Patent ID: 6056527
Filing Date: 2000-05-02
Classification: B29C,B29L,F16J,H05K

Abstract:
An apparatus for forming a bead on a substrate, said apparatus comprising:a container for holding a supply of electrically conductive fluent polymeric material having a viscosity from 100,000-10,000,000 centipoise,an extruder having a chamber for holding a predetermined amount of said fluent polymeric material,a first conduit connecting said container to said chamber for continuously supplying the fluent polymeric material to the extruder,a valve disposed in the first conduit for controlling the flow of material to the extruder,said extruder having an extrusion head defining an orifice and connected with said chamber for extruding said bead of fluent polymeric material on said substrate, said head being movable with respect to said substrate,a first source of gas pressure having a pressure greater than 1 atmosphere and a second source of gas pressure having a pressure less than 1 atmosphere and a control module connected to said first and second gas pressure sources to provide a desired pressure at an outlet thereof,a second conduit connecting said outlet to said extruder,a cap slidingly positioned within the chamber, said cap separating, and preventing contact between, the pressurized gas and the fluent polymeric material, andsaid control module being adapted to control the amount of pressure acting on said cap whereby the amount of fluent polymeric material extruded from the extrusion head is controlled by the amount of gas pressure supplied to said cap, and the flow of material is stopped by reducing the air pressure to said cap to less than about one atmosphere.