Mechanism for the drive of a tool spindle

A mechanism for the drive of a tool spindle which performs a rotating indexing motion, an axial movement and at the same time a rotary movement, comprises a reciprocating drive means kinematically connected to the tool spindle for performing the axial movement, an indexing mechanism connected to the tool spindle and arranged coaxially therewith for rotation therewith for performing the indexing movement, and at least one rocking lever provided with a pivot point fixed to a frame and kinematically connected to the tool spindle and the indexing mechanism for performing the rotary movement, said at least one rocking lever comprises at least one lever arm which is adjustable in its length for varying the pitch of the helical movement resulting from the axial movement and the rotary movement, further comprising a sliding coupling consisting of at least two members, wherein one member is a rocking lever which is connected to the other member through a sliding swivel joint having a sliding guide, the sliding swivel joint is continuously displaceably mounted along the rocking lever and is selectively located in the displacement positions, wherein the axis of rotation of the sliding swivel joint and hence the other member executes a linear movement while the sliding guide of the sliding swivel joint performs a movement perpendicular thereto, whereby the linear movement of the other member causes a linear adjustment movement in the indexing mechanism.