Method of and apparatus for forming weather strip by extrusion

DETAILED DESCRIPTION According to one aspect of the present invention, there is provided a method for forming by extrusion, a weather strip of the type which has a trim portion having a substantially U-shaped cross-section and adapted to be secured to a vehicle body and a lip, the width of which varies according to a position along the length of the weather strip, the lip having a thickened end portion, the method includes the steps of: extruding unvulcanized rubber through a head mounted on a downstream end of an extruder; roughly shaping the extruded unvulcanized rubber by causing the extruded unvulcanized rubber to move through an opening formed in a main die plate disposed downstream of a head so as to shape a portion of the extruded unvulcanized rubber corresponding to the trim portion of the weather strip into a shape substantially conforming with the shape of the trim portion to be finally obtained, and a portion of the extruded unvulcanized rubber corresponding to the lip into a shape having a width not smaller than the maximum width of the lip to be finally formed; forming the thickened end portion by causing the shaped unvulcanized rubber to pass through a space defined by a movable orifice plate which is disposed downstream of the main die plate and which is provided with a recess configured substantially in conformity with the shape of the thickened end portion, while moving the movable orifice plate in the width direction of the weather strip, so as to form the portion of the shaped unvulcanized rubber corresponding to the thickened end portion into the shape of the thickened end portion; and shaping the end of the lip by further advancing the shaped unvulcanized rubber through an end shaping means defining a shape corresponding to the shape of the end of the lip to be finally obtained, while moving the end shaping means substantially together with the movable orifice plate, so as to shape the portion of the shaped unvulcanized rubber corresponding to the end of the lip into the shape of the end of the lip to be finally formed