• 한국정밀공학회지
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• 제17권9호
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• pp.62-69
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• 2000

Uneven clearances in the left and right sides of a press die cause deformation of the punch in precision shearing process. This deformation results from the compression stress and bending moment from shearing force in vertical direction and from the side force in horizontal direction acting to the punch, In this study the behavior of punch deformation is investigated in order to clarify the deformation state of the punch by using strain gauge deformation to shearing force side force bending moment radius of curvature and shear plane of the punch. Also we presented the calculation method of deformation size for the punch.

• 소성∙가공
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• 제24권2호
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• pp.77-82
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• 2015

By investigating the practical use of trim punch configurations for shearing of vehicle panels, the current study first reviews the shearing angle as part of the shearing die design. Based on this review, four different types of trim punch shapes (i.e., horizontal, slope, convex, and concave type) and shearing angles(i.e., 0.76°, 1.53°, 2.29°, 3.05°, 3.81°) were investigated. In order to conduct shearing experiments, four types of trim punch dies were made. The four trim punch dies were tested under various conditions. The experiments used the four trim punch shapes and the five shearing angles. The shearing force varied by shape and decreased from horizontal, slope, convex, to concave for the same shearing angle. The magnitude of shearing force showed differences between the convex and the concave shapes due to the influence of constrained shearing versus free shearing. The test results showed that compared to the horizontal trim punch shearing force, the decrease of the slope, convex, and concave shearing forces were 22.6% to 60.4%. Based on the results, a pad pressure of over 30% is suggested when designing a shearing die.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.185-186
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• 2006

Numerical Simulation of powder die pressing is conducted on Case Study geometry. Influence of fill density distribution and punch kinematics upon green density distribution and punch loading are studied and discussed. Deviations in punch kinematics due to punch deflection influence the most the results in term of density and force.

• 터널과지하공간
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• 제22권2호
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• pp.144-156
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• 2012

본 논문에서는 TBM의 굴진성능 평가를 위한 실내시험 중 하나인 압입시험의 시험과 결과 분석방법에 대하여 연구하였다. 압입시험은 암석의 굴진저항 및 취성도를 나타내는 여러 지수들을 산정하고 이를 통해 TBM의 굴진율 및 추력을 직접적으로 추정할 수 있는 유용한 실험으로 알려져 있으나 국내에서는 아직 관련된 연구가 수행된 바 없으며 규격화된 시험방법이나 결과해석방법 역시 제시되지 못하고 있는 실정이다. 본 연구에서는 압입시험의 시험 장비를 재구성하여 제작하였고 다양한 조건에 대하여 시험을 수행하여 합리적인 시험방법과 시편의 크기에 대하여 고찰하였다. 또한 국내의 6개 암종에 대하여 압입시험을 수행하고 하중지수의 산정방법에 대하여 연구하였으며 하중지수로써 PLI와 MLI를 제안하였다. 본 연구에서 제안된 지수인 PLI와 MLI는 동일한 암종을 대상으로 수행된 선형절삭시험결과와 밀접한 상관관계를 보였으며 하중지수를 통해 개략적으로 예측된 단일 디스크커터의 수직하중은 실험값과 10% 오차를 보였다. 압입시험은 TBM의 성능예측을 위한 유용한 실험법임을 확인할 수 있었으며 본 연구는 이를 위한 기초연구로서 그 활용도가 높을 것으로 기대된다.

• 소성∙가공
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• 제8권5호
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• pp.449-453
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• 1999

Sheet metal forming process is a non-linearity problem which is affected by various process variables, such as geometric shape of punch and die, frictional characteristic, etc.. Therefore, the knowledge of the influence of the process variables is needed in the design of sheet metal working processes. In this paper, cylindrical cup drawing tests for blank holding force, punch speed and lubrication between sheet material and tool were carried out to investigate the influence upon sheet formability. Experimental results were discussed about the defects on the deformation behaviors during the forming process.

• 동력기계공학회지
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• 제15권6호
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• pp.53-58
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• 2011

To optimization of mlod for fineblanking forming of sector gear of recliner, it was analyzed the effect of clearance, V-ring height, V-ring position, blank holding force and counter punch force. In case of 0.003 mm of clearancs, the finest shear plane was obtained, but optimization between die and punch clearance was 0.005 mm. The height of V-ring was 0.7 mm. In case of increasing of hold force, the size of shear plane got better and the decrement of thickness became smaller. Both the size of shear plane and the decrement of thickness increased according to increasing of counter punch force.

• 대한기계학회논문집A
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• 제24권6호
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• pp.1565-1574
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• 2000

Surface edge crack subjected to contact stresses is analysed. A punch with corner radii is considered to press the semi-infinite plane. Partial slip problem is solved when a shear force is applied to the punch. Dislocation density function method is used to solve the present mixed mode crack problem. The crack length of positive K1 is examined, which is affected by the ratio of the flat portion to the total width of the punch. Surface traction during one cycle of the shear force is evaluated to simulate the fretting condition. The compliance change of the contact surface is also investigated during the shear cycle. It is found that the crack grows during only a part of the cycle, which may be termed as effective period of crack growing. A design method for restraining the fretting failure is discussed, from which recommendable geometry of the punch is suggested.

• Design & Manufacturing
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• 제16권4호
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• pp.46-51
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• 2022

The piercing process of creating holes in sheet metals for mechanical fastening generates high shear force. Real-time monitoring technology could predict tool damage and product defects due to this severe condition, but there are few applications for piercing high-strength aluminum. In this study, we analyzed the load signal to predict the punch's wear level during the process with a piezoelectric sensor installed piercing tool. Experiments were conducted on Al6061 T6 with a thickness of 3.0 mm using piercing punches whose edge angle was controlled by reflecting the wear level. The piercing load increases proportionally with the level of tool wear. For example, the maximum piercing load of the wear-shaped punch with the tip angle controlled at 6 degrees increased by 14% compared to the normal-shaped punch under the typical clearance of 6.7% of the aluminum piercing tool. In addition, the tool wear level increased compression during the down-stroke, which is caused by lateral force due to the decrease in the diameter of pierced holes. Our study showed the predictability of the wear level of punches through the recognition of changes in characteristic elements of the load signal during the piercing process.

• 소성∙가공
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• 제30권3호
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• pp.149-156
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• 2021

Fine blanking is a high-precision process combining principles of metal stamping and cold forming. Unlike conventional metal stamping, fine blanking uses a special triple action such as V-ring force, counter force, shearing force. This study performed the effect of pocket-shaped compression molding on the mold life of the fine blanking using the 7.4mm thick SM45C material. In order to determine the lifespan of the punch and die in the fine blanking molds, a trial mold was manufactured and various punch materials were selected to perform the mold life test. A study on the life of a fine blanking mold by applying a thick plate material was experimentally performed through a mold test.

• Structural Engineering and Mechanics
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• 제83권1호
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• pp.67-77
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• 2022

In this study, frictionless continuous and discontinuous contact problems of a magneto-electro-elastic layer in the presence of the body force were discussed. The layer was indented by a rigid cylindrical insulating punch and supported by a rigid substrate without bond. Applying the Fourier integral transform technique, the general expressions of the problem were derived in the presence of body force. Thanks to the boundary conditions, the singular integral equations were obtained for both the continuous and the discontinuous contact cases. Gauss-Chebyshev integration formulas were used to transform the singular integral equations into a set of nonlinear equations. Contact width under the punch, initial separation distance, critical load, separation regions and contact stress under the punch and between the layer, and substrate were given as a result.