| 摘要 |
PROBLEM TO BE SOLVED: To thin a valve seat, improve the strength of a joining part and thermal conductivity, and suppress hardness change of a material by press-fitting the valve seat made of sintered alloy comprising iron as a main component into a valve port of a cylinder head made of aluminum alloy, and joining the valve seat by means of high frequency heating. SOLUTION: A cylindrical body 5 is manufactured by aluminum casting of AC2B as a member corresponding to a cylinder head. A valve seat 6 made of sintered alloy comprising Fe, C, Cr, and the like as components is manufactured on an edge part of a center penetrating hole of the cylindrical body 5. Namely, the valve seat 6 is press-fitted into the edge part of the center penetrating hole within a range of 0 to 120μm as a press-fit margin. A high frequency coil 7 for making cooling water flow to an inner circumferential part is disposed in an inner circumference of the valve seat 6. In this condition, a high frequency device is actuated so as to set a temperature gradient of a cross section of the valve seat 6 and the cylinder head 5 to a predetermined value, and thereby, connection is promoted at a differential material surface part, and both members 5, 6 are metallurgicaly joined with each other. |
