Abstract: A novel solid conveying theory，double-flight driving theory(TGL theory), was proposed based on the model of arcplates.The key idea was to avoid circumferential shear to the solid plug and to make thetranslating from friction drag conveying to positive conveving in solid conveying zone. Through motion analysis and force analysis of the solid plug for the lKV single screw extruder, it was found that the driving forces from screwflank and feeding seeve flank were the reason of the motion of solidplug.The friction forces between solid plugand barrel surface and that between solid plug and screw surface constituted the resistance force.The boundary condition for avoiding circumferential sheal to the solid plug could be solved through the determination of coefficient k.

Key words: IKV single screw extruder;solid conveying theory, double-flight driving