Optimal Design of Investment Casting System for a Stuffing Box with Pedestal of Centrifugal Pump: Computer Simulations and Experimental Verification

基於數值模擬與實驗研究之泵浦底座澆鑄系統設計

郭振坤(Jenn-Kun Kuo) ； 黃培興(Pei-Hsing Huang) ； 蔡鈺鼎(Yu-Ting Tsai) ； 鍾齊(Zhong Qi) ； 周春禧(Chuen-Shii Chou)

《中國機械工程學刊》 41卷5期 (2020/10) Pp. 551-563

摘要

The stuffing box with pedestal (SBP) is a major component in centrifugal pumps (CPs). It is responsible for the transfer of load generated in the CP to the baseplate of the pump and finally to the ground. SBPs are usually fabricated using investment casting; however, this process is prone to residual casting defects, which can reduce mechanical strength and increase the likelihood of crack formation following long-term usage. In this study, the AnyCasting numerical simulation software package was used to optimize the investment parameters for the casting of an SBP in SUS304 alloy. Optimization efforts targeted the shrinkage cavity (based on retained melt modulus) and porosity defects (based on Niyama criterion). The results of preliminary simulations and experiments informed the establishment of five casting schemes for subsequent simulation. We used virtual thermodynamic sensors to determine the rate and direction of solidification in the mold cavity, and also investigated variations in the velocity of the molten metal at the inlets of the gating system as a function of time. The optimal casting parameters derived in simulations were assessed by fabricating an SBP via investment casting in a domestic foundry. Nondestructive testing based on X-ray analysis revealed none of the detrimental defects commonly associated with this type of casting.

關鍵字

investment casting ； centrifugal pump ； stuffing box with pedestal ； retained melt modulus ； Niyama criterion

並列摘要

帶填料函的基座是離心泵的主要組成部件。它負責將離心泵產生的負載移轉到泵的底板及地基上，通常採用熔模鑄造製造。但是此工藝容易產生殘餘鑄造缺陷，因而降低機械強度並增加長期使用後形成裂紋的可能性。本研究基於有限差分法之電腦輔助金屬模流分析技術，針對改善精密鑄造中常見之巨觀縮孔、微觀縮鬆與氣孔缺陷，於SUS304不銹鋼泵浦底座產品之澆鑄系統優化設計。初步模擬和實驗的結果為隨後的模擬提供了五個鑄造方案的建立。我們使用虛擬的熱力學傳感器來確定型腔中鐵水的凝固速率和方向，並且還研究了澆口系統入口處的熔融金屬速度隨時間的變化，通過在國內鑄造廠之驗證獲得熔模鑄造SBP製程之最佳鑄造參數。