• Transactions of Materials Processing
• /
• v.8 no.6
• /
• pp.591-603
• /
• 1999

A computer-aided process planning system for rotationally symmetric deep drawing products has been developed. The application for non-axisymmetric components, however, has been reported yet. Therefore, this study investigates process sequence design in deep drawing process and constructs a computer-aided process planning system for non-axisymmetric motor frame products with elliptical shape. The system developed consists of three modules. The first one os a 3-dimensional modeling module to calculate surface area for non-axisymmetric products. The second one is a blank design module that creates an oval-shaped blank with the identical surface area. The third one is a process planning module based on production rules that play the best important roles in an expert system for manufacturing. The production rules are generated and upgraded by interviewing with field engineers. Especially, drawing coefficient, punch and die radii are considered as main design parameters. The constructed system for elliptical deep drawing products would be very useful to reduce lead time and improve accuracy for production.

• Transactions of Materials Processing
• /
• v.27 no.6
• /
• pp.356-362
• /
• 2018

A liner is a crucial component that directly affects the penetration performance of the shaped charge warhead. If the material of the liner has fine grain size and high strength, then the penetration performance can be further improved. There have been attempts to use a preform obtained by a severe plastic deformation (SPD) process. In this study, the process of minimizing the strain deviation to maintain the characteristics of material obtained by the severe plastic deformation process was investigated. The FE analysis of liner forging process was performed using the design of experiments (DOE), to optimize various shape parameters of the forming process such as shape of preform and forging die. As a result, the combination of design variables with the minimum effective strain deviation in the liner forging process were obtained.

• Transactions of Materials Processing
• /
• v.9 no.3
• /
• pp.293-303
• /
• 2000

Recent developments of Fe technology make it possible to apply CAD/CAE/CAM techniques successfully to the stamping die design among the automotive parts industries. Those successful applications are greatly attributable to the development of commercial S/W. Up to now most commercial S/W for the analysis of sheet metal forming is based on the dynamic explicit algorithm. The main characteristics of dynamic explicit algorithm is that there is no convergence problem if the time increment is taken less than the stability limit. The stability of the analysis is guaranteed in the commercial code, since the adequate time increment is computed from the so called "Courant Condition". However excess computing time is often pointed out in the dynamic explicit analysis according to the characteristics of process parameters taken. In the study, various parameters that may affect the stability and the method how to improve computational efficiency of analysis have been investigated.estigated.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.523-526
• /
• 1997

Sheanng is one of the most important operating processes in the field of sheet metal manufacturing. Compared with casting, forging and machining, shearing is very economical to obtain the desired shape. In recent years there has been increasing the use of shearing process in the manufacturing of small and light electronic components. In this paper, it has been researched the experimental investigation to examine the mfl uence of shearing process parameters such as clearance and lower holder configuration. Through the experiment results, the more narrow clearance gives the smaller burr height and the removal of lower holder makes the worse sheared surface. And FE simulation of shearing process using DEFORM-2D were camed out and the results compared w~th experimental studies

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.03b
• /
• pp.30.2-34
• /
• 1999

The hydroforming technology has gained in importance over the last few years, because of its potential for substantial weight avings costs reduction and quality improvement such as collision property, shape fixability and rigidity of white body. However, in comparison with the traditional sheet forming process, the hydroforming is much younger and the main development efforts were made in the last 15 years. The new technology, high pressure tublar hydroforming in particular, involves many process parameters to be optimized. This paper covers a brief overview of the hydroforming simulator as well as design of die and tools. The effects of typical parameters such as internal pressure and axial compression stroke are presented. Moreover, the conditions of forming failure occurrences such as fracture and wrinkle are examinated.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.2
• /
• pp.221-227
• /
• 2016

The main shaft is one of the key components connecting the rotor hub and gear box of a wind power generator. Typically, main shafts are manufactured by open die forging method. However, the main shaft for large MW class wind generators is designed to be hollow in order to reduce the weight. Additionally, the main shafts are manufactured by a casting process. This study aims to develop a manufacturing process for hollow main shafts by the open die forging method. The design of a forging process for a solid main shaft and hollow shaft was prepared by an open die forging process design scheme. Finite element analyses were performed to obtain the flow stress by a hot compression test at different temperature and strain rates. The control parameters of each forging process, such as temperature and effective strain, were obtained and compared to predict the suitability of the hollow main shaft forging process. Finally, high productivity reflecting material utilization ratio, internal quality, shape, and dimension was verified by the prototypes manufactured by the proposed forging process for hollow main shafts.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.9
• /
• pp.1364-1372
• /
• 1997

In this paper, the forging of helical gears has been investigated. Punch is tooth-shaped as is the die insert. The punch compresses a cylindrical billet placed in a die insert. As a consequence the material of billet flows into the tooth region. The forging has been analysed by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, an involute curve has been introduced to represent tooth profile of the gear. Numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, helix angle and friction factor on the forging of helical gears. Some forging experimentswere carried out with aluminum alloy to show the validity of the analysis. Good agreement was found between the predicted values of the forging load and obtained from the experimental results.

• Transactions of Materials Processing
• /
• v.3 no.1
• /
• pp.110-119
• /
• 1994

In this paper, a new forming process of large-size forgings of converged nozzle-shape is developed by the experimental study using the incremental forging method and combined forming method. The development of the forming process is focused on the manufacturing of large-size forgings by the press with medium load capacity. Various related processes are proposed and modelling experiments using plasticine are carried out. Thus, the incremental forging method for expanding is recommanded from the study of formability and forming load, etc. The selected process is then subjected to modelling experiments of lead and the design parameters such as preform for final process, die-width of the upper die and reduction amount of each stroke are determined. In order to verify the effectiveness of the selected process, 1/7 scale prototype experiment of the real material is carried out. Forgings of converged nozzle shape can be produced by the developed process within the limit loads and with the simple tools.

• Transactions of Materials Processing
• /
• v.13 no.4
• /
• pp.342-349
• /
• 2004

The form-joining process (or clinching) uses a set of die and punch to impose the plastic deformation-induced geometric constraint on a sheet metal pair. The joining strength from the process ranges 50-70 percent of that of the resistance spot welding. In this paper, a new form-joining process with the aid of an adhesive is proposed in which an epoxy adhesive is applied to a sheet metal pair, and before it cures the pair is clinched to cause the geometric constraint in the form of a protrusion. In order to reduce the forming load and the height of protrusions, a new die and punch set with a very small clearance is devised to reduce the depth of drawing and the forming load. Taguchi method is employed to find the optimal values of design parameters. To implement each case of the orthogonal array, the finite element method is used. The experiments show that in the tensile-shear test, the bonding strength of the new form-joining process with an epoxy adhesive is approximately the same as that of the resistance spot welding; and in comparison with the other two form-joining processes with an epoxy adhesive, the height of protrusions is reduced by more than 65 percent and the forming load by 50 percent.

• International Journal of Precision Engineering and Manufacturing
• /
• v.7 no.2
• /
• pp.8-11
• /
• 2006

Gas-assisted injection molding (GAIM) process reduces the required injection pressure during mold filling stage as well as the shrinkage and warpage of the part and cycle time. Despite of these advantages, this process needs new parameters and makes the application more difficult because gas and melt interact during the injection molding process. Important GAIM factors involved in this process are gas penetration design, locations of gas injection points, shot size, delay time to inject gas as well as common injection molding parameters. In this study, the experiments are conducted to investigate effects of GAIM process variables on the gas penetration for PP (Polypropylene) and ABS (Acrylonitrile Butadiene Styrene) moldings by changing the gas injection point. Taguchi method is used for the design of the experiments. When the gas is injected at a cavity's center, the most effective factor is the shot size. When the gas is injected at a cavity's end, the most effective factor is the melt temperature. The injection speed is also an effective factor in GAIM process.