Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1525
標題: 氣壓模墊於衝擊負荷下之有限元素研究
Finite Element Analysis of Pneumatic Die Cushion under Impact Loading
作者: 劉玄淞
Liu, Hsuan-Sung
關鍵字: Impact force;衝擊力;air cushion;LS-DYNA;氣壓模墊;LS-DYNA
出版社: 機械工程學系所
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摘要: 
一般沖床機械,以馬達為動力源驅動滑塊與上模具,使其具備動能,作為引伸、沖剪及摺彎等工作。在上模具未接觸板件時,壓板及板件是靜止不動的。壓板係經由氣壓模墊提供一壓板力,於引伸過程中,上模具與滑塊以一定速撞擊到板件與壓板,此瞬間在上模具、板件與壓板間產生一衝擊力,此衝擊力經由機件零件相互間的碰撞、磨擦與材料本身的剛性消除。此衝擊力對機械零件、引伸模具與壓板等的磨損與使用壽命有著重要的影響。衝擊力對機械的軸承受力、磨耗,會導致機械精度的重現性不良,對模具與壓板的磨損更是直接的因素,使製品表面受損,嚴重的更會導致製品成形困難與良率降低等。如能有效的改善並減少此衝擊力,將能提高機件使用壽命並減少零件費用因衝擊受損的支出。本研究以Pro/Engineerr建之沖床簡化模型,由有限元素軟體ANSYS進行壓板推擠氣壓模墊,形成壓板預負載,將其結果檔帶入LS-DYNA中,由定速上模具撞擊此壓板預負載,進行求解。有限元素結果分析,上模具於相同速度下,撞擊單一壓板預負載,其衝擊力是串聯壓板預負載的2倍。藉此結果反推於各種沖壓條件情況下,串聯式壓板預負載能有效的降低上模具衝擊力,供業界設計參考。

In typical die press machine industries, electric motor drives slider and dies, once the kinetic energy is transferred to associated mechanisms, deep drawn, shearing and bending process can be completed. In typical single die press mechanism for deep drawn process, blank holder is kept stationary until upper die is driven down to contact work piece. During deep drawn process, pneumatic die cushion will provide a pre-loaded pressure to blank holder, then upper die and slider is driven downward with a defined velocity, meanwhile, the force is transferred to work piece then to blank holder. During the process, with working cycle increased, continuous impact, friction will lead mechanical components such as bearings, dies. Overall precision of machine will be followed by wearing of the mechanical components. With the machine loses its overall, product components can possibly difficult to be built, high percentage of defective components will be constructed and costs of machine maintenance will increase.
If the impact force and wearing can be minimized, dies, bearing, and other the mechanical components their working life can be extended due to normal wear, then lower cost of machine maintenance will be the consequential result. This research uses Pro/Engineer as 3D modeling tool and using ANSYS as simulation tool. A simplified single slider die press was 1st created then motion with pre-loaded force was simulated using ANSYS with followed by impact simulation using LS-DYNA. In the simulation, two different blank holder pre-load methods were developed, single blank holder pre-load method and serial blank holder pre-load method. In single blank holder pre-load method, a defined velocity was applied for driving slider with upper die together downward to impact work piece and blank holder then the impact force received by the upper die and blank holder is obtained. In serial blank holder pre-load method is different from single blank holder pre-load, a simulated spring was placed between work piece and blank holder.
Comparing the results of two different pre-load methods, the impact force between die and blank holder, single blank holder pre-load method has about two times higher than serial blank holder pre-load method. The results of this study can be applied on for minimizing the wearing of dies, mechanical components of die press machine. This will provide a great opportunity for die press machine industries to lower their costs machine maintenance.
URI: http://hdl.handle.net/11455/1525
其他識別: U0005-0802201217080400
Appears in Collections:機械工程學系所

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