Patent ID: 11865800
Assignee: SUMITOMO RUBBER INDUSTRIES, LTD.
Field: Transport (Mechanical engineering)
Classification: CPC B | IPC B

Claim 13:
14. A tire mold used for producing a tire including a tread having a tread surface to come into contact with a road surface, at least two circumferential grooves being formed on the tread, thereby forming at least three land portions in the tread, the tread surface including the at least two circumferential grooves and at least three land surfaces that are outer surfaces of the at least three land portions, the tire mold comprising:
a tread-forming surface to shape the tread surface, wherein
the tread-forming surface includes projections to form the circumferential grooves and land surface-forming portions to form the land surfaces,
a surface that has a contour represented by at least one circular arc and that is tangent to the three land surface-forming portions aligned in an axial direction with the projections interposed therebetween is a reference forming surface of the tread-forming surface,
among the three land surface-forming portions, a land surface-forming portion located between the two projections is a curved land surface-forming portion,
the projections each include a reference side surface that is a side surface on the land surface-forming portion side, and a back side surface that is a side surface located on a back side of the reference side surface,
a tangent point between the curved land surface-forming portion and the reference forming surface is a reference tangent point,
a boundary between the reference side surface and the curved land surface-forming portion is a reference boundary point,
a point of intersection of the reference forming surface and a virtual line of the reference side surface that extends from the reference boundary point toward the reference forming surface is a reference virtual point of intersection,
a contour of the curved land surface-forming portion is represented by one or more circular arcs,
the reference boundary point is located inward of the reference forming surface,
under a condition that a first projection of the two projects has a first cross-sectional area, and the second projection of the two projects has a second cross-sectional area greater than the first cross-sectional area of the first projection, a first distance from the reference virtual point of intersection to the reference boundary point on the first projection side is shorter compared to a second distance from the reference virtual point of intersection to the reference boundary point on the second projection side is longer,
any position that is on a virtual line of the reference side surface and that is between the reference boundary point and the reference virtual point of intersection is a vertical point,
a circular arc that passes through the vertical point and that is tangent to the reference forming surface at the reference tangent point is a tangent point-side circular arc,
any position that is on the reference forming surface and that is between the reference tangent point and the reference virtual point of intersection is a horizontal point,
a point of intersection of the tangent point-side circular arc and a normal line that passes through the horizontal point and that is normal to the reference forming surface is an intermediate boundary point,
a circular arc that passes through the reference boundary point and that is tangent to the tangent point-side circular arc at the intermediate boundary point is a boundary-side circular arc, and
of the contour of the curved land surface-forming portion, a contour from the reference tangent point to the intermediate boundary point is represented by the tangent point-side circular arc, and a contour from the intermediate boundary point to the reference boundary point is represented by the boundary-side circular arc,
among the land surface-forming portions included in the tread-forming surface, a land surface-forming portion located on an outer side in the axial direction is a shoulder land surface-forming portion,
among the three land surface-forming portions, a land surface-forming portion located adjacent to the curved land surface-forming portion is the shoulder land surface-forming portion,
a side surface on the curved land surface-forming portion side of a projection located between the shoulder land surface-forming portion and the curved land surface-forming portion is the reference side surface, and a side surface on the shoulder land surface-forming portion side of said projection is the back side surface,
a tangent point between the shoulder land surface-forming portion and the reference forming surface is a shoulder reference tangent point,
a boundary between the back side surface and the shoulder land surface-forming portion is a shoulder reference boundary point,
a point of intersection of the reference forming surface and a virtual line of the back side surface that extends from the shoulder reference boundary point to the reference forming surface is a shoulder reference virtual point of intersection,
a distance from the shoulder reference virtual point of intersection to the shoulder reference boundary point at the back side surface is equal to a distance from the reference virtual point of intersection to the reference boundary point at the reference side surface,
a distance from the shoulder reference virtual point of intersection to the shoulder reference tangent point is equal to the distance from the reference virtual point of intersection to the reference tangent point,
any position that is on the virtual line of the back side surface and that is between the shoulder reference boundary point and the shoulder reference virtual point of intersection is a shoulder vertical point,
a circular arc that passes through the shoulder vertical point and that is tangent to the reference forming surface at the shoulder reference tangent point is a shoulder tangent point-side circular arc,
any position that is on the reference forming surface and that is between the shoulder reference tangent point and the shoulder reference virtual point of intersection is a shoulder horizontal point,
a point of intersection of the shoulder tangent point-side circular arc and a normal line that passes through the shoulder horizontal point and that is normal to the reference forming surface is a shoulder intermediate boundary point,
a circular arc that passes through the shoulder reference boundary point and that is tangent to the shoulder tangent point-side circular arc at the shoulder intermediate boundary point is a shoulder boundary-side circular arc,
of a contour of the shoulder land surface-forming portion, a contour from the shoulder reference tangent point to the shoulder intermediate boundary point is represented by the shoulder tangent point-side circular arc, and a contour from the shoulder intermediate boundary point to the shoulder reference boundary point is represented by the shoulder boundary-side circular arc,
a distance from the shoulder reference virtual point of intersection to the shoulder vertical point is equal to the distance from the reference virtual point of intersection to the vertical point, and
a distance from the shoulder reference virtual point of intersection to the shoulder horizontal point is equal to the distance from the reference virtual point of intersection to the horizontal point.