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冷沖模具使用壽命的影響及對策
沖壓模具概述
沖壓模具--在冷沖壓加工中，將材料（金屬或非金屬）加工成零件（或半成品）的一種特殊工藝裝備，稱為冷沖壓模具（俗稱冷沖模）。沖壓--是在室溫下，利用安裝在壓力機上的模具對材料施加壓力，使其產(chǎn)生分離或塑性變形，從而獲得所需零件的一種壓力加工方法。
沖壓模具的形式很多，一般可按以下幾個主要特征分類：
１．根據(jù)工藝性質(zhì)分類
（1）沖裁模 沿封閉或敞開的輪廓線使材料產(chǎn)生分離的模具。如落料模、沖孔模、切斷模、切口模、切邊模、剖切模等。
（2）彎曲模 使板料毛坯或其他坯料沿著直線（彎曲線）產(chǎn)生彎曲變形，從而獲得一定角度和形狀的工件的模具。
（3）拉深模 是把板料毛坯制成開口空心件，或使空心件進一步改變形狀和尺寸的模具。
?。?）成形模 是將毛坯或半成品工件按圖凸、凹模的形狀直接復制成形，而材料本身僅產(chǎn)生局部塑性變形的模具。如脹形模、縮口模、擴口模、起伏成形模、翻邊模、整形模等。
２．根據(jù)工序組合程度分類
（1）單工序模 在壓力機的一次行程中，只完成一道沖壓工序的模具。
（2）復合模 只有一個工位，在壓力機的一次行程中，在同一工位上同時完成兩道或兩道以上沖壓工序的模具。
（3）級進模（也稱連續(xù)模） 在毛坯的送進方向上，具有兩個或更多的工位，在壓力機的一次行程中，在不同的工位上逐次完成兩道或兩道以上沖壓工序的模具。
冷沖模具主要零件
冷沖模具是沖壓加工的主要工藝裝備，沖壓制件就是靠上、下模具的相對運動來完成的。加工時由于上、下模具之間不斷地分合，如果操作工人的手指不斷進入或停留在模具閉合區(qū)，便會對其人身安全帶來嚴重威脅。
（一）模具的主要零件、作用及安全要求
1．工作零件凸凹模是直接使坯料成形的工作零件，因此，它是模具上的關(guān)鍵零件。凸凹模不但精密而且復雜，它應(yīng)滿足如下要求：
（1）應(yīng)有足夠的強度，不能在沖壓過程中斷裂或破壞．
?。?）對其材料及熱處理應(yīng)有適當要求，防止硬度太高而脆裂。
2．定位零件定位零件是確定坯件安裝位置的零件，有定位銷（板）、擋料銷（板）、導正銷、導料板、定距側(cè)刀、側(cè)壓器等。設(shè)計定位零件時應(yīng)考慮操作方便，不應(yīng)有過定位，位置要便于觀察，最好采用前推定位、外廓定位和導正銷定位等。
3．壓料、卸料及出料零件壓料零件有壓邊圈、壓料板等。
壓邊圈可對拉延坯料加壓邊力，從而防止坯料在切向壓力的作用下拱起而形成皺褶。壓料板的作用是防止坯料移動和彈跳。頂出器、卸料板的作用是便于出件和清理廢料。它們由彈簧、橡膠和設(shè)備上的氣墊推桿支撐，可上下運動，頂出件設(shè)計時應(yīng)具有足夠的頂出力，運動要有限位。卸料板應(yīng)盡量縮小閉合區(qū)域或在操作位置上銑出空手槽。暴露的卸料板的四周應(yīng)設(shè)有防護板，防止手指伸入或異物進入，外露表面棱角應(yīng)倒鈍。
4．導向零件導柱和導套是應(yīng)用最廣泛的一種導向零件。其作用是保證凸凹模在沖壓工作時有精確的配合間隙。因此，導柱、導套的間隙應(yīng)小于沖裁間隙。導柱設(shè)在下模座，要保證在沖程下死點時，導柱的上端面在上模板頂面以上最少5至10毫米。導柱應(yīng)安排在遠離模塊和壓料板的部位，使操作者的手臂不用越過導柱送取料。
5．支承及夾持零件它包括上下模板、模柄、凸凹模固定板、墊板、限位器等。
上下模板是冷沖模具的基礎(chǔ)零件，其他各種零件都分別安裝固定在上面。模板的平面尺寸，尤其是前后方向應(yīng)與制件相適應(yīng)，過大或過小均不利于操作。
有些模具（落料、沖孔類模具）為了出件方便，需在模架下設(shè)墊板。這時墊板最好與模板之間用螺釘連接在一起，兩墊板的厚度應(yīng)絕對相等。墊板的間距以能出件為準，不要太大，以免模板斷裂。
6．緊固零件它包括螺釘、螺母、彈簧、柱銷、墊圈等，一般都采用標準件。冷沖模具的標準件用量較多，設(shè)計選用時應(yīng)保證緊固和彈性頂出的需要，避免緊固件暴露在表面操作位置上，防止碰傷人手和妨礙操作。
冷沖模具的發(fā)展
改革開放以來，隨著國民經(jīng)濟的高速發(fā)展，市場對冷沖模具的需求量不斷增長。近年來，冷沖模具工業(yè)一直以15%左右的增長速度快速發(fā)展，冷沖模具工業(yè)企業(yè)的所有制成分也發(fā)生了巨大變化，除了國有專業(yè)模具廠外，集體、合資、獨資和私營也得到了快速發(fā)展。
隨著與國際接軌的腳步不斷加快，市場競爭的日益加劇，人們已經(jīng)越來越認識到產(chǎn)品質(zhì)量、成本和新產(chǎn)品的開發(fā)能力的重要性。而冷沖模具制造是整個鏈條中最基礎(chǔ)的要素之一，冷沖模具制造技術(shù)現(xiàn)已成為衡量一個國家制造業(yè)水平高低的重要標志，并在很大程度上決定企業(yè)的生存空間。
近年許多冷沖模具企業(yè)加大了用于技術(shù)進步的投資力度，將技術(shù)進步視為企業(yè)發(fā)展的重要動力。一些國內(nèi)模具企業(yè)已普及了二維CAD，并陸續(xù)開始使用UG、Pro/Engineer、I-DEAS、Euclid-IS等國際通用軟件，個別廠家還引進了Moldflow、C-Flow、DYNAFORM、Optris和MAGMASOFT等CAE軟件，并成功應(yīng)用于沖壓模的設(shè)計中。
以汽車覆蓋件模具為代表的大型沖壓模具的制造技術(shù)已取得很大進步，東風汽車公司模具廠、一汽模具中心等模具廠家已能生產(chǎn)部分轎車覆蓋件模具。此外，許多研究機構(gòu)和大專院校開展模具技術(shù)的研究和開發(fā)。經(jīng)過多年的努力，在模具CAD/CAE/CAM技術(shù)方面取得了顯著進步；在提高模具質(zhì)量和縮短模具設(shè)計制造周期等方面做出了貢獻。
雖然中國冷沖模具工業(yè)在過去十多年中取得了令人矚目的發(fā)展，但許多方面與工業(yè)發(fā)達國家相比仍有較大的差距。例如，精密加工設(shè)備在冷沖模具加工設(shè)備中的比重比較低；CAD/CAE/CAM技術(shù)的普及率不高；許多先進的模具技術(shù)應(yīng)用不夠廣泛等等，致使相當一部分大型、精密、復雜和長壽命冷沖模具依賴進口。
隨著科學技術(shù)的不斷進步,現(xiàn)代工業(yè)產(chǎn)品的生產(chǎn)日益復雜與多樣化,產(chǎn)品性能和質(zhì)量也在不斷提高,因而對冷沖壓技術(shù)提出了更高的要求.為了使冷沖壓技術(shù)能適應(yīng)各工業(yè)部門的需要,冷沖壓技術(shù)自身也在不斷革新和發(fā)展.冷沖壓技術(shù)的發(fā)展思路就是盡可能地完善和擴充冷沖壓工藝的優(yōu)點,克服其缺點.在冷沖壓技術(shù)的發(fā)展過程中,應(yīng)注意以下幾方面：
(1)冷沖壓技術(shù)的發(fā)展過程中應(yīng)正確地確定工藝參數(shù)及冷沖模具工作部分的形狀與尺寸,提高沖壓件的質(zhì)量、縮短新產(chǎn)品試制周期,應(yīng)在加強沖壓成形理論研究的基礎(chǔ)上,使沖壓成形理論達到能對生產(chǎn)實際起指導作用,逐步建立起一套密切結(jié)合生產(chǎn)實際的先進的工藝分析計算方法.國外已開始采用彈塑性有限元法對汽車覆蓋零件的成形過程進行應(yīng)力應(yīng)變分析和計算機模擬,以預測某一工藝方案對零件成形的可能性和可能出現(xiàn)的問題。
(2)加快產(chǎn)品更新?lián)Q代,克服模具設(shè)計周期長的缺點.應(yīng)大力開展模具計算機輔助設(shè)計和制造(CAD/CAM)技術(shù)的研究.在我國,目前要特別注意加強多工位級進模CAD/CAM技術(shù)的研究。
(3)滿足大量生產(chǎn)需要以及減輕勞動強度.應(yīng)加強冷沖壓生產(chǎn)的機械化和自動化研究,使一般中、小件能在高速壓力機上采用多工位級進模生產(chǎn),達到生產(chǎn)高度自動化,進一步提高沖壓的生產(chǎn)率。
(4)擴大冷沖壓生產(chǎn)的運用范圍.使冷沖壓既適合大量生產(chǎn),也適合小批量生產(chǎn);既能生產(chǎn)一般精度的產(chǎn)品,也能生產(chǎn)精密零件.應(yīng)注意開發(fā)如精密沖裁(特別是厚料精沖)、高能成形、軟模成形、施壓和超塑性加工等新成形工藝,還要推廣簡易模(軟模和低熔點合金模)、通用組合模、數(shù)控沖床等設(shè)備的運用。
此外,對沖壓板料性能的改進,模具新材料、模具新加工方法的開發(fā)也應(yīng)進一步加強。
冷沖模具使用壽命的影響及對策
冷沖模具的使用壽命是以沖制出的工件數(shù)量來計算的。影響冷沖模壽命的因素很多。主要有模具結(jié)構(gòu)設(shè)計、制造模具所用凸模和凹模的材料、模具的熱處理質(zhì)量與表面強化、沖模零件的制造精度和冷沖壓材料的選取。除此之外，還有沖模的安裝、調(diào)整、使用以及維修等。
1．模具設(shè)計對壽命的影響
(1)排樣設(shè)計的影響排樣方法與搭邊值對模具壽命的影響很大，過小的搭邊值，往往是造成模具急劇磨損和凸、凹?？袀闹匾?。從節(jié)約材料出發(fā)，搭邊值愈小愈好，但搭邊值小于一定數(shù)值后，對模具壽命和剪切表面質(zhì)量不利。在沖裁中有可能被拉人模具問隙中，使零件產(chǎn)生毛刺，甚至損壞模具刃口，降低模具壽命。因此，在考慮提高材料利用率的同時，必須根據(jù)零件產(chǎn)量、質(zhì)量和壽命，確定排樣方法和搭邊值。
(2)凹模結(jié)構(gòu)的影響對容易產(chǎn)生應(yīng)力集中而開裂的凹模結(jié)構(gòu)，可以采用組合結(jié)構(gòu)或鑲拼結(jié)構(gòu)，以及預應(yīng)力結(jié)構(gòu)，從而提高模具使用壽命。
(3)間隙的影響當間隙過小時，壓縮擠壓利害，摩擦力增大，磨損增大，側(cè)面的磨損加劇，沖裁后卸料和推件時，材料與凸、凹模之間的摩擦還將造成刃口側(cè)面的磨損比端面的磨大大，同時也容易造成凸、凹模溫度很高，把金屬碎屑吸附在刃口側(cè)面，形成金屬瘤，使凸、凹模出現(xiàn)崩刃或脹裂現(xiàn)象。因此，過小的間隙對模具壽命極為不利。間隙太大，會增加凸模與凹模端面邊緣的集中應(yīng)力，致使壓應(yīng)力急劇增加，于是刃口邊很快屈服變形而失去棱角。因此又增加了沖裁力，進而使刃口邊更快磨損，降低模具壽命。但為了減小凸、凹模的磨損，延長模具使用壽命，在保證沖裁件質(zhì)量的前提下，設(shè)計時適當采用較大間隙是十分必要的。
(4)模具導向結(jié)構(gòu)對壽命的影響可靠的導向?qū)τ跍p小工作零件的磨損，避免凸、凹?？袀欠浅Ｓ行У?。特別對無問隙或小問隙沖裁模、復合模和多工位級進模更為重要。為提高模具壽命，必須根據(jù)工序和零件精度要求，正確選擇導向形式和導向精度，所選擇導向精度應(yīng)高于凸、凹模的配合精度。
(5)冷沖壓材料選取的影響冷沖壓材料應(yīng)滿足制件的設(shè)計要求和沖壓工藝要求，否則容易損傷模具，降低模具使用壽命。冷沖壓材料表面質(zhì)量不好，沖壓時制件易破裂，也易擦傷模具。冷沖壓材料塑性不好，變形量小，沖壓時制件易破裂，也易擦傷模具。另外，材料的厚度公差應(yīng)符合國家標準。因為一副沖模適用于一定材料的厚度，成形、彎曲、翻邊、引伸模具的凸、凹模結(jié)構(gòu)間隙是直接根據(jù)材料厚度來確定的。所以材料厚度不均勻，會導致廢品產(chǎn)生和模具損壞。
2．模具材料對模具壽命的影響
模具材料對模具壽命的影響是模具材料性質(zhì)、化學成分、組織結(jié)構(gòu)、硬度和冶金質(zhì)量等的綜合反映。其中，材料性質(zhì)和熱處理質(zhì)量影響最為明顯。模具材料性質(zhì)對模具壽命的影響是很大的。如將同一種工件，使用不同的模具材料做彎曲試驗，試驗結(jié)果：用9Mn2V材料，其壽命為5萬次；用Crl2MoV滲氮，其壽命可達40萬次。因此，在選用材料時，應(yīng)根據(jù)制件的批量大小，合理選用模具材料。模具工作零件的硬度對模具壽命的影響也很大。但并不是硬度愈高、模具壽命愈長。這是因為硬度與強度、韌性及耐磨性等有密切的關(guān)系。有的沖模要求硬度高，壽命長。如采用T10鋼制造沖模，硬度為54～58HRC，只沖幾千次，制件毛刺就很大。如果將硬度提高到60～64HRC，則刃磨壽命可達2～3萬次。但如果繼續(xù)提高硬度，則會出現(xiàn)早期斷裂。有的沖模硬度不宜過高，如采用Crl2MoV制造凹模硬度為58～62HRC時，一般壽命為2—3萬件，失效形式是崩刃和開裂以及如果將硬度降到54～58HRC，壽命提高到5～6萬件，但硬度降低到50～53HRC會出現(xiàn)凹模刃口易磨鈍現(xiàn)象。由此可見，模具硬度必須根據(jù)材料性質(zhì)和失效形式而定。應(yīng)使硬度、強度、韌性及耐磨性、耐疲勞強度等達到特定沖壓工序所需要的最佳配合。
3．模具的熱處理質(zhì)量與表面強化對壽命的影響
模具的熱處理質(zhì)量對模具的性質(zhì)與使用壽命影響很大。實踐證明，模具工作零件的淬火變形與開裂，使用過程中早期斷裂，雖然與材料的冶金質(zhì)量、鍛造質(zhì)量、模具結(jié)構(gòu)及加工有關(guān)，但與模具的熱處理關(guān)系更大。根據(jù)模具失效原因的分析統(tǒng)計，熱處理不當引起的失效占50％ 以上。實踐證明，高級的模具材料必須配以正確的熱處理工藝，才能真正發(fā)揮材料的潛力。模具工作零件表面強化處理的目的，是獲得外硬內(nèi)韌的效果，從而得到硬度、耐磨性、韌性、耐疲勞強度的良好配合。模具表面強化處理方法很多，表面處理的新技術(shù)工藝發(fā)展很快。除氮碳共滲和離子氮化、滲硼、滲鈮、滲釩、表面鍍硬鉻和電火花強化外，化學氣相沉積(CVD)和物理氣相沉積(PVD)已逐步采用。經(jīng)CVD和PVD處理后，模具表面覆蓋一層超硬物質(zhì)，如TiC、TiN等。硬度極高、耐磨性、耐蝕性、抗黏合性很好，可提高模具壽命幾倍到幾十倍。
4．沖模零件的制造精度對模具壽命的影響
沖模制造的精度與使用壽命關(guān)系很大，特別是模具表面粗糙度對模具影響很大。如用Crl2MoV鋼制造落料模，如果表面粗糙度值R =1．6 m時，其壽命為3萬件左右。如經(jīng)精拋光，表面粗糙度值R =0．4 m，壽命可提高到4—5萬件。因此，對模具工作零件表面，一般都要經(jīng)過磨削、研磨、拋光等精加工和精細加工。
5．其他方面對模具壽命的影響
(1)壓力機的精度不高，也易使沖模損壞。
(2)沖模在壓力機上安裝的正確與否及操作者的技術(shù)水平高低，對模具壽命也有很大影響。
(3)沖模的保管和維護好壞，以及使用潤滑劑的情況，也影響模具使用壽命。
6．結(jié)語
在實際生產(chǎn)中，對于薄板沖模使用，很少出現(xiàn)非正常磨損的情況。但對于厚板沖模時則發(fā)現(xiàn)易出現(xiàn)非正常磨損，我們總是針對出現(xiàn)的問題進行研究總結(jié)。因為一副冷沖模，從設(shè)計、加工制造、裝配、調(diào)試到安裝、使用，都耗費了眾多工時，同時沖模的凸、凹模使用的材料，大都是優(yōu)質(zhì)合金鋼。因此，沖模的成本都是比較高的。所以在生產(chǎn)中了解影響沖模壽命的因素及采取相應(yīng)的對策來指導生產(chǎn)，具有重大的現(xiàn)實意義。
Die Life of cold stamping die and improvements
Overview of stamping die
Stamping Die - Stamping in the cold, the material (metal or non-metallic) processing into parts (or half) of a special technical equipment, called cold stamping die (commonly known as Die). Press - is at room temperature, using the die installed in the press to put pressure on the material to produce a separation or plastic deformation, and thus to obtain the necessary parts of a pressure processing method.
Stamping die in the form of many, the general categories according to the following main features:
1. According to the technical nature of
(1) Die along the closed or open contour the material are derived from mold. If blanking die, punch die, cut off the mold, cut mode, cutting mode, split mode, etc..
(2) bending mode to blank or blank sheet along a straight line (curved line) to bend, deform, and thus obtain a certain angle and shape of the workpiece in the mold.
(3) The drawing die is made of the blank sheet opening hollow, or hollow pieces of further changes to the shape and size of the mold.
(4) Die rough or semi-finished workpiece is convex according to plan, direct copy the shape of the die shape, the material itself, generate only local plastic deformation of the mold. Such as the bulging mode, reducing the die, expansion die, forming die rolling, flanging mold, plastic mold.
2. According to the degree classification process combination
(1) single process model in a press tour, just completed a die stamping process.
(2) composite model is only one station, in a press tour, at the same station at the same time to complete more than two or two die stamping process.
(3) Progressive Die (also known as the modulus of continuity) in the feeding direction, rough, with two or more of the station, at the press of a visit, work in different places on the completion of two or two successive Road over stamping die process.
Die with the main parts
Die stamping tools is the main process equipment, stamping rely on the relative movement under the mold completed. Processing time because the upper and lower mold between the constant division and, if continued operation of the fingers of workers to enter or remain in the mold closed, there will certainly pose a serious threat to their personal safety.
(A) of the mold main parts, function and safety requirements
1. Working parts is a direct punch to blank forming the working parts, therefore, it is the key to mold parts. Punch not only sophisticated and complex, it should meet the following requirements:
(1) be of sufficient strength, can not be broken or destroyed during stamping.
(2) should be appropriate to its material and heat treatment requirements, to prevent too high hardness and brittle fracture.
2. Positioning parts positioning part is to determine the location of the parts installed blank, there are pins (board), gauge pin (plate), lead is sold, guide plate, knife set from the side, side pressure etc.. Design should be considered when positioning parts easy to operate and should not have had orientation, location to facilitate observation, preferably in the forward position, contouring to correct the pin location and positioning.
3. Binder, unloading and discharging parts binder components are blank holder, binder board.
Blank holder pressure can drawing blank holder force, thereby preventing billets under the action of the tangential pressure arch formed folds. The role of pressure plate to prevent movement and bounce blank. Top of the device, discharge board's role is to facilitate the pieces and clean up waste. Them by the spring, rubber and equipment, putting on the air-cushion support, can move up and down, knocking out pieces of the design should have enough top output, movement to the limited spaces. Stripper plate area should be minimized or closed position in the operating groove milling out empty-handed. Exposure of the stripper plate should have protection around the plate, to prevent finger inserted into or foreign objects inside, exposed surface edges should be blunt down.
4. Guide parts and guide sleeve guide pin is the most widely used part of a guide. Its role is to ensure punch the punching clearance when accurate match. Therefore, the guide posts, guide cover the gap should be less than the blanking clearance. Guide Post located next mold base, to ensure that the stroke bottom dead center, the lead column in the template on the face over the top for at least 5 to 10 mm. Guide columns should be arranged far away from the module and the pressure plate in the area, so the operator's arms do not get to take over the lead column material.
5. Supporting and clamping the upper and lower parts which includes templates, die handle, fixed plate punch, plate, stopper, etc..
Up and down the template is the basis of the cold die parts, other parts are respectively fixed at the top. Template plane size, especially around the direction to be compatible with the workpiece, too large or too small are not conducive to action.
Some molds (blanking, punching type mold) to the pieces of convenience, be set up under the mold plate. At this time the best and the template plate connected between the screw, the two plate thickness should be absolutely equal. Plate spacing out the pieces to be able to prevail, not too much, so as not to break the template.
6. Fastening parts which includes screws, nuts, springs, pins, washers, etc., are generally used standard parts. Die more with the amount of standard parts, design choice and flexibility should be tightened to ensure the top out of the need to avoid exposure to the surface fastener operating position, the staff and impede operation to prevent bumps.
Die with the development of
` Since reform and opening, with the rapid development of the national economy, the market demand with the growing Die. In recent years, Die with the industry has been around 15% growth rate of the rapid development of industrial enterprises with ownership Die components also changed dramatically, in addition to the professional mold factory outside of state-owned, collective, joint ventures, wholly-owned and private has been a rapid development.
As with the accelerating pace of international integration, the increasing competition in the market, it has been increasingly recognized product quality, cost, and new product development capacities. The cold die manufacturing is the most basic elements of the chain, one of the cold die manufacturing technology to measure a country's manufacturing sector has become an important symbol of the level, and largely determine the viability of enterprises.
Die with enterprises to increase in recent years many technological advances for investment, technological progress will be seen as an important driving force for enterprise development. Some domestic enterprises have popularized the two-dimensional mold CAD, and gradually began to use UG, Pro / Engineer, I-DEAS, Euclid-IS and other international common software, individual manufacturers have also introduced Moldflow, C-Flow, DYNAFORM, Optris and MAGMASOFT etc. CAE software, and successfully applied in stamping die design.
A car cover mold as the representative of a large stamping die manufacturing technology has made great progress, Dongfeng Motor Corporation mold factory, mold manufacturers such as FAW mold center has been able to produce some car cover mold. In addition, many research institutions and universities to carry out technology research and development of mold. After years of effort, in the mold CAD / CAE / CAM technology has made remarkable progress; in improving quality and reducing mold die design and manufacturing cycle, and so contributed.
Although China Die with the industry over the past decade has made remarkable development, but in many ways compared with the industrialized countries there is still a large gap. For example, the precision machining equipment, processing equipment in Die with the relatively low proportion; CAD / CAE / CAM technology penetration is not high; many advanced mold technology not widely so, resulting in a considerable number of large, sophisticated, complex and long Die life with dependence on imports.
????With the continuous progress of science and technology, modern industrial production of increasingly complex and diverse, product performance and quality is ever increasing, thus the cold stamping technology put forward higher requirements. In order to adapt to the cold stamping technology industry needs, cold stamping technology itself also in innovation and development. cold stamping technology idea is to improve and expand as much as possible the advantages of the cold stamping process, to overcome its shortcomings. in the cold stamping technology development, should note the following aspects:
(1) cold stamping technology process parameters should be properly identified and Die with the work of some of the shape and size, to improve the quality of stamping parts and shorten the new product production cycle should be in strengthening the metal forming the basis of theoretical studies, to metal forming theory to practice can produce a direction, and gradually establish a close connection with the actual production of the advanced process of calculation. abroad have begun to use plastic finite element method, automobile parts forming process of the stress and strain analysis and computer simulation to predict the forming part of a process plan on the possibilities and potential problems.
(2) to accelerate product replacement, mold design to overcome the shortcomings of a long cycle. Should vigorously carry out computer-aided design and manufacture of molds (CAD / CAM) Research. In my country, paying particular attention to strengthening the multi-position progressive die CAD / CAM Technology.
(3) to meet the needs of mass production, and reduce labor intensity. Should strengthen cold stamping of mechanized and automated, so that the average, small pieces of high-speed presses in a multi-position progressive die production, production reached a high degree of automation to further improve stamping productivity.
(4) expand the scope of application of cold stamping production. So cold pressing both suitable for mass production, but also for small batch production; both the general accuracy of product production, but also can produce precision parts. Should pay attention to development such as fine blanking (especially thick material fine blanking), forming high-energy, soft mold forming, pressure and processing new superplastic forming process, but also promote the easy mode (soft mode and the low melting point alloy mold), Universal Hybrid model, the use of CNC punch press and other equipment.
In addition, the performance improvement of sheet metal stamping, mold new material, die development of new processing methods should be further strengthened.
Die with life and Countermeasures
Die with the life of the workpiece by punching out the number of terms. Many factors affect the life Die. There are die structure design, manufacture molds used in the punch and die materials, die quality and surface hardening heat treatment, precision die manufacturing parts and cold stamping materials selection. In addition, there are die installation, adjustment, use and maintenance.
1. Die Design on Life
(1) Layout design of layout methods and take the boundary value a great impact on the die life, too small to take the boundary value, often causing rapid wear and convex mold, die bite wounds on the. Starting from material savings, take the boundary value smaller the better, but take the edge is less than some value, the cut surface of the mold and the quality of life adversely. There will be left behind in the blanking die Q-gap were to produce spare parts glitch, or even damage the die edge, reduce die life. Therefore, consider increasing the material utilization of the same time, parts must yield, quality and life expectancy to determine the layout methods and take the boundary.
(2) die structure prone to stress concentration on the cracking of the die structure, composite structure can be used or mosaic structure, and prestressed structure to enhance the mold life.
(3) the impact of clearance when the gap is too small, compressed extrusion of interest, increased friction, increased wear, the wear side of aggravated discharge and push pieces after blanking time, materials and convex, the friction between die will cause wear and tear than the end edge on the side of the grinding much, but also easily lead to convex, concave mold temperature is high, the adsorption of metal debris in the side edge to form a metal tumor, so that male and female die chipping or expansion occurs crack phenomenon. Therefore, the gap is too small to Die Life very bad. Gap is too large will increase the punch and the die face the edge of the concentration of stress, resulting in a sharp increase in stress, so blade edge quickly lose angular yield deformation. Therefore, addition of blanking force, thereby enabling faster edge edge wear, reduce die life. But in order to reduce the male and female die wear, extending mold life, while ensuring quality of stamping pieces under the premise that larger space designed properly it is necessary.
(4) Die-oriented structure of the life of a reliable guide for the working parts reduce wear, prevent male and female die bite wound is very effective. In particular, non-small-Q gap Q gap or Die, compound die and multi-position progressive die even more important. To improve the die life, must be based on processes and the demand of precision, the correct choice-oriented form and orientation accuracy, the choice should be higher than the accuracy-oriented convex, concave mold with precision.
(5) the impact of cold stamping materials, cold stamping materials selected should meet the design requirements of workpieces and stamping process requirements, or easy to mold damage and reduce mold life. Poor surface quality of cold stamping, punching, cracking when the workpiece is also easy to scratch mold. Bad cold stamping plastic materials,