| 摘要 |
PURPOSE:To eliminate local difference of wear resistance over the whole surface except the grip part of a tool steel drill body and to scheme to obtain uniform wear resistance on each drill part by covering with the covering layer in multi layer, and to obtain a long life of usage of drill. CONSTITUTION:The whole of the tool steel body except super hard alloy chip, brazed part, and grip part is covered with a covering layer which has the thickness of layer of 0.5-7mum and is constituted of a single layer or multi layer selected out of the group comprised from carbide, nitride, and oxide of titanium, and the solid solution having two kinds or more of the substance described above, and further aluminium oxide. If the thickness of layer is less than 0.5mm, wear resistance is inferior, and on the other hand, if the thickness is more than 7mum, the toughness of drill reduces, so the thickness of layer is restricted to the values described above. |
