橢圓墊片沖壓模具設(shè)計【雙孔墊板】【 落料沖孔復(fù)合?!俊菊f明書+CAD+UG】
橢圓墊片沖壓模具設(shè)計【雙孔墊板】【 落料沖孔復(fù)合?!俊菊f明書+CAD+UG】,雙孔墊板, 落料沖孔復(fù)合模,說明書+CAD+UG,橢圓墊片沖壓模具設(shè)計【雙孔墊板】【,落料沖孔復(fù)合?!俊菊f明書+CAD+UG】,橢圓,墊片,沖壓,模具設(shè)計,墊板,沖孔,復(fù)合,說明書,仿單,cad,ug
畢 業(yè) 設(shè) 計 說 明 書
橢圓墊片沖壓模具設(shè)計
學(xué) 號
姓 名
班 級
專 業(yè)
系 部
指導(dǎo)老師
完成時間 2016 年 11月 22日至 2017 年 4 月 22 日
目 錄
引言………………………………………………………………………………1
第1章零件的結(jié)構(gòu)工藝性分……………………………………………………2
1.1零件結(jié)構(gòu)的形狀分析………………………………………………………2
1.2零件的選材分析……………………………………………………………2
1.3零件精度的分析……………………………………………………………2
第2章 沖裁方案的選定…………………………………………………………3
第3章零件相應(yīng)尺寸的計算……………………………………………………4
3.1刃口尺寸的計算……………………………………………………………4
3.2排樣方法的比較與選澤……………………………………………………5
3.3沖裁力的計算………………………………………………………………5
3.4零件壓力中心的選擇………………………………………………………6
第4章沖裁設(shè)備的選擇與了解…………………………………………………7
第5章工作零件的設(shè)計以及模架的挑選………………………………………8
5.1主要零件的設(shè)計模架選 ……………………………………………………8
5.2模架的選擇…………………………………………………………………10
5.3卸料零件的計算與設(shè)計……………………………………………………10
5.4固定零件的計算與設(shè)計……………………………………………………11
5.5推件塊、推桿及打桿的設(shè)計………………………………………………13
5.6卸料裝置中彈性元件的設(shè)計………………………………………………14
5.7上下模座的計算與設(shè)計……………………………………………………15
第6章模具裝配圖………………………………………………………………17
結(jié)束語……………………………………………………………………………18
參考文獻…………………………………………………………………………19
引 言
模具制造與我們生活息息相關(guān),模具制造是產(chǎn)品批量生產(chǎn)不可缺少的工具。只有擁有高水平的模具,才會有高質(zhì)量的產(chǎn)品。而沖壓模具又是當下制造業(yè)不可或缺的重要組成部分,可以說我們的生活離不開模具制品,離不開模具制造。隨著社會地不斷發(fā)展,生產(chǎn)者和消費者都對產(chǎn)品質(zhì)量有了更高的要求,這也是近年來我國模具行業(yè)一直有著穩(wěn)固地發(fā)展的原因之一。在這其中特別是塑料模具的發(fā)展更為迅速,在很多制造業(yè)大國大型塑料模具設(shè)計造與制造是衡量一個國家工業(yè)化發(fā)展地標尺。而我國的模具發(fā)展水平與一些制造業(yè)大國仍有著很大地差距,無論是在技術(shù)上,還是質(zhì)量上仍然有著很大地進步空間。我國的模具制造地發(fā)展仍然需要大力發(fā)展,不僅要在長三角,珠三角等地有模具制造基地,將來在任何一個城市都要看到有一定實力的模具制造業(yè),只有這樣我國的制造業(yè)才會有跟好的發(fā)展,國家才會更加強大。
合理使用模具進行加工生產(chǎn)不僅可以大大地降低生產(chǎn)成本,還能有效地提高生產(chǎn)效率。當下的生產(chǎn)制造業(yè)發(fā)展的特點是產(chǎn)品種類繁多,更新?lián)Q代較快,市場競爭激烈,這也就使許多模具制造者不斷研發(fā)適用于生產(chǎn)的新型模具,這也有效加速了模具制造業(yè)的發(fā)展。
人們?nèi)粘I钪惺褂玫母鞣N東西無不與模具有關(guān)。由于人們對不同產(chǎn)品性能要求的不同,各種模具的性能也就存在著一定的差異。所以也就有了模具的分類,模具大致可以分為沖壓模具、塑料成形模具、壓鑄模、鍛造成形模具等等,而用到比較多的模具也就是沖壓模具和塑料成形模具。在沒有模具情況下的制造業(yè),生產(chǎn)效率會大大降低,而且工件的精度質(zhì)量的也會參差不齊??偟膩碚f就是生產(chǎn)與制造離不開模具制造。
第1章 零件的結(jié)構(gòu)工藝性分
1.1零件的結(jié)構(gòu)形狀分析
該零件結(jié)構(gòu)比較簡單,中心對稱,便于加工。零件兩邊有兩個圓孔10mm,兩個圓孔之間的距離為56mm,零件寬20mm,厚度2mm。另外,根據(jù)計算孔距零件邊的距離為5mm,滿足,所以該零件符合沖裁要求。
圖1.1塑件三維圖
1.2零件的選材分析
綜合考慮之后,我認為Q235鋼是加工該零件選的較合適材料。又因為Q235鋼是常見碳素結(jié)構(gòu)鋼,擁有良好的沖裁成形性能,便于大批量生產(chǎn)并且價格實惠。所以就選擇Q235鋼作為加工該零件的材料。
1.3 零件的精度分析
零件上有3個尺寸有公差尺寸要求,mm,mm,mm根據(jù)查資料可以得到零件的尺寸要求為,所以通過一般的沖裁就會達到墊片的精度要求。
第2章 沖裁方案的確定
該零件是一種落料沖孔零件,可以有如下兩種加工方法:
方法一:首先進行沖孔,然后再落料,采用級進模進行加工;
方法二:將落料沖孔復(fù)合沖壓,采用復(fù)合模進行生產(chǎn)加工。
分析:方案一生產(chǎn)效率可以,但是與方案二比較之后就會發(fā)現(xiàn)前者的生產(chǎn)的墊的 精度沒有后者的精度高。而且方案一和方案二的生產(chǎn)效率相差并不大。換一句話說也就是方案二易加工且零件精度有一定保證,所以選用方案二來進行模具加工。
第3章 零件相應(yīng)尺寸的計算
3.1刃口尺寸計算
(1) 落料尺寸的基本計算公式
尺寸R10mm,根據(jù)資料可以查到凹、凸模的間隙分別為:mm,mm,凸凹模制造公差分別為mm,mm。又不等式成立,所以可得
=
= mm
(2)沖孔尺寸的基本計算公式
尺寸mm,根據(jù)借閱的資料可以查到零件的凹凸模制造公差為,兩者相等都是0.02mm,而且不等式成立,所以根據(jù)公式計算如下
=(10+0.75×0.18)=10.135 mm
= =10.258 mm
(3) 中心距計算
尺寸560.2mm
L=560.2/4=560.05 mm
3.2 排樣方法比較與選擇
根據(jù)墊片外形,可以通過單一直排的排樣方式來進行排樣,一種是縱向直排方法一,還有一種是橫向直排方法二,如下圖3.1。
圖3.1墊片排樣圖
通過計算和實際情況考慮決定采用方法一,方法二是細長板材易斷且不方便放置,并且通過計算以后發(fā)現(xiàn)方法二比方法一更浪費材料,所以我決定采用方法一縱向直排的排樣方法來進行排樣,如下圖3.2。
3.3 沖裁力的計算
查資料可得沖裁力計算公式如下:
墊片的具體如下圖3.2所示
圖3.2墊片排樣圖
零件的周長計算如下:
=2×56+2×3.14×10+3.14×20=237.6≈240 mm
經(jīng)過以上計算這個墊片的周長237.6mm,為了便于計算取零件周長 240mm。所加工的零件的厚度 2mm,又因為該材料抗剪強度為 350。所以沖裁力的計算如下:
=1.3×240×2×350=218.4 ≈220
、的計算如下:
==0.05×220=11
3×0.055×220=36
(為卸料力、為推件力)
所以加工零件所需的沖裁力為:
=++=267
查詢資料可以發(fā)現(xiàn)為開式壓力機的=350≥=267,
所以就選擇壓力機作為該模具的壓力機。
3.4 壓力中心的確定
由下圖3.3可知這個零件為中心對稱的圖形,零件各部分在受力方面也差不多。所以這個零件的壓力中心就是零件圖橫向、縱向?qū)ΨQ線的交點O,坐標為。
圖3.3壓力中心
第4章 沖裁設(shè)備的選用
根據(jù)前面沖裁壓力的計算可得=267,查閱資料后發(fā)現(xiàn)開式雙柱可傾式壓力機JH23-35符合條件(=350≥=267符合≥),所以就選用這個壓力機。
資料上顯示壓力機的主要參數(shù)如下:
公稱壓力: 350KN
滑塊行程: 80mm
最大閉合高度: 280mm
閉合高可度調(diào)節(jié)量: 60mm
立柱距離: 300mm
工作臺的尺寸: 380mm×610mm
墊板尺寸: 60mm×150mm
模柄孔尺寸: 50mm×70mm
滑塊底面尺寸: 190mm×210mm
第5章 模具主要零件的設(shè)計及模架的選擇
5.1 主要零件的設(shè)計
(1)落料凹模的設(shè)計
查資料可得: =0.28×77≈ 22 mm
=(1.5~2)=1.8×22≈ 40 mm
→ =77+2×40=157mm≈ 160 mm
根據(jù)上面的計算可以知道凹模尺寸為160mm×116mm×25mm,凹模具體尺寸以及結(jié)構(gòu)如下圖5.1,5.2所示。
圖5.1凹模二維圖
圖5.2凹模三維圖
(2)沖孔凸模的設(shè)計
沖孔凸模采用直筒式的結(jié)構(gòu),與凸模固定板采用的配合。凸模高度取40mm,其具體尺寸和形狀如下圖5.3所示。
圖5.3凸模
(3) 凹凸模的設(shè)計
凹凸模選擇直通式的結(jié)構(gòu),采用線切割加工方法進行加工,凹凸模外形及尺寸如下圖5.4所示。
圖5.4凹凸模
5.2 模架的選擇
根據(jù)實際情況考慮我決定選擇后置導(dǎo)柱模架來作為加工零件復(fù)合的模架,又結(jié)合前面的設(shè)計與計算,可得凹模尺寸160mm×116mm×25mm,規(guī)定模具模架選擇后置導(dǎo)柱模架,然后從相關(guān)資料中查得模架規(guī)標準如下。
上模座
下模座
導(dǎo)柱
導(dǎo)套
5.3 卸料裝置的計算及設(shè)計
(1) 卸料板的設(shè)計
卸料板的形狀和凹模形狀一樣,厚度為10mm,=160mm×116mm×10mm。
卸料板材料選擇為45鋼,調(diào)質(zhì)處理的硬度為HRC42~45,具體的形狀和尺寸如下圖5.5所示。
圖5.5卸料板
(2) 卸料螺釘?shù)倪x用及安放
由上面的圖5-5可以看出有4個螺釘,這4個螺釘就是M8的卸料螺釘。在裝配發(fā)生誤差的時候,可以通過在卸料板和螺釘之間放置墊片來進行調(diào)整它們之間的間隙。
(3) 導(dǎo)料銷的設(shè)計
在加工過程中主要靠導(dǎo)料銷來保證進料的方向,而該部件對制作材料的要求并不高,為了便于加工所以我決定直接采用圓柱型毛坯來制作導(dǎo)料銷。導(dǎo)料銷的具體形狀如下圖5.6所示 。
圖5.6導(dǎo)料銷
5.4 固定板的計算及設(shè)計
固定板分為凸凹模固定板和凸模固定板
(1)凸凹模固定板
查閱資料后結(jié)合實際情況將凸凹模固定板厚度定為25mm, 凹凸模的外形尺寸為=。凸凹模固定板具體結(jié)構(gòu)形狀與細節(jié)如下圖5.7所示。
圖5.7凸凹模固定板
(2) 凸模固定板
凸模固定板的外形尺寸為=, 查閱資料得凸模固定板厚度定為15mm,凸模固定板結(jié)構(gòu)形狀與細節(jié)如下圖5.8所示。
圖5.8凸模固定板
5.5 推件塊、推桿及打桿的設(shè)計
(1)推件塊的計算與設(shè)計
通過查閱資料推件塊計算可得推件塊大致外形尺寸為=81mm×24mm×14mm,具體結(jié)構(gòu)與細節(jié)如下圖5.9所示。
圖5.9推件塊
(2) 推桿及打桿的選擇與設(shè)計
根據(jù)模架的選擇可以得出推件塊與計算可得推桿及打桿的外形尺寸與細節(jié)如下圖
5.10,5.11。
圖5.10推桿
圖5.11打桿
5.6 卸料裝置中彈性元件的設(shè)計
結(jié)合實際情況考慮后決定選擇彈性卸料裝置作為模具的卸料設(shè)備,橡膠是彈性卸料裝置的主要材料,相應(yīng)的結(jié)構(gòu)尺寸計算如下。
(1) 計算橡膠的自由高度
=(3.5~4)
==+1+(5~10)=10 mm
(綜合考慮后,取為40mm)
(2) 計算橡膠的橫截面積
≈16400
(3) 核對橡膠平面尺寸
根據(jù)零件的尺寸與模架的結(jié)構(gòu)的一系列要求,我覺得橡膠墊中間的避讓尺寸定為80mm×22mm,根據(jù)前面的計算設(shè)計可得橡膠的外形尺寸160mm×115mm×40mm。
5.7上下模座的計算與設(shè)計
根據(jù)落料凹模的計算及設(shè)計以及所選用的后置導(dǎo)柱模架,用過前文的查資料可以得到上下模座的外形尺寸如下。
上模座
下模座
(1) 上下模座具體形狀結(jié)構(gòu)如下圖5.12,5.13,5.14,5.15所示。
圖5.12上模座二維圖
圖5.13上模座三維圖
圖5.14下模座二維圖
圖5.15下模座三維圖
第6章 復(fù)合模具裝配圖
根據(jù)前面的計算及查詢資料可以得到模具的各個零件,然后通過UG這個制圖軟件來進行裝配導(dǎo)出的復(fù)合模具裝配圖如下圖6.1,6.2。
圖6.1裝配二維圖
圖6.2裝配三維圖
結(jié)束語
在高老師的細心指導(dǎo)以及同學(xué)們的幫助下,經(jīng)過十幾天的努力這份墊片沖裁模具畢業(yè)設(shè)計終于快完成了。在這十幾天的時間里,我更加感受到了老師和身邊同學(xué)的對我的幫助,說句實話這份設(shè)計任務(wù)書不是單靠一個人就可以完成的。不僅需要查閱資料,而且需要在老師認真的指導(dǎo)和同學(xué)詳細交流討論中才可以一步步完成。時光匆匆一去不復(fù)返,眼看馬上就要離開學(xué)校出去實習(xí),心中不免感慨萬分,特別是在做這份畢業(yè)設(shè)計期間??偠灾浅8兄x老師和同學(xué)們,在這三年學(xué)習(xí)生活中對我的的悉心指導(dǎo)與幫助。
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沖壓成形與板材沖壓
1. 概述
通過模具使板材產(chǎn)生塑性變形而獲得成品零件的一次成形工藝方法叫做沖壓。由于沖壓通常在冷態(tài)下進行,因此也稱為冷沖壓。只有當板材厚度超過8~100mm時,才采用熱沖壓。沖壓加工的原材料一般為板材或帶材,故也稱板材沖壓。某些非金屬板材(如膠木板、云母片、石棉、皮革等)亦可采用沖壓成形工藝進行加工。
沖壓廣泛應(yīng)用于金屬制品各行業(yè)中,尤其在汽車、儀表、軍工、家用電器等工業(yè)中占有極其重要的地位。沖壓成形需研究工藝設(shè)備和模具三類基本問題。
? 板材沖壓具有下列特點:
(1).高的材料利用率。
(2).可加工薄壁、形狀復(fù)雜的零件。
(3).沖壓件在形狀和尺寸方面的互換性好。
(4).能獲得質(zhì)量輕而強度高、剛性好的零件。
(5).生產(chǎn)率高,操作簡單,容易實現(xiàn)機械化和自動化。
沖壓模具制作成本高,因此適合大批量生產(chǎn)。對于小批量、多品種生產(chǎn),常采用簡易沖模,同時引進沖壓加工中心等新型設(shè)備,以滿足市場求新求變的需求。板材沖壓常用的金屬材料有低碳鋼、銅、鋁、鎂合金及高塑性的合金剛等。如前所述,材料形狀有板材和帶材。
沖壓生產(chǎn)設(shè)備有剪床和沖床。剪床是用來將板材剪切成具有一定寬度的條料,以供后續(xù)沖壓工序使用,沖床可用于剪切及成形。
2. 沖壓成形的特點
生產(chǎn)時間中所采用的沖壓成形工藝方法有很多,具有多種形式餓名稱,但塑性變形本質(zhì)是相同的。沖壓成形具有如下幾個非常突出的特點。
(1).垂直于板面方向的單位面積上的壓力,其數(shù)值不大便足以在板面方向上使??板材產(chǎn)生塑性變形。由于垂直于板面方向上的單位面積上壓力的素質(zhì)遠小于板面方向上的內(nèi)應(yīng)力,所以大多數(shù)的沖壓變形都可以近似地當作平面應(yīng)力狀態(tài)來處理,使其變形力學(xué)的分析和工藝參數(shù)的計算大呢感工作都得到很大的簡化。
(2).由于沖壓成形用的板材毛胚的相對厚度很小,在壓應(yīng)力作用下的抗失穩(wěn)能力也很差,所以在沒有抗失穩(wěn)裝置(如壓邊圈等)的條件下,很難在自由狀態(tài)下順利地完成沖壓成形過程。因此,以拉應(yīng)力作用為主的伸長類沖壓成形過程多于以壓應(yīng)力作用為主的壓縮類成形過程。
(3).沖壓成形時,板材毛胚內(nèi)應(yīng)力的數(shù)值等于或小于材料的屈服應(yīng)力。在這一點上,沖壓成形與體積成形的差別很大。因此,在沖壓成形時變形區(qū)應(yīng)力狀態(tài)中的靜水壓力成分對成形極限與變形抗力的影響,已失去其在體積成形時的重要程度,有些情況下,甚至可以完全不予考慮,即使有必要考慮時,其處理方法也不相同。
(4).在沖壓成形時,模具對板材毛胚作用力所形成的約束作用較輕,不像體積成形(如模鍛)是靠與制件形狀完全相同的型腔對毛胚進行全面接觸而實現(xiàn)的強制成形。在沖壓成形中,大多數(shù)情況下,板材毛胚都有某種程度的自由度,常常是只有一個表面與模具接觸,甚至有時存在板材兩側(cè)表面都有于模具接觸的變形部分。在這種情況下,這部分毛胚的變形是靠模具對其相鄰部分施加的外力實現(xiàn)其控制作用的。例如,球面和錐面零件成形時的懸空部分和管胚端部的卷邊成形都屬這種情況。
? ?由于沖壓成形具有上述一些在變形與力學(xué)方面的特點,致使沖壓技術(shù)也形成了一些與體積成形不同的特點。由于不需要在板材毛的表面施加很大的單位壓力即可使其成形,所以在沖壓技術(shù)中關(guān)于模具強度與剛度的研究并不十分重要,相反卻發(fā)展了學(xué)多簡易模具技術(shù)。
由于相同原因,也促使靠氣體或液體壓力成形的工藝方法得以發(fā)展。因沖壓成形時的平面應(yīng)力狀態(tài)或更為單純的應(yīng)變狀態(tài)(與體積成形相比),當前對沖壓成形匯中毛胚的變形與 力能參數(shù)方面的研究較為深入,有條件運用合理的科學(xué)方法進行沖壓加工。借助于電子計算機與先進的測試手段,在對板材性能與沖壓變形參數(shù)進行實時測量與分析基礎(chǔ)上,實現(xiàn)沖壓過程智能化控制的研究工作也在開展。人們在對沖壓成形過程有離開較為深入的了解后,已經(jīng)認識到?jīng)_壓成型與原材料有十分密切的關(guān)系。所以,對板材沖壓性能即成形性與形狀穩(wěn)定性的研究,目前已成為沖壓技術(shù)的一個重要內(nèi)容。對板材沖壓性能的研究工作不僅是沖壓技術(shù)發(fā)展的需要,而且也促進了鋼鐵工業(yè)生產(chǎn)技術(shù)的發(fā)展,為其提高板材的質(zhì)量提供了一個可靠的基礎(chǔ)與依據(jù)。
3.沖壓變形的分類
? ?沖壓變形工藝可完成多種工序,其基本工序可分為分離工序和變形工序兩大類。分離工序是使胚料的一部分與另一部分相互分離的工藝方法,主要有落料、沖孔、切邊、剖切、修整等。其中又以沖孔、落料應(yīng)用最廣。變形工序是使胚料的一部分相對于另一部分產(chǎn)生位移而不破裂的工藝方法,主要有拉深、彎曲、局部成形、脹形、翻邊、縮徑、校形、旋壓等。
從本質(zhì)上看,沖壓成形就是毛胚的變形區(qū)在外力的作用下產(chǎn)生相應(yīng)的塑性變形,所以變形區(qū)內(nèi)的應(yīng)力狀態(tài)和變形特點景象的沖壓成形分類,可以把成形性質(zhì)相同的成形方法概括成同一個類型并進行體系化的研究。
絕大多數(shù)沖壓成形時毛胚變形區(qū)均處于平面應(yīng)力狀態(tài)。通常認為在板材表面上不受外力的作用,即使有外力作用,其數(shù)值也是較小的,所以可以認為垂直于板面方向上的應(yīng)力為零,使板材毛胚產(chǎn)生塑性變形的是作用于板面方向上相互的兩個主應(yīng)力。由于板厚較小,通常都近似地認為這兩個主應(yīng)力在厚度方向上是均勻分布的。基于這樣的分析,可以把各種形式?jīng)_壓成型中的毛陪變形區(qū)的受力狀態(tài)與變形特點,在平面應(yīng)力的應(yīng)力坐標系中與相應(yīng)的兩向應(yīng)變坐標系中以應(yīng)力與應(yīng)變坐標決定的位置來表示。
4.沖壓用原材料
? ?沖壓加工用原材料有很多種,它們的性能也有很大的差別,所以必須根據(jù)原材料的性能與特點,采用不同的沖壓成形方法、工藝參數(shù)和模具結(jié)構(gòu),才能達到?jīng)_壓加工的目的。由于人們對沖壓成形過程板材毛胚的變形行為有了較為深入的認識,已經(jīng)相當清楚的建立了由原材料的化學(xué)成分、組織等因素所決定的材料性能與沖壓成形之間的關(guān)系,這就使原材料生產(chǎn)部門不但按照沖壓件的工作條件與使用要求進行原材料的設(shè)計工作,而且也根據(jù)沖壓件加工過程對板材性能的要求進行新型材料的開發(fā)工作,這是沖壓技術(shù)在原材料研究方面的一個重要方向。對沖壓用原材料沖壓性能方面的研究工作有
(1)原材料沖壓性能的含義。
(2)判斷原材料沖壓性能的科學(xué)方法,確定可以確切反映材料沖壓性能的參數(shù),建立沖壓性能的參數(shù)與實際沖壓成形間的關(guān)系,以及沖壓性能參數(shù)的測試方法等。
(3)建立原材料的化學(xué)成分、組織和制造過程與沖壓性能之間的關(guān)系。沖壓用原材料主要是各種金屬與非金屬板材。金屬板材包括各種黑色技術(shù)和有色金屬板材。雖然在沖壓生產(chǎn)中所用金屬板材的種類很多,但最多的原材料蛀牙是鋼板、不銹鋼板、鋁合金板及各種復(fù)合金屬板。
5.板材沖壓性能及其鑒定方法
? ? 板材是指對沖壓加工的適應(yīng)能力。對板材沖壓性能的研究具有飛行重要的意義。為了能夠運用最科學(xué)與最經(jīng)濟合理的沖壓工藝過程與工藝參數(shù)制造出沖壓零件,必須對作為加工對象的板材的性能具有十分清楚的了解,這樣才有可能充分地利用板材在加工方面的潛在能力。另一方面,為了能夠依據(jù)沖壓件的形狀與尺寸特點及其所需的成形工藝等基本因素,正確、合理地選用板材,也必須對板材的沖壓性能有一個科學(xué)的認識與正確的判斷。評定板材沖壓性能的方法有直接試驗法與間接試驗法。
? ?實物沖壓試驗是最直接的板材沖壓性能的評定方法。利用實際生產(chǎn)設(shè)備與模具,在與生產(chǎn)完全相同的條件下進行實際沖壓零件的性能評定,當然能夠的最可靠的結(jié)果。但是,這種評定方法不具有普遍意義,不能作為行業(yè)之間的通用標準進行信息的交流。
? ?模擬試驗是把生產(chǎn)中實際存在的沖壓成形方法進行歸納與簡單化處理,消除許多過于復(fù)雜的因素,利用軸對稱的簡化了的成形方法,在保證試驗中板材的變形性質(zhì)與應(yīng)力狀態(tài)都與實際沖壓成形相同的條件下進行的沖壓性能的評定工作。為了保證模擬試驗結(jié)果的可靠性與通用性,規(guī)定了私分具體的關(guān)于試驗用工具的幾何形狀與尺寸、毛胚的尺寸、試驗條件(沖壓速度、潤滑方法、壓邊力等)。
? ?間接試驗法也叫做基礎(chǔ)試驗法。間接試驗法的特點是:在對板材在塑性變形過程中所表現(xiàn)出的基本性質(zhì)與規(guī)律進行分析與研究的基礎(chǔ)上,進一步把它和具體的沖壓成形中板材的塑性變形參數(shù)聯(lián)系起來,建立間接試驗結(jié)果(間接試驗值)與具體的沖壓成形性能(工藝參數(shù))之間的相關(guān)性。由于間接試驗時所用試件的形狀與尺寸以及加載的方式等都不同于具體的沖壓成形過程,所以它的變形性質(zhì)和應(yīng)力狀態(tài)也不同于沖壓變形。因此間接試驗所得的結(jié)果(試驗值)并不是沖壓成形的工藝參數(shù),而是可以用來表示板材沖壓性能的基礎(chǔ)性參數(shù)。
Characteristics and Sheet Metal Forming
1. The article overview
Stamping is a kind of plastic forming process in which a part is produced by means of the plastic forming the material under the action of a die. Stamping is usually carried out under cold state, so it is also called stamping. Heat stamping is used only when the blank thickness is greater than 8~100mm. The blank material for stamping is usually in the form of sheet or strip, and therefore it is also called sheet metal forming. Some non-metal sheets (such as plywood, mica sheet, asbestos, leather)can also be formed by stamping.
?? Stamping is widely used in various fields of the metalworking industry, and it plays a crucial role in the industries for manufacturing automobiles, instruments, military parts and household electrical appliances, etc.
? ?The process, equipment and die are the three foundational problems that needed to be studied in stamping.
? ?The characteristics of the sheet metal forming are as follows:
(1)? ? High material utilization
(2)? ? Capacity to produce thin-walled parts of complex shape.
(3)? ? Good interchangeability between stamping parts due to precision in shape??
and dimension.
(4)? ? Parts with lightweight, high-strength and fine rigidity can be obtained.
(5)? ? High productivity, easy to operate and to realize mechanization and? ? automatization.
? ? The manufacture of the stamping die is costly, and therefore it only fits to mass production. For the manufacture of products in small batch and rich variety, the simple stamping die and the new equipment such as a stamping machining center, are usually adopted to meet the market demands. The materials for sheet metal stamping include mild steel, copper, aluminum, magnesium alloy and high-plasticity alloy-steel, etc.??
Stamping equipment includes plate shear punching press. The former shears plate into strips with a definite width, which would be pressed later. The later can be used both in shearing and forming.
2.Characteristics of stamping forming
There are various processes of stamping forming with different working patterns and names. But these processes are similar to each other in plastic deformation. There are following conspicuous characteristics in stamping:
(1).The force per unit area perpendicular to the blank surface is not large but is enough to cause the material plastic deformation. It is much less than the inner stresses on the plate plane directions. In most cases stamping forming can be treated approximately as that of the plane stress state to simplify vastly the theoretical analysis and the calculation of the process parameters.
(2).Due to the small relative thickness, the anti-instability capability of the blank is weak under compressive stress. As a result, the stamping process is difficult to proceed successfully without using the anti-instability device (such as blank holder). Therefore the varieties of the stamping processes dominated by tensile stress are more than dominated by compressive stress.
(3).During stamping forming, the inner stress of the blank is equal to or sometimes less than the yield stress of the material. In this point, the stamping is different from the bulk forming. During stamping forming, the influence of the hydrostatic pressure of the stress state in the deformation zone to the forming limit and the deformation resistance is not so important as to the bulk forming. In some circumstances, such influence may be neglected. Even in the case when this influence should be considered, the treating method is also different from that of bulk forming.
(4).In stamping forming, the restrain action of the die to the blank is not severs as in the case of the bulk forming (such as die forging). In bulk forming, the constraint forming is proceeded by the die with exactly the same shape of the part. Whereas in stamping, in most cases, the blank has a certain degree of freedom, only one surface of the blank contacts with the die. In some extra cases, such as the forming of the blank on the deforming zone contact with the die. The deformation in these regions are caused and controlled by the die applying an external force to its adjacent area.
Due to the characteristics of stamping deformation and mechanics mentioned above, the stamping technique is different form the bulk metal forming: The importance or the strength and rigidity of the die in stamping forming is less than that in bulk forming because the blank can be formed without applying large pressure per unit area on its surface. Instead, the techniques of the simple die and the pneumatic and hydraulic forming are developed.
Due to the plane stress or simple strain state in comparison with bulk forming, more research on deformation or force and power parameters has been done. Stamping forming can be performed by more reasonable scientific methods. Based on the real time measurement and analysis on the sheet metal properties and stamping parameters, by means of computer and some modern testing apparatus, research on the intellectualized control of stamping process is also in proceeding. It is shown that there is a close relationship between stamping forming and raw material. The research on the properties of the stamping forming, that is, forming ability and shape stability, has become a key point in stamping technology development, but also enhances the manufacturing technique of iron and steel industry, and provides a reliable foundation for increasing sheet metal quality.
3.Categories of stamping forming
? ? Many deformation processes can be done by stamping, the basic processes of the stamping can be divided into two kinds: cutting and forming.Cutting is a shearing process that one part of the blank is cut from the other. It mainly includes blanking, punching, trimming, parting and shaving, where punching and blanking are the most widely used. Forming is a process that one part of the blank has some displacement from the other. It mainly includes deep drawing, bending, local forming, bulging, flanging, necking, sizing and spinning.
In substance, stamping forming is such that the plastic deformation occurs in the deformation zone of the stamping blank caused by the external force. The stress state and deformation characteristic of the deformation zone are the basic factors to decide the properties of the stamping forming. Based on the stress state and deformation characteristics of the deformation zone, the forming methods can be divided into several categories with the same forming properties and be studied systematically.
??The deformation zone in almost all types of stamping forming is in the plane stress state. Usually there is no force or only small force applied on the blank surface. When is assumed that the stress perpendicular to the blank surface equals to zero, two principal stresses perpendicular to each other and act on the blank surface produce the plastic deformation of the material. Due to the small thickness of the blank, it is assumed approximately the two principal stresses distribute uniformly along the thickness direction. Based on this analysis, the stress state and the deformation characteristics of the deformation zone in all kinds of stamping forming can be denoted by the points in the coordinates of the plane principal stresses and the coordinates of the corresponding plane principal strains.
4.Raw materials for stamping forming
There are a lot of raw materials used in stamping forming, and the properties of these materials may have large difference. The stamping forming can be succeeded only by determining the stamping method, the forming parameters and the die structures according to the properties and characteristics of the raw materials. The deformation of the blank during stamping forming has been investigated quite thoroughly. The relationships between the material properties decided by the chemistry component and structure of the material and the stamping forming has been established clearly. Not only the proper material can be selected based on the working condition and usage demand, but also the new material can be developed according to the demands of the blank properties during processing the stamping part. This is an important domain in stamping forming research. The research on the material properties for stamping forming is as follows:
(1).Definition of the stamping property of the material.
(2).Method to judge the stamping property of the material, find parameters to express the definitely material property of the stamping forming, establish the relationship between the property parameters and the practical stamping forming, and investigate the testing methods of the property parameters.
(3).Establish the relationship among the chemical component, structure, manufacturing process and stamping property.
?? The raw materials for stamping forming mainly include various metals and nonmetal plate. Sheet metal includes both ferrous and nonferrous metals. Although a lot of sheet metals are used in stamping forming, the most widely used materials are steel, stainless steel, aluminum alloy and various composite metal plates.
5.Stamping forming property of sheet metal and its assessing method
The stamping forming property of the sheet metal is the adaptation capability of the sheet metal to stamping forming. It has crucial meaning to the investigation of the stamping forming property of the sheet metal. In order to produce stamping forming parts with most scientific, economic and rational stamping forming process and forming parameters, it is necessary to understand clearly the properties of the sheet metal, so as to utilize the potential of the sheet metal fully in the production. On the other hand, to select plate material accurately and rationally in accordance with the characteristics of the shape and dimension of the stamping forming part and its forming technique is also necessary so that a scientific understanding and accurate judgment to the stamping forming properties of the sheet metal may be achieved.
There are direct and indirect testing methods to assess the stamping property of the sheet metal?.Practicality stamping test is the most direct method to assess stamping forming property of the sheet metal. This test is done exactly in the same condition as actual production by using the practical equipment and dies. Surely, this test result is most reliable. But this kind of assessing method is not comprehensively applicable, and cannot be shared as a commonly used standard between factories.
? ? The simulation test is a kind of assessing method that after simplifying and summing up actual stamping forming methods, as well as eliminating many trivial factors, the stamping properties of the sheet metal are assessed, based on simplified axial-symmetric forming method under the same deformation and stress states between the testing plate and the actual forming states. In order to guarantee the reliability and generality of simulation results, a lot of factors are regulated in detail, such as the shape and dimension of tools for test, blank dimension and testing conditions(stamping velocity, lubrication method and blank holding force, etc).???Indirect testing method is also called basic testing method its characteristic is to connect analysis and research on fundamental property and principle of the sheet metal during plastic deformation, and with the plastic deformation parameters of the sheet metal in actual stamping forming, and then to establish the relationship between the indirect testing results(indirect testing value) and the actual stamping forming property (forming parameters). Because the shape and dimension of the specimen and the loading pattern of the indirect testing are different from the actual stamping forming, the deformation characteristics and stress states of the indirect test are different from those of the actual one. So, the results obtained form the indirect test are not the stamping forming parameters, but are the fundamental parameters that can be used to represent the stamping forming property of the sheet metal.
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