Abstract: A flexible membrane is attached to a holder for controlling flow in an extrusion die. The membrane includes a horizontal portion, first and second curved portions adjacent the horizontal portion, first and second offset portions adjacent the first and second curved portions, and first and second edges adjacent the first and second offset portions. The membrane is formed of a single piece of material. The flow control device including the flexible membrane may be produced by fabricating a membrane holder from a material, fabricating a flexible membrane from the same material, joining the flexible membrane to the membrane holder, and hardening the membrane holder and membrane.

Abstract: A flow control device is mounted within a channel of an extrusion die, wherein the channel is defined by a base surface and a side surface normal to the base surface. The device includes a main body and an auxiliary body, wherein the main body includes a side portion that sealingly contacts the side surface of the channel when a force is exerted on the side portion, and the auxiliary body is in contact with the base surface of the channel. The device further includes a flexible membrane on a face opposite the auxiliary body which can influence the flow of material through the channel by moving in a direction perpendicular to the direction of material flow. A sealing apparatus is used to prevent leakage of material between the die and the flexible membrane. The sealing apparatus includes a gasket disposed adjacent an end surface of the membrane and means for causing the gasket to apply a force against the end surface such that the gasket seals against the membrane.