| 摘要 |
PURPOSE:To improve wear resistance and coupling strength of a valve seat, by press molding and sintering the valve seat, and then assembling the sintered alloy valve seat, worked to prescribed dimensions, to a cylinder head, finally applying steam treatment to the valve seat. CONSTITUTION:A sintered alloy made valve seat 2, finished with work, is assembled to a cylinder head 1 by press fit or shrinkage fit and expansion fit. Here the valve seat 2 is formed by press molding of normal powder metallurgy, after sintering, the valve seat, including its valve adapted surface 20, is worked to almost completed dimensions. Nozzles 40, uniformly injecting high temperature heating steam to said valve adapted surface 20, are provided in a steam gun 4, and the steam gun 4 is located at a face-to-face position to the valve seat 2. In this way, an excellent wear resistant oxidized film of Fe3O4 is formed to the valve adapted surface of the sintered alloy valve seat 2, simultaneously coupling strength of the valve seat to the cylinder head in their adapted part can be improved. |
