的模具結(jié)構(gòu)。3.2.3 確定型腔的排列 型腔的布置和澆口的開設(shè)部位應(yīng)力求對(duì)稱,以防模具承受片載而產(chǎn)生溢料現(xiàn)象;型腔排列宜緊湊,以節(jié)約材料,減輕模具的重量;圓形排列平衡好,加工困難,直線型排列加工容易,但平衡性差,H形排列平衡性好,而且加工性尚可,實(shí)用廣泛。本塑件在注射時(shí)采用一模十六件,即模具需要十六個(gè)型腔。綜合考慮澆注系統(tǒng)、模具結(jié)構(gòu)的復(fù)雜程度等因素,擬采用圖6所示的型腔排列方式。 圖3-3 型腔排列3.2.4 澆注系統(tǒng)的設(shè)計(jì)3.2.4.1主流道的設(shè)計(jì) 主流道是塑料熔體進(jìn)入模具型腔是最先經(jīng)過的部位,它將注塑機(jī)噴嘴注出的塑料熔體導(dǎo)入分流道或型腔,其形狀為圓錐形,便于熔體順利的向前流動(dòng),開模時(shí)主流道凝料又能順利拉出來,主流道的尺寸直接影響到塑料熔體的流動(dòng)速度和充模時(shí)間,由于主流道要與高溫塑料和注塑機(jī)噴嘴反復(fù)接觸和碰撞,通常不直接開在定模上,而是將它單獨(dú)設(shè)計(jì)成主流道套鑲?cè)攵0鍍?nèi)。主流道套通常又高碳工具鋼制造并熱處理淬硬。塑件外表面不許有澆口痕,又考慮取料順利,對(duì)塑件與澆注系統(tǒng)聯(lián)接處能自動(dòng)減斷。主流道的設(shè)計(jì)要點(diǎn)如下:(1)為便于從主流道中拉出澆注系統(tǒng)的凝料以及考慮塑料熔體的膨脹,主流道設(shè)計(jì)成圓錐形,因ABS的流動(dòng)性為中性,故其錐度取2度,過大會(huì)造成流速減慢,易成渦流,內(nèi)壁粗糙度為R0.8um。(2)主流道大端呈圓角,其半徑取r=13mm,以減少流速轉(zhuǎn)向過渡的阻力,r=1.5mm.(3)在保證塑件成形良好的情況下,主流道的長(zhǎng)度應(yīng)盡量短,否則會(huì)使主流道的凝料增多,且增加壓力損失,使塑料熔體降溫過多影響注射成形。(4)為使熔融塑料完全進(jìn)入主流道而不溢出,應(yīng)使主流道與注射機(jī)的噴嘴緊密對(duì)接,主流道對(duì)接處設(shè)計(jì)成半球形凹坑,其半徑為r2=r1+(12),其小端直徑D=d+(0.51),凹坑深度常取35mm。(5)由于主流道要與高溫高壓的塑料熔體和噴嘴反復(fù)接觸和碰撞,所以主流道部分常設(shè)計(jì)成可拆卸的主流道襯套,以便選用優(yōu)質(zhì)鋼材單獨(dú)加工和熱處理,大端兼作定位環(huán),圓盤凸出定模端面的長(zhǎng)度H=510mm。同時(shí)因該化妝品噴頭采用ABS,需加熱,所以在主流道處采用電加熱以提高料溫。根據(jù)以上設(shè)計(jì)要點(diǎn)經(jīng)查實(shí)用注塑模設(shè)計(jì)手冊(cè)P7表2-1得SZ60/40型注射機(jī)噴嘴有關(guān)尺寸如下:噴嘴前端孔徑:d0=3.5mm 噴嘴前端球面半徑:R015mm為了使凝料能順利拔出,主流道的小端直徑D1應(yīng)稍大于注射噴嘴直徑d。D1d+(0.51)mm=3.5+14.5mm經(jīng)查實(shí)用模具技術(shù)手冊(cè)P303表15-9主流道部分尺寸,可得主流道大端直徑: D2=d+2Ltg/2 (3-2) 主流道的半錐角通常為12過大的錐角會(huì)產(chǎn)生湍流或渦流,卷入氣,過小的錐角使凝料脫模困難,還會(huì)使充模時(shí)熔體的流動(dòng)阻力過大,此處的角選用2,為使熔料順利進(jìn)入分流道,可在主流道出料端設(shè)計(jì)半徑1.5m圓弧過渡。主流道的長(zhǎng)度L一般控60mm之內(nèi),可取L55mm。經(jīng)換算得主道大端直徑D28.5mm。所設(shè)計(jì)尺寸如圖7所示:圖3-4 澆口套3.2.4.2 冷料井的設(shè)計(jì)冷料井位于主流道正對(duì)面的動(dòng)模板上,或處于分流道末端,其作用是接受料流前鋒的“冷料”,防止“冷料”進(jìn)入型腔而影響塑件質(zhì)量,開模時(shí)又能將主流道的凝料拉出。冷料井的直徑宜大于大端直徑,長(zhǎng)度約為主流道大端直徑。基于本次設(shè)計(jì)的模具,可采用底部帶有拉料桿的冷料井,這類冷料井的底部由一個(gè)拉料桿構(gòu)成。拉料桿裝于型芯固定板上,因此它不能隨脫模機(jī)構(gòu)運(yùn)動(dòng)。利用Z形的拉料桿配合冷料井。其結(jié)構(gòu)如下圖8所示 圖3-5 冷料井與Z形拉料桿的配合3.2.4.3 分流道的設(shè)計(jì)分流道是主流道與澆口之間的通道,一般開在分型面上,起分流和轉(zhuǎn)向的作用。分流道截面的形狀可以是圓形、半圓形、矩形、梯形和U形等,圓形和正方形截面流道的比面積最?。鞯辣砻娣e于體積之比值稱為比表面積),塑料熔體的溫度下降小,阻力小,流道的效率最高。但加工困難,而且正方形截面不易脫模,所以在實(shí)際生產(chǎn)中較常用的截面形狀為梯形、半圓形及U形。分流道設(shè)計(jì)要點(diǎn):(1)在保證足夠的注塑壓力使塑料熔體能順利的充滿型腔的前提下,分流道截面積與長(zhǎng)度盡量取小值,分流道轉(zhuǎn)折處應(yīng)以圓弧過度。(2)分流道較長(zhǎng)時(shí),在分流道的末端應(yīng)開設(shè)冷料井。對(duì)于此模來說在分流道上不須開設(shè)冷料井。(3)分流道的位置可單獨(dú)開設(shè)在定模板上或動(dòng)模板上,也可以同時(shí)開設(shè)在動(dòng),定模板上,合模后形成分流道截面形狀。(4)分流道與澆口連接處應(yīng)加工成斜面,并用圓弧過度。1)分流道的長(zhǎng)度分流道的長(zhǎng)度取決于模具型腔的總體布置方案和澆口位置,從在輸送熔料時(shí)減少壓力損失,熱量損失和減少澆道凝料的要求出發(fā),應(yīng)力求縮短。2)分流道的斷面:經(jīng)查實(shí)用注塑模設(shè)計(jì)手冊(cè)P98,分流道的斷面尺寸應(yīng)根據(jù)塑件的成形的體積,塑件的壁厚,塑件的形狀和所用塑料的工藝性能,注射速率和分流道長(zhǎng)度等因素來確定。對(duì)于壁厚小于3mm,質(zhì)量200g以下的制品,可用以下經(jīng)驗(yàn)公式確定分流道的直徑: (3-3)式中 W 制品質(zhì)量 (g) L 分流道的長(zhǎng)度 (mm) D 分流道的直徑 (mm) 根據(jù)圖6所示型腔的布局分流道的長(zhǎng)度L = 128mm,根據(jù)以上所計(jì)算得到的塑件質(zhì)量W = 1.657g*16 = 26.512g。帶入上公式得制品質(zhì)量W = 4.6mm。經(jīng)查實(shí)用注塑模設(shè)計(jì)手冊(cè)P98表4-2部分塑料常用分流道斷面尺寸推薦范圍,ABS的推薦斷面直徑為4.59.5mm。分流道要減小壓力損失,希望流道的截面積大,表面積小,以減小傳熱損失,同時(shí)因考慮加工的方便性。分流道應(yīng)考慮出料的流暢性和制造方便,熔融料的熱量損失小,流動(dòng)阻力小,比表面和小等問題,但同時(shí)考慮到加工的方便性,可采用半圓形的流道。綜上所述分流道的直徑經(jīng)修正后可采用5mm。3)分流道的布局在多型腔模具中分流道的布置中有平衡和非平衡兩種,根據(jù)本模具的要求我們選取平衡式,也就是指分流道到各型腔澆口的長(zhǎng)度,斷面形狀,尺寸都相同的布置形式。它要求各對(duì)應(yīng)部位的尺寸相等。這種布置可實(shí)現(xiàn)均衡送料和同時(shí)充滿型腔的目的,是成型的塑件力學(xué)性能基本一致。而且在此模具中不會(huì)造成份流道過長(zhǎng)。分流道的布局如下圖9所示。圖3-6 分流道的布局3.2.4.4 澆口的設(shè)計(jì)澆口又稱進(jìn)料口,是連接分流道與型腔之間的一段細(xì)短流道(除直接澆口外),它是澆注系統(tǒng)的關(guān)鍵部分。其主要作用是:(1)型腔充滿后,熔體在澆口處首先凝結(jié),防止其倒流。(2)易于在澆口切除澆注系統(tǒng)的凝料。澆口截面積約為分流道截面積的0.030.09,澆口的長(zhǎng)度約為0.5mm2mm,澆口具體尺寸一般根據(jù)經(jīng)驗(yàn)確定,取其下限值,然后在試模是逐步糾正。當(dāng)塑料熔體通過澆口時(shí),剪切速率增高,同時(shí)熔體的內(nèi)磨檫加劇,使料流的溫度升高,粘度降低,提高了流動(dòng)性能,有利于充型。但澆口尺寸過小會(huì)使壓力損失增大,凝料加快,補(bǔ)縮困難,甚至形成噴射現(xiàn)象,影響塑件質(zhì)量。澆口位置的選擇:(1)澆口位置應(yīng)使填充型腔的流程最短。這樣的結(jié)構(gòu)使壓力損失最小,易保證料流充滿整個(gè)型腔,同時(shí)流動(dòng)比的允許值隨塑料熔體的性質(zhì),溫度,注塑壓力等的不同而變化,所以我們?cè)诳紤]塑件的質(zhì)量都要注意到這些適當(dāng)值。(2澆口設(shè)置應(yīng)有利于排氣和補(bǔ)塑。(3澆口位置的選擇要避免塑件變形。采側(cè)澆口在進(jìn)料時(shí)頂部形成閉氣腔,在塑件頂部常留下明顯的熔接痕,而采用點(diǎn)澆口,有利于排氣,整件質(zhì)量較好,但是塑件壁厚相差較大,澆口開在薄壁處不合理;而設(shè)在厚壁處,有利于補(bǔ)縮,可避免縮孔、凹痕產(chǎn)生。(4)澆口位置的設(shè)置應(yīng)減少或避免生成熔接痕。熔接痕是充型時(shí)前端較冷的料流在型腔中的對(duì)接部位,它的存在會(huì)降低塑件的強(qiáng)度,所以設(shè)置澆口時(shí)應(yīng)考慮料流的方向,澆口數(shù)量多,產(chǎn)生熔接痕的機(jī)會(huì)很多。流程不長(zhǎng)時(shí)應(yīng)盡量采用一個(gè)澆口,以減少熔接痕的數(shù)量。對(duì)于大多數(shù)框形塑件,澆口位置使料流的流程過長(zhǎng),熔接處料溫過低,熔接痕處強(qiáng)度低,會(huì)形成明顯的接縫,如果澆口位置使料流的流程短,熔接處強(qiáng)度高。為了提高熔接痕處強(qiáng)度,可在熔接處增設(shè)溢溜槽,是冷料進(jìn)入溢溜槽。筒形塑件采用環(huán)行澆口無熔接痕,而輪輻式澆口會(huì)使熔接痕產(chǎn)生。(5)澆口位置應(yīng)避免側(cè)面沖擊細(xì)長(zhǎng)型心或鑲件。 根據(jù)上述原則結(jié)合本模具的特點(diǎn)選擇點(diǎn)澆口,其優(yōu)點(diǎn)為: 點(diǎn)澆口尺寸澆口 ,熔體通過點(diǎn)澆口時(shí)的流速增大,提高了沖模速度,因而可獲得外表清晰、有光澤的制品。 熔體流過點(diǎn)澆口時(shí),摩擦阻力使熔體溫度略有升高,黏度下降,改善了流動(dòng)性,對(duì)薄壁或帶有精密花紋的制品成型有利。三冷凝快,縮短了成型周期。 可自動(dòng)拉斷凝料,殘留痕跡小,減少了休整工序,提高了上產(chǎn)率。3.2.5 排氣、溫度調(diào)節(jié)系統(tǒng)的設(shè)計(jì)與計(jì)算3.2.5.1 排氣系統(tǒng)的設(shè)計(jì)與計(jì)算 塑料熔體在填充模具的型腔過程中同時(shí)要排出型強(qiáng)及流道原有的空氣,除此以外,塑料熔體會(huì)產(chǎn)生微量的分解氣體。這些氣體必須及時(shí)排出。否則,被壓縮的空氣產(chǎn)生高溫,會(huì)引起塑件局部碳化燒焦,或塑件產(chǎn)生氣泡,或使塑件熔接不良引起強(qiáng)度下降,甚至充模不滿。因該模具為小型模具,且分型面適宜,可利用分型面排氣,所以無需設(shè)計(jì)排氣槽。3.2.5.2 冷卻系統(tǒng)的設(shè)計(jì)與計(jì)算 冷卻系統(tǒng)設(shè)計(jì)的有關(guān)公式:qV=WQ1/c1(1-2) (3-4) 式中:qV冷卻水的體積流量(m3/min)W單位時(shí)間內(nèi)注入模具中的塑料重量(kg/min)Q1單位重量的塑料制品在凝固時(shí)所放出的熱量(kJ/kg)冷卻水的密度(kg/m3) c1冷卻水的比熱容kJ/(kg.)1冷卻水的出口溫度() 2冷卻水的入口溫度() Q1可表示為:Q1=c2(3-4) 式中:c2塑料的比熱容kJ/(kg.) Q3塑料熔體的初始溫度() 4塑料制品在推出時(shí)的溫度() Q1= c2(3-4) = 1.470(200-60)=205.8kJ/kg 將以上各數(shù)代入公式(3-4)得: qV=(0.013205.8)/0.981034.187(25-20)m3/min =0.1310-3m3/min上述計(jì)算的設(shè)定條件是:模具的平均工作溫度為40,用常溫20的水作為模具的冷卻介質(zhì),其出口溫度為25,產(chǎn)量為0.013kg/min。 由體積流量查塑料成型模具設(shè)計(jì)與制造P103表8-3可知所需的冷卻水管的直徑非常小,體積流量也很小,故可不設(shè)冷卻系統(tǒng),依靠空冷的方式即可。但為滿足模具在不同溫度條件下的使用,可在適當(dāng)?shù)奈恢貌贾弥睆絛為6mm的管道 圖3-7 直流式冷卻回路來調(diào)節(jié)溫度,如圖10所示冷卻回路。另外,具冷卻系統(tǒng)的過程中,還應(yīng)同時(shí)遵循:澆口處加強(qiáng)冷卻;冷卻水孔到型腔表面的距離相等;冷卻水孔數(shù)量應(yīng)盡可能的多,孔徑應(yīng)盡可能的大;冷卻水孔道不應(yīng)穿過鑲快或其接縫部位,以防漏水。進(jìn)水口水管接頭的位置應(yīng)盡可能設(shè)在模具的同一側(cè),通常應(yīng)設(shè)在塑機(jī)的背面。 冷卻水孔應(yīng)避免設(shè)在塑件的熔接痕處。而且在冷卻系統(tǒng)內(nèi),各相接處應(yīng)保持密封,防止冷卻水外3.2.5.3 模具加熱系統(tǒng)的設(shè)計(jì) 因在ABS要求的熔融溫度為200。而且流動(dòng)性能為中性,同時(shí)在注射時(shí)模具溫度要求為5070,所以該模具必須加熱。模具加熱方法包括:熱水,熱空氣,熱油及電加熱等。由于電加熱清潔、結(jié)構(gòu)簡(jiǎn)單、可調(diào)節(jié)范圍大,所以在該模具應(yīng)用電加熱。3.3 模架的選定根據(jù)以上分析,計(jì)算以及型腔尺寸及位置尺寸可確定模架的結(jié)構(gòu)形式和規(guī)格。經(jīng)查實(shí)用模具技術(shù)手冊(cè)P434表20-2注射模中小型模架標(biāo)準(zhǔn)的尺寸組合選用:A2-250355-64-Z1如圖11所示 圖3-8 A2型模架定模板厚度: A=25mm 動(dòng)模板厚度: B=40mm墊快厚度: C=80mm 定模板座厚度: D=25mm動(dòng)模板座厚度:E=25mm根據(jù)自己所設(shè)計(jì)的塑件及澆注系統(tǒng),計(jì)算得其投影面積約為75mm,經(jīng)查塑料模設(shè)計(jì)手冊(cè)P214表5-50,支撐板的厚度: F=25mm模具厚度 H=A+B+C+D+E+F=(25+25+25+25+40+80)mm=220mm模具外形尺寸 250mm355mm220mm4 模具工作零件的設(shè)計(jì)與計(jì)算 型腔是模具上直接成型塑料制件的部位。直接構(gòu)成模具型腔的所有零件的所有零件都稱為成型零件,通常包括:凹模、凸模、成型桿、成型環(huán)、各種型腔鑲件等。所謂工作尺寸是指成型零件上直接用以成型塑件部位的尺寸。工作尺寸的計(jì)算受塑件尺寸精度的制約,影響塑件尺寸精度的因素甚多,且十分復(fù)雜,一次塑件尺寸難以達(dá)到高精度。4.1 凹模的結(jié)構(gòu) 對(duì)塑料制品成型時(shí),凹模的作用是形成制品的外表面。根據(jù)不同的結(jié)構(gòu)形式,凹模大體上可分為整體式結(jié)構(gòu)、整體嵌入式結(jié)構(gòu)、局部鑲嵌式結(jié)構(gòu)、底面鑲嵌式結(jié)構(gòu)和側(cè)壁拼合式結(jié)構(gòu)五種類型。根據(jù)自己所設(shè)計(jì)的塑件以及分型面的選擇,采用整體式凹模比較合理。定模采用整體式凹模是由整塊材料制成,這類模具的優(yōu)點(diǎn)是結(jié)構(gòu)牢固,成型的制品表面無接縫痕跡,對(duì)于中小型模具比較適用。動(dòng)模采用整體嵌入式凹模,在整體嵌入式模具中,把凹模單獨(dú)加工成鑲快,外形采用矩形,從鑲塊下部嵌入動(dòng)模板中,再加以用螺釘定位。鑲塊如圖4-1所示。圖4-1 鑲塊剖面圖 本設(shè)計(jì)中零件工作尺寸的計(jì)算均采用平均尺寸、平均收縮率、平均制造公差和平均磨損量來進(jìn)行計(jì)算,已給出這ABS的成型收縮率為0.005,模具的制造公差取z=/3。經(jīng)查實(shí)用模具技術(shù)手冊(cè)P320表15-25如下表所示:表4-1 型腔型芯工作尺寸的計(jì)算類別塑件尺寸計(jì)算公式模具尺寸型腔計(jì)算型腔板15.100-0.016Lm=(Ls+Ls.Scp%-3/4)0+z15.062500.00615.00-0.018Hm=(Hs+Hs.Scp%-1/2)0+z15.06600.006型芯計(jì)算主型芯12.000.018Lm=(Ls+Ls.Scp%+3/4)0-z12.07350-0.00613.500-0.018Hm=(Hs+Hs.Scp%+1/2)0-z13.6580-0.0064.2 凹模壁厚的計(jì)算在注射成型過程中,模具的型腔將受道高壓的作用,應(yīng)此模具應(yīng)該具有足夠的強(qiáng)度和剛度。強(qiáng)度不足將導(dǎo)致塑性變形,甚至開裂。剛度不足導(dǎo)致彈性變形,導(dǎo)致型腔向外膨脹,產(chǎn)生溢料間隙。經(jīng)查塑料模設(shè)計(jì)手冊(cè)P212式5-20。 長(zhǎng)方形整體式型腔的側(cè)壁厚度計(jì)算公式:SPaL4/32Eb()1/3 (4-1) 式中:S側(cè)壁厚度(mm)P型腔壓力(Mpa) L型腔長(zhǎng)邊的邊長(zhǎng)(mm) a型腔壓力部分的高度(mm) E模具材料的彈性模量(MPa) 剛度條件,即允許變形量(mm) b型腔高度(mm) 將以上各數(shù)代入公式(4-1)得: S(401.82004)/(3215.32.11050.05)1/3 =28.19mm5 脫模機(jī)構(gòu)的設(shè)計(jì)與計(jì)算5.1 脫模力的計(jì)算 此模具采用推桿脫模,因該制件的,屬厚壁制品,所謂壁厚制品就是指塑件壁厚與其內(nèi)孔直徑之比大于0.05.厚壁制品脫模力受到材料向壁厚中性層冷卻收縮的影響,可用彈性力學(xué)的有關(guān)厚壁圓筒的理論進(jìn)行分析計(jì)算,經(jīng)查實(shí)用注塑模設(shè)計(jì)手冊(cè)P124式4-15如下: (5-1)式中,對(duì)于圓筒制品中: 塑料成型平均收縮率() L 塑件包容型芯的長(zhǎng)度(mm) 脫模斜度( ) 塑料與鋼材之間的摩擦因數(shù) r 型芯大小端的平均直徑(mm) 塑料的泊松比 E在脫模溫度下塑料的抗拉彈性模量(MPa) B 塑件再與開模方向垂直的平面上的投影面積(cm) t制品的平均厚度(mm) K1由f和決定的無因次數(shù),可由下式計(jì)算 K1=1+sincos (5-2) K2由(=r/t)和決定的無因次數(shù),可由下式計(jì)算 K2=2/(cos+2cos) (5-3)將以上各數(shù)據(jù)代入公式(5-1)得: Qc=145N 因本模具設(shè)計(jì)的是一模十六腔結(jié)構(gòu),所以每一個(gè)型腔所需脫模力為145N。5.2 頂桿直徑的計(jì)算推桿推頂推件板時(shí)應(yīng)有足夠的穩(wěn)定性,其受力狀態(tài)可簡(jiǎn)化為一端固定、一端鉸支的壓桿穩(wěn)定性模型,根據(jù)實(shí)用模具技術(shù)手冊(cè)P335表15-39,壓桿穩(wěn)定公式推導(dǎo)推桿直徑計(jì)算式為: d=K(l2Qe/nE)1/4 (5-4)推桿直徑確定后,還應(yīng)用下式進(jìn)行強(qiáng)度校核:c=4Qe/nd2s (5-5)式中:d推桿直徑(mm)K安全系數(shù),通常取K=1.32l推桿的長(zhǎng)度(mm) Qe脫模力(N) E推桿材料的彈性模量(MPa) n推桿根數(shù) c推桿所受的壓應(yīng)力(MPa)s推桿材料的屈服點(diǎn)(MPa) 將以上各數(shù)據(jù)代入公式(5-4)得: d=2.3mm 圓整取2.5mm將以上各數(shù)據(jù)代入公式(5-5)進(jìn)行校核: c=4Qe/nd2=29.55 MPas=360 MPa所以此推桿符合要求。5.3 側(cè)抽芯與側(cè)向分型機(jī)構(gòu) 當(dāng)塑件上具有與開模方向非一致的孔或側(cè)壁有凹凸形狀時(shí),必須首先將成型這部分的型芯或型腔脫離塑件,才能將整個(gè)塑件從模具中脫出。通常將這種型芯或型腔稱為側(cè)型芯或側(cè)型腔,并加工成可動(dòng)形式。開模時(shí)推動(dòng)側(cè)型芯或側(cè)型腔外移脫離塑件,合模時(shí)推動(dòng)側(cè)型芯或側(cè)型腔復(fù)位的機(jī)構(gòu)稱為側(cè)向分型與抽芯機(jī)構(gòu)。這類模具脫出塑件的運(yùn)動(dòng)有兩種情況:第一種是開模時(shí)首先完成側(cè)向分型與抽芯,然后推出塑件;第畢業(yè)設(shè)計(jì)開題報(bào)告題目名稱: 化妝品噴頭塑料模具設(shè)計(jì) 院系名稱: 班 級(jí): 學(xué) 號(hào): 學(xué)生姓名: 指導(dǎo)教師: 2011 年 03月畢業(yè)設(shè)計(jì)說明書題目名稱: 化妝品噴頭塑料模具設(shè)計(jì) 院系名稱: 班 級(jí): 學(xué) 號(hào): 學(xué)生姓名: 指導(dǎo)教師: 2011年 05月畢業(yè)實(shí)習(xí)報(bào)告題目名稱: 化妝品噴頭塑料模具設(shè)計(jì) 院系名稱: 班 級(jí): 學(xué) 號(hào): 學(xué)生姓名: 指導(dǎo)教師: 2011年 03月畢業(yè)設(shè)計(jì)(論文)譯文題目名稱: Metal_Machining(金屬加工) 院系名稱: 班 級(jí): 學(xué) 號(hào): 學(xué)生姓名: 指導(dǎo)教師: 2011年 03 月 論文編號(hào):200700314411化妝品噴頭塑料模具設(shè)計(jì)The design of cosmetics shower nozzle plastic mold院系名稱: 班 級(jí): 學(xué) 號(hào): 學(xué)生姓名: 指導(dǎo)教師: 2011年 05月桂林電子科技大學(xué)畢業(yè)設(shè)計(jì)(論文)外文翻譯譯文 第10頁 共22頁編號(hào): 畢業(yè)設(shè)計(jì)(論文)外文翻譯(原文)學(xué) 院: 國(guó)防生學(xué)院 專 業(yè): 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 學(xué)生姓名: 匡鵬來 學(xué) 號(hào): 1000110105 指導(dǎo)教師單位: 機(jī)電工程學(xué)院 姓 名: 曹泰山 職 稱: 講 師 2014年 3 月 9 日桂林電子科技大學(xué)畢業(yè)設(shè)計(jì)(論文)外文翻譯譯文 第27頁 共28頁 technical note on the characterization of electroformed nickel shells for their application to injection molds aUniversidad de Las Palmas de Gran Canaria, Departamento de Ingenieria Mecanica, Spain AbstractThe techniques of rapid prototyping and rapid tooling have been widely developed during the last years. In this article, electroforming as a procedure to make cores for plastics injection molds is analysed. Shells are obtained from models manufactured through rapid prototyping using the FDM system. The main objective is to analyze the mechanical features of electroformed nickel shells, studying different aspects related to their metallographic structure, hardness, internal stresses and possible failures, by relating these features to the parameters of production of the shells with an electroforming equipment. Finally a core was tested in an injection mold. Keywords: Electroplating; Electroforming; Microstructure; Nickel 1. IntroductionOne of the most important challenges with which modern industry comes across is to offer the consumer better products with outstanding variety and time variability (new designs). For this reason, modern industry must be more and more competitive and it has to produce with acceptable costs. There is no doubt that combining the time variable and the quality variable is not easy because they frequently condition one another; the technological advances in the productive systems are going to permit that combination to be more efficient and feasible in a way that, for example, if it is observed the evolution of the systems and techniques of plastics injection, we arrive at the conclusion that, in fact, it takes less and less time to put a new product on the market and with higher levels of quality. The manufacturing technology of rapid tooling is, in this field, one of those technological advances that makes possible the improvements in the processes of designing and manufacturing injected parts. Rapid tooling techniques are basically composed of a collection of procedures that are going to allow us to obtain a mold of plastic parts, in small or medium series, in a short period of time and with acceptable accuracy levels. Their application is not only included in the field of making plastic injected pieces 1, 2 and 3, however, it is true that it is where they have developed more and where they find the highest output. This paper is included within a wider research line where it attempts to study, define, analyze, test and propose, at an industrial level, the possibility of creating cores for injection molds starting from obtaining electroformed nickel shells, taking as an initial model a prototype made in a FDM rapid prototyping equipment. It also would have to say beforehand that the electroforming technique is not something new because its applications in the industry are countless 3, but this research work has tried to investigate to what extent and under which parameters the use of this technique in the production of rapid molds is technically feasible. All made in an accurate and systematized way of use and proposing a working method. 2. Manufacturing process of an injection moldThe core is formed by a thin nickel shell that is obtained through the electroforming process, and that is filled with an epoxic resin with metallic charge during the integration in the core plate 4 This mold (Fig. 1) permits the direct manufacturing by injection of a type a multiple use specimen, as they are defined by the UNE-EN ISO 3167 standard. The purpose of this specimen is to determine the mechanical properties of a collection of materials representative industry, injected in these tools and its coMParison with the properties obtained by conventional tools. Fig. 1.Manufactured injection mold with electroformed core.The stages to obtain a core 4, according to the methodology researched in this work, are the following: (a) Design in CAD system of the desired object.(b) Model manufacturing in a rapid prototyping equipment (FDM system). The material used will be an ABS plastic.(c) Manufacturing of a nickel electroformed shell starting from the previous model that has been coated with a conductive paint beforehand (it must have electrical conductivity).(d) Removal of the shell from the model.(e) Production of the core by filling the back of the shell with epoxy resin resistant to high temperatures and with the refrigerating ducts made with copper tubes.The injection mold had two cavities, one of them was the electroformed core and the other was directly machined in the moving platen. Thus, it was obtained, with the same tool and in the same process conditions, to inject simultaneously two specimens in cavities manufactured with different technologies. 3. Obtaining an electroformed shell: the equipmentElectrodeposition 5 and 6 is an electrochemical process in which a chemical change has its origin within an electrolyte when passing an electric current through it. The electrolytic bath is formed by metal salts with two submerged electrodes, an anode (nickel) and a cathode (model), through which it is made to pass an intensity coming from a DC current. When the current flows through the circuit, the metal ions present in the solution are transformed into atoms that are settled on the cathode creating a more or less uniform deposit layer. The plating bath used in this work is formed by nickel sulfamate 7 and 8 at a concentration of 400ml/l, nickel chloride (10g/l), boric acid (50g/l), Allbrite SLA (30cc/l) and Allbrite 703 (2cc/l). The selection of this composition is mainly due to the type of application we intend, that is to say, injection molds, even when the injection is made with fibreglass. Nickel sulfamate allows us to obtain an acceptable level of internal stresses in the shell (the tests gave results, for different process conditions, not superior to 50MPa and for optimum conditions around 2MPa). Nevertheless, such level of internal pressure is also a consequence of using as an additive Allbrite SLA, which is a stress reducer constituted by derivatives of toluenesulfonamide and by formaldehyde in aqueous solution. Such additive also favours the increase of the resistance of the shell when permitting a smaller grain. Allbrite 703 is an aqueous solution of biodegradable surface-acting agents that has been utilized to reduce the risk of pitting. Nickel chloride, in spite of being harmful for the internal stresses, is added to enhance the conductivity of the solution and to favour the uniformity in the metallic distribution in the cathode. The boric acid acts as a pH buffer. The equipment used to manufacture the nickel shells tested has been as follows: Polypropylene tank: 600mm400mm500mm in size. Three teflon resistors, each one with 800W. Mechanical stirring system of the cathode. System for recirculation and filtration of the bath formed by a pump and a polypropylene filter. Charging rectifier. Maximum intensity in continuous 50A and continuous current voltage between 0 and 16V. Titanium basket with nickel anodes (Inco S-Rounds Electrolytic Nickel) with a purity of 99%. Gases aspiration system.Once the bath has been defined, the operative parameters that have been altered for testing different conditions of the process have been the current density (between 1 and 22A/dm2), the temperature (between 35 and 55C) and the pH, partially modifying the bath composition. 4. Obtained hardnessOne of the most interesting conclusions obtained during the tests has been that the level of hardness of the different electroformed shells has remained at rather high and stable values. In Fig. 2, it can be observed the way in which for current density values between 2.5 and 22A/dm2, the hardness values range from 540 and 580HV, at pH 40.2 and with a temperature of 45C. If the pH of the bath is reduced at 3.5 and the temperature is 55C those values are above 520HV and below 560HV. This feature makes the tested bath different from other conventional ones composed by nickel sulfamate, allowing to operate with a wider range of values; nevertheless, such operativity will be limited depending on other factors, such as internal stress because its variability may condition the work at certain values of pH, current density or temperature. On the other hand, the hardness of a conventional sulfamate bath is between 200250HV, much lower than the one obtained in the tests. It is necessary to take into account that, for an injection mold, the hardness is acceptable starting from 300HV. Among the most usual materials for injection molds it is possible to find steel for improvement (290HV), steel for integral hardening (520595HV), casehardened steel (760800HV), etc., in such a way that it can be observed that the hardness levels of the nickel shells would be within the mediumhigh range of the materials for injection molds. The objection to the low ductility of the shell is compensated in such a way with the epoxy resin filling that would follow it because this is the one responsible for holding inwardly the pressure charges of the processes of plastics injection; this is the reason why it is necessary for the shell to have a thickness as homogeneous as possible (above a minimum value) and with absence of important failures such as pitting. Fig. 2.Hardness variation with current density. pH 40.2, T=45C.5. Metallographic structureIn order to analyze the metallographic structure, the values of current density and temperature were mainly modified. The samples were analyzed in frontal section and in transversal section (perpendicular to the deposition). For achieving a convenient preparation, they were conveniently encapsulated in resin, polished and etched in different stages with a mixture of acetic acid and nitric acid. The etches are carried out at intervals of 15, 25, 40 and 50s, after being polished again, in order to be observed afterwards in a metallographic microscope Olympus PME3-ADL 3.3/10. Before going on to comment the photographs shown in this article, it is necessary to say that the models used to manufacture the shells were made in a FDM rapid prototyping machine where the molten plastic material (ABS), that later solidifies, is settled layer by layer. In each layer, the extruder die leaves a thread approximately 0.15mm in diameter which is compacted horizontal and vertically with the thread settled inmediately after. Thus, in the surface it can be observed thin lines that indicate the roads followed by the head of the machine. These lines are going to act as a reference to indicate the reproducibility level of the nickel settled. The reproducibility of the model is going to be a fundamental element to evaluate a basic aspect of injection molds: the surface texture. The tested series are indicated in Table 1. Table 1. Tested series Series pH Temperature (C) Current density (A/dm2) 14.20.2552.2223.90.2455.5634.00.24510.0044.00.24522.22Fig. 3 illustrates the surface of a sample of the series after the first etch. It shows the roads originated by the FDM machine, that is to say that there is a good reproducibility. It cannot be still noticed the rounded grain structure. In Fig. 4, series 2, after a second etch, it can be observed a line of the road in a way less clear than in the previous case. In Fig. 5, series 3 and 2 etch it begins to appear the rounded grain structure although it is very difficult to check the roads at this time. Besides, the most darkened areas indicate the presence of pitting by inadequate conditions of process and bath composition. Fig. 3.Series 1 (150), etch 1.Fig. 4.Series 2 (300), etch 2.Fig. 5.Series 3 (300), etch 2.This behavior indicates that, working at a low current density and a high temperature, shells with a good reproducibility of the model and with a small grain size are obtained, that is, adequate for the required application. If the analysis is carried out in a plane transversal to the deposition, it can be tested in all the samples and for all the conditions that the growth structure of the deposit is laminar (Fig. 6), what is very satisfactory to obtain a high mechanical resistance although at the expense of a low ductibility. This quality is due, above all, to the presence of the additives used because a nickel sulfamate bath without additives normally creates a fibrous and non-laminar structure 9. The modification until a nearly null value of the wetting agent gave as a result that the laminar structure was maintained in any case, that matter demonstrated that the determinant for such structure was the stress reducer (Allbrite SLA). On the other hand, it was also tested that the laminar structure varies according to the thickness of the layer in terms of the current density. Fig. 6.Plane transversal of series 2 (600), etch 2.6. Internal stressesOne of the main characteristic that a shell should have for its application like an insert is to have a low level of internal stresses. Different tests at different bath temperatures and current densities were done and a measure system rested on cathode flexural tensiometer method was used. A steel testing control was used with a side fixed and the other free (160mm length, 12.7mm width and thickness 0.3mm). Because the metallic deposition is only in one side the testing control has a mechanical strain (tensile or compressive stress) that allows to calculate the internal stresses. Stoney model 10 was applied and was supposed that nickel substratum thickness is enough small (3m) to influence, in an elastic point of view, to the strained steel part. In all the tested cases the most value of internal stress was under 50MPa for extreme conditions and 2MPa for optimal conditions, an acceptable value for the required application. The conclusion is that the electrolitic bath allows to work at different conditions and parameters without a significant variation of internal stresses. 7. Test of the injection moldTests have been carried out with various representative thermoplastic materials such as PP, PA, HDPE and PC, and it has been analysed the properties of the injected parts such as dimensions, weight, resistance, rigidity and ductility. Mechanical properties were tested by tensile destructive tests and analysis by photoelasticity. About 500 injections were carried out on this core, remaining under conditions of withstanding many more. In general terms, important differences were not noticed between the behavior of the specimens obtained in the core and the ones from the machined cavity, for the set of the analysed materials. However in the analysis by photoelasticiy (Fig. 7) it was noticed a different tensional state between both types of specimens, basically due to differences in the heat transference and rigidity of the respective mold cavities. This difference explains the ductility variations more outstanding in the partially crystalline materials such as HDPE and PA 6. Fig. 7.Analysis by photoelasticity of injected specimens.For the case of HDPE in all the analysed tested tubes it was noticed a lower ductility in the specimens obtained in the nickel core, quantified about 30%. In the case of PA 6 this value was around 50%. 8. ConclusionsAfter consecutive tests and in different conditions it has been checked that the nickel sulfamate bath, with the utilized additives has allowed to obtain nickel shells with some mechanical properties acceptable for the required application, injection molds, that is to say, good reproducibility, high level of hardness and good mechanical resistance in terms of the resultant laminar structure. The mechanical deficiencies of the nickel shell will be partially replaced by the epoxy resin that finishes shaping the core for the injection mold, allowing to inject medium series of plastic parts with acceptable quality levels. References1 A.E.W. Rennie, C.E. Bocking and G.R. Bennet, Electroforming of rapid prototyping mandrels for electro discharge machining electrodes, J. Mater. Process. Technol. 110 (2001), pp. 186196. 2 P.K.D.V. Yarlagadda, I.P. Ilyas and P. Chrstodoulou, Development of rapid tooling for sheet metal drawing using nickel electroforming and stereo lithography processes, J. Mater. Process. Technol. 111 (2001), pp. 286294. 3 J. Hart, A. Watson, Electroforming: A largely unrecognised but expanding vital industry, Interfinish 96, 14 World Congress, Birmingham, UK, 1996. 4 M. Monzn et al., Aplicacin del electroconformado en la fabricacin rpida de moldes de inyeccin, Revista de Plsticos Modernos. 84 (2002), p. 557. 5 L.F. Hamilton et al., Clculos de Qumica Analtica, McGraw Hill (1989). 6 E. Julve, Electrodeposicin de metales, 2000 (E.J.S.). 7 A. Watson, Nickel Sulphamate Solutions, Nickel Development Institute (1989). 8 A. Watson, Additions to Sulphamate Nickel Solutions, Nickel Development Institute (1989). 9 J. Dini, Electrodeposition Materials Science of Coating and Substrates, Noyes Publications (1993). 10 J.W. Judy, Magnetic microactuators with polysilicon flexures, Masters Report, Department of EECS, University of California, Berkeley, 1994. (cap. 3). How Surface Treatments Keep Molds Operating LongerImportant tips and information about mold coatings to help you achieve the level of production that you and your customers desire. By Steven . Bales Mold making technology January 2006AbstractTheres an awful lot to know these days about molding plastic and how to get the very best performance from the valuable tools you build or run. This guide has been written to provide important tips and information about mold coatings. After reading this, you should have a very good idea of what coatingsfrom the very traditional to the very latestwill help you to achieve the level of production you and your customers desire. After all, these tools are an investment and they need to be protected for the life of the products they mold.Key Wordsmold coatings preventive maintenance (PM) program benefit nickel Cobalt diamond-chrome nickel-PTFE nickel-boron nitride electroless nickel textureThe Key Role of CoatingsBefore introducing you to the wide range of coatings on the market today, its important to note the role coatings can play in an effective preventive maintenance (PM) program.PM is really the key to protecting your tooling, your investment. Why? Because it saves time and money. Once you invest in a mold coating to improve tool performance, then a PM program is always a good idea to ensure you get the maximum benefit. These two steps should be a given in any shop.Remember, no coating lasts forever, and producing substandard parts from a mold with a worn coating is no way to win customers and stay profitable. PM is probably the most cost-effective strategy you can put in place. The key is to educate your personnel on how mold coatings wear during production. Every coating is different, so its of benefit to have employees learn how to tell when the coating is showing deterioration, especially in high-wear areas such as gates and runners. For example, wear in and around gate areas plated with hard chrome is the first sign that your mol
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