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論文 |
論文
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米山, 猛 ; 阿部, 諭 ; 宮丸, 充
概要:
The effect of weld-line reduction by using the laser metal sintered mold and the effect of hot air supply on the mold surface just before the injection have been investigated. The depth of the weld-line groove in the laser metal sintered mold
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is smaller than that in the conventional steel mold. Mold pressure increase in the laser metal sintered mold is faster than that in the steel mold and the peak pressure in the laser metal sintered mold is higher than that in the steel mold. This must be due to the low thermal conductivity of the laser metal sintered mold. As a preheating effect of the mold surface before the injection, hot air has been supplied on the mold surface using an air jet bulb. The reduction of the weld-line groove has been promoted in the laser metal sintered mold whereas few effects appeared in the steel mold. Surface temperature increase by the hot air supply in the laser metal sintered mold is larger than that in the steel mold. By this higher temperature increase, temperature of the resin on the weld-line area must be higher and the hardness of the resin must be lower in the laser metal sintered mold so that the resin is deformed well reducing the weld-line groove.
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| 2.
論文 |
論文
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米山, 猛 ; 香川, 博之 ; 阿部, 諭 ; 末廣, 栄覚
概要:
Effective cooling channels have been installed in the injection mold during the process of milling-combined laser metal sintering. In the case of molding a flat piece with multiple ribs, it is difficult to insert cooling channels between the
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ribs by conventional machining. Because the heat remains between the ribs, the piece shrinks after the molding to form a warp on the flat surface. Using milling-combined laser metal sintering, oval holes were fabricated between the ribs and they were connected in a spiral loop. The temperature around the ribs became uniform and the warp on the flat surface of the molded specimen reduced compared with that molded in the mold made by conventional method using milling and electro-discharge machining. Simulation of the mold temperature and the warp by commercial software showed the same tendency on the change of the warp with the mold type and the cooling temperature conditions. Therefore, the accuracy of the molded specimen is improved by inserting cooling channels in the mold where heat accumulates using a milling-combined laser metal sintering and the effect can be evaluated by a simulation.
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論文 |
論文
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米山, 猛 ; 内藤, 圭亮 ; 阿部, 諭 ; 宮丸, 充
概要:
Using milling combined laser metal sintering, porous surface has been fabricated on the thin walled cavity closed by the surrounded thick cavity in the injection mold. Resin flows into the cavity of 2mm thick at first around the thin part and
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then flows into the thin cavity of 0.2mm thick with 11mm square by packing pressure. The packing pressure for filling the thin part was compared among laser metal sintered mold with or without porous surface, steel mold with or without porous block. The result shows that packing pressure for filling the thin part in the sintered mold is low even without porous surface because of the low thermal conductivity of the sintered material. The packing pressure to fill the thin part in the sintered mold with porous surface is lower than that in the steel mold with porous block. Pressure applied on the mold surface in the sintered mold is higher than that in the steel mold under the same packing pressure.
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