外文翻譯=沖壓變形=中英文翻譯

遼寧科技學院本科生畢業(yè)設計（論文） 第 1 頁 附錄 1 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. When the deformation zone of the stamping blank is subjected toplanetensile stresses, it can be divided into two cases, that is 0,t=0and 0,t=0.In 遼寧科技學院本科生畢業(yè)設計（論文） 第 2 頁 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 0andt=0, according to the integral theory, the relationships between stresses and strains are: /（ -m） =/（ -m） =t/（ t -m） =k （ 1.1） where, ， ， t are the principal strains of the radial, tangential and thickness directions of the axial symmetrical stamping forming; ， and tare the principal stresses of the radial, tangential and thickness directions of the axial symmetrical stamping forming;m is the average stress,m=（ +t） /3; k is a constant. In plane stress state, Equation 1.1 3/（ 2-） =3/（ 2-t） =3t/-（ t+） =k （ 1.2） Since 0,so 2-0 and 0.It indicates that in plane stress state with two axial tensile stresses, if the tensile stress with the maximum absolute value is , the principal strain in this direction must be positive, that is, the deformation belongs to tensile forming. In addition, because 0， therefore -（ t+） 2,0. The range of is =0 . In the equibiaxial tensile stress state = ，according to Equation 1.2,=0 and t 0 and t=0, according to Equation 1.2 , 2 0 and 0,This result shows that for the plane stress state with two tensile stresses, when the 遼寧科技學院本科生畢業(yè)設計（論文） 第 3 頁 absoluste value of is the strain in this direction must be positive, that is, it must be in the state of tensile forming. Also because0， therefore -（ t+） ,0. The range of is = =0 .When =,=0, that is, in equibiaxial tensile stress state, the tensile deformation with the same values occurs in the two tensile stress directions; when =0, =- /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 ofand, 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 stressesand(t=0), it can also be divided into two cases, which are 0 and t0.The strain in the thickness direction of the blankt is positive, and the thickness increases. The deformation condition in the tangential direction depends on the values of and .When =2,=0;when 2,0. 遼寧科技學院本科生畢業(yè)設計（論文） 第 4 頁 The range of is 0 and t0.The strain in the thickness direction of the blankt is positive, and the thickness increases. The deformation condition in the radial direction depends on the values of and . When =2, =0; when 2,0. The range of is 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). 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 0, |, according to Equation 1.2, 2-0 and 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 0, |, therefore =-. When =-, then 0,0,0, |, according to Equation 1.2, by means of the same analysis mentioned above, 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 , the strain in this direction is positive, that is, in the state of tensile forming. The strain in the radial direction is negative （ =-. When =-, then 0, 0, 0,|, according to Equation 1.2, 2- 0 and 0. The strain in the tensile stress direction is positive, or in the state of tensile forming. The range of is 0=-.When =-, then 0,0,0, |, according to Equation 1.2 and by means of the same analysis mentioned above,=-.When =-, then 0, 0, =-.When =-, then 0, 0, 0 t=0和 0， t=0。再這兩種情況下，絕對值最大的應力都是拉應力。以下對這兩種情況進行分析。 1)當 0 且 t=0 時，安全量理論可以寫出如下應力與應變的關(guān)系式： 遼寧科技學院本科生畢業(yè)設計（論文） 第 10頁 (1-1) /（ - m） = /（ - m） = t/（ t - m） =k 式中 ， ， t 分 別 是 軸對稱沖壓 成 形時 的 徑向 主 應變 、切向主 應 變和厚度方向上的主 應變 ； ， ， t 分 別 是 軸對稱沖壓 成 形時 的 徑向 主 應 力、切向主 應 力和厚度方向上的主 應 力； m 平均 應 力， m=（ + + t） /3； k 常數(shù) 。在平面 應 力 狀態(tài) ，式（ 1 1）具有如下形式： 3 /（ 2 - ） =3 /（ 2 - t） =3 t/-（ t+ ） =k （ 1 2） 因為 0，所以必定有 2 - 0 與 0。 這個結(jié) 果表明：在 兩向拉應 力的平面 應 力 狀態(tài)時 ，如果 絕對 值最大 拉應 力是 ，則在這個方向上的主應變一定是正應變，即是伸長變形。 又因為 0，所以必定有 -（ t+ ） 2 時， 0。 的變化范圍是 = =0 。在雙向等拉力狀態(tài)時， = ，有式（ 1 2）得 = 0 及 t 0 且 t=0 時，有式（ 1 2）可知：因為 0，所以 1） 定有 2 0 與 0。這個結(jié)果表明：對于兩向拉應力的平面應力狀態(tài)，當 的絕對值最大時，則在這個方向上的應變一定時正的，即一定是伸長變形。 又因為 0，所以必定有 -（ t+ ） ， 0。 遼寧科技學院本科生畢業(yè)設計（論文） 第 11頁 的變化范圍是 = =0 。當 = 時， = 0， 也就是在 雙向等拉 力 狀態(tài)下 ，在 兩個拉應 力方向 上產(chǎn) 生 數(shù) 值相同的伸 長 變形 ；在受 單向拉應 力 狀態(tài)時 ， 當 =0 時， =- /2，也就是說， 在受 單向拉應 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，處于沖壓應變圖中的 AOC 范圍內(nèi)（見圖 1 1）；而在沖壓應力圖中則處于 AOH 范圍內(nèi)（見圖 1 2）。 上述兩種沖壓情況，僅在最大應力的方向上不同，而兩個應力的性質(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。 沖壓毛坯變形區(qū)受兩向壓應力的作用，這種變形也分兩種情況分析，即 0 與 t0，即在板料厚度方向上的 應變 是正的，板料增厚。 在 方向上的變形取決于 與 的數(shù)值：當 =2 時， =0；當 2 時， 0。 這時 的變化范圍是 與 0 之間 。當 = 時，是雙向等 壓 力狀態(tài)時，故有 = 0 與 t0，即在板料厚度方向上的 應變 是正的，即 為壓縮變形 ，板厚增大。 在 方向上的變形取決于 與 的數(shù)值：當 =2 時， =0；當 2 ， 0。 這時， 的數(shù)值只能在 0。這種變形與受力情況，處于沖壓應變圖中的 GOL 范圍內(nèi)（見圖 1 1）；而在沖壓應力圖中則處于 DOE 范圍內(nèi)（見圖 1 2）。 沖壓 毛坯變形區(qū)受兩個異號應力的作用，而且拉應力的絕對值大于壓應力的絕對 值。這種變形共有兩種情況，分別作如下分析。 1）當 0， | |時，由式（ 1 2）可知：因 為 0， | |，所以一定有 2 - 0 及 0。 這個結(jié) 果表明：在異 號 的平面 應 力 狀態(tài)時 ，如果 絕對 值最大 應 力是 拉應 力 ，則在這個絕對值最大的拉應力方向上應變一定是正應變，即是伸長變形。 又因為 0， | |，所以必定有 0 0， 0， | |時，由式（ 1 2）可知： 用與前項相同的方法分析可得 0。 即在異 號應 力作用的平面 應 力 狀態(tài)下 ，如果 絕對值最大 應 力是 拉應 力 ，則在這個方向上的應變是 正的，是伸長變形；而在壓應力 方向上的應變是負的（ 0， 0， 0， | |時，由式（ 1 2）可知：因 為 0， | |，所以一定有 2 - 0， 0， 即在 拉應 力方向上的應變 是正的， 是伸長變形。 這時 的變化范圍只能在 =- 與 =0 的范圍內(nèi) 。當 =- 時， 0 0， 0， | |時，由式（ 1 2）可知： 用與前項相同的方法分析可得 0， 0， 0，而且 =- /2。這種變形情況處于沖壓應變圖中的 DOE 范圍內(nèi)（見圖 1 1）；而在沖壓應力圖中則處于 BOC 范圍內(nèi)（見圖 1 2）。 這四種變形與相應的沖壓成形方法之間是相對的，它們之間的對應關(guān)系，用文字標注在圖 1 1 與圖 1 2 上。 上述分析的四種變形情況，相當于所有的平面應力狀態(tài)，也就是說這四種變形情況可以把全部的沖壓變形毫無遺漏地概括為兩大類別，即伸長類與壓縮類。 當作用于沖壓毛坯變形區(qū)內(nèi)的拉應力的絕對值最大時，在