机用螺尖丝锥
spiral pointed machine screw tap
十字螺丝批
Philip’s type screwdriver
塑柄自动擦旋螺丝批
automatic spiral ratchet screwdriver with plastic handle
自动擦旋螺丝批
automatic spiral ratchet screwdriver
闭凸尖锥
closed convex pointed cone
超音速尖锥边界层
supersonic sharp cone boundary layer