单螺杆一般在有效长度上分为三段，按螺杆直径大小 螺距 螺深确定三段有效长度，一般按各占三分之一划分。
Single screw is generally divided into three sections in terms of effective length. The effective length of three sections is determined according to the diameter and pitch depth of the screw, and is generally divided into three sections according to one third of each.
料口最后一道螺纹开始叫输送段：物料在此处要求不能塑化，但要预热、受压挤实，过去老挤出理论认为此处物料是松散体，后来通过证明此处物料实际是固体塞，就是说这里物料受挤压后是一固体象塞子一样，因此只要完成输送任务就是它的功能了。
The last thread of the throat begins to be called the conveying section: the material can't be plasticized here, but it needs to be preheated and compacted. In the past, the old extrusion theory considered that the material here is loose. Later, it was proved that the material here is actually a solid plug, that is to say, the material here is like a solid plug after being extruded, so as long as it is finished. Transport task is its function.
第二段叫压缩段，此时螺槽体积由大逐渐变小，并且温度要达到物料塑化程度，此处产生压缩由输送段三，在这里压缩到一，这叫螺杆的压缩比－－3﹕1，有的机器也有变化，完成塑化的物料进入到第三段。
The second section is called compression section. At this time, the volume of the groove decreases gradually from large to small, and the temperature should reach the degree of plasticization of the material. The compression is generated here from the conveyor section 3, where it is compressed to one. This is called the compression ratio of the screw - - 3:1. Some machines have also changed. The plasticized material enters the third section.
第三段是计量段，此处物料保持塑化温度，只是象计量泵那样准确、定量输送熔体物料，以供给机头，此时温度不能低于塑化温度，一般略高点。
The third section is the measurement section, where the material maintains the plasticizing temperature, just like the metering pump, accurately and quantitatively transports the melt material to supply the machine head. At this time, the temperature can not be lower than the plasticizing temperature, generally slightly higher.