鎖芯套冷沖壓工藝及級進模設(shè)計
鎖芯套冷沖壓工藝及級進模設(shè)計,鎖芯套冷,沖壓,工藝,級進模,設(shè)計
編號
畢業(yè)設(shè)計（論文）
題目： 鎖芯套冷沖壓工藝及級進模設(shè)計
信機 系 機械工程及自動化 專業(yè)
學(xué) 號：
學(xué)生姓名：
指導(dǎo)教師：
3
本科畢業(yè)設(shè)計（論文）
誠 信 承 諾 書
本人鄭重聲明：所呈交的畢業(yè)設(shè)計（論文） 鎖芯套冷沖壓工藝及級進模設(shè)計 是本人在導(dǎo)師的指導(dǎo)下獨立進行研究所取得的成果，其內(nèi)容除了在畢業(yè)設(shè)計（論文）中特別加以標注引用，表示致謝的內(nèi)容外，本畢業(yè)設(shè)計（論文）不包含任何其他個人、集體已發(fā)表或撰寫的成果作品。
班 級：
學(xué) 號：
作者姓名：
信 機 系 機械工程及自動化 專業(yè)
畢 業(yè) 設(shè) 計論 文 任 務(wù) 書
一、題目及專題：
1、題目 鎖芯套冷沖壓工藝及級進模設(shè)計
2、專題
二、課題來源及選題依據(jù)
來源于無錫明達電器有限公司，是電器產(chǎn)品上的一個零件。
模具是機械工程及其自動化專業(yè)的一個專業(yè)方向，選擇模具方向的畢業(yè)設(shè)計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，同時要求學(xué)生要有良好的心理素質(zhì)和仔細認真的作風，對學(xué)生也是一次很好的練習(xí)機會。
三、本設(shè)計（論文或其他）應(yīng)達到的要求：
綜合應(yīng)用各種所學(xué)的專業(yè)知識，在規(guī)定的時間內(nèi)對產(chǎn)品進行冷沖壓工藝分析，制訂完整的沖壓工藝方案，并完成整副模具設(shè)計、數(shù)據(jù)計算和圖紙（所有圖紙折合A0不少于2.5張）繪制，具體內(nèi)容如下：
1．完成模具裝配圖：1張（A0或A1）；
2．零件圖：主要是非標準件零件圖（不少于5張）；
3．冷沖壓工藝卡片：1張 ；
4．設(shè)計說明書：1份（15000字以上，其中參考文獻不少于10篇，外文不少于5篇）；
5．翻譯8000以上外文印刷字符，折合中文字數(shù)約5000字的有關(guān)技術(shù)資料或?qū)I(yè)文獻，內(nèi)容要盡量結(jié)合課題。
四、接受任務(wù)學(xué)生：
班 姓名
五、開始及完成日期：
自2012年11月12日 至2013年5月25日
六、設(shè)計（論文）指導(dǎo)（或顧問）：
指導(dǎo)教師 簽名
簽名
簽名
教研室主任
〔學(xué)科組組長研究所所長〕 簽名
系主任 簽名
冷沖壓工藝卡片
零件名稱
鎖芯套
零件圖號
115401
材料牌號及規(guī)格
08F
0.5×45×L
毛坯種類
帶料
毛坯尺寸
45×L
每毛坯可制件數(shù)
1件/每24.98
工序號
工序名稱
工序內(nèi)容
沖壓設(shè)備
工藝裝備
一次加工數(shù)
工 序 附 圖
10
沖孔
沖4個孔
其中2個定位孔
J23-40
模具和自動送料機構(gòu)
1
20
沖孔
沖2個孔
其中一個預(yù)沖孔
J23-40
模具和自動送料機構(gòu)
1
30
沖裁
預(yù)剪
J23-40
模具和自動送料機構(gòu)
1
40
成形
翻邊
J23-40
模具和自動送料機構(gòu)
1
50
沖裁
切斷
J23-40
模具和自動送料機構(gòu)
1
60
檢驗
檢驗
班級
日期
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)和變形特點進行的沖壓成形分類，可以把成形性質(zhì)相同的成形方法概括成同一個類型并進行系統(tǒng)化的研究。
絕大多數(shù)沖壓成形時毛坯變形區(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?；谶@樣的分析，可以把各種形式?jīng)_壓成形中的毛坯變形區(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(沖壓應(yīng)力圖)與相應(yīng)的兩向應(yīng)變坐標系中(沖壓應(yīng)變圖)以應(yīng)力與應(yīng)變坐標決定的位置來表示。也就是說，沖壓應(yīng)力圖與沖壓應(yīng)變圖中的不同位置都代表著不同的受力情況與變形特點
(1)沖壓毛坯變形區(qū)受兩向拉應(yīng)力作用時，可以分為兩種情況：即σγ>σ>0σt=0和σθ>σγ >0，σt=0。再這兩種情況下，絕對值最大的應(yīng)力都是拉應(yīng)力。以下對這兩種情況進行分析。
1)當σγ>σθ>0且σt=0時，安全量理論可以寫出如下應(yīng)力與應(yīng)變的關(guān)系式：
(1-1) εγ/（σγ-σm）=εθ/（σθ-σm）=εt/（σt -σm）=k
式中 εγ，εθ，εt——分別是軸對稱沖壓成形時的徑向主應(yīng)變、切向主應(yīng)變和厚度方向上的主應(yīng)變；
σγ，σθ，σt——分別是軸對稱沖壓成形時的徑向主應(yīng)力、切向主應(yīng)力和厚度方向上的主應(yīng)力；
σm——平均應(yīng)力，σm=（σγ+σθ+σt）/3；
k——常數(shù)。在平面應(yīng)力狀態(tài)，式（1—1）具有如下形式：
3εγ/（2σγ-σθ）=3εθ/（2σθ-σt）=3εt/[-（σt+σθ）]=k （1—2）
因為σγ>σθ>0，所以必定有2σγ-σθ>0與εθ>0。這個結(jié)果表明：在兩向拉應(yīng)力的平面應(yīng)力狀態(tài)時，如果絕對值最大拉應(yīng)力是σγ，則在這個方向上的主應(yīng)變一定是正應(yīng)變，即是伸長變形。
又因為σγ>σθ>0，所以必定有-（σt+σθ）<0與εt<0，即在板料厚度方向上的應(yīng)變是負的，即為壓縮變形，厚度變薄。
在σθ方向上的變形取決于σγ與σθ的數(shù)值：當σγ=2σθ時，εθ=0；當σγ>2σθ時，εθ<0；當 σγ<2σθ 時，εθ>0。
σθ 的變化范圍是 σγ>=σθ>=0 。在雙向等拉力狀態(tài)時，σγ=σθ ，有式（1—2）得 εγ=εθ>0 及 εt?<0 ；在受單向拉應(yīng)力狀態(tài)時，σθ=0，有式（2—2）可得，εθ=-εγ/2。
根據(jù)上面的分析可知，這種變形情況處于沖壓應(yīng)變圖中的AON范圍內(nèi)（見圖1—1）；而在沖壓應(yīng)力圖中則處于GOH范圍內(nèi)（見圖1—2）。
(1)當σθ>σγ >0且σt=0時，有式（1—2）可知：因為σθ>σγ >0，所以
（2） 定有2σθ>σγ >0與εθ>0。這個結(jié)果表明：對于兩向拉應(yīng)力的平面應(yīng)力狀態(tài)，當σθ的絕對值最大時，則在這個方向上的應(yīng)變一定時正的，即一定是伸長變形。
又因為σγ>σθ>0，所以必定有-（σt+σθ）<0與εt<0，即在板料厚度方向上的應(yīng)變是負的，即為壓縮變形，厚度變薄。
在σθ方向上的變形取決于σγ與σθ的數(shù)值：當σθ=2σγ時，εγ0；當σθ>σγ，εγ<0；當 σθ<2σγ 時，εγ>0。
σγ的變化范圍是 σθ>= σγ>=0 。當σγ=σθ 時，εγ=εθ>0，也就是在雙向等拉力狀態(tài)下，在兩個拉應(yīng)力方向上產(chǎn)生數(shù)值相同的伸長變形；在受單向拉應(yīng)力狀態(tài)時，當σγ=0時，εγ=-εθ /2，也就是說，在受單向拉應(yīng)力狀態(tài)下其變形性質(zhì)與一般的簡單拉伸是完全一樣的。
這種變形與受力情況，處于沖壓應(yīng)變圖中的AOC范圍內(nèi)（見圖1—1）；而在沖壓應(yīng)力圖中則處于AOH范圍內(nèi)（見圖1—2）。
上述兩種沖壓情況，僅在最大應(yīng)力的方向上不同，而兩個應(yīng)力的性質(zhì)以及它們引起的變形都是一樣的。因此，對于各向同性的均質(zhì)材料，這兩種變形是完全相同的。
(1)沖壓毛坯變形區(qū)受兩向壓應(yīng)力的作用，這種變形也分兩種情況分析，即σγ<σθ<
σt=0和σθ<σγ <0，σt=0。
1）當σγ<σθ<0且σt=0時，有式（1—2）可知：因為σγ<σθ<0，一定有2σγ-σθ<0與εγ<0。這個結(jié)果表明：在兩向壓應(yīng)力的平面應(yīng)力狀態(tài)時，如果絕對值最大拉應(yīng)力是σγ<0，則在這個方向上的主應(yīng)變一定是負應(yīng)變，即是壓縮變形。
又因為σγ<σθ<0，所以必定有-（σt+σθ）>0與εt>0，即在板料厚度方向上的應(yīng)變是正的，板料增厚。
在σθ方向上的變形取決于σγ與σθ的數(shù)值：當σγ=2σθ時，εθ=0；當σγ>2σθ時，εθ<0；當 σγ<2σθ 時，εθ>0。
這時σθ 的變化范圍是 σγ與0之間 。當σγ=σθ時，是雙向等壓力狀態(tài)時，故有 εγ=εθ<0；當σθ=0時，是受單向壓應(yīng)力狀態(tài)，所以εθ=-εγ/2。這種變形情況處于沖壓應(yīng)變圖中的EOG范圍內(nèi)（見圖1—1）；而在沖壓應(yīng)力圖中則處于COD范圍內(nèi)（見圖1—2）。
2) 當σθ<σγ <0且σt=0時，有式（1—2）可知：因為σθ<σγ <0，所以一定有2σθσγ <0與εθ<0。這個結(jié)果表明：對于兩向壓應(yīng)力的平面應(yīng)力狀態(tài)，如果絕對值最大是σθ，則在這個方向上的應(yīng)變一定時負的，即一定是壓縮變形。
又因為σγ<σθ<0，所以必定有-（σt+σθ）>0與εt>0，即在板料厚度方向上的應(yīng)變是正的，即為壓縮變形，板厚增大。
在σθ方向上的變形取決于σγ與σθ的數(shù)值：當σθ=2σγ時，εγ=0；當σθ>2σγ，εγ<0；當 σθ<2σγ 時，εγ>0。
這時，σγ的數(shù)值只能在σθ<= σγ<=0 之間變化。當σγ=σθ 時，是雙向等壓力狀態(tài)，所以εγ=εθ<0；當σγ=0時，是受單向壓應(yīng)力狀態(tài)，所以有εγ=-εθ /2>0。這種變形與受力情況，處于沖壓應(yīng)變圖中的GOL范圍內(nèi)（見圖1—1）；而在沖壓應(yīng)力圖中則處于DOE范圍內(nèi)（見圖1—2）。
(1)沖壓毛坯變形區(qū)受兩個異號應(yīng)力的作用，而且拉應(yīng)力的絕對值大于壓應(yīng)力的絕對
值。這種變形共有兩種情況，分別作如下分析。
1）當σγ>0，σθ<0及|σγ|>|σθ|時，由式（1—2）可知：因為σγ>0，σθ<0及|σγ|>|σθ|，所以一定有2σγ-σθ>0及εγ>0。這個結(jié)果表明：在異號的平面應(yīng)力狀態(tài)時，如果絕對值最大應(yīng)力是拉應(yīng)力，則在這個絕對值最大的拉應(yīng)力方向上應(yīng)變一定是正應(yīng)變，即是伸長變形。
又因為σγ>0，σθ<0及|σγ|>|σθ|，所以必定有εθ<0，即在板料厚度方向上的應(yīng)變是負的，是壓縮變形。
這時σθ 的變化范圍只能在σθ=-σγ與σθ=0的范圍內(nèi) 。當σθ=-σγ時，εγ>0εθ<0且|εγ|=|εθ|；當σθ=0時，εγ>0，εθ<0，而且εθ=-εγ/2，這是受單向拉的應(yīng)力狀態(tài)。這種變形情況處于沖壓應(yīng)變圖中的MON范圍內(nèi)（見圖1—1）；而在沖壓應(yīng)力圖中則處于FOG范圍內(nèi)（見圖1—2）。
2）當σθ>0，σγ <0，σt=0及|σθ|>|σγ|時，由式（1—2）可知：用與前項相同的方法分析可得εθ>0。即在異號應(yīng)力作用的平面應(yīng)力狀態(tài)下，如果絕對值最大應(yīng)力是拉應(yīng)力σθ，則在這個方向上的應(yīng)變是正的，是伸長變形；而在壓應(yīng)力σγ方向上的應(yīng)變是負的（εγ<=0），是壓縮變形。
這時σγ 的變化范圍只能在σγ=-σθ與σγ=0的范圍內(nèi) 。當σγ=-σθ時，εθ>0，εγ <0且|εγ|=|εθ|；當σγ=0時，εθ>0，εγ <0，而且εγ=-εθ /
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