To address the issue of fabrication difficulties for rigid sandwich composite preforms caused by frictioninduced breakage of carbon fiber threads during stitching against the core layer (polyurethane foam)

this study proposed a high-efficiency preform stitching forming process with synchronous pre-punching and stitching based on the improved tufting stitching process

aiming to enhance stitching forming efficiency. A prototype stitching forming system for rigid sandwich composite preforms with pre-punching functionality was developed. The system employed a PLC as the control unit and a touchscreen as the human–machine interface. Stitching experiments were conducted using the developed prototype. Experimental results indicate that the integration of the pre-punching process effectively prevents the breakage of carbon fiber threads. During 450 stitching processes

stable carbon fiber loops are formed at the bottom of the preform

and the top stitch positions are accurate. Compared with the preset stitching spacing

the relative error of stitching row spacing is less than 2%

and that of stitching column spacing is less than 4%. No loose delamination occurs among the components of the molded preform. The developed preform stitching forming system enables the efficient stitching forming of rigid sandwich composite preforms.