Investigations of the Elongational Deformation Induced by Pins in Pin-Barrel Cold-Feed Extruders

Abstract

This paper is a study on the elongational deformation induced by pins in pin-barrel cold-feed extruders. The mathematical model is established by using simple flow field, plate model, and Newton constitutive relation. It is proved that there is elongational deformation when the fluid bypasses the pin, and the elongational deformation is quantitatively calculated. The finite element method is used to simulate the flow field of the screw mixing section of the pin-barrel cold-feed extruder with different specifications. The velocity vector nephogram in the simulation results is analyzed by numerical analysis of elongational deformation and compared with the theoretical elongational deformation value. The results show that the simulated and theoretical values of elongational deformation are approximately consistent. The numerical analysis of the key factors affecting the elongational deformation shows that the elongational deformation will gradually increase with the increase of screw diameter. For the screw of the same specification, the increasing helical angle will reduce the elongational deformation, and the increasing rotational speed will linearly increase the elongational deformation in unit time. This study can be used to roughly estimate the elongational deformation induced by pins and establish the mixing theoretical model of the pin-barrel cold-feed extruder.