Milling unit with adjustable copying device

Milling unit with adjustable copying device (15)， comprising the following: a milling cutter (11) which has a cutting edge (12) which is arranged in a ring shape with respect to a working axis (A) and which is rotatable about the latter， around the edge (13) mill a plate (14); - A copying device (15) for guiding the milling cutter (11) relative to the plate (14)， including an annular element (16) and an expansion device (17)， which is coupled to the annular element (16) in order to expand it. The expansion device (17) contains at least one expansion element (18) which is coaxial to the milling cutter (11)， has an outer edge (18a) and is deformable between a first and a second configuration， in which at least a portion of its outer edge ( 18a) takes a first or a second distance from the working axis (A); wherein the second distance is greater than the first distance; - An actuating element (19) which is movable along the working axis (A). The expansion element (18) and the actuating element (19) are connected to one another and designed in such a way that movement of the second element results in a deformation of the first element， which includes a variation in the expansion of the expansion element (18) along the working axis (A).