Tire vulcanizing mold and pneumatic tire
There is provided a tire vulcanizing mold capable of smoothly and surely forming narrow-width grooves in a treading face without causing the damage, breakage and the like of projections for the formation of the grooves in a sector mold and land portions in the tread, which comprises a plurality of sector molds arranged at predetermined pitches in a circumferential direction and displacing in synchronization with each other in extension and retraction directions to conduct the vulcanization of a tire tread portion, wherein a projection for the formation of the groove formed in an inner surface of each of the sector molds is projected from the inner surface of the sector mold in a direction substantially parallel to a displacing direction of the respective sector mold.
1. A tire vulcanizing mold comprising a plurality of sector molds arranged at predetermined pitches in a circumferential direction and displacing in synchronization with each other in extension and retraction directions to conduct the vulcanization of a tire tread portion, in which at least a portion of a projection for the formation of a groove formed in an inner surface of each of the sector molds is formed away from the circumferential center of the sector mold and is projected from the inner surface of the sector mold in a direction substantially parallel to a displacing direction of the respective sector mold.
2. A tire vulcanizing mold according to claim 1 , wherein the displacing direction of the each sector mold is a radially line segment direction connecting a center of the inner surface of the sector mold to a center of a space defined by these sector molds.
3. A tire vulcanizing mold according to claim 1 , wherein the projecting length of the projection from the inner surface of the sector mold is within a range of 40-180 mm.
4. A tire vulcanizing mold according to claim 1 , wherein the projections are slanted with respect to the circumferential direction at a contact position between the mutually adjoining sector molds and wherein the projection direction of the projections at the contact position is a direction parallel to an adjusting line segment connecting an intersect between a circumferential line segment connecting centers of the sector molds and a contact edge of the sector mold to the center of the space defined by these sector molds, and the projecting directions of these projections are gradually approximated to the displacing direction of the each sector mold as they are separated away from the contact edge position of the sector mold.
5. A tire vulcanizing mold according to claim 4 , wherein the projecting direction of the projection at a position separated from the contact position between the mutual sector molds by not less than 50 mm along a ridge line of the projection is made coincident with the displacing direction of the sector mold.
6. A tire vulcanizing mold according to claim 1 , wherein the projections are slanted with respect to the circumferential direction at a contact position between the mutually adjoining sector molds and wherein the projection direction of the projections at the contact position is a direction parallel to an adjusting line segment connecting an intersect between a circumferential line segment connecting centers of the sector molds and a contact edge of the sector mold to the center of the space defined by these sector molds, the projection becomes larger for the formation of a lug groove at the distance separated from the contact position between the sector molds by less than 50 mm along the ridge of the projection and the projection direction for the projection at the distance separated from the contact position between the sector molds by less than 50 mm is a direction parallel to the adjusting line segment up to the continuing position to the distance separated from the contact position between the sector molds by less than 50 mm, and the projection is gradually approximated to the displacing direction of the each sector mold as they are separated away from the contact edge position of the sector mold.
7. A tire vulcanizing mold according to, claim 1 , wherein the pitch number of the sector molds over a full periphery is 12-45.
8. A pneumatic tire vulcanized by a tire vulcanizing mold as claimed in claim 1 .
9. A tire vulcanizing mold comprising a plurality of sector molds arranged at predetermined pitches in a circumferential direction and displacing in synchronization with each other in extension and retraction directions to conduct the vulcanization of a tire tread portion, in which a projection for the formation of a groove formed in an inner surface of each of the sector molds is formed away from a center of the sector mold in the circumferential direction of the sector mold and is projected from the inner surface of the sector mold in a direction parallel to a displacing direction of the respective sector mold.