전문가 시스템을 이용한 주조법 결정

김종도(Jong-Do Kim),윤문철(Moon-Chul Yoon) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.6

In industry, several casting process are widely used to manufacture complex and accurate blank part of hard materials such as aluminum, casting steels, bronze and magnesium alloys which are difficult to manufacture in a blank shape. Even if the casting process does not high accuracy superior surface characteristics other machining process, the casting process is widely used in manufacturing blank part. Furthermore, it is difficult to select appropriate casting process a part among several casting process. for effective selection different process, a careful decision given casting application is necessary. An appropriate casting for a given material and shape condition must be selected for novice engineers in industry. In this paper, an expert system based on an analytic network process(ANP) is suggested for best selection of casting considering a prior interdependency effect among various factors such as material, geometry, process capability, economy and equipment.

Improvement of structural design accuracy using a casting-structural interface(CSI) method in large-scale sand castings

Jae Hyun Yu,Zhi jun Zhao,손창민,박상후 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.12

In general, thermal residual stress is generated in casting products as a result of non-uniform cooling, phase transformation from liquidto solid states, and thermo-mechanical constraints. Thus, understanding accurate stress distributions is important in designing a castingpart to predict its real structural stability. However, the residual stress that occurs in the casting process is often not considered in themechanical design process to reduce engineering efforts and time. We conducted a structural analysis that compares two cases with andwithout considering casting residual stress in large-scale sand castings and obtained significantly different results. We introduced an interfacingalgorithm (casting-structural interface) to map the casting residual stress with structural stress and combined the results of finitedifferent analysis for casting and finite element analysis for structural design. This work represents our preliminary studies on improvingthe design accuracy of a large-scale casting part and shows the importance of considering the casting residual stress. A difference ofabout 41% in maximal principle stress is obtained with and without considering the casting residual stress.

터치 스크린 기반 금속 주조 공정 관리 시스템 개발

김정숙(Jung-Sook Kim),김재형(Jae-Hyeong Kim),정준호(Jun-Ho Jeong),정장영(Jang-Young Chung) 한국지능시스템학회 2013 한국지능시스템학회논문지 Vol.23 No.3

본 논문에서는 스마트 금속 주조 공정 관리 시스템을 사례 기반을 적용해 윈도우 환경에서 개발하였다. 금속 주조는 가장 일반적인 주조 공정이다. 이러한 금속 주조 공정은 복잡하고 각각의 해당 작업에 따라 작업 공정이 변하는 특성을 가진다. 특히 금속 주조 산업의 특성은 다양한 종류의 제품을 생산한다. 따라서 본 논문에서 개발한 스마트 금속 주조 생산 공정관리 시스템은 복잡한 공정 과정을 사례에 기반한 추론을 통해 지능적으로 공정 단계를 생성하는 시스템이다. 따라서 본 논문에서 이들을 효과적으로 해결할 수 있는 금속 주조 생산 공정 관리 시스템을 터치스크린을 기반으로 개발하였다. 시스템에 대한 실험 결과는 수작업으로 하던 공정 관리보다 더욱 생산성이 향상되었다. In this paper, we describe the smart metal casting processing management system, in which we applied case-based reasoning on the window environment. Metal casting is one of the most common casting processes. The metal casting processing is complex and variable depends on a kind of metal casting products. Especially, the metal casting industry has a feature which produces small quantities but produces a lot of different types of metal casting products. And we developed the smart metal casting processing management system which could show the processing route according to the product cases intelligently using the result of case-based reasoning. The experimental result shows that our metal casting processing management system schemes achieves more productivity than manual management schemes.

ESPI 장비를 활용한 사형 주조품의 잔류응력 측정 및 주조 열응력 해석

곽시영,남정호 한국주조공학회 2020 한국주조공학회지 Vol.40 No.1

Many studies involving a thermal stress analysis using computational methods have been conducted, though there have been relatively few experimental attempts to investigate thermal stress phenomena. Casting products undergo thermal stress variations during the casting process as the temperature drops from the melting temperature to room temperature, with gradient cooling also occurring from the surface to the core. It is difficult to examine thermal stress states continuously during the casting process. Therefore, only the final states of thermal stress and deformations can be detemined. In this study, specimens sensitive to thermal stress, were made by a casting process. After which the residual stress levels in the specimens were measured by a hole drilling method with Electron Speckle-Interferometry technique. Subsequently, we examined the thermal stresses in terms of deformation during the casting process by means of a numerical analysis. Finally, we compared the experimental and numerical analysis results. It was found that the numerical thermal stress analysis is an effective means of understanding the stress generation mechanism in casting products during the casting process.

다이캐스팅 공정 지능화를 위한 데이터 수집, 처리, 분석 및 활용 기술 개발

이주연(Ju Yeon Lee) 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.6

This study aims to achieve process intelligence by implementing a technology that collects, processes, analyzes, and utilizes data of die-casting processes. To achieve this goal, the system infrastructure, including hardware and software, was established to collect, process, and store data of the main die-casting processes, i.e., casting, post-processing, and quality inspection. Next, data analysis algorithms were developed to address die-casting quality problems by using the data collected from the established infrastructure. Finally, a 3D model-based visualization technology was implemented to visualize the data analysis results and support the monitoring of important data. The proposed technology was verified by implementing it in an actual die-casting factory. Furthermore, a reference model was presented for implementing the intelligent die-casting processes.

Improvement in the hygroscopicity of inorganic binder through a dual coating process

Choi, Hyun-Hee,Kim, Eun-Hee,Lee, Hye-Ju,Kim, Bong-Gu,Jung, Yeon-Gil,Zhang, Jing Elsevier Sequoia 2019 Progress in organic coatings Vol.135 No.-

<P><B>Abstract</B></P> <P>The use of an anti-absorbent is proposed in this work to reduce the hygroscopicity of the inorganic binder in the casting mold, in which the anti-absorbent is coated on the mold prepared with an inorganic binder. Three types of polymers were used to select material with optimal water resistance. Polystyrene (PS) and polyvinyl alcohol (PVA) were used as a water-insoluble polymer and water-soluble polymer, respectively. In addition, polyurethane (PU) prepolymer has intermediate properties between PS and PVA. PVA and PU prepolymer were used for comparative testing with PS. For this testing process, the prepared green body was dipped into a solution of inorganic binder precursor mixed with tetraethyl orthosilicate (TEOS, SiO<SUB>2</SUB> precursor) and sodium methoxide (NaOMe, Na<SUB>2</SUB>O precursor), and then dipped into a solution of coating reagent after a drying process. Thus, these series of coating processes in a green body is called a dual coating process. Finally the sample was heat-treated at 1000 °C to generate a glass phase by an organic–inorganic conversion process. In the sample prepared with PS, the highest contact angle and a high firing strength were exhibited, independent of polymer concentration, while the sample coated with PVA showed lower green and firing strengths. When prepolymer, PU, was applied, the green strength was remarkably improved, showing lower firing strength compared with that of PS. The green and firing strengths were optimized through the dual coating process with PS. Moreover, the moisture-proof effect of the dual coating process was verified through the moisture steam test.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Development of a <I>new</I> coating process reduced the hygroscopicity of inorganic binder. </LI> <LI> The highest firing strength was <I>obtained</I> in a mold coated with polystyrene (PS). </LI> <LI> The desirable strength was shown in a mixture of PS and polyurethane (PU) prepolymer. </LI> <LI> The contact angle increased in the order of polyvinyl alcohol (PVA), PU, and PS. </LI> <LI> PS and the PU prepolymer were preferable to increase the moisture absorption effect. </LI> </UL> </P>

Effects of Reduced Pressure and Coat Permeability on Casting Characteristics of Magnesium Alloy in Evaporative Pattern Casting Process

Lee, Kyong-Whoan,Cho, Gue-Serb,Choe, Kyeong-Hwan,Jo, Hyung-Ho,Ikenaga, Akira,Koroyasu, Sadatoshi The Japan Institute of Metals 2006 MATERIALS TRANSACTIONS Vol.47 No.11

<P>A magnesium alloy was adopted to an evaporative pattern casting (EPC) process to combine advantages of each. In the present study, foam patterns were cast at a top gating system under atmospheric and reduced pressure to evaluate casting characteristics of AZ91D to develop a complete EPC process for high productivity of magnesium alloy castings. Filling time and temperature of molten metal were measured during mold filling. It was recognized that the average filling velocity was affected by the difference of the coating material and the degree of reduced pressure. The grain size of the magnesium alloy was slightly dependent on the degree of reduced pressure. It was considered that the application of the high reduced pressure, which changed the shape of melt surface from convex to concave, was related to the occurrence of internal defects such as cold shut laps or folds in the casting.</P>

Integration of Additive Manufacturing in Casting: Advances, Challenges, and Prospects

Mengdi Gao,Lei Li,Qingyang Wang,Zhilin Ma,Xinyu Li,Zhifeng Liu 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.1

Additive manufacturing (AM) is a novel manufacturing technology that can create highly customized products with more complex geometries than traditional techniques. Despite its significant advantages, including the freedom of design, mass customization, and ability to produce complex structures, AM consumes a large amount of energy and incurs high costs. In addition, AM suffers from long production cycles and low production efficiency in the large-scale manufacturing of metal structures. This study offers a review of the existing literature focused on metal AM technology. To avoid the shortcomings of AM and highlight its bene fits, which are widely used for manufacturing in combination with casting. The current combination application of AM and casting is reviewed to provide solutions to the problem of manufacturing large metal components from the perspective of the use of different AM technology and quality control in casting. However, such integration is insufficient for producing large castings with complex shapes, structures, or multiple features. Therefore, a novel method for integrating AM into casting to enable the manufacture of large scale metal parts with complex shapes is introduced as a topic for possible future research. This method divides complex castings with multiple features into an AM processing part and the casting substrate. The complex features were processed by AM on the fabricated casting substrate. This study provides a review of the application of AM into casting and presents a novel idea for the integration application of AM and other processes. This promising method has significant value for future study.

Adaptive neural network controller for the molten steel level control of strip casting processes

Hung-Yi Chen,Shiuh-Jer Huang 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.3

The twin-roll strip casting process is a steel-strip production method which combines continuous casting and hot rolling processes. The production line from molten liquid steel to the final steel-strip is shortened and the production cost is reduced significantly as compared to conventional continuous casting. The quality of strip casting process depends on many process parameters, such as molten steel level in the pool, solidification position, and roll gap. Their relationships are complex and the strip casting process has the properties of nonlinear uncertainty and time-varying characteristics. It is difficult to establish an accurate process model for designing a model-based controller to monitor the strip quality. In this paper, a model-free adaptive neural network controller is developed to overcome this problem. The proposed control strategy is based on a neural network structure combined with a sliding-mode control scheme. An adaptive rule is employed to on-line adjust the weights of radial basis functions by using the reaching condition of a specified sliding surface. This surface has the on-line learning ability to respond to the system’s nonlinear and time-varying behaviors. Since this model-free controller has a simple control structure and small number of control parameters, it is easy to implement. Simulation results, based on a semiexperimental system dynamic model and parameters, are executed to show the control performance of the proposed intelligent controller. In addition, the control performance is compared with that of a traditional PID controller.

BSCCO(2212) 벌크 초전도체의 주조조건 및 SrSO₄ 최적함량에 대한 연구

김규태,박의철,장석헌,임준형,주진호,김찬중,김혜림,현옥배,Kim Kyu-Tae,Park Eui-Cheol,Jang Seok-Hern,Lim Jun-Hyung,Joo Jin-Ho,Kim Chan-Joong,Kim Hye-Rim,Hyun Ok-Bae 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.6

We fabricated BSCCO-2212 (2212) rod by the melt casting process (MCP) and evaluated the effect of the melt flowing on the critical current ($I_c$) by using vertical and tilt casting. It was observed that the $2212-SrSO_4$ rod processed by the tilt casting method with homogeneous pre-heating temperature of the mold had a higher $I_c$ than that processed by the vertical casting method. We also evaluated the influence of the strontium sulfates ($SrSO_4$) addition on the texture, microstructure, critical current and temperature, and mechanical hardness of the $2212-SrSO_4$ rods. It was observed that the addition of $SrSO_4$ improved the critical current ($I_c$) and mechanical hardness of the 2212. The $I_c$ of the 2212 increased as the $SrSO_4$ content increased and reached a peak value (260 A at 77 K) at an $SrSO_4$ content of 6 wt.%. In addition, the addition of $SrSO_4$ had a beneficial effect on the mechanical hardness of the 2212. We studied the possible cause of the variation in the $I_c$ with the melt flowing and the $SrSO_4$ content based on the XRD, EPMA analysis and the microstructural observation.