• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.370-373
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• 2008

It is known that the temperatures of die, punch, holder and punch pad need to be kept different to get better formability in Mg sheet forming processes. Heating and cooling channels are usually equipped in each tool to assign different temperature. This study focused on the optimal design of the heating and cooling channels for a cross-shaped deep drawing die set. While the die and blankholder were heated to and kept at $250^{\circ}C$ by using heat cartridges, the punch and punch pad were kept at much lower temperature than that of the die and blankholder by water circulating through cooling channels. All the approaches were done by numerical analyses, aiming to maximize the cup height and to minimize the punch corner radius without any failure.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.1
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• pp.105-112
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• 2010

Weldlines are generated during the injection molding process when two or more melt flows are brought into contact. The weldlines are unavoidable in the cases of presence of holes or inserts, multi-gated delivery systems, significant thickness change, etc. At the welded contact region, a 'V'-shaped notch is formed on the surface of the molded part. This 'V'-notch deteriorates not only surface appearance but also mechanical strength of the molded part. To eliminate or reduce weldlines so as to improve the weldline strength, the mold temperature at the corresponding weld locations should be maintained higher than the glass transition temperature of the resin material. The present study implements high-frequency induction heating in order to rapidly raise mold surface temperature without a significant increase in cycle time. This induction heating enables to local mold heating so as to eliminate or reduce weldlines in an injection-molded plastic part. The effect of induction heating conditions on the weldline strength and surface appearance of an injection-molded part is investigated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1533-1538
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• 2003

The present technology of dielectric heating welding for synthetic resin sheet has a switching frequency over 10MHz by using vacuum tube elements, and has restrictively been applied to PVC whose dielectric loss is comparably high. The technology, however, has a difficulty in applying to materials which are made for environment and have low dielectric lose compared with other synthetic resin materials. Recently, the application of materials made for environment is increased so that the technology is faced with the limit. In this paper, a high frequency induction heating welder for synthetic resin sheet is designed applying temperature control by indirect heating to solve the problems about direct heating synthetic resin made for environment.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.294-295
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• 2014

스크린 플라즈마 기술은 저온에서 가열과 동시에 플라즈마에 의한 확산층을 형성할 수 있는 매우 큰 장점을 가진 기술이다. 특히 저합금강의 내부 경도 저하를 최소화 한 상태에서 표면경도를 올려 플라스틱 금형강 등에 이를 적용할 수 있는 연구를 진행하였고, 이에 대한 결과를 보고하고자 한다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.490-494
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• 2011

In this paper, using by rapid heating and cooling systems for injection molding and temperatures to changes. In the process of molding temperature and pressure inside the mold was found. In addition, the tensile strength of test specimens were molded, mechanical properties of injection molded parts were identified on mold temperature. Copper could withstand more tensile force than NAK. Therefore, it can be concluded that materials with high heat conductivity must be used in thin walled products.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.16-16
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• 1998

우주발사체용 로켓트 구조재로 사용되는 알루미늄합금 단조재는 강도확보를 위하여 고온으로 가열후 급냉과정에서 상당한 크기의 잔류응력이 발생되고 이로 인해 기계가공시 변형이 유발되어 조립성이 나빠진다. 잔류응력은 그 크기가 재료의 항복강도를 초과할 때 제거되므로 응력제거(stress relief)를 위해서는 외부하중이 가해져야 한다. 응력제거 처리는 소성변형, 열처리 및 초음파 등의 방법으로 수행되며 소성변형에 의한 제거효과가 가장 크다 형상이 복잡한 형 단조재의 경우 열간단조금형과 동일한 금형을 이용하는 TX52 등의 방법을 적용한다고 알려져 있으나 TX54에 대한 금형설계 및 소성변형률 적용 데이터는 공정 know-how로 분류되어 있다. 잔류응력제거 처리의 해석적 연구로는 판재와 링롤재에 대해서는 인장 및 압축 소성변형에 적용에 대한 결과가 발표된 바 있으나 형 단조재의 경우에는 전무하다

• Design & Manufacturing
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• v.2 no.2
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• pp.10-14
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• 2008

The application range of injection molded parts is expanding by the development of engineering plastics with good mechanical properties. Plastic products are specially used as automotive parts due to an excellent performance in the characteristics of a strength vs. weight. In this study, heating type of new method such as jet injection was applied to improve heat transfer coefficient is substituted for heating method of injection molding.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.49-54
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• 2010

Rotor pole for AC(alternating current) generator is manufactured through transfer warm forging die. As soon as the material is heated at the warm manufacturing process, it is transferred to the first stage for upsetting work and then to the second stage for lateral extrusion work. The processes at the lateral extrusion work such as die block, die bushing, center punch, and side punch make severe condition and abrasion which leads to shorten the die life. This causes production decrease, long maintenance time, and low level of precision. Research on the die material selection, heat process cycle improvement, electric discharge machining trouble solution, and re-construction of main parts is expected to find a method to lengthen the die life up to 40 - 50%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1237-1238
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• 2010

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.441-444
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• 2009

Weldlines are generated during the injection molding process when two or more melt flows are brought into contact. At the welded contact region, a 'V'-shaped notch is formed on the surface of the molded part. This 'V'-notch deteriorates not only surface appearance but also mechanical strength of the molded part. To eliminate or reduce weldlines so as to improve the weldline strength, the mold temperature at the corresponding weld locations should be maintained higher than the glass transition temperature of the resin material. The present study implements high-frequency induction heating in order to rapidly raise mold surface temperature without a significant increase in cycle time. This induction heating enables to local mold heating so as to eliminate or reduce weldlines in an injection-molded plastic part. The effect of induction heating conditions on the weldline strength and surface appearance of an injection-molded part is investigated.