Patent ID: 7090797

Claim:
A method of extruding a product having two different materials, the method comprising the steps of: providing an extrusion device that has a nozzle outlet and two nozzle chambers supplying respective different materials to the nozzle outlet, a first of the two nozzle chambers supplying material for an outer part of the product and a second of the two nozzle chambers supplying material for an inner part of the product; supplying the respective different materials to the two nozzle chambers; increasing a size of the first of the two nozzle chambers at a rate that causes a decrease in an amount of the material from the first of the two nozzle chambers proceeding to the nozzle outlet; and decreasing a size of the second of the two nozzle chambers at a rate that causes an increase in an amount of the material from the second of the two nozzle chambers proceeding to the nozzle outlet.