• 소성∙가공
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• 제15권4호
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• pp.304-310
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• 2006

Due to a recent growth of the area of MEMS and a trend moving toward smaller scale, a micro manufacturing that is usually related with lithography is now emerging. Differently from traditional manufacturing processes, the micro or miniature manufacturing usually requires expensive sophisticated equipments and its characteristics are of high cost and of low productivity. However, a miniature stamping, which makes small sized product with a thin metal usually in the range of meso-scale, can be realized in a low cost and in a high productivity with relatively inexpensive equipments. For a successful development of miniature stamping, lots of obstacles, including material properties related with formability, have to be overcome. Since the thin metal shows distinctive characteristics, e.g., size effect and statistically scattered material properties, the formability of miniature stamping is not good in general and the possible shape with the miniature stamping is limited relatively simple shapes. Since the optimal blank improves formability and the improved formability can make up for problems of material properties, the possibility of success can be increased. This study is carried out to show the possibility of miniature stamping and to verify the effect of optimal blank for the miniature stamping.

• 오토저널
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• 제15권2호
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• pp.121-129
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• 1993

Plane strain punch stretching test (PSST) was developed to evaluate stamping formability of sheet materials. In this test, the rectangular specimen of sheet material is uniformly stretched up to fracture by raising a specially designed punch to certainly assure plane strain stretching deformation along the longitudinal direction of the specimen. The stamping formability was evaluated by limit punch height(LPH) in plane strain punch stretching test compared to limit dome height(LDH) in hemispherical punch stretching test. LPH-value in PSST well ranks the stamping formability of various material and correlates with press performance. Moreover by using ultrasonic thickness gauge the plane strain intercept-limit plane strain(FLCo)-in forming limit curve can be accurately determined from thickness measurement around the fracture area. The FLCo derived from thickness measurement well correlates with the results from circle grid analysis for the deformed circle grid marked on the surface of the specimen.

• 대한기계학회논문집
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• 제17권5호
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• pp.1132-1137
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• 1993

본 연구에서는 특수하게 제작된 펀치형상을 갖는 평면변형장출실험에 의한 스탬핑성형성 평가기술(RIST-PSST)의 개요에 대하여 논하고 돔장출 실험결과와 비교하여 본 방법의 특징을 검토하였다.

• 한국정밀공학회지
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• 제26권11호
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• pp.108-115
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• 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
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• 제3권1호
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• pp.84-96
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• 1994

Simulation of 3 dimensional large irregularly shaped stamping process by a dynamic approach, based on an explicit time integration scheme, has been shown to be highly efficient and robust in comparison to traditional, implicit, quasi-static ones. The objective of the work is to evaluate the results from explicit code in application to deep drawing of rectangular cup and stamping of automotive front fender, in which deformation, force, thickness distribution are calculated. The method of predicting spring back and formability by and explicit code are suggested and applied to the processes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.25-28
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• 2004

A fracture was generated by change of clearance and deterioration of material properties on the sheet metal through temperature. This paper describes the results of a prediction about the temperature of the sheet metal during continuous stamping process, because the temperature increase of the sheet metal has a detrimental effect on formability. To analyze the temperature increase of the sheet metal during continuous stamping process, tensile and friction tests were performed from room temperature to 300$^{\circ}C$ at warm condition in this study. As temperature increase, tensile strength, elongation, strain hardening exponent and anisotropy coefficient for each specimens were decreased. On the other hand, friction coefficients were increased. From the FE-simulation results, temperature upward tendency was identified on dies and sheet metal. These observations are rationalized on the basis of the material properties, friction coefficient vs. temperature relationship for the sheet.

• 대한기계학회논문집
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• 제14권6호
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• pp.1474-1486
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• 1990

본 연구에서는 자동차용 표면처리 강판의 스탬핑 성형에 있어서 도금 종류별 도금층의 표면특성과 마찰, 윤활특성의 상관관계를 규명하고, 스탬핑 성형특성을 파악 하여 도금 종류별 최적 성형조건을 도출하고자 한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.15-18
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• 1997

The plane strain stretch test (PSST) developed by POSCO as an activity of customer service was applied to the establishment of the formability criteria and the prediction of failure during the stamping processes. The PSST was applied to the actual parts such as oil pan and shock mount and the criteria of PSST value for each forming parts were established. These value can provide the possibility of prediction of failure before the stamping process. These results show that the PSST can precisely predict the stamping formability of steel sheets.

• 소성∙가공
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• 제30권5호
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• pp.242-246
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• 2021

Aluminum alloy sheet is being applied to automobiles continuously for the purpose of reducing car body weight. However, due to low formability, there's a limit to application of products with a deep forming depth such as door inner parts. Therefore, the difficult-to-form parts are mainly segmented formed then joined together, which is also disadvantageous as it increases the cost of manufacturing. This study proposes a hybrid cold-hot stamping method for the 1-piece door inner part to reduce cost. To design the stamping process, numerical simulation method is established by using the temperature-dependent mechanical properties of AA6016. The formability according to the hybrid cold-hot stamping method is evaluated using numerical analysis. The suitability of the proposed stamping method is then verified through the stamping tryout.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.174-177
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• 2008

This paper replaces an conventional 300-austenitic stainless steel sheet to a 400-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 multi-stage stamping process. 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.