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題 名 | 消失模製程振砂之流動特性探討=Sand Flow for the Expendable Pattern Casting Process |
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作 者 | 張在源; 劉煌鑫; 施登士; | 書刊名 | 鑄工 |
卷 期 | 25:1=100 1999.03[民88.03] |
頁 次 | 頁1-10 |
分類號 | 472.2 |
關鍵詞 | 互鎖作用; 液化; 流動區; 共振; Interlock; Liquefaction; Floating zone; Resonance; |
語 文 | 中文(Chinese) |
中文摘要 | 在造模過程中,模砂的流動行為對於鑄件品質與模穴設計扮演著支配性的角色, 由於砂的顆粒間存在著強烈的摩擦力及互鎖作用,以致往往無法順利地將鑄砂輸送至窄而深 的水平保麗龍穴內以形成砂心,或貼切地包圍保麗龍模型四週;過於強制砂的流動則可能導 致保麗龍模型的變形或移位,此等均是造成不良鑄件的基本因素。因此,砂的流動行為是設 計模型及消失性模鑄造製程時必須考慮的基本參數。本實驗主要探討振動條件對於鑄造用乾 砂流動性的影響及砂體流動的機制;研究結果顯示單純的水平方向振動僅會造成砂體的壓 密,對於砂體流動作用不甚顯著。垂直方向振動之主要作用在於減少砂顆粒間之有效應力, 以使砂體呈液化狀態,再藉著水平向的驅動以使砂體流動,此時之流動效果較為顯著,有利 於砂的輸送。在砂表面層以下5~20公分以內之區域其橫向流動性最大,會形成一縮頸區。在 砂箱底層區由於砂箱之振幅不均勻性及砂粒間的接觸力隨深度而增加,其流動性逐漸降低。 二維振動時由於兩互為正交軸向間的相位差,在振動時會相耦合而起共振作用,對於砂體流 動形態會產生很大的作用。 |
英文摘要 | One of the most difficult problems in the expendable pattern casting (EPC) process is that, it is not easy to transport molding sand into long and narrow horizontal cavities or compacted properly around the coated patterns. The significant interlocking and the strong contacting forces among particles retard the sand from moving. An over-drastic vibration, however, might cause deformation or drift of the patterns. All the above situations might results in castings defects. The behavior of sand flow in flask thus plays an important role in design mold cavities or making decision of the molding parameters. The object of this experiment is to investigate the mechanisms of sand flow in flask during vibration for the EPC molding process. Experiment results revealed that a simple horizontal viration contributes minor efforts on sand motion. The main effect of vertical vibration is to liquefy the sand bulk, thus could enhance the fluidity of sand during vibration by reducing the effective stresses among sand particles. Two-dimensional vibration with frequencies at resonance might greatly increase the strength of sand flow, convection zones generated around the depth of 5~20cm from the free surface of the sand bulk. The strength of flow field depends mainly on exciting level (G-L) and the coupling of frequencies of the shaker. |
本系統中英文摘要資訊取自各篇刊載內容。