In manufacturing 3003 small tubes, impact extrusion was applied in order to obtain seamless tubes with high accuracy and high surface finish. In impact extrusion of such tubes, die damages are often observed. These da...In manufacturing 3003 small tubes, impact extrusion was applied in order to obtain seamless tubes with high accuracy and high surface finish. In impact extrusion of such tubes, die damages are often observed. These damages are related to process variables such as tools structure and temperature, extrusion ratio, initial billet temperature, characteristics of the extrusion speed and lubrication. It is economical and efficient to use FEM (finite element method) to simulate metal flow, stress, strain and temperature under different extrusion conditions. The simulation results are helpful to the investigation of die damages and the optimization of extrusion process parameters. [展开更多
This research explored replacing acrylic core-shell impact modifier （AIM） by silica fume to toughen PVC. 100%, 75%, 50% and 25% of AIM （8 phr） were substituted by silica fume in PVC respectively, and then processe...This research explored replacing acrylic core-shell impact modifier （AIM） by silica fume to toughen PVC. 100%, 75%, 50% and 25% of AIM （8 phr） were substituted by silica fume in PVC respectively, and then processed by dry blending and twin-screw extrusion. Severe silica fume agglomeration was observed by scanning electron microscope （SEM） in the PVC matrix when 8 phr pure silica fume was used and processed by screw speed of 20 rpm. Its tensile strength was thereby reduced by 38% comparing to unmodified PVC. The silica fume was successfully dispersed while the screw speed was slowed down to 10 rpm to give a stronger screw torque and a longer melt residential time in the extruder. The tensile strength was ’recovered’ to a level comparable to unmodified PVC. Impact test were performed on all formulations extruded at 10 rpm screw speed and synergetic toughening effect was found with 50% substitution and it had the impact strength that was comparable to 8 phr pure AIM toughened PVC.展开更多
文摘In manufacturing 3003 small tubes, impact extrusion was applied in order to obtain seamless tubes with high accuracy and high surface finish. In impact extrusion of such tubes, die damages are often observed. These damages are related to process variables such as tools structure and temperature, extrusion ratio, initial billet temperature, characteristics of the extrusion speed and lubrication. It is economical and efficient to use FEM (finite element method) to simulate metal flow, stress, strain and temperature under different extrusion conditions. The simulation results are helpful to the investigation of die damages and the optimization of extrusion process parameters. [
文摘This research explored replacing acrylic core-shell impact modifier （AIM） by silica fume to toughen PVC. 100%, 75%, 50% and 25% of AIM （8 phr） were substituted by silica fume in PVC respectively, and then processed by dry blending and twin-screw extrusion. Severe silica fume agglomeration was observed by scanning electron microscope （SEM） in the PVC matrix when 8 phr pure silica fume was used and processed by screw speed of 20 rpm. Its tensile strength was thereby reduced by 38% comparing to unmodified PVC. The silica fume was successfully dispersed while the screw speed was slowed down to 10 rpm to give a stronger screw torque and a longer melt residential time in the extruder. The tensile strength was ’recovered’ to a level comparable to unmodified PVC. Impact test were performed on all formulations extruded at 10 rpm screw speed and synergetic toughening effect was found with 50% substitution and it had the impact strength that was comparable to 8 phr pure AIM toughened PVC.
