• 소성∙가공
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• 제26권3호
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• pp.162-167
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• 2017

The tensile surface residual stress in the multi-pass drawn wire deteriorates the mechanical properties of the wire. Therefore, the evaluation of the residual stress is very important. Especially, the axial residual stress on the wire surface is the highest. Therefore, the objective of this study was to propose an axial surface residual stress prediction model of the multi-pass drawn steel wire. In order to achieve this objective, an elastoplastic finite element (FE) analysis was carried out to investigate the effect of semi-die angle and reduction ratio of the axial surface residual stress. By using the results of the FE analysis, a surface residual stress prediction model was proposed. In order to verify the effectiveness of the prediction model, the predicted residual stress was compared to that of a wire drawing experiment.

• 한국결정성장학회지
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• 제32권6호
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• pp.251-261
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• 2022

본 연구에서는 냉간단조공정에서 성형하중과 금형내 응력집중 감소를 위해 자동차 엔진 밸브 스프링 리테이너 제품의 형상최적화를 위한 금형형상 최적설계를 수행하였다. 기존 생산에 사용되는 각 성형공정별 냉간단조 금형에 대한 유한요소해석 시뮬레이션을 통해 절단공정을 포함해 총 6공정으로 구성되어 있는 냉간단조공정 별 단조 프리폼의 성형 시에 발생하는 성형하중과 성형유동 특성을 분석하였으며, 이를 통해 금형 내 응력집중이 발생하는 주요 설계인자를 확인하였다. 상형금형과 하형금형부의 챔퍼(chamfer) 및 에지필렛(edge fillet) 형상을 대상으로 4인자 3수준 설계인자 및 변수 수준을 설정하고, 성형해석 시뮬레이션과 다구찌법을 활용하여 설계인자별 영향도를 분석하여 최적의 최적설계인자를 결정하였다. 본 연구를 통해 얻어진 최적설계변수를 적용하여 엔진밸브 스프링 리테이너의 최적설계 시뮬레이션 결과, 각 프리폼 성형공정별로 최대 36 %, 전체 공정 평균 20 %의 성형하중 감소 효과를 얻을 수 있었다. 엔진의 고효율, 고출력, 고성능화 목표가 지속적으로 높아짐에 따라 고강도 소재의 활용이 많아지게 되어 이에 대응할 수 있는 성형공정 및 금형설계의 최적화가 필요하며, 향후 연구 결과를 활용하여 현업에 적용하여 제품단조성형성 개선 및 금형수명관리를 위한 기술자료로 활용하고자 한다.

• Design & Manufacturing
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• 제11권2호
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• pp.25-28
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• 2017

Semiconductor equipment manufacturers desire to enhance efficiency of Sub Fab to increase semiconductor productivity. For this reason, Sub Fab equipment manufacturers are developing Integrated System that combined modules with multiple facilities. Integrated System is required to apply Mount Leveler of Wedge Type in compliance with weight increase compared with existing single equipment and product shape change. This thesis analyzes main design variables of components of Wedge Mount Leveler and carries out structure analysis using ANSYS, finite element analysis program Analysis shows that main design variables of components of Wedge Mount Leveler has self-locking condition by friction force of Wedge and adjusting bolt. Each friction force hinges upon Wedge angle and Friction Coefficient of contact surface and upon the thread angle and Friction Coefficient of contact surface. Also, as a result of carrying out structure analysis of Wedge Mount Leveler, deflection and stress appears in different depending on the height of the level.

• 소성∙가공
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• 제12권2호
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• pp.116-122
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• 2003

In the Prestressed die design for cold working, many constraining conditions should be considered to insure the die safety and to improve the dimension accountancy products. Among the constraining conditions, yielding conditions, diameter ratios and interferences between rings are very important. . In this paper, therefore, flexible tolerance method was used in order to search the optimum values of design variables. The maximum inner pressure is used as objective function in this numerical analysis. In the design Process, it was also involved the safety factor to the yield strength of each ring by considering the allowable tensile or compressive hoop stress in each ring. The proposed technique has been applied to the die design of backward extrusion process, and it's analytical results have been compared with that of the conventional design method.

• 소성∙가공
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• 제24권2호
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• pp.89-94
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• 2015

Medical catheter tubes are disposable devices that are inserted into the body cavities such as the pleura, trachea, esophagus, stomach, urinary bladder, ureter, or blood vessels for surgical procedures. Each hole of the inner tube is called a lumen, which is used as a passage for drug injections, waste discharge, polypus removal, blood transport, or injection of a camera or sensor. The catheter tube is manufactured by extrusion. The flow in the inner extrusion die affects the thickness and diameter of the tube. In the current study computer simulation of flow in an extrusion die for catheter tubing was performed. Velocity, pressure, shear rate, and shear stress were investigated and the die design was examined.

• 소성∙가공
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• 제22권4호
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• pp.183-188
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• 2013

Scroll compressors are widely used in air conditioning systems and in automobiles due to their low pressure loss, minimal vibrations, and light-weight. Open-die forging with back pressure is used to forge the rotating scroll, and it requires special care since the forging die can be severely damaged at the fixed end of the spiral cavity similar to a fracture of a cantilever beam. To overcome the inevitable weakness of the forging die due to such damage, an innovative design is necessary. In this study, structural analysis using the finite element method was conducted to determine the reason for the fracture of the forging die. A novel design to avoid stress concentrations and vertical deflection, causing serious damage to the die, is suggested.

• 반도체디스플레이기술학회지
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• 제20권2호
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• pp.43-50
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• 2021

The properties of materials which are widely used in industry fields like automobile, shipbuilding, casting, and electronics are strongly needed to have higher surface hardness, lower surface roughness, and higher compressive residual stress. As mentioned above, for the purpose of satisfying three factors, a variety of researches with respect to surface improvement have been actively studied and applied to every industry. SKD61 which is mostly used for die casting process of cold chamber method must meet a countless number of problems which are thermal, mechanical and chemical from highly specific working environment at high temperature over 600℃. Above all, in case of plunger sleeves used for die casting process, thermal fatigue has a bad effect on the surface of an inlet where molten metal is repeatedly injected. On account of it, plunger sleeves cause manufacturers to deteriorate quality of products. Therefore, in this paper, to improve the surface of an inlet of plunger sleeve, multilayer PVD coating using Ti, Cr and Mo is suggested. Furthermore, The surface characteristics such as surface roughness(Rsa, Rsq), surface hardness(HRB, HRC) and residual stress using XRD(X-ray diffractometer) of coated samples and specimens are studied and discussed.

• 소성∙가공
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• 제8권5호
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• pp.498-506
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• 1999

The metal forming processes of aluminum alloy wheel forging at elevated temperature are analyzed by the finite element method. A coupled thermo-mechanical model for analysis of plastic deformation and geat transfer is adapted in the finite element formulation. In order to consider the strain-rate effects on material properties and the flow stress dependence on temperatures, rigid-viscoplasticity is introduced in this formation. In this paper, several process conditions were applied to the dimulation such as die speed, rib thickness, and depth of die cavity. Simulation results are compared, and discussed with each case. Metal flow, die pressure distributions, temperature distributions, velocity fields and forging loads are summarized as basic data for process design and selection of a proper press equipment.

• Design & Manufacturing
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• 제6권1호
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• pp.73-78
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• 2012

The aim of this dissertation is inferring factors controlling the complex strain behavior of the material and the characteristics of the Fine-Blanking in the most narrow area at the shear zone where we are performing the Fine-Blanking. And also this is for inspecting and presenting their uses and the possibilities to make the results data based in order to utilize easily. Therefore, to analyze of shere zone's strain behaviour, the Fine-Blanking process need to be modelled defining the quadratic-nodded and axi-symmetrical elements as the problems of large deformation axi-symmetry and the non-linear contact. For the method of inputting strain-stress values of the material, the piece-wise linear technics were used, the Implicit-Finite Element method also used making balance of forces on each step by the long intervals, calculates and converges many times was done. The materials used for the analysis was the Steel SNCM220 5.5mm respectively. As the result of FEM analysis, we know that shear stress value in the beginning of punch penetration is distributed widely and done high both in the center of the late-thickness and on the both sides centering around shear strain zone as the punch penetration is increasing. Also.

• 한국주조공학회지
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• 제13권1호
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• pp.81-93
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• 1993

It is well-known that the analysis of elasto-plastic thermal stress and deformation are substantially important in optimal design of metal casting mould. The unsteady state thermal stress and deformation generated during the solidification process of ingot and mould have been analyzed by two dimensional thermal elasto-plastic theories. Distributions of temperature, stress and relative displacement of the mould are calculated by the finite element method and compared with experimental results. In the elasto-plastic thermal stress analysis, compressive stress occurred at the inside wall of the mould whereas tensile stress occurred at outside wall. A coincidence between the analytical and experimental results is found to be fairly good, showing that the proposed analytical method is reliable.