• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.434-437
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• 2007

Cold forging technology of a gear product is being interested in the dimensional accuracy, high stiffness and reduction of stress concentration. Especially it is needed to avoid the damage due to extremely high local pressure. Therefore it is important to ensure high pressure in die design. In this study, single die insert type and splitted die insert type are considered to recognize the notch effects in the die of sprocket forming. The stress concentration has been released at the notch area by the cushion effect in the splitted die insert.

• 소성∙가공
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• 제3권4호
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• pp.454-467
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• 1994

The drawbead restraining forces for the various radius of drawbead and die corner are analyzed by the belt theory, and they are compared with the experimental results. During this procedure, the drawing angles are also varied from $0^{\circ}$ to $60^{\circ}$, and the near part of the drawed die corner are divided into fur steps for the theoretical analysis. The stress distributions through the sheet thickness for these steps are also suggested theoretically. The wide range of experimental data of the drawing forces and strain distributions for the various dimension and blank holding forces are presented. It is concluded that the theoretical assumption for the restraining force analysis is very useful from the comparison with the experimental results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.242-245
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• 2007

In the present investigation, the multi-stage warm drawing process was applied to the magnesium alloy AZ31 sheet to examine the feasibility of multi-stage forming process as a high formability product making process. For that purpose, a multi-stage drawing die system with heating module was developed, and the AZ31 sheets of different sizes were consecutively drawn by the multi-stage drawing die. The obtained drawn cups of AZ31 showed that the multi-stage drawing provided the better formability than the single stage drawing in terms of drawing depth without cup defects such as wrinkles or fractures. The sheet formability improvement by using the multi-stage drawing die system against the single stage was also analyzed in terms of the finite element analysis of material state variables evolution.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2096-2103
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• 2002

Cold ironing, as a post-forging operation of warm forged gears, needs a clear understanding of form errors due to die-elasticity and springback of component. In order to simplify the analysis of cold ironing, a single tooth instead of a whole gear component was investigated. The influence of initial surface roughness, die design, and die/workpiece interference has been examined experimentally and numerically. As a result the changes in geometrical profile, dimensions, and surface finish in a single tooth were observed. This study demonstrates that predicted dimensions can be achieved and surface finish also can be greatly improved.

• 한국초전도ㆍ저온공학회논문지
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• 제19권3호
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• pp.27-32
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• 2017

The effects of artificial holes on the trapped magnetic fields and magnetic levitation forces of very large single-grain $Y_{1.5}Ba_2Cu_3O_{7-y}$ (Y1.5) bulk superconductors were studied. Artificial holes were made for Y1.5 powder compacts by die pressing using cylindrical dies with a diameter of 30 mm or 40 m, or rectangular dies with a side length of 50 mm. The single grain Y1.5 bulk superconductors (25 mm, 33 mm in diameter and 42 mm in side length) with artificial holes were fabricated using a top-seeded melt growth (TSMG) process for the die-pressed Y1.5 powder compacts. The magnetic levitation forces at 77 K of the 25 mm single grain Y1.5 samples with one (diameters of 4.2 mm) or six artificial holes (diameters of 2.5 mm) were 10-17% higher than that of the Y1.5 sample without artificial holes. The trapped magnetic fields at 77 K of the Y1.5 samples with artificial holes were also 9.6-18% higher than that of the Y1.5 sample without artificial holes. The 33 mm and 42 mm single grain Y1.5 samples with artificial holes (2.5 mm and 4.2 mm in diameter) also showed trapped magnetic fields 10-13% higher than that of the Y1.5 samples without artificial holes in spite of the reduced superconducting volume fraction due to the presence of artificial holes. The property enhancement in the large single grain Y1.5 bulk superconductors appears to be attributed to the formation of the pore-free regions near the artificial holes and the homogeneous oxygen distribution in the large Y123 grains.

• 한국정밀공학회지
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• 제18권10호
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• pp.76-83
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• 2001

This paper is concerned with the analysis of the forming characteristics of radial-backward extrusion. The single action pressing is analyzed by using the rigid-plastic FEM. The design factors such as die corner radius, gap height, and friction factor are involved in the simulation. The analysis is focused on the influences of the design factors on the maximum punch farce and metal flow into can and flange region. As a result of analysis, the gap height among the design factors is known to have a major effect on the metal flow of radial-backward extrusion for single action pressing compared with other design factors. As is expected, forming load and volume of flange increase as gap height and die corner radius increase, respectively.

• 한국산학기술학회논문지
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• 제11권12호
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• pp.4691-4696
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• 2010

본 논문에서는 HEV UV단자를 자동화 모듈인 씨마트론 다이 디자인을 활용하여 스트립 레이아웃설계를 3D로 하였다. 제품의 스탬핑을 원활하게 하기 위하여 스트립 레이아웃을 33.5도 경사지게 수정하여 광폭 1열 1개 뽑기의 내측캐리어를 단 배열로 블랭크 레이아웃을 최적화하였다. 1개의 금형에서 두개의 단자를 공용으로 양산하기 위해 29개 공정으로 3D 스트립 레이아웃설계 및 금형설계를 완성하였다.

• 소성∙가공
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• 제11권3호
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• pp.223-230
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• 2002

Matched die forming technology has been used widely as a sheet metal forming method for a long time. This conventional method, however, needs a high cost and long delivery time to prepare a set of matched dies or, in many cases, several sets of dies. For more than ten years, some alternative methods using single die or non-matched dies have been developed and applied practically in various fields of industry. Elasto-forming, fluid forming, hydro-forming, and blow forming are some examples of these new methods. Recently, a dieless sheet forming technology using a reconfigurable matrix of punch elements has been developed, and started to be used in some industries such as aircraft and railroads. A new concept of dieless forming technology has also been proposed to overcome the drawback of the conventional dieless forming technology.

• 오토저널
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• 제12권6호
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• pp.48-59
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• 1990

A finite element program was developed using line elements for simulating the stretch/draw forming operation of an arbitrarily-shaped plane-strain section. An implicit, incremental, updated Lagrangian formulation is employed, introducing a minimum plastic work path assumption for each time step. Geometric and material nonlinearities are also considered within each time step. The finite element equation is based on the mesh-normal, which compatibly describes arbitrary tool surfaces and FEM meshes without depending on the explicit spatial derivatives of tool surfaces. The membrane approximation is adopted under the plane stress assumption. The sheet material is assumed to obey a rigid-viscoplastic constitutive law. The developed program was tested in the die-tryout of typical automotive inner panels. In order to determine a single friction coefficient and boundary length, FEM results and measurements of thinning for a stretched section of final die were compared. After finding analysis parameters, the sheet forming operations of original and final die designs were simulated. Excellent agreement between measured and computed thickness strains was obtained and the developed program was able to identify die designs which were rejected during die tryout.

• 한국정밀공학회지
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• 제18권1호
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• pp.117-122
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• 2001

Many kinds of channels are used in industrial equipment and production machinery. Although mechanical saw has been used to cut many sorts of channels, there is cost rise problem because of low productivity. Shearing of channel has a special place because it helps to cut expected shape and size easily. A channel cutting die set which can be mounted and used on a hydraulic press is developed to improve the productivity of channel cutting process. Mode for the channel cutting is divided into single cut and double cut method. This study use double cut method, and the developed channel cutting die set is composed of upper and lower die set. Shearing time can be reduced from 40 minutes to 20 seconds using the developed channel cutting die set. The productivity of channel cutting process can be increased with shearing time reduction as well as cost reduction.