塑料瓶蓋注塑模具設計【一模十二腔】【側抽芯】【說明書+CAD】

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河南機電高等?？茖W校 學生畢業(yè)設計（論文）中期檢查表 學生姓名 學 號 指導教師 選題情況 課題名稱 塑料瓶蓋注塑模具設計與制造 難易程度 偏難 適中 偏易 工作量 較大 合理 較小 符合規(guī)范化的要求 任務書 有 無 開題報告 有 無 外文翻譯質量 優(yōu) 良 中 差 學習態(tài)度、出勤情況 好 一般 差 工作進度 快 按計劃進行 慢 中期工作匯報及解答問題情況 優(yōu) 良 中 差 中期成績評定： 所在專業(yè)意見： 負責人： 年 月 日 河南機電高等?？茖W校 畢業(yè)設計(論文)開題報告 學生姓名： 學 號： 專 業(yè)： 模具設計與制造 設計(論文)題目： 塑料瓶蓋注塑模具設計與制造 指導教師： 2006年 4 月 8 日  畢 業(yè) 設 計（論 文）開 題 報 告 1．結合畢業(yè)設計（論文）課題情況，根據(jù)所查閱的文獻資料，撰寫1500字左右（本科生200字左右）的文獻綜述(包括目前該課題在國內外的研究狀況、發(fā)展趨勢以及對本人研究課題的啟發(fā))： 文 獻 綜 述 收集有關設計課題研究方面的資料、文獻作為設計前的準備工作，在設計工作開始時，需要研究國內外此類課題的發(fā)展狀況，對自己的課題有一定的背景認識，才會對設計有更好的把握，所以收集、查閱有關文獻資料有一定的必要性。 我在設計前的準備工作主要包括了解國內外塑料模具的發(fā)展趨勢和發(fā)展現(xiàn)狀，并根據(jù)自己的工作經歷發(fā)表自己的一些看法。 隨著科學技術的發(fā)展，我國的工業(yè)化程度也有了很大地提高，特別是在模具行業(yè)有了很大地發(fā)展。如：在模具設計與制造上，不但自己可以制造一些大型，精密，復雜，高效，長壽命的模具，并且能夠出口到國外，打開國外的市場。但是，目前我國的塑料技術與工業(yè)發(fā)達國家相比還相當落后，主要原因是我國在塑料基礎理論及成型工藝，模具標準化，模具設計，模具制造工藝及設備等方面與工業(yè)發(fā)達國家尚有相當大的差距，導致我國的模具在壽命，效率，加工精度，生產周期等方面與工業(yè)發(fā)達國家的模具相比差距相當大。因此這就需要我們努力去研究，推動我國模具業(yè)的發(fā)展，我國模具工業(yè)發(fā)展的制約因素除了以上所述，還有更容易被大家忽視的模具企業(yè)管理上和發(fā)展策劃上的滯后觀念的影響，所以我認為我們缺的不僅僅是技術層次上的東西，還應該以同樣的精力來關注模具企業(yè)的管理模式的探索和應用，這方面更應該優(yōu)先考慮是因為它往往很容易被人們忽視。 隨著工業(yè)產品質量的不斷提高，塑料產品的生產正呈現(xiàn)出多品種、少批量，復雜、大型、精密，更新?lián)Q代速度快等變化特點，塑料模具也正向高效、精密、長壽命、大型化方向發(fā)展。為適應市場的變化，隨著計算機技術和制造技術的迅速發(fā)展，塑料模具設計與制造技術正在由手工設計、依靠工人的經驗和常規(guī)的機械加工技術向計算機輔助設計（CAD）、數(shù)控加工中心進行切削加工、數(shù)控線切割、數(shù)控電火花等為核心的計算機輔助設計與制造（CAD/CAM）技術方面轉變。模具的發(fā)展現(xiàn)狀及發(fā)展趨勢如下詳述： CAD/CAM是一項高科技、高效益的系統(tǒng)工種，是模具設計與制造行業(yè)的有效輔助工具；通過它能夠對產品、模具結構、成型工藝、數(shù)控加工及成本等進行設計和優(yōu)化?，F(xiàn)在已經廣泛地應用與模具的設計與制造加工的過程中，并還在不斷地發(fā)展和創(chuàng)新；模具的標準化對縮短模具制造周期、提高質量、降低成本起到很大的作用。我國的模具標準化程度達到30%以下，而國外先進國家達到70%—80%左右。這樣，不僅有利于國內的模具制造的發(fā)展，也有利于模具的國際化發(fā)展；國外的制造水平能夠是制造公差達到0.003—0.005 mm，表面的粗糙度達到Ra 0.0002 mm以下；我國的制造水平可以是制造公差達到0.01—0.02 mm,模具表面的粗糙度達到Ra0.00160.0008 mm。由此可見，如今模具技術的發(fā)展水平還是很高的，但也可以看出我國在這方面的技術與國外先進國家還有很大的差距。 國外的塑料模具的使用壽命，模具的使用壽命的加長就意味著模具的制造成本降低，從而提高了生產效益；模具的加工制造設備：國外已經廣泛地使用了數(shù)控加工中心，線切割，電火花，化學腐蝕等先進的設備，大大地提高了模具的制造周期； 模具企業(yè)對管理的重視程度在加大，利用軟體包括管理軟件和工藝流程開發(fā)軟件來提高企業(yè)本身的競爭力，而不僅僅是靜態(tài)得考慮模具的開發(fā)和制造成本，對此企業(yè)向更科學更系統(tǒng)的現(xiàn)代管理模式發(fā)展。 收集資料文獻使我對模具業(yè)的發(fā)展現(xiàn)狀及發(fā)展趨勢、模具的設計與制造技術等有了更多，更全面地了解。而且收集到了許多有關本課題的研究，與本課題相關、相似的東西，查找各種有關模具設計與制造方面的經驗公式，和經驗數(shù)據(jù)；通過查閱資料和文獻能夠將課堂上所學習到的理論知識，與實際生產當中的實例相結合去更好地成設計任務；并且使我在課程設計上有了更多的設計思路，也有了更多的考慮空間，同時也使我在設計的過程中能夠從多方面地去考慮問題——模具設計的合理性及對設計好的模具在工作過程中可能會出現(xiàn)的問題及解決辦法。 在這段時間，自己一邊做設計，一邊工作和學習，工作的認識就是資料可以給自己提供許多處理問題的思路，并從比較的角度去考慮加工成本和經濟性，所以收集資料對自己以后也是有必要的。  畢 業(yè) 設 計（論 文）開 題 報 告 ２．本課題的研究思路（包括要研究或解決的問題和擬采用的研究方法、手段（途徑）及進度安排等）： 1. 拿到工件的結構簡圖，對工件進行結構形狀、尺寸精度、加工工藝性等方面作出詳細地分析，并查閱相關資料看是否符合常規(guī)零件結構設計，預計用時兩天； 2. 收集和查閱各種文獻資料和與同學老師的交流，對目前國內外的模具（塑料模具）的發(fā)展狀況了解，熟悉工廠的加工設備，做設計的預備工作，向公司設計人員表述自己的初步構思，提取來自經驗者的意見。預計用時間三天； 3. 經過對工件的結構工藝性分析和同設計人員的探討，擬訂可行的模具設計方案，并經過分析，研究、比較，選擇一種最為合理，估計用時間一天； 4. 進行主要的設計設計計算，較多利用經驗數(shù)據(jù)，查閱文獻，預計需用時間四天； 5. 根據(jù)工件的結構，材料，生產批量來進行模具的總體設計，包括模具的類型，抽芯方式 ，卸件方式，導向方式等方面的設計；在設計中，應該綜合考慮模具的安裝，維修，生產效率等，預計用時間兩天； 6. 對模具的主要零部件進行設計，主要有凸模、凹模、模架和導柱導套等零件，根據(jù)工作需要來設計尺寸，包括各零件的圖紙，預計需用時間五天； 7. 完成模具的總裝圖和主要零件圖，需要用時間兩天； 8. 模具主要零部件的加工工藝過程（型腔，型芯，）分析與設計，預計用時間兩天； 9. 整理自己設計資料，完成畢業(yè)設計說明書，根據(jù)格式要求做進一不整理，完成設計內容； 10. 提交老師指導，針對問題進行修改，最后打印和裝訂，準備答辯。 參考文獻 【1】瞿金平 塑料工業(yè) 北京 化學工業(yè)出版社 1999. 【2】馮炳堯 模具設計與制造簡明手冊 上海 上?？茖W技術出版社 1985. 【3】張克惠 注塑模設計 西安 西北工業(yè)大學出版社 2001. 【4】肖祥芷 模具設計大典（三） 南昌 江西科學技術出版社 2002. 【5】楊占堯 塑料注塑模結構與設計 北京 清華大學出版社 2004. 【6】翟德梅 模具制造技術 新鄉(xiāng) 河南機電高等?？茖W校 2001. 【7】閻亞林 塑料模具圖冊 北京 高等教育出版社 2002. 【8】黃虹 塑料成型加工與模具 北京 化學工業(yè)出版社 2003. 【9】薛嚴成公差配合與測量技術　　 北京 機械工業(yè)出版社　　 1992. 【10】 Thomas peters Tolerance fitting and technology of measuring Publishing house of the mechanical industry 1999. 【11】王永平 注塑模具設計經驗點評 北京 機械工業(yè)出版設 2005  畢 業(yè) 設 計（論 文）開 題 報 告 指導教師意見： 1．對“文獻綜述”的評語： 2．對本課題的研究思路、深度、廣度及工作量的意見和對設計（論文）結果的預測： 指導教師： 年 月 日 所在專業(yè)審查意見： 負責人： 年 月 日 河南機電高等專科學校畢業(yè)設計說明書 插圖清單 【1】 圖 1 制件圖 ……………………………………………………… 6 【2】 圖2 分型面選擇 …………………………………………………10 【3】 圖3 型腔的排列方式 ……………………………………………10 【4】 圖4 斜導柱 ………………………………………………………12 【5】 圖 5 滑塊抽芯圖 ………………………………………………… 12 【6】 圖 6 型芯結構圖… ……………………………………………… 15 【7】 圖 7 冷卻水道布置圖 …………………………………………… 17 附表清單 【1】 表一：凹模工作尺寸表…………………………………………………… 14 【2】 表二: 凸模工作尺寸表 ………………………………………………… 14 【3】 表三：型芯工作尺寸表 ………………………………………………… 14 【4】 表四: 冷卻水道選取表…………………………………………… …… 17 【5】 表五: 制件常見缺陷及解決辦法…………………………………………20 【6】 表六: 凹模型腔板的加工工藝尺寸………………………………………21 【7】 表八: 型芯固定板的加工工藝尺寸………………………………………21 小結 通過這次課程設計使我學到了許多知識，對一些原本模糊的理論也有了清楚的認識。特別是原來所學的一些專業(yè)基礎課：如機械制圖、模具材料、公差配合與技術測量、塑料模具設計與制造等有了更深刻的理解，使制造的模具既能滿足使用要求有不浪費材料，保證了工件的經濟性，設計的合理性。通過塑料模手冊、模具制造簡明手冊、模具標準應用手冊等了解到許多原本不的知識。 由于能力有限，設計中難免有疏漏之處，懇請老師給予指正。我在此衷心謝謝原老師的大力幫助與指導。 塑料瓶蓋注塑模具設計 摘要 本文首先簡要的概述了塑料模在社會領域中的作用及其以后的發(fā)展方向，點明模具設計的重要意義。然后依據(jù)工件圖進行工藝性分析，進而確定了設計方案，計算出模具工作部分的尺寸，設計出工作零部件；然后依據(jù)設計要求選擇出各個標準零部件，然后設計出模具的總裝配圖。在設計中，最重要的就是設計方案的確定、坯料的計算和選取以及工作零部件的設計，這是設計的關鍵，這些設計的正確與否直接關系到成本的高低和設計模具能否正常工作. 關鍵詞：模具設計與制造、CAD軟件、工藝性分析。 Head modelling and mold design of the bottle top Abstract This text the brief plastic role in social field of mould of summary and developing direction afterwards at first, point out in the important meaning of mold design. Then carry on the craft to analyse according to the work piece picture , and then has confirmed the design plan , calculate out mould work some size , design the job spare part; Then choose each standard spare part according to the designing requirement , then design the total installation diagram of the mould . In the design, the important one is sureness of the design plan , calculation and choosing and working the design of the spare part of the blank the most, this is the key to designing, whether these ones that are designed involve directly or not correctly whether the level of the cost and design mould could work normally; At the end that is designed , have summarized one's own gains and experience , and express thanks for my counselor. Keyword: Mold design and making , CAD software , craft analysis. 機械加工工藝過程卡片 產品型號 零（部）件圖號 1 產品名稱 凸模固定板 零（部）件名稱 共（2）頁第（1）頁 材料牌號 45 毛坯 種類 塊料 毛坯外型尺寸 504×354×48 每個毛坯可制件數(shù) 1 每臺 件數(shù) 1 備注 工序號 工序名稱 工 序 內 容 車間 工段 設備 工 藝 裝 備 工時 準終 單件 10 下料 鋸床下料 金工 G7116 20 時效 對鍛件進行時效處理 30 銑削 粗銑504×354的塊料及端面 銑床 臥式銑床 40 銑削 精銑504×354的塊料 銑床 臥式銑床 50 磨削 粗磨504×354的塊料 磨床 M1040 平面磨床 60 退火 去加工應力 熱處理 電爐 70 磨削 精磨臺階軸的外表面 磨床 M1040 專用磨夾具 80 淬火回火 對凸模固定板的要加工的部分進行熱處理 熱處理 90 研磨 對凸模固定板進行進一步的修整 金工 100 檢驗 標記 記數(shù) 更改文 件號 簽字 日期 標記 處數(shù) 更該文件號 審核日期 標準化日期 會簽 日期 機械加工工藝過程卡片1 機械加工工藝過程卡片2 機械加工工藝過程卡片 產品型號 零（部）件圖號 2 產品名稱 型腔板 零（部）件名稱 共（2）頁第（2）頁 材料牌號 45 毛坯 種類 鍛件 毛坯外型尺寸 504mm×354mm×53mm 每個毛坯可制件數(shù) 1 每臺 件數(shù) 1 備注 工序號 工序名稱 工 序 內 容 車間 工段 設備 工 藝 裝 備 工時 準終 單件 10 下料 鋸床下料 金工 G7116 20 鍛造 鍛成六方 鍛 30 時效 對鍛件進行時效退火 熱 40 粗銑 粗銑六面 金工 X 50A 專用銑夾具 50 磨削 粗磨六面成直角 金工 M 1040 專用磨夾具 60 劃線 確定孔位，為下一步加工打好基準沖眼兒 鉗工 70 鉆孔 根據(jù)沖眼兒鉆孔 金工 ZQ 4015 專用鉆夾具 80 精磨 精磨上下兩面，表面粗糟度值為Ra0.8 金工 M 1040 專用磨夾具 90 成型 由加工中心得來的銅電極來加工型腔 CKX-2A 專用電火花夾具 100 研磨 對型腔模板進行進一步的修整 金工 110 淬火回火 對型腔模板進行熱處理 熱處理 120 檢驗 設計日期 審核日期 標準化日期 會簽 日期 河南機電高等專科學校畢業(yè)設計說明書 目 錄 緒論 ………………………………………………………………1 1.本課題的意義、目的及應達到的要求……………………1 2 本課題的國內外現(xiàn)狀 ………………………………………1 3國外塑料模具的發(fā)展現(xiàn)狀……………………………………4 4．本設計所要解決的問題……………………………………5 1 工藝性分析 ……………………………………………………6 1.1：塑料的原材料分析………………………………………6 1.2：塑件的結構和尺寸精度等級及表面質量分析…………6 1.3：計算塑料制件的體積和質量……………………………7 1.4：PP塑料注射成型的工藝參數(shù)……………………………7 1.5：塑料成型設備的選取………………………………………8 2 注塑模具結構的設計……………………………………………9 2.1 模腔數(shù)量的確定………………………………………… 9 2.2 分型面的選擇以及型腔的排列方式的確定……………9 2.3 澆注系統(tǒng)的設計……………………………………………11 2.4 模具側向分型機構…………………………………………12 2.5 排氣結構設計………………………………………………12 3 模具工作零件的設計……………………………………………13 3.1 凹模的設計…………………………………………………13 3.2瓶蓋注塑模具的工作尺寸……………………………13 3.3 型芯結構的確定……………………………………………15 4 模具加熱和冷卻系統(tǒng)的設計………………………………………16 4.1 求塑件在硬化時每小時釋放的熱量…………………………16 4.2 求冷卻水的體積流量…………………………………………16 4.3 確定模具的冷卻系統(tǒng)………………………………………16 5 模具閉和高度的確定………………………………………………17 6 注塑機有關參數(shù)的校核……………………………………………18 7 模具的裝配…………………………………………………………19 8 試模過程中出現(xiàn)的問題及解決辦法……………………………20 9 主要工作零件加工工藝規(guī)程 ……………………………………21 結論……………………………………………………………………22 致謝……………………………………………………………………23 參考文獻………………………………………………………………24 INEEL/CON-2000-00104 PREPRINT Spray-Formed Tooling for Injection Molding and Die Casting Applications K. M. McHugh B. R. Wickham June 26, 2000 – June 28, 2000 International Conference on Spray Deposition and Melt Atomization This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as a account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. The views expressed in this paper are not necessarily those of the U.S. Government or the sponsoring agency. BECHTEL BWXT IDAHO, LLC 1 Spray-Formed Tooling For Injection Molding and Die Casting Applications Kevin M. McHugh and Bruce R. Wickham Idaho National Engineering and Environmental Laboratory P.O. Box 1625 Idaho Falls, ID 83415-2050 e-mail: kmm4@inel.gov Abstract Rapid Solidification Process (RSP) Tooling is a spray forming technology tailored for producing molds and dies. The approach combines rapid solidification processing and net-shape materials processing in a single step. The ability of the sprayed deposit to capture features of the tool pattern eliminates costly machining operations in conventional mold making and reduces turnaround time. Moreover, rapid solidification suppresses carbide precipitation and growth, allowing many ferritic tool steels to be artificially aged, an alternative to conventional heat treatment that offers unique benefits. Material properties and microstructure transformation during heat treatment of spray-formed H13 tool steel are described. Introduction Molds, dies, and related tooling are used to shape many of the plastic and metal components we use every day at home or at work. The process involves machining the negative of a desired part shape (core and cavity) from a forged tool steel or a rough metal casting, adding cooling channels, vents, and other mechanical features, followed by grinding. Many molds and dies undergo heat treatment (austenitization/quench/temper) to improve the properties of the steel, followed by final grinding and polishing to achieve the desired finish [1]. Conventional fabrication of molds and dies is very expensive and time consuming because: ? Each is custom made, reflecting the shape and texture of the desired part. ? The materials used to make tooling are difficult to machine and work with. Tool steels are the workhorse of industry for long production runs. Machining tool steels is capital equipment intensive because specialized equipment is often needed for individual machining steps. ? Tooling must be machined accurately. Oftentimes many individual components must fit together correctly for the final product to function properly. 2 Costs for plastic injection molds vary with size and complexity, ranging from about $10,000 to over $300,000 (U.S.), and have lead times of 3 to 6 months. Tool checking and part qualification may require an additional 3 months. Large die-casting dies for transmissions and sheet metal stamping dies for making automobile body panels may cost more than $1million (U.S.). Lead times are usually greater than 40 weeks. A large automobile company invests about $1 billion (U.S.) in new tooling each year to manufacture the components that go into their new line of cars and trucks. Spray forming offers great potential for reducing the cost and lead time for tooling by eliminating many of the machining, grinding, and polishing unit operations. In addition, spray forming provides a powerful means to control segregation of alloying elements during solidification and carbide formation, and the ability to create beneficial metastable phases in many popular ferritic tool steels. As a result, relatively low temperature precipitation hardening heat treatment can be used to tailor properties such as hardness, toughness, thermal fatigue resistance, and strength. This paper describes the application of spray forming technology for producing H13 tooling for injection molding and die casting applications, and the benefits of low temperature heat treatment. RSP Tooling Rapid Solidification Process (RSP) Tooling, is a spray forming technology tailored for producing molds and dies [2-4]. The approach combines rapid solidification processing and net- shape materials processing in a single step. The general concept involves converting a mold design described by a CAD file to a tooling master using a suitable rapid prototyping (RP) technology such as stereolithography. A pattern transfer is made to a castable ceramic, typically alumina or fused silica (Figure 1). This is followed by spray forming a thick deposit of tool steel (or other alloy) on the pattern to capture the desired shape, surface texture and detail. The resultant metal block is cooled to room temperature and separated from the pattern. Typically, the deposit’s exterior walls are machined square, allowing it to be used as an insert in a holding block such as a MUD frame [5]. The overall turnaround time for tooling is about three days, stating with a master. Molds and dies produced in this way have been used for prototype and production runs in plastic injection molding and die casting. Figure 1. RSP Tooling? processing steps. 3 An important benefit of RSP Tooling is that it allows molds and dies to be made early in the design cycle for a component. True prototype parts can be manufactured to assess form, fit, and function using the same process planned for production. If the part is qualified, the tooling can be run in production as conventional tooling would. Use of a digital database and RP technology allows design modifications to be easily made. Experimental Procedure An alumina-base ceramic (Cotronics 780 [6]) was slurry cast using a silicone rubber master die, or freeze cast using a stereolithography master. After setting up, ceramic patterns were demolded, fired in a kiln, and cooled to room temperature. H13 tool steel was induction melted under a nitrogen atmosphere, superheated about 100°C, and pressure-fed into a bench-scale converging/diverging spray nozzle, designed and constructed in-house. An inert gas atmosphere within the spray apparatus minimized in-flight oxidation of the atomized droplets as they deposited onto the tool pattern at a rate of about 200 kg/h. Gas-to-metal mass flow ratio was approximately 0.5. For tensile property and hardness evaluation, the spray-formed material was sectioned using a wire EDM and surface ground to remove a 0.05 mm thick heat-affected zone. Samples were heat treated in a furnace that was purged with nitrogen. Each sample was coated with BN and placed in a sealed metal foil packet as a precautionary measure to prevent decarburization. Artificially aged samples were soaked for 1 hour at temperatures ranging from 400 to 700°C, and air cooled. Conventionally heat treated H13 was austenitized at 1010°C for 30 min., air quenched, and double tempered (2 hr plus 2 hr) at 538°C. Microhardness was measured at room temperature using a Shimadzu Type M Vickers Hardness Tester by averaging ten microindentation readings. Microstructure of the etched (3% nital) tool steel was evaluated optically using an Olympus Model PME-3 metallograph and an Amray Model 1830 scanning electron microscope. Phase composition was analyzed via energy- dispersive spectroscopy (EDS). The size distribution of overspray powder was analyzed using a Microtrac Full Range Particle Analyzer after powder samples were sieved at 200 μm to remove coarse flakes. Sample density was evaluated by water displacement using Archimedes’ principle and a Mettler balance (Model AE100). A quasi 1-D computer code developed at INEEL was used to evaluate multiphase flow behavior inside the nozzle and free jet regions. The code's basic numerical technique solves the steady- state gas flow field through an adaptive grid, conservative variables approach and treats the droplet phase in a Lagrangian manner with full aerodynamic and energetic coupling between the droplets and transport gas. The liquid metal injection system is coupled to the throat gas dynamics, and effects of heat transfer and wall friction are included. The code also includes a nonequilibrium solidification model that permits droplet undercooling and recalescence. The code was used to map out the temperature and velocity profile of the gas and atomized droplets within the nozzle and free jet regions. 4 Results and Discussion Spray forming is a robust rapid tooling technology that allows tool steel molds and dies to be produced in a straightforward manner. Examples of die inserts are given in Figure 2. Each was spray formed using a ceramic pattern generated from a RP master. Figure 2. Spray-formed mold inserts. (a) Ceramic pattern and H13 tool steel insert. (b) P20 tool steel insert. Particle and Gas Behavior Particle mass frequency and cumulative mass distribution plots for H13 tool steel sprays are given in Figure 3. The mass median diameter was determined to be 56 μm by interpolation of size corresponding to 50% cumulative mass. The area mean diameter and volume mean diameter were calculated to be 53 μm and 139 μm, respectively. Geometric standard deviation, σ d =(d 84 /d 16 ) ? , is 1.8, where d 84 and d 16 are particle diameters corresponding to 84% and 16% cumulative mass in Figure 3. 5 Figure 3. Cumulative mass and mass frequency plots of particles in H13 tool step sprays. Figure 4 gives computational results for the multiphase velocity flow field (Figure 4a), and H13 tool steel solid fraction (Figure 4b), inside the nozzle and free jet regions. Gas velocity increases until reaching the location of the shock front, at which point it precipitously decreases, eventually decaying exponentially outside the nozzle. Small droplets are easily perturbed by the velocity field, accelerating inside the nozzle and decelerating outside. After reaching their terminal velocity, larger droplets (～150 μm) are less perturbed by the flow field due to their greater momentum. It is well known that high particle cooling rates in the spray jet (10 3 -10 6 K/s) and bulk deposit (1- 100 K/min) are present during spray forming [7]. Most of the particles in the spray have undergone recalescence, resulting in a solid fraction of about 0.75. Calculated solid fraction profiles of small (～30 μm) and large (～150 μm) droplets with distance from the nozzle inlet, are shown in Figure 4b. Spray-Formed Deposits This high heat extraction rate reduces erosion effects at the surface of the tool pattern. This allows relatively soft, castable ceramic pattern materials to be used that would not be satisfactory candidates for conventional metal casting processes. With suitable processing conditions, fine 6 Figure 4. Calculated particle and gas behavior in nozzle and free jet regions. (a) Velocity profile. (b) Solid fraction. 7 surface detail can be successfully transferred from the pattern to spray-formed mold. Surface roughness at the molding surface is pattern dependent. Slurry-cast commercial ceramics yield a surface roughness of about 1 μm Ra, suitable for many molding applications. Deposition of tool steel onto glass plates has yielded a specular surface finish of about 0.076 μm Ra. At the current state of development, dimensional repeatability of spray-formed molds, starting with a common master, is about ±0.2%. Chemistry The chemistry of H13 tool steel is designed to allow the material to withstand the temperature, pressure, abrasion, and thermal cycling associated with demanding applications such as die casting. It is the most popular die casting alloy worldwide and second most popular tool steel for plastic injection molding. The steel has low carbon content (0.4 wt.%) to promote toughness, medium chromium content (5 wt%) to provide good resistance to high temperature softening, 1 wt% Si to improve high temperature oxidation resistance, and small molybdenum and vanadium additions (about 1%) that form stable carbides to increase resistance to erosive wear [8]. Composition analysis was performed on H13 tool steel before and after spray forming. Results, summarized in Table 1, indicate no significant variation in alloy additions. Table 1. Composition of H13 tool steel Element C Mn Cr Mo V Si Fe Stock H13 0.41 0.39 5.15 1.41 0.9 1.06 Bal. Spray Formed H13 0.41 0.38 5.10 1.42 0.9 1.08 Bal. Microstructure The size, shape, type, and distribution of carbides found in H13 tool steel is dictated by the processing method and heat treatment. Normally the commercial steel is machined in the mill annealed condition and heat treated (austenitized/quenched/tempered) prior to use. It is typically austenitized at about 1010°C, quenched in air or oil, and carefully tempered two or three times at 540 to 650°C to obtain the required combination of hardness, thermal fatigue resistance, and toughness. Commercial, forged, ferritic tool steels cannot be precipitation hardened because after electroslag remelting at the steel mill, ingots are cast that cool slowly and form coarse carbides. In contrast, rapid solidification of H13 tool steel causes alloying additions to remain largely in solution and to be more uniformly distributed in the matrix [9-11]. Properties can be tailored by artificial aging or conventional heat treatment. A benefit of artificial aging is that it bypasses the specific volume changes that occur during conventional heat treatment that can lead to tool distortion. These specific volume changes occur as the matrix phase transforms from ferrite to austenite to tempered martensite and must be accounted for in the original mold design. However, they cannot always be reliably predicted. Thin sections in the insert, which may be desirable from a design and production standpoint, are oftentimes not included as the material has a tendency to slump during austenitization or distort 8 during quenching. Tool distortion is not observed during artificial aging of spray-formed tool steels because there is no phase transformation. An optical photomicrograph of spray-formed H13 is shown in Figure 5 together with an SEM image, in backscattered electron (BSE) mode. Energy dispersive spectroscopic (EDS) composition analysis of some features in the photomicrographs is also given. While exact quantitative data is not possible due to sampling volume limitations, results suggest that grain boundaries are particularly rich in V. Intragranular (matrix) regions are homogeneous and rich in Fe. X-ray diffraction analysis indicates that the matrix phase is primarily ferrite (bainite) with very little retained austenite, and that the alloying elements are largely in solution. Discrete intragranular carbides are relatively rare, very small (about 0.1 μm) and predominately vanadium-rich MC carbides. M 2 C carbides are not observed. Element Si V Cr Mn Mo Fe Spot #1 (wt%) 0.61 32.13 6.68 0.17 2.05 58.36 Spot #2 (wt%) 1.59 0.79 5.35 0.28 2.28 89.72 Figure 5. Photomicrographs of as-deposited H13 tool steel. 3% nital etch. (a) Optical photomicrograph. (b) SEM image (BSE mode) near a grain boundary. Table gives EDS composition of numbered features. 9 Figure 6 illustrates the microstructure of spray-formed H13 aged at 500°C for 1 hr. During aging, grain boundaries remain well defined, perhaps coarsening slightly compared to as- deposited H13 (Figure 5). The most prominent change is the appearance of very fine (0.1 μm diameter) vanadium-rich MC carbide precipitates. The precipitates are uniformly distributed throughout the matrix and increase the hardness and wear resistance of the tool steel. Increasing the soak temperature to 700°C results in prominent carbide coarsening, the formation of M 7 C 3 and M 6 C carbides, and a decrease in hardness. The photomicrographs of Figure 7 illustrate the dramatic change in carbide size. BSE imaging clearly differentiates Mo/Cr-rich carbides from V-rich carbides, shown as light and dark areas, respectively, in Figure 7. EDS analysis of these carbides is also given in Figure 7. Element Si V Cr Mn Mo Fe Spot #1 (wt%) 0.06 13.80 7.20 2.64 2.44 73.86 Spot #2 (wt%) 1.52 0.82 5.48 0.23 2.38 89.57 Figure 6. Photomicrographs of spray-formed/aged H13 tool steel. 500°C soak for 1 hr. 3% nital etch. (a) Optical photomicrograph. (b) SEM image (BSE mode) near a grain boundary. Table gives EDS composition of numbered features. 10 Element Si V Cr Mn Mo Fe Spot #1 (wt%) 0 82.27 9.01 0 4.33 4.39 Spot #2 (wt%) 0 5.30 25.70 0 55.55 13.45 Spot #3 (wt%) 1.60 0.88 6.32 0.28 2.92 88.00 Figure 7. SEM Photomicrograph (BSE mode) of spray-formed/aged H13 tool steel showing adjacent V-rich (dark) and Mo/Cr-rich (light) carbides. 700°C soak for 1/2 hr, 3% nital etch. Table gives EDS composition of numbered features. Material Properties Porosity in spray-formed metals depends on processing conditions. The average as-deposited density of spray-formed H13 was 98-99% of theoretical, as measured by water displacement using Archimedes’ principle. As-deposited hardness was typically about 59 HRC, harder than commercial forged and heat treated material (28 to 53 HRC depending on tempering temperature), and significantly harder than annealed H13 (200 HB). The high hardness is attributable to lattice strain due to quenching stresses and supersaturation. As shown in Figure 8, hardness can be varied over a wide range by artificial aging. 59 HRC as- deposited samples were given isochronal (1 hr) soaks at 50°C increments from 400 to 700°C, air cooled, and evaluated for microhardness. At 400°C, a small decrease in hardness was observed, presumably due to stress relieving. As the soak temperature was further increased, hardness rose to a peak hardness of approximately 62 HRC at 500°C. Higher soak temperature resulted in a drop in hardness as carbide particles coarsened. Peak age hardness in spray-formed H13 tool steel is notably higher than that of commercial hardened material. Normally, commercial H13 dies used in die casting are tempered to about 40 to 45 HRC as a tradeoff since high hardness dies, while desirable for wear resistance, are prone to premature failure via thermal fatigue as the die’s surface is rapidly cycled from 300°C to 700°C during aluminum production runs. 11 Figure 8. Hardness of artificially aged spray-formed H13 tool steel following one hour soaks at temperature. Hardness range of conventionally heat treated H13 included for comparison. As-deposited spray-formed material was also hardened following the conventional heat treatment cycle used with commercial material. Samples of forged/mill annealed commercial and spray- formed materials were austenitized at 1010°C, air quenched, and double tempered (2 hr plus 2 hr) at (538°C). The microstructure in both cases was found to be tempered martensite with a few spheroidal particles of alloy carbide. Hardness values for both materials were very nearly identical. Table 2 gives the ultimate tensile strength and yield strength of spray-formed, cast, and forged/heat treated H13 tool steel measured at test temperatures of 22 and 550°C. Values for spray formed H13 are given in the as-deposited condition and following artificial aging and conventional heat treatments. Values for the spray-formed material are comparable to those of forged and are considerably higher than those of cast tool steel. The spray-formed material seems to retain its strength somewhat better than forged/heat treated H13 at higher temperatures. 12 Table 2. H13 tool steel mechanical properties. Sample/Heat Treatment Ultimate Tensile Strength (MPa) Yield