Study On Screw Of Microstructure Injection Molding Machine

The widespread use of microstructure plastic products drove development and improvement of microstructure injection molding machine. From the perspective of plasticization of PC in microstructure injection molding machine, the effect of five parameters-flight height, the lead of the screw, flight clearance, the axial width of the flight’s top and the angle of the inclined plane-on melt temperature uniformity was investigated; furthermore, the parameters were optimized; besides, the metering section was designed and improved.The effect of parameters of metering section on melt temperature uniformity was studied by using the methods of orthogonal test and Polyflow simulation analysis. The results showed that the effect of flight clearance on melt temperature uniformity was the biggest, and then flight height, the angle of the inclined plane, the axial width of the flight’s top were in order, in comparison, the influence of the axial width of the flight’s top and the lead of the screw was smaller obviously.Using genetic algorithm, parameters of metering section were optimized based on mixing uniformity formulas. By contrasting the calculation results of mixing uniformity and plasticizing capacity using formulas in different linear velocities and back pressures, it was found that uniformities of optimized screw were raised by24%～31%and its plasticizing capacities increased by7%～8.5%. Furthermore, according to the simulation and contrastive analysis on axial melt temperature differences, radical melt temperature differences and plasticizing capacities of the two screws, this optimization method was feasible.To maintain good melt temperature uniformity and plasticizing capacity and weaken high shear stress, a new-type slotted split-flow screw was designed based on optimized screw. According to orthogonal design, optimal selection was conducted to the four parameters-slotted width, m, slotted cone angle and flight clearance, and the best project was obtained finally.Comparing the plasticizing capacities, shear stresses and melt temperature uniformities obtained by Polyflow simulation between original screw and new-type screw, it indicated:under the same process condition, the plasticizing capacities of new-type screw were slightly higher than that of original screw, while the other indexes had absolute advantages; when the linear velocities of new-type screw was20mm·s-1higher than that of original screw, plasticizing capacities as well as the others of new-type screw were better.