The Planetary Screw Barrel

The planetary screw is mainly used in the calender production line of PVC sheet material, to feed the calender, or to granulate the PVC. 

一、The Structure of Planetary Screw Extruder 

The planetary screw extruder is composed of transmission system, extrusion system, feeding system and temperature control system.  

Planetary screw extruder extrusion system is divided into two segments, the first paragraph for conventional single screw, (the screw diameter is equal to the barrel diameter), the second section of the screw for a planet, it is more similar to the planetary gear train the root of the screw. One large diameter screw in the center is the main screw, and a number of screws with small diameters are arranged around it.  In addition to meshing with the main screw, the small screw is also meshing with the inner spiral processed on the inner wall of the barrel (the barrel is like an inner gear, but does not rotate).  The main screw is connected with the first single screw.  When the main screw turns, it drives the small screw to turn.  In addition to the small screw around its geometric center autobiography, but also around the main screw revolution. 

According to the different use purposes, the planetary section and single screw section can have different combinations: calendaring machine feeding planetary screw extruder extrusion system is composed of these two sections, the material by the planetary section extrusion, under the open mixer.  

Generally, the screw and barrel of the single screw section are provided with a water cooling circulation system, and the planetary barrel is provided with an oil heating circulation system.  Some used for PVC processing by the planet screw extrusion and single screw melt extrusion machine into the second stage of the single screw extruder is also provided with temperature control of the oil circulation loop. 

二、The Characteristics of Planetary Screw Extruder  

1. Streamline the flow channel without dead Angle.  Due to the self-sweeping effect between the planetary screw and the main screw and the barrel (the meshing teeth squeeze the material out of each other), it has a good self-cleaning ability.  

2. In the planetary section, the central screw and barrel are generally heated with circulating oil to control the temperature.  

3. Good dispersion mixing and distribution mixing performance, suitable for blending and filling modification.  

4. Material retention time is short.  

5. It has good exhaust function.  

6. Lower energy consumption.  

7. High production.  

8. Strong applicability 

三、The Application of Planetary Screw

1. Apply for PVC processing

A. Calender feeding: The calender production line usually produces PVC products. The process is that the materials premixed by the high-speed mixer are plasticized by the dense mixer, and then fed to the calender by the open mixer or melt feeding extruder.

B. A double stage extruder with a planetary screw extruder and a single screw extruder can be used for pelleting PVC.

2. Other applications.  

In addition to mainly used for PVC processing, planetary screw extruder can also be used to process other materials, such as PVS/ABS blending, processing powder coatings, processing epoxy resin, polyester, acrylic resins, polyurethane, chlorinated polyethylene.  It can also process thermosetting plastics, such as melamine, polymethyl ester resins and unsaturated resins.