Planetary Screw BarrelFeatures And Applications
In recent years, some domestic enterprises to develop the planetary screw extruder extrusion system, by a main screw and a number of auxiliary screw composition. The main and auxiliary screw threads are imitated spiral bevel gears with the structure of the intermeshing, its conveying capacity and self-cleaning effect is very good, able to continuously feed, it is used as PVC products rolling production line preplasticization equipment, To replace the mixer or open mill to improve the working conditions. However, this kind of planetary extruder can not produce enough pressure on the material, it can not be used for product extrusion, need to be equipped with another extruder into a two-stage arrangement, as shown in Figure 1.
Planetary screw extruder has been abroad for nearly 60 years. More than 20 years ago with the introduction of China's rolling production of rigid PVC transparent film large complete sets of equipment into China. The planetary screw extruder has a very gentle plasticizing effect, the material is scattered evenly, only the lower energy, it is with the traditional rolling production line configuration of the mill, mixer and the early introduction of China's various twin-screw extruder Compared to show its clean, efficient, energy saving, production capacity, saving accessories, and accurate and efficient to join a variety of accessories, with the shortest possible time in accordance with the set temperature to complete the advantages of plastic, so by China's plastics industry's widespread concern The Planetary screw extruder features are:
1) the same amount of material in the case of extrusion, in the planetary screw extruder running time of 20 ~ 40s, while the ordinary single screw extruder to complete the plasticization of 40 ~ 70s, twin screw extruder for 30 ~ 60s The
2) Low energy consumption per unit extruder. Processing of hard PVC, planetary screw extruder energy consumption of 288kJ / kg, while the ordinary single screw extruder for 612kJ / kg, different rotation twin screw extruder 432kJ / kg.
3) Because the number of planetary rollers is large and the length is large, the total number of meshing rolls is very high (although the speed of the planetary screw extruder is generally not more than 60r / min), up to 300,000 times / min Greatly increased the amount of material kneading, extrusion, cutting and mixing.
4) Planetary screw extruder in a very short period of time to achieve the material kneading, extrusion, shear exchange contact surface area is very large, any existing hybrid system can not go beyond.
5) Planetary screw extruder is unique in that it can be in the barrel is not full of materials (rated capacity of 10% or more) in the case of good plastic processing. This feature can be easily applied to debugging production.
In the early 1990s, the core components of the domestic planetary screw extruder were successfully worked in Beijing. 1993 in Beijing to produce the first HT240 machine together in a large rolling line in the successful operation. After nearly 20 years of development, domestic models of the whole series of planetary screw extruder has become the number of domestic enterprises in the scale of the largest number of large and medium-sized production line preferred plastic equipment. And can provide planetary screw extruder machine has more than 10 domestic manufacturers, including Beijing-made star screw extruder series power from 75kW up to 450kw above the production span of each small 350 ~ 4500kg 12 models can be basic To meet the high-end market large and medium-sized rolling production line configuration requirements. Shanghai and central and southern production of the planetary screw extruder to meet the small and medium-sized rolling production line configuration requirements.
In recent years, Germany, Austria, Italy and other presses to produce power on the use of planetary screw extruder is not limited to PVC film market, represented by Germany, has extended the market to the following products:
1) rubber and elastomer curing device, the production capacity of 50kg ~ 6t per hour.
2) powder coating with paint production equipment, production capacity of 50kg ~ 4t per hour.
3) granulation system (modified functional materials, such as wood plastic), production capacity of 100kg ~ 5t per hour.
4) single and double-stage plasticizing device, the production capacity of 100kg ~ 8t per hour.
5) polyester film production line of plasticizing device.
6) food and drug mixing synthesis device, production capacity of 20kg ~ 1t per hour.
7) laboratory with extruder, according to customer requirements custom production line.
8) chemical work of the combination of endothermic reaction and exothermic reaction, drying and degassing, condensation reaction.
Planetary screw extruder construction
The extrusion system of this extruder is divided into two parts, the first part is the conventional single screw extruder feeding section and for the effective control of the amount of feeding and feeding silos to adapt to the mandatory feed (or feed material) System; the second part is installed in the feeding section of the discharge side of the planetary plasticization section, usually with flange to connect a paragraph or two. Planetary plasticizing section is the core part of the planetary screw extruder, mainly by the main screw, planetary screw and in the barrel on the circumferential surface of the exact processing of the same modulus, phase of the spiral angle of the meshing tooth combination (domestic said internal teeth set). The main screw from the speed motor by a special gear box through the feeding section of the screw to obtain power rotation. In the main screw around the rules are arranged with the rolling of the small diameter of the planetary screw, the number of screws with the planetary screw extruder nominal diameter changes, usually 7 to 18 different. The small screw is precisely engaged with the internal teeth on the inner wall of the barrel. When the extruder is running, the helical teeth of the main screw push the peripheral screw and rotate around it. The orbit of the inner gear is the tooth surface of the inner teeth. The small screw is therefore called a planetary screw. The composition of the extrusion plasticizing system called the planetary screw extruder.
The length of the planetary plasticizing section varies greatly depending on the enterprise standards and the requirements of national production and distribution. Usually each section of the length of about 400mm short, long up to 1000mm or so. An extruder with one or two planetary plasticizing stages is often used to produce a plastic film system for PVC diaphragms, with more than three planetary plasticizing sections configured to achieve complex functions.
When the main screw rotates, the planetary screw is driven to rotate. It is well known that when the gear rotates in the direction, the rotating planetary screw rotates in the axial direction to prevent it from spinning out of the axial direction. The high-strength, wear-resistant stop is provided at the discharge port die of the planetary plasticizing section Ring to ensure the reliability of the planet screw axial positioning.
The core part of the planetary screw extruder is a planetary screw, which is a gear with a maximum tooth width of 45 ° helix angle, when the main screw rotation, the planetary screw as the roll in the center of the screw and the inner teeth of the bilateral The roller on the tooth surface rolls like a roll that floats on the rolled material, in which the material is caught by the teeth of one of the planetary rolls, brought into the corresponding backlash and along the helical teeth The surface of the axial delivery, when pulled out into a thin layer and the retaining ring and its cutter layer and cut into small pieces.
This continuous process of continuous rolling out of the layer can achieve accurate temperature adjustment throughout the mixing process.
This is the planetary screw extruder (precisely the planetary roll extruder) to achieve the material mix soft and efficient and accurate temperature control, self-cleaning effect is the best, the least waste source.
The temperature regulation is achieved by the circulation medium of the center screw core and the inner tooth jacket.