유한요소 해석 및 적외선 이미지를 활용한 금형 가열 조립체의 접촉 열저항에 관한 연구

서보민,박창용 대한기계학회 2022 大韓機械學會論文集B Vol.46 No.8

Contact thermal resistance affects mold heating characteristics at a progressive glass molding press heating assembly. In this study, a mold heating assembly was set as a simple test facility, and the temperature changing characteristics were experimentally measured. A finite element method model was built for the assembly, and simulation was performed to estimate contact thermal resistance by matching the measured temperature change trend. The simulation confirmed that an accurate value of contact thermal resistant should be given to the model to fit calculated results to the measured temperature. Additionally, the contact thermal resistance was calculated from an experimental infrared image, and the results showed 3.75% difference from the estimated value by the model. Thus, the contact thermal resistance calculation method with the infrared image could be a useful to determine contact thermal resistance. 순차적 금형 가압 유리성형 공정을 위한 금형 가열장치는 다수의 부품으로 구성되어 접촉면에서 열저항이 금형가열에 영향을 준다. 본 연구에서는 금형 가열부를 실험장치로 구성하여 장치의 가열 특성을 파악하였다. 실험장치에 대한 유한요소 해석모델을 구축하고 계산된 온도를 측정 결과와 비교하여 접촉 열저항을 계산하였다. 해석모델의 다양한 입력값이 온도 예측에 미치는 영향을 파악하여 실험과 일치하는 해석을 얻기 위해서는 정확한 접촉 열저항 값이 입력되어야 함을 파악하였다. 또한, 실험을 통해 얻은 적외선 이미지를 이용하여 접촉 열저항을 구하였으며, 해석과 적외선 이미지를 이용한 접촉 열저항이 3.75%의 차이를 보여 적외선 이미지를 활용한 접촉 열저항 측정법이 유용함을 보였다.

열-유동 상호작용을 고려한 유도가열 적용 미세 사출성형의 통합적 수치해석

엄혜주(Hye Ju Eom),박근(Keun Park) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.5

최근 박육사출성형이나 마이크로 사출성형에서의 성형성을 높이기 위해 급속 금형가열 기술이 사용되고 있다. 고주파 유도가열은 전자기 유도현상을 이용하여 금형 표면만을 효율적으로 가열할 수 있어 급속 금형가열 기술로서 활용되고 있다. 본 연구에서는 고주파 유도가열 적용 사출성형 과정의 수치적 모사를 위해 전자기장 해석, 열전달 해석, 사출성형 유동해석을 연계한 통합적 전산모사 기법에 관한 연구를 수행하였다. 본 연구에서 제안된 통합적 전산모사 기법을 유도가열 적용 박육 사출성형의 해석에 적용하여 실험결과와 비교하였고, 특히 금형온도 경계조건의 부여방식에 따른 해석의 신뢰성에 대한 고찰이 이루어졌다. In recent years, several rapid-mold-heating techniques that can be used for the injection molding of thin-walled parts or micro/nano structures have been developed. High-frequency induction heating, which involves heating by electromagnetic induction, is an efficient method for the rapid heating of mold surfaces. The present study proposes an integrated numerical model of the high-frequency induction heating process and the resulting injection molding process. To take into account the effects of thermal boundary conditions in induction heating, we carry out a fully integrated numerical analysis that combines electromagnetic field calculation, heat transfer analysis, and injection molding simulation. The proposed integrated simulation is extended to the injection molding of a thin-wall part, and the simulation results are compared with the experimental findings. The validity of the proposed simulation is discussed according to the ways of the boundary condition imposition.

고주파 유도가열을 사용한 급속 금형가열 시스템 개발 (1)

박근(K. Park),황재진(J. J. Hwang),권오경(O. K. Kwon),윤재호(J. H. Yun) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. Induction heating is an efficient to heat material by means of an electric current that is caused to flow through the material or its container by electromagnetic induction. It has various applications such as heat treatment, brazing, welding, melting, and mold heating. The present study covers a finite element analysis of the induction heating process which can rapidly raise mold temperature. To simulate the induction heating process, the electromagnetic field analysis and transient heat transfer analysis are required collectively. In this study, a coupled analysis connecting electromagnetic analysis with heat transfer simulation is carried out. The estimated temperature changes are compared with experimental findings for various heating conditions.

유리렌즈 성형 금형에서 방열블록 형상에 따른 금형 가열부의 열전달 특성 연구

서보민,정동연,박근,박창용 한국정밀공학회 2022 한국정밀공학회지 Vol.39 No.7

The purpose of this study is to propose a better contact surface pattern of a heat radiating block in a progressive GMP (Glass Molding Process) heating assembly. In this study, a simulation model based on FEM was developed to perform a thermal analysis for the heating assembly. It was verified by comparing experimental results. The temperature distribution on the heating block surface and heating energy consumption was analyzed with the change of contact surface pattern and area of a heat radiating block. The considered pattern on the contact surface was cross (+) and straight (-) shape. The contact area ratio was changed from 16 to 100%. The simulation results show that the heating energy consumption increased to reach a target temperature with the increase of contact area ratio. The straight-shaped patterns on a heat radiating block presented more uniform temperature distribution on the mold heating surface than the cross shaped surface, whereas it resulted in a slightly higher energy consumption of up to 9%. This study shows that the contact surface pattern on a heat dissipating block can control the temperature distribution on the mold heating surface.

CNT 필름 히터 적용 곡면형 금형의 균일 가열기법 연구

오서현,전은지,이현민,고영배,박근 한국정밀공학회 2022 한국정밀공학회지 Vol.39 No.7

Injection molding is one of most widely-used polymer processing technologies in which hot polymer fills a mold cavity, and is solidified during the subsequent cooling process. In the mold filling stage, the mold temperature should be high to improve flow characteristics, and low to reduce cooling time during the cooling stage. To fulfill these objectives, rapid mold heating technology has been developed to raise mold temperature, without significant increase in cycle time. While the conventional rapid heating technologies required dedicated facilities such as steam heating or high-frequency induction heating system and has a limitation in uniform heating, the purpose of this study was to develop a facile and conformal mold heating unit that uses a carbon nanotube (CNT) film heater. The CNT film heater was used to heat a curved mold with high temperature uniformity, by maintaining uniform distance from the mold surface. The developed conformal heating technology was then applied to a singly curved mold and a multiply curved mold. Considering that the resulting temperature uniformity is superior to the conventional oil heating, the conformal mold heating technology using the CNT film heater can be used to improve part quality and productivity in various molding processes.

유한요소해석과 다변수해석에 의한 선상가열 변형관계식

이장현(Jang Hyun Lee),신종계(Jong Gye Shin) 대한조선학회 2002 大韓造船學會 論文集 Vol.39 No.2

가열 요소를 이용한 형상기억폴리머 안테나 축소 모형의 전개 실험

구남서(Nam Seo Goo),안재균(Jae Kyun Ahn),김태균(Tae Kyun Kim),박미선(Miseon Park),박종규(Jongkyoo Park) 대한기계학회 2018 大韓機械學會論文集A Vol.42 No.10

우주 안테나용으로 연구 중인 열 자극 기반 형상기억폴리머로 된 축소 모형 안테나의 전개 실험을 수행하였다. 전개 실험을 위하여 양쪽 말단에 isocyanate기를 갖는 프리폴리머와 다관능기의 폴리올을 반응시켜 우레탄 형상기억폴리머를 합성하였으며, 2 mm의 두께를 갖는 원형 모양의 전개 시편을 제조하였다. 표면 부착형 가열 요소를 사용하여 형상기억폴리머 안테나 축소 모형을 전개한 결과, 가열요소의 크기와 방향 등에 따라 형상기억폴리머 시편의 온도 상승이 큰 차이를 나타내었다. 다양한 시도를 통하여 형상기억폴리머 시편을 전개시킬 수 있는 최적의 조건을 제시하였다. A deploying test of small-scale antenna models made of thermal stimulus-based shape memory polymer (SMP) was conducted; this material has been researched as a candidate for aerospace antenna applications. For the test, urethane SMP was synthesized from the prepolymer with diisocyanate and multi-functional polyol, and the circle-shaped specimens with a thickness of 2 mm were fabricated. The results of the deploying test of the SMP small-scale antenna model attached with heating element showed that the size and orientation of heating elements affect the temperature increase of the SMP specimens. The optimal attachment condition is suggested to deploy SMP effectively.

매스콘크리트의 열경사 조절에 의한 수화열과 온도균열의 방지

김성수,조태준,이정배 한국구조물진단유지관리공학회 2008 한국구조물진단유지관리공학회 논문집 Vol.12 No.6

초기 재령의 매스콘크리트는 양생과정에서 높은 온도를 유발한다. 수화열 저감 기법 중 내부구속이 지배적인 구조물에서 단면의 내외부 온도차를 관리하는 방식은 그 활용도가 매우 높다. 그러나 수화 균열을 예방하기위해 열경사를 조절하는 현재의 제한적인 방법은 콘크리트 중심과 표면 사이에 미세하거나 거대한 균열을 유발할 수 있다. 특히 냉각파이프를 이용하는 방법은 온도의 상승시에는 적용될 수 있지만, 내외부 온도차이가 심한 온도하강시의 대책으로는 적합하지 않다. 따라서 이 문제에 대한 해결방안으로 가열파이프를 동시에 사용하는 모델을 제안하여 유한요소법으로 해석하였다. 해석 결과, 제안된 냉각파이프와 가열파이프를 동시에 사용하는 방법이 열경사조절에 가장 효과적이며 이를 통해 온도균열을 효과적으로 제어할 수 있을 것으로 판단된다. The heat of hydration for early aged mass concrete induces high temperature with the hydration. Control of the temperature difference across a section is an effective strategy to minimize the hydration heat induced cracks for the structures where internal restraint is dominant. The current prevention methods for hydration cracking show some limitations for the control of thermal gradients, and these limitations could make micro and macro cracks in surface and core of concrete. Especially cooling methods can decrease the increasing hydration temperature, but it can not prevent the problem while decreasing temperature. Consequently heating pipes are added simultaneously with the cooling pipes in order to control the temperature gradients between core and surface of the concrete, followed by the finite element analysis (FEA). Based on the FEA, the proposed method using cooling pipe and heating pipes together has been found to be an effective alternative in thermal gradient control, in terms of controlling temperature induced cracks significantly.

A Study on the Variation of Physical Properties of Line-heated for Type-B LNG Fuel Tank with 9% Nickel Steel Plate

Kyung-Shin Choi(최경신),Ji-Han Lee(이지한),Ji-Ung Hong(홍지웅),Won-Jee Chung(정원지) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.7

Container vessels continue to grow in size, led by global shipowner. Large ships can be loaded more cargo at a time, reducing the cost of transportation per teu. this eventually leads to economies of sale, in which the production cost per unit decreases with increasing output. in accordance with the 70th Convention of the Marine Environment Protection Committee of the International Maritime Organization, as of January 1, 2020, MARPOL Annex Ⅵ Regulation 14.1.3 will be effective. All vessels must be meet these criteria to reduce Sox emissions and reduce NOx emissions by reducing the content of manned sulfur oxides from 3.5% to less than 0.5%, otherwise IACS Member States Entry to the port is denied. in order to do that need to LNG storage tank. in this study characteristic of the material after line heating (600℃,700℃,800℃,900℃) of 9% Ni steel used in the manufacture of LNG fuel tank of ship were verified using by mechanical test. In the heating method by line heating. The initial properties of steel are changed by variables such as temperature, time, speed. The experimental data of line heating presented in this paper confirmed that the initial change of 9% Ni steel could be minimized.

유도 가열 굽힘된 316 계열 오스테나이트 스테인리스 강 배관의 잔류응력 분포 고찰

김종성(Jong Sung Kim),김경수(Kyoung Soo Kim),오영진(Young Jin Oh),장현영(Hyun Young Chang),박흥배(Heung Bae Park) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.7

최근들어 원자력 발전소에 유도 가열 공정으로 굽힌 배관을 적용하려는 동향이 있다. 이러한 유도 가열 굽힘 공정 동안의 열-기계적 메커니즘에 의해 잔류응력이 발생할 수 있다. 잔류응력은 균열 발생과 성장에 중요한 영향을 미치는 균열 구동력들 중의 하나이다. 그러나, 기존 연구들은 두께 변화, 타원도와 같은 기하학적 형상 변이에 집중하고 있는 반면 공정 변수가 잔류응력에 미치는 영향과 관련된 연구는 찾아보기 힘들다. 본 연구에서는 316 오스테나이트 스테인리스 강으로 제작된 유도 가열 굽힘 배관의 잔류응력 분포에 미치는 공정 변수의 영향을 유한요소 변수 해석을 통해 고찰하였다. 고찰 결과, 굽힘 모멘트와 굽힘 각도는 잔류응력에 미치는 영향이 미미한 반면 유도 가열률과 이송 속도는 잔류응력에 상당한 영향을 미침을 확인하였다. The induction heating bending process, which has been recently applied to nuclear piping, can generate residual stresses due to thermomechanical mechanism during the process. This residual stress is one of the crack driving forces that have important effects on crack initiation and propagation. However, previous studies have focused only on geometric shape variations such as the change in thickness and ovality. Moreover, very few studies are available on the effects of process variables on residual stresses. This study investigated the effects of process variables on the residual stress distributions of induction heating bended austenitic stainless steel (316 series) piping using parametric finite element analysis. The results indicated that the heat generation rate and feed velocity have significant effects on the residual stresses whereas the moment and bending angle have insignificant effects.