• 대한기계학회논문집A
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• 제31권5호
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• pp.594-600
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• 2007

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 way to heat a conductive workpiece by means of high-frequency electric current caused by electromagnetic induction. Because the induction heating is a convenient and efficient way of indirect heating, it has various applications such as heat treatment, brazing, welding, melting, and mold heating. The present study covers an experimental investigation on the rapid heating using the induction heating and rapid cooling using a vortex tube in order to eliminate an excessive cycle time increase. Experiments are performed in the case of a steel cup mold core with various heating and cooling conditions. Temperature is measured during heating and cooling time, from which appropriate mold heating and cooling conditions can be obtained.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.439-443
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• 2008

Painting process or coating with acrylic film may improve the surface defects of injection molded parts deteriorated by weldlines. flow marks. and etc. However such processes increase the production costs and increase environmental problems. Recently various types of rapid mold heating & cooling technology have been developed in order to improve surface quality of products. In this study. the heating & cooling performance of a telephone case mold is investigated by heat transfer analysis, in which the rapid mold heating & reeling technology is applied. The surface temperature of the mold was measured using thermal image camera and compared with analysis results. The influence of the rapid mold heating & cooling technology on weldline appearance and cycle time increase was also examined.

• 한국기계가공학회지
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• 제19권7호
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• pp.60-66
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• 2020

In order to improve fatigue life of transmission gear carburizing is normally used. Carburizing is a very good process to achieve low cost and high performance. The machined gears are heated up to carburizing temperature and then cooled rapidly in an oil bath to produce high surface hardness. The gears may undergo excessive thermal distortion during heating and rapid cooling. In order to predict the distortion during heating and rapid cooling, a coupled thermo-mechanical simulation is needed. In the current research, the simulation of heating and cooling was performed. The results show that the thermal distortion and the residual stresses are well predicted by the coupled simulation. In addition, induction heating and rapid cooling simulation is carried out to predict the thermal distortion. The amount of distortion is compared. It is shown that induction heating is very effective to reduce thermal distortion.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1237-1238
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• 2010

• 소성∙가공
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• 제22권1호
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• pp.48-53
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• 2013

As the adoption of injection molding technology increases, injected-molded optical products require higher dimensional accuracy and optical stability than ever before. In the present study, four kinds of molding methods, i.e., conventional injection molding (CIM), injection/compression molding (ICM), rapid heat and cooling the mold(RHCM) and rapid injection/compression molding (RICM) were selected in order to investigate the optical anisotropy of a 7 inch Light Guide Plate(LGP) by examining the gap-wise distribution of birefringence and the extinction angle. The results indicate that the compression process can decrease flow-induced birefringence over the whole region and that rapid heating can decrease the birefringence level better than conventional molding. In addition, for the combination of compression and rapid heating a reversal flow was detected from the distribution of the extinction angle near the gate.

• 한국산학기술학회논문지
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• 제16권8호
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• pp.5074-5081
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• 2015

플라스틱 제품의 휨을 개선하기 위한 방법은 사출성형 공정에서 일어나는 불균일한 냉각을 균일하게 만들어 플라스틱 제품의 잔류응력을 제거하는 방법이다. 본 연구는 균일한 냉각을 위하여 펠티에 소자를 사용하여 급속가열 냉각 장치를 개발하였다. 급속냉각 가열 장치(RCHD)를 제작하여 전통적인 수냉 장치(TWCD)방식과 급속냉각 가열 장치방식에 따른 휨을 비교 분석하였고, 비결정성 수지인 ABS 수지를 사용하였다. 사출성형 조건인 보압시간, 금형온도, 냉각시간, 보압에 따라 휨의 변화량을 측정 비교하였고, 비결정성 ABS 수지에서 급속가열 냉각 장치 냉각방식이 전통적인 수냉방식 보다 휨이 더 적게 발생하고, 위의 결과들로 보아 조금 더 균일하게 냉각되는 것을 알 수 있었다. ABS 폴리머의 분포 상태를 SEM 사진을 통해서 확인하였다. 전통적인 수냉방식은 폴리머의 분포상태가 조밀하게 분포되어 있고, 급속냉각 가열 방식은 전통적인 수냉방식 보다 넓게 분포되어 있었다. 이것은 냉각이 균일하게 이루어지고, 금형의 온도가 서서히 진행되면서 폴리머의 입자가 커지게 되는데, 이것은 내부응력이 줄어든 것을 의미한다.

• 소성∙가공
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• 제23권8호
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• pp.475-481
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• 2014

Water quenching is one method of cooling after hot forming, which is presently being used for the manufacturing of automobile parts. The formed parts at room temperature are heated and then cooled rapidly in a water bath to produce high strength. The formed parts may undergo excessive thermal distortion during the water quench. In order to predict the distortion during water quenching, a coupled thermo-mechanical simulation is needed. In the current study, the simulation of heating and cooling of boron steel cylinders was performed. The material properties for the simulation were calculated from JMatPro, and the convective heat transfer coefficient was obtained from experimental tests. The results show that the thermal distortion and the residual stresses are well predicted by the coupled simulation.

• 한국전산유체공학회지
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• 제21권2호
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• pp.90-98
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• 2016

A numerical study is conducted on thermal performance of a large-area hot plate specially designed as a heating and cooling tool for thermal nanoimprint lithography process. The hot plate has a dimension of $240mm{\times}240mm{\times}20mm$, in which a series of cartridge heaters and cooling holes are installed. The material is stainless steel selected for enduring the high molding pressure. A numerical model based on the ANSYS Fluent is employed to predict the thermal behavior of the hot plate both in heating and cooling phases. The PID thermal control of the device is modeled by adding user defined functions. The results of numerical computation demonstrate that the use of cartridge heaters provides sufficient heat-up performance and the active liquid cooling in the cooling holes provides the required cool-down performance. However, a crucial technical issue is raised that the proposed design poses a large temperature non-uniformity in the steady heating phase and in the transient cooling phase. As a remedy, a new hot plate in which heat pipes are installed in the cooling holes is considered. The numerical results show that the installation of heat pipes could enhance the temperature uniformity both in the heating and cooling phases.

• 대한조선학회논문집
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• 제41권6호
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• pp.65-74
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• 2004

The inherent strain method is known to be very efficient in predicting the deformation of steel plate by line heating. However, in the actual line heating process in shipyard, the rapid quenching changes the phase of steel. In this study, In order to consider additional effects under phase transformation, inherent strain regions were assumed to expand. Also, when calculating inherent strain, material properties of steel in heating and cooling are applied differently considering phase transformation. In this process, a new method which can reflect thermal volume expansion of martensite is suggested.8y the suggested method, it was possible to predict the plate deformations by line heating more precisely.

• 소성∙가공
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• 제19권3호
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• pp.152-159
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• 2010

Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. High-frequency induction is an efficient way to heat mold surface by electromagnetic induction in a non-contact manner, and has been recently applied to the injection molding due to its capability of rapid heating and cooling of mold surface. The present study covers a three-dimensional finite element analysis to investigate heating efficiency and structural safety of the induction heating process of an injection mold. To simulate the induction heating process, an integrated simulation method is proposed by effectively connecting an electromagnetic field analysis, a transient heat transfer analysis and a thermal stress analysis. The estimated temperature changes are compared with experimental measurements for various types of induction coil, from which heating efficiency according to the coil shape is discussed. The resulting thermal stress distributions of the mold plate for various types of induction coils are also evaluated and discussed in terms of the structural safety.