Method of foam-filling a tire carcass

Abstract

A method of making a foam-filled tire wherein a resilient elastomeric foam is formed and cured within a tire carcass while the carcass interior is at super-atmospheric pressure. Such superatmospheric pressure is believed to support the cell walls against internally generated gas (blowing) pressures, thereby stabilizing the cells at higher than usual internal cell pressure. The foaming operation is carried out so that the foam only partially fills the carcass interior. After the elastomeric foam has been cured the tire carcass interior is depressurized down to the pressure to be used in service. During the depressurization process the internal cell pressures cause the cells to expand and further fill the tire interior space. The depressurization processis carried out after the elastomeric foam has been cured, i.e. when the cell walls have attained their full potential strength. Accordingly, the post-cure expansion of the cell walls does not result in cell wall rupture, even though the cell walls are relatively thin. The thin cell walls resulting from this process are advantageous in that they reduce the required mass of foam-forming elastomer, thereby achieving improvements in respect to lower raw material costs, shorter cure times, lesser non-useful dead loads, lesser heat build-up and foam degradation during service, and lesser tendency toward wheel imbalance.

Dependencies are inferred from the claim text.