機(jī)械類、模具類外文翻譯----在拉深件內(nèi)使用空氣壓提高鋁板的拉深極限比-模具設(shè)計(jì)(編輯修改稿)
2025-06-25 23:52 本頁面
【文章內(nèi)容簡(jiǎn)介】 t 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。39。, The relatively steep decrease in thickness at rounding part that had touched with punch nose radius reflects the local strain 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. Figure 7 shows the effect of the air pressure on the drawing. loaddisplacement curves. In general, an increase in the drawing force is observed for larger blank diameters due to the enlargement of fictional interfaces such as the dieblank 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 pressure. It means that the internal airpressing contribute to the reduction of drawing load possibly by reducing friction between punch and blank. In other words, the internal airpressing itself does not alter the deformation resistance of deforming sheet blanks. but has an effect on the manner of the transmission of the load at punch nose radius part and increases LOR of blank. Although the experimental conditions used in this study may not be the optimum for the highest LOR, the trends obviously shows that 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 airpressing process will be more prominent for 10 aluminum alloy sheets than mild steel sheets. 4. Conclusion The airpressing method is proved to be very effective in increasing the
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