Method for Determining the Transverse Curve of a Generally Cylindrical Receiving Surface
Method for determining the transverse curve of a receiving surface of generally cylindrical form designed, during the assembly of the tire blank, to receive the components forming a crown belt in which threads are placed at zero degrees relative to the longitudinal direction, the threads being continuously wound without tension. The elongation rate (A) to be applied to a turn of a zero-degree thread is determined according to the desired pre-tension (A=f(T)), according to its axial position in the tire. Depending upon the radial position (Rf) of the thread of the said turn in the tire fitted into its mould, the initial radial position (Ri=Rf/(1+A)) is determined so that the thread of the turn in question sustains the desired elongation rate during forming in the press. The transverse profile (Rfdp) of the receiving surface is determined, in the axial location of the said turn, by subtracting from the initial position of the thread (Ri) the thickness (e) of the components placed radially inside the turn of the said zero-degree thread (Rfdp=Rf/(1+f(T)) e).
1 . A method for determining the transverse curve of a receiving surface of generally cylindrical form designed, during the assembly of the tire blank, to receive the components forming a crown belt in which threads are placed at zero degrees relative to the longitudinal direction, the said threads being continuously wound without tension, comprising:
determining the elongation rate to be applied to a turn of a zero-degree thread according to the desired pre-tension (A=f(T)), according to its axial position in the tire;
determining, depending upon the radial position (Rf) of the thread of the said turn in the tire fitted into its mould, the initial radial position (Ri=Rf/(1+A)) so that the thread of the turn in question sustains the desired elongation rate during forming in the press; and
determining the transverse profile (Rfdp) of the receiving surface, in the axial location of the said turn, by subtracting from the initial position of the thread (Ri) the thickness (e) of the components placed radially inside the turn of the said zero-degree thread (Rfdp=Rf/(1+f(T)) e).
2 . The method according to claim 1 , wherein the tension of the windings of threads varies axially so that the transverse curve of the receiving form has at least one concavity oriented radially outwards.
3 . The method according to claim 2 , wherein the tension of the windings of threads varies axially so that the transverse curve of the receiving form has at least one concavity oriented radially inwards.