Apparatus for building tire and method for using same

A method for using a tire building apparatus to form a side-reinforcing rubber and stick the formed side-reinforcing rubber to an inner peripheral surface of a cylindrical carcass band laid on the outer peripheral side of a building drum, the method comprising:

• providing the tire building apparatus which comprises an outer shaft, an intermediate shaft, and a center shaft disposed coaxially with each other, a building drum supported on the outer shaft and having a uniform outer diameter over the entire length, and means for rotating these shafts disposed on one side of the building drum, wherein the building drum comprises of two drum portions that are axially divided and which are displaceable in mutually approaching and separating directions and are adapted to be radially expanded and contracted, the intermediate shaft is connected to one drum portion, the one drum portion is drivably connected to the other drum portion so that the one drum portion and the other drum portion are able to reciprocably move in mutually opposite directions in the axial direction, and cam members adapted to bring the drum portions into radial expansive/contractive transformations are connected to the center shaft, and wherein the apparatus further comprises a first motor constantly drivably connected to the intermediate shaft and to the center shaft via a differential speed reducer and selectively drivably connected to the outer shaft, and a second motor constantly drivably connected to the center shaft via a differential speed reducer;
• determining the outer diameters and axial relative positions of paired drum portions corresponding to the tire size and the relative positions in accordance with rotating movements of center and intermediate shafts;
• shaping the side-reinforcing rubber having a required shape and dimension into an annular shape on the drum portions while rotating all of the shafts;
• radially expanding the side-reinforcing rubbers toward the carcass band laid on the outer peripheral side of the building drum in accordance with displacements of the cam members following the rotation of the center shaft;
• and
• after the maximum diameter portion of the side-reinforcing rubber are abutted against the inner peripheral surface of the carcass band, simultaneously performing an approaching displacement of the both drum portions and therefore the both side-reinforcing rubbers and an axially contracting displacement of the carcass band based on the rotation of the intermediate shaft while continuously expanding the side-reinforcing rubbers further to tightly contact the entire outer peripheral surfaces of the side reinforced rubbers with the inner peripheral surfaces of the carcass band.