機(jī)械類(lèi)、模具類(lèi)外文翻譯----在拉深件內(nèi)使用空氣壓提高鋁板的拉深極限比

1、<p>　　Deep Drawing With Internal Air-Pressing to Increase The Limit Drawing Ratio of Aluminum Sheet</p><p>　　Young Hoon Moon*t, Yong Kee Kang, Jin Wook Park, Sung Rak Gong</p><p>　　Engineer

2、ing Research Center for Net Shape and Die Manufacturing,</p><p>　　Pusan National University</p><p>　　The effects of internal air-pressing on deep draw ability are investigated in this study to i

3、ncrease the deep drawability of aluminum sheet. The conventional deep drawing process is limited to a certain limit drawing ratio(LDR) beyond which failure will occur. The intention of this work is to examine the possibi

4、lities of relaxing the above limitation through the deep drawing with internal air-pressing, aiming towards a process with an increased drawing ratio. The idea which may lead to this goal</p><p>　　Keywords:

5、Deep Drawing, Internal Air-Pressing, Limit Drawing Ratio(LDR), AI-1050</p><p>　　1. Introduction</p><p>　　Aluminum alloy sheets are inferior in press formability compared to the mild steel sheets

6、. Most of the aluminum alloys have an r-value(plastic anisotropy value) between 0.7 and 1.0.Nonetheless, even though the r-values for the aluminum alloys are only about half of steel(Roger, 1991), they show, under the ri

7、ght circumstances, quite satisfactory drawing behavior. Among the aluminum alloys some noticeable differences in forming behavior on the stamping shop floor have been observed(Roger, 1991; La</p><p>　　The de

8、sign and control of a deep drawing process depends not only on the workpiece material, but also on the condition at the tool-workpiece interface, the mechanics of plastic deformation and the equipment used.</p>&l

9、t;p>　　The equipment and tooling parameters that affect the success or failure of a deep drawing operation are the punch and die radii, the punch and die clearance, the press speed, the lubrication and the type of rest

10、raint to metal flow(Hrivnak and Sobotoba, 1992; Date and Padmanabhan, 1992; Yossifon and Tisosh, 1991; Thiruvarudehelvan and Loh, 1993; Kawai et al., 1992; Johnson and Mellor, 1983). To establish the geometry of a part t

11、hat can be successfully and economically fabricated from a given mate</p><p>　　This forming limit depends, in addition to the shape change and process conditions, on the ability of a material to deform witho

12、ut failure.</p><p>　　The 'limiting drawing ratio'(LOR), is commonly used to provide a measure of the drawability of sheet metal, being the ratio of maximum blank diameter to punch diameter under the

13、drawing limit without failure(Thomas and Dadras, 1981; Leu, 1997; Chen and Sowerby,1996). It is well recognized that a high plastic anisotropy value(r-value) clearly indicated a better drawability, by inducing a high res

14、istance of a sheet to thinning. But there is no single material parameter which satisfactorily describ</p><p>　　In this work, the effect of internal pressing on the formability of aluminum sheet is investiga

15、ted to increase the LOR of aluminum alloys.</p><p>　　Figure 1 is a schematic of a cup die, showing the punch, die and blank holder, and a partially formed cup. The punch is on the down stroke and is just beg

16、inning to draw the sheet-metal blank into the die cavity. If the blank size has been chosen correctly, the metal will work harden sufficiently to overcome the combined strength of the remainder of the blank metal and fri

17、ction between it and the blank holder and the part will be successfully made. However, if the blank is too large, the part wil</p><p>　　One possible way to do this is air-pressing the internal surface of the

18、 blank by using specially designed punch. Because the air-pressing can reduce the local strain concentration and thus retard an early failure.</p><p>　　The test methods and results are described in this arti

19、cle.</p><p>　　2. Experimental Procedure</p><p>　　2.1 Material and equipment</p><p>　　Commercially available Al-1050 aluminum sheet with a thickness of 1.0 mm is used for the blank m

20、aterial. Tensile property of the AI-1050 is shown in Table I.</p><p>　　Preliminary experiments show that blanks with diameters of less than 70mm are drawn without failure. Therefore blank diameters are progr

21、essively increased by I mm from the blank diameters of 70 mm. When failure of blank occurs, experiments proceed with the diameter increasing or decreasing I mm to ascertain the maximum diameter of the blank sheet without

22、 failure in cup-drawing for estimating the LDR-value.</p><p>　　Figure 2 shows the deep drawing machine that is used in this investigation. It is a hydraulic press with a maximum load capacity of 50 Ton and a

23、 variable punch speed of I mm/sec-15 rum/sec. In this press, the punch is mounted on the lower shoe and the die on the upper shoe of the machine. The punching and blank-holding forces and the punch stroke can be measured

24、 separately by indicators those are provided on the machine.</p><p>　　Proper tool steel with appropriate mechanical properties and hardening treatment is used for the materials of the punches and dies. The t

25、ools are ground to an appropriate surface finish and a final hardness of 60HRC.</p><p>　　Figure.3 schematically shows punch and die set used in this study. For the air-pressing, the punch has been bored out

26、and high pressure air line was connected. This arrangement was used to produce internal air-pressure of maximum 110 kgf/cm2. The geometry of the punch and die, especially their profile radii, are the major variables in d

27、eep drawing processes. It has been shown [8] that for a punch nose radius, rp, that is less than twice the thickness of the blank, to, the cups fail due to tearin</p><p>　　Larger than 10 to stretching may be

28、 introduced. In addition, within the region 4' to< rp< 10· to the radius does not significantly affect the limiting drawing ratio(LOR). Therefore, according to the thickness of the blank, the most suitable

29、 shoulder radii for the dies and punches were selected to be 6mm with a constant punch diameter of 38.6mm.</p><p>　　2.2 Test procedure</p><p>　　A proper drawing speed is important for the deep d

30、rawing process: excessive speeds can cause wrinkling or fracture in the formed part and damage of the tooling: while insufficient speeds reduce the rate of production. In this investigation a drawing speed of 4 mm/sec is

31、 found to be the most suitable speed. The blank holder force is chosen to be the minimum force required to prevent wrinkling of the largest blank and is found to be 350kgf. An operation sequence is arranged for the tests

32、 and the p</p><p>　　Press oil, commercial grade high pressure hydraulic oil, is brushed on to the blank before forming to diminish the friction at the contact interface.</p><p>　　The effectivene

33、ss of the air-pressing was judged by LOR that is determined by the maximum size of blank that could be formed into a cup, since the blank size determines the maximum cup depth, and can be measured more accurately.</p&

34、gt;<p>　　3. Results and Discussion</p><p>　　To investigate the effect of air pressing on the deep drawability, the LOR is obtained at each process condition. For the calculation of LOR, the maximum bl

35、ank diameter, this diameter being that below which the blanks will be drawn successfully and above which tearing will occur in the cup wall is determined.</p><p>　　Figure 4 shows the variation of LOR with in

36、creasing air pressure for AI-1050 and Fig. 5 shows photograph of deep drawn cups at given process conditions.</p><p>　　Above figures show that higher LOR is obtained at higher internal air-pressure. The reas

37、on for the increased LOR at higher air pressure can be explained by thickness profile of cross sectioned cup shown in Fig. 6.</p><p>　　Figure 6 shows that the overall thickness of deep drawn cup and the degr

38、ee of thickness variation at rounding part are decreased at the air pressure of 70 kg/mm'', The relatively steep decrease in thickness at rounding part that had touched with punch nose radius reflects the local s

39、train has been concentrated on this part. Therefore, the decrease in the degree of thickness variation at the rounding part confirms that the local strain concentration has been relaxed by air- pressing.</p><p

40、>　　Figure 7 shows the effect of the air pressure on the drawing. load-displacement curves. In general, an increase in the drawing force is observed for larger blank diameters due to the enlargement of fictional interf

41、aces such as the die-blank and blank holder- blank interfaces. While the figure indicates that the maximum drawing loads are not so significantly increased even with increasing maximum blank diameters at higher air press

42、ure. It means that the internal air-pressing contribute to the red</p><p>　　Although the experimental conditions used in this study may not be the optimum for the highest LOR, the trends obviously shows that

43、 the internal air pressing is advantageous for higher LOR. The effectiveness of the air pressing process depends on how well the metal can be pressed .Therefore, the effect of air-pressing process will be more prominent

44、for aluminum alloy sheets than mild steel sheets.</p><p>　　4. Conclusion</p><p>　　The air-pressing method is proved to be very effective in increasing the deep drawability of AI1050. On the basi

45、s of the experimental investigation made herein, higher air pressing guarantees higher LDR. The increased LDR is mainly caused by the relaxation effect of local strain concentration at punch nose radius area. The results

46、 that have been described above show that air-pressing method also has the potential to increase the LDR of other metal alloy sheets.</p><p>　　Acknowledgements</p><p>　　This work has been suppor

47、ted by the Engineering Research Center for Net Shape and Die Manufacturing (ERC/NSDM), which is financed jointly by the Korean Science and Engineering Foundation (KOSEF)</p><p>　　References</p><p&

48、gt;　　Chen X. and Sowerby R., 1996, "Blank Development and the Prediction of Earing in Cup Drawing," International Journal of Mechanical Science, Vol. 8, No.5, pp. 509-516.</p><p>　　Date P.P. and Pa

49、dmanabhan K.A., 1992, "On the Prediction of the Forming Limit Diagram of Sheet Metals, " International Journal of Mechanical Science, Vol. 34, No.5, pp. 363-374.</p><p>　　Hrivnak A. and Sobotova L

50、.,1992, "The Influence of the Deformation Aging and the Conditions of Stress on the Properties of the Deep Drawing Steel Sheet," Journal of Materials Processing Technology, Vol. 34, pp. 425-430.</p><

51、p>　　Johnson W. and Mellor P.D.,1983 Engineering Plasticity, 2nd Ed., Ellis Horwood, Camelot Press, UK.</p><p>　　Kawai N. et al., 1992,"Friction Behavior in the Cup Ironing Process of Aluminum Sheets.

52、," Journal of Engineering for Industry, Vol. 114, pp.175-180.Leu D.K., 1997, "Prediction of the Limiting Drawing Ratio and the Maximum Drawing Load in Cup-Drawing," International Journal of Machine Tools

53、and Manufacture, Vol. 37, No.2, pp. 201-213.</p><p>　　Lange K., 1985, Handbook of Metal Forming, McGraw-Hill, New York, pp. 20-22.</p><p>　　Roger P., 1991, Sheet Metal Forming, Adam Hilger, New

54、York, pp. 181-242.</p><p>　　Thiruvarudehelvan S. and Loh N.H., 1993, "Drawing of Cylindrical and Hemispherical Cups using an Improved Tooling for Friction-Actuated Blank Holding," Journal of Materi

55、als Processing Technology, Vol. 37, pp. 267-280.</p><p>　　Thomas J.F. and Dadras Jr. P., 1981, Modeling of Sheet Forming Processes-An Overview, Wright State Univ., Dayton, Ohio, pp. 1-22.</p><p>

56、;　　Yossifon S. and Tisosh J., 1991, "On the Dimensional Accuracy of Deep Drawing Products by Hydroforming Processes,” International Journal of Mechanical Science, Vol. 33, No.4, pp. 279-295.</p><p>　　在拉

57、深件內(nèi)使用空氣壓提高鋁板的拉深極限比</p><p>　　Young Hoon Moon*t, Yong Kee Kang, Jin Wook Park, Sung Rak Gong</p><p>　　凈成形與模具制造工程研究中心</p><p><b>　　釜山國(guó)立大學(xué)</b></p><p>　　該研究主要是通過(guò)研

58、究使用空氣壓對(duì)拉深的影響來(lái)提高鋁板的拉深能力，傳統(tǒng)的拉深過(guò)程是局限在某一個(gè)極限拉深比（LDR的）過(guò)后，將出現(xiàn)拉裂。這項(xiàng)工作的目的是通過(guò)研究放寬傳統(tǒng)拉深限制，在拉深的進(jìn)出中，內(nèi)部使用空氣壓的可能性，目的在于提高拉深比。這個(gè)想法可能是導(dǎo)致這一目標(biāo)過(guò)程中使用特殊的沖壓拉深，可以在高施加壓力板的內(nèi)部表面變形。對(duì)于超出1050號(hào)鋁的拉深極限，在拉深凸模內(nèi)通空氣壓以降低在凸模半徑范圍局部應(yīng)變以及使用內(nèi)部空氣壓獲得更高的拉深極限比是非常有效的方法的證

59、明。</p><p>　　關(guān)鍵詞: 拉深、內(nèi)部空氣壓、極限拉深比（LDR），鋁-1050 。</p><p><b>　　1介紹</b></p><p>　　鋁合金板的成形性能不如中性鋼板。 Most of the aluminum alloys have an r-value(plastic anisotropy value) between

60、 0.7 and 1.0.Nonetheless, even though the r-values for the aluminum alloys are only about half of steel(Roger, 1991), they show, under the right circumstances, quite satisfactory drawing behavior. Among the aluminum allo

61、ys some noticeable differences in forming behavior on the stamping shop floor have been observed(Roger, 1991;Lange, 1985) because the relationship between the material, die design and te</p><p>　　拉深成形是一種無(wú)折皺平

62、板過(guò)渡成杯形局部變薄的工藝。在設(shè)計(jì)和控制拉深過(guò)程不僅取決工件的材料，而且還取決于工件表面狀態(tài)，塑性變形力和使用的設(shè)備。</p><p>　　設(shè)備和模具參數(shù)上影響拉深成功與否是凸模和凹模的刃口圓角半徑，，凸、凹模間隙，沖壓速度，潤(rùn)滑程度和約束金屬流動(dòng)條件（Hrivnak and Sobotoba, 1992; Date and Padmanabhan, 1992; Yossifon and Tisosh, 1991

63、; Thiruvarudehelvan and Loh, 1993; Kawai et al., 1992; Johnson and Mellor, 1983）對(duì)于可以從給定的材料已能判斷能否成功成形的幾何零件，知道該材料的成形極限是必要的。除了形狀的變化和工藝條件，對(duì)材料的變形能力，還有有無(wú)故障這都取決于成形極限。</p><p>　　拉深極限比通常是用來(lái)表示金屬板料的拉深能力，即是拉深件的最大板直徑與最終拉深

64、后的直徑比在成功的拉深條件下，從所周知一個(gè)高的塑性各項(xiàng)異值（r值）清楚地代表了更好的拉深性能，通過(guò)提高抵抗板料的變薄性能。但是沒(méi)有一個(gè)材料的參數(shù)能夠滿意描述拉深的過(guò)程。</p><p>　　在這項(xiàng)工作中，研究?jī)?nèi)部壓力對(duì)鋁板成形性能的影響，以提高鋁合金的的拉深極限比。</p><p>　　圖1是一個(gè)杯形件模具示意圖，顯示了凸模、凹模和壓邊，以及部分已成形杯狀。凸模剛好向下沖程板料進(jìn)入凹模型腔

65、。如果板料的尺寸選擇正確，拉深將穩(wěn)定進(jìn)行足以克服板料與壓邊的摩擦和部分綜合力，拉深將成功。但是，如果板料尺寸過(guò)大，當(dāng)拉深超過(guò)拉深強(qiáng)度時(shí)工件將拉裂。第一次變形發(fā)生在凹模圓角半徑與凸模圓角半徑部分，因?yàn)檫@是模具不受摩擦約束的部分。材料在該位置面積增加而變薄強(qiáng)度降低，因此，可判斷凸、凹模的圓角半徑是拉深失效的主要因素，如果在關(guān)鍵領(lǐng)域中可以釋放集中壓力，承載能力將增加，斷裂是可以避免的。 One possible way to do this

66、is air-pressing the internal surface of the blank by using specially designed punch. </p><p>　　一種可能的方式，這是空氣壓利用專(zhuān)門(mén)設(shè)計(jì)的沖床通氣在板料內(nèi)部表面的。 Because the air-pressing can reduce the local strain concentration and thus re

67、tard an early fail由于空氣壓可減少局部應(yīng)變集中，從而延緩了早期失效。 </p><p>　　本篇文章介紹了實(shí)驗(yàn)方法和結(jié)果。</p><p><b>　　2實(shí)驗(yàn)過(guò)程</b></p><p><b>　　2.1材料和設(shè)備</b></p><p>　　市場(chǎng)鋁-1050厚度為1.0毫米的板

68、材，表1為其材料參數(shù)。</p><p>　　實(shí)驗(yàn)初步表明，板料直徑小于70mm都沒(méi)有發(fā)生破裂，因此我從70mm 直徑的板料逐步增加直徑，當(dāng)破裂發(fā)生的板料時(shí)，實(shí)驗(yàn)進(jìn)行增加或減少板料的直徑，以確定材料的最大直徑來(lái)估算板料的拉深極限比。</p><p>　　圖2顯示的本次研究所用的拉深機(jī)。這個(gè)壓力機(jī)的最大載重量為50噸，沖壓速度1mm/s~15mm/s，在這沖壓過(guò)程中，凸模安裝在下方，而凹模安裝

69、在上面，沖壓的壓邊力和沖壓的行程指標(biāo)由計(jì)算機(jī)提供。</p><p>　　凸、凹模的材料選用合適的模具鋼并進(jìn)行機(jī)械處理和硬化處理，這些模具最終的表面光潔度要有合理值，最終硬度為60HRC。</p><p>　　圖3示意本研究中使用的凸、凹模。在凸模通孔與高壓空氣管連接，通入高壓空氣，在這項(xiàng)中使用最大的空氣壓力為110MPa。凸、凹模的幾何形狀，尤其它們的圓角半徑是拉深過(guò)程的主要考慮因素，在[

70、8]說(shuō)明了當(dāng)凸模圓角半徑的值不不超過(guò)板料厚度的兩倍，則在拉深是不會(huì)拉裂，而當(dāng)凸模的圓角半徑大于板料厚度的10倍是，則拉深不能順利流動(dòng)。與此同時(shí)，圓角半徑在4-10倍是卻不能顯示影響拉深極限比。因此根據(jù)板料的厚度，為凸、凹模選擇最合適的圓角半徑為6mm，凸模直徑為38.6mm。</p><p><b>　　2.2實(shí)驗(yàn)過(guò)程</b></p><p>　　在拉深過(guò)程中拉深速度

71、是一個(gè)重要因素，過(guò)大的速度可能會(huì)導(dǎo)致拉深件的起皺或模具損傷斷裂；速度不足從而降低了生產(chǎn)速度。在本研究中4mm/s的速度是拉深最合適的速度，壓邊力需要選擇為最低限度的力，以防止拉深件的起皺，在一系列的測(cè)試中發(fā)現(xiàn)350kgf為最合適，在實(shí)驗(yàn)中安排沖床沖壓與變量測(cè)試同時(shí)進(jìn)行，逐步增加空氣壓力，直到找到最大壓力其不在影響拉深性能的，每次測(cè)試是重復(fù)2至3次取其平均值，所以實(shí)驗(yàn)如圖3所示進(jìn)行操作。本研究應(yīng)用的實(shí)驗(yàn)參數(shù)如表2所示。</p>

72、<p>　　在拉深前，板料涂上高潤(rùn)滑油，以降低板料成形時(shí)的接觸摩擦。由空氣壓的影響可以判斷板料最大尺寸可以成形拉深件，因?yàn)榘辶系某叽绱笮Q定了拉深的高度并更加準(zhǔn)確的加以衡量。</p><p><b>　　3結(jié)果與討論</b></p><p>　　為了研究空氣壓對(duì)拉深性能的影響，拉深極限比可從各工序條件獲得，為了拉深極限比，板料的最大直徑，這是計(jì)算直徑低于

73、該板料將被拉深成功及關(guān)于拉深件出現(xiàn)拉裂的關(guān)鍵。</p><p>　　圖4顯示的是鋁1050增加空氣壓力的變化。圖5顯示的是拉深的照片在給定的參數(shù)條件下拉深得到的。</p><p>　　上述數(shù)字表明了，高拉深極限比是在高的內(nèi)部空氣壓力獲得的圖5解釋來(lái)為什么高氣壓能獲得高的拉深極限比。</p><p>　　圖6展示了板料在過(guò)渡成拉深件的厚度變化在氣壓70MPa，在凸模的

74、圓角半徑處隨空氣壓力的下降而該局部應(yīng)變一直集中在這一部分，因此，拉深的厚度變化程度在減少得到證實(shí)。該位置的應(yīng)變集中受到空氣壓的釋放。</p><p>　　圖7顯示了空氣壓對(duì)拉深的影響載荷位移曲線，在一般情況下，板料的直徑大拉深力也增大，而這個(gè)數(shù)據(jù)表明了，在高空氣壓下，板料的直徑增大，拉深最大載荷并沒(méi)有一直增大，這就是說(shuō)，內(nèi)部空氣壓有助于降低拉深力和板料摩擦力。換句話說(shuō)，內(nèi)部空氣壓本身并沒(méi)有改變變形，而是改變板料成

75、形的變形抗力，有效的疏導(dǎo)了凸模圓角半徑對(duì)板料的效應(yīng)和提高了板料的拉深極限比。</p><p>　　雖然實(shí)驗(yàn)研究獲得的拉深極限比并不是在最佳的條件下進(jìn)行的，，但該趨勢(shì)表明了使用內(nèi)空氣壓獲得高的拉深極限比是很有優(yōu)勢(shì)的。材料可以在空氣壓下更好的拉深，因此，在空氣壓下，鋁板比鋼板塑性更加突出。</p><p><b>　　4 結(jié)論</b></p><p&g

76、t;　　空氣壓被證明是增加鋁1050拉深性能的有效方法。對(duì)于本實(shí)驗(yàn)研究的基礎(chǔ)上進(jìn)行，用高空氣壓保證了高拉深極限比，拉深極限比的提高在于凸模圓角半徑出板料應(yīng)變集中得到緩解。從上述措施表明，空氣壓的方法也有可能提高其他金屬合金板料的拉深極限比。</p><p><b>　　鳴謝</b></p><p>　　該項(xiàng)目由凈成形與模具制造工程技術(shù)研究中心（ERC/NSDM）支持,

77、其研究經(jīng)費(fèi)由韓國(guó)科學(xué)與工程基金會(huì)提供。</p><p><b>　　參考資料</b></p><p>　　Chen X. and Sowerby R., 1996, "Blank Development and the Prediction of Earing in Cup Drawing," International Journal of Me

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83、20-22.</p><p>　　Roger P., 1991, Sheet Metal Forming, Adam Hilger, New York, pp. 181-242.</p><p>　　Thiruvarudehelvan S. and Loh N.H., 1993, "Drawing of Cylindrical and Hemispherical Cups usi

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