High Specific Mechanical Energy extruder screw assemblies (14, 88, 98) and complete extruders (10, 86, 96) are provided, which include wide-flight intermediate screw sections (104) having axial flight widths greater than the flight widths of the inlet and outlet screw sections (102, 106) on opposite sides of the intermediate sections (104). The intermediate sections (104) provide increased friction and shear serving to enhance the SMEs imparted to comestible food materials during processing thereof.

High Specific Mechanical Energy extruder screw assemblies (14, 88, 98) and complete extruders (10, 86, 96) are provided, which include wide-flight intermediate screw sections (104) having axial flight widths greater than the flight widths of the inlet and outlet screw sections (102, 106) on opposite sides of the intermediate sections (104). The intermediate sections (104) provide increased friction and shear serving to enhance the SMEs imparted to comestible food materials during processing thereof.

A screw for a plasticating apparatus has one or more helical flights. A portion of the screw has a plurality of advancing grooves arranged in a noncontinuous helix cut in the screw. The advancing grooves are dimensioned to receive material therein as the material is conveyed through the barrel. The screw has a plurality of noncontinuous cross-cut grooves traversing one or more of the advancing grooves. The cross-cut grooves have a second helix angle greater than the first helix angle and less than ninety degrees; and/or one or more of the cross-cut grooves have a third helix angle of about ninety degrees.

A screw for a plasticating apparatus has one or more helical flights. A portion of the screw has a plurality of advancing grooves arranged in a noncontinuous helix cut in the screw. The advancing grooves are dimensioned to receive material therein as the material is conveyed through the barrel. The screw has a plurality of noncontinuous cross-cut grooves traversing one or more of the advancing grooves. The cross-cut grooves have a second helix angle greater than the first helix angle and less than ninety degrees; and/or one or more of the cross-cut grooves have a third helix angle of about ninety degrees.

There is provided with a screw that is inserted into a cylinder an inside of which a material is loaded, and is rotatably supported in both end portions on an upstream side and a downstream side, or in an end portion on the upstream side, in the cylinder; a first kneading blade including a plurality of first blades that are helically provided on the screw and send the material toward the downstream side with rotation of the screw; and a second kneading blade including a second blade that is helically provided on the screw and returns the material, which is sent toward the downstream side by the first kneading blade, toward the upstream side, the number of blades in the second blade being smaller than the number of blades in the first blade.

A co-rotating self-cleaning two-screw extruder with a gradual number of threads and through self-cleaning function, and a processing method using the same, are disclosed. The screw assembly in the extruder includes a first screw (3) and a second screw (4) that co-rotate at the same speed in engagement; the first screw (3) includes a first single threaded element, a first transition element, a multiple threaded element, a second transition element and a second single threaded element that are connected in sequence; and the second screw (4) includes a first single threaded element, a third transition element, a multiple threaded element, a fourth transition element and a second single threaded element that are connected in sequence. The materials are transferred by rotation of the first (3) and second screws (4), and get their respective compositions mixed based on the structure of a gradual number of threads; with the flow passage expanded, contracted and re-expanded in shape in sequence, the materials undergo the single-to-multiple threaded, multiple-to-single threaded and again single-to-multiple threaded chaotic mixing in sequence; and the first and second screws achieve the self-cleaning effect by wiping each other.

A screw for a plasticating apparatus has one or more helical flights. A portion of the screw has a plurality of advancing grooves arranged in a noncontinuous helix cut in the screw. The advancing grooves are dimensioned to receive material therein as the material is conveyed through the barrel. The screw has a plurality of noncontinuous cross-cut grooves traversing one or more of the advancing grooves. The cross-cut grooves have a second helix angle greater than the first helix angle and less than ninety degrees; and/or one or more of the cross-cut grooves have a third helix angle of about ninety degrees.

A screw for a plasticating apparatus has one or more helical flights. A portion of the screw has a plurality of advancing grooves arranged in a noncontinuous helix cut in the screw. The advancing grooves are dimensioned to receive material therein as the material is conveyed through the barrel. The screw has a plurality of noncontinuous cross-cut grooves traversing one or more of the advancing grooves. The cross-cut grooves have a second helix angle greater than the first helix angle and less than ninety degrees; and/or one or more of the cross-cut grooves have a third helix angle of about ninety degrees.

An apparatus having an extrusion machine and a feeding unit. for producing foamed polymeric material, in particular polyethylene and polypropylene, is disclosed. The extrusion machine includes a cylindrical barrel which is connected with a first end thereof to the feeding unit to receive a blend of plastic material to be extruded, a parallel pair of screws in the cylindrical barrel, a driving unit for driving the screws into rotation in opposite directions, a gas tank containing CO.sub.2 as a foaming gas, injection means for injecting the foaming gas into the cylindrical barrel; a head mounted at a second end of the cylindrical barrel opposite to the first end and heating means arranged around the cylindrical barrel for transferring heat thereto.

An apparatus having an extrusion machine and a feeding unit. for producing foamed polymeric material, in particular polyethylene and polypropylene, is disclosed. The extrusion machine includes a cylindrical barrel which is connected with a first end thereof to the feeding unit to receive a blend of plastic material to be extruded, a parallel pair of screws in the cylindrical barrel, a driving unit for driving the screws into rotation in opposite directions, a gas tank containing CO.sub.2 as a foaming gas, injection means for injecting the foaming gas into the cylindrical barrel; a head mounted at a second end of the cylindrical barrel opposite to the first end and heating means arranged around the cylindrical barrel for transferring heat thereto.