Machine for flaring holes in diaphragms of heat exchangers, comprising: - a first ground support frame , having a main direction of extension (x), adapted to support a diaphragm on a plane ; - a first working head , comprising a first flaring tool , provided with rotation movement around its vertical axis (y1), and vertical translation means for said first flaring tool ; - a second frame adapted to support said first working head so that the latter is mobile with respect thereto; - motor means (M) for driving said machine ; - a control unit (C), wherein said first working head comprises tilting means for said first flaring tool , adapted to allow an angular deviation movement with respect to a hub belonging to the vertical axis (y1) of rotation of said first flaring tool , when said first flaring tool touches said diaphragm to be inserted into one of said holes , characterized in that said machine comprises a second working head comprising: - a second flaring tool provided with rotation movement around its vertical axis (y2) and vertical translation means for said second flaring tool ; - tilting means for said second flaring tool adapted to allow an angular deviation movement with respect to a hub belonging to the vertical axis (y2) of rotation of said second flaring tool , when said second flaring tool touches said diaphragm to be inserted into one of said holes , wherein said second working head is situated on the opposing side with respect to said first working head and to said plane . - a first ground support frame , having a main direction of extension (x), adapted to support a diaphragm on a plane ; - a first working head , comprising a first flaring tool , provided with rotation movement around its vertical axis (y1), and vertical translation means for said first flaring tool ; - a second frame adapted to support said first working head so that the latter is mobile with respect thereto; - motor means (M) for driving said machine ; - a control unit (C), wherein said first working head comprises tilting means for said first flaring tool , adapted to allow an angular deviation movement with respect to a hub belonging to the vertical axis (y1) of rotation of said first flaring tool , when said first flaring tool touches said diaphragm to be inserted into one of said holes , characterized in that said machine comprises a second working head comprising: - a second flaring tool provided with rotation movement around its vertical axis (y2) and vertical translation means for said second flaring tool ; - tilting means for said second flaring tool adapted to allow an angular deviation movement with respect to a hub belonging to the vertical axis (y2) of rotation of said second flaring tool , when said second flaring tool touches said diaphragm to be inserted into one of said holes , - a second flaring tool provided with rotation movement around its vertical axis (y2) and vertical translation means for said second flaring tool ; - tilting means for said second flaring tool adapted to allow an angular deviation movement with respect to a hub belonging to the vertical axis (y2) of rotation of said second flaring tool , when said second flaring tool touches said diaphragm to be inserted into one of said holes , wherein said second working head is situated on the opposing side with respect to said first working head and to said plane . <EOS>