Method for manufacturing a lightened toothed wheel by double overmoulding

A method for manufacturing a toothed wheel, said method comprising:

• a carrier core manufacturing step (a), during which a carrier core is made of a first polymer material, said carrier core including a hub with a main axis, as well as a collar which extends substantially radially from said hub, away from the main axis, up to a peripheral flanged edge said collar being delimited axially by an upper surface orientated on the side axially opposite to the flanged edge and by a lower surface axially orientated on the side of the flanged edge, and
• a coating step (b) during which is carried out by overmolding on the carrier core in a second polymer material, a permanent coating layer which remains permanently on the completed toothed wheel said coating layer comprising in one piece (i) a frontal layer which covers the upper surface of the collar as an axial over-thickness of said collar and (ii) a lateral layer which axially extends said frontal layer by covering the radially outer surface of the flanged edge as a radial over-thickness of said flanged edge, so that said lateral layer forms a wheel rim in the radial thickness of which meshing teeth of the wheel are formed,
• wherein, during the carrier core manufacturing step (a), channeling grooves are formed in the carrier core, wherein the channeling grooves extend substantially radially on the upper surface of the collar, from the hub up to the flanged edge, and further extend axially, in forming an angle, along said flanged edge on the radially outer surface of said flanged edge.