材料加工專(zhuān)業(yè)英文翻譯--在拉深件內(nèi)使用空氣壓提高鋁板的拉深極限比-展示頁(yè)
2025-05-26 13:58本頁(yè)面
【正文】 Sung Rak Gong 凈成形與模具制造工程研究中心 釜山國(guó)立大學(xué) 該研究主要是通過(guò)研究使用空氣壓對(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。 to the radius does not significantly affect the limiting drawing ratio(LOR). Therefore, according to the thickness of the blank, the most suitable shoulder radii for the dies and punches were selected to be 6mm with a constant punch diameter of . Test procedure A proper drawing speed is important for the deep drawing 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 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 and the punch forces are measured simultaneously as function of test variables. The airpressure is applied until the load 7 reaches the maximum load because the airpressing after reaching the maximum load no longer affect better deep drawability. Each test is repeated two or three times, average values being obtained. All experiments were carried out by the cupdrawing operation shown in Fig. 3 and experimental variables applied in this study are described in Table 2. Press oil, mercial grade high pressure hydraulic oil, is brushed on to the blank before forming to diminish the friction at the contact interface. The effectiveness of the airpressing 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. 3. Results and Discussion 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 blank 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. 8 Figure 4 shows the variation of LOR with increasing air pressure for AI1050 and Fig. 5 shows photograph of deep drawn cups at given process conditions. Above figures show that higher LOR is obtained at higher internal airpressure. The reason for the increased LOR at higher air pressure can be explained by thickness profile of cross sectioned cup shown in Fig. 6. Figure 6 shows that the overall thickness of deep drawn cup and the degree of thickness 9 variation at rounding part are decreased at the air pressure of 70 kg/mm39。 Chen and Sowerby,1996). It is well recognized that a high plastic anisotropy value(rvalue) clearly indicated a better drawability, by inducing a high resistance of a sheet to thinning. But there is no single material parameter which satisfactorily describes the drawing behavior. In this work, the effect of internal pressing on the formability of aluminum sheet is investigated to increase the LOR of aluminum alloys. 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 beginning to draw the sheetmetal blank into the die cavity. If the blank size has been chosen correctly, the metal will work harden sufficiently to overe the bined strength of the remainder of the blank metal and friction between it and the blank holder and the part will be successfully made. However, if the blank is too large, the part will break when the tensile strength is exceeded. The first deformation of the blank occurs between the die radius and the punchnose radius part, since this is the part that is not supported by friction with the tooling ponents. The metal in this section is increasing in area as it thins out and losing 4 much of
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