Design And Construction Principle Of Screw In Plastic Pipe Production Line
Design and Construction Principle of Screw in Plastic Pipe Production Line
Plastic Pipe Production Line is the main component of the screw barrel, plastic plastic, extrusion, molding also plays an extremely important role, so the rational use of screw structure and parameters is to obtain the ideal product quality and production of important links. In order to meet the needs of different plastic processing, there are many kinds of screw structure, there are three common: gradient type (isometric), gradient type (equidistant level), mutant type, torpedo head type and so on.
The selection of the screw structure of the Plastic Pipe Production Line is mainly based on the physical properties of the plastic and the technical specifications of the extruder.
(1) the softening of non-crystalline polymer is completed in a relatively wide temperature, the general use of equidistant gradient screw. Crystalline polymer melting temperature range is relatively narrow, generally use equidistant mutant screw.
(2) in the small Plastic Pipe Production Line, such as φ45 extruder screw is not equal to the depth of the whole thread type, the length of the screw is relatively small, mainly for the extrusion of small cross-section of the insulation and jacket , Extrusion speed faster.
(3) medium-sized screw with equidistant and thread depth gradient of the whole thread type, its length and diameter ratio than the small screw larger, the pitch of the thread from the root from shallow to deep. Thread at the end of the thread deep, the root of the thread is shallow, so that the amount of plastic extrusion, without affecting the screw strength, extrusion speed, plastic plastic good, is generally small and medium-sized extruder production insulation and protection The ideal screw of the jacket.
Plastic Pipe Production Line Feeding area: fixed screw groove of the groove deep, its function is responsible for preheating and plastic solid conveying and pushing. It must be ensured that the plastic begins to melt at the end of the feed section - that is, to preheat to the melting point. (PA, POM, PE, PP, CA) of about 48 ~ 58% L, plus glassy nature of about 45 ~ 55% of the non-crystalline (AS, ABS, ps) L.
Plastic Pipe Production Line compression area: tapered screw screw groove deep, its function for the plastic raw materials melting, mixing, shear compression and pressurized exhaust. Plastic in this paragraph will be completely dissolved, the volume will be reduced, so the design of the degree of compression is very important. (PA, POM, PE, PP, CA) of about 22 ~ 32% L, plus about 28 ~ 40% L of glass, , Heat sensitivity (PVC) 100% L.
Plastic Pipe Production Line metering area: screw screw groove fixed groove deep, the main function of mixing, melt transport, measurement, but also must provide sufficient pressure to maintain the uniform temperature of molten rubber and stable flow of molten plastic. (PA, POM, PE, PP, CA, etc.) of about 48 ~ 58% L, plus glass of about 45 ~ 55% of the total length of: non-crystalline (AS, ABS, PS) L.
Although the Plastic Pipe Production Line screw can be functional or geometric appearance to distinguish, but the actual plasticization process, the overlapping function of each section, it is difficult to distinguish between the interval. The study of plastic screw, nothing more than want to: improve the role of cutting and mixing, improved even mixing, improve the plasticizing capacity, improve the melt temperature uniformity. When the depth of the feed section deepened the greater the amount of deep, but the screw required greater torque; feed section of the tooth depth is too shallow, the amount of delivery is not enough, compression ratio is insufficient. When the measurement section of the tooth is too deep, the compression ratio is insufficient, the required feeding power is larger; too shallow when too easy to burn. The average tooth depth is about 0.03 to 0.07 times the screw diameter. Therefore, plastic plastic screw has the function of conveying, melting, kneading, compressing and measuring, and plays a very important role in plasticizing quality.