| 摘要 |
PURPOSE:To offer an assembled hob for making hourglass worms which assures high precision and high efficiency as well as provides possibility to save the material to hob by constructing the hob in a form of assembled hob and by installing the secondary on the group of cutting edges corresponding to a lead of thread situated at the entrance side which works rather much. CONSTITUTION:This assembled hob is composed of the body, i.e. the central part, and rigns 2, 3 at both sides provided with a group of cutting edges each, corresponding to a lead of thread. These ring 2, 3 and body 1 have a hole with the same diameter and, at the end faces of every piece, key 5 or key seat 6 to engage each other is provided perpendicular to the hob axis X-X. Their relative positioning is determined by an arbor which shall fit to this front key and hole 4. No.2 cutter are used as cutting edges leading the rings 2, 3 which are due much and other types of cutters are used for cutting edges following these two and provided on the central part, body, which do not work much. According to this arrangement, in the case of wear only those at the rings on both ends be substituted. |
