• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.32 no.6
• /
• pp.251-261
• /
• 2022

This paper describes the finite element analysis and die design change of spring retainer forging process to reduce the cold forging load and plastic forming stress concentration. Plastic deformation analysis was carried out in order to understand the forming process of workpieces and elastic stress analysis of the die set was performed in order to get basic data for the die fatigue life estimation. Cold forging die design was set up to each process with different four types analysis progressing, the upper and lower dies shapes with combination of fillets and chamfers shapes of cold forging dies. This study suggested optimal cold forging die geometry to reduce cold forging load. The design parameters of fillets and chamfers are selected geometry were selected to apply optimization with the DoE (design of experiment) and Taguchi method. DoE and Taguchi method was performed to optimize the workpiece preform shape for spring retainer forging process, it was possible to expect an increase in cold forging die life due to the 20 percentage forging load reduction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.365-368
• /
• 2000

We have studies on the Microstructures and densities as a function of forming pressures and the magnetic properties of the specimens with additive Bi$_2$O$_3$ that sintered at 95$0^{\circ}C$ for 4.5 hours for synthesizing optimal Ni-Cu-Zn ferrite. Green density rose generally as Forming pressure increased from 1.7 ton/cm$^2$to 2.5 ton/cm$^2$and Cold Isostatic Pressure(CIP) method was more effective than Die Pressure(DP) method to high green density. Forming pressure had no influence on apparent density but on the other hand Bi$_2$O$_3$contents were strongly dominant to appaernt density than forming pressure. Bi$_2$O$_3$liquid phases created during sintering process promoted sintering and grain growth so that apparent density, grain size and permeability increased compared to that of the specimens which were sintered with non-additive Bi$_2$O$_3$.

• Transactions of Materials Processing
• /
• v.16 no.6
• /
• pp.452-456
• /
• 2007

Cold forging technology of a gear product is being interested in the dimensional accuracy, high stiffness and reduction of stress concentration. Especially it is needed to avoid the damage due to extremely high local pressure. Therefore it is important to reduce the high pressure in die design of cold forging. In this study, single die insert type and splitted die insert type are considered to recognize the notch effects in the die of sprocket forming. The stress concentration has been released at the notch area by the cushion effect in the splitted die insert.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.2
• /
• pp.30-37
• /
• 2005

A drum clutch which is a main part for the automatic transmission of auto-mobiles has been manufactured by glob threading and machining. The tooth shape of the drum clutch manufactured by machining has lower dimensional accuracy than that by pressing and its machining needs the enormous cost at plant investment. Thus, this study was designed to develop cold forging process and to improve the productivity and dimensional accuracy. In this work, variables affecting dimensional accuracy were first determined, then cold forming process design according to each variables was performed by FE simulation. Optimal process was suggested on the basis of analytical results.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.10
• /
• pp.164-171
• /
• 1999

An optimum blank design technology is required for near-net of net-shape cold forming using sheets. Originally, the backward tracing scheme has been developed for preform design in bulk forming, and applied to several forming processes successfully. Its key concept is to trace backward from the final desirable configuration to an intermediate preform of initial blocker. A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracing simulation, has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping, the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup product without machining after forming. Another general application appears in the blank design of a cup stamping with protruding flanges, one of typical automobile components. The blank configurations derived by backward tracing simulation have been confirmed by a series of loading simulations. The approach or decision of an initial blank configuration presented in this study will be a milestone in fields of sheet forming process design.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1996.10a
• /
• pp.174-184
• /
• 1996

Two methods for cold extrusion processes to produce an axisymmetric steel gear blank are investigated for comparing each other. The "classical" forming method consisting of four operations is selected first to be simulated using the rigid-plastic finite element method and uses single-die presses. The other using a fully automated transfer headers can produce the final part without interannealing. The final products must be checked at the design criteria such as area reduction, the extrusion ratio and punch diameter to depth ratio, especially punch buckling by simulations. FEM analysis is performed mainly for strain distribution, both process sequences are proved to have proper charicteristics suitable for each production method in terms of maximum load. Those simulation results will provide good design criteria in the future work to advance the manufacturing process.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.12 no.6
• /
• pp.69-76
• /
• 2013

This paper presents the development of the FCF method for the manufacturing of final products using numbers related to the minimum amount of work. The utilized product is a drum clutch, which is part of the transmission of an automobile. A double acting press is secured first and a prediction of the forming load on the practical material is made through an experiment with a plasticine model. Also, a finite element simulation using product shape and properties is performed, as well as a press experiment. A double acting press is manufactured that is suitable for a double acting experiment with a conventional hydraulic press(200 tons). A peripheral device for the press is additionally designed for experimental purposes. And, the press has as its essential points the drive speed, stroke control, etc., all of which influence the forming and is modified. Especially, a laser system is used for velocity measurement of two punches. The forming load of a practical material is predicted in order to derive a forming load formula for cold conditions on the basis of approximate similarity theory. Finite element analysis of the relative velocity ratio(RVR), etc., for most suitable flow defect(unfilling, etc.) prevention is achieved as well. The results are verified through a press experiment.

• Design & Manufacturing
• /
• v.10 no.2
• /
• pp.44-49
• /
• 2016

The roll forming produces mass products using the continuous production process. Also we need the process that continuous long material or goods cutting into a desired length. Our study uses 3-D driving cutter and roll forming material as SPCC to investigate this. When we cut the material using the process of roll forming, the shear resistance is raised at the cutting punch's edge. The result is remained the trouble about burr and progressive deformation on the material. This study shows the method minimizing the above trouble. The material of punch was considering heat generated on the continuous production process. So we used the type of STD 61 for the material of punch and had the vacuum heat treatment for the surface hardness of HRC 53. The structure of the mold is designed with forming a double cam die at the upper punch and the both sides of central core. We conducted the experiment three times. In the result when had to make V-groove within the angle between 105 and 110 on the punch front end, we could get the minimum shear resistance on the punch front end. Also with the same condition we minimizes the material jams in the continuous production process.

• Transactions of Materials Processing
• /
• v.6 no.5
• /
• pp.446-455
• /
• 1997

A Combined extrusion operation consists of forward and backward extrusion forming and it is possible to make the process be simple by employing it. But the metal flow pattern induced by the operation is hard to analyze accurately because the flows are non-steady, which have at least two directions dependent upon each other. So engineers in the industrial factories had conducted the two extrusion operations separately. A new process was designed by the industrial expert for forming of an alu-minum preform using the combined extrusion operation. In this study, experiments and finite element analysis was carried out to determine the process parameters. Through the preliminary experiment, it was shown that warm forming condition was more desirable than cold or hot ones. And optimal shape of initial billet could be also determined. From the compatibility test, bonde-lube was chosen as the optimal lubricant and 20$0^{\circ}C$ as the material temperature by the inspection of micro-structure. The operation was simulated by the rigid-plastic finite element method to examine the metal flow. Disap-pearing of dead metal zone was observed as the punch fell down and desirable shape was obtained from the one operation. As a result of this study, 7 operations could be reduced and 225% of material saved.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1990.04a
• /
• pp.83-88
• /
• 1990

The study is concerned with the theoretical and experimental investigation of axisymmetric fluid pressure-drive hydronforming of sheet metal by forming over the die cavity. The rigid-plastic finite element method is employed to calculate the stress and strain distribution The effect of blank size and die radius is also studied in the finite element analysis. Experiments are carried out for hydroforming of cold rolled steel sheets under various process conditions. The computational results are compared with the experimental results for the forming pressure vs. pole displacement relations and strain distributions. Comparison has shown that theoretical predictions by the finite element method are in good agreement with the experimental observations. Thus, it is shown that the rigid-plastic finite element method is effectively used in the analysis of axisymmetric fluid pressure-driven hydroforming process.