• 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.

• 한국정밀공학회지
• /
• 제22권9호
• /
• pp.41-48
• /
• 2005

In this study, to improve the formability of the rear floor in series stamping process, the method for predicting the temperature of tools and steel sheet is proposed using FE analysis. To do this, tensile tests and straight pulling friction tests of three steel sheets are carried out at temperatures up to $300^{\circ}C$, and the effect of temperature on the tensile properties and the characteristics of friction are examined. The steel sheets have a higher n-value in the temperature range of about $50^{\circ}C$, and it is related to the maximum uniform elongation. Also, the blue shortness occurs in the temperature range of about $150^{\circ}C$. When the temperature is higher than $200^{\circ}C$, the friction coefficient increase with increasing temperature. From the FE-simulation, the effects of the punch temperature considering heat expansion in the number of stamping are examined and discussed. The technique developed in this study fur estimating tool temperature can be used to develop more feasible ways to improve continuous productivity in series stamping process.

• 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.

• 소성∙가공
• /
• 제9권6호
• /
• pp.653-662
• /
• 2000

Wrinkling is one of the major defects in sheet metal products together with tearing, springback and other geometric and surface defects. The initiation and growth of wrinkles are influenced by many factors such as stress ratios, mechanical properties of the sheet material, geometry of the workpiece, contact condition, etc. It is difficult to analyze the wrinkling initiation and growth considering all the factors because the effects of the factors are very complex and the wrinkling behavior may show a wide scatter of data even for small deviations of factors. The finite element analyses of the wrinkling initiation and growth in the sheet metal forming process provide the detailed information about the wrinkling behavior of sheet metal. The direct analyses of the wrinkling initiation and growth, however, bring about a little difficulty in complex industrial problems because it needs large memory size and long computation time. In the present study, therefore, a global-local analysis technique is introduced for the computational efficiency. Through the analysis of wrinkling in the door inner stamping process, the efficiency of the global-local analysis technique is investigated.

• 대한기계학회논문집
• /
• 제16권10호
• /
• pp.1853-1860
• /
• 1992

본 연구에서는 평면변형을 가정할 수 있는 부품을 대상으로 하여 성형에너지 최소화 기법을 사용하여 계산속도가 빠르고, 설계된 금형의 CAD 데이터로부터 직접 변 형해석이 가능하며 금형 설계자들이 용이하게 사용할 수 있는 2차원적인 해석을 연구 하였다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1996년도 자동차부품 제작기술의 진보
• /
• pp.87-95
• /
• 1996

The stamping process consists of two stages : First, the blank is held by the blank holder and then it is further formed into the die cavity by punch stroke. In actual stamping process, the accurate prediction of binder wrap is an indispensable step in sheet metal forming analysis because the initial plastic buckling induced by improper die design is directly related with fatal defect at the final stage. In the present work, an approach including the gravity effect of blank material and proper consideration of contact and friction is proposed. Computations are carried out for some actual auto-body parts using 3D FEM code to investigate the validity of the proposed methodology. Comparisons with experimental results show that the suggested scheme can be effectively applied to the precise prediction of binder wrap for arbitrarily curved die faces in which gravity and contact effect must be taken into account.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1994년도 박판성형기술의 진보
• /
• pp.119-128
• /
• 1994

Until recently, Stamping tool manufacturing depend on skilled designers and technicians, because it has many parameters. So, Try-out time not controlled. We now apply CAE, preliminary experiment, material database and automated stain measurement in stamping tool manufacturing for concurrent engineering that decreases product development circle time, saves cost, improves product reliability. Automated strain analysis and measurement environment gives very accurately informations to technicians of stamping tool manufacturing. They analysed the part in problem and appled to results in Try-out step.

• 한국정밀공학회지
• /
• 제21권10호
• /
• pp.115-126
• /
• 2004

In the present work a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Analyzed auto-body panel stomping process correction of forming using software called Dynaform using dynamic extensive method. Further, the simulated results for the auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.

• 한국기계가공학회지
• /
• 제4권1호
• /
• pp.30-36
• /
• 2005

The static implicit finite element method is applied effectively to analyze total tray panel stamping processes, which include the forming stage. Complicated and abnormal large size tray panel was analyzed by using commercial program called AutoForm. Analysis results examining possibility and validity of the AutoForm software and the factor study are presented. Further, the simulated results for the total tray panel stamping processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1998년도 제2회 박판성형심포지엄 논문집 박판성형기술의 현재와 미래
• /
• pp.33-40
• /
• 1998

In recent domestic automotive industry, applications of computer simulation to the manufacturing of stamping dies for inner and outer body panels which greatly affect durability and aesthetic quality of automobiles, have been increased. Enhancement of die quality, and reduction of total die manufacturing time and consequently manufacturing cost are the visible outcome. However, to successfully apply the result of simulation by a commercial package to the die manufacturing, development of an optimal die manufacturing process is required upon the completion of analysis of forte and shortcomings of available sheet metal forming softwares in the market. Based on the results of numerical analysis of front door outer panel forming, this paper evaluates the applicability of simulation results to the real die making for automotive body panels. Also, it attempts to select an optimal die manufacturing process including design, machining and tryout. Lastly, it discusses the expected effects by adopting the selected process in a real stamping die manufacturing facility.