沖壓模具畢業(yè)論文（墊片沖壓模具設(shè)計）

1、異型墊片沖壓模具設(shè)計摘 要該論文分析了墊片的工藝性，介紹了其特殊復(fù)合?？傮w設(shè)計結(jié)構(gòu)和排樣方案。實踐證明:該模具結(jié)構(gòu)合理、可靠，并能保證產(chǎn)品質(zhì)量，對此類零件的復(fù)合模設(shè)計有重要參考價值。采用復(fù)合模便于生產(chǎn)批量大，尺寸小的工件，可以提高生產(chǎn)率，操作平安，保證質(zhì)量，但復(fù)合模工序安排較為重要，設(shè)計中應(yīng)充分考慮各工序的順序，提高工作效率，提高模具壽命和降低模具本錢。主要工序包括：a落料，b沖孔。本設(shè)計分別論述了產(chǎn)品工藝分析，沖壓方案確實定，工藝計算，模板及零件設(shè)計等問題。本設(shè)計的內(nèi)容是確定復(fù)合模內(nèi)型和結(jié)構(gòu)形式以及工藝性，繪制模具總圖和非標準件零件圖。該墊片復(fù)合?？傮w設(shè)計結(jié)構(gòu)和排樣方案經(jīng)分析論證和實際投產(chǎn)檢

2、驗。實踐證明:模具結(jié)構(gòu)靈活、可靠，并能保證產(chǎn)品質(zhì)量，本錢低，對此類零件的級進模設(shè)計有重要參考價值。通過本論文我掌握了模具設(shè)計的根本的模具技能懂得了怎樣分析零件的工藝性，怎樣確定工藝方案，了解了模具的根本結(jié)構(gòu)，提高了計算能力，繪圖能力，熟悉了標準和標準，同時各科相關(guān)的課程都有了全面的復(fù)習(xí)，獨立思考的能力也有了提高。關(guān)鍵詞：墊片，落料, 沖孔, 模具設(shè)計 MULTI-ARM OF THE RAM DIE DESIGNABSTRACTAfter an analysis on the manufacturability of gasket, a particular progressive die,

3、including its structure and layout design, was developed. The die was reliable in structure and good in operation. It can be important reference to the design of progressive dies for similar parts. Principal manufacturing processes, including: a punching, ,b blanking, .Respectively on the design of

4、the product process, pressing for identification, technology, design templates and components, and other issues. The design is to determine the content of progressive die-mold-type structure and form and process of drawing the map and the non-standard mold of Parts. The structure and layout design o

5、f the gasket are as proof of actual production and testing. Practice has proved: the structure of die is flexible, reliable and can ensure product quality and low cost，it can be important reference to the design of progressive die for such parts.Through this paper we master die design of the basic s

6、kills to understand the mold of what parts of the process, how to determine Process, learn the basic structure of the mold, improved computing power, graphics capabilities, and is familiar with the norms and standards related to curriculum subjects at the same time have a comprehensive review, the a

7、bility of independent thinking has also improved.KEY WORDS: gasket， blank, punch，die design目 錄摘 要.1前 言.5 第一章 設(shè)計任務(wù)書和產(chǎn)品圖.8第二章 零件的工藝性分析.9 2.1 零件的工藝性分析.,.9 2.2 沖裁件的精度.9 2.3 確定工藝方案.9第三章 沖壓模具工藝與設(shè)計計算 .,.11.11 模具類型.11 操作與定位方式.11 卸料與出件方式.11 模架類型及精度.113.2 排樣設(shè)計與計算.113.3 設(shè)計沖壓力與壓力中心,初選壓力機. .123.4 計算凸凹模刃口尺寸及公差.13

8、第四章 模具的總張圖與零件圖.,154.1 沖壓模具的零件圖.15 凹模的設(shè)計.15 凸模的設(shè)計.16 4.1.3凸凹模的設(shè)計.164.2選擇鞏固件及定位零件.17 螺釘規(guī)格的選用.17活動擋料銷.184.3設(shè)計和選用卸料與出件零件.18 卸料板.184.4選擇模架及其它模具零件.19 4,4,1 模架.19 模柄.20 墊板.21 凸模固定板.21 凸凹模固定板.22 4.5壓力機的校核.23 4.6級進模具的裝配圖.24結(jié) 論.25參考文獻.26致 謝.27外文資料.,.28 前 言模具是現(xiàn)代工業(yè)的重要工藝設(shè)備，隨著科學(xué)技術(shù)的不斷進步，它在國民經(jīng)濟中占有越來越重要的地位，開展前景十分廣闊。

9、模具技術(shù)水平在很大程度上決定于人才的整體水平，而模具技術(shù)水平的上下，又決定這產(chǎn)品的質(zhì)量、效益和新產(chǎn)品的開發(fā)能力，因此模具技術(shù)已成為衡量一個國家產(chǎn)品制造水平上下的重要標志。改革開放30年來，我國的模具工業(yè)獲得了飛速的開展，設(shè)計、制造加工能力和水平、都有一了很大的提高。雖然我國模具產(chǎn)品水平有了很大提高，但差距還很大。 近些年來，中國模具的設(shè)計和制造水平有了很大提高，CAD/CAE/CAM等計算機輔助技術(shù)、高速加工技術(shù)、熱流道技術(shù)、氣輔技術(shù)、逆向工程等新技術(shù)得到廣泛應(yīng)用。目前，國內(nèi)外相繼涌現(xiàn)出精密沖壓工藝、軟模成形工藝、高能高速成形工藝及無模多點成形工藝等精密、高效、經(jīng)濟的沖壓新工藝。其中，精密沖裁

10、是提高沖裁件質(zhì)量的有效方法，它擴大了沖壓加工范圍，目前精密沖裁加工零件的厚度可達25mm，精度可達IT1617級；用液體、橡膠、聚氨酯等作柔性凸?；虬寄５能浤３尚喂に?，能加工出用普通加工方法難以加工的材料和復(fù)雜形狀的零件，在特定生產(chǎn)條件下具有明顯的經(jīng)濟效果；采用爆炸等高能效成形方法對于加工各種尺寸在、形狀復(fù)雜、批量小、強度高和精度要求較高的板料零件，具有很重要的實用意義；利用金屬材料的超塑性進行超塑成形，可以用一次成形代替多道普通的沖壓成形工序，這對于加工形狀復(fù)雜和大型板料零件具有突出的優(yōu)越性；無模多點成形工序是用高度可調(diào)的凸模群體代替?zhèn)鹘y(tǒng)模具進行板料曲面成形的一種先進技術(shù)，我國已自主設(shè)計制造

11、了具有國際領(lǐng)先水平的無模多點成形設(shè)備，解決了多點壓機成形法，從而可隨意改變變形路徑與受力狀態(tài)，提高了材料的成形極限，同時利用反復(fù)成形技術(shù)可消除材料內(nèi)剩余應(yīng)力，實現(xiàn)無回彈成形。無模多點成形系統(tǒng)以CAD/CAM/CAE技術(shù)為主要手段，能快速經(jīng)濟地實現(xiàn)三維曲面的自動化成形。沖壓成形是一種歷史悠久的金屬加工工藝方法. 本世紀前20年是我國經(jīng)濟社會開展的重要戰(zhàn)略機遇期。在這樣一個關(guān)鍵歷史時期，制造業(yè)扮演著重要的角色。制造業(yè)中的沖壓成形行業(yè)是開展汽車制造業(yè)、航空航天工業(yè)、金屬制品業(yè)、儀器儀表電器及化工工業(yè)等等的根底，是現(xiàn)階段我國最具商機，既有大好開展機遇，又面臨嚴峻市場挑戰(zhàn)的行業(yè)。因此，依靠技術(shù)進步，大力

12、開展先進成形技術(shù)，振興我國沖壓行業(yè)是歷史性戰(zhàn)略任務(wù)21世紀初，制造業(yè)全球化進程的加快及信息技術(shù)、材料技術(shù)的迅猛開展，必將給沖壓成形技術(shù)和行業(yè)帶來一系列新的深刻的變化。沖壓行業(yè)必須轉(zhuǎn)變觀念，改變機制，加速信息技術(shù)、數(shù)字化技術(shù)與沖壓成形技術(shù)的融合，改變傳統(tǒng)沖壓行業(yè)的面貌，才能滿足國民經(jīng)濟快速開展的需要和提升國際競爭力，把中國的沖壓成形行業(yè)做大做強。沖壓主要是按工藝分類，可分為別離工序和成形工序兩大類。別離工序也稱沖裁，其目的是使沖壓件沿一定輪廓線從板料上別離，同時保證別離斷面的質(zhì)量要求。成形工序的目的是使板料在不破坯的條件下發(fā)生塑性變形，制成所需形狀和尺寸的工件。在實際生產(chǎn)中，常常是多種工序綜合應(yīng)

13、用于一個工件。沖裁、彎曲、剪切、拉深、脹形、旋壓、矯正是幾種主要的沖壓工藝。 沖壓用板料的外表和內(nèi)在性能對沖壓成品的質(zhì)量影響很大，要求沖壓材料厚度精確、均勻；外表光潔，無斑、無疤、無擦傷、無外表裂紋等；屈服強度均勻，無明顯方向性；均勻延伸率高；屈強比低；加工硬化性低。，有6070%是板材，其中大局部是經(jīng)過沖壓制成成品。汽車的車身、底盤、油箱、散熱器片，鍋爐的汽包、容器的殼體、電機、電器的鐵芯硅鋼片等都是沖壓加工的。儀器儀表、家用電器、自行車、辦公機械、生活器皿等產(chǎn)品中，也有大量沖壓件。全世界的鋼材中沖壓是高效的生產(chǎn)方法，采用復(fù)合模，尤其是多工位級進模，可在一臺壓力機上完成多道沖壓工序，實現(xiàn)由帶

14、料開卷、矯平、沖裁到成形、精整的全自動生產(chǎn)。生產(chǎn)效率高，勞動條件好，生產(chǎn)本錢低，一般每分鐘可生產(chǎn)數(shù)百件。 在中國，從事模具技術(shù)研究的機構(gòu)和院校已達30余家。華中科技大學(xué)模具技術(shù)國家重點實驗室、上海交通大學(xué)模具CAD國家工程研究中心、北京機電研究所精沖技術(shù)國家工程研究中心和鄭州工業(yè)大學(xué)橡塑模具國家工程研究中心等，在模具CADCAECAM技術(shù)、冷沖模和精沖模CAD軟件、模具的電加工和數(shù)控加工技術(shù)、快速成型PP和快速制模技術(shù)、新型模具材料等方面都取得了顯著的進步和多項成果。由此展望未來，中國模具工業(yè)將會有一個持續(xù)快速開展的機遇期。我們要很好地把握住這個機遇期，使我國模具工業(yè)有一個很大的提高。 面對這

15、種形勢，我國模具行業(yè)當(dāng)前的任務(wù)是：推進改革，調(diào)整結(jié)構(gòu)，開拓市場，苦練內(nèi)功，提升水平，上新臺階。最終使我國成為真正的模具強國。通過四年的根底課程和專業(yè)課程的學(xué)習(xí)，我對本專業(yè)的理論知識已有了系統(tǒng)的掌握，為以后走上工作崗位打下了結(jié)實的根底。但在這次設(shè)計中我也發(fā)現(xiàn)了我的許多缺乏之處，并加以改正。本套模具就是在發(fā)現(xiàn)錯誤和改正錯誤的過程中完成的，由于知識淺薄，錯誤之處難免，敬請老師指正。 第一章 設(shè)計任務(wù)書和產(chǎn)品圖 本設(shè)計零件名稱為異型墊片，材料為08鋼，材料厚度3mm，大批量生產(chǎn)，沖壓件圖如下列圖所示: 圖1-1 工件圖 技術(shù)要求： 1.材料：08鋼； 2.料厚：3mm； 零件的工藝性分析2.1 零件的

16、工藝性分析 該零件材料為08鋼結(jié)構(gòu)簡單,抗剪強度為300mpa形狀對稱,只有落料，沖孔兩個工序具有良好的沖壓性能，適合沖裁。工件結(jié)構(gòu)相對簡單，有一個20mm的孔兩個8mm的孔；孔與孔、孔與邊緣之間的的距離也滿足要求，最小壁厚為6mm20mm孔與35mm的孔、8mm的孔與R10mm的外圓之間的壁厚。2.2 沖裁件的精度與粗糙度 沖裁件的經(jīng)濟公差等級不高于IT11級,一般落料公差等級最好低于IT10級,沖孔件公差等級最好低于IT9級,工件的尺寸全部為自由公差，可看作IT14級，尺寸精度較底，普通沖裁完全能滿足要求。根據(jù)表8-14得出零件圖如下： 圖2-1 工件圖 該沖裁件包括落料和沖孔兩個根本工序

17、,可采用的沖裁方案有單工序沖裁,復(fù)合沖裁和級進沖裁三種：方案一、單序模：零件屬于中批量生產(chǎn),因此采用單工序須要模具數(shù)量較多,生產(chǎn)率低,所用費用也高,不合理;方案二、：復(fù)合模：mm。 方案三、級進模：大批量生產(chǎn)、沖裁精度較高，沖裁件孔與孔、孔與邊緣尺寸較小時使用，計算該件的最小壁厚為6mm。綜上所述可選方案二復(fù)合模。第三章 沖壓模具工藝與設(shè)計計算根據(jù)零件的沖裁工藝方案,采用復(fù)合沖裁模.導(dǎo)向與定位方式導(dǎo)向形式：滑動導(dǎo)柱導(dǎo)套導(dǎo)向定位方式：板料定位靠導(dǎo)料銷和彈簧彈頂?shù)幕顒訐趿箱N完成，因為該模具采用的是條料，控制條料的送進方向采用的是導(dǎo)料板，無側(cè)壓裝置?？刂茥l料的送進步距采用擋料銷定距。卸料與出件方式

18、沖孔凸模與凸凹模沖孔，沖孔廢料直接落料。利用推件塊將制件頂出。模架類型及精度該模具采用后側(cè)導(dǎo)柱模架，以凹模周界尺寸為依據(jù)，選擇模架規(guī)格。3.2 排樣設(shè)計與計算 根據(jù)零件形狀和增大利用率而采用斜排。 條料寬度與導(dǎo)料板間距離計算 采用無側(cè)壓裝置條料寬度與導(dǎo)料板間距離 條料的寬度B=Dmax+2a+C查表得條料寬度偏差導(dǎo)料板與條料之間的最小間隙C查表B=(35+2x2.8+0.5)mm,根據(jù)實際取料寬為42mm導(dǎo)料板間的距離:A=B+C= 步距S=2X+a1如圖4-1,x=35.28,S=35.28X2+2.5=73.06,圖3-1 排樣圖 條料的利用率=(A/BS)X100%一個進距內(nèi)的坯料面積:

19、,因此材料利用率為:=(A/BS)X100%=(1600.77/3068.52)X100%53%3.3 設(shè)計沖壓力與壓力中心,初選壓力機 落料力 根據(jù)零件圖,用CAD可計算出沖一次零件外周邊之和L=186.6mm,沖孔內(nèi)周邊之和L=113.1mm,又因為=300Mpa,t=3mm,取K=1.3,那么根據(jù)式,F1=KLt沖孔力: F2=KLt推件力:由表卸料力FX 由表,取KX=0.04,那么根據(jù)公稱壓力選取壓力機因此可選壓力機型號為J23-80閉合高度為380H290 壓力中心 因為該制件是簡單對稱件,所以壓力中心為該制件的幾何中心.3.4 計算凸凹模刃口尺寸及公差沖孔尺寸2-根據(jù)表2.3.3

20、,由材料厚度可得Zmin=0.460mm, Zmax=0.640mm.查表磨損系數(shù)表可得磨損系數(shù)X1=0.5,dT=(dmin+x)=(8+0.5X0.36)dA=(dT + Zmin)=(8.18+0.46) 沖孔尺寸20磨損系數(shù)表可得磨損系數(shù)X1=0.5,dT=(dmin+x)=(20+0.5X0.52)dA=(dT + Zmin)=( 20.26+0.46)= 落料尺寸20磨損系數(shù)表可得磨損系數(shù)X1=0.5,DA=(Dmax-x)=(20-0.5X0.52)DT=(DA-Zmax)=(19.74-0.64) 落料尺寸35磨損系數(shù)表可得磨損系數(shù)X1=0.5,DA=(Dmax-x)=(35-

21、0.5X0.62)DT=(DA-Zmax)=(34.69-0.64) 孔心距 60L=L平18=6018X1.48=60第四章 模具的總張圖與零件圖4.1 沖壓模具的零件圖凹模設(shè)計 各沖裁的凹?？拙捎镁€切割機床加工,安排凹模在模架上的位置時,要依據(jù)計算壓力中心的數(shù)據(jù)將壓力中心與模柄中心重合,其輪廓尺寸按公式2.9.3 凹模厚度H=kb=0.3X78=23.4mm 凹模厚度取24mm凹模壁厚C=(1.5-2)H=40mm 所以凹模壁厚度為40mm 凹模長度L=l+2C=78+2X40=158mm 凹模寬度 B=l+2C=35+2X40=115mm由以上算得凹模輪廓尺寸LXBXH=158X115

22、X24,查有關(guān)國家標準,并無厚度適宜,因此我選LXB為標準尺寸,得LXB=160X125凹模材料的選用:材料選用Cr4WmoV。 圖4-1 沖孔凹模4.1.2 凸模設(shè)計凸模材料：參照沖壓模具設(shè)計與制造選用T10A因為所沖的孔均為圓形，而且都都不屬于特別保護的小凸模，所以沖孔凸模采用階梯式，一方面加工簡單，另一方面又便于裝配與更換，沖孔凸模結(jié)構(gòu)如圖： 圖4-2 沖孔凸模 凸凹模設(shè)計由表 圖4-3 凸凹模 選擇鞏固件及定位零件 螺釘規(guī)格的選用:,根據(jù)標準GB699選取材料為45HRC3540 卸料螺釘選用圓柱頭內(nèi)六角卸料螺釘,卸料板上設(shè)置4個卸料螺釘,公稱直徑為12mm 卸料釘尾部應(yīng)留有足夠的行程

23、空間,卸料螺釘擰緊后應(yīng)使卸料板超出凸凹模端面1mm,有誤差時通過在螺釘與卸料板之間安裝墊片來調(diào)整. 圖4-4 卸料螺釘 活動擋料銷: 在卸料板上固定了3個導(dǎo)料銷,用于條料送進的定位.在送進方向上用一個彈簧彈頂裝置的擋料銷, 擋料銷,的尺寸如下列圖: 圖4-5 活動檔料銷4.3 設(shè)計和選用卸料與出件零件卸料以卸料板卸料,出件是以凸凹模往上沖出即可,因此不用設(shè)計出件零件.固定卸料板的平面外形尺寸一般與凹模板相同,其厚度可取10，LXBXH=158X115X10材料為45號鋼由以上根據(jù)凸凹?？稍O(shè)計出卸料板如圖4-6. HYPERLINK :/blog.sina /biye58 t _blank 模具

24、畢業(yè)設(shè)計畢業(yè)設(shè)計詳情： HYPERLINK :/blog.sina /biye58 因為真誠，所以信任！因為專注，所以專業(yè)！因為專業(yè)，所以信賴！淘寶店鋪： HYPERLINK :/shop68037878.taobao / 圖4-6 卸料板4.4 選擇模架及其它模具零件選擇模架:根據(jù)GB/T 2861.5-90,由凹模周界158X115,及安裝要求,選取凹模周界:LXB=160X125,閉合高度:H=170205,上模座:160X125X40下模座:160X125X50導(dǎo)柱25X160, 導(dǎo)套:25X95X38,由以上可得模架如圖4-7所示. 圖4-7 模架 模柄: 由壓力機的型號J23-80

25、.可查得模柄孔的直徑為60,深度為80,由裝配要求,模柄與模柄孔配合為H7/m6并加銷釘防轉(zhuǎn),模柄長度比模柄孔深度小510mm,由于采用固定卸料，上模座回程時受力較大，因此選用壓入式模柄較合理，所以根據(jù)GB2862.1-81得圖4-8所示: 圖4-8 模柄 墊板: 墊板的作用是承受并擴散凸模傳遞的壓力,以防止模座被擠壓損傷,因此在與模座接觸面之間加上一塊淬硬磨平的墊板.墊板的外形尺寸與凸模固定板相同,厚度可取310mm,這里設(shè)計時,由于壓力較大,根據(jù)G選取規(guī)格為LXBXH=160X115X10 凸模固定板: 凸模固定板的外形尺寸與凸模的外形尺寸一致,厚度為18mm,根據(jù)核準選取板的規(guī)格為LXB

26、XH=160X115X18; 圖4-9 凸模固定板 凸凹模固定板: 凸凹模固定板的尺寸與墊板的尺寸一致,厚度為20mm,規(guī)格為LXBXH=160X115X20; 圖4-10 凸模固定板4.5 壓力機的校核 公稱壓力 根據(jù)公稱壓力的選取壓力機型號為J23-80,它的壓力為800699.43所以壓力得以校核; 閉合高度 由壓力機型號知Hmax=380 M=90 H1=100Hmin=HmaxM=380-90=290(M為閉合高度調(diào)節(jié)量/mm,H1為墊板厚度/mm)根據(jù)GB/T 2851.3-90 得模具閉和高度為170H205,根據(jù)公稱壓力選用壓力機閉和高度 290H380, H墊=100因為 H

27、min+10-H墊HHmax-5-H墊 200H275所以H=205 選頂定壓力機J23-8符合要求.H=H(上)+H(墊)+H(凸凹)+L+H(下)=40+10+43.2+H(凸凹)+50=145+ H(凸凹)145+ H(凸凹)=205 H(凸凹)=60如圖4-11所示: HYPERLINK :/blog.sina /biye58 t _blank 模具畢業(yè)設(shè)計畢業(yè)設(shè)計詳情： HYPERLINK :/blog.sina /biye58 因為真誠，所以信任！因為專注，所以專業(yè)！因為專業(yè)，所以信賴！淘寶店鋪： HYPERLINK :/shop68037878.taobao / m/圖4-11

28、裝配圖 結(jié) 論在大學(xué)的學(xué)習(xí)過程中，畢業(yè)設(shè)計是一個重要的環(huán)節(jié)。是我們步入社會參與實際工作的一次極好的演示，我十分有幸提早把畢業(yè)設(shè)計和實際工作有機的結(jié)合起來。經(jīng)過這次設(shè)計，我認識到在沖壓模具設(shè)計中，主要涉及到兩個方面的問題：一是模具結(jié)構(gòu)的整體構(gòu)思，二是技術(shù)標準的選用。在設(shè)計中，整體構(gòu)思非常重要，一次完整的設(shè)計全部由整體構(gòu)思所引導(dǎo)，假設(shè)沒有一個完善的整體構(gòu)思，設(shè)計過程將會很難順利進行。技術(shù)標準的選用也至關(guān)重要，選用合理的技術(shù)標準會很大程度上減小模具的設(shè)計、制造難度。在這次設(shè)計中，我綜合運用本專業(yè)所學(xué)課程的理論和生產(chǎn)實際知識進行一次冷沖壓模具設(shè)計工作的實際訓(xùn)練從而培養(yǎng)和提高學(xué)生獨立工作能力，穩(wěn)固與擴充

29、了冷沖壓模具設(shè)計等課程所學(xué)的內(nèi)容，掌握冷沖壓模具設(shè)計的方法和步驟，掌握冷沖壓模具設(shè)計的根本的模具技能懂得了怎樣分析零件的工藝性。但是畢業(yè)設(shè)計也暴露出自己專業(yè)根底的很多缺乏之處，比方缺乏綜合應(yīng)用專業(yè)知識的能力，對材料的不了解。這次實踐是對自己大學(xué)所學(xué)的一次大的檢閱，使我明白了自己知識還很淺薄。雖然馬上要畢業(yè)了但是自己的求學(xué)之路還很長，以后更應(yīng)在工作中學(xué)習(xí)，努力使自己成為一個對社會有所奉獻的人。參考文獻【1】史鐵梁.冷沖壓設(shè)計指導(dǎo).北京：機械工業(yè)出版社，1999.【2】肖景容、姜奎華.沖壓工藝學(xué).北京：機械工業(yè)出版社，2021.【3】王愛珍.冷作成形技術(shù)手冊.北京：機械工業(yè)出版社，2006.【4】

30、涂光祺.沖模技術(shù).北京：機械工業(yè)出版社，2002.【5】楊玉英.實用沖壓工藝及模具設(shè)計手冊.北京：機械工業(yè)出版社，2005.【6】李天佑.沖模圖冊.北京：機械工業(yè)出版社，1988.【7】謝建、杜東福.沖壓工藝及模具設(shè)計技術(shù)問答.上海：上?？茖W(xué)技術(shù)出版社，2005.【8】何永熹、武充分.幾何精度標準學(xué).北京：北京理工大學(xué)出版社，2006.【9】付宏生.冷沖壓成形工藝與模具設(shè)計制造.北京：化學(xué)工業(yè)出版社，2006.【10】付建軍.模具制造工藝.北京：機械工業(yè)出版社，2007.【11】冷沖模國家標準【12】 周玲.沖模設(shè)計實例詳解.北京：化學(xué)工業(yè)出版社，2007.【13】 中國機械工業(yè)教育協(xié)會.冷沖

31、模設(shè)計及制造.北京：機械工業(yè)出版社，2003.【14】 黃毅宏、李明輝.模具制造工藝.北京：機械工業(yè)出版社，2021.【15】 趙大興.工程制圖.北京：高等教育出版社，2003.【16】 王鵬駒、成虹.沖壓模具設(shè)計師手冊.北京：機械工業(yè)出版社，2021. 致 謝 通過這次畢業(yè)設(shè)計，我深切體會到團體力量的重要性。無論是參考資料的互借，還是問題的探討，都對這次設(shè)計的順利進行起到至關(guān)重要的作用。首先感謝洛陽理工學(xué)院，給我提供這么好的學(xué)習(xí)生活環(huán)境，在校學(xué)習(xí)和生活的日子是我一生中一段難忘的經(jīng)歷！本文是在金文中老師精心指導(dǎo)和大力支持下完成的。金老師以其嚴謹求實的治學(xué)態(tài)度、高度的敬業(yè)精神、兢兢業(yè)業(yè)、孜孜以求

32、的工作作風(fēng)和大膽創(chuàng)新的進取精神對我產(chǎn)生重要影響。他淵博的知識、開闊的視野和敏銳的思維給了我深深的啟迪。這次畢業(yè)設(shè)計能夠順利完成，機電工程系的領(lǐng)導(dǎo)對我的大力支持和幫助，離不開同學(xué)們的熱心幫助，更離不開金文中老師對我的我耐心指導(dǎo)和支持，借此向他們再次表示衷心的感謝。 最后，再次對關(guān)心、幫助我的老師和同學(xué)表示衷心地感謝。6 Bending of sheet6.1IntroductionBending along a straight line is the most common of all sheet forming processes; it can be done in various wa

33、ys such as forming along the complete bend in a die, or by wiping, folding or flanging in special machines, or sliding the sheet over a radius in a die. A very large amount of sheet is roll formed where it is bent progressively under shaped rolls. Failure by splitting during a bending process is usu

34、ally limited to high-strength, less ductile sheet and a more common cause of unsatisfactory bending is lack of dimensional control in terms of springback and thinning. If the line of bending is curved, adjacent sheet is usually deformed in the process and the sheet is either stretched, which may lea

35、d to splitting, or compressed with the possibility of buckling. There are special cases where sheet can be bent along curved lines without stretching or shrinking adjacent areas, but these require special geometric design.In this chapter, simple cases of bending along straight lines are examined for

36、 the elastic, plastic and fully plastic regimes.6.2Variables in bending a continuous sheetAs shown in Figure 6.1, we consider a unit width of a continuous sheet in which a cylindrical bent region of radius of curvature is flanked by flat sheet. The bend angle is , and a moment per unit width M, and

37、a tension (force per unit width) Tare applied. We note that the tensionTis applied at the middle surface of the sheet. The units of Mare force length/length and of Tforce/length. Figure 6.1A unit length of a continuous strip bent along a line.Figure 6.2Deformation of longitudinal fibres in bending a

38、nd tension.6.2.1Geometry and strain in bendingIn bending a thin sheet to a bend radius more than three or four times the sheet thickness, it may be assumed that a plane normal section in the sheet will remain plane and normal and converge on the centre of curvature as shown in Figure 6.2.In general,

39、 a line CD0 at the middle surface may change its length to CD if, for example, the sheet is stretched during bending; i.e. the original length l0 becomesLs = A line AB0at a distance y from the middle surface will deform to a lengthThe axial strain of the fibre AB isWhere a is the strain at the middl

40、e surface or the membrane strain and b is the bending strain. Where the radius of curvature is large compared with the thickness, the bending strain can be approximated as,The strain distribution is approximately linear as illustrated in Figure .2Plane strain bendingIf the flat sheet on eithe

41、r side of the bend in Figure 6.1 is not deforming it will constrain the material in the bend to deform in plane strain; i.e. the strain parallel to the bend will be zero. In this work, plane strain conditions will be assumed, unless stated otherwise.The deformation process in bending an isotropic sh

42、eet is thereforeBending of sheet83Figure 6.3Assumed strain distribution in bending.Following Equations 2.18(b) and 2.19(c), for, = 0, = 1/2, we obtainWhere S is the plane strain flow stress. (Equation 6.6 assumes the von Mises yield condition. If a Tresca yield criterion is assumed,1= f= S.) The str

43、esses on a section along the bend axis are illustrated in Figure 6.4. Clearly, at the edge of the sheet, the stress along the bend axis will be zero at the free surface and plane strain will not exist. It is usually observed that the edge of the sheet will curl as illustrated. This happens because t

44、he stress state is approximately uniaxial tension near the edges of the sheet; the minor strain will be negative near the outer surface and positive near the inner surface giving rise to the anticlasticcurvature as shown. Within the bulk of the sheet, however, plane strain deformation is assumed wit

45、h the minor strain along the axis of the bend equal to zero.Free edgeFigure 6.4Stress state on a section through the sheet in plane strain bending.6.3Equilibrium conditionsWe consider a general stress distribution on a normal section through a unit width of sheet in bending, as shown in Figure 6.5.

46、The force acting on a strip of thickness dy across the unit section is1 dy 1. The tensionTon the section is in equilibrium with the integral of this force element, i.e.Mechanics of Sheet Metal FormingFigure 6.5Equilibrium diagram (a) for a section through a unit width of sheet and (b) at y cal stres

47、s distribution.Integrating the moment of the force element, we obtain(We note too that there is a third equilibrium equation for forces in the radial direction arising from the tension T . This is given in Section by Equation 4.11.)6.4Choice of material modelFor the strain distribution given by Equa

48、tion 6.3, the stress distribution on a section can be determined if a stress strain law is available. In general, the material will have an elastic, plastic strain-hardening behaviour as shown in Figure 6.6(a). In many cases, it is useful to approximate this by a simple law and several examples will

49、 be given. The choice of material model will depend on the magnitude of the strain in the process. The strain will depend mainly on thebend ratio, which is defined as the ratio of the radius of curvature to sheet thickness, /t.6.4.1Elastic, perfectly plastic modelIf the bend ratio is not less than a

50、bout 50, strain-hardening may not be so important and the material model can be that shown in Figure 6.6(b). This has two parts, i.e. if the stress Figure 6.6Material models for bending. (a) An actual stress strain curve. (b) An lastic, perfectly plastic model. (c) A rigid, perfectly plastic model.

51、(d) A train-hardening plastic model. is less than the plane strain yield stress, SWhere the modulus of elasticity in plane strain is slightly different from the uniaxial Youngs modulus , E; i.e.Where is Poissons ratio.For strains greater than the yield strain,Where Sis constant. In isotropic materia

52、ls,Sis related to the uniaxial flow stress byEquation 6.6 for the von Mises yield condition.6.4.2Rigid, perfectly plastic modelFor smaller radius bends, and where we are not concerned with elastic springback, it may be sufficient to neglect both elastic strains and strain-hardening. A rigid, perfect

53、ly plastic model is shown in Figure 6.6(c), where and Sis a value averaged over the strain range as indicated in Section .6.4.3Strain-hardening modelWhere the strains are large, the elastic strains may be neglected and the power law strain-hardening model used, whereFor a material having a known eff

54、ective stress strain curve of the formThe strength coefficient Kcan be calculated using Equations 6.6. This model is illustrated in Figure 6.6(d).6.5Bending without tensionWhere sheet is bent by a pure moment without any tension being applied, the neutral axis will be at the mid-thickness. This kind

55、 of bending is examined here for several types of material behaviour . In these cases, a linear strain distribution as illustrated in Figure 6.3 is assumed and the equilibrium equations, Equations 6.7 and 6.8, will apply. Linear elastic bending of sheet showing the material model (a), the strain dis

56、tribution (b), and the stress distribution (c).6.5.1Elastic bendingThe material model is illustrated in Figure 6.7(a) where the yield stress isS. The stress strain relation is given by Equation 6.9 and for the strain distribution shown in Figure 6.7(b), the stress distribution in Figure 6.7(c) will

57、be obtained. The stress at a distance y from the neutral axis, from Equations 6.4 and 6.13, isThe moment at the section, from Equation 6.8, isFrom Equation 6.15, we have and Equation 6.16 can be written in the familiar form for elastic bending.CurvatureFigure 6.8Moment curvature diagram for elastic

58、bending. Where I = t3/12 is the second moment of area for a unit width of sheet and 1/is the curvature.The limit of elastic bending is when the outer fibre at y = t /2 reaches the plane strain yield stress S. The limiting elastic moment is given byAnd the curvature at this moment isWithin this elast

59、ic range, the moment, curvature diagram is linear as shown in Figure 6.8, i.e.The bending stiffness of unit width of the sheet is E t3/Rigid, perfectly plastic bendingIf the curvature is greater than about five times the limiting elastic curvature, a rigid, perfectly plastic model, Equation

60、6.12, as shown in Figure 6.6(c), may be appropriate, although this will not give information on springback. The stress distribution will be as shown in Figure 6.9. In Equation 6.8, the stress is constant and integrating, we obtain the so-called fully plastic moment Mp asThe moment will remain consta