Effect of Structural Parameters on Melting Performance of Grooved Barrel Single-Screw Extruder

To address the mismatch between solid conveying efficiency and melting efficiency in grooved barrel single-screw extruders (SSEs), the effects of barrel groove and screw channel structural parameters on the melting start point and melting length were systematically investigated based on the groove-channel coupled melting (GCCM) theory. Three extruder configurations—smooth barrel, spiral-grooved IKV (Institut für Kunststoffverarbeitung), and GCCM—were designed and tested on a hydraulically driven clamshell barrel SSE platform with a screw diameter of 45 mm and a length-to-diameter ratio of 30:1. Low-density polyethylene (LDPE) grade 607 was used as the model material. The results demonstrate that increasing the barrel groove depth shifts both the melting start point and melting length downstream, whereas the groove width has negligible effects. A minimum melting start point is achieved at a groove pitch of 4D. At a screw speed of 30 r/min, the GCCM extruder equipped with a BARR barrier screw achieves a melting start point 24.0% earlier than the IKV extruder and a melting length shortened to 62.7% of the IKV value, representing reductions of 27–35% and 21–31% compared to reported barrier screw and Maddox screw melting lengths, respectively. The actual throughput reaches 93.7–95.7% of the theoretical solid conveying throughput, with specific energy consumption only 8.5% higher than the IKV extruder and throughput fluctuation reduced to 23.7%. Complete melting is achieved at a melting zone temperature of only 110 °C, confirming the dominant role of internal frictional heat. This study provides systematic experimental data and theoretical guidance for the structural optimization of grooved barrel SSEs.