Optimal Spreading of Fiber Bundles through an Impregnation Device with Convex Rolls

摘要

There is an increasing demand for thermoplastic granules containing long fibers which can be used in an injection or compression molding process. Granules are produced in a pultrusion process, where a fiber bundle is pulled through a bath of thermoplastic material and chopped to the desired length. However, the high viscosity of thermoplastic material obstructs the impregnation of fiber bundles. This problem is overcome by a specially designed impregnation device which has powered rolls of convex and tapered shape. The current prototype impregnation device is based on good workmanship, but the design did not arise from a geometrical study on the optimal design with respect to the impregnation quality. In this paper, the development of a mathematical model of the impregnation device for the analysis of geodesic filament trajectories over convex rolls of arbitrary geometry and location is described. The impregnation quality is determined by the contact surface over the rolls of a fiber bundle, which is represented by a number of filament trajectories. In future, this model will be used in an optimization procedure, where the objective is to determine the optimal geometry with respect to impregnation quality.