| 摘要 |
Snapping unit (11) for heads of harvesting machines comprises a pair of counter-rotating snapping rolls (13a, 13b) and a support and motion transmitting unit (15) with which the snapping rolls are associated so as to cooperate with each other when placed into rotation around their longitudinal axis, each snapping roll comprising a body (17) where a cylindrical rear portion (17a) and a frustoconical front portion (17b) are defined, the side wall (19) of the body (17) being provided on its outer surface with longitudinal helical grooves (21) defining helical protrusions (23) ending in corresponding helical ridges (25) capable of penetrating the groove (21) defined between the helical ridges (25) of the adjacent roll during rotation of the two snapping rolls, wherein the helical grooves (21) and, correspondingly, the helical protrusions (23) and the respective helical ridges (25) have a pitch equal to or more than the total length of the corresponding roll (13a, 13b) and extend on at least part of the frustoconical portion (17b). |
