中英文中英文文獻(xiàn)翻譯-沖壓變形

1、 英文原文Categories of stamping formingMany deformation processes can be done by stamping, the basic processes of the stampingcan 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 mainlyincludes blanking, punching, trimming,

2、 parting and shaving, where punching and blanking are themost widely used. Forming is a process that one part of the blank has some displacement form theother. It mainly includes deep drawing, bending, local forming, bulging, flanging, necking, sizingand spinning.In substance, stamping forming is su

3、ch that the plastic deformation occurs in the deformationzone of the stamping blank caused by the external force. The stress state and deformationcharacteristic of the deformation zone are the basic factors to decide the properties of the stampingforming. Based on the stress state and deformation ch

4、aracteristics of the deformation zone, theforming methods can be divided into several categories with the same forming properties and to bestudied 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 ap

5、plied on the blank surface. When it is assumed thatthe stress perpendicular to the blank surface equal to zero, two principal stresses perpendicular toeach other and act on the blank surface produce the plastic deformation of the material. Due to thesmall thickness of the blank, it is assumed approx

6、imately that the two principal stresses distributeuniformly along the thickness direction. Based on this analysis, the stress state and thedeformation characteristics of the deformation zone in all kind of stamping forming can bedenoted by the point in the coordinates of the plane principal stress(d

7、iagram 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 stateand deformation characteristics.(1)When the deformation zone of the stamp

8、ing blank is subjected toplanetensile stresses, itcan be divided into two cases, that is 0, =0and 0, =0.In both cases, the stress withttthe maximum absolute value is always a tensile stress. These two cases are analyzed respectivelyas follows.2)In the case that 0and =0, according to the integral the

9、ory, the relationships betweentstresses and strains are: /（ - ）= /（ - ）= /（ - ）=k1.1where, ， ， are the principal strains of the radial, tangential and thickness directions of themmttmtaxial symmetrical stamping forming; ， and are the principal stresses of the radial, tangentialtand thickness directi

10、ons of the axial symmetrical stamping forming; is the average stress, =mm （ + + ）/3; k is a constant.tIn plane stress state, Equation 1.13 /（2 - ）=3 /（2 - ）=3 /-（ + ）=k 1.2tttSince 0,so 2 - 0 and 0.It indicates that in plane stress state with two axialtensile stresses, if the tensile stress with the

11、 maximum absolute value is , the principal strain inthis direction must be positive, that is, the deformation belongs to tensile forming.In addition, because 0，therefore -（ + ）0 and 2 , 0；and when 0.The range of is = =0 . In the equibiaxial tensile stress state = ，according toEquation 1.2, = 0 and 0

12、 and =0, according to Equation 1.2 , 2 0 and 0,This result showstthat for the plane stress state with two tensile stresses, when the absoluste value of is the strainin this direction must be positive, that is, it must be in the state of tensile forming.Also because 0，therefore （- + ）0 and , 0;and wh

13、en 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 thesame as that of

14、 the ordinary uniaxial tensile.This kind of deformation is in the region AON of the diagram of the stamping strain (seeFig.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 of and , and thedeformation cause

15、d 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 compressivestresses and ( =0), it can also be divided into two cases, which are 0, =0 an

16、d tt0, =0.t1）When 0 and =0, according to Equation 1.2, 2 - 0 與 =0.This result showstthat in the plane stress state with two compressive stresses, if the stress with the maximumabsolute value is 0, the strain in this direction must be negative, that is, in the state of compressive forming.Also becaus

17、e 0 and 0.The strain in the thickness direction of thettblank is positive, and the thickness increases.tThe deformation condition in the tangential direction depends on the values of and .When =2 , =0;when 2 , 0;and when 0.The range of is 0.When = ,it is in equibiaxial tensile stress state, hence =

18、0;when =0,it is in uniaxial tensile stress state, hence =- /2.This kind of deformation condition isin the region EOG of the diagram of the stamping strain (see Fig.1.1), and in the region COD ofthe diagram of the stamping stress (see Fig.1.2).2）When 0and =0, according to Equation 1.2,2 - 0 and 0. Th

19、is result showstthat in the plane stress state with two compressive stresses, if the stress with the maximumabsolute value is , the strain in this direction must be negative, that is, in the state ofcompressive forming.Also because 0 and 0.The strain in the thickness direction ofttthe blank is posit

20、ive, and the thickness increases.tThe deformation condition in the radial direction depends on the values ofand . When =2 , =0; when 2 , 0; and when 0.The range of is = =0 . When = , it is in equibiaxial tensile stress state, hence = 0.This kind ofdeformation is in the region GOL of the diagram of t

21、he stamping strain (see Fig.1.1), and in theregion 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 oppositesigns, and the absolute value of the tensile stress is larger than that of the compressive stress.There

22、exist two cases to be analyzed as follow:1)When 0, | |, according to Equation 1.2, 2 - 0 and 0.This resultshows that in the plane stress state with opposite signs, if the stress with the maximum absolutevalue is tensile, the strain in the maximum stress direction is positive, that is, in the state o

23、f tensileforming.Also because 0, | |, therefore = =- . When =- , then 0, 0, 0, | |, according to Equation 1.2, bytmeans of the same analysis mentioned above, 0, that is, the deformation zone is in the planestress state with opposite signs. If the stress with the maximum absolut e value is tensile st

24、ress ,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 and 0, therefore 2 - 0. The strain in the tensile stressdirection is positive, or in t

25、he state of tensile forming.The range of is 0= =- .When =- , then 0, 0, 0, | |, according to Equation 1.2 and by means of the sameanalysis mentioned above, = =- .When =- , then 0, 0, 0, and =- /2. Such deformation is in the region DOF of the diagram of the stampingstrain (see Fig.1.1), and in the re

26、gion 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 pla

27、ne stressstates, that is, the four deformation conditions can sum up all kinds of stamping forming in to twotypes, tensile and compressive. When the stress with the maximum absolute value in thedeformation zone of the stamping blank is tensile, the deformation along this stress direction mustbe tens

28、ile. Such stamping deformation is called tensile forming. Based on above analysis, thetensile forming occupies five regions MON, AON, AOB, BOC and COD in the diagram of thestamping stain; and four regions FOG, GOH, AOH and AOB in the diagram of the stamping stress.When the stress with the maximum ab

29、solute value in the deformation zone of the stampingblank is compressive, the deformation along this stress direction must be compressive. Such stamping deformation is called compressive forming. Based on above analysis, the compressiveforming occupies five regions LOM, HOL, GOH, FOG and DOF in the

30、diagram of the stampingstrain; 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 stampingstrain and stress respectively. The tensile forming is located in the top right of the boundary, andthe

31、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 straincaused by the stress, there also exist certain relationships between the diagrams of the stampingstress and strain. There are corresponding

32、 locations in the diagrams of the stamping stress andstrain for every stamping deformation. According to the state of stress or strain in the deformationzone of the forming blank, and using the boundary line in the diagram of the stamping stress MDor the boundary line in the diagram of the stamping

33、strain FB, it is easy to know the properties andcharacteristics of the stamping forming.The locations in the diagrams of the stamping stress and strain for various stress states andthe corresponding relationships of the two diagrams are listed in Table 1.1.It shows that thegeometrical location for e

34、very 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 linebetween the tensile and the compressive forming is an inclined line at 45 to the coordinate axis.The characteristics of the stampin

35、g technique for tensile and compressive forming are listed inTable 1.2.Table 1.2 clearly shows that in the deformation zone of the blank, the characteristics of theforce and deformation, and the patterns relevant to the deformation for each stamping method arethe same. Therefore, in addition to the

36、research on the detail stamping method, it is feasible tostudy stamping systematically and comprehensively. The characteristic of the systematic researchis to study the common principle of all different types of stamping methods. The results of thesystematic research are applicable to all stamping m

37、ethods. The research on the properties andlimit of the sheet metal stamping has been carried out in certain extent. The contents of theresearch on the stamping forming limit by using systematic method are shown in Fig.1.3.State of stressLocation in Location inthe diagram the diagramTypesofthedeforma

38、tionstampingstrain BiaxialTensileTensiletensile stressstateBiaxialCompressivcompressivestress state 0, 0 =0和 t 0， =0。再這兩種情況下，絕對(duì)值最大的應(yīng)力都是拉應(yīng)力。以下對(duì)這兩種情況進(jìn)行t分析。1)當(dāng) 0 且 =0 時(shí)，安全量理論可以寫出如下應(yīng)力與應(yīng)變的關(guān)系式：t(1-1) /（ - ）= /（ - ）= /（ - ）=kmmtmt式中 ， ， 分別是軸對(duì)稱沖壓成形時(shí)的徑向主應(yīng)變、切向主應(yīng)變和厚度方向上t的主應(yīng)變； ， ， 分別是軸對(duì)稱沖壓成形時(shí)的徑向主應(yīng)力、切向主應(yīng)力和厚度方向上的

39、主t應(yīng)力； 平均應(yīng)力， =（ + + ）/3；mmtk常數(shù)。在平面應(yīng)力狀態(tài)，式（11）具有如下形式：3 /（2 - ）=3 /（2 - ）=3 /-（ + ）=k （12）ttt因?yàn)?0，所以必定有 2 - 0 與 0。這個(gè)結(jié)果表明：在兩向拉應(yīng)力的平面應(yīng)力狀態(tài)時(shí)，如果絕對(duì)值最大拉應(yīng)力是 ，則在這個(gè)方向上的主應(yīng)變一定是正應(yīng)變，即是伸長(zhǎng)變形。又因?yàn)?0，所以必定有-（ + ）0 與 2 時(shí)， 0；當(dāng) 0。 的變化范圍是 = =0 。在雙向等拉力狀態(tài)時(shí)， = ，有式（12）得 = 0 及 0 且 =0 時(shí)，有式（12）可知：因?yàn)?0，所以t（2）定有 2 0 與 0。這個(gè)結(jié)果表明：對(duì)于兩向拉應(yīng)力的平

40、面應(yīng)力狀態(tài)，當(dāng)?shù)慕^對(duì)值最大時(shí)，則在這個(gè)方向上的應(yīng)變一定時(shí)正的，即一定是伸長(zhǎng)變形。又因?yàn)?0，所以必定有-（ + ）0 與 ， 0；當(dāng) 0。 的變化范圍是 = =0 。當(dāng) = 時(shí)， = 0，也就是在雙向等拉力狀態(tài)下，在兩個(gè)拉應(yīng)力方向上產(chǎn)生數(shù)值相同的伸長(zhǎng)變形；在受單向拉應(yīng)力狀態(tài)時(shí)，當(dāng)=0 時(shí)， =-/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(jiǎn)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 11）；而在沖壓應(yīng)力圖中則處于 AOH 范圍內(nèi)（見圖 12）。上述兩種沖壓情況，僅在最大應(yīng)力的方向上不同，而兩個(gè)應(yīng)力的性質(zhì)以及它們引起的變形都是一樣的。因此，對(duì)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 =0 和 0， =0。tt1）當(dāng) 0 且 =0 時(shí)，有式（12）可知：因?yàn)?0，一定有 2 - 0t與 0。這個(gè)結(jié)果表明：在兩向壓應(yīng)力的平面應(yīng)力狀態(tài)時(shí)，如果絕對(duì)