Bridgestone Corporation

Hiroo Matsunaga

Misao Kawabata

Hisao Ushikubo

Yutaka Yamaguchi

Katsutoshi Tani

Hiroshi Imai

Hironobu Fukushima

Takeshi Hamachi

Miyoji Kishimoto

A pneumatic tire comprising a tread portion, a pair of sidewall portions and a pair of bead portions is manufactured by conducting the venting in a portion of a green tire placed in a vulcanization mold prior to vulcanization and corresponding to the sidewall portion in at least one place in a radial direction of the tire during the vulcanization.

Vulcanization process for pneumatic tire and mold therefor

It is a method of manufacturing a pneumatic tire provided with a bead guard having an excellent appearance without forming spews and bare, wherein when a pneumatic tire ( ) provided with a bead guard ( ) of a trapezoidal shape at section is vulcanization-shaped in a split type mold ( ) comprising a pair of annular side rings ( ) and many divided segments ( ) for the formation of a tread portion integrally united and engaged therewith, an edge ( - SE, - iSE) of a dividing face ( - S, - iS) between mutually adjoining side ring pieces ( - - ) formed by annularly dividing a side ring ( ) inward and outward in a radial direction with respect to a center axis line of the split type mold ( ) and located at a side of a tire shaping face is positioned in a place corresponding to a depressing portion ( ) forming a bead guard ( ).

Method of manufacturing pneumatic tire and vulcanizing metal mold used for the method

In the manufacture of pneumatic radial tires each having an annular groove in its central portion, a green tire is formed from a belt-tread band having a constricted portion formed by concavely depressing a belt and a tread inward in a radial direction of the tire.

Process for the manufacture of pneumatic radial tires with initial

A high-speed running pneumatic radial tire comprises a cylindrical crown portion, a pair of sidewall portions extending inward therefrom, a radial carcass extending from one of the sidewall portions through the crown portion to the other sidewall portion, and a belt and a tread successively superimposed on the crown portion outward in the radial direction of the tire. The tread has plural rows of blocks defined by plural circumferential grooves and many lateral grooves, and the belt is comprised of at least two main crosscord belt layers and an auxiliary belt layer arranged thereon. The auxiliary belt layer is formed by spirally winding a rubberized ribbon ply of heat-shrinkable cords on the main belt layers, in which an overlapped amount of the ribbon ply is made large in a zone of the tread substantially corresponding to the block row than in a zone of the tread substantially corresponding to the circumferential groove.

Pneumatic radial tires for passenger cars

A high performance pneumatic radial tire comprises a toroidal carcass, a tread radially outside a crown portion of the carcass, a belt layer interposed between the carcass and the tread and having a same width of the tread, and an auxiliary layer arranged between the belt layer and the tread and covering the entire belt layer. organic cords are buried substantially parallel to an equatorial plane of the tire in the auxiliary layer, and land portions are defined between at least two circumferential main grooves formed in an outer surface portion of the tread and between the circumferential main grooves and axially opposite edges of the tread. In the tire, a rigidity of the tire corresponding to locations overlapping the circumferential main grooves is made smaller than that of portions corresponding to the land portions by, for example, constituting the auxiliary layer from at least two auxiliary plies comprising one auxiliary ply located on a radially innermost side and covering the belt layer over an entire width thereof, and cutting at least a radially outermost auxiliary ply at locations overlapping the circumferential main grooves among the auxiliary plies having portions overlapping the circumferential main groove.

Growing community of inventors

Kodaira, Japan

Hiroo Matsunaga