精密鑄造冷接缺陷及疏鬆缺陷的形成機理及改善方案：以316L不鏽鋼渦流閥件的數值模擬與實驗驗證為例;The formation mechanism and correction plan of cold shut and porosity defects in investment casting: Numerical simulation and experimental verification of 316L stainless steel vortex flowmeters

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Title:	精密鑄造冷接缺陷及疏鬆缺陷的形成機理及改善方案：以316L不鏽鋼渦流閥件的數值模擬與實驗驗證為例;The formation mechanism and correction plan of cold shut and porosity defects in investment casting: Numerical simulation and experimental verification of 316L stainless steel vortex flowmeters
Authors:	陳庭儀;Chen, Ting-Yi
Contributors:	機械工程學系
Keywords:	渦街流量計;冷接;表面缺陷;熔模鑄造;316L 不鏽鋼
Date:	2023-07-28
Issue Date:	2024-09-19 17:41:05 (UTC+8)
Publisher:	國立中央大學
Abstract:	渦流閥件（VFM）是一種廣泛用於石化工業的流量計，且需要高精度的表面尺寸。由於其複雜的幾何形狀，生產過程很容易產生缺陷，冷接（CS）缺陷尤其常見，發生率高達42.6%。滲透檢測可以揭示缺陷的嚴重程度和位置，而光學顯微鏡（OM）、X射線繞射（XRD）分析和視覺量測系統（CCD）可以深入瞭解其缺陷形成和形態。本研究採用C3P模擬軟體的數值類比和實驗驗證，分析了渦流閥件CS缺陷的原因，排除了人工澆注引起的澆注時間不同的因素。文獻表明，模具厚度不足和金屬液體溫度會降低金屬的流動性，並可能產生CS缺陷。在確定缺陷的原因后，設計了有效的預防措施，其中包括在深壁和薄壁位置使用陶芯替換外殼。虛擬熱動力感測器（VTDS）用於分析陶芯安裝前後該區域的溫度分佈。結果表明，由於陶瓷材料的高導熱性，安裝陶芯後的溫度分佈明顯更高，減少了區域幾何導致製殼困難所引起的殼厚不足，這使得熔融金屬能夠平穩地流過薄壁區域。最後，該預防措施成功地將缺陷發生率降低到0%。;The vortex flow meter (VFM) is a flowmeter widely used in the petrochemical industry that requires high precision in surface dimensions. Due to its complex geometry, the production process can easily generate defects, with cold shut (CS) defects being particularly common, occurring up to 42.6% of the time. Penetrant inspection can reveal the severity and location of defects, while optical microscopy (OM), X-ray diffraction (XRD) analysis, and Charge-coupled Devices (CCD) can provide insights into their formation and morphology. This study employs numerical simulations using C3P simulation software and experimental verifications to analyze the causes of CS defects in vortex flowmeters, ruling out the factor of different pouring time caused by manual casting. Literature suggests that insufficient mold thickness and metal liquid temperatures reduce the fluidity of the metal and may produce CS defects. Effective preventive measures were designed after identifying the causes of defects, which involved using ceramic cores to replace the shell at deep and thin-walled locations. A virtual thermo-dynamic sensor (VTDS) was used to analyze the temperature distribution in the area before and after the installation of ceramic cores. The results indicate that the temperature distribution after installing the ceramic core is significantly higher, reducing the insufficient shell thickness caused by coating while promoting even heat distribution due to the high thermal conductivity of ceramic materials. This enables smooth flow of the molten metal through the thin-walled areas. Finally, this preventive measure successfully reduced the defect occurrence rate to 0%
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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