• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.231-234
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• 2001

Shearing, including blanking, trimming, piercing, etc, is one of the most frequently used processes in sheet metal manufacturing. In this paper, an individual set of tooling with an in-die sensor was designed and precisely fabricated to carry out the experiment for the shearing process investigation. Through various experiments, it has been examined the influence of process parameters such as clearance, edge material properties and pad configuration. Since the tension between the part and the scrap increases when the clearance increases, the clearance should be selected properly in order to reduce the burr height. Also removal of the lower pad makes the sheared surface worse and the shearing system unstable. The shearing force increases when the clearance decreases and the friction of the tooling material decreases. Dynamic reaction force is also important to obtain the fine sheared surfaces.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.523-526
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• 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

• 소성∙가공
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• 제32권2호
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• pp.61-66
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• 2023

The quality of the sheared surface affects the stretch flangeability of steel sheet. The quality of sheared surface is influenced by several process factors such as die clearance, shape of cutting edge, use of counter punch, and shear. In this paper, the influence of these shearing process factors on the stretch flangeability of the HSS (DP980) was analyzed through a shearing and a stretch flangeability test. When the die clearance was 10%, the effect of these shearing process factors on the stretch flangeability was the greatest, and the use of an acute angle blade was found to be more advantageous in the stretch flangeability than a right angle blade. It was found that the stretch flangeability was improved when active bending was applied during shearing.

• 한국조경학회지
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• 제27권5호
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• pp.80-93
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• 2000

This study measured the shearing resistance of the roots of the Pinus Koraiensis by the tensile strength gained through their individual tensile test for the Root Reinforcement Model. On the basis of the shearing resistance value calculated through such a process the factor of safety(Fs) was comparatively presented by using the simplified Janbu Method in PCSTABL5M, the slop-analyzing software which had been developed in Purdue University of the U.S.A according to the shape of a slope and the type of soil. The results to have measured a stress and the factor of safety(Fs) by experiment are as follows. 1) The mean root diameter of the Pinus Koraiensis used for this experiment was 2.483mm and the mean tensile stress was calculated as 422.846(kgf/$\textrm{cm}^2$). In the strain ratio of material and the elastic modulus was measured 7.8%, 9,291.92(kgf/$\textrm{cm}^2$). 2) The shearing strength including the resistance of soil and root is expressed as Rt=C+Cr+$\sigma$.tan . ΔCr(kg/$\textrm{cm}^2$) of the shearing resistance calculated by estimating the areal ratio of roots at 10 is 0.253(kgf/$\textrm{cm}^2$). 3) As the result of making an analysis of the natural slope stability by the soil parameter, the factor of safety(Fs) was calculated at 1.795 in CL, and the stability analysis of the root reinforcement slope, Fs was calculated at 1.952. However, since a precise analysis of the controlled factors of the slope analyses are demanded for more accurate dynamic analyses, the future demands a study on this.

• 반도체디스플레이기술학회지
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• 제10권3호
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• pp.61-65
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• 2011

The capabilities of finite elements codes allow now accurate simulations of blanking processes when appropriate materials modelling are used. Over the last decade, numerous numerical studies have focused on the influence of process parameters such as punch-die clearance, tools geometry and friction on blanking force and blank profile. In this study, three dimensional finite element analysis is carried out to design a lead frame blanking die using LS-Dyna3D package. After design of the blanking die, an experiment is also carried out to investigate the characteristics of blanking for nickel alloy Alloy42, a kind of IC lead frame material. In this paper, it has been researched the investigation to examine the influence of process parameters such as clearance and air cylinder pressure on the accuracy of sheared plane. Through the experiment results, it is shown that the quality of sheared plane is less affected by clearance and air cylinder pressure.

• Geomechanics and Engineering
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• 제8권1호
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• pp.33-52
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• 2015

Based on the Mohr-Coulomb failure criterion, a gradient-dependent plastic model that considers the strain-softening behavior is presented in this study. Both triaxial shear tests on conventional specimen and precut-specimen, which were obtained from an ancient landslide, are performed to plot the post-peak stress-strain entire-process curves. According to the test results of the soil strength, which reduces from peak to residual strength, the Mohr-Coulomb criterion that considers strain-softening under gradient plastic theory is deduced, where strength reduction depends on the hardening parameter and the Laplacian thereof. The validity of the model is evaluated by the simulation of the results of triaxial shear test, and the computed and measured curves are consistent and independent of the adopted mesh. Finally, a progressive failure of the ancient landslide, which was triggered by slide of the toe, is simulated using this model, and the effects of the strain-softening process on the landslide stability are discussed.

• Applied Microscopy
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• 제25권3호
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• pp.99-107
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• 1995

The morphological changes of primary solid particles as a function of process time on hypereutectic Al-15.5wt%Si alloy during semi-solid state processing with a shear rate of $200s^{-1}$ are studied. In this alloy, it was observed that primary Si crystals are fragmented at the early stage of stirring and morphologies of primary Si crystals change from faceted to spherical during isothermal shearing for 60 minutes. To understand the role of Al dissolved in the primary Si crystal by shear stress at high temperature, lattice parameters of the primary Si crystals are determined as a variation of high order Laue zone(HOLZ) line positions measured from convergent beam electron diffraction(CBED) pattern. The lattice parameter of the primary Si crystal in the rheocast Al-15.5wt%Si alloy shows tensile strain of about 5 times greater than that of the gravity casting. Increase of the lattice parameter by rheocasting is due to the increased amount of Al dissolved in the primary Si crystal accelerated by shear stress at high temperature. The amounts of solute Al in the primary Si crystal are measured quantitatively by EPMA method to confirm the CBED analysis.

• 한국정밀공학회지
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• 제20권9호
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• pp.55-62
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• 2003

This paper investigates the micro-cutting of cemented carbides using PCD (polycrystalline diamond) and PCBN (polycrystalline cubic boron nitride) cutting tools are performed with SEM direct observation method. The purpose of this study is to make clear the cutting mechanism of cemented carbides and the fracture of WC particles at the plastic deformation zone in orthogonal micro-cutting. And also to achieve systematic understanding, the effect of machining parameter on chip formation and machined surface was studied, including cutting speed, depth of cut and various tool rake angle. Summary of the results are shown below. (1) Three type of chip formation process have been proposed by the results of the direct observation in orthogonal micro-cutting of cemented carbide materials. (2) From the whole observation of chip formation, primary WC particles are crushed and/or fine grained in the shearing deformation zone. A part of them are observed to collide directly with a cutting edge of tool by following the micro-cutting. (3) Surface finish, surface morphology and surface integrity is good to obtain by cutting with PCD cutting tool compared with PCBN. (4) The machined surface has the best quality near the low cutting speed of 10${\mu}m$/sec with a cutting depth of 10 ${\mu}m$ using 0$^\circ$ rake angle and 3$^\circ$ flank angle in this condition, but it was found that excessively low speed, for example the extent of 1 ${\mu}m$/sec, is not good enough to select for various reason.

• 한국식품과학회지
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• 제31권4호
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• pp.1011-1016
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• 1999

식물의 세포벽 모형에 근거하여 고온고압의 조건하에서 기계적인 전단웅력을 식물 세포벽에 가할 경우 수용성 다당류를 효과적으로 분리할 수 있다는 가설에 근거하여 사과박으로부터 펙틴을 추출하기 위해 압출처리법을 도입하였다. L/D비가 20: 1인 동방향완전맞물림형 이축압출기를 이용하여 압출기의 축회전수, 원료의 공급률 및 원료의 수분함량을 공정변수로 하고 압출기의 비기계에너지를 시스템의 매개변수로 하여 압출처리에 의한 수용성 다당류의 수율, 평균 분자량 및 galacturonic acid 함량을 분석한 후, 각각의 모형을 개발하였다. 펙틴의 수율과 품질을 동시에 비교해 볼때, 비기계에너지를 증가시키면 펙틴의 수율이 향상되는 것으로 나타났으나, 수율을 향상시키는 압출조건은 품질의 저하를 초래하는 것으로 나타났다. 비기계에너지가 191 kWh/ton인 고강도의 추출조건에서 수율은 20.1%로 나타나 기존의 산처리법에 의한 14.4% 수율보다 월등히 향상된 수율을 얻을 수 있었다. 한편, 비기계에너지가 96 kWh/ton인 저강도의 추출조건에서는 분자량이 240,000인 펙틴을 얻을 수 있어 산처리시 분자량 181,000의 펙틴보다 훨씬 양질의 펙틴을 얻을 수 있었다. 따라서, 목표로 하는 품질의 펙틴을 생산할 수 있으면서 최고의 수율을 얻을 수 있는 압출조건을 설정해야 하며, 이를 위해서 본 연구에서 제시한 펙틴의 수율 및 품질 모형을 이용할 수 있다.