A Visualization Study Of Single Extruder

In order to learn more about the changes of material in extruder, a new type of visualisationsingle-screw extruder based on former machine was designed and manutfatured, in which thevariances of maize and rice can be seen clearly on line: The material transported in particle at thebeginning, then was delivered ahead and compacted to the plunger. With the fierce compressing,friction and high shear, the plunger gradually softened and melted. In the high pressure andtemperature such extrudate would expel from the extruder die to yield the final product. In thatprocess the pressure decreased most rapidly and the water in the extrudate vaporized. There are alots of small hole in the extrudate.In the base of visualisation experiments, three types of transportation models of material inextruder were established: particle transportation model, plunger transportation model and meltingmass transportation model.With the method of the quadratic orthogonal retation combination design, five samples werecollected at five segments of A, B, C, D and E along the screw to study the regularity of the contentof reducing sugar along the screw. Result showed that: It is increasing from A to B and decreasingfrom B to C, then is changeless from C to D and increasing from D to E.Simultaneously, with the software of REDA to analysis the influence of the system parameters tothe reducing sugar of rice. Result showed that: 1. With the increasing of the screw velocity, thecontent of reducing sugar in segment B and C is decreasing and it is reverse in segment D, and E isdecreasing firstly and then increasing. 2. With the increasing of the moisture content, the content ofreducing sugar in segment B is increasing firstly and then decreasing, it is reverse in segment C andD, and it is increasing in segment E. 3. With the increasing of the barrel temperature, the content ofreducing sugar in segment B is increasing firstly and then decreasing and it is reverse in segment C,and it is increasing in segment D and E.With the method of the quadratic orthogonal retation combination design, the influence of theextrusion system parameters—barrel temperature, screw velocity and moisture content to the power,pressure and productivity of the extruder and swelling degree of extrudate was studied. Resultshowed that: 1. With the increasing of the screw velocity, the productivity and pressure of theextruder are increasing, but the power is to be decreased and the change of the swelling degree isnot obvious. 2. With the increasing of the moisture content, the productivity is increasing and thepressure and swelling degree are decreasing, but the power of the extruder is increasing firstly andthen decreasing. 3. With the increasing of the barrel temperature, the power and the swelling degree are decreasing firstly and then increasing and the productivity is reverse, the change of the pressureis not obvious.Through this study physical and mathematical model were researched, it provided the theoryand the scientific evidence for designing extrusion system.