| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a boring tool capable of preventing seizure of a stem guide hole by regulating surface roughness of a finishing surface of a bored hole within an optimum range for securing lubrication oil during a finish process of the stem guide hole. Ž<P>SOLUTION: A reamer inserted in a lower hole formed in a cut material in advance for cutting an inner wall surface of the lower hole and forming a processing hole includes cutting blades 31 and three bearing parts 26 at a constant interval in a circumference direction. The surface roughness of each bearing part 26 is set within a range of 1.1-1.4 μm in terms of Rz value, and sum W26 of width in a tool circumference direction of a plurality of the bearing parts 26 is set within 0.15×D to 0.45×D mm to an outer diameter D of the cutting blades 31. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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