• International Journal of Precision Engineering and Manufacturing
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• 제2권3호
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• pp.69-78
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• 2001

This paper presents a process and operation planning system and an NC code post-processor for effective machining of press dies for production of cars. Based on the machining feature, major parts of press dies are categorized into 15 groups and a standard process plan is defined for each group. The standard process plan consists of a series of processes where a process is defined as a group of operations that can be done with one setup. Details such as cutting tools, cutting conditions, and tool paths are decided at the operation planning stage. At the final stage of process and operation planning, the NC code post-processor adjusts feedrates along the tool path to reduce machining time while maintaining the quality. The adjustment rule is selected based on the machining load estimated by virtual machining.

• 한국정밀공학회지
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• 제22권3호
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• pp.137-145
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• 2005

The present research deals with structural analysis and optimal design of the heating drum of a hot-rolling press for medium density fiberboard. Stress concentration in the journal of the heating drum is analyzed by the submodel technique of the finite element method. The fatigue life under operating conditions is analyzed and evaluated by the stress-life theory. Shape optimal design problems, to minimize the maximum stress occurring in the journal, are formulated and shape parameters of the corner fillets of the journal are defined as the design variables. The problems are solved by the numerical optimization method and optimal shapes are found. The optimal designs are shown to be reliable in terms of the maximum stress and the fatigue life.

• 한국정밀공학회지
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• 제15권5호
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• pp.50-58
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• 1998

A proper model of expert system for the very thin sheet metal press die design has been suggested. Using the suggested model, an expert system of the very thin sheet metal press die has been developed. This study contains that the results from the developed system for three kinds of specimens have the adaptability in the actual site. In addition, the possibility for expansion of this system has been discussed. The developed system, which is based on the knowledge base, has been included in a lot of expert's technology in the practice field. C-language under the HP-UNIX system and CIS customer language of the EXCESS CAD/CAM system have been used as the overall CAD environment. Results from this system will provide effective aids to the designer in this field.

• 한국정밀공학회지
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• 제20권3호
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• pp.105-111
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• 2003

This paper presents an approach to automate process planning of press dies for manufacturing of car bodies. Considering that the press-dies used at the same press operations regardless of the panels they produce or the car models of which they produce panels have similar shapes except for the forming part of the dies, general approaches to recognize manufacturing features from CAD models are not necessary. Therefore, a hybrid approach is proposed combining feature-based design and feature-extraction approaches. The proposed method recognizes features by parsing the parameters extracted from CAD models and finds proper operations by querying the database by the recognized features. An internet-based process planning system is developed to demonstrate the proposed approach and to suggest a new paradigm of process planning system that utilizes an internet access to the CAD system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.1016-1019
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• 2005

In the cutting of plate steel, the quality of the cut surfaces is strongly dependent on the cutting condition such as cutting speed, plate thickness, power, kerf width and gas pressure etc. The cutting tests of Steel Automobile Press Hot were carried out using $CO_2$ Laser cutting machine. The kerf width and surface roughness of a section are examined at various cutting conditions. This paper deals with cutting characteristics of Steel Automobile Press Hot(SAPH400) using $CO_2$ Laser Cutting Machine.

• 한국정밀공학회지
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• 제28권1호
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• pp.63-72
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• 2011

In recent years, hot-stamped components are more increasingly used in the automotive industry in order to reduce weight and to improve the strength of vehicles. In hot stamping process, blank is hot formed and press hardened in a tool. However, in hot stamping without cooling channel, temperature of the tool increases gradually in mass production thus cannot meet the critical cooling rate to obtain high strength over 1500MPa. Warpage occurs in the hot stamped component due to non-uniform stress state caused by unbalanced cooling. Therefore, tools should be uniformly as well as rapidly cooled down by the coolant which flows through cooling channel. In this paper, optimal design method of cooling channel to obtain uniform and high strength of the component is proposed. Optimized cooling channel is applied to the hot press V-bending process. As a result of measuring strength, hardness and microstructure of the hot formed parts, it is known that the design methodology of cooling channel is effective to the hot stamping process.

• 한국정밀공학회지
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• 제25권12호
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• pp.125-131
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• 2008

In the past, precision optical glass lenses were produced through multiple processes such as grinding and polishing, but mass production of aspheric lenses requiring high accuracy and having complex profile was rather difficult. In such a background, the high-precision optical GMP processes were developed with an eye to mass production of precision optical glass parts by molding press. Generally because the forming stage in a GMP process is operated at high temperature above $570^{\circ}C$, thermal stresses and deformations are generated in the aspheric glass lens mold that is used in GMP process. Thermal stresses and deformations have negative influences on the quality of a glass lens and mold, especially the height of the deformed glass lens will be different from the height of designed glass lens. To prevent the problems of a glass lens mold and the glass lens, it is very important that the thermal stresses and deformations of a glass lens mold at high forming temperature are considered at the glass molds design step. In this study as a fundamental study to develop the molds used in an aspheric glass lens fabrication, a heat transfer and a thermal stress analysis were carried out for the case of one cavity glass lens mold used in progressive GMP process. Finally using analysis results, it was predicted the height of thermally deformed guide ring and calculated the height of the guide ring to be modified, $64.5{\mu}m$. This result was referred to design the glass lens molds for GMP process in production field.

• 한국정밀공학회지
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• 제29권12호
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• pp.1267-1271
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• 2012

Demand for optical glass device used for lighting could increase rapidly because of LED lighting market growth. The optical glass devices that have been formed by hot press molding process the desired optical performance without being subjected to mechanical processing such as curve generation or grinding. EL-Max material has been used for many engineering applications because of their high wear resistance, high compressive strength, corrosion resistant and very good dimensional stability. EL-Max is very useful for a glass lens mold especially at high temperature and pressure. The performance and reliability of optical components are strongly influenced by the surface damage of EL-Max during grinding process. Therefore, the severe process condition optimization shall be necessary for the highly qualified EL-Max glass lens mold. To get the required qualified surface of EL-Max, the selection of type of the diamond wheel is also important. In this paper, we report best grinding conditions of ultra-precision grinding machining. The grinding machining results of the form accuracy and surface roughness have been analyzed by using Form Talysurf and NanoScan.

• 한국정밀공학회지
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• 제28권2호
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• pp.202-210
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• 2011

The fabrication method of aspheric lens is changed from machining to press molding so as to improve the productivity. In the case of the press molding method, the temperature control of the molding die is most important, because the temperature of each molding die determines the quality of lens. But any practical method for direct measuring of the lens temperature and the die internal temperature is yet unknown. Besides, in the case of the press molding system in which the heating and pressing and cooing of a die is done at separate work stations, the lens productivity of the system for small lens is yet too low. The paper shows an improved structure of convective sequential system, the lens productivity of which is three times as many as the conventional convective system. To know the die internal temperature, numerical results are given using ANSYS. A new convective sequential system is developed and tested. Finally, the Taguchi method is applied in order to optimize the setting conditions of individual work station of the system.

• 한국정밀공학회지
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• 제27권12호
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• pp.67-74
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• 2010

The fabrication method of aspheric lens is changed from machining to press molding so as to improve the productivity. In the case of the press molding method, the temperature control of the molding die is most impotent, because the temperature of each molding die determines the quality of lens. But any practical method for direct measuring of the lens temperature and the die internal temperature is yet unknown. Besides, in the case of the press molding system in which the heating and pressing and cooing of a die is done at one work station, the cycle time for the system is yet too long. The paper shows an improved structure of radiant sequential system in which the heating and pressing and cooing of dies is done at individual work station so as to cut down the cycle time. To know the die internal temperature, numerical results are given using ANSYS. An experimental radiant sequential system is developed and tested. Finally, the Taguchi method is applied in order to optimize the setting conditions of individual work station.