• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.341-347
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• 2003

Single flighted screw extrusion is the most cost effective method for the production of film, sheet, pipe and the fundamental step in other processes including blow molding and injection molding The temperature and injection pressure in barrel play a very important role in quality of products. Because thermal distortion and displacement of barrel by temperature difference and injection pressure difference cause irregular resine melting and flow. In this paper thermal distortion and stress of barrel includes pressure and temperature distributions by finite element analysis to understand dynamic characteristics of barrel.

• 한국정밀공학회지
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• 제32권11호
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• pp.977-982
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• 2015

This study uses finite element analysis to evaluate the forming load of tool entrance angle of the cold forward extrusion molding process of helical gear; this can replace the spur gear applied to the Electronic Parking Brake (EPB) system. A cold forging process is often used in the automobile industry as well as in various industrial machines due to its high efficiency. Finite element analysis is frequently used when interpreting results of the forging process. Formality was evaluated by calculating tooth profile filling rate of helical gear. Change in required forming load was investigated when the entrance angle of forward extrusion tool die was changed from $30^{\circ}$ to $60^{\circ}$, also by finite element analysis. We suggest suitable tool entrance angles.

• 대한기계학회논문집A
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• 제39권1호
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• pp.111-115
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• 2015

핫 러너를 이용한 사출 공정에서는, 색교체가 중요한 문제이다. 이 연구는 열가소성 수지의 색교체 특성을 평가할 수 있는 방법을 제시하고자 한다. 캐필러리 다이를 이용하여 색교체도를 평가할 수 있는 방법을 고안하고 구현한다. 캐필러리 다이로부터의 토출물을 영상화하여, 회색음영으로 정량화하였다. 그 음영도를 기반으로 하여, 색교체도를 결정하였다. 주어진 온도와 토출 속도에서, 색교체도가 토출회수에 따라 변화하는 추이를 얻어 내고 분석하였다.

• 한국재료학회지
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• 제22권5호
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• pp.227-236
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• 2012

Ionomer is a thermoplastic that is composed of covalent bonds and ionic bonds. It is possible to use this material in processes such as injection molding or extrusion molding due to the material's high oil resistance, weatherproof characteristics, and shock resistance. In this study, a new ionomer having a multifunctional group was prepared by a stepwise neutralization system with the addition of acidic and salt additives. In step I, to increase the contents of the multifunctional group and the acid degree in ethylene acrylic acid (EAA), MGA was added to the ionomer resin (EAA). A new ionomer was prepared via the traditional preparation method of the ionic cross-linking process. In step II, metal salt was added to the mixture of EAA and MGA. The extrusion process was performed using a twin extruder (L/D = 40, size : ${\varphi}30$). Ionomer film was prepared for evaluation of gas permeability by using the compression molding process. The degree of neutralized and ionic cross-linked new ionomer was confirmed by FT-IR and XRD analysis. In order to estimate the neutralization of the new ionomer film, various properties such as gas permeation and mechanical properties were measured. The physical strength and anti-scratch property of the new ionomer were improved with increase of the neutralization degree. The gas barrier property of the new ionomer was improved through the introduction of an ionic site. Also, the ionic degree of cross-linking and gas barrier property of the ionomer membrane prepared by stepwise neutralization were increased.

• 한국공작기계학회논문집
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• 제18권2호
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• pp.194-200
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• 2009

The extruder type is classified as screw type and non-screw type in terms of the extrusion method. The screw type extruder, which is the most frequently used, is classified as the single screw extruder and the multi-screw extruder. They are classified as vertical type and horizontal type in terms of structure; and those for compounding and for forming in terms of function. The single screw extruder is a universal extruder, most of which is suitable for the extrusion forming of thermoplastic resin. The multi-screw(two-screw, three-screw and four-screw) extruder can increase the extrusion power using the engagement of the screw flank. The single screw extruder does not have a good mixing ratio of the raw material and stable extrusion power, while it has low construction cost and operation cost. In this study, the single screw extruder, which has many weak points compared with the multi-screw extruder, was studied. There have been many studies on the single screw extruder, and they led to its significant development. The existing study method, however, had complex analysis processes and required much time. In this study, the CFD was applied to the performance test and analysis of the extruder, and the optimal design condition of the extrusion power for the screw and die of the single screw extruder was found by comparing the analysis results with the actual performance measurement of the single screw extruder.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.197-198
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• 2003

Poly(butylene terephthalate)(P5T) has long history as an engineering thermoplastic. PBT was first introduced commercially to the market place as an injection molding resin about 1969 by Celanese Plastics in the U.S.A. It is still widely used as a molding resin. Processing or forming methods for solid-phase deformation, such as stretching, hydrostatic extrusion. roller stretching, rolling, and so on can improve the mechanical properties effectively. (omitted)

• 한국생산제조학회지
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• 제20권1호
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• pp.81-85
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• 2011

Recently, the electronic parts are to be thinner plate, smaller size, light weight material and CPU, HDD and DRAM in all the parts have been produced on the basis of the high speed and greater capacity. Also, conventional goods have replaced a LED (Light-Emitting Diode) in lighting products so; such industry devices need to have cooling. To maximize all the performance on the heat-radiated products, the area of heat-radiated parts is required to be cooled for keeping the life time extension and performance of product up. Existing cooling systems are using radiant heat plate of aluminum, brass by extrusion molding, heat pipe or hydro-cooling system for cooling. There is a limitation for bringing the light weight of product, cost reduction, molding of the cooling system. So it is proposed that an alternative way was made for bringing to the cooling system. EP (Engineering Plastic) of low-cost ABS (Acrylonitrile butadiene styrene Resin) and PC (Polycarbonate) was coated with brass and the coating made the radiated heat go up. The performance of radiant heat plate is the similar to the existing part. We have studied experimentally on the radiated heat plate for the light-weight, molding improvement and low-cost. From now on, we are going to develop the way to replace the exiting plate with exterior surface of product as a cooling system.

• Korea-Australia Rheology Journal
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• 제11권4호
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• pp.305-311
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• 1999

The shear behavior of polymers obtained by means of devices such as capillary and cone-and-plate rheo-meters is commonly used to assess their processing performance and as a characterization tool. However, the number of instances when two polymers have the same shear properties but perform differently during certain types of processing operations (e.g. film blowing and sheet extrusion) indicate that shear properties alone may not be sufficient to characterize polymeric fluids. We begin by defining the kinematics of shear-free or extensional flow and the associated material functions. The extensional and shear behavior of three different types of polyethylene (PE) are then compared to illustrate the points that one cannot ascertain the extensional properties of polymer melts from their shear properties and, furthermore, there may not be a simple relation between properties obtained from one type of extensional flow and those of another type. The kinematics of most processing flows are extensional rather than shear in nature, and , hence, the performance of polymers during processes such as fiber spinning, film casting, film blowing, thermoforming, blow molding, and even extrusion is more readily accounted for through extensional viscosity measurements. Methods for carrying out extensional flow measurements are then reviewed including approximate methods. To illustrate the sensitivity of extensional viscosity measurements to subtle changes in the molecular architecture of PEs, results are presented for samples with a narrow molecular weight distribution but with varying numbers of long chain branches. Finally, constitutive equations which allow one to separate shear and extensional flow behavior are discussed as any attempts to simulate the subtle processing differences between two polymers will require constitutive equations of this nature.

• 폴리머
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• 제36권6호
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• pp.761-767
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• 2012

본 연구에서는 압출 컴파운딩 공정 및 압축 성형 공정을 이용하여 직하형 LED backlight unit(BLU)용 PC계 확산판을 제조하였다. 광 확산제로 무기 실리카 다공체의 적용을 시도하였으며, 제조된 확산판의 광학 및 열적, 기계적 물성의 변화를 조사하였다. 모폴로지 관찰을 통하여 광 확산제가 압출 공정 중 발생된 높은 전단응력에 의하여 PC 매트릭스 상에서 응집 현상 없이 균일하게 분산되었음을 확인하였다. 실리카 다공체를 보조 확산제로 첨가한 경우 확산판의 위치 및 시야각에 따른 휘도 균일도가 순수 아크릴 비드만을 첨가한 경우에 비해 뚜렷하게 향상되었으며, 반면에 절대휘도의 감소 정도는 매우 낮은 것으로 나타났다. 또한 첨가된 실리카 다공체는 확산판의 열 및 기계적 성질의 개선에도 기여하였다.

• Korean Chemical Engineering Research
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• 제50권6호
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• pp.1068-1075
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• 2012

압출성형을 통한 core/shell 구조를 갖는 폴리부틸렌테레프탈레이트(PBT)/Nylon6,12 미세모를 제조함에 있어 최적의 압출조건을 규명하기 위하여, 압출온도와 배합비를 다르게 하여 제조한 블렌드 미세모의 상용성을 SEM 모폴로지와 DSC 분석을 통해 확인하고 UTM을 통해 압출속도에 따른 기계적 물성의 변화를 측정하였다. SEM 모폴로지 분석결과 압출온도가 증가할수록 분산상인 Nylon6,12 비드의 크기가 감소하였으며, Nylon6,12의 함량이 증가할수록 PBT 매트릭스 내 Nylon6,12의 상분리 현상이 감소하였다. DSC 분석 결과도 같은 경향을 나타냈는데, 압출온도가 상승함에 따라 녹는점에 해당하는 피크들의 경계가 사라지고, Nylon6,12의 비율이 증가할수록 두 피크의 간격이 좁아지는 것을 확인할 수 있었다. 한편 PBT/Nylon6,12 블렌드 미세모의 인장강도와 연신율 및 굴곡강도와 굴곡탄성률 모두 압출온도가 $260^{\circ}C$ 일 때까지 증가하였으나 그 이상의 온도에서는 오히려 감소하였다. $260^{\circ}C$에서의 인장강도와 연신율, 굴곡강도, 굴곡탄성률은 각각 560 $kg_f/cm^2$와 220%, 807 $kg_f/cm^2$, 22,146 $kg_f/cm^2$였는데 이는 PBT와 Nylon6,12의 중간 값을 상회하는 수치로 두 물질이 압출성형에 의한 블렌드 효과가 있다는 것을 확인할 수 있었다. 이처럼 우수한 상용성을 보일 때의 블렌드 압출 조건들을 토대로 하여 core/shell 구조의 이중구조 미세모를 제조하였다.