汽車轉(zhuǎn)向螺帽墊片沖壓模具設(shè)計(jì)【沖孔落料復(fù)合?！?/h1>
汽車轉(zhuǎn)向螺帽墊片沖壓模具設(shè)計(jì)【沖孔落料復(fù)合?！?沖孔落料復(fù)合模,汽車,轉(zhuǎn)向,螺帽,墊片,沖壓,模具設(shè)計(jì),沖孔,復(fù)合
編號(hào)
無錫太湖學(xué)院
畢業(yè)設(shè)計(jì)（論文）
相關(guān)資料
題目： 鎖芯套冷沖壓工藝及級(jí)進(jìn)模設(shè)計(jì)
信機(jī) 系 機(jī)械工程及自動(dòng)化專業(yè)
學(xué) 號(hào)： 0923215
學(xué)生姓名： 王 吉
指導(dǎo)教師： 鐘建剛（職稱：副教授）
（職稱： ）
2013年5月25日
目 錄
一、畢業(yè)設(shè)計(jì)（論文）開題報(bào)告
二、畢業(yè)設(shè)計(jì)（論文）外文資料翻譯及原文
三、學(xué)生“畢業(yè)論文（論文）計(jì)劃、進(jìn)度、檢查及落實(shí)表”
四、實(shí)習(xí)鑒定表
無錫太湖學(xué)院
畢業(yè)設(shè)計(jì)（論文）
開題報(bào)告
題目： 鎖芯套冷沖壓工藝及級(jí)進(jìn)模設(shè)計(jì)
信機(jī) 系 機(jī)械工程及自動(dòng)化 專業(yè)
學(xué) 號(hào)： 0923215
學(xué)生姓名： 王 吉
指導(dǎo)教師： 鐘建剛 （職稱：副教授）
（職稱： ）
2012年11月22日
課題來源
來源于無錫明達(dá)電器有限公司，是電器產(chǎn)品上的一個(gè)零件。
科學(xué)依據(jù)（包括課題的科學(xué)意義；國(guó)內(nèi)外研究概況、水平和發(fā)展趨勢(shì)；應(yīng)用前景等）
（1）課題科學(xué)意義
模具是機(jī)械工程及其自動(dòng)化專業(yè)的一個(gè)專業(yè)方向，選擇模具方向的畢業(yè)設(shè)計(jì)題目完全符合本專業(yè)的要求，從應(yīng)用性方面來說，模具又是生產(chǎn)效率極高的工具之一，能有效保證產(chǎn)品一致性和可更換性，具有很好的發(fā)展前途和應(yīng)用前景。連續(xù)模在模具中技術(shù)含量高，制造、裝配難度大，因此本課題研究連續(xù)模的沖壓工藝、排樣方案、模具結(jié)構(gòu)分析等方面，同時(shí)要求學(xué)生要有良好的心理素質(zhì)和仔細(xì)認(rèn)真的作風(fēng)，對(duì)學(xué)生也是一次很好的鍛煉機(jī)會(huì)。
（2）研究狀況及其發(fā)展前景
隨著電子、信息等高新技術(shù)的不斷發(fā)展，模具CAD/CAE/CAM正向集成化、三維化、智能化和網(wǎng)絡(luò)化方向發(fā)展。模具CAD/CAE/CAM技術(shù)是模具設(shè)計(jì)、制造技術(shù)的發(fā)展方向，模具和工件的檢測(cè)數(shù)字、模具軟件功能集成化、模具設(shè)計(jì)、分析及制造的三維化、模具產(chǎn)業(yè)的逆向工程以及模具軟件應(yīng)用的網(wǎng)絡(luò)化是主趨勢(shì)。
模具發(fā)展日新月異，今后其發(fā)展趨勢(shì)大致包括以下方面：
1.發(fā)展高效模具 對(duì)于大批量生產(chǎn)用模具，應(yīng)向高效率發(fā)展。如為了適應(yīng)當(dāng)前高速壓力機(jī)的使用，應(yīng)發(fā)展多工位級(jí)進(jìn)模以提高生產(chǎn)效率。
2.發(fā)展簡(jiǎn)易模具 對(duì)于小批量生產(chǎn)用模具，為降低成本，縮短模具制造周期，盡量發(fā)展薄板沖模，鋅合金、低熔點(diǎn)合金，環(huán)氧樹脂等簡(jiǎn)易模。
3.發(fā)展多功能模具 為了提高效率和保證制品的質(zhì)量，要采用多工位級(jí)進(jìn)模及具有組合功能的雙色，多色塑料注射模等。
4.發(fā)展高壽命模具 高效率必然需要高壽命，為了達(dá)到高壽命，除模具本身結(jié)構(gòu)優(yōu)化外，還要對(duì)材料的選用和熱處理，表面強(qiáng)化技術(shù)予以開發(fā)和創(chuàng)新。
5.發(fā)展高精度模具 要實(shí)現(xiàn)模具的高精度，在模具的設(shè)計(jì)與加工中必然要使用高精度加工設(shè)備和高技術(shù)加工工藝。要進(jìn)一步發(fā)展數(shù)控機(jī)床和加工中心的使用，要發(fā)展CAD/CAE/CIM等高新技術(shù)。
研究?jī)?nèi)容
本課題研究連續(xù)模的沖壓工藝、排樣方案、模具結(jié)構(gòu)分析等方面，通過平時(shí)的學(xué)習(xí)和專業(yè)老師的精心指導(dǎo)以及查閱大量資料，從而能夠有序的完成模具的設(shè)計(jì)過程。所以通過此次論文寫作，我更進(jìn)一步體會(huì)了模具在制造業(yè)中的作用，在本篇論文中我將較多的研究和調(diào)查沖壓模具，探討沖壓模具在模具工業(yè)中現(xiàn)在的研究狀況和將來的發(fā)展，為以后的實(shí)際工作打下了堅(jiān)實(shí)的理論基礎(chǔ)。
擬采取的研究方法、技術(shù)路線、實(shí)驗(yàn)方案及可行性分析
首先，要對(duì)零件的工藝進(jìn)行分析，課題的鎖芯套零件的方按，采用先沖孔、再預(yù)剪、之后翻邊，最后落料的工藝。其次，是對(duì)零件的排樣方按的設(shè)定，通過計(jì)算，選擇最優(yōu)的排樣方按。之后，則是對(duì)沖壓凹凸模的設(shè)計(jì)計(jì)算，合理的沖裁間隙關(guān)系著沖裁模的沖裁質(zhì)量和沖裁模具本身的壽命，也是模具設(shè)計(jì)中較為重要的一個(gè)環(huán)節(jié)。最后是模架和壓力機(jī)的選用。
研究計(jì)劃及預(yù)期成果
研究計(jì)劃：
2012年11月12日-2012年12月2日：按照任務(wù)書要求查閱論文相關(guān)參考資料，填寫畢業(yè)設(shè)計(jì)開題報(bào)告書。
2012年12月3日-2013年3月1日：工作計(jì)劃、進(jìn)度。
2013年3月4日-2013年3月15日：查閱參考資料，學(xué)習(xí)并翻譯一篇與畢業(yè)設(shè)計(jì)相關(guān)的英文材料。
2013年3月18日-2013年4月12日：沖壓工藝設(shè)計(jì)，模具結(jié)構(gòu)設(shè)計(jì)，刃口尺寸和主要零件結(jié)構(gòu)設(shè)計(jì)和尺寸計(jì)算。
2013年4月15日-2013年5月3日：繪制模具裝配圖和零件圖。
2013年5月6日-2013年5月25日：工藝文件、畢業(yè)論文撰寫和修改工作。
預(yù)期成果：
1．完成模具裝配圖：1張（A0或A1）；
2．零件圖：主要非標(biāo)準(zhǔn)件零件圖（不少于5張）；
3．冷沖壓工藝卡片：1張；
4．設(shè)計(jì)說明書：1份；
5．翻譯8000以上外文印刷字符或譯出約5000左右漢字的有關(guān)技術(shù)資料或?qū)I(yè)文獻(xiàn)，內(nèi)容要盡量結(jié)合課題。
特色或創(chuàng)新之處
①該課題主要針對(duì)鎖芯套零件，在對(duì)零件沖孔、翻邊和落料的成形工藝分析的基礎(chǔ)上，提出了該零件采用多工位級(jí)進(jìn)模的沖壓方案
②在排樣方按上采用利用率高的斜排。
已具備的條件和尚需解決的問題
①了解沖壓的知識(shí)，比如說模具零件的認(rèn)識(shí)和沖壓機(jī)的工作原理。
②理論與實(shí)踐有著不可避免的差距，由于沒有設(shè)計(jì)經(jīng)驗(yàn)，在實(shí)際設(shè)計(jì)時(shí)，會(huì)遇到許多問題。在零件排樣和料帶設(shè)計(jì)中，由于實(shí)際定位和導(dǎo)向零件的設(shè)計(jì)，需要做一定的修改。
指導(dǎo)教師意見
指導(dǎo)教師簽名：
年 月 日
教研室（學(xué)科組、研究所）意見
教研室主任簽名：
年 月 日
系意見
主管領(lǐng)導(dǎo)簽名：
年 月 日
英文原文
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 form 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 form 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 to 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 it is assumed that the stress perpendicular to the blank surface equal 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 that 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 kind of stamping forming can be denoted by the point in the coordinates of the plane principal stress(diagram of the stamping stress) and the coordinates of the corresponding plane principal stains (diagram of the stamping strain). The different points in the figures of the stamping stress and strain possess different stress state and deformation characteristics.
(1)When the deformation zone of the stamping blank is subjected toplanetensile stresses, it can be divided into two cases, that is σγ>σθ>0,σt=0andσθ>σγ >0,σt=0.In both cases, the stress with the maximum absolute value is always a tensile stress. These two cases are analyzed respectively as follows.
2)In the case that σγ>σθ>0andσt=0, according to the integral theory, the relationships between stresses and strains are:
εγ/（σγ-σm）=εθ/（σθ-σm）=εt/（σt -σm）=k 1.1
where, εγ，εθ，εt are the principal strains of the radial, tangential and thickness directions of the axial symmetrical stamping forming; σγ，σθand σtare the principal stresses of the radial, tangential and thickness directions of the axial symmetrical stamping forming;σm is the average stress,σm=（σγ+σθ+σt）/3; k is a constant.
In plane stress state, Equation 1.1
3εγ/（2σγ-σθ）=3εθ/（2σθ-σt）=3εt/[-（σt+σθ）]=k 1.2
Since σγ>σθ>0,so 2σγ-σθ>0 and εθ>0.It indicates that in plane stress state with two axial tensile stresses, if the tensile stress with the maximum absolute value is σγ, the principal strain in this direction must be positive, that is, the deformation belongs to tensile forming.
In addition, because σγ>σθ>0，therefore -（σt+σθ）<0 and εt<0. The strain in the thickness direction of the blankεt is negative, that is, the deformation belongs to compressive forming, and the thickness decreases.
The deformation condition in the tangential direction depends on the values ofσγ and σθ. When σγ=2σθ,εθ=0； when σγ>2σθ,εθ<0；and when σγ<2σθ ,εθ>0.
The range of σθ is σγ>=σθ>=0 . In the equibiaxial tensile stress state σγ=σθ ，according to Equation 1.2,εγ=εθ>0 and εt?<0 . In the uniaxial tensile stress stateσθ=0，according to Equation 1.2 εθ=-εγ/2.
According to above analysis, it is known that this kind of deformation condition is in the region AON of the diagram of the diagram of the stamping strain (see Fig .1.1), and in the region GOH of the diagram of the stamping stress (see Fig.1.2).
2)When σθ>σγ >0 and σt=0, according to Equation 1.2 , 2σθ>σγ >0 and εθ>0,This result shows that for the plane stress state with two tensile stresses, when the absoluste value of σθ is the strain in this direction must be positive, that is, it must be in the state of tensile forming.
Also becauseσγ>σθ>0，therefore -（σt+σθ）<0 and εt<0. The strain in the thickness direction of the blankεt is negative, or in the state of compressive forming, and the thickness decreases.
The deformation condition in the radial direction depends on the values ofσγ and σθ. When σθ=2σγ,εγ0;when σθ>σγ,εγ<0;and when σθ<2σγ,εγ>0.
The range of σγ is σθ>= σγ>=0 .When σγ=σθ,εγ=εθ>0, that is, in equibiaxial tensile stress state, the tensile deformation with the same values occurs in the two tensile stress directions; when σγ=0, εγ=-εθ /2, that is, in uniaxial tensile stress state, the deformation characteristic in this case is the same as that of the ordinary uniaxial tensile.
This kind of deformation is in the region AON of the diagram of the stamping strain (see Fig.1.1), and in the region GOH of the diagram of the stamping stress (see Fig.1.2).
Between above two cases of stamping deformation, the properties ofσθandσγ, and the deformation caused by them are the same, only the direction of the maximum stress is different. These two deformations are same for isotropic homogeneous material.
(1)When the deformation zone of stamping blank is subjected to two compressive stressesσγandσθ(σt=0), it can also be divided into two cases, which are σγ<σθ<0,σt=0 and σθ<σγ <0,σt=0.
1）When σγ<σθ<0 and σt=0, according to Equation 1.2, 2σγ-σθ<0與εγ=0.This result shows that in the plane stress state with two compressive stresses, if the stress with the maximum absolute value is σγ<0, the strain in this direction must be negative, that is, in the state of compressive forming.
Also because σγ<σθ<0, therefore -（σt +σθ）>0 and εt>0.The strain in the thickness direction of the blankεt is positive, and the thickness increases.
The deformation condition in the tangential direction depends on the values ofσγ and σθ.When σγ=2σθ,εθ=0;when σγ>2σθ,εθ<0;and when σγ<2σθ ,εθ>0.
The range of σθ is σγ<σθ<0.When σγ=σθ,it is in equibiaxial tensile stress state, henceεγ=εθ<0; when σθ=0,it is in uniaxial tensile stress state, hence εθ=-εγ/2.This kind of deformation condition is in the region EOG of the diagram of the stamping strain (see Fig.1.1), and in the region COD of the diagram of the stamping stress (see Fig.1.2).
2）When σθ<σγ <0and σt=0, according to Equation 1.2,2σθ-σγ <0 and εθ<0. This result shows that in the plane stress state with two compressive stresses, if the stress with the maximum absolute value is σθ, the strain in this direction must be negative, that is, in the state of compressive forming.
Also becauseσθ<σγ <0 , therefore -（σt +σθ）>0 and εt>0.The strain in the thickness direction of the blankεt is positive, and the thickness increases.
The deformation condition in the radial direction depends on the values ofσγ and σθ. When σθ=2σγ, εγ=0; when σθ>2σγ,εγ<0; and when σθ<2σγ ,εγ>0.
The range of σγ is σθ<= σγ<=0 . When σγ=σθ , it is in equibiaxial tensile stress state, hence εγ=εθ<0; when σγ=0, it is in uniaxial tensile stress state, hence εγ=-εθ /2>0.This kind of deformation is in the region GOL of the diagram of the stamping strain (see Fig.1.1), and in the region DOE of the diagram of the stamping stress (see Fig.1.2).
(3) The deformation zone of the stamping blank is subjected to two stresses with opposite signs, and the absolute value of the tensile stress is larger than that of the compressive stress. There exist two cases to be analyzed as follow:
1)When σγ>0, σθ<0 and |σγ|>|σθ|, according to Equation 1.2, 2σγ-σθ>0 and εγ>0.This result shows that in the plane stress state with opposite signs, if the stress with the maximum absolute value is tensile, the strain in the maximum stress direction is positive, that is, in the state of tensile forming.
Also because σγ>0, σθ<0 and |σγ|>|σθ|, therefore εθ<0. The strain in the compressive stress direction is negative, that is, in the state of compressive forming.
The range of σθ is 0>=σθ>=-σγ. When σθ=-σγ, then εγ>0,εθ<0 , and |εγ|=|εθ|;when σθ=0, then εγ>0,εθ<0, and εθ=-εγ/2, it is the uniaxial tensile stress state. This kind of deformation condition is in the region MON of the diagram of the stamping strain (see Fig.1.1), and in the region FOG of the diagram of the stamping stress (see Fig.1.2).
2)When σθ>0, σγ <0,σt=0 and |σθ|>|σγ|, according to Equation 1.2, by
means of the same analysis mentioned above, εθ>0, that is, the deformation zone is in the plane stress state with opposite signs. If the stress with the maximum absolute value is tensile stress σθ, the strain in this direction is positive, that is, in the state of tensile forming. The strain in the radial direction is negative （εγ<=0）, that is, in the state of compressive forming.
The range of σγ is 0>=σγ>=-σθ. When σγ=-σθ, then εθ>0,εγ <0 and |εγ|=|εθ|; when σγ=0, then εθ>0,εγ <0, andεγ=-εθ /2. This kind of deformation condition is in the region COD of the diagram of the stamping strain (see Fig.1.1), and in the region AOB of the diagram of the stamping stress (see Fig.1.2).
Although the expressions of these two cases are different, their deformation essences are the same.
(4) The deformation zone of the stamping blank is subjected to two stresses with opposite signs, and the absolute value of the compressive stress is larger than that of the tensile stress. There exist two cases to be analyzed as follows:
1)When σγ>0,σθ<0 and |σθ|>|σγ|, according to Equation 1.2, 2σθ- σγ<0 and εθ<0.This result shows that in plane stress state with opposite signs, if the stress with the maximum absolute value is compressive stress σθ, the strain in this direction is negative, or in the state of compressive forming.
Also because σγ>0 and σθ<0, therefore 2σγ- σθ<0 and εγ>0. The strain in the tensile stress direction is positive, or in the state of tensile forming.
The range of σγis 0>=σγ>=-σθ.When σγ=-σθ, then εγ>0,εθ<0, and εγ=-εθ;when σγ=0, then εγ>0,εθ<0, and εγ=-εθ/2. This kind of deformation is in the region LOM of the diagram of the stamping strain (see Fig.1.1), and in the region EOF of the diagram of the stamping stress (see Fig.1.2).
2)When σθ>0, σγ <0 and |σγ|>|σθ|, according to Equation 1.2 and by means of the same analysis mentioned above,εγ< 0.This result shows that in plane stress state with opposite signs, if the stress with the maximum absolute value is compressive stress σγ,the strain in this direction is negative, or in the state of compressive forming, The strain in the tensile stress direction is positive, or in the state of tensile forming.
The range of σθ is 0>=σθ>=-σγ.When σθ=-σγ, then εθ>0,εγ <0, and εθ=-εγ;when σθ=0, then εθ>0,εγ <0, and εθ=-εγ/2. Such deformation is in the region DOF of the diagram of the stamping strain (see Fig.1.1), and in the region BOC of the diagram of the stamping stress (see Fig.1.2).
The four deformation conditions are related to the corresponding stamping forming methods. Their relationships are labeled with letters in Fig.1.1 and Fig.1.2.
The four deformation conditions analyzed above are applicable to all kinds of plane stress states, that is, the four deformation conditions can sum up all kinds of stamping forming in to two types, tensile and compressive. When the stress with the maximum absolute value in the deformation zone of the stamping blank is tensile, the deformation along this stress direction must be tensile. Such stamping deformation is called tensile forming. Based on above analysis, the tensile forming occupies five regions MON, AON, AOB, BOC and COD in the diagram of the stamping stain; and four regions FOG, GOH, AOH and AOB in the diagram of the stamping stress.
When the stress with the maximum absolute value in the deformation zone of the stamping blank is compressive, the deformation along this stress direction must be compressive. Such stamping deformation is called compressive forming. Based on above analysis, the compressive forming occupies five regions LOM, HOL, GOH, FOG and DOF in the diagram of the stamping strain; and four regions EOF, DOE, COD and BOC in the diagram of the stamping stress.
MD and FB are the boundaries of the two types of forming in the diagrams of the stamping strain and stress respectively. The tensile forming is located in the top right of the boundary, and the compressive forming is located in the bottom left of the boundary.
Because the stress produced by the plastic deformation of the material is related to the strain caused by the stress, there also exist certain relationships between the diagrams of the stamping stress and strain. There are corresponding locations in the diagrams of the stamping stress and strain for every stamping deformation. According to the state of stress or strain in the deformation zone of the forming blank, and using the boundary line in the diagram of the stamping stress MD or the boundary line in the diagram of the stamping strain FB, it is easy to know the properties and characteristics of the stamping forming.
The locations in the diagrams of the stamping stress and strain for various stress states and the corresponding relationships of the two diagrams are listed in Table 1.1.It shows that the geometrical location for every region are different in the diagrams of the stamping stress and strain, but their sequences in the two diagrams are the same. One key point is that the boundary line between the tensile and the compressive forming is an inclined line at 45°to the coordinate axis. The characteristics of the stamping technique for tensile and compressive forming are listed in Table 1.2.
Table 1.2 clearly shows that in the deformation zone of the blank, the characteristics of the force and deformation, and the patterns relevant to the deformation for each stamping method are the same. Therefore, in addition to the research on the detail stamping method, it is feasible to study stamping systematically and comprehensively. The characteristic of the systematic research is to study the common principle of all different types of stamping methods. The results of the systematic research are applicable to all stamping methods. The research on the properties and limit of the sheet metal stamping has been carried out in certain extent. The contents of the research on the stamping forming limit by using systematic method are shown in Fig.1.3.
State of stress
Location in the diagram of the stamping strain
Location in the diagram of the stamping stress
Types of deformation
Stress Strain
Biaxial tensile stress state
σθ>0,σγ>0
σγ> σθ
AON
GOH
+ +
Tensile
σθ>σγ
AOC
AOH
+ +
Tensile
Biaxial compressive stress state
σθ<0,σγ<0
σγ< σθ
EOG
COD
— —
Compressive
σθ<σγ
GOL
DOE
— —
Compressive
Stateof stress with opposite signs
σγ>0,σθ<0
|σγ|>|σθ|
MON
FOG
+ +
Tensile
|σθ|>|σγ|
LOM
EOF
— —
Compressive
State of stress with opposite signs
σθ>0,σγ<0
|σθ|>|σγ|
COD
AOB
+ +
Tensile
|σγ|> |σθ|
DOE
BOC
— —
Compressive
Table 1.1 Comparison between states of stress and strain in stamping
Table 1.2 Comparison between tensile and compressive forming
Item
Tensile forming
Compressive forming
Representation of the quality problem in the deformation zone
Fracture in the deformation zone due to excessive deformation
Instability wrinkle caused by compressive stress
Forming limit
1． Mainly depends on the plasticity of the material, and is irrelevant to the thickness
2． Can be estimated by extensibility or the forming limit DLF
1． Mainly depends on the loading capability in the force transferring zone
2． Depends on the anti-instability capability
3． Has certain relationship to the blank thickness
Variation of the blank thickness in the deformation zone
Thinning
Thickening
Methods to improve forming limit
1． Improve the plasticity of the material
2． Decrease local deformation, and increase deformation uniformity
3． Adopt an intermediate heat treatment process
1． Adopt multi-pass forming process
2． Change the mechanics relationship between the force transferring and deformation zones
3． Adopt anti-wrinkle measures
Fig.1.1 Diagram of stamping strain Fig.1.2 Diagram of stamping stress
Fig.1.3 Examples for systematic research methods
中文譯文
沖壓變形
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。
分離工序是使坯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。其中有以沖孔、落料應(yīng)用最廣。變形工序是使坯料的一部分相對(duì)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，沖壓成形就是毛坯的變形區(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)的應(yīng)力狀態(tài)和變形性質(zhì)是決定沖壓成形性質(zhì)的基本因素。因此，根據(jù)變形區(qū)應(yīng)力狀態(tài)和變形特點(diǎn)進(jìn)行的沖壓成形分類，可以把成形性質(zhì)相同的成形方法概括成同一個(gè)類型并進(jìn)行系統(tǒng)化的研究。
絕大多數(shù)沖壓成形時(shí)毛坯變形區(qū)均處于平面應(yīng)力狀態(tài)。通常認(rèn)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(rèn)為垂直于板面方向的應(yīng)力為零，使板材毛坯產(chǎn)生塑性變形的是作用于板面方向上相互垂直的兩個(gè)主應(yīng)力。由于板厚較小，通常都近似地認(rèn)為這兩個(gè)主應(yīng)力在厚度方向上是均勻分布的?；谶@樣的分析，可以把各種形式?jīng)_壓成形中的毛