| 摘要 |
1,174,640. Making tubes; rolling tubes. CALUMET & HECLA CORP. 5 Dec., 1967 [26 June, 1967], No. 55225/67. Headings B3A and B3M. [Also in Division F4] External helical fins 48 and internal helically extending ribs are formed integrally on a tube T by applying rolling pressure to sets of fin forming rolls 42, the tube T being simultaneously advanced over a supporting cylindrical mandrel 40. Each set of rolls 42 comprises an arbor 44 carrying a plurality of discs 46 together with a further disc 52 of larger diameter located beyond the end of the mandrel 40 and which forms the internal helical ribs. Alternatively, as shown in Fig. 5, a rolling tool 60 comprising an arbor 62 carrying spaced discs 64 is used to form the external helical fins 70 and grooves 68, and a separate tool 76 provided with a helical rib 78 engages in one of the previously formed grooves to deepen it so forming the inwardly projecting helical rib 74. |
