Classification of extruders,the extruder is the host of the extrusion molding production line,its function is to plasticize,transport materials and provide the pressure required for the product.Extrusion molding has the following advantages:the production process is continuous,and the production efficiency is high;the application range is wide,and it can produce pipes,rods,sheet metal cables,profiled materials,etc.,with small investment and fast harvest.Extruder exists as the main equipment for processing polymers,and has become a serialized and standardized series of mechanical products in many countries and my country's machinery industry.There are many types,their scope of use,and performance indicators are expressed by relevant parameters.

　　2.1 Classification of extruders

　　The extruders are classified as follows:according to the number of screws,they can be mainly divided into single-screw and twin-screw extruders;according to whether they are vented,they can be divided into vented and non-vented extruders;according to the position of the screws,they can be divided into vertical and extruders.Horizontal extruder.my country's national standard GBT12783-91 stipulates the same compilation method for China's rubber and plastic molding machinery:category number,composition number,auxiliary number,specification code design code,the first three codes are the most basic codes,and the specific methods are as follows

　　1.SJ-45x20 S is plastic,J is the extruder,45 is the screw diameter d,and the length-to-diameter ratio is 20:1(specification parameters,the standard stipulates that the length-to-diameter ratio of the extruder is 20:1,which may not be marked).

　　2.SJF-60x30S is plastic,J is extruder,F is foam(variety code),60 is screw diameter,and the length-to-diameter ratio of the screw is 30:1

　　Ratio,expressed in L/D

　　(3)The screw speed range refers to the maximum and minimum speed ranges when the screw rotates,expressed in nmin~nmax.

　　(4)Driving motor power refers to the power of the motor that drives the rod to rotate,and the unit is KW expressed in Pm.

　　(5)The heating power of the machine and the number of heating sections of the barrel.The heating power of the machine refers to the electric power of the barrel heating,expressed by Pn,and the unit is kw.The number of barrel heating sections means that the barrel is divided into several sections for heating,that is,the number of sections for temperature control,represented by B

　　(6)The productivity of the extruder refers to the production capacity of the extruder per unit time,with Q as the unit kg/h.

　　(7)Nominal specific power refers to the comprehensive index of motor power required to process 1kg of products per hour,represented by P,P=Pm/Qmax.

　　(8)The specific flow rate refers to the quality of the produced product per revolution of the screw,measured by QQ/n,and the unit is(kg/h)/(r/min).

　　(9)The height of the machine center refers to the height from the center line of the screw to the ground,expressed in H,and the unit is

　　mm.

　　(10)The overall dimensions of the machine are represented by length,width and height,and the unit is mm.

　　(11)The mass of the machine is represented by w,the unit or kilogram.