| 摘要 |
Tapered conduit (12) having a smaller end and a larger end in transverse dimension including at least one longitudinal formation (65) characterised in that there is provided a pair of longitudinal deformations (60) each having a susbtantially uniform taper from end to end wherein each deformation (60) is located with said formation (65) interposed therebetween to facilitate interfitting of adjacent similar sections of the tapered conduit, which may be round or rectangular in cross section, with the smaller end of one section being insertable in the larger end of the other section. A method and apparatus for forming tapered conduit (12) including two sets (28, 35) of primary (36) and secondary (31) rollers and means for orienting (17) tubular shape conduit (12) to pass through the said sets (28, 35) of rollers (36, 31) in a predetermined configuration and means for causing relative movement between each primary (36) and secondary (31) roller to form a pair of longitudinal deformations (60) on the conduit (12) on either side of the formation (65). |
