• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.9
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• pp.93-99
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• 2020

Recently, as the weight reduction of vehicles has been actively progressed, parts developed using aluminum 60XX series from existing steel materials are increasing. In this paper, the bushing used for the front frame rail, which is one of the parts for fixing engines and other parts in automobiles, was changed to an aluminum material of the Al60XX series, and it was intended to be produced by applying of cold forging method. The bushing is a part that secures the engine frame, and in order to produce it by cold forging, the molding limit is predicted through process design, and a multi-stage process is designed through finite element analysis. In addition, in order to verify the feasibility of the designed forging process, the limits of the multi-step process were verified based on the Cockcroft Latham theory, and the crack and overlap of the actual forging work were predicted and improved.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.82-90
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• 2020

Due to the complicated shape of the spider, the production method was changed from cold to warm forging. Finite element analysis was performed to predict the forging load and shape using the enclosed hydraulic die set. As the forging load increases due to the spider die volume, die stress analyses were performed to optimize the die design in order to reduce the die stress in various conditions. Large deformation while producing the complicated forging parts induces high forging load, which is one of the main parameters of the forging surface defects. The forging process was analyzed to find out the root cause of the surface defects generated during the spider production for various parameters, thereby revealing that the radius of die in the defect zone influenced the air trap depth, being the root cause of the surface defect. It was verified that die life was increased and the surface defect was eliminated by changing the die design during the mass production test.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.33-41
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• 2010

This study was aimed at the design of the dies for the unified pipe joint of the intermediate shaft using the computer simulation to shorten the period of production, on the basis of the process planning which was designed by the field experts. In the computer simulation, 'Deform-3d' and 'eesy-DieOpt' have been used, which are the commercial process analysis and die design program. Through the process analysis, we could know the propriety of the forming process, the inner pressure of the die and the suitable fitting pressure between the insert and the sleeve which was not showing any positive tangential stresses in the insert. Through the simulation of die design, we could know the number of the stress ring, the diameter ratios, the stresses of the die, the shrink fitting tolerance and temperature in the condition of the already determined maximum outer die diameter of the multi-stage former. The validity of the die design using the computer simulation was analyzed by the experiments and the results were satisfactory. As the results of this study, the new and easy die design system for multi-forging has been developed.

• Transactions of Materials Processing
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• v.17 no.3
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• pp.155-160
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• 2008

We analyzed a sequence of multi-stage automatic cold forging processes composed of four axisymmetric processes followed by a non-axisymmetric process using rigid-plastic finite element based forging simulators. The forging sequence selected for an example involves a piercing process and a heading process accompanying folding or overlapping, which all make it difficult to simulate the processes. To reduce computational time and to enhance the solution reliability, only the non-symmetric process was analyzed by the three-dimensional approach after the axisymmetric processes were analyzed by the two-dimensional approach. It has been emphsized that this capability is very helpful in simulating the multi-stage automatic forging processes which are next to axisymmetric or involve several axisymmetric processes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.195-200
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• 2007

We analyzed a sequence of multi-stage automatic cold forging processes composed of four axisymmetric processes followed by a non-axisymmetric process using rigid-plastic finite element based forging simulators. The forging sequence selected for an example involves a piercing process and a heading process accompanying folding or overlapping, which all make it difficult to simulate the processes. To reduce computational time and to enhance the solution reliability, only the non-symmetric process was analyzed by the three-dimensional approach after the axisymmetric processes were analyzed by the two-dimensional approach. It has been emphsized that this capability is very helpful in simulating the multi-stage automatic forging processes which are next to axisymmetric.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.166-173
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• 1999

Al forged parts are many cases with rib-web section which is difficult to manufacture precisely. Therefore, process conditions must be optimized for precision forging of Al alloys. In this study, various process parameters such as die design, lubricant, ram speed, forging temperature have been investigated using the experiment, upper bound theory and F.E.M. simulation to develop the precision forging technology for rib-web shape component. When lubricant is applied to both material and die, shear friction factor is 0.1 which shows best effect of lubricant. It is specific corner radius of die that minimized forging load regarding process conditions, especially according to the ratio of the width of rib and web. In conclusion, optimum corner radius is 2~3mm when the width of rib and web is 3mm and 20mm respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.50-52
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• 2007

Large size forged parts usually were made by hot open die forging because of the die cost, high applied load and small manufacturing quantities. Cast ingots were used in open die forging and the ingots almost included the cavities in its inside. Therefore, one of the aims for forging processes is to close and remove the cavities. However, its criteria were well not defined since the studies have many difficulties to investigate the cavity behaviors because of its large size. In this study, the cavity closure behavior was investigated by experimental and FE analysis. The FEM analysis is performed to investigate the overlap defect of cast ingots during free forging stage. The measured flow stress data were used to simulate the forging process of cast ingot using the practical material properties. Also the analysis of cavity closure is performed by using the $DEFORM^{TM}$-3D. The calculated results of cavity closure behavior are compared with the measured results before and after forging, which are scanned by the X-ray scanner. From this result, the criteria for deformation amounts effect on the cavity closure can be investigated by the comparison between practical experiment and numerical analysis.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.75-77
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• 2007

Mg alloys have the highest specific strength which can be used industrial application. Since formability of Mg alloys is very limited, optimization of forming process is always needed for successful engineering application. In the present study. three different Mg alloys were used for hot forging processes and several process variables such as temperature and forging speed were investigated to improve forgeability of Mg alloys. To understand the effect of process variables in details, 2D-finite element analysis and forging experiment was performed. In the results, forging speed seems to be more important than forging temperature in hot forging of Mg alloys.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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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.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.71-74
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• 2008

In order to resolve the problems which appear after the clean large ingot production process, the impurities which are involved in the steel smelting process should be removed by developing cleaner materials. Through the rationalization of cogging process that is the first forging process of large ingot the quality is to be improved. For the sake of the optimization of an open die forging process and the improvement of the subject matter frequency ratio, a hazard precise die forging process must be developed and a Near Net Shape Forming accomplished. As a result, energy can be reduced by minimizing an after control process. In order to produce large axes and other forming parts, processing techniques are to be developed. In this context, this paper is a study about a reduction ratio, dies width ratio and rotary angles, the amount of overlap, and intends to analysis cogging processes, utilizing Deform-3D cogging module