Device for axially retaining blades on a turbomachine rotor disk

1. A device for axially retaining blades on a rotor disk of a turbomachine, the device comprising an annulus that is mounted via a radially inner edge in an annular groove of the disk, and that bears via a radially outer edge against the roots of the blades mounted in grooves in the periphery of the disk, the device further comprising an annular lock received in the annular groove of the disk to prevent the annulus from turning in said annular groove, the radially inner edge of the annulus being festooned or crenellated, the annular groove of the disk comprising a radially outer edge that is festooned or crenellated, the annular lock comprising a radially inner portion that is festooned or crenellated, and said annular lock being turnable in the annular groove between an annulus-locking position and a position for mounting and dismounting in the annular groove.

2. A device according to claim 1 , wherein the annular lock has hooks for engaging by elastic snap-fastening on the radially inner edge of the annulus and between the solid portions of the radially outer edge of the annular groove in the annulus-locking position.

3. A device according to claim 2 , and wherein the hooks of the annular lock are formed on solid portions of its radially inner portion.

4. A device according to claim 2 , wherein the hooks of the annular lock comprise radial tabs extending towards the axis of the annular lock from a radially outer annular portion thereof, and axial tabs connected to the radial tabs at one of their ends, and terminating at their other ends in respective catches facing radially outwards and forming members for retaining the radially inner edge of the annulus.

5. A device according to claim 4 , wherein the catches of the annular hooks of the lock are designed to engage in part on the annular edges of gap portions of the radially inner edge of the annulus while the annulus is being put into place by movement in axial translation into the annular groove of the disk.

6. A device according to claim 1 , wherein, in the locking position of the annulus, solid portions of the radially inner edge of the annulus are axially aligned with solid portions of the radially outer edge of the annular groove to prevent the annulus and the annular lock from moving axially relative to the disk, and the solid portions of the radially inner portion of the annular lock engaged in gap portions of the radially inner edge of the annulus are engaged in the gap portions of the radially outer edge of the annular groove of the disk and are in transverse alignment therewith to prevent the annular lock and the annulus from turning relative to the disk.

7. A device according to claim 4 , wherein the axial tabs of the hooks are extended at their ends carrying the catches by respective second radial tabs extending away from the catches, these second radial tabs including means such as orifices for being caught or engaged by tools for applying traction to snap the catches onto the radially inner edge of the annulus, and for applying thrust to disengage the catches from the radially inner edge of the annulus in order to dismount the annulus.

8. A device according to claim 7 , wherein the second radial tabs of the annular lock which are engaged in gap portions of the radially outer edge of the annular groove when in the annulus-locking position, are of a shape that is substantially complementary to the shape of said gap portions.

9. A device according to claim 1 , wherein, in the annulus-locking position, a radially outer annular portion of the annular lock is pressed axially against the radially inner edge of the annulus which is pressed axially against solid portions of the radially outer edge of the annular groove, and which is clamped axially between the radially outer annular portion of the annular lock and catches of hooks formed on the radially inner portion of said annular lock.

10. A turbomachine comprising a device according to claim 1 .