| 摘要 |
The present invention relates to a multi-diameter expanding drill capable of simply and simultaneously expand a variety of diameters of pipes by preparing different diameters of drill bits required to expand the internal diameters of the pipes, and efficiently expanding a connection end unit of a pipe by forming an elliptical curvature contact structure. According to an embodiment of the present invention, a drill comprises: a support flange formed to support one end of a pipe; an equipment coupling unit extended in a longitudinal direction on a back of the support flange to be able to be connected and detached from an electric apparatus; an internal diameter expansion unit extended in the longitudinal direction in a front of the flange unit, having different sizes of expanding tools inserted into an end of the pipe and divided into four sections to expand an internal diameter of the pipe, selecting an expansion diameter step by size of the expanding tools and forming the pipe to be processed. The internal diameter expansion unit comprises: an entry end unit to guide an entry path toward the pipe in the front end; a first expansion tool extended from one end of the entry end unit, having an external diameter to expand a pipe with a small diameter; a second expansion tool extended from one end of the first expansion tool, having an external diameter to expand a pipe with a medium diameter greater than the small diameter; a third expansion tool extended from one end of the second expansion tool, having an external diameter to expand a pipe with a medium-large diameter greater than the medium diameter; and a fourth expansion tool extended to be in contact with the support flange, having an external diameter to expand a pipe with a large diameter greater than the medium-large diameter. |
