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西京學(xué)院畢業(yè)設(shè)計（論文）任務(wù)書
指導(dǎo)教師
姓名
盛尚雄
畢業(yè)設(shè)計（論文）題目
真空助力器殼體成形與設(shè)計
職稱
教授
題目類型
理工類
□√ 工程設(shè)計 □科學(xué)實驗 □軟件開發(fā) □理論研究 □綜合
經(jīng)管文
□理論性研究 □應(yīng)用性研究 □應(yīng)用軟件設(shè)計 □調(diào)查報告
選題學(xué)生
史浩
教學(xué)單位
機電工程系
學(xué)號
1109331154
專業(yè)班級
機制1130
一、 題目簡介：（含來源、目的、意義）
真空助力器殼體制造的技術(shù)發(fā)展決定了真空助力器的使用壽命和汽車行業(yè)的發(fā)展，它已成為衡量一個國家制造業(yè)水平高低的重要標志。在現(xiàn)有真空助力器殼體內(nèi)部平板毛坯局部脹形產(chǎn)生的塑性變形不局限在所謂的直接變形區(qū)范圍內(nèi)的材料, 而比直接變形區(qū)大得多的范圍內(nèi)的材料都產(chǎn)生了塑性變形此范圍的大小,取決于板材本身的極限強度與屈服強度之比值，比值越大則變形區(qū)的范圍相對地就越大。故真空助力器殼體中的成形脹形能達到的高徑比主要由材料的極限強度與屈服強度的比值及延伸率所決定，研究設(shè)計一種材料為08 F 鋼, 其脹形高徑比可達0.4的真空助力器殼體成形與設(shè)計，以滿足工程設(shè)計的要求。
二、主要任務(wù)：
真空助力器固定在車身上，其輸出端與液壓制動主缸相連，控制端通過杠桿機構(gòu)與制動踏板相連，低壓腔通過軟管與發(fā)動機相連。本次研究的主要任務(wù)是把真空助力器殼體成型設(shè)計出來。要求畫出其真空助力器殼體成形的結(jié)構(gòu)示意圖及主要結(jié)構(gòu)裝配圖、零件圖，殼體成形工藝示意圖。
三、主要內(nèi)容與基本要求：（有實驗環(huán)節(jié)的要提出主要技術(shù)指標要求）
真空助力器分為前殼體和后殼體，真空助力器是五十鈴汽車實行國產(chǎn)化的一項產(chǎn)品其中前殼體、后殼體是兩個板沖件, 形狀復(fù)雜, 要求高。此兩個件的制造成為該項產(chǎn)品能否開發(fā)成功的關(guān)鍵問題, 對殼體的毛胚部分進行小端的平板局部脹形估計及計算，對該殼體進行邏輯分析與力學(xué)計算，作出合理的設(shè)計。畫出殼體總裝圖;；最后對大端的成形進行分析研究，針對其技術(shù)性能不足之處，進行改進與創(chuàng)新，設(shè)計具有較好實用價值的新型裝備。畫出總裝圖或部裝圖及零件圖。
四、計劃進度：（包括時間劃分和各階段主要工作內(nèi)容，按周次填寫）
第1周-第2周：查閱真空助力器殼體相關(guān)資料準備開題。進行可行性分析并撰寫文獻綜述，最后完成開題報告。
第3周：查閱并篩選出與畢業(yè)設(shè)計內(nèi)容相關(guān)性較好的外文資料兩篇，并對其進行翻譯，以便在后面的畢業(yè)論文中對其進行參考。
第4周-第8周：在篩選相關(guān)資料的基礎(chǔ)上，初步確定設(shè)計方案。首先對常見的真空助力器殼體進行分類整理，然后在已有的資料的基礎(chǔ)上進行改進或者是創(chuàng)新設(shè)計出有效真空助力器殼體，最后進行進行三維仿真建模，畫出機構(gòu)總裝圖;并對該殼體進行邏輯分析力學(xué)計算。
第9周-第11周：按照計算過程檢查每一步計算數(shù)據(jù)并整合資料。完成畢業(yè)論文的撰寫工作和附件的整理并完成裝配圖的繪制。向?qū)熖峤划厴I(yè)設(shè)計（論文）初稿。
第12周：完成畢業(yè)論文的修改工作，正式提交畢業(yè)設(shè)計（論文）終稿。
第13周：根據(jù)教務(wù)科要求整理畢業(yè)設(shè)計相關(guān)資料并裝訂成冊，進一步熟悉畢業(yè)設(shè)計內(nèi)容，準備畢業(yè)答辯。
第14周：總結(jié)工作，推薦優(yōu)秀論文，收集整理有關(guān)檔案資料。
五、主要參考文獻：(要寫清參考文獻名稱、作者、出版社、出版時間)
[1] 周天瑞，等．汽車覆蓋件沖壓成形技術(shù)[M]． 北京：機械工
業(yè)出版社．2000．
[2] 安文寶。劉晶波，等．沖模斜楔傳動機構(gòu)的設(shè)計口]．模具工
業(yè)，2001 (7)：25—28．
[3] 李楊，王曉東．真空助力器工作原理及其自動檢測過程分析．機械工程師，2010(3)：23-25．
[4] 楊維和．汽車制動真空助力器的工作原理與性能計算．汽車技術(shù)，1991(10)：9一l3，51．
[5] 王小華，常春·沖模斜楔機構(gòu)的角度優(yōu)化[J]．模具制造，
2004 (3)： 12—13．
[6] 杜平安．有限元網(wǎng)格劃分的基本原則．機械設(shè)計與制造，2000(2)：34-36．
[7] 劉寶波，譚柏春．基于ANSYS Workbench的集裝箱雙面吊車架的強度設(shè)計．現(xiàn)代制造工程，2011(9)：130—133．
[8] 沈軍民,沈詠軍,等,關(guān)于真空助力器助力比與最大助力點關(guān)系的研究.中國測試技術(shù),2006,7
[9] 楊維和,汽車制動真空助力器的工作原理與性能計算 . 汽車技術(shù),1991.10
[10] 桂健生,制動真空伺服器, .輕型汽車技術(shù),2002,2.
[11] 真空助力器隨動段力特性設(shè)計與評價方法探討.重慶市首屆工程師大會論文集。??
[12] 趙凱.基于反求設(shè)計的汽車真空助力器總成的研究[D].成都：西南交通大學(xué)，2007.
[13] Borenstein J.Ulrich I The Guide Cane--A Computerized Travel Aid for the Active Guidance of Blind Pedestrians 1997
[14]Gearbox?shell?machining?process?design,Serope?kalpakjian,?Steven?R.Schmid,《Manufacturing?Engineering?and?Technology—Machining》，2004年3月第1版.
六、工作量要求
（1）查閱文獻資料不少于12篇，其中外文資料不少于2篇；
（2）完成畢業(yè)設(shè)計（論文）不少于8000字。
（3）完成開題報告一份；
（4）完成離心增力夾具的主要零部件圖共2張A3圖紙；
指導(dǎo)教師
（簽名）：
年 月 日
學(xué) 生
（簽名）：
年 月 日
教研室意見：
教研室主任：
年 月 日
注：本表一式三份。一份交教學(xué)單位存檔，一份交學(xué)生，一份指導(dǎo)教師自留。
Characteristics of Stamping and Properties of
Sheet Metal Forming
1．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.
沖壓成形的特點與板材沖壓成形性能
1．概述
沖壓是通過模具使板材產(chǎn)生塑性變形而獲得成品零件的一次成形工藝方法。由于沖壓通常在冷態(tài)下進行，因此也稱為冷沖壓。只有當(dāng)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）．材料利用率高。
（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．沖壓成行的特點
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(dāng)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(dāng)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(dāng)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(dāng)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)。
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