Apparatus for forming a gasket

• US 6,056,527 A
• Filed: 02/14/1997
• Issued: 05/02/2000
• Est. Priority Date: 01/24/1995
• Status: Expired due to Term

• Current Assignee: Parker Intangibles LLC (Parker-Hannifin Corporation)
• Original Assignee: George R. Watchko, John E. Soron, John P. Kalinoski, Michael H. Bunyan, Paul R. Vilandre, Rudolf I. Shvartsman, Russell T. Lucia
• Inventors: Bunyan, Michael H., Watchko, George R., Kalinoski, John P., Vilandre, Paul R., Lucia, Russell T., Shvartsman, Rudolf I., Soron, John E.
• Primary Examiner(s): Pyon, Harold
• Assistant Examiner(s): LEYSON, JOSEPH S
• Application Number:
  US08/800,362
• Time in Patent Office: 1,173 Days
• Field of Search: 425/113, 425/140, 425/141, 425/146, 425/376.1, 425/461, 425/DIG. 47, 425/465, 264/40.3, 264/40.7, 264/104, 264/323, 118/323, 222/263, 222/571, 156/500
• US Class Current: 425/113
• CPC Class Codes: B29C 48/363 using non-actuated dynamic mixing devices
• CPC Class Codes: B29L 2031/26 Sealing devices, e.g. packaging for pistons or pipe joints
• CPC Class Codes: F16J 15/064 the packing combining the sealing function with other functions
• CPC Class Codes: F16J 15/14 by means of granular or plastic material, or fluid
• CPC Class Codes: H05K 9/0015 Gaskets or seals

Abstract

An apparatus for forming an EMI shielding gasket. The gasket is a formed-in-place gasket which is deposited by an extruder. The gasket material is a fluent polymeric material having a conductive particles disposed therein. The fluent polymeric material is supplied to the extruder by a material supply system having several canisters and a mixing chamber. The fluent polymeric material is fed to a chamber in the extruder. Pressure is applied to the fluent polymeric material by a pressure supply system which includes a source of positive pressure and negative pressure, and a control module for selectively supplying positive pressure and negative pressure to the extrusion chamber.

Claims

1. 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, and

said 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.

2. The apparatus as recited in claim 1 wherein the control module is adapted to control the amount of pressure acting on said electrically conductive fluent polymeric material such that the extruder forms a bead with a cross section between 0.0002 in² and about 0.01563 in² with an accuracy of about +/-0.002 in.

3. The apparatus as recited in claim 1 wherein the extruder head is mounted for movement along an X, Y axis at a rate between about 0.5 in. per second to about 6 in. per second while forming a bead about 0.020 to about 0.125 in. wide and about 0.01 to about 0.125 in. high.

4. The apparatus as recited in claim 1 further comprising a heat curing apparatus for curing the bead on the substrate.

5. The apparatus as recited in claim 1 wherein the extrusion head orifice has a diameter of about 0.025 in. to about 0.090 in.

6. The apparatus as recited in claim 1 wherein the pressure on the extruder chamber varies from about -0.9 atmospheres to about 160 psi.

7. An apparatus for forming a bead on a substrate, said apparatus comprising:

a first container for holding a first component of an electrically conductive fluent polymeric material,

a second container for holding a second component of said electrically conductive fluent polymeric material,

a first and second conduit connecting the first container and the second container, respectively, to a mixing location for mixing a predetermined amount of each component of said electrically conductive fluent polymeric material,

an extruder having a chamber for holding a predetermined amount of electrically conductive fluent polymeric material,

a third conduit connecting said chamber and the mixing location for supplying the extruder with said electrically conductive fluent polymeric material,

a support for carrying said substrate,

an extrusion head connected to the chamber for applying said bead on said substrate, the extrusion head being movable with respect to the support,

a cap slidingly positioned within the chamber, said cap separating, and preventing contact between, the pressurized gas and the fluent polymeric material, and

an air conduit connected to the extruder for supplying air pressure to said cap and controlling the continuous flow thereof out of the extrusion head by varying the amount of pressure in the air conduit, a control module connected to said air conduit for controlling air pressure to cause extrusion of said bead on said substrate at first elevated pressure and for decreasing air pressure to discontinue extrusion of the bead without drool and with desired cross sectional accuracy.

11. The apparatus as recited in claim 7 wherein the extrusion head has an orifice with a diameter of about 0.025 in. to about 0.090 in.

12. The apparatus as recited in claim 7 wherein the pressure on the extruder chamber varies from about -0.9 atm to about 160 psi.

8. An apparatus for forming a bead on a substrate, said apparatus comprising:

a first container for holding a first component of an electrically conductive fluent polymeric material,

a second container for holding a second component of said electrically conductive fluent polymeric material,

a first and second conduit connecting the first container and the second container, respectively, to a mixing location for mixing a predetermined amount of each component of said electrically conductive fluent polymeric material,

an extruder having a chamber for holding a predetermined amount of electrically conductive fluent polymeric material,

a third conduit connecting said chamber and the mixing location for supplying the extruder with said electrically conductive fluent polymeric material,

a support for carrying said substrate,

an extrusion head connected to the chamber for applying said bead on said substrate, the extrusion head being movable with respect to the support, wherein the extrusion head has a decreasing diameter along the axial length thereof adapted to apply the bead of the fluent polymeric material on the substrate, the fluent polymeric material having a viscosity of 100,000 to 10,000,000 centipoise,

a cap slidingly positioned within the chamber, said cap separating, and preventing contact between, the pressurized gas and the fluent polymeric material, and

an air conduit connected to the extruder for supplying air pressure to said cap and controlling the continuous flow thereof out of the extrusion head by varying the amount of pressure in the air conduit, a control module connected to said air conduit for controlling air pressure to cause extrusion of said bead on said substrate at first elevated pressure and for decreasing air pressure to discontinue extrusion of the bead without drool and with desired cross sectional accuracy.

9. The apparatus as recited in claim 8 wherein said extruder head is movable at a rate of about 0.5 inches per second to about 6 inches per second and is adapted to form a bead having a cross-sectional area between about 0.0002 in² to about 0.01563 in².

10. The apparatus as recited in claim 8 further comprising a heating apparatus to cure the bead disposed on the substrate.

13. An apparatus for extruding electrically conductive polymeric material, said apparatus comprising:

an extruder having a chamber with a first and a second end for holding polymeric material,

a cap slidingly positioned within the chamber, said cap separating, and preventing

contact between, a pressurized gas and the polymeric material,

an extrusion head attached to said first end for extruding said polymeric material,

a source of positive gas pressure and a source of negative gas pressure connected to a control module,

said control module having an outlet end for selectively applying the positive and negative pressure on said cap, and

a conduit fluidly connecting the outlet end of the control module with the second end of the extruder chamber, whereby the amount of polymeric material extruded from the extrusion head varies with the amount of pressure applied on said cap.

14. An apparatus for forming a bead of an electrically conductive fluent polymeric material on a substrate, said apparatus comprising:

an extruder having a chamber for holding a predetermined amount of a fluent polymeric material having electrically conductive particle fillers therein and a viscosity of from 100,000 to 10,000,000 centipoise,

a cap slidingly positioned within the chamber, said cap separating, and preventing contact between, a pressurized gas and the fluent polymeric material,

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,

a second source of gas pressure having a pressure less than 1 atmosphere,

a control module connected to said extruder and to said first and second gas pressure sources to provide a desired pressure acting on said cap, said desired pressure ranging from a positive to a negative pressure,

said control module being adapted to control the amount of pressure acting on said cap in said extruder so that 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 said polymeric material is stopped by reducing the air pressure to said cap to less than about one atmosphere.