T-dies adapted for extrusion molding

A T-die adapted for extrusion molding of a plastic material such as plastic film is constituted by a lower stationary half and an upper movable half. The stationary half is integrally provided with a steady lip portion and a movable half is provided with a base portion and flexible lip portion so as to form a gap in slit form between the steady and flexible lip portions. The gap is adjusted partially by a plurality of adjusting bolts screwed to the upper portion of the movable half extending to cover the flexible lip portion with space, the bolts being arranged in a line along the longitudinal direction of the T-die and spaced equally with each other. Each bolt has such a length that the front end thereof downwardly presses the flexible lip portion when the bolt is driven downwardly. The flexible lip portion is provided with a plurality of U-shaped grooves each disposed between the adjacent two bolts and having a width of an opening substantially equal to the distance between the adjacent two bolts. The operation continuity and the flexibility of the flexible lip portion can be improved by the depth of the groove in accordance with the cross sectional shape thereof.