Rubber strip material
When forming a rubber member which is made up of a combination of a plurality of rubber compounds by winding spirally a ribbon-shaped unvulcanized rubber strip material in an overlapping fashion, the number of times of winding is reduced so as to shorten a fabrication cycle time of the rubber member to thereby increase the productivity thereof. As a means therefore, a rubber strip material whose cross section is divided into two or more regions which are made up of different rubber compounds is wound spirally on to a drum in an overlapping fashion so as to build a green tire or a tire rubber member.
1. A rubber strip material for building a green tire or a tire rubber member by being wound spirally in a tire circumferential direction in a partially overlapping fashion on a rotational support element, comprising:
a first rubber compound, and
a second rubber compound,
wherein in cross section, the rubber strip material is divided into a first region made up of said first rubber compound and a second region made up of said second rubber compound,
wherein said first region is wider than said second region,
wherein said first rubber compound has a lower air permeability than said second rubber compound, and
wherein a cross-sectional shape of said rubber strip material is a flat substantially crescent shape, a flat substantially triangular shape or a flat substantially trapezoidal shape.
2. The rubber strip material as set forth in claim 1 , wherein the cross-sectional shape of said rubber strip material has a thickness which is gradually reduced from a widthwise central portion towards both sides thereof.
3. A method of fabricating a green tire, comprising:
spirally winding a rubber strip material in a tire circumferential direction in a partially overlapping fashion on a rotational support element,
wherein said rubber strip material comprises
a first rubber compound, and
a second rubber compound,
wherein in cross section, the rubber strip material is divided into a first region made up of said first rubber compound and a second region made up of said second rubber compound,
wherein said first region is wider than said second region,
wherein said first rubber compound has a lower air permeability than said second rubber compound, and
wherein a cross-sectional shape of said rubber strip material is a flat substantially crescent shape, a flat substantially triangular shape or a flat substantially trapezoidal shape.
4. The method as set forth in claim 3 , wherein the cross-sectional shape of said rubber strip material has a thickness which is gradually reduced from a widthwise central portion towards both sides thereof.