• 한국정밀공학회지
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• 제19권6호
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• pp.160-165
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• 2002

A study on digital processes of injection mold in reverse engineering are presented. Reverse engineering is useful fur several cases, where user has no geometry information of object. Laser scanner is used to obtaining 3D coordinates of object. Sequences to process cloud data are described; sampling to reduce number of points, sorting to adjust the point order, and fitting to curve and surface, and so on. Split slide structure of mold is used fur undercut part and high viscosity material. Flow of injection molding are analysed to correct cooling channel and simulate molding conditions. NC tool paths are generated to carve core and cavity. The processes are performed in digital data for reduction of lead time and consecutive geometry data.

• 오토저널
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• 제14권3호
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• pp.102-108
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• 1992

To clarify the structure of a diesel spray, a transient non-evaporating diesel spray injected under different ambient pressure and different injection pressure was studied. Spray tip penet- ration and spray angle were measured by taking the high speed shadowgraph of spray and Sauter mean Diameter(SMD) was also measured by light scattering technique at different positions along the spray axis and at different time from the start of injection. The effects of the operating parameters on the spray shape and SMD were investigated. By increasing the injection pressure, the spray tip penetration and the spray angle increased and the change of the ambient pressure also resulted in the considerable change in the shape of the spray. The analysis of SMD measurement showed that the atomization is a process that continues in sp- ace and time. As the injection pressure increases SMD decreases rapidly and with the increa- se of the ambient pressure the atomization process ends faster than the lower ambient press- ure and at lower pressure the atomization process continues to much farther downstream and far afterward.

• Design & Manufacturing
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• 제8권2호
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• pp.41-45
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• 2014

Automated polishing apparatus based on the research have been developed. The research is improvement of polishing process for surface quality and uniformity improvement of preform injection mold core. Surface quality of preform core have influence on ejecting and product quality after injection molding. Thus, the current being made by hand to automate the polishing process, the surface of the preform to improve the quality and uniformity improvement. First made a division by analyzing manual process a step-by-step. And draw a mechanism for converting mechanical movement. Automated polishing apparatus for preform core was developed, through which shortens production time and were able to secure the safety of the worker.

• 한국기계가공학회지
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• 제14권1호
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• pp.36-43
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• 2015

Optimizing multiple design characteristics which are usually in conflict with each other in the injection molding process is frequently becoming a critical problem for designers who work in this area. The purpose of this work is to develop an automated design methodology for optimizing two such design characteristics found in injection-molded parts. A value function based on decision-making theory is used as a means of evaluating the performance of a two-characteristic design alternative. Also, a design space reduction algorithm based on Taguchi's orthogonal arrays is utilized to discover an optimal design alternative. Verification of the developed design methodology is carried out for an actual model with two design characteristics, the weld line and the gate location, to be optimized in computer simulation experiments.

• 대한기계학회논문집
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• 제7권3호
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• pp.257-262
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• 1983

The performance of a direct-injection type diesel engine often depends on the shape of combustion chamber, strength of swirl or squish, the number of nozzle holes, etc. This is of course because the process of combustion in the cylinder was affected by the mixture formation process. In this paper, the relation betweeen the flame progress and the performance of engine was clarified by changing variously the combustion process in cylinder with a special method, and thus the measures for improving the combustion were indirectly examined. Namely it was investigated what effect the flame progress in cylinder, which was varied with the locality of the lean premixture injected by the auxiliary injection method using an auxiliary injection nozzle in advance at the place where main spray was injected later, has on the engine output, the exhaust smoke density and the NO concentration in exhaust gas.

• 한국기계가공학회지
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• 제15권6호
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• pp.50-57
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• 2016

Refrigerator glass shelves are manufactured by Insert Injection Molding. The current process of injection of glass into the mold induces movement of the core, on urethane springs. Defects in the product can result from too low a force being transmitted from the springs. To solve this problem, the force on the moving core and the injection molding pressure were subjected to numerical analysis. Based on this, the number of urethane springs as well as their hardness was changed to improve the situation. The number of springs was changed from 6 to 4. The diameter of the springs was increased from ${\emptyset}75$ to ${\emptyset}100$, and the hardness was increased from 70 (shore A) to 90 (shore A). These improvements caused the force on the molding core to increase by approximately 65,442 N. The proportion of defects decreased by 66%.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.1061-1064
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• 1997

Micro injection molding technology is very important fiw mass product of micro structures or micro parts. And, it is so difficult that the molding technology of micro pole or thin wall(barrier rib) structures with high aspect ratio. In this stud). \vc intend to research on the basic technology of micro wall structure part:< with high aspect ratio by the inject~on moldins method. The mold for esperimenrs with micro multi-square structures was made by L, I(;A process. One square polc's size is 157 157pm. height 50011111. And the distance of each poles is 5011n1. 7'hus. molding products will be for~nctl like as the net structure with thin wall of about 50pn thickness.(aspect ratio 10) Ihrough the e~lxriment. \be obtained the prociuctr of micro multi-square slructure with bout 37.000 cell per a piece. 'Ihe micro injection molding process technolog for thin wall by multi-square structure mold was analy~cd.

• 한국정밀공학회지
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• 제16권8호
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• pp.71-78
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• 1999

The application range of injection molded parts is expanding by the development of engineering plastics with good mechanical properties. Plastic gears are specially used as automotive parts due to an excellent performance in the characteristics of a strength vs. weight, and the study of injection molding process of plastic gear using Nylon66 is performed in this study. Filling, packing and cooling analyses were done by using the simulation software like Moldflow, and a mold was designed by following the simulation results. Pin-point gates with three points were taken to satisfy the design guides like a full-shot, and lower clamping force and uniform shrinkage. Characteristics of shrinkage of molded gear and temperature difference between cavity and core sides of a mold were shown.

• 소성∙가공
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• 제12권6호
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• pp.521-528
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• 2003

Powder injection molding (PIM) uses the shaping advantage of injection molding but is applicable to metals and ceramics. This process combines a small quantity of polymer with an inorganic powder to form a feedstock that can be molded. After shaping, the polymeric binder is extracted and the powder is sintered, often to near-theoretical densities. According1y, PIM delivers structural materials in a shaping technology previously restricted to polymers. The process overcomes the shape limitations of traditional powder compaction, the costs of machining, the productivity limits of isostatic pressing and slip casting, and the defect and tolerance limitations of conventional casting. Since 1980s when major attention was given to PIM process, it has been widening the application area from small parts with complex shape and tailored properties to structural parts requiring strength and ductility as in automotive, military and medical industries.

• 한국기계가공학회지
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• 제9권5호
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• pp.28-33
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• 2010

A computer code was developed to simulate all three stages of the injection molding process: filling, packing and cooling by finite element method. The constitutive equation used here was compressible Leonov model. The PVT relationship was assumed to follow the Tait equation. The flow-induced birefringence was related to the calculated flow stresses through the linear stress-optical law. Based on the simulation, the Taguchi method was used to investigate the influences of injection molding conditions on the birefringence of a center gate disk. In addition, the optimal processing conditions were selected to minimize the birefringence and the birefringence difference along the positions of the disk.