• 소성∙가공
• /
• 제25권6호
• /
• pp.396-401
• /
• 2016

Recently, Multi-strength hot stamping process has been widely used to achieve lightweight and crashworthiness in automotive industry. In concept of multi-strength hot stamping process, process design of tailor rolled blank(TRB) in partial heating is difficult because of thickness and temperature variation of blank. In this study, springback prediction of TRB in partial heating process was performed considering its thickness and temperature variation. In partial heating process, TRB was heated up to $900^{\circ}C$ for thicker side and below $Ac_3$ transformation temperature for thinner side, respectively. Johnson-Mehl-Avrami-Kolmogorov(JMAK) equation was applied to calculate austenite fraction according to heating temperature. Calculated austenite fraction was applied to FE-simulation for the prediction of springback. Experiment for partial heating process of TRB was also performed to verify prediction accuracy of FE-simulation coupled with JMAK equation.

• 한국정밀공학회지
• /
• 제28권3호
• /
• pp.349-356
• /
• 2011

This paper replaces a conventional austenitic stainless steel sheet to a ferritic stainless steel for the cost reduction of a pulsator cover of a washing machine. However, ferritic stainless steel has poor formability in comparison with austenitic one. The low formability of ferritic steel results in problems during stamping such as fracture, wrinkling, shape inaccuracy and so on. Design modification of the stamping tool is carried out with the aid of the finite element analysis for multistage stamping process of the pulsator cover. The simulation results show that fracture occurs on top of the product while wrinkles are generated by the excess metal near the wing part. Modification of the initial stamping die is performed to improve metal flow and to eliminate problems during the stamping process. Simulation with the modified design fully demonstrates that safe forming is possible without inferiorities.

• 한국기계가공학회지
• /
• 제3권3호
• /
• pp.58-63
• /
• 2004

In the present work a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of multi-stage stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation Multi-Stage stamping is analyzed by using dynamic-explicit finite element method. Further, the simulated results for the panel stamping processes are shown and discussed. Its application is being increased especially in the stamping industrial area for the cost reduction, weight saving, and improvement of strength.

• 소성∙가공
• /
• 제15권3호
• /
• pp.247-254
• /
• 2006

Rather than traditional manufacturing processes, miniature manufacturing processes usually require sophisticated equipments and characteristics of the processes of high cost and of low productivity. Contrarily, miniature stamping process can be realized in a low cost high productivity with relatively inexpensive equipments. In the meso scale, mechanical properties, especially work hardening characteristics, are discovered to be statically scattered and size dependent by intensive experimental and numerical investigations, which make the stamping process hard to apply to the miniature manufacturing. In this study, dual purpose experimental device that can be used for both miniature scale tensile test and miniature scale stamping by simple change of attachment has been developed. For the tensile test, the elongation has been measured with a combined use of a CCD camera and a linear encoder in order to account for the possibility of slippage between specimen and the grip and to ensure the accuracy of the measurement, while load has been measured with a load cell. To satisfy the required material properties for stamping, optimal annealing condition has been found by examining the microstructure of annealed specimen.

• 소성∙가공
• /
• 제26권2호
• /
• pp.87-94
• /
• 2017

Center pillar, which is installed in the center of flank of car body, supports roof and door and ensures the safety of driver by reducing the damage of car body caused by impact. Recently, high-strength steel is widely used to manufacture the center pillar due to high stiffness and fuel efficiency. In this study, material properties of the high-strength steel, whose tensile strength is more than 780MPa, were obtained to produce the center pillar. Stamping was performed by considering the design parameters (blank holder force, press stroke, blank size and pad pressure) used in the actual filed. The drawbeads were included in the stamping process to reduce the amounts of wrinkling and spring back. Using the commercial software, Autoform R5.2 and Minitab, effects of design parameters of the stamping process upon spring back were analyzed and applied to the design process. The restriking process meets the target of under 0.5mm in the amount of spring back.

• Journal of Welding and Joining
• /
• 제33권6호
• /
• pp.36-41
• /
• 2015

In the automotive industry, TWB hot stamping process is broadly adapted to reduce weight of the car and improve fuel efficiency. However, the process faces a problem of weakened strength of the welded zone after hot stamping process, due to the fact that Al-Si elements of the coating layer penetrating the welded zone. In this study, filler wires with high percentages of carbon and manganese is adapted during laser welding process to secure the strength of the fusion zone. In addition, wire feeding speed and laser welding speed are optimized by sample test.

• 한국정밀공학회지
• /
• 제26권11호
• /
• pp.108-115
• /
• 2009

In metal forming technologies, the stamping process is one of the significant manufacturing processes to produce sheet metal components. It is important to design stamping process which can produce sound products without defect such as fracture and wrinkle. The objective of this study is to propose the feasible formability diagram which denotes the safe region without fracture and wrinkle for effective design of stamping process. To determine the feasible formability diagram, FE-analyses were firstly performed for the combinations of process parameters and then the characteristic values for fracture and wrinkle were estimated from the results of FE-analyses based on forming limit diagram. The characteristic values were extended through training of the artificial neural network. The feasible formability diagram was finally determined for various combinations of process parameters. The stamping process of turret suspension to support suspension module was taken as an example to verify the effectiveness of feasible formability diagram. The results of FE-analyses for process conditions within fracture and wrinkle as well as safe regions were in good agreement with experimental ones.

• 소성∙가공
• /
• 제32권2호
• /
• pp.81-86
• /
• 2023

The hot stamping process is widely used for high strength of vehicle parts, with heating 900 ℃ or higher in a furnace and in-die quenching to achieve strength above 1.5 GPa of the quenchable boron alloyed steel 22MnB5. First of all, the hot stamping process consisted of heating, forming, quenching and trimming. In the trimming process case, the laser method has been conventionally adopted. For laser trimming process, it has the problems pertaining to low productivity and high cost while the hot stamping process, accordingly the trimming process need to investigate the research for alternative method. In order to overcome these issues, many research groups have studied the mechanical trim solution on the hot stamped parts at high temperature. In this study, the mechanical piercing was performed during the hot stamping process at the high temperature for overcome the disadvantages of laser cutting. Also, the process parameters such as piercing time after die closing, clearances of between die and punch were controlled for obtaining the reasonable shear characteristics.

• 한국정밀공학회지
• /
• 제22권12호
• /
• pp.156-162
• /
• 2005

In this paper, we study the mechanism of lead deformation by numerically simulating the stamping process by means of a commercial finite element code. It is very important to analyze effects that the lead shape makes on the lead deformation, because the lead shape is often modified in order to minimize the deformation or to increase the buckling critical load of the punch. Therefore the stamping process, first, numerically simulated by considering as a quasi-static problem. Second, the effect on the lead deformation due to the lead shape variation, a linear lead geometry and a bent lead, was numerically analyzed and discussed. Finally, the punching order was optimized fur multi-lead generating stamping process. The results show that the bent lead is little bit more shifted than the linear lead after the punching process. But the bent lead is vertically less deformed than the linear lead. The punching order to successively generate the lead is good to keep the lead space uniform. The results will be very effectively applied for the design of the blanking or punching dies in industry.

• Journal of the Korean Data and Information Science Society
• /
• 제17권4호
• /
• pp.1299-1307
• /
• 2006

This study investigates solving production problems in an automotive stamping plant using Finite Element (FE) analysis. The fundamentals of stamping, metal plasticity and FE analysis are developed. In this paper, we provide the basis for a simulation of the stamping of a production part, the automotive rear floorpan. On-plant factorial Design of Experiments (DoE) were simulated using the floorpan model. The accuracy of the simulations was undetermined because of variability in the DoE results. Predictions of flange shape, wrinkling and thickness show qualitative agreement with manufactured parts and indicate that simulating an industrial part is feasible.