Asymmetric co-rotating multi-screw extrusion device, extruder and processing method thereof

A multi-screw extruder, comprising:

• an asymmetric co-rotating multi-screw extrusion device, wherein the asymmetric co-rotating multi-screw extrusion device comprises
• a barrel, and
• a screw mechanism, arranged inside the barrel,
• wherein,
• the barrel is provided with a feed port located at one end of the screw mechanism and a discharge port located at another end of the screw mechanism, and the barrel comprises a conveying section, a melting section, an exhaust section, and a mixing extrusion section sequentially arranged from a side thereof where the feed port is located, wherein the exhaust section is provided with an exhaust hole;
• and
• the screw mechanism comprises at least a first screw and a second screw arranged parallel to the first screw, wherein the first screw and the second screw comprise a cross-sectional profile comprising a plurality of circular arcs forming a plurality of radial steps between roots and crests of the first screw and the second screw, and the first screw and the second screw are asymmetrically inter-meshed and co-rotate at a same speed;
• the cross-sectional profile of the first screw is formed by circular arcs of the plurality of circular arcs and curved arcs which are connected;
• the cross-sectional profile of the second screw is formed by circular arcs of the plurality of circular arcs and curved arcs which are connected;
• a number of the circular arcs and the curved arcs of the second screw is a same as that of the circular arcs and the curved arcs of the cross-sectional profile of the first screw;
• and,
• the circular arcs of the second screw are tangent to corresponding circular arcs of the first screw.

A processing method performed on an asymmetric co-rotating multi-screw extrusion device, wherein the asymmetric co-rotating multi-screw extrusion device comprises a barrel and a screw mechanism arranged inside the barrel, wherein the barrel is provided with a feed port located at one end of the screw mechanism and a discharge port located at another end of the screw mechanism, and the barrel comprises a conveying section, a melting section, an exhaust section, and a mixing extrusion section sequentially arranged from a side thereof where the feed port is located, wherein the exhaust section is provided with an exhaust hole, wherein the screw mechanism comprises at least a first screw and a second screw arranged parallel to the first screw, wherein the first screw and the second screw comprise a cross-sectional profile comprising a plurality of circular arcs forming a plurality of radial steps between roots and crests of the first screw and the second screw, and the first screw and the second screw are asymmetrically inter-meshed and co-rotate at a same speed, and wherein the cross-sectional profile of the first screw is formed by circular arcs of the plurality of circular arcs and curved arcs which are connected, wherein the cross-sectional profile of the second screw is formed by circular arcs of the plurality of circular arcs and curved arcs which are connected, wherein a number of the circular arcs and the curved arcs of the second screw is a same as that of the circular arcs and the curved arcs of the cross-sectional profile of the first screw, and wherein the circular arcs of the second screw are tangent to corresponding circular arcs of the first screw, and wherein the processing method comprises:

• pushing materials to move forward in a direction towards a flow channel of the melting section, by co-rotating the first screw and the second screw at the same speed along respective screw axes, after the materials are fed into a flow channel of the conveying section from the feed port;
• melting the materials to melt, through an accelerated melting process due to a strong axial back mixing effect, when the materials are moved into the flow channel of the melting section,
• venting gas from the exhaust section under an action of the first screw and the second screw, and further moving the materials in a direction towards a flow channel of the mixing extrusion section, after the materials that are melted are moved into a flow channel of the exhaust section from the flow channel of the melting section;
• and
• plasticizing and mixing the materials that are melted under the strong axial back mixing effect between the first screw and the second screw, and stably extruding the materials that are melted from the discharge port, after the materials that are melted are moved into the flow channel of the mixing extrusion section.