• 소성∙가공
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• 제17권6호
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• pp.412-419
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• 2008

Using lightweight materials in vehicle manufacturing in order to reduce energy consumption is one of the most effective approach to decrease pollutant emissions. As a lightweight material, magnesium is increasingly employed in automotive parts. However, because of its hexagonal closed-packed(HCP) crystal structure, in which only the basal plane can move, the magnesium alloy sheets show low ductility and formability at room temperature. Thus the press forming of magnesium alloy sheets has been performed at elevated temperature within range of $200^{\circ}C{\sim}250^{\circ}C$. Here we try the possibility of sheet metal forming at room temperature by adopting incremental forming technique with rotating tool, which is so called as rotational-incremental sheet forming(RISF). In this rotational-incremental sheet forming the spindle tool rotates on the surface of the sheet metal and moves incrementally with small pitch to fit the sheet metal on the desired shape. There are various variables defining the formability of sheet metals in the incremental forming such as speed of spindle, pitch size, lubricants, etc. In this study, we clarified the effects of spindle speed and pitch size upon formability of magnesium alloy sheets at room temperature. In case of 0.2, 0.3 and 0.4mm of pitch size with hemispherical rotating tool of 6.0mm radius, the maximum temperature at contact area between rotating tool and sheet metal were $119.2^{\circ}C,\;130.8^{\circ}C,\;and\;177.3^{\circ}C$. Also in case of 300, 500, and 700rpm of spindle speed, the maximum temperature at the contact area were $109.7^{\circ}C,\;130.8^{\circ}C\;and\;189.8^{\circ}C$.

• Journal of Mechanical Science and Technology
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• 제18권5호
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• pp.770-779
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• 2004

This paper describes the micro cutting of wear resistant tungsten carbides using PCD (Poly-Crystalline Diamond) cutting tools in performance with SEM (Scanning Electron Microscope) direct observation method. Turning experiments were also carried out on this alloy (V50) using a PCD cutting tool. One of the purposes of this study is to describe clearly the cutting mechanism of tungsten carbides and the behavior of WC particles in the deformation zone in orthogonal micro cutting. Other purposes are to achieve a systematic understanding of machining characteristics and the effects of machining parameters on cutting force, machined surface and tool wear rates by the outer turning of this alloy carried out using the PCD cutting tool during these various cutting conditions. A summary of the results are as follows: (1) From the SEM direct observation in cutting the tungsten carbide, WC particles are broken and come into contact with the tool edge directly. This causes tool wear in which portions scrape the tool in a strong manner. (2) There are two chip formation types. One is where the shear angle is comparatively small and the crack of the shear plane becomes wide. The other is a type where the shear angle is above 45 degrees and the crack of the shear plane does not widen. These differences are caused by the stress condition which gives rise to the friction at the shear plane. (3) The thrust cutting forces tend to increase more rapidly than the principal forces, as the depth of cut and the cutting speed are increased preferably in the orthogonal micro cutting. (4) The tool wear on the flank face was larger than that on the rake face in the orthogonal micro cutting. (5) Three components of cutting force in the conventional turning experiments were different in balance from ordinary cutting such as the cutting of steel or cast iron. Those expressed a large value of thrust force, principal force, and feed force. (6) From the viewpoint of high efficient cutting found within this research, a proper cutting speed was 15 m/min and a proper feed rate was 0.1 mm/rev. In this case, it was found that the tool life of a PCD tool was limited to a distance of approximately 230 m. (7) When the depth of cut was 0.1 mm, there was no influence of the feed rate on the feed force. The feed force tended to decrease, as the cutting distance was long, because the tool was worn and the tool edge retreated. (8) The main tool wear of a PCD tool in this research was due to the flank wear within the maximum value of $V_{max}$ being about 260 $\mu\textrm{m}$.

• Architectural research
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• 제13권2호
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• pp.3-12
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• 2011

Planning information generated during initial architectural design phases significantly influences subsequent phases, and is implemented into architectural design models during the design process. However, failures to manage and use planning information in Korean design offices remain common. Current design tools that incorporate planning information also do not address the issue of interoperability during the life cycles of buildings. To address these problems, the Industry Foundation Classes (IFC) extension model was developed to accommodate the need to manage and use planning information for cooperation between design offices carrying out multidisciplinary tasks. This paper introduces a purpose-built software tool that implements the IFC model and demonstrates the efficiency of the proposed method with the software tool.

• 소성∙가공
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• 제7권3호
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• pp.282-290
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• 1998

In bulk metal forming processes prediction of tool life is very important for saving production cost and achieving good material properties. Generally the service life of tools in metal forming process is limited to a large extent by wear, fracture and plastic deformation of tools. In case of hot and warm forging processes tool life depends on wear over 70%. In this study finite element analyses are con-ducted to warm and hot forging by adopting suggested wear model. By comparison of simulation and eal profile of die suggested wear model. By comparison of simulation and real profile of die suggested model is verified.

• 한국생산제조학회지
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• 제9권2호
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• pp.66-71
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• 2000

Laser induced surface hardening of Tool steel(STC5) can be achieved either with or without surface melting. In trans-formation hardening as the surface is heated to a temperature below its melting point and is rapidly cooled solidified microstructures are usually much finer and stronger than those of the base matals. For this reason surface modification of tool steel by YAG laser irradiation has been studied as a function of processing parameters such as power density pulse width defocusing distance and molten depth. The high energy density changes and refines the microstructure of the near surface layer. In the case of beam passes martensite formed in the melt zone exhibited very high vickers hardness values. Molten depth and width depend on defocusing distance and energy of black color painting is more absorptive than other color painting.

• 한국생산제조학회지
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• 제4권3호
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• pp.67-76
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• 1995

An experimental study of hot machining has performed to improve the machinability of Inconel718. This experiment used plasma are for heating materials and Whisker0reinforce aluminum oxide ceramic tool insert. An assembled plasma heating system are described and experimental results from both conventional and plasma hot machining of Inconel 718 are compared. The experiments with plasma heating demonstrated the following effectiveness. 1)The cutting force was reduced with increasing surface temperature of workpiece from 450$^{\circ}C$ up to 720$^{\circ}C$ as much as approximately from 20 to 40%. 2) Surface roughness(Ra) was improved by as much as a factor 2 in case of one pass cutting with new ceramic tool inserts.3) The depth of cut notch were at promary cutting tool was significantly reduced.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1590-1594
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• 2007

This paper describes a case study on dynamic characteristics analysis of a 5-axis multi-tasking machine tool of ram-head typed. Natural frequency and corresponding vibration modes of the machine tool structure were obtained by using both FEM modal analysis and an experimental modal test(impulse hammer test). Both the theoretical and experiment analysis results showed good agreement with each other. Finally, some discussion and review, from the view point of resonance vibration and/or mode coupled chatter, were made based on the analysis results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1191-1194
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• 1995

A conversational programming system for turning processes was studied to enhance the user friendlness of an NC by adopting man-machine interface functions through Visual C $^{++}$ programming tool under the Windows 95 environment. Shop floor programming performance was incorporated in the developed CAM module. In order to increase flexibility of the man-machine interface, graphic based programmin tool have been developed. An NC turning machine equipped whit an open architecture PCNC was used as a test bed of the system. Perfomance of the system was verified through case studies..

• 산업공학
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• 제16권2호
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• pp.156-166
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• 2003

Proposed in this paper is a standard-compliant business process modeling tool which is based on the UML(Unified Modeling Language) activity diagram and produces an XPDL(XML Process Definition Language) file as an output. The XPDL is a standard process definition exchange format by WfMC (Workflow Management Coalition). To develop an UML/XPDL-based modeling tool, the mapping of modeling elements between activity diagram and XPDL format is conducted after the detailed analysis of each modeling specification. As a result of this mapping, it is revealed that modeling elements of each activity diagram and XPDL must be expanded. So new modeling elements are identified and added to each specification. Based on this mapping, the prototype system is developed, and the usefulness of the developed system is shown through the case study.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.17-20
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• 2006

Inside the global management environment that is going through sudden changes, businesses are concentrating on putting in much hard work to establish the most competitive management strategy for its survival. As a executing tool and following the strategy establishment, BSC is being introduced and used by many businesses and public institutions, but instead of being used as a tool with the proper purpose of executing strategies, in reality, it is mainly being used to measure and evaluate outcomes. Of the several reasons why this is so, one important issue and its fundamental cause is that although BSC had been developed as a strategy executing tool, it is diffcult to understand the degree of execution of strategies because the overall measurement of the KPI includes all the strategic and operational parts. Through case study, this article acts on presenting the methodology of measuring the degree of execution of strategies that apply the BSC and PM frameworks.