| 摘要 |
PURPOSE:To prevent a guide part from being worn out earlier than a cutting edge part as well as to make improvements in accuracy of bore finishing and tool service life, by using a superhigh pressure sintered body for both these cutting edge and guide parts, in case of a drilling tool for a two-flute gun reamer or the like. CONSTITUTION:In a two-flute gun reamer 2, there is provided with a chip discharge groove 22 on the outer circumference of a tip part of a tool body 21. A cemented carbide tip 23 is brazed to a surface of this chip discharge groove 22 facing toward a rotational direction A of the tool body 21. And, a cutting edge part consisting of a superhigh pressure sintered body of diamond is brazed to a cutting face of this tip 23. In addition, a cemented carbide guide pad 25 is brazed to the outer circumference of the tool body 21. More over, a guide part 26 consisting of the superhigh pressure sintered body of diamond is brazed to the outer circumferential part of this guide pad 25. This gun reamer 2 makes the guide part 26 contact with an inner circumferential surface of a bore, guiding the tool body 21, and it is designed so as to cut the inner circumferential surface of the bore.
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