筆記本頂蓋的鎂合金板材沖壓模具設(shè)計外文翻譯

1、出處：Journal of Materials Processing TechnologyVolume 201, Issues 13, 26 May 2008, Pages 24725110th International Conference on Advances in Materials and Processing TechnologiesAMPT 2007題目：筆記本頂蓋的鎂合金板材沖壓模具設(shè)計蔡恒光，廖浩欽，陳復(fù)國摘要：在本文章中，對LZ91鎂鋰合金板材在室溫下制造筆記本頂蓋時的沖壓工藝進(jìn)行了檢查，同時使用了實驗方法和有限元分析。四步工序沖壓工藝的開發(fā)，以消在沖壓頂蓋的工藝的情況下

2、產(chǎn)生裂縫和起皺缺陷。為了驗證有限元分析，進(jìn)行實際操作沖壓工藝與使用0.6毫米厚的LZ91的空白。厚度分布在不同地點之間的實驗數(shù)據(jù)和有限元計算結(jié)果吻合良好，證實了有限元分析的準(zhǔn)確性和效率。 LZ91板材在室溫成形性能優(yōu)越，也表明目前的筆記本頂蓋的成功制造研究。適合的四步操作過程本身操作程序數(shù)量少，比在目前的實踐要求，形成在筆記本鉸鏈的有效途徑。這也印證了在制造筆記本蓋的情況下，可以用LZ91鎂合金板材的沖壓工藝生產(chǎn)。它提供了一個在電子行業(yè)替代鎂合金的應(yīng)用。關(guān)鍵字筆記本電腦情況下;LZ91鎂鋰合金板材;多工序沖壓;成形性1. 介紹在EMI中由于重量輕，性能良好，在電子行業(yè)鎂合金已被廣泛用于結(jié)構(gòu)部件

3、，如手機(jī)和筆記本電腦。雖然現(xiàn)行的鎂合金產(chǎn)品制造過程一直壓鑄，鎂合金板材的沖壓行業(yè)，因為其有競爭力的生產(chǎn)力和有效的薄壁結(jié)構(gòu)構(gòu)件生產(chǎn)性能已制定的利益。由于它的六角形密堆積（HCP的形成）晶體結(jié)構(gòu)（陳等，2003和陳和黃，2003），即使它需要高溫，常用沖壓工藝中鎂合金（鋁3，鋅1）已在目前的形成過程中應(yīng)用。最近，鎂，鋰（LZ）合金也已研制成功，以提高鎂合金的室溫成形性。鎂合金的延展性，可以改善鋰此外，開發(fā)形成體心立方（BCC）晶體結(jié)構(gòu)（Takuda等人。，1999，Takuda等。，1999和Drozd等，2004）。在本研究中，一個筆記本頂蓋使用LZ表的情況下的沖壓工藝進(jìn)行了檢查。筆記本頂蓋的兩

4、個鉸鏈的形成，如圖1所示（a和b），是由于在沖壓過程中最困難的操作之間的法蘭和圖中顯示在小角落半徑小的距離。 如圖1（c）。造成這種幾何復(fù)雜圓角半徑的一個戲劇性的變化時，鉸鏈法蘭太接近筆記本的邊緣，這很容易造成周圍的鉸鏈法蘭斷裂缺損，并要求多操作，克服這一問題。在本研究中，LZ鎂合金板的成形性能和最佳的多工序沖壓工藝開發(fā)，以減少同時使用的實驗方法和有限元分析的操作程序。圖1 在筆記本頂蓋的鉸鏈法蘭 （a）鉸鏈，（b）頂蓋情況和（c）法蘭。2。鎂合金板材的力學(xué)性能在室溫下進(jìn)行拉伸試驗，比較其機(jī)械性能，在高溫下對AZ31張鎂鋰合金板材LZ61（鋰6，鋅1），LZ91，LZ101。圖2（a）顯示LZ

5、表在室溫和那些對AZ31張在室溫和200C的應(yīng)力應(yīng)變關(guān)系據(jù)悉，應(yīng)力 - 應(yīng)變曲線趨于增加鋰的含量較低。圖（2）也顯示，LZ91板材在室溫和AZ31鎂板在200C是彼此接近。 LZ101板材在室溫下具有更延性比LZ91和AZ31在200C由于鋰的成本是非常昂貴，而不是LZ101板材LZ91板材，可被視為一個合適的LZ鎂合金板材在室溫下呈現(xiàn)良好的成形性。出于這個原因，本研究采用LZ91板材的筆記本頂蓋的空白，并試圖探討在室溫成形性LZ91。以確定是否斷裂將發(fā)生在有限元分析，為0.6毫米厚的LZ91板材成形極限圖還建立了如圖2（b）所示。 圖2 鎂合金的力學(xué)性能 （a）鎂合金的應(yīng)力應(yīng)變關(guān)系; （b）

6、LZ91板材的（FLD）成形極限圖3。有限元模型如圖3（a）所示，使用軟件DELTAMESH，由CAD軟件，PRO / E的模具幾何構(gòu)造，被轉(zhuǎn)換成有限元網(wǎng)格。被視為剛體的工具，并采用四節(jié)點殼單元建設(shè)空白網(wǎng)。從實驗中獲得的材料特性和成形極限圖中使用的有限元模擬。在初始運行中使用的其他模擬參數(shù)為：沖壓力5毫米/秒，壓邊力3千牛，庫侖摩擦系數(shù)為0.1。采用有限元軟件PAM_STAMP進(jìn)行分析，并在臺式電腦上進(jìn)行模擬。 圖3 有限元模擬 （a）有限元網(wǎng)格和（b）在角落斷裂。首次構(gòu)建了有限元模型研究的一個鉸鏈的形成過程。由于對稱性，只有一個頂蓋的情況下的一半是模擬，如圖3（a）所示。仿真結(jié)果如圖3（b）

7、所示，表明斷裂發(fā)生在法蘭的角落，最小厚度小于0.35毫米。這意味著斷裂問題非常嚴(yán)重，是只通過擴(kuò)大在法蘭圓角半徑是不能解決的。對有限元模擬進(jìn)行研究的參數(shù)，影響斷裂的發(fā)生以及避免斷裂，提出了幾種方法。4. 多工序沖壓工藝設(shè)計為了避免發(fā)生斷裂，多工序沖壓過程是必需的。在當(dāng)前的工業(yè)實踐中，形成頂蓋的情況下，使用鎂合金板材，通常需要至少十步的運作程序。在本研究中，嘗試了減少運作程序。對避免斷裂，提出了幾種方法，斷裂問題的一個可行的解決方案是四個操作沖壓工藝。為了限制這個文件的長度，在下面只對兩個操作和四個操作沖壓工藝進(jìn)行了描述。4.1 兩步操作沖壓工藝第一是在兩個操作沖壓工藝側(cè)壁形成如圖4（a），第二是

8、在圖4（b）提出的鉸鏈法蘭成型，鉸鏈法蘭的高度為5毫米。圖4（c）所示的厚度分布的有限元模擬得到。變形板材的最小厚度為0.41毫米及以上的成形極限圖的菌株。這意味著可避免斷裂缺損。此外，法蘭的高度符合要達(dá)到的目標(biāo)。然而，這個過程是產(chǎn)生起皺缺陷的關(guān)鍵，如圖4（d）所示，法蘭上的鉸鏈，導(dǎo)致在隨后的修剪操作中出現(xiàn)問題。因此，即使兩個操作沖壓工藝解決在角落和底部的鉸鏈法蘭斷裂問題，更好的形成過程仍有望解決鉸鏈法蘭起皺。圖4 兩個操作沖壓工藝 （a）形成的側(cè)壁，（b）鉸鏈，（c）厚度分布和（d）皺紋的形成4.2 四步操作沖壓工藝如圖5（a）所示，四部操作在本研究中提出的形成過程三個側(cè)壁和慷慨的角半徑的鉸

9、鏈法蘭成形開始。由于側(cè)壁接近法蘭開放和圓角半徑大于所需的法蘭成功形成無斷裂。成功地避免了這樣的過程，同時形成兩個幾何特征的難度，但增加了一張白紙的物質(zhì)流。下一步是修剪外側(cè)壁的空白，并校準(zhǔn)所需的圓角半徑4毫米到2.5毫米的值。鉸鏈，從而形成，如圖5（b）所示。第三步是開放的一面折疊，使側(cè)壁可以圍繞其周邊完成，如圖5（c）所示。研究修剪額外的表外側(cè)壁在第二步第三步的效果。當(dāng)額外的工作表不修剪，在拐角處的厚度為0.381毫米，如圖5（d）所示。提高到0.473毫米厚度的角落，如圖5（e）所示。如果修剪在第二個步驟實施。在第三步的折疊過程中產(chǎn)生過多的物質(zhì)，然后根據(jù)零件設(shè)計，修剪掉。最后一步是醒目的過程

10、，是適用于校準(zhǔn)所有的圓角半徑設(shè)計值。在最終產(chǎn)品的角落的最小厚度為0.42毫米，和所有株以上的成形極限圖。這是要注意，圖5（a-c）只顯示一個鉸鏈的形成。相同的設(shè)計概念，然后擴(kuò)展到完整的頂蓋的沖壓工藝。5。實驗驗證為了驗證有限元分析，進(jìn)行實際操作沖壓工藝與使用0.6毫米厚的LZ91表的空白。毛坯尺寸和模具的幾何形狀設(shè)計，根據(jù)有限元模擬結(jié)果。然后制造一個完善的產(chǎn)品無斷裂和皺紋，如圖6（a）所示。為了進(jìn)一步驗證了有限元分析定量，厚度，在完善的產(chǎn)品的鉸鏈周圍的角落，如圖6（b）所示，進(jìn)行測量和對比獲得的有限元模擬，如表1所列。表1中可以看出，實驗數(shù)據(jù)和有限元計算結(jié)果是一致的。四步操作過程的有限元分析的

11、基礎(chǔ)上設(shè)計，然后由實驗數(shù)據(jù)證實。圖6 完善的產(chǎn)品 （a）無斷裂和皺紋（b）測量厚度的位置。表1。測量的厚度比較ABCD真實值0.42mm0.44mm0.49mm0.53mm理論值0.423mm0.448mm0.508mm0.532mm誤差0.71%1.79%3.54%0.38%6。結(jié)束語在目前使用的實驗方法和有限元分析對鎂合金板材成形進(jìn)行了研究。首先研究了AZ31和LZ的成形性。研究結(jié)果表明，LZ91板材在室溫下有良好的成形性，類似于AZ31板材成形溫度在200C。LZ91板材在室溫成形性能優(yōu)越，也表明在目前的筆記本頂蓋制造的成功研究。四步的操作過程使其本身在筆記本比在目前的實踐中需要較少的操

12、作程序，形成鉸鏈的有效途徑。同時證明了筆記本蓋，可以用LZ91， LZ91鎂合金板的沖壓工藝生產(chǎn)。在電子行業(yè)它提供了一個替代鎂合金的應(yīng)用。Journal of Materials Processing TechnologyVolume 201, Issues 13, 26 May 2008, Pages 24725110th International Conference on Advances in Materials and Processing TechnologiesAMPT 2007Die design for stamping a notebook case with magne

13、sium alloy sheets Heng-Kuang Tsai, Chien-Chin Liao, Fuh-Kuo Chen, Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan, ROC Available online 8 December 2007. , How to Cite or Link Using DOI Permissions & ReprintsAbstractIn the present study, the stamping process for manuf

14、acturing a notebook top cover case with LZ91 magnesiumlithium alloy sheet at room temperature was examined using both the experimental approach and the finite element analysis. A four-operation stamping process was developed to eliminate both the fracture and wrinkle defects occurred in the stamping

15、 process of the top cover case. In order to validate the finite element analysis, an actual four-operation stamping process was conducted with the use of 0.6mm thick LZ91 sheet as the blank. A good agreement in the thickness distribution at various locations between the experimental data and the fin

16、ite element results confirmed the accuracy and efficiency of the finite element analysis. The superior formability of LZ91 sheet at room temperature was also demonstrated in the present study by successful manufacturing of the notebook top cover case. The proposed four-operation process lends itself

17、 to an efficient approach to form the hinge in the notebook with less number of operational procedures than that required in the current practice. It also confirms that the notebook cover cases can be produced with LZ91 magnesium alloy sheet by the stamping process. It provides an alternative to the

18、 electronics industry in the application of magnesium alloys.Keywords Notebook case; LZ91 magnesiumlithium alloy sheet; Multi-operation stamping; Formability1. IntroductionDue to its lightweight and good performance in EMI resistance, magnesium alloy has been widely used for structural components in

19、 the electronics industry, such as cellular phones and notebook cases. Although the prevailing manufacturing process of magnesium alloy products has been die casting, the stamping of magnesium alloy sheet has drawn interests from industry because of its competitive productivity and performance in th

20、e effective production of thin-walled structural components. As for stamping process, AZ31 magnesium alloy (aluminum 3%, zinc 1%) sheet has been commonly used for the forming process at the present time, even though it needs to be formed at elevated temperature due to its hexagonal closed-packed (HC

21、P) crystal structure ( Chen et al., 2003andChen and Huang, 2003). Recently, the magnesiumlithium (LZ) alloy has also been successfully developed to improve the formability of magnesium alloy at room temperature. The ductility of magnesium alloy can be improved with the addition of lithium that devel

22、ops the formation of body centered-cubic (BCC) crystal structure ( Takuda et al., 1999a, Takuda et al., 1999bandDrozd et al., 2004).In the present study, the stamping process of a notebook top cover case with the use of LZ sheet was examined. The forming of the two hinges in the top cover of a noteb

23、ook, as shown in Fig. 1(a and b), is the most difficult operation in the stamping process due to the small distance between the flanges and the small corner radii at the flanges, as displayed in Fig. 1(c). This geometric complexity was caused by a dramatic change in the corner radius when the flange

24、 of hinge gets too close to the edge of the notebook, which would easily cause fracture defect around the flange of hinge and require a multi-operation stamping process to overcome this problem. In the present study, the formability of LZ magnesium alloy sheets was investigated and an optimum multi-

25、operation stamping process was developed to reduce the number of operational procedures using both the experimental approach and the finite element analysis.Fig. 1.Flange of hinges at notebook top cover case. (a) Hinge, (b) top cover case and (c) flanges of hinge.View thumbnail images2. Mechanical p

26、roperties of magnesium alloy sheetsThe tensile tests were performed for magnesiumlithium alloy sheets of LZ61 (lithium 6%, zinc 1%), LZ91, and LZ101 at room temperature to compare their mechanical properties to those of AZ31 sheets at elevated temperatures. Fig. 2(a) shows the stressstrain relations

27、 of LZ sheets at room temperature and those of AZ31 sheets at both room temperature and 200C. It is noted that the stressstrain curve tends to be lower as the content of lithium increases. It is also observed from Fig. 2(a) that the curves of LZ91 sheet at room temperature and AZ31 sheet at 200C are

28、 close to each other. LZ101 sheet at room temperature exhibits even better ductility than LZ91 and AZ31 do at 200C. Since the cost of lithium is very expensive, LZ91 sheet, instead of LZ101 sheet, can be considered as a suitable LZ magnesium alloy sheet to render favorable formability at room temper

29、ature. For this reason, the present study adopted LZ91 sheet as the blank for the notebook top cover case and attempted to examine the formability of LZ91 at room temperature. In order to determine if the fracture would occur in the finite element analysis, the forming limit diagram for the 0.6mm th

30、ick LZ91 sheet was also established as shown in Fig. 2(b).Fig. 2.Mechanical properties of magnesium alloy. (a) The stressstrain relations of magnesium alloy; (b) forming limit diagram (FLD) of LZ91 sheet.View thumbnail images3. The finite element modelThe tooling geometries were constructed by a CAD

31、 software, PRO/E, and were converted into the finite element mesh, as shown in Fig. 3(a), using the software DELTAMESH. The tooling was treated as rigid bodies, and the four-node shell element was adopted to construct the mesh for blank. The material properties and forming limit diagrams obtained fr

32、om the experiments were used in the finite element simulations. The other simulation parameters used in the initial run were: punch velocity of 5mm/s, blank-holder force of 3kN, and Coulomb friction coefficient of 0.1. The finite element software PAM_STAMP was employed to perform the analysis, and t

33、he simulations were performed on a desktop PC.Fig. 3.The finite element simulations. (a) Finite element mesh and (b) fracture at the corners.View thumbnail imagesA finite element model was first constructed to examine the one-operation forming process of the hinge. Due to symmetry, only one half of

34、the top cover case was simulated, as shown in Fig. 3(a). The simulation result, as shown in Fig. 3(b), indicates that fracture occurs at the corners of flanges, and the minimum thickness is less than 0.35mm. It implies that the fracture problem is very serious and may not be solved just by enlarging

35、 the corner radii at the flanges. The finite element simulations were performed to study the parameters that affect the occurrence of fracture. Several approaches were proposed to avoid the fracture as well.4. Multi-operation stamping process designIn order to avoid the occurrence of fracture, a mul

36、ti-operation stamping process is required. In the current industrial practice, it usually takes at least ten operational procedures to form the top cover case using the magnesium alloy sheet. In the present study, attempts were made to reduce the number of operational procedures. Several approaches

37、were proposed to avoid the fracture, and the four-operation stamping process had demonstrated itself as a feasible solution to the fracture problem. To limit the length of this paper, only the two-operation and the four-operation stamping processes were depicted in the following.4.1. Two-operation s

38、tamping processThe first operation in the two-operation stamping process was sidewall forming as shown in Fig. 4(a), and the second one was the forming of flange of hinge presented in Fig. 4(b), the height of the flange of hinge being 5mm. Fig. 4(c) shows the thickness distribution obtained from the

39、 finite element simulation. The minimum thickness of the deformed sheet was 0.41mm and the strains were all above the forming limit diagram. It means the fracture defect could be avoided. In addition, the height of the flange conformed to the target goal to be achieved. However, this process produce

40、d a critical defect of wrinkling, as shown in Fig. 4(d), on the flange of hinge, which induces a problem in the subsequent trimming operation. Hence, even though the two-operation stamping process solved the fracture problem at the corner of the bottom and the flange of hinge, a better forming proce

41、ss is still expected to solve the wrinkling of flange of hinge.Fig. 4.Two-operation stamping process. (a) Formation of sidewalls, (b) formation of hinges, (c) thickness distribution and (d) wrinkle.View thumbnail images4.2. Four-operation stamping processThe four-operation forming process proposed i

42、n the present study starts with the forming of three sidewalls and the flange of the hinge with a generous corner radius, as shown in Fig. 5(a). Since the sidewall close to the flange was open and the corner radius was larger than the desired ones, the flange was successfully formed without fracture

43、. Such process successfully avoided the difficulty of forming two geometric features simultaneously, but increased the material flow of the blank sheet. The next step was to trim the blank outside the sidewalls, and to calibrate the corner radius of 4mm to the desired value of 2.5mm. The hinge was t

44、hus formed, as shown in Fig. 5(b). The third step was to fold the open side, so that the sidewall could be completed around its periphery, as shown in Fig. 5(c). The effect of trimming the extra sheet outside the sidewalls in the second step on the third step was studied. When the extra sheet was no

45、t trimmed, the thickness at the corner was 0.381mm, as shown in Fig. 5(d). The thickness of the corner increased to 0.473mm, as shown in Fig. 5(e), if the trimming was implemented in the second step. The excessive material produced by the folding process in the third step was then trimmed off accord

46、ing to the parts design. The last step was the striking process that is applied to calibrate all the corner radii to the designed values. The minimum thickness at the corner of the final product was 0.42mm, and all the strains were above the forming limit diagram. It is to be noted that Fig. 5(ac) o

47、nly shows the formation of one hinge. The same design concept was then extended to the stamping process of the complete top cover case.Fig. 5.Four-operation stamping process. (a) First operation, (b) second operation, (c) third operation, (d) without trimming and (e) with trimming.View thumbnail ima

48、ges5. Experimental validationIn order to validate the finite element analysis, an actual four-operation stamping process was conducted with the use of 0.6mm thick LZ91 sheet as the blank. The blank dimension and the tooling geometries were designed according to the finite element simulation results.

49、 A sound product without fracture and wrinkle was then manufactured, as shown in Fig. 6(a). To further validate the finite element analysis quantitatively, the thickness at the corners around the hinge of the sound product, as shown in Fig. 6(b), were measured and compared with those obtained from t

50、he finite element simulations, as listed in Table 1. It is seen in Table 1 that the experimental data and the finite element results were consistent. The four-operation process design based on the finite element analysis was then confirmed by the experimental data.Fig. 6.The sound product. (a) Witho

51、ut fracture and wrinkle and (b) locations of thickness measured.View thumbnail imagesTable 1. Comparison of thickness measuredABCDExperiment0.42mm0.44mm0.49mm0.53mmSimulation0.423mm0.448mm0.508mm0.532mmError0.71%1.79%3.54%0.38%Full-size table6. Concluding remarksThe press forming of magnesium alloy

52、sheets was studied in the present study using the experimental approach and the finite element analysis. The formability of both AZ31 and LZ sheets was examined first. The research results indicated that the LZ91 sheet has favorable formability at room temperature, which is similar to that of AZ31 s

53、heet at the forming temperature of 200C.The superior formability of LZ91 sheet at room temperature was also demonstrated in the present study by successful manufacturing of the notebook top cover case. The proposed four-operation process lends itself to an efficient approach to form the hinge in the

54、 notebook with fewer operational procedures than that required in the current practice.It also confirms that the notebook cover cases can be produced with LZ91 magnesium alloy LZ91 sheet by the stamping process. It provides an alternative to the electronics industry in the application of magnesium a

55、lloys.AcknowledgmentsThe authors would like to thank the National Science Council of the Republic of China for financially supporting this research under the Project No. NSC-95-2622-E-002-019-CC3, which made this research possible. They would also like to thank ESI, France for the help in running th

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