Apparatus for cutting an oval hole in the wall of a pipe

An apparatus for cutting an oval hole in the wall of a pipe, said apparatus comprising a baseplate (1) with elements (18) for securing a pipe to be cut, a carriage (2) supported on top of the baseplate (1) for linear movement along runners (3), a drive pulley (4) driven by a power unit (7) and having an opening (8) for a tool (20) and an internal toothed rim (9) meshing with an external toothed rim (19) of the tool (20) for rotating the same, a gear (22) meshing with a second toothed rim (23) of the tool (20) for rotating it slowly, whereby a cutter head (24) is carried by said slow rotational motion relative to the carriage (2) along a circular path, the cutter head (24) rotating at the same time about its own axis driven by the toothed rims (9, 19), characterized in that adapted for rotation along with the drive pulley (4) is a cogged wheel (10), which through the transmission of a cam lever (11) is adapted to drive a shaft (12) whose rotational motion is transmitted on the one hand to drive the gear (22) and on the other hand to work the carriage (2) back and forth in relation to the baseplate (1), a round-trip displacement (2xa) being equal to a difference between the major axis and the minor axis of a desired ellipse.