• 한국재료학회지
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• 제13권6호
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• pp.374-380
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• 2003

The effect of forging parameters, including different forging stock, strain rate and strain, on the mechanical properties of hot-forged Al 6061-T6 was investigated. The forging was conducted using either hydraulic press, crank press or hammer press, respectively, at a forging temperature of $400^{\circ}C$. When using an extruded bar as a forging stock, the tensile strength was lower for the specimens prepared by hammer forging than those by crank press forging. It was found that the coarsening of recrystallized grain was responsible for the decrease in tensile strength with hammer forging. Systematic studies on the effects of strain and strain rate on the tensile properties of hot-forged Al 6061-T6 products using extruded bar as a forging stock further suggested that the coarsening of recrystallized grains and$ Mg_2$Si precipitates complexed the observed trends in the tensile behavior. In case of hot forging with continuous cast bar as a forging stock, on the other hand, the mechanical properties of the specimen were largely improved with hammer press compared to those with crank press, which appeared to be due to the homogenization of microstructure.

• 대한기계학회논문집
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• 제14권5호
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• pp.1166-1180
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• 1990

본 연구에서는 열간 반경단조를 해석하는데 있어서 재료의 변형 해석은 강-점 소성해석법으로 해석하고 온도분포도 유한 요소법으로 해석한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.117-125
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• 1998

A hot forging product in general is produced through buster, blocker and finisher processes. Usually the processes including dies are designed by experienced forging engineers. However, due to the lack of such engineers, it is necessary to develop expert systems with which engineers of little experience can perform the design task. In the present study, an expert system is developed for axisyrnmetric hot steel forgings. It is a rule based system written in Fortran and AutoLISP, operating on a personal computer. In this paper, structures of the system are summarized and capabilities of the system are examined through several examples.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.188-191
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• 2005

Lower arm for automobile has been made in steel traditionally. Nowadays steel is being substituted fur aluminum to reduce weight of automobile. Widely applied production method of aluminum component has been casting processes or cast/forging processes. But casting or cast/forging processes have limits of application to parts which is required high strength durability like automotive component. In this research, hot forging process has been adopted to produce aluminum lower arm to ensure required mechanical properties. To reduce production cost, 2 pieces with 1 blow process was developed. Optimization and verification of hot forging process for aluminum lower arm was performed by computer aided engineering using finite volume methods.

• 소성∙가공
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• 제3권3호
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• pp.271-281
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• 1994

Titanium-6242 $({\alpha}+{\beta})$ alloy has been used for aircraft engine components such as disks and blades, because it has an excellent strength/weight ratio at high temperatures. When this material is forged to manufacture disks, process parameters should be carefully designed to control strain and temperature distributions within the process windows by which desirable mechanical properties can be produced. In the present investigation, it was intended to design the process parameters for a conventional hot forging of this material by using a rigid-thermoviscoplastic finite element analysis technique. It was assumed that the process was performed by a screw press which is capable of maintaining a constant ram speed during loading. From the analysis results, it was found out that the initial temperature of the workpiece and the die shape were important parameters to control the forging process. In result, these parameters were properly designed for hot forging of a disk with specific dimensions.

• 한국생산제조학회지
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• 제24권5호
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• pp.489-495
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• 2015

Forging is a manufacturing process involving the shaping of metal using localized compressive forces and the process of deforming metal into a predetermined shape using certain tools and press according to the temperature. Forging provides stronger metal parts than that possible by casting or machining. Conventional clutch jaw parts have been developed through cold forging and precision machining; however, fabrication of integral clutch jaw parts for farm machinery has not been reported yet. These parts were developed by applying a complex forging technology combining cold and hot forging. The integrated forming technology proposed in this study will be useful for reducing the lead-time for manufacturing, improving the accuracy of products, and eliminating the welding process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.666-669
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• 2002

Process design of hot forging, asymmetric to symmetric rail, which is used for the turnout of railway express has been investigated. Owing to the big difference in shape between the initial billet and the final forged product, it is impossible to hot forge the rail in a single step. Therefore, multi step forging as well as die design for each step are necessary for the production. The deformation behavior during hot forging has been analyzed by the numerical simulation through commercial FEA software, DEFORM$^{TM}$-2D. Modification of the design and repeated simulation have been carried out on the basis of the simulation result. For comparison with the simulation results, flow analysis experiment using plasticize has been also carried out. The results of the flow analysis experiment showed good agreement with those of the simulation. Therefore, the developed process design could be applied to the actual production.

• 소성∙가공
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• 제1권1호
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• pp.20-32
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• 1992

This paper describes some research of Computer-Aided Process Planning and Die Design of Hot Forging for axisymmetric parts produced by the press. An approach to the system is based on knowledge based system. The system has been written in AutoLisp with personal computer. Knowledges for process planning & die design are extracted from the plasticity theories, handbooks, relevent references and empirical know-how of field experts in hot forging companies. The developed system is composed of five main modules, such as input module, process planning module, die design module, flow simulation module and output module which are used independently or in all. The final output is generated in graphic from. The developed system which aids designer provides powerful capabilities for process planning and die design of hot forging. This system also provides approximate flow pattern.

• 소성∙가공
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• 제12권6호
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• pp.536-541
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• 2003

In this paper, the rigid-viscoplastic finite element method is employed together with an iteratively force-balancing method to analyze a piercing and trimming process with a spring-attached die in hot former forging. An actual piercing and trimming process with a spring-attached die is investigated in detail and a generalized analysis model is proposed. A multi-stage hot former forging process is simulated under various spring constants. The analyzed results are discussed in order to investigate the effects of spring constants on the metal flow lines and the formed shapes. Then an optimal piercing and trimming process in hot former forging is devised.

• 제어로봇시스템학회논문지
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• 제21권5호
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• pp.427-433
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• 2015

Hot forging industry workers are prone to encounter several health risks due to lack of automation and poor working environment conditions. These workers particularly suffer from muscle fatigue owing to the constant handling of heavy products during the forging process. Thus we developed an assistant robot for workers who carry out hot forging tasks. The purpose of a robot is to compensate gravity-loads for heavy products. To verify the functionality of a robot, we performed a muscle fatigue analysis using Electromyography (EMG) signals. Four muscles of the upper extremity were chosen to measure muscle activity. And experiment conditions were setup to imitate the hot forging process. Post experimental analysis of the captured muscle activity revealed a reduction in the median frequency of the EMG signals, which means clear fatigue reduction due to a robot's assistance. The developed assist robot with compact and economical components can be efficiently utilized at forging work sites to create better working conditions for operators.