U形件彎曲模具設(shè)計(jì)【沖壓零件彎曲順序的優(yōu)化及模具設(shè)計(jì)】
U形件彎曲模具設(shè)計(jì)【沖壓零件彎曲順序的優(yōu)化及模具設(shè)計(jì)】,沖壓零件彎曲順序的優(yōu)化及模具設(shè)計(jì),U形件彎曲模具設(shè)計(jì)【沖壓零件彎曲順序的優(yōu)化及模具設(shè)計(jì)】,彎曲,曲折,模具設(shè)計(jì),沖壓,零件,順序,優(yōu)化
沖壓零件彎曲順序的優(yōu)化及模具設(shè)計(jì)
題目簡介:300字:彎曲零件可能存在多個(gè)彎曲角,對彎曲的先后順序做一個(gè)優(yōu)化設(shè)計(jì),對零件進(jìn)行建模,并根據(jù)優(yōu)化結(jié)果設(shè)計(jì)一套彎曲模具。
學(xué)生技能要求:彎曲模具設(shè)計(jì)理論,使用三維造型軟件設(shè)計(jì)模型以及進(jìn)行模具設(shè)計(jì),使用三維動(dòng)畫軟件進(jìn)行動(dòng)畫仿真。
設(shè)計(jì)(論文)主要內(nèi)容:
1、對零件的彎曲順序進(jìn)行優(yōu)化設(shè)計(jì)。
2、完成零件圖的三維造型,彎曲模的總體方案設(shè)計(jì)
(1)對零件的形狀、結(jié)構(gòu)、精度和各項(xiàng)技術(shù)指標(biāo)進(jìn)行工藝性分析,確定模具類型及結(jié)構(gòu)形式;
(2)計(jì)算沖壓力、卸料力、推件力、頂件力及沖壓合力,正確選擇壓力機(jī)的型號,確定排樣方式、模具結(jié)構(gòu)方案,進(jìn)行方案的設(shè)計(jì);
3、完成該零件的模具裝配圖和典型零件圖的繪制
(1)確定成型部分鑲塊鑲拼方法,選擇合理的結(jié)構(gòu)參數(shù),確定各部位結(jié)構(gòu),設(shè)計(jì)模具裝配圖;
(2)計(jì)算凸、凹模刃口尺寸;
(3)校核模具的推桿行程,重要部件的強(qiáng)度,核對全部圖紙;
4、完成該零件模具開合模運(yùn)動(dòng)仿真
主要任務(wù)
1、查閱不少于15篇的相關(guān)資料,其中外文文獻(xiàn)不少于5篇,完成開題報(bào)告。
2、完成彎曲模的裝配圖。
3、完成彎曲模典型零件圖繪制。
4、完成不少于2萬英文(5000漢字)印刷符,且與選題相關(guān)的文獻(xiàn)翻譯。
5、完成15篇以上文摘(其中至少兩篇外文),每篇的閱讀摘要為300~500字。
6、完成1萬字以上論文設(shè)計(jì)計(jì)算說明書。
7、圖紙工作量不少于1#圖5張(其中有一張為手工繪圖)。
進(jìn)度安排
第1-3周 認(rèn)真搜集和學(xué)習(xí)有關(guān)資料文獻(xiàn),完成英文文獻(xiàn)的翻譯
第4-5周 完成15篇以上的文獻(xiàn)摘要(其中三篇外文)
第6-7周 根據(jù)彎曲件的特點(diǎn),確定最優(yōu)方案
第8周 完成開題報(bào)告
第9周 零件建模
第10周 選擇合理的結(jié)構(gòu)參數(shù),確定各部分結(jié)構(gòu)。完成各零部件尺寸的計(jì)算
第11周 完成裝配圖和典型零件圖的繪制
第12周 核對全部圖紙。并且完成該自動(dòng)輸送裝置的運(yùn)動(dòng)仿真
第13周 完成并修改畢業(yè)論文
第14-15周 最后準(zhǔn)備階段,完成畢業(yè)答辯
開題報(bào)告
學(xué)生姓名: XXX
導(dǎo)師姓名、職稱: XXX
所屬學(xué)院: XXXXXX
專業(yè)班級: XXXXXX
設(shè)計(jì)題目: 彎曲模具設(shè)計(jì)
2014年 X 月 X日
1目的及意義
精密級進(jìn)模技術(shù)水平的高低是衡量一個(gè)國家制造水平的重要標(biāo)志,級進(jìn)模又稱連續(xù)模或者跳步模,是指壓力機(jī)在一次行程中,依次在幾個(gè)不同的位置上,同時(shí)完成多道工序的沖模。沖壓模具是沖壓生產(chǎn)必不可少的工藝裝備,是技術(shù)密集型產(chǎn)品。沖壓件的質(zhì)量、生產(chǎn)效率以及生產(chǎn)成本等,與模具設(shè)計(jì)和制造有直接關(guān)系。模具設(shè)計(jì)與制造技術(shù)水平的高低,在很大程度上決定著產(chǎn)品的質(zhì)量、效益和新產(chǎn)品的開發(fā)能力。我國沖壓模無論在數(shù)量上,還是在質(zhì)量、技術(shù)和能力等方面都已有了很大發(fā)展,但與國民經(jīng)濟(jì)需求和世界先進(jìn)水平相比,差距仍很大,一些大型、精密、復(fù)雜、長壽命的高檔模具每年仍大量進(jìn)口,特別是中高檔轎車的覆蓋件模具,目前仍主要依靠進(jìn)口。一些低檔次的簡單沖模,已趨供過于求,市場競爭激烈。
通過本次畢業(yè)設(shè)計(jì),我們能夠真正的鞏固所學(xué)的專業(yè)知識(shí),掌握運(yùn)用專業(yè)軟件解決實(shí)際問題的能力,如AUTO CAD、UG、3DMAX。這將會(huì)使我們運(yùn)用這些軟件的能力得到提升。另外,本次畢業(yè)設(shè)計(jì),將使我掌握寫論文的一般步驟及方法,同時(shí)也提高了我如何快速而有效的查閱相關(guān)信息的能力,不僅鍛煉了我在遇到困難時(shí)冷靜分析獨(dú)立思考及解決問題的能力,而且培養(yǎng)了我和同學(xué)相互討論,相互學(xué)習(xí)的習(xí)慣。
2國內(nèi)外的研究現(xiàn)狀分析
近年來中國模具技術(shù)有了較快的發(fā)展,整體水平有了較大提升,以沖壓模具為例,占國內(nèi)模具生產(chǎn)總量40%的沖壓模具,其制品覆蓋了汽車、電子、通訊、機(jī)械、電機(jī)電器、儀器儀表和家電等產(chǎn)品范圍,在汽車輕量化、新能源、自動(dòng)化裝備、醫(yī)療器械、航空航天、節(jié)能減排等領(lǐng)域的模具發(fā)展勢頭強(qiáng)勁。其中,代表先進(jìn)沖壓模具技術(shù)的大型精密復(fù)雜沖模和精密多工位級進(jìn)模占主流,不但數(shù)量有所增加,而且產(chǎn)品水平明顯提升。衡量多工位級進(jìn)模水平,主要包括模具制造精度(包括尺寸精度,步距精度,表面粗糙度),模具使用壽命(包括刃磨一次壽命,沖次速度),模具制造周期和復(fù)雜程度等要素。國內(nèi)級進(jìn)模與國際先進(jìn)水平的主要差距體現(xiàn)在以下幾個(gè)方面:
(1)模具制造精度方面和國外先比,模具的精細(xì)化制造程度上低一級。
(2)模具的使用壽命和國外相比,低30%以上。模具維護(hù)次數(shù)增加,降低了生產(chǎn)效率。
(3)模具穩(wěn)定性和可靠性與國際先進(jìn)水平相比,在試模和模具使用中的調(diào)整及維修時(shí)間增加30%以上,這種差距,是直接影響國內(nèi)模具市場競爭力的要素。
(4)模具制造周期方面與國際先進(jìn)水平相比,差距不斷縮小,但是在接單較多、而制造周期集中的情況下,導(dǎo)致模具不能如期交貨,從總體來看,模具規(guī)范化生產(chǎn)的能力和交貨期的實(shí)現(xiàn)率較國際水平低10%以上。
除模具綜合水平量化在指標(biāo)上的差距外,國內(nèi)在研發(fā)能力、人員素質(zhì)和對模具設(shè)計(jì)制造的基礎(chǔ)理論與技術(shù)的研究等方面與國外先進(jìn)模具企業(yè)相比,也存在一定的差距。
3研究的基本內(nèi)容、擬采用的技術(shù)方案及措施
3.1研究的基本內(nèi)容
(1)對零件的形狀、結(jié)構(gòu)、精度和各項(xiàng)技術(shù)指標(biāo)進(jìn)行工藝性分析,確定模具類型及結(jié)構(gòu)形式;
(2)計(jì)算沖裁力、卸料力、推件力、頂件力及沖壓合力,正確選擇壓力機(jī)的型號,確定排樣方式、模具結(jié)構(gòu)方案,進(jìn)行方案的設(shè)計(jì);
(3)計(jì)算零件的展開尺寸,結(jié)合排樣圖,確定條料的寬度及送進(jìn)步距;
(4)計(jì)算凸、凹模刃口尺寸;
(5)校核模具的推桿行程,重要部件的強(qiáng)度;
(6)確定成型部分鑲塊鑲拼方法,選擇合理的結(jié)構(gòu)參數(shù),確定各部位結(jié)構(gòu),設(shè)計(jì)模具裝配圖;
(7)校核全部圖紙;
3.2工藝方案的確定
3.2.1工藝性分析
圖3-1零件二維圖
如圖3-1,該零件為彎曲件,其生產(chǎn)過程包括落料、彎曲兩種工藝,具體為、兩端和單側(cè)翼的彎曲工序以及整個(gè)外形的落料工序。
現(xiàn)分析其工藝性:由于該零件大批量生產(chǎn),考慮到生產(chǎn)率故采用級進(jìn)?;驈?fù)合模生產(chǎn),零件結(jié)構(gòu)比較簡單,規(guī)則,尺寸適中,最高精度IT12級,均符合沖裁件的工藝要求,另外單側(cè)的彎曲寬度為15mm,屬寬板彎曲,為減少零件回彈,不妨取接近最小彎曲半徑的值,查機(jī)械手冊知該材料最小彎曲半徑為0.1t(為軟鍍鋅板材料),厚度為1mm,故取0.2mm,下料及沖裁時(shí)注意材料方向性,彎曲時(shí)注意使毛刺位于彎曲的內(nèi)側(cè)。由于工件結(jié)構(gòu)比較簡單規(guī)則,為了簡化模具結(jié)構(gòu),降低沖裁力,提高材料利用率,采用少廢料排樣,另外為使去邊料的刃口尺寸盡可能簡單,最終采用單樣。
3.2.2最佳工藝方案確定
A方案 去邊料、彎曲、剪切多工序級進(jìn)模生產(chǎn),由于材料厚度為1mm,因此采用側(cè)刃或者送料機(jī)定距。
B方案 先落料彎曲然后彎曲,然后再折彎的復(fù)合模具和單工序配合生產(chǎn),考慮到零件批量很大,且凸凹模壁厚在允許的厚度內(nèi),能夠保證強(qiáng)度,為了操作方便、安全和提高生產(chǎn)率,結(jié)構(gòu)。排樣圖如圖3-3
C 方案 采用落料然后折彎 折彎 折彎 彎曲 采取單工序
B方案落料和彎曲在同一工位進(jìn)行,對零件的定位有較高要求,而且復(fù)合模的設(shè)計(jì)制造都比較復(fù)雜,還得落料后先抽出凸模才能進(jìn)行彎曲,不易實(shí)現(xiàn);
C方案將彎曲作為一個(gè)單工序分離出來,雖然制件的精度能得到保證,但是采用四套模具增加了成本,而且零件的轉(zhuǎn)移和定位降低了生產(chǎn)效率;
A方案采用去邊料、彎曲、剪切級進(jìn)模生產(chǎn),效率最高,由于采用的是側(cè)刃定距,不會(huì)造成材料的浪費(fèi)和存在定距側(cè)刃制造的高成本,同時(shí)保證了產(chǎn)品的位置精度,更加適合大批量生產(chǎn)。故選用A方案。
4.進(jìn)度安排
第1-3周 進(jìn)行畢業(yè)實(shí)習(xí),為下一階段的畢業(yè)設(shè)計(jì)做準(zhǔn)備
第4-5周 認(rèn)真搜集和學(xué)習(xí)有關(guān)資料文獻(xiàn),完成英文文獻(xiàn)的翻譯
第6-7周 完成15篇以上的文獻(xiàn)摘要(其中三篇外文)
第8周 根據(jù)沖壓廢料輸送的特點(diǎn),論爭幾種基本的輸送方案,并且確定最優(yōu)方案
第9周 完成開題報(bào)告
第10周 選擇合理的結(jié)構(gòu)參數(shù),確定各部分結(jié)構(gòu)。完成各零部件尺寸的計(jì)算
第11周 完成裝配圖和典型零件圖的繪制
第12周 核對全部圖紙。并且完成該自動(dòng)輸送裝置的運(yùn)動(dòng)仿真
第13周 完成并修改畢業(yè)論文
第14-15周 最后準(zhǔn)備階段,完成畢業(yè)答辯
5.參考文獻(xiàn)
[1]姜立忠,張建營,周耀東,畢大森.汽車結(jié)構(gòu)件多工位精密級進(jìn)模排樣及模具設(shè)計(jì)[J].鍛壓技術(shù).2009(03)
[2]張蔭朗.多工位級進(jìn)模設(shè)計(jì)入門(七)[J].模具工業(yè).1993(07)
[3]林國萍.多工位級進(jìn)模排樣圖分析[J].機(jī)械工人(熱加工).1994(01)
[4]張正修,張鎮(zhèn),趙向珍.級進(jìn)模排樣設(shè)計(jì)[J].模具制造.2004(12)
[5]張蔭朗.多工位級進(jìn)模設(shè)計(jì)入門(三)[J].模具工業(yè).1993(03)
[6]蔣成.多工位級進(jìn)模精加工[J].機(jī)械工人.冷加工.1987(03)
更多還原
[7]劉利.級進(jìn)模設(shè)計(jì)的關(guān)鍵──徹底的標(biāo)準(zhǔn)化[J].鍛壓機(jī)械.1995(03)
[8]姜伯軍.級進(jìn)模沖件與載體最后分離的設(shè)計(jì)[J].模具制造.2002(12)
更多還原
[9]張斌.級進(jìn)模設(shè)計(jì)需考慮的幾個(gè)問題[J].模具制造.2004(02)
[10]郭平喜,馬定勝.級進(jìn)模側(cè)刃的設(shè)計(jì)[J].模具制造.2001(02)
[11]Zone-Ching Lin, Chang-Cheng Chen.The application of the moment equilibrium model to the offset of pressure center of trimming progressive die in IC packaging machine[J].Journal of Materials Processing Tech,2003,140 (1):653-661
[12]Zelinski,Peter.The Progress of a Progressive Die Maker[J].Modern Machine Shop,2010,82 (12)
[13]Wu Xiao Feng, Xu Na , Lou Fei Peng , Li Yong De , Shi Jun Bo.Failure Analysis of the Guide Pillar in a Progressive Die[J].Advanced Materials Research, 2011,1167 (197):1416-1419
[14]S.Kumar,R. Singh.Automation of strip-layout design for sheet metal work on progressive die[J].Journal of Materials Processing Tech,2007,195 (1-3):94-100.
[15]Mehrdad Ghatrehnaby,Behrooz Arezoo.Automatic strip layout design in progressive dies[J].Journal of Intelligent Manufacturing2010,23 (3)
6.指導(dǎo)教師意見
指導(dǎo)教師簽名:_______________________ 年 月 日
設(shè) 計(jì)
課 題: 沖壓零件彎曲順序的優(yōu)
化及模具設(shè)計(jì)
設(shè)計(jì)時(shí)間: 2013.XX.XX~XX.XX
班 級: XXXXX
學(xué) 號: XXXXXXX
姓 名: XXXX
指導(dǎo)教師: XXXX
完成日期:201X 年XX月 XX 日
前言
一、彎曲的概念與應(yīng)用
金屬材料被彎成一定形狀和角度的零件的成形方法稱為彎曲。彎曲是沖壓生產(chǎn)中應(yīng)用廣泛的一種工藝,可用于制造大型結(jié)構(gòu)零件,,如飛機(jī)機(jī)翼、汽車大梁等,也可用于生產(chǎn)中小型機(jī)器及電子儀器儀表零件,如鉸鏈、點(diǎn)子元器件等。根據(jù)彎曲件的不同要求和生產(chǎn)批量的大小,有各種不同的彎曲方法。最常用的是以彎曲模具在通用壓力機(jī)上進(jìn)行壓彎,此外也有在折彎機(jī)、滾彎機(jī)、拉彎機(jī)上進(jìn)行的折彎、滾彎、及拉彎。
目錄
前言·····················································2
設(shè)計(jì)任務(wù)書···············································5
U形件彎曲模
第一章 工藝分析········································6
1.1材料分析··········································6
1.2結(jié)構(gòu)分析··········································6
第二章 工藝方案擬定····································7
2.1毛坯展開··········································7
2.2方案確定···········································8
第三章 模具彎曲工藝計(jì)算·································8
3.1沖壓力計(jì)算········································8
3.2模具工作部分尺寸計(jì)算······························9
第四章 模具總結(jié)構(gòu)形式確定·····························12
第五章 沖壓設(shè)備的選擇·································12
第六章 彎曲模模架及零件設(shè)計(jì)···························13
6.1模架的選用······································13
6.2其它零件結(jié)構(gòu)·····································13
第七章 模具制造工藝過程·······························16
7.1凹模制造工藝過程·································16
7.1凸模制造工藝過程·································16
第八章 模具各部分零件參數(shù)·····························16
第九章 橡膠墊的選用···································17
第十章 總工程圖·······································18
總結(jié)·················································19
致謝信···············································20
參考文獻(xiàn)·············································22
附錄·················································23
任務(wù)書
設(shè)計(jì)題目:沖壓零件彎曲順序的優(yōu)化及模具設(shè)計(jì)
一、設(shè)計(jì)要求
下圖是生產(chǎn)中常見的零件圖,零件寬為19.5mm,材料為Q235鋼。請?jiān)O(shè)計(jì)U形件彎曲模。
要求:
1. 查模具設(shè)計(jì)資料,計(jì)算該彎曲件的下料長度
2. 查該模具設(shè)計(jì)資料,計(jì)算出模具凸、凹刃口尺寸
3. 繪制一幅模具裝配圖一;主要零件圖2
4. 圖紙格式必須符合國家標(biāo)準(zhǔn)
彎曲模具設(shè)計(jì)
本課題為一個(gè)需要多次折彎的一個(gè)彎曲件其兩端為二次折彎一個(gè)折彎角,其比較簡單的做法就是做單一的單工序模具,但是這樣設(shè)計(jì)模具工序比較多浪費(fèi)腦動(dòng)力,資源浪費(fèi)比較嚴(yán)重,所以本次設(shè)計(jì)對其進(jìn)行優(yōu)化,具體為落料,第一次折彎,第二次折彎,如圖示意
落料
第一次折彎
第二次折彎
本次設(shè)計(jì)主要設(shè)計(jì)第二次設(shè)計(jì)
如圖所示的彎曲件,其材料為Q235,料厚2mm,板寬19.5mm。
圖1
一、工藝性分析。
1、材料分析。
該工件所用材料Q235是常用的沖壓材料,塑性較好,適合沖壓加工。
2、結(jié)構(gòu)分析。
該工件結(jié)構(gòu)簡單,形狀對稱,適合彎曲。
工件彎曲半徑為2mm,查表3.1(垂直于纖維),查表rmin=0.1t=0.6mm,即能一次彎曲成功。工件的彎曲直邊高度為15mm,遠(yuǎn)大于2t,因此可以彎曲成功。該工件是一個(gè)彎曲角度為90o的彎曲件,所有尺寸精度均未標(biāo)注公差,而當(dāng)r/t<5時(shí),可以不考慮圓角半徑的回彈,所以該工件符合普通彎曲的經(jīng)濟(jì)精度要求。
3、結(jié)論。
該工件的彎曲工藝性良好,適合進(jìn)行彎曲加工。
二、工藝方案的擬定。
1、毛坯展開。
如圖所示:
圖2
毛坯總長度等于各直邊長度加上各圓角展開長度,即:
L=2L1+2L2+L3
由圖1可得
L1=19mm
L2=22mm(x查表1可得)
L3=46mm
于是可得
L≈93.6mm
同理L寬=45.3mm
r/t
0.1
0,2
0.3
0.4
o.5
0.6
0.7
0.8
1.0
1.2
x
0.21
0.22
0.23
0.23
0.25
0.26
0.28
0.30
0.32
0.33
r/t
1.3
1.5
2.0
2.5
3.0
4.0
5.0
6.0
7.0
≥8.0
x
0.34
0.36
0.38
0.39
0.40
0.42
0.44
0.46
.048
0.50
表1
2、方案確定。
由圖1分析看出,該產(chǎn)品需要的基本沖壓工序?yàn)槁淞?、彎曲。根?jù)上述分析結(jié)果,生產(chǎn)該產(chǎn)品的工藝方案為先落料,再彎曲。
三、彎曲工藝計(jì)算。
1、沖壓力的計(jì)算。
(1)力的計(jì)算。
彎曲力的大小不僅與毛坯尺寸、材料的力學(xué)性能、凹模支點(diǎn)間的間距、彎曲半徑及凸凹模間隙等因素有關(guān),而且與彎曲方法也有很大的關(guān)系。生產(chǎn)中常用經(jīng)驗(yàn)公式進(jìn)行計(jì)算。
1) 折彎力
FZ=0.7Kbt2σb/r+t=0.7×1.3×50×2×2×400/2=18.2KN
式中: FZ——材料在沖壓行程結(jié)束時(shí)的彎曲力,N;
b ——彎曲件的寬度,mm;
t——彎曲材料的厚度,mm;
——彎曲件的內(nèi)彎曲半徑,mm;
——材料強(qiáng)度極限,Mpa;
——安全系數(shù),一般?。?.3。
(2)頂件力的計(jì)算。
對于設(shè)置頂件裝置或壓料裝置的彎曲模,其頂件力(或壓料力)(或)可近似取自由彎曲力的30~80%,即
FD=(0.3~0.8)FZ
1)頂件力由式得
FD=0.6FZ=0.3×18.2N≈5.5KN
(3)壓力機(jī)公稱壓力的確定。
對于有彈性頂件裝置的自由彎曲壓力機(jī)噸位可按下式計(jì)算:
F設(shè)=(1.1~1.2)(Fz+Fd)
F設(shè)——壓力機(jī)公稱壓力,N
1) 公稱壓力由式得
F設(shè)=(1.1~1.2)×(18.2+5.5)KN=(1.1~1.2)23.7KN,即F設(shè)=28.44KN,該工件不需要考慮圓角的回彈,故不需要用校正彎曲來控制回彈,所以選用160KN的開式壓力機(jī)。
2、模具工作部分尺寸計(jì)算。
工作零件
(1)凸、凹模間隙計(jì)算。
由式由c=(1.05~1.15)t 可取c=1.1t=2.2mm。
(2)凸凹模寬度尺寸。
彎曲工序中,凸、凹模的寬度尺寸根據(jù)彎曲工件的標(biāo)注方式不同,可根據(jù)下列情況分別計(jì)算。
1)標(biāo)注外形尺寸的彎曲件 應(yīng)以凹模為基準(zhǔn),首先設(shè)計(jì)凹模的寬度尺寸。
①當(dāng)工件標(biāo)注成雙向偏差時(shí):
凹模寬度
②當(dāng)工件標(biāo)注成單向偏差時(shí):
凹模寬度
在工件標(biāo)注外形尺寸的情況下,凸模寬度應(yīng)按凹模寬度尺寸配制,并保證單邊間隙為c,即
2)標(biāo)注內(nèi)形尺寸的彎曲件 應(yīng)以凸模為基準(zhǔn),首先設(shè)計(jì)凸模的寬度尺寸。
①當(dāng)工件標(biāo)注成對稱偏差時(shí)
凸模寬度
②當(dāng)工件標(biāo)注成單向偏差時(shí)
凸模寬度
在工件標(biāo)注內(nèi)形尺寸的情況下,凹模寬度應(yīng)按凸模寬度尺寸
行配制,并保證單邊間隙為c,即
在式中,
——彎曲凸、凹模寬度尺寸,mm;
——彎曲件外形或內(nèi)形基本尺寸,mm;
C——彎曲模單邊間隙,mm;
——彎曲件尺寸公差,mm;
——凸、凹模制造公差,一般取(1/3~1/4)Δ
由于工件標(biāo)注在外形上,因此以凹模為基準(zhǔn),先計(jì)算凹模寬度尺寸,由GB/T15055-2007查得:
基本尺寸為50mm,板厚2mm的彎曲件未注公差為±0.08mm,則由式:
凹模寬度:=mm=mm
凸模寬度:=mm=mm
(3)凸、凹模圓角半徑的確定。
1)凸模圓角半徑。
在保證不小于最小彎曲半徑值的前提下,當(dāng)零件的相對圓角半徑較小時(shí),凸模圓角半徑取等于零件的彎曲半徑,即。
2)凹模圓角半徑。
凹模圓角半徑的大小影響彎曲力、彎曲件質(zhì)量與彎曲模壽命,凹模兩邊的圓角半徑應(yīng)一致且合適,過小,彎曲力會(huì)增加,會(huì)刮傷彎曲件表面,模具的磨損加大;過大,支撐不利,其值一般根據(jù)板厚取或直接查表。
t≤2mm時(shí), rd=(3~6)t
t=2~4mm時(shí), rd=(2~3)t
t=≥4mm時(shí), rd=2t
rd由表查得為2mm。
(4)凹模工作部分深度。
過小的凹模深度會(huì)使毛坯兩邊自由部分過大,造成彎曲件回彈量大,工作不平直;過大的凹模深度增加了凹模尺寸,浪費(fèi)模具材料,并且需要大行程的壓力機(jī),因此模具設(shè)計(jì)中,要保持適當(dāng)?shù)陌寄I疃取T摦a(chǎn)品零件為彎邊高度不大且兩邊要求平直的沖壓零件彎曲順序的優(yōu)化及模具設(shè)計(jì),則凹模深度應(yīng)大于零件的高度,且高出值h0=2mm。查表得凹模工作部分深度為10mm如下圖所示:
四、模具總體結(jié)構(gòu)形式確定。
為操作方便,選用后側(cè)滑動(dòng)導(dǎo)柱模架,毛坯利用凹模上的定位板定位,剛性推件裝置推件,頂件裝置頂件,并同時(shí)提供頂件力,防止毛坯竄動(dòng)。
折彎模具
五、沖壓設(shè)備的選擇。
因?yàn)榇斯ぜ璐笈可a(chǎn),精度要求不高,因壓力機(jī)公稱壓力算得為24KN,故選用160KN的壓力機(jī),為JA23-63A。
其參數(shù)如下:
公稱壓力 160KN
滑塊行程 50mm
行程次數(shù) 160/min
最大閉合高度 210mm
六、模架及零件設(shè)計(jì)。
1、后側(cè)導(dǎo)柱模架的選用。
標(biāo)準(zhǔn)模架的選用依據(jù)為凹模的外形尺寸,所以因首先計(jì)算凹模周界的大小。查表的凹模周界大小為200mm×200mm。
折彎模具采用中間導(dǎo)柱模架,查的模架的規(guī)格為:
上模座:320mm×220mm×35mm;
下模座320mm×220mm×45mm;
導(dǎo)柱28mm×200mm;
導(dǎo)套28mm×110mm×43mm。
2、其它零件結(jié)構(gòu)。
墊板:此模具中需采用墊板,墊板厚度h=10。材料選用45鋼,熱處理43~48HRC。
凸模固定板:凸模固定板與凸模采用過渡配合關(guān)系,平面尺寸與凹模外形尺寸相同。固定板的厚度為20mm。材料選用Q235鋼。
定位板:定位板尺寸與毛坯的長度尺寸有關(guān),其外形尺寸與凹模尺寸相同。材料選用45鋼,熱處理43~48HRC。
頂件板:頂件板尺寸與凹??紫嗯浜?,平面尺寸與凹模內(nèi)形尺寸相同。材料選用45鋼,熱處理43~48HRC。
模柄:模具采用材料為A3的壓入式模柄GB/T2862.1—81根據(jù)設(shè)備的??壮叽纾瑧?yīng)選用規(guī)格為A32×95的模柄。
銷釘:模具的銷釘選用圓柱銷GB/T 119.1,根據(jù)設(shè)備尺寸分別為:,銷?10×50。材料選用35鋼,熱處理28~38HRC。不經(jīng)表面處理的圓柱銷。
鏍釘:模具采用圓柱頭內(nèi)六角螺釘GB/T 70.1,根據(jù)尺寸分別為:螺釘M12×85,螺釘M10×71,螺釘M8×38,螺釘M12×64, 螺釘M10×122,材料為35鋼,熱處理:硬度28~38HRC表面氧化。
導(dǎo)柱:模具導(dǎo)柱選用直徑d=28mm,長度h=200mm的A型導(dǎo)柱。材料為20鋼,熱處理:滲碳深度0.8~1.2mm,硬度58~62HRC。導(dǎo)柱 A28×200 GB2861.1—90。
導(dǎo)套:模具導(dǎo)套選用內(nèi)徑d=28mm,長度L=100mm,外徑D=43mm的A型導(dǎo)套。材料為20鋼,熱處理:滲碳深度0.8~1.2mm,硬度58~62HRC。導(dǎo)套 28×110×43 GB2861.6。
凸模 :模具凸模的結(jié)構(gòu)形式及尺寸如下圖所示。材料選用Cr12,熱處理56~60HRC。
凸模
凹模 :模具凹模的結(jié)構(gòu)形式及尺寸如下圖所示,材料選用Cr12,熱處理56~60HRC。
七、模具制造工藝過程。
1、凹模制造工藝過程。
下料——鍛造——正火——機(jī)加工(粗)——調(diào)質(zhì)——機(jī)加工(精)——淬硬58HRC——磨削
2、凸模制造工藝過程。
下料——鍛造——正火——機(jī)加工(粗)——調(diào)質(zhì)——機(jī)加工(精)——淬硬60HRC——磨削
正火:作為預(yù)先熱處理,目的是消除鍛件內(nèi)應(yīng)力,細(xì)化晶粒,改善切削加工性。
調(diào)質(zhì):獲得回火索氏體,具有較好的綜合力學(xué)性能,為表面淬火做好組織準(zhǔn)備。
淬硬:作為最終熱處理,使工作表面得到高的硬度、耐磨性和疲勞強(qiáng)度,使零件消除應(yīng)力,防止磨削和產(chǎn)生裂痕,并保持高硬度和耐磨性。
八、模具各部分零件參數(shù)。
折彎模具
上模座 45 長300mm,寬220mm,厚35mm
凸模墊板 45剛 長180mm,寬140mm, 厚10mm
凸模固定板 45鋼 長180mm,寬140mm,厚20mm
凹模 Cr12 長 180mm,寬140mm,厚35mm
模具閉合高度 H=200mm
九、橡膠墊的選用。
1.為保證橡膠墊不過早失去彈性而損壞,其允許的最大壓縮量不得超過自由高度的45%,一般取H總=(0.35~0.45)H自由。橡膠墊的預(yù)壓縮量一般取自由高度的10%~15%。
H工作=H總—H預(yù)
故工作行程: H工作=H總-(0.1~0.15)H自由
由工作行程可計(jì)算出橡膠墊高度:
H自由=H工作÷(0.25~0.30)
式中 H自由———橡膠墊自由狀態(tài)下多的高度
H工作———所需工作行程
2.橡膠墊產(chǎn)生的力
F=Ap
式中 F——壓力
A——橡膠墊橫截面積
P——與橡膠墊壓縮量有關(guān)的單位壓力
橡膠墊壓縮量%
單位壓力P/MPa
橡膠墊壓縮量%
單位壓力P/MPa
10
0.26
25
1.06
15
0.50
30
1.52
20
0.70
35
2.10
十、總工程圖
總結(jié)
本次設(shè)計(jì)是在校唯一一次設(shè)計(jì),也是畢業(yè)設(shè)計(jì),各項(xiàng)要求都比較嚴(yán)格,為了能夠很好的完成最后一次功課,交給老師一份滿意的答卷,我從圖書館借來的書籍中和網(wǎng)上查閱了大量的關(guān)于沖壓模具的設(shè)計(jì)資料,這位我在后來的畢業(yè)設(shè)計(jì)實(shí)施過程中減去了不少麻煩。也更通過這次畢業(yè)設(shè)計(jì)我系統(tǒng)的翻閱了兩年半時(shí)間以來所學(xué)的專業(yè)知識(shí),重現(xiàn)的學(xué)習(xí)和掌握,讓自己發(fā)現(xiàn)到更多的不足之處。
在這次的畢業(yè)設(shè)計(jì)中,我綜合了幾年多來所學(xué)的所有專業(yè)知識(shí),使我受益匪淺。不僅使自己的專業(yè)技能有所發(fā)揮并且掌握的更為熟練,也加強(qiáng)了在大學(xué)階段所學(xué)專業(yè)理論知識(shí)的鞏固。
在做畢業(yè)設(shè)計(jì)的過程中,在設(shè)計(jì)和繪圖都遇到方面遇到了一些實(shí)際問題,經(jīng)過老師和同學(xué)的指導(dǎo)幫助,再加上自身不懈的努力,問題得到了及時(shí)解決。這次的畢業(yè)設(shè)計(jì)使我對冷沖壓模具設(shè)計(jì)有了一定的認(rèn)識(shí),在模具設(shè)計(jì)過程中,不僅把大學(xué)所學(xué)到知識(shí)加深了,還學(xué)會(huì)了查閱有關(guān)書籍和資料,能夠把各科靈活的運(yùn)用到設(shè)計(jì)中去。更是鍛煉了自己的查閱資料的能力。
這次的畢業(yè)設(shè)計(jì)不僅是對自己大學(xué)幾年的考核,也是在工作之前對自身的一次全面、綜合型的測試。這為今后的工作做好了鋪墊和奠定了一定的基礎(chǔ)。
致謝
經(jīng)過一個(gè)多月的努力,畢業(yè)設(shè)計(jì)基本完成了。在畢業(yè)設(shè)計(jì)的的實(shí)踐中,學(xué)到很多有用的知識(shí),也積累了不少寶貴的模具設(shè)計(jì)有關(guān)知識(shí)。在這里我特別要感謝我的老師**,由于自身能力有限,總會(huì)在設(shè)計(jì)過程中遇到諸多的問題不能得以很好的解決,多次打擾到**的工作、生活和休息時(shí)間,但**每次總能很好的為我細(xì)心解答。**時(shí)刻關(guān)注我們的設(shè)計(jì)課程。及時(shí)給我們提供一切關(guān)于畢業(yè)設(shè)計(jì)方面要注意的資料,他對工作的積極熱情,認(rèn)真負(fù)責(zé),給我留下深刻印象,使我受益匪淺。在此我向教授表示衷心的感謝和深深的敬意。
這次設(shè)計(jì)的是一個(gè)沖壓零件彎曲順序的優(yōu)化及模具設(shè)計(jì)的簡易沖壓模具。畢業(yè)設(shè)計(jì)歷時(shí)一個(gè)多月。在設(shè)計(jì)過程中,有些尺寸,數(shù)據(jù)是一點(diǎn)都馬虎不得的,只要一個(gè)數(shù)據(jù)有誤,就得全部改動(dòng),使設(shè)計(jì)難度大大增加。在這次設(shè)計(jì)中,我感覺要完成這次設(shè)計(jì)不僅要有扎實(shí)的專業(yè)知識(shí),還要有過硬的計(jì)算機(jī)基礎(chǔ)知識(shí)做保障,才能很好的完成這次設(shè)計(jì)任務(wù)。
這次畢業(yè)設(shè)計(jì)雖說簡單,但收益良多。是對三年所學(xué)知識(shí)一次系統(tǒng)綜合運(yùn)用,在軟件應(yīng)用方面,使我對AutoCAD的應(yīng)用更加熟練,更加認(rèn)識(shí)到在機(jī)械制圖上AutoCAD的極大重要性。同時(shí)這次設(shè)計(jì)涉及到機(jī)械制圖,機(jī)械設(shè)計(jì),模具設(shè)計(jì),互換性以及CAD等各方面內(nèi)容。
即將走上工作崗位了,能有這樣一次設(shè)計(jì),有這樣一個(gè)總結(jié),很高興,很興奮,也很感激。這次,是我親眼看見了花朵變成果實(shí)。雖然它還不是很成熟,但以散發(fā)出淡淡的香氣。感謝默默付出的老師們!關(guān)心支持我的同學(xué),朋友們!
畢業(yè)設(shè)計(jì)的完成,我要感謝我的知道老師教授的大力支持。**為了我們的畢業(yè)設(shè)計(jì),是他的耐心指導(dǎo)和教導(dǎo)才使我的畢業(yè)設(shè)計(jì)逐漸趨于完善。謝謝你,**!
同時(shí),我要感謝給我們授課的各科老師,正是由于你們的傳道,授業(yè),解惑,讓我學(xué)到了專業(yè)知識(shí),并從他們身上學(xué)到了如何求知治學(xué),如何為人處事。我也要感謝我的母校,滁州職業(yè)技術(shù)學(xué)院,是他提供了良好的學(xué)習(xí)環(huán)境和生活環(huán)境,讓我的大學(xué)生活豐富多姿,為我的人生留下精彩的一筆。
與此同時(shí),我還得到了同學(xué)們,朋友們的關(guān)心和幫助,在此一并表示感謝!
同時(shí)更要感謝百忙之中參加答辯考核的評審老師。
即將走上工作崗位,在今后的工作中,我將繼續(xù)努力!
主要參考文獻(xiàn)
信群 主編 AutoCAD 合肥工業(yè)大學(xué)出版社
信群 主編 機(jī)械制圖 合肥工業(yè)大學(xué)出版社
信群 主編 互換性與測量技術(shù) 北京航空航天大學(xué)出版社
榮清 主編 模具設(shè)計(jì)與制造 高等教育出版社
王孝培 主編 沖壓手冊 機(jī)械工業(yè)出版社
郝濱海 主編 沖壓模具簡明設(shè)計(jì)手冊 化學(xué)工業(yè)出版社
梅伶 主編 模具課程設(shè)計(jì)與指導(dǎo) 機(jī)械工業(yè)出版社
王芳 主編 冷沖壓模具設(shè)計(jì)與指導(dǎo) 機(jī)械工業(yè)出版社
編號
無錫太湖學(xué)院
畢業(yè)設(shè)計(jì)(論文)
相關(guān)資料
題目: 軸承保持架沖壓模具設(shè)計(jì)
機(jī)電 系 機(jī)械工程及自動(dòng)化專業(yè)
學(xué) 號: 0923181
學(xué)生姓名: 呂金勇
指導(dǎo)教師: 黃敏(職稱:副教授)
2013年5月25日
無錫太湖學(xué)院
畢業(yè)設(shè)計(jì)(論文)
開題報(bào)告
題目: 軸承保持架沖壓模具設(shè)計(jì)
機(jī)電 系 機(jī)械工程及自動(dòng)化 專業(yè)
學(xué) 號: 0923181
學(xué)生姓名: 呂金勇
指導(dǎo)教師: 黃敏 (職稱:副教授)
2012年11月25日
課題來源
自擬。
科學(xué)依據(jù)(包括課題的科學(xué)意義;國內(nèi)外研究概況、水平和發(fā)展趨勢;應(yīng)用前景等)
(1)課題科學(xué)意義
隨著與國際接軌的腳步日益放慢,市場競爭的日益加劇,人們對模具的各種要求也不斷的加大.可以說模具制造技術(shù)是用來衡量一個(gè)國家工業(yè)發(fā)展水平的重要標(biāo)志。則現(xiàn)階段的工業(yè)生產(chǎn)中,模具是一種非常重要的工藝裝備。其在各個(gè)行業(yè)中也演繹著非常重要的角色,其運(yùn)用于汽車、機(jī)械、航天、航空、輕工、電子、電器、儀表等行業(yè)。在我國的模具行業(yè)中有50%的是沖壓模具,足以看出沖壓模具之重要。所以現(xiàn)階段對于沖壓模具的研究也是非常有必要的。
軸承保持架沖壓模具的研究狀況及其發(fā)展前景
隨著計(jì)算機(jī)技術(shù)的發(fā)展和普及,沖壓模具也基本實(shí)現(xiàn)了計(jì)算機(jī)化,其中使用最多的是cad軟件。抽高壓模具的計(jì)算機(jī)化也是日益發(fā)展趨勢下不可避免的。近些年來各種多軸數(shù)控機(jī)床,激光切割機(jī)床數(shù)控雕刻機(jī)床等等紛紛面世,這些設(shè)備在提高模具的數(shù)量,規(guī)模和制造能力上的作用是不可估量的。還有其中快速成形技術(shù)和快速模具技術(shù)這兩種先進(jìn)的制造技術(shù)也越來越廣泛的應(yīng)用于模具行業(yè)。
中國的模具行業(yè)每年都保持著25%的增長率,其行業(yè)的生產(chǎn)能力也僅次于美國日本,位列世界第三。其行業(yè)生產(chǎn)能力約占世界總量的10%。
然而, 與國際先進(jìn)水平相比, 中國的模具行業(yè)的差距不僅表現(xiàn)在精度差距大、 交貨周期長等方面, 模具壽命也只有國際先進(jìn)水平的 50% 左右。大型、精密、技術(shù)含量高的轎車覆蓋件沖壓模具和精密沖裁模具是現(xiàn)階段最需要解決的問題。綜上由于市場需求模具的現(xiàn)階段發(fā)展快速,應(yīng)用廣其前景也是也是非??春玫?。
研究內(nèi)容
①了解沖壓加工的工作原理,國內(nèi)外的研究發(fā)展現(xiàn)狀;
②完成軸承保持架沖壓模具的總體方案設(shè)計(jì);
③完成有關(guān)零部件的選型計(jì)算、結(jié)構(gòu)強(qiáng)度校核及液壓系統(tǒng)設(shè)計(jì);
④熟練掌握有關(guān)計(jì)算機(jī)繪圖軟件,并繪制裝配圖和零件圖紙,折合A0紙不少于3張;
⑤完成設(shè)計(jì)說明書的撰寫,并翻譯外文資料1篇。
擬采取的研究方法、技術(shù)路線、實(shí)驗(yàn)方案及可行性分析
沖壓是一種利用壓力加工的方法,就是壓力機(jī)上裝上模具對材料施加壓力。使材料分離或者變形形成合格的所需產(chǎn)品。
沖壓模具材料的確定是一開始必須要確認(rèn)的,其次是沖壓模具的結(jié)構(gòu)設(shè)計(jì)分沖壓工藝的確定和模具結(jié)構(gòu)的設(shè)計(jì)兩個(gè)方面,則需從這兩個(gè)方面入手。最后是對模具的壓力計(jì)算還有軟件模擬。
研究計(jì)劃及預(yù)期成果
研究計(jì)劃:
2012年11月17日-2013年1月13日:按照任務(wù)書要求查閱論文相關(guān)參考資料,填寫畢業(yè)設(shè)計(jì)開題報(bào)告書,學(xué)習(xí)并翻譯一篇與畢業(yè)設(shè)計(jì)相關(guān)的英文材料。
2013年1月11日-2013年3月5日:指導(dǎo)員實(shí)訓(xùn)。
2013年3月8日-2013年3月14日:查閱與設(shè)計(jì)有關(guān)的參考資料不少于10篇,其中外文不少于5篇,翻譯機(jī)械方面的外文資料。
2013年3月15日-2013年3月21日:軸承保持架工藝分析。
2013年3月22日-2013年4月11日:初步繪制裝配圖和修改完成。
2013年4月12日-2013年4月25日:對凹凸模尺寸計(jì)算,繪制凹凸模及各零件。
2013年4月26日-2013年5月21日:繪制上下模及其各零件,完成設(shè)計(jì)說明書(論文)、摘要和小結(jié),修改設(shè)計(jì)說明書開題報(bào)告格式,整理所有資料,打印后上交,準(zhǔn)備答辯。
預(yù)期成果。
特色或創(chuàng)新之處
① 沖模的使用便于生產(chǎn)自動(dòng)化,操作簡單,生產(chǎn)率提高。
② 減少制作軸承保持架的材料。
已具備的條件和尚需解決的問題
① 已找到大量相關(guān)資料文獻(xiàn),對軸承保持架零件有相關(guān)認(rèn)識(shí)。
② 沖壓工藝的加工工序
指導(dǎo)教師意見
指導(dǎo)教師簽名:
年 月 日
教研室(學(xué)科組、研究所)意見
教研室主任簽名:
年 月 日
系意見
主管領(lǐng)導(dǎo)簽名:
年 月 日
英文原文
Stress Analysis of Stamping Dies
J. Mater. Shaping Technoi. (1990) 8:17-22 9 1990 Springer-Verlag New York Inc.
R . S . R a o
Abstract:
Experimental and computational procedures for studying deflections, flit, andalignment characteristics of a sequence of stamping dies, housed in a transfer press, are pre-sented. Die loads are actually measured at all the 12 die stations using new load monitors and used as input to the computational procedure. A typical stamping die is analyzed using a computational code, MSC/NASTRAN, based on finite element method. The analysis is then extended to the other dies, especially the ones where the loads are high. Stresses and deflections are evaluated in the dies for the symmetric and asymmetric loading conditions. Based on our independent die analysis, stresses and deflections are found to be reasonably well within the tolerable limits. However, this situation could change when the stamping dies are eventually integrated with the press as a total system which is the ultimate goal of this broad research program.
INTRODUCTION
Sheet metal parts require a series of operations such as shearing , drawing , stretching , bending , and squeezing. All these operations are carried out at once while the double slide mechanism descends to work on the parts in the die stations, housed in a transfer press [1]. Material is fed to the press as blanks from a stock feeder. In operation the stock is moved from one station to the next by a mechanism synchronized with the motion of the slide. Each die is a separate unit which may be independently adjusted from the main slide. An automotive part stamped from a hot rolled steel blank in 12 steps without any intermediate anneals is shown in Figure 1.
Transfer presses are mainly used to produce different types of automotive and aircraft parts and home appliances. The economic use of transfer presses depends upon quantity production as their usual production rate is 500 to 1500 parts per hour [2]. Although production is rapid in this way, close tolerances are often difficult to achieve. Moreover, the presses produce a set of conditions for off-center loads owing to the different operations being performed simultaneously in several dies during each stroke. Thus, the forming load applied at one station can affect the alignment and general accuracy of the operation being performed at adjacent stations. Another practical problem is the significant amount of set-up time involved to bring all the dies into proper operation. Hence, the broad goal of this research is to study the structural characteristics of press and dies combination as a total system. In this paper, experimental and computational procedures for investigating die problems are presented. The analysis of structural characteristics of the transfer press was pursued separately [3].
A transfer press consisting of 12 die stations was chosen for analysis. Typical die problems are excessive deflections, tilt, and misalignment of the upperand lower die halves. Inadequate cushioning and offcenter loading may cause tilt and misalignment of the dies. Tilt and excessive deflections may also be caused by the lack of stiffness of the die bolster and the die itself. Part quality can be greatly affected by these die problems. There are a lot of other parameters such as the die design, friction and lubrication along the die work interface, speed, etc. that play a great role in producing consistently good parts. Realistically, the analysis should be carded out by incorporating the die design and the deforming characteristics of the work material such as the elastic-plastic work hardening properties. In this preliminary study, the large plastic deformation of the workpiece was not considered for the reasons mentioned below.
Large deformation modeling of a sheet stretching process was carded out using the computational code based on an elastic-plastic work hardening model of the deformation process [4]. Laboratory experiments were conducted on various commercial materials using a hemispherical punch. The coefficient of friction along the punch-sheet interface was actually measured in the experiment and used as a prescribed boundary to the numerical model. Although a good solution was obtained, it was realized that the numerical analysis was very sensitive to the frictional conditions along the interface. In the most recent work, a new friction model based on the micromechanics of the asperity contact was developed [5]. In the present problem, there are several operations such as deep drawing, several reduction drawing operations, and coining, which are performed using complex die geometries. The resources and the duration of time were not adequate to study these nonlinear problems. Hence,the preliminary study was limited to die problems basedon linear stress analysis.
A detailed die analysis was carried out by using MSC /NASTRAN code based on finite ele mentmethod. Die loads were.measured at all the stations using new load monitors. Such measured data were used in the numerical model to evaluate stresses and deflections in the dies for normal operating conditions and for asymmetric loading conditions. Asymmetric loading conditions were created in the analysis by tilting the dies. In real practice, it is customary to pursue trial-and-error procedures such as placing shims under the die or by adjusting the cushion pressure to correct the die alignment problems. Such time consuming tasks can be reduced or even eliminated using the computational and experimental procedures presented here.
DIE GEOMETRY AND MATERIALS
The design of metal stamping dies is an inexact process. There are considerable trial-and-error adjustments during die tryout that are often required to finish the fabrication of a die that will produce acceptable parts. It involves not only the proper selection of die materials, but also dimensions. In order to withstand the pressure, a die must have proper cross-sectional area and clearances. Sharp comers, radii, fillets, and sudden changes in the cross section can have deleterious effects on the die life. In this work, the analysis was done on the existing set of dies.
The dies were made of high carbon, high chromium tool steel. The hardness of this tool steel material is in the range of Rockwell C 57 to 60. Resistance to wear and galling was greatly improved by coating the dies with titanium nitride and titanium carbide. The dies were supported by several other steel holders made of alloy steels such as SAE 4140. The geometry of a typical stamping die is axisymmetric but it varies slightly from die to die depending on the operation. Detailed information about geometry andmaterials of a reduction drawing die (station number 4) was gathered from blueprints. It was reproducedin three-dimensional geometry using a preprocessor, PATRAN. One quadrant of the die is shown in Figure2. The data including geometry and elastic properties of the die material were fed to the numerical model.
The work material used was hot rolled aluminumkilled steel, SAE 1008 A-K Steel and the blank thickness was about 4.5 ram. Stampings used in unexposed places or as parts of some deisgn where fine finish is not essential are usually made from hot rolled steel. The automotive part produced in this die set is a cover for a torque converter. A principal advantage of aluminum-killed steel is its minimum strain aging.
EXPERIMENTAL PROCEDURES
As mentioned earlier, this research involved monitoting of die loads which were to be used in the numerical model to staldy the structural characteristicsof dies. The other advantage is to avoid overloadingthe dies in practice. Off-center loading can be detected and also set-up time can be reduced. Thus, any changes in the thickness of stock, dulling of the die,unbalanced loads, or overloadings can be detected using die load monitors.
Strain gage based fiat load cells made of high grade tool steel material were fabricated and supplied by IDC Corporation. Four identical load cells were embedded in a thick rectangular plate as shown in Figure 3. They were calibrated both in the laboratory and in the plant.The plate was placed on the top of the die. The knockout pin slips through the hole in the plate. Six such plates were placed on each of six dies. In this way,24 readings can be obtained at a given time. Then they were shifted to the other six dies for complete data. All the 12 die loads are presented in Table 1.
COMPUTATIONAL PROCEDURES
Linear static analysis using finite element method wasused to study the effect of symmetric and asymmetric loading for this problem. A finite element model of die station 4 was created using the graphical preprocessor, PATRAN, and the analysis was carried outusing the code MSC/NASTRA N . The code has a wide
T a b l e I. Die Loads
Die Station Load
Number (kN)
1 356
2 641
3 214
4 356
5 854
6 712
7 285
8 32O
9 2349
10 1139
11 214
12 2100
spectrum of capabilities, of which linear static analysis is discussed here.
The NASTRAN code initially generates a structural matrix and then the stiffness and the mass matrices from the data in the input file. The theoretical formulations of a static structural problem by the displacement method can be obtained from the references [6]. The unknowns are displacements and are solved for the appropriate boundary conditions. Strains are obtained from displacements. Then they are converted into stresses by using elastic stress-strain relationships of the die material.
The solution procedure began with the creation of die geometry using the graphical preprocessor, PATRAN. The solution domain was divided into appropriate hyper-patches. This was followed by the generation of nodes, which were then connected by elements. Solid HEXA elements with eight nodes were used for this problem. The nodes and elements were distributed in such a way that a finer mesh was created at the critical region of the die-sheet metal interface and a coarser mesh elsewhere. The model was then optimized by deleting the unwanted nodes. The element connectivities were checked. By taking advantage of the symmetry, only one quarter of the die was analyzed. In the asymmetric case, half of the die was considered for analysis. Although, in practice, the load is applied at the top of the die, for the purpose of proper representation of the boundary conditions to the computational code, reaction forces were considered for analysis. The displacement and force boundary conditions are shown for the two cases inFigure 4.
As mentioned earlier, sheet metal was not modeled in this preliminary research. As shown in Figure 4(a),the nodes on the top surface of the die were constrained (stationary surface) and the measured load of 356 kN was equally distributed on the contact nodes at the workpiece die interface. Similar boundary conditions for the punch are shown in Figure 4(b). It is noticeable that fewer nodes are in contact with the sheet metal due to the die tilt for the asymmetric loading case as shown in Figure 4(c). In real practice, the pressure actually varies along the die contact surface. Since the actual distribution was not known, uniform distribution was considered in the present analysis.
DISCUSSION OF RESULTS
As described in the earlier section, the numerical analysis of die Station 4 (both the die and punch) was performed using the code MSC/NASTRAN . Two cases were considered, namely: (a) symmetric loading and (b) asymmetric loading
Fig. 4. Boundary conditions. (A) Symmetric case (onequadrant of the die). (B) Symmetric case (one quadrant ofnthe punch). (C) Asymmetric case (half of the die).
Symmetric Loading
Numerical analysis of the die was carried out for a measured load o f 356 kN as distributed equally in Figure 4(a). The major displacements in the loading direction are shown in Figure 5(a). These displacement contours can be shown in various colors to represent different magnitudes. The m aximum displacement value is 0.01 m m for a uniformly distributed load of 356 kN. The corresponding critical stress is very small, 8.4 MPa in the y direction and 30 MPa in the x direction. The calculated displacements and stresses at the surrounding elements and nodes were
of the same order, but they decreased in magnitude at the nodes away from this critical region. Thus, the die was considered very rigid under this loading condition.
Symmetric loading was applied to the punch and the numerical analysis was carried out separately. The displacement values in the protruding region of the punch were high compared to the die. The maximum displacement was 0.08 m m . It should be noted that the displacement values in this critical range of the punch were of the same order ranging from 0.05 mm to 0.08 ram. Although the load acting on the punch (bottom half) was the same as the die (upper half), that is, 356 kN, the values of displacements and stresses were higher in the punch because of the differences in the geometry. This is especially true for the protruding part of the punch. The corresponding maxim u m stress was 232 MPa. This part of the punch is still in the elastic range as the yield strength of tool steel is approximately 1034 MPa. The critical stress value might be varied for different load distributions. Since the actual distribution of the load was not known,the load was distributed equally on all nodes. As the die (upper half) is operating in a region which is extremely safe, a change in the load distribution may not produce any high critical stresses in the die. Although higher loads are applied at other die stations(see Table 1), it is concluded that the critical stresses are not going to be significantly higher due to the appropriate changes in the die geometries.
Asymmetric Loading
For the purpose of analysis, an asymmetric loading situation was created by tilting the die. Thus, only 15 nodes were in contact with the workpiece compared to 40 nodes for the symmetric loading case. As shown in Figure 4(c), a 356 kN load was uniformly distributed over the 15 nodes that were in contact with the workpiece. Although the pressure was high, because of the geometry at the location where the load was acting, the critical values of displacement and stress were found to be similar to the symmetric case. The predicted displacement and stress values were not significantly higher than the values predicted for the symmetric case.
Fig. 5. Displacement contours in the loading direction. (A) Symmetric case (one quadrant of the
die). (B) Symmetric case (one quadrant of the punch). (C)Asymmetric case (half of the die).
CONCLUSIONS
In this preliminary study, we have demonstrated the capabilities of the computational procedure, based on finite element method, to evaluate the stresses and deflections within the stamping dies for the measured loads. The dies were found to be within the tolerable elastic limits for both symmetric and asymmetric loading conditions. Thus the computational procedure can be used to study the tilt and alignment characteristics of stamping dies. In general, the die load monitors are very useful not only for analysis but also for on-line tonnage control. Future research involves the
integration of the structural analysis of stamping dies with that of the transfer press as a total system.
ACKNOWLEDGMENTS
Professor J.G. Eisley, W.J. Anderson, and Mr. D.Londhe are thanked for their comments on this paper.
REFERENCES
1. R.S. Rao and A. Bhattacharya, "Transfer Process De-flection, Parallelism, and Alignment Characteristics,"Technical Report, January 1988, Department of Mechanical Engineering and Applied Mechanics, the University of Michigan, Ann Arbor.
2. Editors of American Machinist, "Metalforming: Modem Machines, Methods, and Tooling for Engineers and Operating Personnel," McGraw-Hill, Inc., 1982, pp. 47-50.
3. W.J. Anderson, J.G. Eisley, and M.A. Tessmer,"Transfer Press Deflection, Parallelism, and Alignment Characteristics," Technical Report, January 1988, Department of Aerospace Engineering, the University of Michigan, Ann Arbor.
4. B.B. Yoon, R.S. Rao, and N. Kikuchi, "Sheet Stretching: A Theoretical Experimental Comparison," International Journal of Mechanical Sciences, Vol. 31, No.8, pp. 579-590, 1989.
5. B.B. Yoon, R.S. Rao, and N. Kikuchi, "Experimental and Numerical Comparisons of Sheet Stretching Using a New Friction Model," ASME Journal of Engineering Materials and Technology, in press.
6. MSX/NASTRAN, McNeal Schwendler Corporation.22 9 J. Materials Shaping Technology, Vol. 8, No. 1, 1990
中文譯文
沖壓模具的受力分析
R.S.Rao
J.Mater.Shaping Tec
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