喜歡這套資料就充值下載吧。。。資源目錄里展示的都可在線預(yù)覽哦。。。下載后都有,,請放心下載,,文件全都包含在內(nèi),,【有疑問咨詢QQ:1064457796 或 1304139763】
題目名稱
諾基亞手機上殼體注塑模具設(shè)計
設(shè)
計
內(nèi)
容
及
設(shè)
計
要
求
隨著中國制造業(yè)的快速發(fā)展,塑料的應(yīng)用領(lǐng)域日趨廣泛,用量不斷增加,尤其是工程塑料由于具有更優(yōu)異的性能而成為增長速度最快的塑料品種。國內(nèi)工程塑料市場前景廣闊,有著巨大的發(fā)展?jié)摿Γ芰鲜请娮有畔?、交通運輸、航空航天、機械制造業(yè)的上游產(chǎn)業(yè),在國民經(jīng)濟中占據(jù)著重要的地位。
本課題是設(shè)計手機外殼注塑模具,要求設(shè)計的模具制造方便,充分考慮制件設(shè)計特點特色,盡量減少后加工;效率高,使用安全可靠;模具零件應(yīng)當(dāng)耐磨、耐用。設(shè)計時首先進行塑件分析,明確塑件設(shè)計要求和生產(chǎn)批量,計算塑件的體積和質(zhì)量,然后選用注塑機;進行模具有關(guān)設(shè)計計算;進行模具結(jié)構(gòu)設(shè)計;模具總體尺寸的確定,選擇模架;進行注塑機參數(shù)的校核;繪制模具裝配圖和零件圖。
主要技術(shù)路線包括:
一、接受任務(wù)書
二、收集、分析、消化原始資料
三、確定成型方法
四、選擇成型設(shè)備
五、具體結(jié)構(gòu)方案:
六、整理資料進行歸檔
主
要
設(shè)
計
參
數(shù)
材料:ABS塑料
形狀總體為長方形: 長為102mm、寬為45mm、高為9mm、壁厚為1.5 mm。
塑件表面質(zhì)量:
手機外殼的外表面要求較高,不能有任何缺陷、毛刺或飛邊存在,此處采用5級精度。表面粗糙度Ra為0.5um;內(nèi)表面要求無明顯質(zhì)量缺陷
學(xué)
生
應(yīng)
完
成
設(shè)
計
工
作
量
1、開題報告一份(不少于3000字)
2、完成模具裝配圖一張(為A0)和零件圖若干(拆合A0幅面圖紙至少二張),還有一張手工繪制(至少為A1)其余均采用計算機出圖。利用Pro/E繪制相關(guān)零件圖,裝配圖。
3、設(shè)計說明書一份(不少于1萬字)
4、外文資料翻譯不少于原文單詞3000
建
議
進
度
第一周:確定畢業(yè)設(shè)計題目,收集與課題相關(guān)的資料,完成開題報告
第二周:外文文獻的翻譯
第三周:注塑產(chǎn)品三維結(jié)構(gòu)設(shè)計
第四周:設(shè)計澆注系統(tǒng),設(shè)計分型面
第五周:成型零件計算
第六周:側(cè)向分型與抽芯機構(gòu)的設(shè)計
第七周:冷卻系統(tǒng)的設(shè)計
第八周:繪制模具裝配圖及相關(guān)零件圖
第九周:編寫說明書及其畢業(yè)成果
第十周:指導(dǎo)老師批改,修改設(shè)計及完善設(shè)計成果,準(zhǔn)備答辯。
參
考
資
料
(1) 陸 寧. 實用注塑模設(shè)計. 北京:中國輕工業(yè)出版社. 1997.5.
(2)《塑料模設(shè)計手冊》編寫組 編著. 北京:機械工業(yè)出版社 .2006.3 .
(3) 齊曉杰.《塑料成型工藝及模具設(shè)計》.北京:機械工業(yè)出版社.2005.10.
(4) 屈華昌.《.塑料成型工藝與模具設(shè)計》.北京:機械工業(yè)出版社.2003.3.
(5) 洪慎章.《實用注塑成型及模具設(shè)計》.北京:機械工業(yè)出版社.2006.1.
(6) 徐佩弘.《塑料制品與模具設(shè)計》.北京:中國輕工業(yè)出版社.2001.7.
(7)《模具設(shè)計與制造技術(shù)教育叢書》編委會編的《模具結(jié)構(gòu)設(shè)計》.北京:機械工業(yè)出版社.2005.6
(8) 關(guān)興舉.Pro/ENGINEER塑料產(chǎn)品設(shè)計.北京:人民郵電出版社.2006.1.
(9) 樊增輝. 凸模吸塑成型抽芯機構(gòu)設(shè)計[J]. 模具工業(yè) ,2005.(11) .
(10) 劉俊松. 聯(lián)合抽芯機構(gòu)設(shè)計[J]. 模具制造 ,2004,(06).
(11) 劉金楚. 注塑模的擺動抽芯機構(gòu)[J]. 模具工業(yè) , 2006.(01).
(12) Johnson L, Olley P, Coates PD. Plast Rubber Compos 2000;29-31.
(13) D.F. Mielewski, D.R. Bauer, P.J. Schmitz, H. Van, Weld line morphology of injection molded polypropylene, Polymer Engineering and Science 38 (1998) 2020–2028.
題目來源
工程生產(chǎn)
題目類型
設(shè)計
教
研
室
意
見
教研室主任:
年 月 日
學(xué)
院
意
見
學(xué)院負(fù)責(zé)人:
年 月 日
院畢業(yè)設(shè)計指導(dǎo)委員會
意見
指導(dǎo)委員會主任:
年 月 日
備注:1)題目來源:工程實際、科研項目、實驗室建設(shè)、教師自擬、其它;
2)題目類型:設(shè)計、軟件、實驗、綜述、論文、其它。
機電學(xué)院
畢業(yè)設(shè)計(論文)任務(wù)書
指導(dǎo)教師: 李曉冬
專 業(yè):機械設(shè)計制造及其自動化
班 級: 機制0444
學(xué)生姓名: 張 維 俏
學(xué) 號: 04A413405
長 春 工 程 學(xué) 院
長春工程學(xué)院機電學(xué)院畢業(yè)設(shè)計(論文)
外 文 翻 譯
外文題目:Automated surface finishing of plastic injection mold steel with spherical grinding and ball burnishing processes
專業(yè)名稱: 機制0444班
指導(dǎo)教師: 李曉冬
學(xué)生姓名: 張維俏
畢業(yè)設(shè)計(論文)
諾基亞手機上殼體注塑模具設(shè)計
The injection modeling design for the Nokia mobilephone upper shell
學(xué)生姓名
所在院系
所學(xué)專業(yè)
所在班級
指導(dǎo)教師
教師職稱
完成時間
: 張維俏
: 機電學(xué)院
: 機械設(shè)計制造及其自動化
: 機制0444班
: 李曉冬
: 講師
: 2008年6年20日
長 春 工 程 學(xué) 院
2004級本科畢業(yè)設(shè)計(論文)開題報告
設(shè)計(論文)題目:諾基亞手機上殼體注塑模具設(shè)計
姓 名: 張維俏 專 業(yè):機械設(shè)計制造及其自動化
班 級: 機制0444班 學(xué) 號: 04A413405
指 導(dǎo) 教 師: 李曉冬 職 稱/學(xué) 歷: 講師/博士
長春工程學(xué)院機電學(xué)院
二00 八 年 四 月 八 日
1.1課題研究的目的與意義??
目的與意義:
隨著塑料成型加工機械和成型模具的迅速增長,高效率、自動化、大型、微型、精密、高壽命的模具在整個模具產(chǎn)量中所占比例越來越大。從模具設(shè)計和制造技術(shù)角度來看,模具的發(fā)展趨勢可歸納為以下幾個方面:
??????? 1、?? 加深理論研究??? 在模具設(shè)計中,對工藝原理的研究越來越深入,模具設(shè)計已經(jīng)由經(jīng)驗設(shè)計階段逐漸向理論計算方面以發(fā)展。
????? ??2、 高效率、自動化??? 大量采用各種高效率、自動化的模具結(jié)構(gòu),如高效冷卻以縮短成型周期;各種能可靠地自動脫出產(chǎn)品和流道凝料的脫模機構(gòu);熱流道澆注系統(tǒng)注射出模具等。高速自動化的塑料成型機械配合以先進的模具,對提高生產(chǎn)效率,降低成本起了很大作用。
??????? 3、?? 大型、超小型及高精度? 由于模料應(yīng)用的擴大,塑料制件已應(yīng)用到建筑、機械、電子、儀器、儀表等各個工業(yè)領(lǐng)域,于是出現(xiàn)了各種大型、精密和高壽命的成型模具,為了滿足這些要求,研制了高強度、高硬度、高耐磨性能且易加工,熱處理變小、導(dǎo)熱性能優(yōu)異的制模材料。
??????? 4、? 革命模具制造工藝??? 為了更新產(chǎn)品花式和適應(yīng)小批量產(chǎn)品的生產(chǎn)要求,除大力發(fā)展高強度、高耐磨性的材料外,同時又重視簡易制模工藝研究。
??????? 5、?? 標(biāo)準(zhǔn)化??? 開展模具標(biāo)準(zhǔn)化工作,使模板,導(dǎo)柱等通用零件標(biāo)準(zhǔn)化、商品化,以適應(yīng)大規(guī)模地成批生產(chǎn)塑料成型模具。
通過本次諾基亞8610手機前殼體注塑模具設(shè)計,使自己能夠?qū)臅局袑W(xué)到的理論知識與生產(chǎn)實際相結(jié)合,進一步強化自己對注塑模具設(shè)計設(shè)計流程的熟悉,能夠熟練查閱注塑模具設(shè)計手冊及相關(guān)書籍,熟練掌握pro/e軟件的操作過程。熟練掌握繪圖和編寫技術(shù)文件的能力。手機已成為日益普遍的通訊工具,因此其注塑模具的需求也日益增多,市場前景廣泛,而且根據(jù)不同手機的外形的不同,注塑模具也就有了很大的不同。因此通過對這款手機外殼模具的設(shè)計,增強了自己獨立設(shè)計注塑模具的能力。
在網(wǎng)絡(luò)化和數(shù)字化迅猛發(fā)展的今天,手機已經(jīng)成為引領(lǐng)消費時尚的異軍突起的工業(yè)產(chǎn)品。2007年國內(nèi)手機產(chǎn)量有望突破4億部,占全球總產(chǎn)量的50%,手機出口額達(dá)到133億美元。因此手機外殼注射模具的設(shè)計有廣泛的市場應(yīng)用前景。
1.2文獻綜述(相關(guān)課題國內(nèi)外研究的現(xiàn)狀)
國外方面:
隨著全球經(jīng)濟的發(fā)展,新的技術(shù)革命不斷取得新的進展和突破,技術(shù)的飛躍發(fā)展已經(jīng)成為全世界經(jīng)濟增長的重要因素。市場經(jīng)濟的不斷發(fā)展,促使工業(yè)產(chǎn)品越來越向多品種、小批量、高質(zhì)量、低成本的方向發(fā)展,為了保持和加強產(chǎn)品在市場上的競爭力,產(chǎn)品的開發(fā)周期、生產(chǎn)周期越來越短,于是對制造各種產(chǎn)品的關(guān)鍵工藝裝備—模具的要求越來越苛刻。
國外注塑成型技術(shù)在向多工位、商效率、自動化、連續(xù)化、低成本方向發(fā)展。因此.模具向高精度復(fù)雜、多功能的方向發(fā)展.例如:組合模、即鈑金和注塑一體注塑鉸鏈一體注塑、活動周轉(zhuǎn)箱一體注塑;多色注塑等;向高效率、高自動化和節(jié)約能源降低成本的方向發(fā)展 例如:疊模的大量制造和應(yīng)用.水路設(shè)計的復(fù)雜化、裝夾的自動化、取件全部自動化。
國外模具工廠運行的現(xiàn)狀介紹。21世紀(jì)模具制造行業(yè)的基本特征是高度集成化、智能化、柔性化和網(wǎng)絡(luò)化。追求的目標(biāo)是提高產(chǎn)品質(zhì)量及生產(chǎn)效率。縮短設(shè)計周期及制造周期,降低生產(chǎn)成本,最大限度地提高模具制造業(yè)的應(yīng)變能力滿足用戶需求。
國內(nèi)方面:
80年代以來,在國家產(chǎn)業(yè)政策和與之配套的一系列國家經(jīng)濟政策的支持和引導(dǎo)下,我國模具工業(yè)發(fā)展迅速,均增速均為13%,1999年我國模具工業(yè)產(chǎn)值為245億,至2002年我國模具總產(chǎn)值約為360億元,其中塑料模約30%右。在未來的模具市場中,塑料模在模具總量中的比例還將逐步提高。
我國塑料模具工業(yè)從起步到現(xiàn)在,歷經(jīng)半個多世紀(jì),有了很大發(fā)展,模具水平有了較大提高。在大型模具方面能生產(chǎn)48英寸大屏幕彩電塑殼注射模具、6.5Kg大容量洗衣機全套塑料模具以及汽車保險杠和整體儀表板等塑料模具,精密塑料模具方面,已能生產(chǎn)照相機塑料件模具、多型腔小模數(shù)齒輪模具及塑封模具。如天津的津榮天和機電有限公司和煙臺北極星Ⅰ.K模具有限公司制造多腔VCD和DVD齒輪模具,所生產(chǎn)的這類齒輪塑件的尺寸精度、同軸度、跳動等要求都達(dá)到了國外同類產(chǎn)品的水平,而且還采用最新的齒輪設(shè)計軟件,糾正了由于成型收縮造成齒形誤差,達(dá)到了標(biāo)準(zhǔn)漸開線齒形要求。還能生產(chǎn)厚度僅為0.08mm的一模兩腔的航空杯模具和難度較高的塑料門窗擠出模等等。注塑模型腔制造精度可達(dá)0.02mm~0.05mm,表面粗糙度Ra0.2μm,模具質(zhì)量、壽命明顯提高了,非淬火鋼模壽命可達(dá)10~30萬次,淬火鋼模達(dá)50~1000萬次,交貨期較以前縮短,但和國外相比仍有較大差距。
近年來我國通過引進國際的先進技術(shù)和加工設(shè)備,使塑料模具的制造水平比十年前進了一大步,然而由于基礎(chǔ)薄弱、對引進技術(shù)的吸收、掌握,尚有一段距離,而且發(fā)展也十分不平衡,因而,我國塑料模具總體水平與世界先進技術(shù)尚有一定差距。塑料成型模具可分為三大類,即注射成型模具、中空成型模具和擠出成型模具。我國現(xiàn)在的制造水平,以注射成型模具為最高,中空成型具為最低,如化妝品用瓶子的吹塑模具,無論從造型以及質(zhì)量上遠(yuǎn)不能適應(yīng)出口要求。
從注塑工藝來說,氣體輔助注射成型、結(jié)構(gòu)泡沫成型、反應(yīng)注射成型、共注射成型、推-拉成型、注射-壓縮成型、低壓注射成型、交變注射成型、熔芯注射成型、動態(tài)保壓注射成型等引入了模內(nèi)反應(yīng)、發(fā)泡、振動和氣輔等關(guān)鍵技術(shù),大大豐富了傳統(tǒng)注塑工藝的內(nèi)容,使塑料的流動特性、制品的力學(xué)性能、外觀質(zhì)量都得到有效的控制。當(dāng)然,這些新型注塑工藝所要求的注塑機和模具系統(tǒng)等機械、壓力和電氣系統(tǒng)控制也有別與傳統(tǒng)注塑機。
近年來,國內(nèi)已較廣泛地采用一些新的塑料模具鋼,如:P20、3Cr2Mo、PMS、SMⅠ、SMⅡ等,對模具的質(zhì)量和使用壽命有著直接的重大的影響,但總體使用量仍較少。塑料模標(biāo)準(zhǔn)模架、標(biāo)準(zhǔn)推桿和彈簧等越來越廣泛地得到應(yīng)用,并且出現(xiàn)了一些國產(chǎn)的商品化的熱流道系統(tǒng)元件。但目前我國模具標(biāo)準(zhǔn)化程度和商品化程度一般在30%以下,和國外先進工業(yè)國家已達(dá)到70%-80%相比,仍有很大差距。
當(dāng)今,中國塑料工業(yè)已步人世界塑料先進大國的行列,塑料機械與模具、塑料制品與應(yīng)用,塑料樹脂與助劑,總的生產(chǎn)量和消費量都分別躍居世界的第一、第二、第三位,為世人所關(guān)注。因為,從此結(jié)束了我國塑料工業(yè)長期 利用國產(chǎn)裝備生產(chǎn)高精密塑料制品的歷史!宣告我國塑料制品行業(yè)已真正步入精密化、微型化時代!
1.3采用的設(shè)計方案(基本理論)與技術(shù)路線
方案確定
經(jīng)分析,根據(jù)塑件的表面粗糙度,及生產(chǎn)的規(guī)模,選用單分型面注射模,一模一件。
單分型面注射模 型腔在定模上;主流道設(shè)在定模一側(cè),分流道設(shè)在分型面上,開模后塑件連同流道內(nèi)的凝料一起留在動模一側(cè);動模上設(shè)有頂出機構(gòu),用以頂出塑件和流道內(nèi)的凝料??赡艿臐部谛问接校褐苯訚部凇?cè)澆口、重疊澆口等,從中選擇點澆口。
技術(shù)路線
1. 進行產(chǎn)品工藝性分析:(1)材料性能(2)成型特性及條件(3)結(jié)構(gòu)工藝性(4)批量生產(chǎn)(5)零件體積及質(zhì)量估算。
2. 初選注塑機型號和規(guī)格。
3. 確定模具基本結(jié)構(gòu)(單分型面注射模)。
4. 模具結(jié)構(gòu)設(shè)計:(1)確定型腔數(shù)目及配置(2)選擇分型面(3)確定澆注系統(tǒng)尺寸(4)校核計算(5)確定型腔、型芯的結(jié)構(gòu)(6)確定頂出機構(gòu)類型(7)側(cè)向分型與抽芯機構(gòu)的設(shè)計(8)確定導(dǎo)向機構(gòu)(9)排氣機構(gòu)。
5. 繪制模具裝配草圖。
6. 校核加工性能;核算輔助工具的主要工作尺寸并拆畫零件圖。
7. 試模及修模。
1.4研究內(nèi)容及擬解決的關(guān)鍵問題:
1. 模具的冷卻和加熱問題。
2. 進澆點和分型面的選擇問題。
3. 注塑機的合理選擇。
4. 模具總體結(jié)構(gòu)和零件形狀要簡單合理;模具應(yīng)具有適當(dāng)?shù)木取偠群蛷姸取?
5. 易于制造和裝配。
1.5參考文獻
(1) 陸 寧. 實用注塑模設(shè)計. 北京:中國輕工業(yè)出版社, 1997.5.
(2)《塑料模設(shè)計手冊》編寫組. 北京:機械工業(yè)出版社 ,2006.3.
(3) 齊曉杰.《塑料成型工藝及模具設(shè)計》.北京:機械工業(yè)出版社,2005.10.
(4) 屈華昌.《塑料成型工藝與模具設(shè)計》.北京:機械工業(yè)出版社,2003.3.
(5) 洪慎章.《實用注塑成型及模具設(shè)計》.北京:機械工業(yè)出版社,2006.1.
(6) 徐佩弘.《塑料制品與模具設(shè)計》.北京:中國輕工業(yè)出版社,2001.7.
(7)《模具設(shè)計與制造技術(shù)教育叢書》編委會.《模具結(jié)構(gòu)設(shè)計》.北京:機械工業(yè)出版社,2005.6.
(8) 關(guān)興舉.《Pro/ENGINEER塑料產(chǎn)品設(shè)計》.北京:人民郵電出版社,2006.1.
(9) 樊增輝. 凸模吸塑成型抽芯機構(gòu)設(shè)計[J]. 模具工業(yè) ,2005.(11).
(10) 劉金楚. 注塑模的擺動抽芯機構(gòu)[J]. 模具工業(yè) , 2006.(01).
(11) Johnson L, Olley P, Coates PD. Plast Rubber Compos 2000:29-31.
(12) D.F. Mielewski, D.R. Bauer, P.J. Schmitz, H. Van, Weld line morphology of injection molded polypropylene, Polymer Engineering and Science 38 (1998) :2020–2028.
2、答辯組論證結(jié)論
(1)方案可行,技術(shù)路線清晰 □ (2)方案可行,技術(shù)路線基本清晰 □
(3)方案基本可行,技術(shù)路線不很清晰 □ (4)方案和技術(shù)路線不很清晰 □
(5)方案和技術(shù)路線不清晰 □
3、指導(dǎo)教師意見: 教研室主任意見:
指導(dǎo)教師(簽名): 教研室主任(簽名):
年 月 日 年 月 日
注:(1) 開題報告是用文字體現(xiàn)的設(shè)計(論文)總構(gòu)想,篇幅不必過大,但要把計劃設(shè)計的課題、如何設(shè)計、理論依據(jù)和研究現(xiàn)狀等主要問題說清楚;
(2) 字?jǐn)?shù)不少于3000字,參考文獻不少于6篇,印刷字符在10萬印刷符以上。
目 錄
1 前 言 1
1.1 課題的目的、意義及設(shè)計任務(wù) 1
1.2 我國塑料模具發(fā)展趨勢分析 1
1.3 注射成型原理及工藝 3
1.3.1 注射成型原理 3
1.3.2 注射成型工藝過程 3
2 注塑產(chǎn)品分析 4
2.1 塑件的工藝性分析 4
2.2 塑件的結(jié)構(gòu)尺寸及表面質(zhì)量分析 5
2.2.1 結(jié)構(gòu)分析 5
2.2.2 塑件表面質(zhì)量分析 5
2.3 塑件體積和質(zhì)量的計算 6
2.3.1 計算塑件體積 6
2.3.2 計算塑件質(zhì)量 6
3 選擇注射機 6
4 澆注系統(tǒng)的設(shè)計 7
4.1 主流道設(shè)計 8
4.2 分流道設(shè)計 8
4.3 澆口的設(shè)計 9
4.4 定位環(huán)及澆口套 10
5 分型面和型腔數(shù)目的確定 11
5.1 選擇分型面 11
5.2 型腔數(shù)的確定 11
6 成型零件設(shè)計 12
6.1 型腔及型芯的設(shè)計 12
6.1.1 凹模的設(shè)計 12
6.1.2 凸模的設(shè)計 13
6.2 工作尺寸計算 13
6.2.1 凹模的工作尺寸計算 13
6.2.2 凸模的工作尺寸計算 14
6.2.3 型芯側(cè)壁計算 15
7 導(dǎo)向機構(gòu)設(shè)計 15
7.1 導(dǎo)柱與導(dǎo)套的選擇 15
7.2 導(dǎo)柱導(dǎo)套的設(shè)計原則 16
8 脫模機構(gòu)設(shè)計 17
8.1 頂出機構(gòu)的設(shè)計原則 17
8.1.1 頂出機構(gòu)的設(shè)計原則 17
8.2 頂出力的計算 17
8.3 脫模力計算 18
8.4 推桿直徑確定 19
9 模架的選擇 20
9.1 各模板尺寸的確定 20
9.2 模架的確定 21
10 側(cè)向分型與抽芯機構(gòu)設(shè)計 21
10.1 側(cè)向分型與抽芯機構(gòu)的分類和特點 21
10.2 抽拔力的計算 22
10.3 抽芯距 23
10.4 斜導(dǎo)柱傾斜角 23
10.5 斜導(dǎo)柱的直徑 23
10.6 斜導(dǎo)柱的長度和最小開模行程的計算 23
10.7 導(dǎo)滑部分設(shè)計 24
10.7.1 滑塊 24
10.7.2 滑塊的定位裝置 24
10.7.3 壓緊塊 24
10.7.4 抽芯時的干涉現(xiàn)象 25
10.7.5 斜滑塊內(nèi)抽芯機構(gòu) 25
11 冷卻系統(tǒng)的設(shè)計 25
11.1 冷卻系統(tǒng)的設(shè)計原則 25
11.2 冷卻管道傳熱面積及管道數(shù)目的計算 26
12 有關(guān)參數(shù)校核 28
12.1 注塑機參數(shù)校核 28
12.2 注塑機鎖模力校核 28
12.3 模具長寬尺寸的校核 28
12.4 模具閉合高度的校核 28
12.5 開模行程校核 28
總 結(jié) 29
參考文獻 30
致 謝 31
附錄一 32
8Fang-Jung Shiou · Chao-Chang A. Chen · Wen-Tu Li
注塑模表面自動化磨削和拋光的過程
發(fā)表日期: 2004年3月30日: 2004年7月5日 網(wǎng)上公布: 2005年3月30日?斯普林格-柏林出版社,倫敦有限公司2005年
摘要:本文探討在數(shù)控加工中心中對注塑模上任意一個自由表面進行自動化磨削和拋光過程的可能性。作者在本文中已經(jīng)完成了磨削和拋光工具的設(shè)計和制造。在加工中心的注塑模使用Taguchi正交矩陣方法確定其最佳表面磨削參數(shù)。注塑模的最佳表面參數(shù)為:磨削材料為 ,磨削速度為,磨削深度為,進給速度為。通過使用最佳磨削參數(shù)的平磨可使其表面粗糙度從提高到,使用最佳拋光參數(shù)的拋光過程可使其表面粗糙度從提高到,將最佳表面磨削和拋光參數(shù)運用到自由表面模腔,其部分表面粗糙度值可從提高到。
關(guān)鍵字:自動表面拋光,拋光加工,磨削加工,表面粗糙度,Taguchi方法
1 介紹
塑料是重要的工程材料,由于其具有特定的特點:如耐腐蝕性,抗化學(xué)品的腐蝕,密度低,并且易于制造,在工業(yè)應(yīng)用上已日益取代金屬部件。注射成型工藝在塑料產(chǎn)品中是一個重要的成形過程。表面加工的質(zhì)量是注塑模的一個重要要求,因為它直接影響塑膠產(chǎn)品的外觀。加工過程中的拋光和研磨被普遍使用來改善工件表面光潔度。
展開磨削已被廣泛應(yīng)用于傳統(tǒng)模具加工行業(yè)。展開磨削的自動化表面加工過程的幾何模型將在【1】中介紹。球面磨削加工使自動化表面加工系統(tǒng)被提高了【2】。磨削速度,切削深度,進給速度,磨具屬性,如研磨材料和磨料粒大小,在球形磨削過程中起主導(dǎo)作用,如圖1所示。注塑模具的最優(yōu)球面磨削參數(shù)尚未被證實。
近幾年來,一些確定拋光過程最佳參數(shù)的研究已經(jīng)進在行了。舉例來說,現(xiàn)在已發(fā)現(xiàn)塑料變形可使工件表面減少使用碳化鎢材料,從而改善其表面粗糙度,表面硬度,抗疲勞強度[ 3-6 ] 。拋光過程是通過加工中心[ 3,4]和車床[ 5 ,6 ] 來完成年的。主要拋光參數(shù)對球或滾子材料的表面的粗糙度具有重大作用,拋光力,進給速度,拋光速度,潤滑,其他的拋光途徑,其中包括[ 3 ] 。注塑模的最佳表面拋光參數(shù)是一種組合的油脂潤滑劑,碳化鎢材料,拋光速度,拋光力,進給 [ 7 ] 。拋光表面采用最佳球面拋光參數(shù)的滲透速度為2.5微米。通過拋光過程來改善表面粗糙度的概率一般在到 [ 3-7 ] 。
圖1.磨削過程示意圖
圖2 .拋光過程示意圖
本研究的主要目的是提高加工中心注塑模具自由表面的磨削和拋光光潔度。自動化表面磨削和拋光過程的流程圖如圖。我們給加工中心設(shè)計和制造球面磨削工具及其對準(zhǔn)裝置,最佳球面磨削參數(shù)的特定是利用Taguchi正交矩陣方法。四個因素和三個相應(yīng)條件,然后挑選Taguchi正交矩陣方法矩陣進行實驗。表面研磨的最佳展開球面磨削參數(shù)被應(yīng)用到自由曲面加工過程中。用最佳球面拋光參數(shù)來改善表面粗糙度和光潔度。
2 設(shè)計球面磨削工具及其對準(zhǔn)裝置
從自由表面的球面磨削過程進行的可能性看,球面磨削中心應(yīng)在加工中心的軸,展開磨削的工具及調(diào)節(jié)裝置的設(shè)計如圖所示。電動磨床是安裝在兩個可調(diào)樞軸螺釘之間。該磨床中心的磨削球借助圓錐曲線溝槽的對齊組件和圓錐形凹線進行的良好的排列。排列好的研磨球被兩個可調(diào)螺釘固定,之后,對準(zhǔn)元件可以被撤銷。球面磨床的中心坐標(biāo)和它的偏差在左右,它是由數(shù)控坐標(biāo)測量機測量。機床振動導(dǎo)致的力被螺旋型彈簧吸收。球面磨削工具和球面拋光工具的安裝如圖所示,主軸被鎖,不論磨削過程還是拋光過程由主軸鎖定。
圖.4.球面磨床工具及其調(diào)整示意圖
3 矩陣實驗的步驟
3.1 Taguchi正交陣列的結(jié)構(gòu)
用Taguchi正交矩陣[ 8 ]做矩陣實驗要求那些參數(shù)的影響是有效地。為了配合上述球面磨削參數(shù)的要求,在本研究中磨削的材料(直徑10毫米),進給速度,磨削深度,電動磨床的轉(zhuǎn)速被選定為四個實驗因素(參數(shù))并被指定為因子A至D (見表1 )。并為每個素設(shè)定了3個等級來包含它們所涉及的范圍,用數(shù)字1、2、3來標(biāo)識。每個因素的3個
表1 .實驗因素和層次
因素 等級
1
2
3
:研磨材料
WA
,PA
:進給速度
50
100
200
:磨削深度
20
20
80
:轉(zhuǎn)數(shù)
12000
18000
24000
數(shù)值要求在在研究結(jié)果的基礎(chǔ)上來確定。第四個因素的第三級的磨削過程用正交矩陣來進行矩陣實驗。
3.2 數(shù)據(jù)分析
工程設(shè)計上的問題可以分成越小越好的類型,額定最佳類型,越大越好的類型,標(biāo)記目標(biāo)類型,其中還包括[ 8 ] 。該信號和噪音()的比例是用來作為優(yōu)化產(chǎn)品或工藝設(shè)計的目標(biāo)函數(shù)。經(jīng)過磨削參數(shù)的組合,其表面粗糙度值應(yīng)小于原來表面的粗糙度值。因此,球面磨削過程是越小越好類型問題的一個例子。該比,,是指由下列方程[ 8 ]定義的 :
(1)
結(jié)果:
:觀測表明,質(zhì)量特性是根據(jù)不同的噪聲條件來確定的
n :多次實驗
每個 正交矩陣計算的的比值顯示,每個因素的主要影響是由不同技術(shù)的分析和方差測試的結(jié)果來決定的 [ 8 ] 。解決越小越好問題的的最佳方法是取的最大值,由公式1來定義的。各個因素的最大值的選定將對有重大影響,然后就能確定球面磨削的最佳條件。
圖.6.實驗設(shè)置來確定最佳的球面磨削參數(shù)
4 實驗工作及結(jié)果
該材料用于工具鋼的研究[ 9 ] ,這是常用于在汽車部件和家用器具領(lǐng)域的大型注塑模具制品。這種材料的優(yōu)越性在于經(jīng)過加工后,模具可以直接用于其特殊前處理未經(jīng)熱處理的進一步加工過程。該產(chǎn)品的設(shè)計制造使它們可以被要求裝在動力架上來測量其動力。經(jīng)過簡單加工,然后裝在動力架上對3坐標(biāo)加工中心進行測量,該加工中心由Yang-Iron公司生產(chǎn),配備了FUNUC公司數(shù)控控制器。運用Hommelwerke T4000設(shè)備對預(yù)加工表面粗糙度的測量,大約為。圖6顯示了實驗開始時的球面磨削過程,由Renishaw公司生產(chǎn)的觸發(fā)器結(jié)合加工中心刀具參數(shù)來測量和協(xié)調(diào)該制品。該拋光路徑由PowerMILL CAM軟件生成數(shù)控代碼。這些代碼可以同步傳送到數(shù)控加工中心的RS232串行接口中。
表2總結(jié)了表面粗糙度值Ra的測量和用公式1計算每個正交矩陣的值,然后進行真叫矩陣材料實驗。通過的平均值可以得到每個級別的4個因素,在表3中列表,其數(shù)字在表2中列出。其示意圖如圖7所示。
圖 .7 控制因素的影響
表2 . 標(biāo)本表面粗糙度
年限
序號
內(nèi)部陣列
(控制因素)
衡量表面
粗糙度值()
結(jié)果
A
b
C
D
y1(μm)
y2(μm)
y3(μm)
S/N比例(dB)
平均值(μ m)
1
1
1
1
1
0.35
0.35
0.35
9.119
0.35
2
1
2
2
2
0.37
0.36
0.38
8.634
0.37
3
1
3
3
3
0.41
0.44
0.40
7.597
0.417
4
2
1
2
3
0.63
0.65
0.64
3.876
0.640
5
2
2
3
1
0.73
0.77
0.78
2.380
0.760
6
2
3
1
2
0.45
0.42
0.39
7.520
0.42
7
3
1
3
2
0.34
0.31
0.32
9.801
0.323
8
3
2
1
3
0.27
0.25
0.28
11.471
0.267
9
3
3
2
1
0.32
0.32
0.32
9.897
0.320
10
1
1
2
2
0.35
0.39
0.40
8.390
0.380
11
1
2
3
3
0.41
0.50
0.43
6.968
0.447
12
1
3
1
1
0.40
0.39
0.42
7.883
0.403
13
2
1
1
3
0.33
0.34
0.31
9.712
0.327
14
2
2
2
1
0.48
0.50
0.47
6.312
0.483
15
2
3
3
2
0.57
0.61
0.53
4.868
0.570
16
3
1
3
1
0.59
0.55
0.54
5.030
0.560
17
3
2
1
2
0.36
0.36
0.35
8.954
0.357
18
3
3
2
3
0.57
0.53
0.53
5.293
0.543
表3 . 各因素的比值的平均值(分貝)
因素
A
B
C
D
等級1
8.099
7.655
9.110
6.770
等級2
5.778
7.453
7.067
8.028
等級3
8.408
7.176
6.107
7.486
結(jié)果
2.630
0.479
3.003
1.258
等級
2
4
1
3
平均值
.428
其目的在于將磨削過程中的表面粗糙度值減到最小,確定每項因素的最佳等級。由于該函數(shù)為單調(diào)遞減函數(shù),我們應(yīng)定量增大值。因此,我們能確定每一項因素的最佳等級。其最高值為。因此,基于矩陣實驗,最佳研磨材料是粉紅氧化鋁(,PA),最佳進給速度為,最佳磨削深度為,最佳轉(zhuǎn)速為。如表4所示。
表4 .球面磨削的最佳參數(shù)
因素
等級
研磨材料
,PA
進給速度
50mm/min
磨削深度
20um
轉(zhuǎn)數(shù)
18000rpm
表5 .表面粗糙度比的方差分析表
因素
自由度
平方和
均方和
方差比
A
2
24.791
12.396
3.62
B
2
0.692
0.346
C
2
28.218
14.109
4.12
D
2
4.776
2.388
誤差
9
總計
17
匯集誤差
13
3.424
分析每一項因素的主要原因,進一步采用方差分析技術(shù)和F對比檢驗,以確定其定義(見表5)根據(jù)F分布表,是指F值在時,廢品率為,自由度數(shù)為2,匯集誤差為13.F值若大于,對表面粗糙度值有重大影響,因此,進給速度和磨削深度對表面粗糙度有重大影響。
表6 .被測樣品經(jīng)實驗測得的表面粗糙度值
年限。序號
實測值(Ra)
平均值(um)
S/N 比
Y1
Y2
Y3
1
0.30
0.31
0.33
0.313
10.073
2
0.36
0.37
0.36
0.363
8.802
3
0.36
0.37
0.37
0.367
8.714
4
0.35
0.37
0.34
0.353
9.031
5
0.33
0.36
0.35
0.347
9.163
平均值
0.349
9.163
通過觀察五個驗證實驗得出了用最佳拋光參數(shù)的可重復(fù)性,如表6所示。該表面粗糙度值被測量是大約.用最佳組合的球面磨削參數(shù)可使表面粗糙度大概提高了約78 % 。表面用最佳拋光參數(shù)進一步拋光。通過拋光后,表面粗糙度值可能達(dá)到。圖8顯示的是用30倍的的顯微鏡對拋光后的表面粗糙度進行觀察。拋光后預(yù)加工表面的粗糙度改進大約為。
從Taguchi正交矩陣實驗獲得的最佳磨削參數(shù)應(yīng)用到表面光潔度的自由曲面的模具插入評價表面粗糙度的改善。 1個香料被選定為測試載體。數(shù)控加工的模具,亞塞特為測試對象,模擬銑床 CAM軟件。模具插入進的地面與最優(yōu)球面磨削參數(shù)取自田口的矩陣實驗。拋光與最佳球拋光是地面的參數(shù),以進一步改善表面粗糙度的測試對象(見圖9 ) 。表面粗糙度模具插入測量儀器與霍梅爾有限公司 t4000設(shè)備。平均表面粗糙度值在未加工表面平均值;工件表面的平均值為,以及對拋光表面的平均值為。通過實驗后表面粗糙度的改進,工件表面大約為( 2月15日-0 45 / 2 15 = 79 1 % ,拋光表面大約為( 2月15日-0 07 / 2月15日= 96 7 % )。
圖. 8 用30倍的模具顯微鏡觀測比較加工前工件表面和加工后工件表面
圖. 9磨削和拋光模具中插入一個香水瓶
5 結(jié)論
這篇文章中,在一個加工中心對注塑模表面自動化磨削和拋光過程的最佳參數(shù)已經(jīng)研究出來。掛接球面磨削工具(和其對齊元件)的設(shè)計和制造方法 。最佳球面磨削參數(shù)是通過Taguchi的矩陣實驗來確定的。最佳球面磨削參數(shù)是注塑模pds5是研磨材料粉紅氧化鋁(,PA)的組合,進給速度,拋光深度的,轉(zhuǎn)速。利用最佳磨削參數(shù)來進行表面磨削可以使表面粗糙度從提高到。模具的自由表面加工運用最佳表面研磨和拋光參數(shù),測量的表面粗糙度有很大的提高,磨削表面大概為,拋光表面大概為。
11
DOI 10.1007/s00170-004-2328-8 ORIGINAL ARTICLE Int J Adv Manuf Technol (2006) 28: 6166 Fang-Jung Shiou Chao-Chang A. Chen Wen-Tu Li Automated surface finishing of plastic injection mold steel with spherical grinding and ball burnishing processes Received: 30 March 2004 / Accepted: 5 July 2004 / Published online: 30 March 2005 Springer-Verlag London Limited 2005 Abstract This study investigates the possibilities of automated spherical grinding and ball burnishing surface finishing pro- cesses in a freeform surface plastic injection mold steel PDS5 on a CNC machining center. The design and manufacture of a grinding tool holder has been accomplished in this study. The optimal surface grinding parameters were determined using Taguchis orthogonal array method for plastic injection molding steel PDS5 on a machining center. The optimal surface grind- ing parameters for the plastic injection mold steel PDS5 were the combination of an abrasive material of PA Al 2 O 3 , a grind- ing speed of 18 000 rpm, a grinding depth of 20 m, and a feed of 50 mm/min. The surface roughness R a of the specimen can be improved from about 1.60 mto0.35 m by using the optimal parameters for surface grinding. Surface roughness R a can be further improved from about 0.343 mto0.06 mbyusingthe ball burnishing process with the optimal burnishing parameters. Applying the optimal surface grinding and burnishing parame- ters sequentially to a fine-milled freeform surface mold insert, the surface roughness R a of freeform surface region on the tested part can be improved from about 2.15 mto0.07 m. Keywords Automated surface finishing Ball burnishing process Grinding process Surface roughness Taguchis method 1 Introduction Plastics are important engineering materials due to their specific characteristics, such as corrosion resistance, resistance to chemi- cals, low density, and ease of manufacture, and have increasingly F.-J. Shiou (a117) C.-C.A. Chen W.-T. Li Department of Mechanical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, 106 Taipei, Taiwan R.O.C. E-mail: shioumail.ntust.edu.tw Tel.: +88-62-2737-6543 Fax: +88-62-2737-6460 replaced metallic components in industrial applications. Injec- tion molding is one of the important forming processes for plas- tic products. The surface finish quality of the plastic injection mold is an essential requirement due to its direct effects on the appearance of the plastic product. Finishing processes such as grinding, polishing and lapping are commonly used to improve the surface finish. The mounted grinding tools (wheels) have been widely used in conventional mold and die finishing industries. The geometric model of mounted grinding tools for automated surface finish- ing processes was introduced in 1. A finishing process model of spherical grinding tools for automated surface finishing sys- tems was developed in 2. Grinding speed, depth of cut, feed rate, and wheel properties such as abrasive material and abrasive grain size, are the dominant parameters for the spherical grind- ing process, as shown in Fig. 1. The optimal spherical grinding parameters for the injection mold steel have not yet been investi- gated based in the literature. In recent years, some research has been carried out in de- termining the optimal parameters of the ball burnishing pro- cess (Fig. 2). For instance, it has been found that plastic de- formation on the workpiece surface can be reduced by using a tungsten carbide ball or a roller, thus improving the surface roughness, surface hardness, and fatigue resistance 36. The burnishing process is accomplished by machining centers 3, 4 and lathes 5, 6. The main burnishing parameters having signifi- cant effects on the surface roughness are ball or roller material, burnishing force, feed rate, burnishing speed, lubrication, and number of burnishing passes, among others 3. The optimal sur- face burnishing parameters for the plastic injection mold steel PDS5 were a combination of grease lubricant, the tungsten car- bide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N, and a feed of 40 m 7. The depth of penetration of the burnished surface using the optimal ball burnishing parameters was about 2.5 microns. The improvement of the surface rough- ness through burnishing process generally ranged between 40% and 90% 37. The aim of this study was to develop spherical grinding and ball burnishing surface finish processes of a freeform surface 62 plastic injection mold on a machining center. The flowchart of automated surface finish using spherical grinding and ball bur- nishing processes is shown in Fig. 3. We began by designing and manufacturing the spherical grinding tool and its alignment de- vice for use on a machining center. The optimal surface spherical grinding parameters were determined by utilizing a Taguchis orthogonal array method. Four factors and three corresponding levels were then chosen for the Taguchis L 18 matrix experiment. The optimal mounted spherical grinding parameters for surface grinding were then applied to the surface finish of a freeform surface carrier. To improve the surface roughness, the ground surface was further burnished, using the optimal ball burnishing parameters. Fig. 1. Schematic diagram of the spherical grinding process Fig. 2. Schematic diagram of the ball-burnishing process Fig. 3. Flowchart of automated surface finish using spherical grinding and ball burnishing processes 2 Design of the spherical grinding tool and its alignment device To carry out the possible spherical grinding process of a freeform surface, the center of the ball grinder should coincide with the z-axis of the machining center. The mounted spherical grinding tool and its adjustment device was designed, as shown in Fig. 4. The electric grinder was mounted in a tool holder with two ad- justable pivot screws. The center of the grinder ball was well aligned with the help of the conic groove of the alignment com- ponents. Having aligned the grinder ball, two adjustable pivot screws were tightened; after which, the alignment components could be removed. The deviation between the center coordi- nates of the ball grinder and that of the shank was about 5 m, which was measured by a CNC coordinate measuring machine. The force induced by the vibration of the machine bed is ab- sorbed by a helical spring. The manufactured spherical grind- ing tool and ball-burnishing tool were mounted, as shown in Fig. 5. The spindle was locked for both the spherical grinding process and the ball burnishing process by a spindle-locking mechanism. 63 Fig. 4. Schematic illustration of the spherical grinding tool and its adjust- ment device 3 Planning of the matrix experiment 3.1 Configuration of Taguchis orthogonal array The effects of several parameters can be determined efficiently by conducting matrix experiments using Taguchis orthogonal array 8. To match the aforementioned spherical grinding pa- rameters, the abrasive material of the grinder ball (with the diam- eter of 10 mm), the feed rate, the depth of grinding, and the revolution of the electric grinder were selected as the four experi- mental factors (parameters) and designated as factor A to D (see Table 1) in this research. Three levels (settings) for each factor were configured to cover the range of interest, and were identi- Fig. 5. a Photo of the spherical grinding tool b Photo of the ball burnishing tool Table 1. The experimental factors and their levels Factor Level 123 A. Abrasive material SiC Al 2 O 3 ,WA Al 2 O 3 ,PA B. Feed (mm/min) 50 100 200 C. Depth of grinding (m) 20 50 80 D. Revolution (rpm) 12 000 18 000 24 000 fied by the digits 1, 2, and 3. Three types of abrasive materials, namely silicon carbide (SiC), white aluminum oxide (Al 2 O 3 , WA), and pink aluminum oxide (Al 2 O 3 , PA), were selected and studied. Three numerical values of each factor were determined based on the pre-study results. The L 18 orthogonal array was se- lected to conduct the matrix experiment for four 3-level factors of the spherical grinding process. 3.2 Definition of the data analysis Engineering design problems can be divided into smaller-the- better types, nominal-the-best types, larger-the-better types, signed-target types, among others 8. The signal-to-noise (S/N) ratio is used as the objective function for optimizing a product or process design. The surface roughness value of the ground sur- face via an adequate combination of grinding parameters should be smaller than that of the original surface. Consequently, the spherical grinding process is an example of a smaller-the-better type problem. The S/N ratio, , is defined by the following equation 8: =10 log 10 (mean square quality characteristic) =10 log 10 bracketleftBigg 1 n n summationdisplay i=1 y 2 i bracketrightBigg . (1) where: y i : observations of the quality characteristic under different noise conditions n: number of experiment After the S/N ratio from the experimental data of each L 18 orthogonal array is calculated, the main effect of each factor was determined by using an analysis of variance (ANOVA) tech- nique and an F-ratio test 8. The optimization strategy of the 64 smaller-the better problem is to maximize ,asdefinedbyEq.1. Levels that maximize will be selected for the factors that have a significant effect on . The optimal conditions for spherical grinding can then be determined. 4 Experimental work and results The material used in this study was PDS5 tool steel (equiva- lent to AISI P20) 9, which is commonly used for the molds of large plastic injection products in the field of automobile com- ponents and domestic appliances. The hardness of this material is about HRC33 (HS46) 9. One specific advantage of this ma- terial is that after machining, the mold can be directly used for further finishing processes without heat treatment due to its special pre-treatment. The specimens were designed and manu- factured so that they could be mounted on a dynamometer to measure the reaction force. The PDS5 specimen was roughly ma- chined and then mounted on the dynamometer to carry out the fine milling on a three-axis machining center made by Yang- Iron Company (type MV-3A), equipped with a FUNUC Com- pany NC-controller (type 0M) 10. The pre-machined surface roughness was measured, using Hommelwerke T4000 equip- ment, to be about 1.6 m. Figure 6 shows the experimental set-up of the spherical grinding process. A MP10 touch-trigger probe made by the Renishaw Company was also integrated with the machining center tool magazine to measure and determine the coordinated origin of the specimen to be ground. The NC codes needed for the ball-burnishing path were generated by PowerMILL CAM software. These codes can be transmitted to the CNC controller of the machining center via RS232 serial interface. Table 2 summarizes the measured ground surface roughness value R a and the calculated S/N ratio of each L 18 orthogonal ar- ray using Eq. 1, after having executed the 18 matrix experiments. The average S/N ratio for each level of the four factors can be obtained, as listed in Table 3, by taking the numerical values pro- vided in Table 2. The average S/N ratio for each level of the four factors is shown graphically in Fig. 7. Fig. 6. Experimental set-up to determine the op- timal spherical grinding parameters Table 2. Ground surface roughness of PDS5 specimen Exp. Inner array Measured surface Response no. (control factors) roughness value (R a ) ABCD y 1 y 2 y 3 S/N ratio Mean (m) (m) (m) (dB) y (m) 1 1 1 1 1 0.35 0.35 0.35 9.119 0.350 2 1 2 2 2 0.37 0.36 0.38 8.634 0.370 3 1 3 3 3 0.41 0.44 0.40 7.597 0.417 4 2 1 2 3 0.63 0.65 0.64 3.876 0.640 5 2 2 3 1 0.73 0.77 0.78 2.380 0.760 6 2 3 1 2 0.45 0.42 0.39 7.520 0.420 7 3 1 3 2 0.34 0.31 0.32 9.801 0.323 8 3 2 1 3 0.27 0.25 0.28 11.471 0.267 9 3 3 2 1 0.32 0.32 0.32 9.897 0.320 10 1 1 2 2 0.35 0.39 0.40 8.390 0.380 11 1 2 3 3 0.41 0.50 0.43 6.968 0.447 12 1 3 1 1 0.40 0.39 0.42 7.883 0.403 13 2 1 1 3 0.33 0.34 0.31 9.712 0.327 14 2 2 2 1 0.48 0.50 0.47 6.312 0.483 15 2 3 3 2 0.57 0.61 0.53 4.868 0.570 16 3 1 3 1 0.59 0.55 0.54 5.030 0.560 17 3 2 1 2 0.36 0.36 0.35 8.954 0.357 18 3 3 2 3 0.57 0.53 0.53 5.293 0.543 Table 3. Average S/N ratios by factor levels (dB) Factor A B C D Level 1 8.099 7.655 9.110 6.770 Level 2 5.778 7.453 7.067 8.028 Level 3 8.408 7.176 6.107 7.486 Effect 2.630 0.479 3.003 1.258 Rank2413 Mean 7.428 The goal in the spherical grinding process is to minimize the surface roughness value of the ground specimen by determin- ing the optimal level of each factor. Since log is a monotone decreasing function, we should maximize the S/N ratio. Conse- quently, we can determine the optimal level for each factor as being the level that has the highest value of . Therefore, based 65 Fig. 7. Plots of control factor effects on the matrix experiment, the optimal abrasive material was pink aluminum oxide; the optimal feed was 50 mm/min; the optimal depth of grinding was 20 m; and the optimal revolution was 18 000 rpm, as shown in Table 4. The main effect of each factor was further determined by using an analysis of variance (ANOVA) technique and an F ratio test in order to determine their significance (see Table 5). The F 0.10,2,13 is 2.76 for a level of significance equal to 0.10 (or 90% confidence level); the factors degree of freedom is 2 and the degree of freedom for the pooled error is 13, according to F-distribution table 11. An F ratio value greater than 2.76 can be concluded as having a significant effect on surface roughness and is identified by an asterisk. As a result, the feed and the depth of grinding have a significant effect on surface roughness. Five verification experiments were carried out to observe the repeatability of using the optimal combination of grinding pa- rameters, as shown in Table 6. The obtainable surface roughness value R a of such specimen was measured to be about 0.35 m. Surface roughness was improved by about 78% in using the op- Table 4. Optimal combination of spherical grinding parameters Factor Level Abrasive Al 2 O 3 ,PA Feed 50 mm/min Depth of grinding 20 m Revolution 18 000 rpm Table 5. ANOVA table for S/N ratio of surface roughness Factor Degrees Sum Mean F ratio of freedom of squares squares A 2 24.791 12.396 3.620 B 2 0.692 0.346 C 2 28.218 14.109 4.121 D 2 4.776 2.388 Error 9 39.043 Total 17 97.520 Pooled to error 13 44.511 3.424 F ratio value 2.76 has significant effect on surface roughness Table 6. Surface roughness value of the tested specimen after verification experiment Exp. no. Measured value R a (m) Mean y (m) S/N ratio y 1 y 2 y 3 1 0.30 0.31 0.33 0.313 10.073 2 0.36 0.37 0.36 0.363 8.802 3 0.36 0.37 0.37 0.367 8.714 4 0.35 0.37 0.34 0.353 9.031 5 0.33 0.36 0.35 0.347 9.163 Mean 0.349 9.163 timal combination of spherical grinding parameters. The ground surface was further burnished using the optimal ball burnishing parameters. A surface roughness value of R a = 0.06 m was ob- tainable after ball burnishing. Improvement of the burnished sur- face roughness observed with a 30 optical microscope is shown in Fig. 8. The improvement of pre-machined surfaces roughness was about 95% after the burnishing process. The optimal parameters for surface spherical grinding ob- tained from the Taguchis matrix experiments were applied to the surface finish of the freeform surface mold insert to evalu- ate the surface roughness improvement. A perfume bottle was selected as the tested carrier. The CNC machining of the mold in- sert for the tested object was simulated with PowerMILL CAM software. After fine milling, the mold insert was further ground with the optimal spherical grinding parameters obtained from the Taguchis matrix experiment. Shortly afterwards, the ground surface was burnished with the optimal ball burnishing parame- ters to further improve the surface roughness of the tested object (see Fig. 9). The surface roughness of the mold insert was meas- ured with Hommelwerke T4000 equipment. The average surface roughness value R a on a fine-milled surface of the mold insert was 2.15 m on average; that on the ground surface was 0.45 m Fig. 8. Comparison between the pre-machined surface, ground surface and the burnished surface of the tested specimen observed with a toolmaker microscope (30) 66 Fig. 9. Fine-milled, ground and burnished mold insert of a perfume bottle on average; and that on burnished surface was 0.07 monaver- age. The surface roughness improvement of the tested object on ground surface was about (2.150.45)/2.15 = 79.1%, and that on the burnished surface was about (2.150.07)/2.15 = 96.7%. 5 Conclusion In this work, the optimal parameters of automated spheri- cal grinding and ball-burnishing surface finishing processes in a freeform surface plastic injection mold were developed suc- cessfully on a machining center. The mounted spherical grinding tool (and its alignment components) was designed and manu- factured. The optimal spherical grinding parameters for surface grinding were determined by conducting a Taguchi L 18 matrix experiments. The optimal spherical grinding parameters for the plastic injection mold steel PDS5 were the combination of the abrasive material of pink aluminum oxide (Al 2 O 3 ,PA),afeed of 50 mm/min, a depth of grinding 20 m, and a revolution of 18 000 rpm. The surface roughness R a of the specimen can be improved from about 1.6 mto0.35 m by using the optimal spherical grinding conditions for surface grinding. By applying the optimal surface grinding and burnishing parameters to the surface finish of the freeform surface mold insert, the surface roughness improvements were measured to be ground surface was about 79.1% in terms of ground surfaces, and about 96.7% in terms of burnished surfaces. Acknowledgement The authors are grateful to the National Science Coun- cil of the Republic of China for supporting this research with grant NSC 89-2212-E-011-059. References 1. Chen CCA, Yan WS (2000) Geometric model of mounted grinding tools for automated surface finishing processes. In: Proceedings of the 6th International Conference on Automation Technology, Taipei, May 911, pp 4347 2. Chen CCA, Duffie NA, Liu WC (1997) A finishing model of spherical grinding tools for automated surface finishing systems. Int J Manuf Sci Prod 1(1):1726 3. Loh NH, Tam SC (1988) Effects of ball burnishing parameters on surface finisha literature survey and discussion. Precis Eng 10(4):215 220 4. Loh NH, Tam SC, Miyazawa S (1991) Investigations on the sur- face roughness produced by ball burnishing. Int J Mach Tools Manuf 31(1):7581 5. Yu X, Wang L (1999) Effect of various parameters on the surface roughness of an aluminum alloy burnished with a spherical surfaced polycrystalline diamond tool. Int J Mach Tools Manuf 39:459469 6. Klocke F, Liermann J (1996) Roller burnishing of hard turned surfaces. Int J Mach Tools Manuf 38(5):419423 7. Shiou FJ, Chen CH (2003) Determination of optimal ball-burnishing parameters for plastic injection molding steel. Int J Adv Manuf Technol 3:177185 8. Phadke MS (1989) Quality engineering using robust design. Prentice- Hall, Englewood Cliffs, New Jersey 9. Ta-Tung Company (1985) Technical handbook for the selection of plas- tic injection mold steel. Taiwan 10. Yang Iron Works (1996) Technical handbook of MV-3A vertical ma- chining center. Taiwan 11. Montgomery DC (1991) Design and analysis of experiments. Wiley, New York