| Key Words |
Bedplate, Insert, Sintered metal(소결), Powder, Steam treatment(스팀처리), AL thermal spray coating (알루미늄 용사코팅), NVH, Die-casting |
| 초록 |
If it is necessary to improve the NVH of the engine, apply a bed plate (or lower crankcase). Bed plate suppresses crankshaft bending and torsion behavior by integrating the ladder frame and main bearing cap, which were independently consisted at the bottom of the block. At this time, since the bearing receives less load, rotational noise is reduced. The bearing cap of the bed plate can be made of Al material, but in the case of turbo and diesel, the crankshaft torsional behavior due to combustion pressure is large, so cast iron is used. A small gap between the surface of the cast iron insert and the aluminum part causes cracks due to slipping between the materials, resulting in an aluminum thermal spray coating on the insert surface. Although it is not a chemical bonding, it is known that a mechanical bonding force is formed between the cast iron surface and the aluminum material, thereby reducing microscopic gaps between dissimilar materials. However, the cost of the aluminum thermal spray coating used for our bedplates alone is estimated to be about 6-7 billion won/year. To solve this problem, we tried to introduce an insert structure that structurally suppresses slip between dissimilar materials without aluminum thermal spray coating. Based on the existing cast iron, a structure similar to a dovetail used for wood connection was implemented for the side protrusion, and a circular intaglio/embossed protrusion pattern was implemented on the lower surface of the insert. In order to realize such a combined structure, a sintering method that can implement a rather complicated shape on the outer/surface by vertical pressing was applied. |
