Experimental Parameter Identification for the Bending Based Preforming of Thermoplastic UD-Tape

Abstract

The combination of different types of plastics can be advantageous to obtain a good component performance at a reasonable price. For this, a compromise between mechanical properties and cheap manufacturing has to be found. In the research project GRK2078, the manufacturing of hybrid components consisting of long fiber reinforced thermoplastics (LFT) and unidirectional endless fiber reinforced material (UD-tapes) is researched. The LFT is the main constituent of the components. Local UD-tape reinforcements are added in areas with high load for a large effect or low geometric complexity to minimize preforming effort. To keep the cost low, a novel preforming process for the UD-tapes is in development at wbk Institute of Production Science. The aim is to enable the shape flexible, tool less forming of UD-tapes. To obtain this, the process is based on sequential bending of the UD-tape on several positions along its longitudinal axis during handling operations. To conduct the process, a supply unit and an industrial robot with a gripper with integrated heating devices are used. In this paper, the experimental examination of the process and the identification of suitable parameters on the shape of the preform are presented. The main influencing factors are the type of UD-tape, the heating of the tape and the movement of the robot. The processes are conducted with PA and PP carbon fiber tapes. The process quality with contact and radiation heating are compared and the respective heating duration is identified. For the robot movement, a kinematic description of the process is derived and compared to a circular bending movement. With the identified parameters, the process can be conducted reliably. The resulting accuracy limit and the process time with these parameters are described in this paper.KeywordsPreformingHandlingUD-tapeBendingKinematics