（2） 机筒：是一金属圆筒，一般用耐热、耐压强度较高、坚固耐磨、耐腐蚀的合金钢或内衬合金钢的复合钢管制成。机筒与螺杆配合，实现对塑料的粉碎、软化、熔融、塑化、排气和压实，并向成型系统连续均匀输送胶料，一般机筒的长度为其直径的15～30倍，以使塑料得到充分加热和充分塑化为原则。
（4） 机头和模具：机头由合金钢内套和碳素钢外套构成，机头内装有成型模具，机头的作用是将旋转运动的塑料熔体转变为平行直线运动，均匀平稳的导入模套中，并赋予塑料以必要的成型压力，塑料在机筒内塑化压实，经多孔滤板沿一定的流道通过机头脖颈流入机头成型模具，模芯模套适当配合，形成截面不断减小的环形空隙，使塑料熔体在芯线的周围形成连续密实的管状包覆层。为保证机头内塑料流道合理，消除积存塑料的死角，往往安置有分流套筒，为消除塑料挤出时压力波动，也有设置均压环的。机头上还装有模具校正和调整的装置，便于调整和校正模芯和模套的同心度。
The main line of the civil line extruding machine includes a screw, a barrel, a hopper, a machine head, and a mold. The plastic is plasticized into a uniform melt through an extrusion system, and the extruder is continuously compressed under the pressure established in the process. head.
(1) Screw: It is the most important part of the extruder. It is directly related to the application range and productivity of the extruder. It is made of high strength and corrosion resistant alloy steel.
(2) Barrel: It is a metal cylinder. It is generally made of alloy steel with high heat resistance, high compressive strength, strong wear resistance and corrosion resistance or composite steel pipe lined with alloy steel. The barrel cooperates with the screw to realize the pulverization, softening, melting, plasticizing, venting and compaction of the plastic, and continuously and uniformly convey the rubber to the molding system. The length of the general barrel is 15 to 30 times its diameter, The principle of fully heating and fully plasticizing the plastic.
(3) Hopper: The bottom of the hopper is e with a cutting device to adjust and cut the flow. The side of the hopper is e with a sight hole and a calibration metering device.
(4) Machine head and die: The machine head is composed of alloy steel inner sleeve and carbon steel jacket. The machine head is e with a forming die. The function of the machine head is to transfor