Upper annular tire tread expansion loop and method thereof

The invention relates to an upper annular tire tread expansion loop and a method thereof, which are applied to an upper annular tire tread forming machine together. The loop adopts a mechanical type tire tread expansion mechanism to realize the state that an annular tire tread is inflated uniformly along the outer diameter of a tire body, and the inner diameter of the annular tire tread is expanded and stabilized to be more than the outer diameter of the tire body. The loop and the method can improve the accuracy for coaxial sleeve of the annular tire tread and the tire body, and prevent the phenomenon of tire tread deviation. While the annular tire tread is expanded and inflated, local stretching and local deformation are prevented from occurring so as to ensure the sleeving compactness between the annular tire tread and the tire body and improve the integral quality of tire renovation. The expansion loop is mainly provided with an expansion loop body sliding in a reciprocating mode along a bottom sliding seat; and a plurality of support rods which are distributed along the circumference of the ring and in axial connection are arranged on one side at the vertical part of the expansion loop body, while the other side is provided with a driving part which is connected and drives the support rods to move along a radial direction so as to support the annular tire tread.