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Domestic and foreign car coverage Die Design Overview
A.S. Pouzada, E.C. Ferreira and A.J. Pontes
Abstract : In introducing the current domestic car stamping die design and manufacture of the foundation, expounded foreign auto company cars panel particular panel of the stamping process and die design status application of new technologies .
Key words : mechanical manufacturing; Car panel; Stamping technology; Mold Design
1 Introduction
In recent years, China's car market has developed very rapidly in 2002 in car sales more than one million on the basis of in 2003 to 2 million people relations forward, reaching 1.97 million. However, in the car heat rapidly warming, had to face the embarrassment of this reality-market best-selling vehicle for the majority of people must be directly imported from abroad. As domestic car cover mold design and manufacturing capability on the whole is relatively weak, in order to produce these models, each company had to spend hundreds of millions or hundreds of billion of overseas procurement die. People with foreign automobile companies, because the relatively small scale of production, This has resulted in motorcycle smoothing wood into the mold much higher than foreign cars, This is also produced cars along with high wood manufacturing into one of the main reasons.
2 Domestic car coverage Die development capability
Major car manufacturers to Die : Die Manufacturing Co. Ltd. of FAW, Dongfeng Motor Die Works, Tianjin Automobile Die Company, CAC Integration Technology Co., Ltd Nanjing mold equipment, Shanghai Auto Body 1000 margin Die Company. Most people as a domestic car production and sales of commercial-vehicle population of Shanghai Limited, also has its own mold design and manufacturing departments ((TMM Division). Currently, Although domestic Die in Car cover the mold design and manufacturing has a small capacity, auto plants can undertake some development projects die, but for a very high surface accuracy and surface quality requirements of the outside panel. It is especially the high-grade cars outside panel, auto plants rarely die by the will of such domestic development.
Shanghai Public Motors Limited in order to reduce vehicle production costs, but also to increase the company's core technical competencies, Since the beginning of 2001, set foot in the car stamping die design and manufacturing fields. 2001 -2002 completed POLO cars manually presses the production line 10 Die simple parts , the company's quality assurance department as well and put into production. Beginning in 2002, the type of people to the complex, automation, 6000kN the design and manufacture of automatic production line POLO cars tyres. Die Block (dimensions of the parts, deep drawing deep, complex shape) in 2003, in order to further enhance the design and manufacture of mold ability and level We get involved in the Multi-Position 20000kN Press and 10000kN automatic production line of die design. Shanghai over the past number of people in many public spaces 20000kN Press on the use of the mold, all u need to progress, Die domestic business still lacks the ability to design and manufacture the mold. To this end, we chose POLO Car column plate mold design. 20000kN Multi-Position Press is the world's most advanced presses, integration, a very high degree of automation. Of course, this right mold design requirements also increased accordingly. Parts Feeding height, distance, location manipulator strict requirements ensure that the manipulator in the course of the campaign and die without interference, so the mold design for space on a small lot. In considering many factors, we finally completed the whole mold design, CAD state assembly as shown in figure 1. In addition, we have completed the POLO cars 10000kN automatic production line of the rear wheel cover mold design, In last year's build on that. These successful completion of the Shanghai marks the number of people die design capability has reached advanced domestic level. thus for the future of Shanghai people die Domestic car lay a solid foundation. Nevertheless, with the international advanced level, the more people there are still gaps, For example, in the car outside cover mold design or from the air.
Die in Car, the most difficult of the outer covering die design, mainly in the following two aspects :
(1)Overcome by the resilience of parts surface deviations
Breakdown, wrinkling, Rebound car is stamping process of forming the main shortcomings, as car outside panel dimensions. deep drawing shallow, plastic deformation low level generally will not crack, Resilience as a result of such parts on the manufacturing process and the main problems, it will seriously affect the parts with the mutual relations. Finite element simulation software in the stamping die design universal application, has been able to accurately predict rupture and wrinkle-free. thus contribute to the design of appropriate auxiliary surfaces to improve the process of drawing materials flow, improve parts forming ft. However, to date) unknown. Most of the finite element software can not be accurately forecast Stamping Die them removed from the rebound after deformation. Therefore, the external panel dealing with the resilience of the major changes to rely on the experience of the die face, stamping parts are forming over, to offset rebound led to the deformation.
(2)Stamping the pick-up
As foreign coverage (eg front cover plate, the roof and fender panels) are subject to complex flanging plastic or anticipated beading crafts, This makes the design of the mold structure, we must consider the ram after forming the pick-up, the current people are relying on more complex Wedge institutional linkages to achieve some of the work to mold parts his resignation to achieve to enable them to pieces. The resulting mold of the entire structure is very complicated.
3 Foreign coverage Die Design
Currently, foreigners Motors Corporation in order to reduce mold development and manufacturing costs, shorten production cycles, In addition to cars outside panel of people out of the car Stamping Die Mold were left to professional companies (such as Fontana Pietro.Kuka.Laepple.Schuler Cartec.Ogi-ha la-Fuji Techniaca etc.) to design and manufacture, these companies have strong development capabilities, and in some parts of the manufacturing mold with unique advantages. But as auto plants, taking into account the development of new models in the process of confidentiality, such as the right-wing boards, suitcase covers, doors, side-Wai, the roof front cover and other sensitive parts of the die, die by their own manufacturing sector to design and manufacture.
3.1 Software Environment
Stamping die design, in addition to the need for CAD software, also large-scale application of the finite element simulation software If AutoForm.PamStamp. DynaForm. Indeed, aided design stamping process. Below, AutoForm as an example to show how the use of CAE software design process of drawing surfaces.
AutoForm is supplied by the Swiss Development professional rapid simulation of sheet metal forming software can be used in sheet, welded plate stamping, such as Hydroforming process simulation, with different functional modules, can also be used for single-step stamping parts and the simulation of forming processes of drawing surfaces ((Addendum) Design . Car stampings, About two-thirds of the use of AutoForm Diedesigner Module Module Design A ddendum the module under specified by the designer or by the software automatically generate pressure-ring face and and the process of multi-added section of the line (Profile), to produce rapid-added process, Drawing for the simulation process, as shown in Figure 2. V-ring face and Profile parameter can be the adjustment. This rapid design is based on surface Addendum Construction of the rough, curved surface film itself, and between the curved surface of the film is not very continuous fairing, Despite this surface is not used directly to the mold surface machining. But the simulation accuracy is not affected people. According to the simulation results. designers can easily add-on technology adjustment until simulation results meet design requirements. Finally, will Blankholder circle Profile Addendum to surface and neutral data format output IGS or VDA, CAD software for surface reconstruction and digital-analog integrated products, will be able to be machined can use the drawing process a few Die Mold.
Stamping Process traditional design methods : First, on the basis of experience, the use of CAD technology to add noodles. Secondly, CAD will be transmitted to the model number of AutoForm software such as CAE deep drawing process simulation; According to the simulation results. in CAD add-on process adjustments and a few new CAD - CAE pass to start new simulation, Until meet the requirements for competition. This is one from CAD to CAE to return to the CAD kept in the process. Because each of the CAD surface structure than in AutoForm are complex, therefore, The whole process will have to spend much more time. And the new method of stamping process in the design stage, Diedesigner Module used in AutoForm software design and adjust the deep drawing process surfaces with the traditional design methods, we will be able to greatly improve the efficiency of design.
A AutoForm is due to the rapid simulation software in a relatively short time stamping parts of the complicated process of forming the evaluation of membrane modules used to model discrete geometry, bound to reduce the simulation accuracy, therefore, Some car companies prior to the start of mold design will use high-precision simulation of the CAE software, Germany on the number of people using the software Indeed, Drawing on procedures for the simulation again ((Indeed calculation software is based on the thickness of the shell element. to be more accurate results, However, the calculation of time spent AutoForm is usually several times that of the 10, The software is applicable to the ultimate test), Drawing all must pass Indeed Process simulation and validation to be feasible, in order for mold design.
Mold design complete, the combination of drawings through the bubble acceptance model (Figure 3) different procedures with different colors of the lines marking the bubble model, the so intuitive and clear. Technology should also be organized, including designers, project planning, mold testing, Die operators and other stakeholders to discuss acceptance. For the stamping process difficult to solve the problem of forming, product development should also be invited to discuss personnel, look for changes in product design possibilities.
3.2 Rebound amendment response
The former is known, the rebound was cars outside panel forming process of the main questions are covered plate before example, conduct detailed analysis.
① Usually panel of the rebound following two categories :
Large flat surface caused by the elastic response of buckling or collapse, as illustrated in figure 4, Part C Click below, dotted said parts removed from the mold and rebound occurred after the position. In such cases, the design process is not normally be considered. Technology products in a few die-face with some of the data from the product development departments of consistent data, and for die manufacturing. To tryout, and the specimens were seized compared with measurements, according to the deviation of drawing surface model amendment. If designers to control such problems have very rich experience, can be estimated in advance surface elastic recovery and the direction of offset, and will reverse its superposition of several product-development, Rebound consider seeking deformation of the surface of deep drawing process, the calculation process requires specialized computer software to accomplish, In Germany public, using the ICEM.
② Flanging plastic part by bending the rebound fold angle changes, as illustrated in figure 4 B Click below. For this kind of problem, in addition to the Department of Drawing and cutting edge, but also including flanging and Wedge plastic, plastic take-off process is forming 2 -3, to offset the springback. The process design work completed and reflected in the number of program modules.
3．3 Wedge new outer body mold coverage on the application
Currently, many of the new models outside panel, fender panels (Figure 5) front cover plate, the roof flanging plastic processes, used as a "revolving Wedge," new technology. The working principle see figure 6, rotating Wedge part of the cavity is required plastic stamping parts of the region, when the plastic process is complete, Cylinder - driven carriers to promote Wedge around rotating drum rotation, so as to achieve the purpose of the yield components, After the convenience of plastic parts, removed from the mold. Rotating Wedge's advantages are : plastic parts for stamping parts and materials entrusted part of the mosaic is very fairing, Therefore, there is no obvious parts indentation; Die simple structure; maintenance is simple and low cost.
4 Concluding remarks
In recent years, through the tireless efforts and the car stamping die design and manufacturing capabilities made significant progress. However, the car is especially luxury cars outside the coverage of mold development, the international level and there are still more people gap. However, this gap is not narrowing, So long as we strengthen international exchanges and learn from their foreign counterparts in designing and manufacturing experience, car will be able to accelerate the coverage Die domestic process.
References
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國內(nèi)外轎車覆蓋件模具設(shè)計概況
A.S. Pouzada, E.C. Ferreira and A.J. Pontes
摘要: 在介紹目前國內(nèi)轎車沖壓模具設(shè)計制造情況的基礎(chǔ)上，闡述了國外汽車公司轎車覆蓋件特別是外覆蓋件的沖壓工藝設(shè)計現(xiàn)狀及模具新技術(shù)應(yīng)用情況。
關(guān)鍵詞: 機(jī)械制造;轎車覆蓋件;沖壓工藝;模具設(shè)計
1前言
近幾年來，我國轎車市場發(fā)展十分迅猛，2002年在轎車銷售超過100萬輛的基礎(chǔ)上，2003年則向200萬輛大關(guān)邁進(jìn)，達(dá)到了197萬輛。然而，在轎車熱迅速升溫的同時，不得不尷尬地面對這樣的現(xiàn)實—市場上熱銷的絕大多數(shù)車型是直接從國外引進(jìn)的。由于國內(nèi)轎車覆蓋件模具設(shè)計制造能力從總體上看還比較薄弱，為了生產(chǎn)這些車型，各大汽車公司不得不耗資幾億、十幾億元采購海外模具。與國外大汽車公司相比，由于生產(chǎn)規(guī)模比較小，這就造成單車均攤的模具成本遠(yuǎn)高于國外車，這也是造成國產(chǎn)車整車制造成木居高不下的主要原因之一。
2 國產(chǎn)轎車覆蓋件模具開發(fā)能力
國內(nèi)主要的轎車模具制造商有:一汽模具制造有限公司、東風(fēng)汽車模具廠、天津汽車模具有限公司、成飛集成科技股份有限公司、南京模具裝備有限公司、上海千緣汽車車身模具有限公司等等。作為國內(nèi)最大轎車生產(chǎn)銷售商—上海大眾汽車有限公司，也有自己的模具設(shè)計制造部門((TMM部)。目前，雖然國內(nèi)模具商在轎車內(nèi)覆蓋件模具設(shè)計制造方面已小有能力，并可承接整車廠的部分模具開發(fā)項目，但對于有很高型面精度和表面質(zhì)量要求的外覆蓋件，特別是中高檔轎車的外覆蓋件，整車廠很少會將這類模具交由國內(nèi)開發(fā)。
上海大眾汽車有限公司為了降低整車生產(chǎn)成本，同時也為了提高公司的核心技術(shù)能力，從2001年開始，涉足轎車沖壓模具設(shè)計制造領(lǐng)域。2001年-2002 年完成了POLO轎車在手動壓機(jī)線上生產(chǎn)的10只簡單零件的模具，通過了公司質(zhì)保部門驗收并投產(chǎn)。2002年開始向大型化、復(fù)雜化、自動化發(fā)展，設(shè)計制造了6000kN自動線上生產(chǎn)的POLO轎車備胎座模具(該零件外形尺寸大、拉深深度深、形狀復(fù)雜)2003年，為進(jìn)一步提高模具設(shè)計制造的能力和水平，我們涉足20000kN多工位壓力機(jī)和10000kN自動線生產(chǎn)使用的模具設(shè)計。過去上海大眾在20000kN多工位壓力機(jī)上使用的模具，全部需進(jìn)u,國內(nèi)模具商還沒有能力設(shè)計制造這樣的模具。為此，我們選擇了POLO轎車中柱內(nèi)板的模具進(jìn)行設(shè)計。20000kN多工位壓力機(jī)是世界上最先進(jìn)的壓力機(jī)之一，集成化、自動化程度非常高，當(dāng)然這對模具設(shè)計的要求也相應(yīng)地提高。零件的送料高度、步距、機(jī)械手的位置有嚴(yán)格的要求，還要保證機(jī)械手在運(yùn)動過程中與模具無干涉，這樣給予模具設(shè)計的空間就小了很多。在考慮諸多因素之后，我們最終完成了整套模具的設(shè)計，其CAD裝配狀態(tài)如圖1所示。另外，我們還完成了POLO轎車在10000kN自動線上生產(chǎn)的后輪罩的模具設(shè)計，在去年的基礎(chǔ)上更進(jìn)一步。這些工作的順利完成，標(biāo)志著上海大眾模具設(shè)計能力已經(jīng)達(dá)到了國內(nèi)先進(jìn)水平，從而為今后上海大眾汽車模具國產(chǎn)化打下了堅實的基礎(chǔ)。盡管如此，與國際先進(jìn)水平比較，仍有較大差距，比如在轎車外覆蓋件模具設(shè)計方面還是空自。
在轎車沖模中，難度最大的是外覆蓋件模具設(shè)計，主要表現(xiàn)在以下兩個方面:
(1)克服由回彈造成的零件型面偏差
破裂、起皺、回彈是轎車沖壓件成形過程中的主要缺陷，由于轎車外覆蓋件外形尺寸大、拉深深度淺、塑性變形程度低，一般不易拉裂，因而回彈就成為該類零件制造過程中的主要問題，它將嚴(yán)重影響零件間的相互配合關(guān)系。有限元模擬軟件在沖壓模具設(shè)計中得到普遍應(yīng)用，已經(jīng)能夠比較準(zhǔn)確地預(yù)測破裂和起皺，從而有助于設(shè)計合適的工藝補(bǔ)充面來改善拉深過程中材料的流動狀況，提高零件的成形ft。然而，迄今為止，大多數(shù)有限元軟件還不能精確地預(yù)測沖壓件從模具當(dāng)中取出后的回彈變形。因此，對外覆蓋件回彈問題的處理，主要還是依靠經(jīng)驗來修改模具型面，使沖壓件過正成形，來抵消由于回彈導(dǎo)致的變形。
(2)沖壓件的取件
由于外覆蓋件(如前蓋外板、車頂、翼子板)都需進(jìn)行復(fù)雜的翻邊整形或預(yù)卷邊工藝，這就使得在模具結(jié)構(gòu)設(shè)計時，必須考慮沖壓件成形后的取件問題，目前，大都依靠復(fù)雜的多斜楔機(jī)構(gòu)聯(lián)動來實現(xiàn)模具工作部分對零件讓位，以實現(xiàn)方便取件，由此造成整個模具的結(jié)構(gòu)十分復(fù)雜。
3 國外覆蓋件模具設(shè)計
目前，國外大汽車公司為了降低模具開發(fā)、制造成本，縮短生產(chǎn)周期，將除轎車外覆蓋件之外的大部分轎車沖壓件的模具都交由專業(yè)模具公司(如Fontana Pietro. Kuka. Laepple.Schuler Cartec.Ogi-hala-Fuji Techniaca等等)設(shè)計和制造，這些公司都有很強(qiáng)的開發(fā)能力，并在某些零件的模具制造方面擁有獨(dú)到的優(yōu)勢。但作為整車廠，考慮到新車型開發(fā)過程中的保密，對諸如翼子板、行李箱蓋、車門、側(cè)圍、車頂、前蓋等敏感零部件的模具，則都由自己的模具制造部門來設(shè)計和制造。
3.1軟件環(huán)境
沖壓模具設(shè)計，除了必要的CAD軟件之外，還大量應(yīng)用了有限元模擬軟件，如AutoForm.PamStamp. DynaForm. Indeed等，來輔助沖壓工藝設(shè)計。下面，以AutoForm為例，說明如何利用CAE軟件來設(shè)計拉深工序工藝補(bǔ)充面。
AutoForm是一款由瑞士開發(fā)的專業(yè)薄板成形快速模擬軟件，可以用于薄板、拼焊板的沖壓成形、液壓脹形等過程的模擬，配合不同的功能模塊，還可以進(jìn)行沖壓件單步法成形模擬以及拉深工序工藝補(bǔ)充面((Addendum)的設(shè)計。轎車沖壓件中，約有2/3可以利用AutoForm的Diedesigner Module模塊設(shè)計Addendum，該模塊根據(jù)由設(shè)計者指定的或由軟件自動產(chǎn)生的壓邊圈型面，以及工藝補(bǔ)充面的多條截面線(Profile)，能夠快速地生成工藝補(bǔ)充面，用于拉深工序的模擬，如圖2所示。壓邊圈型面、Profile均可進(jìn)行參數(shù)化式的調(diào)整。這種快速設(shè)計是建立在對Addendum曲面的粗略構(gòu)造上的，即曲面面片本身以及曲面面片之間的連續(xù)并非十分光順，盡管這種曲面不能夠直接用于模具表面的機(jī)械加工，但是對于模擬精度的影響卻不是很大。根據(jù)模擬結(jié)果，設(shè)計者可以很方便地對工藝補(bǔ)充面進(jìn)行調(diào)整，直到模擬結(jié)果滿足設(shè)計要求。最后，將壓邊圈、Addendum曲面和Profile以中性數(shù)據(jù)格式IGS或VDA輸出，在CAD軟件中進(jìn)行曲面重構(gòu)，并結(jié)合產(chǎn)品數(shù)模，就能夠得到機(jī)加工可以使用的拉深工序模具數(shù)模。
沖壓工藝傳統(tǒng)設(shè)計方法:首先，在經(jīng)驗基礎(chǔ)上，利用CAD設(shè)計工藝補(bǔ)充面;其次，將CAD數(shù)模傳遞給AutoForm等CAE軟件進(jìn)行拉深過程模擬;根據(jù)模擬結(jié)果，在CAD中對工藝補(bǔ)充面進(jìn)行調(diào)整，并將新的CAD數(shù)模傳遞給CAE，開始新的模擬，直到滿足要求為比。這是一個從CAD到CAE再回到CAD的不斷反復(fù)的過程。由于每次在CAD中構(gòu)造曲面都遠(yuǎn)較在AutoForm中復(fù)雜，因此，整個過程所花費(fèi)的時間就多得多。而新方法在沖壓工藝設(shè)計初期，就用 Diedesigner Module在AutoForm軟件中設(shè)計并調(diào)整拉深工藝補(bǔ)充面，與傳統(tǒng)的設(shè)計方法相比，就能夠大大提高設(shè)計效率。
由于AutoForm是一款快速模擬軟件，為了在較短的時間內(nèi)對復(fù)雜沖壓件的成形過程進(jìn)行評價，采用了膜單元來離散幾何模型，必然要降低模擬精度，因此，有些汽車公司在模具設(shè)計開始之前還要利用模擬精度高的CAE軟件，如德國大眾就采用了Indeed軟件，對拉深工序進(jìn)行再次模擬((Indeed軟件的計算是基于帶厚度的殼單元的，能夠得到更為準(zhǔn)確的計算結(jié)果，但是其計算所花費(fèi)的時間通常是AutoForm的幾到十幾倍，該軟件比較適用于最終驗證)，所有拉深工藝必須通過Indeed模擬并驗證為是可行的，才可用于模具設(shè)計。
模具設(shè)計完備，應(yīng)通過圖紙結(jié)合泡沫模型進(jìn)行驗收(圖3)，各道工序用不同顏色的線條標(biāo)記在泡沫模型上，這樣做直觀而清晰。還應(yīng)組織包括工藝設(shè)計者、項目規(guī)劃員、模具調(diào)試人員、模具操作者等相關(guān)人員進(jìn)行討論驗收。對于在沖壓工藝上難以解決的成形問題，還應(yīng)邀請產(chǎn)品開發(fā)人員一同討論，尋求對產(chǎn)品進(jìn)行更改設(shè)計的可能性。
3.2 修正回彈的對策
由前已知，回彈是轎車外覆蓋件成形過程中的主要問題，現(xiàn)以前蓋外板為例，對此進(jìn)行詳細(xì)分析。
通常外覆蓋件的回彈有以下兩類:
①大片平坦曲面由彈性回復(fù)造成的拱起或塌陷，如圖4中C部放大所示，虛線表示零件從模具中取出并發(fā)生回彈后的位置。這類問題，工藝設(shè)計時通常不加以考慮，工藝數(shù)模中產(chǎn)品型面部分的數(shù)據(jù)與來自于產(chǎn)品開發(fā)部門的數(shù)據(jù)相一致，并用于模具制造。待試模之后，將試件與檢具進(jìn)行對比測量，根據(jù)偏差對拉深模型面進(jìn)行修正。如果設(shè)計人員對于這類問題的控制擁有非常豐富經(jīng)驗的話，也可以事先估計出曲面彈性回復(fù)的方向以及偏移量，并將其反向疊加到產(chǎn)品數(shù)模上去，求得考慮回彈變形的拉深工藝曲面，這個計算過程需要由專門的計算機(jī)軟件來完成，在德國大眾，采用的是ICEM。
②翻邊整形部分由彎曲變形回彈造成的折邊轉(zhuǎn)角變化，如圖4中B部放大所示。對于這類問題，該處除拉深和剪邊外，還包括翻邊和斜楔整形，整形工藝需過正成形2 -3 ，以抵消彎曲回彈。該工作由工藝設(shè)計完成，并體現(xiàn)在工藝方案的數(shù)模中。
3.3 新斜楔機(jī)構(gòu)在外覆蓋件模具上的應(yīng)用
目前，新車型的很多外覆
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