• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.448-452
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• 2005

Punching/blanking/shearing is among the oldest and most frequently used sheet metal forming process. We have developed the shear device for burrless cutting using the micro wire. Since the burr minimization and fine shear plane, this paper is a study on the effect of the shear angle and clearance of the cutter-cutter. And, we confirm the tendency of the shear plane. It is impossible to completely remove the burr in the shearing process. In order to minimize the burr size and fine shear plane, we have accomplished the various experiment conditions such as the shear angle and clearance. Despite the quality of shear plane is not good enough yet, it is possible to make the burr minimization and fine shear plane by the optimization of process parameters.

• 한국기계가공학회지
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• 제5권3호
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• pp.51-57
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• 2006

Hydro-mechanical punching was developed for preventing burr formation. Circular hole punching and Finite element method(FEM) analysis were conducted to investigate shearing characteristics of this process in comparison with conventional and mechanical counter punching. In this process hydrostatic pressing with appropriate medium was utilized instead of counter punch, which resulted in the delay of the point that the fracture is initiated and clean shearing surface was obtained. FEM analysis was utilized to find out optimum processing parameters and shearing mechanism for burr-free hole punching.

• 한국생산제조학회지
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• 제9권5호
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• pp.80-86
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• 2000

The Tailor Welded Blanks(TWB) are using various materials (different thickness, strength and different materials) can be welded together prior to the forming process. Therefore, TWB applications have become little by little important in automobile industries, because it has more light weight and process reduction. A burnish area is very important for TWB using laser welding. In this paper, evaluated failure criterion, effect of clearance and distance of between pad and punch by computer simulation. We used element separation method for fracture. And applied a plastic strain to failure criterion. According to the analysis results, we obtain failure criterion, when plastic strain is 2.0. The burnish area and clearance were inverse proportional.

• 비파괴검사학회지
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• 제27권4호
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• pp.321-327
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• 2007

위상잠금 적외선 열화상기법은 넓은 면적을 동시에 검사할 수 있으며, 결함부와 건전부 사이의 위상 차로부터 결함의 유무를 판단할 수 있다. 지금까지 결함의 크기는 검사자의 주관적 판단으로 평가되어 왔으며, 재현성과 정확성이 부족하였다. 본 논문에서는 결함의 크기와 위치 평가에 있어 정확성과 재현성을 개선하기 위해서 전단위상기법을 제안하였다. 시험에서는 인공결함을 갖는 시험편으로 제안된 기법을 검증하였으며, 결함평가에 영향을 주는 인자를 추출하여 그 영향을 분석하였다.

• 소성∙가공
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• 제31권1호
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• pp.23-28
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• 2022

Although the hole expansion test is currently the most commonly used method to evaluate the stretch flangeability of HSS, it has been criticized due to its poor repeatability and reproducibility for test results. This paper focuses on the development of a new measurement method to investigate the stretch flangeability of HSS. Two materials (DP590, DP980) were investigated with a hole expansion test and a developed test method. Test results showed that the developed test method could be used as one stretch flangeability test to help identify relevant parameters of the shearing process to avoid edge cracking.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.679-682
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• 2001

An experiment is carried out to investigate the influences of shearing characteristic factors for the process design of lead frame blanking in copper alloy C194(t=0.205mm). 3 process parameters, e.g., clearance between die and punch, strip holding pressure, and bridge allowance are selected for this study. From the basis condition 6% clearance, 20N/$mm^2$, and 1.5t bridge allowance the seven times of experiment are done by varying the each factor. The square shape specimen is used to study the characteristics of shearing factors. The ratios of roll over, burnish, fracture zone are measured after blanking. The experimental analysis shows that the burnish ratio is decreased as the clearance increases. And the larger strip holding pressure is shown that the roll over and burnish ratio are both decreased. It is found that an optimal strip holding pressure is need for large burnish zone. Finally it is shown that the bridge allowance is less affected than clearance and strip holding pressure.

• Geomechanics and Engineering
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• 제34권2호
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• pp.197-208
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• 2023

Rate-dependent mechanical response of sand, subjected to loading of medium to high strain rate range, is of interest for several civilian and military applications. Such rate-dependent response can vary significantly based on the initial density state of the sand, applied confining pressure, considered strain rate range, drainage condition and sand morphology. A numerical study has been carried out employing a recently proposed visco-plastic constitutive model to explore the rate-dependent mechanical behaviour of Toyoura sand under drained triaxial loading condition. The model parameters have been calibrated using the experimental data on Toyoura sand available in published literature. Under strain rates higher than a reference strain rate, the simulation results are found to be in good agreement with the experimentally observed characteristic shearing behaviour of sand, which includes increased shear strength, pronounced post-peak softening and suppressed compression. The rate-dependent response, subjected to intermediate strain rate range, has further been assessed in terms of enhancement of peak shear strength and peak friction angle over varying initial density and confining pressure. The simulation results indicate that the rate-induced strength increase is highest for the dense state and such strength enhancements remain nearly independent of the applied confinement level.

• Nuclear Engineering and Technology
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• 제52권5호
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• pp.1066-1078
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• 2020

The present paper describes an analytic solution procedure for flexural vibration of a rotationally restrained hinged-hinged Timoshenko beam at the supports during an earthquake. Focusing on maximal magnitudes of internal loads such as bending moment and shearing force under wide variations of two parameters, kL/EI and kGAL²/EI, various beams under synchronous and asynchronous support motions are simulated. The simulations under asynchronous support motions show the following facts. The variations of the maximal magnitudes of internal loads of stocky beams due to the variation of kL/EI from zero to infinity show much wider variations than those of slender beams as kGAL²/EI decreases. The maximal magnitudes of internal loads of a beam tend to be governed by their static components as kL/EI increases and kGAL²/EI decreases. When the internal loads are governed by their static components, maximal magnitudes of internal loads of the stocky tend to increase monotonically as the value of kL/EI increases. However, the simulations under synchronous support motions show the static components of the internal loads vanish and the internal loads are governed by dynamic components irrespective of the two parameters.

• 비파괴검사학회지
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• 제26권2호
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• pp.122-129
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• 2006

본 논문에서는 레이저 응용 비파괴검사 기술인 Shearography를 이용하여 압력 배관 내부 결함의 검출에 있어서 미치는 전단량의 영향을 분석하였다. Shearography는 레이저 응용기법에 비하여 환경 외란에 둔감하며, 대상체 표면의 상대 변위를 검출함으로서 비파괴검사 분야에서 많은 활용이 기대된다. 현재까지 연구는 적용 가능성의 평가와 적용 대상의 확대에 중점을 두어 연구가 진행되어 왔으며, 결함의 정량평가를 위해서는 결함 검출에 있어서 영향을 주는 인자들에 대한 연구가 필요하다. 따라서 본 논문에서는 결함의 검출에 영향을 줄 수 있는 전단량의 변화에 따라 결함의 크기 측정과 길함의 위치 결정에 대한 영향을 예측하고, 압력용기 내부의 길이 방향 인공 결함에 대해 적용하여 검출 결과를 분석하였다.

• 소성∙가공
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• 제14권3호
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• pp.207-214
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• 2005

Blanking process is widely used fur producing various structural parts. However, fine blanking technology is frequently used as a single step blanking operation with clean cut surface of a sheared surface because the fractured surface of parts causes serious problems in the final product and therefore it must be removed by the post-processing in case of the conventional blanking. In the present investigation, a fine blanking process was designed within the framework of progressive die to produce a carrier plate assembled within the auto transmission. Finite element analysis of the shearing behavior at the respective stage of the progressive fine blanking was conducted to validate the designed die parameters. Finally the designed progressive fine blanking process was experimentally evaluated by using the machined die.