A
machine for drilling oil-holes in crankshafts and the corresponding procedure. It can be used to
drill one, two or more crankshafts per cycle. Each
crankshaft can revolve on its own axis. The unit described is mounted on a horizontally-faced rotary table with vertical rotating axis, to place the crankshafts at different angles to the Z axis of the
machining module, maintaining the horizontal position of the longitudinal axes of the crankshafts. Facing the unit is the
machining module, provided with two horizontal spindles,
drill tool-holders, with their corresponding guide bushings and parallel to each other, one on top of the other, at the same distance as the two crankshafts. The module has movement in three co-ordinates: axis X (horizontal-transverse), Y (vertical ) and Z (horizontal-presenting tools). A fourth axis W, (with additional module and
independent action), moves parallel to Z and carries the guide bushings. It is provided with an automatic
changeover, (tool+
bushing or just the
bushing), incorporating simultaneously the pair of spindles.