< Topic >The wood-screw section of the high order accuracy which is united with cone grinding tool usually in the revolving shaft of the diameter 2.34mm which is installed in the hand piece of the engine for dentistry skill manufacture is provided.SolutionsIs the revolving shaft which makes with suitable depth the periodic duty after the second hand exchanging of the union with the cone grinding tool and grinding tool possible with the spiral shellfish conjunction of the wood-screw section this device due to the fact that diameter of the screw thread processes the wood-screw within diameter of the wire rod in one end of the revolving shaft which uses the wire rod whose precision of diameter is high.< Choice figure >Drawing 1【課題】歯科技工用エンジンのハンドピースに取り付ける通常直径2.34mmの回転軸において円錐形研磨具と合体する高精度の木ねじ部を設ける。【解決手段】本考案は直径の精度の高い線材を使用した回転軸の一端にねじ山の直径が線材の直径以内の木ねじの加工をすることにより、適当な深さでの木ねじ部の螺合により円錐形研磨具との合体と研磨具の使用済み交換後の反復使用を可能にした回転軸である。【選択図】図1
