The Study On Screw's Parametric CAD Of Twin-Screw Plastic Extruder

With the applications of plastic getting more extensive, the demand of plastic machine gets more, too. In recent years, it's one of the fastest growing trades with the increase ratio about 30 percent. The related statistic data show that more than 60 percent plastic products are processed by extruding, so the extrusion molding has been becoming the main processing method of polymeric materials. The plastic extruders in China are mainly single screw extruders with relatively mature technology, but the limited space to enhance capabilities limits its development. For the future, parallel axis twin-screw extruder is the main developing aspect in China and abroad. The screw is the most important part of extruder, as well as the key component of extrusion molding. A mass of practical examples show that the level of screw design impacts the output and quality of extrusion product greatly.Many researchers have been studying on twin-screw, but no one has discussed the machinery structure of twin-screw systematically and brought forward the idear of parametric design. This paper is novel and has its practical meaning to increase design level of plastic extruders, shorten produce period, impel plastic machine's development and upgrade plastic machine's competitive ability of our country.In this paper about twin-screw parametric CAD, the main researches are as follow:1. Do research on the co-rotating parallel axis fully intermeshing twin-screw from intermeshing principle, cross section curves, volume parameters, center distance and so on. The mathematical model of center distance, groove depth, pitch and other main design parameters of twin-screw is educed to make ready for the parametric design.2. The counter-rotating compact intermeshing twin-screw is researched detailedly from intermeshing principle, formula of cross section curves, C mould cavity volume parameter and main structure parameters. Then the infection of calendering effect on screw design is analysed and the mathematical relations of screw diameter, rotate speed and extruding quantity is educed.3. To conclude the main application areas of co-rotating parallel axis fully intermeshing and counter-rotating compact intermeshing twin-screw, then choose the most common uses as the design objective of parametric CAD.