| 摘要 |
A machine for perforating a cylindrical pipe consisting of a frame operable to support said pipe between diametrically opposed pairs of shear blades carried by said frame and extending longitudinally of said pipe, a head carried by said frame for powered movement through said pipe parallel to the axis thereof, and a pair of cutter wheels carried rotatably by said head on axes transverse to said pipe and having rolling engagement with the interior of said pipe respectively in alignment with one of said pairs of shear blades, each of said wheels having a series of angularly spaced cutter teeth projecting radially outwardly therefrom by a distance greater than the wall thickness of said pipe, each of said teeth being operable, as said wheel rolls through said pipe, to cooperate with the associated shear blades to cut a pair of short parallel slits longitudinally in the pipe wall, and to offset outwardly the wall section between said slits.
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