Method and device for forming pneumatic tire
A tire is formed by disposing a cylindrical band member on a forming drum and outer circumferential sides of side portions disposed on both sides of the forming drum in a drum axial direction; expanding in diameter the forming drum and moving the side portions closer together in the drum axial direction; making step portions formed in the band member conform to side surfaces of the forming drum; moving bead members toward the step portions and compression-bonding the bead members to the band member on the side surfaces of the forming drum; and using a turn-up mechanism to wrap the bead members by turning up both end portions of the band member in the drum axial direction to form an intermediate green tire.
1. A method for forming a pneumatic tire, comprising:
disposing a cylindrical band member on an outer circumferential side of an expandable and contractible forming drum and on outer circumferential sides of side portions disposed on both sides of the forming drum in a drum axial direction, forming a gap between the cylindrical band member and inner end portions of the side portions in a drum axial direction formed into a tapered shape that decreases in diameter extending inward in the drum axial direction, the gap further extending between the inner end portions of the side portions having the tapered shape and a planar end of a segment of the forming drum perpendicular to a surface of the outer circumferential sides of the side portions;
forming step portions in the band member by expanding the forming drum in diameter;
compression-bonding bead members onto the band member after forming the step portions, compressing-bonding the bead members further comprising compression-bonding the bead members on side surfaces of the forming drum by moving the bead members toward the step portions;
locking the bead members using a bead lock after compression-bonding the bead members on the side surfaces of the forming drum;
forming an intermediate green tire by wrapping the bead members by turning up both end portions of the band member in the drum axial direction; and
forming a green tire by bonding a remaining member to the intermediate green tire; wherein
the step portions of the band member are made to deform by being made to conform to the side surfaces of the forming drum and made to come into contact with the side surfaces by moving the side portions closer together in the drum axial direction in sync with a diameter-expanding operation of the forming drum.
2. The method for forming a pneumatic tire according to claim 1 , wherein
a diameter-expanding operation and movement of the side portions in the drum axial direction are synchronized by moving a portion of the forming drum along a surface with the tapered shape, with the portion of the forming drum being in contact with the surface with the tapered shape.