雙孔鏈板片沖孔落料復(fù)合模設(shè)計(jì)-帶答辯ppt（鏈片沖壓模具含12張CAD圖紙）
雙孔鏈板片沖孔落料復(fù)合模設(shè)計(jì)-帶答辯ppt（鏈片沖壓模具含12張CAD圖紙）,雙孔鏈板片,沖孔,復(fù)合,設(shè)計(jì),答辯,ppt,沖壓,模具,12,CAD,圖紙
20XX 年度畢業(yè)生論文答辯鏈板片沖孔落料復(fù)合模設(shè)計(jì)1答辯人：答辯人：XXXX指導(dǎo)教師：指導(dǎo)教師：XXXX 目錄主要零部件設(shè)計(jì)主要零部件設(shè)計(jì)模具設(shè)計(jì)工藝計(jì)算模具設(shè)計(jì)工藝計(jì)算模具總體結(jié)構(gòu)的確定模具總體結(jié)構(gòu)的確定沖裁方案的確定沖裁方案的確定工藝分析工藝分析齒輪螺栓墊片沖壓模設(shè)計(jì)齒輪螺栓墊片沖壓模設(shè)計(jì)對(duì)工件進(jìn)行相關(guān)的工藝分析給出設(shè)計(jì)任務(wù)根據(jù)分析結(jié)果確定工藝方案工藝分析設(shè)計(jì)任務(wù)工藝分析工藝方案設(shè)計(jì)任務(wù)鏈板片沖孔落料復(fù)合模設(shè)計(jì) 鏈板片零件圖鏈板片的材料為10鋼，厚度為0.5mm，大批量生產(chǎn)。設(shè)計(jì)任務(wù)工藝分析 （1 1）材料）材料:該沖裁件的材料為該沖裁件的材料為1010號(hào)鋼號(hào)鋼，1010號(hào)鋼塑性、號(hào)鋼塑性、韌性很好，易冷熱加工成形，具有較好的沖裁成形性性韌性很好，易冷熱加工成形，具有較好的沖裁成形性性能，適合要求較高的零件。綜合評(píng)比均適合沖裁加工。能，適合要求較高的零件。綜合評(píng)比均適合沖裁加工。（2）零件結(jié)構(gòu)）零件結(jié)構(gòu):零件結(jié)構(gòu)簡(jiǎn)單對(duì)稱(chēng)，無(wú)尖角，對(duì)零件結(jié)構(gòu)簡(jiǎn)單對(duì)稱(chēng)，無(wú)尖角，對(duì)沖裁加工較為有利。外形有多處圓弧，里面有兩個(gè)圓孔，沖裁加工較為有利。外形有多處圓弧，里面有兩個(gè)圓孔，孔的直徑為孔的直徑為10mm10mm，外圓半徑為，外圓半徑為12mm12mm，凸、凹模允許的最，凸、凹模允許的最小壁厚小壁厚4.5mm，小于最小孔邊距，小于最小孔邊距5mm,所以，用倒裝式所以，用倒裝式復(fù)合模沖壓這個(gè)零件。因此，復(fù)合模沖壓這個(gè)零件。因此，該制件具有良好的沖壓工該制件具有良好的沖壓工藝性，比較適合沖裁。藝性，比較適合沖裁。（3）尺寸精度）尺寸精度:由于本零件給定的精度都按生產(chǎn)由于本零件給定的精度都按生產(chǎn)所需經(jīng)濟(jì)精度要求所需經(jīng)濟(jì)精度要求IT14，查閱相關(guān)資料，發(fā)現(xiàn)普通沖裁，查閱相關(guān)資料，發(fā)現(xiàn)普通沖裁能夠滿足零件精度要求。能夠滿足零件精度要求。工藝方案 該零件包括落料、沖孔兩個(gè)基本工序，現(xiàn)有以下三種工藝方案:（1）在壓力機(jī)一次行程內(nèi)只完成一個(gè)沖壓工序的沖裁模即單工序沖裁。（2）在壓力機(jī)一次行程內(nèi)，在模具的同一位置同時(shí)完成兩個(gè)或兩個(gè)以上的沖壓工序即復(fù)合沖裁。（3）把沖裁件的若干個(gè)沖壓工序，排列成一定的順序，在壓力機(jī)的一次行程中條料在沖模的不同位置上，分別完成工件所要求的工序即級(jí)進(jìn)沖裁。由于該零件的生產(chǎn)要求的是大批量生產(chǎn)、零件的尺寸較小，制造相對(duì)比較難，為提高生產(chǎn)率，根據(jù)上述方案分析、比較，宜采用復(fù)合模沖裁。模具結(jié)構(gòu)模具結(jié)構(gòu)模具結(jié)構(gòu)卸料卸料出件方式出件方式定位定位方式方式模具模具類(lèi)型類(lèi)型送料送料方式方式模具類(lèi)型按照復(fù)合模工作零件的安裝位置不同，分為正裝式復(fù)合模和倒裝按照復(fù)合模工作零件的安裝位置不同，分為正裝式復(fù)合模和倒裝式復(fù)合模兩種，兩種類(lèi)型的優(yōu)點(diǎn)、缺點(diǎn)及適用范圍見(jiàn)下表：式復(fù)合模兩種，兩種類(lèi)型的優(yōu)點(diǎn)、缺點(diǎn)及適用范圍見(jiàn)下表：模具類(lèi)型 正裝式復(fù)合模適合于沖制材質(zhì)較軟或板料較薄的平直度要求較高的沖裁件，還可以沖制孔邊距離較小的沖裁件。倒裝式冷沖模不宜沖制孔邊距離較小的沖裁件，但倒裝式冷沖模結(jié)構(gòu)簡(jiǎn)單，可以直接利用壓力機(jī)打桿裝置進(jìn)行推件，卸件可靠，便于操作，并為機(jī)械化出件提供了有利條件，故應(yīng)用十分廣泛。綜上所述，該制件結(jié)構(gòu)形狀簡(jiǎn)單，精度要求較低，孔邊距較大，宜采用倒裝式復(fù)合模。由以上沖壓工藝分析可知，采用復(fù)合模沖壓，模具類(lèi)型為倒裝式復(fù)合模。送料方式 條料在模具送料平面必須有兩個(gè)方向的限位：一是條料在模具送料平面必須有兩個(gè)方向的限位：一是在與條料方向垂直的方向上的限位，保證條料沿正確的在與條料方向垂直的方向上的限位，保證條料沿正確的方向送進(jìn)，稱(chēng)為送進(jìn)導(dǎo)向；二是在送料方向上的限位，方向送進(jìn)，稱(chēng)為送進(jìn)導(dǎo)向；二是在送料方向上的限位，控制條料一次送進(jìn)的距離稱(chēng)為送料定距?？刂茥l料一次送進(jìn)的距離稱(chēng)為送料定距。送進(jìn)導(dǎo)向的定位零件有導(dǎo)料銷(xiāo)、導(dǎo)料板、側(cè)壓板等；送進(jìn)導(dǎo)向的定位零件有導(dǎo)料銷(xiāo)、導(dǎo)料板、側(cè)壓板等；送料定距的定位零件有用擋料銷(xiāo)、導(dǎo)正銷(xiāo)、側(cè)刃等。送料定距的定位零件有用擋料銷(xiāo)、導(dǎo)正銷(xiāo)、側(cè)刃等。由于零件的生產(chǎn)批量是大批量及模具類(lèi)型的確定，由于零件的生產(chǎn)批量是大批量及模具類(lèi)型的確定，合理安排生產(chǎn)可合理安排生產(chǎn)可采用前后自動(dòng)送料方式采用前后自動(dòng)送料方式。定位方式因?yàn)樵撃＞卟捎玫氖菞l料，控制條料的送進(jìn)方向采用導(dǎo)料銷(xiāo)，無(wú)側(cè)壓裝置?？刂茥l料的送進(jìn)布局采用擋料銷(xiāo)定距。而第一件的沖壓位置因?yàn)闂l料長(zhǎng)度有一定余量，可以靠操作工目測(cè)來(lái)定。卸料、出件方式 工件平直度較高，料厚為工件平直度較高，料厚為0.5mm0.5mm相對(duì)較薄，卸料相對(duì)較薄，卸料力不大，由于彈性卸料模具比剛性卸料模具方便，操力不大，由于彈性卸料模具比剛性卸料模具方便，操作者可以看見(jiàn)條料在模具中的送進(jìn)狀態(tài)，且彈性卸料作者可以看見(jiàn)條料在模具中的送進(jìn)狀態(tài)，且彈性卸料板對(duì)工件施加的柔性力，不會(huì)損傷工件表面，故可采板對(duì)工件施加的柔性力，不會(huì)損傷工件表面，故可采用用彈性卸料彈性卸料。排樣設(shè)計(jì)排樣設(shè)計(jì)沖裁力計(jì)算沖裁力計(jì)算沖壓設(shè)備選擇沖壓設(shè)備選擇刃口尺寸刃口尺寸工藝計(jì)算 排樣設(shè)計(jì) 一、確定搭邊值一、確定搭邊值 搭邊起補(bǔ)償條料的剪裁誤差，送料步距誤差以搭邊起補(bǔ)償條料的剪裁誤差，送料步距誤差以及補(bǔ)償于條料與導(dǎo)料板之間有間隙所造成的送料及補(bǔ)償于條料與導(dǎo)料板之間有間隙所造成的送料歪斜誤差的作用。使凸，凹模刃口雙邊受力，受歪斜誤差的作用。使凸，凹模刃口雙邊受力，受力平衡，合理間隙一易破壞，模具壽命與工件斷力平衡，合理間隙一易破壞，模具壽命與工件斷面質(zhì)量都能提高。對(duì)于利用搭邊自動(dòng)送料模具，面質(zhì)量都能提高。對(duì)于利用搭邊自動(dòng)送料模具，搭邊使條料有一定的剛度，以保證條料的連續(xù)送搭邊使條料有一定的剛度，以保證條料的連續(xù)送進(jìn)。搭邊的合理數(shù)值主要決定于材料厚度、材料進(jìn)。搭邊的合理數(shù)值主要決定于材料厚度、材料種類(lèi)、沖裁件的大小以及沖裁件的輪廓形狀等。種類(lèi)、沖裁件的大小以及沖裁件的輪廓形狀等。一般板料愈厚，材料愈軟以及沖裁件尺寸愈大，一般板料愈厚，材料愈軟以及沖裁件尺寸愈大，形狀愈復(fù)雜，則搭邊值也應(yīng)愈大。形狀愈復(fù)雜，則搭邊值也應(yīng)愈大。選擇選擇工件間搭工件間搭邊值為邊值為3mm3mm，側(cè)面搭邊值為，側(cè)面搭邊值為3mm3mm。排樣設(shè)計(jì)二、送料步距與條料寬度的計(jì)算二、送料步距與條料寬度的計(jì)算采用直對(duì)排的排樣方案，如圖所示采用直對(duì)排的排樣方案，如圖所示。送料步距送料步距A A：送料步距的大小應(yīng)為條料上沖裁件的對(duì)應(yīng)點(diǎn)：送料步距的大小應(yīng)為條料上沖裁件的對(duì)應(yīng)點(diǎn)之間的距離，每次沖之間的距離，每次沖1 1個(gè)零件的步距按式：個(gè)零件的步距按式：A A寬寬a a1 1，A A2424+3 32727mmmm 條料寬度條料寬度B B：B B：B B長(zhǎng)長(zhǎng)+2a+2a=（6060+2+23 3）mm=mm=6666mmmm沖壓件的毛坯面積沖壓件的毛坯面積的計(jì)算，的計(jì)算，利用利用cadcad測(cè)量得面積測(cè)量得面積1316.4mm1316.4mm2 2排樣設(shè)計(jì)三、材料利用率的計(jì)算三、材料利用率的計(jì)算材料利用率是指沖裁件的實(shí)際面積與所用板料面積的百分材料利用率是指沖裁件的實(shí)際面積與所用板料面積的百分比，他是衡量合理利用材料的經(jīng)濟(jì)性指標(biāo)，一個(gè)步距內(nèi)的材料比，他是衡量合理利用材料的經(jīng)濟(jì)性指標(biāo)，一個(gè)步距內(nèi)的材料利用率計(jì)算式為：利用率計(jì)算式為：式中，式中，A A為一個(gè)步距內(nèi)沖裁件的實(shí)際面積，為一個(gè)步距內(nèi)沖裁件的實(shí)際面積，B B為條料寬度為條料寬度,S,S為步距為步距,即每次條料送進(jìn)模具的距離。所以計(jì)算得加工該零件即每次條料送進(jìn)模具的距離。所以計(jì)算得加工該零件的材料利用率如下：的材料利用率如下：沖裁力計(jì)算 計(jì)算沖裁力的目的是為了選擇合適的壓力機(jī)，設(shè)計(jì)算沖裁力的目的是為了選擇合適的壓力機(jī)，設(shè)計(jì)模具和檢驗(yàn)?zāi)＞叩膹?qiáng)度，壓力機(jī)的噸位必須大于計(jì)模具和檢驗(yàn)?zāi)＞叩膹?qiáng)度，壓力機(jī)的噸位必須大于所計(jì)算的沖裁力，以適宜沖裁的要求，普通平刃沖所計(jì)算的沖裁力，以適宜沖裁的要求，普通平刃沖裁模，其沖裁力裁模，其沖裁力F F一般按如下計(jì)算：一般按如下計(jì)算：落料力：Fl147.40.536027KN。卸料力：Fx0.04271.1 KN。沖孔力：Fc 62.80.536012KN。推件力：Ft=80.0512=4.8F總=F落+F沖孔+F卸+F推=27+12+1.1+4.8=44.9KN 壓力機(jī)公稱(chēng)壓力的確定：沖裁時(shí)，壓力機(jī)的公稱(chēng)壓力機(jī)公稱(chēng)壓力的確定：沖裁時(shí)，壓力機(jī)的公稱(chēng)壓力必須大于或等于各沖裁工藝力的總和：壓力必須大于或等于各沖裁工藝力的總和：沖壓設(shè)備選擇 計(jì)算得總沖壓力是計(jì)算得總沖壓力是44.944.9KNKN，所選壓力機(jī)，所選壓力機(jī)的公稱(chēng)壓力的公稱(chēng)壓力必須大于或等于總沖壓力必須大于或等于總沖壓力的的1.31.3倍倍。所以選用公稱(chēng)壓力。所以選用公稱(chēng)壓力為為160160KNKN的機(jī)械壓力機(jī)。的機(jī)械壓力機(jī)。刃口尺寸 根據(jù)實(shí)用間隙表查得材料不銹鋼的最小雙面間隙根據(jù)實(shí)用間隙表查得材料不銹鋼的最小雙面間隙Zmin=0.04mm，最大雙，最大雙面間隙面間隙Zmax=0.06mm。具體計(jì)算見(jiàn)下表：具體計(jì)算見(jiàn)下表：主要零部件設(shè)計(jì)一、凹模的設(shè)計(jì)一、凹模的設(shè)計(jì)二、凸模的設(shè)計(jì)二、凸模的設(shè)計(jì)三、凸凹模設(shè)計(jì)三、凸凹模設(shè)計(jì)四、墊板的設(shè)計(jì)四、墊板的設(shè)計(jì)凹模的設(shè)計(jì)凸模的設(shè)計(jì)凸模高度為：凸模高度為：L L=h1+h2h1+h2+附加長(zhǎng)度附加長(zhǎng)度 (7-7-5)5)式中：式中：h1h1-凸模固定板厚度，可得：凸模固定板厚度，可得：h1=h1=1818mmmm；h2h2-凹模厚度，可得：凹模厚度，可得：h2=h2=2525mmmm；附加長(zhǎng)度包括凸模的修磨量，凸模進(jìn)入附加長(zhǎng)度包括凸模的修磨量，凸模進(jìn)入凸凹模的深度。（附加長(zhǎng)度取凸凹模的深度。（附加長(zhǎng)度取1mm1mm）由公式得由公式得L=L=1818+25+125+1=4444(mm)(mm)由以上可得凸模簡(jiǎn)圖如圖所示由以上可得凸模簡(jiǎn)圖如圖所示凸凹模的設(shè)計(jì)凸凹模外形的確定凸凹模外形的確定凸凹模的外形由本套模具所設(shè)計(jì)的零件圖樣外形確定凸凹模的外形由本套模具所設(shè)計(jì)的零件圖樣外形確定凸凹模材料的選取在該模具中凸凹模材料選用Cr12凸凹模精度的確定外形精度公差為IT7凸凹模壁厚的確定凹模內(nèi)外刃口間壁厚校核：根據(jù)沖裁件結(jié)構(gòu)凸凹模內(nèi)外刃口最小壁厚為1.8mm，該壁厚為1.8mm即可，本設(shè)計(jì)中凸凹模的壁厚為7mm，故該凸凹模的側(cè)壁強(qiáng)度要求足夠凸凹模洞口類(lèi)型的選取選擇直通式洞口，如圖所示墊板的設(shè)計(jì)它的作用是直接承受和擴(kuò)散凸模傳遞的壓力，如它的作用是直接承受和擴(kuò)散凸模傳遞的壓力，如果凸模的端部對(duì)材料的壓力超過(guò)材料的許用壓力，果凸模的端部對(duì)材料的壓力超過(guò)材料的許用壓力，需在凸模端部與模座之間加上墊板防止模具損壞。需在凸模端部與模座之間加上墊板防止模具損壞。墊板外形尺寸可與固定板相同，其厚度一般取墊板外形尺寸可與固定板相同，其厚度一般取3 310mm10mm，查參考文獻(xiàn)沖壓模具設(shè)計(jì)與制造，查參考文獻(xiàn)沖壓模具設(shè)計(jì)與制造 22.522.5-17JB/T7643.317JB/T7643.3-1994,1994,墊板尺寸為墊板尺寸為1 14 40mm0mm1 12020mmmm8 8mmmm。裝配圖工作過(guò)程：1、前后方向進(jìn)料；2、導(dǎo)料銷(xiāo)進(jìn)行導(dǎo)料 3、定位銷(xiāo)進(jìn)行定位 4、由零件18進(jìn)行沖孔，后續(xù)工位19進(jìn)行落料 5、料由大氣壓吹出 謝謝各位老各位老師！
英文資料
Comparison of sheet-metal-forming simulation and
try-out tools in the design of a forming tool
A. ANDERSSON
Today, sheet-metal-forming simulation is a poAwerful technique for predicting the formability of automotive parts. Compared with traditional methods such as the use of try-out tools, sheet-metal-forming simulation enables a significant increase in the number of tool designs that can be tested before hard tools are manufactured. Another advantage of sheet-metal-forming simulation is the possibility to use it at an early stage of the design process, for example in the preliminary design phase.Today, the accuracy of the results in sheet-metal-forming simulation is high enough to replace the use of try-out tools to a great extent. At Volvo Car Corporation, Body Components, where this study has been carried out, sheet-metal-forming simulation is used as an integrated part in the process of tool design and tool production.
1 Introduction
Traditionally, try-out tools are used to verify that a certain tool design will produce parts of the required quality. The try-out tools are often made of a cheaper material (e.g. kirksite) than production tools in order to reduce the try-out costs. This is a very time-consuming and cost-consuming method. However, today another more efficient technique is available—sheet-metal-forming simulation. This new technique is based on the simulation of the forming process, and could result in a cost reduction of factor 10 and a time reduction of factor 15 for each hard tool. Sheet-metal-forming simulation technology is constantly developing and the results of the simulations are
more and more accurate. In the future it will also be possible to analyse more processes using sheet-metal-forming simulations. Today, the accuracy of the results in sheetmetal- forming simulation is high enough to replace the use of try-out tools to a great extent.
2 Method
The purpose of this study is to analyse and compare the benefits and drawbacks of the use of sheet-metal-forming simulation and try-out tools in the design of forming tools. The method employed in this study is based on the Production Reliability Matrix (PSM) (Rundqvist and Sta°hl 2001) together with a Process Correspondence Matrix (PCM) that has been developed especially for this study. The PSM is a matrix that categorizes the effects of different factors (parameters) in the process into different factor groups. The effect of each factor (parameter) is then assessed according to a scale of 0–3. Based on the results of the matrix, the parameters that have the most considerable effects on the production process can be extracted, and a priority list for neutralizing or minimizing these effects can be made. The PCM has been developed through extensive interviews of senior experts in automotive component forming to analyse the correspondence between the results of sheet-metalforming simulations, the try-out tool and the quality of produced parts in actual production.
3 Process for designing a forming tool
Figure 1 shows a simplified flow of the production process of developing a forming tool at Volvo Car Corporation, Body Components (VCBC).
The process of the design of a forming tool includes a try-out phase where different designs of the tool are tested. This is a very important stage in the tool design process,in order to verify that the part will fulfil the required quality. It is very difficult to predict the result of a forming operation, but by using sheet-metal-forming simulation there is a possibility to gain valuable insight into the outcome of the forming operation.
3.1 Use of sheet-metal-forming simulation
Sheet-metal-forming simulation can be used in several stages of a tool design process:
●early in the preliminary design phase, to enable rapid verification of different proposals for the design of automotive components
●to improve an existing process.
Preliminarydesign of part
Part
layout
Hard forming tools/Process design
Try-out
tools
Sheet metal forming simulation
Figure 1. Process for designing a forming tool at VCBC.
3.1.1. Requirements for sheet-metal-forming simulation.
Sheet-metal-forming simulation requires the following:
●Simulation software.
●A computer-aided design (CAD) model of the part layout or a CAD model of the forming surfaces of the tool.
●Parameters for description of the specified sheet-metal material.
●Process parameters.
●Workstations (today the development of the personal computer (PC) is rapidly advancing so that PCs will be a strong alternative in the future).
●A competent staff that can handle the software and analyse the results of the simulation.
Simulation software. Today there is a variety of commercial software available on the market. In order to find suitable software, the area of use must be analysed. The software package is different with regard to user-friendliness and flexibility.
At VCBC, where this study was performed, two different software packages are used. One is Autoform (2001), which is user-friendly and provides fast results. This software is used for the iterative process of finding the proper tool geometry. The other software is LS-DYNA (2001), which is used at VCBC to verify the results of
Autoform.
CAD model. In order to analyse a part or a tool design using sheet-metal-forming simulation, a CAD model of the part or tool is needed. This model can be created in most CAD programs, for instance CATIA, which is used at VCBC. Different simulation software demand different qualities of the CAD models.
Material parameters. Uniaxial tensile tests are used to describe the material parameters. There is also a need for describing the risk of fracture in the material. Data regarding risk for fracture are obtained by creating a forming limit curve. The forming limit curve is a curve in the plane of principal strains that indicates the maximum allowed strain values before fracture occurs. A more thorough description is presented in Pearce (1991).
Process parameters. Sheet-metal-forming simulation requires proper process parameters (e.g. drawbeads).
Workstations. The simulation models that are used in sheet-metal-forming simulation are generally so large that they require a workstation in order to achieve reasonable calculation times. However, the development of PCs enables the clustering of several PCs, which can be an alternative to workstations.
Competent personnel. In order to interpret the results of a sheet-metal-forming simulation, it is necessary to enter the correct input data and possess the ability to understand the results. This requires competent personnel. The competence should consist of both forming knowledge and simulation knowledge since that gives a natural connection between the production process and the interpretation of the results.
Thickness(mm)
Rp0.2yield strength(Mpa)
Rm ultimate
tensile strength
(MPa)
n value
(average)
R value
(average)
0.8
140
320
0.243
1.76
Table 1 Material data for V-1158.
3.2. Results of a sheet-metal-forming simulation
Sheet-metal-forming simulation enables the study of:
●Thickness distribution.
●Risk of fracture.
●Draw lines.
●Wrinkles.
●Drawbeads/ blankholder pressure.
●Surface defects.
●Stability of the surface.
●Springback.
●Material behaviour.
●Process surveillance.
●Draw in.
●Forming window.
●Forces (punch, blankholder).
In order to demonstrate possible results, a simulation of a Body Side Outer from a Volvo S80 has been studied. The material used for this automotive component is a mild steel with good formability (V-1158). Material data are presented in table 1.
3.2.1. Thickness distribution.
The sheet-metal-forming simulation can provide a good approximation of the thickness distribution for a part (see figure 2). In the automotive industry there are requirements concerning the maximum allowable reduction in thickness, in order to ensure safety margins in the event of a crash.
Figure 2. Thickness distribution. The scale shows blue for 20% thinning and red for 10% thickening.
3.2.2. Risk for fracture. Risk for fracture during the forming process could be evaluated by means of a forming limit curve, which was described earlier in this section.
Figure 3. Risk for fracture.
In this image, cracks are shown in red. To the right is the forming limit curve represented by the black line. Shown also are the results of the simulations (blue points)
3.2.3. Draw lines. Draw lines occur when a visible section of an exterior part has been gliding over a radius during forming. A plot of how a point on the part surface moves during the simulation (see figure 4) illustrates these lines. Draw lines are not acceptable on a visible surface on an exterior part.
In figure 5, which describes formability, surfaces with enough strains to be stable can be seen. By studying these images together it is possible to estimate the stability of the surfaces. This is a simplified analysis. A more detailed analysis would include the interaction between stresses and strains for the complete part.
Figure 4. The blue dark line in the image shows how the material has flowed during the forming operation.
If the material has flowed over a radius, a draw line will appear on the part.
If the draw line appears on a visible surface of an exterior part, the part will be rejected for quality reasons.
Figure 5. The images show an example of surveillance of the process.
It is easy to follow how the wrinkles develop during the forming process.
3.2.4 Wrinkles. Visible wrinkles are not allowed on a part. These can be detected with sheet-metal-forming simulation (see figure 6).
3.2.5 Forces. In order to dimension the process in an accurate way, it is necessary to know which forces are necessary to form the part. The data for these forces can be obtained from the results of a sheet-metal-forming simulation.
3.2.6 Surface defects. Exterior automotive parts are sensitive to deflections of the surface that can occur during forming. These deflections can be very small but can still be visible after the part is painted, which means that the part must be scrapped.The defects can be detected by the human hand as it moves gently across the surface.Sheet-metal-forming simulation can be used for detecting risk areas through analysis of the stress strain distribution.。
3.2.7 Stability of the surface. Stable surfaces are required in order to increase the stiffness of the part to prevent the part from becoming unstable and vibrating. Sheet-metal-forming simulation can be used for detecting risk areas through analysis of the strain distribution. Figure 6 describes a simplified analysis. A more detailed analysis would include the interaction between stresses and strains for the complete part.。
Figure 6. The upper image shows the formability.
The grey areas in the upper image indicate unstable surfaces and the pink area indicates wrinkles. In the lower image the surfaces with small strains are marked blue, which indicates compression. If these areas are located on a visible surface of an exterior part, there is a risk for unstable areas.
3.2.8 Springback. Springback is a phenomenon that could be described as a change in geometry that occurs after the parts have been removed from the forming tool. This g eometry change causes mismatch for the part when it is assembled with other parts.
3.2.9 Process surveillance. In sheet-metal-forming simulation, the process can be followed in detail by means of animations. Figure 5 illustrates this.
3.2.10 Draw in. To minimize material consumption, it is important to optimize the shape of the blank. Sheet-metal-forming simulation can facilitate optimization of the blank by analysing the draw in (see figure 7).
3.2.11 Forming window. A forming window could be described as the allowable variation of the process parameters in order to keep the quality of the produced parts.
3.3. Use of try-out tools
Try-out tools are used when the design of the process is to be verified (see figure 1).Based on this design the try-out tools are then cast in kirksite, for example. Prototype parts are then produced from this try-out tool. There are several differences between a try-out tool and a production tool. One is that the try-out tool wears out much faster than a production tool. Therefore, it is not possible to produce so many parts in a try-out tool. Another difference is that a try-out tool is much cheaper than a production tool. However, since there are differences between the two types of tools, there is no guarantee that the parts produced in the two types of tools will have the same quality..
The PSM can be used to determine which parameters have significant effects on the stability of the process. It is also possible to determine the extent of an effect. This provides valuable help in the identification of the most severe problems. These severe problems are especially interesting since they are the most cost-effective when solved. A more detailed description of the PSM is presented by Rundqvist and Sta°hl (2001). An example where the PSM is applied is presented in Pettersson (1991), where the PSM is used to analyse different processes at VCBC.
Figure 7. The cyan line shows the sheet position after blankholder closing.
The draw in can then easily be measured by a comparison with the line in the bottom position.
5 Result
The technique of using try-out tools has been compared with the technique of using sheet-metal-forming simulation from two aspects. The first aspect is a comparison of the ability to predict the different parameters of the production process, mentioned in section 3. The second aspect is the ability to verify which process parameters should be studied.
5.1 Study of agreement of predicted process with production process
The PCM allows a clear comparison between try-out tools and simulation regarding correspondence with the production process. Table 2 presents the different fields of applications for the different techniques together with the ability to predict behaviour in the production process. The values in table 2 have been determined through extensive interviews with senior forming experts.
In table 2 the following scale is used:
5 The results show perfect agreement with the production process.
4 The results show good agreement with the production process. Special cases can deviate.
3 The results show good agreement in most cases with the production process.
2 The results show good agreement in certain cases with the production process. Indirect interpretation of the results is needed.
1 The results show no agreement with the production process. It cannot be used for process prediction or verification.
Comments on table 2 include the following:
● The difference between risk for fracture and actual fracture is that risk for fracture shows areas that have not cracked but where necking has appeared.
●The parameter ‘Material characteristics’ refers to the ability to predict the quality of the part depending on variation in the material quality.
● Process surveillance enables the monitoring of how different parameters change during the process.
●The forming window is an aid for detecting how sensitive the process is to disturbances.
●The values for the tool forces are based on the assumption that it is possible to measure the forces in the try-out press.
process
Thickness distribution
Risk for fracture
Fracture
Draw lines
Wrinkles
Surface defects
Stability of the surface
springback
Material properties
Process surveillance
Draw in
Force-punch
Draw beads
Blankholder force
Forming window
simulation
4
4
4
4
4
2
2
2
4
4
4
3
2
2
4
Try-out tool
3
3
4
3
4
4
4
3
2
3
4
3
4
3
3
Table 2. Process Correspondence Matrix (PCM): correspondence with the production process.
5.2 Study of which factors in the production process are possible to analyse
The concept of grouping different factors that are typical for the production process into different factor groups has been used in this study according to the PSM model. In a previous study (Andersson et al. 1999), different factors concerning the forming of aluminium were studied. This work has been modified in order to facilitate a comparison between the two techniques for prediction and verification considered in this study; namely, sheet-metal-forming simulation and try-out tools. See table 3 for the results.
In table 3 the following scale is used:
3 The results show perfect prediction of production process.
2 The results show direct prediction of production process.
1 The results show indirect prediction of production process.
0 The results cannot predict production process at all.
5.3. Restriction /expansion of test possibilities
An analysis of tables 2 and 3 shows several advantages of using sheet-metal-simulation in the tool design process. However, one of the biggest advantages of sheetmetal- forming simulation is that it enables the testing of many different designs of the part, tool or process, which generates substantial savings in costs and time. In this respect, try-out tools are more limited and expensive, which means that only a minimum number of try-out tools are produced. The use of try-out tools contributes to a restriction of test possibilities while the use of sheet-metal-forming simulation contributes to an expansion in test possibilitie
6. Conclusions
The use of sheet-metal-forming simulation leads to a significant reduction in both cost and time compared with the use of try-out tools. The requirement is that the respective parameter for study (see section 3.1.2) demonstrates good correspondence between simulation and actual production processes. Sheet-metal-forming simulation is also superior to try-out tools with regard to predicting and verifying the forming process.
The investment requirements are relatively small when starting to implement sheet-metal-forming simulation. It is necessary to invest in a workstation and software, which cost about SEK 500,000. In addition, it is necessary to have competent personal for handling the sheet-metal-forming simulation. Compared with the investment for one try-out tool (.SEK 500,000 per tool), it is clear that there is a lot to gain in reducing cost and time if sheet-metal-forming simulation is used when it is suitable.
Factor gruups
Sheet-metal-forming
simulation
Thy-out tools
A
Tooling
A1
Tool geometry
2
2
A2
Microgeomertril/Surface
0
1
A3
Drawbeads
1
2
B
Material
B1
Thickness distribution
2
2
B2
Risk for fraction
2
2
B3
Draw lines
2
2
B4
Wrinkles
2
2
B5
Surface defects
1
2
B7
Surface stability
1
2
B8
Springback
1
2
B9
Material properities
2
2
B10
Draw in
2
2
B11
Surface roughness/galling
0
2
C
Process
C1
Press velocity
1
2
C2
Temperature
0
1
C3
Lubrication
1
2
C4
Forces-punch
2
2
C5
Forces-blankholder
2
2
C8
Forming-window
2
2
D
Human factor
D1
Control
1
2
D2
Change frequency
1
2
E
Maintenace
E2
Press maintenace
1
1
F
Special factors
F1
Tool cleaning
0
2
G
Misc equipment
G1
Handling equipment
1
3
Table 3. The possibilities to predict different factors (parameters) in the production process
compared in a Production Reliability Matrix (PSM)
Assuming the possibility of measuring forces in the try-out tool.
As stated earlier, today the accuracy of the results in sheet-metal-forming simulation is high enough to replace the use of try-out tools to a great extent. The use of try-out tools in the tool design process may be necessary for some time to come to verify some process parameters, but the following advantages are closely associated with sheet-metal-forming simulation:
● Deeper insight into the process at significantly earlier stages.
● Greater flexibility in testing designs for the part, the tool
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