A rapid locking device axially secures a disc-type tool (16), in particular a grinding disc on the flange (24) of a driven spindle (14), the spindle (14) having an axial bore containing at least one locking element in the form of a plate spring (28), which co-operates with a locking pad (22). The tool can be locked between contact surfaces of the flange (24) and the locking pad (22), the distance between said surfaces being modifiable. The shank (30) of the locking pad (22) can be accommodated in the bore of the spindle (14) and can be secured in a friction fit by the locking element (20).