Robot-assisted laser additive manufacturing for high-strength/low-porosity continuous fiber-reinforced thermoplastic composites

Additive manufacturing (AM) of continuous fiber-reinforced thermoplastic composites (CFRTPCs) has become a hot area for both academia and industry. In this paper, a robot-assisted laser additive manufacturing (RLAM) technique is proposed, which involves utilizing a laser beam to heat the filament to a semi-molten state, followed by compacting it with a roller and bonding it layer by layer to create densely structured components. Firstly, an integrated framework of hardware, software, and control systems is presented. Then, the relationship between the processing parameters and the properties of the final specimens was examined. Finally, a process strategy was proposed to improve the forming accuracy. Due to the effective impregnation of continuous carbon fibers, the printed CFRTPCs using the LRAM process exhibit comparatively low porosity and superior mechanical performance. Specifically, the flexural strength, flexural modulus, and interlayer shear strength reached 584 MPa, 43.7 GPa, and 28.0 MPa, respectively. The prepared specimens boast a porosity of 0.19%, approaching levels achieved through autoclave processes. In addition, it was found that the dynamic offset of the yaw axis could be utilized to correct the deviation of the actual forming path due to the pultrusion force, thus making the position of the towpreg under the rollers controllable and improving the accuracy of the parts. This new method combines the advantages of industrial robotics and laser&roller-based continuous fiber additive manufacturing processes to enable high-performance additively manufactured large and complex CFRTPCs, which shows great potential for printing lightweight structures in the rail transit and aerospace industries.