• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.4
• /
• pp.525-540
• /
• 1997

The effect of mold rotation on the transport process and resultant macrosegregation pattern during solidification of an Al-Cu alloy contained in a vertical axisymmetric annular mold cooled from the inner wall is numerically investigated. The mold initially at rest starts to rotate at a prescribed angular velocity simultaneously with the beginning of cooling. Computed results for a representative case show that the mold rotation essentially suppresses the development of both thermal and solutal convections in the melt, creating distinct characteristics such as the liquidus front, flow pattern and temperature distribution from those for the stationary mold. Thermal convection which develops at the early stages of cooling is soon extinguished by the rotating flow induced during spin-up, and thus does not effectively remove the initial superheat from the melt. On the other hand, solutal convection, though it weakens considerably and is confined within the mushy zone, still predominates over the solute redistribution process. With increasing the angular velocity, the solute transport in the axial direction is enhanced, whereas that in the radial direction is reduced. The final macrosegregation formed in the mold rotating at moderate angular velocities appears to be favorable in comparison with the stationary casting, in that not only relatively homogenized composition is achieved, but also a severely positive-segregated channel is restrained.

• 한국정보통신설비학회:학술대회논문집
• /
• 2009.08a
• /
• pp.391-394
• /
• 2009

In this paper, achieved rise temperature distribution about degradation phenomenon of 2 MVA distribution mold transformer using finite element method (FEM). Usually, life of transformer is depended on temperature distribution of specification region than thermal special quality of transformer interior. Specially, life of transformer by decline of dielectric strength decreases rapidly in case rise by strangeness transformer interior hot spot temperature value permits. Because calculating high-voltage winding and low-voltage winding of mold transformer and Joule's loss of core for improvement these life, forecasted heat source, and high-voltage winding and low-voltage winding of mold transformer and rise temperature distribution of core for supply of electric power and temperature distribution of highest point on the basis of the result Also, calculated temperature rise limit of mold transformer and permission maximum temperature using analysis by electron miracle heat source alculate and forecasted rise temperature distribution by heat source of thermal analysis with calculated result.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.5 no.2
• /
• pp.186-190
• /
• 2004

By this time, a mold with nano size pattern was produced using a fabrication of X-ray lithography method and in a m icro size's case it was produced using fabrication of Deep UV lithography. In this paper, we produced mold with 400 $\mu{m}$depth pattern using a new technology of SLS(Selective Laser Sintering) Rapid Prototyping method. In addition to enhance strength and thermal stability, we produced Ni structure with a thickness of 300 $\mu{m}$ on a surface of mold using electro forming method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.10a
• /
• pp.289-292
• /
• 2007

To prevent the damage of glass lens molds and deterioration of glass lenses using in progressive GMP process, a thermal stress and a deformation of the glass lens molds at forming temperature should be considered in the design step. In this study, as a fundamental study to develop a multi cavity mold used in an aspheric glass lens molding, a heat transfer and a thermal stress analysis were carried out for the case of one cavity glass lens mold used in progressive GMP process. Finally, using analysis results, we estimated the thermal stress in a glass lens mold and predicted a modified height of guide ring that determines the forming height of a glass lens.

• Journal of Korea Foundry Society
• /
• v.7 no.2
• /
• pp.122-132
• /
• 1987

Full mold casting process is a new technique offering numerous advantages and promising possibilities. The present study is aimed to bring out the results of experiments carried out to study the effect of pattern coatings on the solidification of 99.5% pure aluminum plate-shaped castings in the various sand molds and the thermal behavior of the molds. The results of the investigation indicate that (i) with increase in pattern coating thickness, the relative chilling power decreases gradually for silica and increases for zircon coating, and (ii) the application of a pattern coating significantly reduces the maximum interface temperature by the mold which is more pronounced in the case of thinner mold wall. The investigation also indicates that Chvorinov's rule is not found to be valid for the casting in the full mold, with or without pattern coating. Therefore in full mold process, the pattern coating thickness will be a very important parameter in the study of thermal behavior.

• Journal of Korea Foundry Society
• /
• v.29 no.5
• /
• pp.238-243
• /
• 2009

This study has been carried out to investigate the cooling ability improvement of diecasting mold by decompression cooling system. The decompression cooling system was applied to the new/used oil pump cover molds. The temperature of the surface mold applied the decompression cooling system fell to 15 degrees, especially in case of the used mold. The defect ratio of the oil pump cover manufactured by decompression cooling system has decreased from 2.8 percent to 0.2 percent. According to the results of the cooling ability improvement of diecasting mold by decompression cooling system, the decompression degree and supply pressure were set up the control item to apply the decompression cooling system to the diecasting mold in the industry field.

• Design & Manufacturing
• /
• v.13 no.1
• /
• pp.25-30
• /
• 2019

This paper presents the design strategy for the optimal RTM molds of Carbon Fiber Reinforced Plastic (CFRP) by carbon fiber draping and resin flow simulation. First, the mold shape and molding condition were determined considering the undercut and die face of the product in the draping simulation, which made the preliminary shape of the product by compressing the carbon fiber. After that, the diffusion behavior during the injection of resin in the mold was predicted by the resin flow simulation. Finally, the optimal mold shape was designed by selecting the locations of resin injection port and vent based on total results of simulations. In this paper, the mold of automotive side mirror case was selected as the representative product. Also, the actual mold was manufactured based on the simulation design to confirm the practicality of it. This study is expected to contribute to the industry as a technology to improve the reliability and productivity of CFRP producted by RTM process.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.47 no.5
• /
• pp.112-119
• /
• 2015

The pulp mold attract the increasing concern as recyclable, biodegradable, and eco-friendly packaging materials. In order to broaden the applicability of the pulp mold as substitutes of the expanded styrofoam, the properties of various raw materials for the pulp mold were evaluated and the way for improving water resistance properties of the pulp mold were also tested by applying some additives. The higher value in the fines contents and in the water retention value were shown for the TMP (thermomechanical pulp), which resulted in the bulkier pulp mold with the higher moisture absorption property. In case of water resistance properties, the pulp mold made of white ledger stock showed the higher value in water contact angle and very slow water absorption rate. The addition of oil palm EFB fiber showed the improvement in the water resistance of the pulp mold made of UBKP. The effects of various additives on the improvement in the water resistance properties of the pulp mold were tested by using AKD, PVAm, epoxy resin. The application of AKD leaded to the higher increase in the water resistance. The results in this study showed the effects of AKD for the pulp mold could be improved and optimized by the application with fixing agent and by the ageing treatment after production.

• Journal of the Korea Safety Management & Science
• /
• v.15 no.4
• /
• pp.179-184
• /
• 2013

An accident from machine work is often fatal to the worker. This accident is mostly preventable through perfect process jig. In case of this machine work, however, the disaster frequently occurred because of the design which is not considered the beginning of product design, post-process and mass process of production. As for sand casting method, this has the merits of the production; the product is easily produced by manual labor. On the other hand, this method has the demerits of a bigger dimensional error contrary to other mass process of production. When the sand casting product is in machine work, there are various problems such as unsafe fix and excessive cutting, product desorption and rapid life depreciation of equipment and tools. Considering the characteristics of sand casting method, it is accepted as difficulty to improve the problems. In this study, it suggests shell mold method for mold instead of the machine work after the sand casting of the circle shape container product. And the surface accomplishes the following average of surface roughness Ra$9.94{\mu}m$ of machine work with the casting of flask mold by shell mold method. In accordance with the simplification of processing process and reducing the average thickness variation by mass production of product with detailed appearance, it has a good influence on safety accident prevention caused by production and damaged product. It is confirmed that making higher degree of size precision of all machine work product is possible to increase the safety and productivity, reduce the processing process and improve environment.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.20 no.6
• /
• pp.824-829
• /
• 2011

The mold is widely used for mass production in present industry. Also, product cycle time is faster, for this request, high productivity improvement in mold machining is required. And, In case of mold manufacturing company, the delivery shortening is required to quickly manufacture new product. Therefore, we aim for the delivery shortening though the method of machining time shortening in mold machining. On this paper, first, we made the NC-code of Insert die-casting as the object model using PowerMill. And then, analyzed cutting force by Toolpath in Insert mold machining using Production Module of Advantedge which is cutting force analysis program. After that, we came up with the optimum conditions of productivity improvement throughout the analysis result of before and after optimization of cutting force, machining time variation, and surface roughness by changing min tangential force to 80, 85, 90% of max tangential force.