The sheet-like rubber forming device has a die body which has an opening having a predetermined cross sectional shape, and a variable die lip which is arranged in a front side of the die body and can change the height of the opening. The variable die lip is constructed by a first movable body and a second movable body. The die lip control unit controls the variable die lip so as to drive the first movable body in an opening direction from a state in which the first movable body and the second movable body are closed when the forming is started, hold the positions of the first movable body and the second movable body after reaching a predetermined height, and drive the second movable body in a closing direction when the forming is finished.

The sheet-like rubber forming device has a die body which has an opening having a predetermined cross sectional shape, and a variable die lip which is arranged in a front side of the die body and can change the height of the opening. The variable die lip is constructed by a first movable body and a second movable body. The die lip control unit controls the variable die lip so as to drive the first movable body in an opening direction from a state in which the first movable body and the second movable body are closed when the forming is started, hold the positions of the first movable body and the second movable body after reaching a predetermined height, and drive the second movable body in a closing direction when the forming is finished.

A method of forming a tread comprising two or more layers of rubber is described. The method includes the steps of: extruding a rubber compound through an extruder and a gear pump and mixing with an accelerant and then applying a continuous strip of rubber directly onto a tire building machine to form a first layer of rubber having a first cure rate; adjusting the amount of accelerant to obtain a second cure rate different than said first cure rate, and then applying a strip of rubber having a second cure rate onto the tire building machine, wherein one of the cure rates is faster than the other cure rate.

A method of forming a tread comprising two or more layers of rubber is described. The method includes the steps of: extruding a rubber compound through an extruder and a gear pump and mixing with an accelerant and then applying a continuous strip of rubber directly onto a tire building machine to form a first layer of rubber having a first cure rate; adjusting the amount of accelerant to obtain a second cure rate different than said first cure rate, and then applying a strip of rubber having a second cure rate onto the tire building machine, wherein one of the cure rates is faster than the other cure rate.

In a process for building tyres for vehicle wheels, at least one tread band (9) or other elastomeric component of a tyre (2) is made by applying at least one continuous elongated element (14) according to a plurality of turns (C) around a forming drum (15) rotating around a geometric rotation axis (X) thereof. The continuous elongated element (14) is made by the action of extruding a first material through an extrusion nozzle (16), to form an inner core (33) of said continuous elongated element (14) exiting from an outlet opening (18) of the extrusion nozzle (16). During the extrusion, a second material different from the first material is conveyed around the first material, at the extrusion nozzle (16) and upstream of the outlet opening (18), to form a coating layer (32) which entirely surrounds the inner core (33).

In a process for building tyres for vehicle wheels, at least one tread band (9) or other elastomeric component of a tyre (2) is made by applying at least one continuous elongated element (14) according to a plurality of turns (C) around a forming drum (15) rotating around a geometric rotation axis (X) thereof. The continuous elongated element (14) is made by the action of extruding a first material through an extrusion nozzle (16), to form an inner core (33) of said continuous elongated element (14) exiting from an outlet opening (18) of the extrusion nozzle (16). During the extrusion, a second material different from the first material is conveyed around the first material, at the extrusion nozzle (16) and upstream of the outlet opening (18), to form a coating layer (32) which entirely surrounds the inner core (33).

A method of manufacturing a pneumatic tire and a manufacturing device for a pneumatic tire capable for suppressing heat degradation in a base tire and forming a tread portion with high dimensional precision. A rigid inner mold (2) made of metal is brought into contact with a tire inner surface across an area corresponding to a tread portion (TR) of the base tire (BT), the strong rigid inner mold (2) supporting the base tire (BT) from the inner side. In this state, unvulcanized rubber (R) is injected into a cavity (11) of a tread mold (10) that covers an outer circumferential surface of the base tire (BT) corresponding to the tread portion (TR). Via vulcanization of this unvulcanized rubber R, a tread portion (TR) is formed on the outer circumferential surface of the base tire (BT) and the tread portion (TR) is integrated with the outer circumferential surface.

A method of manufacturing a pneumatic tire and a manufacturing device for a pneumatic tire capable for suppressing heat degradation in a base tire and forming a tread portion with high dimensional precision. A rigid inner mold (2) made of metal is brought into contact with a tire inner surface across an area corresponding to a tread portion (TR) of the base tire (BT), the strong rigid inner mold (2) supporting the base tire (BT) from the inner side. In this state, unvulcanized rubber (R) is injected into a cavity (11) of a tread mold (10) that covers an outer circumferential surface of the base tire (BT) corresponding to the tread portion (TR). Via vulcanization of this unvulcanized rubber R, a tread portion (TR) is formed on the outer circumferential surface of the base tire (BT) and the tread portion (TR) is integrated with the outer circumferential surface.

One or more embodiments of the present invention provide a method for forming a tread on a green carcass comprising the steps of providing a tire building drum having a carcass thereon, applying a strip of a base compound continuously over one half of the carcass forming a first layer of base compound from the centerline of the carcass to a first lateral edge, applying a first tread cap compound over the base compound, applying a strip of a base compound continuously over the second half of the carcass forming a second layer of base compound from the centerline of the carcass to a second lateral edge, forming a chimney along an edge of the first tread cap compound, and applying a first tread cap compound over the second layer of the base compound.

One or more embodiments of the present invention provide a method for forming a tread on a green carcass comprising the steps of providing a tire building drum having a carcass thereon, applying a strip of a base compound continuously over one half of the carcass forming a first layer of base compound from the centerline of the carcass to a first lateral edge, applying a first tread cap compound over the base compound, applying a strip of a base compound continuously over the second half of the carcass forming a second layer of base compound from the centerline of the carcass to a second lateral edge, forming a chimney along an edge of the first tread cap compound, and applying a first tread cap compound over the second layer of the base compound.