Rastogi Prasansha, Venner Cornelis H, Visser Claas Willem
Engineering Fluid Dynamics Group, Department of Thermal and Fluid Engineering, Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Polymers (Basel). 2022 Jul 16;14(14):2895. doi: 10.3390/polym14142895.
Direct Bubble Writing is a recent technique to print shape-stable 3-dimensional foams from streams of liquid bubbles. These bubbles are ejected from a core-shell nozzle, deposited on the build platform placed at a distance of approximately 10 cm below the nozzle, and photo-polymerized in situ. The bubbles are ejected diagonally, with a vertical velocity component equal to the ejection velocity and a horizontal velocity component equal to the motion of the printhead. Owing to the horizontal velocity component, a discrepancy exists between the nozzle trajectory and the location of the printed strand. This discrepancy can be substantial, as for high printhead velocities (500 mm/s) an offset of 8 mm (in radius) was measured. Here, we model and measure the deviation in bubble deposition location as a function of printhead velocity. The model is experimentally validated by the printing of foam patterns including a straight line, a circle, and sharp corners. The deposition offset is compensated by tuning the print path, enabling the printing of a circular path to the design specifications and printing of sharp corners with improved accuracy. These results are an essential step towards the Direct Bubble Writing of 3-dimensional polymer foam parts with high dimensional accuracy.
直接气泡书写是一种最新的技术，用于从液体气泡流中打印形状稳定的三维泡沫。这些气泡从核壳喷嘴喷出，沉积在放置在喷嘴下方约10厘米处的构建平台上，并在原位进行光聚合。气泡以对角线方向喷出，其垂直速度分量等于喷出速度，水平速度分量等于打印头的运动速度。由于水平速度分量，喷嘴轨迹与打印线条的位置之间存在差异。这种差异可能很大，例如对于高打印头速度（500毫米/秒），测量到的偏移量为8毫米（半径）。在此，我们对气泡沉积位置的偏差进行建模并测量其作为打印头速度的函数。该模型通过打印包括直线、圆形和尖角在内的泡沫图案进行了实验验证。通过调整打印路径来补偿沉积偏移，从而能够按照设计规格打印圆形路径并以更高的精度打印尖角。这些结果是朝着高精度三维聚合物泡沫部件的直接气泡书写迈出的重要一步。
