753 杯形件拉深模具的設(shè)計

753 杯形件拉深模具的設(shè)計,杯形件拉深,模具,設(shè)計 山 西 農(nóng) 業(yè) 大 學(xué)本科生畢業(yè)論文（設(shè)計）選題審批表畢業(yè)論文（設(shè)計）題目 杯形件拉深模具的設(shè)計指 導(dǎo) 教 師 邢澤炳 職 稱 副教授學(xué)生具備條件 修完教學(xué)計劃要求課程內(nèi)容及學(xué)時選題完成形式 開題報告內(nèi) 容 簡 要：本論文應(yīng)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)和提高獨立工作能力，鞏固與擴充了冷沖壓模具設(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)計的基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，了解了模具的基本結(jié)構(gòu)，提高了計算能力，繪圖能力，熟悉了規(guī)范和標準，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。采用拉深模模具設(shè)計制造簡便易行。拉深效果好，能極大地提高生產(chǎn)效率。本設(shè)計共分 5 章，分別論述了產(chǎn)品工藝分析，工藝計算，模板及零件設(shè)計，模具組立等問題。了解產(chǎn)品用途，并進行沖壓件的工藝性及尺寸公差等級分析，對于一些沖壓件結(jié)構(gòu)不合理或工藝性不好的進行改進并繪制模具總圖和非標準件零件圖。 系主任簽字：年 月 日 院長簽字：年 月 日山西農(nóng)業(yè)大學(xué)本科生畢業(yè)論文(設(shè)計)開題報告題 目 杯形件拉深模具的設(shè)計 學(xué) 院 信息學(xué)院 專 業(yè) 機械設(shè)計制造及其自動化 年 級 機制信 052 姓 名 田 陽 學(xué) 號 2005151211 指導(dǎo)教師 邢澤炳 職 稱 副教授 2009 年 06 月 15 日 選題的依據(jù)及意義隨著科學(xué)技術(shù)的發(fā)展需要，模具已成為現(xiàn)代化不可缺少的工藝裝備，模具設(shè)計是機械專業(yè)一個最重要的教學(xué)環(huán)節(jié),是一門實踐性很強的學(xué)科，是我們對所學(xué)知識的綜合運用，通過對專業(yè)知識的綜合運用，對模具從設(shè)計到制造的過程有個基本上的了解，為以后的工作及進一步學(xué)習(xí)深造打下了堅實的基礎(chǔ)。模具制造技術(shù)現(xiàn)代化是模具工業(yè)發(fā)展的基礎(chǔ)。計算機技術(shù)、信息技術(shù)、自動化技術(shù)等先進技術(shù)正在不斷向傳統(tǒng)制造技術(shù)滲透、交叉、融合形成了現(xiàn)代模具制造技術(shù)。其中高速銑削加工、電火花銑削加工、慢走絲切割加工、精密磨削及拋光技術(shù)、數(shù)控測量等代表了現(xiàn)代沖模制造的技術(shù)水平。高速銑削加工不但具有加工速度高以及良好的加工精度和表面質(zhì)量（主軸轉(zhuǎn)速一般為15000~40000r/min）,加工精度一般可達 10 微米，最好的表面粗糙度 Ra≤1 微米） ，而且與傳統(tǒng)切削加工相比具有溫升低（工件只升高 3 攝氏度） 、切削力小，因而可加工熱敏材料和剛性差的零件，合理選擇刀具和切削用量還可實現(xiàn)硬材料（60HRC）加工；電火花銑削加工（又稱電火花創(chuàng)成加工）是以高速旋轉(zhuǎn)的簡單管狀電極作三維或二維輪廓加工（像數(shù)控銑一樣） ，因此不再需要制造昂貴的成形電極，如日本三菱公司生產(chǎn)的EDSCAN8E 電火花銑削加工機床，配置有電極損耗自動補償系統(tǒng)、CAD/CAM 集成系統(tǒng)、在線自動測量系統(tǒng)和動態(tài)仿真系統(tǒng)，體現(xiàn)了當今電火花加工機床的技術(shù)水平；慢走絲線切割技術(shù)的發(fā)展水平已相當高，功能也相當完善，自動化程度已達到無人看管運行的程度，目前切割速度已達到 300mm /min,加工精度可達±1.5 微米，表面粗糙度達2Ra=01~0.2 微米;精度磨削及拋光已開始使用數(shù)控成形磨床、數(shù)控光學(xué)曲線磨床、數(shù)控連續(xù)軌跡坐標磨床及自動拋光等先進設(shè)備和技術(shù);模具加工過程中的檢測技術(shù)也取得了很大的發(fā)展,現(xiàn)在三坐標測量機除了能高精度地測量復(fù)雜曲面的數(shù)據(jù)外,其良好的溫度補償裝置、可靠的抗振保護能力、嚴密的除塵措施及簡單操作步驟，使得現(xiàn)場自動化檢測成為可能。此外，激光快速成形技術(shù)（RPM）與樹脂澆注技術(shù)在快速經(jīng)濟制模技術(shù)中得到了成功的應(yīng)用。 本課題研究內(nèi)容本課題研究的是杯形件拉深模具的設(shè)計。拉深是主要的沖壓工序之一，應(yīng)用很廣，象汽車、拖拉機的一些罩件、覆蓋件，電器儀表的殼體件及眾多的日用品等都是應(yīng)用拉深成型的。本課題主要研究的是拉深的工藝性。包括分析零件的工藝性，確定工藝方案，了解了模具的基本結(jié)構(gòu)、尺寸公差等級的確定以及拉深時毛坯起皺、斷裂等現(xiàn)象，并提出解決方案。本課題研究方案我國當前拉深技術(shù)發(fā)展受到限制，主要的問題表現(xiàn)在：（1）模具故障，模具故障是沖壓生產(chǎn)中最容易出現(xiàn)的問題，常常造成停產(chǎn)，影響產(chǎn)品生產(chǎn)周期。 　?。?）模具損壞，模具損壞是指模具開裂、折斷、漲開等，處理模具損壞問題。鑒于上述分析，本課題主要是從模具的設(shè)計、制造工藝和模具使用方面尋找原因。首先要審核模具的制造材料是否合適 ，相對應(yīng)的熱處埋工藝是否合理。模具使用時，零件位置、方向等安裝錯誤或螺栓緊固不好。工作高度調(diào)整過低、導(dǎo)柱潤滑不足。送料設(shè)備有故障，壓力機異常等，都會造成模具的損壞。本課題針對以上缺陷提出了解決方案。研究的創(chuàng)新之處本課題的難點以及重點在于解決拉深時起皺現(xiàn)象。拉深過程中，凸緣材料由扇形擠壓成矩形。材料間產(chǎn)生很大的切向壓力，這一壓力猶如壓桿兩端受壓失穩(wěn)似的似凸緣材料失去穩(wěn)定而形成皺折，鑒于以上情況分析，我解決的方法是：（1）模具改進，在流量大的地方設(shè)加強筋（2）改善材質(zhì)，降低延伸率等 研究過程(含完成期限)第一周與指導(dǎo)老師確定設(shè)計題目并制定詳細的設(shè)計要求；第二周調(diào)查、收集、研究現(xiàn)有資料，根據(jù)課題的要求，明確整個論文的任務(wù)和方向；第三周提出多種研究方案，通過分析對比，確定出最優(yōu)方案；第四和第五周以確定的初步方案繪制出工作示意圖或機構(gòu)運動簡圖，確定機構(gòu)組成和各種參數(shù)計算；第六和第七周詳細書寫論文正文內(nèi)容及經(jīng)濟效益分析第八周交由指導(dǎo)老師批改；第九周修改并完善論文。指導(dǎo)教師意見指導(dǎo)教師簽名：年 月 日教研室意見教研室主任簽名：年 月 日院系意見主管領(lǐng)導(dǎo)簽名：年 月 日畢業(yè)論文中文摘要杯形件拉深模具的設(shè)計摘要 本論文應(yīng)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，鞏固與擴充了冷沖壓模具設(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)計的基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，了解了模具的基本結(jié)構(gòu)，提高了計算能力，繪圖能力，熟悉了規(guī)范和標準，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。 。采用拉深模模具設(shè)計制造簡便易行。拉深效果好，能極大地提高生產(chǎn)效率。本設(shè)計共分5章，分別論述了產(chǎn)品工藝分析，工藝計算，模板及零件設(shè)計，模具組立等問題。了解產(chǎn)品用途，并進行沖壓件的工藝性及尺寸公差等級分析，對于一些沖壓件結(jié)構(gòu)不合理或工藝性不好的進行改進并繪制模具總圖和非標準件零件圖。關(guān)鍵詞 工藝分析 工藝設(shè)計 模具組立畢業(yè)論文外文摘要Cup form a deep drawing die designAbstractIn this paper, the application of the professional courses of theoretical and practical knowledge of the production of a cold stamping die design of the practical training of students so as to nurture and enhance the ability to work independently, Consolidation and expansion of the cold stamping die design, the content of classroom teaching, master of cold stamping die design methods and steps. Cold stamping die design to master the basic skills to understand how to mold parts of the process of analysis and how to determine the technology program to understand the basic structure of the mold to enhance the computing power, graphics capability, familiar with the norms and standards, At the same time, there are various courses related to a comprehensive review, the ability to think independently improved. . The use of drawing die design and manufacture of simple mold. Drawing effective and can greatly improve the production efficiency. The design is divided into 5 chapters on analysis of the product technology, technical computing, design templates and components, mold legislation and other issues group.We should understand the product uses, and the process of stamping parts and dimension tolerance level analysis, some unreasonable or stamping process of the bad ones, and we need to mapping tool to improve the overall map and non-standard Parts items.Keywords Process Analysis Process Design Mold GroupCharacteristics 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: （1）．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. （2）．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. （3）．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. Wrinkling that occurs in the stamping of tapered square cups and stepped rectangular cups is investigated. A common characteristic of these two types of wrinkling is that the wrinkles are found at the draw wall that is relatively unsupported. In the stamping of a tapered square cup, the effect of process parameters, such as the die gap and blank-holder force, on the occurrence of wrinkling is examined using finiteelement simulations. The simulation results show that the larger the die gap, the more severe is the wrinkling, and such wrinkling cannot be suppressed by increasing the blank-holder force. In the analysis of wrinkling that occurred in the stamping of a stepped rectangular cup, an actual production part that has a similar type of geometry was examined. The wrinkles found at the draw wall are attributed to the unbalanced stretching of the sheet metal between the punch head and the step edge. An optimum die design for the purpose of eliminating the wrinkles is determined using finite-element analysis. The good agreement between the simulation results and those observed in the wrinkle-free production part validates the accuracy of the finite-element analysis, and demonstrates the advantage of using finite-element analysis for stamping die design.Wrinkling is one of the major defects that occur in the sheet metal forming process. For both functional and visual reasons, wrinkles are usually not acceptable in a finished part. There are three types of wrinkle which frequently occur in the sheet metal forming process: flange wrinkling, wall wrinkling, and elastic buckling of the undeformed area owing to residual elastic compressive stresses. In the forming operation of stamping a complex shape, draw-wall wrinkling means the occurrence of wrinkles in the die cavity. Since the sheet metal in the wall area is relatively unsupported by the tool, the elimination of wall wrinkles is more difficult than the suppression of flange wrinkles. It is well known that additional stretching of the material in the unsupported wall area may prevent wrinkling, and this can be achieved in practice by increasing the blank-holder force; but the application of excessive tensile stresses leads to failure by tearing. Hence, the blank-holder force must lie within a narrow range, above that necessary to suppress wrinkles on the one hand, and below that which produces fracture on the other. This narrow range of blank-holder force is difficult to determine. For wrinkles occurring in the central area of a stamped part with a complex shape, a workable range of blank-holder force does not even exist.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)。 在沖壓臺階方盒形件、錐形方盒形件中發(fā)生的褶皺現(xiàn)象（的原因）已經(jīng)被調(diào)查出。兩種褶皺的共同特點是褶皺都出現(xiàn)在相對無支撐的拉延壁上。沖壓錐形方盒形件時，工藝參數(shù)如凸凹模間隙和壓邊力等對產(chǎn)生褶皺的影響可以用有限元分析檢查出來。（有限元分析的）模擬結(jié)果顯示凸凹模間隙越大,褶皺就越嚴重,并且這種褶皺不能通過增加壓邊力來消減.在對沖壓臺階方盒形件中產(chǎn)生的褶皺的分析中,對一個有相似結(jié)構(gòu)(臺階結(jié)構(gòu))的實際生產(chǎn)中的零件進行檢查.在拉延壁上發(fā)現(xiàn)的褶皺歸因于在沖頭和臺階之間的金屬板材受到的拉伸力的不平衡.通過有限元分析能夠確定最合理的可以減小褶皺的模具的設(shè)計.模擬結(jié)果和對不發(fā)生褶皺產(chǎn)品的觀察結(jié)果的吻合驗證了有限元分析的精確性,并且證明了對沖壓模具設(shè)計進行有限元分析的優(yōu)勢所在.起皺是金屬板料成型中常見的失效形式之一。 由于功能的和視覺效果的原因, 起皺通常不能為零件制品所接受。在金屬板料成型加工中通常存在三種類型的起皺現(xiàn)象：法蘭起皺，側(cè)壁起皺，和由于殘余壓應(yīng)力在未變形區(qū)產(chǎn)生的彈性變形。在沖壓復(fù)雜形狀之間時，拉伸壁起皺就是在模具型腔中形成的起皺。由于金屬板料在拉伸壁區(qū)域內(nèi)相對無支撐，因此消除拉伸壁起皺比抑制法蘭邊起皺要難得多。我們知道在不被支撐的拉伸壁區(qū)域中材料的外力拉伸可以防止起皺，這可以在實踐中通過增加壓邊力而實現(xiàn)，但是運用過大的拉伸力會引起破裂失效。因此，壓邊力必須控制在一定的范圍內(nèi)，一方面增抑制起皺，另一方面防止破裂。合適的壓邊力范圍是很難決定的。因為起皺在沖壓零件的中心位置以一個復(fù)雜的形狀形成，甚至不存在一個合適的壓邊力范圍。