Introduction and application of single screw extruder

Oct 28,2021

A single screw extruder consists of an Archimedean screw rotating in a heated barrel.Because of its simple structure, easy manufacturing, high processing efficiency, low price and is widely used, is the most mature technology, the most used extruder type.

Single screw extruder has the basic spiral structure, develop the screw block, such as damping exhaust type screw, slotted screw tubes, pin cylinder, a variety of different structure types such as modular structure, at the same time, because of the single screw extruder to take up the space is little, and become a composite processing and mainly used in the field of plastic blown film equipment.

single screw extruder

(SHANGHAI OMEGA MACHINERY CO., LTD exports a large number of extruders to the United States every year)

As the name implies, a single screw extruder is a single screw inside a cylinder.


01. Introduction of single screw extruder

The first segment: : start from the last section of thread of the feed port, called the conveying section.Material here requires not plasticizing, but to preheat, squeezed, the old extrusion theory in the past that the material is loose, and later proved that the material here is actually a solid plug, that is to say, here is a solid after extrusion like a plug, so as long as the completion of the conveying task is its function.

The second segment: called the compression segment. This section of the screw body product from large gradually smaller, and the temperature to reach the degree of material plasticization, compression here (by conveying section three, here can be compressed to a, this is called the screw compression ratio - 3:1, some machines also have different), complete plasticization of the material into the third section.

The third segment: measurement section. Here the material maintains the plasticizing temperature, just like the metering pump accurate, quantitative transport of melt material, to supply the head, the temperature can not be lower than the plasticizing temperature, generally slightly higher.

High efficiency single screw extruder adopts double-stage overall design to strengthen plasticizing function and ensure high speed and high performance stable extrusion. Comprehensive mixing design ensures the mixing effect of materials. High shear and low fusion plasticizing temperature ensures high performance low temperature and low pressure metering extrusion of materials.


02. Single screw extruder maintenance:

1. Because the electrical control system has high requirements for environmental temperature and dust prevention, the electrical system should be separated from the production site, and ventilation or ventilation fans should be installed. It is recommended to put the electric control cabinet in the simple room, keep the room clean and ventilated, so that the indoor temperature is not higher than 40℃.

2. Single screw extruder is not allowed to run empty, in order to avoid screw and machine rolling.The idle running of the host cannot exceed 100r/min. Start the main engine at a low speed first, check if there is any abnormal noise after starting the main engine, and then slowly increase the speed of the main engine to the allowable range of the process (it is better if it can be adjusted to the best state). When the new machine runs in, the current load should be 60-70%, and the current in normal use should not exceed 90%. Note: if any abnormal sound occurs during the operation of the extruder, stop immediately for inspection or repair.

3. Turn on the oil pump after startup and turn off the oil pump after shutdown; Water pump in the whole production process to maintain the working state, can not stop the operation of the pump, so as to avoid the barrel temperature rise lead to the barrel material decomposition and carbonization; Asbestos air cover of main motor fan should be cleaned frequently to avoid dust adhesion too much blocking air cover, resulting in insufficient heat dissipation of motor due to overheating and trip.

4. Clean the grime, tools and sundries on the surface of the unit in time.

5. Prevent metal or other debris falling into the hopper, so as not to damage the screw and barrel.In order to prevent iron debris from entering the barrel, magnetizing parts or magnetic frame can be installed at the feeding mouth of the material into the barrel to prevent debris from falling into the material must be screened in advance.

6. Pay attention to the production environment clean, do not make garbage impurities mixed with the material blocking the filter plate, affect the output, quality and increase the nose resistance.

7. Reducer should use the lubricating oil specified in the machine specification, and add oil according to the specified oil level height, too little oil, lubrication is not enough, reduce the service life of parts; Too much oil, high fever, high energy consumption, easy deterioration of oil, also make lubrication failure, resulting in damage to parts. The oil leakage part of the reducer should be replaced in time to ensure the amount of lubricating oil.


03. Main Uses:

It is mainly used for extrusion of pipe, sheet, plate and profile, and granulation of some modified materials.

1. Pipe extrusion: suitable for PP-R pipe, PE gas pipe, PEX crosslinking pipe, aluminum-plastic composite pipe, ABS pipe, PVC pipe, HDPE silicon core pipe and various co-extrusion composite pipe.

2. Sheet and sheet extrusion: suitable for PVC, PET, PS, PP, PC and other profiles and sheet extrusion.Other kinds of plastic extrusion such as wire, rod, etc.

3. Profile extrusion: adjust the speed of the extruder and change the structure of the extrusion screw can be used to produce PVC, polyolefin and other plastic profiles. Modified granulation: suitable for mixing, modifying and reinforcing granulation of various plastics.

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