Patent ID: 7258827

Claim:
A method for extruding unvulcanized rubber, in which an extruded rubber member is formed by extrusion by an extruding apparatus having a flow dividing mechanism that includes a first weir disposed at an upstream side of a die plate including an opening and apart from the die plate, and protruding from a second passage side of a second passage toward a first passage in a direction perpendicular to a direction in which a first unvulcanized rubber passes, and a partition wall extending substantially perpendicular from the first weir in a direction away from the die plate, one end portion of the first weir being connected to a passage-forming die and the other end portion thereof being disposed at a portion substantially corresponding to a widthwise intermediate portion of the opening of the die plate, the widthwise direction corresponding to a direction in which the first weir protrudes, the extruded rubber member having a cross sectional configuration in which a portion of a second unvulcanized rubber intrudes into the first unvulcanized rubber and a portion of the first unvulcanized rubber is disposed at both sides of the intruded second unvulcanized rubber in a direction intersecting a direction in which the second unvulcanized rubber intrudes, said method comprising the steps of: dividing a portion of the first unvulcanized rubber flowing through the first passage by the flow dividing mechanism into two flows at an upstream side of the die plate including the opening in the extruding apparatus; allowing a portion of the second unvulcanized rubber flowing through the second passage to intrude in between the two flows into which the portion of the first unvulcanized rubber is divided; and extruding, from the opening of the die plate, an extruded rubber member in which the first unvulcanized rubber and the second unvulcanized rubber are integrated with each other.