Experimental research on performance of different knotter driving pulleys

As a key part of the knotter, knotter driving pulley is the total power source of the knotter used on briquetters. The parameters of knotter driving pulley are main factors for affecting the knotting rate. Two kinds of CTRC knotters (CTRC_I and CTRC_II) were designed to solve the present knotting problems, which including mis-clipping, mis-cutting and mis-tripping off the twine. CTRC_I was composed of CTRC basal part and reversed “9” type cam block, while CTRC_II was composed of CTRC basal part and arc-tangent type cam block. The comparison was carried out among CTRC_I, CTRC_II and New Holland knotter driving pulleys indoor. The results showed that the stable knotting rate of CTRC_I pulley (90.0%) was significant higher than that of New Holland (83.5%) and CTRC_II (65.0%) types of pulleys. The best stable knotting rate was obtained under three combinations: New Holland with sisal twine, CTRC_I with polypropylene twine and CTRC_I with sisal twine and was 22.7%~53.5% higher than the other three combinations. During the experiments, mean maximum pull tension was got by the CTRC_II type pulley, while the minimum pull tension was got by the CTRC_I type pulley. At last, the knot quality was the highest for CTRC_I pulley while the twine dosage was also largest for it in comparison with the CTRC_II and New Holland pulleys. Meanwhile, the twine dosage was the largest at 70 r/min (99.5 mm) and smallest at 40 r/min (94.8 mm). Finally, the knotting performance of CTRC_I and New Holland pulleys were proved to be better than CTRC_II pulley by comprehensive benefit analysis through combining the methods of analytic hierarchy process and effect coefficient. Combination of the CTRC_I pulley and polypropylene rope was the best operating mode among the six different combinations.