Printing Hollow Tubes Using Digital Glass Forming

This article investigates printing hollow tubes using the digital glass forming process. A CO2 laser locally heats continuously fed glass tube feedstock so that it can be plastically deformed. This allows it to be bent and deposited onto a workpiece. The workpiece is positioned relative to the laser using precision four-axis computer numerical control stages. The loading on the laser-heated region is controlled by the stages as well as pneumatic pressure in the tube, which allows the printing complex shapes without the tube collapsing. The bending behavior of freestanding glass structures is examined, focusing on the geometric accuracy and temperature profile of the deformation zone as a function of the process parameters. The application of pneumatic pressure allows the control of the printed tube diameter. Several complex tube geometries deposited on the planar substrates as well as freestanding structures are demonstrated.