A brief introduction about screw extruder
Typically, a screw extruder comprises an elongated cylinder or barrel, a feed hopper mounted on one end of the barrel, and a rotatable screw axially extending within the barrel. In use, an extrudable material is fed into the hopper, which in turn passes that material into the extruder barrel, and the extruder screw is rotated in the barrel to advance the extrudable material therethrough. The material is then forced from the barrel and, usually, through a nozzle or die that forms the extrudable material into a desired shape.
Near the inlet of the extruder barrel, the rotating extruder screw tends to push the extrudable material toward one side of the barrel. As a result, some extrudable materials, such as some chewing gum compositions, do not always flow smoothly into the extruder barrel from the feed hopper, and instead extrudable material may accumulate on one side of the hopper in the area of the hopper outlet. This interferes with the flow of the extrudable material through the extruder, and in fact might stop that flow. Moreover, the extruder screw may push clogged material upward in the feed hopper, and under certain conditions, material may actually be pushed upwards out of that hopper.Another object of the present invention is to insure a smooth and regular flow of material, such as chewing gum compositions, into an extruder barrel from a feed hopper.
A further object of this invention is to provide twin screw extruder with a feed assist roller to help push material into an extruder barrel from a feed hopper. These and other objects are attained with an extruder comprising an extruder head that forms a tubular passageway, an extruder screw rotatably disposed in that tubular passageway, and drive means connected to the extruder screw for rotating that screw to force an extrudable material through the tubular passageway. The extruder further comprises a feed hopper for holding the extrudable material, and having an outlet in communication with an inlet of the extruder head for conducting the material thereinto. The feed hopper defines a supplemental opening adjacent the inlet of the extruder head, and a feed assist roller is rotatably supported on the extruder and extends partly through the supplemental opening to a location adjacent the outlet of the feed hopper. Supplemental drive means is connected to the feed assist roller for rotating that roller to facilitate moving the extrudable material from the hopper and into the tubular passageway of the extruder head. Further benefits and advantages of the invention will become apparent from a consideration of the following detailed description given with reference to the accompanying drawings which specify and show preferred embodiments of the invention.