Multistage reducing percussion bit of large aperture

The utility model relates to a when carrying out the large -diameter borehole to the concrete, can improve drilling hole of the percussion drill efficiency effectively, can reach required drilling diameter's multistage reducing percussion bit of large aperture again fast, including percussion bit, the diameter of percussion bit drilling rod begins grow gradually by the initiating terminal, and the spiral chip groove cutting part that distributes on the reducing drilling rod has inlayed multistage hole enlargement alloy head. The advantage: firstly, having improved effectively and having assaulted the drilling efficiency who bores, fast superdata realizes the quick reaming in required aperture and the quick discharge of reaming waste material, secondly, save labour, laborsaving. 本实用新型涉及种在对混凝土进行大孔径钻孔时，既能有效地提高冲击钻钻孔效率，又能快速达到所需钻孔直径的大孔径多级变径冲击钻头，包括冲击钻头，所述冲击钻头钻杆的直径由起始端开始逐渐变大，分布在变径钻杆上的螺旋排屑槽刃部嵌有多级扩径合金头。优点：是有效地提高了冲击钻的钻孔效率，快速达实现所需孔径的快速扩孔及扩孔废料的快速排出；二是省工、省力。